U.S. patent application number 10/128546 was filed with the patent office on 2003-04-03 for pneumatic tire.
This patent application is currently assigned to The Yokohama Rubber Co., Ltd.. Invention is credited to Hashimura, Yoshiaki, Higuchi, Tadashi, Kanenari, Daisuke, Shida, Zenichiro.
Application Number | 20030062106 10/128546 |
Document ID | / |
Family ID | 27571649 |
Filed Date | 2003-04-03 |
United States Patent
Application |
20030062106 |
Kind Code |
A1 |
Kanenari, Daisuke ; et
al. |
April 3, 2003 |
Pneumatic tire
Abstract
A pneumatic tire constituting part or all of the part members
constituting the pneumatic tire by a rubber composition containing,
based on a total 100 parts by weight of a rubber containing at
least 70 parts by weight of an ethylenic unsaturated
nitrile-conjugated diene-based highly saturated rubber having a
content of conjugated diene units of not more than 30 percent by
weight, 0 to 120 parts by weight of zinc methacrylate and 0 to 60
parts by weight of carbon black and having a total formulations of
zinc methacrylate and carbon black of 10 to 120 parts by weight,
and providing, between the above part members and the adjoining
diene-based rubber layer, a bonding rubber layer comprising of a
rubber composition containing, based on a total 100 parts by weight
of a predetermined diene-based rubber and acrylonitrile butadiene
copolymer rubber, 5 to 80 parts by weight of a predetermined
aromatic petroleum resin.
Inventors: |
Kanenari, Daisuke;
(Hiratsuka-shi, JP) ; Hashimura, Yoshiaki;
(Hiratsuka-shi, JP) ; Shida, Zenichiro;
(Hiratsuka-shi, JP) ; Higuchi, Tadashi;
(Hiratsuka-shi, JP) |
Correspondence
Address: |
ARENT FOX KINTNER PLOTKIN & KAHN
1050 CONNECTICUT AVENUE, N.W.
SUITE 400
WASHINGTON
DC
20036
US
|
Assignee: |
The Yokohama Rubber Co.,
Ltd.
|
Family ID: |
27571649 |
Appl. No.: |
10/128546 |
Filed: |
April 24, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10128546 |
Apr 24, 2002 |
|
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09297076 |
May 3, 1999 |
|
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6397913 |
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09297076 |
May 3, 1999 |
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PCT/JP98/04376 |
Sep 29, 1998 |
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Current U.S.
Class: |
152/517 ;
152/524; 152/555 |
Current CPC
Class: |
C08L 9/02 20130101; B60C
1/0025 20130101; B60C 1/00 20130101; B60C 1/0016 20130101; C08L
21/00 20130101; B60C 5/12 20130101; B60C 17/00 20130101; C08K 3/04
20130101; C08K 5/098 20130101; C08L 7/00 20130101; B60C 1/0008
20130101; C08L 9/00 20130101; B60C 15/0607 20130101; Y10T 152/10864
20150115; C08L 15/005 20130101; B60C 15/06 20130101; B60C 11/005
20130101; C08L 9/06 20130101; Y10S 152/12 20130101; C08K 5/098
20130101; C08L 15/005 20130101; C08L 21/00 20130101; C08L 2666/06
20130101; C08L 21/00 20130101; C08L 2666/08 20130101; C08L 21/00
20130101; C08K 3/04 20130101; C08K 5/098 20130101; C08L 15/005
20130101; C08L 9/06 20130101; C08K 3/04 20130101; C08K 5/098
20130101; C08L 7/00 20130101; C08L 15/005 20130101; C08L 7/00
20130101; C08K 3/04 20130101; C08K 5/098 20130101; C08L 9/00
20130101; C08L 15/005 20130101; C08L 7/00 20130101; C08K 3/04
20130101; C08K 5/098 20130101; C08L 9/02 20130101; C08L 9/02
20130101; C08K 3/04 20130101; C08K 5/098 20130101; C08L 7/00
20130101; C08L 9/00 20130101; C08K 3/04 20130101; C08K 5/098
20130101; C08L 7/00 20130101 |
Class at
Publication: |
152/517 ;
152/524; 152/555 |
International
Class: |
B60C 017/00; B60C
017/04 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 29, 1997 |
JP |
9-264245 |
Oct 13, 1997 |
JP |
9-278959 |
Oct 15, 1997 |
JP |
9-281985 |
Oct 21, 1997 |
JP |
9-288661 |
Oct 23, 1997 |
JP |
9-291025 |
Oct 24, 1997 |
JP |
9-292959 |
Nov 18, 1997 |
JP |
9-316980 |
Jan 20, 1998 |
JP |
10-8920 |
Claims
1. A pneumatic tire providing a rubber composition containing,
based on a total 100 parts by weight of a rubber containing 70 to
100 parts by weight of an ethylenic unsaturated nitrile-conjugated
diene-based highly saturated copolymer rubber having a content of
conjugated diene units of not more than 30 percent by weight, 40 to
120 parts by weight of zinc methacrylate, containing no carbon
black or containing not more than 40 parts by weight of the same,
and having a total of formulations of zinc methacrylate and carbon
black of not more than 120 parts by weight as the reinforcing
rubber layer of the bead portion at least at part of a bead filler,
and/or providing it as an auxiliary bead filler at the outside of
the axial direction of the carcass wrapping layer, and bonding with
the adjoining rubber layer through a bonding rubber layer
containing, based on a total 100 parts by weight of (A) at least
one type of diene-based rubber selected from the group consisting
of a natural rubber, polyisoprene rubber, polybutadiene rubber, and
conjugated diene-aromatic vinyl copolymer rubber and (B) an
acrylonitrile-butadiene copolymer rubber, (C) 5 to 80 parts by
weight of an aromatic petroleum resin having an average molecular
weight of 300 to 1500, a softening point of 50 to 160.degree. C.,
and an iodine adsorption value of at least 20 g/100 g.
2. A pneumatic tire as set forth in claim 1, wherein the thickness
of the bonding rubber layer is 0.1 to 2.0 mm.
3. A pneumatic tire as set forth in claim 1, wherein the (A)
diene-based rubber and (B) acrylonitrile-butadiene copolymer rubber
contained in the bonding rubber layer have a ratio by weight in the
range of A:B=10:90 to 90:10.
4. A pneumatic tire as set forth in claim 1, wherein the bonding
rubber layer further contains at least one co-cross-linking agent
selected from the group consisting of a methacrylic acid higher
ester, triallyl isocyanurate, metal salt of methacrylic acid or
acrylic acid, diallyl phthalate ester, and 1,2-polybutadiene, and
is cross-linked by an organic peroxide.
5. A pneumatic tire providing at least at part of the bead toe
portion a rubber composition containing 70 to 100 parts by weight
of an ethylenic unsaturated nitrile-conjugated diene-based highly
saturated rubber having a content or conjugated diene units of not
more than 30 percent by weight and containing 20 to 120 parts by
weight of zinc methacrylate.
6. A pneumatic tire as set forth in claim 5, having a rubber
composition of the bead toe portion further containing not more
than 40 parts by weight of carbon black and having a total of
formulations of zinc methacrylate and carbon black of not more than
120 parts by weight.
7. A pneumatic tire as set forth in claim 5, bonding the rubber
members of the bead toe portion with the adjoining rubber layers
through a bonding rubber layer comprised of a rubber composition
containing, based on a total 100 parts by weight of (A) at least
one type of diene-based rubber selected from the group consisting
of a natural rubber, polyisoprene rubber, polybutadiene rubber, and
conjugated diene-aromatic vinyl copolymer rubber and (B) an
acrylonitrile-butadiene copolymer rubber, (C) 5 to 80 parts by
weight of an aromatic petroleum resin having an average molecular
weight of 300 to 1500, a softening point of 50 to 160.degree. C.,
and an iodine adsorption value of at least 20 g/l 100 g.
8. A pneumatic tire as set forth in claim 7, wherein the ratio of
weight (A)/(B) of the component (A) and component (B) in the
bonding rubber layer is 90/10 to 10/90.
9. A pneumatic tire as set forth in claim 7, wherein the thickness
of the bonding rubber layer is 0.1 to 1.5 mm.
10. A pneumatic tire as set forth in claim 7, wherein the bonding
rubber layer further contains at least one co-cross-linking agent
selected from the group consisting of a methacrylic acid higher
ester, triallyl isocyanurate, metal salt of methacrylic acid or
acrylic acid, diallyl phthalate ester, and 1,2-polybutadiene, and
is cross-linked by an organic peroxide.
Description
TECHNICAL FIELD
[0001] The present invention relates to a pneumatic tire, more
particularly relates to a pneumatic tire using a rubber containing
a specific hydrogenated NBR (that is, "a rubber composition
containing, based on a total 100 parts by weight of rubber
containing at least 40 parts by weight of an ethylenic unsaturated
nitrile-conjugated diene-based highly saturated rubber having a
content of conjugated diene units of not more than 30 percent, 0 to
120 parts by weight of zinc methacrylate and 0 to 60 parts by
weight of carbon black and having a total amount of formulations of
zinc methacrylate and carbon black of 10 to 120 parts by weight")
for part or all of the tire.
BACKGROUND ART
[0002] Known in the art is the use of hydrogenated NBR for tires
etc., making use of the fact that vulcanized formulations of this
with a zinc compound, methacrylic acid, and organic peroxide have
extremely high strength characteristics (Japanese Unexamined Patent
Publication (Kokai) No. 1-306443). There is the problem, however,
that such hydrogenated NBR compositions are generally extremely
difficult to bond with general purpose rubbers. Techniques are also
being developed for bonding general purpose rubbers for tires and
such members through a specific bonding layer to solve the problem
of bonding (Japanese Unexamined Patent Publication (Kokai) No.
5-185805). Even with this method, however, the bonding force with
the adjoining rubber is not sufficient. When applied to a tire, not
only does the durability fall, but also, since two bonding layers
are needed, there is the problem that the productivity of the tire
worsens.
DISCLOSURE OF THE INVENTION
[0003] Therefore, an object of the present invention is to provide
a pneumatic tire reducing the weight of the tire, lightening the
rolling resistance, and improving the durability, abrasion
resistance, cut resistance, and driving stability by constituting
part or all of the part members in a tire by a rubber containing a
specific hydrogenated NBR or by using a specific bonding rubber
layer for the bonding layer between such part members and parts
comprised of other general purpose rubbers when using the rubber
containing a specific hydrogenated NBR for part of the part members
and not requiring the inner layer required in the past due to the
superior air barrier property of the hydrogenated NBR. Another
object of the present invention is to provide a pneumatic tire
using such a rubber containing a hydrogenated NBR as a reinforcing
layer for part of the inside and outside layers of the tire or
using it as a white or colored decorative member for the outer
surface of the tire.
[0004] According to a first aspect of the present invention, an
object of the present invention is the provision of a pneumatic
tire which can strikingly improve the abrasion resistance and
rolling resistance or improve the driving stability feeling and
lighten the weight without reducing the high speed durability by
applying a specific hydrogenated NBR rubber composition including
the rubber containing a hydrogenated NBR and zinc methacrylate
and/or carbon black for the members of the cap tread and/or under
tread of the tire and further by using a specific bonding layer to
strongly bond the cap tread and adjoining under tread or belt layer
or the under tread and the adjoining rubber layer.
[0005] According to the present invention, there is provided a
pneumatic tire having a cap tread which is comprised of a rubber
composition containing, based on a total 100 parts by weight of
rubber containing at least 70 parts by weight of hydrogenated NBR,
0 to 80 parts by weight of zinc methacrylate and 0 to 40 parts by
weight of carbon black and having a total of the formulations of
zinc methacrylate and carbon black of 10 to 120 parts by weight,
and providing between the cap tread and the adjoining rubber layer
(normally an under tread layer or belt layer) a bonding rubber
layer comprised of a rubber composition containing, based on a
total 100 parts by weight of (A) at least one type of diene-based
rubber selected from the group consisting of a natural rubber,
polyisoprene rubber, polybutadiene rubber, and conjugated
diene-aromatic vinyl copolymer rubber and (B) an
acrylonitrile-butadiene copolymer rubber, (C) 5 to 80 parts by
weight of an aromatic petroleum resin having an average molecular
weight of 300 to 1500, a softening point of 50 to 160.degree. C.,
and an iodine adsorption value of at least 20 g/100 g.
[0006] Further, according to the present invention, there is
provided a pneumatic tire inserting between a cap tread and belt
layer an under tread comprised of a rubber composition containing,
based on a total 100 parts by weight of rubber containing at least
40 parts by weight of a hydrogenated NBR, 0 to 120 parts by weight
of zinc methacrylate and 0 to 40 parts by weight of carbon black
and having a total of the formulations of zinc methacrylate and
carbon black of 10 to 120 parts by weight, and providing between
the under tread and adjoining rubber layer a bonding rubber layer
comprised of a rubber composition containing, based on a total 100
parts by weight of (A) at least one type of diene-based rubber
selected from the group consisting of a natural rubber,
polyisoprene rubber, polybutadiene rubber, and conjugated
diene-aromatic vinyl copolymer rubber and (B) an
acrylonitrile-butadiene copolymer rubber, (C) 5 to 80 parts by
weight of an aromatic petroleum resin having an average molecular
weight of 300 to 1500, a softening point of 50 to 160.degree. C.,
and an iodine adsorption value of at least 20 g/100 g.
[0007] Further, according to the present invention, there is
provided a pneumatic tire having, at a layer under a cap tread of a
hydrogenated NBR rubber composition comprised of the composition of
said cap tread, an under tread of a hydrogenated NBR rubber
composition comprised of the composition of the under tread and
having, between the under tread and the adjoining rubber layer, a
bonding layer of a rubber composition comprised of the composition
of the bonding rubber.
[0008] Further, according to the present invention, there is
provided a pneumatic tire characterized in that a thickness of the
bonding rubber layer positioned between the cap tread and the
adjoining rubber layer is 0.1 to 4 mm; the thickness of the bonding
layer positioned between the under tread and the adjoining rubber
layer is 0.1 to 0.5 mm; the ratio of weight (A)/(B) of the
component (A) and component (B) in the bonding rubber layer is
90/10 to 10/90; and the bonding rubber layer further contains at
least one co-cross-linking agent selected from the group consisting
of a methacrylic acid higher ester, triallyl isocyanurate, metal
salt of methacrylic acid or acrylic acid, diallyl phthalate ester,
and 1,2-polybutadiene and is cross-linked by an organic
peroxide.
[0009] Further, according to a second aspect of the present
invention, an object of the present invention is to provide a
pneumatic tire which improves the run flat property by constituting
a crescent sectional-shaped reinforcing liner inserted between a
carcass layer of a side wall portion and inner liner layer by a
specific rubber material and which strongly bonds the reinforcing
liner and the adjoining rubber layer through a specific bonding
rubber layer comprised of one layer.
[0010] According to the present invention, there is provided a
pneumatic tire having at a side wall portion a crescent
sectional-shape reinforcing liner layer comprised of a rubber
composition containing, based on a total 100 parts by weight of a
rubber containing 70 to 100 parts by weight of an ethylenic
unsaturated nitrile-conjugated diene-based highly saturated
copolymer rubber having a content of conjugated diene units of at
least 30 percent by weight, 20 to 120 parts by weight of zinc
methacrylate, containing no carbon black or not more than 40 parts
by weight of the same, and having a total of formulations of zinc
methacrylate and carbon black of not more than 120 parts by weight
and bonding with an adjoining rubber layer through a bonding rubber
layer containing, based on a total 100 parts by weight of (A) at
least one type of diene-based rubber selected from the group
consisting of a natural rubber, polyisoprene rubber, polybutadiene
rubber, and conjugated diene-aromatic vinyl copolymer rubber and
(B) an acrylonitrile-butadiene copolymer rubber, (C) 5 to 80 parts
by weight of an aromatic petroleum resin having an average
molecular weight of 300 to 1500, a softening point of 50 to
160.degree. C., and an iodine adsorption value of at least 20 g/100
g.
[0011] Further, according to the present invention, there is
provided a pneumatic tire characterized in that a thickness of the
bonding rubber layer is 0.1 to 2.0 mm; the ratio of weight of the
(A) diene-based rubber and (B) acrylonitrile-butadiene copolymer
rubber contained in the bonding rubber layer is A:B=10:90 to 90:10;
and the bonding rubber layer further contains at least one
co-cross-linking agent selected from the group consisting of a
methacrylic acid higher ester, triallyl isocyanurate, metal salt of
methacrylic acid or acrylic acid, diallyl phthalate ester, and
1,2-polybutadiene and is cross-linked by an organic peroxide.
[0012] Further, according to a third aspect of the present
invention, an object of the present invention is to provide a tire
improved in durability and improved in the driving stability since
it becomes possible to increase the rigidity of a side wall portion
without reducing the durability of the reinforcing rubber member of
the bead portion and without increasing the tire mass and it
becomes possible to bond the members strongly to the adjoining
rubber layers by using a hydrogenated NBR composition containing a
specific hydrogenated NBR and zinc methacrylate for the reinforcing
rubber member of the bead portion and using a bonding rubber
composition comprised of a specific diene-based rubber, NBR, and
aromatic petroleum resin for the bonding rubber layer.
[0013] According to the present invention, there is provided a tire
providing a rubber composition containing, based on a total 100
parts by weight of a rubber containing 70 to 100 parts by weight of
an ethylenic unsaturated nitrile-conjugated diene-based highly
saturated copolymer rubber having a content of conjugated diene
units of not more than 30 percent by weight, 40 to 120 parts by
weight of zinc methacrylate, containing no carbon black or
containing not more than 40 parts by weight of the same, and having
a total of formulations of zinc methacrylate and carbon black of
not more than 120 parts by weight as the reinforcing rubber layer
of the bead portion at least at part of a bead filler and/or
providing it as a reinforcing bead filler at the outside of the
axial direction of the carcass turn up layer, and bonding with the
adjoining rubber layer through a bonding rubber layer containing,
based on a total 100 parts by weight of (A) at least one type of
diene-based rubber selected from the group consisting of a natural
rubber, polyisoprene rubber, polybutadiene rubber, and conjugated
diene-aromatic vinyl copolymer rubber and (B) an
acrylonitrile-butadiene copolymer rubber, (C) 5 to 80 parts by
weight of an aromatic petroleum resin having an average molecular
weight of 300 to 1500, a softening point of 50 to 160.degree. C.,
and an iodine adsorption value of at least 20 g/100 g.
[0014] Further, according to the present invention, there is
provided a tire characterized in that a thickness of the bonding
rubber layer is 0.1 to 2.0 mm; the (A) diene-based rubber and (B)
acrylonitrile-butadiene copolymer rubber contained in the bonding
rubber layer have a ratio by weight in the range of A:B=10:90 to
90:10; and the bonding rubber layer further contains at least one
co-cross-linking agent selected from the group consisting of a
methacrylic acid higher ester, triallyl isocyanurate, metal salt of
methacrylic acid or acrylic acid, diallyl phthalate ester, and
1,2-polybutadiene and is cross-linked by an organic peroxide.
[0015] Further, according to a fourth aspect of the present
invention, an object of the present invention is, taking note of
the characteristic of hydrogenated NBR of having a higher rigidity
and lower tans than general purpose rubber, being superior in heat
resistance, weather resistance, and abrasion resistance, and having
a low unvulcanized viscosity contrary to its hardness, to use a
rubber composition containing a specific hydrogenated NBR and zinc
methacrylate and/or carbon black for the carcass coat of a
pneumatic tire, and thereby has as its object to provide a
pneumatic tire comprised of a rubber which exhibits a high strength
with a reduction in the amount of use of carbon or without
formulation of the same, has an extremely low tan.delta., and can
reduce the rolling resistance of the tire by use of this for the
carcass coat, can further improve the driving stability, and, since
the hydrogenated NBR is also superior in air barrier property,
enables elimination of the inner liner (air barrier layer) and a
major reduction in weight when used for the carcass, and further
uses a rubber bonding layer of a specific composition between the
carcass coat and the adjoining rubber and thereby improves the
bonding force and also increases the productivity.
[0016] According to the present invention, there is provided a
pneumatic tire covering the reinforcing cord by a rubber
composition containing, based on a total 100 parts by weight of a
rubber containing at least 70 parts by weight of an ethylenic
unsaturated nitrile-conjugated diene-based highly saturated rubber
(hydrogenated NBR) having a content of conjugated diene units of
not more than 30 percent by weight, 0 to 90 parts by weight of zinc
methacrylate and 0 to 40 parts by weight of carbon black and having
a total of formulations of zinc methacrylate and carbon black of 10
to 90 parts by weight and further using at least one carcass layer
of 1.1 d.ltoreq.T.ltoreq.3.6 d where the diameter of the
reinforcing cord is d and the thickness of the reinforcing cord
covering is T.
[0017] Further, according to the present invention, there is
provided a pneumatic tire of the above composition which provides
between the carcass and the tire members positioned at the outside
of the carcass such as a belt and side wall, etc., a rubber
composition layer containing, based on 100 parts by weight of (A)
at least one type of diene-based rubber selected from the group
consisting of a natural rubber, polyisoprene rubber, polybutadiene
rubber, and conjugated diene-aromatic vinyl copolymer rubber and
(B) an acrylonitrile-butadiene copolymer rubber, (C) 5 to 80 parts
by weight of an aromatic petroleum resin having an average
molecular weight of 300 to 1500, a softening point of 50 to
160.degree. C., and an iodine adsorption value of at least 20 g/100
g.
[0018] Further, according to the present invention, there is
provided a pneumatic tire characterized in that a thickness of the
rubber composition positioned at the outside of the carcass is 0.1
to 1.7 mm; the ratio of weight of (A) and (B) of the rubber
composition is (A)/(B)=90/10 to 10/90; the rubber composition
further contains at least one co-cross-linking agent selected from
the group consisting of a methacrylic acid higher ester, triallyl
isocyanurate, metal salt of methacrylic acid or acrylic acid,
diallyl phthalate ester, and 1,2-polybutadiene and is cross-linked
by an organic peroxide; and the carcass does not have an air
barrier layer.
[0019] Further, according to a fifth aspect of the present
invention, an object of the present invention is to provide a
pneumatic tire which reinforces at least part of the side wall of
the tire by a rubber containing a hydrogenated NBR or a rubber
composition containing this and zinc methacrylate and/or carbon
black, and further uses a specific adhesive to ensure bonding with
the adjoining rubber layer and thereby reduce the thickness of the
side wall and accordingly reduce the weight of the tire without
lowering the durability and cut resistance.
[0020] Further, an object of the present invention is to provide a
pneumatic tire which, by using a hydrogenated NBR rubber or a
hydrogenated NBR rubber composition containing zinc methacrylate
for the white or colored ribbon or letter parts positioned at the
surface of the side wall part of the tire, is greatly improved in
weather resistance and cut resistance and which does not
necessarily require an exclusive mold or can reduce the thickness
of the rubber at the ribbon or letter part, can lighten the weight
of the tire since not requiring a protective layer for preventing
migration of the polluting antioxidant, and uses a specific
adhesive to ensure bonding with the adjoining rubber layer and
thereby also improves the durability of the tire.
[0021] According to the present invention, there is provided a
pneumatic tire which reinforces at least part of the side wall by a
reinforcing layer comprised of a rubber composition containing,
based on a total 100 parts by weight of rubber containing at least
40 parts by weight of the hydrogenated NBR, 0 to 120 parts by
weight of zinc methacrylate and 0 to 30 parts by weight of carbon
black and having a total of formulations of zinc methacrylate and
carbon black of 10 to 120 parts by weight.
[0022] Further, according to the present invention, there is
provided a pneumatic tire providing a rubber composition colored
other than black at the surface of the side wall portion wherein
the rubber composition is comprised of a rubber composition
containing, based on a total 100 parts by weight of a rubber
containing at least 30 parts by weight of a hydrogenated NBR, 0 to
90 parts by weight of zinc methacrylate and the thickness is not
less than 0.5 mm.
[0023] Further, according to the present invention, there is
provided a pneumatic tire providing between the reinforcing layer
or rubber composition providing layer and the rubber layers
adjoining these a bonding rubber layer comprised of a rubber
composition containing, based on a total 100 parts by weight of (A)
at least one type of diene-based rubber selected from the group
consisting of a natural rubber, polyisoprene rubber, polybutadiene
rubber, and conjugated diene-aromatic vinyl copolymer rubber and
(B) an acrylonitrile-butadiene copolymer rubber, (C) 5 to 80 parts
by weight of an aromatic petroleum resin having an average
molecular weight of 300 to 1500, a softening point of 50 to
160.degree. C., and an iodine adsorption value of at least 20 g/100
g.
[0024] Further, according to the present invention, there is
provided a pneumatic tire characterized in that a thickness of the
bonding rubber layer is 0.1 to 2.0 mm; the ratio of weight (A)/(B)
of the (A) component and (B) component in the bonding rubber layer
is 90/10 to 10/90; and the bonding rubber layer further contains at
least one co-cross-linking agent selected from the group consisting
of a methacrylic acid higher ester, triallyl isocyanurate, metal
salt of methacrylic acid or acrylic acid, diallyl phthalate ester,
and 1,2-polybutadiene and is cross-linked by an organic
peroxide.
[0025] Further, according to a sixth aspect of the present
invention, an object of the present invention, noticing the
characteristics of hydrogenated NBR, is to provide a pneumatic tire
which uses a rubber composition containing a specific composition
of hydrogenated NBR and zinc methacrylate and/or carbon black for
the air barrier layer of the pneumatic tire to achieve a high
strength while reducing the amount of carbon used or without
formulating it, which is extremely low in tan.delta. and superior
in air barrier property and therefore enables a reduction of weight
through a lower thickness of the air barrier layer and further
improves the driving stability, and which uses a specific
composition of a rubber bonding layer between the air barrier layer
and the adjoining rubber to improve the bonding force and increase
the productivity.
[0026] According to the present invention, there is provided a
pneumatic tire forming an air barrier layer by a rubber composition
containing, based on a total 100 parts by weight of a rubber
containing at least 70 parts by weight of an ethylenic unsaturated
nitrile-conjugated diene-based highly saturated rubber having a
content of conjugated diene units of not more than 30 percent by
weight, 0 to 90 parts by weight of zinc methacrylate and 0 to 40
parts by weight of carbon black and having a total of formulations
of zinc methacrylate and carbon black of 10 to 90 parts by weight
and providing between the air barrier layer and the adjoining
rubber a bonding rubber layer comprised of a rubber composition
containing, based on a total 100 parts by weight of (A) at least
one type of diene-based rubber selected from the group consisting
of a natural rubber, polyisoprene rubber, polybutadiene rubber, and
conjugated diene-aromatic vinyl copolymer rubber and (B) an
acrylonitrile-butadiene copolymer rubber, (C) 5 to 80 parts by
weight of an aromatic petroleum resin having an average molecular
weight of 300 to 1500, a softening point of 50 to 160.degree. C.,
and an iodine adsorption value of at least 20 g/100 g.
[0027] Further, according to the present invention, there is
provided a pneumatic tire characterized in that the thickness of
the air barrier layer is 0.2 to 1.2 mm; the thickness of the
bonding rubber layer is 0.1 to 1.1 mm; the ratio of weight of (A)
and (B) of the rubber composition forming the bonding rubber layer
is (A)/(B)=90/10 to 10/90, and the rubber composition forming the
bonding rubber layer further contains at least one co-cross-linking
agent selected from the group consisting of a methacrylic acid
higher ester, triallyl isocyanurate, metal salt of methacrylic acid
or acrylic acid, diallyl phthalate ester, and 1,2-polybutadiene and
is cross-linked by an organic peroxide.
[0028] Further, according to a seventh aspect of the present
invention, an object of the present invention is to provide a
pneumatic tire improving the rim detachment and improving the
driving stability without reducing the strength of the bead toe
portion by providing at the bead toe portion a specific
hydrogenated NBR composition having a hardness higher than rubber,
a high strength with respect to deformation, and a small
temperature dependency of the hardness compared with rubber.
[0029] According to the present invention, there is provided a
pneumatic tire providing at least at part of the bead toe portion a
rubber composition containing 70 to 100 parts by weight of an
ethylenic unsaturated nitrile-conjugated diene-based highly
saturated rubber having a content of conjugated diene units of not
more than 30 percent by weight and containing 20 to 120 parts by
weight of zinc methacrylate.
[0030] Further, according to the present invention, there is
provided a pneumatic tire having a rubber composition of the bead
toe portion further containing not more than 40 parts by weight of
carbon black and having a total of formulations of zinc
methacrylate and carbon black of not more than 120 parts by
weight.
[0031] Further, according to the present invention, there is
provided a pneumatic tire bonding the rubber member of the bead toe
portion with the adjoining rubber layer through a bonding rubber
layer comprised of a rubber composition containing, based on a
total 100 parts by weight of (A) at least one type of diene-based
rubber selected from the group consisting of a natural rubber,
polyisoprene rubber, polybutadiene rubber, and conjugated
diene-aromatic vinyl copolymer rubber and (B) an
acrylonitrile-butadiene copolymer rubber, (C) 5 to 80 parts by
weight of an aromatic petroleum resin having an average molecular
weight of 300 to 1500, a softening point of 50 to 160.degree. C.,
and an iodine adsorption value of at least 20 g/100 g.
[0032] Further, according to the present invention, there is
provided a pneumatic tire characterized in that the ratio of weight
(A)/(B) of the component (A) and component (B) in the bonding
rubber layer is 90/10 to 10/90; the thickness of the bonding rubber
layer is 0.1 to 1.5 mm; and the bonding rubber layer further
contains at least one co-cross-linking agent selected from the
group consisting of a methacrylic acid higher ester, triallyl
isocyanurate, metal salt of methacrylic acid or acrylic acid,
diallyl phthalate ester, and 1,2-polybutadiene and is cross-linked
by an organic peroxide.
[0033] Further, according to an eighth aspect of the present
invention, there is provided a pneumatic tire having at least one
carcass layer comprised of rubberized organic fiber cord or steel
cord and at least two belt layers comprised of rubberized organic
fiber cord or steel cord, wherein at least the carcass coat rubber
and the belt coat rubber are comprised of a rubber composition
containing, based on a total 100 parts by weight of a rubber
containing at least 40 parts by weight of an ethylenic unsaturated
nitrile-conjugated diene-based highly saturated rubber having a
content of conjugated diene units of not more than 30 percent by
weight, 0 to 120 parts by weight of zinc methacrylate and 0 to 60
parts by weight of carbon black and having a total of formulations
of zinc methacrylate and carbon black of 10 to 120 parts by weight,
and providing between the rubber composition and adjoining
diene-based rubber a bonding rubber layer comprised of a rubber
composition containing, based on a total 100 parts by weight of (A)
at least one type of diene-based rubber selected from the group
consisting of a natural rubber, polyisoprene rubber, polybutadiene
rubber, and conjugated diene-aromatic vinyl copolymer rubber and
(B) an acrylonitrile-butadiene copolymer rubber, (C) 5 to 80 parts
by weight of an aromatic petroleum resin having an average
molecular weight of 300 to 1500, a softening point of 50 to
160.degree. C., and an iodine adsorption value of at least 20 g/100
g.
[0034] Further, according to a ninth aspect of the present
invention, there is provided a pneumatic tire which constitutes the
carcass coat rubber, belt coat rubber, and bead filler rubber; the
carcass coat rubber, belt coat rubber, bead filler, and side wall
rubber; or carcass coat rubber, belt coat rubber and bead filler,
side wall, rim cushion, and chafer rubber by the rubber containing
the hydrogenated NBR, and provides the bonding rubber layer between
the parts of these groups and the adjoining diene-based rubber
members.
[0035] Further, according to a 10th aspect of the present
invention, there is provided a pneumatic tire which uses at least
one type of rubber selected from the group consisting of a
diene-based rubber and butyl-based rubber for the cap tread and
uses at least one type of rubber selected from the group consisting
of a diene-based rubber, chloroprene-based rubber, butyl-based
rubber, ethylene-propylene-based rubber, nitrile-based rubber, and
hydrin-based rubber for the bead insulation or uses at least one
type of rubber selected from the group consisting of a diene-based
rubber and butyl-based rubber for the cap tread, and constitutes
the rubber of the other portions by the rubber containing the
hydrogenated NBR, and provides the bonding rubber layer between the
same.
[0036] Further, according to the inventions of the eighth to 10th
aspects, there is provided a pneumatic tire characterized in that
the thickness of the bonding rubber layer is 0.1 to 2.0 mm; the
ratio of weight (A)/(B) of (A) and (B) in the bonding rubber layer
is 90/10 to 10/90; and the bonding rubber layer further contains at
least one co-cross-linking agent selected from the group consisting
of a methacrylic acid higher ester, triallyl isocyanurate, metal
salt of methacrylic acid or acrylic acid, diallyl phthalate ester,
and 1,2-polybutadiene and is cross-linked by an organic
peroxide.
[0037] Further, according to an 11th aspect of the present
invention, there is provided a pneumatic tire constituting the bead
insulation rubber by at least one type of rubber selected from the
group consisting of a diene-based rubber, chloroprene-based rubber,
butyl-based rubber, ethylene-propylene-based rubber, nitrile-based
rubber, and hydrin-based rubber, and does not provide the bonding
rubber layer between the bead insulation and the adjoining rubber
composition containing the hydrogenated NBR.
[0038] Further, according to a 12th aspect of the present
invention, there is provided a pneumatic tire wherein the rubber at
portions other than the bead insulation rubber is comprised of
rubber containing the hydrogenated NBR or a pneumatic tire wherein
the rubber at all portions constituting the tire is comprised of
rubber containing the hydrogenated NBR.
[0039] Further, according to a 13th aspect of the present
invention, there is provided a pneumatic tire using rubber
containing the hydrogenated NBR colored a color other than black at
least at part of the inside and outside surface of the tire.
[0040] Further, according to a 14th aspect of the present
invention, there is provided a pneumatic tire not having an inner
liner layer when using rubber containing a hydrogenated NBR for the
rubber for predetermined part members.
BRIEF DESCRIPTION OF THE DRAWINGS
[0041] FIG. 1(a) to FIG. 1(e) are partial semisectional views in
the meridian direction showing the positional relationship of a
reinforcing liner layer in a run flat tire of the present
invention;
[0042] FIG. 2(a) to FIG. 2(c) are partial semisectional views in
the meridian direction of a tire showing the positional
relationship of a reinforcing rubber member of a bead portion of a
pneumatic tire of the present invention;
[0043] FIG. 3(a) to FIG. 3(g) are partial semisectional views in
the meridian direction of a tire showing the positional
relationship of various reinforcing layers in a side wall of a
pneumatic tire of the present invention, wherein FIG. 3(a) is a
view of the structure where the reinforcing layer is provided at
the surface of the side wall, FIG. 3(b) is a view of the structure
where the side wall is completely reinforced by the reinforcing
layer, FIG. 3(c) is a view of the structure where a side
reinforcing layer is provided between the carcass and side wall,
FIG. 3(d) is a view of the structure where a side reinforcing layer
is provided only near the maximum width position, FIG. 3(e) is a
view of the structure where a side reinforcing layer is provided
only at the top of the side wall, FIG. 3(f) is a view of the
structure where the side reinforcing layer is provided only at the
bottom of the side wall, and FIG. 3(g) is a view of the structure
where the side reinforcing layer is provided only at the top and
bottom of the side wall;
[0044] FIG. 4 is a view explaining the positional relationship of a
reinforcing layer at a side part of the pneumatic tire of the
present invention;
[0045] FIG. 5(a) and FIG. 5(b) are partial semisectional views in
the meridian direction of a tire showing the configuration of a toe
rubber member in the bead portion structure of a pneumatic tire of
the present invention, wherein FIG. 5(a) is a view of an embodiment
with finishing and FIG. 5(b) is a view of an embodiment without
finishing;
[0046] FIG. 6 is a view explaining the positional relationship of a
rubber member of a toe portion in a bead toe portion of a pneumatic
tire of the present invention;
[0047] FIG. 7 is a partial semisectional view in the meridian
direction of a structure where a rubber including hydrogenated NBR
is positioned at a carcass coat and belt coat member of a pneumatic
tire of the present invention;
[0048] FIG. 8 is a partial semisectional view in the meridian
direction of a structure where a rubber including hydrogenated NBR
is positioned at a carcass coat, belt coat, and bead filler member
of a pneumatic tire of the present invention;
[0049] FIG. 9 is a partial semisectional view in the meridian
direction of a structure where a rubber including hydrogenated NBR
is positioned at a carcass coat, belt coat, bead filler, and side
wall member of a pneumatic tire of the present invention;
[0050] FIG. 10 is a partial semisectional view in the meridian
direction of the positional relationship of part members of a
pneumatic tire of the present invention;
[0051] FIG. 11 is a partial semisectional view in the meridian
direction of a structure where a rubber including hydrogenated NBR
is positioned at all members other than the cap tread and bead
insulation of a pneumatic tire of the present invention; and
[0052] FIG. 12 is a view summarizing the test course used in a rim
detachment test of a test tire.
BEST MODE FOR WORKING THE INVENTION
[0053] In the present invention, a rubber composition containing,
based on a total 100 parts by weight of a rubber (rubber containing
hydrogenated NBR) containing at least 30 parts by weight of an
ethylenic unsaturated nitrile-conjugated diene-based highly
saturated rubber (hydrogenated NBR) having a content of conjugated
diene of not more than 30 percent by weight, preferably not more
than 20 percent by weight, 0 to 120 parts by weight of zinc
methacrylate and 0 to 60 parts by weight of carbon black and having
a total of formulations of zinc methacrylate and carbon black of 10
to 120 parts by weight is used for part or all of the part members
constituting the cap tread, under tread, reinforcing liner of the
side wall portion, bead portion reinforcing layer, carcass, side
wall reinforcing layer, air barrier layer, bead toe portion,
carcass coat, belt coat, bead insulation, and colored layer of the
pneumatic tire and, except when all of the part portions are
comprised of the rubber containing hydrogenated NBR or when the
bead insulation is comprised of a diene-based rubber and the
adjoining part portions are comprised of rubber containing a
hydrogenated NBR, providing between the part portions comprised of
the rubber containing a hydrogenated NBR and the adjoining other
part portions comprised of the diene-based rubber a bonding rubber
layer comprised of a rubber composition containing, based on a
total 100 parts by weight of (A) at least one diene-based rubber
selected from the group consisting of a natural rubber,
polyisoprene rubber, polybutadiene rubber, and conjugated
diene-aromatic vinyl copolymer rubber and (B) an
acrylonitrile-butadiene copolymer rubber, (C) 5 to 80 parts by
weight of an aromatic petroleum resin having an average molecular
weight of 300 to 1500, a softening point of 50 to 160.degree. C.,
and an iodine adsorption value of at least 20 g/100 g so as to
strongly bond the part portions comprised of the rubber containing
a hydrogenated NBR and the part portions comprised of the
diene-based rubber.
[0054] For the rubber containing a hydrogenated NBR used for the
part portions in the present invention, a rubber composition
containing, based on a total 100 parts by weight of rubber
containing at least 30 parts by weight of the hydrogenated NBR, 0
to 120 parts by weight of zinc methacrylate and 0 to 60 parts by
weight of carbon black and having a total amount of formulations of
zinc methacrylate and carbon black of 10 to 120 parts by weight is
used. In the rubber containing a hydrogenated NBR, if the
hydrogenated NBR is less than 30 parts by weight, the desired
strength of the rubber cannot be obtained, and therefore the rubber
is not desirable in use. Even if it is 100 parts by weight, there
is no problem at all. Further, if the total amount of formulations
of the zinc methacrylate and carbon black formed in the rubber
containing the hydrogenated NBR is less than 10 parts by weight,
the rubber is too soft and the driving stability etc. fall, while
if over 120 parts by weight, the rubber is too hard and is
inconvenient in use. Further, the rubber containing the
hydrogenated NBR may be made an extremely high hardness compared
with conventional diene-based rubbers by changing the formulations
in the range of amounts of formulations of the predetermined
components. At that time, the rubber is superior in durability,
fatigue resistance, and cut resistance and has a low heat buildup
and has a small drop in hardness at a high temperature, and
therefore the rubber containing hydrogenated NBR can be effectively
used for various tire part portions required for driving stability,
low rolling resistance, and lightening in weight.
[0055] The hydrogenated NBR (ethylenic unsaturated
nitrile-conjugated diene-based highly saturated copolymer rubber)
is already known as a copolymer of an ethylenic unsaturated nitrile
such as an acrylonitrile and methacrylonitrile and a conjugated
diene such as a 1,3-butadiene, isoprene, 1,3-pentadiene, and the
like or a terpolymer of the above two types of monomers and a
monomer copolymerizable therewith, such as a vinyl aromatic
compound, (meth)acrylic acid, alkyl (meth)acrylate, alkoxyalkyl
(meth)acrylate, cyanoalkyl (meth)acrylate, and the like.
Specifically, an acrylonitrile-butadiene copolymer rubber,
acrylonitrile-isoprene copolymer rubber,
acrylonitrile-butadiene-isoprene copolymer rubber,
acrylonitrile-butadiene-acrylate copolymer rubber,
acrylonitrile-butadiene-acrylate-methacrylate copolymer rubber, and
the like may be mentioned. These rubbers contain 30 to 60 percent
by weight of ethylenic unsaturated nitrile units and the conjugated
diene units are made less than 30 percent by weight, preferably
less than 20 percent by weight, by a means such as partial
hydrogenation of conjugated diene units.
[0056] The method of mixing the above zinc methacrylate (including
types in the form of zinc dimethacrylate) and/or carbon black with
the hydrogenated NBR is not particularly limited, but it is
possible to use a roll, bambury mixer, kneader, single-screw
kneader, double-screw kneader, and other mixers usually used in the
rubber industry.
[0057] Further, as the method of mixing the zinc methacrylate with
the hydrogenated NBR, in addition to the method of mixing the zinc
methacrylate directly with the hydrogenated NBR, it is also
possible to use the method of first mixing a zinc compound such as
zinc oxide and zinc carbonate with the hydrogenated NBR and causing
it to sufficiently disperse, then mixing or making the methacrylic
acid be absorbed to produce zinc methacrylate in the polymer. This
method is preferable since it gives an extremely good dispersion of
the zinc methacrylate. Further, it is preferable to use a
composition comprised of the zinc methacrylate and zinc compounds
dispersed in advance in the hydrogenated NBR. This may be obtained
as the "ZSC" (trademark) series made by Nippon Zeon, for example,
ZSC2295, ZSC2295N, ZSC2395, ZSC2298, etc.
[0058] Further, the rubber containing the hydrogenated NBR is
preferably cross-linked by an organic peroxide. As the organic
peroxide, one used for peroxide vulcanization of normal rubber may
be used. For example, a dicumyl peroxide, di-t-butyl peroxide,
t-butylcumyl peroxide, benzoyl peroxide,
2,5-dimethyl-2,5-di(t-butylperoxy)hexine-3,2,5-dimethyl-2,5-di(-
benzoylperoxy)hexane, 2,5-dimethyl-2,5-mono(t-butylperoxy)hexane,
.alpha.,.alpha.'-bis(t-butylperoxy-m-isopropyl)benzene, etc. may be
mentioned. These organic peroxides may be used alone or in
combinations of two or more types and preferably are formulated in
amounts of 0.2 to 10 parts by weight, preferably 0.2 to 6 parts by
weight based on 100 parts by weight of the rubber.
[0059] The rubber containing a hydrogenated NBR may suitably
contain other fillers, such as silica, calcium carbonate, talc,
etc., cross-linking aids such as triallyl isocyanurate, methacrylic
acid higher esters, diallyl phthalate esters, m-phenylene
bismaleinimide, and 1,2-polybutadiene, other plasticizers generally
used in the rubber industry, antioxidants, stabilizers, adhesives,
resins, processing aids, coloring agents, etc.
[0060] According to the present invention, to improve the bonding
between the part members comprised of the rubber containing the
hydrogenated NBR and the diene-based rubber layers of other
adjoining part members, it is necessary to bond them through a
bonding rubber layer comprising (A) at least one type of
diene-based rubber selected from the group consisting of a natural
rubber, polyisoprene rubber, polybutadiene rubber, and conjugated
diene-aromatic vinyl copolymers and (B) an acrylonitrile-butadiene
copolymer rubber and comprising, based on a total 100 parts by
weight of (A)+(B), 5 to 80 parts by weight of (C) an aromatic
petroleum resin having an average molecular weight of 300 to 1500,
a softening point of 50 to 160.degree. C., and an iodine adsorption
value of at least 20 g/100 g. If the amount of formulation of the
(C) aromatic petroleum resin based on the total 100 parts by weight
of the (A)+(B) is less than 5 parts by weight, the bonding force
drops. Further, if over 80 parts by weight, the heat buildup is
large. In both cases, this leads to tire breakage, and therefore it
is not preferable to formulate outside the above amount of (C).
[0061] The ratio of formulation of the (A) diene-based rubber and
(B) acrylonitrile-butadiene copolymer rubber contained in the
bonding rubber layer is preferably A:B=10:90 to 90:10 from the
viewpoint of the bonding force. If this range of the ratio of
formulation is exceeded, the bonding force falls. Further, the
thickness of the bonding rubber layer may be suitably determined by
the bonding with the parts in the range of 0.1 to 4.0 mm,
preferably 0.1 to 2.0 mm, more preferably 0.2 to 0.8 mm. If the
thickness is less than 0.1 mm, the bonding rubber layer will break
during production and the processing will become difficult, while
when thicker than 4.0 mm, while there will not be a problem in
ordinary driving, the bonding rubber layer will build up heat and
the bonding layer will break with long driving or highly severe
conditions, thus this is also not preferred.
[0062] The bonding rubber layer more preferably contains at least
one co-cross-linking agent selected from the group consisting of a
methacrylic acid higher ester, triallyl isocyanurate, metal salt of
methacrylic acid or acrylic acid, diallyl phthalate ester, and
1,2-polybutadiene and is cross-linked by an organic peroxide.
[0063] Further, the rubber composition constituting the bonding
rubber layer may suitably contain, in addition to the (C) aromatic
oil resin, a blending agent generally formulated in rubbers, for
example, fillers such as carbon, silica and talc, antioxidants,
plasticizers, processing aids, resins, adhesives, cross-linking
aids, vulcanization accelerators, tackifiers, etc.
[0064] The cap tread used in the first aspect of the invention must
be comprised of a hydrogenated NBR composition containing, based on
a total 100 parts by weight of rubber containing at least 70 parts
by weight of the hydrogenated NBR, 0 to 80 parts by weight of zinc
methacrylate and 0 to 40 parts by weight of carbon black and having
a total amount of these of 10 to 120 parts by weight. If the
hydrogenated NBR is less than 70 parts by weight in this
hydrogenated NBR composition, the strength is insufficient, and
therefore the abrasion of the members becomes too great and the
tire is unsuitable for use, but with 100 parts by weight, the
desired physical properties are rather excellent and the rubber is
very convenient for use. Further, if the total of the zinc
methacrylate and the carbon black is outside the above
predetermined range, the abrasion becomes great and the result is
inconvenient. The range is more preferably 30 to 100 parts by
weight.
[0065] Further, the under tread used in the present invention must
be comprised of a hydrogenated NBR composition containing, based on
a total 100 parts by weight of rubber containing at least 40 parts
by weight of the hydrogenated NBR, 0 to 120 parts by weight of zinc
methacrylate and 0 to 40 parts by weight of carbon black and having
a total amount of these of 10 to 120 parts by weight. If the
hydrogenated NBR is less than 40 parts by weight in this
hydrogenated NBR composition, it becomes difficult to obtain both
of the effect of improvement of the driving stability and the
reduction of the rolling resistance, but when using 100 parts by
weight, the desired effects are improved. Further, the amounts of
formulation of the zinc methacrylate and the carbon black and the
total amount of formulations being in the above ranges of
formulations is necessary from the viewpoint of the driving
stability, high speed durability, etc. If outside of these ranges
of formulation, the properties become poor, and therefore this is
not preferable.
[0066] In the present invention, in order to strongly bond the cap
tread and adjoining rubber layer and the under tread and adjoining
rubber layer, it is necessary to bond them through a bonding rubber
layer comprising a rubber composition containing, based on a total
100 parts by weight of (A) at least one type of diene-based rubber
selected from the group consisting of a natural rubber,
polyisoprene rubber, polybutadiene rubber, and conjugated
diene-aromatic vinyl copolymer rubber and (B) an
acrylonitrile-butadiene copolymer rubber (NBR), (C) 5 to 80 parts
by weight of an aromatic petroleum resin having an average
molecular weight of 300 to 1500, a softening point of 50 to
160.degree. C., and an iodine adsorption value of at least 20 g/100
g. The composition of the bonding rubber is preferably one
containing, based on a total 100 parts by weight of (A) a
diene-based rubber and (B) NBR in a ratio of 90/10 to 10/90, (C) 5
to 80 parts by weight of an aromatic petroleum resin. If the ratio
of (A)/(B) is not in the above range, the bonding force is poor and
the durability is inferior. Further, if the ingredient (C) is less
than 5 parts by weight, the bonding force is not satisfied, while
if over 80 parts by weight, the rolling resistance becomes
poor.
[0067] In constituting the pneumatic tire of the present invention,
the cap tread and under tread of the present invention may be
applied to only the cap tread portion or only the under tread
portion of the tire. Further, the cap tread and under tread of the
members of the present invention may be applied to both the cap
tread and under tread of the tire. In the latter case, not only is
the tire performance improved, but also the bonding rubber layer
between the cap tread and under tread becomes unnecessary, which is
more effective in terms of productivity. Further, when using the
cap tread of the present invention, it is possible to use the cap
tread of the present invention for only the tread shoulder part as
a measure against shoulder wear or conversely to use the cap tread
of the present invention for only the tread center part as a
measure against center wear. In addition, it is possible to use a
tread formed by laminating at least two compositions of different
formulations in the thickness direction of the tread.
[0068] Further, regarding the thickness of the cap tread used in
the tire configuration, the thickness must be at least the
thickness from the wear indicator to the road surface. If not, the
bonding rubber layer will end up becoming exposed before the wear
indicator is exposed. Further, the thickness of the bonding rubber
layer adjoining the cap tread must be at least 0.1 mm to
sufficiently satisfy the bonding, but conversely if over 4 mm, the
rolling resistance deteriorates, which is not preferable. If less
than 0.1 mm, the processing becomes difficult in practice, and
therefore the result is not practical industrially. The thickness
of the bonding rubber layer is more preferably 0.2 mm to 2.0
mm.
[0069] Further, the thickness of the bonding rubber layer adjoining
the under tread used for the tire configuration is preferably less
than the thickness of the under tread itself. Preferably, it is 0.1
to 0.5 mm, more preferably 0.2 to 0.3 mm. If less than 0.1 mm, the
actual processing becomes difficult, while if too thick, the effect
in improving the driving stability is reduced and the weight ends
up increasing as well.
[0070] In the second aspect of the present invention, when using a
predetermined hydrogenated NBR composition for the material
constituting a crescent sectional-shaped reinforcing liner layer
inserted and positioned between the carcass layer of the side wall
portion and inner liner layer in the pneumatic tire, it is possible
to increase the elasticity of the reinforcing liner layer without
increasing the heat buildup. Further, since the drop in modulus of
elasticity at high temperatures is low, it is possible to improve
the run flat property without causing an increase in the rolling
resistance. Further, even if the elasticity of the material is
raised, since the rubber has a higher durability compared with
conventional rubber compositions, it is possible to achieve the
same elasticity of the reinforcing liner layer as in the past even
if reducing the sectional area of the reinforcing liner layer, and
therefore it is possible to obtain a light weight run flat tire
without reducing the run flat property.
[0071] The crescent sectional-shaped reinforcing liner layer used
in the present invention must be comprised of a hydrogenated NBR
rubber composition containing, based on a total 100 parts by weight
of rubber containing 70 to 100 parts by weight of a hydrogenated
NBR, 20 to 120 parts by weight of zinc methacrylate and 0 to 40
parts by weight of carbon black and having a total of the
formulations of zinc methacrylate and carbon black of not more than
120 parts by weight. If the hydrogenated NBR is less than 70 parts
by weight in this hydrogenated NBR composition, the rubber is too
soft and is unsuitable for use, but there is no problem even if 100
parts by weight. Further, if the zinc methacrylate formulated in
the hydrogenated NBR composition is less than 20 parts by weight,
the rubber is too soft, while if over 120 parts by weight, it
becomes too hard. Further, there is no problem even if no carbon
black is formulated in the hydrogenated NBR composition, but even
if formulated in an amount over 40 parts by weight, the rubber
becomes brittle and will sometimes break, and therefore this is not
preferable. Further, if the total of the carbon black and zinc
methacrylate formulated in the hydrogenated NBR composition is over
120 parts by weight, the rubber becomes too hard and the riding
comfort of the vehicle becomes poor, and therefore this is not
preferred.
[0072] According to the present invention, in order to improve the
bonding between the reinforcing liner layer and the adjoining
rubber layer, it is necessary to bond them through a bonding rubber
layer comprising (A) at least one type of diene-based rubber
selected from the group consisting of a natural rubber,
polyisoprene rubber, polybutadiene rubber, and conjugated
diene-aromatic vinyl copolymers and (B) an acrylonitrile-butadiene
copolymer rubber and comprising, based on a total 100 parts by
weight of (A)+(B), (C) 5 to 80 parts by weight of an aromatic
petroleum resin having an average molecular weight of 300 to 1500,
a softening point of 50 to 160.degree. C., and an iodine adsorption
value of at least 20 g/100 g. If the amount of formulation of the
(C) aromatic petroleum resin based on the total 100 parts by weight
of the (A)+!B) is less than 5 parts by weight, the bonding force
drops. Further, if over 80 parts by weight, the heat buildup is
large. In both cases, this leads to tire breakage, and therefore it
is not preferable to formulate outside the amount of (C).
[0073] The ratio of formulation of the (A) diene-based rubber and
(B) acrylonitrile-butadiene copolymer rubber contained in the
bonding rubber layer is preferably A:B 10:90 to 90:10 in view of
the bonding force. If this range of the ratio of formulation is
exceeded, the bonding force drops. Further, the thickness of the
bonding rubber layer should be from 0.1 to 2.0 mm, more preferably
0.2 to 0.8 mm. If the thickness is less than 0.1 mm, breaks occur
in the bonding rubber layer at the time of production and the
processing becomes difficult. Further, if greater than 2.0 mm,
while there will not be a problem in ordinary driving, the bonding
rubber layer will build up heat and the bonding layer will break
with long driving or highly severe conditions, and therefore this
is also not preferred.
[0074] Below, an explanation will be made of the arrangement of the
reinforcing liner layer in the pneumatic tire of the second aspect
of the present invention referring to FIG. 1. FIGS. 1(a) to 1(e)
are semisectional explanatory views along the meridian direction of
the pneumatic tire of the present invention. These show the
positional arrangement among the crescent sectional-shaped
reinforcing liner layer, bonding rubber layer, and adjoining rubber
layer in the side wall portion of the tire and the positional
relationship between the belt layer of the reinforcing liner layer
and the bead filler.
Positional Relationship of Reinforcing Liner (FIGS. 1(a) to 1(e))
and Merits Thereof
[0075] (a) A structure where the carcass layer is comprised of an
inside and outside layer, the inside carcass layer is folded
outward from the inside of the tire around the bead core, and the
end is sandwiched between the inside carcass layer and the outside
carcass layer, and a structure where the outside carcass layer is
folded back at the bead core and the crescent sectional-shaped
reinforcing liner layer has one end which overlaps the end of the
belt layer of the tread portion and other end which overlaps the
bead filler of the bead portion. However, the outside carcass layer
need not be folded back at the bead core and may be turned down so
that an end is positioned near the bead core.
[0076] A preferable structure where there is little local
deformation of the side wall portion and the entirety deforms
smoothly, and therefore the run flat property is most improved.
[0077] (b) A structure where, compared with (a), one end of the
reinforcing liner layer is not overlapped with the end of the belt
layer.
[0078] The local deformation of the side wall portion becomes
larger than that of (a), and therefore the effect of improvement of
the run flat property declines somewhat from the structure of (a),
but the effect of improvement is sufficient compared with when not
utilizing the present invention.
[0079] (c) A structure where, compared with (a), one end of the
reinforcing liner layer does not overlap the bead filler.
[0080] The local deformation of the side wall portion becomes
larger than that of (a), and therefore the effect of improvement of
the run flat property declines somewhat from the structure of (a),
but the effect of improvement is sufficient compared with when not
utilizing the present invention.
[0081] (d) A structure where, compared with (a), both ends of the
reinforcing liner layer do not overlap either the belt layer or the
bead filler.
[0082] The local deformation of the side wall portion becomes
larger than that of (a), and therefore the effect of improvement of
the run flat property declines somewhat from the structure of (b)
and (c), but the effect of improvement is sufficient compared with
when not utilizing the present invention.
[0083] (e) A structure where the carcass layer is comprised of two
layers and the two carcass layers are both folded back outward from
the inside of the tire around the the bead core.
[0084] Compared with the structure of (a), it is possible to
eliminate the step of folding back the outside carcass layer inside
and the productivity is improved.
[0085] In the third aspect of the present invention, a hydrogenated
NBR composition containing, based on a total 100 parts by weight of
a rubber containing 20 to 100 parts by weight of the hydrogenated
NBR, 40 to 120 parts by weight of zinc methacrylate and 0 to 40
parts by weight of carbon black and, when containing both
ingredients of the zinc methacrylate and carbon black, having a
total amount of formulations of not more than 120 parts by weight
is used for the reinforcing rubber member of the bead portion in
the tire (including solid tires). The hydrogenated NBR used in the
base rubber member is an ethylenic unsaturated nitrile-conjugated
diene-based highly saturated copolymer rubber having a content of
conjugated diene units of not more than 30 percent by weight. For
this hydrogenated NBR, one having a content of conjugated diene
units of not more than 30 percent by weight, preferably not more
than 20 percent by weight may be preferably used. If the content of
the conjugated diene units is not more than 30 percent by weight,
that is, if the partial hydrogenation rate is less than about 50
percent, the strength of the rubber composition becomes
insufficient.
[0086] As the hydrogenated NBR used for the base rubber member, one
containing 70 to 100 parts by weight of this is preferably used. If
less than 70 parts by weight, the rubber becomes too soft and the
desired effect cannot be achieved. Further, the zinc methacrylate
formulated in the hydrogenated NBR is preferably used in a range of
40 to 120 parts by weight. If the amount formulated is less than 40
parts by weight, the rubber becomes too soft, while if over 120
parts by weight, the rubber becomes too hard and is unsuitable.
Further, the carbon black need not be formulated, but may be
included in an amount of formulation up to 40 parts by weight. If
the amount of formulation of carbon black exceeds 40 parts by
weight, the reinforcing rubber member becomes brittle and breaks,
and therefore this is not preferable. Further, when the carbon
black is used together with zinc methacrylate, if the total amount
of formulations exceeds 120 parts by weight, the member will become
too hard and the driving stability and riding comfort will become
poor, and therefore it is necessary to keep the total amount to be
not more than 120 parts by weight.
[0087] Here, the reinforcing rubber member of the bead portion, in
the third aspect of the present invention, means the bead filler
member, different bead filler member, and auxiliary bead filler
member of the portions shown by the hatchings in FIGS. 2(a) to
2(c). That is, as shown in FIG. 2(a), basically the member of the
present invention is used as a bead filler adjoining the carcass
body and the turned up portion at the outside of the radial
direction of the bead core. Further, as shown in FIG. 2(b), the
bead filler can be comprised of a plurality of types of materials
combined with other materials including the members of the present
invention. In this case, it is a bead filler combining different
types of members of the present invention, rubbers, etc. Further,
as shown in FIG. 2(c), in addition to the bead filler, it is also
possible to provide an auxiliary bead filler structure, a member of
the present invention, at an adjoining location through the carcass
layer. At this time, if the auxiliary bead filler is arranged to
envelop the turned up end of the carcass, the durability is
improved, and therefore this is preferred. Further, in all cases,
the position of the turned up end of the carcass may be made higher
than or lower than the upper end of the bead filler, including the
different member and the auxiliary bead filler.
[0088] In the present invention, the reinforcing rubber member of
the bead portion and the adjoining rubber layer are strongly bonded
through a bonding rubber layer containing, based on a total 100
parts by weight of (A) at least one type of diene-based rubber
selected from the group consisting of a natural rubber,
polyisoprene rubber, polybutadiene rubber, and conjugated
diene-aromatic vinyl copolymer rubber and (B) an
acrylonitrile-butadiene copolymer rubber, (C) 5 to 80 parts by
weight of an aromatic petroleum resin having an average molecular
weight of 300 to 1500, a softening point of 50 to 160.degree. C.,
and an iodine adsorption value of at least 20 g/100 g. If the
amount of formulation of the (C) aromatic petroleum resin is less
than 5 parts by weight based on the total 100 parts by weight of
(A)+(B), the bonding force falls, while if over 80 parts by weight,
the heat buildup becomes large and the rubber breaks when driving
the tire at a high load, and therefore it is necessary to keep the
above amount of formulation.
[0089] The ratio of (A):(B) contained in the bonding rubber layer
is preferably a ratio by weight of 10:90 to 90:10 in terms of the
bonding force. Further, the thickness of the bonding rubber layer
is preferably 0.1 to 2.0 mm, more preferably 0.2 to 0.8 mm. If this
is less than 0.1 mm, the bonding rubber layer may break at the time
of laminar shaping by extrusion etc. and the processing will become
difficult. If thicker than 2.0 mm, when the tire is run at a high
load, the bonding rubber layer will build up heat, and therefore
the durability will fall.
[0090] The carcass used for the pneumatic tire according to the
fourth aspect of the present invention must be comprised by
covering the reinforcing cord by a rubber composition containing,
based on a total 100 parts by weight of a rubber containing at
least 70 parts by weight of the hydrogenated NBR, 0 to 90 parts by
weight of zinc methacrylate and 0 to 40 parts by weight of carbon
black and having a total of formulations of zinc methacrylate and
carbon black of 10 to 90 parts by weight and further using at least
one carcass of 1.1 d.ltoreq.T.ltoreq.3.6 d where the diameter of
the reinforcing cord is d and the thickness of the reinforcing cord
covering is T. Here, the reinforcing cord does not necessarily have
to be positioned at the center in the thickness direction of the
carcass. So long as the thickness of one of the rubber coverings
satisfies the minimum thickness (0.05 d when the diameter of the
cord is d), it may be positioned to one side. Further, the
thickness of the rubber covering does not have to be constant in
the cord direction. So long as the minimum thickness is 1.1 d and
the average thickness does not exceed 3.6 d, it may be freely set.
Further, when two or more layers of carcass are used, the bonding
rubber layer need only be outside of the outermost carcass layer.
When providing the air barrier layer of the butyl rubber at the
innermost surface of the tire, the bonding rubber layer is not
necessarily required between them.
[0091] The thickness of the carcass is made 1.1 to 3.6 times the
reinforcing cord because it has to be made 1.1 times the minimum
carcass cord diameter to effectively envelop the carcass cord and
further if over 3.6 times, there is no longer any merit in weight
even if eliminating the air barrier layer.
[0092] If the air barrier property is set the same as in a
conventional tire, the weight can be reduced by the amount of the
air barrier layer. Further, if desiring to make the air barrier
property better than in the past, it is sufficient to increase the
gauge of the carcass cord. By using this method, it is possible to
provide a tire with little air leakage without increasing the
manufacturing costs.
[0093] The hydrogenated NBR has a high polymer strength and enables
a reduction in the amount of formulation of carbon, which is a
cause of a high tan.delta. compared with general purpose rubber.
Further, a rubber composition comprising the hydrogenated NBR of
the present invention plus zinc methacrylate exhibits a high
strength even without formulation of carbon and an extremely low
tan.delta.. By using this for the carcass coat, it is possible to
reduce the rolling resistance of the tire.
[0094] Further, the hydrogenated NBR is superior in air barrier
property, and therefore a tire using the hydrogenated NBR for a
carcass does not necessarily require an air barrier layer and
therefore a large reduction in weight can be achieved. Here, by
just removing the air barrier layer, the rigidity of the tire as a
whole will end up falling while the weight is reduced. With the
carcass coat of the present invention, however, it is possible to
increase the amount of the zinc methacrylate so as to increase the
modulus of the rubber without increasing the tan.delta. as with a
carbon formulation and thereby make up for the insufficient
rigidity due to the greater thinness.
[0095] According to the present invention, in order to increase the
bonding between the carcass and adjoining rubber layer, it is
necessary to bond them through a bonding rubber layer comprising
(A) at least one type of diene-based rubber selected from the group
consisting of a natural rubber, polyisoprene rubber, polybutadiene
rubber, and conjugated diene-aromatic vinyl copolymers and (B) an
acrylonitrile-butadiene copolymer rubber and comprising, based on a
total 100 parts by weight of (A)+(B), 5 to 80 parts by weight of
(C) an aromatic petroleum resin having an average molecular weight
of 300 to 1500, a softening point of 50 to 160.degree. C., and an
iodine adsorption value of at least 20 g/100 g. If the amount of
formulation of the (C) aromatic petroleum resin based on the total
100 parts by weight of the (A)+(B) is less than 5 parts by weight,
the bonding force drops. Further, if over 80 parts by weight, the
heat buildup is large. In both cases, this leads to tire breakage,
and therefore it is not preferable to formulate outside the amount
of (C).
[0096] Regarding the thickness of the bonding rubber layer used
above, in the case of a carcass, one with a thickness in the range
of 0.1 to 1.7 mm so as to be positioned at the outside of the
carcass is preferably used. If the thickness of the bonding rubber
layer is at least 0.1 mm, the bonding property is sufficiently
satisfied, but as a practical range in industry, it is preferably
at least 0.2 mm. Conversely, if the thickness exceeds 1.7 mm, the
weight increases too much and the rolling resistance deteriorates,
and therefore this is also not preferred.
[0097] The composition of the bonding rubber layer is preferably a
total 100 parts by weight of (A) diene-based rubber and (B)
acrylonitrile-butadiene copolymer rubber in a ratio by weight of
90/10 to 10/90 and 5 to 80 parts by weight of the (C) aromatic
petroleum resin.
[0098] In the fifth aspect of the present invention, it is
contemplated that a hydrogenated NBR rubber composition having
rigidity and superior in weather resistance and durability is used
for at least part of the side wall in a pneumatic tire or for the
white or colored ribbon or letter portion placed at the surface
part of the side wall. Using this hydrogenated NBR composition for
the tire member, however, results in a problem of bonding of the
material itself with the general purpose rubber used for the tire
and is accompanied by a large amount of difficulty in practical
use. In the present invention, however, a specific rubber adhesive
extremely superior in terms of bonding between the members and
general purpose rubber was discovered whereby the problem was
eliminated all at once and the present invention realized.
[0099] According to one embodiment of the present invention, a
reinforcing layer comprised of a rubber composition containing,
based on a total 100 parts by weight of rubber containing at least
40 parts by weight of an ethylenic unsaturated nitrile-conjugated
diene-based highly saturated copolymer rubber having a content of
conjugated diene units of not more than 30 percent by weight
(hydrogenated NBR), 0 to 120 parts by weight of zinc methacrylate
and 0 to 30 parts by weight of carbon black and having a total of
formulations of zinc methacrylate and carbon black of 10 to 120
parts by weight is used for at least part of the side wall portion
of the pneumatic tire.
[0100] As the hydrogenated NBR contained in the rubber composition,
one having a content of conjugated diene units of preferably not
more than 30 percent by weight, preferably not more than 20 percent
by weight is used. If the content of the conjugated diene units is
more than 30 percent by weight, that is, the partial hydrogenation
rate is not more than about 50 percent, the strength of the rubber
composition becomes insufficient. Further, as the hydrogenated NBR
used for the base rubber member used for the reinforcing layer, one
containing 40 to 100 parts by weight of the same is used. If the
amount is less than 40 parts by weight, the rubber becomes too soft
and the desired effect as a reinforcing layer cannot be achieved.
Further, the total amount of formulations of zinc methacrylate
and/or carbon black acting as the reinforcing agent formulated in
the hydrogenated NBR composition is preferably made 10 to 120 parts
by weight. If the amount of formulation is less than 10 parts by
weight, the rubber is too soft and the cut resistance deteriorates,
while if over 120 parts by weight, it is too hard and the
durability deteriorates, and therefore both cases are
unsuitable.
[0101] The reinforcing layer at the side wall portion in the
present invention can be positioned in various arrangements. For
example, it can be arranged as shown in FIGS. 3(a) to 3(g).
Further, regarding the range of the reinforcing layer at the side
wall portion, in all of the cases shown in FIG. 3, it is sufficient
that at least part of the range of 20 to 80 percent of the
sectional height SH of the tire be reinforced by the side part
reinforcing layer as shown in FIG. 4.
[0102] According to another embodiment of the present invention, a
rubber composition colored other than black containing, based on a
total 100 parts by weight of a rubber containing at least 30 parts
by weight of a hydrogenated NBR, 0 to 90 parts by weight of zinc
methacrylate, is provided at the surface of the side wall portion
of the pneumatic tire at a thickness of not less than 0.5 mm.
According to this embodiment of the present invention, by providing
a rubber composition comprised of the above predetermined
composition at the surface of the side wall of the pneumatic tire
to a predetermined thickness, it is possible to greatly improve the
weather resistance and cut resistance of the tire and use the
rubber composition provided as a white or colored ribbon or letters
and thereby achieve an aesthetic effect of the tire.
[0103] The hydrogenated NBR contained in the rubber composition
must be present in an amount of 30 to 100 parts by weight in the
case of the above embodiment. Further, 0 to 90 parts by weight of
zinc methacrylate is formulated in the rubber composition. The zinc
methacrylate can give a sufficient cut resistance in formulations
of 0 to 90 parts by weight. When formulated in an amount more than
90 parts by weight, the rubber becomes too hard and the durability
becomes poor. Note that in the case of the above embodiment, in
order to avoid the rubber composition becoming black, no carbon
black is formulated. Further, the thickness of the rubber
composition layer provided has to be at least 0.5 mm in order to be
able to prevent the migration of the antioxidant, which is a cause
of pollution, from the tire rubber composition. Therefore, by
applying a rubber composition satisfying the above requirements to
the surface of the side wall portion of the pneumatic tire, it is
possible to greatly improve the weather resistance, cut resistance,
and durability of the tire and reduce the thickness, and therefore
the weight can be reduced. Further, no special mold like in the
past is necessarily required. Further, since the hydrogenated NBR
has a high polymer polarity, the polluting antioxidant does not
easily migrate and therefore there is the effect that there is no
discoloration even without providing a protective layer for the
same.
[0104] In the present invention, further, the reinforcing layer
used in the first and second embodiments and the rubber composition
layers where they are provided are bonded with the adjoining rubber
layers through a bonding rubber layer containing, based on a total
100 parts by weight of (A) at least one type of diene-based rubber
selected from the group consisting of a natural rubber,
polyisoprene rubber, polybutadiene rubber, and conjugated
diene-aromatic vinyl copolymer rubber and (B) an
acrylonitrile-butadiene copolymer rubber, (C) 5 to 80 parts by
weight of an aromatic petroleum resin having an average molecular
weight of 300 to 1500, a softening point of 50 to 160.degree. C.,
and an iodine adsorption value of at least 20 g/100 g. If the
amount of formulation value of the (C) aromatic petroleum resin
based on the total 100 parts by weight of the (A)+(B) is less than
5 parts by weight, the bonding force drops and the durability
deteriorates. Further, if over 80 parts by weight, the heat buildup
is large and the rolling resistance deteriorates. Therefore, this
amount of formulation is necessary.
[0105] Further, in the present invention, the thickness of the
bonding rubber layers in the case of bonding with the reinforcing
layer used in the first embodiment or rubber composition layer used
in the second embodiment is 0.1 to 2.0 mm, preferably 0.2 to 1.5
mm. If less than 0.1 mm, the actual processing becomes difficult
and the result is not industrially practical. Further, if thicker
than 2.0 mm, the effect of reducing the weight is not obtained and
the rolling resistance deteriorates.
[0106] The sixth aspect of the present invention is characterized
by the use of a predetermined hydrogenated NBR composition for the
material constituting the air barrier layer in the pneumatic tire
and by the bonding of the air barrier layer and adjoining rubber
layer through a bonding rubber layer comprising a specific
diene-based rubber, acrylonitrile-butadiene copolymer rubber, and
aromatic oil resin.
[0107] As the air barrier layer used in the pneumatic tire of the
present invention, a hydrogenated NBR rubber composition
containing, based on a total 100 parts by weight of a rubber
containing at least 70 parts by weight of the hydrogenated NBR, 0
to 90 parts by weight of zinc methacrylate and 0 to 40 parts by
weight of carbon black and having a total of formulations of these
of 10 to 90 parts by weight is used. If the amount of formulation
of the hydrogenated NBR is less than 70 parts by weight, the air
barrier property deteriorates, but a sufficient air barrier
property can be secured by 70 to 100 parts by weight. If the total
of the zinc methacrylate and the carbon black is less than 10 parts
by weight, the driving stability becomes poor, while if over 90
parts by weight, conversely the riding comfort deteriorates, and
therefore these are not preferred. Further, the thickness of the
air barrier layer is suitably 0.2 to 1.2 mm. If the thickness is at
least 0.2 mm, the required air barrier property is sufficiently
satisfied, while if over 1.2 mm, the weight unpreferably
increases.
[0108] When using the hydrogenated NBR composition for the air
barrier layer, since the energy loss of the hydrogenated NBR
composition is small, there is no problem even if butyl rubber
enters between the carcass cord at the time of vulcanization, i.e.,
so-called spectacle phenomenon occurs. Therefore, the tie rubber of
the conventional buffer rubber sheet becomes unnecessary and the
weight can be reduced by that amount. Further, the processability
of the unvulcanized rubber is good and the liner can be hardened by
the addition of the zinc methacrylate, and therefore it is possible
to raise the rigidity of the tire and improve the driving
stability.
[0109] According to the present invention, in order to improve the
bonding between the air barrier layer and the adjoining rubber
layer, it is necessary to bond them through a bonding rubber layer
comprising (A) at least one type of diene-based rubber selected
from the group consisting of a natural rubber, polyisoprene rubber,
polybutadiene rubber, and conjugated diene-aromatic vinyl copolymer
rubber and (B) an acrylonitrile-butadiene copolymer rubber and
comprising, based on a total 100 parts by weight of (A)+(B), (C) 5
to 80 parts by weight of an aromatic petroleum resin having an
average molecular weight of 300 to 1500, a softening point of 50 to
160.degree. C., and an iodine adsorption value of at least 20 g/100
g. If the amount of formulation of the (C) aromatic petroleum resin
based on the total 100 parts by weight of the (A)+(B) is less than
5 parts by weight, the bonding force drops. Further, if over 80
parts by weight, the heat buildup is large. In both cases, this
leads to tire breakage, and therefore it is not preferable to
formulate outside the amount of (C).
[0110] Regarding the thickness of the bonding rubber layer used, it
is preferable to use a layer of a thickness of 0.1 to 1.1 mm. So
long as the thickness of the bonding rubber layer is at least 0.1
mm, the bonding is sufficiently satisified, but an industrially
practical range is preferably at least 0.2 mm. Conversely, if the
thickness is over 1.1 mm, the weight increases too much and
conversely the rolling resistance deteriorates, and therefore this
is not preferred.
[0111] The composition of the bonding rubber layer is preferably a
total 100 parts by weight of the (A) diene-based rubber and (B)
acrylonitrile-butadiene copolymer rubber in a ratio of 90/10 to
10/90 and 5 to 80 parts by weight of (C) the aromatic petroleum
resin.
[0112] The seventh aspect of the present invention is characterized
mainly in that a predetermined hydrogenated NBR composition is used
for the member constituting the bead toe portion of the pneumatic
tire and that the bead toe portion and adjoining rubber layer are
bonded through a bonding rubber layer comprised of a specific
diene-based rubber, acrylonitrile-butadiene copolymer rubber, and
aromatic petroleum resin.
[0113] The bead toe portion used in the present invention must be
comprised of a hydrogenated NBR rubber composition containing,
based on a total of 100 parts by weight of a rubber. containing 70
to 100 parts by weight of the hydrogenated NBR, 20 to 120 parts by
weight of zinc methacrylate. In this hydrogenated NBR rubber
composition, if the hydrogenated NBR is less than 70 parts by
weight, the rubber is too soft and the driving stability declines,
and therefore the rubber is unsuitable for use, but there is no
problem even if 100 parts by weight. Further, if the amount of zinc
methacrylate formulated in the hydrogenated NBR composition is less
than 20 parts by weight, the rubber is too soft and the driving
stability declines, while if over 120 parts by weight, the rubber
is too hard and the fit with the rim deteriorates. Further, the
hydrogenated NBR composition may contain up to 40 parts by weight
of carbon black. In this case, the total amount of formulations of
the zinc methacrylate and the carbon black must be made not more
than 120 parts by weight. If the amount of formulation of the
carbon black exceeds 40 parts by weight, the rubber becomes brittle
and breaks upon major deformation at the time of attachment to the
tire rim. Further, if the total of the zinc methacrylate and the
carbon black exceeds 120 parts by weight, the rubber becomes too
hard and the fit with the rim deteriorates, and therefore this is
also not preferred.
[0114] According to the present invention, in order to improve the
bonding between the rubber members of the bead toe portion and the
adjoining rubber layer, it is possible to bond them through a
bonding rubber layer comprised of a rubber composition containing,
based on a total 100 parts by weight of (A) at least one type of
diene-based rubber selected from the group consisting of a natural
rubber, polyisoprene rubber, polybutadiene rubber, and conjugated
diene-aromatic vinyl copolymer rubber and (B) an
acrylonitrile-butadiene copolymer rubber, (C) 5 to 80 parts by
weight of an aromatic petroleum resin having an average molecular
weight of 300 to 1500, a softening point of 50 to 160.degree. C.,
and an iodine adsorption value of at least 20 g/100 g. If the
amount of formulation of the (C) aromatic petroleum resin based on
the total 100 parts by weight of (A)+(B) is less than 5 parts by
weight, the processability of the bonding rubber deteriorates.
Further, if over 80 parts by weight, the compression set
deteriorates.
[0115] The ratio of formulation of the (A) diene-based rubber and
the (B) acrylonitrile-butadiene copolymer rubber contained in the
bonding rubber layer is preferably A:B=10:90 to 90:10 from the
viewpoint of the bonding force. Further, the thickness of the
bonding rubber layer should be 0.1 to 1.5 mm, more preferably 0.2
to 0.8 mm. If the thickness is less than 0.1 mm, the bonding rubber
layer will break at the time of production and the processing will
become difficult. Further, if thicker than 1.5 mm, the bead width
becomes greater and the fit with the rim deteriorates, and
therefore this is not preferred.
[0116] In the tire according to the present invention, the strain
occurring at the bead toe portion at the time of general driving is
small, and therefore there is no absolute need for the above
bonding rubber layer, but since the strain becomes large at the
bead toe portion in the case of highly severe driving (for example,
circuit driving) etc., it is preferable to provide the bonding
rubber layer.
[0117] The rubber members of the bead toe portion according to the
present invention are actually used in the manners shown in the
embodiments of FIGS. 5(a) and 5(b). Further, explaining the
preferable positional relationship of the rubber members of the
bead toe portion using FIG. 6, it is preferable that they be
arranged to satisfy the relationship of:
Lc.ltoreq.L.ltoreq.Ls and Hc.ltoreq.H.ltoreq.2Hc
[0118] wherein L: Distance in tire axial direction from bead toe to
under bead core of rubber member of toe portion,
[0119] Lc: Distance in tire axial direction from bead toe to inside
bead core,
[0120] Ls: Distance in tire axial direction from bead toe to
outside bead core,
[0121] H: Height in tire radial direction from bead toe of rubber
member of bead portion to upper end of rubber member of toe
portion, and
[0122] Hc: Height in tire radial direction from bead toe of rubber
member of bead portion to center of bead core.
[0123] Here, when the relationship L<Lc stands, since there is
no portion facing the bottom side of the bead core, the rubber
member of the toe portion is liable to detach during rim
attachment. Further, when the relationship L>Ls stands, the fit
of the tire and rim is liable to deteriorate. Further, when the
relationship H<Hc stands, the bead portion will easily collapse
during cornering and the effect of improvement of the driving
stability is liable to become smaller. Further, when the
relationship H>2Hc stands, the fit by the rim attachment is
liable to decline somewhat.
[0124] In the eighth to 14th aspects of the present invention it is
characterized in that a rubber composition containing, based on a
total 100 parts by weight of a rubber containing at least 40 parts
by weight of an ethylenic unsaturated nitrile-conjugated
diene-based highly saturated rubber having a content of conjugated
diene units of not more than 30 percent (hydrogenated NBR), 0 to
120 parts by weight of zinc methacrylate and 0 to 60 parts by
weight of carbon black and having a total of formulations of zinc
methacrylate and carbon black of 10 to 120 parts by weight (rubber
containing hydrogenated NBR) is used for part or all of the part
portions constituting the carcass coat, belt coat, bead filler,
side wall, rim cushion, chafer, cap tread, and bead insulation in
the pneumatic tire, and between the part portions constituted by
the rubber containing the hydrogenated NBR and the adjoining other
part portions constituted by a diene-based rubber, a bonding rubber
layer comprised of a rubber composition containing, based on a
total 100 parts by weight of (A) at least one type of diene-based
rubber selected from the group consisting of a natural rubber,
polyisoprene rubber, polybutadiene rubber, and conjugated
diene-aromatic vinyl copolymer rubber and (B) an
acrylonitrile-butadiene copolymer rubber, (C) 5 to 80 parts by
weight of an aromatic petroleum resin having an average molecular
weight of 300 to 1500, a softening point of 50 to 160.degree. C.,
and an iodine adsorption value of at least 20 g/100 g is provided
to strongly bond the part portions comprised of the rubber
containing the hydrogenated NBR and the part portions comprised of
the diene-based rubber.
[0125] For the rubber containing the hydrogenated NBR used for the
part portions in the present invention, a rubber composition
containing, based on a total 100 parts by weight of a rubber
containing at least 40 parts by weight of the hydrogenated NBR, 0
to 120 parts by weight of zinc methacrylate and 0 to 60 parts by
weight of carbon black and having a total amount of the
formulations of zinc methacrylate and carbon black of 10 to 120
parts by weight is used. In this rubber containing hydrogenated
NBR, if the amount of the hydrogenated NBR is less than 40 parts by
weight, the desired strength of the rubber will not be obtained,
and therefore this is not preferable in use. Even if 100 parts by
weight, however, there is no problem at all. Further, if the total
amount of formulations of the zinc methacrylate and carbon black
formulated in the rubber containing hydrogenated NBR is less than
10 parts by weight, the rubber becomes too soft and the driving
stability etc. fall, while if over 120 parts by weight, the rubber
is too hard and is inconvenient for use. Further, the rubber
containing hydrogenated NBR can be made an extremely high hardness
compared with conventional diene-based rubbers by changing the
formulations in the range of the amounts of formulations of the
predetermined ingredients. At this time as well, the rubber is
superior in durability, fatigue resistance, and cut resistance and
low in heat buildup. Further, since the decline in hardness at high
temperatures is small, the rubber containing the hydrogenated NBR
can be effectively used for various tire part portions required for
the driving stability, low rolling resistance, and lightening in
weight.
[0126] According to the present invention, in order to improve the
bonding between the part portions comprised of the rubber
containing hydrogenated NBR and the diene-based rubber layer of the
other adjoining part portions, it is necessary to bond them through
a bonding rubber layer containing, based on (A) at least one type
of diene-based rubber selected from the group consisting of a
natural rubber, polyisoprene rubber, polybutadiene rubber, and
conjugated diene-aromatic vinyl copolymer rubber and (B) an
acrylonitrile-butadiene copolymer rubber and containing, based on a
total 100 parts by weight of (A)+(B), (C) 5 to 80 parts by weight
of an aromatic petroleum resin having an average molecular weight
of 300 to 1500, a softening point of 50 to 160.degree. C., and an
iodine adsorption value of at least 20 g/100 g. If the amount of
formulation of the (C) aromatic petroleum resin based on the total
100 parts by weight of (A)+(B) is less than 5 parts by weight, the
bonding force declines. Further, if over 80 parts by weight, the
heat buildup is large. In both cases, this leads to tire breakage,
and therefore it is not preferable to formulate outside the amount
of (C).
[0127] The ratio of formulations of the (A) diene-based rubber and
(B) acrylonitrile-butadiene copolymer rubber contained in the
bonding rubber layer is preferably A:B=10:90 to 90:10 from the
viewpoint of the bonding force. If this range of the ratio of
formulation is exceeded, the bonding force falls. Further, the
thickness of the bonding rubber layer is preferably 0.1 to 2.0 mm,
more preferably 0.2 to 0.8 mm. If the thickness is less than 0.1
mm, the bonding rubber layer will break during production and
processing will become difficult, while when thicker than 2.0 mm,
while there will not be a problem in ordinary driving, the bonding
rubber layer will build up heat and the bonding layer will break
with long driving or highly severe conditions, and therefore this
is also not preferred.
[0128] According to the eighth aspect of the present invention, as
shown in FIG. 7, the rubber coating the reinforcing cord of the
carcass and the belt is comprised of the rubber containing
hydrogenated NBR. In this case, the rubber containing hydrogenated
NBR is reinforced by zinc methacrylate and/or carbon black. The
other part portions may be comprised of a conventional diene-based
rubber. In this case, the rubber containing hydrogenated NBR and
diene-based rubber are bonded by interposing a predetermined
bonding rubber layer with the rubber containing hydrogenated NBR
comprising the carcass coat and belt coat.
[0129] When adopting this embodiment, since the rubber containing
hydrogenated NBR is higher in hardness and lower in heat buildup
and superior in cut resistance compared to a conventional
diene-based rubber, the conventionally arranged under tread is not
necessarily needed.
[0130] When there is no cover layer between the belt layer and
tread layer and it is desired to secure the same thickness from the
bottom of the tread grooves to the belt as in the past or when
there is a cover layer between the belt layer and tread, the cover
layer is comprised of reinforcing cord coated by a rubber
composition containing hydrogenated NBR, and it is desired to
secure the same thickness from the bottom of the tread grooves to
the cover layer as in the past, that portion (portion where
conventional under tread has been positioned) is preferably also
comprised by a rubber containing the hydrogenated NBR.
[0131] According to a ninth aspect of the present invention, as a
first aspect, as shown in FIG. 8, the rubbers of the carcass coat,
belt coat, and bead filler are comprised a of rubber containing the
hydrogenated NBR. In this case, since the rubber containing the
hydrogenated NBR is high in strength, a tire lateral rigidity equal
to that of the past can be obtained even if making the volume of
the bead filler smaller and the driving stability will not decline.
Further, since the heat buildup is small, the rolling resistance
will not increase, and therefore the rubber can be preferably used
for the bead filler rubber.
[0132] Further, if comprising the bead filler by the rubber
containing hydrogenated NBR as well, since there is no need for a
bonding rubber layer between the carcass coat and the bead filler,
the rolling resistance can be further reduced and the productivity
is improved, which is more preferable.
[0133] According to the present invention, as a second embodiment,
as shown in FIG. 9, the carcass coat and belt coat, bead filler,
and side wall are comprised of the rubber containing the
hydrogenated NBR. In this case, since the rubber containing the
hydrogenated NBR is superior in resistance to ozone deterioration,
pollution resistance, and cut resistance and further features low
heat buildup, it is preferable as a side wall achieving both cut
resistance and low rolling resistance with reduced weight. Since it
is superior in cut resistance, if the carcass coat rubber is
comprised of a rubber containing the hydrogenated NBR, the cut
resistance will not decline even if making the side wall thinner.
Further, since the heat buildup is small, there is the effect that
the rolling resistance is reduced.
[0134] Further, if the side wall is comprised of the rubber
containing the hydrogenated NBR, the bonding rubber layer with the
carcass becomes unnecessary, and therefore the rolling resistance
can be further reduced and the productivity is improved as well,
which is more preferable.
[0135] Further, when making both the bead filler and the side wall
a rubber containing the hydrogenated NBR, the bonding rubber layers
among the carcass, bead filler, and side wall become unnecessary,
which is further preferable.
[0136] According to the present invention, as a third embodiment,
the carcass coat, belt coat, bead filler, side wall, rim cushion,
and chafer shown in FIG. 10 are comprised of a rubber containing
the hydrogenated NBR. In this case, since the rubber containing the
hydrogenated NBR has a higher hardness, lower heat buildup, and
higher strength compared with a conventional diene-based rubber, it
is preferable as the chafer of the bead portion and rim cushion.
Since it is high in hardness, the movement of the bead portion is
suppressed and the driving stability is improved. Further, since
the rubber is high in strength and superior in crack resistance,
there is the effect that the bead toe portion will not easily break
even with repeated rim attachment and rim detachment.
[0137] Further, if the chafer and rim cushion are also comprised of
a rubber containing the hydrogenated NBR, the bonding rubber layer
with the carcass becomes unnecessary and the productivity is
improved, and therefore this is more preferable. Further, when the
bead filler and side wall are also comprised of the rubber
containing the hydrogenated NBR and further the chafer and rim
cushion are comprised of the rubber containing the hydrogenated
NBR, the bonding rubber layers among the carcass, bead filler, side
wall, rim cushion, and chafer become unnecessary, and therefore
this is further preferable.
[0138] According to a 10th aspect of the present invention, as a
first embodiment, a diene-based rubber or/and a butyl-based rubber
is used for the cap tread shown in FIG. 11, at least one type of
rubber selected from the group consisting of a diene-based rubber,
chloroprene-based rubber, butyl-based rubber,
ethylene-propylene-based rubber, nitrile-based rubber, and
hydrin-based rubber is used for the bead insulation, and a rubber
containing the hydrogenated NBR is used for the rubber of other
portions.
[0139] Further, as a second embodiment, a diene-based rubber or/and
a butyl-based rubber is used for the cap tread shown in FIG. 11 and
a rubber containing the hydrogenated NBR is used for the rubber of
other portions. As in these cases, if all of the rubber except for
the cap tread or all of the rubber except for the cap tread and the
bead insulation is comprised by a rubber containing the
hydrogenated NBR and a bonding rubber layer is provided with the
cap tread, the bonding rubber layer becomes unnecessary other than
with the cap tread. Therefore, it becomes possible to produce a
green tire with no cap tread in advance by a better productivity
since there is no bonding rubber layer, then attach the cap tread
along with the bonding rubber layer to complete the green tire, and
therefore it is possible to obtain a high performance tire with a
low rolling resistance, reduced weight, superior cut resistance,
and good productivity.
[0140] Further, since the rubber containing the hydrogenated NBR
has a good abrasion resistance and low heat buildup, it may be used
as the cap tread as well, but it is preferable to use a cap tread
of a conventional diene-based rubber formulation in order to
achieve braking performance, wet performance, and other grip
performance and abrasion resistance and low heat buildup with a
good balance.
[0141] According to the 11th aspect of the present invention, the
bead insulation rubber shown in FIG. 10 is comprised by at least
one type of rubber selected from the group consisting of a
diene-based rubber, chloroprene-based rubber, butyl-based rubber,
ethylene-propylene-based rubber, nitrile-based rubber, and
hydrin-based rubber, and the bonding rubber layer is not provided
between the bead insulation and the adjoining rubber composition
containing the hydrogenated NBR. In the case of this structure, the
strain occurring when using the tire is extremely small in just the
bead insulation rubber covering the bead wire. There is no problem
in durability even if the bonding with the adjoining rubber is
weak, and therefore the bonding rubber layer is not necessary.
[0142] According to a 12th aspect of the present invention, as a
first embodiment, the bead insulation rubber shown in FIG. 10 is
comprised by at least one type of rubber selected from the group
consisting of a diene-based rubber, chloroprene-based rubber,
butyl-based rubber, ethylene-propylene-based rubber, nitrile-based
rubber, and hydrin-based rubber and the rubber at other portions is
comprised of the rubber containing the hydrogenated NBR. In this
case, the strain occurring when using the tire is extremely small
in just the bead insulation rubber covering the bead wire. There is
no problem in durability even if the bonding with the adjoining
rubber is weak, and therefore the bonding rubber layer is not
necessary between the bead insulation rubber and the adjoining
rubber. In the end, therefore, it is possible to produce a tire not
requiring bonding rubber layers.
[0143] According to the present invention, as a second embodiment,
it is possible to comprise the rubber of all portions constituting
the tire shown in FIG. 10 by a rubber containing hydrogenated NBR.
In this case, since the rubber containing the hydrogenated NBR is
superior in strength, low heat buildup, cut resistance, and other
physical properties, there is no need to change the formulation for
each member like with a conventional tire. Therefore, since the
types of rubber formulations required for a single tire are
reduced, it is possible to improve the productivity. Further, since
it is possible to produce a green tire without a cap tread by
extrusion, then attaching the cap tread together with the bonding
rubber layer to complete the green tire, it is possible to further
improve the productivity. Note that the thus obtained tire is also
suitable as a high performance tire with a low rolling resistance
and a base tire for retreading.
[0144] According to a 13th aspect of the present invention, it is
possible to provide a pneumatic tire using a rubber containing the
hydrogenated NBR colored a color other than black at least at part
or all of the inside and outside surface of the tire. In this case,
since the rubber containing the hydrogenated NBR is superior in
strength, low heat buildup, cut resistance, and other physical
properties and can improve the strength using only zinc
methacrylate even if not containing carbon black, it is possible to
color the rubber any color other than black without detracting from
the above physical properties. By using a rubber containing the
hydrogenated NBR colored a color other than black and positioning
it at part or all of the inside or outside surface of the parts
arranged at the inside and outside surfaces of the tire, it is
possible to obtain an aesthetic effect for the tire while
maintaining the above physical properties.
[0145] In a tire according to the 14th aspect of the present
invention, since the rubber containing the hydrogenated NBR used
here has a low air permeation coefficient, the conventionally
provided inner liner is not necessarily required. Therefore, it is
possible to reduce the weight by that amount.
[0146] Further, the cushion rubber shown in FIG. 10, which had in
the past been arranged between layers of the belt ends and between
the belt end and carcass, is preferably comprised by the rubber
containing the hydrogenated NBR together with the carcass and belt.
When comprising the carcass and belt by the rubber containing the
hydrogenated NBR, however, there is leeway in the durability, and
therefore the cushion rubber is not necessarily required.
EXAMPLES
[0147] The present invention will now be explained by Examples, but
the present invention is of course not limited to these
Examples.
[0148] The following commercial products were used for the
ingredients of the formulations of the following Standard Examples
1 to 3, Examples 1 to 27, and Comparative Examples 1 to 16. Note
that blending agents not changed in amount are not listed in the
tables of the examples.
1 1) Ingredients of Formulations of Cap Treads SBR: Nipol NS-116
(made by Nippon Zeon) variate NR: RSS#3 variate HNBR (hydrogenated
NBR): Zetpol 2020 variate (made by Nippon Zeon) Zinc methacrylate:
R-20S (made by variate Asada Chemical Industry) Carbon black: N339
(made by Showa variate Cabot) Organic peroxide (40% diluted): 5
parts Parkadox 14/40 (made by Kayaku Akzo) by weight Antioxidant:
Nauguard 445 (made by 1.5 parts Uniroyal) by weight 2) Ingredients
of Formulations of Under Tread NR: RSS#3 variate BR: Nipol BR-1220
(made by Nippon Zeon) variate HNBR: Zetpol 2020 (made by Nippon
Zeon) variate Zinc methacrylate: R-20S (made by variate Asada
Chemical Industry) Carbon black (FEF grade): HTC-100 variate (made
by Shinnikka Carbon) Organic peroxide (40% diluted): 5 parts
Parkadox 14/40 (made by Kayaku Akzo) by weight Antioxidant:
Nauguard 445 (made by 1.5 parts Uniroyal) by weight 3) Ingredients
of Formulations of Bonding Rubber Layer NR: RSS#3 variate NBR:
Nipol DN401 (made by Nippon Zeon) variate Carbon black: N339 (made
by Showa 50 parts Cabot) by weight Aromatic petroleum resin: FR-120
variate (made by Fujikosan) Zinc oxide: Zinc White #3 (made by 5
parts Seido Chemical Industry) by weight Stearic acid: Beads
Stearic Acid (made 1 part by Nippon Oil and Fat) by weight
Antioxidant: Nocrac 224 (made by Ouchi 1 part Shinko Chemical) by
weight Sulfur: Insoluble sulfur 2 parts by weight (case of sulfur
vulcanization based formulation) Vulcanization accelerator:
Nocceler CZ-G 1 part (made by Ouchi Shinko Chemical) by weight
(case of sulfur vulcanization based formulation) Vulcanization
accelerator: Nocceler 0.5 part TOT-N (made by Ouchi Shinko
Chemical) by weight (case of sulfur vulcanization based
formulation) Organic peroxide (40% diluted): 3.5 parts Parkadox
14/40 (made by Kayaku Akzo) by weight (case of organic peroxide
cross-linking based formulation) Co-cross-linking agent: TAIC (made
by 3 parts Nippon Kasei Chemical) by weight (case of organic
peroxide cross-linking based formulation)
Fabrication of Test Tires
[0149] Test tires (size: 185/65R14) were fabricated in accordance
with the tire configurations of the examples from the cap treads,
under treads, and bonding rubber layers comprised of the
compositions of the formulations shown in the Examples and were
used for the following predetermined tests:
[0150] The test and evaluation methods in the examples were as
follows:
[0151] 1) High Speed Durability Test Method
[0152] A drum tester having a smooth drum surface, made of steel,
and having an inside diameter of 1707 mm was used, the ambient
temperature was controlled to 38.+-.3.degree. C., and the tires
were run to warm up under conditions of a rim size of 14.times.5
1/2JJ, an internal pressure of 220 kPa, a load of 4.36 kN, and a
speed of 81 km/h for 120 minutes. The tires were then allowed to
cool for at least 3 hours, then were readjusted to the test air
pressure and the main running was commenced.
[0153] The main running was started at a speed of 121 km/h. The
speed was increased in steps of 8 km/h every 30 minutes of running
and the tires were run until trouble occurred. The distance run
until the trouble occurred in the tires was expressed indexed to
the distance of occurrence of trouble of a conventional tire as 100
and used as the high speed durability. (The larger the value, the
better.)
[0154] 2) Abrasion Test Method
[0155] Test tires were mounted on the four wheels of a 1.6 liter
engine displacement compact passenger car. This was driven 10,000
km on a predetermined course and the average amount of abrasion for
the four tires was measured. The result was expressed indexed to
the amount of abrasion of a conventional tire as 100. (The smaller
the value, the more resistant to abrasion.)
[0156] 3) Rolling Resistance Test Method
[0157] Tires were run under the following conditions to measure the
rolling resistance at that time. The results were expressed indexed
to the measured value for a conventional tire as 100. (The smaller
the value, the better.)
[0158] Running conditions: A drum tester having a smooth drum
surface, made of steel, and having an inside diameter of 1707 mm
was used, the ambient temperature was controlled to 23.+-.2.degree.
C., and the tires were run under conditions of a rim size of
14.times.5 1/2JJ, an internal pressure of 200 kPa, and a speed of
80 km/h.
[0159] 4) Vehicular Driving Stability Test Method
[0160] Test tires mounted on 14.times.5 1/2JJ rims at an internal
pressure of 200 kPa were mounted on a 1.6 liter engine displacement
front engine front wheel drive compact passenger car. The car was
driven over a test course by five trained drivers to evaluate the
feeling. The results were ranked by a five-point system based on
the following judgement criteria in relative comparison with
reference tires. The average of the three drivers, not including
the highest score and lowest score, was shown. (The larger the
values, the better.)
[0161] Judgement criteria:
[0162] 5: Excellent, 4: good, 3.5: somewhat good, 3: equal to
reference, 2.5: somewhat poor (practical lower limit), 2: poor, 1:
very poor
[0163] 5) High Load Durability Test Method
[0164] Tires were run under the following conditions and ranked as
"no good" (poor) when trouble occurred and "OK" (good) when it did
not.
[0165] Running conditions: A drum tester having a smooth drum
surface, made of steel, and having an inside diameter of 1707 mm
was used, the ambient temperature was controlled to 38.+-.3.degree.
C., and the tires were run under conditions of a rim size of
14.times.5 1/2JJ, an internal pressure of 240 kPa, and a speed of
81 km/h. The initial load was made 4.57 kN, then the load was
increased to a load of 7.28 kN in 0.68 kN increments every 2 hours.
After this, the load was increased to a load of 14.0 kN in 0.68 kN
increments every 4 hours. The test was ended when running at a load
of 14.0 kN for 4 hours.
Standard Examples 1 to 2, Examples 1 to 8, and Comparative Examples
1 to 4 (Cap Tread)
[0166] The results of tests on the high speed durability, abrasion,
and rolling resistance of test tires in the case of changing the
ratio of ingredients in the formulations of the cap tread and
leaving the composition of the bonding rubber layer and the tire
configuration constant are shown in the following Table I.
2TABLE I (Test Tire Size: 185/65R14) Stand. Stand. Comp. Comp. Ex.
1 Ex. 2 Ex. 1 Ex. 2 Ex. 1 Ex. 2 Ex. 3 Cap tread formulation SBR
(phr) 50 100 NR (phr) 50 40 30 20 HBR (phr) 100 60 70 80 100 Rubber
total (phr) 100 100 100 100 100 100 100 Zinc methacrylate (phr) 60
60 60 60 60 Carbon (phr) 50 75 0 0 0 0 0 Total of zinc methacrylate
+ carbon 50 75 60 60 60 60 60 (phr) Bonding rubber layer
formulation*1 NR (phr) -- -- 60 60 60 60 NBR (phr) -- -- 40 40 40
40 Aromatic petroleum resin (phr) -- -- 40 40 40 40 Sulfur (phr) --
-- 2 2 2 2 Vulcanization accelerator (CZ) (phr) -- -- 1 1 1 1
Vulcanization accelerator (TOT-N) -- -- 0.5 0.5 0.5 0.5 (phr) Tire
structure Cap tread thickness (mm) 9.9 9.9 9.5 9.7 9.7 9.7 9.7
Groove thickness (mm) 8.6 8.6 8.6 8.6 8.6 8.6 8.6 Bonding rubber
layer thickness (mm) -- -- 0.4 0.2 0.2 0.2 0.2 Under tread
thickness (mm) 1 1 1 1 1 1 1 Tread total thickness (mm) 10.9 10.9
10.9 10.9 10.9 10.9 10.9 Test results High speed durability (index)
100 100 82 104 104 104 104 Abrasion (index) 102 100 70 102 93 80 70
Rolling resistance (index) 100 101 97 99 98 98 97 Comp. Comp. Ex. 3
Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Ex. 4 Cap tread formulation SBR (phr)
NR (phr) 30 30 30 30 30 30 30 HBR (phr) 70 70 70 70 70 70 70 Rubber
total (phr) 100 100 100 100 100 100 100 Zinc methacrylate (phr) 5
10 10 0 80 80 85 Carbon (phr) 5 40 0 40 45 Total of zinc
methacrylate + carbon 5 10 10 40 80 120 130 (phr) Bonding rubber
layer formulation NR (phr) 60 60 60 60 60 60 60 NBR (phr) 40 40 40
40 40 40 40 Aromatic petroleum resin (phr) 40 40 40 40 40 40 40
Sulfur (phr) 2 2 2 2 2 2 2 Vulcanization accelerator (CZ) (phr) 1 1
1 1 1 1 1 Vulcanization accelerator (TOT-N) 0.5 0.5 0.5 0.5 0.5 0.5
0.5 (phr) Tire structure Cap tread thickness (mm) 9.7 9.7 9.7 9.7
9.7 9.7 9.7 Groove thickness (mm) 8.6 8.6 8.6 8.6 8.6 8.6 8.6
Bonding rubber layer thickness (mm) 0.2 0.2 0.2 0.2 0.2 0.2 0.2
Under tread thickness (mm) 1 1 1 1 1 1 1 Tread total thickness (mm)
10.9 10.9 10.9 10.9 10.9 10.9 10.9 Test results High speed
durability (index) 104 104 104 104 104 104 104 Abrasion (index) 101
99 98 95 92 99 102 Rolling resistance (index) 98 98 98 99 99 100
100 *1Bonding layer is two-layer structure of isobutylene-isoprene
copolymer (IIR) rubber layer and ultrahigh molecular weight
polyethylene (UHMwPE) sheet.
[0167] From the results of Table I, the tires of the examples using
the cap treads having the compositions of formulations in
accordance with the present invention all exhibited the desired
superior high speed durability, low abrasion, and low rolling
resistance.
Examples 9 to 13 and Comparative Examples 5 to 8 (Cap Tread)
[0168] The results of tests on the high speed durability, abrasion,
and rolling resistance of test tires in the case of changing the
ratio of ingredients in the formulations of the bonding rubber
layer and leaving the composition of the cap tread and the tire
configuration constant are shown in the following Table II.
3TABLE II (Test Tire Size: 185/65R14) Comp. Comp. Comp. Comp. Ex. 5
Ex. 9 Ex. 10 Ex. 11 Ex. 6 Ex. 7 Ex. 12 Ex. 13 Ex. 8 Cap tread
formulation NR (phr) 30 30 30 30 30 30 30 30 30 HBR (phr) 70 70 70
70 70 70 70 70 70 Rubber total (phr) 100 100 100 100 100 100 100
100 100 Zinc methacrylate (phr) 60 60 60 60 60 60 60 60 60 Carbon
(phr) 0 0 0 0 0 0 0 0 0 Total of zinc 60 60 60 60 60 60 60 60 60
methacrylate + carbon (phr) Bonding rubber layer formulation NR
(phr) 0 10 50 90 100 60 60 60 60 NBR (phr) 100 90 50 10 0 40 40 40
40 Aromatic petroleum resin 40 40 40 40 40 0 5 80 90 (phr) Sulfur
(phr) 2 2 2 2 2 2 2 2 2 Vulcanization accelerator 1 1 1 1 1 1 1 1 1
(CZ) (phr) Vulcanization accelerator 0.5 0.5 0.5 0.5 0.5 0.5 0.5
0.5 0.5 (TOT-N) (phr) Tire structure Cap tread thickness (mm) 9.7
9.7 9.7 9.7 9.7 9.7 9.7 9.7 9.7 Groove thickness (mm) 8.6 8.6 8.6
8.6 8.6 8.6 8.6 8.6 8.6 Bonding rubber layer 0.2 0.2 0.2 0.2 0.2
0.2 0.2 0.2 0.2 thickness (mm) Under tread thickness 1 1 1 1 1 1 1
1 1 (mm) Tread total thickness 10.9 10.9 10.9 10.9 10.9 10.9 10.9
10.9 10.9 (mm) Test results High speed durability 82 103 104 102 83
97 104 102 101 (index) Abrasion (index) 93 93 93 93 93 93 93 93 93
Rolling resistance 97 97 97 97 97 97 97 100 102 (index)
[0169] From the results of Table II, the tires of the examples
bonding the cap treads using bonding rubber layers of compositions
of formulations in accordance with the present invention all
exhibited the desired superior high speed durability, low abrasion,
and low rolling resistance.
Examples 14 to 18 and Comparative Example 9 (Cap Tread)
[0170] The results of tests on the high speed durability, abrasion,
and rolling resistance of test tires in the case of leaving the
ingredients in the formulations of the cap tread and bonding rubber
layer constant and changing the thicknesses of the cap tread and
bonding rubber layer in the tire configurations are shown in the
following Table III.
4TABLE III (Test Tire Size: 185/65R14) Comp. Ex. 9 Ex. 14 Ex. 15
Ex. 15 Ex. 17 Ex. 18 Cap tread formulation NR (phr ) 30 30 30 30 30
30 HBR (phr) 70 70 70 70 70 70 Rubber total (phr) 100 100 100 100
100 100 Zinc methacrylate (phr) 60 60 60 60 60 60 Carbon (phr) 0 0
0 0 0 0 Total of zinc methacrylate + carbon 60 60 60 60 60 60 (phr)
Bonding rubber layer formulation NR (phr) 60 60 60 60 60 60 NBR
(phr) 40 40 40 40 40 40 Aromatic petroleum resin (phr) 40 40 40 40
40 40 Sulfur (phr) 2 2 2 2 2 0 Vulcanization accelerator (CZ) (phr)
1 1 1 1 1 Vulcanization accelerator (TOT-N) 0.5 0.5 0.5 0.5 0.5
(phr) Cross-linking agent (TAIC) (phr) 3 Organic peroxide (phr) 1.4
Tire structure Cap tread thickness (mm) 9.7 9.7 9.7 9.7 10.7 9.7
Groove thickness (mm) 8.6 8.6 8.6 8.6 8.6 8.6 Bonding rubber layer
thickness (mm) 0 0.1 0.2 4 0.2 0.2 Under tread thickness (mm) 1 1 1
1 0 1 Tread total thickness (mm) 10.7 10.8 10.9 14.7 10.9 10.9 Test
results High speed durability (index) 80 104 104 101 106 110
Abrasion (index) 93 93 93 93 97 93 Rolling resistance (index) 99 99
99 100 96 97
[0171] From the results of Table III, the tires of the examples
having thicknesses of bonding rubber layers in accordance with the
present invention and using cap treads of predetermined thicknesses
(7 to 10.7 mm thickness) all exhibited the desired superior high
speed durability, low abrasion, and low rolling resistance.
Standard Example 3, Examples 19 to 23, and Comparative Examples 10
to 15 (Under Tread)
[0172] The results of tests on the vehicular driving stability,
high speed durability, and high load durability of test tires in
the case of changing the ratio of ingredients in the formulations
of the under tread and leaving the composition of the bonding
rubber layer and the tire configuration constant are shown in the
following Table IV.
5TABLE IV (Test Tire Size: 185/65R14) Stand. Comp. Comp. Ex. 3 Ex.
10 Ex. 19 Ex. 20 Ex. 11 Ex. 21 Under tread formulation NR (phr) 70
70 60 30 30 BR (phr) 30 30 HNBR (phr) 40 100 70 70 Zinc
methacrylate (phr) 0 0 0 0 Carbon (FEF grade) (phr) 60 80 40 40 5
10 Bonding rubber layer formulation NR (phr) -- -- 60 60 60 60 NBR
(phr) -- -- 40 40 40 40 Aromatic petroleum resin (phr) -- -- 40 40
40 40 Sulfur (phr) -- -- 2 2 2 2 Vulcanization accelerator (CZ)
(phr) -- -- 1 1 1 1 Vulcanization accelerator (TOT-N) -- -- 0.5 0.5
0.5 0.5 (phr) Tire structure Under tread thickness (mm) 1.5 1.5 1.1
1.1 1.1 1.1 Bonding rubber layer thickness (mm) -- -- 0.2 .times. 2
0.2 .times. 2 0.2 .times. 2 0.2 .times. 2 Under tread total
thickness (mm) 1.5 1.5 1.5 1.5 1.5 1.5 Test results Vehicular
driving stability 3 3.2 3.2 3.2 2.8 3 High speed durability (index)
100 97 103 104 106 105 High load durability Good Good Good Good
Good Good Comp. Comp. Comp. Comp. Ex. 12 Ex. 13 Ex. 22 Ex. 23 Ex.
14 Ex. 15 Under tread formulation NR (phr) 30 30 30 30 30 30 BR
(phr) NNBR (phr) 70 70 70 70 70 70 Zinc methacrylate (phr) 0 5 10
120 130 100 Carbon (FEF grade) (phr) 45 0 0 0 0 30 Bonding rubber
layer formulation NR (phr) 60 60 60 60 60 60 NBR (phr) 40 40 40 40
40 40 Aromatic petroleum resin (phr) 40 40 40 40 40 40 Sulfur (phr)
2 2 2 2 2 2 Vulcanization accelerator (CZ) (phr) 1 1 1 1 1 1
Vulcanization accelerator (TOT-N) 0.5 0.5 0.5 0.5 0.5 0.5 (phr)
Tire structure Under tread thickness (mm) 1.1 1.1 1.1 1.1 1.1 1.1
Bonding rubber layer thickness (mm) 0.2 .times. 2 0.2 .times. 2 0.2
.times. 2 0.2 .times. 2 0.2 .times. 2 0.2 .times. 2 Under tread
total thickness (mm) 1.5 1.5 1.5 1.5 1.5 1.5 Test results Vehicular
driving stability 3.2 2.8 3 3.3 3.3 3.3 High speed durability
(index) 98 108 108 106 104 102 High load durability Good Good Good
Good Poor Poor
[0173] From the results of Table IV, the tires of the examples
using under treads having compositions of formulations in
accordance with the present invention all exhibited the desired
superior vehicular driving stability, high speed durability, and
high load durability.
Examples 24 to 27 and Comparative Example 16 (Under Tread)
[0174] The results of tests on the vehicular driving stability,
high speed durability, and high load durability of test tires in
the case of leaving the composition of formulations in the under
tread and bonding rubber layer constant and changing the
thicknesses of the under tread and bonding rubber layer of the tire
configuration are shown in the following Table V.
6TABLE V (Test Tire Size: 185/65R14) Comp. Ex. 16 Ex. 24 Ex. 25 Ex.
26 Ex. 27 Under tread formulation NR (phr) 30 30 30 30 30 NNBR
(phr) 70 70 70 70 70 Zinc methacrylate (phr) 70 70 70 70 70 Carbon
(FEF grade) (phr) 10 10 10 10 10 Bonding rubber layer formulation*1
NR (phr) -- 60 60 60 60 NBR (phr) -- 40 40 40 40 Aromatic petroleum
resin (phr) -- 40 40 40 40 Sulfur (phr) -- 2 2 2 Vulcanization
accelerator (CZ) (phr) -- 1 1 1 1 Vulcanization accelerator (TOT-N)
(phr) -- 0.5 0.5 0.5 0.5 Cross-linking agent (TAIC) (phr) -- 3
Organic peroxide (phr) -- 1.4 Tire structure Under tread thickness
(mm) 0.9 1.1 1.3 0.9 0.5 Bonding rubber layer thickness (mm) 0.3
.times. 2 0.2 .times. 2 0.1 .times. 2 0.3 .times. 2 0.5 .times. 2
Under tread total thickness (mm) 1.5 1.5 1.5 1.5 1.5 Test results
Vehicular driving stability 3.2 3.2 3.3 3.2 3.2 High speed
durability (index) 82 110 105 103 101 High load durability Poor
Good Good Good Good
[0175] From the results of Table V, the tires of the examples
having the thicknesses of the under treads and bonding rubber
layers in accordance with the present invention all exhibited the
desired superior vehicular driving stability, high speed
durability, and high load durability.
[0176] The following commercial products were used-for the
ingredients of the formulations used for the examples of the
following Standard Example 4, Examples 28 to 49, and Comparative
Examples 17 to 26. Note that blending agents not changed in amount
are not listed in the tables of the examples.
7 1) Ingredients of Formulations of Reinforcing Liner Layer of Side
Wall Portion Hydrogenated NBR: Zetpol 2020 variate (made by Nippon
Zeon) Zinc methacrylate: R-20S (made by variate Asada Chemical
Industry) Carbon black: N339 (made by Showa variate Cabot) Organic
peroxide (40% diluted): 5 parts Parkadox 14/40 (made by Kayaku
Akzo) by weight Antioxidant: Nauguard 445 (made by 1.5 parts
Uniroyal) by weight 2) Ingredients of Formulation of Bonding Rubber
Layer Diene-based rubber (NR): RSS#3 variate NBR: Nipol DN401 (made
by Nippon Zeon) variate Carbon black: N339 (made by Showa 50 parts
Cabot) by weight Aromatic petroleum resin: FR-120 variate (made by
Fujikosan) Zinc oxide: Zinc White #3 (made by 5 parts Seido
Chemical Industry) by weight Stearic acid: Beads Stearic Acid 1
part (made by Nippon Oil and Fat) by weight Antioxidant: Nocrac 224
(made by Ouchi 1 part Shinko Chemical) by weight Sulfur: Insoluble
sulfur 2 parts by weight (sulfur vulcanization based) Vulcanization
accelerator: Nocceler 1 part CZ-G (made by Ouchi Shinko Chemical)
by weight (sulfur vulcanization based) Vulcanization accelerator:
Nocceler 0.5 part TOT-N (made by Ouchi Shinko Chemical) by weight
(sulfur vulcanization based) Organic peroxide (40% diluted):
variate Parkadox 14/40 (made by Kayaku Akzo) (organic peroxide
cross-linking based) Co-cross-linking agent: TAIC (made by variate
Nippon Kasei Chemical) (organic peroxide cross-linking based)
[0177] Further, the rubber formulations A and B used in Standard
Example 4 and Comparative Example 17 of Table VI were as
follows:
8 A B (Parts (Parts by by Conventional rubber formulation weight)
weight) NR: RSS#3 40 40 BR: Nipol BR1220 (made by Nippon 60 60
Zeon) Carbon black: N326M (made by Showa 60 80 Cabot) Zinc oxide:
Zinc White #3 (made by 5 5 Seido Chemical Industry) Stearic acid:
Beads Stearic Acid 1 1 (made by Nippon Oil and Fat) Antioxidant:
Nocrac 6C (made by 2 2 Ouchi Shinko Chemical) Phenol resin:
Sumicanol 610 (made 6 6 by Sumitomo Chemical) Sulfur: Insoluble
sulfur 5 5 Vulcanization accelerator: 2 2 Nocceler NS-F (made by
Ouchi Shinko Chemical)
Fabrication of Test Run Flat Tires
[0178] The reinforcing liner layers and bonding layers comprised of
compositions of the formulations shown in the Examples were shaped
by conventional techniques and arranged and bonded to give the
predetermined positional relationships shown in FIGS. 1(a) to 1(e).
Run flat tires of a size of 255/40R17 were fabricated and used for
run flat durability tests, rolling resistance tests, and riding
comfort tests.
[0179] The methods of measurement and evaluation in the Examples
were as follows:
[0180] 1) Run Flat Durability Test Method
[0181] Test tires were mounted on a vehicle given a load of 4.90
kN/tire at an air pressure of 0 kPa in a manner so that the tires
would not detach from the rims. The distances until the tires broke
were measured. The Examples show values indexed to a conventional
tire as 100. The larger the index, the better the run flat
durability shown.
[0182] 2) Rolling Resistance Test Method
[0183] Tires were run under the following conditions to measure the
rolling resistance at that time. The results were expressed indexed
to the measured value for a conventional tire as 100. The smaller
the value, the better.
[0184] Running conditions: A drum tester having a smooth drum
surface, made of steel, and having an inside diameter of 1707 mm
was used, the ambient temperature was controlled to 23.+-.2.degree.
C.,and the tires were run under conditions of a rim size of
17.times.9JJ, an internal pressure of 220 kPa, a load of 5.5 kN,
and a speed of 80 km/h.
[0185] 3) Riding Comfort Test Method
[0186] Test tires were mounted on 17.times.9JJ rims, filled at an
internal pressure of 220 kPa, and mounted on a passenger car. The
car was driven over a test course by five trained drivers to
evaluate the feeling. The results were ranked by a five-point
system based on the following judgement criteria in relative
comparison with reference tires. The average of the three drivers,
not including the highest score and lowest score, was classified as
follows.
[0187] Judgement criteria
[0188] 5: Excellent, 4: good, 3: equal to reference, 2: poor, 1:
very poor
[0189] Classification
[0190] Average score larger than reference (3 points): Very
good
[0191] Equal to reference: Good
[0192] Less than reference: Poor
Standard Example 4, Examples 28 to 49, and Comparative Examples 17
to 26 (Reinforcing Liner of Side Wall Portion)
[0193] The results of the measurement and evaluation of the run
flat tires in the examples are shown in Table VI.
9TABLE VI (Run Flat Tire: Tire Size: 255/40R17) Standard Comp.
Comp. Comp. Comp. Ex. 4 Ex. 17 Ex. 18 Ex. 28 Ex. 19 Ex. 29 Ex. 30
Ex.19 Ex. 31 <Reinforcing liner layer> Formulation
Conventional Conven- C C D E F G H rubber tional formulation rubber
formu- lation A B Hydrogenated NBR (parts by weight) -- -- 100 100
60 (under 70 (lower 100 100 100 (standard) (standard) low limit)
limit) (stand.) Zinc methacrylate (parts by weight) -- -- 80 80 80
80 80 10 (<low 20 (low (standard) (standard) limit) limit)
Carbon black (parts by weight) 60 80 0 0 0 0 0 0 0 Zinc
methacrylate and carbon black 60 80 80 80 80 80 80 10 20 total
(parts by weight) Maximum thickness (mm) 4.0 4.0 4.0 4.0 4.0 4.0
4.0 4.0 4.0 Reinforcing liner layer and belt layer Yes Yes Yes Yes
Yes Yes Yes Yes Yes overlap Reinforcing liner layer and bead Yes
Yes Yes Yes Yes Yes Yes Yes Yes filler overlap <Bonding
layer> Existence of bonding layer and its -- -- 2-layer*1 P P P
P P P structure and formulation Ratio A:B of (A) diene-based rubber
-- -- -- 50:50 50:50 50:50 50:50 50:50 50:50 and (B) NBR (C)
Aromatic petroleum resin to 100 -- -- -- 30 30 30 30 30 30 parts by
weight of (A) + (B) (parts by (standard) (stand.) weight) Sulfur
(parts by weight) -- -- -- 2 2 2 2 2 2 Vulcanization accelerator CZ
-- -- -- 1 1 1 1 1 1 (parts by weight) Vulcanization accelerator
TOT-N -- -- -- 0.5 0.5 0.5 0.5 0.5 0.5 (parts by weight)
Cross-linking agent (TAIC) (parts by -- -- -- 0 0 0 0 0 0 weight)
Organic peroxide (parts by Weight) -- -- -- 0 0 0 0 0 0 Thickness
(mm) -- -- IIR:0.4 0.5 0.5 0.5 0.5 0.5 0.5 UHMwPE: 0.1 Bead area
structure FIG. 1 (a) FIG. 1 (a) FIG. 1 (a) FIG. 1 (a) FIG. 1 (a)
FIG. 1 (a) FIG. 1 (a) FIG. 1 (a) FIG. 1 (a) Bead filler height (mm)
32 32 32 32 32 32 32 32 32 Bead filler JIS (A) hardness 75 75 75 75
75 75 75 75 75 Run flat durability (index) -> 100 85 87 110 82
(soft) 103 117 87 (soft) 107 larger, the better (breaks) (adhesion)
Rolling resistance (index) -> 100 103 98 93 92 94 95 94 94
smaller, the better Riding comfort Good Good Good Good Very Good
Good Very Good Good Good Comp. Comp. Comp. Ex. 32 Ex. 20 Ex. 33 Ex.
21 Ex. 34 Ex. 35 Ex. 22 Ex. 36 Ex. 37 <Reinforcing liner
layer> Formulation I J K L C C C C C Hydrogenated NBR (parts by
weight) 100 100 100 100 100 100 100 100 100 (stand.) (stand)
(stand) Zinc methacrylate (parts by weight) 120 (hi 130 (>hi 80
80 80 80 80 80 80 limit) limit) (stand) (stand) Carbon black (parts
by weight) 0 0 40 (hi 45 (>hi 0 0 0 0 0 limit) limit) Zinc
methacrylate and carbon black 120 130 (>hi 120 (hi 125 (>hi
80 80 80 80 80 total (parts by weight) limit) limit) limit) Maximum
thickness (mm) 4.0 4.0 4.0 4.0 4.0 4.0 4.0 4.0 4.0 Reinforcing
liner layer and belt Yes Yes Yes Yes Yes Yes Yes Yes Yes layer over
lap Reinforcing liner layer and bead Yes Yes Yes Yes Yes Yes Yes
Yes Yes filler overlap <Bonding layer> Existence of bonding
layer and its P P P P Q R S T U structure and formulation Ratio A:B
of (A) diene-based rubber 50:50 50:50 50:50 50:50 10:90 90:10 50:50
50:50 50:50 and (B) NBR (C) Aromatic petroleum resin to 100 30 30
30 (stand.) 30 30 (stand) 30 3 5 (low 80 (hi parts by weight of (A)
+ (B) (parts limit) limit) by weight) Sulfur (parts by weight) 2 2
2 2 2 2 2 2 2 Vulcanization accelerator CZ (parts 1 1 1 1 1 1 1 1 1
by weight) Vulcanization accelerator TOT-N 0.5 0.5 0.5 0.5 0.5 0.5
0.5 0.5 0.5 (parts by weight) Cross-linking agent (TAIC) (parts 0 0
0 0 0 0 0 0 0 by weight) Organic peroxide (parts by weight) 0 0 0 0
0 0 0 0 0 Thickness (mm) 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Bead
area structure FIG. 1 (a) FIG. 1 (a) FIG. 1 (a) FIG. 1 (a) FIG. 1
(a) FIG. 1 (a) FIG. 1 (a) FIG. 1 (a) FIG. 1 (a) Bead filler height
(mm) 32 32 32 32 32 32 32 32 32 Bead filler JIS (A) hardness 75 75
75 75 75 75 75 75 75 Run flat durability (index) -> 105 89
(hard) 105 90 (bri- 108 104 95 (adhe- 127 117 larger, the better
title) sion) Rolling resistance (index) -> 96 95 94 94 95 96 96
95 96 smaller, the better Riding comfort Good Poor Good Poor Good
Good Good Good Good Comp. Comp. Comp. Ex. 23 Ex. 24 Ex. 38 Ex. 39
Ex. 40 Ex. 41 Ex. 25 Ex. 42 Ex. 43 <Reinforcing liner layer>
Formulation C C C C C C C C C Hydrogenated NBR (parts by 100 100
100 100 100 100 100 100 100 weight) (stand) (stand) (stand) Zinc
methacrylate (parts 80 80 (stand) 80 80 80 80 80 80 (stand) 80
(stand) by weight) Carbon black (parts by weight) 0 0 0 0 0 0 0 0 0
Zinc methacrylate and carbon black 80 80 80 80 80 80 80 80 80 total
(parts by weight) Maximum thickness (mm) 4.0 4.0 4.0 4.0 4.0 4.0
4.0 4.0 3.0 Reinforcing liner layer Yes Yes Yes Yes Yes Yes Yes Yes
Yes and belt layer overlap Reinforcing liner layer Yes Yes Yes Yes
Yes Yes Yes Yes Yes and bead filler overlap <Bonding layer>
Existence of bonding layer V P P P P P P U P and its structure and
formulation Ratio A:B of (A) diene- 50:50 50:50 50:50 50:50 50:50
50:50 50:50 50:50 50:50 based rubber and (B) NBR (C) Aromatic
petroleum resin to 100 85 30 (stand) 30 30 30 30 30 30 (stand) 30
(stand) parts by weight of (A) + (B) (parts by weight) Sulfur
(parts by weight) 2 2 2 2 2 2 2 0 2 Vulcanization accelerator 1 1 1
1 1 1 1 0 1 CZ (parts by weight) Vulcanization accelerator 0.5 0.5
0.5 0.5 0.5 0.5 0.5 0 0.5 TOT-N (parts by weight) Cross-linking
agent (TAIC) 0 0 0 0 0 0 0 3 0 (parts by weight) Organic peroxide
(parts by weight) 0 0 0 0 0 0 0 2 0 Thickness (mm) 0.5 0.05 0.1
(low 0.2 0.8 2.0 (hi 2.5 0.5 0.5 limit) limit) Bead area structure
FIG. 1 (a) FIG. 1 (a) FIG. 1 (a) FIG. 1 (a) FIG. 1 (a) FIG. 1 (a)
FIG. 1 (a) FIG. 1 (a) FIG. 1 (a) Bead filler height (mm) 32 32 32
32 32 32 32 32 32 Bead filler JIS (A) 75 75 75 75 75 75 75 75 75
hardness Run flat durability (index) -> 92 95 103 104 121 111 94
147 108 larger, the better (heat) (heat) Rolling resistance (index)
-> 94 94 94 95 95 96 97 96 92 smaller, the better Riding comfort
Good Good Good Good Good Good Good Good Good Comp. Ex. 44 Ex. 45
Ex. 46 Ex. 47 Ex. 26 Ex. 48 Ex. 49 <Reinforcing liner layer>
Formulation C C C C C C C Hydrogenated NBR (parts by weight) 100
100 100 100 100 100 100 Zinc methacrylate (parts by weight) 80 80
80 80 80 80 80 Carbon black (parts by weight) 0 0 0 0 0 0 0 Zinc
methacrylate and carbon black 80 80 80 80 80 80 80 total (parts by
weight) Maximum thickness (mm) 8.0 4.0 4.0 4.0 4.0 4.0 4.0
Reinforcing liner layer and belt Yes No Yes No Yes Yes Yes layer
overlap Reinforcing liner layer and bead Yes Yes No No Yes Yes Yes
filler overlap <Bonding layer> Existence of bonding layer and
its P P P P P P P structure and formulation Ratio A:B of (A)
diene-based rubber 50:50 50:50 50:50 50:50 50:50 50:50 50:50 and
(B) NBR (C) Aromatic petroleum resin to 100 30 30 30 30 30 30 30
parts by weight of (A) + (B) (parts by weight) Sulfur (parts by
weight) 2 2 2 2 2 2 2 Vulcanization accelerator CZ (parts 1 1 1 1 1
1 1 by weight) Vulcanization accelerator TOT-N 0.5 0.5 0.5 0.5 0.5
0.5 0.5 (parts by weight) Cross-linking agent (TAIC) (parts by 0 0
0 0 0 0 0 weight) Organic peroxide (parts by weight) 0 0 0 0 0 0 0
Thickness (mm) 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Bead area structure FIG.
1 (a) FIG. 1 (b) FIG. 1 (c) FIG. 1 (d) FIG. 1 (a) FIG. 1 (a) FIG. 1
(e) Bead filler height (mm) 32 32 32 32 45 35 32 Bead filler JIS
(A) hardness 75 75 75 75 75 75 75 Run flat durability (index) ->
135 107 105 102 100 108 115 larger, the better Rolling resistance
(index) -> 99 93 94 94 97 98 96 smaller, the better Riding
comfort Good Good Good Good Good Good Good *1Two-layer structure of
isobutylene-isoprene copolymer (IIR) rubber layer and ultrahigh
molecular weight polyethylene (UHMwPE) sheet.
[0194] As is seen from the results of Table VI, pneumatic tires
configured by bonding the reinforcing liner layers of the
compositions according to the present invention with the adjoining
rubber layers in predetermined positional relationships through
bonding rubber layers comprised of predetermined compositions are
excellent in all of the run flat durability, rolling resistance,
and riding comfort and give excellent run flat tires.
[0195] The following commercial products were used for the
ingredients of the formulations used in the following Standard
Example 5, Examples 50 to 66, and Comparative Examples 27 to 36.
Note that blending agents not changed in amounts are not listed in
the tables of the examples.
10 1) Ingredients of Formulations of Bead Portion Reinforcing
Rubber Members Hydrogenated NBR: Zetpol 2020 (made variate by
Nippon Zeon) Zinc methacrylate: R-20S (made by variate Asada
Chemical Industry) Carbon black: N339 (made by Showa variate Cabot)
Organic peroxide (40% diluted): 5 parts Parkadox 14/40 (made by
Kayaku Akzo) by weight Antioxidant: Nauguard 445 (made by 1.5 parts
Uniroyal) by weight 2) Ingredients of Formulations of Bonding
Rubber Layer Diene-based rubber (NR): RSS#3 variate NBR: Nipol
DN401 (made by Nippon Zeon) variate Carbon black: N339 (made by
Showa 50 parts Cabot) by weight Aromatic petroleum resin: FR-120
variate (made by Fujikosan) Zinc oxide: Zinc White #3 (made by 5
parts Seido Chemical Industry) by weight Stearic acid: Beads
Stearic Acid 1 part (made by Nippon Oil and Fat) by weight
Antioxidant: Nocrac 224 (made by Ouchi 1 part Shinko Chemical) by
weight Sulfur: Insoluble sulfur 2 parts by weight (sulfur
vulcanization based) Vulcanization accelerator: Nocceler 1 part
CZ-G (made by Ouchi Shinko Chemical) by weight (sulfur
vulcanization based) Vulcanization accelerator: Nocceler 0.5 part
TOT-N (made by Ouchi Shinko Chemical) by weight (sulfur
vulcanization based) Organic peroxide (40% diluted): 5 parts
Parkadox 14/40 (made by Kayaku Akzo) by weight (organic peroxide
cross-linking based) Co-cross-linking agent: TAIC (made by 3 parts
Nippon Kasei Chemical) by weight (organic peroxide cross-linking
based)
[0196] The rubber formulations A and B used in Standard Example 5
and Comparative Example 27 in Table VII were as follows:
11 A B (parts (parts by by Conventional rubber formulation weight)
weight) NR: RSS#3 75 75 SBR: Nipol 1502 (made by Nippon 25 25 Zeon)
Carbon black: B326M (made by Showa 70 65 Cabot) Zinc oxide: Zinc
White #3 (made by 5 5 Seido Chemical Industry) Stearic acid: Beads
Stearic Acid 1 1 (made by Nippon Oil and Fat) Antioxidant: Nocrac
224 (made by 1 1 Ouchi Shinko Chemical) Novolak type phenol resin:
PR-YR- 5 20 36F (made by Sumitomo Durez) Sulfur: Insoluble sulfur 5
5 Vulcanization accelerator: 2.5 2.5 Nocceler NS-F (made by Ouchi
Shinko Chemical) Nocceler H (made by Ouchi Shinko 1 1 Chemical)
Fabrication of Test Tires
[0197] Reinforcing rubber members of the bead portion comprised of
compositions of the formulations shown in the Examples were
extruded into different shapes and wrapped around by the bonding
rubber layers shown in the examples, then shaped by conventional
techniques and arranged and bonded to give the predetermined
positional relationships shown in FIGS. 2(a) to 2(c) to fabricate
tires of a size of 185/65 R14 which were used for durability tests,
driving stability tests, and riding comfort tests.
[0198] Note that FIGS. 2(a) to 2(c) show the reinforcing rubber
members of the bead portions and the bonding rubber layers
together.
[0199] The methods of measurement and evaluation in the examples
were as follows:
[0200] 1) Durability Test
[0201] Tires were run under the following conditions and the
distances at which trouble occurred were expressed as indexes. (The
larger the index, the better.)
[0202] Running conditions: A drum tester having a smooth drum
surface, made of steel, and having an inside diameter of 1707 mm
was used, the ambient temperature was controlled to 38.+-.3.degree.
C., and the tires were run under conditions of a rim size of
14.times.5.5-J, an internal pressure of 240 kPa, and a speed of 81
km/h. The load was started from an initial 4.5 kN and increased to
a load of 7.28 kN in 0.68 kN increments every 2 hours. After this,
the load was increased to a load of 14.0 kN in 0.68 kN increments
every 4 hours. The test was ended when running at a load of 14.0 kN
for 4 hours.
[0203] 2) Vehicular Driving Stability/Riding Comfort Test
[0204] Test tires mounted on 14.times.5.5-J rims at an internal
pressure of 200 kPa were mounted on a 1.6 liter engine displacement
front engine front wheel drive passenger car. The car was driven
over a test course by five trained drivers to evaluate the feeling.
The results were ranked by a five-point system based on the
following judgement criteria in relative comparison with reference
tires. The average of the three drivers, not including the highest
score and lowest score, was classified as follows.
[0205] Judgement criteria
[0206] 5: Excellent, 4: good, 3: equal to reference, 2: poor, 1:
very poor
[0207] Classification
[0208] Average score larger than reference (3 points): Very
good
[0209] Equal to reference: Good
[0210] Less than reference: Poor
Standard Example 5, Examples 50 to 66, and Comparative Examples 27
to 36 (Reinforcing Rubber of Bead Portion)
[0211] The results of tests on the durability, driving stability,
and riding comfort of the test tires in the examples are shown in
the following Table VII.
12TABLE VII (Tire Size: 185/65R14) Stand. Comp. Comp. Comp. Ex. 5
Ex. 27 Ex. 28 Ex. 50 Ex. 29 Ex. 51 <Bead reinforcing rubber
member> Formulation Conv. Conv. C C D B Rubber rubber form. A
form. B Hydrogenated NBR (parts by weight) -- -- 100 100 60
(<low 70 (low (stand.) (stand.) limit) limit) Zinc methacrylate
(parts by weight) -- -- 80 80 80 80 (stand.) (stand.) Carbon black
(parts by weight) (70) (65) 0 0 0 0 Zinc methacrylate and carbon
black 80 80 80 80 total (parts by weight) Novolak-type phenol resin
(parts by 5 20 weight) <Bonding layer> -- Existence and no.
of bonding layers -- -- 2-layer*1 1-layer 1-layer 1-layer
Formulation -- -- -- N N N Ratio A:B of (A) diene-based rubber --
-- -- 50:50 50:50 50:50 and (B) NBR (C) Aromatic petroleum resin to
100 -- -- -- 30 30 30 parts by weight of (A) + (B) (parts by
(stand) weight) Sulfur (parts by weight) -- -- -- 2 2 2
Vulcanization accelerator CZ (parts -- -- -- 1 1 1 by weight)
Vulcanization accelerator TOT-N -- -- -- 0.5 0.5 0.5 (parts by
weight) Cross-linking agent (TAIC) (parts by -- -- -- 0 0 0 weight)
Organic peroxide (parts by weight) -- -- -- 0 0 0 Thickness of
bonding layer (mm) -- -- 11R:0.2 0.5 0.5 0.5 UHMwPE: 0.2 Bead area
structure FIG. 2 (a) FIG. 2 (a) FIG. 2 (a) FIG. 2 (a) FIG. 2 (a)
FIG. 2 (a) Bead filler height (mm) 45 45 45 45 45 45 Bead filler
JIS (A) hardness 65 95 95 95 85 93 Durability (index of running 100
97 87 120 127 125 distance) -> larger, the better (break)
(adhesion) Driving stability Poor Good Good Good Poor Good Riding
comfort V. Good Good Good Good V. Good Good Comp. Comp. Ex. 52 Ex.
30 Ex. 53 Ex. 54 Ex. 31 Ex. 55 <Bead reinforcing rubber
member> Formulation F G H I J K Hydrogenated NBR (parts by
weight) 100 100 100 100 100 100 (stand.) (stand.) Zinc methacrylate
(parts by weight) 80 20 (<low 40 (low 120 (hi 130 (>hi 80
limit) limit) limit) limit) (stand.) Carbon black (parts by weight)
0 0 0 0 0 40 (hi limit) Zinc methacrylate and carbon black 80 20 40
120 130 120 (hi total (parts by weight) limit) <Bonding
layer> Existence and no. of bonding layers 1-layer 1-layer
1-layer 1-layer 1-layer 1-layer Formulation N N N N N N Ratio A:B
of (A) diene-based rubber 50:50 50:50 50:50 50:50 50:50 50:50 and
(B) NBR (C) Aromatic petroleum resin to 100 30 30 (stand.) 30 30 30
30 (stand.) parts by weight of (A) + (B) (parts by weight) Sulfur
(parts by weight) 2 2 2 2 2 2 Vulcanization accelerator CZ (parts 1
1 1 1 1 1 by weight) Vulcanization accelerator TOT-N 0.5 0.5 0.5
0.5 0.5 0.5 (parts by weight) Cross-linking agent (TAIC) (parts by
0 0 0 0 0 0 weight) Organic peroxide (parts by weight) 0 0 0 0 0 0
Thickness of bonding layer (mm) 0.5 0.5 0.5 0.5 0.5 0.5 Bead area
structure FIG. 2 (a) FIG. 2 (a) FIG. 2 (a) FIG. 2 (a) FIG. 2 (a)
FIG. 2 (a) Bead filler height (mm) 45 45 45 45 45 45 Bead filler
JIS (A) hardness 95 82 (soft) 94 95 97 95 Durability (index of
running 122 131 121 120 115 106 distance) -> larger, the better
Driving stability Good Poor Good Good V. Good Good Riding comfort
Good V. Good Good Good Poor Good Comp. Comp. Ex. 32 Ex. 56 Ex. 57
Ex. 33 Ex. 58 Ex. 59 <Bead reinforcing rubber member>
Formulation L C C C C C Hydrogenated NBR (parts by weight) 100 100
(stand.) 100 100 (stand.) 100 100 Zinc methacrylate (parts by
weight) 80 80 (stand.) 80 80 (stand.) 80 80 Carbon black (parts by
weight) 50 0 0 0 0 0 (>hi limit) Zinc methacrylate and carbon
black 130 80 80 80 80 80 total (parts by weight) (>hi limit)
<Bonding layer> Existence and no. of bonding layers 1-layer
1-layer 1-layer 1-layer 1-layer 1-layer Formulation N O P Q R S
Ratio A:B of (A) diene-based rubber 50:50 10:90 90:10 50:50 50:50
50:50 and (B) NBR (C) Aromatic petroleum resin to 100 30 30
(stand.) 30 3 5 80 parts by weight of (A) + (B) (parts by weight)
Sulfur (parts by weight) 2 2 2 2 2 2 Vulcanization accelerator CZ
(parts 1 1 1 1 1 1 by weight) Vulcanization accelerator TOT-N 0.5
0.5 0.5 0.5 0.5 0.5 (parts by weight) Cross-linking agent (TAIC)
(parts by 0 0 0 0 0 0 weight) Organic peroxide (parts by weight) 0
0 0 0 0 0 Thickness of bonding layer (mm) 0.5 0.5 0.5 0.5 0.5 0.5
Bead area structure FIG. 2 (a) FIG. 2 (a) FIG. 2 (a) FIG. 2 (a)
FIG. 2 (a) FIG. 2 (a) Bead filler height (mm) 45 45 45 45 45 45
Bead filler JIS (A) hardness 97 95 95 95 95 95 Durability (index of
running 95 (brittle) 125 123 96 115 117 distance) -> larger, the
better (adhesion) Driving stability Good Good Good Good Good Good
Riding comfort Poor Good Good Good Good Good Comp. Comp. Ex. 34 Ex.
35 Ex. 60 Ex. 61 Ex. 62 Ex. 63 <Bead reinforcing rubber
member> Formulation C C C C C C Hydrogenated NBR (parts by
weight) 100 100 (stand.) 100 100 100 100 Zinc methacrylate (parts
by weight) 80 80 (stand.) 80 80 80 80 Carbon black (parts by
weight) 0 0 0 0 0 0 Zinc methacrylate and carbon black 80 80 80 80
80 80 total (parts by weight) <Bonding layer> Existence and
no. of bonding layers 1-layer 1-layer 1-layer 1-layer 1-layer
1-layer Formulation T N N N N N Ratio A:B of (A) diene-based rubber
50:50 50:50 50:50 50:50 50:50 50:50 and (B) NBR (C) Aromatic
petroleum resin to 100 85 30 (stand.) 30 30 30 30 parts by weight
of (A) + (B) (parts by weight) Sulfur (parts by weight) 2 2 2 2 2 2
Vulcanization accelerator CZ (parts 1 1 1 1 1 1 by weight)
Vulcanization accelerator TOT-N 0.5 0.5 0.5 0.5 0.5 0.5 (parts by
weight) Cross-linking agent (TAIC) (parts by 0 0 0 0 0 0 weight)
Organic peroxide (parts by weight) 0 0 0 0 0 0 Thickness of bonding
layer (mm) 0.5 0.05 0.1 0.2 0.8 2.0 Bead area structure FIG. 2 (a)
FIG. 2 (a) FIG. 2 (a) FIG. 2 (a) FIG. 2 (a) FIG. 2 (a) Bead filler
height (mm) 45 45 45 45 45 45 Bead filler JIS (A) hardness 95 95 95
95 95 95 Durability (index of running 93 (heat) 115 117 115 116 110
distance) -> larger, the better Driving stability Good Good Good
Good Good Good Riding comfort Good Good Good Good Good Good Comp.
Ex. 36 Ex. 64 Ex. 65 Ex. 66 <Bead reinforcing rubber member>
Formulation C C C C Hydrogenated NBR (parts by weight) 100 100
(stand.) 100 (stand.) 100 Zinc methacrylate (parts by weight) 80 80
(stand.) 80 (stand.) 80 Carbon black (parts by weight) 0 0 0 0 Zinc
methacrylate and carbon black 80 80 80 80 total (parts by weight)
<Bonding layer> Existence and no. of bonding layers 1-layer
1-layer 1-layer 1-layer Formulation N U N N Ratio A:B of (A)
diene-based rubber 50:50 50:50 50:50 50:50 and (B) NBR (C) Aromatic
petroleum resin to 100 30 30 (stand.) 30 (stand.) 30 parts by
weight of (A) + (B) (parts by weight) Sulfur (parts by weight) 2 0
2 2 Vulcanization accelerator CZ (parts 1 0 1 1 by weight)
Vulcanization accelerator TOT-N 0.5 0 0.5 0.5 (parts by weight)
Cross-linking agent (TAIC) (parts by 0 3 0 0 weight) Organic
peroxide (parts by weight) 0 2 0 0 Thickness of bonding layer (mm)
2.5 0.5 0.5 0.5 Bead area structure FIG. 2 (a) FIG. 2 (a) FIG. 2
(b) FIG. 2 (c) Bead filler height (mm) 45 45 45 45 Bead filler JIS
(A) hardness 95 95 95 95 Durability (index of running 97 (heat) 118
124 122 distance) -> larger, the better Driving stability Good
Good Good Good Riding comfort Good Good Good Good *1Two-layer
structure of isobutylene-isoprene copolymer (IIR) rubber layer and
ultrahigh molecular weight polyethylene (UHMwPE) sheet.
[0212] As seen from the results of Table VII, the tires obtained by
arranging and bonding the reinforcing rubber members of the bead
portions according to the present invention at predetermined
locations are superior in durability and greatly improved in
driving stability and riding comfort.
[0213] In the following Standard Example 6, Example 67 to 82, and
Comparative Examples 37 to 44, test tires of a tire size of
185/65R14 were prepared using the ingredients of the formulations
listed in the tables to give the tire configurations listed in the
tables and the results of tests on them were shown.
[0214] The following commercial products were used for the
ingredients of the formulations used in the examples. Note that
blending agents not changed in amount are not listed in the tables
of the examples.
13 1) Ingredients of Formulations of Carcass Coat NR: RSS#3 variate
HNBR (hydrogenated NBR): Zetpol 2020 variate (made by Nippon Zeon)
Zinc methacrylate: R-20S (made by variate Asada Chemical Industry)
Carbon black (FEF grade): HTC-100 variate (made by Shinnikka
Carbon) Zinc oxide: Zinc White #3 (made by 5 parts Seido Chemical
Industry) by weight Antioxidant: Nauguard 445 (made by 1.5 parts
Uniroyal) by weight Organic peroxide: Parkadox 14/40 (made 5 parts
by Kayaku Akzo) by weight 2) Ingredients of Formulations of Bonding
Rubber Layer Diene-based rubber (NR): RSS#3 variate NBR: Nipol
DN401 (made by Nippon Zeon) variate Carbon black: N339 (made by
Showa variate Cabot) Aromatic petroleum resin: FR-120 variate (made
by Fujikosan) Zinc oxide: Zinc White #3 (made by 5 part Seido
Chemical Industry) by weight Stearic acid: Beads Stearic Acid 1
part (made by Nippon Oil and Fat) by weight Antioxidant: Nocrac 224
(made by Ouchi 1 part Shinko Chemical) by weight Sulfur: Insoluble
sulfur 2 parts by weight (sulfur vulcanization based) Vulcanization
accelerator: Nocceler 1 part CZ-G (made by Ouchi Shinko Chemical)
by weight (sulfur vulcanization based) Vulcanization accelerator:
Nocceler 0.5 part TOT-N (made by Ouchi Shinko Chemical) by weight
(sulfur vulcanization based) Organic peroxide (40% diluted): 3.5
parts Parkadox 14/40 (made by Kayaku Akzo) by weight (organic
peroxide cross-linking based) Co-cross-linking agent: TAIC (made by
3 parts Nippon Kasei Chemical) by weight (organic peroxide
cross-linking based)
[0215] The following commercial products were used for the
ingredients for the formulations in the standard examples in Tables
VIII to X. Note that the blending agents of the standard examples
include ingredients not listed in the tables.
Ingredients of Formulation in Carcass Coat in Standard Example
[0216]
14 NR: RSS#3 70 parts by weight SBR: Nipol 1502 (made by Nippon
Zeon) 30 parts by weight Carbon black (FEF grade): HTC-100 50 parts
(made by Shinnikka Carbon) by weight Zinc oxide: Zinc White #3
(made by 5 parts Seido Chemical Industry) by weight Stearic acid:
Beads Stearic Acid 1 part (made by Nippon Oil and Fat) by weight
Aromatic oil: Komorex 300 (made by 8 parts Nippon Oil) by weight
Antioxidant: Nocrac 224 (made by Ouchi 1.5 parts Shinko Chemical)
by weight Sulfur: Insoluble sulfur 2.5 parts by weight
Vulcanization accelerator: Nocceler 1 part CZ-G (made by Ouchi
Shinko Chemical) by weight Vulcanization accelerator: Nocceler 1.5
parts NS-F (made by Ouchi Shinko Chemical) by weight
[0217] The methods of measurement and evaluation in the Examples
were as follows:
[0218] 1) Rolling Resistance Test
[0219] Tires were run under the following conditions to measure the
rolling resistance at that time. The results were expressed indexed
to the measured value for a conventional tire as 100. (The smaller
the value, the better.)
[0220] Running conditions: A drum tester having a smooth drum
surface, made of steel, and having an inside diameter of 1707 mm
was used, the ambient temperature was controlled to 23.+-.2.degree.
C., and the tires were run under conditions of a rim size of
14.times.5.5-J, an internal pressure of 200 kPa, a load of 4.1 kN,
and a speed of 80 km/h.
[0221] 2) Driving Stability Feeling Test
[0222] Test tires mounted on 14.times.5.5-J rims at an internal
pressure of 200 kPa were mounted on a 1.6 liter engine displacement
front engine front wheel drive compact passenger car. The car was
driven over a test course by five trained drivers to evaluate the
feeling. The results were ranked by a five-point system based on
the following judgement criteria in relative comparison with
reference tires. The average of the three drivers, not including
the highest score and lowest score, was shown.
[0223] Judgement criteria:
[0224] 5: Excellent, 4: good, 3.5: somewhat good, 3: equal to
reference, 2.5: somewhat poor (practical lower limit), 2: poor, 1:
very poor
[0225] 3) Indoor Durability Test
[0226] A drum tester having a smooth drum surface, made of steel,
and having an inside diameter of 1707 mm was used, the ambient
temperature was controlled to 38.+-.3.degree. C., and the tires
were run at a rim size of 14.times.5.5-J, an internal pressure of
140 kPa, a load of 6.0 kN, and a speed of 140 km/h until trouble
occurred. The running distances until trouble occurred in the tires
was expressed indexed to the distance where trouble occurred in a
standard tire as 100. (The larger the value, the better.)
[0227] 4) Air Leakage Test
[0228] The tire was allowed to stand at an initial pressure of 200
kPa, room temperature of 20.degree. C., and no load conditions for
three months. The internal pressure was measured at intervals of
four days. The .alpha. value was found by recurrence to the
following equation where the measurement pressure was Pt, the
initial pressure was P.sub.0, and the number of days elapsed was
t:
Pt/P.sub.0=exp(-.alpha.t)
[0229] Using the .alpha. obtained and substituting 30 (days) for t,
the following was obtained:
.beta.=[1-exp(-.alpha.t)].times.100
[0230] .beta. was made the pressure drop (%/month) per month.
Standard Example 6, Examples 67 to 71, and Comparative Examples 37
to 41 (Carcass Coat)
[0231] The results of tests in the case of changing the compound of
the carcass coat are shown in Table VIII.
15TABLE VIII <Examples of Changing Carcass Coat Compound>
Stand. Comp. Comp. Comp. Ex. 6 Ex. 37 Ex. 38 Ex. 39 Ex. 67 Ex. 68
Carcass coat NR (phr) 70 70 40 30 30 30 SBR (phr) 30 30 HNBR (phr)
60 70 70 70 Zinc methacrylate (phr) 0 0 0 0 20 20 Carbon (FEF
grade) (phr) 50 50 45 45 35 35 Bonding rubber layer NR (phr) -- --
-- -- -- 70 NBR (phr) -- -- -- -- -- 30 Aromatic petroleum resin
(phr) -- -- -- -- -- 40 Sulfur (phr) -- -- -- -- -- 2 Vulcanization
accelerator (CZ) -- -- -- -- -- 1 (phr) Vulcanization accelerator
-- -- -- -- -- 0.5 (TOT-N) (phr) Tire structure Bonding rubber
layer thickness -- -- -- -- -- 0.3 (mm) Air barrier layer Yes No No
No No No Carcass coat thickness (mm) 1.2 1.2 1.0 1.0 1.0 1.0 Air
barrier layer thickness 1.2 -- -- -- -- -- (mm) Tire mass (g) 7300
6850 6770 6770 6765 6885 Test results Rolling resistance (index)
100 100 101 101 99 99 Driving stability feeling 3 2 3 3.5 3 3
(score) Indoor durability test (index) 100 104 96 99 102 114 Air
leakage test (%/month) 2.8 8.9 3.0 2.7 2.7 2.7 Comp. Comp. Ex. 69
Ex. 70 Ex. 71 Ex. 40 Ex. 41 Carcass coat NR (phr) 30 30 30 30 SBR
(phr) HNBR (phr) 70 70 100 70 70 Zinc methacrylate (phr) 40 80 40
100 70 Carbon (FEF grade) (phr) 10 5 10 0 25 Bonding rubber layer
NR (phr) 70 70 70 70 70 NBR (phr) 30 30 30 30 30 Aromatic petroleum
resin (phr) 40 40 40 40 40 Sulfur (phr) 2 2 2 2 2 Vulcanization
accelerator (CZ) 1 1 1 1 1 (phr) Vulcanization accelerator 0.5 0.5
0.5 0.5 0.5 (TOT-N) (phr) Tire structure Bonding rubber layer
thickness 0.3 0.3 0.3 0.3 0.3 (mm) Air barrier layer No No No No No
Carcass coat thickness (mm) 1.0 1.0 1.0 1.0 1.0 Air barrier layer
thickness -- -- -- -- -- (mm) Tire mass (g) 6890 6890 6890 6900
6900 Test results Rolling resistance (index) 98 98 98 97 99 Driving
stability feeling 3.5 4 3.5 3.5 3.5 (score) Indoor durability test
(index) 120 127 118 97 93 Air leakage test (%/month) 2.6 2.5 2.3
2.5 2.4
[0232] The tires of Examples 37 to 71 using carcass coats
satisfying the various conditions defined in the present invention
exhibited good results in all of the rolling resistance, driving
stability feeling, indoor durability test, and air leakage test. As
opposed to this, with the tire using a conventional carcass coat
and omitting the air barrier layer of Comparative Example 37, the
air leakage became worse and the driving stability feeling
declined. Further, in Comparative Example 38 where the amount of
HNBR was less than the lower limit, there was a large air leakage,
while in Comparative Example 39 where the amount of HNBR was
sufficient and there was too much carbon black, it was seen that
the rolling resistance became worse. Further, in Comparative
Example 40 where there was too much zinc methacrylate, the carcass
coat became too hard and the tire failed in durability, while in
Comparative Example 41 where the total of the zinc methacrylate and
the carbon black exceeded 90 parts by weight, the tire also failed.
In Example 68 with the bonding rubber layer, the durability was
further improved compared with Example 67 without the same. In
Examples 69 and 70 where the amounts of zinc methacrylate were
increased, it was seen that the hardness of the rubber was improved
and the driving stability feeling was further improved while
maintaining the rolling resistance. In Example 71 where the HNBR
was made 100 phr, it was seen that the air barrier performance was
further improved.
Standard Example 6, Examples 72 to 77, and Comparative Example 42
(Carcass Coat)
[0233] The results of tests in the case of leaving the formulation
of the carcass coat constant and changing the compound of the
bonding rubber compound are shown in Table IX.
16TABLE IX <Examples of Changing Bonding Rubber Compound>
Stand. Comp. Ex. 6. Ex. 72 Ex. 73 Ex. 74 Ex. 75 Ex. 76 Ex. 42 Ex.
77 Bonding rubber layer NR (phr) -- 20 80 60 60 60 60 60 NBR (phr)
-- 80 20 40 40 40 40 40 Aromatic petroleum resin (phr) -- 40 40 5
40 80 100 30 Sulfur (phr) -- 2 2 2 2 2 2 Vulcanization accelerator
(CZ) 1 1 1 1 1 1 (phr) Vulcanization accelerator 0.5 0.5 0.5 0.5
0.5 0.5 (TOT-N) (phr) Cross-linking agent (TAIC) -- 3 (phr) Organic
peroxide (phr) -- 1.4 Carcass coat NR (phr) 70 SBR (phr) 30 HNBR
(phr) 100 100 100 100 100 100 100 Zinc methacrylate (phr) 0 60 60
60 60 60 60 60 Carbon (FEF grade) (phr) 50 0 0 0 0 0 0 0 Tire
structure Bonding rubber layer thickness -- 0.5 0.5 0.5 0.5 0.5 0.5
0.5 (mm) Air barrier layer Yes No No No No No No No Carcass coat
thickness (mm) 1.2 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Air barrier layer
thickness 1.2 -- -- -- -- -- -- -- (mm) Tire mass (g) 7300 6970
6970 6970 6970 6970 6970 6970 Test results Rolling resistance
(index) 100 97 97 97 97 97 97 97 Driving stability feeling 3 3.5
3.5 3.5 3.5 3.5 3.5 3.5 (score) Indoor durability test (index) 100
112 114 102 122 100 95 143 Air leakage test (%/month) 2.8 2.2 2.3
2.2 2.3 2.3 2.4 2.3
[0234] The tires of Example 72 to 77 having carcass coats using the
bonding rubber layer defined in the present invention exhibited
good results in all of the rolling resistance, driving stability
feeling, indoor durability test, and air leakage test. As opposed
to this, with tires like in Comparative Example 42 where the
aromatic oil resin ingredient was formulated in over the upper
limit, the bonding rubber layer broke and the durability became
poor. It was seen that the tire of Example 75 which suitably
increased the amount of the aromatic oil resin in the range of the
predetermined amount of formulation was further improved in the
durability. Further, in Example 77 which was formulated a
co-cross-linking agent in the bonding rubber layer and was
cross-linked by an organic peroxide, it was seen that the
durability was further improved.
Standard Example 6, Examples 78 to 82, and Comparative Examples 43
to 44 (Carcass Coat)
[0235] The results of tests in the case of leaving the formulations
of the carcass coat and bonding rubber layer constant and changing
the thicknesses are shown in Table X.
17TABLE X <Examples of Changing Thickness of Carcass and Bonding
Rubber Composition Layers> Stand. Comp. Comp. Ex. 6 Ex. 78 Ex.
79 Ex. 43 Ex. 80 Ex. 81 Ex. 44 Ex. 82 Carcass coat NR (phr) 70 SBR
(phr) 30 HNBR (phr) 100 100 100 100 100 100 100 Zinc methacrylate
(phr) 0 60 60 60 60 60 60 60 Carbon (FEF grade) (phr) 50 0 0 0 0 0
0 0 Bonding rubber layer NR (phr) -- 70 70 70 70 70 70 NBR (phr) --
30 30 30 30 30 30 IIR (HNBR side)* (phr) 100 Aromatic petroleum
resin (phr) -- 40 40 40 40 40 40 Sulfur (phr) -- 2 2 2 2 2 2 2
Vulcanization accelerator (CZ) -- 1 1 1 1 1 1 (phr) Vulcanization
accelerator -- 0.5 0.5 0.5 0.5 0.5 0.5 (TOT-N) (phr) Ultrahigh
molecular weight PE -- -- -- -- 0.1 mm -- -- -- layer* (mm) Tire
structure Bonding rubber layer thickness -- 0.3 0.1 0.1 1.6 1.8 0.3
(mm) 0.6 Two-layer bonding treated* air Yes No No No No No No Yes
barrier layer Carcass coat thickness (mm) 1.2 0.7 2.3 2.4 1.0 0.7
0.7 0.7 T/d 1.85 1.10 3.60 3.70 1.55 1.10 1.10 1.10 Air barrier
layer thickness 1.2 -- -- -- -- -- -- 0.3 (mm) Tire mass (g) 7300
6760 7290 7330 6990 7280 7360 6890 Test results Rolling resistance
(index) 100 100 98 98 100 100 101 96 Driving stability feeling 3 3
4 4 3 3 3 3.5 (score) Indoor durability test (index) 100 110 109
115 105 117 113 106 Air leakage test (%/month) 2.8 2.7 1.4 1.3 2.7
2.7 2.7 2.1 *Japanese Unexamined Patent Publication (Kokai) No.
5-185805
[0236] The tires of Examples 78 to 82 using the thicknesses of the
carcass coats defined in the present invention exhibited good
effects in all of the rolling resistance, driving stability
feeling, indoor durability test, and air leakage test. As opposed
to this, in Comparative Example 43 with a thickness of the carcass
coat exceeding the upper limit, the air barrier property and the
driving stability feeling were improved, but the weight ended up
exceeding the standard example. Further, even in the case of
Comparative Example 44 where the thickness of the bonding rubber
layer was too great, the weight of the tire ended up exceeding the
standard example. In Example 80 using a bonding rubber layer
comprised of two layers of the method of a conventional example
(Japanese Unexamined Patent Publication (Kokai) No. 5-185805), the
tire was insufficient in terms of the durability etc., but the
shaping was troublesome. According to Example 82, it was seen that
it was also possible to provide an ordinary air barrier layer
instead of making the carcass coat thicker.
[0237] As shown in the above examples, by using a predetermined
hydrogenated NBR composition for the material constituting the
carcass coat in the pneumatic tire according to the present
invention or by bonding the carcass coat and adjoining rubber layer
through a bonding rubber layer comprised of a predetermined rubber
composition, it was seen that a pneumatic tire were superior in the
rolling resistance, driving stability feeling, indoor durability,
and air barrier property and lightening in weight could be
obtained.
[0238] The following commercial products were used for the
ingredients of the formulations of the following Standard Examples
7 to 8, Examples 83 to 111, and Comparative Examples 45 to 61. Note
that blending agents not changed in amount are not listed in the
tables of the examples.
18 1) Ingredients of Formulations of Side Reinforcing Layer and
Side Ribbon Portion NR: RSS#3 variate HNBR: Zetpol 2020 (made by
Nippon Zeon) variate Zinc methacrylate: R-20S (made by variate
Asada Chemical Industry) Carbon black (FEF grade): HTC-100 variate
(made by Shinnikka Carbon) (case of only side reinforcing layer)
Titanium dioxide: A-100 (made by 10 parts Ishihara Sangyo) by
weight (case of only white ribbon) Zinc oxide: Zinc White #3 (made
by 5 parts Seido Chemical Industry) by weight Antioxidant: Nauguard
445 (made by 1.5 parts Uniroyal) by weight Organic peroxide:
Parkadox 14/40 5 parts (made by Kayaku Akzo) by weight 2)
Ingredients of Formulations of Bonding Rubber Layer Diene-based
rubber (NR): RSS#3 variate NBR: Nipol DN401 (made by Nippon Zeon)
variate Carbon black: N339 (made by Showa variate Cabot) Aromatic
petroleum resin: FR-120 variate (made by Fujikosan) Zinc oxide:
Zinc White #3 (made by 5 parts Seido Chemical Industry) by weight
Stearic acid: Beads Stearic Acid 1 part (made by Nippon Oil and
Fat) by weight Antioxidant: Nocrac 224 (made by Ouchi 1 part Shinko
Chemical) by weight Sulfur: Sanfer (made by Sanshin 2 parts
Chemical) by weight (case of sulfur vulcanization based
formulation) Vulcanization accelerator: Nocceler 1 part CZ-G (made
by Ouchi Shinko Chemical) by weight (case of sulfur vulcanization
based formulation) Vulcanization accelerator: Nocceler 0.5 part
TOT-N (made by Ouchi Shinko Chemical) by weight (case of sulfur
vulcanization based formulation) Organic peroxide (40% diluted):
3.5 parts Parkadox 14/40 (made by Kayaku Akzo) by weight (case of
organic peroxide cross-linking based formulation) Co-cross-linking
agent: TAIC (made by 3 parts Nippon Kasei Chemical) by weight (case
of organic peroxide cross-linking based formulation)
[0239] Further, the formulations of the standard examples of the
side reinforcing layer and white side were as follows:
Ingredients of Formulation of Standard Example of Side Reinforcing
Layer (Table XI to Table XIII)
[0240]
19 NR: RSS#3 60 parts by weight BR: Nipol BR-1220 (made by Nippon
Zeon) 40 parts by weight Carbon black (FEF grade): HTC-100 50 parts
(made by Shinnikka Carbon) by weight Zinc oxide: Zinc White #3
(made by 5 parts Seido Chemical Industry) by weight Stearic acid:
Beads Stearic Acid 1 part (made by Nippon Oil and Fat) by weight
Aromatic oil: Komorex 300 (made by 8 parts Nippon Oil) by weight
Antioxidant: Nocrac 6C (made by Ouchi 1.0 part Shinko Chemical) by
weight Antioxidant: Nocrac 224 (made by Ouchi 0.5 part Shinko
Chemical) by weight Wax: Sunnoc (made by Ouchi Shinko 1.0 part
Chemical) by weight Sulfur: Sanfer (made by Sanshin 2.0 parts
Chemical) by weight Vulcanization accelerator: Nocceler 1.0 part
NS-F (made by Ouchi Shinko Chemical) by weight
Ingredients of Formulation of Standard Example of White Ribbon
Portion (Table XIV to Table XV)
[0241]
20 NR: RSS#3 50 parts by weight C1-IIR: Exxon Chlorobutyl 106 (made
by 25 parts Japan Butyl) by weight EPDM: Esprene 505A (made by
Sumitomo 25 parts Chemical) by weight Titanium dioxide: A-100 (made
by 20 parts Ishihara Sangyo) by weight Clay: Suprex Clay (made by
Huber) 50 parts by weight Zinc oxide: Zinc White #3 (made by 6
parts Seido Chemical Industry) by weight Stearic acid: Beads
Stearic Acid 1 part (made by Nippon Oil and Fat) by weight
Antioxidant: Nauguard 445 (made by 1.5 parts Uniroyal) by weight
Petroleum resin: Hiletz G-100X 2 parts (made by Mitsui
Petrochemical) by weight Sulfur: Sanfer (made by Sanshin 1part
Chemical) by weight Vulcanization accelerator: Nocceler 1 part NS-F
(made by Ouchi Shinko Chemical) by weight
Fabrication of Test Tires
[0242] An inner layer and carcass were successively wrapped on a
shaping drum, beads were given, the carcass was turned up, the
bonding rubber layer of the composition and thickness shown in each
of the examples was adhered, then the side reinforcing layer and
side ribbon portion were adhered. A steel belt layer comprised of
two layers and a cap tread were superposed to shape a green tire.
In the case of a side reinforcing layer, tires of a size of
185/65R14 were fabricated by arranging and bonding members to give
the predetermined positional relationships of FIGS. 3(a) to 3(g).
Further, in the case of a side ribbon, tires of 185/65R14 obtained
by arranging and bonding members at the predetermined positions of
the examples were fabricated. These were used for predetermined
tests.
[0243] The methods of tests and evaluation in the Examples of the
side reinforcing layers (Tables XI to XIII) and side ribbon
portions (Tables XIV to XV) were as follows:
[0244] 1) Cut Resistance Test Method
[0245] Tires were run under the following conditions to find the
average value of the critical speed at which tires do not burst.
When the average value of the critical speed was less than that of
a conventional tire (Comparative Example 1), the tire was rated "no
good" (Poor), while when it was the same as or higher than that of
a conventional tire, it was rated "OK" (Good). Further, when the
average value of the critical speed was more than 2 km/h higher
than that of the conventional tire, it was rated "very good"
(V.Good).
[0246] Running conditions: Test tires were mounted on a 1.6 liter
engine displacement front engine front wheel drive compact
passenger car with a rim size of 14.times.5 1/2JJ and an internal
pressure of 200 kPa and were driven over a steel rail of a height
of 100 mm as shown below at an angle of 30.degree.. The speed at
this time was changed from 10 km/h in steps of 1.0 km/h. The
critical speed at which the tires would not burst was investigated
by n=3 and the cut resistance was evaluated from that average
value.
[0247] 2) Durability Test Method
[0248] Tires were run under the following conditions and ranked as
"no good" (poor) when trouble occurred and "OK" (good) when it did
not.
[0249] Running conditions: A drum tester having a smooth drum
surface, made of steel, and having an inside diameter of 1707 mm
was used, the ambient temperature was controlled to 38.+-.3.degree.
C., and the tires were run under conditions of a rim size of
14.times.5 1/2JJ, an internal pressure of 240 kPa, and a speed of
81 km/h. The initial load was made 4.57 kN, then the load was
increased to a load of 7.28 kN in 0.68 kN increments every 2 hours.
After this, the load was increased to a load of 14.0 kN in 0.68 kN
increments every 4 hours. The test was ended when running at a load
of 14.0 kN for 4 hours.
[0250] 3) Rolling Resistance Test Method
[0251] Tires were run under the following conditions to measure the
rolling resistance at that time. The results were expressed indexed
to the measured value for a conventional tire (Comparative Example
1) as 100. (The smaller the value, the better.)
[0252] Running conditions: A drum tester having a smooth drum
surface, made of steel, and having an inside diameter of 1707 mm
was used, the ambient temperature was controlled to 23.+-.2.degree.
C., and the tires were run under conditions of a rim size of
14.times.5 1/2JJ, an internal pressure of 200 kPa, and a speed of
80 km/h.
[0253] 4) Ozone Crack Test Method
[0254] Stretch test pieces were exposed in an atmosphere containing
a low concentration of artificially generated ozone to promote
deterioration and examine the ozone resistance. The test pieces
were evaluated by a combination of alphabet letters and numerals by
evaluating the number of cracks by A (small number), B (large
number), and C (innumerable) and evaluating the sizes and depths of
the cracks by 1 (cracks not visible to the naked eye, but
observable under a 10.times. magnifying glass), 2 (cracks visible
to the naked eye), 3 (cracks deep and relatively large but less
than 1 mm), 4 (cracks deep and large 1 to 3 mm), and 5 (cracks over
3 mm or likely to cause breaks). In these examples, the
conventional tire (standard example) was evaluated as "good", good
tires as "very good", and poor tires as "poor".
[0255] Test conditions: Test pieces (strip of length 60 mm, width
10 mm, and thickness 2 mm) were stretched 20.+-.2%, exposed in an
atmosphere of an ozone concentration of 50.+-.5 pphm, and taken out
after 72 hours.
[0256] 5) Deterioration Test Method
[0257] Test tires mounted on rims of 14.times.5 1/2JJ and filled
with air to an air pressure of 200 kPa were exposed in an
atmosphere of an ozone concentration of 100 pphm for 24 hours, then
the discoloration of the ribbon portions were evaluated visually.
The degree of discoloration of a conventional tire was evaluated as
"good", tires with greater discoloration than the conventional tire
(standard tire) as "poor", and tires with less discoloration as
"very good".
Standard Example 7, Examples 83 to 88, and Comparative Examples 45
to 51 (Side Reinforcing Layer)
[0258] The results of tests on the cut resistance, durability, and
rolling resistance of test tires in the case of changing the ratio
of ingredients in the formulations of the side reinforcing layer
and leaving the composition of the bonding rubber layer and the
tire configuration constant are shown in the following Table
XI.
21TABLE XI (Tire Size: 185/65R14) Stand. Comp. Comp. Comp. Comp.
Side reinforcing layer formulation Ex. 7 Ex. 45 Ex. 46 Ex. 83 Ex.
84 Ex. 47 Ex. 85 Ex. 48 NR (phr) -- -- 70 60 30 30 30 HNBR (phr) --
-- 30 40 100 70 70 70 Zinc Methacrylate (phr) -- -- 0 0 0 0 0 0
Carbon (FEF grade) (phr) -- -- 30 30 30 5 10 35 Bonding rubber
layer formulation NR (phr) -- -- 60 60 60 60 60 60 NBR (phr) -- --
40 40 40 40 40 40 Aromtic petroleum resin (phr) -- -- 40 40 40 40
40 40 Sulfur (phr) -- -- 2 2 2 2 2 2 Vulcanization accelerator (CZ)
(phr) -- -- 1 1 1 1 1 1 Vulcanization accelerator (TOT-N) (phr) --
-- 0.5 0.5 0.5 0.5 0.5 0.5 Cross-linking agent (TAIC) (phr) -- --
Organic peroxide (phr) -- -- Tire structure Side reinforcing layer
No No Fig. 3(a) Fig. 3(a) Fig. 3(a) Fig. 3(a) Fig. 3(a) Fig. 3(a)
Side reinforcing layer thickness (mm) 0 0 1 1 1 1 1 1 Bonding
rubber layer thickness (mm) -- -- 0.5 0.5 0.5 0.5 0.5 0.5 Side wall
thickness (mm) 3 2.5 1 1 1 1 1 1 Side wall total thickness (mm) 3
2.5 2.5 2.5 2.5 2.5 2.5 2.5 Tire mass (g) 7300 7160 7160 7160 7160
7160 1760 17660 Test results Cut resistance Good Poor Poor Good
Good Poor Good Good Durability Good Good Good Good Good Good Good
Good Rolling resistance (index) 100 98 100 100 99 97 97 100 Comp.
Comp. Comp. Side reinforcing layer formulation Ex. 49 Ex. 86 Ex. 87
Ex. 50 Ex. 88 Ex. 51 NR (phr) 30 30 30 30 30 30 HNBR (phr) 70 70 70
70 70 70 Zinc Methacrylate (phr) 5 10 120 130 60 100 Carbon (FEF
grade) (phr) 0 0 0 0 10 30 Bonding rubber layer formulation NR
(phr) 60 60 60 60 60 60 NBR (phr) 40 40 40 40 40 40 Aromtic
petroleum resin (phr) 40 40 40 40 40 40 Sulfur (phr) 2 2 2 2 2 2
Vulcanization accelerator (CZ) (phr) 1 1 1 1 1 1 Vulcanization
accelerator (TOT-N) (phr) 0.5 0.5 0.5 0.5 0.5 0.5 Cross-linking
agent (TAIC) (phr) Organic peroxide (phr) Tire structure Side
reinforcing layer Fig. 3(a) Fig. 3(a) Fig. 3(a) Fig. 3(a) Fig. 3(a)
Fig. 3(a) Side reinforcing layer thickness (mm) 1 1 1 1 1 1 Bonding
rubber layer thickness (mm) 0.5 0.5 0.5 0.5 0.5 0.5 Side wall
thickness (mm) 1 1 1 1 1 1 Side wall total thickness (mm) 2.5 2.5
2.5 2.5 2.5 2.5 Tire mass (g) 7160 7160 7160 7160 7160 7160 Test
results Cut resistance Poor Good Good Good Good Good Durability
Good Good Good Poor Good Poor Rolling resistance (index) 96 96 97
97 98 100
[0259] From the results of Table XI, it is seen that the tires of
examples using side reinforcing layers having the compositions in
accordance with the present invention all exhibited superior cut
resistance, durability, and rolling resistance.
Examples 89 to 93 and Comparative Examples 52 to 54 (Side
Reinforcing Layer)
[0260] The results of tests on the cut resistance, durability, and
rolling resistance of test tires in the case of changing the ratio
of ingredients in the formulations of the bonding rubber layer and
leaving the composition of the side reinforcing layer and the tire
configuration constant are shown in the following Table XII.
22TABLE XII (Tire Size: 185/65R14) Comp. Comp. Side reinforcing
layer formulation Ex. 52 Ex. 89 Ex. 90 Ex. 53 Ex. 91 Ex. 92 Ex. 54
Ex. 93 NR (phr) 30 30 30 30 30 30 30 30 HNBR (phr) 70 70 70 70 70
70 70 70 Zinc Methacrylate (phr) 60 60 60 60 60 60 60 60 Carbon
(FEF grade) (phr) 10 10 10 10 10 10 10 10 Bonding rubber layer
formulation *1 NR (phr) -- 10 90 60 60 60 60 60 NBR (phr) -- 90 10
40 40 40 40 40 Aromtic petroleum resin (phr) -- 40 40 3 5 80 85 40
Sulfur (phr) -- 2 2 2 2 2 2 Vulcanization accelerator (CZ) (phr) --
1 1 1 1 1 1 Vulcanization accelerator (TOT-N) (phr) -- 0.5 0.5 0.5
0.5 0.5 0.5 Cross-linking agent (TAIC) (phr) -- 3 Organic peroxide
(phr) -- 1.4 Tire structure Side reinforcing layer Fig. (3a) Fig.
(3a) Fig. (3a) Fig. (3a) Fig. (3a) Fig. (3a) Fig. (3a) Fig. (3a)
Side reinforcing layer thickness (mm) 1 1 1 1 1 1 1 1 Bonding
rubber layer thickness (mm) 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Side
wall thickness (mm) 1 1 1 1 1 1 1 1 Side wall total thickness (mm)
2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Tire mass (g) 7160 7160 7160 7160
7160 7160 7160 7160 Test results Cut resistance Good Good Good Good
Good Good Good Good Durability Poor Good Good Poor Good Good Poor
Good Rolling resistance (index) 98 98 98 98 98 98 98 98 *1: Example
of bonding layer made a two-layer structure of TIR of a thickness
of 0.4 mm and UHMwPE (ultrahigh molecular weight polyethylene) of a
thickness of 0.1 mm.
[0261] From the results of Table XII, it is seen that the tires of
examples using bonding rubber layers having the compositions in
accordance with the present invention all exhibited superior cut
resistance, durability, and rolling resistance compared with tires
of Comparative Examples 52, 53, and 54.
Examples 94 to 102 and Comparative Example 55 (Side Reinforcing
Layer)
[0262] The results of tests on the cut resistance, durability, and
rolling resistance of test tires in the case of leaving the
compositions of the side reinforcing layer and bonding rubber layer
constant and changing the arrangement of the side reinforcing layer
in the tire configuration and the thicknesses of the side
reinforcing layer and bonding rubber layer are shown in the
following Table XIII.
23TABLE XIII (Tire Size: 185/65R14) Comp. Side reinforcing layer
formulation Ex. 94 Ex. 95 Ex. 96 Ex. 97 Ex. 55 NR (phr) 30 30 30 30
30 HNBR (phr) 70 70 70 70 70 Zinc Methacrylate (phr) 60 60 60 60 60
Carbon (FEF grade) (phr) 10 10 10 10 10 Bonding rubber layer
formulation *1 NR (phr) 60 60 60 60 60 NBR (phr) 40 40 40 40 40
Aromtic petroleum resin (phr) 40 40 40 40 40 Sulfur (phr) 2 2 2 2 2
Vulcanization accelerator (CZ) (phr) 1 1 1 1 1 Vulcanization
accelerator (TOT-N) (phr) 0.5 0.5 0.5 0.5 0.5 Cross-linking agent
(TAIC) (phr) Organic peroxide (phr) Tire structure Side reinforcing
layer Fig. 3(a) Fig. 3(a) Fig. 3(b) Fig. 3(b) Fig. 3(b) Side
reinforcing layer thickness (mm) 1 1 1 1 0.5 Bonding rubber layer
thickness (mm) 0.1 0.2 1.5 2 2.5 Side wall thickness (mm) 1 1 0 0 0
Side wall total thickness (mm) 2.1 2.2 2.5 3 3 Tire mass (g) 7020
7050 7160 7300 7300 Test results Cut resistance Good Good Good V.
Good V. Good Durability Good Good Good Good Good Rolling resistance
(index) 95 96 99 100 102 Side reinforcing layer formulation Ex. 98
Ex. 99 Ex. 100 Ex. 101 Ex. 105 NR (phr) 30 30 30 30 30 HNBR (phr)
70 70 70 70 70 Zinc Methacrylate (phr) 60 60 60 60 60 Carbon (FEF
grade) (phr) 10 10 10 10 10 Bonding rubber layer formulation NR
(phr) 60 60 60 60 60 NBR (phr) 40 40 40 40 40 Aromtic petroleum
resin (phr) 40 40 40 40 40 Sulfur (phr) 2 2 2 2 2 Vulcanization
accelerator (CZ) (phr) 1 1 1 1 1 Vulcanization accelerator (TOT-N)
(phr) 0.5 0.5 0.5 0.5 0.5 Cross-linking agent (TAIC) (phr) Organic
peroxide (phr) Tire structure Side reinforcing layer Fig. 3(c) Fig.
3(d) Fig. 3(e) Fig. 3(f) Fig. 3(g) Side reinforcing layer range (SH
ratio) 20-80 30-70 40-80 20-60 20-45 55-80 Side reinforcing layer
thickness (mm) 1 1 1 1 1 Bonding rubber layer thickness (mm) 0.5
.times. 2 0.5 0.5 0.5 0.5 Side wall thickness (mm) (Reinforced
part) (mm) 1 1.5 1.5 1.5 1.5 (Nonreinforced part) (mm) 3 3 3 3 3
Side wall total thickness (mm) 3 3 3 3 3 Tire mass (g) 7300 7300
7300 7300 7300 Test results Cut resistance Good Good Good Good Good
Durability Good Good Good Good Good Rolling resistance (index) 98
99 99 99 99
[0263] From the results of Table XIII, it is seen that the tires of
examples configured with the arrangements of side reinforcing
layers and thicknesses of side reinforcing layers and bonding
rubber layers in accordance with the present invention all
exhibited superior cut resistance, durability, and rolling
resistance.
Standard Example 8, Examples 103 to 106, and Comparative Examples
56 to 58 (Side Ribbon)
[0264] The results of tests on the ozone crack resistance,
deterioration resistance, cut resistance, and durability of test
tires in the case of changing the ratio of ingredients in the
formulations of the side ribbon portion and leaving the composition
of the bonding rubber layer and the tire configuration constant are
shown in the following Table XIV.
24TABLE XIV (Tire Size: 185/65R14) Stand. Comp. Comp. Comp. Side
ribbon part formulation Ex. 8 Ex. 56 Ex. 57 Ex. 103 Ex. 104 Ex. 105
Ex. 106 Ex. 58 C1-IIR (phr) 25 EPDM (phr) 25 NR (phr) 50 0 80 70 0
0 0 0 HNBR (phr) 100 20 30 100 100 100 100 Rubber total (phr) 100
100 100 100 100 100 100 100 Zinc methacrylate (phr) 40 40 40 40 0
90 100 Bonding rubber layer formulation *1 NR (phr) -- 60 60 60 60
60 60 NBR (phr) -- 40 40 40 40 40 40 Aromatic petroleum resin (phr)
-- 40 40 40 40 40 40 Sulfur (phr) -- 2 2 2 2 2 2 Vulcanization
accelerator (CZ) -- 1 1 1 1 1 1 (phr) Vulcanization accelerator
(TOT-N) -- 0.5 0.5 0.5 0.5 0.5 0.5 (phr) Cross-linking agent (TAIC)
(phr) -- Organic peroxide (phr) -- Tire structure Need for special
mold Yes No No No No No No No Ribbon part thickness (mm) 3.5 1.0
1.0 1.0 1.0 1.0 1.0 1.0 Existence of protective layer Yes No No No
No No No No Bonding rubber layer thickness -- 0.2 0.2 0.2 0.2 0.2
0.2 0.2 (mm) Total thickness (mm) 4 1.2 1.2 1.2 1.2 1.2 1.2 1.2
Tire mass (g) 7470 7300 7300 7300 7300 7300 7300 7300 Test results
Ozone crack Good V. Good Poor Good V. Good V. Good V. Good V. Good
Deterioration resistance Good V. Good V. Good V. Good V. Good V.
Good V. Good V. Good Cut resistance Good V. Good Poor Good V. Good
Good V. Good V. Good Durability Good Poor Good Good Good Good Good
Poor *1: Bonding layer is two-layer structure of
isobutylene-isoprone copolymer (TIR) rubber layer and ultrhigh
molecular weight UHMwPE) sheet.
[0265] From the results of Table XIV, it is learned that the tires
of examples using side ribbons having the compositions of side
ribbon portions in accordance with the present invention all
exhibited superior ozone crack resistance, deterioration
resistance, cut resistance, and durability.
Standard Example 8, Examples 107 to 111, and Comparative Examples
60 to 61 (Side Ribbon)
[0266] The results of tests on the ozone crack resistance,
deterioration resistance, cut resistance, and durability of test
tires in the case of leaving the compositions of the side ribbon
portions and the bonding rubber layers constant and changing the
thicknesses of the side ribbon portions and bonding rubber layers
in the tire configuration are shown in the following Table XV.
25TABLE XV (Tire Size: 185/65R14) Stand. Comp. Comp. Comp. Side
ribbon part formulation Ex. 8 Ex. 59 Ex. 60 Ex. 107 Ex. 61 Ex. 108
Ex. 109 Ex. 110 Ex. 111 C1-IIR (phr) 25 EPDM (phr) 25 NR (phr) 50 0
0 0 0 0 0 0 0 HNBR (phr) 100 100 100 100 100 100 100 100 Rubber
total (phr) 100 100 100 100 100 100 100 100 100 Zinc methacrylate
(phr) 40 40 40 40 40 40 40 40 Bonding rubber layer formulation *1
NR (phr) -- 60 60 60 60 60 60 60 NBR (phr) -- 40 40 40 40 40 40 40
Aromatic petroleum resin (phr) -- 40 40 40 40 40 40 40 Sulfur (phr)
-- 2 2 2 2 2 2 0 Vulcanization accelerator (CZ) -- 1 1 3 3 3 3
(phr) Vulcanization accelerator (TOT-N) -- 0.5 0.5 4 4 4 4 4 (phr)
Cross-linking agent (TAIC) (phr) -- 3 Organic peroxide (phr) -- 1.4
Tire structure Need for special mold Yes No No No No No No No No
Ribbon part thickness (mm) 3.5 1.0 0.2 0.5 1.0 1.0 1.0 1.0 1.0
Existence of protective layer Yes No No No No No No No No Bonding
rubber layer thickness -- 0.2 0.2 0.2 0 0.1 0.2 1 0.2 (mm) Total
thickness (mm) 4 1.2 0.4 0.7 1.0 1.1 1.2 2.0 1.2 Tire mass (g) 7470
7300 7300 7300 7300 7300 7300 7300 7300 Test results Ozone crack
Good V. Good V. Good V. Good V. Good V. Good V. Good V. Good V.
Good Deterioration resistance Good Good Poor Good Good Good Good
Good Good Cut resistance Good V. Good V. Goor V. Good V. Good V.
Good V. Good V. Good V. Good Durability Good Poor Good Good Poor
Good Good Good V. Good
[0267] From the results of Table XV, it is seen that the tires of
examples configured with the thicknesses of side ribbon portions
and bonding rubber layers in accordance with the present invention
all exhibited superior ozone crack resistance, deterioration
resistance, cut resistance, and durability.
[0268] In the following Standard Example 9, Examples 112 to 128,
and Comparative Examples 62 to 75, test tires of the tire size:
185/65R14 were fabricated using the ingredients of the formulations
shown in the tables and giving the tire configurations listed in
the tables and the results of tests on these were shown.
[0269] The following commercial products were used for the
ingredients for the formulations used in the examples. Note that
the blending agents not changed in amount are not listed in the
tables of the examples.
26 1) Ingredients of Formulations of Air Barrier Layers NR: RSS#3
variate HNBR: Zetpol 2020 (made by Nippon Zeon) variate Zinc
methacrylate: R-20S (made by Asada Chemical Industry) variate
Carbon black (FEF grade): HTC-100 variate (made by Shinnikka
Carbon) Zinc oxide: Zinc White #3 (made by 5 parts by weight Seido
Chemical Industry) Antioxidant: Nauguard 445 (made by 1.5 parts by
weight Uniroyal) Organic peroxide: Parkadox 14/40 5 parts by weight
(made by Kayaku Akzo) 2) Ingredients of Formulations of Bonding
Rubber Layers Diene-based rubber (NR): RSS#3 variate NBR: Nipol
DN401 (made by Nippon Zeon) variate Carbon black: N339 (made by
Showa variate Cabot) Aromatic petroleum resin: FR-120 variate (made
by Fujikosan) Zinc oxide: Zinc White #3 (made by 5 parts by weight
Seido Chemical Industry) Stearic acid: Beads Stearic Acid 1 part by
weight (made by Nippon Oil and Fat) Antioxidant: Nocrac 224 (made
by Ouchi 1 part by weight Shinko Chemical) Sulfur: Insoluble sulfur
2 parts by weight (sulfur vulcanization based) Vulcanization
accelerator: Nocceler 1 part by weight CZ-G (made by Ouchi Shinko
Chemical) (sulfur vulcanization based) Vulcanization accelerator:
Nocceler 0.5 part by weight TOT-N (made by Ouchi Shinko Chemical)
(sulfur vulcanization based) Organic peroxide (40% diluted) 3.5
parts by weight Parkadox 14/40 (made by Kayaku Akzo) (organic
peroxide cross-linking based) Co-cross-linking agent (TAIC): TAIC 3
parts by weight (made by Nippon Kasei Chemical) (organic peroxide
cross-linking based)
[0270] Further, the following commercial products were used for the
ingredients of the formulation in the standard example in Tables
XVI to XVIII. Note that the formulations of the standard example
include ingredients not listed in the tables.
27 Ingredients of Formulation in Air Barrier Layer in Standard
Example Br-IIR: Exxon Bromobutyl 2244 80 parts by weight (made by
Japan Butyl) NR: RSS#3 30 parts by weight Carbon black (FEF grade):
HTC-100 60 parts by weight (made by Shinnikka Carbon) Zinc oxide:
Zinc White #3 (made by 5 parts by weight Seido Chemical Industry)
Stearic acid: Beads Stearic Acid 0.5 part by weight (made by Nippon
Oil and Fat) Antioxidant: Nauguard 445 (made by 1.5 parts by weight
Uniroyal) Petroleum resin: Hiletz G-100X 5 parts by weight (made by
Mitsui Petrochemical) Sulfur: Insoluble sulfur 0.5 part by weight
Vulcanization accelerator: Nocceler DM 1 part by weight (made by
Ouchi Shinko Chemical)
[0271] The methods of measurement and tests in the examples were as
follows:
[0272] 1) High Load Durability Test
[0273] Tires were run under the following conditions and ranked as
"no good" (poor) when trouble occurred and "OK" (good) when it did
not.
[0274] Running conditions: A drum tester having a smooth drum
surface, made of steel, and having an inside diameter of 1707 mm
was used, the ambient temperature was controlled to 38.+-.3.degree.
C., and the tires were run under conditions of a rim size of
14.times.5.5-J, an internal pressure of 240 kPa, and a speed of 81
km/h. The initial load was made 4.6 kN, then the load was increased
to a load of 7.3 kN in 0.7 kN increments every 2 hours. After this,
the load was increased to a load of 14.0 kN in 0.7 kN increments
every 4 hours. The test was ended when running at a load of 14.0 kN
for 4 hours.
[0275] 2) Riding Comfort and Driving Stability Test
[0276] Test tires mounted on 14.times.5.5-J rims at an internal
pressure of 200 kpa were mounted on a 1.6 liter engine displacement
front engine front wheel drive passenger car. The car was driven
over a test course by five trained drivers to evaluate the feeling.
The results were ranked by a five-point system based on the
following judgement criteria in relative comparison with reference
tires. The average of the three drivers, not including the highest
score and lowest score, was shown. The larger the values, the
better.
[0277] 5: Excellent, 4: good, 3.5: somewhat good, 3: equal to
reference, 2.5: somewhat poor (practical lower limit), 2: poor, 1:
very poor
[0278] 3) Air Leakage Test
[0279] The tire was allowed to stand at an initial pressure of 200
kPa, room temperature of 20.degree. C., and no load conditions for
three months. The internal pressure was measured at intervals of
four days. The .alpha. value was found by recurrence to the
following equation where the measurement pressure was Pt, the
initial pressure was P.sub.0, and the number of days elapsed was
t:
Pt/P.sub.0=exp(-.alpha.t)
[0280] Using the .alpha. obtained and substituting 30 (days) for t,
the following was obtained:
.beta.=[1-exp(-.alpha.t)].times.100
[0281] .beta. was made the pressure drop (%/month) per month.
[0282] 4) Rolling Resistance Test
[0283] Tires were run under the following conditions to measure the
rolling resistance at that time. The results were expressed indexed
to the measured value for a tire of a standard example as 100. (The
smaller the value, the better.)
[0284] Running conditions: A drum tester having a smooth drum
surface, made of steel, and having an inside diameter of 1707 mm
was used, the ambient temperature was controlled to 23.+-.2.degree.
C., and the tires were run under conditions of a rim size of
14.times.5.5-J, a test internal pressure of 200 kPa, a load of 4.1
kN, and a speed of 80 km/h.
Standard Example 9, Examples 112 to 118, and Comparative Examples
62 to 65 (Air Barrier Layer)
[0285] The results of tests in the case of changing the compound of
the air barrier layer are shown in Table XVI.
28TABLE XVI <Examples of Changing Air Barrier Layer Compound>
Air barrier layer Stand Comp. Comp. Comp. Ex. Ex. Comp. Ex. Ex. Ex
Ex. Comp. formulation Ex. 9 Ex. 62 Ex. 63 112 113 Ex. 64 114 115
116 117 118 Ex. 65 IIR (phr) 80 NR (phr) 20 40 30 0 30 30 30 30 30
30 30 HNBR (phr) 100 60 70 100 70 70 70 70 70 70 70 Rubber total
(phr) 100 100 100 100 100 100 100 100 100 100 100 100 Zinc
methacrylate (phr) 80 60 60 60 5 10 10 0 60 50 50 Carbon (phr) 60 0
0 0 0 0 0 5 30 0 40 45 Zinc methacrylate + 60 80 60 60 60 5 10 15
30 60 90 95 carbon total (phr) Bonding rubber *1 formulation NR
(phr) - 60 60 60 60 60 60 60 60 60 60 NBR (phr) - 40 40 40 40 40 40
40 40 40 40 Aromatic petroleum resin - 40 40 40 40 40 40 40 40 40
40 (phr) Sulfur (phr) - 2 2 2 2 2 2 2 2 2 2 Vulcanization - 1 1 1 1
1 1 1 1 1 1 accelerator (CZ) (phr) Vulcanization - 0.5 0.5 0.5 0.5
0.5 0.5 0.5 0.5 0.5 0.5 accelerator (TOT-N) (phr) Cross-linking
agent - 0 0 0 0 0 0 0 0 0 0 (TAIC) (phr) Organic peroxlde (phr) - 0
0 0 0 0 0 0 0 0 0 Tire structure Air barrier layer 0.5 0.5 1.1 1.1
1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 thickness (mm) Tie rubber thickness
0.8 (mm) Bonding rubber thickness 0.4 0.2 0.2 0.2 0.2 0.2 0.2 0.2
0.2 0.2 0.2 (mm) Total thickness (mm) 1.3 0.9 1.3 1.3 1.3 1.3 1.3
1.3 1.3 1.3 1.3 1.3 Tire mass (g) 7300 7110 7300 7300 7300 7300
7300 7300 7300 7300 7300 7300 Test results Durability Good Poor
Good Good Good Good Good Good Good Good Good Good Riding comfort
(score) 3 3.5 3.5 3.5 3.5 3.5 3 3 3 3 2 Driving stability 3 3 3 3.5
3.5 2.5 3 3 3.5 3.5 3.5 3.5 (score) Air leakage (index) 100 99 102
100 96 100 100 100 100 100 99 99 Rolling resistance 100 97 97 97 97
97 97 98 99 97 99 99 (index) *1: Bonding layer is two-layer
structure of isobutylene-isoprene coploymer (IIR) rubber layer and
ultrahigh molecular weight (UHMwPE) sheet.
[0286] Despite the use of an air barrier layer with a thickness
smaller than that of a general butyl liner tire (Standard Example
9), the tires of Examples 112 to 118 using the air barrier layer
prescribed in the present invention were not inferior in terms of
the air leakage and exhibited excellent results in terms of the
durability, riding comfort and driving stability, and rolling
resistance. As opposed to this, in the case of Comparative Example
62 using the conventional example (Japanese Unexamined Patent
Publication (Kokai) No. 5-185805) comprised of two layers for the
bonding rubber layer, the tire was inferior in terms of durability
and further was difficult to shape. Further, in the case of
Comparative Example 63 where the amount of formulation of HNBR was
lower than the prescribed amount, the tire exhibited a large air
leakage. It was seen that in Comparative Example 64 where the total
of the zinc methacrylate and the carbon black was less than 10
parts by weight, the driving stability was poor, while in
Comparative Example 65 where it exceeded 90 parts by weight,
conversely the riding comfort was poor.
Standard Example 9, Examples 119 to 123, and Comparative Examples
66 to 70 (Air Barrier Layer)
[0287] The results of tests in the case of leaving the formulation
of the air barrier layer constant and changing the bonding rubber
compound are shown in Table XVII.
29TABLE XVII <Examples of Changing Bonding Rubber Compound>
Stand Comp. Comp. Ex. Ex. Comp. Comp. Ex. Ex. Comp. Ex. Air barrier
layer formulation Ex. 9 Ex. 66 Ex. 67 119 120 Ex. 68 Ex. 69 121 122
Ex. 70 123 IR (phr) 80 NR (phr) 20 HNBR (phr) 100 100 100 100 100
100 100 100 100 100 Rubber total (phr) 100 100 100 100 100 100 100
100 100 100 100 Zinc methacrylate (phr) 80 60 60 60 60 60 60 60 60
60 Carbon (phr) 60 0 0 0 0 0 0 0 0 0 0 Zinc methacrylate I carbon
total 60 80 60 60 60 60 60 60 60 60 60 (phr) Bonding rubber
formulation *1 NR (phr) - 0 10 90 100 60 60 60 60 60 NBR (phr) -
100 90 10 0 40 40 40 40 40 Aromatic petroleum resin (phr) - 40 40
40 40 0 5 80 90 90 Sulfur (phr) - 2 2 2 2 2 2 2 2 0 Vulcanization
accelerator (CZ) - 1 1 1 1 1 1 1 1 0 (phr) Vulcanization
accelerator (TOT-N) - 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0 (phr)
Cross-linking agent (TAIC) (phr) - 0 0 0 0 0 0 0 0 3 Organic
peroxlde (phr) - 0 0 0 0 0 0 0 0 1.4 Tire structure Air barrier
layer thickness (mm) 0.5 0.5 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6
Tie rubber thickness (mm) 0.8 Bonding rubber thickness (mm) 0.4 0.2
0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Total thickness (mm) 1.3 0.9 0.8
0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 Tire mass (g) 7300 7110 7060 7060
7060 7060 7060 7060 7060 7060 7060 Test results Durability Good
Poor Poor Good Good Poor Poor Good Good Poor V. Good Riding comfort
(score) 3 3.5 3.5 3.5 3.5 3.5 3.5 3.5 3.5 3 3.5 Driving stability
(score) 3 3 3.5 3.5 3.5 3.5 3 3.5 3.5 3.5 3.5 Air leakage (index)
100 99 99 99 99 99 99 99 99 99 99 Rolling resistance (index) 100 97
97 97 97 97 97 97 100 101 97
[0288] The tires of Examples 119 to 123 using bonding rubber layers
of the formulations defined in the present invention exhibited
excellent results in terms of the durability, riding comfort and
driving stability, air leakage, and rolling resistance. As opposed
to this, in the case of Comparative Example 67 where the bonding
rubber was only NBR and in the case of Comparative Example 68 where
the bonding rubber was only a diene-based rubber (NR), the tires
exhibited inferior bonding. Further, it was seen that, in the case
of Comparative Example 69 not containing an aromatic petroleum
resin, the predetermined bonding force was not satisfied, while in
the case of Comparative Example 70 containing a larger amount than
80 parts by weight of the aromatic petroleum resin, the rolling
resistance and durability became worse. According to Example 123
where the bonding rubber layer contains a co-cross-linking agent
and is cross-linked by an organic peroxide, it was seen that the
tire was more superior in terms of durability.
Standard Example 9, Examples 124 to 128, and Comparative Examples
71 to 75 (Air Barrier Layer)
[0289] The results of tests in the case of leaving the formulations
of the air barrier layer and bonding rubber layer constant and
changing their thicknesses are shown in Table XVIII.
30TABLE XVIII <Examples of Changing Thickness of Air Barrier
Layer and Bonding Rubber Layer> Stand Comp. Comp. Ex. Ex. Comp.
Comp. Ex. Ex. Ex. Comp. Air barrier layer formulation Ex. 9 Ex. 71
Ex. 72 124 125 Ex. 73 Ex. 74 126 127 128 Ex. 75 IR (phr) 80 NR
(phr) 20 HNBR (phr) 100 100 100 100 100 100 100 100 100 100 Rubber
total (phr) 100 100 100 100 100 100 100 100 100 100 100 Zinc
methacrylate (phr) 80 60 60 60 60 60 60 60 60 60 Carbon (phr) 60 0
0 0 0 0 0 0 0 0 0 Zinc methacrylate I carbon total 60 80 60 60 60
60 60 60 60 60 60 (phr) Bonding rubber formulation *1 NR (phr) --
60 60 60 60 -- 60 60 60 60 NBR (phr) -- 40 40 40 40 -- 40 40 40 40
Aromatic petroleum resin (phr) -- 40 40 40 40 -- 40 40 40 40 Sulfur
(phr) -- 2 2 2 2 -- 2 2 2 2 Vulcanization accelerator (CZ) -- 1 1 1
1 1 1 1 1 1 (phr) Vulcanization accelerator (TOT-N) -- 0.5 0.5 0.5
0.5 0.5 0.5 0.5 0.5 0.5 (phr) Cross-linking agent (TAIC) (phr) -- 0
0 0 0 0 0 0 0 0 Organic peroxlde (phr) -- 0 0 0 0 0 0 0 0 0 Tire
structure Air barrier layer thickness (mm) 0.5 0.5 0.1 0.2 1.2 1.5
0.2 0.2 0.2 0.2 0.2 Tie rubber thickness (mm) 0.8 0.4 Bonding
rubber thickness (mm) 0.2 0.2 0.1 0.1 0 0.1 0.2 1 1.2 Total
thickness (mm) 1.3 0.9 0.3 0.4 1.3 1.6 0.2 0.3 0.4 1.2 1.4 Tire
mass (g) 7300 7110 6810 6860 7300 7450 6770 6810 6860 7250 7350
Test results Durability Good Poor Good Good Good Good Poor Good
Good Good Good Riding comfort (score) 3 3.5 3.5 3.5 3.5 3 3.5 3.5
3.5 3.5 3.5 Driving stability (score) 3 3 3.5 3.5 3.5 3.5 3.5 3.5
3.5 3 3 Air leakage (index) 100 99 101 100 96 93 100 100 100 100
100 Rolling resistance (index) 100 97 97 97 99 99 97 97 98 100
101
[0290] The tires of Examples 124 to 128 selecting the thicknesses
prescribed in the present invention exhibited good results in terms
of the durability, riding comfort and driving stability, air
leakage, and rolling resistance. As opposed to this, the tire of
Comparative Example 72 making the thickness of the air barrier
layer 0.1 mm exhibited an inferior air barrier property. Further,
in the tire of Comparative Example 73 making the thickness of the
air barrier layer 1.5 mm was increased in tire mass. In the tire of
Comparative Example 74 with no bonding rubber layer, the durability
is not satisfied, while in the tire of Comparative Example 75
making the thickness of the bonding rubber 1.2 mm, the tire mass
was increased and the rolling resistance became worse.
[0291] In the following Standard Example 10, Examples 126 to 139,
and Comparative Examples 76 to 83, test tires of a tire size of
185/65R14 were fabricated using the ingredients of the formulations
listed in the tables and giving the tire configurations listed in
the tables and the results of tests on the same were shown.
[0292] The following commercial products were used for the
ingredients of the formulations used in the examples. Note that
blending agents not changed in amount are not listed in the tables
of the examples.
31 1) Ingredients of Formulations of Toe Portion Rubber Members
HNBR: Zetpol 2020 (made by Nippon Zeon) variate Zinc methacrylate:
R-20S (made by variate Asada Chemical Industry) Carbon black (FEF
grade): HTC-100 variate (made by Shinnikka Carbon) Zinc oxide: Zinc
White #3 (made by 5 parts by weight Seido Chemical Industry)
Antioxidant: Nauguard 445 (made by 1.5 parts by weight Uniroyal)
Organic peroxide: Parkadox 14/40 (made 5 parts by weight by Kayaku
Akzo) 2) Ingredients of Formulations of Bonding Rubber Layer
Diene-based rubber (NR): RSS#3 variate NBR: Nipol DN401 (made by
Nippon Zeon) variate Carbon black: N339 (made by Showa 50 parts by
weight Cabot) Aromatic petroleum resin: FR-120 variate (made by
Fujikosan) Zinc oxide: Zinc White #3 (made by 5 parts by weight
Seido Chemical Industry) Stearic acid: Beads Stearic Acid 1 part by
weight (made by Nippon Oil and Fat) Antioxidant: Nocrac 224 (made
by Ouchi 1 part by weight Shinko Chemical) Sulfur: Insoluble sulfur
2 parts by weight (case of sulfur vulcanization based formulation)
Vulcanization accelerator: Nocceler 1 part by weight CZ-G (made by
Ouchi Shinko Chemical) (case of sulfur vulcanization based
formulation) Vulcanization accelerator: Nocceler 0.5 part by weight
TOT-N (made by Ouchi Shinko Chemical) (case of sulfur vulcanization
based formulation) Organic peroxide (40% diluted): Parkadox 14/40
(made by Kayaku Akzo) 5 parts by weight (case of organic peroxide
cross-linking based formulation) Co-cross-linking agent (TAIC):
TAIC 3 parts by weight (made by Nippon Kasei Chemical) (case of
organic peroxide cross-linking based formulation)
[0293] The rubber formulations used in Standard Example 10 and
Comparative Example 76 were as follows:
32 Conv. Ex. Comp. Ex. 1 (Parts (Parts by by Rubber formulation
weight) weight) NR: RSS#3 40 40 BR: Nipol BR1220 (made by Nippon 60
60 Zeon) Carbon black: N326M (made by Showa 60 80 Cabot) Zinc
oxide: Zinc White #3 (made by 5 5 Seido Chemical Industry) Stearic
acid: Beads Stearic Acid 1 1 (made by Nippon Oil and Fat)
Antioxidant: Nocrac 6C (made by 2 2 Ouchi Shinko Chemical) Phenol
resin: Sumicanol 610 (made 6 6 by Sumitomo Chemical) Sulfur:
Insoluble sulfur 5 5 Vulcanization accelerator: 2 2 Nocceler NS-F
(made by Ouchi Shinko Chemical)
[0294] The methods of measurement and evaluation in the examples
were as follows:
[0295] 1) Evaluation of Resistance to Rim Detachment
[0296] Test tires attached to rims of 14.times.5.5J were mounted on
a 1.5 liter engine displacement front engine front wheel drive
passenger car. The car was driven on a test course comprised of a
semicircle having a radius of 6 m and lines connecting with it
shown in FIG. 12 at 35 km/h. The air pressure of the tire of the
left front tire of the test vehicle was reduced from 200 kPa at 10
kPa increments and the air pressure when the rim touched or the
tire detached from the rim was measured.
[0297] The test was conducted five times at different air pressures
(200 kPa, 190 kPa, 180 kPa, . . . ) and the results were expressed
indexed to the measured value for a conventional tire as reference
(100) (reciprocal). The larger the index, the more superior the
resistance to rim detachment.
[0298] 2) Evaluation of Driving Stability
[0299] Test tires attached to rims of 14.times.5.5J were mounted on
a 1.5 liter engine displacement front engine front wheel drive
passenger car. The car was driven to warm up at a high speed for
about 30 minutes. Immediately thereafter, it was driven on a slalom
course comprised of an asphalt paved straight road set with five
pylons at 30 meter intervals and the driving time was measured. The
results were expressed indexed to the time of a conventional tire
as 100 reciprocal). The larger the index, the better the driving
stability.
[0300] 3) Evaluation of Rim Attachment
[0301] Test tires were attached and detached to and from rims of
14.times.5.5J by a rim assembler (Tire Changer MON-21E-4 made by
Hoffman Japan) repeatedly 10 times and the damage to the bead toe
portion was observed. Tires not damaged even after this repeated 10
times of attachment/detachment were ranked as "very good", tires
not damaged after 3 times, but damaged before 10 times were ranked
as "good", and tires damaged before 3 times were ranked as
"poor".
[0302] 4) Evaluation of Fit
[0303] Soap water was lightly coated on the bead portions
contiguous to the rim of the test tire and the tire was attached to
the rim by a rim assembler (Tire Changer MON-21E-4 made by Hoffman
Japan) before the soap water was dried. Next, the tire was filled
to an air pressure of 200 kPa and allowed to stand for 10 minutes,
then the distances between the rim check line at the bead portion
of the tire and the rim flange were measured in a direction
perpendicular to the tire axis at 20 locations at equal intervals
along the circumference and the peak-toe-peak value was found. The
value was expressed indexed to a conventional tire as 100
(reciprocal). The larger the index, the better the fit.
Standard Example 10, Examples 129 to 132, and Comparative Examples
76 to 77 (Bead Toe Portion)
[0304] The results of tests on the resistance to rim detachment,
driving stability, rim attachment, and fit of test tires in the
case of changing the amount of formulation of the hydrogenated NBR
in the toe portion rubber member are shown in the following Table
XIX.
33TABLE XIX (Tire Size 185/65R14) Stand. Comp. Comp. Ex. 10 Ex. 76
Ex. 129 Ex. 130 Ex. 77 Ex. 131 Ex. 132 <Toe portion rubber
member> Formulation A B C C D E F Hydrogenated NBR (parts by 0 0
100 100 60 70 100 weight) Zinc methacrylate (parts by 0 0 80 80 80
80 80 weight) Carbon black (parts by weight) 60 80 0 0 0 0 0 Zinc
methacrylate and carbon 60 80 80 80 80 80 80 black total (parts by
weight) <Bonding rubber layer> Existence of bonding rubber No
No No Yes Yes Yes Yes layer Formulation R R R R Ratio A:B of (A)
diene-based -- -- -- 50:50 50:50 50:50 50:50 rubber and (B) NBR (C)
aromatic petroleum resin -- -- -- 30 30 30 30 to 100 parts by
weight (A) I (B) (parts by weight) Sulfur (parts by weight) -- --
-- 2 2 2 2 Vulcanization accelerator (CZ) -- -- -- 1 1 1 1 parts by
weight) Vulcanization accelerator -- -- -- 0.5 0.5 0.5 0.5 (TOT-N)
(parts by weight) Triallyl isocyanurate (parts -- -- -- 0 0 0 0 by
weight) Organic peroxide (parts by -- -- -- 0 0 0 0 weight)
Thickness of bonding rubber -- -- -- 0.5 0.5 0.5 0.5 layer (mm)
<Evaluation> Resistance to rim detachment 100 121 121 121 106
106 121 (index) Driving stability (index) 100 106 107 106 97 101
106 Rim attachment Good Poor V. Good V. Good V. Good V. Good V.
Good Fit (index) 100 99 101 100 102 101 100
[0305] From the results of Table XIX, it is seen that the tires of
examples using rubber members of toe portion having the
compositions of the hydrogenated NBR in accordance with the present
invention all exhibited superior resistance to rim detachment,
driving stability, rim attachment, and fit.
Standard Example 10, Examples 133 to 135, and Comparative Examples
78 to 81 (Bead Toe Portion)
[0306] The results of tests on the resistance to rim detachment,
driving stability, rim attachment, and fit of test tires in the
case of changing the amounts of formulation of zinc methacrylate
and carbon black in the rubber members of the toe portion are shown
in the following Table XX.
34TABLE XX (Tire Size 185/65R14) Stand. Comp. Comp. Comp. Comp. Ex.
10 Ex. 78 Ex. 133 Ex. 134 Ex. 79 Ex. 135 Ex. 80 Ex. 81 <Toe
portion rubber member> Formulation A G H I J K L M Hydrogenated
NBR (parts by 0 100 100 100 100 100 100 100 weight) Zinc
methacrylate (parts by 0 10 20 120 130 80 80 100 weight) Carbon
black (parts by weight) 60 0 0 0 0 40 45 30 Zinc methacrylate and
carbon 60 10 20 120 130 120 125 130 black total (parts by weight)
<Bonding rubber layer> Existence of bonding rubber No Yes Yes
Yes Yes Yes Yes Yes layer Formulation R R R R R R R Ratio A:B of
(A) diene-based -- 50:50 50:50 50:50 50:50 50:50 50:50 50:50 rubber
and (B) NBR (C) aromatic petroleum resin -- 30 30 30 30 30 30 30 to
100 parts by weight (A) + (B) (parts by weight) Sulfur (parts by
weight) -- 2 2 2 2 2 2 2 Vulcanization accelerator (CZ) -- 1 1 1 1
1 1 1 parts by weight) Vulcanization accelerator -- 0.5 0.5 0.5 0.5
0.5 0.5 0.5 (TOT-N) (parts by weight) Triallyl isocyanurate (parts
-- 0 0 0 0 0 0 0 by weight) Organic peroxide (parts by -- 0 0 0 0 0
0 0 weight) Thickness of bonding rubber -- 0.5 0.5 0.5 0.5 0.5 0.5
0.5 layer (mm) <Evaluation> Resistance to rim detachment 100
95 103 121 131 131 131 131 (index) Driving stability (index) 100 94
101 105 106 104 104 105 Rim attachment Good V. Good V. Good V. Good
Poor V. Good Poor Poor Fit (index) 100 103 103 102 98 101 98 97
[0307] From the results of Table XX, it is seen that the tires of
examples using rubber members of toe portion having the
compositions of zinc methacrylate and carbon black in accordance
with the present invention all exhibited superior resistance to rim
detachment, driving stability, rim attachment, and fit.
Standard Example 10 and Examples 136 to 137 (Bead Toe Portion)
[0308] The results of tests on the resistance to rim detachment,
driving stability, rim attachment, and fit of test tires in the
case of changing the ratio of formulation of the (A) diene-based
rubber and (B) NBR in the bonding rubber layer are shown in the
following Table XXI.
35TABLE XXI (Tire Size: 185/65R14) Stand. Ex. Ex. Ex. 10 136 137
<Toe portion rubber A C C members> Hydrogenated NBR (parts by
0 100 100 weight) Zinc methacrylate (parts by 0 80 80 weight)
Carbon black (parts by 0 0 0 weight) Total of zinc methacrylate 60
80 80 and carbon black (parts by weight) <Bonding rubber
layer> Existence of bonding rubber No Yes Yes layer Formulation
U V Ratio of formulation A:B of -- 10:90 90:10 (A) diene-based
rubber and (B) NBR (C) Aromatic petroleum -- 30 30 resin to 100
parts by weight of (A) + (B) (parts by weight) Sulfur (parts by
weight) -- 2 2 Vulcanization accelerator -- 1 1 (CZ) (parts by
weight) Vulcanization accelerator -- 0.5 0.5 (TOT-N) (parts by
weight) Triallyl isocyanurate -- 0 0 (parts by weight) Organic
peroxide (parts by -- 0 0 weight) Thickness of bonding rubber --
0.5 0.5 layer (mm) <Evaluation> Resistance to rim 100 121 121
detachment (index) Driving stability (index) 100 104 105 Rim
attachment Good V. Good V. Good Fit (index) 100 102 101
[0309] From the results of Table XXI, it is seen that the tires of
examples using bonding rubber layers having the compositions of
bonding rubber layers in accordance with the present invention all
exhibited superior resistance to rim detachment, driving stability,
rim attachment, and fit.
Standard Example 10, Examples 138 to 142, and Comparative Examples
82 to 83 (Bead Toe Portion)
[0310] The results of tests on the resistance to rim detachment,
driving stability, rim attachment, and fit of test tires in the
case of changing the thickness of the bonding rubber layer are
shown in the following Table XXII.
36TABLE XXII (Tire Size 185/65R14) Stand Comp. Comp. Ex. 10 Ex. 82
Ex. 138 Ex. 139 Ex. 140 Ex. 141 Ex. 83 Ex. 142 <Toe portion
rubber member> Formulation A A C C C C C C Hydrogenated NBR
(parts by 0 0 100 100 100 100 100 100 weight) Zinc methacrylate
(parts by 0 0 80 80 80 80 80 80 weight Carbon black (parts by
weight) 60 60 0 0 0 0 0 0 Zinc met.hacrylate and carbon 60 60 80 80
80 80 80 80 black total (parts by weiqht) <Bonding rubber
layer> Existence of bonding rubber No Yes Yes Yes Yes Yes Yes
Yes layer Formulation R R R R R R S Ratio A:B of (A) diene-based --
50:50 50:50 50:50 50:50 50:50 50:50 50:50 rubber and (B) NBR (C)
aromatic petroleum resin -- 30 30 30 30 30 30 30 to 100 parts by
weight (A) + (B) (parts by weight) Sulfur (parts by weight) -- 2 2
2 2 2 2 0 Vulcanization accelerator (CZ) -- 1 1 1 1 1 1 0 parts by
weight) Vulcanization accelerator -- 0.5 0.5 0.5 0.5 0.5 0.5 0.5
(TOT-N) (parts by weight) Triallyl isocyanurate (parts -- 0 0 0 0 0
0 3 by weight) Organic peroxide (parts by -- 0 0 0 0 0 0 2 weight)
Thickness of bonding rubber -- 0.05 0.1 0.2 0.8 1.5 2.0 0.5 layer
(mm) <Evaluation> (Prod Resistance to rim detachment 100
ucti- 121 121 113 106 100 113 (index) vity Driving stability
(index) 100 poor) 105 104 103 102 101 103 Rim attachment Good V.
Good V. Good V. Good V. Good V. Good V. Good Fit (index) 100 103
102 102 100 97 102
[0311] From the results of Table XXII, it is seen that the tires of
examples using bonding rubber layers having thicknesses of bonding
rubber layers in accordance with the present invention all
exhibited superior resistance to rim detachment, driving stability,
rim attachment, and fit.
[0312] The following commercial products were used for the
ingredients for the formulations in the predetermined parts and
bonding rubber layers used for the following Standard Examples 11
to 12, Examples 143 to 154, and Comparative Examples 84 to 86. Note
that, in the ingredients of the formulations of the bonding rubber
layers, the blending agents not changed in amount are not listed in
the tables of the examples.
37 1) Ingredients of Formulations of Tire Parts TABLE XXIII
Formulation of Tire Parts of Examples Formul- Formul- Formul-
Formul- Formul- Formul- Formul- Formul- ation 1 ation 2 ation 3
ation 4 ation 5 ation 6 ation 7 ation 8 Cap Carcass Belt Bead side
Cushion Insul- Base Name of tread coat coat filler wall rubber tion
tire* Part name product Manufacturer Formulation (phr) Natural
rubber RSS #3 40 20 20 20 BR Nipol BR- Nippon Zeon 30 1220
Hydrogenated NBR Zetpol Nippon Zeon 100 60 80 100 70 80 80 100 2020
Zinc R-20S Asada 40 50 70 100 40 70 70 60 methacrylate Chemical
Industry Carbon (HAF N339 Showa Cabot 20 grade) Carbon (FEF HTC-100
Shinnikka 10 10 10 10 grade) Carbon Zinc oxide Zinc white Seido
Chemical 3 3 3 5 3 3 3 3 #3 Industry Plasticizer DOP Mitsubishi Gas
10 Chemical Antioxidant Nauguard Uniroyal 1.5 1.5 1.5 1.5 1.5 1.5
1.5 1.5 445 Cross-linking Perkadox Kayaku Akzo 5 5 5 8 3.5 5 5 5
agent 14/40 Co-cross-linking TAIC Nippon Kaser 2 2 2 3 2 2 2 2
agent Chemical 2) Ingredients of Formulations of Bonding Rubber
Layer Diene-based rubber (NR): RSS#3 variate NBR: Nipol DN401 (made
by Nippon Zeon) variate Carbon black: N339 (made by Showa 50 parts
Cabot) by weight Aromatic petroleum resin: FR-120 variate (made by
Fujikosan) Zinc oxide: Zinc White #3 (made by 5 parts Seido
Chemical Industry) by weight Stearic acid: Beads Stearic Acid 1
part (made by Nippon Oil and Fat) by weight Antioxidant: Nocrac 224
(made by 1 part Ouchi Shinko Chemical) by weight Sulfur: Insoluble
sulfur 2 parts by weight (case of sulfur vulcanization)
Vulcanization accelerator: Nocceler 1 part CZ-G (made by Ouchi
Shinko Chemical) by weight (case of sulfur vulcanization)
Vulcanization accelerator: Nocceler 0.5 part TOT-N (made by Ouchi
Shinko Chemical) by weight (case of sulfur vulcanization) Organic
peroxide (40% diluted) variate Parkadox 14/40 (made by Kayaku Akzo)
(case of organic peroxide cross-linking) Co-cross-linking agent:
TAIC (made by variate Nippon Kasei Chemical) (case of organic
peroxide cross-linking) 3) Ingredients of Conventional Formulations
of Tire Parts [1] Conventional Formulation of Cap Tread 50 parts
NR: RSS#3 by weight SBR: Nipol 1502 (made by Nippon Zeon) 50 parts
by weight Carbon black (HAF grade) N339 (made 50 parts by Showa
Cabot) by weight Zinc oxide: Zinc White #3 (made by 3 parts Seido
Chemical Industry) by weight Stearic acid: Beads Stearic Acid 1
part (made by Nippon Oil and Fat) by weight Aromatic oil: Komorex
300 (made by 10 parts Nippon Oil) by weight Antioxidant: Nocrac 6C
(made by Ouchi 1.5 parts Shinko Chemical) by weight Wax: Sunnoc
(made by Ouchi Shinko 5 parts Chemical) by weight Sulfur: Sanfer
(made by Sanshin 2 parts Chemical) by weight Vulcanization
accelerator: Nocceler 1 part NS-F (made by Ouchi Shinko Chemical)
by weight [2] Conventional Formulation of Carcass Coat 70 parts NR:
RSS#3 by weight SBR: Nipol 1502 (made by Nippon Zeon) 30 parts by
weight Carbon black (FEF grade) HTC-100 50 parts (made by Shinnikka
Carbon) by weight Zinc oxide: Zinc White #3 (made by 5 parts Seido
Chemical Industry) by weight Stearic acid: Beads Stearic Acid (made
1 part by Nippon Oil and Fat) by weight Aromatic oil: Komorex 300
(made by 8 parts Nippon Oil) by weight Antioxidant: Nocrac 224
(made by 1.5 parts Ouchi Shinko Chemical) by weight Sulfur: Sanfer
(made by Sanshin 2.5 parts Chemical) by weight Vulcanization
accelerator: Nocceler 1 part CZ-C (made by Ouchi Shinko Chemical)
by weight Vulcanization accelerator: Nocceler 1.5 parts NS-F (made
by Ouchi Shinko Chemical) by weight [3] Conventional Formulation of
Belt Coat 100 parts NR: RSS#3 by weight Carbon black (HAE grade) :
N339 (made by 60 parts Showa Cabot) by weight Zinc oxide: Zinc
White #3 (made by 7 parts Seido Chemical Industry) by weight
Stearic acid: Beads Stearic Acid 0.5 part (made by Nippon Oil and
Fat) by weight Antioxidant: Nocrac 224 (made by Ouchi 2 parts
Shinko Chemical) by weight Cobalt stearate (made by Dainippon Ink 1
part and Chemicals) by weight RF resin: Sumicanol 610 (made by 2
part Sumitomo Chemical) by weight Sulfur: Sanfer (made by Sanshin 5
parts Chemical) by weight Vulcanization accelerator: Nocceler 1
part CZ-G (made by Ouchi Shinko Chemical) by weight [4]
Conventional Formulation of Bead Filler 80 parts NR: RSS#3 by
weight SBR: Nipol 1502 (made by Nippon Zeon) 20 parts by weight
Carbon black (HAF grade) : N339 (made 70 parts by Showa Cabot) by
weight Zinc oxide: Zinc White #3 (made by 5 parts Seido Chemical
Industry) by weight Stearic acid: Beads Stearic Acid 1 part (made
by Nippon Oil and Fat) by weight Aromatic oil: Komorex 300 (made by
5 parts Nippon Oil) by weight Antioxidant: Nocrac 224 (made by
Ouchi 1.5 parts Shinko Chemical) by weight Sulfur: Sanfer (made by
Sanshin 3 parts Chemical) by weight Vulcanization accelerator:
Nocceler 1 part CZ-G (made by Ouchi Shinko Chemical) by weight [5]
Conventional Formulation of Side Wall 60 parts NR: RSS#3 by weight
BR: Nipol BR1220 (made by Nippon Zeon) 40 parts by weight Carbon
black (FEF grade) : HTC-100 50 parts (made by Shinnikka Carbon) by
weight Zinc oxide: Zinc White #3 (made by 5 parts Seido Chemical
Industry) by weight Stearic acid: Beans Stearic Acid 1 part (made
by Nippon Oil and Fat) by weight Aromatic oil: Komorex 300 (made by
8 parts Nippon Oil) by weight Antioxidant: Nocrac 6C (made by Ouchi
1 part Shinko Chemical) by weight Antioxidant: Nocrac 224 (made by
Ouchi 0.5 parts Shinko Chemical) by weight Wax: Sunnoc (made by
Ouchi Shinko 1 part Chemical) by weight Sulfur: Sanfer (made by
Sanshin 2 parts Chemical) by weight Vulcanization accelerator:
Nocceler 1 part NS-F (made by Ouchi Shinko Chemical) by weight [6]
Conventional Formulation of Bead Insulation NR: RSS#3 70 parts by
weight SBR: Nipol 1502 (made by Nippon Zeon) 30 parts by weight
Carbon black (FEF grade) : HTC-100 70 parts (made by Shinnikka
Carbon) by weight Clay: T clay (made by Nippon Talc) 10 parts by
weight Zinc oxide: Zinc White #3 (made by 3 parts Seido Chemical
Industry) by weight Stearic acid: Beads Stearic Acid (made 2 parts
by Nippon Oil and Fat) by weight Aromatic oil: Komorex 300 (made by
10 parts Nippon Oil) by weight Antioxidant: Nocrac 224 (made by
Ouchi 1 part Shinko Chemical) by weight Sulfur: Sanfer (made hy
Sanshin 4 parts Chemical) by weight Vulcanization accelerator:
Nocceler 1 part NS-F (made by Ouchi Shinko Chemical) by weight
[0313] The test tires used in the following examples were
fabricated as follows:
Fabrication of Test Tires
[0314] Parts and bonding rubber layers comprised of compositions of
the formulations shown in the examples were successively arranged
and bonded at predetermined positions in accordance with the tire
configurations of the examples to prepare test tires (size:
185/65R14) for use in the following tests.
[0315] The test and evaluation methods in the examples were as
follows:
[0316] 1) Durability Test Method
[0317] Tires were run under the following conditions and ranked as
failing (poor) when trouble occurred and passing (good) when it did
not.
[0318] Running conditions: A drum tester having a smooth drum
surface, made of steel, and having an inside diameter of 1707 mm
was used, the ambient temperature was controlled to 38.+-.3.degree.
C., and the tires were run under conditions of a rim size of
14.times.5 1/2JJ, an internal pressure of 180 kPa, and a speed of
80 km/h under a load of 4.42 kN for 4 hours, then under a load of
4.68 kN for 6 hours, then under a load of 5.20 kN for 24 hours.
Here, the running was stopped once, then if no abnormalities were
observed in the appearance, it was resumed under a load of 5.98 kN
for 4 hours, then under a load of 6.76 kN for 2 hours.
[0319] When judged as passing (good), the tires were further run
under a load of 6.76 kN for 2 hours, then under a load of 7.28 kN
for 4 hours, then under a load of 8.32 kN for 4 hours. At this
time, when there was no trouble in the appearance or inside, the
tires were judged as passing (very good).
[0320] 2) Rolling Resistance Test Method
[0321] Tires were run under the following conditions to measure the
rolling resistance at that time. The results were expressed indexed
to the measured value for a conventional tire as 100. (The smaller
the value, the better.)
[0322] Running conditions: A drum tester having a smooth drum
surface, made of steel, and having an inside diameter of 1707 mm
was used, the ambient temperature was controlled to 23.+-.2.degree.
C., and the tires were run under conditions of a rim size of
14.times.5 1/2JJ, an internal pressure of 200 kPa, and a speed of
80 km/h.
[0323] 3) Vehicular Driving Stability Test Method
[0324] Test tires mounted on 14.times.5 1/2JJ rims at an internal
pressure of 200 kPa were mounted on a 1.6 liter engine displacement
front engine front wheel drive compact passenger car. The car was
driven over a test course by five trained drivers to evaluate the
feeling. The results were ranked by a five-point system based on
the following judgement criteria in relative comparison with
reference tires. The average of the three drivers, not including
the highest score and lowest score, was shown. (The larger the
values, the better.)
[0325] 5: Excellent, 4: good, 3.5: somewhat good, 3: equal to
reference, 2.5: somewhat poor (practical lower limit), 2: poor, 1:
very poor
[0326] 4) Abrasion Resistance Test Method
[0327] Test tires were mounted on the four wheels of a 1.6 liter
engine displacement compact passenger car. This was driven 10,000
km on a predetermined course and the average amount of abrasion for
the four tires was measured. The result was expressed indexed to
the amount of abrasion of a cap tread of a conventional formulation
as 100. (The larger the value, the more resistant to abrasion.)
[0328] 5) Cut Resistance Test Method
[0329] Tires were run under the following conditions to find the
average value of the critical speed at which tires do not burst.
When the average value of the critical speed was less than that of
a conventional tire, the tire was rated "no good" (Poor), while
when it was the same as or higher than that of a conventional tire,
it was rated "good" (Good). Further, when the average value of the
critical speed was more than 2 km/h higher than that of the
conventional tire, it was rated "very good" (V.Good).
[0330] Running conditions: Test tires were mounted on a 1.6 liter
engine displacement front engine front wheel drive compact
passenger car with a rim size of 14.times.5 1/2JJ and an internal
pressure of 200 kPa and were driven over a steel rail of a height
of 100 mm as shown below at an angle of 30.degree.. The speed at
this time was changed from 10 km/h in steps of 1.0 km/h. The
critical speed at which the tires would not burst was investigated
by n=3 and the cut resistance was evaluated from that average
value.
[0331] 6) Air Leakage Test Method
[0332] The tire was allowed to stand at an initial pressure of 200
kPa, room temperature of 21.degree. C., and no load conditions for
three months. The internal pressure was measured at intervals of
four days. The a value was found by recurrence to the following
equation where the measurement pressure was Pt, the initial
pressure was P.sub.0, and the number of days elapsed was t:
Pt/P.sub.0=exp(-.alpha.t)
[0333] Using the .alpha. obtained and substituting 30 (days) for t,
the following was obtained:
.beta.=[1-exp(-.alpha.t)].times.100
[0334] .beta. was made the air leakage (%/month) per month.
Standard Example 11, Example 143 to 147, and Comparative Example 84
to 86
[0335] These examples show the results of tests on the durability
and rolling resistance of test tires (configurations of FIG. 7)
using a rubber containing the hydrogenated NBR for the carcass
coat, belt coat, rubber between belt end layers, and rubber between
belt end and carcass layer (cushion rubber) and using conventional
formulations of rubber (diene-based rubber) for other part members.
The results are shown in Table XXIV.
38TABLE XXIV (Tire Size: 185/65R14) Stand. Bonding rubber Ex.11
Comp. Ex. Ex. Comp. Ex. Ex. Comp. Ex. formulation (Control) Ex. 84
143 144 Ex. 85 145 146 Ex. 86 147 NR (phr) -- 10 90 60 60 60 60 60
NBR (phr) -- 90 10 40 40 40 40 40 Aromatic petroleum resin -- 40 40
3 5 80 85 40 (phr) Sulfur (phr) Vulcanization -- 2 2 2 2 2 2
acceleratar (CZ) (phr) -- 1 1 1 1 1 1 Vulcanizatian accel- -- 0.5
0.5 0.5 0.5 0.5 0.5 erator (TOT-N) (phr) Co-cross-linking agent: --
3 (TAIC) (phr) Organic peroxide (phr) -- 1.4 IIR sheet (mm) 0.4
Ultrahigh molecular 0.1 weight PE sheet (mm) Test results *
Durability V. Good Poor Good Good Poor Good Good Poor V. Good
Rolling resistance 100 96 96 96 96 96 97 97 96 (index) *
Composition of Japanese Unexamined Patent Publication (Kokai) No.
5-185805
[0336] Standard Example 11: Conventional tire having carcass coat
and belt coat of conventional rubber formulations.
[0337] Comparative Example 84: Example where bonding layer is made
two-layer structure of IIR of thickness of 0.4 mm and UHMwPE
(ultrahigh molecular weight polyethylene) of thickness of 0.1 mm.
(Bond poor and durability no good.)
[0338] The thicknesses of the bonding rubber layers in the
following Example 143, Comparative Example 85 and the subsequent
Examples thereof were entirely made 0.5 mm.
[0339] Example 143: Example where the ratio of rubbers in bonding
rubber is NR/NBR=10/90.
[0340] Example 144: Example where the ratio of rubbers in bonding
rubber is NR/NBR=90/10.
[0341] Comparative Example 85: Example where the amount of aromatic
petroleum resin formulated in bonding rubber is less than lower
limit. (Bond poor and durability no good.)
[0342] Example 145: Example where the amount of aromatic petroleum
resin formulated in bonding rubber is lower limit.
[0343] Example 146: Example where the amount of aromatic petroleum
resin formulated in bonding rubber is upper limit.
[0344] Comparative Example 86: Example where the amount of aromatic
petroleum resin formulated in bonding rubber exceeds upper limit.
(Bond poor and durability no good.)
[0345] Example 147: Example of case of blending co-cross-linking
agent in bonding rubber and cross-linking by organic peroxide.
(Bond good and durability further improved.)
Standard Example 12 and Examples 148 to 154
[0346] These examples show the results of tests on the durability,
rolling resistance, vehicular driving stability, abrasion
resistance, cut resistance, and air barrier property of test tires
(configurations of FIG. 7 to FIG. 11) using a rubber containing the
hydrogenated NBR for different predetermined part members and using
conventional formulations of rubber (diene-based rubber) for other
than the predetermined part members. The results are shown in Table
XXV.
39Table XXV (Tire Size: 185/65R14) Stand. Bonding rubber
formulation Ex. 12 Ex. 148 Ex. 149 Ex. 150 Ex. 151 Ex. 152 Ex. 153
Ex. 154 NR (phr) -- 60 60 60 60 60 -- -- NBR (phr) -- 40 40 40 40
40 -- -- Aromatic petroLeum resin -- 30 30 30 30 30 -- -- (phr)
Sulfur (phr) -- 2 2 2 2 2 -- -- Vulcanization accelerator -- 1 1 1
1 1 -- -- (CZ) (phr) Vulcanization accelerator -- 0.5 0.5 0.5 0.5
0.5 -- -- (TOT-N) (phr) Co-cross-inking agent -- (TAIC) (phr)
Organic perioxide (phr) -- Tire configuration Member comprised by
rubber No *6 *7 *8 *9 *10 *11 (see *12 (see including hydrogenated
NBR (Fig. 7) (Fig. 8) (Fig. 9) (Fig. 11) (Fig. 10) (Fig. 10) Cap
tread C. form. C. form. C. form. C. form. C. form. C. form. Form. 1
Form. 1 Carcass coat C. form. Form. 2 Form. 2 Form. 2 Form. 2 Form.
2 Form. 2 Form. 8 Belt coat C. form. Form. 3 Form. 3 Form. 3 Form.
3 Form. 3 Form. 3 Form. 8 Bead filler C. form. C. form. C. form.
Form. 4 Form. 4 Form. 4 Form. 4 Form. 8 Side wall C. form. C. form.
C. form. C. form. Form. 5 Form. 5 Form. 5 Form. 8 Bead insulation
C. form. C. form. C. form. C. form. C. form. C. form. C. form.
Form. 8 Bonding rubber thickness -- 0.5 0.5 0.5 0.5 0.5 -- -- (mm)
Inner liner Yes Yes No Yes Yes Yes No No Mass (g) 7300 7350 6940
6860 6800 6850 6850 6880 Test results Durability V. Good Good Good
Good Good Good Good Good Rolling resistance (index) 100 96 94 95 93
93 91 91 Vehicular driving stability 3.0 3.0 3.0 3.2 3.2 3.3 3.2
3.3 Abrasion resistance (index) 100 100 100 100 100 100 125 125 Cut
resistance Good Good Good Good V. Good V. Good V. Good V. Good Air
leakage (%/month) 3.0 2.7 3 2.7 2.5 2.5 2.6 2.6
[0347] Standard Example 12: Conventional tire where all part
members are constituted by conventional formulations of rubber.
[0348] *6. Example 148: Tire where carcass coat, belt coat, rubber
between belt end layers (cushion rubber), and rubber between belt
end and carcass layer (cushion rubber) are constituted by a rubber
containing the hydrogenated NBR. (Rolling resistance and air
barrier property improved.)
[0349] *7. Example 149: Tire where members are made of a rubber
containing the hydrogenated NBR same as *6. Inner layer omitted.
(Lightening in weight and rolling resistance improved while
maintaining air barrier property.)
[0350] *8. Example 150: Tire where, in addition to *6, bead filler
is also constituted by a rubber containing the hydrogenated NBR.
(Rolling resistance and air barrier property improved and, further,
vehicular driving stability improved.)
[0351] *9. Example 151: Tire where, in addition to *6, bead filler
and side wall are also constituted by a rubber containing the
hydrogenated NBR. (Rolling resistance, air barrier property, and
vehicular driving stability improved and, further, cut resistance
improved.)
[0352] *10. Example 152: Tire where all members other than cap
tread and bead insulation are constituted by a rubber containing
the hydrogenated NBR. (Vehicular driving stability improved further
compared with Example 151.)
[0353] *11. Example 153: Tire where all members other than bead
insulation are constituted by a rubber containing the hydrogenated
NBR. (Large improvement in abrasion resistance compared with
Example 152 (conventional cap tread).)
[0354] *12. Example 154: Tire where all rubber members are
constituted by a rubber containing the hydrogenated NBR (tire
casing portion is constituted by single compound). (Tire exhibited
good results in all test items and was extremely superior in
productivity.)
[0355] As will be understood from Examples 148 to 154, according to
the present invention, by using a rubber containing a predetermined
hydrogenated NBR for predetermined parts or all of the part members
in a pneumatic tire and using a predetermined bonding rubber layer
for the bonding layer between the rubber containing the
hydrogenated NBR and adjoining parts comprised of other general
purpose rubber, it is possible to obtain a pneumatic tire which is
lightened in the weight of the tire and improves the
characteristics such as the durability, rolling resistance,
vehicular driving stability, cut resistance, and air leakage.
Capability of Utilization in Industry
[0356] As explained above, according to the present invention, by
using a rubber containing a predetermined hydrogenated NBR for
predetermined parts or all of the part members in a pneumatic tire
and using a predetermined bonding rubber layer for the bonding
layer between the rubber containing the hydrogenated NBR and the
adjoining other general purpose rubber, it is possible to obtain a
pneumatic tire which lightens the weight of the tire, improves the
characteristics such as the durability, rolling resistance,
vehicular driving stability, cut resistance, and air leakage or can
be decorated.
* * * * *