U.S. patent application number 13/108298 was filed with the patent office on 2011-09-08 for poorly air-permeable rubber laminate composed of poorly air-permeable resin and rubber composition, and method for production thereof.
This patent application is currently assigned to The Yokohama Rubber Co., Ltd.. Invention is credited to Naoyuki Morooka.
Application Number | 20110217536 13/108298 |
Document ID | / |
Family ID | 37899939 |
Filed Date | 2011-09-08 |
United States Patent
Application |
20110217536 |
Kind Code |
A1 |
Morooka; Naoyuki |
September 8, 2011 |
POORLY AIR-PERMEABLE RUBBER LAMINATE COMPOSED OF POORLY
AIR-PERMEABLE RESIN AND RUBBER COMPOSITION, AND METHOD FOR
PRODUCTION THEREOF
Abstract
A method for producing a laminate (E) of a low air permeable
resin/rubber composition comprising: laminating a laminate (D) of a
low air permeable resin (A) layer having an air permeation
coefficient of 1.0.times.10.sup.-12 cccm/cm.sup.2 or less and an
average thickness d (.mu.m) of 0.05<d<5 and a thermoplastic
resin composition (B) layer with a rubber composition (E) layer so
as to form (B)/(A)/(E), followed by vulcanization, and peeling off
only the thermoplastic resin composition (B) from the laminate, as
well as the laminate thereof.
Inventors: |
Morooka; Naoyuki;
(Hiratsuka-shi, JP) |
Assignee: |
The Yokohama Rubber Co.,
Ltd.
Tokyo
JP
|
Family ID: |
37899939 |
Appl. No.: |
13/108298 |
Filed: |
May 16, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12088607 |
Mar 28, 2008 |
7976666 |
|
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PCT/JP2006/320022 |
Sep 29, 2006 |
|
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13108298 |
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Current U.S.
Class: |
428/220 |
Current CPC
Class: |
B32B 1/08 20130101; Y10T
428/265 20150115; B29C 48/21 20190201; B32B 2307/748 20130101; B32B
27/34 20130101; B29C 48/08 20190201; B32B 2307/7242 20130101; B32B
27/08 20130101; B29L 2030/008 20130101; Y10T 428/1379 20150115;
B32B 27/30 20130101; B32B 2038/0076 20130101; B29D 30/0681
20130101; B32B 2305/77 20130101; B29C 48/07 20190201; B32B 25/08
20130101; B29D 2030/0682 20130101; B60C 5/14 20130101; B60C 1/0008
20130101; B32B 37/025 20130101 |
Class at
Publication: |
428/220 |
International
Class: |
B32B 3/00 20060101
B32B003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 30, 2005 |
JP |
2005-288219 |
Claims
1. A laminate (F) of a low air permeable resin/rubber composition
comprising a low air permeable resin (A) layer having an air
permeation coefficient of 1.0.times.10.sup.-12 cccm/cm.sup.2seccmHg
or less and an average thickness d (.mu.m) of 0.05<d<5,
laminated to at one surface of a rubber composition (E) layer.
2. A laminate (F) of a low air permeable resin/rubber composition
as claimed in claim 1, wherein the average thickness d of the low
air permeable resin (A) layer is 1 to 3 .mu.m.
3. A laminate (F) of a low air permeable resin/rubber composition
as claimed in claim 1, wherein the low air permeable resin (A) is
an ethylene-vinyl alcohol copolymer.
4. A laminate (F) of a low air permeable resin/rubber composition
as claimed in claim 1, wherein an ethylene ratio of the
ethylene-vinyl alcohol copolymer is 50 mol % or less.
5. A laminate (F) of a low air permeable resin/rubber composition
as claimed in claim 2, wherein the low air permeable resin (A) is
an ethylene-vinyl alcohol copolymer.
6. A laminate (F) of a low air permeable resin/rubber composition
as claimed in claim 2, wherein an ethylene ratio of the
ethylene-vinyl alcohol copolymer is 50 mol % or less.
7. A laminate (F) of a low air permeable resin/rubber composition
as claimed in claim 3, wherein an ethylene ratio of the
ethylene-vinyl alcohol copolymer is 50 mol % or less.
Description
CROSS REFERENCE TD RELATED APPLICATIONS
[0001] This application is a Divisional of co-pending application
Ser. No. 12/088,607, filed On Mar. 28, 2608 and for which priority
is claimed under 35 U.S.C. .sctn.120; which is the National Stage
of International Application No. PCT/JP2006/320022 filed on Sep.
29, 2006; and this application claims priority to Application No.
2005-288219 flied in Japan on Sep. 30, 2005 under 35 U.S.C.
.sctn.119; the entire contents of all are hereby incorporated by
reference.
TECHNICAL FIELD
[0002] The present invention relates to a low air permeable rubber
laminate and a method for producing the same, more specifically
relates to a low air permeable rubber laminate having a superior
air barrier property and durability comprised of a layer of a
rubber composition on which a low air permeable resin layer having
an average thickness greater than 0.05 .mu.m and less than 5 .mu.m
is laminated, a method for producing the same and a product
obtained therefrom.
BACKGROUND ART
[0003] It has been known in the past to cover a layer of a rubber
composition with a layer (or film) of a thermoplastic (or
thermosetting) resin to obtain a laminate having functions derived
from that resin. As an example, various attempts have been made to
coat a rubber composition with a film having a low air permeability
and to use this as an inner liner layer of a pneumatic tire.
Recently, for example, Japanese Patent Publication (A) No.
2002-79804 proposes the use of an electron beam cross-linked
polyvinyl alcohol, ethylene-vinyl alcohol copolymer, etc. as a gas
barrier layer, which is then laminated on an elastomer auxiliary
layer. The resultant laminate is used as the inner liner layer of a
pneumatic tire. The thickness of this gas barrier layer is defined
as being 30 .mu.m or less, but the examples only describe the case
of a thickness of EVOH of 20 .mu.m. EVOH is an extremely hard resin
having a tensile modulus of elasticity of 2 to 3 GPa, and
therefore, in the case of a thickness of 20 .mu.m, if stretched,
necking deformation occurs and, due to stress concentration, easy
breakage occurs. For this reason, due to repeated dynamic strain,
cracks easily occur, peeling occurs from cracks, and other problems
arise. Further, Japanese Patent. Publication (A) No. 20.04-255937
describes a support, and a pneumatic run flat tire, using a single
layer of an electron beam cross-linked polyvinyl alcohol or
ethylene-vinyl alcohol copolymer having a thickness of 5 to 100
.mu.m, as a gas barrier layer.
DISCLOSURE OF THE INVENTION
[0004] Note that, as a method of coating a thin film of a low air
permeable rein (A) on a rubber composition layer, there is the
method of coating a solution or emulsion of the resin (A) on the
rubber composition layer. This method has no problems when coating
a relatively thick film of such as, for example, 10 .mu.m or more,
but it is difficult to control the uniformity of a thin film having
a thickness of, for example, thinner than 5 .mu.m, more
particularly 3 .mu.m or less. Further, there is the problem that
the number of steps such as coating a primer for imparting
bondability with the rubber composition layer, drying of the
solvent, etc. is, increased. Further, when, a rubber composition
requiring a vulcanization step is coated, in, order to give the
separability from the bladder rubber, it is necessary to coat the
laminate surface with a release agent, followed by vulcanizing the
same. At this time, the coating layer is liable to break.
Therefore, there is the problem that it is not possible to impart a
sufficient gas barrier property.
[0005] Accordingly, an object of the present invention is to
provide a low air permeable rubber laminate comprised of a layer of
a low air permeable resin (A) having a thickness of less than 5
.mu.m, uniformly laminated on a layer of a rubber composition,
capable of solving the above problems and a production method
thereof and the product thereof.
[0006] In accordance with the present invention, there is provided
a low air permeability rubber laminate (E) comprising a low air
permeable resin (A) layer having an air permeation coefficient of
1.0.times.10.sup.-12 cccm/cm.sup.2seccmHg or less and an average
thickness d (.mu.m) of 0.05<d<5, laminated to one surface, of
a rubber composition (D) layer.
[0007] In, accordance with the present invention, there is further
provided a method for producing a low air permeability rubber
laminate (E) comprising a rubber composition (E) layer laminated,
at one surface thereof, with a low air permeable resin (A) layer
comprising stacking and vulcanizing a laminate (D) of a low air
permeable resin (A) layer having an air permeation coefficient of
1.0.times.10.sup.-1 cccm/cm.sup.2seccmHg or less and an average
thickness d (.mu.m) of 0.05<d<5 and a thermoplastic resin
composition (B) layer in a quasi-bonded state with the (A) layer
and having a peeling strength from the (A) layer at room
temperature of 0.001 to 10N/mm with a rubber composition (E) layer
to so as to form a laminate of (B)/(A)/(E), followed by
vulcanization such that the peeling strength between the low
permeability resin (A) layer/the rubber composition (E) layer after
vulcanization is larger than the peeling strength between the (A)
layer/(B) layer, and
[0008] peeling off only the thermoplastic resin composition (B)
from the laminate.
[0009] The low air permeable resin (A) has a high Young's modulus,
and therefore, when the laminated on the rubber, which receives
repeated dynamic deformation, material breakage of the resin and
the resin/rubber interfacial peeling occur. Contrary to this,
according to the present invention, in a laminate comprised of a
thin film of a low air permeable resin having a thickness of less
than 5 .mu.m, laminated on a layer of a rubber composition, bending
cracks are difficult to occur, flexing fatigue resistance is
superior, and interfacial separation is difficult to occur. In
particular, when an ethylene-vinyl alcohol copolymer, which has the
lowest air permeability among all resins, is used, even, a thin
film having a thickness of less than 5 .mu.m has a gas barrier
property sufficient for use as the inner liner of a pneumatic tire
and the weight of the tire can be remarkably reduced.
BEST MODE FOR CARRYING OUT THE INVENTION
[0010] The singular form a ("a", "an", and "the") used in the
Description and attached Claims should be understood as including
the plural form except when otherwise clear from the context.
[0011] The inventors engaged in research to solve the above
problems and, as a result, found that, by laminating and
vulcanizing a two- or three-layer coextruded laminate (D) of a
thermoplastic resin composition (B)/low air permeability resin
(A)/optional adhesive (C) with a layer of a rubber composition (E),
then peeling off the thermoplastic resin composition (B) layer, it
is possible to uniformly coat a thin film of the low air permeable
resin (A) layer having a thickness of less than 5 .mu.m on the
layer of the rubber composition (E), found that this low air
permeable rubber laminate (F) has superior properties (e.g., gas
barrier, property and dynamic properties), whereby the present
invention has been completed.
[0012] If the thickness of the low permeable resin (A) layer having
an air permeation coefficient of 1.0.times.10.sup.-12
cccm/cm.sup.2seccmHg or less (determined according JIS K7126 (test
gas: air; (N.sub.2:O.sub.2=8:2), 30.degree. C.), the same
hereinbelow) is less than 5 .mu.m, preferably 1 to 3 .mu.m, it is
possible to remarkably improve the gas barrier property such as
oxygen, ozone, without sacrificing the dynamic properties (e.g.,
elongation at break, tensile and compressive set, etc.) of the
rubber. For this reason, since the oxidation degradation of the
rubber is remarkably decreased, the invention can be suitably
applied to the side rubber etc. of tires, in addition to the inner
liner. Further, a thin film of a low air permeable resin having a
thickness of less than 5 .mu.m has flexing fatigue resistance, and,
therefore, the low permeable rubber laminate (E) can be suitably
used, even as one layer of, for example, an inner layer,
intermediate layer and outer layer of a hose, where flexing fatigue
resistance and gas barrier property are essential.
[0013] That is, according, to the present invention, by laminating
and, after the lamination, vulcanizing, a laminate (D) of a low air
permeable resin (A) layer having an air permeation coefficient of
1.0.times.10.sup.-12 cccm/cm.sup.2seccmHg or less, preferably 0.001
to 0.1.times.10.sup.-12 cccm/cm.sup.2seccmHg and having an average
thickness d of 0.05<d<5 .mu.m, preferably 1 to 3 .mu.m and a
thermoplastic resin composition (B) layer in a quasi-bonded state
with the (A) layer (that is, a state where the two layers are
bonded in the state of ordinary use, but when separating the two
layers, they can be easily separated by just pulling by hand and
cannot be re-bonded by just placing them together under simple
pressing) and having a peeling strength at room temperature with
the (A) layer of 0.001 to 10N/mm, preferably 0.01 to 1N/mm
(determined according to JIS6256, the same hereinbelow), with a
layer of a rubber composition (E) so as to form a laminate of
(B)/(A)/(E), in this order; by selecting (A), (B) and (E) so that,
the peeling strength between the low air permeable resin (A)
layer/the rubber composition (E) layer after vulcanization becomes
larger than the peeling strength of the (A) layer/the (B) layer.
Thereafter, only the thermoplastic resin composition (B) layer is
peeled off from the (A) layer of the laminate, it is possible to
obtain a low air permeable rubber laminate (F) comprising the
rubber composition (E) layer on one surface of which the (A) layer
is coated (or laminated).
[0014] The laminate (D) of the low air permeable resin (A) layer
and the thermoplastic resin composition (B) layer can, for example,
be a multilayer co-extruded or multilayer inflated molded article
of (A) and (B). This procedure is generally used in this technical
field. The present invention can also utilize this general
procedure.
[0015] As the resin usable, as the low air permeable resin (A), in
the present invention, polyolefin ketone (POK), polyvinyl alcohol
(PVA), ethylene-vinyl alcohol (EVOH) and Nylon MXD6 (i.e.,
polycondensates of meta-xylene diamine and adipic acid) may be
mentioned. Among these, from the viewpoint of the balanced melt
moldability of the gas barrier property and the flexibility, an
ethylene-vinyl alcohol copolymer is preferable. Among the
ethylene-vinyl alcohol copolymers, those having an ethylene
composition ratio of 50 mol % or less is more preferable from the
viewpoint of the heat resistance (or melting point) and the gas
barrier property.
[0016] In the present invention, the resin composition usable, as
the thermoplastic resin composition (B), is preferably a
composition containing at least one resin of polyamide resins and
polyester resins. As the specific resin forming the thermoplastic
resin composition (B), at least one resin of, for example, Nylon 6,
Nylon 66, Nylon 6.66, Nylon 6.10, Nylon 6.12, Nylon 46, Nylon 11,
Nylon 12, polyethylene terephthalate (PET), polybutylene
terephthalate (PET), polyethylene naphthalate (PEN), etc. may be
mentioned. From the viewpoint of the release, property (i.e., small
peeling strength) from the (A) layer, the use of Nylon 11 and Nylon
12 is particularly preferred.
[0017] The rubber component forming the rubber composition (E),
usable in the present invention is not particularly limited. Any
rubber material generally used as rubber for a tire in the past can
be used. As such a rubber, for example, diene-based rubber such as
natural rubber (NR), polyisoprene rubber (IR) polybutadiene rubber
(BR), styrene-butadiene copolymer rubber (SBR), halogenated butyl
rubber, ethylene-propylene, copolymer rubber, etc., to which
compounding agents such as carbon black, a process oil,
vulcanization agent is added.
[0018] As the adhesive (C) optionally usable in the present
invention, modified styrene copolymers may be mentioned.
Specifically, any adhesive used for a Nylon-based thermoplastic
elastomer in the past comprising, a styrene-ethylene-propylene
copolymer, styrene-ethylene-butadiene-styrene copolymer,
styrene-ethylene-butadiene copolymer, or styrene-butadiene-styrene
copolymer having a functional group such as an epoxy group,
hydroxyl group, amino group, carboxyl group, acid anhydride group,
and a vulcanization accelerator, vulcanization agent and tackifier
(see Japanese Patent Application Nos. 2003-208227 and 2004-025782)
may be mentioned. The application methods and the amounts applied
may also be made as in the past.
[0019] The low air permeable rubber laminate (F) according to the
present invention can be used for the inner liner of a pneumatic
tire, the side parts of a pneumatic tire, a low permeability hose,
etc. The production methods thereof are not particularly limited.
The conventional general methods may be used.
[0020] The resin composition and rubber composition of the present
invention may further include, in addition to the above components,
any additives conventionally used for these compositions, for
example, carbon black or silica or another filler, a vulcanization
or cross-linking agent, a vulcanization or cross-linking
accelerator, various types of oils, an antioxidant, a plasticizer,
or other additive. These additives may be mixed by a general method
to obtain a composition for vulcanization or cross-linking. The
amounts of these vulcanization agents may be made the conventional
general amounts so long as the object of the present invention is
not adversely affected.
EXAMPLES
[0021] Examples will now be used to further explain the present
invention, but the scope of the present invention is by no means
limited to these Examples.
Examples 1 to 3 and Comparative Examples 1 to 3
Preparation of Laminate (D)
[0022] A three-layer dies-equipped inflation molding machine was
used to prepare cylindrical laminates (D) of a thermoplastic resin
composition (B)/low air permeable resin (A)/adhesive (C) as shown
in Table I, Table II, Table III and Table IV. As Comparative
Example 3, a laminate (D) composed of two layers of a thermoplastic
resin composition (B)/low air permeable resin (A) was prepared.
Further, as Comparative Example 4, a laminate (D) composed of two
layers of Nylon 11 (BESNO TL)/adhesive was prepared.
[0023] <Evaluation as Tire Inner Liner>
[0024] The prepared laminates (D) were used, instead of inner
liners, to fabricate tires (size: 165SR13 (rim 13.times.4 1/2-J))
by a general method. After preparing the tires, the (B) layers were
peeled off, whereby the tires having inner liner layers were
obtained, where the innermost surfaces of the tires were coated
with an ethylene-vinyl alcohol copolymer. These tires were
subjected to indoor tire tests and evaluated for air leakage.
[0025] Evaluation and Test Methods
[0026] Measurement of Peeling Strength
[0027] The peeling strength between (A)/(B) was measured according
to JIS6256 after laminating and vulcanizing the (B)/(A)/adhesive
(C)/rubber composition (E) in this order, sufficiently
strengthening the bonding strength between (A)/rubber composition,
and establishing a state enabling (A)/(B) to be peeled apart.
[0028] In the measurement of the peeling strength between
(A)/rubber composition (E), when the peeling strength between
(A)/(B) is weaker than that between (A)/rubber composition (E),
(A)/(B) is peeled apart, and, therefore, the measurement is not
possible in some cases. Accordingly, the peeling strength of
(A)/rubber composition (E) was found by preparing a two layer
inflation laminate of (A)/adhesive (C), then laminating and
vulcanizing (A)/binder (C)/rubber composition (E) in this order and
peeling apart (A)/rubber composition (E).
[0029] Indoor Tire Evaluation
[0030] The prepared 165SR13 steel radial tires (rim 13.times.4
1/2-J) were mounted on a 1500 cc class passenger car with an air
pressure of 2106 kPa, given a load equivalent to that when carrying
four passengers (65 kg/passenger), and run on an actual road for
20,000 km. After driving, the tires were removed from the rims and
the (A) layers at the insides of the tires were visually examined.
Tires with cracks in the (A) layer; and tires with peeling
blistering of the (A) layer were judged as failing, while those
without peeling blistering were judged as passing.
[0031] Judgment Method
[0032] Good: Case where the (A) layer does not exhibit any cracks
and peeling
[0033] Poor: Case where (A) layer exhibits cracks and peeling
[0034] Air Leakage
[0035] 165SR13 steel radial tires (rim 13.times.4 1/2-J) were
allowed to stand under conditions of an initial pressure of 200 kPa
and no-load at room temperature of 21.degree. C. for three months.
The pressure was measured each measurement interval of four days.
This was regressed to a function of the measurement pressure
P.sub.t, initial pressure P.sub.0 and days elapsed t
P.sub.t/P.sub.0=exp(-.alpha.t)
to find the .alpha. value. The .alpha. thus obtained was used and
t=30 was entered into the following equation:
.beta.=[1-exp(-.alpha.t)].times.100
to obtain the .beta. value. This .beta. value was used as the rate
of drop in pressure per month (air leakage rate) (,%/month).
[0036] Air Leakage Judgment Criteria
[0037] Good: air leakge<2.5%/month
[0038] Fair: 2.5%/month<air leakage<4.0%/month
[0039] Poor: air leakage>4.0%/month
TABLE-US-00001 TABLE I Low Air Permeable Resin (A) Air permeation
Product Manu- coefficient (.times.10.sup.-12 cc cm/ Material name
facturer cm.sup.2 s cmHg ) EVOH (ethylene- Eval Kuraray 0.01 vinyl
alcohol L171B copolymer) EVOH (modified Eval Kuraray 0.02
ethylene-vinyl SP521B alcohol copolymer) Rilsan Arkema 10 PA11
(Nylon 11), BESNO TL
TABLE-US-00002 TABLE II Thermoplastic Resin Material Product name
Manufacturer PA6.66 (6.66 copolymer nylon) UBE 5033B Ube Industry
PA11 (11 Nylon) Rilsan BESTNOTL Atofina PA12 (12 Nylon) UBESTA
3030XA Ube Industry Mah-EB (anhydrous maleic acid MA8510 Mitsui
modified ethylene-butene CHemical copolymer)
TABLE-US-00003 TABLE III Thermoplastic Resin Composition (B)
Thermoplastic Thermoplastic resin composition (B) (wt %) resin
maerial*.sup.1 B1 B2 B3 5033B (PA6.66) 40 -- -- BESNOTL (PA11) 50
45 -- 3030XA (PA12) -- -- 45 MA8510 (Mah-EB) 10 55 55 *.sup.1See
Table II
TABLE-US-00004 TABLE IV Binder (C) Material Binder composition
(parts by weight) ESBS*.sup.1 100 Tackifier*.sup.2 30 Stearic
acid*.sup.3 1 Peroxide''*.sup.4 2 Zinc White*.sup.5 0.5 Total [phr]
133 *.sup.1Epoblend AT501 (Daicel Chemical Industrial) *.sup.2YS
Resin D105: (Yasuhara Chemical) *.sup.3Beads Stearate (NOF
Corporation) *.sup.4Parkadox 14/40C (Kayaku Akzo) *.sup.5Zinc White
No. 3 (Seido Chemical Industry)
TABLE-US-00005 TABLE V Inner Liner Evaluation Comp. Comp. Comp.
Comp. Ex. 1 Ex. 1 Ex. 2 Ex. 3 Ex. 2 Ex. 3 Ex. 4 Thermoplastic B1 B2
B3 B3 B2 B2 -- resin composition (B) (B) layer gauge 100 100 100
100 100 100 0 (.mu.m) Low air L171B L171B SP521B L171B L171B L171B
BESNOTL permeable resin (A) (A) layer gauge 1 0.5 1 3 12 12 30
(.mu.m) Binder Yes Yes Yes Yes Yes No Yes (B)/(A) peeling 100 (B)
0.05 0.04 0.03 0.05 0.05 -- strength (N/mm) material breakage
(A)/rubber 10 10 10 10 10 0.01 10 peeling strength (N/mm) Indoor
tire (B) No No No (A) -- (A) evaluation layer cracks cracks cracks
layer layer cracks crack crack and peeling Durability Poor Good
Good Good Good -- Poor judgment Air leakage Good Good Good Good
Good -- Poor evaluation
[0040] In Comparative Example 1, (B)/(A) was not able to be peeled
apart, and, therefore, the indoor tire test was conducted, while
leaving the layer laminated.
[0041] In Comparative Example 3, a laminate (D) composed of two
layers of thermoplastic resin composition (B)/low air permeable
resin composition (A) was used. The (A)/rubber peeling strength was
less than the (B)/(A) peeling strength, and, therefore, the (A)
layer was not coated on the rubber layer.
Examples 4 to 6 and Comparative Examples 5 to 7
Evaluation as Tire Side Part
[0042] As shown in Table VI, each laminate (D) layer was laminated
on a side rubber compound, then used to prepare a tire by a
conventional general method. After tire vulcanization, the (B)
layer was peeled off, whereupon a tire having an EVOH thin film
coated on the tire sides was obtained. The results are shown in
Table VI.
[0043] Evaluation Method
[0044] Peeling strength: Same as the case of the inner liner
mentioned above
[0045] Oxygen degradation evaluation: The prepared 0.165SR13 steel
radial tires (rim 13.times.4 1/2-J) were mounted on a 1500 cc class
passenger car with an air pressure of 120 kPa, given a load
equivalent to that when carrying four passengers (65 kg/passenger),
and run on for 5,000 km while exposing the two sides of the tires
to ozone. After driving, the formation of ozone cracks at the side
parts was visually checked.
[0046] Judgment Method
[0047] Good: Case where there are no ozone cracks from the side
part
[0048] Poor: Case where ozone cracks are seen from the side
part
TABLE-US-00006 TABLE VI Comp. Comp. Comp. Ex. 5 Ex. 4 Ex. 5 Ex. 6
Ex. 6 Ex. 7*.sup.1 Thermoplastic resin B1 B2 B3 B3 B2 composition.
(B) (B) layer gauge (.mu.m) 100 100 100 100 100 Low air permeable
L171B L171B SP521B L171B L171B resin(A) (A) layer gauge (.mu.m) 1
0.5 1 3 12 Adhesive Yes Yes Yes Yes Yes (B)/(A) peeling 100 (B)
0.05 0.04 0.02 0.05 -- strength (N/mm) material breakage (A)/rubber
peeling 12 12 10 12 12 -- strength (N/mm) Driving after oxygen (B)
layer No No No (A) layer Side rubber degradation cracks cracks
cracks cracks crack ozone cracks Durability judgment Poor Good Good
Good Poor Poor *.sup.1Comparative Example 7 was tested by an
ordinary tire not using a laminate (C).
INDUSTRIAL APPLICABILITY
[0049] As explained above, according to the present invention, by
making the thickness of the thin film of the low air permeable
resin (A) having a thickness of leas than 5 .mu.m, the laminate
comprising the thin film of the low air permeable resin (A)
laminated on a rubber composition (E) is given resistance to flex
cracking, superior flexing fatigue resistance and resistance to
interfacial peeling. In particular, if using an ethylene-vinyl
alcohol copolymer, which has the lowest air permeable among resins,
even a thin film having a thickness of less than 5 .mu.m, further 3
.mu.m or less, can be given a gas barrier property sufficient for
use, as an inner liner of a pneumatic tire, and therefore, the
weight of the tire can be remarkably decreased. Further, if a thin
film having a thickness of less than 5 .mu.m, it is possible to
remarkably improve the oxygen, ozone, and other gas barrier
property, without adversely affecting the dynamic properties of the
rubber (e.g., elongation at break, tensile and compressive set,
etc.). Since the oxidation degradation of the rubber is remarkably
decreased, this can be suitably used as side rubber etc. of a tire.
Further, this can be suitably used even for a hose, where flexing
fatigue resistance and gas barrier property are essential.
* * * * *