U.S. patent application number 17/501780 was filed with the patent office on 2022-02-03 for methods for manufacturing a tread for agricultural tire using a dinitrile oxide cure system.
The applicant listed for this patent is BRIDGESTONE AMERICAS TIRE OPERATIONS, LLC. Invention is credited to Joshua ABELL, Robert BARNED, David BENDER.
Application Number | 20220032566 17/501780 |
Document ID | / |
Family ID | |
Filed Date | 2022-02-03 |
United States Patent
Application |
20220032566 |
Kind Code |
A1 |
BARNED; Robert ; et
al. |
February 3, 2022 |
METHODS FOR MANUFACTURING A TREAD FOR AGRICULTURAL TIRE USING A
DINITRILE OXIDE CURE SYSTEM
Abstract
A method of manufacturing a tread for agricultural tires, the
method comprising providing an agricultural tire casing, providing
a cured rubber component having first and second planar surfaces,
providing a plurality of cushion gums, wherein the plurality of
cushion gums contains a cure system comprising a stable dinitrile
oxide compound, providing a plurality of lugs, and forming an
agricultural tread composite by mating the lugs to a planar surface
of the cured rubber component using the cushion gum.
Inventors: |
BARNED; Robert; (Akron,
OH) ; ABELL; Joshua; (Franklin, TN) ; BENDER;
David; (Muscatine, IA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BRIDGESTONE AMERICAS TIRE OPERATIONS, LLC |
Nashville |
TN |
US |
|
|
Appl. No.: |
17/501780 |
Filed: |
October 14, 2021 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
15753810 |
Feb 20, 2018 |
11148381 |
|
|
PCT/US16/48017 |
Aug 22, 2016 |
|
|
|
17501780 |
|
|
|
|
62207505 |
Aug 20, 2015 |
|
|
|
International
Class: |
B29D 30/56 20060101
B29D030/56; B60C 11/02 20060101 B60C011/02; B60C 11/00 20060101
B60C011/00; B60C 1/00 20060101 B60C001/00; B29D 30/54 20060101
B29D030/54; C08K 5/00 20060101 C08K005/00; C08L 7/00 20060101
C08L007/00; C08L 9/00 20060101 C08L009/00; B29D 30/06 20060101
B29D030/06; C08K 5/32 20060101 C08K005/32 |
Claims
1. A method of retreading a used agricultural tire, the method
comprising: (i) providing a used agricultural tire casing from the
used agricultural tire; (ii) providing a cured rubber component
having first and second planar surfaces; (iii) providing a
plurality of lug cushion gums, wherein each lug cushion gum of the
plurality of lug cushion gums contains a cure system comprising a
stable dinitrile oxide compound; (iv) providing a plurality of
lugs; and (v) mating the plurality of lug cushion gums to the
plurality of lugs to form a plurality of mated lugs, (vi) mating
the plurality of mated lugs to the cured rubber component to form a
mated cured rubber component, and (vii) mating the mated cured
rubber component to the used agricultural tire casing to form a
pre-cured retread agricultural tire.
2. The method of claim 1, further comprising the step of treating
the pre-cured retread agricultural tire to form a retread
agricultural tire.
3. The method of claim 1, wherein the lugs contain at least about
50 wt. % synthetic polyisoprene or natural rubber.
4. The method of claim 1, wherein the first planar surface of the
cured rubber component includes a plurality of recesses and said
step of mating the plurality of mated lugs includes aligning the
plurality of mated lugs with the plurality of recesses.
5. The method of claim 4, wherein said step of mating includes
placing the plurality of mated lugs on the first planar surface of
the cured rubber component.
6. The method of claim 1, wherein the cured rubber component
contains at least about 50 wt. % synthetic polyisoprene or natural
rubber.
7. The method of claim 1, wherein the at least one stable dinitrile
oxide compound is a stable aryl dinitrile oxide.
8. The method of claim 7, wherein the stable aryl dinitrile oxide
is selected from the group consisting of mesitylene dinitrile oxide
(MDNO) and bismesitylene dinitrile oxide (BMNO).
9. The method of claim 1, wherein the step of providing a plurality
of lug cushion gums further comprises extruding a lug cushion gum
composition to form each lug cushion gum of the plurality of lug
cushion gums.
10. The method of claim 1, wherein the plurality of lug cushion
gums each contain at least about 50 wt. % synthetic polyisoprene or
natural rubber.
11. The method of claim 2, where said step of treating includes
encasing the pre-cured retread agricultural tire in an envelope;
placing the enveloped pre-cured retread agricultural tire in a
pressure chamber at a temperature between about 10.degree. C. and
about 60.degree. C.; and applying pressure to the enveloped
pre-cured retread agricultural tire to form the retread
agricultural tire.
12. The method of claim 1, further comprising: (i) providing a
casing cushion gum for mating the cured rubber component to the
tire casing, wherein the casing cushion gum contains a cure system
comprising a stable dinitrile oxide compound; (ii) applying the
casing cushion gum to the agricultural tire casing; and (iii)
applying the second planar surface of the cured rubber component to
the second cushion gum.
13. The method of claim 12, wherein said step of mating the mated
lugs to the cured rubber component and said step of mating the
mated cured rubber component takes place at a location, and wherein
said steps of providing the plurality of lug cushion gums and
providing the casing cushion gum take place at the same
location.
14. The method of claim 1, wherein said step of providing an
agricultural tire casing comprises preparing an agricultural tire
casing to have a buffed surface by buffing off a tread portion and
lugs of an agricultural tire.
15. The method of claim 1, wherein said step of providing the used
agricultural tire casing comprises preparing the used agricultural
tire casing to have a buffed surface by buffing off a tread
portion, lugs, and a subtread of the used agricultural tire.
16. A method of manufacturing an agricultural tire, the method
comprising: (i) providing a newly manufactured agricultural tire
casing; (ii) providing a plurality of lug cushion gums, wherein
said plurality of lug cushion gums each contain a cure system
comprising a stable dinitrile oxide compound; (iii) providing a
plurality of lugs; (iv) mating the plurality of lug cushion gums to
the plurality of lugs to form a plurality of mated lugs; and (v)
mating the plurality of mated lugs to newly manufactured
agricultural tire casing to form a pre-cured retread agricultural
tire.
17. The method of claim 16, wherein the lugs contain at least about
50 wt. % synthetic polyisoprene or natural rubber, wherein the
newly manufactured agricultural tire casing contains at least about
50 wt. % synthetic polyisoprene or natural rubber, and wherein the
plurality of lug cushion gums each contain at least about 50 wt. %
synthetic polyisoprene or natural rubber.
18. The method of claim 16, wherein the at least one stable
dinitrile oxide compound is a stable aryl dinitrile oxide, and
wherein the stable aryl dinitrile oxide is selected from the group
consisting of mesitylene dinitrile oxide (MDNO) and bismesitylene
dinitrile oxide (BMNO).
19. The method of claim 16, wherein the step of providing a
plurality of lug cushion gums further comprises extruding a lug
cushion gum composition to form each lug cushion gum of the
plurality of lug cushion gums.
20. The method of claim 16, further comprising a step of treating
the pre-cured retread agricultural tire, where said step of
treating includes encasing the pre-cured retread agricultural tire
in an envelope; placing the enveloped pre-cured retread
agricultural tire in a pressure chamber at a temperature between
about 10.degree. C. and about 60.degree. C.; and applying pressure
to the enveloped pre-cured retread agricultural tire to form a
retread agricultural tire.
Description
FIELD OF THE INVENTION
[0001] Embodiments of the invention relate to methods for the
manufacture of treads for agricultural tires. According to one or
more embodiments, the method includes applying lugs to a tire tread
substrate by using a cushion gum that includes a stable dinitrile
oxide compound.
BACKGROUND OF THE INVENTION
[0002] Agricultural tires are tires used to travel on soft soil,
such as fields, and not hard roads. Further, agricultural tires
have a lug pattern tread shape and are inflated at a lower pressure
than passenger car tires in order to generate traction and move
forward by penetrating soft soil.
[0003] Traditionally, agricultural tires are created in a similar
way to normal passenger car tires. Simply stated, the process of
making a tire begins with a tire carcass, then a cured rubber
component, also known as a tread component, is attached to the tire
carcass by various known methods, and then the tire carcass and the
tread component are cured, and a tire is formed.
[0004] Methods of retreading tires are used to extend the life of
tires. By applying a new tread to a used tire casing, the life of
the tire casing is extended. Retreaded tires often have to meet the
same stringent quality standards as new tires and they additionally
offer an economical and environmentally friendly alternative to new
tires. Agricultural tires are able to go through a retreading
process when available because it provides an economical way to
gain additional use out of an agricultural tire casing after the
original tread has become worn.
[0005] Agricultural tires nonetheless differ from normal passenger
car tires in various ways. The most pronounced difference is the
fact that agricultural tires contain large tread components that
are often referred to as ribs, lugs, bars, or tread blocks. These
large tread components extend radially outward from the tire
carcass much farther than a typical tread pattern on a normal
passenger tire.
[0006] In some known processes, these lugs are integral with the
cured rubber component, and applying the cured rubber component and
the lugs to the tire casing can take place in one simple step. In
other known processes, the lugs are formed separately from the
cured rubber component. In these processes, the cured rubber
component is applied to the tire casing in one step, and the lugs
are then applied to the cured rubber component in a subsequent
step.
[0007] In one such process, lugs are secured to a cured rubber
component using a layer often referred to as a cushion gum or
cushion gum layer. This cushion gum is an uncured rubber-containing
composition that, upon curing, mates the lug to cured rubber
component.
[0008] In some processes, the cushion gum is applied to the back,
i.e., the inside surface, of the lug. The cushion gum and lug can
then be applied in combination about the circumference of the cured
rubber component, which is then applied to the circumference of the
tire casing, to create an uncured retreaded tire composite that is
ready for curing. Typically, the uncured retreaded tire composite
is then placed within a flexible rubber envelope and an airtight
seal is created between the envelope and the beads of the tire to
create an enveloped tire assembly. The enveloped tire assembly is
then placed within a curing chamber and is subjected to pressure
and heat in order to effect curing of the cushion gum.
[0009] Logistically, the lugs may be manufactured at a lug-making
facility and shipped to a different facility where the new
agricultural tires are made. The cushion gum may likewise be
generally made at a facility distinct from the facility where the
agricultural tires are made; e.g. it is prepared at the lug-making
facility and shipped to the retreading facility.
[0010] In many processes, the cushion gum comprises a rubber
component, a sulfur based cure system, reinforcing fillers, and
other optional components. The uncured retread tire is then
subjected to both heat and pressure in order to cure the cushion
gum to the lug and the cured rubber component. Although limited,
the shelf life of the cushion gum is relatively long because the
sulfur-based cure systems require relatively high heat to be
activated. Typically, the shelf life of the cushion gum is much
shorter than the shelf life of the lug to which the cushion gum
will eventually be secured. Furthermore, the cost of manufacturing
an agricultural tire is affected by having to produce the cushion
gum at a facility distinct from the facility where the agricultural
tires are made. The cost of making an agricultural tire is also
affected by having to apply both heat and pressure to cure the
cushion gum to the lug and the cured rubber component.
[0011] A desire therefore exists to improve upon the methods for
manufacturing a agricultural tire, especially in regards to the
preparation of the cushion gum and the treatment of the uncured
retread tire composite.
SUMMARY OF THE INVENTION
[0012] One or more embodiments of the present invention provides a
method of retreading a used agricultural tire, the method
comprising providing a cured rubber component having first and
second planar surfaces, providing a plurality of cushion gums,
where the cushion gum contains a cure system comprising a stable
dinitrile oxide compound, providing a plurality of lugs, and
forming an agricultural tire composite by mating the lugs to a
planar surface of the cured rubber component using the cushion
gums.
[0013] One or more embodiments of the present invention provides a
method of manufacturing an agricultural tire, the method comprising
providing a newly manufactured agricultural tire casing, providing
a plurality of cushion gums, wherein each cushion gum of the
plurality of cushion gums contains a cure system comprising a
stable dinitrile oxide compound, providing a plurality of lugs; and
forming an agricultural tire composite by mating the lugs to a
planar surface of the cured rubber component using the cushion
gums.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a flow chart showing the method of applying a
plurality of lugs to an agricultural tire according to one or more
embodiments of the invention.
[0015] FIG. 2 is a cross-sectional view of an agricultural
tire.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0016] Embodiments of the present invention are based, at least in
part, upon the discovery of a process of manufacturing an
agricultural tire. In one or more embodiments, the process includes
mating lugs to a substrate by using a cushion gum having a cure
system that includes a stable dinitrile oxide compound. Because of
the nature of the curing system, specifically the presence of the
stable dinitrile oxide compound, the lugs can be advantageously
mated to a cured rubber component (e.g., tread substrate) at
ambient temperatures. Moreover, the process allows for the
efficient mating of a plurality of lugs to a cured rubber component
to form a useable agricultural tire.
[0017] In general, procedures for applying lugs to a tire tread
substrate are known in the art as generally disclosed in U.S. Publ.
No. 2014/0008005 and copending applications gaining priority from
U.S. Ser. No. 61/846,591, which are incorporated herein by
reference.
Application of Lugs
[0018] In one or more embodiments, the methods of the invention are
employed for manufacturing a new agricultural tire. An exemplary
process of the present invention may include a first step of
providing a newly manufactured agricultural tire base, which is a
tire that contains no lugs. This tire base, which is fully cured,
may include a carcass layer as the outer layer, or may include
additional outer circumferential layers such as an undertread layer
or subtread layer. Practice of one or more embodiments of the
invention is not necessarily limited by the cured layer to which
the lugs are secured since design specs may change for any given
agricultural tire. Accordingly, reference may be simply made to
tread substrate to refer to the outer circumferential layer of the
cured tire base to which the lugs are secured or mated. A second
step includes providing a plurality of cushion gums including a
stable dinitrile oxide compound. The third step includes providing
a plurality of lugs, which are fully cured. The fourth step then
includes securing or mating the lugs to the tread substrate by
using the cushion gum as an adhesive layer. Finally, the cushion
gums are allowed to cure to thereby form a new agricultural tire.
As the skilled person will appreciate, the cushion gum may be first
applied to the lugs to form a lug composite, and then the composite
is mated to the tread substrate. Alternatively, the cushion gum is
first mated to the tire substrate, and then the lug is applied or
mated to the cushion gum.
[0019] In one or more embodiments, the tire substrate to which the
lugs are applied includes a rubber component. The rubber component
of the cushion gum composition may include natural and synthetic
rubbers, which may also be referred to as elastomers. For example,
the synthetic elastomers may include diene-based rubbers such as
butadiene rubber, styrene-butadiene copolymer rubber, isoprene
rubber, butyl rubber, halogenated butyl rubber,
acrylonitrile-butadiene rubber, chloroprene rubber,
styrene-isoprene-butadiene copolymer rubber, and isoprene-butadiene
copolymer rubber. Other useful rubbers include
ethylene-propylene-diene copolymer rubber, styrene-isoprene
copolymer rubber, ethylene-propylene copolymer rubber, acrylic
rubber, epichlorohydrin rubber, polysulfide rubber, silicone
rubber, fluororubber, urethane rubber, and combinations thereof.
These rubber components may be selected as appropriate in order to
obtain high adhesiveness, depending on the content of the rubber
component which makes up the newly manufactured carcass for an
agricultural tire.
[0020] In one or more embodiments, the rubber component of the
tread substrate is a diene-based rubber. In these or other
embodiments, the rubber component of the tread substrate includes
synthetic polyisoprene or natural rubber. In these or other
embodiments, the tread substrate contains at least about 50 wt. %;
in other embodiments at least about 70 wt. %; and in yet other
embodiments at least about 80 wt. % synthetic polyisoprene or
natural rubber.
[0021] The plurality of cushion gums comprises a cushion gum
composition containing a rubber component, a cure system,
reinforcing fillers, and other optional ingredients. The step of
providing a plurality of cushion gums further includes the step of
manufacturing a plurality of cushion gums. The manufacturing
process may include fabricating cushion gum using a cushion gum
composition. The cushion gum composition comprises a rubber
component, a cure system, reinforcing fillers, and other optional
ingredients.
[0022] In one or more embodiments, the rubber component of the
cushion gum composition may include natural and synthetic rubbers,
which may also be referred to as elastomers. For example, the
synthetic elastomers may include diene-based rubbers such as
butadiene rubber, styrene-butadiene copolymer rubber, isoprene
rubber, butyl rubber, halogenated butyl rubber,
acrylonitrile-butadiene rubber, chloroprene rubber,
styrene-isoprene-butadiene copolymer rubber, and isoprene-butadiene
copolymer rubber. Other useful rubbers include
ethylene-propylene-diene copolymer rubber, styrene-isoprene
copolymer rubber, ethylene-propylene copolymer rubber, acrylic
rubber, epichlorohydrin rubber, polysulfide rubber, silicone
rubber, fluororubber, urethane rubber, and combinations thereof.
These rubber components may be selected as appropriate in order to
obtain high adhesiveness, depending on the content of the rubber
component which makes up the newly manufactured carcass for an
agricultural tire.
[0023] In one or more embodiments, the rubber component of the
cushion gum composition is a diene-based rubber. In these or other
embodiments, the rubber component of the cushion gum composition
includes synthetic polyisoprene or natural rubber. In these or
other embodiments, the cushion gum composition contains at least
about 50 wt. %; in other embodiments at least about 70 wt. %; and
in yet other embodiments at least about 80 wt. % synthetic
polyisoprene or natural rubber.
[0024] In one or more embodiments, the lugs provided contain a
rubber component, and in some embodiments, the rubber component is
a diene-based rubber. In these or other embodiments, the rubber
component of the lugs includes synthetic polyisoprene or natural
rubber. In these or other embodiments, the lugs contain at least
about 50 wt. %; in other embodiments at least about 70 wt. %; and
in yet other embodiments at least about 80 wt. % synthetic
polyisoprene or natural rubber.
[0025] In one or more embodiments, the lugs are ultimately mated to
the tread substrate by curing the cushion gum while force is
applied to the lug thereby pressing the lug to the tread substrate.
This may be accomplished by using a rubberized curing envelope
designed for the particular agricultural tire type and size being
manufactured. The envelope may be sealed to the beads of the base
tire, and then the rubberized curing envelope is subjected to
pressure (or vacuum). In one or more embodiments, the pressure
applied is about 70 PSI to about 100 PSI relative to atmospheric,
in other embodiments from about 80 PSI to about 95 PSI relative to
atmospheric, and in yet other embodiments from about 85 PSI to
about 90 PSI relative to atmospheric.
[0026] In other embodiments, the process of the invention includes
a process for retreading an agricultural tire. An exemplary process
of the present invention can be described with reference to FIG. 1,
which shows a process 10 including step 12 of providing an
agricultural tire casing in need of being retreaded; step 14 of
providing a cured rubber component having a first and second planar
surface, step 16 of providing a plurality of cushion gums, wherein
the cushion gum contains a cure system comprising a stable
dinitrile oxide compound; step 18 of providing a plurality of lugs;
step 20 of applying the cured rubber component to the agricultural
tire carcass to form an agricultural tire composite; step 22 of
applying a plurality of cushion gums to the cured rubber component;
step 24 of mating the plurality of lugs to the plurality of cushion
gums located on the cured rubber component; and step 26 of allowing
the cushion gum to cure and thereby form an agricultural tire.
[0027] In one or more embodiments, step 12 of providing an
agricultural tire casing includes collecting a used agricultural
tire, such as the one shown in FIG. 2, wherein the used
agricultural tire requires retreading. Step 12 of providing an
agricultural tire casing may then include buffing the existing
tread and lugs from the casing.
[0028] An exemplary agricultural tire 11 includes a carcass 101
extending between a pair of axially-spaced beads 102, 102'.
Abrasion strips 103, 103' partially encase carcass 101 at or near
beads 102, 102'. Agricultural tire 11 further includes opposing
sidewalls 104, 104', and tread portion 105 having lugs 105', which
forms the outermost circumferential surface of agricultural tire
11. Subtread 106 is disposed below tread 105, undertread 107 is
disposed below subtread 106, and belt package 108 is disposed below
undertread 107. Belt package 108, which may include a plurality of
belts (not shown), is positioned above carcass 101, which itself
may include one or more body plies (not shown). Inner liner 109 is
disposed on the interior of carcass 101 relative to the tread
portion 105. As the skilled person will appreciate, agricultural
tire 11 may also include various other components, which are not
shown, such as, but not limited to, tread shoulders, cap plies,
belt wedges, and belt shoulders.
[0029] Most often the buffed surface left behind includes portions
of the undertread 107, and other times the buffed surface left
behind even includes portions of the subtread 106. When the tread
portion 105 is removed from the agricultural tire 11, the remaining
substrate may be referred to as a tire casing.
[0030] In one or more retread situations, step 12 of providing an
agricultural tire casing further includes an inspection of the tire
casing. This may include manual inspection such as a visual
inspection and a tactile inspection. In one or more embodiments,
inspection can be performed using the assistance of equipment that
can perform non-destructive testing. This equipment may include,
for example, X-ray.
[0031] In one or more retread situations, the tread portion 105 and
the lugs 105' are removed from the agricultural tire 11 using a
buffing machine, such as those machines manufactured by Bridgestone
Commercial Solutions. During the buffing operation, the tread
portion 105 and the lugs 105' are ground away from agricultural
tire, thereby leaving a tire carcass with a buffed surface. In one
or more embodiments, only the tread portion 105 and the lugs 105'
are ground away from the agricultural tire 11, leaving both the
subtread 106 and the undertread 107 attached to the tire casing. In
other embodiments, the tread portion 105, the lugs 105', and the
subtread 106 are ground away from the agricultural tire 11, leaving
only the undertread 107 attached to the agricultural tire 11. The
buffed surface extends circumferentially about the tire casing and
also extends transversely across the outside of the outer radial
wall until it terminates at the buffed shoulder areas.
[0032] In one or more retread situations, step 12 of providing a
tire casing may then include treating (e.g. spraying) the tire
casing with a cement in order to assist in the subsequent
application of the cured rubber component. Various cements may be
employed and this invention is not limited to any particular cement
treatment.
[0033] In one or more retread situations, following the removal of
the used tread layer, the tire casing may undergo repair. For
example, the tire casing may undergo skiving and filling. Skiving
is the removal of damaged material from a tire casing prior to
making a repair. Often, a tire accumulates cuts, holes, nicks, or
tears due to stones or other sharp objects that the tire comes in
contact with during use. The injured or damaged area may be first
ground smooth by an appropriate grinding tool and then filled with
repair gum. It may be necessary to fill the injured areas to the
level of the buffed surface to avoid air pockets between the buffed
surface and the later applied cured rubber component because
trapped air can have negative effects on the longevity of a typical
retreaded tire.
[0034] In addition to skiving, which primarily addresses minor
damage including non-penetrating injuries, the repair process may
also include section repair wherein cables or other reinforcing
elements of the tire carcass are repaired. Also, repair may be made
to penetrating injuries. Such repair may occur by using various
plugs and patches to repair punctures in the tire casing.
[0035] In one or more retread situations, the tire casing is
allowed to equilibrate at ambient indoor temperature and humidity
for a period of time, or in other embodiments from about 10 to 15
hours. In one or more embodiments, visible surface moisture on the
tire casing is removed, and holes or other damage to the tire
casing are repaired.
[0036] In one or more retread situations, step 14 includes
providing a cured rubber component, wherein the cured rubber
component has first and second planar surfaces. The cured rubber
component contains a first planar surface and a second planar
surface. In one or more embodiments, the first planar surface is a
smooth surface. In these or other embodiments, the second planar
surface may be a smooth surface. In one or more embodiments,
practice of the present invention is not necessarily limited by the
selection of the cured rubber component, which may also be referred
to as a pre-cured profiled tread strip or a tread substrate.
Accordingly, the step of providing a cured rubber component may
rely on known techniques of the prior art. In one or more
embodiments, the first planar surface of the cured rubber component
may advantageously include a plurality of recesses having varying
depths and/or designs. In one or more embodiments, the recesses may
have a shape corresponding to the shape of the lugs that will be
placed into the recesses. In one or more embodiments, the cured
rubber component may be formed by methods known to those skilled in
the art including, but not limited to, curing with a flat molding
press. Cured rubber components useful in practice of the present
invention include those described in U.S. Pat. Nos. 3,951,720,
4,075,047, 4,046,947, and 8,298,463, as well as EP 0989171, which
are incorporated herein by reference.
[0037] As generally known in the art, the cured rubber component
may have a first planar surface opposite a second planar surface.
The first planar surface may be integral with the second planar
surface to the extent that they both derive from the same
extrudate, or in other embodiments the second planar surface may
derive from one or more additional rubber layers mated to the first
planar surface. In one or more embodiments, the first planar
surface may include a plurality of recesses.
[0038] In one or more retread situations, the cured rubber
component may include natural and synthetic rubbers, which may also
be referred to as elastomers. For example, the synthetic elastomers
may include diene-based rubbers such as butadiene rubber,
styrene-butadiene copolymer rubber, isoprene rubber, butyl rubber,
halogenated butyl rubber, acrylonitrile-butadiene rubber,
chloroprene rubber, styrene-isoprene-butadiene copolymer rubber,
and isoprene-butadiene copolymer rubber. Other useful rubbers
include ethylene-propylene-diene copolymer rubber, styrene-isoprene
copolymer rubber, ethylene-propylene copolymer rubber, acrylic
rubber, epichlorohydrin rubber, polysulfide rubber, silicone
rubber, fluororubber, urethane rubber, and combinations
thereof.
[0039] In one or more retread situations, the cured rubber
component is a diene-based rubber. In these or other embodiments,
the cured rubber component includes synthetic polyisoprene or
natural rubber. In these or other embodiments, the cured rubber
component contains at least about 50 wt. %; in other embodiments at
least about 70 wt. %; and in yet other embodiments at least about
80 wt. % synthetic polyisoprene or natural rubber.
[0040] In one or more retread situations, step 16 includes
providing a plurality of cushion gums, wherein each cushion gum
containing a stable dinitrile oxide compound. The cushion gum
comprises a cushion gum composition containing a rubber component,
a cure system, reinforcing fillers, and other optional
ingredients.
[0041] In one or more retread situations, step 16 of providing a
plurality of cushion gums includes the step of manufacturing a
plurality of cushion gums. The manufacturing process may include
fabricating cushion gum using a cushion gum composition.
[0042] The manufacturing process for the plurality of cushion gums
is not particularly limited, and may be selected as appropriate
depending upon the application thereof. In one or more embodiments,
cushion gum may be manufactured by forming a sheet using a rolling
roll or by extrusion techniques.
[0043] The shape of the cushion gums is not particularly limited,
and may be selected as appropriate depending on the application
thereof. Regardless of what process is used to manufacture the
plurality of cushion gums, the process to prepare cushion gum may
take place at the same location in which the process for applying
the lugs to the agricultural tire takes place because the cure
system in the cushion gum composition has a limited shelf life.
That shelf life is defined as the time it takes for cushion gum to
loss its tack, or its ability to adhere to both the lug and the
cured rubber component. The shelf life of cushion gum begins at the
time the cushion gum composition is formed and ends when the
cushion gum loses its tack.
[0044] In one embodiment, the cushion gum is manufactured by
extrusion. The cushion gum composition is extruded through an
extruder to form a cushion gum extrudate. The cushion gum extrudate
may then be applied the cured rubber component. In another
embodiment, the cushion gum composition is extruded directly on to
the cured rubber component. In yet other embodiments, the gum
cushion is extruded directly onto the lugs. In still other
embodiments, the cushion gum is prepared by calendaring.
[0045] In one or more embodiments, the rubber component of the
cushion gum composition may include natural and synthetic rubbers,
which may also be referred to as elastomers. For example, the
synthetic elastomers may include diene-based rubbers such as
butadiene rubber, styrene-butadiene copolymer rubber, isoprene
rubber, butyl rubber, halogenated butyl rubber,
acrylonitrile-butadiene rubber, chloroprene rubber,
styrene-isoprene-butadiene copolymer rubber, and isoprene-butadiene
copolymer rubber. Other useful rubbers include
ethylene-propylene-diene copolymer rubber, styrene-isoprene
copolymer rubber, ethylene-propylene copolymer rubber, acrylic
rubber, epichlorohydrin rubber, polysulfide rubber, silicone
rubber, fluororubber, urethane rubber, and combinations thereof.
These rubber components may be selected as appropriate in order to
obtain high adhesiveness, depending on the content of the rubber
component which make up the cured rubber component and the rubber
component which make up the tire casing.
[0046] In one or more embodiments, the rubber component of the
cushion gum composition is a diene-based rubber. In these or other
embodiments, the rubber component of the cushion gum composition
includes synthetic polyisoprene or natural rubber. In these or
other embodiments, the cushion gum composition contains at least
about 50 wt. %; in other embodiments at least about 70 wt. %; and
in yet other embodiments at least about 80 wt. % synthetic
polyisoprene or natural rubber.
[0047] In one or more embodiments, the cure system of the cushion
gum composition comprises at least one nitrile oxide compound, such
as a stable dinitrile oxide compound. There are relatively few
chemical reactions know that can modify a diene rubber selectively
and at an ambient temperature the way nitrile oxides can. Dinitrile
oxides are extremely reactive toward double bonds, including the
carbon-carbon double bonds in rubbers. Because of this extreme
reactivity, dinitrile oxides can be employed as curing
(crosslinking) agents for rubbers.
[0048] Practice of one or more embodiments of the present invention
is not necessarily limited by the method of producing the stable
dinitrile oxide compound. Accordingly, the stable dinitrile oxide
compound is produced by various known methods, such as those
methods taught by U.S. Patent Application No. 2012/0196976 and U.S.
Pat. No. 6,355,826, both of which are incorporated herein by
reference.
[0049] In one embodiment, the stable dinitrile oxide compound is a
stable aryl dinitrile oxide compound. In one embodiment, the stable
aryl dinitrile is selected from the group consisting of mesitylene
dinitrile oxide (MDNO) and bismesitylene dinitrile oxide
(BMNO).
[0050] In one or more embodiments, the reinforcing filler of the
cushion gum composition may include carbon black, inorganic
fillers, and/or combinations thereof. The content of the
reinforcing filler is not particularly limited, and may be selected
as appropriate depending on the application thereof.
[0051] In one or more embodiments, the reinforcing filler is an
inorganic filler. The inorganic filler is not particularly limited,
and may be selected as appropriate depending on the application
thereof. In one embodiment, the inorganic filler is selected from
the group consisting of silica, aluminum hydroxide, clay, alumina,
talc, mica, kaolin, glass balloon, glass beads, calcium carbonate,
magnesium carbonate, magnesium hydroxide, calcium carbonate,
magnesium oxide, titanium oxide, potassium titanate, barium
sulfate, and combinations thereof. In some embodiments, when using
an inorganic filler, a silane coupling agent may be used as
appropriate.
[0052] In one or more embodiments, the reinforcing filler is carbon
black. The carbon black may be selected as appropriate depending on
the application thereof. In one embodiment, the carbon black is
selected from the group consisting of carbon black of HAF, FF, FEF,
GPF, SRF, FT grades, and combinations thereof.
[0053] In one or more embodiments, the cushion gum composition
comprises other components when necessary. In one embodiment, the
other components are selected from the group consisting of a
tackifier, a reinforcing agent, a softening agent, a filler, a
vulcanizing aid, a colorant, a flame retardant, a lubricant, a
foaming agent, a plasticizer, a processing aid, an antioxidant, an
age resister, an ultraviolet rays protecting agent, an antistatic
agent, a color protecting agent, and combinations thereof.
[0054] In one or more embodiments, the cushion gum composition may
include from about 10 to about 120 parts by weight filler per 100
parts by weight rubber, in other embodiments from about 20 to about
100 parts by weight filler per 100 parts by weight rubber, and in
other embodiments from about 30 to about 80 parts by weight filler
per 100 parts by weight rubber.
[0055] In one or more embodiments, the cushion gum composition may
include from about 1 to about 20 parts by weight dinitrile oxide
per 100 parts by weight rubber, in other embodiments from about 2
to about 15 parts by weight dinitrile oxide per 100 parts by weight
rubber, and in other embodiments from about 5 to about 10 parts by
weight dinitrile oxide per 100 parts by weight rubber.
[0056] In one embodiment, the content of the stable aryl dinitrile
compound is between 1 and 20 phr, parts by weight per hundred parts
of the rubber component of the cushion gum composition, preferably
between 2 and 15 phr, and more preferably between 5 and 10 phr.
[0057] The content thereof per 100 parts by mass of the rubber
component of the cushion gum composition is preferably 10 parts by
mass to 80 parts by mass, more preferably 25 parts by mass to 50
parts by mass, and particularly preferably 30 parts by mass to 40
parts by mass.
[0058] The content of the carbon black per 100 parts by mass of the
rubber component of the cushion gum composition is not particularly
limited, and may be selected as appropriate depending on the
application thereof. The content thereof is preferably 25 parts by
mass to 50 parts by mass, and more preferably 30 parts by mass to
40 parts by mass.
[0059] If the content of the carbon black per 100 parts by mass of
the rubber component is less than 25 parts by mass, sufficient
reinforcing effect may not be obtained, and if the content thereof
exceeds 50 parts by mass, the rubber composition may become too
hard.
[0060] In one or more embodiments, the cushion gum composition
comprises other components when necessary. In one embodiment, the
other components are selected from the group consisting of a
tackifier, a reinforcing agent, a softening agent, a filler, a
vulcanizing aid, a colorant, a flame retardant, a lubricant, a
foaming agent, a plasticizer, a processing aid, an antioxidant, an
age resister, an ultraviolet rays protecting agent, an antistatic
agent, a color protecting agent, and combinations thereof.
[0061] In one or more retread situations, step 18 includes
providing a plurality of lugs. In one or more embodiments, step 18
includes providing cured lugs. In one or more embodiments, the
rubber component of the lugs is a diene-based rubber. In these or
other embodiments, the rubber component of the lugs includes
synthetic polyisoprene or natural rubber. In these or other
embodiments, the lugs contain at least about 50 wt. %; in other
embodiments at least about 70 wt. %; and in yet other embodiments
at least about 80 wt. % synthetic polyisoprene or natural
rubber.
[0062] In one or more embodiments, the lugs are sulfur cured. In
other embodiments, the lugs are cured using a stabile dinitrile
oxide as described herein. In one or more embodiments, the lugs
have a substantially rectangular cross section. In an alternative
embodiment, the lugs have a trapezoidal cross-section. In another
alternative embodiment the lugs have curved sides. In another
alternative embodiment, the cross-section of the lugs may be of any
geometric shape.
[0063] Each lug of the plurality of lugs has a top surface and a
bottom surface. Each lug has a lug height which represents the
distance between top surface and the bottom surface of the lug.
Each lug may be defined by a lug angle that represents the average
inclination of the lug with respect to the cured rubber component's
equatorial plane.
[0064] In one embodiment, the lugs are extruded, and then cut to a
desired length. In an alternative embodiment, the lugs are molded.
In another alternative embodiment, the lugs are formed by a 3-D
printing or additive manufacturing process. In other alternative
embodiments, the lugs may be formed by any known process.
[0065] In one particular embodiment, the lugs are skid lugs. In
this embodiment, the height of each skid lug is approximately 6% of
the tire's width. In additional embodiments, the height of each
skid lug is between 3-8% or 4-7% of the tire's width. In further
embodiments, the height of each skid lug is between 6-18% of the
tire's width. However, it should be understood that the skid lugs
may have any height.
[0066] In an alternative embodiment, the lugs are deep skid lugs.
In this embodiment, the height of each deep skid lug is
approximately 8% of the tire's width. In additional embodiments,
the height of each deep skid lug is between 5-20% of the tire's
width. In further embodiments, the height of each deep skid lug is
between 6-22% of the tire's width. However, it should be understood
that the deep skid lugs may have any height.
[0067] In an alternative embodiment, the lugs are skid lugs for use
on a relatively narrow agricultural tire. In this embodiment, the
height of each skid lug for use on a relatively narrow agricultural
tire is approximately 14% of the tire's width. In additional
embodiments, the height of each skid lug for use on a relatively
narrow agricultural tire is between 10-17% of the tire's width. In
further embodiments, the height of each skid lug for use on a
relatively narrow agricultural tire is between 12-19% or 20-35% of
the tire's width. However, it should be understood that the skid
lugs for use on a relatively narrow agricultural tire may have any
height.
[0068] As one of ordinary skill in the art would recognize, the
lugs may be used in agricultural tire constructions designated as
R1, R1W, and R2 constructions, where R1 corresponds to a standard
skid depth (Tire & Rim Association Standard AG-09-21), R1W
corresponds to a skid depth that is 20% deeper than R1, and R2
corresponds to a skid depth that is 200% of R1. Additional examples
of tires utilizing skids include, without limitation, drive wheels
for agricultural vehicles, irrigation tires, forestry tires,
floatation tires, combine tires, tractor tires, mining tires,
construction tires, sprayer tires, and off-the-road vehicles.
[0069] In one embodiment, the lugs are arranged to provide a
mono-pitch noise-sequenced tread. In an alternative embodiment, the
lugs are modulated to provide a bi-pitch noise-sequenced tread. In
yet another embodiment, the lugs are modulated to provide a
multi-pitch noise-sequenced tread.
[0070] In one or more retread situations, step 20 includes applying
the cured rubber component to the agricultural tire casing to form
an agricultural tire composite. Practice of one or more embodiments
of the present invention is not necessarily limited by the method
of applying the cured rubber component to the agricultural tire
casing. However, one such method comprises providing a second
cushion gum, wherein the second cushion gum contains a cure system
comprising at least one stable dinitrile oxide compound; applying
the second cushion gum to the agricultural tire casing; and
applying the second planar surface of the cured rubber component to
the second cushion gum.
[0071] In one or more retread situations, step 22 includes applying
the plurality of cushion gums to the cured rubber component. In
this or other embodiments, said step of applying the plurality of
cushion gums to the cured rubber component further may include
applying a layer of unheated cushion gum directly to the cured
rubber component. Typically, each cushion gum is cut transversely,
and the cut edge is spliced with the leading edge so there is no
gap between the beginning and the end each cushion gum.
[0072] In one or more retread situations, the cushion gum is
extruded directly onto the cured rubber component at a position
where a lug is desired. In other embodiments, the cushion gum is
extruded directly onto the lug. In other embodiments, the cushion
gum is extruded onto a transfer film, and then the transfer film is
used to apply the extrudate directly to the cured rubber component,
before an appreciable amount of curing takes place, and the
transfer film is then removed.
[0073] In one or more retread situations, each cushion gum may be
applied over the cured rubber component and trimmed to size. The
resulting "cushioned" cured rubber component is then paired with a
lug and is then subjected to a treatment, as described later.
[0074] In certain retread situations, after each cushion gum is
applied the cured rubber component, a layer is stitched, or in
other words pressed, against each applied cushion to drive out any
air trapped between the cushion gum and the cured rubber component.
Following stitching, if a top layer of plastic is present over the
cushion gum, the top layer of plastic is removed from the cushion
gum to permit a lug to later be applied over the cushion gum.
[0075] In one or more retread situations, step 24 includes applying
a lug to each cushion gum that has been applied to the cured rubber
component. In one or more embodiments, step 24 includes applying
the bottom surface of each lug against the exposed portion of each
cushion gum. In one or more embodiments, each lug is also applied
with the assistance of a building machine that differs from the
building machine used to apply each cushion gum. When using a
building machine, each lug may be guided onto the cured rubber
component against each cushion gum by guide rollers.
[0076] In one or more retread situations, step 26 includes treating
the untreated agricultural tire composite to cure each cushion gum
and to form a retread agricultural tire. In one or more
embodiments, said step of treating the untreated agricultural tire
composite to cure each cushion gum further may include encasing the
agricultural tire composite in an envelope.
[0077] In one or more embodiments, after application of the cured
rubber component, the application of each cushion gum onto the
cured rubber component, and the application of the lugs, the
untreated agricultural tire composite is ready for treatment under
appropriate temperature and pressure conditions. In one or more
retread situations, step 26 of treating the untreated agricultural
tire composite includes placing the untreated agricultural tire
composite into a rubberized curing envelope designed for the
particular agricultural tire type and size being retreaded. The
envelope is sealed to the beads of the untreated agricultural tire
casing. The rubberized curing envelope is then subjected to
pressure so as to ensure that the lugs conform to the cured rubber
component. In one or more embodiments, the pressure applied is
about 70 PSI to about 100 PSI relative to atmospheric, in other
embodiments from about 80 PSI to about 95 PSI relative to
atmospheric, and in yet other embodiments from about 85 PSI to
about 90 PSI relative to atmospheric.
[0078] In one or more retread situations, step 26 of treating the
tire composite takes places at an ambient operating temperature. In
one or more embodiments, the operating temperature is between about
10.degree. C. and about 60.degree. C., in other embodiments between
about 15.degree. C. and about 50.degree. C., and in yet other
embodiments between about 18.degree. C. and about 45.degree. C.
[0079] The time required or desired to treat the tire composite
will depend on the treatment conditions. After the treatment is
complete, the pressure on the curing envelope is returned to
atmospheric, and a fully functional retread tire is formed.
[0080] Practice of one or more embodiments of the present invention
is not necessarily limited by the particular type of rubberized
curing envelope used. Accordingly, the known types of rubberized
curing envelopes are used, such as those envelopes taught by U.S.
Patent Application No. 2014/0008005, which is incorporated herein
by reference.
[0081] Various modifications and alterations that do not depart
from the scope and spirit of this invention will become apparent to
those skilled in the art. This invention is not to be duly limited
to the illustrative embodiments set forth herein.
* * * * *