Resilient tires and wheels – Tires – resilient – Anti-skid devices
Reexamination Certificate
2000-07-25
2003-03-18
Maki, Steven D. (Department: 1733)
Resilient tires and wheels
Tires, resilient
Anti-skid devices
C152S510000, C152S537000, C152S564000
Reexamination Certificate
active
06533008
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a liquid polysulfide compound which is useful in rubber compositions for use in a pneumatic tire.
BACKGROUND OF THE INVENTION
Polysulfide rubbers have long been known in the art and are known to have certain outstanding properties such as excellent resistance to a wide range of solvents, good resistance to atmospheric oxidation and weathering, adherence to metals and retention of their elastic properties over a relatively wide temperature range. They were initially produced as solid polymers. At a later date, methods were developed (as disclosed, for example, in U.S. Pat. No. 2,466,963) for splitting the solid polymers to form liquid polythiopolymercaptan polymers that are curable to form rubber-like materials having the desirable properties described above. The liquid polymers are particularly useful in a wide variety of applications because of the ease of handling a liquid material and of forming it to a desired configuration in which it can be cured to become a shaped elastomeric product.
As disclosed in U.S. Pat. No. 2,466,963, the polysulfide polymer molecules are characterized by the recurring unit (RSS), in which R represents the same or different divalent organic radicals that can vary widely in their specific structure but are typically alkylene or oxyhydrocarbon radicals interconnected by disulfide groups. While a wide variety of such polymers can be prepared, the polymers that are presently of commercial importance fall within a somewhat more limited group. Several of the commercially important liquid polymers are particularly described in articles by Fettes and Jorczak, published in
Industrial and Engineering Chemistry,
vol 42, page 2217 (1950) and vol 43, page 324 (1951). As pointed out in these articles, the commercially available liquid polysulfide polymers (e.g., the LP-2, LP-3, LP-12, LP-31, LP-32 and LP-33 polymers, available from Morton International, Chicago, Ill.) (“LP” is a registered trademark of Thiokol Corporation) are generally prepared from bis-beta-chloroethyl-formal and have essentially the following structure:
HS&Parenopenst;C
2
H
4
OCH
2
OC
2
H
4
SS&Parenclosest;
x
C
2
H
4
OCH
2
OC
2
H
4
SH
wherein x has an average value of from about 2 to about 59, preferably from about 5 to about 20. Morton International also markets ELP-3 and ELP-33 which are the epoxy-terminated derivatives of the LP-3 and the LP-33 polysulfides, respectfully.
SUMMARY OF THE INVENTION
The present invention relates to a pneumatic tire having a rubber component containing a liquid polysulfide compound.
DETAILED DESCRIPTION OF THE INVENTION
There is disclosed a pneumatic tire having a rubber component comprised of
(a) 100 parts by weight of at least one elastomer containing olefinic unsaturation; and
(b) 1 to 20 phr of a liquid organic polysulfide polymer having a molecular weight of from 500 to 10,000.
The present invention relates to a pneumatic tire having a rubber component containing elastomers having olefinic unsaturation. The phrase “rubber or elastomer containing olefinic unsaturation” is intended to include both natural rubber and its various raw and reclaim forms as well as various synthetic rubbers. In the description of this invention, the terms “rubber” and “elastomer” may be used interchangeably, unless otherwise prescribed. The terms “rubber composition,” “compounded rubber” and “rubber compound” are used interchangeably to refer to rubber which has been blended or mixed with various ingredients and materials and such terms are well known to those having skill in the rubber mixing or rubber compounding art. Representative synthetic polymers are the homopolymerization products of butadiene and its homologues and derivatives, for example, methylbutadiene, dimethylbutadiene and pentadiene as well as copolymers such as those formed from butadiene or its homologues or derivatives with other unsaturated monomers. Among the latter are acetylenes, for example, vinyl acetylene; olefins, for example, isobutylene, which copolymerizes with isoprene to form butyl rubber; vinyl compounds, for example, acrylic acid, acrylonitrile (which polymerize with butadiene to form NBR), methacrylic acid and styrene, the latter compound polymerizing with butadiene to form SBR, as well as vinyl esters and various unsaturated aldehydes, ketones and ethers, e.g., acrolein, methyl isopropenyl ketone and vinylethyl ether. Specific examples of synthetic rubbers include neoprene (polychloroprene), polybutadiene (including cis-1,4-polybutadiene), polyisoprene (including cis-1,4-polyisoprene), butyl rubber, styrene/isoprene/butadiene rubber, copolymers of 1,3-butadiene or isoprene with monomers such as styrene, acrylonitrile and methyl methacrylate, as well as ethylene/propylene terpolymers, also known as ethylene/propylene/diene monomer (EPDM), and in particular, ethylene/propylene/dicyclopentadiene terpolymers. The preferred rubber or elastomers are natural rubber, polybutadiene and SBR.
In one aspect, the rubber is preferably of at least two of diene-based rubbers. For example, a combination of two or more rubbers is preferred such as cis 1,4-polyisoprene rubber (natural or synthetic, although natural is preferred), 3,4-polyisoprene rubber, styrene/isoprene/butadiene rubber, emulsion and solution polymerization derived styrene/butadiene rubbers, cis 1,4-polybutadiene rubbers and emulsion polymerization prepared butadiene/acrylonitrile copolymers.
In one aspect of this invention, an emulsion polymerization derived styrene/butadiene (E-SBR) might be used having a relatively conventional styrene content of about 10 to about 28 percent bound styrene or, for some applications, an E-SBR having a medium to relatively high bound styrene content, namely, a bound styrene content of about 30 to about 45 percent.
The relatively high styrene content of about 30 to about 45 for the E-SBR can be considered beneficial for a purpose of enhancing traction, or skid resistance, of the tire tread. The presence of the E-SBR itself is considered beneficial for a purpose of enhancing processability of the uncured elastomer composition mixture, especially in comparison to a utilization of a solution polymerization prepared SBR (S-SBR).
By emulsion polymerization prepared E-SBR, it is meant that styrene and 1,3-butadiene are copolymerized as an aqueous emulsion. Such are well known to those skilled in such art. The bound styrene content can vary, for example, from about 5 to about 50 percent. In one aspect, the E-SBR may also contain acrylonitrile to form a terpolymer rubber, as E-SBAR, in amounts, for example, of about 2 to about 30 weight percent bound acrylonitrile in the terpolymer.
Emulsion polymerization prepared styrene/butadiene/acrylonitrile copolymer rubbers containing about 2 to about 40 weight percent bound acrylonitrile in the copolymer are also contemplated as diene based rubbers for use in this invention.
The solution polymerization prepared SBR (S-SBR) typically has a bound styrene content in a range of about 5 to about 50, preferably about 9 to about 36, percent. The S-SBR can be conveniently prepared, for example, by organo lithium catalyzation in the presence of an organic hydrocarbon solvent.
A purpose of using S-SBR is for improved tire rolling resistance as a result of lower hysteresis when it is used in a tire tread composition.
The 3,4-polyisoprene rubber (3,4-PI) is considered beneficial for a purpose of enhancing the tire's traction when it is used in a tire tread composition. The 3,4-PI and use thereof is more fully described in U.S. Pat. No. 5,087,668 which is incorporated herein by reference. The Tg refers to the glass transition temperature which can conveniently be determined by a differential scanning calorimeter at a heating rate of 10° C. per minute.
The cis 1,4-polybutadiene rubber (BR) is considered to be beneficial for a purpose of enhancing the tire tread's wear, or treadwear. Such BR can be prepared, for example, by organic solution polymerization of 1,3-butadiene. The BR may be conveniently characterized, for examp
Henoumont Marc Jules Alexis
Lickes Jean-Paul
Linster Tom Dominique
DeLong J. D.
Hendricks B. J.
Maki Steven D.
The Goodyear Tire & Rubber Company
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