Resilient tires and wheels – Tires – resilient – Pneumatic tire or inner tube
Reexamination Certificate
2002-09-17
2004-12-28
Knable, Geoffrey L. (Department: 1733)
Resilient tires and wheels
Tires, resilient
Pneumatic tire or inner tube
C152S524000, C525S192000, C525S193000, C525S333400
Reexamination Certificate
active
06834697
ABSTRACT:
FIELD OF THE INVENTION
A tire having a visible sidewall of a rubber composition containing a combination of:
(A) a liquid ethylene/butylene copolymer having a terminal hydroxyl group on one end of the copolymer and either a partially hydrogenated polyisoprene block containing olefinic double bonds, or an epoxidized polyisoprene block containing olefinic double bonds, on the other end of the copolymer,
(B) cis 1,4-polybutadiene rubber,
(C) a brominated copolymer of isobutylene and para-methylstyrene, and
(D) a minor amount of at least one conjugated diene-based rubber, preferably cis 1,4-polyisoprene.
In such manner, it is considered herein that such liquid polymers are functional liquid polymers via the associated terminal hydroxyl group on one end of the copolymer and the modified polyisoprene blocks on the other end. In another aspect, the liquid copolymers are seen herein to act as processing aids for the rubber composition followed by becoming an integral part of the polymer network upon sulfur curing the resulting rubber composition. Therefore, a tire having a sulfur cured, visible sidewall rubber composition is also provided. In a further aspect, the rubber composition may be reinforced with a reinforcing filler as carbon black or as a combination of carbon black and silica together with a coupling agent.
BACKGROUND OF THE INVENTION
Pneumatic tires have sidewalls which are conventionally desired to have good resistance to flex fatigue, scuff resistance and resistance to tear. A suitable visual appearance of the tire sidewall surface may also be a desirable property.
Scuff resistance for a tire sidewall rubber composition is typically enhanced by inclusion of cis 1,4-polybutadiene rubber which is well known to those having skill in such art.
Resistance to flex fatigue for a tire rubber sidewall may sometimes be enhanced by inclusion of an aromatic, naphthenic or parafinnic rubber processing oil in its composition which is also well known by those having skill in such art.
However, while rubber processing oils have been used to improve the processability (e.g. reduced rubber viscosity) of various unvulcanized high viscosity elastomers, as well as improving resistance to flex fatigue of a rubber composition for use as a tire sidewall application, the inclusion of processing oils in such rubber compositions often results in a decrease in various physical properties such as, for example, a vulcanized modulus of elasticity. Accordingly, the use of substantial amounts of processing oils in rubber compounds for a purpose of enhancing their unvulcanized processability, as well as improving resistance to flex fatigue is not necessarily a desirable option.
In one aspect, it has heretofore been proposed to use various diene-based liquid polymers which contain olefinic unsaturation to replace at least a portion of rubber processing oil contained in various rubber compositions. One philosophy has been for the liquid polymer to initially enhance the processability (e.g. reduce rubber viscosity) of a high viscosity unvulcanized rubber composition by reducing its viscosity and to later co-sulfur vulcanize with the elastomer via the olefinic double bonds contained in the liquid polymer upon sulfur vulcanizing the rubber composition.
In another aspect, U.S. Pat. No. 6,255,397 relates to replacement of conventional rubber processing oils with a prescribed hydroxyl terminated liquid polyalkylene-based polymer which reportedly resulted in improved resistance to flex fatigue in the absence of amine-based antioxidants for a sulfur-cured tire sidewall rubber composition which was composed of cis 1,4-polybutadiene, a brominated copolymer of isobutylene and para-methylstyrene and a minor amount of cis 1,4-polyisoprene.
However, it remains desirable to continue to improve various properties for a tire rubber sidewall.
In the description of this invention, the term “phr” as used herein, and according to conventional practice, refers to “parts of a respective material per 100 parts by weight of rubber”. The terms “rubber” and “elastomer” can be used interchangeably, unless otherwise indicated. The terms “rubber composition”, “compounded rubber” and “rubber compound” can be used interchangeably to refer to “rubber which has been blended or mixed with various ingredients and materials” and the terms “cure” and “vulcanize” may also be used interchangeably herein, unless otherwise indicated and such terms are well known to those having skill in the rubber mixing or rubber compounding art.
SUMMARY AND PRACTICE OF THE INVENTION
In accordance with this invention a tire is provided having a visible sidewall of a rubber composition comprised of, based upon parts by weight per 100 parts by weight rubber (phr):
(A) 100 phr of elastomers comprised of
(1) about 30 to about 70, alternately about 35 to about 65, phr of cis 1,4-polybutadiene rubber,
(2) zero to about 30, alternately about 5 to about 25, phr of cis 1,4-polyisoprene rubber, and
(3) about 30 to about 70, alternately about 40 to about 60, phr of brominated copolymer of isobutylene and p-methylstyrene;
(B) about 2 to about 30, alternately about 5 to about 25, phr of a liquid polyalkylene copolymer selected from:
(1) a first ethylene/butylene copolymer having a mono-terminal hydroxyl group on one end of the copolymer and an hydrogenated polyisoprene block which contains olefinic double bonds therein on the other end of the copolymer, or
(2) a second ethylene/butylene copolymer having a mono-terminal hydroxyl group on one end of the copolymer and an epoxidized polyisoprene block on the other end of the copolymer, and
(C) about 15 to about 70 phr of reinforcing filler as:
(1) carbon black, or
(2) combination of carbon black and synthetic precipitated silica, optionally with a coupling agent having a moiety reactive with hydroxyl groups (e.g. silanol groups) contained on the precipitated silica and another moiety interactive with said conjugated diene-based elastomer(s).
It is a significant aspect of this invention that the rubber composition is suitable for a tire sidewall where high flex endurance properties over a considerable period of time and good resistance to atmospheric ozone degradation without use of amine-based antidegradants in the rubber composition is desired.
In further accordance with this invention, a tire is provided having said visible sidewall rubber composition as a sulfur cured rubber composition. For such tire, the unvulcanized tire assembly, including its sidewall rubber composition, is vulcanized in a suitable mold at an elevated temperature to shape and sulfur-vulcanize the associated rubber compositions of the tire. In such manner, the liquid hydroxyl terminated, saturated ethylene/butylene backbone copolymers having a modified polyisoprene block on the opposite end of the copolymer becomes a part of the sulfur cured network of the sidewall rubber composition in combination with the diene-based rubbers and brominated copolymer of isobutylene and para methylstyrene. Therefore, a tire is provided where said sidewall rubber composition is sulfur vulcanized and said hydroxyl terminated ethylene/butylene backbone copolymer containing said modified polyisoprene block is a part of the sulfur vulcanized rubber network of said sidewall rubber composition.
A significant aspect of this invention is the inclusion of the specified polyalkylene copolymers in a tire sidewall in combination with the cis 1,4-polybutadiene rubber and the brominated copolymer of isobutylene and para-methylstyrene.
Interestingly, it can readily be seen that the liquid copolymers are of a saturated ethylene/butylene backbone containing on one end a mono-hydroxyl terminal group and on the other end of the saturated liquid copolymer backbone is the olefinic (carbon-to-carbon unsaturation) polyisoprene block or the epoxidized polyisoprene block.
In particular, the mono-hydroxyl termination of the copolymers is considered herein to be beneficial in that it might provide compatibility with the diene-based rubbers whereas the ethylene/butylene backbone provides compatibili
Knable Geoffrey L.
The Goodyear Tire & Rubber Company
Young, Jr. Henry C.
LandOfFree
Tire having sidewall of rubber composition containing... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Tire having sidewall of rubber composition containing..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Tire having sidewall of rubber composition containing... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3309344