Resilient tires and wheels – Tires – resilient – Anti-skid devices
Reexamination Certificate
2001-02-01
2003-05-13
Maki, Steven D. (Department: 1733)
Resilient tires and wheels
Tires, resilient
Anti-skid devices
C152S209160, C152S524000, C152SDIG001
Reexamination Certificate
active
06561243
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a tire with a colored sidewall joined with a plurality of colored grooves in its tread. In particular, the present invention relates to a tire of a black-colored rubber composition having a non-black colored sidewall portion which is integral with a plurality of non-black colored grooves of a tread of lug and groove configuration. For said tread, at least a portion of the visible surface of a plurality of tread grooves, exclusive of the outer surface portion of said carbon black reinforced rubber lugs intended to be ground-contacting, is of a non-black colored, synthetic amorphous silica reinforced rubber composition exclusive of carbon black. For said colored sidewall and plurality of connecting tread groove combination, said tread groove and sidewall may be of the same or different non-black color(s). In one aspect, said non-black visible surface of said tread grooves and connecting sidewall contains an elastomeric brominated copolymer of isobutylene and p-methyl styrene in combination with an organo phosphite compound.
BACKGROUND OF THE INVENTION
Most tires have a tread of a lug and groove configuration of a rubber composition which contains carbon black and is therefore black in color.
It may sometimes be desired to provide a tire with a colored sidewall. Such colored sidewalls are normally prepared by providing a sidewall rubber composition which is devoid of carbon black and contains white titanium dioxide as a coloring pigment.
It may sometimes desired to provide a tire with a colored tread. In such case, the tread rubber composition is also devoid of carbon black and, in order to achieve suitable tread rubber physical properties, a particulate, synthetic amorphous silica is used to reinforce the rubber and a colorant added to achieve the desired color for the tire tread
For example, see PTC patent application WO 99/01299 and also Austrian Patent No. 335 726.
It should pointed out that it is considered herein that a significant disadvantage of tires with treads of lug and groove configuration where the outer surface of the tread lugs designed to be ground-contacting is of a non-black color is
(A) a tendency of such tire tread lugs to leave colored markings on the road over which they travel, which can be objectionable where such roads have other colored markings designed to aid or control vehicular traffic patterns and
(B) a tendency of the outer non-black tread lug surface to become discolored, particularly unevenly discolored, as the outer surface of the tread lugs travel over surfaces such as, for example, asphalt roads.
Therefore, it may sometimes be desirable to provide a tire tread where its grooves are of a non-black color and, further, to provide such tread where such colored grooves communicate with a colored tire sidewall both of which are exclusive of carbon black and are silica reinforced.
It should be appreciated that rubber compositions based upon sulfur curable diene derived elastomers which contain carbon-to-carbon double bond unsaturation in their elastomer backbone may be reinforced with silica and be exclusive of carbon black.
A coupling agent is often used for such silica reinforced rubber compositions to aid in enabling the silica to effectively reinforce the rubber composition to achieve suitable physical properties whether for the tire tread or tire sidewall. Widely used coupling agents for such purpose are comprised of a moiety (e.g. an alkoxysilane moiety) which is reactive with hydroxyl groups (e.g. silanol groups) on the surface of the silica and another moiety (e.g. a polysulfide moiety) which is interactive with unsaturated elastomers which contain carbon-to-carbon double bonds in their elastomer backbone. Such silica coupling agent activity is believed to be well known to those skilled in such art.
However, saturated elastomers, which inherently do not have carbon-to-carbon double bond in their backbone, such as halogenated (e.g. brominated) copolymers of isobutylene and p-methyl styrene elastomers inherently do not respond to sulfur bonding or crosslinking in the manner of unsaturated diene-based elastomers.
Accordingly, coupling agents for the silica which rely upon an interaction with diene-based elastomers which contain carbon-to-carbon double bonds unsaturation in their backbone, namely polysulfide based couplers such as, for example bis(3-alkoxysilylalkyl) polysulfides, are considered herein to have limited value for coupling the silica to the elastomer, even when the rubber composition contains a diene hydrocarbon based elastomer, wherein the rubber composition has an appreciable amount of an elastomeric brominated copolymer of isobutylene and p-methyl styrene.
Such copolymers typically have a ratio of isobutylene to p-methyl styrene in a range of about 50/1 to 7/1.
In practice, the aforesaid saturated halogenated copolymer elastomer might be prepared, for example, by first copolymerizing isobutylene and p-methyl styrene. Usually a ratio of isobutylene to p-methyl styrene in a range of about 50/1 to about 7/1 is used. The resulting copolymer is then halogenated with a halogen such as bromine which occurs at the paramethyl position, yielding a benzyl bromide functionality. The degree of bromination can typically be varied from about 0.5 to about 2.5, usually preferably about 1.5 to about 2.5, weight percent, based upon the copolymer of isobutylene and p-methyl styrene.
The following reference provides additional information relating to the preparation of such halogenated copolymers: “A New Isobutylene Copolymer; Non-tire Uses” by D. Kruse and J. Fusco,
Rubber & Plastics News,
Feb. 1, 1993”.
Such brominated copolymer of isobutylene and p-methyl styrene may, for example, have physical properties such as, for example, a Mooney viscosity value (ML(1+8) at 125° C.) in a range of about 35 to about 60 and a Tg in a range of about −50° C. to about −60° C.
It is to be appreciated that such halogenated (e.g. brominated) copolymer elastomer has a completely saturated backbone as being devoid of carbon-to-carbon double bond unsaturation and therefore is uniquely useful for a rubber composition where stability of various of its physical properties desired when the rubber composition is exposed to atmospheric conditions which conventionally attack unsaturated diene-based elastomers and particularly oxidative influences of ozone.
However, the utility for such halogenated saturated elastomers is limited because, as hereinbefore discussed, because of its lack of carbon-to-carbon double bonds, it is not considered as being reactive with sulfur and is therefore not ordinarily considered as being sulfur curable in a sense of diene hydrocarbon-based elastomers.
Historically, some organo phosphites have previously been recognized as being reactive with alkyl halides. For example, see
Introduction to Organic Chemistry,
2
nd
Edition, by A. Steitwieser, Jr and C. H. Heathcock, Page 829, which refers to a Arbuzov-Michaelis reaction of a phosphite with an alkyl halide.
It is contemplated herein to apply such indicated alkyl halide activity of organo phosphites for enhancing the utilization of silica reinforcement of rubber compositions which contain a halogenated copolymer of isobutylene and p-methyl styrene.
In the description of this invention, the terms “rubber” and “elastomer” if used herein, may be used interchangeably, unless otherwise prescribed. The terms “rubber composition”, “compounded rubber” and “rubber compound”, if used herein, 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.
In the description of this invention, the term “phr” refers to parts of a respective material per 100 parts by weight of rubber, or elastomer. The terms “rubber” and “elastomer” may be used interchangeably unless otherwise indicate. The terms “cure” and “vulcanize” may be used interchangeably unless otherwise indicated.
SUMMARY AND
Holden Brian David
Zanzig David John
Maki Steven D.
The Goodyear Tire & Rubber Company
Young, Jr. Henry C.
LandOfFree
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