Resilient tires and wheels – Tires – resilient – Anti-skid devices
Reexamination Certificate
2001-02-05
2003-09-02
Wu, David W. (Department: 1713)
Resilient tires and wheels
Tires, resilient
Anti-skid devices
C525S236000, C525S235000, C525S331900, C525S332500, C524S153000, C524S151000, C524S128000, C524S126000, C524S495000, C524S492000
Reexamination Certificate
active
06612351
ABSTRACT:
BACKGROUND OF THE INVENTION
A pneumatic rubber tire is provided having inner and outer air retention quasi envelopes which individually substantially envelop the tire air chamber and which are comprised of a first inner quasi envelope as an integral innerliner and a second outer quasi envelope as a combination of sidewalls and tread. Such pneumatic tire is of a relatively conventional open toroidal shape. The innerliner and the sidewall-tread combination are termed as being quasi envelopes in a sense that a rigid rim, onto which the tire is to be mounted and inflated, is used to complete the closure of the tire's air chamber envelope.
BACKGROUND OF THE INVENTION
A pneumatic rubber is typically of what might be termed an open toroidal shape.
A pneumatic tire is typically composed of two spaced apart, essentially inextensible, bead portions and a carcass extending from bead-to-bead and composed of one or more carcass plies, over which is integrally positioned a circumferential rubber tread and outer rubber sidewalls wherein the sidewalls extend in a radial direction from said bead portions to join the peripheral edges of said tread. The tire also typically contains an innerliner which is a rubber layer designed to assist in retaining air in the enveloped air chamber of the tire and rigid rim onto which the tire is to be mounted and inflated. Such pneumatic tire configuration is well known to those having skill in such art.
In particular the inner liner of a pneumatic rubber tire is a thin rubber layer typically comprised of an elastomeric composition designed to prevent or retard the permeation of air and moisture into the carcass from the tire's inner air chamber. Innerliners have also been used for many years in pneumatic vehicle tires to retard or prevent the escape of air used to inflate the tire, thereby maintaining tire pressure. They may also be used in tires which are designed to run on zero, or at least a very low, inflation pressure. Rubbers which are relatively impermeable to air are often used as a major portion of said innerliners and can include butyl rubber and halobutyl rubbers. U.S. Pat. No. 3,808.177 discloses other polymers which may also be relatively impermeable.
Historically, such saturated butyl rubber and halobutyl elastomers, which inherently do not have carbon-to-carbon double bonds in their backbone, such as halogenated (e.g. brominated) copolymers of isobutylene and p-methyl styrene elastomers, inherently do not effectively respond to sulfur bonding or crosslinking in the manner of unsaturated diene-based elastomers.
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 is understood to occur 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 of such halogenated saturated elastomers is limited where it is desired to use precipitated silica reinforcement in combination with a coupling agents to enhance the silica reinforcement, particularly where well known coupling agents such as, for example, bis(3-trialkoxysilylalkyl) polysulfides which contain an average of 2 to 2.6 or from 3.5 to 4 connecting sulfur atoms in their polysulfide bridges, or mercaptosilanes are used. This is because the lack of carbon-to-carbon double bonds in the saturated elastomers renders such elastomers essentially unreactive with the sulfur moiety of such coupling agents. Therefore, such saturated polymers cannot readily be coupled to the silica with such coupling agents.
Historically, it is observed that some organophosphites have been heretofore 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 organophosphites 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 term “phr” is used to designate parts by weight of a material per 100 parts by weight of elastomer. In the further description, the terms “rubber” and “elastomer” may be used interchangeably unless otherwise mentioned. The terms “vulcanized” and “cured” may be used interchangeably, as well as “unvulcanized” or “uncured”, unless otherwise indicated.
DISCLOSURE AND PRACTICE OF INVENTION
In accordance with this invention, a pneumatic rubber tire is provided of an open toroidal shape comprised of a two spaced apart inextensible bead portions with a carcass extending from bead-to-bead to define a tire cavity intend to be closed by a rigid rim positioned from bead-to-bead to form an air-containing envelope, wherein said carcass contains
(A) a rubber innerliner on its inner surface, and
(B) a combination of a circumferential rubber tread and pair of rubber sidewalls on the outersurface of said carcass wherein said sidewalls extend radially outward from said bead portions to join the respective peripheral edges of said tread,
wherein said innerliner, tread and sidewalls are individually comprised of, based upon parts by weight per 100 parts by weight elastomer(s), (phr);
(1) about 20 to 100, alternately about 50 to about 80, phr of halogenated isobutylene copolymer selected from
(a) halogenated copolymer of isobutylene and isoprene, wherein said halogen is selected from bromine or chlorine, preferably bromine, and wherein the ratio of isoprene to isobutylene is in a range of about 5/100 to about 10/100; or
(b) halogenated copolymer of isobutylene and p-methylstyrene, wherein said halogen is selected from bromine or chlorine, preferably bromine, and wherein the ratio of isobutylene to p-methylstyrene is in a range of 50/1 to 7/1; and
(2) from zero to about 80, alternately about 20 to about 50, phr of at least one diene-based elastomer;
wherein said innerliner is preferably comprised of from 5 to about 90, alternately about 10 to about 55, phr of said halogenated isobutylene copolymer and, correspondingly about 10 to about 95, alternately about 45 to about 90, phr of said diene-based elastomers;
wherein said innerliner, tread and sidewalls individually contain about 25 to about 100, alternately about 35 to about 90, phr of particulate reinforcing filler comprised of
(a) from zero to about 100, alternately about 10 to about 85, phr of synthetic amorphous silica aggregates and, correspondingly,
(b) from zero to about 75, alternately about 10 to about 60 phr of at least one of carbon black and silica treated carbon black ha
Lee Rip A.
The Goodyear Tire & Rubber Company
Wu David W.
Young, Jr. Henry C.
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