Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2002-03-14
2003-11-11
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S331900, C525S333100, C525S534000, C525S535000, C525S537000, C524S492000, C524S495000
Reexamination Certificate
active
06646066
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a rubber composition which contains a thermoplastic polymer and use thereof as a tire sidewall component and/or tread supporting ring for use in a tire/rim assembly. Such tire sidewall component may be a sidewall insert and/or apex of a rubber composition which contains a thermoplastic polymer.
BACKGROUND OF THE INVENTION
Pneumatic tires conventionally contain a relatively hard rubber sidewall insert in the nature of an apex as an insert within a tire's sidewall adjacent to, and usually juxtapositioned to, a tire's bead portion to aid in controlling the stiffness of the tire's sidewall.
For some tires, particularly tires which are intended to be able to run with only atmospheric air pressure within the pneumatic tire cavity, a relatively hard rubber insert is positioned in the tire sidewall which may be spaced apart from the bead portions in order to add support as well as stiffness to the tire sidewall.
Such insert-containing sidewall, because of a usual inherent increased thickness of the sidewall itself, an inherent increase in heat generation is typically experienced which results in an increased running temperature for the tire sidewall during its operation of moving its associated vehicle.
The invention relates to use of an inclusion of a particular thermoplastic polymer in such rubber sidewall inserts to reduce heat generation within the rubber insert while substantially maintaining its compression modulus.
The invention also relates to a tread support ring in a tire/rim assembly comprised of a rubber composition which contains an inclusion of a thermoplastic polymer to aid in reducing heat generation.
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. The terms “rubber” and “elastomer” may be used interchangeably unless otherwise indicated. The terms “vulcanized” and “cured” may be used interchangeably, as well as “unvulcanized” or “uncured”, unless otherwise indicated.
SUMMARY AND PRACTICE OF THE INVENTION
In accordance with this invention, a rubber composition containing a thermoplastic polymer is provided which comprises at least one diene-based elastomer and an inclusion therein of said thermoplastic polymer is provided which comprises, based upon 100 phr of elastomer:
(A) 100 phr of a diene-based elastomer, and
(B) about 5 to about 20, alternately about 5 to about 10, phr of particulate thermoplastic material dispersed therein selected from at least one of polyphenylene ether, polyphenylene sulfide and syndiotactic polystyrene,
(C) about 20 to about 100, alternately about 25 to about 90, phr of at least one reinforcing particulate filler selected from carbon black, aggregates of synthetic amorphous silica and silica-containing carbon having domains of silica on its surface, and
(D) a coupling agent having a moiety reactive with hydroxyl groups (e.g. silanol groups) contained on the surface of said precipitated silica and said silica domains on the surface of said silica-containing carbon black and another moiety interactive with at least one of said elastomers.
In further accordance with this invention, a tire is provided having an insert within its sidewall comprised of said elastomer having said inclusion therein of said thermoplastic polymer.
In additional accordance with this invention a tire/rim assembly is provided comprised of a pneumatic tire mounted on a rigid rim to form a cavity therebetween (generally confined by the cavity of said pneumatic tire and said rim), wherein said rim contains a tire tread supportable ring mounted thereon and within said cavity, wherein said ring is comprised of said rubber composition which contains an said inclusion therein of said thermoplastic polymer.
In said tire sidewall, said insert may be in a form of an apex in juxtaposition to one or more tire tread component or may be spaced apart from said bead portion to a position closer to the tire tread.
In said tire/rim assembly, said tread supporting ring is typically mounted on the tire rim within the pneumatic tire envelope, or toriodal cavity, in a manner to not normally contact the tire carcass in the crown region of the tire beneath the tire tread, but to contact and thereby support the tire when the tire looses its inflation pressure to keep the tire from going flat.
In practice the tire is a substantially open toroidaly shaped pneumatic rubber tire comprised of a carcass which supports a circumferential tread designed to be ground contacting and which contains two spaced apart, relatively inextensible bead portions, and two sidewall portions which individually extend from each of said bead portions to the tire tread;
wherein said carcass is comprised of at least one carcass ply extending from bead to bead, and optionally at least one belt ply extending circumferentially around said carcass and positioned between said tread and said carcass plies;
wherein said carcass plies and belt plies are individually comprised of a laminate of a rubber composition and a plurality of spaced apart cords disposed in a substantially parallel relationship to each other, wherein said rubber composition encapsulates said cords, and wherein said cords are comprised of one or more filaments, wherein said filaments are selected from brass coated steel filaments, polyester filaments, nylon filaments, aramid filaments and glass filaments;
wherein said carcass contains
(A) an apex as a strip of a rubber composition in a shape of an annular ring positioned within a carcass sidewall adjacent to a bead portion of the carcass in a primary annular direction circumferentially co-extensive within the sidewall portion of the carcass and a secondary radial direction extending toward and spaced apart from the tire tread, and/or;
(B) a sidewall insert as a strip of said rubber composition which contains an inclusion of said thermoplastic polymer, in a shape of an annular ring positioned within a carcass sidewall and spaced apart from a carcass bead portion in a primary annular direction circumferentially co-extensive within the sidewall portion of the carcass and a secondary radial direction extending toward and spaced apart from the tire tread.
Coupling agents for said rubber composition which contains an inclusion of said thermoplastic polymer and silica and/or carbon black which contains silica domains on its surface, may include, for example, bis(3-trialkoxysilylalkyl) polysulfides, such as, for example, a bis(3-trioxysilylpropyl) polysulfide, having an average of from about 2 to about 2.6 or from 3.5 to about 4, connecting sulfur atoms in its polysulfidic bridge, preferably from 2 to 2.6 connection sulfur atoms.
The polyphenylene oxide material may be a poly(2,6-dimethyl-p-phenylene) ether obtained as Vistoran™ 1900 from the Creanova Company and blended with polystyrene polymers.
The polyphenylene sulfide material may be Ryton™ from the Phillips Petroleum Company.
The syndiotactic polystyrene may contain a small amount of co-polymerized p-methylstyrene and obtained as Questra™ from the Dow Chemical Company.
A significant aspect of is this invention is the reduction of heat generation in the rubber composition which contains a dispersion of such polymers.
In practice, for the purposes of this invention, said thermoplastic polymer is homogeneously dispersed in its elastomer host by mixing at a temperature in a range of about 100° C. to about 175° C. and under conditions sufficient to break down the elastomer and disperse the thermoplastic polymer therein.
In practice, various diene-based elastomers may be used for the tire component (e.g. tire tread) such as, for example, polymers of isoprene and/or 1,3-butadiene and copolymers of styrene with isoprene and/or 1,3-butadiene.
Representative of such conjugated diene-based elastomers are, for example, cis 1,4-polyisoprene (natural and synthetic), cis 1,4-polybutadiene, styrene/butadiene copolymers (aqueous emulsion polymerization prepared and organic solvent solution polymerization prepared), medium v
Benko David Andrew
Hahn Bruce Raymond
Hargis Ivan Glen
Lee Rip A
The Goodyear Tire & Rubber Company
Wu David W.
Young, Jr. Henry C.
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