Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2000-09-14
2004-03-30
Mulcahy, Peter D. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S495000, C525S331900, C525S342000, C152S209100
Reexamination Certificate
active
06713549
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a rubber composition which contains reinforcement selected from at least one of synthetic amorphous silica, carbon black and silica treated carbon black, non-alkoxysilane containing coupling agent, wherein at least one of said reinforcements is pre-treated prior to its addition to said rubber composition with at least one of an alkylsilane hydrophobating agent and/or non-alkoxysilane containing coupling agent, and to articles of manufacture, including tires, having at least one component comprised of such rubber composition
BACKGROUND OF THE INVENTION
For various applications utilizing rubber compositions, carbon black and/or synthetic amorphous silica-based materials are conventionally used as particulate reinforcing fillers for the elastomer(s) of the rubber composition(s).
Often a coupling agent is used together with the silica in order to couple, or otherwise enhance, its elastomer reinforcement effect for the elastomer(s) and such use of a coupling agent is well known to those having skill in such art. Such coupling agents might also be sometimes referred to as being adhesive agents insofar as use thereof to enhance reinforcement of various elastomer compositions with various silica-based materials such as, for example, aggregates of precipitated silica.
Historically, such adhesive agents are conventionally silane-based compounds which have one moiety (a silane-based moiety such as, for example, an alkoxysilane moiety) which is reactive with hydroxyl groups (e.g. silanol groups) on the surface of a synthetic amorphous silica and having another moiety (e.g. a polysulfide bridge) which becomes interactive with a conjugated diene-based elastomer.
For example, bis-(3-triethoxysilylpropyl) polysulfides having an average of from 2 to 4 connecting sulfur atoms in their polysulfidic bridge are often used as a coupling agent (or adhesive) to enhance coupling of synthetic amorphous silicas, such as aggregates of precipitated silica, to various conjugated diene-based elastomers. Use of such coupling agents is well known to those having skill in such art.
However, use of silane-containing coupling agents, or adhesives, which rely upon a reaction between the silane and hydroxyl groups (e.g. silanol groups) on the surface of a synthetic amorphous silica typically releases an alcohol as a by product of such reaction. For example, a reaction of a bis-(3-triethoxysilylpropyl) polysulfide coupling agent with silanol groups on the surface of a silica material releases ethanol as a byproduct.
For various purposes, it may be desired to reduce such alcohol evolution created by an in situ reaction of said reactants, with an associated alcohol formation, within an elastomer host during the mixing of a rubber composition which contains such reactants.
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.
Historically, it is also sometimes desired to homogeneously blend synthetic amorphous silica aggregates more efficiently with a rubber composition.
It is to be appreciated that such precipitated silica aggregates are, in general, hydrophilic in nature and thereby tend to agglomerate together within an unvulcanized rubber composition during the mixing thereof so that it is sometimes relatively difficult to obtain a homogeneous blend of such silica aggregates within the rubber composition without extensive mixing of the rubber and silica aggregates.
Accordingly, it has sometimes been suggested to hydrophobate such silica aggregates with an alkylsilane. Such silica hydrophobation may be accomplished, for example, by (1) mixing a hydrophobation agent with the rubber composition so that the silica aggregates are hydrophobated in situ within the elastomer host or (2) by pre-treating the silica aggregates during or after their precipitative formation prior to the introduction of the silica aggregates into the rubber composition. For example see U.S. Pat. Nos. 5,094,829; 5,708,069; 5,789,514; 5,750,610 and 5,914,364.
Accordingly, it is desired herein to provide and utilize a non alkoxysilane containing coupling agent for a synthetic amorphous silica-based material within a diene-based elastomer host which does not readily produce an alcohol as a byproduct in combination with pre-hydrophobated synthetic amorphous silica aggregates.
The term “phr” where used herein, and according to conventional practice, refers to “parts of a respective material per 100 parts by weight of rubber, or elastomer”.
In the description of this invention, the terms “rubber” and “elastomer” where 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.
A reference to an elastomer's Tg, if used herein, refers to its glass transition temperature, which can conveniently be determined by a differential scanning calorimeter at a heating rate of 10° C. per minute.
SUMMARY AND PRACTICE OF THE INVENTION
In accordance with this invention, a rubber composition is provided which comprises, based upon parts by weight per 100 parts by weight elastomer (phr):
(A) 100 parts by weight of at least one diene-based elastomer,
(B) about 25 to about 100, optionally about 35 to about 90, phr of particulate reinforcing filler comprised of about 25 to about 100, alternately about 10 to about 70, phr of synthetic amorphous silica aggregates and, correspondingly, from zero to about 75, alternately about 10 to about 60 phr of at least one of carbon black and silica treated carbon black having domains of silica on its surface; wherein said silica aggregates and said silica domains on the surface of said treated carbon black contain hydroxyl groups (e.g. silanol groups) on their surface; and
(C) about 0.5 to about 10, alternately about 1 to about 7, phr of a coupling agent selected from at least one of:
(1) carboxymaleimidophenyl ester, (U.S. Pat. No. 5,990,210)
(2) 2,2′ dithiosalicylic acid, disodium salt, (U.S. Pat. No. 5,961,755)
(3) bis-succinimide polysulfide, (U.S. Pat. No. 5,922,792)
(4) 2-benzothiazyl-3-(propane-1,2-diol), (U.S. Pat. No. 5,900,467)
(5) o-salicylsalicylic acid, (U.S. Pat. No. 5,886,074)
(6) pyrazine amide, (U.S. Pat. No. 5,739,211)
(7) 3,3′-tetrathiodipropanol, (U.S. Pat. No. 5,733,963)
(8) hydroxyethyl-phenoxyacetic acid, (U.S. Pat. No. 5,719,208)
(9) 3,3′tetrathiodipropionamide, (U.S. Pat. No. 5,641,820)
(10) poly-(2-propanol-1,3-polysulfide), (U.S. Pat. No. 5,610,216)
(11) 3,3′-tetrathiodipropionitrile, (U.S. Pat. No. 5,605,951)
(12) Nicotinamide, (U.S. Pat. No. 5,504,137)
(13) zinc and sodium salts of salicylic acid, (U.S. Pat. No. 5,534,578)
(14) diaminodirosinate salts, (U.S. Pat. No. 5,434,206), and
(15) bisaniline PD bismaleimide, (U.S. Pat. No. 5,153,248);
wherein said coupling agent is mixed with at least one of said elastomers according to one or more of the following:
(1) mixing at least one of said coupling agents with said elastomer(s) with said particulate reinforcement, preferably in an internal rubber mixer, wherein said coupling agent(s) has been pre-reacted with carbon black to form a carbon black composite thereof,
(2) mixing at least one of said coupling agents with said elastomer(s) and said particulate reinforcement, preferably in an internal rubber mixer, wherein said coupling agent(s) has been pre-reacted with said silica treated carbon black to form a silica treated carbon back composite thereof,
(3) mixing at least one of said coupling agents with said elastomer(s) and sa
Pyle Kevin James
Sandstrom Paul Harry
Smith Richard Robinson
Wideman Lawson Gibson
Lee Rip A
Mulcahy Peter D.
The Goodyear Tire & Rubber Company
Young, Jr. Henry C.
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