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
2002-10-03
2004-04-06
Nutter, Nathan M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S221000, C525S222000, C525S232000, C525S241000
Reexamination Certificate
active
06716925
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a tire having at least one component of a rubber composition comprised of two distinctly different rubbers. The first rubber is a terpolymer rubber which contains pendant hydroxyl groups and is derived from a diene hydrocarbon, vinyl aromatic compound monomers and a hydroxyl containing a co-monomer. The second rubber contains a nitrile moiety.
BACKGROUND OF THE INVENTION
Vehicular tires, particularly pneumatic tires, are sometimes provided with a component such as, for example, a tread which is comprised of a rubber composition which contains two or more rubbers or elastomers.
Elastomer blends which contain, for example, cis 1,4-polybutadiene and styrene/butadiene elastomers are often used for such tire component (e.g. tire tread). Rubber compositions may also contain various amounts of additional diene-based elastomers such as, for example, one or more of cis 1,4-polyisoprene, cis 1,4-polybutadiene, medium vinyl polybutadiene, styrene/butadiene copolymers, isoprene/butadiene copolymers, and minor amounts of 3,4-polyisoprene.
For the above mentioned styrene/butadiene copolymer rubber, both emulsion polymerization prepared and organic solvent polymerization prepared styrene/butadiene copolymer elastomers have been used. Also, historically, emulsion polymerization derived terpolymer elastomers comprised of units derived from styrene and 1,3-butadiene together with an additional monomer have been prepared and proposed for use for various products.
U.S. Pat. No. 5,902,852 discloses the modification of an asphalt cement with a rubbery terpolymer prepared by emulsion polymerization which is comprised of repeat units derived from conjugated diolefin monomer, such as, for example, cis 1,4-polybutadiene, vinyl aromatic monomer such as styrene and a small amount of hydroxypropyl methacrylate (HPMA).
U.S. Pat. No. 6,057,937 discloses use of a terpolymer of cis 1,4-polybutadiene, styrene and, for example hydroxypropyl methacrylate in rubber compositions.
Hydroxy-containing polymers are disclosed in U.S. Pat. Nos. 4,150,014, 4,150,015, 4,152,308 and 4,357,432.
SUMMARY AND PRACTICE OF THE INVENTION
The present invention relates to a rubber composition which is particularly suited for use in a tire. The composition is characterized by containing two very dissimilar rubbers. The first rubber is a terpolymer having a pendant hydroxyl group. The second rubber contains a nitrile moiety.
DETAILED DESCRIPTION OF THE INVENTION
There is disclosed a rubber composition comprising, based on 100 parts by weight (phr) of rubber
(A) from 10 to 90 phr of a terpolymer rubber comprised of repeat units derived from
(1) 30 to 89 weight percent of a conjugated diene monomer which contains from 4 to 8 carbon atoms;
(2) 10 to 50 weight percent of a vinyl substituted aromatic monomer; and
(3) 1 to 20 weight percent of at least one co-monomer selected from the group consisting of the following general formulas I, II, and III:
wherein R represents a hydrogen atom or an alkyl group containing from 1 to 8 carbon atoms;
wherein R
1
represents a saturated alcohol group containing from 1 to 8 carbon atoms;
(B) 10 to 90 phr of a rubber comprised of repeat units derived from
(1) 30 to 99 weight percent of a conjugated diene monomer which contains from 4 to 8 carbon atoms;
(2) zero to 50 weight percent of a vinyl substituted aromatic monomer; and
(3) 1 to 20 weight percent of an olefinic unsaturated nitrile selected from the group consisting of acrylonitrile, methacrylonitrile, ethacrylonitrile, crotononitrile and mixtures thereof.
In addition, there is disclosed a tire having a component comprising, based on 100 parts by weight (phr) of rubber
(A) from 10 to 90 phr of a terpolymer rubber comprised of repeat units derived from
(1) 30 to 89 weight percent of a conjugated diene monomer which contains from 4 to 8 carbon atoms;
(2) 10 to 50 weight percent of a vinyl substituted aromatic monomer; and
(3) 1 to 20 weight percent of at least one co-monomer selected from the group consisting of the following general formulas I, II, and III:
wherein R represents a hydrogen atom or an alkyl group containing from 1 to 8 carbon atoms;
wherein R
1
represents a saturated alcohol group containing from 1 to 8 carbon atoms;
(B) from 10 to 90 phr of a rubber comprised of repeat units derived from
(1) 30 to 99 weight percent of a conjugated diene monomer which contains from 4 to 8 carbon atoms;
(2) zero to 50 weight percent of a vinyl substituted aromatic monomer; and
(3) 1 to 20 weight percent of an olefinic unsaturated nitrile selected from the group consisting of acrylonitrile, methacrylonitrile, ethacrylonitrile, crotononitrile and mixtures thereof.
In the description of this invention, the terms “rubber” and “elastomer” when used herein, are 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.
The term “phr” if used herein, and according to conventional practice, refers to “parts of a respective material per 100 parts by weight of rubber, or elastomer”.
The Tg of an elastomer, if referred to herein, refers to a “glass transition temperature” of the elastomer which can conveniently be determined by a differential scanning calorimeter at a heating rate of 10° C. per minute.
The first critical ingredient in the rubber composition is the terpolymer rubber derived from the conjugated diene monomer, vinyl substituted aromatic monomer and hydroxyl containing co-monomer. The terpolymer will comprise from 10 to 90 phr of the total 100 parts by weight of rubber in the composition. Preferably, from 25 to 75 phr will be the terpolymer.
Representative examples of conjugated diene monomers which may be used include 1,3-butadiene, isoprene, 1,3-ethylbutadiene, 1,3-pentadiene, 1,3-hexadiene, 1,3-cyclooctadiene, 1,3-octadiene and mixtures thereof. Preferably, the conjugated diene is 1,3-butadiene. The terpolymer will contain repeat units derived from 30 to 89 weight percent of the conjugated diene. Preferably, from 50 to 80 weight percent of the terpolymer will be derived from the conjugated diene.
The terpolymer is also derived from a vinyl substituted aromatic monomer. The vinyl-substituted aromatic compound may contain from 8 to 16 carbon atoms. Representative examples of vinyl substituted aromatic monomers are styrene, alpha methyl styrene, vinyl toluene, 3-methyl styrene, 4-methyl styrene, 4-cyclohexylstyrene, 4-para-tolylstyrene, para-chlorostyrene, 4-tert-butyl styrene, 1-vinylnaphthalene, 2-vinylnaphthalene and mixtures thereof. Preferably, styrene is used. The terpolymer will contain repeat units derived from 10 to 50 weight percent of the vinyl substituted aromatic monomer. Preferably, from 20 to 40 weight percent of the terpolymer is derived from a vinyl substituted aromatic monomer.
The terpolymer is also derived from a hydroxyl containing monomer. One to 20 weight percent of the terpolymer is derived from the hydroxy containing monomers. Preferably, from 1 to 5 weight percent of the terpolymer is derived from these monomers. The hydroxyl containing co-monomer may be a hydroxyl alkyl acrylate of formula I or a hydroxy alkyl acrylamide of formula II and/or III, as seen below.
wherein R represents a hydrogen atom or an alkyl group containing from 1 to 8 carbon atoms. Preferably, R is a hydrogen atom or an alkyl group having from 1 to 4 carbon atoms. R
1
is a saturated alcohol group containing from 1 to 8 carbon atoms. Preferably, R
1
has from 1 to 4 carbon atoms. The saturated alcohol group may be a primary, secondary or tertiary alcohol group.
The hydroxy alkyl acrylate co-monomer of structural formula I may be hydroxymethyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate (HPMA isomer), 3-hydroxypropyl methacrylate (HPMA isomer), 3-phenoxy-2-hydroxypropyl methacryl
Jacoby Claude Charles
Kaes Christian
Thielen Georges Marcel Victor
Westermann Stephan Franz
DeLong John D.
Hendricks Bruce J.
Nutter Nathan M.
The Goodyear Tire & Rubber Company
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