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
1999-12-02
2001-12-04
Henderson, Christopher (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...
C525S332700
Reexamination Certificate
active
06326438
ABSTRACT:
BACKGROUND OF THE INVENTION
U.S. Pat. No. 3,979,369 relates to a method for cross-linking rubber with polysulfides. Included in the hundreds of polysulfides listed in this reference are bis benzothiazolyldithio end capped compounds.
Use of the described bis-benzothiazolyldithio end capped compounds does not yield the desirable anti-reversion properties and reduced heat rise that is sought related to the current invention.
PCT application number PCT/EP94/018 (WO 94/29380 discloses a rubber composition containing citraconimides and itaconimides as anti-reversion coagents.
SUMMARY OF THE INVENTION
The present invention relates to a rubber composition containing the combination of:
(a) a bismaleimide and
(b) a bis benzothiazolyldithio compound of the formula:
wherein R
1
is selected from the group consisting of alkylene radicals having from 1 to 20 carbon atoms, cycloalkylene radicals having from 6 to 24 carbon atoms and arylene radicals having from 6 to 18 carbon atoms, alkarylene radicals having from 7 to 25 carbon atoms and divalent radicals of the formula:
&Parenopenst;R
1
&Parenclosest;O&Parenopenst;R
1
&Parenclosest;.
DETAILED DESCRIPTION OF THE INVENTION
There is disclosed a sulfur vulcanizable rubber composition comprising:
(a) a rubber selected from the group consisting of natural rubber, a rubber derived from a diene monomer and mixture thereof;
(b) from about 0.1 to about 10 phr of a bismaleimide compound of the general formula:
wherein R is divalent and is selected from the group consisting of acyclic aliphatic groups having from about 2 to 16 carbon atoms, cyclic aliphatic groups having from about 5 to 20 carbon atoms, aromatic groups having from about 6 to 18 carbon atoms, and alkylaromatic groups having from about 7 to 24 carbon atoms, wherein these divalent groups may contain a hetero atom selected from O, N and S; X is 0 or an integer of from 1 to 3 and Y is hydrogen or —CH
3
; and
(c) from about 0.1 phr to about 10 phr of a bis benzothiazolyldithio compound of the general formula:
where R
1
is selected from the group consisting of alkylene radicals having from 1 to 20 carbon atoms, cycloalkylene radicals having from 6 to 24 carbon atoms and arylene radicals having from 6 to 18 carbon atoms, alkarylene radicals having from 7 to 25 carbon atoms and divalent radicals of the formula:
&Parenopenst;R
1
&Parenclosest;O&Parenopenst;R
1
&Parenclosest;.
The bismaleimide is an essential component in the claimed invention. The bismaleimide is generally present in an amount of from about 0.1 to 10 phr. Preferably, the bismaleimide is present in an amount ranging from about 0.5 to about 5 phr.
Representative of the bismaleimides of formula I and which may be used in the present invention include N,N′-ethylenebismaleimide, N,N′-hexamethylenebismaleimide, N,N′-dodecamethylenebismaleimide, N,N′-(2,2,4-trimethylhexamethylene)bismaleimide, N,N′-(oxydipropylene)bismaleimide, N,N′-(aminodipropylene)bismaleimide, N,N′-(ethylenedioxydipropylene)-bismaleimide, N,N′(1,4-cyclohexylene)bismaleimide, N,N′-(1,3-cyclohexylene)bismaleimide, N,N′-(methylene-1,4-dicyclohexylene)bismaleimide, N,N′-(isopropylidene-1,4-dicyclohexylene)bismaleimide, N,N′-(oxy-1,4-dicyclohexylene)bismaleimide, N,N′-(m-phenylene)bismaleimide, N,N′-p-(phenylene)bismaleimide, N,N′-(o-phenylene)bismaleimide, N,N′-(1,3-naphthylene)bismaleimide, N,N′-(1,4-naphthylene)bismaleimide, N,N′-(1,5-naphthylene)bismaleimide, N,N-(3,3′-dimethyl-4,4′-diphenylene)bismaleimide, N,N′-(3,3-dichloro-4,4′-biphenylene)bismaleimide, N,N′-(2,4-pyridyl)bismaleimide, N,N′-(2,6-pyridyl)bismaleimide, N,N′-(m-tolylene)bismaleimide, N,N′-(p-tolylene)bismaleimide, N,N′-(4,6-dimethyl-1,3-phenylene)bismaleimide, N,N′-(2,3-dimethyl-1,4-phenylene)bismaleimide, N,N′-(4,6-dichloro-1,3-phenylene)bismaleimide, N,N′-(5-chloro-1,3-phenylene)bismaleimide, N,N′-(5-hydroxy-1,3-phenylene)bismaleimide, N,N′-(5-methoxy-1,3-phenylene)bismaleimide, N,N′-(m-xylylene)bismaleimide, N,N′-(p-xylylene)bismaleimide, N,N′-(methylenedi-p-phenylene)bismaleimide, N,N′-(isopropylidenedi-p-phenylene)bismaleimide, N,N′-(oxydi-p-phenylene)bismaleimide, N,N′-(thiodi-p-phenylene)bismaleimide, N,N′-(dithiodi-p-phenylene)bismaleimide, N,N′-(sulfodi-p-phenylene)bismaleimide, N,N′-(carbonyldi-p-phenylene)bismaleimide, &agr;,&agr;-bis-(4-maleimidophenyl)-meta-diisopropylbenzene, &agr;,&agr;-bis-(4-p-phenylene) bismaleimide, N,N′-(m-xylylene)bis-citraconimide and &agr;,&agr;-bis-(4-maleimidophenyl)-para-diisopropylbenzene. The preferred bismaleimide is N,N′-(m-xylylene)bis-citraconimide.
The other essential feature of the present invention is the presence of a bis benzothiazolyldithio compound of the formula:
wherein R
1
is selected from the group consisting of alkylene radicals having from 1 to 20 carbon atoms, cycloalkylene radicals having from 6 to 24 carbon atoms and arylene radicals having from 6 to 18 carbon atoms, alkarylene radicals having from 7 to 25 carbon atoms and divalent radicals of the formula:
&Parenopenst;R
1
&Parenclosest;O&Parenopenst;R
1
&Parenclosest;.
Preferably, R
1
is an alkylene radical having 6 carbon atoms.
The bis benzothiazolyldithio compound is generally present in an amount ranging from about 0.1 to 10 phr. Preferably, such compound is present in an amount ranging from about 0.5 to 5 phr.
Representative compounds of formula II include 1,1-bis(2-benzothiazolyldithio)methane; 1,2-bis(2-benzothiazolyldithio)ethane; 1,3-bis(2-benzothiazolyldithio)propane; 1,4-bis(2-benzothiazolyldithio)butane; 1,6-bis(2-benzothiazolyldithio)hexane; 1,8-bis(2-benzothiazolyldithio)octane; 1,10-bis(2-benzothiazolyldithio)decane; 1,10-bis(2-benzothiazolyldithio)octadecane; 1,18-bis(2-benzothiazolyldithio)octadecane; 2,2′-bis(2-benzothiazolyldithio)oxydiethane; 2,2′-bis(2-benzothiazolyldithio)thiodiethane; 4,4′-bis(2-benzothiazolyldithio)oxydibutane; 1,1-bis(2-benzothiazolyldithio)-1,4-cyclohexanedimethane; 1,4-bis(2-benzothiazolyldithio)benzene; &agr;,&agr;′-bis(2-benzothiazolyldithio)p-xylene; 1,2-bis(2-benzothiazolyldithio)cyclohexane; 1,1-bis(2-benzothiazolyldithio)cyclohexane; 1,4-bis(2-benzothiazolyldithio)cyclohexane; 1,4-bis(2-benzothiazolyldithio)naphthalene; 4,4′-bis(2-benzothiazolyldithio)biphenyl; 4,4′-bis(2-benzothiazolyldithio)oxybisbenzene and mixtures thereof.
Examples of rubbers for use in the present invention include substituted and unsubstituted, saturated and unsaturated, natural and synthetic polymers. The natural polymers include natural rubber in its various forms, e.g., pale crepe and smoked sheet, and balata and gutta percha. The synthetic polymers are derived from a diene monomer and include those prepared from a single monomer (homopolymer) or a mixture of two or more copolymerizable monomers (copolymer) when the monomers are combined in the random distribution or block form. The monomers may be substituted or unsubstituted and may possess one or more double bonds, conjugated and nonconjugated dienes and monoolefins, including cyclic and acyclic monoolefins, especially vinyl and vinylidene monomers. Examples of conjugated dienes are 1,3-butadiene, isoprene, chloroprene, 2-ethyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene and piperylene. Examples of nonconjugated dienes are 1,4-pentadiene, 1,4-hexadiene, 1,5-hexadiene, dicyclopentadiene, 1,5-cyclooctadiene, and ethyldiene norbornene. Examples of acyclic monoolefins are ethylene, propylene, 1-butene, isobutylene, 1-pentene and 1-hexene. Examples of cyclic monoolefins are cyclopentene, cyclohexene, cycloheptene, cyclooctene and 4-methyl-cyclooctene. Examples of vinyl monomers are styrene, acrylonitrile, acrylic acid, ethylacrylate, vinyl chloride, butylacrylate, methyl vinyl ether, vinyl acetate and vinyl pyridine. Examples of vinylidene monomers are alpha-methylstyrene, methacrylic acid, methyl
D'Sidocky Richard Michael
Maly Neil Arthur
Wideman Lawson Gibson
Henderson Christopher
Hendricks Bruce J.
The Goodyear Tire & Rubber Company
LandOfFree
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