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
2000-09-08
2002-03-19
Acquah, Samuel A. (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...
C525S063000, C525S064000, C525S165000, C525S168000, C525S178000, C525S445000, C524S081000, C524S286000, C524S297000, C524S534000
Reexamination Certificate
active
06359064
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the development of high damping polymers with superior high-temperature stability, mechanical strength, and moldability. The inventive composition is particularly useful as a soft molding material for various products. The inventive composition also has an improved hysteresis value while maintaining the other superior qualities of centipede gels due to the addition of a hyperbranched polyester to the polymer composition.
BACKGROUND OF THE INVENTION
The polymerization of isobutylene and maleic anhydride and the polymerization of styrene or methyl vinyl ether and maleic anhydride may be carried out by free radical initiation. Further, imidization between a maleic anhydride and primary amine groups is known.
Two or more polymers may be blended together to form a wide variety of random or structured morphologies to obtain products that offer potentially desirable combinations of characteristics. However, it may be difficult or even impossible in practice to achieve many potential combinations through simple blending. Frequently, the polymers are thermodynamically immiscible, which precludes generating a truly homogeneous product. While it is sometimes desirable to have a two-phase structure, the situation at the interface between these two phases very often leads to problems. The typical case is one of high interfacial tension and poor adhesion between the two phases. This interfacial tension contributes, along with high viscosities, to the inherent difficulty of imparting the desired degree of dispersion to random mixtures and to their subsequent lack of stability, giving rise to gross separation or stratification during later processing or use. Poor adhesion leads, in part, to the very weak and brittle mechanical behavior often observed in dispersed blends and may render some highly structured morphologies impossible.
It is desirable to design a polymer composition which has high damping capabilities while avoiding the above-mentioned problems.
SUMMARY OF THE INVENTION
In one aspect, the present invention provides a process for forming an elastomeric polymer gel composition. The process includes combining a poly(alkenyl-co-maleimide) comprising a maleimide and at least one monomer contributed unit chosen from vinyl aromatic hydrocarbons, R
1
R
2
ethylenes, and alkyl vinyl ethers, with a maleated polyalkylene so as to form a blend. This is followed by addition of a crosslinking agent, which is allowed to react with the poly(alkenyl-co-maleimide) and maleated polyalkylene to form a polyalkenyl grafted poly(alkenyl-co-maleimide). The grafted poly(alkenyl-co-maleimide) is blended with a polyester.
In another aspect, the present invention provides an elastomeric composition. The elastomeric composition comprises a copolymer, including a maleimide and at least one monomer contributed unit chosen from the group consisting of vinyl aromatic hydrocarbons, R
1
R
2
ethylenes, and alkyl vinyl ethers, a maleated polyalkylene, a crosslinking agent, and a hyperbranched polyester.
The present invention provides a centipede polymer composition exhibiting improved properties such as hysteresis, tensile strength, maximum elongation, tear strength, damping properties, high temperature compression set, and the like. More particularly, the inventive grafted poly(alkenyl-co-maleimide) copolymers react with hyperbranched polyesters to improve the hysteresis values while maintaining the tensile strength, tear strength, damping properties, and high-temperature compression set of the centipede polymer.
The following definitions apply hereinthroughout unless a contrary intention is expressly indicated:
“Vinyl aromatic hydrocarbon” and “alkenyl benzene” are used interchangeably;
“Maleic anhydride” encompasses dicarboxylic acids, including maleic anhydride, which can form a copolymer with an alkenyl benzene, an R
1
R
2
ethylene, or an alkyl vinyl ether, the copolymer having dicarboxylic acid units which are capable of reaction with an amine functional group;
“Maleimide” encompasses the reaction product of an primary amine and the dicarboxylic acids described above;
“R
1
R
2
ethylene” as used herein encompasses monomers of the general formula:
where R
1
and R
2
are the same or different substituents on the same or different carbon atoms of the ethylene group, and are independently H or substituted or unsubstituted C
1
-C
20
alkyl groups;
Poly(alkenyl-co-maleimide) includes poly(alkenylbenzene-co-maleimide), poly(R
1
R
2
ethylene-co-maleimide), and poly(alkyl vinyl ether-co-maleimide); and
“Hyperbranched” means a highly branched polymer structure with a random morphology and high resistance to crystallization.
DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS
Preferably, the polymer compositions of the present invention include a backbone formed by copolymerization of a maleic anhydride with at least a second monomer, such as butadiene, styrene, or methyl vinyl ether. The maleic anhydride units are partially imidized with a primary amine, and the remainder are graft reacted to a maleated polyalkylene via a crosslinking agent such as a diamine. This composition is blended with a hyperbranched polyester to form an elastomeric polymer gel composition with superior damping properties.
The elastomeric polymer gel composition contains a poly(alkenyl-co-maleimide) having at least one maleated polyalkylene segment grafted thereto through at least one functional linkage formed by a cross-linking reaction with a grafting agent, at least one hyperbranched polyester additive, and, optionally, an extender.
The poly(alkenyl-co-maleimide) is a “centipede” polymer formed by imidizing a poly(alkenyl-co-maleic anhydride) with a primary amine. The centipede polymer has a high molecular weight spine connected with many relatively short side chains formed from the addition of the primary amines. The length of the main chain usually is as long or longer than the entanglement length, which is herein defined theoretically as an order of magnitude of 100 repeating units, while the length of the side chains is smaller than the entanglement length.
At least a portion of the maleic anhydride-contributed monomer units are not reacted with the primary amine, and thus remain available for coupling with a maleated polyalkylene via a crosslinking agent. These unreacted maleic anhydride-contributed monomer units preferably comprise from about 0.01 to about 5 weight percent of the copolymer.
Suitable alkenyl contributed monomer units include alkenyl benzene, R
1
R
2
ethylene, and alkyl vinyl ethers.
Preferred alkenyl benzene-contributed monomer units of the poly(alkenyl-co-maleimide) centipede are any one or combination of styrene, &agr;-methylstyrene, p-methylstyrene, 4-phenylstyrene, m-methylstyrene, p-tert-butylstyrene, dimethylstyrene, as well as alkyl, cycloalkyl, aryl, alkaryl, and aralkyl derivatives thereof, in which the total number of carbon atoms in the combined hydrocarbon is generally not greater than 12, as well as any di- or tri-vinyl aromatic hydrocarbons. Particularly preferred vinyl aromatic hydrocarbons are styrene and/or &agr;-methylstyrene.
The R
1
R
2
ethylene contributed monomer units of the centipede polymer contain 3 to about 40 carbon atoms wherein R
1
and R
2
are hydrogen or the same or different substituents on the same or different carbon atom of the ethylene group, selected from unsubstituted and substituted, linear and branched C
1
-C
20
alkyl groups, the substituted groups being non-reactive with the remaining components of the centipede polymers, such as alkoxyalkyl groups having C
1
-C
20
carbon atoms. Other acceptable substituents include —Cl, —OH, —COOH, and —CN.
The alkyl vinyl ether contributed monomer units are chosen such that the alkyl group contains about 1 to about 20 carbon atoms in the backbone and may be substituted or unsubstituted, linear or branched, along the backbone of the alkyl group. The substituted groups, such as C
2
-C
20
alkoxyalkyl groups, are non-reactive with the remaining components of the centipede polymers.
Exampl
Hall James E.
Wang Xiaorong
Bridgestone Corporation
Burleson David G.
Reginelli Arthur M.
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