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
2000-06-05
2002-05-07
Sellers, Robert E. L. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C523S436000
Reexamination Certificate
active
06384134
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the development of high damping polymers with superior adhesion properties, high-temperature stability, mechanical strength and moldability.
BACKGROUND OF THE INVENTION
The polymerization of isobutylene and maleic anhydride is known, as is the polymerization of styrene and maleic anhydride, and alkyl vinyl ethers and maleic anhydride. These polymerization techniques are carried out by free radical initiation. Further, imidization between a maleic anhydride and a primary amine group is a commonly known chemical reaction. It has long been recognized that two or more polymers may be blended together to form a wide variety of random or structured morphologies to obtain products that potentially offer desirable combinations of characteristics. However, it may be difficult or even impossible in practice to achieve many potential combinations through simple blending because of some inherent and fundamental problem. Frequently, the two polymers are thermodynamically immiscible, which precludes generating a truly homogeneous product. While immiscibility may not be a problem since it may be desirable to have a two-phase structure, the situation at the interface between these two phases very often does lead 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.
SUMMARY OF THE INVENTION
The present invention is a polymer gel composition comprising a polymer including an anhydride unit and an alkenyl unit; a crosslinking agent; a maleated polyalkylene; an extender; and an epoxy.
According to one embodiment of this invention, a blend of a maleated polyalkylene and a poly(alkenyl-co-maleimide) and an epoxy polymer that is useful in producing high damping and soft materials with good adhesion properties is provided. The polymer gel can be formed by reacting the polymeric constituents with a grafting agent, followed by mixture with an epoxy polymer.
It is an advantage of the invention to produce a polymer composition that exhibits improved properties such as tensile strength, maximum elongation, tear strength, damping properties, high temperature stability, good adhesion, and the like, with emphasis on good adhesion. More particularly, the present inventive grafted polymer compositions combine with an epoxy polymer to improve the tensile strength, tear strength, damping properties, high-temperature compression set, and adhesion of the centipede polymer.
DETAILED DESCRIPTION OF THE INVENTION
The polymer gel composition of the present invention contains: 0.5-200 parts by weight of a grafted polymer of a poly(alkenyl-co-maleimide) having at least one maleated polyalkylene segment grafted thereto through the at least one functional linkage formed by a cross-linking reaction with a diamine grafted agent; and 0 to 1000 parts by weight of a hyperbranched epoxy polymer. It is understood that the general term poly(alkenyl-co-maleimide) is an inclusive term which includes poly(alkenylbenzne-co-maleimide), poly(R
1
R
2
ethylene-co-maleimide), and poly(alkylvinyl ether-co-maleimide).
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 usally equals or is 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.
The preferred alkenyl monomer units of the poly(alkenylbenzne-co-maleimide) “centipede” are any one or combination of styrene, &agr;-methyl styrene, 1-vinyinaphthalene, 2-vinylnaphthalene, 1-&agr;-methyl-vinyinaphthalene, 2-&agr;-methyl vinylnaphthalene, 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. The preferred vinyl aromatic hydrocarbons are either styrene or &agr;-methylstyrene. The terms “alkenyl benzene” and “vinyl aromatic” are understood to be interchangeable as used herein.
The preferred R
1
R
2
ethylene contributed monomer units of the poly(R
1
R
2
ethylene-co-maleimide) are any alkene such as ethylene, propylene, butylene, isobutylene, pentene, hexene, heptene, etc., as well as any di- or tri- alkene, with preference given to isobutylene.
The preferred alkyl vinyl ether contributed monomer units of the poly(alkylvinyl ether-co-maleimide) are any alkylvinyl ether such as methylvinyl ether, ethylvinyl ether, propylvinyl ether, butylvinyl ether, and any other alkyl vinyl ether wherein the number of carbons in the alkyl substituent is not greater than about 12.
The poly(alkenyl-co-maleimides) described herein are subsequently graft-reacted through a difunctional linking or grafting agent to a maleated polyalkylene to yield a maleated polymer having at least one polyalkylene segment grafted thereto through at least one functional linkage thus formed. The alkylene moiety of the polyalkylene is selected from the group consisting of ethylene, propylene, and mixtures thereof The preferred polyalkylene is polypropylene.
The maleated polypropylene may be any of the conventionally known polypropylene compounds that are subsequently maleated by methods known in the art. The polypropylene grafted segment or segments have molecular weights M
W
of about 10,000 up to about 10,000,000, or higher, preferably about 20,000 to about 300,000.
The crystallinity, or tacticity, of the polypropylene may vary from being substantially amorphous to being completely crystalline, that is from about 10-100% crystallinity. Most typically, because of the extensive commercial use of isotactic polypropylene, the grafted polypropylene will be substantially crystalline, e.g., greater than about 90%. Generally, the polypropylene is substantially free of ethylene. However, under certain circumstances small amounts of ethylene, on the order of less than about 10% by weight, may be incorporated. Furthermore, in certain instances the polypropylene contains small amounts of ethylene in copolymers known as “reactor copolymers.” Thus, it is within the scope of the invention that the grafted polypropylenes contain minor amounts of ethylene, both as part of the ethylene-propylene segments and as polyethylene segments.
The maleated polypropylene of this invention contains from about 0.01 wt. % incorporated maleic anhydride, based upon the weight of the maleated polypropylene, up to about 5 wt. %. Preferably the maleic anhydride content will be from about 0.01 to about 2 wt. %, most preferably about 0.03 to about 0.2 wt. %. As will be apparent, unreacted polypropylene will also be present in the reaction mix as will minor amounts of reaction by-products, such as decomposed free-radical initiator compounds and low molecular weight free-radical products. These by-products are substantially removed, by methods known in the art, e.g., sparging with nitrogen or washing with water. Maleic anhydride may not be left in substantial amounts in the polymer without detrimental effects on the subsequent reaction of the poly(alkenyl-co-maleimide) with the maleated polyalkylene.
The poly(alkenyl-co-maleimide) of the present invention is formed by reacting a poly(alkenyl-co-maleic anhydride) in the presence of a mono-primary amine at temperatures from about 100° C. to about 300° C. and at a pressure from
Hall James E.
Wang Xiaorong
Bridgestone Corporation
Burleson David G.
McCollister Scott A.
Sellers Robert E. L.
LandOfFree
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