Graft copolymer of syndiotactic styrene copolymer

Details Graft copolymer of syndiotactic styrene copolymer Graft copolymer of syndiotactic styrene copolymer

2000-12-29

2002-08-20

Seidleck, James J. (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...

C525S333400, C525S333500, C525S333600, C525S379000, C525S386000, C526S347000, C526S293000, C526S329200

Reexamination Certificate

active

06437051

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a graft copolymer of a syndiotactic styrene/para-alkylstyrene copolymer.
2. Description of the Prior Art
Syndiotactic polystyrene (sPS) is very useful in many commercial applications. However, it suffers from a major deficiency: poor adhesion to other materials (for example, to the copper of PC boards). In addition, sPS has poor compatibility with other functional polymers. Therefore, there is a need to improve the physical properties of the conventional syndiotactic polystyrene.
Chung et al. in U.S. Pat. No. 5,543,484 have disclosed a functionalized x-olefin/para-alkylstyrene copolymer. First, (&agr;-olefin and para-alkylstyrene are copolymerized. The incorporation of p-alkylstyrene into the &agr;-olefin polymer results in the generation of benzylic protons, which are readily available for many chemical reactions, thereby introducing functional groups at the benzylic position under mild reaction conditions. Then, the olefin/p-alkylstyrene copolymer is functionalized by the functionalization of benzylic protons in p-alkylstyrene units. Such functionalization leads to improvement in the physical properties of the original olefin polymers.
Powers et al. in U.S. Pat. No. 5,548,029 has disclosed graft copolymers of para-alkylstyrene/isoolefin. In a similar manner, isoolefin and para-alkylstyrene are copolymerized, and then the p-alkylstyrene/isoolefin copolymer is functionalized by the functionalization of benzylic protons in p-alkylstyrene units. By such functionalization, the physical properties of the isoolefin polymer can be improved.
In Powers et al., to improve compatibility of the isoolefin/p-alkylstyrene copolymer with other polymers (for example, with thermoplastic polymers), grafting technique can also be used. That is, a thermoplastic polymer moiety is grafted onto the functional copolymer. Moreover, such a graft copolymer can also serve as a compatibilizer to compatibilize polymer blends.
To date, no one has ever provided a graft copolymer of syndiotactic styrene/para-alkylstyrene copolymers.
SUMMARY OF THE INVENTION
The object of the present invention is to solve the above-mentioned problems and to provide a graft copolymer of a syndiotactic styrene/para-alkylstyrene copolymer. The compatibility of the graft copolymer of syndiotactic styrene/para-alkylstyrene copolymer of the present invention with other polymers is improved over a syndiotactic styrene polymer. Moreover, the graft copolymer of a syndiotactic styrene/para-alkylstyrene copolymer of the present invention can serve as a compatibilizer for a polymer blend so as to improve the compatibility of the polymer blend with other polymers, and increase the impact resistance and elongation of the polymer blend, while the physical properties of the original polymers in the polymer blend can still be maintained.
To achieve the above-mentioned object, the graft copolymer of a syndiotactic styrene/para-alkylstyrene copolymer of the present invention has the formula of
wherein
R
1
and R
2
are independently selected from the group consisting of hydrogen, alkyl, and primary and secondary haloalkyl,
X is a functional group selected from a group containing halogen, oxygen, sulfur, silicon, nitrogen, carbon, phosphorus, and mixtures thereof,
Y is an atactic polymer moiety,
a ranges from 10 to 30000,
b ranges from 0 to 30000,
c ranges from 0 to 30000, and
d ranges from 1 to 30000.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is the first time a graft-from copolymer of a syndiotactic styrene/para-alkylstyrene copolymer has been successfully provided.
The graft-from copolymer of a syndiotactic styrene/para-alkylstyrene copolymer has the formula of
wherein R
1
and R
2
are independently selected from the group consisting of hydrogen, alkyl, and primary and secondary haloalkyl.
X is a functional group selected from a group containing halogen, oxygen, sulfur, silicon, nitrogen, carbon, phosphorus, and mixtures thereof. Preferably, R
1
and R
2
are independently selected from the group consisting of hydrogen, C
1
to C
5
alkyl, and C
1
to C
5
primary and secondary haloalkyl.
Y is an atactic polymer moiety.
a ranges from 10 to 30000, b ranges from 0 to 30000, c ranges from 0 to 30000, and d ranges from 1 to 30000.
Preferably, the copolymer has a number average molecular weight of at least 1000.
The general process for preparing the graft copolymer of a syndiotactic styrene/para-alkylstyrene copolymer of the present invention will be described below.
The grafting techniques can be classified into “graft-from” and “graft-on”. Graft-from technique involves the reaction of a syndiotactic styrene/p-alkylstyrene copolymer and a monomer via anionic polymerization, cationic polymerization, anionic or cationic ring-open polymerization, or free radical polymerization. A “graft-from” anionic polymerization is as follows:
The reaction of a functionalized (such as brominated) syndiotactic styrene/p-alkylstyrene with a monomer via cationic polymerization is as follows:
The reaction of a functionalized (such as brominated) syndiotactic styrene/p-alkylstyrene with a monomer via free radical polymerization is as follows:
The “graft-on” technique involves the reaction of a functionalized syndiotactic styrene/p-alkylstyrene copolymer and a polymer which can react with the functional group of such a functionalized syndiotactic styrene/p-alkylstyrene copolymer, such that the polymer bonds to the functionalized syndiotactic styrene/p-alkylstyrene copolymer and grafting is achieved.
Therefore, Y in formula (I) is selected from the group consisting of polymers and copolymers of anionically polymerizable monomers, cationically polymerizable monomers, anionically and cationically ring-openable monomers, and free radical polymerizable monomers.
Representative examples of the anionically polymerizable monomers include conjugated dienes, vinyl aromatic compounds, vinyl unsaturated amides, acenaphthylene, 9-acrylcarbazole, acrylonitrile, methacrylonitrile, organic isocyanates, acrylates, methacrylates, alkyl acrylates, alkyl methacrylates, glycidyl methacrylates, vinyl pyridines, and mixtures thereof.
Representative examples of the cationically polymerizable monomers include vinyl aromatic compounds, vinyl ethers, N-vinylcarbazole, isobutene, and mixtures thereof.
Representative examples of the ring-openable monomers include cyclic ethers, sulfides, lactones, lactams, N-carboxyanhydrides, cyclic anhydrides, and mixtures thereof.
Representative examples of the free radical polymerizable monomers include vinyl aromatic compounds, conjugated dienes, acrylates, methacrylates, alkyl acrylates, alkyl methacrylates, vinyl acetates, and mixtures thereof.
As a result, after further grafting (e.g., graft-from or graft-on), the syndiotactic styrene/para-alkylstryene copolymer of the present invention has a grafted side chain (Y) that is an atactic polymer, rather than a syndiotatic polymer.
The general process for preparing the functionalized syndiotactic styrene/para-alkylstyrene copolymer of the present invention will be described below.
We take the reaction of styrene and para-methylstyrene monomers as an example. First, the two monomers are copolymerized by using a metallocene as a catalyst. The catalyst system may also include an activating cocatalyst such as methyl aluminoxane (MAO).
wherein each x and y is the molar ratio of the respective monomer and x+y=100.
Suitable metallocene catalysts have a delocalized &pgr;-bonded moiety with a constrained geometry. The catalysts may be further described as a metal coordination complex comprising a metal of Groups IVB-VIB of the Periodic Table of the elements and a delocalized &pgr;-bonded moiety with a constrained geometry. Some of them have been taught in U.S. Pat. Nos. 4,542,199; 4,530,914; 4,665,047; 4,752,597; 5,026,798; and 5,272,236. Preferred catalyst complexes include zirconocene and titanocene coordination compounds with single or double cyclopentadienyl derivatives which form the constrained

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