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
2001-12-18
2004-01-27
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...
59, 59
Reexamination Certificate
active
06683134
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an amorphous polyolefin resin composition having good transparency and impact resistance, and more particularly to an amorphous polyolefin resin composition containing a core-shell elastomer which is effective for improving the impact resistance of the amorphous polyolefin with minimum loss of the transparency of the amorphous polyolefin.
BACKGROUND ART
Cyclic olefin polymers (including copolymers) which are one type of amorphous polyolefins, have lately attracted attention as plastics having excellent moldability, dimensional stability, transparency and moisture barrier. However, the impact strength thereof is not sufficient and, therefore, improvement in impact resistance has been conventionally investigated. It has been demanded to improve the impact resistance of cyclic olefin polymers with maintaining an excellent transparency that the cyclic olefin polymers possess.
It is generally known that alloying brittle thermoplastic resins with rubber components incompatible therewith enhances the impact resistance. This manner is also effective for cyclic olefin polymers. For example, JP-A-7-233301, JP-A-7-233302 and JP-A-7-300540 disclose improving the impact resistance of amorphous polyolefins by incorporating core-shell elastomers therein.
JP-A-7-233301 and JP-A-7-233302 disclose that core-shell elastomers are effective for improving the impact resistance of cyclic olefin polymers which are one type of amorphous polyolefins. However, it cannot be said that the degree of improvement in impact resistance and the level of transparency are sufficient. No countermeasure to further improve them is disclosed therein.
JP-A-7-300540 discloses that core-shell elastomers wherein the graft layer (shell layer) is formed by graft polymerization of cycloalkyl (meth)acrylates, are effective for improving the impact resistance of cyclic olefin copolymers. However, since cycloalkyl (meth)acrylates are industrially special monomers and are also very low in solubility in water, emulsion polymerization or seed polymerization which has been generally used in industrial production of core-shell elastomers is hard to apply to the cycloalkyl (meth)acrylates as a satisfactory, simple and easy method.
An object of the present invention is to provide an amorphous polyolefin resin composition having an improved impact resistance without remarkably deteriorating excellent transparency of the amorphous polyolefin resins.
A further object of the present invention is to provide a core-shell graft copolymer which can be prepared by a general polymerization method with the use of easily available raw materials and which is suitable for improvement in impact resistance of amorphous polyolefins.
DISCLOSURE OF INVENTION
The present inventors have found that core-shell elastomers useful for improvement in impact resistance of amorphous polyolefins are obtained without using any industrially special cycloalkyl (meth)acrylates by graft-polymerizing a monomer mixture containing an easily available linear or branched alkyl (meth)acrylate and an aromatic vinyl monomer onto a conjugated diene copolymer rubber.
Thus, in accordance with the present invention, there is provided an amorphous polyolefin resin composition comprising (A) 1 to 40% by weight of a core-shell elastomer and (B) 99 to 60% by weight of an amorphous polyolefin, wherein said core-shell elastomer (A) is a core-shell elastomer prepared by graft polymerization of a graft component (A-2) in the presence of a copolymer rubber (A-1) of not less than 50% by weight of a conjugated diene monomer and not more than 50% by weight of at least one vinyl monomer copolymerizable therewith, in which said graft component (A-2) is a mixture of 1 to 99% by weight of at least one aromatic vinyl monomer and 99 to 1% by weight of a monomer mixture of (Ml) a linear and/or branched alkyl (meth)acrylate with a C
3
to C
8
alkyl group and (M2) at least one monomer selected from the group consisting of alkyl (meth)acrylates with an alkyl group having 2 or less carbon atom and vinyl cyanide monomers in an M1/M2 ratio of 99/1 to 30/70 by weight.
The core-shell elastomer in the present invention is preferably a core-shell elastomer having a shell layer of a multilayer structure from the viewpoint of balance between transparency and impact resistance.
Thus, in accordance with a preferable embodiment of the present invention, there is provided an amorphous polyolefin resin composition comprising (A) 1 to 40% by weight of a core-shell elastomer and (B) 99 to 60% by weight of an amorphous polyolefin, wherein said core-shell elastomer (A) is a core-shell elastomer (A′) having a multilayer structure prepared by graft-polymerizing either of graft component (A-2) and graft component (A-2′) and then the other in the presence of a copolymer rubber (A-1) of not less than 50% by weight of a conjugated diene monomer and not more than 50% by weight of at least one vinyl monomer copolymerizable therewith, in which said graft component (A-2) is a mixture of 1 to 99% by weight of at least one aromatic vinyl monomer and 99 to 1% by weight of a monomer mixture of (M 1) a linear and/or branched alkyl (meth)acrylate with a C
3
to C
8
alkyl group and (M2) at least one monomer selected from the group consisting of alkyl (meth)acrylates with an alkyl group having 2 or less carbon atom and vinyl cyanide monomers in an M1/M2 ratio of 99/1 to 30/70 by weight, and said graft component (A-2′) is a mixture of 0 to 100% by weight of a linear and/or branched alkyl (meth)acrylate with a C
3
to C
8
alkyl group (M 1), 0 to 50% by weight of at least one monomer (M2) selected from the group consisting of alkyl (meth)acrylates with an alkyl group having 2 or less carbon atom and vinyl cyanide monomers, and 50 to 100% by weight of an aromatic vinyl monomer.
As the copolymer rubber (A-1) which constitutes the core are used, for example, styrene-butadiene rubber, styrene-butadiene-isoprene rubber and the like. The core of the core-shell elastomer in the present invention is able to have a multilayer structure. Copolymer rubbers (A-1) having a multilayer structure which are obtained by radical polymerization of a monomer component comprising 50 to 100% by weight a conjugated diene monomer and 50 to 0% by weight of at least one vinyl monomer copolymerizable with the diene monomer in the presence of a copolymer rubber of a conjugated diene monomer and at least one vinyl monomer copolymerizable with the diene monomer, are preferably used as the core from the viewpoint of the transparency and/or the impact resistance. The multilayer structure copolymer rubbers having an average particle size of 0.05 to 0.30 &mgr;m are particularly preferred.
The core-shell elastomers of the present invention are applicable to amorphous polyolefins and, in particular, are suitable for improvement in impact resistance of cyclic olefin homopolymers and copolymers such as cyclic olefin addition copolymers composed of &agr;-olefin and cyclic olefin, cyclic olefin addition copolymers composed of ethylene, cyclic olefin and &agr;-olefin, and hydrogenation products of homopolymers and copolymers by ring-opening polymerization of cyclic olefins.
BEST MODE FOR CARRYING OUT THE INVENTION
Core-Shell Elastomer (A)
The core-shell elastomer (A) is composed of a core and a shell layer which covers a part or whole of the surface of the core. Core-shell elastomers may be used alone or in admixture thereof as the component (A) so long as they satisfy the requirements of the present invention.
The core is made of a copolymer rubber (A-1) of at least 50% by weight, preferably 70 to 90% by weight, more preferably 80 to 88% by weight, of a conjugated diene monomer and at most 50% by weight of at least one vinyl monomer copolymerizable with the diene monomer. If the proportion of the conjugated diene monomer in the copolymer rubber (A-1) which constitutes the core is low, the effect of improving the impact resistance of amorphous polyolefins tends to be not sufficient.
The copolymer rubber (A-1) c
Kadokura Mamoru
Kawai Hideki
Miyamoto Masahiro
Asinovsky Olga
Kaneka Corporation
Seidleck James J.
Westerman Hattori Daniels & Adrian LLP
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