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
2002-12-27
2004-11-02
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...
C525S098000, C525S303000, C525S308000, C525S902000, C523S201000, C524S504000
Reexamination Certificate
active
06812284
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to amorphous polyester resin compositions. More particularly, it relates to novel amorphous polyester resin compositions which contain core-shell impact resistance improving agents and have excellent transparency and impact resistance.
BACKGROUND ART
Because being excellent in transparency, mechanical properties and gas barrier properties, amorphous polyester resin compositions have been widely employed mainly in packaging materials such as bottles and sheets. With the recent tendency toward large-sized containers in complicated shapes, it has been required to elevate the impact resistance of these compositions. To improve the impact resistance of polyester resin compositions, attempts have been made to add fibrous inorganic fillers, thereby achieving certain effects of improving the impact resistance. Also, attempts have been frequently made to add rubbery polymers and rubber-containing polymers to polyester resin compositions to improve the impact resistance. In particular, it is known that core-shell impact resistance improving agents having rubbery polymer particles enclosed in a glassy polymer are effective in improving impact resistance. In case of adding these fibrous inorganic fillers or core-shell impact resistance improving agents to amorphous polyester resin compositions, the impact resistance can be effectively improved. In such a case, however, the transparency of the amorphous polyester resin compositions is seriously damaged. Namely, excellent impact resistance and high transparency can be hardly achieved at the same time.
In case of adding these fibrous inorganic fillers or core-shell impact resistance improving agents to amorphous polyester resin compositions, the impact resistance can be effectively improved. In such a case, however, the transparency of the amorphous polyester resin compositions is seriously damaged. Namely, excellent impact resistance and high transparency can be hardly achieved at the same time and thus no satisfactory result can be established so far.
Japanese Patent No. 2,079,959 discloses core-shell polymers which have a core carrying epoxy group on its surface and a shell free from epoxy group or any functional group reactive with the epoxy group located on the core as improving agents for crystalline polyalkylene terephthalates such as poly (butylene terephthalate). However, this document neither discloses nor suggests any effective method of maintaining a high transparency in amorphous polyester resin compositions.
U.S. Pat. No. 5,321,056 discloses blends of impact resistance improving agents capable of imparting a high transparency and a high notched Izod impact resistance with amorphous aromatic polyesters. The impact resistance improving agents disclosed therein are core-shell polymers having a core mainly containing rubbery polymers of diolefin and aromatic vinyl monomers and a shell mainly containing aromatic vinyl monomers and monomers having hydroxyl group. Although the impact resistance can be surely improved by introducing the monomers having hydroxyl group into the core, the improving effect is not so high and the optical transparency is still insufficient. In such a case, moreover, a high viscosity is observed at the melt-blending step, which brings about a problem in molding properties.
As impact resistance improving agents for amorphous aromatic polyesters, Japanese Patent Laid-Open No. 34327/2000 discloses core-shell polymers having a core mainly containing rubbery polymers of diolefin and aromatic vinyl monomers, an intermediate stage mainly containing aromatic vinyl monomers, and a shell mainly containing hydroxyalkyl (meth)acrylate monomers and aromatic vinyl monomers. Although the impact resistance can be improved by introducing monomers having hydroxyl group into the outer layer of the shell, the improving effect is not so high and the optical transparency is still insufficient. Although these improving agents disclosed in Japanese Patent Laid-Open No. 34327/2000 impart a significantly improved impact resistance to transparent and amorphous aromatic polyesters, improving agents capable of imparting well-balanced impact resistance and optical transparency are still needed.
DISCLOSURE OF THE INVENTION
The invention aims at providing amorphous polyester resin compositions which are excellent in both of transparency and impact resistance.
To solve these problems, the present inventors have conducted intensive studies. As a result, they have found out core-shell impact resistance improving agents having a core made of a butadiene-based copolymer and an inner layer shell containing hydroxy or alkoxy group.
Accordingly, the invention relates to:
1. a core-shell impact resistance improving agent which comprises: (A) from 40 to 90 parts by weight of a core made of a butadiene-based copolymer obtained by polymerizing a monomer mixture containing from 30 to 100% by weight of a butadiene monomer, from 0 to 70% by weight of an aromatic vinyl monomer, from 0 to 10% by weight of a copolymerizable vinyl monomer and from 0 to 5% by weight of a crosslinkable monomer; (B) from 5 to 40 parts by weight of an inner layer shell obtained by polymerizing a monomer mixture containing from 60 to 98% by weight of an aromatic vinyl monomer, from 2 to 40% by weight of a (meth)acrylate monomer having hydroxyl or alkoxy group and from 0 to 20% by weight of a copolymerizable vinyl monomer; and (C) 5 to 20 parts by weight of an outer layer shell obtained by polymerizing a monomer mixture containing from 10 to 100% by weight of an aromatic vinyl monomer, from 0 to 90% by weight of an alkyl (meth)acrylate having 1 to 8 carbon atoms in the alkyl group, and from 0 to 50% by weight of a copolymerizable vinyl monomer, thus giving the sum of (A), (B) and (C) of 100 parts by weight; and
2. an amorphous polyester resin composition which comprises from 1 to 40% by weight of the impact resistance improving agent as described above and from 60 to 99% by weight of an amorphous polyester resin.
BEST MODE FOR CARRYING OUT THE INVENTION
The core (A) of the core-shell impact resistance improving agent according to the invention is obtained. by polymerizing a monomer mixture containing from 30 to 100% by weight, preferably from 40 to 90% by weight and still preferably from 50 to 80% by weight, of a butadiene monomer, from 0 to 70% by weight, preferably from 10 to 60% by weight and still preferably from 20 to 50% by weight, of an aromatic vinyl monomer, from 0 to 10% by weight of a vinyl monomer copolymerizable with these monomers, and from 0 to 5% by weight of a crosslinkable monomer. From the viewpoint of strength, it is preferable to use a butadiene monomer. However, it is desirable to use not more than 90% by weight of the butadiene monomer from the viewpoint of transparency, since its reflective index largely differs from the reflective index of amorphous polyester resin compositions. It is also desirable that the content of the butadiene monomer is not less than 40% by weight, since the effect of expressing strength is superior. Therefore, it is preferable to use from 40 to 90% by weight, still preferably from 50 to 80% by weight, of the butadiene monomer. The aromatic vinyl monomer means a compound having a vinyl double bond and one or more benzene nuclei in a single molecule. Particular examples thereof include aromatic vinyl monomers such as styrene, &agr;-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-ethylstyrene, 2,5-dimethylstyrene, 4-methoxystyrene, 4-ethoxystyrene, 4- propoxystyrene, 4-butoxystyrene, chlorostyrene, dichlorostyrene, trichlorostyrene, vinyltoluene, bromostyrene, dibromostyrene, tribromostyrene, vinylnaphthalene, isopropenylnaphthalene, isopropenylbiphenyl and divinylbenzene, though the invention is not restricted thereto. Since the reflective index of rubber particles can be elevated and thus brought so close to the reflective index of amorphous polyester resin composition by using such an aromatic vinyl monomer, it is preferable from the viewpoint of transparency to use
Kadokura Mamoru
Kawai Hideki
Onuma Hisashi
Brinks Hofer Gilson & Lione
Kaneka Corporation
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