EP0352383A1 — Anionically-polymerized-rubber-modified styrene c…

Claim 1

Independent Claim 262 words

An anionically-polymerized-rubber-modified styrene copolymer characterized in that: A) said copolymer contains, as an impact strength modifier, 5-35 wt.% of a butadiene-based rubbery polymer (e.g. a butadiene-styrene copolymer) having a viscosity of 2-250 (e.g. 2-70) centipoises as measured at 25°C in the form of a 5 wt.% styrene solution, containing less than 0.1 wt.% of styrene-insoluble components and produced by anionic polymerization; B) said rubbery polymer is dispersed as particles, in which small particles of a copolymer (SA copolymer) of a styrene-type monomer (ST) (e.g. styrene or α-methyl-styrene) and an acrylonitrile-type monomer (AN) (e.g. acrylonitrile) are occluded in the form of cells, in a continuous phase of the same SA copolymer; C) in an ultrathin slice electron micrograph of ultrathin section of said anionically-polymerized-rubber-modified styrene copolymer, the percentage of the areas of rubber particles (R2) in each of which the maximum cell diameter is smaller than 0.1 µm is at least 40% when the area of all the rubber particles is assumed to be 100%; D) in the electron micrograph of ultrathin section, the volume average particle size of the rubber particles of R2 is 0.1-0.4 µm; E) the weight ratio of the monomers in the SA copolymer is expressed by 90/10 ≧ ST/AN ≧ 55/45; and F) per 100 parts by weight of the SA copolymer making up the continuous phase, the proportion of polymers having a molecular weight greater than 1,000,000 is smaller than 0.5 (e.g. smaller than 0.01) part by weight and the proportion of polymers having a molecular weight greater than 1,200,000 is smaller than 0.01 part by weight.

Claim 2

Dependent Claim 262 words

An anionically-polymerized-rubber-modified styrene copolymer characterized in that: A) said copolymer contains, as an impact strength modifier, 5-35 wt.% of a butadiene-based rubbery polymer (e.g. a butadiene-styrene copolymer) having a viscosity of 2-250 (e.g. 2-70) centipoises as measured at 25°C in the form of a 5 wt.% styrene solution, containing less than 0.1 wt.% of styrene-insoluble components and produced by anionic polymerization; B) said rubbery polymer is dispersed as particles, in which small particles of a copolymer (SA copolymer) of a styrene-type monomer (ST) (e.g. styrene or α-methyl-styrene) and an acrylonitrile-type monomer (AN) (e.g. acrylonitrile) are occluded in the form of cells, in a continuous phase of the same SA copolymer; C) in an ultrathin slice electron micrograph of ultrathin section of said anionically-polymerized-rubber-modified styrene copolymer, the percentage of the areas of rubber particles (R2) in each of which the maximum cell diameter is smaller than 0.1 µm is at least 40% when the area of all the rubber particles is assumed to be 100%; D) in the electron micrograph of ultrathin section, the volume average particle size of the rubber particles of R2 is 0.1-0.4 µm; E) the weight ratio of the monomers in the SA copolymer is expressed by 90/10 ≧ ST/AN ≧ 55/45; and F) per 100 parts by weight of the SA copolymer making up the continuous phase, the proportion of polymers having a molecular weight greater than 1,000,000 is smaller than 0.5 (e.g. smaller than 0.01) part by weight and the proportion of polymers having a molecular weight greater than 1,200,000 is smaller than 0.01 part by weight.

Claim 3

Dependent Claim 80 words

The rubber-modified styrene copolymer as claimed in claim 1, wherein the rubbery polymer is a styrene-butadiene copolymer rubber in the form of an S-B-S block of styrene (S) and butadiene (B), the copolymer rubber has a styrene contant of 10-30 (e.g. 15-27) wt.% and a visocity of 2-19 centipoises as measured at 25°C as a 5 wt.% styrene solution, and the microstructure of a butadiene chain of the S-B copolymer rubber contains 5-25 (e.g. 10-23) mole % of 1,2-vinyl bonds.

Claim 4

Dependent Claim 38 words

The rubber-modified styrene copolymer as claimed in claim 1, wherein the rubbery polymer contains the SA copolymer particles occluded and/or grafted in an amount of 10-100 parts by weight per 100 parts by weight of the rubbery polymer.

Claim 5

Dependent Claim 81 words

The rubber-modified styrene copolymer as claimed in claim 3, wherein the rubbery polymer is a styrene-butadiene (S-B) copolymer rubber in the form of an S-B block of styrene (S) and butadiene (B), the copolymer rubber has a styrene content of 3-28 (e.g. 15-27) wt.% and a viscosity of 2-19 centipoises as measured at 25°C as a 5 wt.% styrene solution, and the microstructure of a butadiene chain of the S-B copolymer rubber contains 5-25 (e.g. 10-23) mole % of 1,2-vinyl bonds.

Claim 6

Dependent Claim 83 words

The rubber-modified styrene copolymer as claimed in claim 2 or claim 4, wherein the viscosity (v) of the copolymer rubber as measured at 25°C as a 5 wt.% styrene solution satisfies the following equation: 0.5S - 7 ≦ v ≦ 0.5S + 3 wherein S is represented by 100z/(y+z) [S = 100z/(y+z)] in which y and z mean respectively the proportions of the styrene-type and acrylonitrile-type monomers in terms of parts by weight per 100 parts by weight of the rubber-modified styrene copolymer.

Claim 7

Dependent Claim 308 words

An anionically-polymerized-rubber-modified styrene copolymer characterized in that: A) said copolymer contains, as an impact strength modifier, 5-35 wt.% of a butadiene-based rubbery polymer (e.g. a butadiene-styrene copolymer) having a viscosity of 2-250 (e.g. 2-70) centipoises as measured at 25°C in the form of a 5 wt.% styrene solution, containing less than 0.1 wt.% of styrene-insoluble components and produced by anionic polymerization; B) said rubbery polymer is dispersed as particles, in which small particles of a copolymer (SA copolymer) of a styrene-type monomer (ST) (e.g. styrene or α-methyl-styrene) and an acrylonitrile-type monomer (AN) (e.g. acrylonitrile) are occluded in the form of cells, in a continuous phase of the same SA copolymer; C) in an electron micrograph of ultrathin section of said anionically-polymerized-rubber-modified styrene copolymer, the percentage of the areas of first rubber particles (R1) in each of which the maximum cell diameter is at least 0.1 µm is 2-60% (e.g. 2-45 %) while the percentage of the areas of second rubber particles (R2) in each of which the maximum cell diameter is smaller than 0.1 µm is 98-40 % (e.g. 98-55 %), both, when the area of all the rubber particles is assumed to be 100%; D) in the electron micrograph of ultrathin section, the volume average particle size of the first rubber particles (R1) is 0.3-4.0 µm while the volume average particle size of the second rubber particles (R2) is 0.1-0.4 µm; E) the weight ratio of the monomers in the SA copolymer is expressed by 90/10 ≧ ST/AN ≧ 55/45; and F) per 100 parts by weight of the SA copolymer making up the continuous phase, the proportion of polymers having a molecular weight greater than 1,000,000 is smaller than 0.5 (e.g. smaller than 0.01) part by weight and the proportion of polymers having a molecular weight greater than 1,200,000 is smaller than 0.01 part by weight.

Claim 8

Dependent Claim 308 words

An anionically-polymerized-rubber-modified styrene copolymer characterized in that: A) said copolymer contains, as an impact strength modifier, 5-35 wt.% of a butadiene-based rubbery polymer (e.g. a butadiene-styrene copolymer) having a viscosity of 2-250 (e.g. 2-70) centipoises as measured at 25°C in the form of a 5 wt.% styrene solution, containing less than 0.1 wt.% of styrene-insoluble components and produced by anionic polymerization; B) said rubbery polymer is dispersed as particles, in which small particles of a copolymer (SA copolymer) of a styrene-type monomer (ST) (e.g. styrene or α-methyl-styrene) and an acrylonitrile-type monomer (AN) (e.g. acrylonitrile) are occluded in the form of cells, in a continuous phase of the same SA copolymer; C) in an electron micrograph of ultrathin section of said anionically-polymerized-rubber-modified styrene copolymer, the percentage of the areas of first rubber particles (R1) in each of which the maximum cell diameter is at least 0.1 µm is 2-60% (e.g. 2-45 %) while the percentage of the areas of second rubber particles (R2) in each of which the maximum cell diameter is smaller than 0.1 µm is 98-40 % (e.g. 98-55 %), both, when the area of all the rubber particles is assumed to be 100%; D) in the electron micrograph of ultrathin section, the volume average particle size of the first rubber particles (R1) is 0.3-4.0 µm while the volume average particle size of the second rubber particles (R2) is 0.1-0.4 µm; E) the weight ratio of the monomers in the SA copolymer is expressed by 90/10 ≧ ST/AN ≧ 55/45; and F) per 100 parts by weight of the SA copolymer making up the continuous phase, the proportion of polymers having a molecular weight greater than 1,000,000 is smaller than 0.5 (e.g. smaller than 0.01) part by weight and the proportion of polymers having a molecular weight greater than 1,200,000 is smaller than 0.01 part by weight.

Claim 9

Dependent Claim 38 words

The rubber-modified styrene copolymer as claimed in claim 6, wherein the rubbery polymer contains the SA copolymer particles occluded and/or grafted in an amount of 10-100 parts by weight per 100 parts by weight of the rubbery polymer.

Claim 10

Dependent Claim 63 words

The rubber-modified styrene copolymer as claimed in claim 1 or claim 6, wherein the copolymer has been obtained by replacing 1-30 parts by weight of the styrene-type monomer and/or acrylonitrile-type monomer with a maleimide-type monomer (e.g. maleimide or N-phenylmaleimide) when the total amount of the styrene-type monomer and acrylonitrile-type monomer as components of the copolymer is assumed to be 100 parts by weight.

Claim 11

Independent Claim 16 words

A method of producing a rubber-modified styrene copolymer according to any one of the preceding claims.

Claim 12

Dependent Claim 18 words

A shaped article moulded from a rubber-modified styrene copolymer according to any one of claims 1 to 8.

Claim 13

Dependent Claim 18 words

A method of producing an article according to claim 10, wherein the article is moulded by injection moulding.

Anionically-polymerized-rubber-modified styrene copolymers

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