JPS634586B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a styrenic polymer composition having excellent impact resistance and appearance characteristics of molded articles. [Prior art] Conventionally, impact-resistant rubber-modified styrenic polymers, acrylonitrile-butadiene-styrene copolymers, and acrylic esters have been used as impact-resistant rubber-modified styrenic polymers that improve the impact resistance and oil resistance of polystyrene. Commercially available products include butadiene-styrene copolymer, methacrylic acid ester-butadiene-styrene copolymer, and impact-resistant rubber-modified styrene-maleic anhydride copolymer. These rubber-modified styrenic polymers take advantage of their characteristics such as rigidity, impact resistance, and processability, and are used as packaging materials,
It is used in a variety of products such as electrical parts, automobile parts, and architectural decorations. Traditionally, manufacturers have selected rubber-modified styrenic polymers available on the market based on price and physical properties, and used them alone or in combination to create products that meet the needs of end users. There is. However, the rubber-modified styrenic polymers available on the market lack impact resistance, and it is often impossible to manufacture impact-resistant products desired by end users. Therefore, there is a strong desire to develop a compounding technique that improves the impact resistance of commercially available rubber-modified styrenic polymers without degrading other physical properties. It is already known that one method for improving the impact resistance of rubber-modified styrenic polymers is to use a conjugated diolefin-vinyl substituted aromatic compound block copolymer as a toughening agent. For example,
-21012 and JP-A-48-56250 describe the use of block copolymers with relatively high conjugated diolefin content as toughening agents for impact-resistant rubber-modified styrene polymers. . However, in the former, although the impact resistance is improved, the surface gloss of the rubber-modified styrenic polymer is deteriorated, and in the latter, the rubber-modified polystyrene composition has good impact resistance and surface gloss. However, its properties are only realized when the difference in the intrinsic viscosity of the methyl ethyl ketone soluble portion of the rubber modified polystyrene and the intrinsic viscosity of the styrene-diene block copolymer is 0.1 d/g or less, and the composition It has the disadvantage that the above characteristics cannot be achieved unless extremely specific components are used as constituents of the product. On the other hand, JP-A-50-121351 and JP-A-51-
Publication No. 128347 describes the use of a block copolymer with a relatively high vinyl-substituted aromatic content as a toughening agent for impact-resistant rubber-modified styrene polymers, and The composition has good surface gloss. However, these compositions have the drawback of reduced impact resistance, and the method has not always been satisfactory. [Problems to be Solved by the Invention] In view of the current situation, the present inventors have conducted extensive studies in order to obtain a composition containing an impact-resistant rubber-modified styrenic polymer that has excellent impact resistance and surface gloss. As a result, by combining a block copolymer with a relatively high content of conjugated diolefin and a block copolymer with a relatively high content of a vinyl-substituted aromatic compound with an impact-resistant rubber-modified styrenic polymer, the objective was achieved. The present inventors have discovered that the following can be achieved, and have come up with the present invention. [Means for solving the problem] That is, the styrenic polymer composition of the present invention has (i) a vinyl-substituted aromatic compound content of 10% by weight;
1 to 50% by weight of a block copolymer consisting of a conjugated diolefin and a vinyl-substituted aromatic compound, the content of which is less than 55% by weight; (ii) the content of the vinyl-substituted aromatic compound is 55% by weight;
A block copolymer consisting of a conjugated diolefin and a vinyl-substituted aromatic compound, the amount of which is 95% by weight or less, and (a)

[Explanation of the structure of the invention and its effects]

The present invention will be explained in detail below. First, the block copolymer of component (i) has a vinyl-substituted aromatic compound content of 10% by weight or more and 55% by weight.
less than 20%, preferably 20-53% by weight, more preferably
25-50% by weight. In addition, the block copolymer of component (ii) has a vinyl-substituted aromatic compound content of 55
The content is at least 95% by weight, preferably from 57 to 90% by weight. In the present invention, a composition excellent in impact resistance and surface gloss can be obtained by using two types of block copolymers having a vinyl-substituted aromatic compound content within the above range. In addition, in the present invention, when the content of the vinyl-substituted aromatic compound in the block copolymer of component (ii) is 55% by weight or more and less than 65% by weight, preferably 57 to 63% by weight, the block copolymer has better impact resistance. A composition is obtained, while component (ii)
The content of the vinyl-substituted aromatic compound in the block copolymer is 65% by weight or more and 95% by weight or less, preferably
When the content is 67 to 90% by weight, a composition with better surface gloss can be obtained, so the content of the vinyl-substituted aromatic compound in the block copolymer can be arbitrarily selected within the above range depending on the required properties of the composition. be able to. As a method for producing the block copolymer of component (i) used in the present invention, Japanese Patent Publication No. 36-19286,
It is described in Japanese Patent Publication No. 14979-1979, Publication No. 36957-1977, etc. All of these are methods of block copolymerizing a conjugated diolefin and a vinyl-substituted aromatic compound using an anionic polymerization initiator such as an organolithium compound in a hydrocarbon solvent, and have the general formula (A-B) _o A(- B-A) _o , B(-A-B) _o (In the above formula, A is a polymer block mainly composed of a vinyl-substituted aromatic compound, and B is a polymer block mainly composed of a conjugated diolefin.
The boundary between A block and B block does not necessarily need to be clearly distinguished. Further, n is an integer of 1 or more. ), or the general formula [(B-A) _o ]- _n+2 X, [(A-B) _o ]- _n+2 X [(B-A)- _o B _n+2 X (In the above formula, A and B are the same as above,
X represents, for example, a residue of a coupling agent such as silicon tetrachloride or tin tetrachloride, or a residue of a polyfunctional organolithium compound. m and n are integers of 1 or more. ) is obtained as a radial block copolymer represented by: The structure of the above block copolymer has the following structure:
Complete block copolymers as well as tapered block copolymers can be included. In the present invention, vinyl-substituted aromatic hydrocarbons used for producing the block copolymers of component (i) and component (ii) include styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, Among them, 1,3-dimethylstyrene, α-methylstyrene, vinylnaphthalene, vinylanthracene, etc., styrene is particularly common. These may be used not only as a single type but also as a mixture of two or more types. Further, the conjugated diene is a diolefin having a pair of conjugated double bonds having 4 to 8 carbon atoms, such as 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3 -dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, etc., and particularly common ones include 1,3-butadiene and isoprene. These may be used not only as a single type but also as a mixture of two or more types. The molecular weight of the block copolymer of component (i) and component (ii) used in the present invention is 10,000 to 1,000,000, preferably 30,000 to 800,000. In the present invention, when a block copolymer having a structure represented by the general formula A-B (A and B have the same meanings as above) is used as the block copolymer of component (ii), it has a particularly high gloss. A composition with excellent properties can be obtained. In addition, as the block copolymer of component (ii), (a) 25% by weight or more and 75% by weight or less, preferably 25% by weight or less of the vinyl-substituted aromatic compound in the block copolymer.
~70% by weight, more preferably 30-65% by weight, is present as block homopolymer segments;
and (b) a composition using a block copolymer with a 1,2-vinyl bond content of 15% or less, preferably 13% or less has a low 1,2-vinyl bond content in the block copolymer. This results in interesting compositions with good impact resistance at low temperatures. In general, block copolymers with a low content of vinyl-substituted aromatic compounds that exist as block homopolymer segments are polymerized in the presence of polar compounds such as ether compounds and tertiary amine compounds in the polymerization system. Since the block copolymer thus obtained has a high 1,2-vinyl bond content, compositions using this block copolymer as a toughening agent have poor impact resistance at low temperatures; When a block copolymer meeting requirements (a) and (b) is used, this problem can be improved. The composition has excellent impact resistance not only at room temperature but also at low temperature.
As frozen foods have become widespread due to recent changes in dietary habits, their development is particularly desired as a material for food packaging containers. In the above requirement (a), a vinyl-substituted aromatic compound that is not incorporated into the block homopolymer segment of the vinyl-substituted aromatic compound, in other words, a vinyl-substituted aromatic compound copolymerized with a conjugated diene is The aromatic compound may be distributed uniformly in the entire polymer chain other than the block homopolymer segment or in a specific region, or may be distributed in a tapered shape. Block-like homopolymer segments of vinyl-substituted aromatic compounds in copolymers are
A method of oxidative decomposition of copolymers with tertiary butyl hydroperoxide using osmium tetroxide as a catalyst (for example, LMKolthoff et al.
al, J. Polymer Sci., 1429 (1946) method)
It can be quantified by etc. Therefore, the proportion of vinyl-substituted aromatic compounds present as block-like homopolymer segments in a block copolymer can be determined by calculating the amount of block-like homopolymer segments determined by such a method. It can be determined by dividing it by the amount of all vinyl-substituted aromatic compounds contained therein. In addition, the content of 1,2-vinyl bonds in the block copolymer is
It can be measured using an infrared spectrophotometer according to the method described in Analytical Chemistry, Vol. 21, p. 923 (1949). A preferred method for producing the block copolymer of component (ii) that satisfies the above requirements (a) and (b) is to prepare a conjugated diolefin and a vinyl-substituted aromatic compound in an inert hydrocarbon solvent substantially free of polar compounds. This is a method in which a mixture of organic lithium and organic lithium compounds is continuously supplied to at least one polymerization vessel, and copolymerization is carried out using an organic lithium compound as a catalyst. Here, to copolymerize by continuously feeding the monomer mixture means to continuously feed the conjugated diolefin and the vinyl-substituted aromatic compound into the polymerization vessel where the polymerization reaction is substantially progressing. means to copolymerize. Therefore, as long as the conjugated diolefin and the vinyl-substituted aromatic compound are continuously supplied to the polymerization vessel and mixed, it is not necessarily necessary to mix these monomers in advance. In producing such a block copolymer, a portion of the conjugated diolefin and/or a portion of the vinyl-substituted aromatic compound may be polymerized separately from the remaining mixture of the conjugated diolefin and the vinyl-substituted aromatic compound. At this time, a part of the conjugated diolefin and/or a part of the vinyl-substituted aromatic compound may be fed into the polymerization vessel in its entirety at once or in a predetermined amount continuously, but the remaining conjugated diolefin and vinyl-substituted aromatic compound The mixture with the substituted aromatic compound must be fed continuously to the polymerization vessel. Further, as a method for producing such a block copolymer, either a semi-batch polymerization method or a continuous polymerization method can be adopted. Examples of organic lithium compounds include hydrocarbons with at least one lithium atom bonded in the molecule, such as n-propyllithium, isopropyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium, and n-pentyllithium. Lithium, lithium toluene, benzyl lithium, 1,4-dilithio-n-butane, 1,2-dilithio-1,2-diphenylethane, trimethylene dilithium, oligoisoprenyl dilithium,
Particularly common examples of polystyryllithium include n-butyllithium and sec-butyllithium. Examples of inert hydrocarbon solvents include aliphatic hydrocarbons such as butane, pentane, hexane, isopentane, octane, and isooctane; alicyclic hydrocarbons such as cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, and ethylcyclohexane; Alternatively, aromatic hydrocarbons such as benzene, toluene, ethylbenzene, and xylene can be used. These can also be mixed and used depending on the purpose. The inert hydrocarbon solvent used as the solvent is one that does not substantially contain polar compounds such as ether compounds and tertiary amine compounds. As mentioned above, the presence of polar compounds in the solvent increases the number of vinyl bonds in the copolymer, which is undesirable. Note that "substantially no polar compounds are contained" means 1,
It means a solvent that can produce a block copolymer whose content of 2-vinyl bonds does not fall within the range defined by the present invention. The block copolymer of component (ii) of the present invention has a polymer structure of the general formula (A-B) _o , A(-B-A) _o , B(-A-B) _o (in the above formula, A B is a polymer block mainly composed of a vinyl-substituted aromatic compound, and B is a polymer block mainly composed of a conjugated diolefin.
The boundary between A block and B block does not necessarily need to be clearly distinguished. Further, n is an integer of 1 or more. ), or the general formula [(B-A) _o ]- _n+2 X, [(A-B) _o ]- _n+2 X [(B-A)- _o B ]― _n+2 X (In the above formula, A and B are the same as above, and
represents, for example, a residue of a coupling agent such as silicon tetrachloride or tin tetrachloride, or a residue of a polyfunctional organolithium compound. m and n are integers of 1 or more. ) can be used. Incidentally, the structure of the above block copolymer may also include a tapered block copolymer. Next, the impact-resistant rubber-modified styrenic polymer used in the present invention is obtained by polymerizing a mixture of a vinyl-substituted aromatic compound or a monomer copolymerizable therewith with an elastomer. Turbid polymerization, emulsion polymerization, bulk polymerization,
Bulk-suspension polymerization is commonly carried out. Examples of monomers copolymerizable with the vinyl-substituted aromatic compound include α-methylstyrene, acrylonitrile, acrylic esters, methacrylic esters, and maleic anhydride. Elastomers include natural rubber, synthetic isoprene rubber, butadiene rubber, styrene-butadiene rubber, high styrene rubber, polybutadiene rubber, chloroprene rubber, polybutene rubber, rubbery ethylene-propylene copolymer, rubbery butadiene-acrylonitrile copolymer. Rubber, butyl rubber, various nitrile rubbers, rubbery ethylene-vinyl acetate copolymers, rubbery ethylene-acrylic acid ester copolymers, rubbery atactic polypropylene resins, rubbery ethylene-acrylic acid ionomers, etc. are used. Particularly preferred impact-resistant rubber-modified styrenic polymers include impact-resistant rubber-modified styrenic polymers,
Acrylonitrile-butadiene-styrene copolymer, acrylic ester-butadiene-styrene copolymer, methacrylic ester-butadiene
Styrene copolymer, impact-resistant rubber-modified styrene
Examples include maleic anhydride copolymers, and these can be used alone or as a mixture of two or more. In the present invention, in addition to components (i), (ii), and (iii), a non-rubber-modified styrenic polymer can be further included to improve the rigidity of the composition. The non-rubber modified styrenic polymer is obtained by polymerizing a vinyl-substituted aromatic compound or a monomer copolymerizable therewith. Examples of monomers copolymerizable with the vinyl-substituted aromatic compound include α-methylstyrene, acrylonitrile, acrylic esters, methacrylic esters, and maleic anhydride. Particularly preferred non-rubber modified styrenic polymers include polystyrene, styrene-α-merstyrene copolymer, acrylonitrile-styrene copolymer, styrene-methacrylic acid ester copolymer,
Examples include styrene-maleic anhydride copolymer, which can be used alone or as a mixture of two or more. In the present invention, the preferred blending weight ratio of each component is that component (i) is 1 to 50% by weight, preferably 3 to 35% by weight, more preferably 5 to 25% by weight;
(ii) is 1 to 98% by weight, preferably 5 to 92% by weight, and component (iii) is 1 to 98% by weight, preferably 5% by weight.
~92% by weight. The blending ratio range of components (i), (ii) and (iii) is the recommended range for use in obtaining a composition with excellent impact resistance and surface gloss. In such a composition, when the composition ratio of component (ii) to component (iii) is 1/1 or more, a composition with relatively good transparency can be obtained. The styrenic polymer composition of the present invention can contain any filler, if necessary. In the present invention, when blending a filler, the blending amount is as follows:
Preferably it is 50 parts by weight or less. When the amount of filler added exceeds 50 parts by weight, the impact resistance of the composition tends to decrease. The type of filler is not particularly limited as long as it is commonly used in plastic compounding, but examples include glass fiber, glass beads, inorganic reinforcing agents such as silica, charcoal, and talc, organic fibers, coumaron indene resin, etc. organic reinforcing agents, crosslinking agents such as organic peroxides and inorganic peroxides, pigments such as titanium white, carbon black, and iron oxide, dyes, flame retardants, antioxidants, ultraviolet absorbers, antistatic agents, lubricants, and plasticizers. , other fillers, or mixtures thereof. In the present invention, the styrenic polymer composition consisting of each component can be produced by any conventionally known compounding method. For example, a melt-kneading method using a general mixer such as an open roll, an intensive mixer, an internal mixer, a co-kneader, a continuous kneader with a twin-screw rotor, an extruder, etc., each component is dissolved or dispersed in a solvent, and then the solvent is mixed. A method is used to heat and remove. The styrenic polymer composition of the present invention thus obtained can be processed by any conventionally known molding method, for example,
Sheets, foams, films, injection molded products of various shapes, etc. are made by extrusion molding, injection molding, blow molding, etc.
It can be easily molded into a wide variety of practically useful products such as blow molded products, pressure molded products, vacuum molded products, and biaxially stretched products. [Examples] Examples of the present invention are shown below to explain the present invention in more detail, but it goes without saying that the content of the present invention is not limited to these Examples. Note that the solvents, monomers, and additives such as randomizers used in the examples were purified and dried in advance. Reference Examples 1 to 4 and Reference Comparative Examples 1 and 2 Styrene having the structure B-A-B-A (B indicates a polymer block mainly composed of butadiene, and A indicates a polymer block mainly composed of styrene). A tapered block copolymer (sample 1) with a content of 40% by weight and a molecular weight of approximately 80,000 and a styrene content of 80% by weight with a similar structure, a ratio of block styrene to the total styrene of 83% by weight, and a molecular weight of approximately 140000, a tapered block copolymer with a 1,2-vinyl bond content of 11% (referred to as sample 2) and an impact-resistant rubber-modified polystyrene with a rubber content of 8% by weight and a melt flow (condition G) of 2 (HIPS1). ) were thoroughly mixed in a Henschel mixer according to the blending ratio shown in Table 1, and then pelletized using an extruder. The obtained pellets were injection molded to prepare specimens for measuring physical properties, and their physical properties were measured.

[Table] Reference Examples 5 and 6 In place of Sample 1, a complete block copolymer having an A-B-A structure with a styrene content of 30% by weight and a molecular weight of approximately 120,000 (referred to as Sample 3) was used. Styrene content with structure B-A instead of 80% by weight, proportion of blocked styrene to total styrene is 8.3% by weight, molecular weight approx.
140,000, a tapered block copolymer with a 1,2-vinyl bond content of 11% (referred to as sample 4) or a styrene content of 60% by weight with an A-B-A structure, a molecular weight of about 140,000, 1,2- Vinyl bond content
A test piece for measuring physical properties was prepared in the same manner as in Example 1, except that a 11% complete block copolymer (referred to as sample 5) was used, and the physical properties were measured.

[Table] Example 1 and Comparative Example 1 It has the structure ABA as shown below, the styrene content is 80% by weight, and the block styrene content (homopolystyrene contained in the copolymer) is about 45%. A block copolymer (referred to as sample 6) having a weight percent and a 1,2-vinyl bond content of 11% was obtained. A washed and dried autoclave equipped with a stirrer jacket was purged with nitrogen, and after charging cyclohexane 4 into the autoclave, the internal temperature was raised to 90°C. Next, after adding a hexane solution containing 2.1 g of n-butyllithium, 100 g of butadiene
A cyclohexane solution mixture containing 1,400 g of styrene and styrene at a concentration of 30% by weight was pumped to 90 ml/
Continuously feed the autoclave at a speed of min,
After the feeding was completed, it was left under stirring for about 5 minutes.
Next, a cyclohexane solution mixture containing 500 g of butadiene at a concentration of 30% by weight was continuously supplied using a pump at a rate of 90 ml/min to cause a reaction.
A hexane solution mixture containing g at a concentration of 30% by weight was continuously fed by a pump at a rate of 90 ml/min, and after the feeding was completed, the mixture was left under stirring for about 15 minutes.
The polymerization temperature during the polymerization was maintained at 90°C throughout. After the polymerization reaction, di-tert-butyl-p-cresol was added as a stabilizer to the resulting copolymer solution, and the solvent cyclohexane was distilled off under heating to obtain a block copolymer. Next, a tapered block copolymer having an ABA structure (referred to as sample 7) was synthesized using tetrahydrofuran as a randomizer in the manner described below. In the same autoclave as above, a cyclohexane solution containing 4 cyclohexane, 1400 g of styrene at a concentration of 30% by weight, and tetrahydrofuran.
A cyclohexane solution containing 10 g of n-butyllithium was added to each, and after the temperature was raised to 55° C., a hexane solution containing 2.1 g of n-butyllithium was added.
After that, after reacting at 60℃ for 1 hour, butadiene
A cyclohexane solution mixture containing 700 g and 1400 g of styrene at a concentration of 30% by weight was added and reacted under similar conditions. The obtained copolymer solution was treated in the same manner as described above to obtain a block copolymer. The styrene content of this block copolymer is
80% by weight, blocked styrene content is approximately 42% by weight
The 1,2-vinyl bond content was 20%. Next, each of the above samples was prepared with a styrene content of 30% by weight having a structure of (A-B) _-4Si , and a molecular weight of approximately
A composition was prepared in which a radial block copolymer of 170,000 (referred to as sample 8) and HIPS1 were blended in the same proportions as in Reference Example 1, and its physical properties were measured. As can be seen from the physical property measurement results shown in Table 3,
In the composition of the present invention, when a block copolymer with a low block styrene content is used as component (ii), the effect of improving impact resistance is large, and furthermore, a block copolymer with a low content of 1,2-vinyl bonds is used. In this case, a composition having good impact resistance at low temperatures can be obtained.

[Table] Example 2 and Comparative Examples 2 and 3 A cyclohexane solution mixture containing 400 g of butadiene and 100 g of styrene at a concentration of 30% by weight as monomers in the first stage, and 100 g of butadiene and 600 g of styrene as monomers in the second stage. A cyclohexane solution mixture containing at a concentration of 30% by weight was added to 700 g of butadiene as the third stage monomer.
and a cyclohexane solution mixture containing 100 g of styrene at a concentration of 30% by weight, and 200 g of butadiene and 1300 g of styrene as fourth stage monomers.
Using a cyclohexane solution mixture containing 30% by weight of
B-A-B-
A block copolymer (referred to as sample 9) having the structure A, containing 60% by weight of styrene, 40% by weight of block styrene, and 11% of 1,2-vinyl bond content was obtained. Next, the composition 100 before adding the filler shown in Table 4
Antimony trioxide 3 parts by weight, respectively
Parts by weight and 30 parts by weight of decabromotetralin were added and thoroughly mixed in a Henschel mixer, and then pelletized in an extruder. The physical properties of the test pieces injection-molded from these pellets are shown in Table 4, and as is clear from the results, the molded products of the composition of the present invention had extremely good surface conditions with no rough skin observed. .

[Table] Example 3 and Comparative Example 4 In order to confirm the synergistic effect of the combination of component (i) and component (ii) in the present invention, a composition was prepared according to the blending ratio shown in Table 5, and injection molded. A test piece for measuring physical properties was prepared. The physical property measurement results are shown in Table 5, and the results show that the combined use of component (i) and component (ii) is superior in terms of impact resistance and surface gloss, confirming their synergistic effect. .

[Table] Example 4 Sample 8 was 7% by weight, styrene content with (A-B) _-4 Si structure was 75% by weight, proportion of blocked styrene to total styrene was 68% by weight, molecular weight was approximately 160,000, 1, 13% by weight radial block copolymer with 11% 2-vinyl bond content, rubber content
Compositions of the invention containing 80% by weight of 20% by weight of acrylonitrile-butadiene-styrene copolymer
100 parts by weight of glass fiber (manufactured by Nittobo Co., Ltd., CS69A
-401) was blended, and a molded article was obtained from the composition by injection molding. The obtained molded product had excellent impact resistance and a good surface condition.

Claims (1)

[Scope of Claims] 1 (i) A block copolymer consisting of a conjugated diolefin and a vinyl-substituted aromatic compound, in which the content of the vinyl-substituted aromatic compound is 10% by weight or more and less than 55% by weight, from 1 to 50% by weight. , (ii) the content of vinyl-substituted aromatic compounds is 55% by weight;
It is a block copolymer consisting of a conjugated diolefin and a vinyl-substituted aromatic compound in an amount of 95% by weight or less, and (a) [Table] 〓Total amount contained in the copolymer〓
〓Amount of vinyl substituted aromatic compound
〓
(b) 1 to 98% by weight of a block copolymer having a 1,2-vinyl bond content of 15% or less, and (iii) a styrenic polymer consisting of 1 to 98% by weight of an impact-resistant rubber-modified styrenic polymer. Coalescing composition. 2. The composition according to claim 1, wherein the vinyl-substituted aromatic compound content of the block copolymer of component (ii) is 55% by weight or more and less than 65% by weight. 3. The composition according to claim 1, wherein the vinyl-substituted aromatic compound content of the block copolymer of component (ii) is 65% by weight or more and 95% by weight or less. 4 Component (iii) is impact resistant rubber modified styrene polymer, acrylonitrile-butadiene-styrene copolymer, acrylic ester-butadiene-styrene copolymer, methacrylic ester-butadiene-styrene copolymer, impact resistant The composition according to claim 1, which is any one type or a mixture of two or more types of rubber-modified styrene-maleic anhydride copolymers. 5 Component (ii) has a structure represented by the general formula A-B (wherein A is a polymer block mainly composed of a vinyl-substituted aromatic compound, and B is a polymer block mainly composed of a conjugated diolefin). The composition according to claim 1, which is a block copolymer comprising: 6 Component (ii) is a method in which a mixture of a conjugated diolefin and a vinyl-substituted aromatic compound is continuously introduced into at least one polymerization vessel using an organolithium compound as a catalyst in an inert hydrocarbon solvent substantially free of polar compounds. The composition according to claim 1, which is a block copolymer obtained by copolymerizing the composition. 7. A block copolymer in which component (ii) is obtained by polymerizing a part of the conjugated diolefin and/or a part of the vinyl-substituted aromatic compound separately from the remaining mixture of the conjugated diolefin and the vinyl-substituted aromatic compound. The composition according to claim 6, which is 8. The composition according to claim 1, which contains 50 parts by weight or less of a filler based on 100 parts by weight of the composition.