JP2008308608A - Resin composition composed of styrene-based resin and polylactic acid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To develop a resin composition which does not deteriorate original moldability and stiffness inherent in a styrene-based resin by formulating a resin derived from a plant to the styrene-based resin, and to put it to practical use as a material for a foam, a sheet and an enclosure, etc. in order to reduce petroleum usage and maintain the environment. <P>SOLUTION: This resin composition comprises a styrene-based resin (A) of 87-15 wt.%, a hydrogenated block copolymer (B) of 5-30 wt.% containing a conjugated diene and a vinyl aromatic hydrocarbon, a block copolymer (C) of 3-20 wt.% containing a styrene-based monomer and a (meth)acrylate monomer, and polylactic acid (D) of 5-50 wt.%. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a styrene resin composition containing polylactic acid. By blending polylactic acid, a plant-derived material, the amount of petroleum-derived styrene resin used can be reduced, and the original properties of the styrene resin are not impaired, and fluidity and impact resistance are further reduced. Is obtained, and this resin composition can be preferably used for a molded body such as a casing.

  Styrenic resins are used in many industrial fields such as foams, sheets, and casings, taking advantage of their ease of molding and light weight.

  On the other hand, in recent years, non-petroleum resins that do not use petroleum as a raw material have attracted attention from the viewpoint of environmental problems such as global warming associated with the problem of depletion of petroleum resources and carbon dioxide emissions.

  Under these circumstances, resins using plant-derived raw materials as monomers have been developed. Starch obtained from corn and potatoes has already been saccharified, and further lactic acid bacteria to lactic acid, and then lactic acid is cyclized to lactide, A polylactic acid resin has been produced by ring-opening polymerization of this.

  The carbon in the plant-derived raw material resin thus obtained is fixed by photosynthesis of carbon dioxide in the atmosphere, so that even if incinerated, it increases the total amount of carbon dioxide. It can be said that there is no so-called “carbon neutral” material. In other words, it is a circulation type material that can maintain the environment.

By using such a plant-derived material capable of maintaining the environment in a petroleum resin, the amount of petroleum resin used can be reduced, and various studies have been conducted (Patent Documents). 1). If the above materials can be blended and used in a styrene resin, which is a typical petroleum resin, the amount of styrene resin used is large, and the amount of reduction is expected to be great. Reducing the amount of styrene resin used is to reduce the amount of petroleum used and the total amount of carbon dioxide gas, leading to a reduction in environmental burden.
JP-A-2005-48067

  The present invention can reduce the environmental load by blending a plant-derived resin with a styrene resin, and also has practical rigidity and excellent fluidity without losing the original moldability of the styrene resin. It aims at providing the resin composition which has impact resistance.

  As a result of diligent investigations by the present inventor to achieve this problem, the present inventors have found that a styrene resin, a hydrogenated block copolymer comprising a conjugated diene and a vinyl aromatic hydrocarbon, a styrene monomer, and a (meth) acrylate ester monomer. The present inventors have found that a block copolymer made of a monomer and a resin composition made of polylactic acid have fluidity and excellent mechanical properties that can be applied to various molding methods, and have reached the present invention.

That is, the present invention is as follows.
(1) Styrenic resin (A) 87-15% by weight, hydrogenated block copolymer consisting of conjugated diene and vinyl aromatic hydrocarbon (B) 5-30% by weight, styrene monomer and (meth) acrylic A resin composition comprising 3 to 20% by weight of a block copolymer (C) comprising an acid ester monomer and 5 to 50% by weight of polylactic acid (D).
(2) The block copolymer (C) comprising a styrene monomer and a (meth) acrylic acid ester monomer is an ab type block copolymer, and the a segment is formed from a styrene monomer. The b segment is formed from a (meth) acrylic acid ester monomer having an alkyl chain having 1 to 4 carbon atoms, and the ratio of the a segment to the b segment is 95/5 to 30 / by weight ratio. 70. The resin composition as described in (1), which is 70.
(3) A molded body comprising the resin composition according to any one of (1) and (2).

According to the present invention, environmental load can be reduced by blending a plant-derived resin with a styrenic resin, and practical rigidity and excellent fluidity can be achieved without losing the original moldability of the styrenic resin. And a resin composition having both impact resistance can be provided.

  Hereinafter, the present invention will be described in detail.

The styrene resin (A) used in the present invention is a polymer mainly composed of styrene.
Examples of the styrene resin (A) include polystyrene, rubber-modified polystyrene, styrene resin obtained by copolymerizing styrene and other vinyl monomers, and the like.

  Polystyrene is a homopolymer of styrene, and generally available ones can be appropriately selected and used. Generally available polystyrenes are provided with different flowability by adjusting the degree of polymerization of styrene, molecular weight distribution, and the amount of plasticizer and lubricant. As for the fluidity of the polystyrene used in the present invention, the melt flow rate measured in accordance with ISO 1133 is preferably in the range of 1 to 10 g / 10 min. When the flowability of polystyrene is lower than the above range, the moldability of the resin composition of the present invention, particularly the mold filling property in injection molding, is not preferable. On the other hand, when the flowability of polystyrene exceeds the above range, the moldability of the resin composition of the present invention, particularly the thickness uniformity in extrusion molding, vacuum molding, and blow molding, is unfavorable.

Rubber-modified polystyrene is a molding material in which a rubber-like polymer is graft-polymerized and dispersed in a continuous phase composed of a polymer of styrene alone, and generally available materials can be appropriately selected and used. Examples of the rubber used for the rubber-modified polystyrene include polybutadiene, styrene-butadiene copolymer, polyisoprene, butadiene-isoprene copolymer, natural rubber, and ethylene-propylene copolymer. In particular, polybutadiene and styrene-butadiene copolymer are preferable.
As for the fluidity of the rubber-modified polystyrene, the melt flow rate measured according to ISO 1133 is preferably in the range of 1 to 10 g / 10 min. When the fluidity of the rubber-modified polystyrene is below the above range, the moldability of the resin composition of the present invention, particularly the mold filling property in the injection molding, is not preferable. On the other hand, when the fluidity of the rubber-modified polystyrene exceeds the above range, the moldability of the resin composition of the present invention, particularly the thickness uniformity in extrusion molding, vacuum molding, and blow molding, is unfavorable.

  Styrene resins copolymerized with styrene and other vinyl monomers include styrene and (meth) acrylic acid copolymers, styrene and (meth) acrylic acid ester copolymers, styrene and maleic anhydride And a copolymer.

  The (A) component polystyrene of the present invention, rubber-modified polystyrene, and styrene resin copolymerized with styrene and other vinyl monomers may be used alone, or at least two components may be used in an arbitrary ratio. You may mix and use. When a plurality of components (A) are used, a hydrogenated block copolymer (B) comprising a conjugated diene and a vinyl aromatic hydrocarbon, a block comprising a styrene monomer and a (meth) acrylate monomer Prior to mixing the copolymer (C) and the polylactic acid (D), the component (A) may be previously made into a uniform material by melt kneading or the like, or a plurality of components (A), a conjugated diene and vinyl. A hydrogenated block copolymer (B) comprising an aromatic hydrocarbon, a block copolymer (C) comprising a styrene monomer and a (meth) acrylate monomer, and polylactic acid (D) together You may melt-knead.

  When the entire resin composition of the present invention is 100% by weight, the content of the styrenic resin (A) is 87 to 15% by weight. Preferably, it is 80 to 20% by weight. When it exceeds 87% by weight, the blending amount of other components is small, and therefore improvement in physical properties is hardly observed. On the other hand, if the content of the styrenic resin (A) is less than 15% by weight, the inherent characteristics of the styrenic resin, such as rigidity and heat resistance (Vicat softening temperature, load deflection temperature), are greatly impaired.

The hydrogenated block copolymer (B) comprising a conjugated diene and a vinyl aromatic hydrocarbon used in the present invention is obtained by hydrogenating a non-hydrogenated block copolymer comprising a conjugated diene compound and a vinyl aromatic compound. Hydrogenated block copolymer. The conjugated diene compound is a diolefin having a pair of conjugated double bonds, and examples thereof include 1,3-butadiene and 2-methyl-1,3-butadiene (isoprene). Examples of vinyl aromatic compounds include styrene, α-methylstyrene, and divinylbenzene. The most common is a hydrogenated block copolymer consisting of 1,3-butadiene and styrene, called SEBS.
A known method can be used for block copolymerization of the conjugated diene and the vinyl aromatic hydrocarbon and hydrogenation of the obtained block copolymer.
The content of the vinyl aromatic compound in the hydrogenated block copolymer (B) comprising conjugated diene and vinyl aromatic hydrocarbon used in the present invention is preferably 10% by weight or more and less than 70% by weight, more preferably 20% by weight. As mentioned above, it is less than 60 weight%. If the vinyl aromatic compound content is less than 10% by weight, the rigidity of the resin composition of the present invention is significantly reduced. On the other hand, if the vinyl aromatic compound content exceeds 70% by weight, impact resistance is improved. It is not recognized and neither is preferable.
The hydrogenation rate of the double bond based on the conjugated diene compound of the hydrogenated block copolymer (B) comprising conjugated diene and vinyl aromatic hydrocarbon used in the present invention is preferably 75 to 100%, more preferably 80 to 100. %. When the hydrogenation rate is lower than 75%, the rigidity of the resin composition of the present invention is significantly lowered, which is not preferable.
The weight average molecular weight of the hydrogenated block copolymer (B) comprising conjugated diene and vinyl aromatic hydrocarbon used in the present invention is preferably 3 to 1,000,000. More preferably, it is 5 to 800,000.
When the weight average molecular weight is less than 30,000, the impact resistance of the resin composition of the present invention is inferior, and when the weight average molecular weight exceeds 1,000,000, the molding processability of the resin composition of the present invention is inferior.

  The hydrogenated block copolymer (B) comprising a conjugated diene and a vinyl aromatic hydrocarbon used in the present invention may be modified with a compound having a functional group. Examples of the functional group include a carboxyl group, an acid anhydride group, an isocyanate group, an epoxy group, a silanol group, and an alkoxysilane group.

  A commercially available product can be used as the hydrogenated block copolymer (B) comprising a conjugated diene and a vinyl aromatic hydrocarbon used in the present invention. An example is Tuftec (trade name) manufactured by Asahi Kasei Chemicals Corporation.

  When the total resin composition of the present invention is 100% by weight, the content of the hydrogenated block copolymer (B) comprising conjugated diene and vinyl aromatic hydrocarbon is 5 to 30% by weight, preferably 10 to 25% by weight. It is. If it is less than 5% by weight, the impact resistance is hardly improved. On the other hand, when it exceeds 30% by weight, the decrease in rigidity and heat resistance (Vicat softening temperature, load deflection temperature) is not preferable.

  As impact resistance, Charpy impact strength and DuPont impact strength are evaluated. DuPont impact is the surface impact strength measured by dropping a dart onto a flat test piece. In particular, the DuPont impact strength can be remarkably improved by blending the hydrogenated block copolymer (B) comprising a conjugated diene and a vinyl aromatic hydrocarbon.

    The block copolymer (C) comprising a styrene monomer and a (meth) acrylic acid ester monomer used in the present invention is an ab type block copolymer, and the a segment is a styrene monomer. The b segment is formed from a (meth) acrylic acid ester monomer having an alkyl chain having 1 to 4 carbon atoms. The ab type block copolymer can be produced by using, for example, polymeric peroxide by a known production process such as bulk polymerization, suspension polymerization, emulsion polymerization, and solution polymerization.

  Specific examples of the (meth) acrylic acid ester monomer having an alkyl chain having 1 to 4 carbon atoms include (meth) acrylic acid methyl ester, (meth) acrylic acid ethyl ester, ester (meth) acrylic acid isopropyl ester, Examples include butyl acrylate, and the most easily available monomer is methacrylic acid methyl ester.

  The ratio of the styrene monomer as the a segment to the (meth) acrylic acid ester monomer as the b segment is 95/5 to 30/70, preferably 93/7 to 40/60. It is. When the weight ratio of the (meth) acrylic acid ester monomer is outside the above range, tensile by blending a block copolymer (C) composed of a styrene monomer and a (meth) acrylic acid ester monomer An improvement in fracture strain, Charpy impact strength, or the like is not recognized, or rather may be lowered.

  A commercially available block copolymer (C) composed of the styrene monomer and the (meth) acrylic acid ester monomer may be used. As an example, “Modiper (trade name) MS10B” manufactured by NOF Corporation may be used.

When the entire resin composition of the present invention is 100% by weight, the content of the block copolymer (C) composed of a styrene monomer and a (meth) acrylate monomer is 3 to 20% by weight, preferably 5 to 20% by weight. If it is less than 3% by weight, almost no improvement in Charpy impact strength is observed. On the other hand, if it exceeds 20% by weight, the decrease in DuPont impact strength is large, which is not preferable.
By blending a block copolymer (C) consisting of a styrene monomer and a (meth) acrylic acid ester monomer, the Charpy impact strength is improved without reducing the rigidity, but the DuPont impact strength. (Surface impact strength) decreases. As described above, the DuPont impact strength can be remarkably improved by blending the hydrogenated block copolymer (B) composed of a conjugated diene and a vinyl aromatic hydrocarbon. Therefore, by using a hydrogenated block copolymer (B) composed of a conjugated diene and a vinyl aromatic hydrocarbon and a block copolymer (C) composed of a (meth) acrylate monomer, the Charpy impact strength is increased. Both the thickness and the DuPont impact strength can be greatly improved, which is preferable.

  The polylactic acid (D) used in the present invention is obtained by saccharifying starch obtained from corn, potatoes, etc., further obtaining lactic acid by lactic acid bacteria, and then cyclizing the lactic acid to give lactide, which is subjected to ring-opening polymerization. Then, polylactic acid (D) obtained by the method can be used. Also, polylactic acid obtained by synthesizing lactide from petroleum and ring-opening polymerization thereof, or polylactic acid obtained by obtaining lactic acid from petroleum and directly dehydrating and condensing it may be used.

  Moreover, regarding the ratio of L-lactic acid and D-lactic acid which comprise polylactic acid (D), it can use without being specifically limited. However, when it is necessary to increase heat resistance by crystallizing polylactic acid, the ratio of L-lactic acid to D-lactic acid is 100: 0 to 90:10 or 0: 100 to 10:90, preferably L -Polylactic acid having a ratio of lactic acid to D-lactic acid of 100: 0 to 95: 5 or 0: 100 to 5:95 is used.

  Furthermore, other components may be copolymerized with polylactic acid (D) in addition to D-lactic acid and L-lactic acid, which are main constituent monomers. Examples of other copolymer components include ethylene glycol, propylene glycol, butanediol, oxalic acid, adipic acid, and sebacic acid. Such a copolymer component is preferably contained in an amount of usually 0 to 30 mol%, more preferably 0 to 10 mol%, in all monomer components.

  The molecular weight and molecular weight distribution of polylactic acid (D) are not particularly limited as long as it can be substantially molded, but the weight average molecular weight is preferably 10,000 or more and 400,000 or less, more preferably 40,000 or more and 300,000. It is as follows.

  The compounding quantity of polylactic acid (D) is 5 to 50 weight% when the whole resin composition of this invention is 100 weight%, Preferably it is 10 to 50 weight%. When the polylactic acid (D) exceeds 50% by weight, the Vicat softening temperature and the load deflection temperature of the resin composition are significantly lowered as compared with the styrene resin (A), which is not preferable. On the other hand, if the polylactic acid (D) is less than 5% by weight, the effect of adding the polylactic acid (D) is not exhibited, which is not preferable.

  Styrenic resin (A), hydrogenated block copolymer (B) comprising conjugated diene and vinyl aromatic hydrocarbon, block copolymer (C) comprising (meth) acrylic acid ester monomer, and polylactic acid ( The method of blending, melting, kneading and granulating D) is not particularly limited, and a method commonly used in the production of resin compositions can be used. For example, the above ingredients blended with a drum tumbler, Henschel mixer, etc. are melted and kneaded using a Banbury mixer, single screw extruder, twin screw extruder, kneader, etc., and granulated with a rotary cutter, fan cutter, etc. A composition can be obtained. The resin temperature in melting and kneading is preferably 180 to 240 ° C. In order to achieve the target resin temperature, the cylinder temperature of the extruder or the like should be set to a temperature 10 to 20 ° C. lower than the resin temperature. When the resin temperature is less than 180 ° C., the flowability of the block copolymer (C) composed of the styrene resin (A) and the (meth) acrylate monomer is insufficient and mixing with the polylactic acid (D) is not possible. It is not preferable because it is sufficient. On the other hand, when the resin temperature exceeds 240 ° C., polylactic acid (D) is thermally decomposed, which is not preferable.

Furthermore, the resin composition of the present invention comprises a styrene resin (A), a hydrogenated block copolymer (B) comprising a conjugated diene and a vinyl aromatic hydrocarbon, a styrene monomer and a (meth) acrylic acid ester system. Additives such as antioxidants, lubricants, colorants, UV absorbers, and light stabilizers when blending, melting, kneading, and granulating the monomer block copolymer (C) and polylactic acid (D) Can be added.
The resin composition of the present invention is molded into a resin product by a method such as injection molding, sheet extrusion molding, vacuum molding, profile extrusion molding, or blow molding.

＜共役ジエンとビニル芳香族炭化水素からなる水添ブロック共重合体（Ｂ）＞
（Ｂ）−１；タフテック（商品名）Ｈ１０４１＜旭化成ケミカルズ(株）製＞
水添ブロック共重合体、スチレン成分含有量３０重量％
メルトフローレイト＜２００℃，５ｋｇｆ＞：３．５ｇ／１０ｍｉｎ
（Ｂ）−２；タフテック（商品名）Ｈ１０４３＜旭化成ケミカルズ(株）製＞
水添ブロック共重合体、スチレン成分含有量６７重量％
メルトフローレイト＜２３０℃，２．１６ｋｇｆ＞：２．０ｇ／１０ｍｉｎ
（Ｂ）−３；タフテック（商品名）Ｍ１９１３＜旭化成ケミカルズ(株）製＞
変性水添ブロック共重合体、スチレン成分含有量３０重量％
メルトフローレイト＜２００℃，５ｋｇｆ＞：４．０ｇ／１０ｍｉｎ

＜スチレン系単量体と（メタ）アクリル酸エステル系単量体からなるブロック共重合体（Ｃ）＞
（Ｃ）−１；日本油脂株式会社製 「モディパー（商品名） ＭＳ１０Ｂ」
スチレンとメタクリル酸メチルとのブロック共重合体で組成比：スチレン／メタクリル酸メチル＝９０／１０である。また、ＩＳＯ１１３３（２００℃、５ｋｇｆ）に従って測定したメルトフローレイトは３．５ｇ／１０ｍｉｎであった。
＜ポリ乳酸（Ｄ）＞
（Ｄ）−１；Nature Works LLC製「４０３２Ｄ」（商品名）
ＩＳＯ１１３３（２００℃、５ｋｇｆ）に従って測定したメルトフローレイトは１４．２ｇ／１０ｍｉｎであった。 EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further, this invention is not limited to a following example, unless the summary is exceeded.
<Styrene resin (A) -1>
(A) -1; Polystyrene “685” (trade name) manufactured by PS Japan Co., Ltd.
The basic physical properties are shown in (Table-1).
<Styrene resin (A) -2>
(A) -2; Rubber-modified polystyrene “H8117” (trade name) manufactured by PS Japan Co., Ltd.
The basic physical properties are shown in (Table-1).

<Hydrogenated block copolymer (B) comprising conjugated diene and vinyl aromatic hydrocarbon>
(B) -1; Tuftec (trade name) H1041 <Asahi Kasei Chemicals Corporation>
Hydrogenated block copolymer, styrene component content 30% by weight
Melt flow rate <200 ° C., 5 kgf>: 3.5 g / 10 min
(B) -2; Tuftec (trade name) H1043 <Asahi Kasei Chemicals Corporation>
Hydrogenated block copolymer, styrene component content 67% by weight
Melt flow rate <230 ° C., 2.16 kgf>: 2.0 g / 10 min
(B) -3; Tuftec (trade name) M1913 <Asahi Kasei Chemicals Corporation>
Modified hydrogenated block copolymer, styrene component content 30% by weight
Melt flow rate <200 ° C., 5 kgf>: 4.0 g / 10 min

<Block copolymer (C) comprising styrene monomer and (meth) acrylic acid ester monomer>
(C) -1; manufactured by NOF Corporation “Modiper (trade name) MS10B”
It is a block copolymer of styrene and methyl methacrylate, and the composition ratio is styrene / methyl methacrylate = 90/10. Moreover, the melt flow rate measured according to ISO1133 (200 degreeC, 5 kgf) was 3.5 g / 10min.
<Polylactic acid (D)>
(D) -1; “4032D” (trade name) manufactured by Nature Works LLC
The melt flow rate measured according to ISO1133 (200 ° C., 5 kgf) was 14.2 g / 10 min.

<Manufacture of resin composition>
Styrenic resin (A), hydrogenated block copolymer (B) composed of conjugated diene and vinyl aromatic hydrocarbon, block copolymer composed of styrene monomer and (meth) acrylate monomer ( C) and polylactic acid (D) were weighed as shown in the upper part of (Table-2) to (Table-4).
Weighed raw materials are mixed with a drum tumbler, and the same direction twin screw extruder (WERNER & PF)
The mixture was melt kneaded at a cylinder set temperature of 200 ° C. and a screw rotation speed of 200 rpm with a LEIDEER ZSK25) and extracted as a molten strand. The molten strand was cooled with water and the strand was cut with a rotary cutter to obtain a pellet-shaped resin composition.

<Measurement of physical properties>
Measurement of melt flow rate and mechanical properties;
The melt flow rate of the resin composition produced above was measured according to ISO1133. Also, the resin composition produced above is injection molded into ISO type A test pieces, tensile strength and tensile fracture strain according to ISO 527-1, bending strength according to ISO 178, flexural modulus, and Charpy impact strength according to ISO 179. The Vicat softening temperature was measured according to ISO306, and the load deflection temperature was measured according to ISO75-2.
DuPont impact test;
A DuPont impact test was conducted according to JIS K 5400. Using a DuPont impact tester, the energy of dropping the hitting core onto a 2 mm-thick injection-molded plate under the conditions that the tip R of the hitting core is 3 mm and the dent R of the cradle is 6 mm and generating cracks in the molded plate Asked.
The above measurement results are shown in the lower part of (Table-2) to (Table-4).

<Explanation of (Table-2)>
In a blend system of styrene-based resin (A) -1 (polystyrene) and polylactic acid (D), hydrogenation consisting of a conjugated diene and a vinyl aromatic hydrocarbon is compared in the same blending system of polylactic acid (D). By blending both the block copolymer (B) and the block copolymer (C) composed of a styrene monomer and a (meth) acrylate monomer, the Charpy impact strength and the DuPont impact strength are improved. Both are improved (Examples 1 to 5). When only the hydrogenated block copolymer (B) comprising conjugated diene and vinyl aromatic hydrocarbon is added (Comparative Examples 2, 4, 6, 8), the Charpy impact strength is not sufficiently improved. On the other hand, Charpy compared to the case where only the block copolymer (C) consisting of a styrene monomer and a (meth) acrylate monomer was added (Comparative Example 5), and the case where no block copolymer (Comparative Example 3) was added. There is little improvement in impact strength, and DuPont impact strength is rather reduced.
<Explanation of (Table-3)>
A hydrogenated block copolymer (B) comprising a conjugated diene and a vinyl aromatic hydrocarbon and a styrene monomer in a blend system of styrene resin (A) -2 (rubber-modified polystyrene) and polylactic acid (D) And a block copolymer (C) composed of a (meth) acrylic acid ester monomer, both Charpy impact strength and DuPont impact strength are improved (Examples 6 to 13). . When only the hydrogenated block copolymer (B) consisting of a conjugated diene and a vinyl aromatic hydrocarbon is added (Comparative Examples 10, 13-16, 19, 20), the DuPont impact strength is greatly improved. Impact strength is hardly improved. Also,
When only the block copolymer (C) consisting of a styrene-based monomer and a (meth) acrylic acid ester-based monomer is added (Comparative Examples 11, 17, and 21), when it is not added (Comparative Examples 9 and 12, Compared to 19), there is little improvement in Charpy impact strength, and Dupont impact strength is greatly reduced.

<Explanation of (Table-4)>
When styrene resin (A) -1 (polystyrene) and (A) -2 (rubber-modified polystyrene) are blended at 1: 1, or when styrene-based resin (A) -2 (rubber-modified polystyrene) is used alone. A similar tendency is observed. By using a hydrogenated block copolymer (B) composed of a conjugated diene and a vinyl aromatic hydrocarbon and a block copolymer (C) composed of a styrene monomer and a (meth) acrylate monomer (Examples 14 and 15), Charpy and DuPont both have improved impact strength.

  The resin composition of the present invention is preferably used in many industrial fields such as foams, sheets and housings, which are uses of polystyrene.

Claims (3)

  Styrenic resin (A) 87-15% by weight, hydrogenated block copolymer (B) 5% to 30% by weight of conjugated diene and vinyl aromatic hydrocarbon, styrene monomer and (meth) acrylic acid ester A resin composition comprising 3 to 20% by weight of a block copolymer (C) comprising a monomer and 5 to 50% by weight of polylactic acid (D).   A block copolymer (C) comprising a styrene monomer and a (meth) acrylic acid ester monomer is an ab type block copolymer, the a segment is formed from a styrene monomer, b The segment is formed from a (meth) acrylic acid ester monomer having an alkyl chain having 1 to 4 carbon atoms, and the ratio of the a segment to the b segment is 95/5 to 30/70 by weight. The resin composition according to claim 1.   The molded object which consists of a resin composition in any one of Claims 1-2.