JP5228297B2 - Styrene resin composition and molded article comprising the same - Google Patents

Description

The present invention relates to a styrene resin composition having a low environmental impact and capable of greatly reducing CO ₂ emission during production without deteriorating the excellent impact resistance, heat resistance and molding processability of the styrene resin, and It relates to a molded product.

Styrenic resins are used in a wide range of fields such as electrical and electronic parts, automobiles, general merchandise, and various applications due to their excellent mechanical properties, moldability, and appearance. However, styrene-based resins are made from petroleum resources, and CO ₂ emissions into the atmosphere during production and the environmental impact during disposal have been viewed as problems in recent years. ing.

  Therefore, recently, from the viewpoint of global environmental conservation, biodegradable polymers that are decomposed in the natural environment by the action of microorganisms existing in soil and water have attracted attention, and various biodegradable polymers have been developed. Among them, polylactic acid is relatively inexpensive and has a high melting point of about 170 ° C., and is expected as a biodegradable polymer that can be melt-molded. In addition, lactic acid, which is a monomer, has recently been manufactured at low cost by fermentation using microorganisms, and it has become possible to produce polylactic acid at a much lower cost, so that not only as a biodegradable polymer, Use as a general-purpose polymer has also been studied. However, on the other hand, it has physical defects such as low impact resistance and low flexibility, and an improvement is desired.

  Therefore, a method of mixing polylactic acid and a thermoplastic resin such as polystyrene, polyethylene, polyethylene terephthalate, or polypropylene as an environmentally low load material (Patent Document 1) is disclosed. When mixed by this method, it becomes an environmentally low load material, but in order to use any of them as a general-purpose resin, it was necessary to improve mechanical properties. Although this article mentions a rubber component as an impact modifier, preferred embodiments and examples are not exemplified, and the addition of the styrenic resin of the present invention improves the heat resistance, and further the graft polymer. There is no disclosure of improving impact resistance by addition.

  Furthermore, a biodegradable resin composition (Patent Document 2) containing polylactic acid and an amorphous resin having a glass transition temperature higher than the glass transition temperature of polylactic acid has been disclosed. In addition, it is a polylactic acid resin composition containing polylactic acid in an amount of 50% by weight or more based on the total weight of the resin composition, and a general-purpose resin composition in which a polylactic acid resin is blended with the styrene resin of the present invention Different.

In addition, an aliphatic polyester resin composition containing an aliphatic polyester and a multilayer structure polymer (Patent Document 3), and a graft obtained by graft polymerization of a vinyl monomer to a polylactic acid polymer and a rubber polymer Although a resin composition (Patent Document 4) made of a copolymer is disclosed, these resin compositions do not contain a styrenic resin, and the resulting resin composition is heat resistant. There was a problem, and further improvement was required when used as a general-purpose polymer.
JP-T 6-504799 (page 53) Japanese Patent Laying-Open No. 2005-60637 (second page) JP 2003-286396 A (page 2) JP 2004-285258 A (2nd page)

The present invention has been achieved as a result of studying the solution of the above-described problems in the prior art as an object, and the object is to provide excellent impact resistance, heat resistance and molding processability of the styrene resin. An object of the present invention is to provide an environmentally low-load styrene-based resin composition that can significantly reduce CO ₂ emission during production and a molded product made thereof.

As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by using a resin composition containing a styrene resin, a graft polymer, and polylactic acid at a specific ratio.

That is, the present invention
(1) (A) 0 to 99% by weight of unsaturated carboxylic acid alkyl ester unit, (b) aroma based on the total amount of (A) styrene resin, (B) graft polymer and (C) polylactic acid (C) 0 to 50% by weight of vinyl cyanide units, and (d) 0 to 99% by weight of other vinyl units copolymerizable therewith ( A) 25 to 75% by weight of styrene resin, (r) 10 to 80% by weight of diene rubber polymer, (a) 20 to 90% by weight of unsaturated carboxylic acid alkyl ester unit, (b) aromatic vinyl 0 to 70% by weight of system units, (c) 0 to 50% by weight of vinyl cyanide units, and (d) 0 to 70% by weight of other vinyl units copolymerizable with these (B) Graft polymer (however, (a), (b), (c And (d) is 100% by weight, and (a) the unsaturated carboxylic acid alkyl ester unit is 70% by weight or more) and 5 to 50% by weight (C) polylactic acid is 10 to 65% by weight. In the electron micrograph of the cross section of the styrene resin composition, the area ratio in which the (B) graft polymer is present in (C) polylactic acid is in the range of 10 to 90%. A styrenic resin composition, characterized in that
(2) The styrene resin (25) to 50% by weight, (B) the graft polymer 10 to 50% by weight, and (C) polylactic acid 20 to 55% by weight (1) Styrenic resin composition according to
(3) (A) Styrenic resin is (a) 0 to 70% by weight of unsaturated carboxylic acid alkyl ester unit, (b) 25 to 100% by weight of aromatic vinyl unit, (c) vinyl cyanide unit Any of (1) to (2) , characterized in that 0 to 30% by weight, and (d) 0 to 40% by weight of other vinyl units copolymerizable therewith are copolymerized styrene resins A styrenic resin composition according to claim 1,
(4) (A) Styrenic resin is (a) methyl methacrylate 0-70 wt%, (b) styrene 25-100 wt%, (c) acrylonitrile 0-30 wt%, and (d) N-phenyl The styrene resin composition according to (3) , wherein 0 to 40% by weight of maleimide is a copolymerized styrene resin,
(5) (B) Graft polymer is (r) 10 to 80% by weight of diene rubber polymer, (a) 20 to 90% by weight of methyl methacrylate, (b) 0 to 70% by weight of styrene, and ( c) A styrenic resin composition according to any one of (1) to (4) , wherein the graft polymer is a copolymer obtained by copolymerizing 0 to 50% by weight of acrylonitrile.
(6) A molded product obtained by molding the styrene resin composition according to any one of (1) to (5) ,
(7) The molded article according to (6) , wherein the heat distortion temperature (1.82 MPa) measured according to ASTM D648 is 60 ° C. or higher,
It is.

A styrene resin composition of the present invention and a molded product thereof, wherein (A) a styrene resin, (B) a graft polymer, and (C) a polylactic acid are blended, and (A) styrene Excellent impact resistance, heat resistance, and molding by adjusting the amount of (A) styrene resin to 25 to 75% by weight based on the total amount of the resin, (B) graft polymer, and (C) polylactic acid An environmentally low-load styrene resin composition having processability is obtained.

  The resin composition of the present invention will be specifically described below.

  (A) Styrenic resin used in the present invention includes styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, o-ethylstyrene, p-ethylstyrene, pt-butylstyrene, and the like. (B) It can be obtained by subjecting an aromatic vinyl monomer and a monomer copolymerizable therewith to known bulk polymerization, bulk suspension polymerization, solution polymerization, precipitation polymerization or emulsion polymerization.

  The (A) styrene resin in the present invention does not include (r) a rubbery polymer obtained by graft polymerization of (b) an aromatic vinyl unit or the like. (R) A rubber polymer obtained by graft polymerization of (b) an aromatic vinyl unit or the like is included in (B) the graft polymer described later.

  Specifically, (b) 0 to 99% by weight of unsaturated carboxylic acid alkyl ester unit, (c) 0 to 50% by weight of vinyl cyanide unit, based on 1 to 100% by weight of aromatic vinyl unit. %, And (d) a vinyl copolymer obtained by copolymerizing 0 to 99% by weight of other vinyl units copolymerizable therewith.

  The (a) unsaturated carboxylic acid alkyl ester monomer used for the (A) styrene resin in the present invention is not particularly limited, but an acrylic ester having a C 1-6 alkyl group or substituted alkyl group and Methacrylic acid esters are preferred.

  Specific examples of (a) unsaturated carboxylic acid alkyl ester monomers include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, and n-butyl (meth) acrylate. T-butyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, chloromethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 2- (meth) acrylic acid 2- Hydroxyethyl, 3-hydroxypropyl (meth) acrylate, 2,3,4,5,6-pentahydroxyhexyl (meth) acrylate and 2,3,4,5-tetrahydroxypentyl (meth) acrylate Among them, methyl methacrylate is most preferably used. These can be used alone or in combination of two or more thereof.

  The (c) vinyl cyanide monomer used in the (A) styrene resin in the present invention is not particularly limited, and specific examples include acrylonitrile, methacrylonitrile, ethacrylonitrile, etc., among which acrylonitrile. Is preferably used. These can use 1 type (s) or 2 or more types.

  Examples of other vinyl monomers copolymerizable with (A) styrene resins in the present invention include (a) unsaturated carboxylic acid alkyl ester monomers, and (b) aromatic vinyls. There is no particular limitation as long as it is copolymerizable with a monomer based on (c) vinyl cyanide, and specific examples include N-methylmaleimide, N-ethylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, etc. Maleimide monomers, acrylic acid, methacrylic acid, maleic acid, maleic acid monoethyl ester, maleic anhydride, phthalic acid, itaconic acid and other vinyl monomers having a carboxyl group or a carboxyl anhydride group, acrylic acid 2 -Hydroxyethyl, 2-hydroxyethyl methacrylate, 3-hydroxypropyl acrylate, 3-hydride methacrylate Xylpropyl, 2,3,4,5,6-pentahydroxyhexyl acrylate, 2,3,4,5,6-pentahydroxyhexyl methacrylate, 2,3,4,5-tetrahydroxypentyl acrylate, methacrylic acid 2,3,4,5-tetrahydroxypentyl, 3-hydroxy-1-propene, 4-hydroxy-1-butene, cis-4-hydroxy-2-butene, trans-4-hydroxy-2-butene, 3- Vinyl monomers having a hydroxyl group such as hydroxy-2-methyl-1-propene, cis-5-hydroxy-2-pentene, trans-5-hydroxy-2-pentene, 4,4-dihydroxy-2-butene Glycidyl acrylate, glycidyl methacrylate, glycidyl ethacrylate, glycidyl itaconate, allyl glycidyl Vinyl monomers having an epoxy group such as ether, styrene-p-glycidyl ether and p-glycidyl styrene, acrylamide, methacrylamide, N-methylacrylamide, butoxymethylacrylamide, N-propylmethacrylamide, aminoethyl acrylate, Propylaminoethyl acrylate, dimethylaminoethyl methacrylate, ethylaminopropyl methacrylate, phenylaminoethyl methacrylate, cyclohexylaminoethyl methacrylate, N-vinyldiethylamine, N-acetylvinylamine, allylamine, methallylamine, N-methylallylamine , Vinyl monomers having amino groups such as p-aminostyrene and derivatives thereof, 2-isopropenyl-oxazoline, 2-vinyl-oxazoline 2-acryloyl - oxazoline and 2-styryl - vinyl-based monomer having oxazoline group such as oxazoline and the like, which can be used either alone or in combination.

  (A) Although there is no restriction | limiting in the characteristic of a styrene-type resin, The intrinsic viscosity [(eta)] measured at 30 degreeC using the methyl ethyl ketone solvent is 0.20-2.00 dl / g, Especially 0.25-1. The range of 50 dl / g is preferable because a resin composition having excellent impact resistance and molding processability can be obtained.

The (B) graft polymer used in the present invention is a monomer mixture obtained by adding a vinyl monomer and a monomer copolymerizable therewith in the presence of (r) a diene rubbery polymer. It is obtained by subjecting to known bulk polymerization, bulk suspension polymerization, solution polymerization, precipitation polymerization or emulsion polymerization.

The (B) graft polymer means a copolymer having a vinyl monomer-containing copolymer grafted on a (r) diene rubber polymer and a copolymer containing a vinyl monomer. The polymer includes (r) a structure having a non-grafted structure on the diene rubber polymer.

Specifically, (r) in the presence of 10 to 80% by weight of diene rubbery polymer, (a) 20 to 90% by weight of unsaturated carboxylic acid alkyl ester monomer, (b) aromatic vinyl type Units 0 to 70% by weight, (c) vinyl cyanide units 0 to 50% by weight, and (d) vinyl units obtained by copolymerizing other vinyl units copolymerizable with these units 0 to 70% by weight Graft copolymers are preferred.

The (r) is not particularly limited to the diene-based rubbery polymer, but having a glass transition temperature of 0 ℃ or less may be used. Specific examples of these diene rubber polymers, polybutadiene, styrene - butadiene copolymer, styrene - butadiene block copolymer, acrylonitrile - butadiene copolymer, butyl acrylate - butadiene copolymer, blanking Tajien - methyl methacrylate copolymer, butadiene - ethyl acrylate copolymer, ethylene - propylene - etc. diene copolymer. Among these diene rubbery polymers, polybutadiene, styrene-butadiene copolymer, styrene-butadiene block copolymer and acrylonitrile-butadiene copolymer are particularly preferably used from the viewpoint of impact resistance. It can be used in seeds or a mixture of two or more.

The weight average particle diameter of the (r) diene rubber polymer constituting the (B) graft polymer in the present invention is not particularly limited, but is 0.05 to 1.0 μm, particularly 0.1 to 0.5 μm. It is preferable that it is the range of these. By setting the weight average particle diameter of the rubbery polymer in the range of 0.05 μm to 1.0 μm, excellent impact resistance can be exhibited.

The weight average particle diameter of the (r) diene rubber polymer is alginic acid described in “RubberAge, Vol. 88, p. 484 to 490, (1960), by E. Schmidt, P.H. Biddison”. Sodium method, that is, a method for obtaining a particle size of a cumulative weight fraction of 50% from a creamed weight fraction and a cumulative weight fraction of sodium alginate concentration by utilizing the difference in the diameter of the polybutadiene particles to be creamed depending on the concentration of sodium alginate Can be measured.

  The (a) unsaturated carboxylic acid alkyl ester monomer used in the graft polymer (B) in the present invention is not particularly limited, but an acrylate ester having an alkyl group having 1 to 6 carbon atoms or a substituted alkyl group and Methacrylic acid esters are preferred.

  Specific examples of (a) unsaturated carboxylic acid alkyl ester monomers include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, and n-butyl (meth) acrylate. T-butyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, chloromethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 2- (meth) acrylic acid 2- Hydroxyethyl, 3-hydroxypropyl (meth) acrylate, 2,3,4,5,6-pentahydroxyhexyl (meth) acrylate and 2,3,4,5-tetrahydroxypentyl (meth) acrylate Among them, methyl methacrylate is most preferably used. These can be used alone or in combination of two or more thereof.

  The (b) aromatic vinyl monomer used in the graft polymer (B) in the present invention is not particularly limited, and specific examples include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene. , O-ethyl styrene, p-ethyl styrene, pt-butyl styrene and the like, among which styrene and α-methyl styrene are preferably used. These can use 1 type (s) or 2 or more types.

  The (c) vinyl cyanide monomer used in the graft polymer (B) in the present invention is not particularly limited, and specific examples include acrylonitrile, methacrylonitrile, ethacrylonitrile, etc., among which acrylonitrile. Is preferably used. These can use 1 type (s) or 2 or more types.

  (D) Other vinyl monomers copolymerizable with these used in the graft polymer (B) in the present invention include (a) unsaturated carboxylic acid alkyl ester monomers, and (b) aromatic vinyl. There is no particular limitation as long as it can be copolymerized with a monomer based on (c) vinyl cyanide, but specific examples include N-methylmaleimide, N-ethylmaleimide, N-cyclohexylmaleimide, and N-phenyl. Maleimide monomers such as maleimide, vinyl monomers having a carboxyl group or an anhydride carboxyl group such as acrylic acid, methacrylic acid, maleic acid, maleic acid monoethyl ester, maleic anhydride, phthalic acid and itaconic acid, acrylic 2-hydroxyethyl acid, 2-hydroxyethyl methacrylate, 3-hydroxypropyl acrylate, 3-methacrylic acid Droxypropyl, 2,3,4,5,6-pentahydroxyhexyl acrylate, 2,3,4,5,6-pentahydroxyhexyl methacrylate, 2,3,4,5-tetrahydroxypentyl acrylate, 2,3,4,5-tetrahydroxypentyl methacrylate, 3-hydroxy-1-propene, 4-hydroxy-1-butene, cis-4-hydroxy-2-butene, trans-4-hydroxy-2-butene, Vinyl-based monomers having a hydroxyl group such as 3-hydroxy-2-methyl-1-propene, cis-5-hydroxy-2-pentene, trans-5-hydroxy-2-pentene, 4,4-dihydroxy-2-butene Glycidyl acrylate, glycidyl methacrylate, glycidyl ethacrylate, glycidyl itaconate, allyl glyci Vinyl monomers having an epoxy group such as ether, styrene-p-glycidyl ether and p-glycidyl styrene, acrylamide, methacrylamide, N-methylacrylamide, butoxymethylacrylamide, N-propylmethacrylamide, aminoethyl acrylate, Propylaminoethyl acrylate, dimethylaminoethyl methacrylate, ethylaminopropyl methacrylate, phenylaminoethyl methacrylate, cyclohexylaminoethyl methacrylate, N-vinyldiethylamine, N-acetylvinylamine, allylamine, methallylamine, N-methylallylamine , Vinyl monomers having amino groups such as p-aminostyrene and derivatives thereof, 2-isopropenyl-oxazoline, 2-vinyl-oxazo Down, 2-acryloyl - oxazoline and 2-styryl - vinyl-based monomer having oxazoline group such as oxazoline and the like, which can be used either alone or in combination.

In the present invention, the (B) graft polymer comprises (a) an unsaturated carboxylic acid alkyl ester monoester in the presence of (r) a diene rubbery polymer of 10 to 80% by weight, more preferably 30 to 70% by weight. 20-90% by weight of the monomer, more preferably 30-70% by weight, (b) 0-70% by weight of the aromatic vinyl monomer, more preferably 0-50% by weight, (c) vinyl cyanide 0 to 50% by weight of monomer, more preferably 0 to 30% by weight, (d) 0 to 70% by weight of other vinyl monomers copolymerizable with these, more preferably 0 to 50% % Is obtained by copolymerization. Even if the ratio of the rubbery polymer is less than the above range or exceeds the above range, the impact strength and the surface appearance may be deteriorated.

The (B) graft polymer is composed of (r) a graft copolymer having a structure in which a monomer or a monomer mixture is grafted to a diene rubber polymer, and an ungrafted copolymer. Contains. The graft ratio of the graft polymer is not particularly limited, but is 10 to 100% by weight, particularly 20 to 80% by weight, in order to obtain a resin composition having a good balance between impact resistance and gloss. Is preferred. Here, the graft ratio is a value calculated by the following equation.
Graft rate (%) = [<Amount of vinyl copolymer graft-polymerized to rubbery polymer> / <Rubber content of graft copolymer>] × 100

  The characteristics of the ungrafted copolymer are not particularly limited, but the intrinsic viscosity [η] (measured at 30 ° C.) of the methyl ethyl ketone-soluble component is 0.10 to 1.00 dl / g, particularly 0.20 to 0.00. A range of 80 dl / g is a preferable condition for obtaining a resin composition having excellent impact resistance.

(B) The graft polymer can be obtained by a known polymerization method. For example, it is obtained by a method in which a mixture of a monomer and a chain transfer agent and a solution of a radical generator dissolved in an emulsifier is continuously supplied to a polymerization vessel in the presence of a diene rubber polymer latex and subjected to emulsion polymerization. Can do.

In the present invention , (C) polylactic acid is used .

  The polylactic acid is a polymer mainly composed of L-lactic acid and / or D-lactic acid, but may contain other copolymer components other than lactic acid as long as the object of the present invention is not impaired. .

  Examples of such other copolymer component units include polyvalent carboxylic acids, polyhydric alcohols, hydroxycarboxylic acids, lactones, and the like. Specifically, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid , Azelaic acid, sebacic acid, dodecanedioic acid, fumaric acid, cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid, 5-tetrabutylphosphonium sulfoisophthalic acid Polyhydric carboxylic acids such as ethylene glycol, propylene glycol, butanediol, heptanediol, hexanediol, octanediol, nonanediol, decanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, glycerin, trimethyl Propanediol, pentaerythritol, bisphenol A, aromatic polyhydric alcohols obtained by addition reaction of ethylene oxide with bisphenol, polyhydric alcohols such as diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, glycolic acid, Hydroxycarboxylic acids such as 3-hydroxybutyric acid, 4-hydroxybutyric acid, 4-hydroxyvaleric acid, 6-hydroxycaproic acid, hydroxybenzoic acid, glycolide, ε-caprolactone glycolide, ε-caprolactone, β-propiolactone, δ- Lactones such as butyrolactone, β- or γ-butyrolactone, pivalolactone, and δ-valerolactone can be used. These copolymer components can be used alone or in combination of two or more.

  In order to obtain high heat resistance with polylactic acid, it is preferable that the optical purity of the lactic acid component is high. Among the total lactic acid components, L-form or D-form is preferably contained at 80 mol% or more, and more preferably 90 mol%. It is preferably contained in an amount of 95 mol% or more.

(C) As a method for producing polylactic acid , a known polymerization method can be used. In particular, for polylactic acid, a direct polymerization method from lactic acid, a ring-opening polymerization method via lactide, or the like can be employed.

(C) The molecular weight and molecular weight distribution of polylactic acid are not particularly limited as long as it can be substantially molded, and the weight average molecular weight is preferably 10,000 or more, more preferably 40,000 or more, Particularly preferred is 80,000 or more. The weight average molecular weight herein is a weight average molecular weight in terms of polymethyl methacrylate (PMMA) measured by gel permeation chromatography (GPC) using hexafluoroisopropanol as a solvent.

(C) Melting | fusing point of polylactic acid is not specifically limited, It is preferable that it is 90 degreeC or more, and it is more preferable that it is 150 degreeC or more.

The mixing ratio of (A) styrene resin, (B) graft polymer, and (C) polylactic acid in the styrene resin composition of the present invention is (A) styrene resin, (B) graft polymer, and ( C) the total amount of the polylactic acid, (a) a styrene-based resins 2 5-75 wt%, the good Mashiku 30-60 wt%. The amount of (B) graft polymer added is 5 to 50% by weight, preferably 7 to 50% by weight, and more preferably 10 to 50% by weight. Further (C) amount of polylactic acid 6 5-10 wt%, good Mashiku than to ensure that the range of 50 to 10 wt%, it is possible to obtain a sufficient impact resistance and heat resistance.

The feature of the styrene resin composition in the present invention is composed of (A) a styrene resin, (C) a matrix made of polylactic acid, and (B) a graft polymer domain dispersed in the matrix, At this time, it is preferable that (B) graft polymer which is a domain exists in the range of 10 to 90% of the area ratio which exists in (C) polylactic acid .

  For example, for a molded product obtained by injection molding, a sample obtained by staining an ultrathin section after staining (A) a styrene resin and (B) a graft polymer by an osmium block staining method is applied to a transmission electron microscope. By observing the cross section at a magnification of 6000, the dispersion form of the (B) graft polymer can be confirmed.

Furthermore, the dispersion form of the (B) graft polymer can be changed by changing the composition of the monomer mixture that is graft copolymerized with the (r) diene rubbery polymer of the (B) graft polymer. For example, if (a) the unsaturated carboxylic acid alkyl ester in the monomer mixture is increased, the (B) graft polymer will be dispersed in the (C) polylactic acid phase, and (a) the unsaturated carboxylic acid alkyl ester. It can be confirmed that (B) the graft polymer is less dispersed in the (C) polylactic acid phase and (A) is dispersed in the styrene resin phase.

Here, the area ratio in the cross-sectional photograph in which (B) the graft polymer is present in (C) polylactic acid is in the range of 10 to 90%, preferably 20 to 85%, more preferably 30 to 80%. It is a range. When the area ratio is not in the range of 10 to 90%, the impact resistance is remarkably lowered, which is not preferable.

(B) As a method for measuring the area ratio in which the graft polymer is present in (C) polylactic acid , a cross section of the molded product was photographed with a transmission electron microscope in the same manner as described above. Further expanded by a factor of 4, (C) the area (X) of the dispersed graft polymer in the aliphatic polyester and (A) the area (Y) of the dispersed graft polymer in the styrene resin were cut out from the photograph and weighted. It is obtained according to the formula of (X) / ((X) + (Y)).

In the present invention, from the viewpoint of improving toughness such as impact resistance and tensile elongation at break and heat resistance, it is preferable to further contain (D) a dicarboxylic acid anhydride. (D) The dicarboxylic acid anhydride is a compound having a structure in which water molecules are eliminated from the dicarboxylic acid in the molecule. For example, maleic acid anhydride, itaconic acid anhydride, citraconic acid anhydride, 5 -Norbornene-2,3-dicarboxylic acid anhydride, 1-cyclohexene-1,2-dicarboxylic acid anhydride, cis-4-cyclohexene-1,2-dicarboxylic acid anhydride, succinic acid anhydride, adipic acid anhydride, Cyclohexanedicarboxylic acid anhydride, phthalic acid anhydride, etc. are mentioned, and at least one of maleic acid anhydride, succinic acid anhydride, and phthalic acid anhydride in terms of impact resistance, heat resistance, and moldability. In view of impact resistance and heat resistance, maleic anhydride and succinic anhydride are more preferable, and maleic anhydride is more preferable. In the resin composition of the present invention, (D) the dicarboxylic acid anhydride may exist alone as a compound, and (A) a styrene resin, (B) a graft polymer, and (C). It may react with any one or more of polylactic acid and exist without retaining the structure of dicarboxylic acid anhydride.

In the present invention, by blending (D) dicarboxylic acid anhydride, the phase structure of (A) styrene resin, (B) graft polymer, and (C) polylactic acid is affected, and the strength and impact resistance are affected. Properties such as tensile elongation at break, heat resistance and molding processability are considered to be greatly improved.

In this invention, the compounding quantity of (D) dicarboxylic acid anhydride is 0.01- with respect to 100 weight part of total amounts of (A) styrene resin, (B) graft polymer, and (C) polylactic acid. The amount is 5% by weight, and is preferably 0.05 to 2 parts by weight, more preferably 0.1 to 1 part by weight in terms of impact resistance and heat resistance.

  In the present invention, it is preferable to further contain a crystal nucleating agent from the viewpoint of improving heat resistance.

  As the crystal nucleating agent used in the present invention, those generally used as polymer crystal nucleating agents can be used without particular limitation, and any of inorganic crystal nucleating agents and organic crystal nucleating agents can be used. .

  Specific examples of inorganic crystal nucleating agents include talc, kaolinite, montmorillonite, mica, synthetic mica, clay, zeolite, silica, graphite, carbon black, zinc oxide, magnesium oxide, calcium oxide, titanium oxide, calcium sulfide, and nitriding. Examples thereof include metal salts of boron, magnesium carbonate, calcium carbonate, barium sulfate, aluminum oxide, neodymium oxide, and phenylphosphonate, and talc, kaolinite, montmorillonite, and synthetic mica are preferable from the viewpoint of a large effect of improving heat resistance. . These may be used alone or in combination of two or more. These inorganic crystal nucleating agents are preferably modified with an organic substance in order to enhance dispersibility in the composition.

The content of the inorganic crystal nucleating agent is preferably 0.01 to 100 parts by weight, more preferably 0.05 to 50 parts by weight, and 0.1 to 30 parts by weight with respect to 100 parts by weight of (C) polylactic acid. Is more preferable.

  Specific examples of organic crystal nucleating agents include sodium benzoate, potassium benzoate, lithium benzoate, calcium benzoate, magnesium benzoate, barium benzoate, lithium terephthalate, sodium terephthalate, potassium terephthalate, Calcium oxide, sodium laurate, potassium laurate, sodium myristate, potassium myristate, calcium myristate, sodium octacosanoate, calcium octacosanoate, sodium stearate, potassium stearate, lithium stearate, calcium stearate, magnesium stearate, Barium stearate, sodium montanate, calcium montanate, sodium toluate, sodium salicylate, potassium salicylate, salicylic acid , Metal salts of organic carboxylic acids such as aluminum dibenzoate, potassium dibenzoate, lithium dibenzoate, sodium β-naphthalate, sodium cyclohexanecarboxylate, organic sulfonates such as sodium p-toluenesulfonate, sodium sulfoisophthalate, stearic acid Amide, ethylenebislauric acid amide, palmitic acid amide, hydroxystearic acid amide, erucic acid amide, carboxylic acid amides such as trimesic acid tris (t-butylamide), low density polyethylene, high density polyethylene, polypropylene, polyisopropylene, polybutene Polymers such as poly-4-methylpentene, poly-3-methylbutene-1, polyvinylcycloalkane, polyvinyltrialkylsilane, and high melting point polylactic acid, Sodium salt or potassium salt of a polymer having a carboxyl group such as sodium salt of ethylene-acrylic acid or methacrylic acid copolymer, sodium salt of styrene-maleic anhydride copolymer (so-called ionomer), benzylidene sorbitol and its derivatives, sodium-2, Phosphorus compound metal salts such as 2'-methylenebis (4,6-di-t-butylphenyl) phosphate and sodium 2,2-methylbis (4,6-di-t-butylphenyl) From the viewpoint that the effect of improving the resistance is large, organic carboxylic acid metal salts and carboxylic acid amides are preferred. These may be used alone or in combination of two or more.

The content of the organic crystal nucleating agent is preferably 0.01 to 30 parts by weight, more preferably 0.05 to 10 parts by weight, and 0.1 to 5 parts by weight with respect to 100 parts by weight of (C) polylactic acid. Is more preferable.

  In this invention, it is preferable to contain fillers other than an inorganic crystal nucleating agent from a viewpoint that heat resistance improves.

  As fillers other than the inorganic crystal nucleating agent used in the present invention, fibrous, plate-like, granular, and powdery materials that are usually used for reinforcing thermoplastic resins can be used. Specifically, glass fiber, asbestos fiber, carbon fiber, graphite fiber, metal fiber, potassium titanate whisker, aluminum borate whisker, magnesium whisker, silicon whisker, wollastonite, sepiolite, asbestos, slag fiber, zonolite , Elastadite, gypsum fiber, silica fiber, silica-alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber and boron fiber, etc., inorganic fiber filler, polyester fiber, nylon fiber, acrylic fiber, regenerated cellulose fiber, acetate fiber Organic fiber fillers such as kenaf, ramie, cotton, jute, hemp, sisal, flax, linen, silk, manila hemp, sugar cane, wood pulp, paper waste, waste paper and wool, glass flakes, graphite, metal foil, ceramic beads Sericite, bentonite, dolomite, fine silicic acid, feldspar powder, potassium titanate, shirasu balloon, aluminum silicate, silicon oxide, gypsum, novaculite, include plate-like or particulate filler, such as such as dawsonite and white clay. Among these fillers, inorganic fibrous fillers are preferable, and glass fibers and wollastonite are particularly preferable. Moreover, use of an organic fibrous filler is also preferable, and natural fiber and regenerated fiber are more preferable from the viewpoint of taking advantage of biodegradability of the aliphatic polyester resin. Further, the aspect ratio (average fiber length / average fiber diameter) of the fibrous filler used for blending is preferably 5 or more, more preferably 10 or more, and further preferably 20 or more.

  The filler may be coated or focused with a thermoplastic resin such as an ethylene / vinyl acetate copolymer or a thermosetting resin such as an epoxy resin, or may be a coupling agent such as aminosilane or epoxysilane. It may be processed.

The content of the filler is preferably 0.1 to 200 parts by weight, more preferably 0.5 to 100 parts by weight with respect to 100 parts by weight of (C) polylactic acid .

  In the present invention, it is preferable to further contain a plasticizer from the viewpoint of improving heat resistance.

  As the plasticizer used in the present invention, those generally used as polymer plasticizers can be used without particular limitation. For example, polyester plasticizer, glycerin plasticizer, polyvalent carboxylic ester plasticizer, polyalkylene Examples include glycol plasticizers and epoxy plasticizers.

  Specific examples of the polyester plasticizer include acid components such as adipic acid, sebacic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, propylene glycol, 1,3-butanediol, 1,4-butane. Examples thereof include polyesters composed of diol components such as diol, 1,6-hexanediol, ethylene glycol and diethylene glycol, and polyesters composed of hydroxycarboxylic acid such as polycaprolactone. These polyesters may be end-capped with a monofunctional carboxylic acid or monofunctional alcohol, or may be end-capped with an epoxy compound or the like.

  Specific examples of the glycerin plasticizer include glycerin monoacetomonolaurate, glycerin diacetomonolaurate, glycerin monoacetomonostearate, glycerin diacetomonooleate, and glycerin monoacetomonomontanate.

  Specific examples of polycarboxylic acid plasticizers include phthalates such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate, diheptyl phthalate, dibenzyl phthalate, butyl benzyl phthalate, and trimellitic acid. Trimellitic acid esters such as tributyl, trioctyl trimellitic acid, trihexyl trimellitic acid, sebacic acid esters such as diisodecyl adipate, n-octyl-n-decyl adipate adipate, triethyl acetylcitrate, tributyl acetylcitrate, etc. Citrate esters, azelaic acid esters such as di-2-ethylhexyl azelate, sebacic acid esters such as dibutyl sebacate, and di-2-ethylhexyl sebacate.

  Specific examples of the polyalkylene glycol plasticizer include polyethylene glycol, polypropylene glycol, poly (ethylene oxide / propylene oxide) block and / or random copolymer, polytetramethylene glycol, ethylene oxide addition polymer of bisphenols, bisphenols Polyalkylene glycols such as propylene oxide addition polymers, tetrahydrofuran addition polymers of bisphenols, or end-capped compounds such as terminal epoxy-modified compounds, terminal ester-modified compounds, and terminal ether-modified compounds.

  The epoxy plasticizer generally refers to an epoxy triglyceride composed of an alkyl epoxy stearate and soybean oil, but there are also so-called epoxy resins mainly made of bisphenol A and epichlorohydrin. Can be used.

  Specific examples of other plasticizers include benzoic acid esters of aliphatic polyols such as neopentyl glycol dibenzoate, diethylene glycol dibenzoate, triethylene glycol di-2-ethylbutyrate, fatty acid amides such as stearamide, oleic acid Examples thereof include aliphatic carboxylic acid esters such as butyl, oxyacid esters such as methyl acetylricinoleate and butyl acetylricinoleate, pentaerythritol, various sorbitols, polyacrylic acid esters, silicone oils, and paraffins.

  Among the plasticizers used in the present invention, at least one selected from polyester plasticizers and polyalkylene glycol plasticizers is particularly preferable. The plasticizer used in the present invention may be used alone or in combination of two or more.

The plasticizer content is preferably in the range of 0.01 to 30 parts by weight, more preferably in the range of 0.1 to 20 parts by weight, with respect to 100 parts by weight of (C) polylactic acid , and 0.5 to The range of 10 parts by weight is more preferable.

  In the present invention, each of the crystal nucleating agent and the plasticizer may be used alone, but it is preferable to use both in combination.

In the present invention, it is preferable to further contain a carboxyl group-reactive end-blocking agent from the viewpoint of improving heat resistance and durability by inhibiting hydrolysis.
The carboxyl group-reactive end-blocking agent used in the present invention is not particularly limited as long as it is a compound that can block the carboxyl end group of the polymer, and those used as the carboxyl-terminal blocking agent of the polymer are used. be able to. In the present invention, the carboxyl group-reactive end-blocking agent not only blocks the end of (C) polylactic acid but also has a low acidity such as lactic acid and formic acid generated by thermal decomposition or hydrolysis of naturally-occurring organic fillers. The carboxyl group of the molecular compound can also be blocked. Further, the end-capping agent is more preferably a compound that can also block the hydroxyl end where an acidic low molecular weight compound is generated by thermal decomposition.

  As such a carboxyl group-reactive end-blocking agent, it is preferable to use at least one compound selected from an epoxy compound, an oxazoline compound, an oxazine compound, and a carbodiimide compound, and among them, an epoxy compound and / or a carbodiimide compound are preferable. .

The content of the carboxyl group-reactive end-blocking agent is preferably in the range of 0.01 to 10 parts by weight and more preferably in the range of 0.05 to 5 parts by weight with respect to 100 parts by weight of (C) polylactic acid .

Addition timing of the carboxyl group reactive end capping agent is not particularly limited, not only to improve the heat resistance, in that it can improve the mechanical properties and durability, after melt-kneading (C) and the polylactic acid, It is preferable to knead with a natural organic filler.

  In the present invention, stabilizers (antioxidants, ultraviolet absorbers, weathering agents, etc.), lubricants, mold release agents, flame retardants, colorants including dyes or pigments, antistatic agents, as long as the object of the present invention is not impaired. A foaming agent or the like can be added.

  In the present invention, other thermoplastic resins (for example, polyethylene resin, polypropylene resin, acrylic resin, polyamide resin, polyphenylene sulfide resin, polyether ether ketone resin, polyester resin, polysulfone resin, Ethersulfone resin, aromatic and aliphatic polycarbonate resin, polyarylate resin, polyphenylene oxide resin, polyacetal resin, polyimide resin, polyetherimide resin, chlorinated polyethylene resin, chlorinated polypropylene resin, aromatic and aliphatic polyketone resin, fluorine Resin, polyvinyl chloride resin, polyvinylidene chloride resin, vinyl ester resin, polyurethane resin, cellulose acetate resin, polyvinyl alcohol resin, etc.) or thermosetting resin For example, phenol resin, melamine resin, polyester resin, silicone resin, epoxy resin, etc.) or soft thermoplastic resin (for example, ethylene / glycidyl methacrylate copolymer, polyester elastomer, polyamide elastomer, ethylene / propylene terpolymer, ethylene / butene-1) A polymer or the like) and the like. By blending these resins, a molded product having excellent characteristics can be obtained.

  These additives can be blended at any stage for producing the styrenic resin composition of the present invention. For example, a method of simultaneously adding at least two components of a resin, or two components in advance. There are a method of adding the resin after melt kneading, and a method of adding the resin to one resin first and then melt-kneading and then blending the remaining resin.

The method for producing the styrene resin composition of the present invention is not particularly limited. For example, (A) styrene resin, (B) graft polymer, (C) polylactic acid , and (D ) After dicarboxylic acid anhydride, crystal nucleating agent, filler, plasticizer, and other additives are pre-blended, they are mixed in a solution or a method of uniformly melting and kneading with a single or twin screw extruder above the melting point. A method of removing the solvent later is preferably used.

  In the present invention, the obtained styrenic resin composition can be molded by any method such as generally known injection molding, extrusion molding, inflation molding, blow molding, etc., and can be widely used as a molded product of any shape. it can. Molded products are films, sheets, fibers / clothes, non-woven fabrics, injection molded products, extrusion molded products, vacuum / pressure molded products, blow molded products, or composites with other materials. It is useful for electronic equipment materials, agricultural materials, horticultural materials, fishery materials, civil engineering / building materials, stationery, medical supplies, toilet seats, miscellaneous goods, or other uses. The molded product can also be used after being painted, plated or the like.

  In order to describe the present invention more specifically, examples and comparative examples will be described below, but the present invention is not limited to these examples. In the examples, parts and% indicate parts by weight and% by weight, respectively.

[Reference Example 1] (A) Styrenic Resin A method for preparing a styrene resin is shown below. The polymer obtained was dried under reduced pressure at 70 ° C. for 5 hours, and then a methyl ethyl ketone solution having a concentration of 0.4 g / 100 ml was prepared, and the intrinsic viscosity was measured using an Ubbelohde viscometer at 30 ° C.

  <A-1> PS Japan "HF77" (polystyrene: standard grade) was used. The intrinsic viscosity of the soluble part of methyl ethyl ketone was 0.50 dl / g.

<A-2> A 20-liter capacity stainless steel autoclave equipped with baffles and foudra-type stirring blades, and 0.05 parts by weight of methyl methacrylate / acrylamide copolymer (described in Japanese Patent Publication No. 45-24151) are ion-exchanged. A solution dissolved in 165 parts by weight of water was added and stirred at 400 rpm, and the system was replaced with nitrogen gas. Next, the following mixed substances were added with stirring in the reaction system, and the temperature was raised to 60 ° C. to initiate polymerization.
Styrene 70 parts by weight Acrylonitrile 30 parts by weight t-dodecyl mercaptan 0.2 parts by weight 2,2′-azobisisobutyronitrile 0.4 parts by weight

  After raising the reaction temperature to 65 ° C. over 30 minutes, the temperature was raised to 100 ° C. over 120 minutes. Thereafter, the reaction system was cooled, the polymer was separated, washed, and dried according to the usual method to obtain a bead-shaped polymer. The intrinsic viscosity of the methyl ethyl ketone soluble part of the obtained styrene-based resin was 0.53 dl / g.

  <A-3> Suspension polymerization was similarly performed except that 70 parts by weight of styrene and 30 parts by weight of acrylonitrile in the above <A-2> were changed to 70 parts by weight of methyl methacrylate, 25 parts by weight of styrene, and 5 parts by weight of acrylonitrile. went. The intrinsic viscosity of the methyl ethyl ketone soluble part of the obtained styrene resin was 0.35 dl / g.

  <A-4> 50 parts by weight of styrene, 10 parts by weight of acrylonitrile, 40 parts by weight of N-phenylmaleimide, 0.2 part by weight of t-dodecyl mercaptan, 0.4 part by weight of 2,2′-azobisisobutyronitrile Was solution polymerized in cyclohexanone solvent. Thereafter, the polymer was obtained by cooling the reaction system, reprecipitation with a methanol solution, washing, drying, and pulverization according to a usual method. The intrinsic viscosity of the methyl ethyl ketone soluble part of the obtained styrene resin was 0.33 dl / g.

[Reference Example 2] (B) Graft polymer A method for preparing a graft copolymer is shown below. The graft ratio was determined by the following method. Acetone was added to a predetermined amount (m) of the graft copolymer and refluxed for 4 hours. This solution was centrifuged at 8000 rpm (centrifugal force 10,000 G (about 100 × 10 ³ m / s ² )) for 30 minutes, and the insoluble matter was filtered off. This insoluble matter was dried under reduced pressure at 70 ° C. for 5 hours, and the weight (n) was measured.
Graft ratio = [(n) − (m) × L] / [(m) × L] × 100
Here, L means the rubber content of the graft copolymer.

  The filtrate of the acetone solution was concentrated with a rotary evaporator to obtain a precipitate (acetone soluble matter). The soluble matter was dried under reduced pressure at 70 ° C. for 5 hours, a 0.4 g / 100 ml concentration methyl ethyl ketone solution was prepared, and the intrinsic viscosity was measured using an Ubbelohde viscometer under a temperature condition of 30 ° C.

<B-1>
Polybutadiene (weight average particle size 0.35 μm) 50 parts by weight (Nipol LX111K manufactured by Nippon Zeon Co., Ltd.) (solid content conversion)
Potassium oleate 0.5 parts by weight Glucose 0.5 parts by weight Sodium pyrophosphate 0.5 parts by weight Ferrous sulfate 0.005 parts by weight Deionized water 120 parts by weight The temperature was raised to ° C. The polymerization was started when the internal temperature reached 65 ° C., and 35 parts by weight of methyl methacrylate, 12.5 parts by weight of styrene, 2.5 parts by weight of acrylonitrile, and 0.3 parts by weight of t-dodecyl mercaptan were taken over 5 hours. Continuous dripping. In parallel, an aqueous solution consisting of 0.25 parts by weight of cumene hydroperoxide, 2.5 parts by weight of potassium oleate and 25 parts by weight of pure water was continuously added dropwise over 7 hours to complete the reaction. The obtained graft copolymer latex was coagulated with sulfuric acid, neutralized with caustic soda, washed, filtered and dried to obtain a powder. The graft ratio of the obtained graft copolymer was 40%, and the intrinsic viscosity of methyl ethyl ketone-soluble component was 0.30 dl / g.

  <B-2> 35 parts by weight of methyl methacrylate, 12.5 parts by weight of styrene, and 2.5 parts by weight of acrylonitrile are changed to 42.5 parts by weight of methyl methacrylate and 7.5 parts by weight of styrene. Except that, emulsion polymerization was carried out in the same manner. The graft ratio of the obtained graft copolymer was 42%, and the intrinsic viscosity of the methyl ethyl ketone-soluble component was 0.28 dl / g.

  <B-3> Emulsion polymerization is carried out in the same manner except that 35 parts by weight of methyl methacrylate, 12.5 parts by weight of styrene and 2.5 parts by weight of acrylonitrile are changed to 50 parts of methyl methacrylate. It was. The graft ratio of the obtained graft copolymer was 43%, and the intrinsic viscosity of methyl ethyl ketone-soluble component was 0.27 dl / g.

  <B-4> The same as above except that 35 parts by weight of methyl methacrylate, 12.5 parts by weight of styrene and 2.5 parts by weight of acrylonitrile are changed to 35 parts by weight of styrene and 15 parts by weight of acrylonitrile. Emulsion polymerization was performed. The graft ratio of the obtained graft copolymer was 38%, and the intrinsic viscosity of methyl ethyl ketone-soluble component was 0.33 dl / g.

  <B-5> In the presence of 75 parts (converted to solid content) of polybutadiene latex (average rubber particle diameter 0.09 μm), 2 parts of MAA-BA copolymer is added as solid content and stirred at room temperature for 30 minutes. Thereafter, 1.5 parts of potassium oleate and 0.6 parts of sodium formaldehyde sulfoxylate were charged into the flask, the internal temperature was maintained at 70 ° C., and 13 parts of methyl methacrylate and 2 parts of n-butyl acrylate Then, a mixture of 0.03 part of cumene hydroxyperoxide was added dropwise over 1 hour and held for 1 hour. Thereafter, in the presence of the polymer obtained in the previous stage, as a second stage, a mixture of 17 parts of styrene and 0.034 parts of cumene hydroxyperoxide was added dropwise over 1 hour and then held for 3 hours. Thereafter, in the presence of the polymer obtained in the first stage and the second stage, as a third stage, a mixture of 3 parts of methyl methacrylate and 0.003 part of cumene hydroxyperoxide was added over 0.5 hours. After dropping, the polymerization was terminated after holding for 1 hour. After adding 0.5 part of butylated hydroxytoluene to the obtained graft copolymer latex, it was coagulated with sulfuric acid, washed and dried to obtain a powder. The graft ratio of the obtained graft copolymer was 26%, and the intrinsic viscosity of methyl ethyl ketone-soluble component was 0.26 dl / g.

[Reference Example 3] (C) Polylactic acid <C-1> Poly-L-lactic acid having a weight average molecular weight of 200,000, a D-lactic acid unit of 1%, and a melting point of 175 ° C. was used.

[Reference Example 4] (D) Dicarboxylic anhydride <D-1> Maleic anhydride manufactured by Tokyo Chemical Industry was used.

  <D-2> A succinic anhydride manufactured by Tokyo Chemical Industry was used.

[Reference Example 5] Crystal nucleating agent <E-1>"LMS300"(talc; inorganic crystal nucleating agent) manufactured by Fuji Talc Kogyo was used.

  <E-2> Nippon Kasei's “Slipax L” (ethylenebislauric acid amide; organic crystal nucleating agent) was used.

[Reference Example 6] Filler <F-1> “CS3J948” (glass fiber) manufactured by Nittobo was used.

[Examples 1 to 19 and Comparative Examples 1 to 5 ]
After dry blending the raw materials having the compositions shown in Tables 1 and 2, melt mixing pelletizing was performed using a twin screw extruder (PCM-30 manufactured by Ikegai Kogyo Co., Ltd.) set at an extrusion temperature of 220 ° C.

The pellets obtained in Examples 1 to 15 and Comparative Examples 1 to 5 were obtained by injection molding under the conditions of a molding temperature of 230 ° C. and a mold temperature of 40 ° C. using an IS55EPN injection molding machine manufactured by Toshiba Machine. About the test piece, each characteristic was evaluated with the following measuring methods. The pellets obtained in Examples 16 to 19 were all molded and evaluated in the same manner except that the conditions were changed to a molding temperature of 230 ° C and a mold temperature of 80 ° C.

  [Impact resistance]: The impact resistance was evaluated according to ASTM D256-56A.

  [Heat resistance]: The heat distortion temperature was measured according to ASTM D648 (load: 1.82 MPa).

  [Tensile Properties]: Tensile properties were measured according to ASTM D638.

  [Area ratio]: For a molded product obtained by injection molding, a styrene resin and a graft polymer were stained by an osmium block staining method, and a sample obtained by cutting out an ultrathin section was subjected to a transmission electron microscope (HITACHI, ELECTRON). MICROSCOPE H-700) was magnified 6000 times, and the cross section was observed and photographed. Further expanded by a factor of 4, (C) the area (X) of the dispersed graft polymer in the aliphatic polyester and (A) the area (Y) of the dispersed graft polymer in the styrene resin were cut out from the photograph and weighted. The area ratio was determined according to the formula (X) / ((X) + (Y)).

  Tables 1 and 2 show the measurement results of the impact resistance, heat resistance, tensile properties, and area ratio of the graft polymer present in the aliphatic polyester for each sample, respectively.

From Examples 1 to 10 , the styrene-based resin composition of the present invention was greatly improved by adding (A) a styrene-based resin and (B) a graft polymer to polylactic acid alone (Comparative Example 3 ). Impact resistance can be improved and a practical heat-resistant temperature can be achieved.

In particular, Examples 1 to 3 show that the impact resistance can be improved as the proportion of (B) graft polymer in (C) aliphatic polyester increases.

Even more Example 1 1 to 1 5, the styrenic resin composition of the present invention, by adding (D) a dicarboxylic acid anhydride, significantly impact resistance, toughness and heat resistance, such as tensile elongation at break It can be seen that it can be improved.

Further, from Examples 16 to 19 , even when a nucleating agent or a filler is further added to the styrene resin composition of the present invention, the heat resistance can be improved while having good impact resistance.

On the other hand, it can be seen from Comparative Examples 4 and 5 that when the styrenic resin deviates from the scope of the present invention, the impact resistance can be greatly improved, but the heat resistance is low, so it is not practical.

  It can be used as materials for automobiles, materials for electric / electronic devices, materials for agriculture, materials for horticulture, materials for fishing, civil engineering / building materials, stationery, medical supplies, toilet seats, miscellaneous goods, or other uses.

Claims (7)

(A) 0 to 99% by weight of unsaturated carboxylic acid alkyl ester unit, (b) aromatic vinyl based on the total amount of (A) styrene resin, (B) graft polymer and (C) polylactic acid (A) Styrene in which 1 to 100% by weight of units, (c) 0 to 50% by weight of vinyl cyanide units, and (d) 0 to 99% by weight of other vinyl units copolymerizable therewith 25 to 75% by weight of a resin, (r) 10 to 80% by weight of a diene rubber polymer, (a) 20 to 90% by weight of an unsaturated carboxylic acid alkyl ester unit, and (b) an aromatic vinyl unit 0 (B) Graft polymer obtained by graft polymerization of ˜70 wt%, (c) 0 to 50 wt% of vinyl cyanide units, and (d) 0 to 70 wt% of other vinyl units copolymerizable therewith (However, (a), (b), (c) and The total amount of (d) is 100% by weight, and (a) the unsaturated carboxylic acid alkyl ester unit is 70% by weight or more) and 5 to 50% by weight (C) 10 to 65% by weight of polylactic acid. In the electron micrograph of the cross section of the styrene resin composition, the area ratio in which the (B) graft polymer is present in (C) polylactic acid is in the range of 10 to 90%. A styrene-based resin composition characterized by being. The (A) styrene resin is 25 to 50% by weight, the (B) graft polymer is 10 to 50% by weight, and (C) polylactic acid is 20 to 55% by weight. Styrenic resin composition. (A) Styrenic resin is (a) 0 to 70% by weight of unsaturated carboxylic acid alkyl ester unit, (b) 25 to 100% by weight of aromatic vinyl unit, (c) vinyl cyanide unit 0 to 30 3. The styrene resin according to claim 1, wherein the styrene resin is copolymerized by weight% and (d) 0 to 40% by weight of other vinyl units copolymerizable therewith. Styrenic resin composition. (A) Styrenic resin comprises (a) methyl methacrylate 0-70% by weight, (b) styrene 25-100% by weight, (c) acrylonitrile 0-30% by weight, and (d) N-phenylmaleimide 0- The styrene resin composition according to claim 3 , wherein 40% by weight is a copolymerized styrene resin. (B) Graft polymer is (r) 10 to 80% by weight of diene rubber polymer, (a) 20 to 90% by weight of methyl methacrylate, (b) 0 to 70% by weight of styrene, and (c) acrylic. The styrenic resin composition according to any one of claims 1 to 4 , which is a graft polymer obtained by copolymerizing 0 to 50% by weight of nitrile. A molded article formed by molding the styrene resin composition according to any one of claims 1 to 5 . The molded article according to claim 6 , wherein the heat distortion temperature (1.82 MPa) measured according to ASTM D648 is 60 ° C or higher.