JP2014194005A - Thermoplastic resin composition and molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoplastic resin composition which has excellent heat resistance, moldability, and impact resistance while containing polylactic acid in the amount of 25 mass% or more.SOLUTION: A resin composition comprises a polylactic acid resin (A) having the D-form either in the amount of 2.0 mol% or less or in the amount of 98.0 mol% or more, a rubber-reinforced styrenic resin (B), and tin oxide (D). A mass ratio, [(A)/(B)], of the polylactic acid (A) and the rubber-reinforced styrenic resin (B) is 25/75 to 85/15. The tin oxide (D) is contained in the amount of 0.005 to 10 pts.mass relative to total 100 pts.mass of the polylactic acid (A) and the rubber-reinforced styrenic resin (B).

Description

  The present invention comprises a thermoplastic resin composition comprising a polylactic acid resin and a rubber-reinforced styrene-based resin, each having a D-form content satisfying a specific range, and containing tin oxide (D), and the resin composition. The present invention relates to a molded body.

  Rubber-reinforced styrene-based resins such as acrylonitrile butadiene styrene (ABS) resin and rubber-reinforced polystyrene (HIPS) are excellent in appearance, impact resistance, heat resistance, and moldability, and are widely used in the fields of electrical and electronic equipment, automobiles, etc. Has been. However, such a resin uses petroleum as a raw material, and recently, for the purpose of reducing the environmental load, a resin composition in which a plant-derived biomass resin such as a polylactic acid resin is blended with an ABS resin is required.

However, polylactic acid generally has lower impact resistance and heat resistance than ABS resin, and is incompatible with ABS resin. Therefore, if the amount is too large, the appearance and impact resistance of ABS resin is excellent.・ There is a problem that performance such as heat resistance and moldability is impaired.
Therefore, Patent Document 1 and Patent Document 2 disclose resin compositions having good appearance and impact resistance by blending an acrylic resin with polylactic acid and ABS resin. However, in these resin compositions, particularly heat resistance and moldability are still insufficient.

JP 2006-45485 A JP 2006-137908 A

  The present invention solves the above problems and provides a thermoplastic resin composition having excellent heat resistance, moldability, and impact resistance while being a resin composition containing 25% by mass or more of polylactic acid. This is a technical challenge.

The inventor of the present invention has reached the present invention as a result of intensive studies in order to solve the above problems. That is, the gist of the present invention is as follows.
(1) Contains polylactic acid resin (A), rubber-reinforced styrene resin (B), and tin oxide (D) having a D-form content of 2.0 mol% or less or 98.0 mol% or more The mass ratio [(A) / (B)] of the polylactic acid resin (A) and the rubber-reinforced styrene resin (B) is 25/75 to 85/15, A thermoplastic resin characterized by containing 0.005 to 10 parts by mass of tin (D) with respect to a total of 100 parts by mass of the polylactic acid resin (A) and the rubber-reinforced styrene resin (B). Composition.
(2) Further, an impact modifier (G) is contained, and the impact modifier (G) with respect to a total of 100 parts by mass of the polylactic acid resin (A) and the rubber-reinforced styrene resin (B). The thermoplastic resin composition as described in (1) which contains 0.5-10 mass parts.
(3) The polylactic acid resin (A) has a D-form content of 0.1 to 0.6 mol%, or 99.4 to 99.9 mol%, according to (1) or (2) Thermoplastic resin composition.
(4) A molded product comprising the thermoplastic resin composition according to any one of (1) to (3).

Since the thermoplastic resin composition of the present invention is mainly composed of a polylactic acid resin and a rubber-reinforced styrene resin, it has excellent impact resistance. And since the D-form content uses the polylactic acid resin (A) in a specific range, the crystal performance is improved by improving the stereoregularity, and the heat resistance and moldability are significantly improved. In addition, the impact resistance is further improved. Furthermore, the thermoplastic resin composition of the present invention can further improve the crystal performance of the polylactic acid resin (A) and also improve the wet heat durability by containing tin oxide (D). .
Thus, by further improving the crystal performance and wet heat durability of the polylactic acid resin (A), the crystal performance and wet heat durability of the thermoplastic resin composition of the present invention are also improved, and the heat resistance and moldability are further improved. In addition, impact resistance and wet heat durability are further improved.
Furthermore, although the impact resistance of the thermoplastic resin composition can be improved by containing the impact resistance improver (G), the impact resistance becomes more prominent when used together with tin oxide (D). Can be improved.
And since the thermoplastic resin composition of the present invention uses a natural product-derived resin, it can contribute to the saving of depleted resources such as petroleum, and has an extremely high industrial utility value. Furthermore, it is possible to obtain various molded articles such as electric and electronic equipment parts and miscellaneous goods molded articles using the thermoplastic resin composition of the present invention.

Hereinafter, the present invention will be described in detail. The thermoplastic resin composition of the present invention comprises a polylactic acid resin (A), a rubber-reinforced styrene resin (B), and tin oxide (D).
First, the polylactic acid resin (A) will be described. The polylactic acid resin (A) needs to have a D-form content of 2.0 mol% or less or a D-form content of 98.0 mol% or more. Among them, it is preferably 1.5 mol% or less, or preferably 98.5 mol% or more, more preferably 0.6 mol% or less, or 99.4 mol% or more. preferable. When the D-form content is within this range, the crystallinity is excellent. That is, not only the crystallization speed is high, but also the crystallization is sufficiently easy to proceed, so that it is possible to obtain a molded body having excellent heat resistance.
Moreover, it becomes what is further excellent in crystallinity by containing the tin oxide (D) mentioned later. And about wet heat durability, although it is an effect which improves mainly by containing the tin oxide (D) mentioned later, when D body content uses the polylactic acid resin (A) of this range, Improves wet heat durability. If the polylactic acid resin has a D-form content outside this range, it will be difficult to sufficiently improve both the crystallinity and wet heat durability even if tin oxide (D) is contained.
Thus, since tin oxide (D) has a high effect of improving the performance of the polylactic acid resin (A), it may be contained in the polylactic acid resin (A) among the thermoplastic resin compositions. It is preferable.

  In the present invention, the D-form content of the polylactic acid resin (A) is a ratio (mol%) occupied by the D lactic acid unit in the total lactic acid units constituting the polylactic acid resin (A). Therefore, for example, in the case of a polylactic acid resin (A) having a D-form content of 1.0 mol%, the polylactic acid resin (A) has a proportion of 1.0 mol% of D lactic acid units, and L lactic acid The proportion of units is 99.0 mol%.

  In the present invention, the D-form content of the polylactic acid resin (A) is, as will be described later in the Examples, methylated all of L-lactic acid and D-lactic acid obtained by decomposing the polylactic acid resin (A), It is calculated by a method of analyzing the methyl ester of L lactic acid and the methyl ester of D lactic acid with a gas chromatography analyzer.

  In consideration of the moldability of the resin composition of the present invention, the polylactic acid resin (A) has a melt flow rate (measured at 190 ° C. under a load of 2.16 kg) of 0.1 to 50 g / 10 min. Among them, 0.2 to 40 g / 10 min is particularly preferable. When the melt flow rate exceeds 50 g / 10 min, the melt viscosity is too low and the molded article tends to be inferior in mechanical properties and heat resistance. When the melt flow rate is less than 0.1 g / 10 minutes, the load during the molding process becomes too high and the operability may be lowered.

  As polylactic acid resin (A) used for this invention, polylactic acid resin of the range which D body content prescribes | regulates by this invention among various commercially available polylactic acid resins can be used. In addition, among lactides, which are cyclic dimers of lactic acid, L-lactide having a sufficiently low D-form content or D-lactide having a sufficiently low L-form content is used as a raw material, and a known melt polymerization method is used. Alternatively, those produced by further using a solid phase polymerization method can be used.

  Moreover, the polylactic acid resin (A) of the present invention may have a crosslinked structure introduced therein. As a method for introducing a crosslinked structure, it is preferable to employ a method of blending a (meth) acrylic acid ester compound and a peroxide.

  Next, the rubber reinforced styrene resin (B) will be described. Rubber copolymer styrene resin (B3) obtained by graft copolymerization or random copolymerization of styrene resin (B1) and rubber resin (B2), and styrene resin (B1) is rubber resin (B2) or the rubber copolymer. This refers to the resin (B4) mixed with the polymerized styrene resin (B3).

  The styrene resin (B1) is a resin mainly composed of a styrene monomer, and is obtained by copolymerizing other monomers and / or rubber resins copolymerizable with these as required.

  Examples of the styrene monomer constituting the styrene resin (B1) include styrene, α-methyl styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, vinyl xylene, ethyl styrene, dimethyl styrene, p-tert- Examples thereof include styrene derivatives such as butylstyrene, vinylnaphthalene, methoxystyrene, monobromostyrene, dibromostyrene, fluorostyrene, and tribromostyrene. Of these, styrene and α-methylstyrene are preferable. These may be used alone or in combination of two or more.

  Other monomers that can be copolymerized with styrenic monomers include vinyl cyanide compounds such as acrylonitrile and methacrylonitrile, aryl esters of (meth) acrylic acid such as phenyl acrylate and benzyl acrylate, methyl acrylate, ethyl acrylate, and propyl acrylate. , Butyl acrylate, amyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, cyclohexyl acrylate, alkyl ester of (meth) acrylic acid such as dodecyl acrylate, epoxy group-containing methacrylic acid ester such as glycidyl methacrylate, maleimide, N-methyl Maleimide monomers such as maleimide and N-phenylmaleimide, acrylic acid, methacrylic acid, maleic acid, maleic anhydride Phthalic acid, alpha, such as itaconic acid, beta-unsaturated carboxylic acids and their anhydrides, and the like. These may be used alone or in combination of two or more.

  The content of styrene in the styrene resin (B1) is not particularly limited, but is preferably 40% by mass or more.

  The rubber-based resin (B2) refers to a resin excellent in stretchability mainly composed of synthetic rubber. Examples of the rubber resin (B2) include polybutadiene, polyisoprene, styrene / butadiene copolymer, acrylonitrile / butadiene copolymer, (meth) acrylic acid alkyl ester / butadiene copolymer, acrylonitrile / isoprene copolymer, ( Copolymers of ethylene and α-olefin such as (meth) acrylic acid alkyl ester / isoprene copolymers, diene copolymers such as butadiene / isoprene copolymers, ethylene / propylene copolymers, ethylene / butene copolymers, etc. Copolymers, copolymers of ethylene and unsaturated carboxylic acid esters such as ethylene / (meth) acrylate copolymers and ethylene / butyl acrylate copolymers, ethylene and aliphatic carboxylates such as ethylene / vinyl acetate copolymers Copolymer with ethylene, propylene, hexadie Copolymers such as copolymers of ethylene, propylene and non-conjugated dienes, acrylic rubbers such as polybutyl acrylate, polyorganosiloxane rubbers and polyalkyl (meth) acrylate rubbers entangled with each other so that they cannot be separated. Examples thereof include a composite rubber having a structure (hereinafter abbreviated as IPN type rubber). These copolymers may be random copolymers or block copolymers.

  The rubber-reinforced styrene resin (B) in the present invention is a rubber copolymer styrene resin (B3) obtained by graft copolymerization or random copolymerization of the styrene resin (B1) with the rubber resin (B2). The styrene resin (B1) is a resin (B4) mixed with the rubber resin (B2) or the rubber copolymer styrene resin (B3). Specific examples of the rubber copolymer styrene resin (B3) include acrylonitrile / butadiene / styrene resin (hereinafter abbreviated as ABS), methyl methacrylate / butadiene / styrene resin (hereinafter abbreviated as MBS), and the like. Styrene / butadiene / styrene resin, hydrogenated styrene / butadiene / styrene resin, hydrogenated styrene / isoprene / styrene resin, impact-resistant polystyrene, methyl methacrylate / acrylonitrile / butadiene / styrene resin (hereinafter abbreviated as MABS), acrylonitrile. Examples thereof include acrylic rubber / styrene resin, acrylonitrile / ethylene propylene rubber / styrene resin, and rubber-reinforced styrene resin of styrene / IPN type rubber copolymer. Among these, as the rubber-reinforced styrene resin (B), an ABS resin is preferable from the viewpoint of moldability and impact resistance.

  The mass ratio [(A) / (B)] of the polylactic acid resin (A) and the rubber-reinforced styrene resin (B) in the thermoplastic resin composition needs to be 25/75 to 85/15. Especially, it is preferable that it is 30 / 70-70 / 30. If the mass ratio of the polylactic acid resin (A) is reduced and the mass ratio of [(A) / (B)] is out of the above range, the environmental merit is reduced. On the other hand, if the mass ratio of the polylactic acid resin (A) increases and falls outside the above range, the impact resistance and heat resistance improvement effect by the rubber-reinforced styrene resin (B) cannot be obtained.

  Furthermore, it is preferable that the thermoplastic resin composition of the present invention contains an acrylic compatibilizer (C). The acrylic compatibilizer (C) improves the compatibility of the polylactic acid resin (A) and the rubber-reinforced styrene resin (B), and as a result, can improve impact resistance and mechanical strength.

  Examples of the acrylic compatibilizer (C) include (meth) acrylic copolymers, copolymers of styrene monomers and (meth) acrylic monomers, acrylic olefin compounds, and the like. Among these, a (meth) acrylic copolymer is preferable because compatibility can be remarkably improved and impact resistance and mechanical strength can be improved.

  The (meth) acrylic copolymer is obtained by polymerizing a (meth) acrylic monomer alone or by copolymerizing two or more (meth) acrylic monomers. As the (meth) acrylic monomer, the alkyl group (including cycloalkyl group) such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, and isobornyl methacrylate has 1 carbon atom. -18 (meth) acrylic acid alkyl ester monomers, (meth) acrylic acid aryl ester monomers such as phenyl methacrylate, (meth) acrylic acid aralkyl ester monomers such as benzyl methacrylate, and the like. These may be used alone or in combination of two or more. Of these, methyl methacrylate is preferred as the (meth) acrylic monomer, and polymethyl methacrylate is preferred as the (meth) acrylic copolymer.

  The copolymer of a styrene monomer and a (meth) acrylic monomer is obtained by copolymerizing a styrene monomer and a monomer constituting the (meth) acrylic copolymer. Examples of styrenic monomers include styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, vinylxylene, ethylstyrene, dimethylstyrene, p-tert-butylstyrene, vinylnaphthalene, methoxystyrene, Examples thereof include styrene derivatives of monobromostyrene, dibromostyrene, fluorostyrene, and tribromostyrene. Of these, styrene, α-methylstyrene and the like are preferable. These may be used alone or in combination of two or more.

  An acrylic olefin compound is a modified olefin compound obtained by graft copolymerization of a (meth) acrylic acid ester polymer. As a commercial item, NOF Corporation Modiper etc. are mentioned, for example.

  The content of the acrylic compatibilizing agent (C) in the thermoplastic resin composition of the present invention is 0.000 relative to a total of 100 parts by mass of the polylactic acid resin (A) and the rubber-reinforced styrene resin (B). The amount is preferably 5 to 20 parts by mass, and more preferably 3 to 15 parts by mass. When the content of the acrylic compatibilizer (C) is less than 0.5 parts by mass, it is difficult to improve the compatibility between the polylactic acid resin (A) and the rubber-reinforced styrene resin (B), and impact resistance And the effect of improving heat resistance is reduced. On the other hand, when the content exceeds 20 parts by mass, impact resistance and formability tend to deteriorate.

The thermoplastic resin composition of the present invention further contains tin oxide (D). Examples of tin oxide (D) used in the present invention include SnO (stannous oxide), SnO ₂ (stannic oxide), SnO _{3 and the} like. Among them, it is preferable to use SnO ₂ because it is relatively easy to obtain. Further, tin oxide (D) may be in a crystalline state or an amorphous state. Tin oxide (D) improves the crystallinity and wet heat durability of polylactic acid resin (A) by containing a specific amount in polylactic acid resin (A) having a D-form content in a specific range as described above. be able to.

  The content of tin oxide (D) needs to be 0.005 to 10 parts by mass with respect to a total of 100 parts by mass of the polylactic acid resin (A) and the rubber-reinforced styrene resin (B). The amount is preferably 0.01 to 5 parts by mass, and more preferably 0.02 to 3 parts by mass. When the content of tin oxide (D) is less than 0.005 parts by mass, it is difficult to improve the crystallinity and wet heat durability of the polylactic acid resin (A). On the other hand, when the amount exceeds 10 parts by mass, the specific gravity of the resin composition increases, the use is restricted, and the surface of the resulting molded article is inferior in quality such as a glare sensation.

  The average particle diameter of tin oxide (D) is not particularly limited, but is preferably 1 μm to 10 μm, more preferably 2 μm to 5 μm. If the average particle size is less than 1 μm, the polylactic acid resin is easily decomposed because it easily absorbs moisture. On the other hand, when the average particle size is too small, it is not preferable because aggregation tends to occur and dispersibility deteriorates. On the other hand, if the particle diameter is too large, the surface area becomes small, and the effect of improving the crystallinity and wet heat durability as described above is not preferable.

  For the tin oxide (D), it is preferable to use particles formed only of tin oxide, but metal oxides other than tin oxide, or particles having a metal or polymer surface coated with tin oxide are also used. be able to. Alternatively, particles made of tin oxide (D) doped with an element such as indium or antimony may be used. Even when such tin oxide (D) is used, the content of only tin oxide satisfies the above range.

  In addition, as a method for measuring the content of tin oxide (D) in the thermoplastic resin composition of the present invention, a method for measuring the amount of tin in the resin composition by inductively coupled plasma (ICP) measurement, a resin composition Are dissolved in a solvent or the like, the resin is removed, and the remaining inorganic component is analyzed by X-ray analysis or by an Auger microprobe.

It is preferable that the thermoplastic resin composition of the present invention further contains an impact resistance improver (G). In the present invention, the impact resistance is significantly improved by using the impact resistance improver (G) together with tin oxide (D).
The impact resistance improver (G) is preferably at least one of the core-shell type graft copolymer (G1) and the (meth) acrylic acid ester polymer (G2).

First, the core-shell type graft copolymer (G1) will be described.
The core-shell type graft copolymer (G1) is composed of a core layer and a shell layer covering the core layer, and adjacent layers are composed of different polymers. Each of the core layer and the shell layer may have a plurality of layers. The core-shell type graft copolymer (G1) is preferably obtained by graft polymerization of the shell layer component in the presence of the core layer component.

  In the present invention, the core-shell type graft copolymer (G1) is preferably selected from butadiene rubber, acrylic rubber, and silicone rubber from the viewpoint of improving impact resistance.

The butadiene rubber that forms the core component is a polymer composed of only 1,3-butadiene monomer, or one or more vinyl monomers that are copolymerizable with 1,3-butadiene monomer. It is a polymer comprising a monomer.
The content of the one or more vinyl monomers in the butadiene rubber is preferably 50% by mass or less, and more preferably 30% by mass or less.
Examples of vinyl monomers copolymerizable with 1,3-butadiene monomer include aromatic vinyl compounds such as styrene and α-methylstyrene, alkyl methacrylates such as methyl methacrylate and ethyl methacrylate, ethyl acrylate, n -Alkyl acrylates such as butyl acrylate, unsaturated nitriles such as acrylonitrile and methacrylonitrile, vinyl ethers such as methyl vinyl ether and butyl vinyl ether, vinyl halides such as vinyl chloride and vinyl bromide, vinylidene chloride and vinylidene bromide Examples thereof include vinyl monomers having a glycidyl group such as vinylidene halide, glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, and ethylene glycol glycidyl ether.

  In addition to the above, aromatic polyfunctional vinyl compounds such as divinylbenzene and divinyltoluene, polyhydric alcohols such as ethylene glycol dimethacrylate and 1,3-butanediol diacrylate, trimethacrylates, triacrylates, acrylics Crosslinkable monomers (crosslinking agents) such as carboxylic acid allyl esters such as allyl acid and allyl methacrylate, diallyl compounds such as diallyl phthalate and diallyl sebacate, and triallyl compounds such as triallyl triazine can be used. These can be used alone or in admixture of two or more.

The acrylic rubber forming the core component preferably contains 50 to 100% by mass of the main structural unit acrylate, and more preferably 70 to 100% by mass. In the acrylic rubber, the other component than the acrylic ester is preferably a vinyl monomer copolymerizable with the acrylic ester.
Examples of the acrylic acid ester constituting the acrylic rubber include an acrylic acid alkyl ester having an alkyl group having 2 to 8 carbon atoms, and examples thereof include ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, and the like.

  Examples of vinyl monomers copolymerizable with acrylic esters include aromatic vinyl compounds such as styrene and α-methylstyrene, alkyl methacrylates such as methyl methacrylate and ethyl methacrylate, and unsaturated groups such as acrylonitrile and methacrylonitrile. Vinyl ethers such as nitrile, methyl vinyl ether and butyl vinyl ether, vinyl halides such as vinyl chloride and vinyl bromide, vinylidene halides such as vinylidene chloride and vinylidene bromide, glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, ethylene glycol glycidyl ether, etc. And vinyl monomers having a glycidyl group.

The silicone rubber forming the core component is a rubber containing polyorganosiloxane which is a linear polymer having an organosiloxane bond unit of several thousand or more, and contains polyorganosiloxane and alkyl (meth) acrylate rubber. Including silicone / acrylic rubber. The rubber may be produced by any method, but the emulsion polymerization method is optimal.
The structure of the polyorganosiloxane is not particularly limited, but is preferably a polyorganosiloxane containing a vinyl polymerizable functional group. Examples of the dimethylsiloxane used in the production of the polyorganosiloxane include a dimethylsiloxane-based cyclic body having a 3-membered ring or more, and a 3- to 7-membered ring is preferable. Specific examples include hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, and the like. These may be used alone or in combination of two or more.

  In the present invention, the shell component constituting the core-shell type graft copolymer (G1) is an unsaturated carboxylic acid alkyl ester unit, a glycidyl group-containing vinyl unit, an aliphatic vinyl unit, an aromatic vinyl unit, or vinyl cyanide. It is preferably formed of a polymer containing a system unit, a maleimide system unit, an unsaturated dicarboxylic acid system unit, an unsaturated dicarboxylic acid anhydride system unit, and / or another vinyl system unit. Among them, a polymer containing an unsaturated carboxylic acid alkyl ester unit, a glycidyl group-containing vinyl unit and / or an unsaturated dicarboxylic acid anhydride unit is preferable, and a polymer containing an unsaturated carboxylic acid alkyl ester unit is preferable. Is more preferable.

  As the unsaturated carboxylic acid alkyl ester unit constituting the polymer of the shell component, (meth) acrylic acid alkyl ester is preferably used. Specifically, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, (meth) acrylic N-hexyl acid, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, stearyl (meth) acrylate, octadecyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, ( Chloromethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2,3,4,5,6 (meth) acrylic acid -Pentahydroxyhexyl, 2,3,4,5-tetrahydroxypentyl (meth) acrylate, amino acid acrylate Examples include ethyl, propylaminoethyl acrylate, dimethylaminoethyl methacrylate, ethylaminopropyl methacrylate, phenylaminoethyl methacrylate, cyclohexylaminoethyl methacrylate, etc., from the viewpoint that the effect of improving dispersibility in the resin is great. , Methyl (meth) acrylate and n-butyl (meth) acrylate are preferably used. These units can be used alone or in combination of two or more.

  The glycidyl group-containing vinyl-based unit constituting the polymer of the shell component is not particularly limited, but is glycidyl (meth) acrylate, glycidyl itaconate, diglycidyl itaconate, allyl glycidyl ether, styrene-4-glycidyl ether. 4-glycidylstyrene and the like, and glycidyl (meth) acrylate is preferably used from the viewpoint that the effect of improving impact resistance is great. These units can be used alone or in combination of two or more.

  Examples of the aliphatic vinyl units constituting the polymer of the shell component include ethylene, propylene, butadiene and the like. Examples of aromatic vinyl units include styrene, α-methylstyrene, 1-vinylnaphthalene, 4-methylstyrene, 4-propylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2-ethyl-4-benzylstyrene, 4 -(Phenylbutyl) styrene, halogenated styrene, etc. are mentioned. Examples of the vinyl cyanide unit include acrylonitrile, methacrylonitrile, ethacrylonitrile and the like. The maleimide units include maleimide, N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-isopropylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N- (p-bromophenyl) maleimide, N- And (chlorophenyl) maleimide. Examples of unsaturated dicarboxylic acid units include maleic acid, maleic acid monoethyl ester, itaconic acid, and phthalic acid.

  Other vinyl units constituting the polymer of the shell component include acrylamide, methacrylamide, N-methylacrylamide, butoxymethylacrylamide, N-propylmethacrylamide, N-vinyldiethylamine, N-acetylvinylamine, allylamine, meta Examples include allylamine, N-methylallylamine, p-aminostyrene, 2-isopropenyl-oxazoline, 2-vinyl-oxazoline, 2-acryloyl-oxazoline, 2-styryl-oxazoline. These units can be used alone or in combination of two or more.

  Among the core-shell type graft copolymers (G1) obtained by combining the core layer and the shell layer as described above, the following three core-shell type graft copolymers (G1-1) to (G1-3) are impact resistant. The effect of improving the property is excellent, and (G1-1) described below is particularly preferable.

The core-shell type graft copolymer (G1-1) is a composite polymer in which the core layer is composed of an acrylic component and a silicone component, and the shell layer is a heavy polymer having an unsaturated carboxylic acid alkyl ester unit or a vinyl unit. Among them, a polymer containing methyl (meth) acrylate or a glycidyl group-containing vinyl-based unit is preferable.
Examples of commercially available core-shell type graft copolymers (G1-1) include Metablene S-2001, Metabrene S-2006, and Metabrene S-2200 manufactured by Mitsubishi Rayon Co., Ltd.

The core-shell type graft copolymer (G1-2) is a polymer in which the core layer is a butadiene-based rubber and the shell layer has an unsaturated carboxylic acid alkyl ester-based unit. Among them, the core layer is preferably a methyl methacrylate / butadiene copolymer rubber, and the shell layer is preferably a polymer having a methyl (meth) acrylate unit.
Commercially available products of the core-shell type graft copolymer (G1-2) include Metablene C-223A manufactured by Mitsubishi Rayon Co., Ltd., Kaneace B-564 manufactured by Kaneka Co., Ltd. and Paraloid BPM-520 manufactured by Rohm and Haas Co.

The core-shell type graft copolymer (G1-3) is made of a polymer in which the core layer contains an acrylic rubber and the shell layer contains an unsaturated carboxylic acid alkyl ester unit. In particular, the shell layer grafts one or more unsaturated carboxylic acid alkyl ester units, particularly methyl (meth) acrylate, onto the core layer acrylic rubber in the presence of the core layer acrylic rubber. It is preferable that it is obtained by polymerizing.
Examples of commercially available core-shell impact modifiers (G1-3) include Rohm and Haas Paraloid BPM-500, Paraloid BPM-515, Mitsubishi Rayon Metabrene W-450A, and Metabrene W-600A.

  Next, the (meth) acrylic acid ester polymer (G2) will be described. As a monomer which comprises a (meth) acrylic acid ester polymer, acrylic acid and its ester, methacrylic acid and its ester are mentioned, for example. These monomers may be used independently and may be used in combination of 2 or more type. Examples of the copolymer include a block copolymer, a random copolymer, a graft copolymer, or a combination thereof.

Specific examples of (meth) acrylic acid and its esters include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, and n-butyl (meth) acrylate. , Isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, neopentyl (meth) acrylate, ethylhexyl (meth) acrylate, isodecyl acrylate, lauryl (meth) acrylate , Tridecyl (meth) acrylate, stearyl (meth) acrylate, benzyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, methoxyethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, (meth ) Chloroethyl acrylate, Trifluoro (meth) acrylate Ethyl, (meth) heptadecafluorooctyl acrylate, isobornyl (meth) acrylate, and (meth) adamantyl acrylate and (meth) tricycloalkyl Desi sulfonyl acrylate. Further, monomers such as substituted styrene such as styrene, α-methylstyrene, t-butylstyrene and chlorostyrene may be copolymerized.
What is necessary is just to produce a (meth) acrylic acid ester-type copolymer using a well-known method.

  As a 1st preferable aspect of a (meth) acrylic acid ester polymer (G2), the ultrahigh molecular weight (meth) acrylic acid ester polymer whose weight average molecular weight is 500,000 or more and less than 10 million is mentioned. By using an ultra high molecular weight (meth) acrylic acid ester polymer having a weight average molecular weight in the above range, impact resistance is remarkably improved and flexibility is improved. If the weight average molecular weight is less than 500,000, the effect of improving impact resistance and flexibility cannot be obtained sufficiently. On the other hand, when the weight average molecular weight exceeds 10,000,000, the compatibility of the resulting resin composition is impaired, or the melt viscosity becomes too high and it becomes difficult to handle. The weight average molecular weight of such a (meth) acrylic acid ester polymer is more preferably 800,000 to 8 million, and still more preferably 1 million to 5 million.

  Commercially available products of the (meth) acrylic acid ester polymer of the first preferred embodiment include, for example, the Metabrene P series manufactured by Mitsubishi Rayon Co., Ltd., the PARALOID K series manufactured by Rohm & Haas Co., and Kaneace PA manufactured by Kaneka Corporation. Series.

As a second preferred embodiment of the (meth) acrylic acid ester-based polymer, a block copolymer of methyl methacrylate and n-butyl acrylate (hereinafter referred to as block copolymer P) can be mentioned. By using this block copolymer P, impact resistance is remarkably improved, and flexibility and impact resistance against falling ball impact and falling weight impact are also improved. Since the effect of improving the flexibility and impact resistance is sufficiently obtained, the proportion of the n-butyl acrylate monomer in the monomer constituting the block copolymer P is preferably 60% by mass or more, 75 mass% or more is more preferable.
The block copolymer P has a molecular chain composed of a hard block composed of 1 to 5 methyl methacrylate units and a soft block composed of 1 to 5 n-butyl acrylate units. Is preferred.

  The hard block composed of methyl methacrylate units in the molecular chain of the block copolymer P contributes to good compatibility with the polylactic acid resin (A) and the rubber-reinforced styrene resin (B). The soft block composed of n-butyl acrylate units in the molecular chain of the block copolymer P contributes to improvement in flexibility and impact resistance.

  As a commercial item of the block copolymer P of a 2nd preferable aspect, for example, the brand name "Kuraray LA2140e" (content of n-butyl acrylate is 77 mass%) made by Kuraray, the brand name made by Kuraray “Clarity LA2250” (content of n-butyl acrylate is 67% by mass).

In view of the effect of imparting impact resistance to the resin composition, the content of the impact resistance improver (G) in the polylactic acid resin composition of the present invention is such that the polylactic acid resin (A) and the rubber-reinforced styrene system 0.5-10 mass parts is preferable with respect to a total of 100 mass parts with resin (B), 1-9 mass parts is more preferable, and 3-8 mass parts is especially preferable.
When the content of the impact resistance improver (G) is less than 0.5 parts by mass, sufficient impact resistance cannot be imparted to the resin composition. On the other hand, when the content of the impact resistance improver (G) exceeds 10 parts by mass, the impact resistance improving effect is saturated, and the crystallinity of the resin composition is lowered.

  And it is preferable that the carbodiimide compound contains in the thermoplastic resin composition of this invention. Although it is known that when a carbodiimide compound is added to a polylactic acid resin, the wet heat durability of the polylactic acid resin is improved, in the present invention, the polylactic acid resin (A) having a D-form content in a specific range, tin oxide By using together with (D), wet heat durability is remarkably improved.

  Various compounds can be used as the carbodiimide compound. As specific compounds, N, N′-di-2,6-diisopropylphenylcarbodiimide, N, N′-di-o-tolylcarbodiimide, N, N′-diphenylcarbodiimide, N, N′-dioctyldecylcarbodiimide, N, N'-di-2,6-dimethylphenylcarbodiimide, N-tolyl-N'-cyclohexylcarbodiimide, N, N'-di-2,6-di-tert-butylphenylcarbodiimide, N-tolyl-N ' -Phenylcarbodiimide, N, N'-di-p-nitrophenylcarbodiimide, N, N'-di-p-aminophenylcarbodiimide, N, N'-di-p-hydroxyphenylcarbodiimide, N, N'-di- Cyclohexylcarbodiimide, N, N'-di-p-tolylcarbodiimide, p-phenylene-bis-di-o-to Carbodiimide, p-phenylene-bis-dicyclohexylcarbodiimide, hexamethylene-bis-dicyclohexylcarbodiimide, ethylene-bis-diphenylcarbodiimide, N, N'-benzylcarbodiimide, N-octadecyl-N'-phenylcarbodiimide, N-benzyl-N '-Phenylcarbodiimide, N-octadecyl-N'-tolylcarbodiimide, N-cyclohexyl-N'-tolylcarbodiimide, N-phenyl-N'-tolylcarbodiimide, N-benzyl-N'-tolylcarbodiimide, N, N'- Di-o-ethylphenylcarbodiimide, N, N'-di-p-ethylphenylcarbodiimide, N, N'-di-o-isopropylphenylcarbodiimide, N, N'-di-p-isopropylphenylcarbodiimide Diimide, N, N'-di-o-isobutylphenylcarbodiimide, N, N'-di-p-isobutylphenylcarbodiimide, N, N'-di-2,6-diethylphenylcarbodiimide, N, N'-di- 2-ethyl-6-isopropylphenylcarbodiimide, N, N'-di-2-isobutyl-6-isopropylphenylcarbodiimide, N, N'-di-2,4,6-trimethylphenylcarbodiimide, N, N'-di -2,4,6-triisopropylphenylcarbodiimide, N, N'-di-2,4,6-triisobutylphenylcarbodiimide, diisopropylcarbodiimide, dimethylcarbodiimide, diisobutylcarbodiimide, dioctylcarbodiimide, t-butylisopropylcarbodiimide, di- β-naphthylcarbodi De, and the like di -t- butyl carbodiimide

Among these compounds, those commercially available include, for example, monocarbodiimide having one carbodiimide group in the same molecule, such as EN-160 manufactured by Matsumoto Yushi Co., Ltd. Examples thereof include polycarbodiimide having two or more carbodiimide groups in the same molecule, such as EN-180 manufactured by Yushi Co., Ltd., Stavacsol P manufactured by Rhein Chemie, and Carbodilite LA-1 manufactured by Nisshinbo Industries, Ltd.
Among these, monocarbodiimide has a high effect of improving the heat and moisture resistance of the polylactic acid resin when used in combination with stannic oxide, and it is particularly preferable to use N, N′-di-2,6-diisopropylphenylcarbodiimide. Examples of commercially available monocarbodiimides include EN160 manufactured by Matsumoto Yushi Co., Stabuzol I manufactured by Rhein Chemie, Fortezol manufactured by Chuo Kasei Co., Ltd., and the like.

  The content of the carbodiimide compound is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass in total of the polylactic acid resin (A) and the rubber-reinforced styrene resin (B). Especially, it is preferable that it is 0.5-8.0 mass parts, and it is more preferable that it is 1.0-5.0 mass parts. When the content of the carbodiimide compound is less than 0.1 part by mass, the effect of improving wet heat durability as described above cannot be obtained. On the other hand, when the content of the carbodiimide compound exceeds 10 parts by mass, not only the effect is saturated but also other physical properties such as strength reduction are adversely affected.

  Since the thermoplastic resin composition of the present invention uses a polylactic acid resin (A) having a D-form content in a specific range, the crystallinity is sufficiently improved without adding a crystal nucleating agent. It is. However, a crystal nucleating agent may be contained for the purpose of further improving crystallinity (mainly crystallization speed).

  Specific compounds that can be used as the crystal nucleating agent are selected from organic amide compounds, organic hydrazide compounds, carboxylic acid ester compounds, organic sulfonates, phthalocyanine compounds, melamine compounds, and organic phosphonates. It is preferable to use one or more. Among these, organic sulfonates, organic amide compounds, and organic phosphonates are preferable from the viewpoint of crystallization speed.

  As the organic sulfonate, various compounds such as sulfoisophthalate can be used, and among them, dimethyl metal salt of 5-sulfoisophthalic acid is preferable from the viewpoint of the effect of promoting crystallization. Furthermore, barium salt, calcium salt, strontium salt, potassium salt, rubidium salt, sodium salt and the like are preferable. Examples of commercially available products include LAK403 manufactured by Takemoto Yushi Co., Ltd.

  Various kinds of organic amide compounds can be used. Among these, N, N ′, N ″ -tricyclohexyltrimesic acid amide, N, N ′ are preferred from the viewpoint of dispersibility in the resin and heat resistance. -Ethylene bis (12-hydroxystearic acid) amide is preferable, and examples of commercially available products include AS-AT-530SF manufactured by Ito Oil Co., Ltd.

As the organic phosphonate, phenyl phosphonate is preferred from the viewpoint of the effect of promoting crystallization. The metal salt of phenylphosphonic acid is a metal salt of phenylphosphonic acid having a phenyl group which may have a substituent and a phosphone group (—PO (OH) ₂ ), and the substituent of the phenyl group includes carbon. Examples thereof include an alkyl group having 1 to 10 carbon atoms and an alkoxycarbonyl group having 1 to 10 carbon atoms in the alkoxy group. Specific examples of phenylphosphonic acid include unsubstituted phenylphosphonic acid, methylphenylphosphonic acid, ethylphenylphosphonic acid, propylphenylphosphonic acid, butylphenylphosphonic acid, dimethoxycarbonylphenylphosphonic acid, and diethoxycarbonylphenylphosphonic acid. And unsubstituted phenylphosphonic acid is preferred. Of these, zinc phenylphosphonate is particularly preferable.

  Examples of the metal salt of phenylphosphonic acid include salts of lithium, sodium, magnesium, aluminum, potassium, calcium, barium, copper, zinc, iron, cobalt, nickel, etc. Among these metal salts, a zinc salt is selected. It is preferable. Examples of commercially available products include Eco Promote (zinc phenylphosphonate) manufactured by Nissan Chemical Co., Ltd.

  In the thermoplastic resin composition of the present invention, the content of the above crystal nucleating agent is 0.03 to 5 parts per 100 parts by mass in total of the polylactic acid resin (A) and the rubber-reinforced styrene resin (B). The amount is preferably part by mass, more preferably 0.1 to 4 parts by mass, and most preferably 0.5 to 3 parts by mass. When the content of the crystal nucleating agent is less than 0.03 parts by mass, the effect of improving the crystallinity of the polylactic acid resin (A) is poor. On the other hand, when the content exceeds 5 parts by mass, the effect as a crystal nucleating agent is saturated, which is not only economically disadvantageous, but also increases the residue after biodegradation, which is not preferable in terms of environment.

  The thermoplastic resin composition of the present invention includes a plasticizer, a heat stabilizer, an antioxidant, a filler, a pigment, a weathering agent, a flame retardant, a lubricant, a release agent, and a charge, as long as the effects of the present invention are not impaired. Additives such as inhibitors can be added.

  As the plasticizer, polyester plasticizers, glycerin plasticizers, polycarboxylic acid ester plasticizers, phosphate ester plasticizers, polyalkylene glycol plasticizers, epoxy plasticizers, and the like can be used.

Examples of heat stabilizers and antioxidants include hindered phenols, phosphorus compounds, hindered amines, sulfur compounds, copper compounds, alkali metal halides, and vitamin E.
Examples of the filler include inorganic fillers and organic fillers. Inorganic fillers include talc, zinc carbonate, wollastonite, silica, aluminum oxide, magnesium oxide, calcium silicate, sodium aluminate, calcium aluminate, sodium aluminosilicate, magnesium silicate, glass balloon, carbon black, zinc oxide , Antimony trioxide, zeolite, metal fiber, metal whisker, ceramic whisker, potassium titanate, boron nitride, graphite, glass fiber, carbon fiber and the like. Examples of the organic filler include naturally occurring polymers such as starch, cellulose fine particles, wood flour, okara, fir shell, bran, kenaf, and modified products thereof.

As the flame retardant, a halogen-based flame retardant, a phosphorus-based flame retardant, and an inorganic flame retardant can be used. However, in consideration of the environment, it is desirable to use a non-halogen flame retardant. Non-halogen flame retardants include phosphorus flame retardants, hydrated metal compounds (aluminum hydroxide and magnesium hydroxide), N-containing compounds (melamine and guanidine), and inorganic compounds (borate and Mo compounds). It is done.
As the lubricant, various carboxylic acid compounds can be used, and among them, various fatty acid metal salts, particularly magnesium stearate, calcium stearate and the like are preferable.
As the release agent, various carboxylic acid compounds, among them, various fatty acid esters, various fatty acid amides, and the like are preferably used.

In the thermoplastic resin composition of the present invention, polylactic acid resin (A) and rubber-reinforced styrene-based resin (B) are contained as main resin components. Other resins may be contained. Examples thereof include polycarbonate, polyamide, polyester, polyolefin, polyphenylene ether and the like.
The ratio of the total amount of the polylactic acid resin (A) and the rubber-reinforced styrene resin (B) in the thermoplastic resin composition of the present invention is preferably 70% by mass or more, and more preferably 80% by mass or more. It is preferable that

  Next, the manufacturing method of the thermoplastic resin composition of this invention is demonstrated. The thermoplastic resin composition of this invention can be obtained by supplying each component which comprises a thermoplastic resin composition in an extruder, and melt-kneading. However, tin oxide (D) and additives used as necessary (impact resistance improver (G), carbodiimide compound and crystal nucleating agent) are preferably contained in the polylactic acid resin (A). It is preferable to employ a method of adding at the time of polymerization of the polylactic acid resin (A), a method of adding tin oxide (D) or an additive used as necessary to the polylactic acid resin (A) and melt-kneading.

  In addition, in the case of the method of adding at the time of polymerization of the polylactic acid resin (A), a vertical reactor or a horizontal reactor equipped with a helical ribbon blade, a high-viscosity stirring blade or the like is used as a reaction vessel for performing melt ring-opening polymerization. Can be used alone or in parallel. In addition, the reaction vessel may be a continuous type, a batch type or a semi-batch type, or a combination thereof.

  In the case of the method of adding to the polylactic acid resin (A) by melt kneading, after dry blending the polylactic acid resin (A) and tin oxide (D) and additives used as necessary, Examples thereof include a method of supplying to a general kneader and a molding machine, a method of supplying from the top of the kneader using a plurality of feeders, and a method of adding from the middle of melt kneading using a side feeder.

  In the melt-kneading, when the polylactic acid resin (A) and tin oxide (D) and the like are melt-kneaded as described above, the polylactic acid resin (A), the rubber-reinforced styrene resin (B), and if necessary acrylic In the case of simultaneously adding the compatibilizing agent (C) and tin oxide (D), a general kneader such as a single screw extruder, a twin screw extruder, a roll kneader, or a Brabender can be used. From the viewpoint of improving mixing uniformity and dispersibility, it is preferable to use a twin screw extruder.

  Next, the molded article of the present invention is molded using the above-described thermoplastic resin composition of the present invention. Especially, it is preferable that it is a molded object shape | molded using only the thermoplastic resin composition of this invention.

  Examples of the molded article of the present invention include various molded articles obtained by a known molding method such as injection molding, blow molding, and extrusion molding using the thermoplastic resin composition of the present invention. Since the thermoplastic resin composition of the present invention has a high crystallization rate, it is possible to shorten the molding cycle when obtaining a molded body, and is excellent in molding processability.

As an injection molding method, in addition to a general injection molding method, gas injection molding, injection press molding, or the like can be adopted. In the present invention, as an example of suitable injection molding conditions, the cylinder temperature is equal to or higher than the melting point (Tm) or flow start temperature of the polylactic acid resin, preferably in the range of 180 to 230 ° C, and optimally in the range of 190 to 220 ° C. It is. If the cylinder temperature is too low, it tends to cause molding failure or overload of the device due to a decrease in fluidity of the resin. On the other hand, if the cylinder temperature is too high, the polylactic acid resin is decomposed, and problems such as a decrease in strength of the molded product and coloring may occur.
In the present invention, the mold temperature at the time of injection molding is preferably (Tg-10) ° C. or lower when the temperature is set to Tg (glass transition temperature) or lower of the resin composition. Moreover, in order to accelerate | stimulate crystallization for the purpose of the rigidity of a resin composition, and heat resistance improvement, it can also be Tg or more and (Tm-30) degreeC or less.

  Examples of the blow molding method include a direct blow method in which molding is performed directly from raw material chips, an injection blow molding method in which blow molding is performed after a preformed body (bottom parison) is first molded by injection molding, and a stretch blow molding method. Etc. In addition, any of a hot parison method in which blow molding is continuously performed after forming the preform, and a cold parison method in which the preform is cooled and taken out and then heated again to perform blow molding can be employed.

  As the extrusion molding method, a T-die method, a round die method, or the like can be applied. The extrusion molding temperature must be equal to or higher than the melting point or flow start temperature of the raw polylactic acid resin, and is preferably in the range of 180 to 230 ° C, more preferably 190 to 220 ° C. If the molding temperature is too low, there are problems that the operation becomes unstable and that overload tends to occur. On the other hand, if the molding temperature is too high, the polylactic acid resin is decomposed, and problems such as a decrease in strength and coloration of the extruded molded product occur.

  And a sheet | seat, a pipe, etc. can be produced by extrusion molding. Specific applications of the sheet or pipe obtained by the extrusion method include: deep drawing raw sheet, batch-type foam original sheet, credit cards and other cards, underlays, clear files, straws, agriculture / horticulture Hard pipes for use. In addition, the sheet can be further subjected to deep drawing such as vacuum forming, pressure forming and vacuum / pressure forming to produce food containers, agricultural / horticultural containers, blister pack containers and press-through pack containers. it can.

  The molded article of the present invention obtained by the molding method as described above has excellent heat resistance, moldability, impact resistance, wet heat durability and the like possessed by the thermoplastic resin composition of the present invention. It can be suitably used for parts. Specific examples of automotive parts include bumper members, instrument panels, trims, torque control levers, safety belt parts, register blades, washer levers, window regulator handles, window regulator handle knobs, passing light levers, sun visor brackets, Console box, trunk cover, spare tire cover, ceiling material, floor material, inner plate, seat material, door panel, door board, steering wheel, rearview mirror housing, air duct panel, wind molding fastener, speed cable liner, sun visor bracket, Headrest rod holders, various motor housings, various plates, various panels, etc.

In addition, it can be suitably used for applications such as office equipment that requires these performances, housings for home appliances, and various parts. Specific examples of office equipment include a front cover, a rear cover, a paper feed tray, a paper discharge tray, a platen, an interior cover, and a toner cartridge in a casing of a printer, a copying machine, a fax machine, and the like. In addition, it can be suitably used for various applications that require wet heat durability, such as electrical / electronic parts, medical care, food, household / office supplies, office automation equipment, building material-related parts, and furniture parts.
As the molded article of the present invention, other than the above, dishes such as dishes, bowls, bowls, chopsticks, spoons, forks, knives; fluid containers; container caps; rulers, writing instruments, clear cases, CD cases, etc. Office supplies; daily necessities such as kitchen corners, trash cans, washbasins, toothbrushes, combs, hangers; agricultural and horticultural materials such as flower pots and nursery pots; various toys such as plastic models.

Hereinafter, the present invention will be described more specifically with reference to examples. The measurement and evaluation of various characteristic values in the examples were performed as follows.
(1) D-form content of polylactic acid resin 0.3 g of the obtained resin composition was weighed, added to 6 mL of 1N potassium hydroxide / methanol solution, and sufficiently stirred at 65 ° C. Next, 450 μL of sulfuric acid was added and stirred at 65 ° C. to decompose polylactic acid, and 5 mL was measured as a sample.
To this sample, 3 mL of pure water and 13 mL of methylene chloride were mixed and shaken. After stationary separation, about 1.5 mL of the lower organic layer was collected, filtered through a HPLC disk filter having a pore size of 0.45 μm, and then subjected to gas chromatography measurement using HP-6890 Series GC system manufactured by Hewlett Packard. The ratio (%) of the peak area of D-lactic acid methyl ester to the total peak area of lactic acid methyl ester was calculated, and this was defined as the D-form content (mol%) of the polylactic acid resin (A).
(2) Melt flow rate (MFR) of polylactic acid resin
According to JIS K-7210, it measured in the load of 190 degreeC and 21.2N.
(3) Thermal deformation temperature (heat resistance)
Using the obtained test piece, the heat distortion temperature (DTUL) was measured at a load of 0.45 MPa in accordance with ISO 75-1,2.

(4) Molding cycle (crystallization speed)
The time from when the resin composition is injected into the mold (filling, holding pressure) and cooling, when the test piece is obtained, until the molded body can be taken out without being fixed to the mold. (Time counted from the time of injection: second) or time until the molded body can be removed from the mold without resistance (time counted from the time of injection: second) was defined as a molding cycle. The upper limit molding cycle at that time was 180 seconds.
(5) Bending strength retention (wet heat durability)
Using the obtained test piece, in accordance with ISO178, a load was applied at a deformation rate of 2 mm / min to measure the bending rupture strength (the bending rupture strength before wet heat treatment). After the test piece of the resin composition to which no carbodiimide compound was added was exposed to a high temperature and high humidity environment of 60 ° C. and 95% RH for 300 hours, the bending fracture strength of the test piece was measured in the same manner as described above (wet Bending fracture strength after heat treatment). On the other hand, the molded piece of the resin composition to which the carbodiimide compound was added was exposed to a high-temperature and high-humidity environment of 60 ° C. and 95% RH for 3000 hours, and then the bending fracture strength of the test piece was measured in the same manner as described above (wet Bending fracture strength after heat treatment). And based on the following formula | equation, the bending fracture strength retention was computed.
Bending strength retention (%) = [(Bending strength after wet heat treatment) / (Bending strength before wet heat treatment)] × 100
(6) Impact resistance of injection-molded body The obtained thermoplastic resin composition was subjected to a cylinder temperature of 160 to 200 ° C. and a mold temperature of 100 ° C. using an injection molding machine (manufactured by Nissei Resin Co., Ltd., NEX-110 type). A test piece with a V-shaped cut was obtained by setting. And according to ISO 179-1, Charpy impact strength was measured using the obtained test piece.

Various raw materials used in Examples and Comparative Examples are as follows.
[Polylactic acid resin]
A-1: D-form content = 0.1 mol%, MFR = 8 (manufactured by Toyota Motor Corporation; S-12)
A-2: D-form content = 1.4 mol%, MFR = 10 (Unitika Ltd .; TE-4000)
X-1: D-form content = 4.0 mol%, MFR = 4 (manufactured by Nature Works; 4042D)
[Rubber reinforced styrene resin]
B-1: Techno ABS 170 (ABS resin) manufactured by Techno Polymer Co., Ltd.
[Acrylic compatibilizer]
C-1: Mitsubishi Rayon Acrypet VH-001 (polymethyl methacrylate resin)
[Tin compounds]
D-1: stannic oxide (IV) (manufactured by Showa Kako)
Y-1: Tin powder (Kishida Chemical Co., Ltd.)
Y-2: stannous chloride (Ishizu Pharmaceutical)

[Crystal nucleating agent]
E-1: Barium organic sulfonate crystal nucleating agent (Takemoto Yushi Co., Ltd .; LAK403)
[Carbodiimide compound]
F-1: Monocarbodiimide compound (Matsumoto Yushi Co., Ltd .; EN160)
[Impact resistance improver]
G-1: Core-shell type graft copolymer (core component: acrylic rubber, shell component: (meth) methyl acrylate polymer) (manufactured by Rohm and Haas; Paraloid BPM-515)
G-2: Core-shell type graft copolymer (core component: silicone / acrylic rubber, shell component: polymer having a glycidyl group-containing vinyl-based unit) (manufactured by Mitsubishi Rayon Co., Ltd .; Metabrene S-2200)
G-3: Core-shell type graft copolymer (core component: butadiene rubber, shell component: (meth) methyl acrylate polymer) (manufactured by Kaneka Corporation; Kane Ace B-564)
G-4: (meth) acrylic acid ester copolymer of ultra high molecular weight (manufactured by Mitsubishi Rayon Co., Ltd .; Methbrene P-531, weight average molecular weight 4.5 million)
G-5: Methyl methacrylate / n-butyl acrylate copolymer (manufactured by Kuraray Co., Ltd .; Clarity LA2140e, content of n-butyl acrylate 77 mass%)
G-6: Methyl methacrylate / n-butyl acrylate copolymer (Kuraray Co., Ltd .; Clarity LA2250, content of n-butyl acrylate: 67% by mass)

Example 1
Polylactic acid resin (A-1), rubber-reinforced styrene resin (B-1), acrylic compatibilizer (C-1), and tin oxide (D-1) were used in the amounts shown in Table 1, and these were dry blended. Then, it was supplied from the root supply port of a twin screw extruder (TEM 26SS type manufactured by Toshiba Machine Co., Ltd.), and melt kneaded under the conditions of barrel temperature 190 ° C., screw rotation speed 150 rpm, and discharge 15 kg / h. After melt-kneading, a strand is extruded from a 0.4 mm diameter × 3 hole die, cut into a pellet, and is dried at a temperature of 60 ° C. with a vacuum dryer (trade name “Vacuum Dryer DP83” manufactured by Yamato Kagaku). Drying treatment was performed for 48 hours to obtain a thermoplastic resin composition.
The obtained thermoplastic resin composition is set to a cylinder temperature of 160 to 200 ° C. and a mold temperature of 100 ° C. using an injection molding machine (Nissei Resin Co., Ltd., NEX-110 type). A test piece was prepared.

Examples 2-13, Comparative Examples 1-11
A thermoplastic resin composition was prepared in the same manner as in Example 1 except that the types and addition amounts of polylactic acid resin, rubber-reinforced styrene resin, acrylic compatibilizer, and tin compound were changed as shown in Tables 1 and 2. Obtained. And the test piece for a general physical property measurement was produced like Example 1 using the obtained thermoplastic resin composition.

Examples 14-16, Comparative Example 12
The types and addition amounts of polylactic acid resin, rubber-reinforced styrene resin, acrylic compatibilizer, and tin compound were changed as shown in Tables 1 and 2, and crystal nucleating agents were added in the amounts shown in Tables 1 and 2. Except for the above, a thermoplastic resin composition was obtained in the same manner as in Example 1. And the test piece for a general physical property measurement was produced like Example 1 using the obtained thermoplastic resin composition.

Examples 17 to 33, Comparative Examples 13 to 26
Thermoplastic resin in the same manner as in Example 1 except that the types and amounts of addition of polylactic acid resin, rubber-reinforced styrene resin, acrylic compatibilizer, tin compound and impact modifier are changed as shown in Table 3. A composition was obtained. And the test piece for a general physical property measurement was produced like Example 1 using the obtained thermoplastic resin composition.

Examples 34 to 35, Comparative Examples 27 to 29
The types and addition amounts of polylactic acid resin, rubber-reinforced styrene resin, acrylic compatibilizer, and tin compound were changed as shown in Table 4, and the crystal nucleating agent and carbodiimide compound were added in the amounts shown in Table 4. Obtained a thermoplastic resin composition in the same manner as in Example 1. And the test piece for a general physical property measurement was produced like Example 1 using the obtained thermoplastic resin composition.

Example 36
A glass tube was charged with L-lactide and tin oxide (D-1) and heated to 150 ° C. in a nitrogen atmosphere. When the contents were melted, stirring was started, the internal temperature was further raised to 190 ° C. and polymerization (melt polymerization) was performed for 2 hours, and then the polymerization reaction product was taken out. The obtained polymerization reaction product was vacuum-dried at 130 ° C. for 30 hours to remove lactide remaining in the polymerization reaction product. In this way, a polylactic acid resin composition containing tin oxide (D-1) was obtained. Then, a rubber-reinforced styrene resin (B-1) and an acrylic compatibilizer (C-1) were added to the polylactic acid resin composition, and the thermoplastics having the compositions shown in Table 4 were obtained in the same manner as in Example 1. A resin composition was obtained. And the test piece for a general physical property measurement was produced like Example 1 using the obtained thermoplastic resin composition.

  Tables 1 to 4 show the compositions, characteristic values, and evaluation results of the thermoplastic resin compositions obtained in Examples 1 to 36 and Comparative Examples 1 to 29.

As is clear from Table 1, the thermoplastic resin compositions obtained in Examples 1 to 36 have a short molding cycle when obtaining molded articles, and the obtained molded articles have a high thermal deformation temperature. It was excellent in heat resistance. Further, the obtained molded body had high Charpy impact strength and excellent impact resistance, had a high bending rupture strength retention rate, and had excellent wet heat durability.
Especially, since the thermoplastic resin composition of Examples 17-33 was a combination of tin oxide and an impact resistance improver, the impact resistance was greatly improved by a synergistic effect with tin oxide.
Moreover, since the thermoplastic resin compositions of Examples 14 to 19 were a combination of tin oxide and an organic crystal nucleating agent, the crystallinity was further improved, the molding cycle was shortened, and the obtained molded bodies were It was also superior in heat resistance, and also had a high bending rupture strength retention and improved wet heat durability.
Furthermore, since the thermoplastic fat compositions of Examples 18 to 19 were a combination of tin oxide and a carbodiimide compound, the wet heat durability was greatly improved by the synergistic effect of both, and the resulting molded bodies were high in temperature for 3000 hours. The bending rupture strength retention after high humidity treatment was high.

On the other hand, since the thermoplastic resin compositions of Comparative Examples 1 and 9 to 11 did not contain tin oxide, the thermoplastic resin composition of Comparative Example 2 contained a tin compound other than tin oxide. The crystallization rate was slow, the molding cycle was long, and the heat resistance was poor. In Comparative Example 3, since stannous chloride was used instead of tin oxide, the viscosity decreased during melt kneading, and a resin composition could not be obtained. Since the thermoplastic resin composition of Comparative Example 4 contained too much tin oxide, the dispersibility of tin oxide deteriorated, and the resulting molded article had a poor appearance such as a rough surface. The thermoplastic resin composition of Comparative Example 5 was inferior in impact resistance because the content of the rubber-reinforced styrene resin was small. Since the thermoplastic resin composition of Comparative Example 6 contained too little polylactic acid resin, it could not be a resin composition with a low environmental load. The thermoplastic resin compositions of Comparative Examples 7-8, 12, and 29 contained tin oxide because the D-form content of the polylactic acid resin was outside the scope of the present invention, but the crystallization speed was high. It was slow, the molding cycle was long, the heat resistance was inferior, and the impact resistance and wet heat durability were also inferior.
Although the thermoplastic resin compositions of Comparative Examples 13 to 26 contained an appropriate amount of an impact resistance improver, they did not contain tin oxide, so the impact resistance improvement effect was not sufficient and crystallization occurred. The speed was slow, the molding cycle was long, and the heat resistance was poor. The thermoplastic resin compositions of Comparative Examples 27 and 28 contained a crystal nucleating agent and a carbodiimide compound, but did not contain tin oxide, so compared with Examples 34 and 35, the molding cycle, heat resistance, The wet heat durability was poor.

Claims (4)

It contains a polylactic acid resin (A) having a D-form content of 2.0 mol% or less, or 98.0 mol% or more, a rubber-reinforced styrene resin (B), and tin oxide (D). A resin composition having a mass ratio [(A) / (B)] of a polylactic acid resin (A) and a rubber-reinforced styrene resin (B) of 25/75 to 85/15, and tin oxide (D ) In an amount of 0.005 to 10 parts by mass with respect to 100 parts by mass in total of the polylactic acid resin (A) and the rubber-reinforced styrene resin (B). Furthermore, the impact resistance improver (G) is contained in a total of 100 parts by mass of the polylactic acid resin (A) and the rubber-reinforced styrene resin (B). The thermoplastic resin composition of Claim 1 which contains 5-10 mass parts. The thermoplastic resin composition according to claim 1 or 2, wherein the polylactic acid resin (A) has a D-form content of 0.1 to 0.6 mol%, or 99.4 to 99.9 mol%. . A molded article comprising the thermoplastic resin composition according to any one of claims 1 to 3.