JP2014043540A - Polylactic acid-based resin composition and molded article comprising the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polylactic acid-based resin composition having excellent crystal performances and a fast crystallization rate, capable of giving a molded article that is sufficiently crystallized and excellent in heat resistance, and to provide a molded article comprising the polylactic acid-based resin composition.SOLUTION: The polylactic acid-based resin composition comprises a polylactic acid resin (A) and a dianhydrohexitol ester plasticizer (B). The content of the dianhydrohexitol ester plasticizer (B) is 0.5 to 10 parts by mass with respect to 100 parts by mass of the polylactic acid resin (A) in the resin composition.

Description

  The present invention relates to a polylactic acid resin composition containing a dianhydrohexitol ester plasticizer and a molded body formed from the polylactic acid resin composition.

  In recent years, biodegradable polymers that are decomposed by microorganisms and the like have attracted attention with increasing social demands for environmental protection. Specific examples of biodegradable polymers include aliphatic polyesters such as polybutylene succinate, polycaprolactone and polylactic acid, and aliphatic polyesters such as terephthalic acid / 1,4-butanediol / adipic acid copolymer and aromatic compounds. Examples include polyesters that can be injection-molded or extruded, such as polyesters obtained by copolymerization of group polyesters.

  Among the polyesters that can be injection molded or extruded as described above, the polylactic acid resin can be applied to a wide range of uses because it has excellent crystal performance and heat resistance is improved. Furthermore, since the polylactic acid resin is available at a relatively low cost, it is expected to be applied in a wide range as a biodegradable resin.

  However, when the polylactic acid resin is used alone, the crystal performance is insufficient, so that when the molded body is produced, there is a problem that the crystallization of the polylactic acid resin does not proceed sufficiently even though the molded body can be obtained. there were. As a result, there was a problem that the obtained molded body was thermally deformed when the glass transition temperature of the polylactic acid resin was 57 ° C. or higher, resulting in poor heat resistance.

Therefore, various methods for adding a crystal nucleating agent have been proposed as techniques for improving the crystal performance of polylactic acid resin (Patent Documents 1 and 2).
Patent Document 1 discloses a polylactic acid resin composition containing an organic crystal nucleating agent and a crystallization accelerator, and Patent Document 2 discloses a polylactic acid resin containing an amide crystal nucleating agent and an adipate ester plasticizer. A resin composition is described. According to these resin compositions, although the crystal performance has been improved to some extent, development of a polylactic acid-based resin composition having further improved crystal performance (an improvement in crystallization speed and heat resistance) has been demanded.

International Publication No. 2006/121056 Pamphlet JP 2011-241347 A

  The present invention solves the above-described problems, and has excellent crystal performance, a high crystallization speed, sufficient crystallization, and a molded product excellent in heat resistance can be obtained. An object of the present invention is to provide a resin composition. Furthermore, it aims at providing the molded object which consists of this polylactic acid-type resin composition.

The inventors of the present invention have arrived at the present invention as a result of studies to solve the above problems. That is, the gist of the present invention is the following (1) to (4).
(1) A resin composition comprising a polylactic acid resin (A) and a dianhydrohexitol ester plasticizer (B), wherein dianhydrohexene is added to 100 parts by mass of the polylactic acid resin (A). The polylactic acid-based resin composition, wherein the content of the xitol ester-based plasticizer (B) is 0.5 to 10 parts by mass.
(2) The polylactic acid resin composition according to (1), wherein the D-form content of the polylactic acid resin (A) is 1.0 mol% or less, or 99.0 mol% or more. .
(3) The polylactic acid resin composition as described in (1) or (2), wherein the dianhydrohexitol ester plasticizer (B) is an isosorbide diester.
(4) In addition to the polylactic acid resin (A) and the dianhydrohexitol ester plasticizer (B), it contains an organic crystal nucleating agent (C), based on 100 parts by mass of the polylactic acid resin (A). The content of the organic crystal nucleating agent (C) is 0.1 to 10 parts by mass, and the polylactic acid resin composition according to any one of (1) to (3).
(5) A molded article characterized by being formed from the polylactic acid resin composition according to any one of (1) to (4).

Since the polylactic acid resin composition of the present invention contains an appropriate amount of the dianhydrohexitol ester plasticizer (B), the crystal performance of the polylactic acid resin is improved, the crystallization speed is high, and the crystal is sufficiently crystallized. It becomes possible to obtain a molded body excellent in heat resistance.
By using the polylactic acid resin (A) having a D-form content of 1.0 mol% or less, or 99.0 mol% or more, the crystal performance of the polylactic acid resin is further improved, and the above effects are more remarkable. It becomes.
In addition, by containing an appropriate amount of the organic crystal nucleating agent (C) in the polylactic acid resin composition, the improvement in crystal performance becomes more remarkable.
As described above, the polylactic acid-based resin composition of the present invention can greatly expand the range of use of the polylactic acid resin, which is a low environmental load material, and contribute to the saving of depleted resources such as petroleum. The value is extremely high.

Hereinafter, the present invention will be described in detail.
The polylactic acid resin composition of the present invention (hereinafter sometimes simply referred to as “resin composition”) contains a polylactic acid resin (A) and a dianhydrohexitol ester plasticizer (B). is there.
First, the polylactic acid resin (A) will be described. The polylactic acid resin (A) in the present invention refers to poly (L lactic acid), poly (D lactic acid), a mixture or a copolymer thereof. In particular, in order to improve the crystal performance of the polylactic acid resin (A), the D-form content is 3.0 mol% or less, or 97.0 mol% or more in terms of crystallization speed and heat resistance. Is preferably 1.0 mol% or less, or more preferably 99.0 mol% or more.

  The D-form content of the polylactic acid resin (A) refers to the 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 having a D-form content of 1.0 mol%, in this polylactic acid resin, the proportion of D lactic acid units is 1.0 mol%, and the proportion of L lactic acid units is 99.0 mol%.

  In the present invention, the D-form content of the polylactic acid resin (A) is such that L lactic acid and D lactic acid obtained by decomposing the polylactic acid resin (A) are all methyl esterified, and the methyl ester of L lactic acid and the methyl of D lactic acid It is calculated by a method of analyzing an ester with a gas chromatography analyzer.

  The polylactic acid resin (A) is produced by a known melt polymerization method or by further using a solid phase polymerization method. In addition, as the polylactic acid resin (A) satisfying the specific D-form content as described above, a commercially available product may be used, or among the lactides that are cyclic dimers of lactic acid, the D-form content. Using a L-lactide having a sufficiently low L content or a D-lactide having a sufficiently low L-form content as a raw material, and using a known melt polymerization method or a solid phase polymerization method. Also good.

  The weight average molecular weight of the polylactic acid resin (A) used in the present invention is preferably 50,000 to 300,000, and the weight average molecular weight is preferably 100,000 to 300,000, more preferably 120,000 to 200,000. . When the weight average molecular weight is less than 50,000, it is difficult to obtain practical strength and durability. On the other hand, if the weight average molecular weight exceeds 300,000, fluidity is poor and melt extrusion may be difficult. When producing a film or the like, the pressurization of an extruder becomes a problem. The weight average molecular weight of the polylactic acid resin is calculated by a method of analysis by gel permeation chromatography (GPC) described later.

  The polylactic acid resin (A) may be copolymerized with monomers other than the lactic acid component, which is the main component. Examples of the copolymerizable monomer include terephthalic acid, isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, and 1,5 as acid components. -Naphthalenedicarboxylic acid, methyl terephthalic acid, 4,4'-biphenyl dicarboxylic acid, 2,2'-biphenyl dicarboxylic acid, 4,4'-biphenyl ether dicarboxylic acid, 4,4-diphenylmethane dicarboxylic acid, 4,4'- Aromatic dicarboxylic acids such as diphenylsulfone dicarboxylic acid and 4,4'-diphenylisopropylidenedicarboxylic acid; adipic acid, sebacic acid, oxalic acid, malonic acid, succinic acid, azelaic acid, undecanedioic acid, dodecanedioic acid, aikosan diacid Saturated aliphatic dicarboxylic acids such as acids and hydrogenated dimer acids; Unsaturated aliphatic dicarboxylic acids such as malic acid, maleic acid, itaconic acid, mesaconic acid, citraconic acid, and dimer acid and their anhydrides; 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2 -Cycloaliphatic dicarboxylic acid, 2,5-norbornene dicarboxylic acid, and alicyclic dicarboxylic acids such as tetrahydrophthalic acid.

  Examples of the copolymerizable monomer include ethylene glycol, propylene glycol, 1,3-butanediol, diethylene glycol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, 1,8 as diol components. Aliphatic diols such as octanediol and 1,10-decanediol; alicyclic diols such as 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol and 1,2-cyclohexanedimethanol, bisphenol A and bisphenol Bisphenols such as S or their ethylene oxide adducts; and aromatic diols such as hydroquinone and resorcinol.

  Furthermore, as copolymerizable monomers, hydroxycarboxylic acids such as p-hydroxybenzoic acid, p- (2-hydroxyethoxy) benzoic acid, 6-hydroxycaproic acid, 3-hydroxybutyric acid, and 3-hydroxyvaleric acid; -Lactone compounds such as valerolactone, γ-butyrolactone, and ε-caprolactone.

  In addition, it is preferable that the ratio of the polylactic acid resin (A) in the polylactic acid-type resin composition of this invention is 50 mass% or more, Especially it is preferable that it is 60 mass% or more, and it is 80 mass% or more. It is more preferable. If the proportion of the polylactic acid resin (A) in the resin composition is less than 50% by mass, the amount of the polylactic acid resin, which is a low environmental load material, is reduced, making it difficult to obtain an environmentally friendly resin composition. It becomes.

  In the present invention, the dianhydrohexitol ester plasticizer (B) is added for the purpose of increasing the crystallization speed of the polylactic acid resin (A). The dianhydrohexitol ester plasticizer (B) is a plasticizer having excellent compatibility with the polylactic acid resin (A). For this reason, when the dianhydrohexitol ester plasticizer (B) is used, the crystallization speed is faster than when other plasticizers are used, and the resulting molded product is heat resistant. There is an advantage of being excellent.

  Examples of the dianhydrohexitol ester plasticizer (B) include 1,4: 3,6-dianhydro-D-mannitol monoester (hereinafter sometimes abbreviated as isomannide monoester), 1,4: 3,6-dianhydro-D-mannitol diester (hereinafter sometimes abbreviated as isomannide diester), 1,4: 3,6-dianhydro-L-iditol monoester (hereinafter referred to as isoidide monoester) 1,4: 3,6-dianhydro-L-iditol diester (hereinafter sometimes abbreviated as isoidide diester) and 1,4: 3,6-dianhydro-D-sorbitol Monoester (hereinafter sometimes abbreviated as isosorbide monoester), 1,4: 3,6-dianhydro-D-sorbitol Ester (hereinafter sometimes abbreviated as isosorbide diester), with or may be used in combination may be used them in combination. Among these, it is preferable to use isosorbide diester because it is produced using inexpensive starch as a starting material, is easy to obtain commercially because it is easy to manufacture, and has a small colored product.

  The content of the dianhydrohexitol ester plasticizer (B) in the polylactic acid resin composition must be 0.5 to 10 parts by mass with respect to 100 parts by mass of the polylactic acid resin (A). Yes, it is preferably 0.5 to 5 parts by mass, and more preferably 0.5 to 3 parts by mass. If the content is less than 0.5 parts by mass, the effect of promoting crystallization is poor, and it is difficult to sufficiently improve the crystal performance. On the other hand, if the content exceeds 10 parts by mass, the dianhydrohexitol ester plasticizer (B) bleeds out on the surface of the resulting molded article, so that the storage stability is impaired or the processability is reduced. To do. In addition, the viscosity may decrease, making it difficult to obtain a molded product.

  The resin composition of the present invention preferably further contains a crystal nucleating agent. By containing the crystal nucleating agent, the crystal performance of the polylactic acid resin (A) can be further improved, and the transparency when the polylactic acid resin is crystallized can be maintained.

  As such a crystal nucleating agent, known organic nucleating agents and inorganic crystal nucleating agents can be used, but the crystal performance improving effect and the transparency maintaining effect as described above are more remarkable. It is preferable to use the organic crystal nucleating agent (C).

  Examples of the inorganic crystal nucleating agent include layered silicates such as talc, smectite, mica, vermiculite, and swellable fluorine mica.

  Examples of the organic crystal nucleating agent (C) include organic amide compounds, organic hydrazide compounds, carboxylic acid ester compounds, organic sulfonates, phthalocyanine compounds, melamine compounds, and organic phosphonates. Of these, organic sulfonates and organic amide compounds are preferred 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 LAK301 and LAK403 manufactured by Takemoto Yushi Co., Ltd.

  Specific examples of the organic amide compound include the following compounds. N, N′-ethylene-bis-12-hydroxystearylamide, ricinoleic acid amide, ricinostearolic acid amide, hydroxystearic acid amide, N-hydroxyethyl-ricinoleic acid amide, N-hydroxyethyl-12-hydroxystearylamide N, N′-ethylene-bis-ricinoleic acid amide, N, N′-hexamethylene-bis-ricinoleic acid amide, N, N′-hexamethylene-bis-12-hydroxystearylamide, N, N′-xylylene -Bis-12-hydroxystearylamide and the like. Among these, N, N′-ethylene-bis-12-hydroxystearylamide, N, N′-hexamethylene-bis-ricinoleic acid amide, N, N′-hexa from the viewpoint of crystallization speed and transparency. Methylene-bis-12-hydroxystearylamide, N, N′-xylylene-bis-12-hydroxystearylamide and the like are preferable. As what is marketed, AS-AT-530SF by Ito Oil Co., Ltd. etc. are mentioned, for example.

  The content of the crystal nucleating agent in the polylactic acid-based resin composition is preferably 0.1 to 10 parts by mass, more preferably 0.3 to 7 parts by mass with respect to 100 parts by mass of polylactic acid. More preferably, it is 0.5 to 5 parts by mass. When the content of the crystal nucleating agent is less than 0.1 parts by mass, the effect of improving the crystal performance is poor. On the other hand, when it exceeds 10 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.

  From the viewpoint of improving durability, the polylactic acid resin composition of the present invention may contain at least one terminal blocker selected from the group consisting of a carbodiimide compound, an epoxy compound and an oxazoline compound. Among these terminal blocking agents, it is more preferable to use a carbodiimide compound from the viewpoint of durability and hue.

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 di -t- butyl carbodiimide.
And as what is marketed among these compounds, 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 Matsumoto Yushi Co., Ltd., Stavacsol P manufactured by Rhein Chemie, and Carbodilite LA-1 manufactured by Nisshinbo Industries, Ltd.

  The blending amount of the terminal blocking agent in the polylactic acid-based resin composition is in a range that does not inhibit the crystallization rate, so that it is 0.05 to 10 parts by mass with respect to 100 parts by mass of the polylactic acid resin. Preferably, it is 0.1-5 mass parts.

  In addition, the thermoplastic resin composition of the present invention, within a range that does not greatly impair the properties, pigments, heat stabilizers, antioxidants, weathering agents, light resistance agents, flame retardants, plasticizers, lubricants, mold release agents, Antistatic agents, fillers and the like can be added. Examples of heat stabilizers and antioxidants include hindered phenols, phosphorus compounds, hindered amines, sulfur compounds, copper compounds, alkali metal halides, and vitamin E. 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. Inorganic fillers include talc, calcium carbonate, zinc carbonate, wollastonite, silica, alumina, magnesium oxide, calcium silicate, sodium aluminate, calcium aluminate, sodium aluminosilicate, magnesium silicate, glass balloon, carbon black, Examples thereof include zinc oxide, antimony trioxide, zeolite, hydrotalcite, metal fiber, metal whisker, ceramic whisker, potassium titanate, boron nitride, graphite, and carbon fiber. Examples of the organic filler include naturally occurring polymers such as starch, cellulose fine particles, wood flour, okara, fir shell, bran, and modified products thereof. In addition, the method of mixing these with the resin composition of this invention is not specifically limited.

  In addition, as described above, in the polylactic acid resin composition of the present invention, the ratio of the polylactic acid resin (A) is preferably 50% by mass or more, as long as the effects of the present invention are not impaired. In addition, a resin other than the polylactic acid resin (A) may be contained. For example, other resins can be blended to form an alloy with the polylactic acid resin (A).

Examples of such other resins include polyolefin, polyester, polyamide, polycarbonate, polystyrene, polymethyl (meth) acrylate, poly (acrylonitrile-butadiene-styrene) copolymer, liquid crystal polymer, and polyacetal.
Examples of the polyolefin include polyethylene and polypropylene. Examples of the polyamide include polyamide 6, polyamide 66, polyamide 610, polyamide 11, polyamide 12, and polyamide 6T. Examples of the polyester include various aromatic polyesters and various aliphatic polyesters. Specific examples of the aromatic polyester include polyethylene terephthalate, polybutylene terephthalate, polyarylate, and polybutylene adipate terephthalate. Specific examples of the aliphatic polyester include polybutylene succinate and poly (butylene succinate). (Nate-lactic acid) copolymer, polyhydroxybutyric acid and the like.
Other polyesters include polycyclohexylene dimethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate terephthalate, polybutylene isophthalate terephthalate, polyethylene terephthalate / cyclohexylene dimethylene terephthalate, cyclohexyl. Examples include dimethylene isophthalate choterephthalate, copolyester composed of p-hydroxybenzoic acid residue and ethylene terephthalate residue, polytrimethylene terephthalate composed of 1,3-propanediol which is a plant-derived raw material, and the like. The method for mixing the polylactic acid resin and these resins is not particularly limited.

  As a method for obtaining the polylactic acid resin composition of the present invention, a polylactic acid resin (A) and a dianhydrohexitol ester plasticizer (B) are used as necessary by a known method such as melt kneading. A method of kneading the crystal nucleating agent (C) can be mentioned. In melt kneading, a general kneader such as a single screw extruder, a twin screw extruder, a roll kneader, or a Brabender can be used, but in order to improve the dispersibility of each component with respect to the polylactic acid resin, It is preferable to use a twin screw extruder.

  As described above, in the method of obtaining a polylactic acid resin composition by melt-kneading, a polylactic acid resin (A), a dianhydrohexitol ester plasticizer (B), and a crystal nucleating agent (C) are dry blended. The crystal nucleating agent (C) may be supplied from the middle of the extruder using a feeder or the like. Further, since the dianhydrohexitol ester plasticizer (B) is a liquid at room temperature, a method of supplying the dianhydrohexitol ester plasticizer (B) from the middle of kneading using a heating quantitative liquid feeding device or the like is more preferable. Thereafter, the obtained polylactic acid-based resin composition is taken up in a strand shape and cooled, and then cut into a pellet shape to obtain a pellet of the polylactic acid-based resin composition.

  The polylactic acid-based resin composition of the present invention is formed into various molded bodies by injection molding, blow molding, extrusion molding, inflation molding, and molding methods such as vacuum molding, pressure molding, and vacuum / pressure molding after sheet processing. Can do. In particular, it is preferable to adopt an injection molding method, and in addition to a general injection molding method, gas injection molding, injection press molding, and the like can be employed. As an example of injection molding conditions suitable for the resin composition of the present invention, the cylinder temperature is not less than the melting point or flow start temperature of the resin composition, preferably 190 to 270 ° C., and the mold temperature is that of the resin composition. (Melting point-20 ° C.) or less is appropriate. If the molding temperature is too low, the operability becomes unstable, such as short-circuiting in the molded product, and overload tends to occur. Conversely, if the molding temperature is too high, the resin composition will decompose and the resulting molded product Problems such as reduction in strength and coloration are likely to occur, and both may be undesirable.

The molded body of the present invention is molded by the molding method as described above using the polylactic acid resin composition of the present invention. Since the molded body of the present invention has excellent heat resistance, it can be suitably used for applications such as housings for office equipment, 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. Besides, it can be suitably used for various applications such as electric / electronic parts, medical care, food, household / office supplies, OA equipment, building material-related parts, furniture parts, and the like.
Examples of the molded article of the present invention other than the above include 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, etc .; 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.
<material>
Polylactic acid resin (A)
(A-1) Nature Works 3001D Weight average molecular weight = 130,000 D body weight = 1.4 mol%
(A-2) Toyota S-12 weight average molecular weight = 130,000 D body weight = 0.1 mol%
Diane hydrohexitol ester plasticizer (B)
(B-1) POLYSORB ID37-EXP (isosorbide diester) manufactured by Rocket Fleure
(X-1) ATBC (tributyl acetyl citrate) manufactured by Taoka Chemical Co., Ltd.

Organic crystal nucleating agent (C)
(C-1) ASA T-530SF (N, N′-ethylene-bis-12-hydroxystearylamide) manufactured by Ito Oil Co., Ltd.
(C-2) LAK-403 (dimethyl barium 5-sulfoisophthalate) manufactured by Takemoto Yushi Co., Ltd.
(C-3) LAK-301 (dimethyl potassium 5-sulfoisophthalate) manufactured by Takemoto Yushi Co., Ltd.
Inorganic crystal nucleating agent (Y-1) Hayashi Kasei Co., Ltd. MW HS-T (talc)

<Characteristic value and evaluation method>
(1) D-form content of polylactic acid resin (A) 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. Subsequently, 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) Weight average molecular weight (Mw) of polylactic acid resin (A)
Using a gel permeation chromatography device (manufactured by Shimadzu Corporation) equipped with a differential refractive index detector (manufactured by Shimadzu Corporation, trade name “RID-10A”), tetrahydrofuran (THF) as an eluent and a flow rate of 1.0 ml / min. , Measured at 40 ° C. As columns, SHODEX KF-805L and KF-804L (manufactured by Showa Denko KK) were used. The sample was dissolved in 0.5 ml of chloroform after dissolving 10 mg of the resin composition, diluted with 5 ml of THF, filtered through a 0.45 μm filter, and then used for measurement. The molecular weight was converted using polystyrene (manufactured by Waters) as a standard sample.
(3) Molding cycle (formability)
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.

(4) Crystallinity of the molded body A part of the obtained test piece is cut out and used as a sample. Then, using a differential scanning calorimeter (DSC device “DSC7”, manufactured by Perkin Elmer Co., Ltd.), 7 mg of the molded product was heated from 20 ° C. to 200 ° C. at a rate of temperature increase of 20 ° C./min. The amount of heat (ΔHc) and the amount of heat of crystal melting (ΔHm) are measured, and the crystallization index X is calculated by the following formula.
Crystallinity = | ΔHm | − | ΔHc | (J / g)
(5) 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.

Example 1
Using a twin screw extruder (TEM26SS type manufactured by Toshiba Machine Co., Ltd.), the polylactic acid resin (A) and the dianhydrohexitol ester plasticizer (B) were extruded so as to have the composition (ratio) shown in Table 1. From the root supply port. Since the dianhydrohexitol ester plasticizer (B) is a liquid, it is supplied from the root supply port of the extruder to the ratio shown in Table 1 using a liquid injection pump, barrel temperature 200 ° C., screw rotation speed Melt kneading was performed at 150 rpm and a discharge rate of 15 kg / h. After melt-kneading, a strand is extruded from a 0.4 mm diameter × 3 hole die, cut into a pellet, and heated at 60 ° C. in a vacuum dryer (trade name “Vacuum Dryer DP83” manufactured by Yamato Kagaku Co., Ltd.). And dried for 48 hours to obtain a polylactic acid resin composition.
The obtained polylactic acid resin composition is measured for general physical properties in conformity with ISO using an injection molding machine (manufactured by Nissei Resin Co., Ltd., NEX-110 type) at a cylinder temperature of 160 to 200 ° C. and a mold temperature of 110 ° C. A test piece was prepared.

Examples 2 to 22, Comparative Examples 1 to 9
A polylactic acid resin composition was obtained in the same manner as in Example 1 except that the ratio and type of polylactic acid resin, plasticizer, and crystal nucleating agent were variously changed as shown in Table 1.
And the test piece was produced like Example 1 using the obtained polylactic acid-type resin composition.

  Tables 1 and 2 show the characteristic values of the polylactic acid resin compositions obtained in Examples 1 to 22 and Comparative Examples 1 to 9, and molded articles, and the evaluation results.

  As is clear from Table 1, the resin compositions obtained in Examples 1 to 22 were excellent in crystal performance. For this reason, the molding cycle at the time of obtaining a molded article was short, and the obtained molded article had a high heat distortion temperature, a high degree of crystallinity, and excellent heat resistance. Among them, the resin compositions of Examples 7 to 20 using the polylactic acid resin (A) having a D-form content of 1.0 mol% or less have excellent crystal performance, and the improvement in crystal performance is D The lower the body content, the more remarkable. Moreover, in the resin composition of Examples 3-6 and 9-22, it is excellent in crystal | crystallization performance by containing a crystal nucleating agent compared with the case where only a dianhydrohexitol ester plasticizer (B) is contained. Improved moldability and heat resistance. Among these, the resin compositions of Examples 3 to 4 and 9 to 14 to which the organic crystal nucleating agent (C-1 to C-3) was added were examples to which the inorganic crystal nucleating agent (Y-1) was added. It was more excellent in moldability and heat resistance than the resin compositions of 5-6 and 15-16.

On the other hand, as is clear from Table 2, since the resin compositions of Comparative Examples 1 and 2 contained neither a plasticizer nor a crystal nucleating agent, the moldability and heat resistance were poor. In Comparative Example 1, the molding cycle was 180 seconds. It was not possible to mold within. Moreover, the molded object obtained from the resin composition of Comparative Example 2 had a low crystallinity and poor heat resistance. In the resin compositions of Comparative Examples 3 and 4, since the plasticizer was not a dianhydrohexitol ester plasticizer, the molding cycle was slow, and the obtained molded body had a low crystallinity and poor heat resistance. Met. The resin compositions of Comparative Examples 5 to 8 contained a plasticizer and an organic crystal nucleating agent. However, since the plasticizer was not a dianhydrohexitol ester plasticizer (B), the crystal performance was improved by the plasticizer. Improvement was inhibited, and the moldability and heat resistance were lower than those of Examples 9-12. In the resin composition of Comparative Example 9, the plasticizer used was a dianhydrohexitol ester plasticizer, but the plasticizer bleeded out because of the excessive addition amount, and the resulting molded product was sticky. It became a certain quality drop.

Claims (5)

A resin composition comprising a polylactic acid resin (A) and a dianhydrohexitol ester plasticizer (B), the dianhydrohexitol ester per 100 parts by mass of the polylactic acid resin (A) A polylactic acid resin composition, wherein the content of the plasticizer (B) is 0.5 to 10 parts by mass. The polylactic acid resin composition according to claim 1, wherein the D-form content of the polylactic acid resin (A) is 1.0 mol% or less, or 99.0 mol% or more. The polylactic acid resin composition according to claim 1 or 2, wherein the dianhydrohexitol ester plasticizer (B) is an isosorbide diester. In addition to the polylactic acid resin (A) and the dianhydrohexitol ester plasticizer (B), it contains an organic crystal nucleating agent (C). The organic crystal is added to 100 parts by mass of the polylactic acid resin (A). Content of a nucleating agent (C) is 0.1-10 mass parts, The polylactic acid-type resin composition in any one of Claims 1-3 characterized by the above-mentioned. A molded article characterized by being formed of the polylactic acid resin composition according to any one of claims 1 to 4.