JP5107873B2 - Polylactic acid resin composition - Google Patents

Description

  The present invention relates to a polylactic acid resin composition and a polylactic acid resin molded article.

  Among the biodegradable resins, polylactic acid resins are made from saccharides from corn, straw, etc., and a large amount of L-lactic acid is produced by fermentation. The use of the obtained resin is expected because it is extremely rare and has the characteristics that the obtained resin has high rigidity and good transparency. However, polylactic acid resin is brittle, hard, and lacks flexibility, all of which are limited to the field of hard molded products, and when molded into an injection molded product, the flexibility and impact resistance are insufficient. However, there are problems such as whitening and inferior hinge characteristics when bent, and it is not used in the soft or semi-rigid field. In addition, the polylactic acid resin has a slow crystallization rate and is in an amorphous state after molding unless a mechanical process such as stretching is performed. However, since the glass transition temperature (Tg) of polylactic acid resin is as low as 60 ° C. and poor in heat resistance, there is a problem that it cannot be used in an environment where the temperature is 55 ° C. or higher.

Various techniques for applying polylactic acid resin to soft and semi-rigid fields have been proposed, including a method of adding a plasticizer or a method of crystallizing by adding a crystal nucleating agent to improve heat resistance (for example, patents). Document 1) demands the development of a polylactic acid resin composition having better moldability, heat resistance, impact resistance and flexibility.
International Publication No. 2005/108501 Pamphlet

  An object of the present invention is to provide a polylactic acid resin composition having excellent heat resistance and impact resistance, good moldability, particularly excellent moldability at a low mold temperature, and the polylactic acid resin composition. The object is to provide a molded product of polylactic acid resin.

  The present invention is a polylactic acid resin composition comprising a polylactic acid resin, a plasticizer, an organic nucleating agent, a hydrolysis inhibitor, an inorganic filler, and an impact-resistant absorber, wherein the polylactic acid resin has an optical purity. It contains 99.0% or more polylactic acid in an amount of 50% by weight or more, the plasticizer has two or more ester groups in the molecule, and at least one alcohol component constituting the ester per hydroxyl group Provided are a polylactic acid resin composition which is a compound obtained by adding an average of 0.5 to 5 moles of an alkylene oxide having 2 to 3 carbon atoms, and a polylactic acid resin molded article obtained by molding this polylactic acid resin composition.

  The polylactic acid resin composition of the present invention is excellent in heat resistance and impact resistance, and exhibits excellent moldability even at a lower mold temperature.

  The polylactic acid resin composition of the present invention contains a polylactic acid resin, a plasticizer, an organic nucleating agent, a hydrolysis inhibitor, an inorganic filler, and an impact absorber, and the polylactic acid resin has an optical purity. Is characterized by containing 99.0% or more polylactic acid by 50% by weight or more and the plasticizer is a specific compound. In this specification, “inorganic filler” refers to a fibrous, plate-like, granular, or powder-like inorganic substance that is usually used for reinforcing thermoplastic resins, and “impact-resistant absorbent” refers to normal heat It refers to organic fibers, rubber, and compatibilizers used to improve flexibility in plastic resins.

[Polylactic acid resin]
The polylactic acid resin in the present invention contains 50% by weight or more of polylactic acid having an optical purity of 99.0% or more.

  As polylactic acid, polylactic acid obtained by polycondensation of only a lactic acid component as a raw material monomer and / or a hydroxycarboxylic acid component other than a lactic acid component and lactic acid as a raw material monomer (hereinafter also simply referred to as a hydroxycarboxylic acid component) Represents both polylactic acids obtained by polycondensation.

  In lactic acid, there are optical isomers of L-lactic acid (L form) and D-lactic acid (D form). In the present invention, as the lactic acid component, only one or both of the optical isomers may be contained, but both the flexibility, rigidity and heat resistance of the polylactic acid resin composition, and the viewpoint of productivity Therefore, it is preferable to use lactic acid having high optical purity mainly composed of any optical isomer. In the present specification, the “main component” refers to a component whose content in the lactic acid component is 80 mol% or more.

  The content of L-form or D-form in the lactic acid component in the case of polycondensation of only the lactic acid component, that is, the higher content of the isomers is preferably 99.0 to 100 mol%. In addition, since the total content of L-form and D-form in the lactic acid component is substantially 100 mol%, the smaller content of the isomers is 0 to 1.0 mol% in the lactic acid component. Is preferred.

  The content of the L-form or D-form in the lactic acid component when the lactic acid component and the hydroxycarboxylic acid component are subjected to polycondensation, that is, the content of the larger of the isomers, is preferably 99.0 to 100 mol%. In addition, since the total content of L-form and D-form in the lactic acid component is substantially 100 mol%, the smaller content of the isomers is 0 to 1.0 mol% in the lactic acid component. Is preferred.

  On the other hand, examples of the hydroxycarboxylic acid component include hydroxycarboxylic acid compounds such as glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxypentanoic acid, hydroxycaproic acid, and hydroxyheptanoic acid, and are used alone or in combination of two or more. can do. Of these, glycolic acid and hydroxycaproic acid are preferable.

  Moreover, in this invention, the dimer of the said lactic acid and the hydroxycarboxylic acid compound may be contained in each component. Examples of the lactic acid dimer include lactide, which is a cyclic dimer of lactic acid, and examples of the dimer of the hydroxycarboxylic acid compound include glycolide, which is a cyclic dimer of glycolic acid. The lactide includes L-lactide, which is a cyclic dimer of L-lactic acid, D-lactide, which is a cyclic dimer of D-lactic acid, meso-lactide obtained by cyclic dimerization of D-lactic acid and L-lactic acid, DL-lactide, which is a racemic mixture of D-lactide and L-lactide, and any lactide can be used in the present invention, but the flexibility and rigidity of the polylactic acid resin composition and the polylactic acid resin From the viewpoint of productivity, D-lactide and L-lactide are preferable. In addition, the dimer of lactic acid may be contained in the lactic acid component in any case where only the lactic acid component is subjected to polycondensation and in the case where the lactic acid component and the hydroxycarboxylic acid component are polycondensed.

  The condensation polymerization reaction of only the lactic acid component and the condensation polymerization reaction of the lactic acid component and the hydroxycarboxylic acid component are not particularly limited and can be performed using a known method.

  Thus, by selecting the raw material monomer, for example, an optical purity comprising 99.0 mol% or more and less than 100 mol% of either L-lactic acid or D-lactic acid and more than 0 mol% and 1.0 mol% or less of the hydroxycarboxylic acid component is 99. More than 0.0% of polylactic acid can be obtained. Among them, polylactic acid obtained by using lactide, which is a cyclic dimer of lactic acid, glycolide, which is a cyclic dimer of glycolic acid, and caprolactone, as raw material monomers is preferable.

  In the present invention, as a polylactic acid resin containing 50% by weight or more of polylactic acid having an optical purity of 99.0% or more, from the viewpoint of compatibility between flexibility and rigidity of the polylactic acid resin composition, and moldability, You may prepare and use the stereocomplex polylactic acid which uses the two types of said polylactic acid obtained by using the lactic acid component which has a different isomer as a main component as a structural component.

  Specifically, one of the polylactic acids constituting the stereocomplex polylactic acid (hereinafter referred to as polylactic acid (A)) is L-form 99.0 to 100 mol%, other components including D-form 0 to 1.0 mol% Containing. The other polylactic acid (hereinafter referred to as polylactic acid (B)) contains 99.0 to 100 mol% of D isomer and 0 to 1.0 mol% of other components including L isomer. In addition, as other components other than L-form and D-form, dicarboxylic acid, polyhydric alcohol, hydroxycarboxylic acid, lactone, etc. having a functional group capable of forming two or more ester bonds are exemplified, and unreacted Polyester, polyether, polycarbonate or the like having two or more of the functional groups in the molecule may be used.

  In the stereocomplex polylactic acid, the weight ratio of polylactic acid (A) to polylactic acid (B) [polylactic acid (A) / polylactic acid (B)] is the flexibility, rigidity and heat resistance of the polylactic acid resin composition. 10/90 to 90/10 are preferable, and 20/80 to 80/20 are more preferable from the viewpoint of compatibility with the above and moldability.

  The content of polylactic acid having an optical purity of 99.0% or more in the polylactic acid resin is 50% by weight from the viewpoint of compatibility between the flexibility, rigidity and heat resistance of the polylactic acid resin composition, and moldability. It is preferable that the content be 80% by weight or more, more preferably 90% by weight or more, and still more preferably substantially 100% by weight.

  In the present invention, a commercially available polylactic acid resin having an optical purity of 99.0% or more can be used. Examples of such a polylactic acid resin include, for example, a product name Eco-Plastic U'z S-12 (optical purity 99.6%) manufactured by Toyota Motor Corporation, and a product name Eco-plastic U'z S-17 (optical purity 99.90). 7%).

  The optical purity of the polylactic acid in the present invention is D-containing as described in “Voluntary Standards for Food Containers and Packaging Made of Synthetic Resins such as Polyolefins, Third Edition, Revised June 2004, Part 3 Sanitation Test Method P12-13”. It can be determined according to the method of measuring the quantity. Specifically, the method for measuring the optical purity of polylactic acid is as follows.

  First, sodium hydroxide / methanol is added to precisely weighed polylactic acid, set in a water bath shaker set at 65 ° C., and hydrolyzed until the resin content becomes a homogeneous solution. The solution is neutralized by adding dilute hydrochloric acid, and the decomposition solution is dissolved in pure water, and then a predetermined volume is separated into a volumetric flask and diluted with a high-performance liquid chromatography (HPLC) mobile phase solution, and the pH is 3 to 3. The volumetric flask is adjusted so as to be in the range of 7, and the volumetric flask is quantitatively filtered through a membrane filter (0.45 μm). The optical purity of polylactic acid can be determined by quantifying D-lactic acid and L-lactic acid by HPLC using this adjusted solution.

In addition, the measurement of HPLC can be performed on condition of the following.
<HPLC measurement conditions>
Column: Optical resolution column <Example> Sumichiral OA6100 (46 mmφ × 150 mm, 5 μm), pre-column manufactured by Sumika Chemical Analysis Co., Ltd .: Optical resolution column <Example> Sumicial QA6100 (4 mmφ × 10 mm, 5 μm), column temperature manufactured by Sumika Chemical Analysis : 25 ° C
Mobile phase: 1.5% copper sulfate aqueous solution containing 2.5% methanol Mobile phase flow rate: 1.0 ml / min Detector: UV detector (UV254 nm)
Injection volume: 20 μl

  In addition, the weight average molecular weight of the polylactic acid in the present invention is preferably 100,000 or more from the viewpoint of mechanical properties of the molded body, and is preferably 400,000 or less from the viewpoint of fluidity during molding. , 300,000 or less, more preferably 200,000 or less. The weight average molecular weight of polylactic acid was measured using gel permeation chromatograph (GPC), chloroform as solvent, high-temperature SEC column (GMHHR-H series) manufactured by Tosoh Corporation, flow rate 1.0 mL / min, column temperature 40 It can be obtained by conversion using ° C, a differential refractive index detector (RI) as a detector, and styrene having a known molecular weight as a reference.

  In the polylactic acid resin composition in the present invention, in addition to the polylactic acid resin, other resins may be appropriately contained as long as the effects of the present invention are not impaired. Other resins include thermoplastic resins such as polypropylene, polystyrene, ABS resin, AS resin, acrylic resin, polyphenylene sulfide, polyether ether ketone, polyester, polyacetal, polysulfone, polyphenylene oxide, polyether imide, phenol resin, melamine Examples include resins, thermosetting resins such as unsaturated polyester resins, silicone resins, and epoxy resins. Among them, resins having bonds containing carbonyl groups such as ester bonds and carbonate bonds from the viewpoint of compatibility with polylactic acid resins. However, it is preferable because of its structurally high affinity with the polylactic acid resin.

  The content of the polylactic acid resin in the present invention is preferably 50% by weight or more, more preferably 60% by weight or more, and still more preferably 70% by weight or more in the polylactic acid resin composition.

[Plasticizer]
The plasticizer in the present invention has two or more ester groups in the molecule from the viewpoint of interaction with the polylactic acid resin in the present invention and plasticization efficiency, and at least one of the alcohol components constituting the ester is a hydroxyl group. A compound obtained by adding an average of 0.5 to 5 moles of alkylene oxide having 2 to 3 carbon atoms per unit, having two or more ester groups in the molecule, and carbon per one hydroxyl group of an alcohol component constituting the ester A compound in which 0.5 to 5 moles of an average of 2 to 3 alkylene oxides are added is preferable, and an alcohol constituting an ester with a polyhydric alcohol ester or a polycarboxylic acid ether ester having two or more ester groups in the molecule More preferable is a compound in which 0.5 to 5 moles of ethylene oxide is added on average per hydroxyl group of the component. Compounds to 4 mols is more preferable. The alcohol component constituting the ester is preferably an average of 1 to 4 moles of alkylene oxide having 2 to 3 carbon atoms, more preferably 2 to 3 in view of compatibility with polylactic acid resin, plasticization efficiency, and volatility resistance. This is a compound with a molar addition. In view of plasticizing efficiency, the alkylene oxide is preferably ethylene oxide. From the viewpoint of compatibility, the carbon number of hydrocarbon groups such as alkyl groups and alkylene groups contained in the plasticizer, for example, the carbon number of the hydrocarbon group of the polyhydric alcohol or polycarboxylic acid constituting the ester compound is 1-8. Are preferable, 1-6 are more preferable, and 1-4 are more preferable. Moreover, 1-8 are preferable from a compatible viewpoint, as for carbon number of the monocarboxylic acid and monoalcohol which comprise the ester compound of a plasticizer, 1-6 are more preferable, 1-4 are more preferable, and 1-2 are further. More preferred.

  The method for producing a plasticizer in the present invention can be produced, for example, according to the method described in JP-A-2008-174754.

  If the plasticizer in this invention has two or more ester groups in a molecule | numerator, it is excellent in compatibility with a polylactic acid resin, and it is preferable to have 2-4 ester groups in a molecule | numerator. Moreover, if at least one of the alcohol components constituting the ester has an average of 0.5 mol or more of alkylene oxide having 2 to 3 carbon atoms per hydroxyl group, sufficient plasticity is imparted to the polylactic acid resin. If an average of 5 moles or less is added, the effect of bleeding resistance is improved. Further, although the reason is not clear, by using the plasticizer used in the present invention together with a polylactic acid resin containing polylactic acid having an optical purity of 99% or more, the moldability is good, particularly at a low mold temperature. A polylactic acid resin composition exhibiting excellent moldability can be obtained.

The plasticizer in the present invention has two or more ester groups in the molecule from the viewpoint of the moldability and plasticity of the polylactic acid resin molded article and the bleed resistance of the plasticizer, and the average added mole number of ethylene oxide is 3 to 9 compounds are preferred, and at least one selected from the group consisting of an ester of succinic acid or adipic acid and polyethylene glycol monomethyl ether, and an ester of acetic acid and glycerin or ethylene glycol ethylene oxide adduct is more preferred, More preferred are esters of succinic acid or adipic acid with polyethylene glycol monomethyl ether. In addition, the average added mole number of ethylene oxide or propylene oxide can be measured by ¹ H-NMR method.

  Further, from the viewpoint of volatility resistance, an average of 0 to 1.5 of the two or more ester groups in the plasticizer of the present invention may contain an ester group composed of an aromatic alcohol. Since the aromatic alcohol is more compatible with the polylactic acid resin than the aliphatic alcohol having the same carbon number, the molecular weight can be increased while maintaining the bleed resistance. From the viewpoint of plasticizing efficiency, an average of 0 to 1.2, more preferably 0 to 1 is an ester group composed of an aromatic alcohol. Examples of the aromatic alcohol include benzyl alcohol, and examples of the plasticizer include adipic acid and diethylene glycol monomethyl ether / benzyl alcohol = 1/1 mixed diester.

The average molecular weight of the plasticizer in the present invention is preferably from 250 to 700, more preferably from 300 to 600, still more preferably from 350 to 550, still more preferably from the viewpoint of bleed resistance and volatility resistance. ~ 500. The average molecular weight can be obtained by calculating the saponification value by the method described in JIS K0070 and calculating from the following formula.
Average molecular weight = 56108 × (number of ester groups) / saponification value

  As a specific example of the plasticizer in the present invention, from the viewpoint of excellent moldability and impact resistance of a polylactic acid resin molded article, an ester of acetic acid and glycerin ethylene oxide average 3 to 9 mol adduct, acetic acid and diglycerin Average addition of alkyl ether ester of polyhydric alcohol such as ester with propylene oxide average 4 to 12 mol adduct, acetic acid and ethylene glycol with average addition mole number of polyethylene glycol 4-9, succinic acid and ethylene oxide Esters of polyethylene glycol monomethyl ether having 2 to 4 moles, esters of polyethylene glycol monomethyl ether having an average addition mole number of adipic acid and ethylene oxide of 1,3,6-hexanetricarboxylic acid and ethylene oxide The average number of moles added is 2-3 Esters of polyvalent carboxylic acids and polyethylene glycol monomethyl ethers such as esters of triethylene glycol monomethyl ether is more preferable. From the viewpoint of excellent formability, impact resistance and plasticizer bleed resistance of a polylactic acid resin molding, an ester of succinic acid, adipic acid or 1,3,6-hexanetricarboxylic acid and polyethylene glycol monomethyl ether, and acetic acid And at least one selected from the group consisting of an ester of glycerin or ethylene glycol with an ethylene oxide adduct, an ester of acetic acid with an average of 3 to 6 mol of ethylene oxide adduct of glycerin, an average addition mol of acetic acid with ethylene oxide Esters of polyethylene glycol having a number of 4-6, esters of polyethylene glycol monomethyl ether having an average addition mole number of succinic acid and ethylene oxide of 2-3, esters of adipic acid and diethylene glycol monomethyl ether, 1, 3, 6 -Hexa Esters of tricarboxylic acid and diethylene glycol monomethyl ether are more preferable. From the viewpoints of moldability and impact resistance of the polylactic acid resin molded article and bleeding resistance, volatilization resistance and irritating odor of the plasticizer, an ester of succinic acid and triethylene glycol monomethyl ether is more preferable.

  In addition, it is preferable that the ester in this invention is all saturated esterified ester from a viewpoint of fully exhibiting the function as a plasticizer.

  The reason why the effect of the present invention is improved by a specific plasticizer is not clear, but the plasticizer has two or more ester groups in the molecule, and at least one alcohol component constituting the ester is a hydroxyl group 1. A compound obtained by adding an average of 0.5 to 5 moles of alkylene oxide having 2 to 3 carbon atoms per unit, preferably a polysiloxane having 2 or more ester groups in the molecule and an average added mole number of ethylene oxide of 3 to 9 When the compound has an oxyethylene chain (more preferably has a methyl group, preferably 2 or more), its heat resistance and compatibility with the polylactic acid resin are good. Therefore, the bleed resistance is improved and the softening effect of the polylactic acid resin is also improved. It is considered that when the polylactic acid resin is crystallized, the growth rate is also improved by improving the softening of the polylactic acid resin. As a result, since the polylactic acid resin retains flexibility even at a low mold temperature, crystallization of the polylactic acid resin proceeds in a short mold holding time, and good moldability is expected.

  The content of the plasticizer in the polylactic acid resin composition of the present invention is preferably 5 to 50 parts by weight with respect to 100 parts by weight of the polylactic acid resin, from the viewpoint of obtaining a sufficient crystallization speed and impact resistance, and 7 to 30. More preferably, by weight, more preferably 8-30 parts by weight.

[Organic nucleating agent]
The organic nucleating agent in the present invention has a hydroxy fatty acid ester and a hydroxyl group and an amide group in the molecule from the viewpoints of moldability, heat resistance, impact resistance and bloom resistance of the organic nucleating agent. It is preferable to contain at least one selected from the group consisting of compounds (hereinafter referred to as crystal nucleating agent (1)).

  In the present invention, the hydroxy fatty acid ester is preferably a hydroxy fatty acid ester having 12 to 22 carbon atoms of fatty acid from the viewpoint of improving the crystallization speed and compatibility with the polylactic acid resin, and has two or more hydroxyl groups in the molecule. Further, hydroxy fatty acid esters having two or more ester groups are more preferable. In addition, the melting point of the hydroxy fatty acid ester is preferably 65 ° C. or higher, more preferably 70 ° C. to 200 ° C., from the viewpoint of improving the crystallization speed. The melting point of the hydroxy fatty acid ester is determined from the crystal melting endothermic peak temperature by the temperature rising method of differential scanning calorimetry (DSC) based on JIS-K7121.

  Specific examples of the hydroxy fatty acid ester include 12-hydroxystearic acid triglyceride, 12-hydroxystearic acid diglyceride, 12-hydroxystearic acid monoglyceride, pentaerythritol mono-12-hydroxystearate, pentaerythritol di-12-hydroxystearate. And hydroxy fatty acid esters such as pentaerythritol-tri-12-hydroxystearate. From the viewpoints of moldability, heat resistance, impact resistance of the polylactic acid resin molded article, and bloom resistance of the organic nucleating agent, 12-hydroxystearic acid triglyceride is preferable.

  The compound having a hydroxyl group and an amide group in the molecule is preferably an aliphatic amide having a hydroxyl group from the viewpoint of improving the compatibility with the polylactic acid resin, having two or more hydroxyl groups and having two or more amide groups. The aliphatic amide having is more preferable. The melting point of the compound having a hydroxyl group and an amide group in the molecule is preferably 65 ° C. or higher, from the viewpoint of improving the dispersibility of the organic nucleating agent at the time of kneading and improving the crystallization rate, and is 70 to 220 ° C. Is more preferable, and 80-190 degreeC is still more preferable.

  Specific examples of the compound having a hydroxyl group and an amide group in the molecule include hydroxy fatty acid monoamides such as 12-hydroxystearic acid monoethanolamide, methylene bis 12-hydroxystearic acid amide, ethylene bis 12-hydroxystearic acid amide, and hexamethylene. And hydroxy fatty acid bisamides such as bis-12-hydroxystearic acid amide. From the viewpoint of moldability, heat resistance, impact resistance and bloom resistance of the polylactic acid resin composition, methylene bis 12-hydroxystearic acid amide, ethylene bis 12-hydroxystearic acid amide, hexamethylene bis 12-hydroxystearic acid amide, etc. The alkylene bishydroxystearic acid amide is preferably ethylene bis 12-hydroxystearic acid amide.

  The organic nucleating agent in the present invention includes a crystal nucleating agent (1), phenylphosphonic acid metal salt, phosphorus, from the viewpoint of moldability, heat resistance, impact resistance and bloom resistance of the organic nucleating agent. Metal salts of acid esters, metal salts of aromatic sulfonic acid dialkyl esters, metal salts of rosin acids, aromatic carboxylic acid amides, rosin acid amides, carbohydrazides, N-substituted ureas, salts of melamine compounds and uracils It is more preferable to use at least one selected from the group (hereinafter referred to as crystal nucleating agent (2)).

  Specific examples of the crystal nucleating agent (2) in the present invention include phenylphosphonic acid metal salts such as phenylphosphonic acid zinc salt; sodium-2,2′-methylenebis (4,6-di-t-butylphenyl) phosphate, Metal salts of phosphate esters such as aluminum bis (2,2′-methylenebis-4,6-di-t-butylphenyl phosphate); dimethyl dibarium 5-sulfoisophthalate, dimethyl dicalcium 5-sulfoisophthalate, etc. Metal salts of aromatic sulfonic acid dialkyl esters; metal salts of rosin acids such as potassium methyldehydroabietic acid; trimesic acid tris (t-butylamide), m-xylylenebis 12-hydroxystearic acid amide, 1,3,5-benzenetricarboxylic acid Aromatic carboxylic amides such as acid tricyclohexylamide; p-xylyl Carbohydrazide such as decamethylene dicarbonyl dibenzoyl hydrazide; rosin acid amides such as Nbisurojin acid amide N- substituted ureas such as xylene-bis-stearyl urea; 6-uracils such as methyl uracil can be mentioned.

  Among the crystal nucleating agents (2) in the present invention, phenylphosphonic acid metal salts are preferable from the viewpoint of crystallization speed.

The phenylphosphonic acid metal salt used in the present invention is a phenylphosphonic acid metal salt having a phenyl group which may have a substituent and a phosphonic group (—PO (OH) ₂ ). Includes an alkyl group having 1 to 10 carbon atoms, an alkoxycarbonyl group having 1 to 10 carbon atoms in an alkoxy group, and the like. 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.

  Examples of the metal salt of phenylphosphonic acid include salts of lithium, sodium, magnesium, aluminum, potassium, calcium, barium, copper, zinc, iron, cobalt, nickel, and the like, and zinc salts are preferable.

  In the present invention, when an organic nucleating agent is used in combination with a crystal nucleating agent (1) and a crystal nucleating agent (2), preferably a phenylphosphonic acid metal salt, these ratios are from the viewpoint of expressing the effects of the present invention. , Crystal nucleating agent (1) / crystal nucleating agent (2) (weight ratio) = 20/80 to 80/20 is preferable, 30/70 to 70/30 is more preferable, and 40/60 to 60/40 is still more preferable .

  The polylactic acid resin composition of the present invention has a special effect that the crystallization rate is good and the heat resistance is excellent. The reason why the particularly excellent effect of the present invention can be manifested is not clear, but in the presence of a polyresin containing a polylactic acid having an optical purity of 99% or more and 50% by weight or more and a specific plasticizer, the synergistic effect thereof causes remarkable crystallization. It is considered that the conversion speed is improved. Furthermore, the crystal nucleating agent (1) is dissolved during the melt-kneading of the polylactic acid resin composition, and a large number of crystal nuclei can be generated in the cooling step during molding, and the crystal nucleating agent (2) is a metal ion, By having an amide group, NH group, etc., the interaction (adsorbability) with the polylactic acid resin is excellent, so that the crystallization speed of the present invention is synergistically good and the heat resistance is excellent. It is thought to do.

  From the viewpoint of obtaining a sufficient crystallization rate, the total content of the organic nucleating agent in the polylactic acid resin composition of the present invention is preferably 0.05 to 5 parts by weight with respect to 100 parts by weight of the polylactic acid resin, and is 0.10. -3 parts by weight is more preferable, and 0.2-2 parts by weight is more preferable.

[Hydrolysis inhibitor]
The polylactic acid resin composition of the present invention further contains a hydrolysis inhibitor. Examples of the hydrolysis inhibitor include carbodiimide compounds such as polycarbodiimide compounds and monocarbodiimide compounds, and polycarbodiimide compounds are preferred from the viewpoint of moldability of polylactic acid resin molded articles, and heat resistance and moldability of polylactic acid resin molded articles. From the viewpoints of fluidity, impact resistance and bloom resistance of the organic nucleating agent, monocarbodiimide compounds are more preferred.

  Examples of the polycarbodiimide compound include poly (4,4′-diphenylmethanecarbodiimide), poly (4,4′-dicyclohexylmethanecarbodiimide), poly (1,3,5-triisopropylbenzene) polycarbodiimide, and poly (1,3,3). 5-triisopropylbenzene and 1,5-diisopropylbenzene) polycarbodiimide and the like, and examples of the monocarbodiimide compound include N, N′-di-2,6-diisopropylphenylcarbodiimide.

  The carbodiimide compounds may be used alone or in combination of two or more in order to satisfy the moldability, heat resistance, impact resistance and bloom resistance of the organic nucleating agent of the polylactic acid resin molded product. Poly (4,4′-dicyclohexylmethane carbodiimide) is obtained from carbodilite LA-1 (manufactured by Nisshinbo Industries, Inc.), poly (1,3,5-triisopropylbenzene) polycarbodiimide and poly (1,3,5-trimethyl). Isopropylbenzene and 1,5-diisopropylbenzene) polycarbodiimide are stabuxol P and stabuxol P-100 (Rhein Chemie), and N, N'-di-2,6-diisopropylphenylcarbodiimide is stavaxol I (Rhein Chemie). ) Can be purchased and used separately.

  The total content of the hydrolysis inhibitor in the polylactic acid resin composition of the present invention is preferably 0.05 to 20 parts by weight with respect to 100 parts by weight of the polylactic acid resin, from the viewpoint of moldability of the polylactic acid resin molded body, 0.10 to 20 parts by weight is more preferable.

[Inorganic filler]
The composition of the present invention further contains an inorganic filler from the viewpoint of improving physical properties such as rigidity. As the inorganic filler in the present invention, it is possible to use fibrous, plate-like, granular, and powdery inorganic substances that are usually used for reinforcing thermoplastic resins.

  Specific examples of the fibrous inorganic substance include glass fiber, asbestos fiber, carbon fiber, graphite fiber, metal fiber, potassium titanate whisker, aluminum borate whisker, magnesium whisker, silicon whisker, wollastonite, sepiolite, Examples include asbestos, slag fiber, zonolite, elastadite, gypsum fiber, silica fiber, silica / alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, and boron fiber. Among these fibrous inorganic substances, carbon fiber, glass fiber, and wollastonite are preferable. The aspect ratio of the fibrous inorganic filler is preferably 5 or more, more preferably 10 or more, and further preferably 20 or more.

  The total content of the fibrous inorganic substance in the polylactic acid resin composition of the present invention is 1 to 100 parts by weight of the polylactic acid resin from the viewpoint of obtaining a sufficient crystallization speed, moldability, heat resistance and impact resistance. 200 parts by weight is preferred, 3-50 parts by weight is more preferred, and 5-40 parts by weight is even more preferred.

  Specifically, as the plate-like, granular, powder-like inorganic substances, glass flakes, non-swellable mica, swellable mica, graphite, metal foil, ceramic beads, talc, clay, mica, sericite, zeolite, bentonite, Organically modified bentonite, montmorillonite, organically modified montmorillonite, dolomite, smectite, kaolin, finely divided silicic acid, feldspar powder, potassium titanate, shirasu balloon, calcium carbonate, magnesium hydroxide, aluminum hydroxide, magnesium carbonate, barium sulfate, calcium oxide, Examples thereof include aluminum oxide, silica, magnesium oxide, titanium oxide, aluminum silicate, silicon oxide, gypsum, novaculite, dosonite, and clay. Among these inorganic fillers, mica, talc and kaolin are preferable, talc or mica is more preferable, and talc is further preferable.

  The plate-like, granular and powdery inorganic substances may be coated or focused with a thermoplastic resin such as an ethylene / vinyl acetate copolymer or a thermosetting resin such as an epoxy resin. It may be treated with a coupling agent.

  In addition, the average particle size of the plate-like, granular, and powdery inorganic materials is preferably 0.1 to 20 μm and more preferably 0.1 to 10 μm from the viewpoint of obtaining good dispersibility. The average particle diameter of the inorganic substance can be obtained by measuring a volume-based median system by a diffraction / scattering method. For example, as a commercially available apparatus, a laser diffraction / light scattering particle size measuring apparatus LS230 manufactured by Coulter, Inc. can be mentioned.

  In the polylactic acid resin composition of the present invention, the content of the plate-like, granular and powdery inorganic substances is 100 wt.% From the viewpoint of obtaining a sufficient crystallization speed, moldability, heat resistance and impact resistance. The amount is preferably 1 to 200 parts by weight, more preferably 3 to 50 parts by weight, and still more preferably 5 to 40 parts by weight with respect to parts.

  Further, in the present invention, the inorganic filler preferably contains a fibrous inorganic filler from the viewpoint of obtaining a sufficient crystallization speed, moldability, heat resistance and impact resistance, and further, plate-like and granular It is preferable to use at least one of powdery inorganic substances in combination.

  The weight ratio in the polylactic acid resin composition of the present invention between the fibrous inorganic substance and the plate-like, granular, and powdery inorganic substance (weight of the fibrous inorganic substance / total weight of the plate-like, granular, and powdery inorganic substance) is: From the same viewpoint, 1/9 to 5/5 is preferable, and 2/8 to 5/5 is more preferable.

[Shock absorber]
The composition of the present invention further contains an impact-resistant absorbent from the viewpoint of improving physical properties such as flexibility. As the impact-resistant absorbent used in the present invention, organic fibers, rubber, compatibilizing agents and the like that are usually used for improving flexibility in thermoplastic resins can be used.

  As the organic fiber, polyethylene fiber, polyketone fiber, PET fiber, aromatic polyamide fiber (aramid fiber), polyphenylene sulfide (PPS) fiber, polyimide fiber, fluorine fiber, etc. can be suitably used, but the polylactic acid resin composition From the viewpoint of achieving both flexibility, rigidity and heat resistance, it is preferable to use an aromatic polyamide fiber.

  The type of rubber is not particularly limited as long as it is composed of a polymer component having rubber elasticity. For example, a rubber composed of a natural rubber, an acrylic component, a silicone component, a styrene component, a nitrile component, a conjugated diene component, a urethane component, an ethylene propylene component, or the like is used. Commercially available products include, for example, manufactured by Mitsubishi Rayon [Methbrene S type (silicone / acrylic rubber), Methbrene W type (acrylic rubber), Methbrene C type (methyl methacrylate / butadiene / styrene resin)], Kaneka [Kane Ace] , Manufactured by Rohm and Haas (paraloid (methyl methacrylate, butadiene, styrene resin)), manufactured by Gantz Kasei (staphyloid (acrylic rubber)), manufactured by Kuraray (paraface (acrylic rubber)), and the like. These can be used alone or in combination of two or more.

The compatibilizing agent is preferably used in order to increase the compatibility between resins when the polylactic acid resin composition contains a resin other than the polylactic acid resin. Although not particularly limited as long as it softens the polylactic acid resin, from the viewpoint of impact resistance of the resin composition,
Compatibilizer (1): ethylene / vinyl acetate copolymer compatibilizer (2): ethylene / (meth) acrylic ester copolymer compatibilizer (3): acid anhydride group, carboxyl group, amino group, Polyolefin resin compatibilizer (4) having at least one functional group (substituent) selected from the group consisting of imino group, alkoxysilyl group, silanol group, silyl ether group, hydroxyl group, and epoxy group: acid An acrylic having at least one functional group (substituent) selected from the group consisting of an anhydride group, a carboxyl group, an amino group, an imino group, an alkoxysilyl group, a silanol group, a silyl ether group, a hydroxyl group, and an epoxy group Or at least one selected from the group consisting of a compatibilizer (5): polyester resin and a compatibilizer (6): ionomer resin is preferred. Arbitrariness. Specifically, “Bond First 7M, 7B, 2C” manufactured by Sumitomo Chemical Co., Ltd. (polyethylene resin having an epoxy group), “ARUFON” manufactured by Toagosei Co., Ltd. (acrylic resin or styrene resin having an epoxy group), DIC “Plamate PD-350” (PLA-aliphatic polyester copolymer) manufactured by the company can be suitably used.

  These compatibilizers can be used alone or in combination of two or more.

  The melt flow rate (MFR) of the compatibilizer is preferably 3 to 15 g / 10 minutes, more preferably 5 to 10 g / 10 minutes, from the viewpoint of impact resistance and moldability of the resin composition.

  From the viewpoint of impact resistance and moldability of the resin composition, the total content of the impact-absorbing agent in the polylactic acid resin composition of the present invention is preferably 2 to 50 parts by weight with respect to 100 parts by weight of the polylactic acid resin, 3-40 weight part is more preferable, and 5-30 weight part is further more preferable.

  The polylactic acid resin composition of the present invention can further contain a flame retardant. Specific examples of the flame retardant include halogen compounds containing bromine or chlorine, antimony compounds such as antimony trioxide, inorganic hydrates or hydroxides (for example, metal hydroxide such as aluminum hydroxide and magnesium hydroxide). Product), phosphorus compounds, and nitrogen compounds (melamine cyanurate). From the viewpoint of safety, an inorganic hydrate or an inorganic hydroxide is preferable.

  The content of the flame retardant is preferably 10 to 60 parts by weight and more preferably 15 to 55 parts by weight with respect to 100 parts by weight of the polylactic acid resin.

  In addition to the above, the polylactic acid resin composition of the present invention further contains other components such as a hindered phenol or a phosphite antioxidant, or a hydrocarbon wax or a lubricant that is an anionic surfactant. be able to. 0.05-3 weight part is preferable with respect to 100 weight part of polylactic acid resin, and, as for each content of antioxidant and a lubricant, 0.10-2 weight part is more preferable.

  The polylactic acid resin composition of the present invention includes an antistatic agent, an antifogging agent, a light stabilizer, an ultraviolet absorber, a pigment, an antifungal agent, an antibacterial agent, a foaming agent and the like as components other than the above. It can contain in the range which does not prevent achievement of the objective.

[Polylactic acid resin composition]
The polylactic acid resin composition of the present invention can be prepared without particular limitation as long as it contains the polylactic acid resin, a plasticizer, an organic nucleating agent, a hydrolysis inhibitor, an inorganic filler, and an impact absorber. it can.

  The polylactic acid resin composition of the present invention preferably has a half crystallization time at 80 ° C. of 1 minute or less from the viewpoint of exhibiting excellent moldability at a mold temperature of 80 ° C. or less, and 0.8 minutes or less. More preferably, it is more preferably 0.6 minutes or less. In addition, the half crystallization time in 80 degreeC is the value calculated | required by the method shown in an Example.

  Since the polylactic acid resin composition of the present invention has good processability and can be processed at a low temperature of, for example, 200 ° C. or less, there is an advantage that the plasticizer is hardly decomposed. Can be used for applications.

[Polylactic acid resin molded article and method for producing the same]
The polylactic acid resin molded product of the present invention can be obtained by molding the polylactic acid resin composition of the present invention. Specifically, for example, a plasticizer, an organic nucleating agent, a hydrolysis inhibitor, an inorganic filler, and an impact absorber are mixed while melting a polylactic acid resin using an extruder or the like, and then obtained. The molten material is filled into a mold by an injection molding machine or the like and molded.

  A preferred method for producing the polylactic acid resin molded article of the present invention is a polylactic acid resin, a plasticizer, an organic nucleating agent, a hydrolysis inhibitor, an inorganic filler containing 50% by weight or more of polylactic acid having an optical purity of 99.0% or more. , And a step of melt-kneading the polylactic acid resin composition containing the impact-resistant absorbent (hereinafter referred to as step (1)), a step of filling the obtained melt into a mold of 80 ° C. or less and molding (hereinafter referred to as step (1)) It is a method consisting of step (2)).

  In the present invention, after passing through step (1), it is cooled to an amorphous state (that is, a condition that the degree of crystallinity measured by high-angle X-ray diffraction is 1% or less), and then step (2) is performed. The method of performing and the method of performing the step (2) immediately after cooling after the step (1) are preferable. From the viewpoint of the effect of improving the crystallization speed of the present invention, the method is cooled after the step (1). A method in which step (2) is performed immediately is more preferable.

  As a specific example of the step (1), it can be carried out by a usual method, for example, a method of mixing a plasticizer, an organic nucleating agent or the like while melting a polylactic acid resin using an extruder or the like. . The temperature of the step (1) is not less than the melting point (Tm) of the polylactic acid resin from the viewpoint of dispersibility of plasticizers, organic nucleating agents, etc., preferably in the range of Tm to Tm + 100 ° C., more preferably Tm to It is the range of Tm + 50 ° C. For example, Preferably it is 170-240 degreeC, More preferably, it is 170-220 degreeC.

  As a specific example of the step (2) in the method for producing a molded article of the present invention, for example, a method of filling a polylactic acid resin composition in a mold of 80 ° C. or less with an injection molding machine or the like, and the like are mentioned. It is done. The mold temperature in the step (2) is preferably 10 to 80 ° C., more preferably 10 to 80 ° C., and further preferably 15 to 80 ° C., from the viewpoint of improving the crystallization speed and improving workability. is there.

  In the step (2) of the present invention, the holding time in the mold is preferably within 60 seconds, more preferably within 45 seconds, and further preferably within 30 seconds from the viewpoint of improving productivity.

  EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example. In addition, unless otherwise indicated, the part in an example is a weight part.

[Weight average molecular weight of polylactic acid resin (Mw)]
The weight average molecular weight (Mw) was measured by GPC (gel permeation chromatography) under the following measurement conditions.
<Measurement conditions>
Column: GMHHR-H + GMHHR-H
Column temperature: 40 ° C
Detector: RI
Eluent: Chloroform Flow rate: 1.0 mL / min
Sample concentration: 1 mg / mL
Injection volume: 0.1mL
Conversion standard: Polystyrene

[Optical purity of polylactic acid]
The optical purity is determined according to the D-body content measurement method described in “Voluntary Standard for Food Containers and Packaging Made of Synthetic Resins such as Polyolefins, 3rd Edition, Revised June 2004, Part 3 Sanitation Test Method P12-13”. The measurement was performed under the conditions. Specifically, sodium hydroxide / methanol is added to precisely weighed polylactic acid, set in a water bath shaker set at 65 ° C., and hydrolyzed until the resin content becomes a homogeneous solution. Dilute hydrochloric acid is added to the completed alkaline solution to neutralize it, and the decomposition solution is dissolved in pure water. Is adjusted to be in the range of 3 to 7, and the volumetric flask is quantified and filtered through a membrane filter (0.45 μm). The optical purity of was determined.
<HPLC measurement conditions>
Column: Optical resolution column
Sumichiral OA6100 (46mmφ × 150mm, 5μm), Precolumn manufactured by Sumika Chemical Analysis Co., Ltd .: Optical resolution column
Sumichiral QA6100 (4 mmφ × 10 mm, 5 μm), column temperature manufactured by Sumika Chemical Analysis Co., Ltd .: 25 ° C.
Mobile phase: 1.5% copper sulfate aqueous solution containing 2.5% methanol Mobile phase flow rate: 1.0 ml / min Detector: UV detector (UV254 nm)
Injection volume: 20 μl

<Production Example 1 of Stereo Complex Polylactic Acid>
Poly-L-lactic acid (Ecoplastic U'z S-17, optical purity 99.7%, weight average molecular weight 110000) manufactured by Toyota Motor Corporation, and poly-D-lactic acid (TECHNICAL HIGH IV, optical purity 99.000 manufactured by PURAC) A stereocomplex polylactic acid A was obtained by melting and kneading an equal amount (weight) of 0% and a weight average molecular weight of 130000) using a kneader manufactured by Moriyama Seisakusho at a cylinder temperature of 280 ° C. for about 5 minutes in a nitrogen atmosphere. It was. Using a differential scanning calorimetry (DSC) apparatus, the melting point (temperature of melting peak) of poly-L-lactic acid, poly-D-lactic acid and kneaded product (stereocomplex polylactic acid A) is from room temperature (25 ° C) to 10 ° C. When measured at a rate of temperature increase of 250 ° C./min, poly-L-lactic acid and poly-D-lactic acid were observed to have a melting peak of 160 ° C., whereas the kneaded product had a melting peak of 203 ° C. Was observed.

<Plasticizer Production Example 1 (Diester of Succinic Acid and Triethylene Glycol Monomethyl Ether)>
A 3L flask equipped with a stirrer, thermometer, and dehydration tube was charged with 500 g of succinic anhydride, 2463 g of triethylene glycol monomethyl ether, and 9.5 g of paratoluenesulfonic acid monohydrate, and nitrogen (500 mL / min) was blown into the space. The reaction was carried out at 110 ° C. for 15 hours under reduced pressure (4 to 10.7 kPa). The acid value of the reaction solution was 1.6 (KOHmg / g). Add 27g of adsorbent KYOWARD 500SH (manufactured by Kyowa Chemical Industry Co., Ltd.) to the reaction solution, stir at 80 ° C and 2.7kPa for 45 minutes and filter, then triethylene glycol monomethyl at a liquid temperature of 115-200 ° C and pressure of 0.03kPa The ether was distilled off, and after cooling to 80 ° C., the remaining liquid was filtered under reduced pressure to obtain a diester of succinic acid and triethylene glycol monomethyl ether as a filtrate. The obtained diester had an acid value of 0.2 (KOHmg / g), a saponification value of 276 (KOHmg / g), a hydroxyl value of 1 or less (KOHmg / g), and a hue of APHA200.

<Plasticizer Production Example 2 (Triester Compound with Ethylene Oxide Adduct obtained by Adding 3 Mole of Ethylene Oxide to Acetic Acid and Glycerin)>
An autoclave is charged with a specified amount of 3 moles of ethylene oxide to 1 mole of concentrated glycerin for cosmetics manufactured by Kao Corporation. A constant pressure of 0.3 MPa is added using 1 mole% KOH as a catalyst, and the pressure is kept at 150 ° C until the pressure becomes constant. Then, the reaction mixture was cooled to 80 ° C. to obtain a catalyst-unneutralized product. KYOWARD 600S (manufactured by Kyowa Chemical Industry Co., Ltd.) as an adsorbent for the catalyst was added to this product 8 times the catalyst weight, and adsorption treatment was performed at 80 ° C. for 1 hour under slight nitrogen pressure. Further, the adsorbent was filtered through a Nutse obtained by pre-coating Radiolight # 900 on No. 2 filter paper on the treated liquid to obtain a 3 mol adduct of glycerin ethylene oxide (hereinafter referred to as POE (3) glycerin). This was charged into a four-necked flask, heated to 105 ° C and stirred at 300 r / min, and acetic anhydride was added dropwise at a ratio of 3.6 mol to 1 mol of POE (3) glycerin in about 1 hour. I let you. After dropping, the mixture was aged at 110 ° C. for 2 hours and further aged at 120 ° C. for 1 hour. After aging, unreacted acetic anhydride and by-product acetic acid were topped under reduced pressure and further steamed to obtain POE (3) glycerin triacetate.

Examples 1-12, Comparative Examples 1-6
As the polylactic acid resin composition, the composition raw materials shown in Table 1 are melt-kneaded at 190 ° C. with a twin screw extruder (Ikegai Co., Ltd., PCM-45), strand cut, and pellets of the polylactic acid resin composition Got. The obtained pellets were dried at 70 ° C. under reduced pressure for 1 day, and the water content was adjusted to 500 ppm or less.

The raw materials in Table 1 are as follows.
<Polylactic acid resin>
* 1: Polylactic acid resin (manufactured by Toyota Motor Corporation, Eco Plastic U'z S-17)
(Optical purity 99.7%, weight average molecular weight 110000)
* 2: Stereo complex PLA, stereo complex polylactic acid A produced above
* 3: Polylactic acid resin (NatureWorks LLC, NatureWorks 4032D)
(Optical purity 98.5%, weight average molecular weight 200000)
<Plasticizer>
* 4: (MeEO ₃ ) ₂ SA, diester compound of succinic acid and triethylene glycol monomethyl ether prepared above, average molecular weight 410
* 5: (AcEO ₃ ) ₃ Gly, triester compound of ethylene oxide adduct obtained by adding 3 mol of ethylene oxide to acetic acid and glycerin prepared above * 6: DAIFACTY-101, adipic acid, diethylene glycol monomethyl ether / Benzyl alcohol = 1/1 mixed diester (manufactured by Daihachi Chemical Industry Co., Ltd.), average molecular weight 338
<Organic nucleating agent>
* 7: Ethylene bis 12-hydroxystearic acid amide (Nihon Kasei Co., Ltd., SLIPAX H)
* 8: Unsubstituted zinc phenylphosphonate (Nissan Chemical Industries)
<Hydrolysis inhibitor>
* 9: Starvacol I-LF (Rhein Chemie Japan)
* 10: Starvacol P (Rhein Chemie Japan)
<Inorganic filler>
* 11: Talc (Nippon Talc Co., Ltd., MicroAceP-6)
* 12: Glass fiber (T187, manufactured by Nippon Electric Glass Co., Ltd.)
<Shock absorber>
* 13: Aramid fiber (Teijin Techno Products, ZCF T322EH 3-12)
* 14: Metabrene S-2006 (Mitsubishi Rayon Co., Ltd.)
* 15: Bond First 7M (Sumitomo Chemical Co., Ltd.)
<Flame Retardant>
* 16: Leophos 65 (Phosphorus flame retardant, manufactured by Ajinomoto Fine Techno)
* 17: Aluminum hydroxide (inorganic flame retardant, Nippon Light Metal Co., Ltd., BF013)
* 18: Melamine cyanurate (Nitrogen flame retardant, manufactured by Nissan Chemical Industries, MC-610)

  Next, the pellets thus obtained were injection molded using an injection molding machine (J75E-D manufactured by Nippon Steel Works) with a cylinder temperature of 200 ° C., and a test piece [flat plate at a mold temperature of 80 ° C. (70 mm × 40 mm × 3 mm), prismatic test piece (125 mm × 12 mm × 6 mm) and prismatic test piece (63 mm × 12 mm × 5 mm)], and polylactic acid of Examples 1-12 and Comparative Examples 1-6 A molded body of the resin composition was obtained. The mold holding time of the prismatic test piece (125 mm × 12 mm × 6 mm) and the prismatic test piece (63 mm × 12 mm × 5 mm) is 30 seconds.

  In addition, when shape | molding a molded object, the metal mold | die holding time required for mold release of the said test piece was evaluated on the following reference | standard. These results are shown in Table 1.

<Evaluation criteria for mold holding time required for mold release>
At a mold temperature of 80 ° C., the time required until each test piece was not deformed and was easily taken out was defined as the mold holding time (also referred to as semi-crystallization time) necessary for mold release. Note that the higher the melt crystallization speed of the test piece in the mold and the runner part, the shorter the mold holding time required for mold release.

  Next, the physical properties of the molded bodies of the polylactic acid resin compositions of Examples 1 to 12 and Comparative Examples 1 to 6 were examined according to the methods of Test Examples 1 and 2 below. The results are shown in Table 1.

[Test Example 1] (Heat resistance)
For prismatic specimens (125 mm x 12 mm x 6 mm), using a heat distortion temperature measuring machine (B-32 manufactured by Toyo Seiki Seisakusho) based on JIS K 7191, the temperature when the load is 1.25 MPa (° C) ) (Heat distortion temperature) was measured. A higher heat distortion temperature (° C.) indicates better heat resistance.

[Test Example 2] (Impact resistance)
The Izod impact strength (J / m) of a prismatic test piece (63 mm × 12 mm × 5 mm) was measured using an impact tester (type 863 manufactured by Ueshima Seisakusho Co., Ltd.) based on JIS K7110. The higher the Izod impact strength (J / m), the better the impact resistance.

  From the results in Table 1, containing polylactic acid resin containing 50% by weight or more of polylactic acid having an optical purity of 99.0% or more, plasticizer, organic nucleating agent, hydrolysis inhibitor, inorganic filler, and impact-resistant absorber The polylactic acid resin compositions (1 to 12) of the present invention could be molded at a mold temperature of 80 ° C. with a short mold holding time. On the other hand, the comparative polylactic acid resin composition using polylactic acid having an optical purity of less than 99.0% could not be molded at the mold temperature of 80 ° C. within the same mold holding time as the examples. It was.

  In addition, from the results of Table 1, a polylactic acid resin, a plasticizer, an organic nucleating agent, a hydrolysis inhibitor, an inorganic filler, and an impact resistant absorbent containing 50% by weight or more of polylactic acid having an optical purity of 99.0% or more The polylactic acid resin compositions (1 to 12) of the present invention containing succinic acid exhibited heat resistance of 80 ° C. or higher, impact strength of 100 J / m or higher, and excellent durability. On the other hand, the polylactic acid resin composition of the comparative example using polylactic acid having an optical purity of less than 99.0% could not exhibit excellent heat resistance and impact resistance.

  The polylactic acid resin composition of the present invention can be suitably used for various industrial uses such as household goods, household appliance parts, packaging materials for household appliance parts, and automobile parts.

Claims (5)

A polylactic acid resin composition comprising a polylactic acid resin, a plasticizer, an organic nucleating agent, a hydrolysis inhibitor, an inorganic filler, and an impact absorber, wherein the polylactic acid resin has an optical purity of 99.0%. The above polylactic acid is contained in an amount of 50% by weight or more, the plasticizer has two or more ester groups in the molecule, and at least one alcohol component constituting the ester has 2 to 2 carbon atoms per hydroxyl group. compounds der the alkylene oxide and the average 0.5 to 5 mols of 3 is, the inorganic filler is contained and an inorganic fibrous, plate, granular, and at least one powdered inorganic, its weight the ratio (inorganic fibrous weight / plate, granular, the total weight of the powdery inorganic substance) is Ru 1 / 9-5 / 5 der, polylactic acid resin composition.   The plasticizer is at least one selected from the group consisting of an ester of succinic acid or adipic acid and polyethylene glycol monomethyl ether, and an ester of acetic acid and glycerin or an ethylene oxide adduct of ethylene glycol. Polylactic acid resin composition.   The polylactic acid resin composition according to claim 1 or 2, wherein the organic nucleating agent contains at least one selected from the group consisting of a hydroxy fatty acid ester and a compound having a hydroxyl group and an amide group in the molecule.   Organic nucleating agents are further phenylphosphonic acid metal salts, phosphoric acid ester metal salts, aromatic sulfonic acid dialkyl ester metal salts, rosin acid metal salts, aromatic carboxylic acid amides, rosin acid amides, carbohydrazides, N- The polylactic acid resin composition according to claim 3, comprising at least one selected from the group consisting of substituted ureas, salts of melamine compounds and uracils.   The polylactic acid resin molded object formed by shape | molding the polylactic acid resin composition in any one of Claims 1-4.