JP2013199640A - Crosslinked polylactic acid resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polylactic acid resin composition being capable of suppressing color staining when contacting printed matter and the like, and being excellent in heat resistance; and to provide a molding obtained from the composition, and a method for producing the same.SOLUTION: A crosslinked polylactic acid resin composition is made by blending a crosslinked polylactic acid resin (A) and a carbonate ester having a solubility parameter value (SP value) by Fedors method of 10.1 to 11.2 and represented by the following formula (I). R-O-CO-R-CO-[(OR)O-CO-R-CO-]OR(I) wherein Ris a 1-4C alkyl group; Ris a 2-4C alkylene group; Ris a 2-6C alkylene group; m is the number of 1 to 6, and n is the number of 1 to 12; and all Rmay be identical or different, and all Rmay be identical or different.

Description

  The present invention relates to a crosslinked polylactic acid resin composition. More specifically, the present invention relates to a cross-linked polylactic acid resin composition that can be suitably used as a housing or part for information / home appliances, daily necessities, stationery, cosmetics, and the like, and a molded body obtained by injection molding the composition.

  Polylactic acid resin is inexpensive because L-lactic acid as a raw material is produced by fermentation using sugar extracted from corn, straw, etc., and the carbon dioxide emission is extremely low because the raw material is derived from plants. In addition, due to the characteristics of the resin such as high rigidity and high transparency, its use is currently expected.

  Patent Document 1 discloses a plasticizer (B) having a polylactic acid resin (A) and a solubility parameter value (SP value) of 10.6 to 11.6 for the purpose of obtaining a transparent biodegradable resin composition. ) Is contained in a weight ratio of (A) / (B) = 100/10 to 100/80, a biodegradable resin composition is disclosed.

  Patent Document 2 discloses that a lactic acid-based polymer (A) containing polylactic acid as a main component, a dibasic acid and a dihydric alcohol for the purpose of providing a lactic acid-based polymer having excellent heat resistance and transparency. As an essential constituent, a polyester plasticizer (B) having a total acid value and hydroxyl value of 40 or less, which is composed of repeating units of the above and whose ends are sealed with a monobasic acid and / or a monohydric alcohol. A lactic acid polymer composition characterized by containing is disclosed.

JP-A-10-316846 Japanese Patent Laid-Open No. 7-118513

  However, the conventional technology cannot solve the problem that color transfer occurs in a molded product when a printed matter, colored resin or rubber, or cosmetics such as a foundation comes into contact with a load on the polylactic acid resin molded product. It was.

  An object of the present invention is to provide a polylactic acid resin composition that is capable of suppressing color transfer when coming into contact with a printed material or the like and that is excellent in heat resistance, a molded body obtained from the composition, and a method for producing the same. is there.

The present invention relates to the following [1] to [4].
[1] A cross-linked polylactic acid resin (A) and a carboxylic acid ester (B) represented by the following formula (I) having a solubility parameter value (SP value) by a Fedors method of 10.1 to 11.2. A crosslinked polylactic acid resin composition obtained by blending.
R ¹ O—CO—R ² —CO — [(OR ³ ) _m O—CO—R ² —CO—] _n OR ¹ (I)
Wherein R ¹ is an alkyl group having 1 to 4 carbon atoms, R ² is an alkylene group having 2 to 4 carbon atoms, R ³ is an alkylene group having 2 to 6 carbon atoms, and m is 1 to 6 And n represents a number from 1 to 12, provided that all R ² may be the same or different, and all R ³ may be the same or different.
[2] A resin molded body obtained by molding the crosslinked polylactic acid resin composition according to [1].
[3] The method for producing a resin molded article according to [2], comprising the following steps (1) to (2).
Step (1): a crosslinked polylactic acid resin (A) and a carboxylic acid ester (B) represented by the following formula (I) having a solubility parameter value (SP value) by the Fedors method of 10.1 to 11.2; Step of preparing a crosslinked polylactic acid resin composition by melt-kneading a raw material containing R ¹ O—CO—R ² —CO — [(OR ³ ) _m O—CO—R ² —CO—] _n OR ¹ ( I)
Wherein R ¹ is an alkyl group having 1 to 4 carbon atoms, R ² is an alkylene group having 2 to 4 carbon atoms, R ³ is an alkylene group having 2 to 6 carbon atoms, and m is 1 to 6 And n represents a number from 1 to 12, provided that all R ² may be the same or different, and all R ³ may be the same or different.
Step (2): Step of injection-molding the crosslinked polylactic acid resin composition obtained in Step (1) [4] The solubility parameter value (SP value) by the Fedors method is 10.1 to 11.2. A method for preventing coloration of a crosslinked polylactic acid resin composition, comprising mixing the carboxylic acid ester (B) represented by (I) and a crosslinked polylactic acid resin (A).
R ¹ O—CO—R ² —CO — [(OR ³ ) _m O—CO—R ² —CO—] _n OR ¹ (I)
Wherein R ¹ is an alkyl group having 1 to 4 carbon atoms, R ² is an alkylene group having 2 to 4 carbon atoms, R ³ is an alkylene group having 2 to 6 carbon atoms, and m is 1 to 6 And n represents a number from 1 to 12, provided that all R ² may be the same or different, and all R ³ may be the same or different.

  The crosslinked polylactic acid resin composition of the present invention can suppress color transfer when it comes into contact with printed matter and the like, and has an excellent effect of being excellent in coloring resistance and heat resistance.

  The crosslinked polylactic acid resin composition of the present invention has an SP value calculated using the crosslinked polylactic acid resin (A) and the Fedors method of 10.1 to 11.2, preferably 10.1 to 11.0. Preferably 10.3-11.0 carboxylic acid ester (B) is contained. By using these together, it is possible to suppress the coloring of the molded product obtained from the resin composition, but this suppresses the penetration of the resin in which the colorant in the printed material is dispersed into the molded product. It is thought that it is because. In the present specification, “compounding” means “blending or containing”.

  Hereinafter, each component will be described.

[Crosslinked polylactic acid resin composition]
[Crosslinked polylactic acid resin (A)]
As the crosslinked polylactic acid resin in the present invention, a crosslinked polylactic acid resin obtained by crosslinking a polylactic acid resin with a crosslinking agent is used.

  As the polylactic acid resin, a commercially available polylactic acid resin (for example, trade name: Lacia H-100, H-280, H-400, H-440, etc., manufactured by Mitsui Chemicals, Inc., manufactured by Nature Works, Inc., trade name) : Nature Works PLA / NW3001D, NW4032D, etc.), and polylactic acid resin synthesized from lactic acid or lactide according to a known method. From the viewpoint of improvement in strength and heat resistance, a polylactic acid resin having an optical purity of preferably 90% or more, more preferably 95% or more is preferable. For example, a polylactic acid resin having a relatively high molecular weight and a high optical purity is manufactured by Nature Works. Lactic acid resin (NW4032D etc.) is preferable. The optical purity is a ratio of mol% occupied by L-form or D-form in polylactic acid resin.

  Moreover, as a polylactic acid resin in this invention, other biodegradable resin other than the said polylactic acid resin may be contained suitably in the range which does not impair the effect of this invention. Examples of other biodegradable resins include polyester resins such as polybutylene succinate, polyhydroxyalkanoic acid, and the like. Moreover, the said polylactic acid resin may be contained as a polymer alloy by the blend of said other biodegradable resin and non-biodegradable resins, such as a polypropylene, and polylactic acid. In the present specification, “biodegradable” means a property that can be decomposed into a low molecular weight compound by a microorganism in nature. Specifically, JIS K6953 (ISO 14855) “controlled aerobic composting conditions”. This means biodegradability based on the “Aerobic and Ultimate Biodegradation and Disintegration Test”.

  Examples of the crosslinking agent include compounds having two or more epoxy groups in the molecule such as ethylene glycol diglycidyl ether and polyethylene glycol diglycidyl ether; 2,2′-bis (2-oxazoline), 1,3-phenylenebis Compounds having two or more oxazoline groups in the molecule such as bisoxazoline compounds such as oxazoline and 1,3-benzobisoxazoline; compounds having two or more carbodiimide groups in the molecule (polycarbodiimide-based crosslinking agents), etc. .

  Among these, preferred are polycarbodiimide crosslinking agents from the viewpoint of reactivity, and specifically, poly (4,4′-diphenylmethanecarbodiimide), poly (p-phenylenecarbodiimide), poly (m- Aromatic polycarbodiimides such as phenylenecarbodiimide), poly (diisopropylphenylcarbodiimide), poly (triisopropylphenylcarbodiimide); alicyclic polycarbodiimides such as poly (dicyclohexylmethanecarbodiimide); aliphatic polycarbodiimides, and polylactic acid resins Aromatic polycarbodiimides and alicyclic polycarbodiimides are preferable from the viewpoint of increasing the degree of cross-linking with and at least selected from poly (dicyclohexylmethanecarbodiimide) and poly (diisopropylphenylcarbodiimide). More preferably one, from the viewpoint of coloring resistance of the resulting molded article, poly (dicyclohexylmethanecarbodiimide) are preferred. These polycarbodiimide crosslinking agents can be used alone or in combination of two or more.

  The blending amount of the polycarbodiimide crosslinking agent is preferably 0.1 to 5 parts by weight, preferably 0.25 to 2 parts by weight with respect to 100 parts by weight of the polylactic acid resin, from the viewpoint of effectively crosslinking with the polylactic acid resin. Parts are more preferred, and 0.25 to 1.5 parts by weight are even more preferred. In the present specification, the “blending amount” means “blending amount or content”.

  Cross-linking of the polylactic acid resin and the polycarbodiimide-based cross-linking agent can be performed by melt kneading. As a melt kneader for performing melt kneading, a single or biaxial continuous kneader, a batch kneader using a roll mill, an open roll kneader, or the like can be used. Machine is preferred. Examples of such a kneader include a KTK type twin screw extruder manufactured by Kobe Steel, a TEM type extruder manufactured by Toshiba Machine Co., a twin screw extruder manufactured by Kay Sea Kay, a Kneader manufactured by Buss, and Ikekai Tekko. A PCM type twin-screw extruder manufactured by Tosho Co., Ltd. is preferably used.

  The crosslinking reaction (melt kneading) of the polylactic acid resin and the polycarbodiimide-based crosslinking agent is preferably 180 to 230 ° C, more preferably 190 to 220 ° C, and further preferably 195 to 220 ° C. When a melt kneader is used, it means the set temperature of the kneader when melt kneading. Moreover, before melt-kneading, the polylactic acid resin and the polycarbodiimide-based crosslinking agent can be mixed mechanically and uniformly. The method of mechanically uniformly mixing the polylactic acid resin and the polycarbodiimide-based crosslinking agent can be performed under normal conditions using a mixer having a normal stirring blade, and there is no particular limitation on the means.

  The crosslinking reaction is preferably about 10 seconds to 5 minutes, more preferably about 20 seconds to 3 minutes, although it depends on the reaction scale.

  The completion of the crosslinking reaction can be confirmed by measuring the carboxyl group end concentration. The carboxyl group terminal concentration of the crosslinked polylactic acid resin is preferably 20 mmol / kg or less, more preferably 15 mmol / kg or less, still more preferably 12 mmol / kg or less, and still more preferably 10 mmol / kg or less. In the present specification, the carboxyl group terminal concentration can be measured by the following method.

<Measurement method of carboxyl group terminal concentration>
It is obtained by dissolving 3 g of a crosslinked polylactic acid resin in 100 mL of chloroform, adding 50 mL of benzyl alcohol and a small amount of phenolphthalein ethanol solution thereto, and titrating with 0.05 N potassium hydroxide ethanol solution. Here, chloroform is used as a solvent for dissolving polylactic acid resin, 0.05N potassium hydroxide ethanol solution is used as a titration solvent, benzyl alcohol is used as a compatibilizing agent, and phenolphthalein ethanol solution is used as an indicator.

  In addition, in this invention, the polylactic acid resin which is not bridge | crosslinked other than the said crosslinked polylactic acid resin can be mix | blended in the range which does not impair the effect of this invention. The amount of the crosslinked polylactic acid resin is preferably 20 to 100% by weight, more preferably 50 to 100% by weight in the total resin of the crosslinked polylactic acid resin and the non-crosslinked polylactic acid resin, from the viewpoint of coloring resistance. -100% by weight is more preferred, and 90-100% by weight is even more preferred.

[Carboxylic acid ester (B)]
In the present invention, from the viewpoint of coloring resistance and heat resistance, the solubility parameter value (SP value) by the Fedors method is 10.1 to 11.2, preferably 10.1 to 11.0, and more preferably 10.3 to 1. A carboxylic acid ester represented by the following formula (I) which is 11.0 is used.
R ¹ O—CO—R ² —CO — [(OR ³ ) _m O—CO—R ² —CO—] _n OR ¹ (I)
Wherein R ¹ is an alkyl group having 1 to 4 carbon atoms, R ² is an alkylene group having 2 to 4 carbon atoms, R ³ is an alkylene group having 2 to 6 carbon atoms, and m is 1 to 6 And n represents a number from 1 to 12, provided that all R ² may be the same or different, and all R ³ may be the same or different.

In the present specification, the “solubility parameter value (SP value)” is the Fedors method [Robert F. Fedors, Polymer Engineering and Science, 14, 147-154 (1974)], which is a value δ determined based on the following equation.
Fedors equation: δ = (ΣΔei / ΣΔvi) ^1/2
[Unit: (cal / cm ³ ) ^1/2 ]
[Where Δei: evaporation energy of atoms and atomic groups (cal / mol), Δvi: molar volume (cm ³ / mol)]
In the present invention, the SP value of the carboxylic acid ester represented by the formula (I) can be adjusted by the number of carbons of R ¹ , R ² and R ^{3 and} the number of m and n.

R ¹ in formula (I) represents an alkyl group having 1 to 4 carbon atoms, and two of them exist in one molecule and exist at both ends of the molecule. R ¹ may be linear or branched as long as it has 1 to 4 carbon atoms. The number of carbon atoms of the alkyl group is preferably 1 to 4 and more preferably 1 to 2 from the viewpoint of developing coloring resistance and a plasticizing effect. Specific examples include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, a tert-butyl group, and an iso-butyl group. From the viewpoint of improving the compatibility of these compounds and exhibiting a plasticizing effect, a methyl group and an ethyl group are preferable, and a methyl group is more preferable.

R ² in formula (I) represents an alkylene group having 2 to 4 carbon atoms, and a linear alkylene group is a preferred example. Specific examples include an ethylene group, a 1,3-propylene group, and a 1,4-butylene group, and among them, a viewpoint of improving the color resistance and compatibility with the crosslinked polylactic acid resin and exhibiting a plasticizing effect. Therefore, an ethylene group, a 1,3-propylene group, and a 1,4-butylene group are preferable, and an ethylene group is more preferable. However, all R ² may be the same or different.

R ³ in formula (I) represents an alkylene group having 2 to 6 carbon atoms, and is present in the repeating unit as an oxyalkylene group. R ³ may be linear or branched as long as it has 2 to 6 carbon atoms. The number of carbon atoms of the alkylene group is preferably 2 to 6 and more preferably 2 to 3 from the viewpoint of improving the color resistance and compatibility with the cross-linked polylactic acid resin and exhibiting a plasticizing effect. Specifically, ethylene group, 1,2-propylene group, 1,3-propylene group, 1,2-butylene group, 1,3-butylene group, 1,4-butylene group, 2-methyl-1,3 -Propylene group, 1,2-pentylene group, 1,4-pentylene group, 1,5-pentylene group, 2,2-dimethyl-1,3-propylene group, 1,2-hexylene group, 1,5-hexylene Group, 1,6-hexylene group, 2,5-hexylene group, 3-methyl-1,5-pentylene group, among which ethylene group, 1,2-propylene group, 1,3-propylene group are preferable. However, all R ³ may be the same or different.

  m shows the average repeating number of an oxyalkylene group, and is 1-6 from a heat resistant viewpoint, the number of 1-4 is preferable and the number of 1-3 is more preferable.

  n represents the average number of repeating units (average degree of polymerization), and is a number from 1 to 12. From the viewpoint of improving the color resistance and compatibility with the cross-linked polylactic acid resin and improving the plasticizing effect and plasticizing efficiency, the number of 1 to 6 is preferable, the number of 1 to 5 is more preferable, and the number of 1 to 4 Is more preferable. The average degree of polymerization may be determined by analysis such as NMR, but can be calculated according to the method described in Examples below.

Specific examples of the compound represented by formula (I) include: R ¹ is all methyl group, R ² is ethylene group or 1,4-butylene group, R ³ is ethylene group or 1,3-propylene group , M is a number from 1 to 4, and n is a number from 1 to 6, R ¹ is all methyl group, R ² is ethylene group or 1,4-butylene group, R ³ is ethylene group or 1, A compound which is a 3-propylene group and m is a number of 1 to 3 and n is a number of 1 to 5 is more preferable.

The compound represented by the formula (I) is not particularly limited as long as it has the above structure, but those obtained using the following raw materials (1) to (3) are preferable. Note that (1) and (2) or (2) and (3) may be ester compounds. (2) may be an acid anhydride or an acid halide.
(1) Monohydric alcohol having an alkyl group having 1 to 4 carbon atoms
(2) Dicarboxylic acid having an alkylene group having 2 to 4 carbon atoms
(3) Dihydric alcohol having an alkylene group having 2 to 6 carbon atoms

(1) A monohydric alcohol having an alkyl group having 1 to 4 carbon atoms The monohydric alcohol having an alkyl group having 1 to 4 carbon atoms is an alcohol containing R ¹ , specifically, methanol, Examples include ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, and 1,1-dimethyl-1-ethanol. Among these, methanol, ethanol, 1-propanol, and 1-butanol are used from the viewpoint of improving the resistance to coloring and improving the compatibility with the crosslinked polylactic acid resin and exhibiting a plasticizing effect, as well as increasing the efficiency of the transesterification reaction. Preferably, methanol and ethanol are more preferable, and methanol is more preferable.

(2) Dicarboxylic acid having an alkylene group having 2 to 4 carbon atoms The dicarboxylic acid having an alkylene group having 2 to 4 carbon atoms is a dicarboxylic acid containing R ² , specifically, succinic acid, Examples include glutaric acid, adipic acid, and derivatives thereof (for example, succinic anhydride, glutaric anhydride, dimethyl succinate, dibutyl succinate, dimethyl glutarate, dimethyl adipate). Among them, succinic acid, adipic acid and derivatives thereof (for example, succinic anhydride, dimethyl succinate, succinic acid are used from the viewpoint of improving the color resistance and compatibility with the cross-linked polylactic acid resin and exhibiting a plasticizing effect. Dibutyl and dimethyl adipate) are preferable, and succinic acid and derivatives thereof (for example, succinic anhydride, dimethyl succinate, dibutyl succinate) are more preferable.

(3) Dihydric alcohol having an alkylene group having 2 to 6 carbon atoms The dihydric alcohol having an alkylene group having 2 to 6 carbon atoms is a dihydric alcohol containing R ³ , specifically, Ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, 1,2-pentanediol, 1,4-pentanediol, 1,5 -Pentanediol, 2,2-dimethyl-1,3-propanediol, 2,5-hexanediol, 1,6-hexane Ol, 2,5-hexanediol, and 3-methyl-1,5-pentanediol. Among them, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, tetraethylene glycol are used from the viewpoint of improving the color resistance and compatibility with the crosslinked polylactic acid resin and exhibiting a plasticizing effect. 1,4-butanediol is preferred, diethylene glycol, triethylene glycol, 1,2-propanediol and 1,3-propanediol are more preferred, and diethylene glycol, triethylene glycol and 1,3-propanediol are more preferred.

Therefore, as said (1)-(3),
(1) The monohydric alcohol is at least one selected from the group consisting of methanol, ethanol, 1-propanol, and 1-butanol. (2) The dicarboxylic acid is succinic acid, adipic acid, glutaric acid, and derivatives thereof. (3) the dihydric alcohol is diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, tetraethylene glycol, and 1,4-butanediol. It is preferably at least one selected from the group consisting of
(1) The monohydric alcohol is methanol, (2) the dicarboxylic acid is at least one selected from the group consisting of succinic acid and derivatives thereof, (3) the dihydric alcohol is diethylene glycol, triethylene glycol, and 1, More preferably, it is at least one selected from the group consisting of 3-propanediol.

Although there is no limitation in particular as a method of obtaining an ester compound using said (1)-(3), For example, the method of the following aspects 1 and 2 is mentioned.
Aspect 1: (2) Step of synthesizing dicarboxylic acid ester by performing esterification reaction of (2) dicarboxylic acid with (1) monohydric alcohol (Step 1), and (3) esterifying the obtained dicarboxylic acid ester and (3) dihydric alcohol A method comprising a step of reacting (step 2): A method comprising a step of collectively reacting (1) a monohydric alcohol, (2) a dicarboxylic acid, and (3) a dihydric alcohol

  Among these, the method of Embodiment 1 is preferable from the viewpoint of adjusting the average degree of polymerization.

  The method of aspect 1 is demonstrated below.

  Aspect 1 is a method in which a dicarboxylic acid ester, which is a reaction product of a dicarboxylic acid and a monohydric alcohol, is transesterified with a dihydric alcohol. In this specification, the method of aspect 1 is also referred to as a transesterification reaction.

Specifically, first, in step 1 of embodiment 1, (2) a dicarboxylic acid and (1) a monohydric alcohol are esterified to synthesize a dicarboxylic acid ester. Examples of the esterification method include (2) a dehydration esterification method in which (1) a monohydric alcohol is added to a mixture of a dicarboxylic acid and a catalyst and stirred, and water and monohydric alcohol produced are removed from the system. It is done. In particular,
1) A method in which a monohydric alcohol vapor is blown into a dicarboxylic acid to carry out an esterification reaction, and the generated water and unreacted monohydric alcohol are both removed.
2) A method of performing an esterification reaction using excess monohydric alcohol and removing the produced water and monohydric alcohol azeotropically,
3) A method of removing the water and alcohol by adding an esterification reaction and adding water or a solvent (for example, toluene) that azeotropes with water, monohydric alcohol, and the like.

  Examples of the catalyst include inorganic acids such as sulfuric acid, phosphoric acid, methanesulfonic acid, and paratoluenesulfonic acid, and organic acids. Among these, paratoluenesulfonic acid is preferable. 0.05-10 mol is preferable with respect to 100 mol of dicarboxylic acids, and, as for the usage-amount of a catalyst, 0.10-3 mol is more preferable.

  The molar ratio of the monohydric alcohol to the dicarboxylic acid (monohydric alcohol / dicarboxylic acid) is preferably 2/1 to 20/1, more preferably 3/1 to 12/1, from the viewpoint of improving the reaction rate and economy. . In this case, the “reaction rate” means the rate at which the raw materials subjected to the reaction have reacted with respect to the dicarboxylic acid.

  The reaction temperature depends on the type of monohydric alcohol used, but is preferably 50 to 200 ° C, more preferably 80 to 140 ° C, from the viewpoint of improving the reaction rate and suppressing side reactions. The reaction time is preferably 0.5 to 15 hours, more preferably 1.0 to 5 hours. The reaction may be performed under reduced pressure, and the reaction pressure is preferably 2.7 to 101.3 kPa, more preferably 6.7 to 101.3 kPa.

  The resulting dicarboxylic acid ester has an alkyl esterification rate with respect to two molecular ends of preferably 90% or more, more preferably 95% or more, and still more preferably 98% or more. In the present specification, the alkyl esterification rate can be calculated according to the method described in the examples described later.

  The dicarboxylic acid ester thus obtained is subjected to step 2. In the present invention, as the dicarboxylic acid ester, the reaction product obtained as described above may be used, but a commercially available product may be used, and the commercially available product may be subjected to Step 2. Suitable commercially available products include dimethyl succinate (manufactured by Wako Pure Chemical Industries, Ltd.) and dimethyl adipate (manufactured by Wako Pure Chemical Industries, Ltd.).

  In step 2 of embodiment 1, a transesterification reaction of dicarboxylic acid ester with (3) dihydric alcohol is performed.

  Specifically, for example, (3) a dihydric alcohol is continuously added to a mixture of a dicarboxylic acid ester and a catalyst, and the resulting monohydric alcohol is removed from the system, or (3) a divalent Examples include a transesterification reaction in which a dicarboxylic acid ester is continuously added to a mixture of an alcohol and a catalyst, and the resulting monohydric alcohol is removed from the system. In any case, the reaction can proceed by shifting the equilibrium by distilling off the produced monohydric alcohol. Further, the catalyst may be added stepwise. For example, the dihydric alcohol is added to the dicarboxylic acid ester, or the dihydric alcohol is added when the dicarboxylic acid ester is added to the dihydric alcohol. It can be further added at the stage of removal from the system. In addition, the dicarboxylic acid ester used for transesterification can use the reaction mixture obtained by the above-mentioned esterification reaction, or a commercial item as it is, and can also use it after distilling and isolating.

  Examples of the catalyst include inorganic acids such as sulfuric acid, phosphoric acid, methanesulfonic acid, and paratoluenesulfonic acid, and organic acids, organic metal compounds such as tetraisopropoxy titanium and tetrabutoxy titanium, and alkalis such as sodium methoxide. An alkoxide etc. are mentioned. Of these, p-toluenesulfonic acid, tetraisopropoxy titanium, tetrabutoxy titanium, and sodium methoxide are preferable. For example, in the case of paratoluenesulfonic acid and sodium methoxide, the catalyst is used in an amount of preferably 0.05 to 10 mol, more preferably 0.10 to 5 mol, and tetraisopropoxy titanium for 100 mol of dicarboxylic acid ester. In tetrabutoxy titanium, 0.0001 to 0.1 mol is preferable, and 0.0005 to 0.05 mol is more preferable. In addition, the usage-amount of a catalyst here means the total usage-amount of the catalyst used at the process 2. FIG.

  From the viewpoint of controlling the molecular weight of the ester compound in the present invention, the molar ratio of the dicarboxylic acid ester to the dihydric alcohol (dicarboxylic acid ester / dihydric alcohol) is preferably 1.1 / 1 to 15/1, and 1.2 / 1 to 4/1 is more preferable, and 1.3 / 1 to 4/1 is more preferable.

  The reaction temperature is preferably 50 to 250 ° C., more preferably 60 to 150 ° C., from the viewpoint of improving the reaction rate and suppressing side reactions. In this case, the “reaction rate” means the rate at which the raw materials subjected to the reaction have reacted with respect to the dihydric alcohol. The reaction time is preferably 0.1 to 10 hours, and more preferably 1 to 10 hours. The reaction may be performed under reduced pressure, and the reaction pressure is preferably 0.7 to 101.3 kPa, more preferably 2.0 to 101.3 kPa.

  In addition, you may distill away the unreacted raw material and a by-product from the obtained reaction material according to a well-known method.

  Thus, a compound represented by the formula (I) is obtained.

  The compound represented by the formula (I) preferably has an acid value of 1.50 mgKOH / g or less, more preferably 1.00 mgKOH / g or less, and a hydroxyl value of from the viewpoints of coloring resistance and heat resistance. From the viewpoint of color resistance and heat resistance, it is preferably 10.0 mgKOH / g or less, more preferably 5.0 mgKOH / g or less, still more preferably 4.0 mgKOH / g or less.

  The number average molecular weight of the compound represented by the formula (I) is preferably 300 to 1500, more preferably 300 to 1000, from the viewpoint of color resistance. In the present specification, the number average molecular weight, acid value, and hydroxyl value of the carboxylic acid ester can be measured according to the methods described in Examples described later.

  The saponification value of the compound represented by the formula (I) is preferably from 500 to 800 mgKOH / g, more preferably from 550 to 750 mgKOH / g, from the viewpoint of coloring resistance and heat resistance. In addition, in this specification, the saponification value of a plasticizer can be measured according to the method as described in the below-mentioned Example.

  From the viewpoint of color resistance and heat resistance, the compound represented by the formula (I) preferably has an alkyl esterification rate (terminal alkyl esterification rate) with respect to two molecular ends of 95% or more, more preferably 98. % Or more. In the present specification, the terminal alkyl esterification rate of the plasticizer can be calculated according to the method described in Examples described later.

  The ether group value of the compound represented by the formula (I) is preferably 0 to 8 mmol / g, more preferably 0 to 6 mmol / g, from the viewpoint of coloring resistance and heat resistance. In the present specification, the ether group value of the plasticizer can be calculated according to the method described in Examples described later.

  If the compound represented by the formula (I) has an acid group (for example, carboxyl group) or hydroxyl group within the above range, it reacts with the crosslinked polylactic acid resin to cause the polylactic acid resin to decompose and volatilize. It is considered that the heat resistance can be improved by suppressing the generation of the volatile organic compound (VOC).

  The compounding amount of the compound represented by formula (I) in the crosslinked polylactic acid resin composition of the present invention is preferably from the viewpoint of coloring resistance and moldability with respect to 100 parts by weight of the crosslinked polylactic acid resin (A). 1 part by weight or more, more preferably 3 parts by weight or more, further preferably 5 parts by weight or more. From the viewpoint of heat resistance, it is preferably 30 parts by weight or less, more preferably 20 parts by weight or less, still more preferably 15 parts by weight. It is as follows. Moreover, 1-30 weight part is preferable, 3-20 weight part is more preferable, and 5-15 weight part is still more preferable.

  The crosslinked polylactic acid resin composition of the present invention further contains an organic crystal nucleating agent and a hydrolysis inhibitor in addition to the crosslinked polylactic acid resin (A) and the carboxylic acid ester (B) represented by the formula (I). It is preferable to do.

[Organic crystal nucleating agent]
In the present invention, from the viewpoint of improving the crystallization speed of the crosslinked polylactic acid resin and improving the impact resistance, at least one organic crystal nucleating agent selected from the group consisting of the following (a) to (d) is added: Can be used.
(A) From the group consisting of a compound having an isoindolinone skeleton, a compound having a diketopyrrolopyrrole skeleton, a compound having a benzimidazolone skeleton, a compound having an indigo skeleton, a compound having a phthalocyanine skeleton, and a compound having a porphyrin skeleton At least one organic compound selected [referred to as organic crystal nucleating agent (a)]
(B) At least one organic compound selected from the group consisting of carbohydrazides, uracils, and N-substituted ureas (referred to as organic crystal nucleating agent (b))
(C) at least one selected from the group consisting of metal salts of dialkyl aromatic sulfonates, metal salts of phosphoric acid esters, metal salts of phenylphosphonic acids, metal salts of rosin acids, aromatic carboxylic acid amides, and rosin acid amides Species of organic compound [referred to as organic crystal nucleating agent (c)]
(D) At least one organic compound selected from the group consisting of a compound having a hydroxyl group and an amide group in the molecule and a hydroxy fatty acid ester [referred to as organic crystal nucleating agent (d)]

Organic crystal nucleating agent (a)
The organic crystal nucleating agent (a) includes a compound having an isoindolinone skeleton, a compound having a diketopyrrolopyrrole skeleton, a compound having a benzimidazolone skeleton, a compound having an indigo skeleton, a compound having a phthalocyanine skeleton, and a porphyrin skeleton The at least 1 sort (s) of organic compound chosen from the group which consists of a compound which has these is mentioned.

Organic crystal nucleating agent (b)
Examples of the organic crystal nucleating agent (b) include at least one organic compound selected from the group consisting of carbohydrazides, uracils, and N-substituted ureas.

Organic crystal nucleating agent (c)
Examples of the organic crystal nucleating agent (c) include metal salts of aromatic dialkyl sulfonates, metal salts of phosphate esters, metal salts of phenylphosphonic acid, metal salts of rosin acids, aromatic carboxylic acid amides, and rosin acid amides. And at least one organic compound selected from the group consisting of:

Organic crystal nucleating agent (d)
Examples of the organic crystal nucleating agent (d) include at least one organic compound selected from the group consisting of a compound having a hydroxyl group and an amide group in the molecule and a hydroxy fatty acid ester.

  Among these, from the viewpoint of promoting crystallization, the organic crystal nucleating agent (c) and the organic crystal nucleating agent (d) are preferable.

From the above viewpoint, the organic crystal nucleating agent (c) is more preferably a phenylphosphonic acid metal salt having an optionally substituted phenyl group and a phosphonic group (—PO (OH) ₂ ). Specific examples of the acid include unsubstituted phenylphosphonic acid, methylphenylphosphonic acid, ethylphenylphosphonic acid, propylphenylphosphonic acid, butylphenylphosphonic acid, dimethoxycarbonylphenylphosphonic acid, diethoxycarbonylphenylphosphonic acid, and the like. Unsubstituted phenylphosphonic acid is preferred.

  The compound having a hydroxyl group and an amide group in the molecule of the organic crystal nucleating agent (d) is preferably an aliphatic amide having a hydroxyl group. Specific examples thereof include hydroxy fatty acid monoamides such as 12-hydroxystearic acid monoethanolamide, methylenebis. Examples thereof include hydroxy fatty acid bisamides such as 12-hydroxystearic acid amide, ethylene bis 12-hydroxystearic acid amide, and hexamethylene bis 12-hydroxystearic acid amide.

  The blending amount of the organic crystal nucleating agent in the crosslinked polylactic acid resin composition of the present invention is preferably 0.1 to 5 parts by weight, more preferably 0.5 to 3 parts by weight with respect to 100 parts by weight of the crosslinked polylactic acid resin. 0.7-3 parts by weight is more preferred, and 0.7-2 parts by weight is even more preferred. In addition, in this specification, the compounding quantity of an organic crystal nucleating agent means the total compounding quantity of all the organic crystal nucleating agents mix | blended with a composition.

[Hydrolysis inhibitor]
In the crosslinked polylactic acid resin composition of the present invention, a carbodiimide compound is preferably used as a hydrolysis inhibitor from the viewpoint of moldability.

  Examples of the carbodiimide compound include a monocarbodiimide compound and a polycarbodiimide compound.

  As monocarbodiimide compounds, diphenylcarbodiimide, di-2,6-dimethylphenylcarbodiimide, di-2,6-diethylphenylcarbodiimide, di-2,6-diisopropylphenylcarbodiimide, di-2,6-ditert-butylphenyl Carbodiimide, di-o-tolylcarbodiimide, di-p-tolylcarbodiimide, di-2,4,6-trimethylphenylcarbodiimide, di-2,4,6-triisopropylphenylcarbodiimide, di-2,4,6-tri Aromatic monocarbodiimide compounds such as isobutylphenylcarbodiimide; Alicyclic monocarbodiimide compounds such as di-cyclohexylcarbodiimide; Aliphatic monocarbodiimides such as di-isopropylcarbodiimide and di-octadecylcarbodiimide Thing, and the like.

  Examples of the polycarbodiimide compound include poly (4,4′-diphenylmethanecarbodiimide), poly (p-phenylenecarbodiimide), poly (m-phenylenecarbodiimide), poly (diisopropylphenylenecarbodiimide), and poly (triisopropylphenylenecarbodiimide). An aliphatic polycarbodiimide compound; an alicyclic polycarbodiimide compound such as poly (4,4′-dicyclohexylmethanecarbodiimide); and an aliphatic polycarbodiimide compound.

  Among these, a polycarbodiimide compound is preferable from the viewpoint of impact resistance. These carbodiimide compounds can be used alone or in combination of two or more.

  The blending amount of the carbodiimide compound in the crosslinked polylactic acid resin composition of the present invention is preferably 0.1 to 10 parts by weight, preferably 0.2 to 5 parts by weight with respect to 100 parts by weight of the crosslinked polylactic acid resin, from the viewpoint of moldability. Is more preferable, and 0.3-3 weight part is further more preferable. In addition, in this specification, the compounding quantity of a carbodiimide compound means the total compounding quantity of all the carbodiimide compounds mix | blended with a composition except what was used for manufacture of crosslinked polylactic acid resin.

  The cross-linked polylactic acid resin composition of the present invention includes, as components other than the above, other plasticizers other than the carboxylic acid ester represented by the formula (I), inorganic crystal nucleating agents, fillers (inorganic fillers, organic Fillers), flame retardants, antioxidants, ultraviolet absorbers, antistatic agents, antifogging agents, light stabilizers, pigments, antifungal agents, antibacterial agents, foaming agents, etc., within a range that does not impair the effects of the present invention. Can be blended. Similarly, other polymer materials and other resin compositions can be added within a range that does not impair the effects of the present invention.

  Examples of flame retardants include halogen compounds containing bromine or chlorine such as tetrabromobisphenol-A-epoxy oligomers, tetrabromobisphenol-A-carbonate oligomers, and brominated epoxy resins; inorganic compounds such as antimony trioxide and zinc borate Flame retardants; Silicone flame retardants such as silicone resins and silicone oils; inorganic hydrates such as aluminum hydroxide and magnesium hydroxide (from the viewpoint of physical properties, surface treatment with a silane coupling agent, especially isocyanate silane Preferred); phosphorus-based flame retardants such as triaryl isopropylates, condensed phosphates, melamine polyphosphates, piperazine polyphosphates and phosphazene compounds; nitrogen-containing compounds such as melamine cyanurate. Among these, the solubility parameter value (SP value) by the Fedors method is preferably 10.1 to 11.2, more preferably 10.2 to 11.2, and still more preferably 10.3 to 11.2. It is preferable to add a phosphorus-based flame retardant from the viewpoints of flame retardancy and coloring resistance.

  Preferable phosphorus flame retardants include, specifically, triphenyl phosphate (SP value 10.7), tricresyl phosphate (SP value 10.5), trixylenyl phosphate (SP value 10.3), cresyl Diphenyl phosphate (SP value 10.6), cresyl-di-2,6-xylenyl phosphate (SP value 10.3), triaryl phosphate isopropylate (for example, average 1.2 isopropyl groups per molecule) In this case, phosphoric acid triaryl ester such as SP value 10.3), 1,3-phenylene bis (diphenyl phosphate) (SP value 11.1), bisphenol A bis (diphenyl phosphate) (SP value 10.9), 1 , 3-phenylene bis (di-2,6 xylenyl phosphate) (SP value 10.6) And the like. Moreover, a condensed phosphate ester is more preferable from the viewpoint of excellent heat resistance (weight reduction rate).

  The blending amount of the phosphorus-based flame retardant having a solubility parameter value (SP value) according to the Fedors method in the crosslinked polylactic acid resin composition of 10.1 to 11.2 improves flame retardancy, coloring resistance and heat resistance. From the viewpoint of making it, from the viewpoint of flame retardancy and color resistance, it is preferably 2 parts by weight or more, more preferably 3 parts by weight or more, and further preferably 4 parts by weight or more with respect to 100 parts by weight of the crosslinked polylactic acid resin. From the viewpoint of heat resistance, it is preferably 40 parts by weight or less, more preferably 30 parts by weight or less, and still more preferably 20 parts by weight or less. The SP value calculated using the Fedors method in the crosslinked polylactic acid resin composition is 10.1 to 11.2 by blending a phosphorus-based flame retardant having the SP value of 10.1 to 11.2. The amount of the carboxylic acid ester (B) can be reduced. For example, the blending amount of the carboxylic acid ester (B) when blending the phosphorus-based flame retardant is preferably 0.5 parts by weight from the viewpoint of coloring resistance and moldability with respect to 100 parts by weight of the crosslinked polylactic acid resin. From the viewpoint of heat resistance, it is preferably 28 parts by weight or less, more preferably 18 parts by weight or less, and further preferably 13 parts by weight or less. .

  Phosphorus flame retardant having a solubility parameter value (SP value) of 10.1 to 11.2 by the Fedors method and a carboxylic acid ester having an SP value of 10.1 to 11.2 calculated using the Fedors method (B ) And the blending ratio (weight ratio) (phosphorous flame retardant / carboxylic acid ester (B)) is preferably 0.1 or more, more preferably 0.3 or more, and still more preferably, from the viewpoint of flame retardancy. Is 0.5 or more, and from the viewpoint of moldability, it is preferably 7 or less, more preferably 5 or less, and even more preferably 3 or less.

  The crosslinked polylactic acid resin composition of the present invention can be prepared without particular limitation as long as it contains the crosslinked polylactic acid resin and the carboxylic acid ester represented by the formula (I). The raw material containing the carboxylic acid ester represented by the formula (I) and the flame retardant and various additives, if necessary, is used for a closed kneader, a single or twin screw extruder, an open roll kneader, etc. It can be prepared by melt kneading using a known kneader. The raw materials can be subjected to melt kneading after being uniformly mixed in advance using a Henschel mixer, a super mixer, or the like. In preparing the crosslinked polylactic acid resin composition, in order to promote the plasticity of the crosslinked polylactic acid resin, it may be melt-mixed in the presence of a supercritical gas. Moreover, as the crosslinked polylactic acid resin, those prepared in advance or commercially available products may be used. Preferably, the crosslinked polylactic acid resin obtained by kneading the polylactic acid resin and polycarbodiimide at 180 to 230 ° C. according to the above method. Preparing the lactic acid resin (A), then adding and mixing the carboxylic acid ester represented by the formula (I) and, if necessary, the raw materials for the crosslinked polylactic acid resin composition such as the flame retardant, and then kneading the mixture. Can do.

  The melt kneading temperature is preferably 170 to 240 ° C, more preferably 180 to 220 ° C, from the viewpoint of improving the moldability of the crosslinked polylactic acid resin composition. The melt-kneading time cannot be generally determined depending on the melt-kneading temperature and the type of the kneader, but is preferably 30 to 120 seconds. The carboxylic acid ester represented by the formula (I) suppresses the generation of volatile organic compounds even in melt kneading at the above temperature. In addition, after melt-kneading, the melt-kneaded product may be dried or cooled according to a known method.

  The cross-linked polylactic acid resin composition of the present invention thus obtained has good processability and excellent coloration resistance and heat resistance, so that it can be used under high temperature conditions. -It can use suitably for household appliance use. Therefore, this invention also provides the resin molding which shape | molded the crosslinked polylactic acid resin composition of this invention.

  The resin molded body of the present invention is not particularly limited as long as the crosslinked polylactic acid resin composition of the present invention is molded, and a known method can be used as the molding method. For example, the resin molding of the present invention is performed by injection-molding the crosslinked polylactic acid resin composition of the present invention using an injection molding machine in which the cylinder temperature is preferably set to 180 to 220 ° C., more preferably 180 to 210 ° C. The body is obtained.

  The present invention also provides a method for producing the resin molded body of the present invention.

  As a manufacturing method, what is necessary is just a method including the process of melt-kneading and shape | molding the said crosslinked polylactic acid resin and the carboxylic acid ester represented by Formula (I), for example, the following methods are used suitably.

Specifically, the manufacturing method which has the following process (1)-(2) is mentioned.
Step (1): a crosslinked polylactic acid resin (A) and a carboxylic acid ester (B) represented by the following formula (I) having a solubility parameter value (SP value) by the Fedors method of 10.1 to 11.2; Step of preparing a crosslinked polylactic acid resin composition by melt-kneading a raw material containing R ¹ O—CO—R ² —CO — [(OR ³ ) _m O—CO—R ² —CO—] _n OR ¹ ( I)
Wherein R ¹ is an alkyl group having 1 to 4 carbon atoms, R ² is an alkylene group having 2 to 4 carbon atoms, R ³ is an alkylene group having 2 to 6 carbon atoms, and m is 1 to 6 And n represents a number from 1 to 12, provided that all R ² may be the same or different, and all R ³ may be the same or different.
Step (2): Step of injection molding the crosslinked polylactic acid resin composition obtained in Step (1)

  Step (1) includes a crosslinked polylactic acid resin, a carboxylic acid ester (B) represented by the above formula (I) having a solubility parameter of 10.1 to 11.2 according to the Fedors method, and, if necessary, Known materials such as hermetic kneaders, single or twin screw extruders, open roll kneaders, etc. containing raw materials containing or blended with organic crystal nucleating agents, hydrolysis inhibitors, and other additives (for example, flame retardants) The cross-linked polylactic acid resin composition is prepared by melt-kneading at 170 to 240 ° C., more preferably 180 to 220 ° C., using a kneading machine. As described above, the cross-linked polylactic acid resin is preferably one in which a cross-linking reaction is performed in advance with a polycarbodiimide-based cross-linking agent and a polylactic acid resin. The raw materials can be subjected to melt kneading after being uniformly mixed in advance using a Henschel mixer, a super mixer, or the like. In preparing a melt of the crosslinked polylactic acid resin composition, in order to promote the plasticity of the crosslinked polylactic acid resin, a supercritical gas may be present and melt-mixed.

  In step (2), the crosslinked polylactic acid resin composition obtained in step (1) is injection molded. As injection molding, it can shape | mold by injecting in a metal mold | die using a well-known injection molding machine. For example, those having a cylinder and a screw inserted through the cylinder as main components [J110AD-180H (manufactured by Nippon Steel), etc.] can be mentioned. In addition, although the raw material of the crosslinked polylactic acid resin composition of the present invention may be supplied to a cylinder and melt-kneaded as it is, it is preferable to fill an injection molding machine with a melt-kneaded material in advance.

  The set temperature of the cylinder is preferably 180 to 220 ° C, more preferably 180 to 210 ° C. When a melt kneader is used, it means the set temperature of the cylinder of the kneader when melt kneading. The cylinder is equipped with a heater, and the temperature is adjusted accordingly. The number of heaters differs depending on the model and is not determined unconditionally, but the heater adjusted to the set temperature is a temperature existing on the melt-kneaded product discharge port side (nozzle tip side).

  The mold temperature is preferably 70 to 120 ° C., more preferably 75 to 115 ° C., and still more preferably 80 to 110 ° C. from the viewpoint of improving the crystallization speed and workability of the crosslinked polylactic acid resin composition.

  The holding time in the mold cannot be generally determined by the temperature of the mold, but is preferably 10 to 120 seconds, and more preferably 30 to 90 seconds.

  Furthermore, this invention provides the coloring prevention method of the crosslinked polylactic acid resin composition of this invention.

Specifically, a solubility parameter value (SP value) according to the Fedors method is 10.1 to 11.2, a carboxylic acid ester (B) represented by the following formula (I), and a crosslinked polylactic acid resin (A): If it mixes, there will be no limitation in particular. In addition, as the crosslinked polylactic acid resin (A) and the carboxylic acid ester (B), those blended in the aforementioned crosslinked polylactic acid resin composition of the present invention can be used in the same amount within the same range. it can.
R ¹ O—CO—R ² —CO — [(OR ³ ) _m O—CO—R ² —CO—] _n OR ¹ (I)
Wherein R ¹ is an alkyl group having 1 to 4 carbon atoms, R ² is an alkylene group having 2 to 4 carbon atoms, R ³ is an alkylene group having 2 to 6 carbon atoms, and m is 1 to 6 And n represents a number from 1 to 12, provided that all R ² may be the same or different, and all R ³ may be the same or different.

  The crosslinked polylactic acid resin composition of the present invention can be suitably used for home appliance parts such as a casing of an information home appliance. This is because color transfer from a printed matter such as toner or ink jet to a housing or the like can be suppressed. Compared with the case of containing a dibasic acid ester composed of a monoalkyl ether of polyalkylene glycol and a dibasic acid, the carboxylic acid has a low ether group content as a polar group and has excellent oxidation stability and volatility resistance. Since the ester is contained, smoke generation from the extruder during extrusion molding is also suppressed, workability is improved, and heat resistance of the molded body is improved.

  EXAMPLES Hereinafter, although an Example and a comparative example are 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. “Normal pressure” indicates 101.3 kPa, and “normal temperature” indicates 15 to 25 ° C.

[Acid value, hydroxyl value, and saponification value of carboxylic acid ester]
Acid value: Analysis is performed according to the test method of JIS K 0070, except that toluene / ethanol = 2/1 (volume ratio) is used as a titration solvent.
Hydroxyl value: Analysis is performed according to the test method of JIS K 0070, except that acetic anhydride / pyridine = 1/4 (volume ratio) is used as the acetylating reagent and the addition amount is 3 mL.
Saponification value: Analysis is performed according to the test method of JIS K 0070, except that the temperature of the water bath is 95 ° C. and the heating temperature is 1 hour.

[Molecular weight of carboxylate ester, terminal alkyl esterification rate, and ether group value]
Molecular weight: In this specification, the molecular weight of a carboxylic acid ester means a number average molecular weight, and is calculated from the acid value, hydroxyl value, and saponification value according to the following formula.
Average molecular weight M = (M ₁ + M ₂ −M ₃ × 2) × n + M ₁ − (M ₃ −17.01) × 2 + (M ₃ −17.01) × p + (M ₂ −17.01) × q + 1. 01 × (2-pq)
q = hydroxyl value × M ÷ 56110
2-pq = acid value × M ÷ 56110
Average degree of polymerization n = saponification number × M ÷ (2 × 56110) −1
Terminal alkyl esterification rate: The molecular terminal alkyl esterification rate (terminal alkyl esterification rate) can be calculated from the following formula. The larger the value of the molecular terminal alkyl esterification rate, the free carboxyl group or hydroxyl group There are few, and it shows that the molecular terminal is fully alkylesterified.
Terminal alkyl esterification rate (%) = (p ÷ 2) × 100
However, M ₁ : dicarboxylic acid used as a raw material and monohydric alcohol used as a raw material
Molecular weight of diester M ₂ : Molecular weight of dihydric alcohol used as raw material M ₃ : Molecular weight of monohydric alcohol used as raw material p: Number of terminal alkyl ester groups in one molecule q: Number of terminal hydroxyl groups in one molecule Ether group number : The ether group value which is the number of millimoles (mmol) of the ether group in 1 g of the carboxylic acid ester is calculated from the following formula.
Ether group value (mmol / g) = (m−1) × n × 1000 ÷ M
Where m: average number of repeating oxyalkylene groups (m-1 represents the number of ether groups in one molecule of dihydric alcohol)
In addition, when using multiple types of dicarboxylic acid, monohydric alcohol, and dihydric alcohol, molecular weight uses the molecular weight of a number average value.

Production Example 1 of Crosslinked Polylactic Acid Resin
50 parts of polylactic acid resin (a-1) (manufactured by NatureWorks, 4032D carboxyl group terminal concentration 22 mmol / kg) as polylactic acid resin, and poly (dicyclohexylmethanecarbodiimide) (manufactured by Nisshinbo Chemical Co., Ltd., Carbodilite LA-) as a polycarbodiimide-based crosslinking agent 1) 0.5 part was melt-kneaded with a twin-screw extruder (Ikegai Iron Works, PCM-45) at a set temperature of the cylinder of 200 ° C., a rotation speed of 100 rpm, and a supply rate of 30 kg / h, The strand cut was performed to obtain pellets (diameter: 3 to 4 mm) of a crosslinked polylactic acid resin (crosslinked polylactic acid resin) in which the polylactic acid resin was crosslinked with a polycarbodiimide-based crosslinking agent. The carboxyl group terminal concentration of the obtained cross-linked polylactic acid resin was 7 mmol / kg.

Production example 1 of carboxylic acid ester (dimethyl succinate-diethylene glycol, n = 1.6)
In a four-necked flask (with a stirrer, thermometer, dropping funnel, distillation tube, nitrogen blowing tube), 999 g (9.41 mol) of diethylene glycol and 23.6 g of a methanol solution containing 28 wt% sodium methoxide as a catalyst (sodium methoxide 0) .122 mol) was added, and methanol was distilled off while stirring at normal pressure (101.3 kPa) and 120 ° C. for 0.5 hour. Thereafter, 4125 g (28.2 mol) of dimethyl succinate (manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise over 3 hours, and methanol produced by the reaction was distilled off at normal pressure and 120 ° C. Next, the mixture was cooled to 75 ° C., the pressure was gradually reduced from normal pressure to 6.7 kPa over 2 hours to distill off methanol, and the pressure was returned to normal pressure. Further, 28 wt% sodium methoxide-containing methanol was used as a catalyst. 4.4 g of solution (0.023 mol of sodium methoxide) was added, and methanol was distilled at 100 ° C. by gradually lowering the pressure from normal pressure to 2.9 kPa over 2 hours. Then, after cooling to 80 ° C., 41 g of KYOWARD 600S (manufactured by Kyowa Chemical Industry Co., Ltd.) was added and stirred at a pressure of 4.0 kPa and 80 ° C. for 1 hour, followed by filtration under reduced pressure. The filtrate was raised at a pressure of 0.3 kPa and the temperature from 70 ° C. to 190 ° C. over 4 hours, and the remaining dimethyl succinate was distilled off to obtain a room temperature yellow liquid. In addition, the usage-amount of the catalyst was 0.51 mol with respect to 100 mol of dicarboxylic acid ester.

Production example 2 of carboxylic acid ester (dimethyl succinate-diethylene glycol, n = 2.1)
A four-necked flask (with a stirrer, thermometer, dropping funnel, distillation tube, nitrogen blowing tube) was charged with 363 g (3.42 mol) of diethylene glycol and 6.6 g of a methanol solution containing 28 wt% sodium methoxide as a catalyst (sodium methoxide 0). 0.034 mol) was added, and methanol was distilled off while stirring at normal pressure and 120 ° C. for 0.5 hour. Thereafter, 1000 g (6.84 mol) of dimethyl succinate (manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise over 3 hours, and methanol produced by the reaction was distilled off at normal pressure and 120 ° C. Next, the mixture was cooled to 75 ° C., the pressure was gradually reduced from normal pressure to 6.7 kPa over 1.5 hours to distill off methanol, and then the pressure was returned to normal pressure. Further, 28 wt% sodium methoxide was used as a catalyst. A methanol solution containing 5.8 g (sodium methoxide 0.030 mol) was added, and the pressure was gradually reduced from normal pressure to 2.9 kPa over 2 hours at 100 ° C. to distill methanol. Then, after cooling to 80 ° C., 18 g of KYOWARD 600S (manufactured by Kyowa Chemical Industry Co., Ltd.) was added and stirred at a pressure of 4.0 kPa and 80 ° C. for 1 hour, followed by filtration under reduced pressure. The filtrate was pressured at 0.3 kPa and the temperature was raised from 70 ° C. to 190 ° C. over 1 hour to distill off the remaining dimethyl succinate to obtain a room temperature yellow liquid. In addition, the usage-amount of the catalyst was 0.94 mol with respect to 100 mol of dicarboxylic acid ester.

Carboxylic acid ester production example 3 (dimethyl succinate-diethylene glycol, n = 4.3)
In a four-necked flask (with a stirrer, thermometer, dropping funnel, distillation tube, nitrogen blowing tube) 581 g (5.47 mol) of diethylene glycol and 9.1 g of methanol solution containing 28 wt% sodium methoxide as a catalyst (sodium methoxide 0) 0.047 mol), and methanol was distilled off with stirring at normal pressure and 120 ° C. for 0.5 hour. Thereafter, 1200 g (8.21 mol) of dimethyl succinate (manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise over 2 hours, and methanol produced by the reaction was distilled off at normal pressure and 120 ° C. Next, the mixture was cooled to 75 ° C., the pressure was gradually reduced from normal pressure to 6.7 kPa over 1.5 hours to distill off methanol, and then the pressure was returned to normal pressure. Further, 28 wt% sodium methoxide was used as a catalyst. The methanol solution containing 9.8 g (0.051 mol of sodium methoxide) was added, and the pressure was gradually reduced from normal pressure to 2.9 kPa over 2 hours at 100 ° C. to distill methanol. Then, after cooling to 80 ° C., 28 g of KYOWARD 600S (manufactured by Kyowa Chemical Industry Co., Ltd.) was added and stirred at a pressure of 4.0 kPa and 80 ° C. for 1 hour, followed by vacuum filtration. The filtrate was pressured at 0.3 kPa and the temperature was raised from 70 ° C. to 170 ° C. over 2.5 hours to distill off the remaining dimethyl succinate to obtain a room temperature yellow liquid. In addition, the usage-amount of the catalyst was 1.2 mol with respect to 100 mol of dicarboxylic acid ester.

Production example 4 of carboxylic acid ester (dimethyl succinate-triethylene glycol, n = 1.5)
In a four-necked flask (with a stirrer, thermometer, dropping funnel, distillation tube, nitrogen blowing tube) 342 g (2.28 mol) of triethylene glycol and 4.4 g of a methanol solution containing 28 wt% sodium methoxide as a catalyst (sodium methoxy) 0.023 mol), and methanol was distilled off while stirring at normal pressure and 120 ° C. for 0.5 hour. Thereafter, 1000 g (6.84 mol) of dimethyl succinate (manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise over 3 hours, and methanol produced by the reaction was distilled off at normal pressure and 120 ° C. Next, after cooling to 75 ° C., the pressure was gradually lowered from normal pressure to 6.7 kPa over 2 hours to distill off methanol, and then returned to normal pressure, and further containing 28 wt% sodium methoxide as a catalyst. 3.8 g of methanol solution (sodium methoxide 0.020 mol) was added, and the pressure was gradually decreased from normal pressure to 2.9 kPa over 3 hours at 100 ° C. to distill methanol. Then, after cooling to 80 ° C., 12 g of KYOWARD 600S (manufactured by Kyowa Chemical Industry Co., Ltd.) was added and stirred at a pressure of 4.0 kPa and 80 ° C. for 1 hour, followed by vacuum filtration. The filtrate was heated at a pressure of 0.3 kPa and the temperature was raised from 70 ° C. to 165 ° C. over 1 hour to distill off the remaining dimethyl succinate to obtain a room temperature yellow liquid. In addition, the usage-amount of the catalyst was 0.63 mol with respect to 100 mol of dicarboxylic acid ester.

Carboxylic ester production example 5 (dimethyl succinate-1,3-propanediol, n = 1.5)
A 4-necked flask (with a stirrer, thermometer, dropping funnel, distillation tube and nitrogen blowing tube) was charged with 86.8 g (1.14 mol) of 1,3-propanediol and a methanol solution 2 containing 28 wt% sodium methoxide as a catalyst. 0.2 g (0.011 mol of sodium methoxide) was added, and methanol was distilled off with stirring at normal pressure and 120 ° C. for 0.5 hour. Thereafter, 500 g (3.42 mol) of dimethyl succinate (manufactured by Wako Pure Chemical Industries, Ltd.) was dropped over 2 hours, and methanol produced by the reaction was distilled off at normal pressure and 120 ° C. Next, the mixture was cooled to 75 ° C., the pressure was gradually reduced from normal pressure to 6.7 kPa over 2 hours to distill off methanol, and the pressure was returned to normal pressure. Further, 28 wt% sodium methoxide-containing methanol was used as a catalyst. 2.0 g of solution (0.010 mol of sodium methoxide) was added, and methanol was distilled by gradually lowering the pressure from normal pressure to 2.9 kPa over 3 hours at 100 ° C. Then, after cooling to 80 ° C., 6 g of KYOWARD 600S (manufactured by Kyowa Chemical Industry Co., Ltd.) was added and stirred at a pressure of 4.0 kPa and 80 ° C. for 1 hour, followed by vacuum filtration. The filtrate was heated at a pressure of 4.5 kPa and the temperature was raised from 114 ° C. to 194 ° C. over 1 hour to distill off the remaining dimethyl succinate, thereby obtaining a room temperature yellow liquid. In addition, the usage-amount of the catalyst was 0.61 mol with respect to 100 mol of dicarboxylic acid ester.

Carboxylic ester production example 6 (dimethyl succinate-1,3-propanediol, n = 4.4)
In a four-necked flask (with a stirrer, thermometer, dropping funnel, distillation tube, nitrogen blowing tube), 521 g (6.84 mol) of 1,3-propanediol and 5.9 g of a methanol solution containing 28 wt% sodium methoxide as a catalyst (Sodium methoxide 0.031 mol) was added, and methanol was distilled off with stirring at normal pressure and 120 ° C. for 0.5 hour. Thereafter, 1500 g (10.26 mol) of dimethyl succinate (manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise over 1 hour, and methanol produced by the reaction was distilled off at normal pressure and 120 ° C. Next, the mixture was cooled to 60 ° C., 5.6 g of 28 wt% sodium methoxide-containing methanol solution (0.029 mol of sodium methoxide) was added, the temperature was raised to 120 ° C. over 2 hours, and then the pressure was applied over 1 hour. The methanol was gradually distilled off from normal pressure to 3.7 kPa. Then, after cooling to 80 ° C., 18 g of KYOWARD 600S (manufactured by Kyowa Chemical Industry Co., Ltd.) was added and stirred at a pressure of 4.0 kPa and 80 ° C. for 1 hour, followed by filtration under reduced pressure. The filtrate was raised at a pressure of 0.1 kPa and the temperature was raised from 85 ° C. to 194 ° C. over 2.5 hours to distill off the remaining dimethyl succinate to obtain a room temperature yellow liquid. In addition, the usage-amount of the catalyst was 0.58 mol with respect to 100 mol of dicarboxylic acid ester.

Production example 7 of carboxylic acid ester (dimethyl adipate-diethylene glycol, n = 1.5)
In a four-necked flask (with a stirrer, thermometer, dropping funnel, distillation tube, nitrogen blowing tube), 203 g (1.91 mol) of diethylene glycol and 5.5 g of a methanol solution containing 28 wt% sodium methoxide as a catalyst (sodium methoxide 0) 0.029 mol) was added, and methanol was distilled off while stirring at normal pressure and 120 ° C. for 0.5 hour. Thereafter, 1000 g (5.74 mol) of dimethyl adipate (manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise over 2 hours, and methanol produced by the reaction was distilled off at normal pressure and 120 ° C. Next, the mixture was cooled to 75 ° C., the pressure was gradually reduced from normal pressure to 6.7 kPa over 2 hours to distill off methanol, and the pressure was returned to normal pressure. Further, 28 wt% sodium methoxide-containing methanol was used as a catalyst. 3.7 g (sodium methoxide 0.019 mol) was added, and methanol was distilled off at 100 ° C. by gradually lowering the pressure from normal pressure to 2.4 kPa over 2 hours. Thereafter, the mixture was cooled to 80 ° C., 14 g of KYOWARD 600S (manufactured by Kyowa Chemical Industry Co., Ltd.) was added, and the mixture was stirred at a pressure of 4.0 kPa and 80 ° C. for 1 hour, followed by filtration under reduced pressure. The filtrate was raised at a pressure of 0.3 kPa and the temperature was raised from 70 ° C. to 190 ° C. over 1 hour to distill off the remaining dimethyl adipate to obtain a room temperature yellow liquid. In addition, the usage-amount of the catalyst was 0.84 mol with respect to 100 mol of dicarboxylic acid ester.

Production example 8 of carboxylic acid ester (bis (2-ethylhexyl) adipate / neopentyl glycol, n = 1.2)
In a four-necked flask (with a stirrer, thermometer, dropping funnel, distillation tube, nitrogen blowing tube), neopentyl glycol 263.5 g (2.53 mol), bis (2-ethylhexyl) adipate 1500 g (4.05 mol) 2-ethyl ester produced by the reaction while adding 5.6 g of methanol solution containing 28 wt% sodium methoxide (0.029 mol of sodium methoxide) as a catalyst and reacting at a pressure of 3.7 kPa and 120 ° C. for 1.5 hours. Hexanol was distilled off. Next, after cooling to 75 ° C., the pressure is returned to normal pressure. Further, 3.0 g (sodium methoxide 0.016 mol) of 28 wt% sodium methoxide-containing methanol solution is added as a catalyst, and the pressure is 0.4 kPa and the temperature is increased. Was raised from 92 ° C. to 160 ° C. over 1 hour to distill 2-ethylhexanol. Then, after cooling to 80 ° C., 19 g of KYOWARD 600S (manufactured by Kyowa Chemical Industry Co., Ltd.) was added and stirred at a pressure of 4.0 kPa and 80 ° C. for 1 hour, followed by vacuum filtration. The filtrate was raised at a pressure of 0.3 kPa and the temperature was raised from 166 ° C. to 214 ° C. over 2 hours to distill off 504 g of residual bis (2-ethylhexyl) adipate to obtain a room temperature yellow liquid. In addition, the usage-amount of the catalyst was 1.11 mol with respect to 100 mol of dicarboxylic acid ester.

  The acid value, hydroxyl value, and saponification value of the obtained compound were measured, and the number average molecular weight, terminal alkyl esterification rate, average degree of polymerization (n), and ether group value were calculated based on the above formula. Moreover, SP value was computed by the method shown below (it shows about the manufacture example 1 as an example). The results are shown in Tables 1-2.

<SP value calculation example>
Among the compounds represented by the formula (I), the carboxylic acid ester obtained in Production Example 1 is
R ¹ O—CO—R ² —CO — [(OR ³ ) _m O—CO—R ² —CO—] _n OR ¹
R ^{1 is a} methyl group, R ^{2 is an} ethylene group, R ^{3 is an} ethylene group, m is 2, and n is 1.6. That is, it has 2 methyl groups, 11.6 methylene groups, 5.2 ester groups, and 1.6 ether groups.
Therefore, the Fedors equation: δ = (ΣΔei / ΣΔvi) ^1/2
[Unit: (cal / cm ³ ) ^1/2 ]
[Where Δei: evaporation energy of atoms and atomic groups (cal / mol), Δvi: molar volume (cm ³ / mol)]
Calculating based on
Δei of the methyl group is 1125 (cal / mol), Δvi is 33.5 (cal / mol),
Δei of the methylene group is 1180 (cal / mol), Δvi is 16.1 (cal / mol),
Δei of the ester group is 4300 (cal / mol), Δvi is 18.0 (cal / mol),
The Δei of the ether group is 800 (cal / mol), and Δvi is 3.8 (cal / mol).
From these, the calculated SP value is 10.6.

Examples 1 to 13 and Comparative Examples 1 to 5
Preparation of Resin Composition The raw materials for the composition shown in Tables 3 to 5 were melt-kneaded at 190 ° C. using a same-direction meshing twin-screw extruder (TEM-41SS manufactured by Toshiba Machine Co., Ltd.), and strand cutting was performed. A pellet of the resin composition was obtained. In addition, the obtained pellet was dehumidified and dried at 110 ° C. for 2 hours, and the water content was adjusted to 500 ppm or less.

Preparation of resin molding Next, the obtained pellets were injection molded using an injection molding machine (Japan Steel J75E-D) with a cylinder temperature of 200 ° C., and tested at a mold temperature of 80 ° C. and a molding time of 60 seconds. A piece [flat plate (70 mm × 40 mm × 2 mm)] was molded.

In addition, the raw material in Tables 3-5 is as follows. Calculation of the SP value of the flame retardant was performed in the same manner as for the plasticizer.
<Polylactic acid resin>
Cross-linked polylactic acid resin: Cross-linked polylactic acid resin produced in Production Example 1 of cross-linked polylactic acid resin NW4032D: NatureWorks 4032D manufactured by Nature Works
<Plasticizer>
Production Examples 1-8: Carboxylic acid ester ethylphthalylethyl glycolate described in Tables 1-2: # 10 manufactured by Daihachi Chemical Industry Co., Ltd.
DAIFATTY-101: adipic acid-methyldiglycol / benzyl ester, Citroflex 2: Daihachi Chemical Industry Co., Ltd .: Triethyl citrate, manufactured by Morimura Corporation <Organic crystal nucleating agent>
Eco Promote: unsubstituted phenylphosphonic acid zinc salt, Sripax H manufactured by Nissan Chemical Industries, Ltd .: ethylene bis 12-hydroxystearic acid amide, manufactured by Nippon Kasei Co., Ltd. <hydrolysis inhibitor>
Starbaxol P: polycarbodiimide, carbodilite LA-1 manufactured by Rhein Chemie, Ltd .: polycarbodiimide, manufactured by Nisshinbo Chemical Co., Ltd. <Flame Retardant>
TPP: triphenyl phosphate, Daihachi Chemical Industries CDP: cresyl diphenyl phosphate, Daihachi Chemical Industries Leophos 65: triaryl phosphate isopropylate (average 1.2 isopropyl groups per molecule), Ajinomoto Fine Techno-made CR-733S: 1,3 phenylene bis (diphenyl phosphate), Daihachi Chemical Industry PX-200: 1,3 phenylene bis (di 2,6 xylenyl phosphate), Daihachi Chemical Industry

  The characteristics of the obtained molded body were evaluated according to the methods of Test Examples 1 and 2 below. The results are shown in Tables 3-5.

Test Example 1 <Color resistance>
A4 paper (type of paper) printed on the entire surface in black (setting conditions: print quality / standard) using a Canon Satera LBP5400 laser beam printer is sandwiched between the molded products and a 1 kg weight is placed on the 40 ° C / It was left for 24 hours in an environment with a humidity of 65%. “1” when the printed matter adheres to the surface of the molded body and the transfer of printing does not disappear even after wiping with a tissue. “2” when the slight change of adhesion occurs but the transfer of printing disappears when wiped with a tissue. The case where there was no adhesion was designated as “3”.

Test Example 2 <Heat resistance>
About 7.0 to 8.0 mg of the molded body was precisely weighed, using a thermal analyzer EXTRA TG / DTA 7200 manufactured by SII Nanotechnology, Inc., under an air stream (200 mL / min), at a temperature rising rate of 40 ° C./min. The temperature was increased from 40 ° C. to 210 ° C., and the weight reduction rate (%) when held at 210 ° C. for 30 minutes was measured. A smaller weight reduction rate (%) indicates better heat resistance.

  The molded products of the present invention products of Examples 1 to 13 are excellent in coloring resistance and heat resistance. In particular, the injection molded products of Examples 1 to 6 and 9 to 13 using the carboxylic acid ester represented by the formula (I) having an SP value of 10.3 or more are more excellent in color resistance.

  Moreover, since the molded articles of the present invention products of Examples 9 to 13 use a phosphorus-based flame retardant having a specific SP value, the blending amount of the carboxylic acid ester represented by the formula (I) is reduced. Can do.

  The crosslinked polylactic acid resin composition of the present invention can suppress color transfer from a printed matter such as a copy or an ink jet, a colored resin or rubber to a casing, etc., and has excellent heat resistance when molded. For this reason, it can be suitably used for home appliance parts such as a casing of an information home appliance.

Claims (9)

A cross-linked polylactic acid resin (A) and a carboxylic acid ester (B) represented by the following formula (I) having a solubility parameter value (SP value) by the Fedors method of 10.1 to 11.2 are blended. A crosslinked polylactic acid resin composition.
R ¹ O—CO—R ² —CO — [(OR ³ ) _m O—CO—R ² —CO—] _n OR ¹ (I)
Wherein R ¹ is an alkyl group having 1 to 4 carbon atoms, R ² is an alkylene group having 2 to 4 carbon atoms, R ³ is an alkylene group having 2 to 6 carbon atoms, and m is 1 to 6 And n represents a number from 1 to 12, provided that all R ² may be the same or different, and all R ³ may be the same or different.   The crosslinked polylactic acid resin according to claim 1, comprising a crosslinked polylactic acid resin (A) obtained by kneading a polylactic acid resin and polycarbodiimide at 180 to 230 ° C and the carboxylic acid ester (B). Composition.   The crosslinked polylactic acid resin composition according to claim 1 or 2, wherein the carboxylic acid ester (B) represented by the formula (I) is 1 to 30 parts by weight with respect to 100 parts by weight of the crosslinked polylactic acid resin (A). . The crosslinked polylactic acid resin composition according to any one of claims 1 to 3, wherein the carboxylic acid ester (B) represented by the formula (I) is obtained using the following (1) to (3) as raw materials.
(1) Monohydric alcohol having an alkyl group having 1 to 4 carbon atoms
(2) Dicarboxylic acid having an alkylene group having 2 to 4 carbon atoms
(3) Dihydric alcohol having an alkylene group having 2 to 6 carbon atoms   The crosslinked polylactic acid resin according to any one of claims 1 to 4, wherein the carboxylic acid ester (B) represented by the formula (I) has an acid value of 1.50 mgKOH / g or less and a hydroxyl value of 10.0 mgKOH / g or less. Composition.   Furthermore, the crosslinked polylactic acid resin composition in any one of Claims 1-5 formed by mix | blending the phosphorus type flame retardant whose solubility parameter value (SP value) by a Fedors method is 10.1-11.2.   The resin molding formed by shape | molding the crosslinked polylactic acid resin composition in any one of Claims 1-6. The manufacturing method of the resin molding of Claim 7 which has following process (1)-(2).
Step (1): a crosslinked polylactic acid resin (A) and a carboxylic acid ester (B) represented by the following formula (I) having a solubility parameter value (SP value) by the Fedors method of 10.1 to 11.2; Step of preparing a crosslinked polylactic acid resin composition by melt-kneading a raw material containing R ¹ O—CO—R ² —CO — [(OR ³ ) _m O—CO—R ² —CO—] _n OR ¹ ( I)
Wherein R ¹ is an alkyl group having 1 to 4 carbon atoms, R ² is an alkylene group having 2 to 4 carbon atoms, R ³ is an alkylene group having 2 to 6 carbon atoms, and m is 1 to 6 And n represents a number from 1 to 12, provided that all R ² may be the same or different, and all R ³ may be the same or different.
Step (2): Step of injection molding the crosslinked polylactic acid resin composition obtained in Step (1) Crosslinking by mixing a carboxylic acid ester (B) represented by the following formula (I) and a crosslinked polylactic acid resin (A) having a solubility parameter value (SP value) by the Fedors method of 10.1 to 11.2. A method for preventing coloration of a polylactic acid resin composition.
R ¹ O—CO—R ² —CO — [(OR ³ ) _m O—CO—R ² —CO—] _n OR ¹ (I)
Wherein R ¹ is an alkyl group having 1 to 4 carbon atoms, R ² is an alkylene group having 2 to 4 carbon atoms, R ³ is an alkylene group having 2 to 6 carbon atoms, and m is 1 to 6 And n represents a number from 1 to 12, provided that all R ² may be the same or different, and all R ³ may be the same or different.