JP2014047234A - Polylactic acid resin composition - Google Patents

Abstract

To provide a polylactic acid resin composition having excellent transparency and having both strength and flexibility, and a method for producing the composition.
A polylactic acid resin composition comprising a polylactic acid resin and a refined layered double hydroxide-containing composition, wherein the refined layered double hydroxide-containing composition comprises an alkyl phosphorus. A polylactic acid resin composition obtained by a method comprising a step of refining a layered double hydroxide organized by an organic agent selected from the group consisting of acid esters and salts thereof in the presence of a plasticizer object.
[Selection figure] None

Description

  The present invention relates to a polylactic acid resin composition. More specifically, the present invention relates to a polylactic acid resin composition that can be suitably used as household goods, home appliance parts, automobile parts, and the like, and a method for producing 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, as a characteristic of the resin, it has an advantage that the rigidity is strong and the transparency is high. Therefore, it is currently expected to be used, and development of polylactic acid resin having higher rigidity and transparency is being promoted.

  For example, in Patent Document 1, when a cation exchange layered clay mineral treated with an organic ammonium compound is added to a polyester resin or the like, a reaction between the organic ammonium compound and the resin occurs during mixing, and the resin has a low molecular weight. Therefore, a method for improving mechanical properties such as elastic modulus by adding anion exchange layered clay mineral to a resin is disclosed.

  In Patent Document 2, as a filler for resin addition that can improve the mechanical properties of a polyester resin by adding a small amount, an intermediate layer of a hydrotalcite-like compound and an organic reagent having ion exchange / adsorption properties are used. An organic hydrotalcite-like compound formed by ion exchange is disclosed.

  Patent Document 3 discloses a nanocomposite obtained by pretreating a layered silicate with dimethyl sulfoxide (DMSO), ethanol or the like and then intercalating with an organic material such as hexadecyltrimethylammonium bromide. Has been.

  Patent Document 4 reports that when a basic oxide is contained in polylactic acid, a composition excellent in hue and moist heat resistance and having almost no foul odor can be obtained. Hydrotalcite is exemplified as a preferred example of the basic oxide, and it is also described that the basic oxide can be supported on an inert carrier used as a catalyst carrier such as silica and alumina. ing.

  Patent Document 5 discloses a method for improving tensile strength, impact strength, and heat resistance by adding a phosphate metal salt and a basic inorganic aluminum compound to a polylactic acid resin. As the phosphoric acid ester metal salt, a metal salt of a specific aromatic organic phosphoric acid is disclosed. In addition, as a preferable example of the basic inorganic aluminum compound, hydrotalcite can be cited as a preferred example, and the surface thereof is coated with higher fatty acid, higher fatty acid metal salt, organic sulfonic acid metal salt, higher fatty acid amide, higher fatty acid ester or wax. It is also described as good. These phosphate metal salt and basic inorganic aluminum compound are dry blended with a raw material such as polylactic acid resin and then kneaded to obtain pellets.

JP 2003-171568 A JP-A-2005-47946 Special table 2009-522390 Japanese Patent Application Laid-Open No. 2010-100774 JP 2003-192883 A

  In accordance with the prior art, a polylactic acid resin is blended with a layered compound such as hydrotalcite, and the layered compound is subjected to treatments such as organication and carrier retention, so that the strength and resistance of the polylactic acid resin composition are increased. It becomes possible to improve hydrolyzability and heat resistance. However, the polylactic acid resin composition is expected to be used in a wider range of applications such as automobile applications and food containers, and has an excellent transparency and has both strength and flexibility. A lactic acid resin composition is desired.

  An object of the present invention is to provide a polylactic acid resin composition having excellent transparency and having both strength and flexibility, and a method for producing the composition.

  As a result of intensive studies on the above problems, the present inventors have obtained an excellent polylactic acid resin composition obtained by blending a polylactic acid resin with a layered double hydroxide that has been refined in the presence of a plasticizer. The present invention has been completed by finding that it has excellent transparency and has both strength and flexibility.

  That is, the present invention is a polylactic acid resin composition containing a polylactic acid resin and a refined layered double hydroxide-containing composition, wherein the refined layered double hydroxide-containing composition comprises: Polylactic acid obtained by a method comprising a step of refining a layered double hydroxide organized by an organic agent selected from the group consisting of alkyl phosphate esters and salts thereof in the presence of a plasticizer The present invention relates to a resin composition.

  The polylactic acid resin composition of the present invention has an excellent effect of having excellent transparency and achieving both strength and flexibility.

  In the polylactic acid resin composition of the present invention, a layered double hydroxide obtained by organizing a polylactic acid resin with an organic agent selected from the group consisting of an alkyl phosphate ester and a salt thereof is refined in the presence of a plasticizer. It has the big characteristic in containing the layered double hydroxide containing composition obtained by the method which has the process to do. Here, “organization” refers to replacing part or all of the counter ion of the layered double hydroxide with an anionic group having an alkyl group.

As the layered double hydroxide, for example, hydrotalcite is a layered compound having a composition of Mg ₆ Al ₂ (OH) ₁₆ CO ₃ .4H ₂ O, and the layered compound is dispersed in the resin to form a resin. Strength is improved. However, since a resin with high strength is inferior in flexibility, a further polylactic acid resin having both resin strength and flexibility is required. Thus, as a result of studies by the present inventors, it was obtained by refining a layered double hydroxide organized by an organic agent selected from the group consisting of alkyl phosphate esters and salts thereof in the presence of a plasticizer. It has been found that the resin containing the layered double hydroxide-containing composition has excellent strength and flexibility. Although the detailed reason is unknown, in the refined layered double hydroxide-containing composition, it is presumed that the plasticizer and the layered double hydroxide have some interaction. Therefore, when the micronization is performed in the presence of the plasticizer, the plasticizer is attached to the surface of the resulting layered double hydroxide, and in the melt-kneading step, the refined layered double hydroxide is obtained. It is considered that the contained composition is finely dispersed in the polylactic acid resin without reaggregating. For this reason, it is considered that the contact area between the polylactic acid resin and the layered double hydroxide-containing composition is increased, and the strength is remarkably improved. In addition, since the layered double hydroxide to be refined is organicized with an alkyl phosphate ester or a salt thereof having a high affinity with the layered compound, the interlayer easily swells, so that the polylactic acid resin easily enters the interlayer. Thus, it is considered that the affinity with the layered double hydrate can be further increased. Furthermore, the layered double hydroxide-containing composition according to the present invention has a contact area because the polylactic acid resin is inserted between layers of the layered double hydroxide by melt-kneading with the polylactic acid resin. Polylactic acid resin composition with excellent transparency and high flexibility due to the effect of the plasticizer, as the composition containing layered double hydroxide, which has been further refined and refined in addition to high strength, is highly dispersed. It is thought that a thing is obtained. In this specification, “strength” means a property evaluated by “tensile elastic modulus” described later, and “flexibility” means a property evaluated by “elongation at break” described later. “Achieving compatibility between strength and flexibility of a product” means compatibility between strength and flexibility of a molded product obtained by molding the composition.

(Layered double hydroxide-containing composition)
The layered double hydroxide-containing composition in the present invention is a step of refining a layered double hydroxide organized by an organic agent selected from the group consisting of alkyl phosphates and salts thereof in the presence of a plasticizer. It is obtained by a method having

The layered double hydroxide in the present invention is an inorganic layered compound obtained by crystallizing a hydroxide of an element such as magnesium, calcium, zinc, aluminum, bismuth, iron, etc. and has a layered structure. However, a compound having a multilayer structure in which the intermediate layer represented by the general formula (2) is sandwiched between the basic layers represented by the general formula (1) is preferable. Specifically, hydrotalcite, mana Site, alunite, calcite and magnesite are preferred, and hydrotalcite and manasite are more preferred.
[M2 ⁺ _1-p M3 ⁺ _p (OH) ₂ ] Formula (1)
( ^Wherein M ²⁺ is a divalent metal ion such as Mg ²⁺ , Mn ²⁺ , Ni ²⁺ , Fe ²⁺ , Zn ²⁺ , and M ³⁺ is a trivalent metal ion such as Al ³⁺ , Cr ³⁺ , Fe ³⁺ , Co ^3+. And p is 0.2 or more and 0.33 or less)
[A ^n- _{p / n} · qH ₂ O] Formula (2)
(Wherein, n is a number from 1 or ^{2, A n-is _{OH -, Cl -, CO 3}} 2-, SO 4 2-, ClO 4 -, NO 3 -, I -, F -, Br - And q is an integer of 1 or more and 10 or less)

  In a layered structure, organic compounds having various anion species and cation species can be inserted (intercalated) between layers, thereby increasing the interlayer distance and increasing the contact area with the polylactic acid resin. It is considered that strength and transparency can be imparted to the resin composition. Therefore, the layered double hydroxide in the present invention is not limited to the viewpoint of improving the refinement of the layered double hydroxide, but also from the viewpoint of improving the strength and transparency of the polylactic acid resin composition. A compound that is organized with an organic agent selected from the group consisting of alkyl phosphates having functional groups with excellent affinity and salts thereof is used.

As the alkyl phosphate ester, the following formula (I):

As the salts thereof, the following formulas (II-1) and (II-2):

The compound represented by these is preferable.

R ¹ in formula (I), formula (II-1), and formula (II-2) is preferably an alkyl group having 4 to 24 carbon atoms, more preferably 8 to 18 carbon atoms, and is linear. It may be branched or branched. Specific examples include a hexyl group, an octyl group, a decyl group, a dodecyl group (lauryl group), a myristyl group, and an octadecyl group (stearyl group), and in particular, from the viewpoint of improving the refinement of the layered double hydroxide. In addition, from the viewpoint of improving the strength and transparency of the polylactic acid resin composition, a lauryl group and a stearyl group are preferable, and a lauryl group is more preferable.

  Moreover, M in Formula (II-1) and Formula (II-2) is a monovalent alkali metal, preferably sodium or potassium.

  M in the formula (I), the formula (II-1) and the formula (II-2) represents the strength and transparency of the polylactic acid resin composition in addition to the viewpoint of improving the refinement of the layered double hydroxide. From a viewpoint of improving, 0-5 are preferable and 0-3 are more preferable.

  Specific examples of alkyl phosphates and salts thereof include lauryl phosphate, sodium lauryl phosphate, disodium lauryl phosphate, potassium lauryl phosphate, dipotassium lauryl phosphate, polyoxyethylene lauryl ether phosphate, polyoxyethylene Sodium lauryl ether phosphate, disodium polyoxyethylene lauryl ether phosphate, potassium polyoxyethylene lauryl ether phosphate, dipotassium polyoxyethylene lauryl ether phosphate, myristyl phosphate, sodium myristyl phosphate, disodium myristyl phosphate, myristyl Potassium phosphate, dipotassium myristyl phosphate, polyoxyethylene myristyl ether phosphate, polyoxyethylene myristyl ether sodium phosphate, poly Disodium oxyethylene myristyl ether phosphate, polyoxyethylene myristyl ether potassium phosphate, polyoxyethylene myristyl ether dipotassium phosphate, cetyl phosphate, sodium cetyl phosphate, disodium cetyl phosphate, potassium cetyl phosphate, dipotassium cetyl phosphate, polyoxyethylene Cetyl ether phosphate, sodium polyoxyethylene cetyl ether phosphate, disodium polyoxyethylene cetyl ether phosphate, potassium polyoxyethylene cetyl ether phosphate, dipotassium polyoxyethylene cetyl ether phosphate, stearyl phosphate, stearyl phosphate Sodium, disodium stearyl phosphate, potassium stearyl phosphate, dipotassium stearyl phosphate, polyoxyethylene These include ether ether phosphate, sodium polyoxyethylene stearyl ether phosphate, disodium polyoxyethylene stearyl ether phosphate, potassium polyoxyethylene stearyl ether phosphate, dipotassium polyoxyethylene stearyl ether phosphate, among others, From the viewpoint of improving the strength and transparency of the polylactic acid resin composition in addition to the viewpoint of improving the refinement of the layered double hydroxide, lauryl phosphate, sodium lauryl phosphate, disodium lauryl phosphate, lauryl phosphate Potassium, dipotassium lauryl phosphate, polyoxyethylene lauryl ether phosphate, sodium polyoxyethylene lauryl ether phosphate, disodium polyoxyethylene lauryl ether phosphate, polyoxyethylene N-lauryl ether potassium phosphate and polyoxyethylene lauryl ether dipotassium phosphate are preferred. You may use these individually or in combination of 2 or more types.

  The method for organizing the layered double hydroxide with the organic agent is not particularly limited, and a known method is used. For example, Chem. Commun. 2000, 91-92, and Japanese Patent Application Laid-Open No. 2009-173482. Specifically, there may be mentioned a method in which ions between layers of a layered double hydroxide dispersed in water are once replaced with chloride ions with sodium chloride, and then interlayer ions are replaced with a target organic agent. In addition, when substituting with the target organic agent, the treatment may be performed once (for example, mixing at 70 ° C.) or divided into a plurality of times (for example, mixing at 45 ° C. twice). Good.

  The amount of the organic agent used for the organication increases the interlayer distance of the layered double hydroxide, increases the contact area with the polylactic acid resin, and gives strength and transparency to the polylactic acid resin composition before treatment. 30 to 500 parts by weight is preferable, 50 to 450 parts by weight is more preferable, and 100 to 400 parts by weight is more preferable with respect to 100 parts by weight of the layered double hydroxide. The amount of the organic agent as used herein refers to the total amount of the organic agent used for organic formation when the substitution treatment is performed in multiple steps.

  Although the shape and average particle diameter of the layered double hydroxide subjected to the refining treatment are not particularly limited as long as the refining treatment can be performed, 1 to 100 μm is preferable, and 5 to 60 μm is more preferable. The interlayer distance is preferably 0.5 to 5.0 nm, more preferably 1.5 to 4.5 nm, and still more preferably 1.8 to 4.0 nm. In the present specification, the average particle size of the layered double hydroxide can be measured according to the method described in Examples described later.

  In the present invention, such a layered double hydroxide is subjected to a treatment step for refining in the presence of a plasticizer (hereinafter also referred to as a refining treatment step).

  The plasticizer used in the refinement treatment step is not particularly limited, and examples thereof include known ones. For example, phthalate esters such as di-n-octyl phthalate, di-2-ethylhexyl phthalate, dibenzyl phthalate, and diisodecyl phthalate. , Isophthalic acid esters such as dioctyl isophthalate, di-n-butyl adipate, adipic acid esters such as dioctyl adipate, maleic acid esters such as di-n-butyl malate, citrate esters such as acetyl tri-n-butyl citrate, Polyalkyl alcohols such as itaconic acid esters such as monobutyl itaconate, oleic acid esters such as butyl oleate, diacetyl caprylic acid monoglyceride, diacetyl lauric acid monoglyceride, ricinoleic acid monoglyceride, decaglycerin monoelate Polyalkylene glycols such as phosphate esters such as ester esters, tricresyl phosphate, polyethylene glycol (hereinafter PEG), PEG diacetate, polypropylene glycol (hereinafter PPG), PEG-PPG-PEG block polymers, PPG-PEG-PPG block polymers , Lactic acid oligomer esters such as triethylene glycol monomethyl ether lactic acid oligomer ester, and rosin acid esters such as diethylene glycol rosin ester acetate can be used. Among these, from the viewpoint of improving the refinement of the layered double hydroxide, and from the viewpoint of improving the flexibility of the polylactic acid resin composition by adhering the plasticizer to the layered compound by the refinement, a carboxylic acid ester and And / or a phosphate ester, and among them, from the viewpoint of further improving the compatibility between the strength and flexibility of the polylactic acid resin composition, an alcohol component having two or more ester groups in the molecule and constituting the ester It is preferable that at least one of these contains an ester compound (hereinafter referred to as “AO addition ester compound”) obtained by adding an average of 0.5 to 5 moles of alkylene oxide having 2 to 3 carbon atoms per hydroxyl group.

The carboxylic acid ester is preferably an oligoester represented by the following formula (III) from the viewpoint of improving the flexibility of the polylactic acid resin composition and improving the miniaturization of the layered double hydroxide.
R ³ O—CO—R ⁴ —CO — [(OR ⁵ ) _a O—CO—R ⁴ —CO—] _b OR ³ (III)
Wherein R ³ is an alkyl group having 1 to ⁴ carbon atoms, R ⁴ is an alkylene group having 2 to 4 carbon atoms, R ⁵ is an alkylene group having 2 to 6 carbon atoms, and a is 1 to 6 And b represents a number from 1 to 6, provided that all R ⁴ may be the same or different, and all R ⁵ may be the same or different.

R ³ in formula (III) 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 ³ 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 improving the compatibility with the polylactic acid resin and expressing the plasticizing effect. Specific examples include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, and a tert-butyl group. Among them, the compatibility with a polylactic acid resin is improved and a plasticizing effect is obtained. From the viewpoint of expression, a methyl group is preferable.

R ⁴ in formula (III) 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. Among them, from the viewpoint of improving compatibility with the polylactic acid resin and expressing flexibility, an ethylene group, A 1,3-propylene group is preferred, an ethylene group is more preferred, and an ethylene group and a 1,4-butylene group are preferred, and an ethylene group is more preferred from the viewpoints of developing flexibility and economic efficiency. However, all R ⁴ may be the same or different.

R ⁵ in formula (III) represents an alkylene group having 2 to 6 carbon atoms, and OR ⁵ represents an oxyalkylene group. R ⁵ 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 compatibility with the 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 others, the viewpoint of improving the compatibility with polylactic acid resin and developing the plasticizing effect Therefore, an ethylene group, a 1,2-propylene group, and a 1,3-propylene group are preferable. However, all R ⁵ may be the same or different.

  a shows the average repeating number of an oxyalkylene group, and is a number of 1-6. When a becomes large, the ether group value of the ester compound represented by the formula (III) increases, which tends to be oxidized and the stability tends to decrease. From the viewpoint of improving the compatibility with the polylactic acid resin, the number of 1 to 4 is preferable, and the number of 1 to 3 is more preferable.

  b shows an average degree of polymerization and is a number of 1-6. From the viewpoint of improving the compatibility with the polylactic acid resin and improving the flexibility of the polylactic acid resin, the number of 1 to 4 is preferable.

Specific examples of the compound represented by the formula (III) include an ester in which R ³ is a methyl group, R ⁴ is an ethylene group, R ⁵ is an ethylene group, a is 2 and b is 1.5, R ³ Is an ethyl group, R ⁴ is a 1,4-butylene group, R ⁵ is a 1,3-propylene group, a is an ester of 1, b is 2, R ³ is a butyl group, R ⁴ is 1,3- A propylene group, R ⁵ is an ethylene group, a is an ester of 3, b is 1.5, R ³ is a methyl group, R ⁴ is an ethylene group, R ⁵ is a 1,6-hexylene group, 1 and b are 3 esters, and these may be used alone or in combination of two or more. Among these, R ³ is all methyl group, R ⁴ is ethylene group or 1,4-butylene group, R ⁵ is ethylene group or 1,3-propylene group, a is a number of 1 to 3, b Is preferably a compound in which R ³ is a methyl group, R ⁴ is an ethylene group or a 1,4-butylene group, R ⁵ is an ethylene group or a 1,3-propylene group, and a is A compound having 1 to 3 and b being 1 to 3 is more preferable.

  The acid value of the oligoester represented by the formula (III) is preferably 1.00 mgKOH / g or less, more preferably 0.90 mgKOH / g or less, and the hydroxyl value is preferably 5.0 mgKOH / g or less, and 4.0 mgKOH / g. The number average molecular weight is more preferably 300 to 700, and more preferably 350 to 600.

  From the viewpoint of improving volatility, at least one dibasic acid selected from succinic acid, glutaric acid, and adipic acid, diethylene glycol, triethylene glycol, 1,2-propanediol, and 1,3-propane An oligoester of at least one dihydric alcohol selected from diols [in formula (III), b = 1.2 to 3] is preferable.

  As the phosphate ester, from the viewpoint of improving the refinement of the layered double hydroxide and from the viewpoint of improving the flexibility of the polylactic acid resin composition by attaching the plasticizer to the layered compound by the refinement. And the following formula (IV):

(In the formula, R ⁶ , R ⁷ and R ⁸ each independently represents an alkyl group having 1 to 4 carbon atoms, and A ¹ , A ² and A ³ each independently represents an alkylene group having 2 or 3 carbon atoms. X, y and z are each independently a positive number indicating the average number of moles added of the oxyalkylene group, and x + y + z is a number satisfying 4 to 12)
The compound represented by these is preferable.

  The compound represented by the formula (IV) is a polyether-type phosphate triester, which may be a symmetric structure or an asymmetric structure, but a phosphotriester having a symmetric structure is preferred from the standpoint of production.

R ⁶ , R ⁷ and R ⁸ each independently represent an alkyl group having 1 to 4 carbon atoms and may be linear or branched. Specific examples include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, and an isobutyl group, and an ethyl group, a propyl group, and a butyl group are preferable, and an ethyl group and a propyl group are more preferable.

A ¹ , A ² , and A ³ each independently represent an alkylene group having 2 or 3 carbon atoms, and may be linear or branched. Specific examples include an ethylene group, an n-propylene group, and an isopropylene group, and an ethylene group is preferable. A ¹ , A ² , and A ^{3 form} adjacent oxygen atoms and an oxyalkylene group (alkylene oxide) to form a repeating structure in the compound represented by formula (IV).

  x, y and z are each independently a positive number indicating the average added mole number of the oxyalkylene group, and x + y + z is 4 to 12, and the viewpoint of improving the refinement of the layered double hydroxide, and From the viewpoint of improving the flexibility of the polylactic acid resin composition by adhering the plasticizer to the layered compound by miniaturization, the number is preferably 5 to 10, more preferably 6 to 9 It is a number to do.

  Specific examples of the compound represented by the formula (IV) include the formula (V):

Tris (ethoxyethoxyethyl) phosphate represented by the formula [In the formula (IV), R ⁶ , R ⁷ and R ⁸ are all ethyl groups, A ¹ , A ² and A ³ are all ethylene groups, x, y, z is 2 and x + y + z = 6], tris (methoxyethoxyethyl) phosphate, tris (propoxyethoxyethyl) phosphate, tris (butoxyethoxyethyl) phosphate, tris (methoxyethoxyethoxyethyl) phosphate, tris ( Symmetric polyether phosphate triesters such as ethoxyethoxyethoxyethyl) phosphate, and asymmetric polyether phosphates such as bis (ethoxyethoxyethyl) methoxyethoxyethoxyethyl phosphate and bis (methoxyethoxyethoxyethyl) ethoxyethoxyethyl phosphate Examples include asymmetric polyether-type phosphate ester obtained by reesterifying a mixture of a polyoxyethylene adduct or a polyoxypropylene adduct of a C 1-4 alcohol with a phosphoric acid so as to satisfy the formula (IV). From the viewpoint of improving the refinement of the layered double hydroxide and from the viewpoint of improving the flexibility of the polylactic acid resin composition by adhering the plasticizer to the layered compound by the refinement, tris (ethoxyethoxyethyl) ) Phosphate is preferred.

  Moreover, as said AO addition ester compound, it has a plasticizer as described in Unexamined-Japanese-Patent No. 2008-115372 and Unexamined-Japanese-Patent No. 2008-174718, ie, has two or more ester groups in a molecule | numerator, and comprises ester. An ester compound in which an average of 0.5 to 5 moles of an alkylene oxide having 2 to 3 carbon atoms per hydroxyl group is added as at least one of the alcohol components is exemplified. For example, an alkyleneoxy group having 2 or 3 carbon atoms per hydroxyl group Is preferably a compound obtained by polycondensation of an alcohol component such as an alkylene oxide adduct of alcohol with an average of 0.5 to 5 moles of addition and a known carboxylic acid component.

  The condensation polymerization of the alcohol component and the carboxylic acid component can be performed according to a known method, for example, a method described in JP-A-2008-174735.

  In the present invention, an ester of succinic acid or adipic acid and polyethylene glycol monomethyl ether from the viewpoint of compatibility between strength and flexibility of the polylactic acid resin composition, moldability, plasticity, and improvement of bleed resistance of the plasticizer. At least one selected from the group consisting of a compound and an ester compound of acetic acid and glycerin or ethylene glycol ethylene oxide adduct is preferred, and an ester compound of succinic acid or adipic acid and polyethylene glycol monomethyl ether is more preferred.

  From the viewpoint of improving volatility resistance and improving the flexibility of the polylactic acid resin composition, an ester compound of adipic acid and a mixture of diethylene glycol monomethyl ether / benzyl alcohol (weight ratio: 1/1) Is preferred.

  The AO addition ester compound is from the viewpoint of improving the refinement of the layered double hydroxide and from the viewpoint of improving the flexibility of the polylactic acid resin composition by adhering the plasticizer to the layered compound by the refinement. , It is preferable that all the acid groups are esterified.

The average molecular weight of the AO ester compound is preferably 250 to 700, more preferably from the viewpoint of improving both the strength and flexibility of the polylactic acid resin composition and improving the bleed resistance and volatilization resistance of the plasticizer. Is 300 to 600, more preferably 350 to 550, and still more preferably 400 to 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 = 56,108 × (number of ester groups per molecule) / saponification value

  These carboxylic acid esters and phosphoric acid esters may be used alone or in combination. In addition to the carboxylic acid ester and phosphoric acid ester, other esters and the like may be used in combination as long as the effects of the present invention are not impaired. Can do. The content of the carboxylic acid ester and the phosphoric acid ester is not particularly limited. However, from the viewpoint of improving both the strength and flexibility of the polylactic acid resin composition and improving the bleed resistance of the plasticizer, 60 in the plasticizer. % By weight or more is preferable, 70% by weight or more is more preferable, 90% by weight or more is further preferable, and substantially 100% by weight is even more preferable.

  Although there is no limitation in particular as a method of a refinement | miniaturization process, wet pulverization is preferable. As a pulverizer used for wet pulverization, a known pulverizer such as a medium pulverizer or a non-media pulverizer can be used, and is not particularly limited. Non-medium pulverizers include high-pressure pulverizers such as ultrasonic homogenizers and jet mills. The medium type pulverizer includes a container drive type pulverizer and a medium stirring type pulverizer. Examples of the container-driven crusher include a paint shaker, a rolling mill, a vibration mill, a planetary mill, and a centrifugal fluid mill. Among these, a vibration mill is preferable from the viewpoint of high grinding efficiency and productivity. As a medium agitation pulverizer, a tower type pulverizer such as a tower mill; an agitator tank type pulverizer such as an attritor, an aquamizer, and a sand grinder; a distribution tank type pulverizer such as a visco mill and a pearl mill; For example, a continuous dynamic type pulverizer. Among these, a stirring tank type pulverizer is preferable from the viewpoint of high pulverization efficiency and improved productivity. The peripheral speed at the tip of the stirring blade when using the medium stirring pulverizer is preferably 0.5 to 20 m / s, more preferably 1.0 to 15 m / s. In addition, the kind of grinder can refer to "Progress of chemical engineering 30th particle control" (Chemical Engineering Society, Tokai branch edition, published on October 10, 1996, Kashiwa Shoten). Moreover, as a processing method, either a batch type or a continuous type may be sufficient.

  The refining treatment time cannot be determined unconditionally depending on the type of pulverizer, the type of medium, the size, the filling rate, etc., but from the viewpoint of refining the layered double hydroxide, preferably 0.02 to 5 hr, Preferably it is 0.05-3 hr, More preferably, it is 0.10-2 hr. Although processing temperature does not have a restriction | limiting in particular, From a viewpoint of preventing deterioration by a heat | fever, Preferably it is 5-250 degreeC, More preferably, it is 10-200 degreeC.

  As a specific aspect of wet pulverization, for example, an organic layered double hydroxide and the plasticizer may be added independently or simultaneously to a medium pulverizer and wet pulverized.

  Thus, a refined layered double hydroxide-containing composition is obtained. In the present invention, the obtained layered double hydroxide-containing composition may be subjected to a cleaning step, a dilution step, a concentration step, and the like according to a known method after the step of refining.

  The average particle size of the refined layered double hydroxide-containing composition is preferably 0.1 to 20 μm, more preferably 0.1 to 15 μm, and still more preferably 0.1 to 10 μm. In addition, the interlayer distance is preferably 2.0 to 5.0 nm from the viewpoint of increasing the contact area with the polylactic acid resin, increasing the strength of the resulting polylactic acid resin composition and increasing the transparency, and 2.0 to 4 0.0 nm is more preferable, and 2.5 to 4.0 nm is more preferable.

(Polylactic acid resin)
The polylactic acid resin in the present invention is polylactic acid or a copolymer of lactic acid and hydroxycarboxylic acid. Examples of the hydroxycarboxylic acid include glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxypentanoic acid, hydroxycaproic acid, hydroxyheptanoic acid and the like, and glycolic acid and hydroxycaproic acid are preferable.

  The molecular structure of polylactic acid is preferably composed of 80 to 100 mol% of either L-lactic acid (L-form) or D-lactic acid (D-form) and 0 to 20 mol% of the enantiomer. . The copolymer of lactic acid and hydroxycarboxylic acid is composed of 85 to 100 mol% of either L-lactic acid or D-lactic acid and 0 to 15 mol% of hydroxycarboxylic acid units.

  These polylactic acid resins can be obtained by dehydrating polycondensation using L-lactic acid, D-lactic acid and hydroxycarboxylic acid as a raw material by selecting those having the required structure. Preferably, it can be obtained by ring-opening polymerization by selecting a desired structure from lactide, which is a cyclic dimer of lactic acid, glycolide, which is a cyclic dimer of glycolic acid, and caprolactone. 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, and D-lactide. There is DL-lactide, which is a racemic mixture of lactide and L-lactide. Any lactide can be used in the present invention. However, the main raw material is preferably D-lactide or L-lactide.

  In the present invention, from the viewpoint of improving the moldability of the polylactic acid resin composition, it is preferable to use a polylactic acid resin having a high optical purity of the lactic acid component. That is, it is preferable that 80% or more of the L-form or D-form is included in the total lactic acid component of the polylactic acid resin, more preferably 90% or more of the L-form or D-form is contained, % Or more, more preferably 98% or more of L-form or D-form, and still more preferably 99% or more of L-form or D-form.

  Further, in the present invention, as polylactic acid, both the viewpoint of improving the moldability and transparency of the polylactic acid resin composition, and the strength and impact resistance of the molded body made of the polylactic acid resin composition are improved, and the heat resistance is improved. From the point of view, stereocomplex polylactic acid composed of two types of polylactic acid obtained by using a lactic acid component mainly composed of different isomers may be used. One polylactic acid constituting the stereocomplex polylactic acid (hereinafter referred to as polylactic acid (A)) contains 90 to 100 mol% of L isomer and 0 to 10 mol% of other components including D isomer. The other polylactic acid (hereinafter referred to as polylactic acid (B)) contains 90 to 100 mol% of D isomer and 0 to 10 mol% of other components including L isomer. Examples of the other components other than the L-form and D-form include dicarboxylic acids, polyhydric alcohols, hydroxycarboxylic acids, lactones and the like having a functional group capable of forming two or more ester bonds. Polyester, polyether, polycarbonate or the like having two or more functional groups in the reaction 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 preferably 10/90 to 90/10, and 20/80 to 80 / 20 is more preferable, and 40/60 to 60/40 is more preferable.

  The weight average molecular weight of the polylactic acid resin is preferably 100,000 or more from the viewpoint of improving the mechanical properties of a molded article made of the polylactic acid resin composition, and improves the fluidity during molding of the polylactic acid resin composition. It is preferable that it is 400,000 or less from a viewpoint to make it. The weight average molecular weight of the polylactic acid resin was determined by using gel permeation chromatography (GPC), chloroform as the solvent, Tosoh Corporation column, high temperature SEC column (GMHHR-H series), flow rate 1.0 mL / min, column The temperature can be calculated by using a differential refractive index detector (RI) as a detector at a temperature of 40 ° C. and polystyrene having a known molecular weight as a reference.

  Polylactic acid can be synthesized according to a known method, but a commercially available product can be used. For example, Mitsui Chemicals Co., Ltd., trade name Lacia; Toyota Motor Co., Ltd., trade name Eco Plastic U'z; Nature Works Co., Ltd., trade name Nature works; Zhejiang Haisho Biomaterials Co., Ltd., trade name REVODE, etc. Can be mentioned. Among the above-mentioned commercially available products, from the viewpoint of improving the moldability, Mitsui Chemicals, trade names Lacia H-100, H-400, H-440, Toyota Motor Corporation, trade names Eco Plastic U'z S -9, S-12, S-17, manufactured by Nature Works, trade names Nature works 4032D and 3001D are preferable.

  The content of the polylactic acid resin in the polylactic acid resin composition of the present invention is preferably 50% by weight or more, more preferably 70% by weight or more from the viewpoint of achieving the object of the present invention.

  The polylactic acid resin composition of the present invention further contains a crystal nucleating agent, a plasticizer, a hydrolysis inhibitor, and the like as appropriate in addition to the finely divided layered double hydroxide-containing composition and the polylactic acid resin. It may be.

  The content of the refined layered double hydroxide-containing composition improves the strength, flexibility, and transparency of the molded product made of the obtained polylactic acid resin composition with respect to 100 parts by weight of the polylactic acid resin. From the viewpoint of making it, 1 to 30 parts by weight is preferable, 2 to 25 parts by weight is more preferable, 3 to 15 parts by weight is further preferable, and 5 to 15 parts by weight is further preferable. Further, the content of the layered double hydroxide in the polylactic acid resin composition is such that the strength, flexibility, and transparency of the molded product made of the polylactic acid resin composition obtained with respect to 100 parts by weight of the polylactic acid resin. 0.1 to 15 parts by weight is preferable, 0.2 to 10 parts by weight is more preferable, 0.5 to 8 parts by weight is further preferable, and the molded article made of the polylactic acid resin composition obtained is preferable. From the viewpoint of further improving the transparency, 0.1 to 3 parts by weight is preferable, 0.2 to 2 parts by weight is preferable, and 0.5 to 1.5 parts by weight is more preferable. In the present specification, “content” means “content or blending amount”.

  The weight ratio of the layered double hydroxide to the plasticizer (layered double hydroxide / plasticizer) in the refinement treatment process improves the compatibility with the polylactic acid resin from the viewpoint of further miniaturizing the layered double hydroxide. From the viewpoint of improving flexibility, 1/99 to 40/60 is preferable, 4/96 to 40/60 is more preferable, 6/94 to 40/60 is further preferable, and 8/92 to 40/60 is more preferable. Even more preferred. When the weight ratio of the layered double hydroxide and the plasticizer is in the above range, the layered double hydroxide is refined without agglomeration and the plasticizer adheres to the surface of the layered double hydroxide. A composition is obtained. In addition, the weight of a plasticizer here means the total weight of the used plasticizer, when using a plurality of plasticizers.

(Plasticizer)
In the present invention, a plasticizer (also referred to as an additional plasticizer) can be further contained from the viewpoint of improving the transparency and flexibility of the polylactic acid resin composition. In the present invention, since the plasticizer present on the surface of the refined layered double hydroxide-containing composition exhibits flexibility, a good crystallization rate and no additional plasticizer can be obtained. A polylactic acid resin composition having heat resistance can be obtained.

  As the plasticizer to be added to the polylactic acid resin composition, the same plasticizer as that used when preparing the layered double hydroxide-containing composition can be used. In addition, the content of the total plasticizer in the polylactic acid resin composition is based on 100 parts by weight of the polylactic acid resin from the viewpoint of improving the heat resistance, transparency, and flexibility of the molded body made of the polylactic acid resin composition. The amount is preferably 1 to 30 parts by weight, more preferably 3 to 25 parts by weight, and still more preferably 5 to 20 parts by weight. The total plasticizer content means the total content of the plasticizer contained in the layered double hydroxide-containing composition and the plasticizer (additional plasticizer) added separately to the polylactic acid resin composition. To do.

(Crystal nucleating agent)
In the present invention, it is preferable to contain a crystal nucleating agent from the viewpoint of improving the crystallization speed of the polylactic acid resin composition of the present invention and the heat resistance and moldability of the molded body made of the polylactic acid resin composition. As the crystal nucleating agent, known ones are used without particular limitation. From the viewpoint of improving the heat resistance and strength of the polylactic acid resin composition, a compound having a hydroxyl group and an amide group in the molecule, phthalocyanine, and phosphate ester. From the group consisting of metal salts, 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 At least one selected from the above is preferable, and a compound having a hydroxyl group and an amide group in the molecule is preferable from the viewpoint of improving the crystallization speed of the polylactic acid resin and the heat resistance of the molded article made of the polylactic acid resin composition. The crystal nucleating agent is melted during the kneading of the polylactic acid resin to generate a large number of crystal nuclei, and the polylactic acid resin composition obtained by interaction with the refined layered double hydroxide-containing composition The crystallization speed and heat resistance of the product can be further improved.

  From the viewpoint of improving the crystallization speed of the polylactic acid resin composition, the compatibility with the polylactic acid resin, and the impact resistance and moldability of the polylactic acid resin composition as the compound having a hydroxyl group and an amide group in the molecule. An aliphatic amide having a hydroxyl group is preferred, and an aliphatic amide having two or more hydroxyl groups and two or more amide groups in the molecule is more preferred.

  The melting point of the compound having a hydroxyl group and an amide group in the molecule is preferably 65 ° C. or higher, more preferably 70 to 220 ° C. from the viewpoint of improving the dispersibility of the crystal nucleating agent during kneading and improving the crystallization speed. 80 to 190 ° C is 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 bis. Examples thereof include hydroxy fatty acid bisamides such as 12-hydroxystearic acid amide, and hydroxy fatty acid triamides such as 12-hydroxystearic acid triglyceride. From the viewpoint of improving the moldability of the polylactic acid resin composition, the heat resistance and impact resistance of the molded product made of the polylactic acid resin composition, and the bloom resistance of the crystal nucleating agent, ethylene bis 12-hydroxystearic acid amide, hexamethylene Hydroxy fatty acid bisamides such as bis12-hydroxystearic acid amide and 12-hydroxystearic acid triglyceride are preferable, and ethylene bis12-hydroxystearic acid amide is more preferable.

  Weight ratio of the compound having a hydroxyl group and an amide group in the molecule to the refined layered double hydroxide-containing composition (compound having a hydroxyl group and an amide group in the molecule / a refined layered double hydroxide-containing composition) ) Is 0.5 / 99.5 from the viewpoint of increasing the crystallization speed of the polylactic acid resin, the moldability of the polylactic acid resin composition, and the heat resistance of the molded body made of the polylactic acid resin composition. 20/80 is preferable, 0.5 / 99.5 to 17/83 is more preferable, 1.0 / 99.0 to 10/90 is further preferable, and 1.5 / 98.5 to 8/92 is even more preferable. preferable.

  The content of the crystal nucleating agent in the polylactic acid resin composition is 0 with respect to 100 parts by weight of the polylactic acid resin from the viewpoint of improving the heat resistance, impact resistance, and moldability of the molded body made of the polylactic acid resin composition. 0.1-5 parts by weight is preferable, 0.15-5 parts by weight is more preferable, 0.20-3 parts by weight is further preferable, and 0.25-2 parts by weight is more preferable.

(Hydrolysis inhibitor)
The polylactic acid resin composition of the present invention can further contain a hydrolysis inhibitor from the viewpoint of improving strength, durability, and hydrolysis resistance. Examples of the hydrolysis inhibitor include carbodiimide compounds such as polycarbodiimide compounds and monocarbodiimide compounds. From the viewpoint of improving the strength, durability, and impact resistance of the polylactic acid resin composition, polycarbodiimide compounds are preferable, and the polylactic acid resin composition From the viewpoint of improving the durability and moldability (fluidity) of the product, a monocarbodiimide compound is preferred. Moreover, it is preferable to use together monocarbodiimide and polycarbodiimide from the viewpoint of further improving the durability, impact resistance, and moldability of the molded article made of the polylactic acid resin composition.

  Examples of the polycarbodiimide compound include poly (4,4′-diphenylmethanecarbodiimide), poly (4,4′-dicyclohexylmethanecarbodiimide), poly (1,3,5-triisopropylbenzene) polycarbodiimide, 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 compound may be used singly or in combination of two or more in order to satisfy the durability, impact resistance and moldability of the molded article made of the polylactic acid resin composition. Poly (4,4′-dicyclohexylmethane carbodiimide) is obtained from carbodilite LA-1 (manufactured by Nisshinbo Chemical Co., Ltd.), poly (1,3,5-triisopropylbenzene) polycarbodiimide and poly (1,3,5-tri (Isopropylbenzene and 1,5-diisopropylbenzene) polycarbodiimide is stavaxol P and stabaxol P-100 (manufactured by Rhein Chemie), and N, N'-di-2,6-diisopropylphenylcarbodiimide is stavaxol I (Rhein Chemie). Can be purchased and used.

  The content of the hydrolysis inhibitor is preferably 0.05 to 3 parts by weight with respect to 100 parts by weight of the polylactic acid resin, from the viewpoint of improving the transparency and moldability of the molded body made of the polylactic acid resin composition. 0.10 to 2 parts by weight is more preferable.

  In addition to the above, the polylactic acid tree composition of the present invention preferably further contains an inorganic filler other than the refined layered double hydroxide-containing composition from the viewpoint of improving physical properties such as strength. .

(Inorganic filler)
As the inorganic filler, fibers, plates, granules, and powders that are usually used for reinforcing thermoplastic resins can be used. Specifically, glass fiber, carbon fiber, graphite fiber, wollastonite, non-swellable mica, swellable mica, graphite, talc, clay, mica, zeolite, bentonite, organic modified bentonite, organic modified montmorillonite, kaolin, fine powdered silica Examples thereof include plate-like and granular inorganic fillers such as acid, calcium carbonate, magnesium carbonate, barium sulfate, calcium oxide, aluminum oxide, titanium oxide, aluminum silicate, silicon oxide, gypsum, nobaculite, dosonite and clay. Among these inorganic fillers, carbon fiber, glass fiber, wollastonite, mica, talc and kaolin are preferable. The aspect ratio of the fibrous filler is preferably 5 or more, more preferably 10 or more, and further preferably 20 or more.

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

  The content of the inorganic filler is preferably 1 to 100 parts by weight and more preferably 5 to 50 parts by weight with respect to 100 parts by weight of the polylactic acid resin. The content of the inorganic filler means the total content of the layered double hydroxide-containing composition and other inorganic fillers.

(Organic filler)
In addition to the above, the polylactic acid resin composition of the present invention preferably contains an organic filler from the viewpoint of further improving physical properties such as strength.

  As the organic filler, a chip-like, fiber-like, plate-like or powder-like one usually used for reinforcing thermoplastic resins can be used. Specific examples include rice husks, wood chips, okara, waste paper pulverized materials, chip-shaped materials such as clothing pulverized materials, cotton fibers, hemp fibers, bamboo fibers, wood fibers, kenaf fibers, jute fibers, banana fibers, coconut fibers. Pulp fiber or cellulose fiber processed from these plant fibers and animal fibers such as silk, wool, Angola, cashmere, camel, etc., fibrous materials such as aramid fiber, polyarylate fiber, PBO fiber, pulp powder , Paper powder, wood powder, bamboo powder, cellulose powder, rice husk powder, fruit husk powder, chitin powder, chitosan powder, protein, starch, and the like. From the viewpoint of improving moldability, paper powder, Powdered wood powder, bamboo powder, cellulose powder, kenaf powder, rice husk powder, fruit shell powder, chitin powder, chitosan powder, protein powder, starch, etc. Preferably, paper powder, wood powder, bamboo powder, cellulose powder, kenaf powder is more preferable. From the viewpoint of improving toughness, it is preferable to use a powdery organic filler obtained by amorphizing cellulose using a vibrating rod mill, a bead mill or the like. Among organic fillers, cellulose is preferable from the viewpoint of achieving both strength and flexibility, and cellulose having a crystallinity of less than 50% described in WO2010 / 010961 is more preferable.

  The content of the organic filler is preferably 1 to 100 parts by weight and more preferably 5 to 50 parts by weight with respect to 100 parts by weight of the polylactic acid resin.

(Other resins and additives)
The polylactic acid resin composition of the present invention may contain other resins from the viewpoint of improving physical properties such as strength, flexibility, heat resistance, and durability of the molded body made of the polylactic acid resin composition. Specific examples of other resins include polyethylene, polypropylene, polystyrene, ABS resin, AS resin, acrylic resin, polyamide, polyphenylene sulfide, polyether ether ketone, polyester, polyacetal, polysulfone, polyphenylene oxide, polyimide, polyetherimide, Or thermoplastic resins such as ethylene / glycidyl methacrylate copolymers, polyester elastomers, polyamide elastomers, soft thermoplastic resins such as ethylene / propylene terpolymers, ethylene / butene-1 copolymers, phenol resins, melamine resins, unsaturated Examples thereof include thermosetting resins such as polyester resins, silicone resins, and epoxy resins.

  The polylactic acid resin composition of the present invention can further contain a flame retardant from the viewpoint of improving physical properties such as strength, flexibility, heat resistance, and durability of the molded body made of the polylactic acid resin composition. . Specific examples of the flame retardant include halogenated compounds containing bromine or chlorine such as tetrabromobisphenol-A-epoxy oligomer, tetrabromobisphenol-A-carbonate oligomer, brominated epoxy resin, antimony trioxide, boric acid, etc. Inorganic flame retardants such as zinc, silicone flame retardants such as silicone resin and silicone oil, inorganic hydroxides such as aluminum hydroxide and magnesium hydroxide (surface treatment with silane coupling agent, especially isocyanate silane from the viewpoint of physical properties And phosphorous compounds such as triaryl isopropylates, condensed phosphates, melamine polyphosphates, piperazine polyphosphates and phosphazene compounds, and nitrogen-containing compounds such as melamine cyanurate. From the viewpoint of improving safety, an inorganic hydroxide or a phosphorus compound is preferable, and from the viewpoint of improving physical properties, the combined use of an inorganic hydroxide and a phosphorus compound is preferable. The content of the flame retardant is preferably 10 to 60 parts by weight and more preferably 15 to 50 parts by weight with respect to 100 parts by weight of the polylactic acid resin.

  The polylactic acid resin composition of the present invention may contain a core-shell type rubber from the viewpoint of improving physical properties such as impact resistance and toughness of a molded article made of the polylactic acid resin composition. Specific examples include (core; silicone / acrylic polymer, shell; methyl methacrylate polymer), (core; silicone / acrylic polymer, shell; methyl methacrylate / glycidyl methacrylate polymer), (core; butanediene / Styrene polymer, shell; methyl methacrylate polymer), (core; acrylic polymer, shell; methyl methacrylate polymer) and the like. From the viewpoint of improving transparency, commercially available products are preferably made by Mitsubishi Rayon Co., Ltd .; Metabrene S-2006, S-2100, S-2200, Rohm and Haas Co., Ltd .; Paraloid BPM-500. The content of the core-shell type rubber is preferably 2 to 30 parts by weight and more preferably 3 to 20 parts by weight with respect to 100 parts by weight of the polylactic acid resin.

  The polylactic acid resin composition of the present invention is a conventional additive such as a hindered phenol or a phosphite-based antioxidant, or an aliphatic amide as long as the components other than the above are not impaired. UV absorbers (benzophenone compounds, benzotriazole compounds, aromatic benzoate compounds, oxalic acid anilide compounds, cyanoacrylate compounds, etc.) And hindered amine compounds), heat stabilizers (hindered phenol compounds, phosphite compounds, thioether compounds), antistatic agents, antifogging agents, light stabilizers, foaming agents, release agents, dyes and pigments One or more of colorants, fungicides, antibacterial agents and the like can be further contained.

(Production method of polylactic acid resin composition)
The polylactic acid resin composition of the present invention can be prepared without particular limitation as long as it contains a polylactic acid resin and a refined layered double hydroxide-containing composition. The layered double hydroxide-containing composition and, if necessary, the raw material for the polylactic acid resin composition containing various additives, known as a closed kneader, a single or twin screw extruder, an open roll type kneader, etc. It can be prepared by melt-kneading using a kneader. The raw materials can be mixed in advance using a Henschel mixer, a super mixer, etc., and then subjected to melt kneading.

  The melt kneading temperature is preferably from 160 to 250 ° C, more preferably from 165 to 230 ° C, and even more preferably from 170 to 210 ° C, from the viewpoint of improving the moldability and deterioration prevention of the 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 15 to 900 seconds.

The melt kneader is preferably an apparatus having a shear rate of 10 to 1000 (1 / s), more preferably 20 to 500 (1 / s), from the viewpoint of dispersibility of the layered double hydroxide. . In the present specification, the shear rate of the melt kneader is a value obtained from the following equation, and the tip clearance means a gap between the outer periphery of the rotor and the inner wall surface of the chamber.
Shear rate (1 / s) = screw speed (r / s) × 2π × screw radius / chip clearance

  Thus, the polylactic acid resin composition of the present invention is obtained. Therefore, this invention also provides the manufacturing method of the polylactic acid resin composition of this invention.

As a suitable production method of the polylactic acid resin composition of the present invention,
Step (1): A layered double hydroxide organized by an organic agent selected from the group consisting of an alkyl phosphate ester and a salt thereof is refined in the presence of a plasticizer, and the refined layered double hydroxide is obtained. Step of obtaining a product-containing composition, and step (2): melting the refined layered double hydroxide-containing composition obtained in step (1) and a raw material for a polylactic acid resin composition containing a polylactic acid resin Examples thereof include a method including a kneading step.

  In the step (1), a layered double hydroxide organized by an organic agent selected from the group consisting of an alkyl phosphate ester and a salt thereof is refined in the presence of a plasticizer, and the refined layered double water is obtained. An oxide-containing composition is obtained. Preferably, a method of pulverizing a mixture of a layered double hydroxide and a plasticizer that has been organized by the organic agent is mentioned. As the organic agent, the layered double hydroxide and the plasticizer, those described above are used. Moreover, there is no limitation in particular also about the refinement | miniaturization method, The method employ | adopted when preparing the layered double hydroxide containing composition contained in the polylactic acid resin composition of this invention, for example, wet grinding, is preferable.

  In step (2), the refined layered double hydroxide-containing composition obtained in step (1) and a raw material for polylactic acid resin composition containing polylactic acid resin are melt-kneaded. As a raw material used at a process (2), the thing similar to what is contained in the polylactic acid resin composition of this invention is mentioned. Further, there is no particular limitation on the melt-kneading method, and examples thereof include the method employed when preparing the polylactic acid resin composition of the present invention. For example, the polylactic acid resin and the refined layered double hydroxide-containing composition, Furthermore, if necessary, the raw material for the polylactic acid resin composition containing various additives is preferably 160 to 160, using a known kneader such as a closed kneader, a uniaxial or biaxial extruder, and an open roll kneader. A method of melt kneading at 250 ° C., more preferably 165 to 230 ° C., further preferably 170 to 210 ° C., preferably 10 to 1000 (1 / s), more preferably 20 to 500 (1 / s). Is mentioned. The raw materials may be subjected to melt kneading after being uniformly mixed in advance using a Henschel mixer, a super mixer, or the like.

  The polylactic acid resin composition of the present invention has good workability since it has both toughness and plasticity, and has an advantage that the plasticizer is hardly decomposed even when processed at a low temperature of 200 ° C. or less, for example, in a film or sheet. It can be used for various applications by press molding. Further, due to the high crystallization speed, it is possible to perform molding at a low mold temperature and in a short time in injection molding. Moreover, after processing once into a film or a sheet form, it can also be used for processing (secondary processing) such as thermoforming or stretching to obtain a thermoformed product or a stretched film.

  In addition, the polylactic acid resin composition of the present invention is, for example, a plasticizer as needed while mixing and melting the finely divided layered double hydroxide-containing composition and the polylactic acid resin using an extruder or the like. And a hydrolysis inhibitor and the like, and the resulting melt can be filled into a mold with an injection molding machine or the like and molded. Therefore, the present invention also provides a polylactic acid resin molded article obtained by molding the polylactic acid resin composition of the present invention and a method for producing the same.

The polylactic acid resin molded article of the present invention is, for example, after melt-kneading a raw material for a polylactic acid resin composition containing a layered double hydroxide-containing composition refined in the presence of the plasticizer and a poly milk resin, The obtained melt-kneaded product is obtained by filling a mold at 110 ° C. or lower and molding. As a suitable production method of the polylactic acid resin molded article of the present invention,
Step (A): a step of wet-pulverizing the layered double hydroxide in the presence of the plasticizer to obtain a refined layered double hydroxide-containing composition,
Step (B): a step of melt-kneading the refined layered double hydroxide-containing composition obtained in Step (A) and a raw material for a polylactic acid resin composition containing a polydairy resin, and Step (C) : A method including a step of filling the melt obtained in the step (B) into a mold of 110 ° C. or lower and molding the melt.

  In addition, after the melt kneading in the step (B), it may be molded after cooling to an amorphous state (that is, a condition that the crystallinity measured by the wide angle X-ray diffraction method is 1% or less) It may be molded immediately after cooling. From the viewpoint of improving the crystallization speed of the polylactic acid resin, a method in which after cooling and kneading, cooling and molding immediately, that is, after passing through step (B), cooling and immediately performing step (C) is preferable.

  As a specific example of the step (C), for example, a step of filling the polylactic acid resin composition of the present invention in a mold of 110 ° C. or less with an injection molding machine or the like and molding it can be mentioned. The mold temperature in the step (C) is preferably 110 ° C. or lower, more preferably 90 ° C. or lower, and further preferably 80 ° C. or lower, from the viewpoint of improving the crystallization speed and workability of the polylactic acid resin composition. Moreover, 30 degreeC or more is preferable, 40 degreeC or more is more preferable, and 60 degreeC or more is further more preferable. From this viewpoint, the mold temperature is preferably 30 to 110 ° C, more preferably 40 to 90 ° C, and further preferably 60 to 80 ° C. Since the polylactic acid resin composition of the present invention has an excellent crystallization rate and can be molded at a low temperature, a molded product having sufficient heat resistance can be obtained even at the mold temperature.

  The holding time in the mold in the step (C) is preferably 20 to 90 seconds, more preferably 20 to 80 seconds, from the viewpoint of improving the heat resistance and productivity of the molded article made of the polylactic acid resin composition, More preferably, it is 20 to 60 seconds. That is, since the polylactic acid resin composition obtained by the production method of the present invention has a high crystallization rate, a molded body comprising the polylactic acid resin composition having sufficient heat resistance even with the short holding time described above is obtained. It is done.

The heat resistance of the molded body made of the polylactic acid resin composition is proportional to the relative crystallinity. In the present specification, the relative crystallinity refers to the crystallinity represented by the following formula.
Relative crystallinity (%) = {(ΔHm−ΔHcc) / ΔHm × 100}
Specifically, the relative crystallinity was raised from 20 ° C. to 200 ° C. at a rate of temperature increase of 20 ° C./min using a DSC apparatus (Diamond DSC manufactured by PerkinElmer Co., Ltd.) at a rate of temperature increase of 20 ° C./min. After holding, the temperature was lowered from 200 ° C. to 20 ° C. at a temperature drop rate of −20 ° C./min, held at 20 ° C. for 1 minute, and then further increased from 20 ° C. to 200 ° C. at a temperature rising rate of 20 ° C./min as 2ndRUN. The absolute value ΔHcc of the cold crystallization enthalpy of the polylactic acid resin observed at 1st RUN and the crystal melting enthalpy ΔHm observed at 2nd RUN can be used.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.

(Particle size of layered double hydroxide)
The particle size (nm) of the layered double hydroxide is measured by using a laser diffraction / scattering type particle size distribution analyzer LA-920 (manufactured by HORIBA) in ethanol (manufactured by Kanto Chemical Co., Ltd., deer grade 1). Then, the layered double hydroxide particles or 0.05 g of the contained composition was dispersed and measured while stirring (stirring speed: level 4), and the median diameter was calculated with a refractive index of 1.10. In addition, when measuring the particle size of the layered double hydroxide before the refinement treatment, ultrasonic treatment is performed for 1 minute in order to disperse the particles in the measurement solvent, and the layered double hydroxide after the refinement treatment is processed. When measuring the particle size, only the stirring operation is performed.

Plasticizer Production Example 1 (Diester of succinic acid and triethylene glycol monomethyl ether)
A 3 L 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 monohydroxide, and nitrogen (500 mL / min) was added to the space. While blowing, 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 (KOH mg / g). After adding 27 g of adsorbent KYOWARD 500SH (manufactured by Kyowa Chemical Industry Co., Ltd.) to the reaction solution and stirring and filtering at 80 ° C. and 2.7 kPa for 45 minutes, triethylene at a liquid temperature of 115 to 200 ° C. and a pressure of 0.03 kPa. After distilling off the glycol monomethyl ether and cooling to 80 ° C., the residual liquid was filtered under reduced pressure to obtain a diester [(MeEO ₃ ) ₂ SA] of succinic acid and triethylene glycol monomethyl ether as a filtrate. The obtained diester had a weight average molecular weight of 410, a viscosity (23 ° C.) of 27 mPa · s, an acid value of 0.2 KOH mg / g, a saponification value of 274 KOH mg / g, a hydroxyl value of 1 KOH mg / g or less, and a hue APHA200.

Production Example 1 of Organically Treated Layered Double Hydroxide
In 2 L of distilled water, 1.2 g of acetic acid (manufactured by Kishida Chemical Co., Ltd.), 14.76 g of sodium acetate (manufactured by Sigma Aldrich Japan), 450 g of sodium chloride (manufactured by Wako Pure Chemical Industries, Ltd.) are dissolved at room temperature (25 ° C.). In order to add 3.6 g of layered double hydroxide (hydrotalcite DHT-6, manufactured by Kyowa Chemical Industry Co., Ltd.) and replace the carbonate ions between the layers with chloride ions, the mixture was stirred at room temperature (25 ° C.) for 20 hours ( The rotation speed was 200 rpm. After filtration, washing with water and drying, 1 g of the obtained powder was mixed with 1.52 g of monododecyl sodium phosphate (manufactured by Tokyo Chemical Industry Co., Ltd.) and 100 g of distilled water and stirred at 45 ° C. for 20 hours ( The rotation speed was 500 rpm. After filtration and washing with 100 g of distilled water and drying (at 80 ° C. for 12 hours), the obtained powder was further mixed with 1.52 g of sodium monododecyl sodium phosphate (Tokyo Chemical Industry Co., Ltd.) and 100 g of distilled water. The layered double hydroxide was organized by stirring (rotation speed: 500 rpm) at 45 ° C. for 20 hours. Filtration, washing with 100 g of distilled water, and drying (at 80 ° C. for 12 hours) gave organically modified layered double hydroxide 1.

Production example 2 of organically treated layered double hydroxide
Production Example except that 1 g of layered double hydroxide powder exchanged for chloride ions was mixed with 1.52 g of monododecyl sodium phosphate and 100 g of distilled water, and the mixture was stirred and mixed at 70 ° C. for 20 hours for organic formation. In the same manner as in Example 1, an organically modified layered double hydroxide 2 was obtained.

Production Examples 1 to 3 of the refined layered double hydroxide-containing composition
The layered double hydroxide and plasticizer shown in Table 1 were subjected to the pulverizer shown in Table 1 and pulverized for the time shown in Table 1. Table 1 shows the average particle size of the layered double hydroxide-containing composition before and after pulverization. In Production Example 3, the amount of layered double hydroxide and plasticizer shown in Table 1 were mixed by hand mixing.

In addition, the raw material and apparatus in Table 1 are as follows.
(Plasticizer)
Plasticizer 1: Diester of succinic acid and triethylene glycol monomethyl ether produced in Production Example 1 of plasticizer (pulverizer)
Crusher 1: Ultrasonic homogenizer (US-300T, manufactured by Nippon Seiki Seisakusho)

  From Table 1, it was confirmed that the layered double hydroxides of Production Examples 1 and 2 were refined by pulverizing the layered double hydroxide in the presence of a plasticizer.

Examples 1 and 2 and Comparative Example 1
In a melt kneader of the type shown in Table 2, 50 g (100 parts by weight) of the polylactic acid resin and the layered double hydroxide composition, crystal nucleating agent, and hydrolysis inhibitor shown in Table 2 were used. The mixture was melt-kneaded at a shear rate and a kneading temperature of 190 ° C. shown in Table 2 to obtain pellets of a polylactic acid resin composition. 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. In addition, the shear rate of the melt-kneader shown in Table 2 is a value obtained from the following formula.
Shear rate (1 / s) = screw speed (r / s) × 2π × screw radius / chip clearance

  Next, the pellets of Examples and Comparative Examples were melted at 190 ° C. using a heat press machine (manufactured by Toyo Seiki Seisakusho Co., Ltd., lab press), cooled to 20 ° C., and then heated again to 80 ° C. A sheet having a thickness of 0.4 mm was formed. A No. 2 test piece was prepared from the obtained molded body based on JIS 7127K, and the characteristics were examined according to the methods of Test Examples 1 to 3 below. The results are shown in Table 2.

In addition, the raw material and apparatus in Table 2 are as follows.
(Polylactic acid resin)
NW4032D: Polylactic acid resin (manufactured by Nature Works LLC, NatureWorks 4032D)
(Layered double hydroxide-containing composition)
Layered double hydroxide-containing composition (crystal nucleating agent) prepared in Production Examples 1 to 3 shown in Table 1
SLIPAX H: Ethylene bis 12-hydroxystearic acid amide (Nippon Kasei Co., Ltd.)
(Hydrolysis inhibitor)
Carbodilite LA-1: Polycarbodiimide (Nisshinbo Chemical Co., Ltd.)
(Melt kneader)
Kneading machine 1: Sealed kneader "Lab Plast Mill" (manufactured by Toyo Seiki Seisakusho)

Test Example 1 <Strength Evaluation>
About the obtained molded object, the tension test was done and the initial stage elastic modulus (GPa) was investigated. The tensile test was conducted according to JIS 7127K using a Tensilon universal testing machine (RTC-1210A) manufactured by Orientec. Higher values indicate better rigidity and higher strength.

Test Example 2 <Transparency Evaluation>
About the obtained molded object, the haze value was measured using the haze meter (HM-150 type | mold Murakami Color Research Laboratory company make), and this was made into the parameter | index of transparency. It shows that it is excellent in transparency, so that a numerical value is low.

Test Example 3 <Evaluation of flexibility>
The obtained molded body was subjected to a tensile test at a test temperature of 23 ° C. and a test speed of 50 mm / s to examine the stretch ratio at which it breaks [elongation at break (%)]. A Tensilon universal testing machine (RTC-1210A) manufactured by Orientec Co., Ltd. was used for the tensile test. It shows that it is excellent in flexibility, so that a numerical value is high.

  As is clear from the results in Table 2, the molded product of the polylactic acid resin composition of the present invention is more transparent than the resin composition having the same composition except that the layered double hydroxide is not refined. In addition, the tensile modulus and elongation at break are large, suggesting that both strength and flexibility can be achieved. In particular, Example 1 is superior to Comparative Example 1 in tensile modulus, haze, and elongation at break. This is presumably because the dispersibility is insufficient only by the organic layer formation, and the dispersibility in the resin is improved by the refinement by wet pulverization. This suggests that the scattering of visible light is suppressed, the haze value is lowered, and the layered double hydroxide acts as a reinforcing agent for the polylactic acid resin composition and is excellent in strength, flexibility and transparency. .

  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 (6)

  A polylactic acid resin composition comprising a polylactic acid resin and a refined layered double hydroxide-containing composition, wherein the refined layered double hydroxide-containing composition comprises an alkyl phosphate ester and A polylactic acid resin composition obtained by a method comprising a step of refining a layered double hydroxide organized by an organic agent selected from the group consisting of salts in the presence of a plasticizer.   The polylactic acid resin composition according to claim 1, wherein the plasticizer includes a carboxylic acid ester and / or a phosphoric acid ester.   In the step of refining the layered double hydroxide in the presence of the plasticizer, the weight ratio of the layered double hydroxide to the plasticizer (layered double hydroxide / plasticizer) is 1/99 to 40/60. The polylactic acid resin composition according to claim 1 or 2, wherein the polylactic acid resin composition is a step of use within a range for refinement.   The carboxylate ester and / or phosphate ester is an ester having two or more ester groups in the molecule, and the alcohol component constituting the ester averages an alkylene oxide having 2 to 3 carbon atoms per hydroxyl group. The polylactic acid resin composition according to claim 2 or 3, comprising 0.5 to 5 mol of added alcohol. The manufacturing method of the polylactic acid resin composition containing following process (1) and (2).
Step (1): A layered double hydroxide organized by an organic agent selected from the group consisting of an alkyl phosphate ester and a salt thereof is refined in the presence of a plasticizer, and the refined layered double hydroxide is obtained. Process step (2) for obtaining a product-containing composition: Melt kneading the refined layered double hydroxide-containing composition obtained in step (1) and a raw material for a polylactic acid resin composition containing a polylactic acid resin Process   The step (1) is a step of pulverizing a mixture of an organically modified layered double hydroxide and a plasticizer to obtain a refined layered double hydroxide-containing composition. A method for producing a lactic acid resin composition.