JP2014009267A - Injection-molded article formed of polylactic acid resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection-molded article formed of a polylactic acid resin composition excellent in strength and heat resistance, and a method for manufacturing the injection-molded article.SOLUTION: A molded article is obtained by injection-molding a molten and kneaded product of a polylactic acid resin composition containing a polylactic acid resin and a pulverized product of a laminar double hydroxide obtained by a method including a step of pulverizing the laminar double hydroxide in the presence of a plasticizer. A method for manufacturing an injection-molded article includes: a step (1) of obtaining a pulverized product of a laminar double hydroxide by pulverizing the laminar double hydroxide in the presence of a plasticizer; and a step (2) of preparing a molten and kneaded product of a polylactic acid resin composition by melting and kneading a raw material for the polylactic acid resin composition containing the pulverized product of the laminar double hydroxide obtained in the step (1) and a polylactic acid resin.

Description

  The present invention relates to an injection molded article made of a polylactic acid resin composition. More specifically, the present invention relates to an injection-molded body made of a 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 method for producing the injection-molded body.

  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.

  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 an anion-exchanged layered clay mineral to the resin has been 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.

JP 2003-171568 A JP-A-2005-47946

  In accordance with the prior art, blending a polylactic acid resin with a layered compound such as hydrotalcite or a compound obtained by subjecting the layered compound to organic treatment or the like to improve the mechanical strength of the polylactic acid resin composition Is possible. However, since the polylactic acid resin composition is expected to be used in a wider range of applications such as daily necessities, information home appliances and automobile supplies, for example, when it is injection molded, in addition to excellent mechanical strength Therefore, a polylactic acid resin composition capable of providing a molded product having excellent heat resistance is desired.

  An object of the present invention relates to an injection-molded article made of a polylactic acid resin composition having excellent strength and heat resistance, and a method for producing the injection-molded article.

The present invention relates to the following [1] to [2].
[1] Melting of a polylactic acid resin composition comprising a polylactic acid resin and a layered double hydroxide refined product obtained by a method comprising a step of refining a layered double hydroxide in the presence of a plasticizer A molded product obtained by injection molding a kneaded product.
[2] A method for producing an injection-molded article comprising the following steps (1) to (3).
Step (1): A layered double hydroxide obtained in step (1) is obtained by refining a layered double hydroxide in the presence of a plasticizer to obtain a refined layered double hydroxide. Step (3) for preparing a melt-kneaded product of a polylactic acid resin composition by melt-kneading a raw material for a polylactic acid resin composition containing a refined product and a polylactic acid resin of the polylactic acid resin composition obtained in step (2) A process of injection molding a melt-kneaded product of a lactic acid resin composition into a mold

  The injection-molded article comprising the polylactic acid resin composition of the present invention has an excellent effect that it is excellent in strength and heat resistance.

  The injection-molded article of the present invention comprises a polylactic acid resin composition containing a polylactic acid resin and a layered double hydroxide, and the layered double hydroxide is refined by a specific method. It has a special feature. In addition, in this specification, the refined layered double hydroxide may be referred to as a refined layered double hydroxide or a refined layered double hydroxide.

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, in addition to high strength, a polylactic acid resin excellent in heat resistance is required. Thus, as a result of investigations by the present inventors, it has been found that a resin containing a layered double hydroxide refined in the presence of a plasticizer is excellent in heat resistance while being excellent in strength. The detailed reason is unknown, but by making the material fine in the presence of the plasticizer, the plasticizer adheres to the surface of the obtained layered double hydroxide. Things are thought to interact in some way. Therefore, it is presumed that the fine layered double hydroxide is finely dispersed in the polylactic acid resin without re-aggregation in the melt-kneading. For this reason, it is considered that the contact area between the polylactic acid resin and the layered double hydroxide increases, and the strength is remarkably improved. Further, it is considered that the plasticizer is inserted between the layered double hydroxides to increase the interlayer distance, and as a result, the contact area between the layered double hydroxide and the polylactic acid resin is increased. Also, by melt-kneading with polylactic acid resin, the polylactic acid resin is inserted between the layers of the layered double hydroxide, so that the contact area is further increased. As a result, the layered double hydroxide is highly dispersed. It is considered that a molded article made of a polylactic acid resin composition having excellent strength and heat resistance can be obtained. In this specification, “strength” means a characteristic evaluated by “bending strength” described later, and “heat resistance” means a characteristic evaluated by “thermal deformation temperature” described later.

[Polylactic acid resin composition]
[Polylactic acid resin]
Examples of the polylactic acid resin include commercially available polylactic acid resins (for example, products manufactured by Nature Works: trade name: Nature Works PLA / NW3001D, NW4032D, manufactured by Toyota Motor Corporation: trade names: Ecoplastic U'z S-09, S-12 , S-17, etc.), and polylactic acid resin synthesized from lactic acid or lactide. From the viewpoint of improving strength and heat resistance, a polylactic acid resin having an optical purity of 90% or more is preferable. For example, a polylactic acid resin (NW4032D or the like) manufactured by Nature Works with a relatively high molecular weight and high optical purity is preferable.

  In the present invention, as the polylactic acid resin, stereocomplex polylactic acid may be used from the viewpoints of coexistence of strength and flexibility of the polylactic acid resin composition, and improvement of heat resistance and mechanical strength.

  Stereocomplex polylactic acid is a polylactic acid resin composed of two types of polylactic acid obtained using lactic acid components mainly composed of different isomers. One of the polylactic acids constituting the stereocomplex polylactic acid [hereinafter referred to as polylactic acid] Lactic 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. In addition, as other components other than L-form and D-form, dicarboxylic acid, polyhydric alcohol, hydroxycarboxylic acid, lactone, etc. having a functional group capable of forming two or more ester bonds are exemplified, and unreacted Polyester, polyether, polycarbonate or the like having two or more of the functional groups in the molecule may be used.

  In the stereocomplex polylactic acid, the mass 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.

  Moreover, the polylactic acid resin in this invention may be contained as a polymer alloy by the blend of non-biodegradable resin other than polylactic acid resin, non-biodegradable resins, such as a polypropylene, and polylactic acid resin.

  Although content of polylactic acid resin is not specifically limited, In a polylactic acid resin composition, 50 mass% or more is preferable, 60 mass% or more is more preferable, 70 mass% or more is further more preferable.

[Refinement of layered double hydroxide]
The refined layered double hydroxide (refined layered double hydroxide) in the present invention is obtained by a method having a step of refining the layered double hydroxide in the presence of a plasticizer.

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, or iron, and is particularly limited as long as it 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, Manasite, 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 flexibility can be imparted to the resin composition. Therefore, the layered double hydroxide in the present invention is not only from the viewpoint of improving the refinement of the layered double hydroxide, but also from the viewpoint of improving the strength and heat resistance of the polylactic acid resin composition. It is preferable that it is organicized with an organic agent selected from the group consisting of acids, fatty acids, and salts thereof.

As the alkyl sulfate ester, the following formula (I):
^{_{R 1 - (O-CH 2}} -CH 2) m -O-SO 3 H (I)
The compound represented by
As the alkylsulfonic acid, the following formula (II):
^{_{R 2 - (O-CH 2}} -CH 2) m -SO 3 H (II)
The compound represented by
As the fatty acid, the following formula (VI):
R ⁹ —CO ₂ H (VI)
The compound represented by these is preferable.

^{R 1} in Formula (I), ^{R 2} in formula (II), and ^{R 9} in formula (VI), preferably 4 to 24 carbon atoms, more preferably include an alkyl group having 4 to 18 carbon atoms It may be linear or branched. Specific examples include a hexyl group, an octyl group, a decyl group, a dodecyl group, a myristyl group, a lauryl group, a stearyl group, and an octadecyl group. Among them, in addition to the viewpoint of improving the refinement of the layered double hydroxide From the viewpoint of improving the strength and heat resistance of the polylactic acid resin composition, a lauryl group and a stearyl group are preferred.

  M in the formula (I) and the formula (II) is 0 to 5 from the viewpoint of improving the strength and heat resistance of the polylactic acid resin composition in addition to improving the refinement of the layered double hydroxide. 0-3 are preferable.

  Specific examples of alkyl sulfates, alkyl sulfonic acids, fatty acids, and salts thereof include lauryl sulfate, sodium lauryl sulfate, potassium lauryl sulfate, polyoxyethylene lauryl sulfate, polyoxyethylene lauryl sodium sulfate, and polyoxyethylene lauryl. Potassium sulfate, myristyl sulfate, sodium myristyl sulfate, potassium myristyl sulfate, 1-dodecanesulfonic acid, sodium 1-dodecanesulfonate, potassium 1-dodecanesulfonate, 1-hexanesulfonic acid, sodium 1-hexanesulfonate, 1- Potassium hexanesulfonate, 1-octanesulfonic acid, sodium 1-octanesulfonate, potassium 1-octanesulfonate, 1-decanesulfonic acid, sodium 1-decanesulfonate , 1-decanesulfonic acid potassium, sodium stearate, among others, in addition to the viewpoint of improving the refinement of the layered double hydroxide, from the viewpoint of improving the strength and heat resistance of the polylactic acid resin composition, Sodium lauryl sulfate, potassium lauryl sulfate, polyoxyethylene sodium lauryl sulfate, polyoxyethylene potassium lauryl sulfate, sodium stearate are preferred, sodium lauryl sulfate, potassium lauryl sulfate, polyoxyethylene sodium lauryl sulfate, potassium polyoxyethylene lauryl sulfate More 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.

  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 heat resistance to the polylactic acid resin composition before treatment. From the viewpoint of the exchangeability of ions between the layered double hydroxide layers with respect to 100 parts by weight of the layered double hydroxide, 10 parts by weight or more is preferable, 30 parts by weight or more is more preferable, and 50 parts by weight or more is further provided. Preferably, from the viewpoint of the colorability of the refined layered double hydroxide, 300 parts by mass or less is preferable, 200 parts by mass or less is more preferable, and 150 parts by mass or less is more preferable. Moreover, 10-300 mass parts is preferable from a viewpoint of coexistence of the ion exchange property between layered double hydroxide layers, and the coloring property of refined layered double hydroxide, 30-200 mass parts is more preferable, 50-150 Part by mass is more preferable.

  The shape and average particle diameter of the layered double hydroxide subjected to the fine processing are not particularly limited as long as the fine processing can be performed, but is preferably 1 μm or more, more preferably 10 μm or more, and 100 μm or less. Is preferable, and 60 μm or less is more preferable. Moreover, 1-100 micrometers is preferable and 10-60 micrometers is more preferable. The interlayer distance is preferably 0.5 to 5.0 nm, more preferably 1.5 to 3.0 nm, and even more preferably 1.8 to 2.8 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, the layered double hydroxide is subjected to a step of refining in the presence of a plasticizer (hereinafter also referred to as a refining step).

  There is no limitation in particular as a plasticizer used at a refinement | miniaturization process, A plasticizer well-known in the said field | area can be used. Examples thereof include carboxylic acid esters, polyhydric alcohol esters, phosphate esters, polyalkylene glycols, lactic acid oligomer esters, rosin acid esters, and the like. Specifically, examples of the carboxylic acid ester include phthalic acid esters such as di-n-octyl phthalate, di-2-ethylhexyl phthalate, dibenzyl phthalate, and diisodecyl phthalate, isophthalic acid esters such as dioctyl isophthalate, and di-n- Adipic acid esters such as butyl adipate and dioctyl adipate, maleic acid esters such as di-n-butyl malate, citric acid esters such as acetyltri-n-butyl citrate, itaconic acid esters such as monobutyl itaconate, butyl oleate, etc. Oleic acid esters are exemplified. Examples of the polyhydric alcohol ester include diacetyl caprylic acid monoglyceride, diacetyl lauric acid monoglyceride, ricinoleic acid monoglyceride, decaglycerin monoelate and the like. Examples of the phosphate ester include tricresyl phosphate. Examples of polyalkylene glycols include polyethylene glycol (hereinafter PEG), PEG diacetate, polypropylene glycol (hereinafter PPG), PEG-PPG-PEG block polymer, PPG-PEG-PPG block polymer, and the like. Examples of the lactic acid oligomer esters include triethylene glycol monomethyl ether lactic acid oligomer esters. Examples of rosin acid esters include diethylene glycol rosin ester acetate. 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 double hydroxide by the refinement, Acid esters and / or phosphate esters are preferred. In addition, from the viewpoint of further improving both the strength and flexibility of the polylactic acid resin composition, the molecule has two or more ester groups, and at least one alcohol component constituting the ester per hydroxyl group It is preferable to contain an ester compound (hereinafter referred to as “AO-added ester compound”) obtained by adding an average of 0.5 to 5 moles of an alkylene oxide having 2 to 3 carbon atoms.

The carboxylic acid ester is not particularly limited as long as it is an ester compound of carboxylic acid, and other than the carboxylic acid ester, polycarboxylic acid ester such as succinic acid ester such as dioctyl succinate is exemplified. From the viewpoint of improving the flexibility of the resin composition and improving the miniaturization of the layered double hydroxide, an oligoester represented by the following formula (III) is preferable.
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. In the present specification, the average degree of polymerization can be calculated according to the method described in Examples described later.

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 following is more preferable. In the present specification, the acid value and hydroxyl value of the plasticizer can be calculated according to the methods described in the examples below.

  The average molecular weight of the oligoester represented by the formula (III) is preferably from 500 to 1500, more preferably from 500 to 1400, still more preferably from 500 to 1300, more preferably from the viewpoint of improving volatility resistance and plasticizing efficiency. Preferably it is 500-1200. In the present specification, the number average molecular weight of the oligoester plasticizer can be calculated according to the method described in Examples described later.

  The oligoester represented by the formula (III) has an alkyl esterification rate with respect to two molecular ends (from the viewpoint of improving the compatibility with the polylactic acid resin and developing the plasticizing effect and improving the plasticizing efficiency ( The terminal alkyl esterification ratio) is preferably 85% or more, more preferably 90% or more.

  The ether group value of the oligoester represented by the formula (III) is preferably 0 to 8 mmol / g, more preferably 0 to 6 mmol / g, and more preferably 1 to 6 mmol / g from the viewpoint of improving the compatibility with the polylactic acid resin. g is more preferable, and 1 to 5 mmol / g is more preferable.

  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.

  The compound represented by the formula (III) may be a commercially available product or may be synthesized according to a known production method, for example, produced according to a method disclosed in JP2012-62467A. be able to.

  As the phosphoric acid ester, the viewpoint of improving the miniaturization of the layered double hydroxide, and the flexibility of the polylactic acid resin composition is improved by adhering the plasticizer to the layered double hydroxide through the miniaturization. From the viewpoint of 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 double hydroxide by miniaturization, the number is preferably 5 to 10, more preferably 6 to It is a number that satisfies 9.

  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 double hydroxide through the refinement, Tris ( Ethoxyethoxyethyl) phosphate is preferred.

  The compound represented by the formula (IV) may be a commercially available product or may be synthesized according to a known production method, for example, produced according to a method as disclosed in JP-A-10-17581. be able to.

  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. Examples include ester compounds in which at least one alcohol component is a compound obtained by adding an average of 0.5 to 5 moles of alkylene oxide having 2 to 3 carbon atoms per hydroxyl group. Among these, compounds obtained by condensation polymerization of alcohol components such as alkylene oxide adducts of alcohols having an average of 0.5 to 5 moles of an alkyleneoxy group having 2 or 3 carbon atoms per hydroxyl group and a known carboxylic acid component Is preferred.

  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.

  Specific examples of the AO addition ester compound include saturated dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, 2-methylsuccinic acid, and adipic acid, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and triethylene glycol monomethyl ether. And diesters of polyethylene glycol monoalkyl ethers such as triethylene glycol monoethyl ether and tetraethylene glycol monomethyl ether, and diesters of acetic acid and glycerin or ethylene glycol ethylene oxide adducts. Among them, from the viewpoints of compatibility of strength and flexibility of the polylactic acid resin composition, moldability, plasticity, and improvement of bleed resistance of the plasticizer, an ester compound of succinic acid or adipic acid and polyethylene glycol monomethyl ether, And at least one selected from the group consisting of an ester compound of acetic acid and glycerin or an ethylene oxide adduct of ethylene glycol is preferred, and an ester compound of succinic acid or adipic acid and polyethylene glycol monomethyl ether is more preferred.

  Further, 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 (mass ratio: 1/1) Is preferred.

  The AO addition ester compound improves the flexibility of the polylactic acid resin composition by improving the refinement of the layered double hydroxide and by adhering the plasticizer to the layered double hydroxide through the refinement. From the viewpoint of making it, it is preferable that all acid groups are complete esters obtained by esterification.

The average molecular weight of the AO-added ester compound is preferably 250 to 700 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. Preferably it is 300-600, More preferably, it is 350-550, More preferably, it is 400-500. In this specification, the average molecular weight of the AO-added ester plasticizer can be obtained by calculating the saponification value by the method described in JIS K0070 and calculating from the following formula.
Average molecular weight = 56108 × (number of ester groups in one molecule) / saponification value

  These carboxylic acid ester, phosphoric acid ester, and AO addition ester compound may be used alone or in combination, and the carboxylic acid ester, phosphoric acid ester, and AO addition ester are within the range not impairing the effects of the present invention. In addition to the compounds, other esters can be used in combination. The content of the carboxylic acid ester, the phosphoric acid ester, and the AO addition ester compound is not particularly limited, but from the viewpoint of improving both the strength and flexibility of the polylactic acid resin composition and the bleed resistance of the plasticizer. In the plasticizer, 60% by mass or more is preferable, 70% by mass or more is more preferable, 90% by mass or more is further preferable, and substantially 100% by mass is even more preferable.

  The mass ratio of the layered double hydroxide and the plasticizer in the refinement step (layered double hydroxide / plasticizer) 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 or more is preferable, 4/96 or more is more preferable, 6/94 or more is more preferable, 8/92 or more is even more preferable, and the fine layered double hydroxide is fine. From the viewpoint of dispersion, 50/50 or less is preferable, and 40/60 or less is more preferable. Moreover, from the viewpoint of heat resistance and mechanical strength of the polylactic acid resin composition, 1/99 to 50/50 is preferable, 4/96 to 50/50 is more preferable, and 6/94 to 50/50 is further preferable. 8/92 to 40/60 is even more preferable. When the mass ratio of the layered double hydroxide and the plasticizer is within the above range, the layered double hydroxide is refined without agglomeration, and the plasticizer adheres to the surface of the layered double hydroxide. An oxide refinement can be obtained. In addition, the mass of a plasticizer here means the total mass of the used plasticizer, when using a plurality of plasticizers.

  The method for miniaturization is not particularly limited, but 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. From the viewpoint of improving pulverization efficiency, a medium pulverizer is preferable. 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 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, it is preferably 0.02 to 5 hr, more preferably Is 0.05-2 hr, more preferably 0.10-1 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 mode of wet pulverization, for example, a mode in which wet pulverization is performed by adding the layered double hydroxide and the plasticizer independently or simultaneously to a medium-type pulverizer can be mentioned.

  Thus, a refined layered double hydroxide is obtained. In the present invention, the obtained refined layered double hydroxide may be subjected to a cleaning process, a dilution process, a concentration process and the like according to a known method after the refinement process.

  The average particle size of the fine layered double hydroxide is preferably 0.1 μm or more from the viewpoint of heat resistance of the polylactic acid resin composition, preferably 20 μm or less, and preferably 15 μm or less from the viewpoint of strength of the polylactic acid resin composition. Is more preferably 10 μm or less. Moreover, 0.1-20 micrometers is preferable from a viewpoint of coexistence of the heat resistance and intensity | strength of a polylactic acid resin composition, 0.1-15 micrometers is more preferable, and 0.1-10 micrometers is further more preferable. 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 heat resistance, and 2.0 to 4.0 nm. Is more preferable, and 3.0-4.0 nm is further more preferable.

  The content of the fine layered double hydroxide is preferably 1 part by mass or more with respect to 100 parts by mass of the polylactic acid resin from the viewpoint of improving the heat resistance of the molded product made of the polylactic acid resin composition obtained. More preferably 3 parts by mass or more, further preferably 5 parts by mass or more, and more preferably 30 parts by mass or less, more preferably 25 parts by mass or less, from the viewpoint of the strength of the polylactic acid resin composition. More preferred is less than or equal to parts by weight. Moreover, from a viewpoint of the bending strength and heat resistance of a polylactic acid resin composition, 1-30 mass parts is preferable, 2-25 mass parts is more preferable, 3-15 mass parts is more preferable, 5-15 mass parts is further preferable. In the present specification, “content” means “content or blending amount”.

  In addition, the content of the layered double hydroxide itself is 0.1 parts by mass or more from the viewpoint of improving the heat resistance of the molded product made of the polylactic acid resin composition obtained with respect to 100 parts by mass of the polylactic acid resin. Preferably, 0.2 parts by mass or more is more preferable, 0.5 parts by mass or more is more preferable, and from the viewpoint of the bending strength of the polylactic acid resin composition, 15 parts by mass or less is preferable, 10 parts by mass or less is more preferable, 8 The amount is more preferably equal to or less than part by mass, and further preferably equal to or less than 5 parts by mass. Moreover, from a viewpoint of coexistence of the bending strength and heat resistance of a polylactic acid resin composition, 0.1-15 mass parts is preferable, 0.2-10 mass parts is more preferable, 0.5-8 mass parts is further more preferable. . Further, the content of the plasticizer itself is preferably used so that the mass ratio of the layered double hydroxide and the plasticizer is within the above range, but the polylactic acid resin to be obtained with respect to 100 parts by mass of the polylactic acid resin. From the viewpoint of improving the flexibility and heat resistance of the molded article made of the composition, it is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, further preferably 8 parts by mass or more, and the bending strength of the polylactic acid resin composition. In view of the above, 30 parts by mass or less is preferable, 20 parts by mass or less is more preferable, and 15 parts by mass or less is more preferable. Moreover, from a viewpoint of coexistence of the bending strength and heat resistance of a polylactic acid resin composition, 3-30 mass parts is preferable, 5-20 mass parts is more preferable, and 8-15 mass parts is further more preferable.

  The polylactic acid resin composition in the present invention may further contain a crystal nucleating agent, a hydrolysis inhibitor and the like as appropriate in addition to the polylactic acid resin and the refined layered double hydroxide.

[Crystal nucleating agent]
As the crystal nucleating agent, at least one organic crystal nucleus selected from the group consisting of the following (a) to (d) from the viewpoint of improving the crystallization speed of the polylactic acid resin composition and improving the impact resistance. An agent 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)]

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

  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.

  From the viewpoint of promoting crystallization, the content of the crystal nucleating agent is preferably 0.1 to 5 parts by mass, more preferably 0.5 to 3 parts by mass with respect to 100 parts by mass of the polylactic acid resin, and 0.7 -3 mass parts is further more preferable, and 0.7-2 mass is still more preferable.

[Hydrolysis inhibitor]
Examples of the hydrolysis inhibitor include carbodiimide compounds such as polycarbodiimide compounds and monocarbodiimide compounds. From the viewpoint of improving the durability and impact resistance of the polylactic acid resin composition, the polycarbodiimide compound is preferable, and the polylactic acid resin composition From the viewpoint of improving the durability and moldability (fluidity), 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 a 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 alone or in combination of two or more in order to satisfy the durability, impact resistance, and moldability of a molded product made of a 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 mass with respect to 100 parts by mass of the polylactic acid resin from the viewpoint of improving the heat resistance and moldability of the molded product made of the polylactic acid resin composition. 0.10-2 mass parts is more preferable.

  The polylactic acid resin composition in the present invention is a filler (inorganic filler, organic filler), a flame retardant, an antioxidant, a hydrocarbon wax, or an anionic surfactant as components other than those described above. A lubricant, an ultraviolet absorber, an antistatic agent, an antifogging agent, a light stabilizer, a pigment, an antifungal agent, an antibacterial agent, a foaming agent, and the like can be contained as long as the effects of the present invention are not impaired. Moreover, a plasticizer (additional plasticizer) can be further contained separately from those used for the refinement of the layered double hydroxide. The additional plasticizer and the plasticizer used for refining the layered double hydroxide may be the same or different. In addition, other polymer materials and other resin compositions can be added within a range that does not impair the effects of the present invention.

  The melt-kneaded product of the polylactic acid resin composition in the present invention can be prepared without any particular limitation as long as it contains a polylactic acid resin and a refined layered double hydroxide, such as a polylactic acid resin and a refined layered layer. Prepared by melt-kneading a raw material containing double hydroxide and, if necessary, various components using a known kneader such as a closed kneader, a single or twin screw extruder, an open roll kneader, etc. Can do. After the melt-kneading, the melt-kneaded product may be dried or cooled according to a known method. In addition, 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 order to promote the plasticity of the polylactic acid resin during melt kneading, it may be melt-mixed in the presence of a supercritical gas.

  From the viewpoint of improving the moldability and prevention of deterioration of the polylactic acid resin composition, the melt kneading temperature is preferably 160 ° C or higher, more preferably 165 ° C or higher, further preferably 170 ° C or higher, and preferably 250 ° C or lower. More preferably, it is 230 degrees C or less, More preferably, it is 210 degrees C or less. Moreover, Preferably it is 160-250 degreeC, More preferably, it is 165-230 degreeC, More preferably, it is 170-210 degreeC. 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 glass transition temperature (Tg) of the obtained melt-kneaded product is preferably 30 ° C. or higher, more preferably 35 ° C. or higher, because the plasticizer used for refining the layered double hydroxide works effectively. And preferably it is 60 degrees C or less, More preferably, it is 55 degrees C or less. Moreover, Preferably it is 30-60 degreeC, More preferably, it is 30-55 degreeC, More preferably, it is 35-55 degreeC.

  The cold crystallization temperature (Tc) of the melt-kneaded product is preferably 50 ° C. or higher, more preferably 60 ° C. or higher, because the plasticizer used for refining the layered double hydroxide works effectively. Preferably it is 110 degrees C or less, More preferably, it is 100 degrees C or less, More preferably, it is 90 degrees C or less. Moreover, Preferably it is 50-110 degreeC, More preferably, it is 50-100 degreeC, More preferably, it is 60-90 degreeC.

  The melting point (Tm) of the melt-kneaded product is preferably 130 ° C. or higher, more preferably 140 ° C. or higher, more preferably 150 ° C. or higher, and preferably 210 ° C. or lower, from the viewpoint of heat resistance and workability of the molded product. More preferably, it is 200 degrees C or less, More preferably, it is 180 degrees C or less. Moreover, Preferably it is 130-210 degreeC, More preferably, it is 140-200 degreeC, More preferably, it is 150-180 degreeC.

[Injection molded body]
The melt-kneaded product thus obtained has good workability and excellent heat resistance, so it can be used under high-temperature conditions, and can be suitably used for various uses, especially for information and home appliances. The molten kneaded product is molded into an injection-molded body.

  The injection-molded body is not particularly limited as long as the melt-kneaded product of the polylactic acid resin composition is injection-molded. For example, the melt-kneaded product is filled in an injection molding machine and injected into a mold. It is obtained by molding.

  As the injection molding, a known injection molding machine can be used. 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 said polylactic acid resin composition may be supplied to a cylinder and melt-kneaded as it is, it is preferable to fill what was previously melt-kneaded into an injection molding machine.

  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 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.

  The injection-molded article of the present invention is excellent in strength and heat resistance because the processability of the polylactic acid resin composition is good and the plasticizing effect by the plasticizer attached to the surface of the fine layered double hydroxide is excellent. Is.

  The present invention also provides a method for producing the injection molded article of the present invention.

  The production method is not particularly limited as long as it includes a step of injection molding a melt-kneaded product of the polylactic acid resin composition containing the polylactic acid resin and the refined layered double hydroxide. Depending on the type, a process can be added as appropriate.

Specifically, the aspect containing the following processes is mentioned.
Step (1): A layered double hydroxide obtained in step (1) is obtained by refining a layered double hydroxide in the presence of a plasticizer to obtain a refined layered double hydroxide. Step (3) for preparing a melt-kneaded product of a polylactic acid resin composition by melt-kneading a raw material for a polylactic acid resin composition containing a refined product and a polylactic acid resin of the polylactic acid resin composition obtained in step (2) A process of injection molding a melt-kneaded product of a lactic acid resin composition into a mold

  Step (1) is a step of obtaining a refined layered double hydroxide. Specifically, the mass ratio of the layered double hydroxide to the plasticizer (layered double hydroxide / plasticizer) in the presence of the plasticizer is preferably 1/99 to 50/50. More preferably 4/96 to 50/50, further preferably 6/94 to 50/50, more preferably 8/92 to 40/60, and pulverization, preferably wet pulverization. Can be As the layered double hydroxide and the plasticizer, those described above are used.

  Step (2) is a step of preparing a melt-kneaded product of the polylactic acid resin composition. Specifically, the raw material containing the fine layered double hydroxide obtained in step (1) and the polylactic acid resin is preferably 160 to 250 ° C, more preferably 165 to 230 ° C, and even more preferably 170. It can be prepared by melt-kneading at ˜210 ° C.

  Step (3) is a step of injection molding a melt-kneaded product of the polylactic acid resin composition. Specifically, the melt-kneaded product obtained in step (2) is preferably filled into an injection molding machine equipped with a cylinder heated to 180 to 220 ° C., more preferably 180 to 210 ° C., preferably 70 to It can be molded by injection into a mold at 120 ° C., more preferably 75 to 115 ° C., and still more preferably 80 to 110 ° C.

  The injection molded product of the present invention thus obtained has excellent strength and heat resistance because the layered double hydroxide finely adhered by attaching a plasticizer to the surface is excellently dispersed. It can be suitably used for equipment, housings, parts, etc. for daily necessities, stationery, cosmetics and the like.

  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. “Normal pressure” indicates 101.3 kPa, and “normal temperature” indicates 15 to 25 ° C.

[Average particle size of layered double hydroxide]
The average particle size (nm) of the layered double hydroxide was measured using a laser diffraction / scattering particle size distribution analyzer LA-920 (manufactured by HORIBA) and ethanol as a measurement solvent (manufactured by Kanto Chemical Co., Ltd., deer grade 1). Then, 0.05 g of the layered double hydroxide particles are dispersed while being stirred (stirring speed: level 4), and the median diameter is calculated with a refractive index of 1.12. 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.

[Acid value, hydroxyl value, and saponification value of plasticizer]
Acid value: Analysis is performed according to the test method of JIS K0070 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 K0070, 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 K0070, except that the temperature of the water bath is 95 ° C. and the heating time is 1 hour.

[Molecular weight of oligoester plasticizer]
Molecular weight: In this specification, the molecular weight of an oligoester plasticizer 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 b = saponification number × M ÷ (2 × 56110) −1

[Average molecular weight of AO addition ester plasticizer]
The average molecular weight of the AO-added ester plasticizer means a mass average molecular weight, and is calculated from the saponification value by the following formula.
Average molecular weight = 56108 × (number of ester groups in one molecule) / saponification value

Production Example 1 of Plasticizer (Diester Compound 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 mass average molecular weight of 410, a viscosity (23 ° C.) of 27 mPa · s, an acid value of 0.2 mgKOH / g, a saponification value of 274 mgKOH / g, a hydroxyl value of 1 mgKOH / g or less, and a hue of APHA200.

Plasticizer Production Example 2 (Tris (ethoxyethoxyethyl) phosphate)
To a 1 liter four-necked flask, 600 g (4.47 mol) of diethylene glycol monoethyl ether was added and stirred under reduced pressure (20 kPa) while blowing dry nitrogen gas at a flow rate of 50 mL per minute. Next, 114 g (0.745 mol) of phosphorus oxychloride was slowly added dropwise while maintaining the reaction system at room temperature (15 ° C.), and then aged at 40 to 60 ° C. for 5 hours. Thereafter, 149 g of a 16% by mass aqueous sodium hydroxide solution was added for neutralization, and excess unreacted diethylene glycol monoethyl ether was distilled off under reduced pressure at a temperature of 70 to 120 ° C., and further contacted with steam to obtain crude phosphoric acid. 367 g of triester was obtained. Further, 300 g of a 16% by mass aqueous sodium chloride solution was added to the crude phosphoric acid triester for washing. Thereafter, the phase-separated lower phase was drained, and the remaining upper phase was dehydrated under reduced pressure at 75 ° C., and the solid content was further removed by filtration to obtain 266 g of the desired tris (ethoxyethoxyethyl) phosphate ( Yield 80%). This tris (ethoxyethoxyethyl) phosphate is a colorless and transparent uniform liquid. As a result of the chloro ion analysis, the chloro ion content was 10 mg / kg or less.

Plasticizer Production Example 3 (Diester compound of glutaric acid and diethylene glycol monomethyl ether)
A 1 L flask equipped with a stirrer, thermometer, dehydration tube and reflux tube was charged with 118 g of glutaric acid, 361 g of diethylene glycol monomethyl ether, 250 mL of toluene, and 2.0 g of paratoluenesulfonic acid monohydroxide, and reacted at 120 ° C. for 9 hours. . After cooling, 350 mL of ethyl acetate was added, washed with an aqueous sodium carbonate solution and further with a saturated aqueous sodium chloride solution, and dried over anhydrous sodium sulfate. Ethyl acetate and toluene were removed by an evaporator, and low-boiling components were distilled off under reduced pressure to obtain a diester of glutaric acid and diethylene glycol monomethyl ether. The obtained diester had a mass average molecular weight of 324, an acid value of 0.2 KOH mg / g, a saponification value of 346 KOH mg / g, and a hydroxyl value of 1 KOH mg / g or less.

Production Example 4 of plasticizer (oligoester compound of dimethyl succinate and diethylene glycol)
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 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 succinate to obtain a room temperature yellow liquid (oligoester of dimethyl succinate and diethylene glycol). In addition, the usage-amount of the catalyst was 0.94 mol with respect to 100 mol of dicarboxylic acid ester. The resulting oligoester had a number average molecular weight of 530, an acid value of 0.37 mgKOH / g, a saponification value of 643 mgKOH / g, and a hydroxyl value of 0.6 mgKOH / g.

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 and drying, 1 g of the obtained powder was mixed with 1.33 g of sodium lauryl sulfate (manufactured by Wako Pure Chemical Industries) and 100 g of distilled water, and stirred at room temperature (25 ° C.) for 20 hours (rotation speed: 200 rpm) ) To make the layered double hydroxide organic by ion exchange. The resulting powder was washed with 250 g of distilled water in three portions (first time; 80 g, second time; 80 g, third time; 90 g), and organically modified layered double hydroxide 1 was obtained.

Production example 2 of organically treated layered double hydroxide
Layered double hydroxide organics in the same manner as in Production Example 1, except that 1.33 g of sodium lauryl sulfate (manufactured by Wako Pure Chemical Industries, Ltd.) was changed to 1.33 g of sodium polyoxyethylene lauryl sulfate (manufactured by Kao). The organically modified layered double hydroxide 2 was obtained.

Production Example 3 of Organically Treated Layered Double Hydroxide
Layered double hydroxide organics in the same manner as in Production Example 1, except that 1.33 g of sodium lauryl sulfate (manufactured by Wako Pure Chemical Industries, Ltd.) was changed to 1.33 g of sodium stearate (manufactured by Wako Pure Chemical Industries, Ltd.) The organic layered double hydroxide 3 was obtained.

Production Examples 1-14 of Fine Layered Double Hydroxide
The layered double hydroxides and plasticizers shown in Tables 1 and 2 were subjected to ultrasonic homogenizer (US-300T, manufactured by Nippon Seiki Seisakusho Co., Ltd.) and pulverized for the time shown in Tables 1 and 2. In Production Examples 12 and 13, the layered double hydroxide and the plasticizer were only mixed by manual stirring without being pulverized. In Production Example 14, only the layered double hydroxide was subjected to ultracentrifugation (ZM200, manufactured by Retsch) and pulverized. Tables 1 and 2 show the average particle size of the layered double hydroxide before and after the treatment.

In addition, the raw material in Tables 1-2 is as follows.
(Plasticizer)
Plasticizer 1: Diester of succinic acid and triethylene glycol monomethyl ether produced in Production Example 1 of plasticizer, mass average molecular weight 410
Plasticizer 2: Diester of adipic acid and diethylene glycol monomethyl ether / benzyl alcohol = 1/1 mixture (manufactured by Daihachi Chemical Industry Co., Ltd.), mass average molecular weight 338
Plasticizer 3: Tris (ethoxyethoxyethyl) phosphate produced in Production Example 2 of plasticizer Plasticizer 4: Diester compound of glutaric acid and diethylene glycol monomethyl ether produced in Production Example 3 of plasticizer, mass average molecular weight 324
Plasticizer 5: Oligoester compound of dimethyl succinate and diethylene glycol produced in Production Example 4 of plasticizer, number average molecular weight 530
Plasticizer 6: Dioctyl adipate (Wako Pure Chemical Industries, Reagent)

  From Tables 1 and 2, it was confirmed that the layered double hydroxides of Production Examples 1 to 11 were refined by wet pulverizing the layered double hydroxide in the presence of a plasticizer.

Examples 1-11 and Comparative Examples 1-3
Preparation of polylactic acid resin composition The composition raw materials shown in Tables 3 to 4 were melt-kneaded at a rotation speed of 100 r / min and a melt-kneading temperature of 190 ° C in a twin-screw extruder (Ikegai Iron Works, PCM-45). The strand was cut to obtain pellets of the 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 the polylactic acid resin composition of Comparative Example 3, the diester compound of succinic acid and triethylene glycol monomethyl ether produced in Production Example 1 of a plasticizer was separately added as a composition raw material in the amount shown in the table. In the same manner as in the polylactic acid resin composition of Example 1, pellets were prepared.

Preparation of injection molded body Next, the obtained pellets were injection molded using an injection molding machine (J110AD-180H manufactured by Nippon Steel Works) with a cylinder temperature of 200 ° C., and a mold temperature of 80 ° C. and a molding time of 60 seconds. A test piece [a prismatic test piece (125 mm × 12 mm × 6 mm)] was formed.

In addition, the raw material in Tables 3-4 is as follows.
<Polyester resin>
NW4032D: Polylactic acid resin, manufactured by Nature Works LLC, poly-L-lactic acid, NatureWorks 4032D
<Refined layered double hydroxide>
Production Examples 1 to 14: Refinement of layered double hydroxide prepared in Production Examples 1 to 14 described in Tables 1 to 2 <Plasticizer>
Plasticizer 1: Diester of succinic acid and triethylene glycol monomethyl ether produced in Production Example 1 of plasticizer <Crystal nucleating agent>
PPA-Zn: unsubstituted phenylphosphonic acid zinc salt, manufactured by Nissan Chemical Industries, Ltd. <Hydrolysis inhibitor>
Carbodilite LA-1: Polycarbodiimide, manufactured by Nisshinbo Chemical Co., Ltd.

  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 3-4.

Test Example 1 <Evaluation of heat resistance>
When a prismatic test piece (125 mm × 12 mm × 6 mm) is bent by 0.25 mm at a load of 1.80 MPa using a thermal deformation temperature measuring device (B-32, manufactured by Toyo Seiki Seisakusho) based on JIS K7191. The temperature was measured as the heat distortion temperature (° C.). A higher heat distortion temperature indicates better heat resistance.

Test Example 2 <Bending strength>
A prismatic test piece (125 mm × 12 mm × 6 mm) is bent using Tensilon (Orientec Co., Ltd., Tensilon Universal Testing Machine RTC-1210A) based on JIS K7203 with a crosshead speed set to 3 mm / min. A test was conducted to determine the bending strength. The higher the bending strength, the better the strength.

  As is apparent from the results of Tables 3 to 4, it is suggested that the molded bodies (Examples 1 to 11) of the polylactic acid resin composition of the present invention are excellent in heat resistance and have high bending strength and excellent strength. The

  Since the injection-molded article of the present invention is excellent in heat resistance and strength, it can be suitably used for various industrial uses such as information and home appliances, housings and parts such as daily necessities, stationery, and cosmetics.

Claims (7)

  A melt kneaded product of a polylactic acid resin composition comprising a polylactic acid resin and a layered double hydroxide refined product obtained by a method comprising a step of miniaturizing a layered double hydroxide in the presence of a plasticizer A molded product formed by injection molding.   The molded object of Claim 1 in which a plasticizer contains carboxylic acid ester and / or phosphate ester.   The molded article according to claim 1 or 2, wherein the layered double hydroxide is organically formed by an organic agent selected from the group consisting of alkyl sulfates, alkyl sulfonic acids, fatty acids, and salts thereof.   In the step of refining the layered double hydroxide in the presence of the plasticizer, the mass ratio of the layered double hydroxide to the plasticizer (layered double hydroxide / plasticizer) is 1/99 to 50/50. The molded body according to any one of claims 1 to 3, which 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 molded product according to any one of claims 2 to 4, comprising 0.5 to 5 mol of added alcohol. A method for producing an injection-molded article comprising the following steps (1) to (3).
Step (1): A layered double hydroxide obtained in step (1) is obtained by refining a layered double hydroxide in the presence of a plasticizer to obtain a refined layered double hydroxide. Step (3) for preparing a melt-kneaded product of a polylactic acid resin composition by melt-kneading a raw material for a polylactic acid resin composition containing a refined product and a polylactic acid resin of the polylactic acid resin composition obtained in step (2) A process of injection molding a melt-kneaded product of a lactic acid resin composition into a mold   The method for producing an injection-molded article according to claim 6, wherein the step (1) is a step of obtaining a refined layered double hydroxide by pulverizing a mixture of the layered double hydroxide and the plasticizer.