JP2007262319A - Foamable polylactic acid-based resin composition and molded article using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a foamable polylactic acid-based resin composition excellent in heat resistance by using a general purpose polylactic acid. <P>SOLUTION: The invention relates to the foamable polylactic acid-based resin composition comprising 100 pts.wt. of the polylactic acid and 0.01-10 pts.wt. of at least one of amide-based compound selected from a group comprising a linear amide compound or a linear hydrazide compound represented by general formula (I) and a specific cyclic amide compound or a cyclic hydrazide compound. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a foamed polylactic acid-based resin composition that achieves excellent heat resistance by adding a foaming agent and a specific compound to polylactic acid, and a molded article using the same.

  In recent years, biodegradable polymers that decompose in the natural environment and molded articles thereof have been demanded from the standpoint of protecting the natural environment, and research on natural degradable resins such as aliphatic polyester has been actively conducted. In particular, the lactic acid-based polymer has a sufficiently high melting point of 140 to 180 ° C. and is excellent in transparency, so that it is highly expected as a packaging material or a molded product utilizing the transparency.

  However, a container made by injection molding of a lactic acid-based polymer is excellent in rigidity, but has low heat resistance or low heat resistance and impact resistance. For example, in a packaging container, hot water or a microwave oven may be used. It is not possible and the application is limited.

  In order to impart heat resistance, it was necessary to cool the mold for a long time during the molding process, or to anneal the molded product after molding to highly crystallize. However, a long cooling process at the time of molding is not practical and crystallization tends to be insufficient, and post-crystallization by annealing has a drawback that the molded product tends to be deformed in the process of crystallizing.

  In order to overcome the above drawbacks, for example, Patent Document 1 discloses that the properties of hardness, strength, and temperature resistance can be changed by adding fillers of inorganic compounds such as silica and kaolinite to lactide thermoplastics. In Patent Document 2, lactate and benzoate are used as nucleating agents. In Patent Document 3, polyglycolic acid and its derivatives are added to poly L-lactide and the like as nucleating agents to increase the crystallization rate. Therefore, it is possible to shorten the injection molding cycle time and to have excellent mechanical properties. In addition, Patent Documents 4 to 6 disclose that aromatic and aliphatic carboxylic acids are used for polylactic acid and aliphatic polyester. It is disclosed that a composition and a molded body having excellent crystallinity and transparency and excellent heat resistance can be obtained by mixing an amide compound.

  On the other hand, in resin molded products, it is widely used to reduce the weight, impart heat insulation and sound insulation, or use as a cushioning material by using a foam. For example, the foaming agent is decomposed by heat at the time of molding and a gas is rapidly generated, and the gas becomes bubbles to remain in the resin, thereby obtaining a foam molded product. However, foams made of polylactic acid resin have low heat resistance and deform when contacted with hot water or food cooked in a microwave oven. Not used.

  Patent Document 7 proposes a method for making cells of a foam-molded product uniform by using 2-hydroxybenzamido-1,2,4-triazol-3-yl together with a foaming agent in polypropylene. It is also known to lower the decomposition temperature of the foaming agent by using a foaming aid such as zinc stearate.

  However, 2-hydroxybenzamido-1,2,4-triazol-3-yl proposed in Patent Document 7 is effective in homogenizing cells in polypropylene, but the crystallinity, processing temperature, and processing Polylactic acid resins having different viscosities and the like are not effective, and when zinc stearate is added, it becomes difficult to control foaming due to a decrease in decomposition temperature.

Regarding foams of biodegradable resins such as polylactic acid, Patent Document 8 should use an aliphatic polyester having a specific melt viscosity and melting point, and Patent Document 9 should use talc and ethylenebisstearylamide in combination. However, Patent Document 10 uses an aliphatic polyester having a specific melt viscosity and melt tension. Patent Document 11 includes a biodegradable resin having a specific molecular weight distribution and a crosslinking aid. The foamed product is blended with polylactic acid in which the molar ratio of d-form to l-form is specified in Patent Document 12, and is a foam using a pyrolytic foaming agent and has a gel fraction of 10% or more. The foams are each disclosed.
Japanese Patent Publication No. 4-504731 (WO90 / 01521) (Claims) JP-T 6-504799 JP-A-4-220457 JP-A-9-278991 (Claims) Japanese Patent Laid-Open No. 10-87975 JP-A-11-5849 JP-A-1-203441 JP-A-6-248104 (Claims) JP-A-10-81815 JP 2003-335889 A (Claims) JP 2004-352751 A (Claims) Japanese Patent Laying-Open No. 2005-8869 (Claims)

  However, the above proposals, except for Patent Document 9, propose to provide an excellent foam by controlling and selecting the resin, and as a result, usable polylactic acid is limited. Therefore, the properties of the obtained molded product are also limited. Also, the proposal of Patent Document 9 is not satisfactory even though the properties of the foam are improved.

  Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a foamed polylactic acid-based resin composition excellent in heat resistance using general-purpose polylactic acid, particularly without limitation of resin physical properties. .

  As a result of intensive studies, the present inventors have blended polylactic acid with an amide compound selected from a chain amide compound, a cyclic amide compound, a chain hydrazide compound, and a cyclic hydrazide compound having a specific structure. The inventors have found that the above object can be achieved, and have completed the present invention.

（式（Ｉ）中、Ｒ_a、Ｒ_b及びＲ_cは、各々独立に、水素原子、ヒドロキシ基、炭素原子数１〜８のアルキル基、炭素原子数１〜８のアルコキシ基、炭素原子数６〜１８のアリール基、又は結合して環状構造（該環状構造の炭素原子数は、縮合環の全炭素原子数として１０〜１８）を表し、Ｒは、直接結合、ｎ価の炭素原子数２〜３０の炭化水素基、複素環、又は下記式（Ｉ−ａ）、

（式（Ｉ−ａ）中、Ｒ’は、ｎ価の炭素原子数１〜３０の炭化水素基又は複素環を表し、Ｘは直接結合又は炭素原子数１〜２０のアルキレン基を表し、ｎは１〜３の数を表す。）で表される基を表し、ｎは１〜３の数を表す。）

（式（ＩＩ）〜（ＶＩＩ）中、Ａ¹、Ａ²、Ａ³、Ａ⁴、Ａ⁵、Ａ⁶、Ａ⁷、Ａ⁸、Ａ⁹、Ｂ¹、Ｂ²、Ｂ³、Ｂ⁴、Ｂ⁵、Ｂ⁶、Ｂ⁷、Ｂ⁸、Ｂ⁹、Ｂ¹⁰、Ｂ¹¹およびＢ¹²は各々独立に−ＣＨ₂−、−Ｃ（＝Ｏ）−、−Ｃ（＝Ｓ）−、−ＮＨ−、−ＮＲ₁₃−、又は−Ｓ（＝Ｏ）₂−を表し、Ｒ₁、Ｒ₂、Ｒ₃、Ｒ₄、Ｒ₅、Ｒ₆、Ｒ₇、Ｒ₈、Ｒ₉、Ｒ₁₀、Ｒ₁₁、Ｒ₁₂は水素原子、ハロゲン原子、ヒドロキシ基、炭素原子数１〜１８のアルキル基、アルケニル基、アルキニル基、アルコキシ基、シクロアルキル基、又は炭素原子数６〜１８のアリール基を表し、Ｒ₁₃は−ＮＨ₂、−ＮＨＲ₁₄、−ＮＨＣ（＝Ｏ）−Ｒ₁₅、炭素原子数１〜１８のアルキル基、シクロアルキル基、アルケニル基、又は炭素原子数６〜１８のアリール基を表し、Ｒ₁₄、Ｒ₁₅は炭素原子数１〜１８のアルキル基、シクロアルキル基、アルケニル基、又は炭素原子数６〜１８のアリール基を表す。ただし、Ａ¹、Ａ²、Ａ³のいずれか１個以上は−Ｃ（＝Ｏ）−又は−Ｃ（＝Ｓ）−であり、いずれか１個以上は−ＮＨ−又は−ＮＲ₁₃−であり、Ａ⁴、Ａ⁵、Ａ⁶のいずれか１個以上は−Ｃ（＝Ｏ）−又は−Ｃ（＝Ｓ）−であり、いずれか１個以上は−ＮＨ−又は−ＮＲ₁₃−であり、Ａ⁷、Ａ⁸、Ａ⁹のいずれか１個以上は−Ｃ（＝Ｏ）−又は−Ｃ（＝Ｓ）−であり、いずれか１個以上は−ＮＨ−又は−ＮＲ₁₃−であり、Ｂ¹、Ｂ²、Ｂ³、Ｂ⁴のいずれか１個以上は−Ｃ（＝Ｏ）−又は−Ｃ（＝Ｓ）−であり、いずれか１個以上は−ＮＨ−又は−ＮＲ₁₃−であり、Ｂ⁵、Ｂ⁶、Ｂ⁷、Ｂ⁸のいずれか１個以上は−Ｃ（＝Ｏ）−又は−Ｃ（＝Ｓ）−であり、いずれか１個以上は−ＮＨ−又は−ＮＲ₁₃−であり、Ｂ⁹、Ｂ¹⁰、Ｂ¹¹、Ｂ¹²のいずれか１個以上は−Ｃ（＝Ｏ）−又は−Ｃ（＝Ｓ）−であり、いずれか１個以上は−ＮＨ−又は−ＮＲ₁₃−である。） That is, the foamed polylactic acid-based resin composition of the present invention has a chain amide compound or chain hydrazide compound represented by the following general formula (I), and the following general formula (II) to 100 parts by weight of polylactic acid. (VII) One or more amide compounds selected from cyclic amide compounds or cyclic hydrazide compounds represented by any one of (VII) are blended in an amount of 0.01 to 10 parts by weight. is there.

(In the formula (I), R _a , R _b and R _c are each independently a hydrogen atom, a hydroxy group, an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, or the number of carbon atoms. An aryl group of 6 to 18 or a cyclic structure (the number of carbon atoms of the cyclic structure is 10 to 18 as the total number of carbon atoms of the condensed ring), and R is a direct bond, the number of n-valent carbon atoms 2 to 30 hydrocarbon groups, heterocyclic rings, or the following formula (Ia),

(In the formula (Ia), R ′ represents an n-valent hydrocarbon group or heterocyclic ring having 1 to 30 carbon atoms, X represents a direct bond or an alkylene group having 1 to 20 carbon atoms, and n Represents a number of 1 to 3.), and n represents a number of 1 to 3. )

(In the formula (II) ~ (VII), A 1, A 2, A 3, A 4, A 5, A 6, A 7, A 8, A 9, B 1, B 2, B 3, B 4, B ⁵ , B ⁶ , B ⁷ , B ⁸ , B ⁹ , B ¹⁰ , B ¹¹ and B ¹² are each independently —CH ₂ —, —C (═O) —, —C (═S) —, —NH -, - NR ₁₃ -, or -S (= O) ₂ - _{represents, R 1, R 2, R} 3, R 4, R 5, R 6, R 7, R 8, R 9, R 10, R ₁₁ , R ₁₂ represents a hydrogen atom, a halogen atom, a hydroxy group, an alkyl group having 1 to 18 carbon atoms, an alkenyl group, an alkynyl group, an alkoxy group, a cycloalkyl group, or an aryl group having 6 to 18 carbon atoms; R ₁₃ is _{-NH 2, -NHR 14, -NHC (} = O) -R 15, an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group, an alkenyl group, or an aryl group having 6 to 18 carbon atoms R _14, R ₁₅ represents an alkyl group, a cycloalkyl group, an alkenyl group, or an aryl group having 6 to 18 carbon atoms having 1 to 18 carbon atoms. However, A ^1, any one of A ^2, A ³ One or more is —C (═O) — or —C (═S) —, and one or more is —NH— or —NR ₁₃ —, and any one of A ⁴ , A ⁵ , and A ⁶ One or more is —C (═O) — or —C (═S) —, one or more is —NH— or —NR ₁₃ —, and any one of A ⁷ , A ⁸ , and A ⁹ One or more is —C (═O) — or —C (═S) —, and one or more is —NH— or —NR ₁₃ —, and each of B ¹ , B ² , B ³ , B ⁴ Any one or more is —C (═O) — or —C (═S) —, and any one or more is —NH— or —NR ₁₃ —, and B ⁵ , B ⁶ , B ⁷ , any one of the B ⁸ Above is -C (= O) - or -C (= S) -, wherein 1 or more either is -NH- or -NR ₁₃ - and is, any ^{B 9, B 10, B 11} , B 12 Or at least one is —C (═O) — or —C (═S) —, and at least one is —NH— or —NR ₁₃ —.)

  In the present invention, the amide compound is preferably a compound having a benzoic acid amide structure.

  In the present invention, a compound having a condensed heterocyclic structure is also suitable as the amide compound.

  Furthermore, in the present invention, decanedicarboxylic acid bisbenzoyl hydrazide is also suitable as the amide compound.

  Furthermore, in the present invention, phthalic hydrazide is also suitable as the amide compound.

  The heat-resistant polylactic acid-based resin molded product of the present invention is characterized by being formed by molding the above-mentioned foamed polylactic acid-based resin composition.

  According to the present invention, it is possible to provide a foamed polylactic acid-based resin composition having excellent heat resistance using general-purpose polylactic acid without any particular limitation on the physical properties of the resin, because of the above configuration.

  In the present invention, polylactic acid (lactic acid-based polymer) includes polylactic acid homopolymers, polylactic acid copolymers, and blend polymers of polylactic acid homopolymers and copolymers. Further, a blend polymer mainly composed of a polylactic acid homopolymer and / or a polylactic acid copolymer may be used as long as the crystallinity characteristic of the present invention is not impaired.

  The weight average molecular weight of polylactic acid is generally 50,000 to 500,000, preferably 100,000 to 250,000. If the weight average molecular weight is less than 50,000, physical properties necessary for practical use cannot be obtained. On the other hand, if the weight average molecular weight exceeds 500,000, the moldability tends to deteriorate.

  In addition, the constituent molar ratio L / D of the L-lactic acid unit and the D-lactic acid unit in the polylactic acid may be any of 100/0 to 0/100, but L-lactic acid or D may be used to obtain a high melting point. -In order to obtain 75 mol% or more of any unit of lactic acid and a higher melting point, it is preferable to contain 90 mol% or more of any unit of L-lactic acid or D-lactic acid.

  The lactic acid copolymer is obtained by copolymerizing a lactic acid monomer or other component copolymerizable with lactide. Examples of such other components include dicarboxylic acids having two or more ester bond-forming functional groups, polyhydric alcohols, hydroxycarboxylic acids, lactones, etc., and various polyesters and various polyethers composed of these various components. And various polycarbonates.

  Examples of the dicarboxylic acid include succinic acid, adipic acid, azelaic acid, sebacic acid, terephthalic acid, and isophthalic acid.

  Examples of polyhydric alcohols include aromatic polyhydric alcohols such as those obtained by addition reaction of bisphenol with ethylene oxide, ethylene glycol, propylene glycol, butanediol, hexanediol, octanediol, glycerin, sorbitan, trimethylolpropane, neo Examples include aliphatic polyhydric alcohols such as pentyl glycol, ether glycols such as diethylene glycol, triethylene glycol, polyethylene glycol, and polypropylene glycol.

  Examples of the hydroxycarboxylic acid include glycolic acid, hydroxybutylcarboxylic acid, and others described in JP-A-6-184417.

  Examples of the lactone include glycolide, ε-caprolactone glycolide, ε-caprolactone, ε-propiolactone, δ-butyrolactone, β-butyrolactone, γ-butyrolactone, pivalolactone, δ-valerolactone, and the like.

  Polylactic acid can be synthesized by a conventionally known method. That is, direct dehydration condensation from a lactic acid monomer as described in JP-A-7-33861, JP-A-59-96123, Polymer Proceedings Proceedings Vol. 44, pages 3198-3199, or cyclic lactic acid It can be synthesized by ring-opening polymerization of a monomeric lactide.

  When performing direct dehydration condensation, any lactic acid of L-lactic acid, D-lactic acid, DL-lactic acid, or a mixture thereof may be used. Moreover, when performing ring-opening polymerization, you may use any lactide of L-lactide, D-lactide, DL-lactide, meso-lactide, or a mixture thereof.

  The synthesis, purification and polymerization operations of lactide are described, for example, in US Pat. No. 4,057,537, published European Patent Application No. 261572, Polymer Bulletin, 14, 491-495 (1985), and Macromol. Chem. 187, 1611-1628 (1986), etc.

  The catalyst used in this polymerization reaction is not particularly limited, but a known lactic acid polymerization catalyst can be used. For example, tin compounds such as tin lactate, tin tartrate, dicaprylate, dilaurate, dipalmitate, tin distearate, tin dioleate, tin α-naphthoate, tin β-naphthoate, tin octylate, Powdered tin, tin oxide, zinc powder, zinc halide, zinc oxide, organic zinc compounds, titanium compounds such as tetrapropyl titanate, zirconium compounds such as zirconium isopropoxide, antimony compounds such as antimony trioxide, oxidation Examples thereof include bismuth compounds such as bismuth (III) and aluminum compounds such as aluminum oxide and aluminum isopropoxide.

  Among these, a catalyst made of tin or a tin compound is particularly preferable from the viewpoint of activity. The amount of these catalysts used is, for example, about 0.001 to 5% by weight based on lactide when ring-opening polymerization is performed.

  The polymerization reaction can be usually performed at a temperature of 100 to 220 ° C. in the presence of the catalyst, although it varies depending on the catalyst type. It is also preferable to carry out a two-stage polymerization as described in JP-A-7-247345.

  The blend polymer mainly composed of polylactic acid is, for example, a mixture obtained by mixing and melting polylactic acid homopolymer and / or lactic acid copolymer and aliphatic polyester other than polylactic acid, and aliphatic polyester other than polylactic acid. By blending, it is possible to impart flexibility and impact resistance to the molded product. The weight ratio of the blend is usually about 10 to 100 parts by weight of an aliphatic polyester other than polylactic acid with respect to 100 parts by weight of the polylactic acid homopolymer and / or lactic acid copolymer.

  In the present invention, an aliphatic polyester other than polylactic acid (hereinafter simply referred to as “aliphatic polyester”) may be a single polymer or a composite of two or more polymers. For example, the polymer may be an aliphatic carboxylic acid component. And an aliphatic hydroxycarboxylic acid polymer obtained by ring-opening polymerization of a cyclic anhydride such as ε-caprolactone. To obtain these, there are a method of directly polymerizing to obtain a high molecular weight product, and an indirect method of obtaining a high molecular weight product with a chain extender after polymerization to the extent of an oligomer. Further, the aliphatic polyester may be a copolymer or a mixture with other resins as long as it is a polymer mainly composed of the aliphatic monomer component.

  The aliphatic polyester used in the present invention is preferably composed of an aliphatic dicarboxylic acid and an aliphatic diol. Examples of the aliphatic dicarboxylic acid include compounds such as succinic acid, adipic acid, suberic acid, sebacic acid, and dodecanoic acid, and anhydrides and derivatives thereof. On the other hand, as the aliphatic diol, glycol compounds such as ethylene glycol, butanediol, hexanediol, octanediol, cyclohexanedimethanol, and derivatives thereof are common. These aliphatic dicarboxylic acids and aliphatic diols are monomers having an alkylene group, a cyclocyclic group or a cycloalkylene group having 2 to 10 carbon atoms. Aliphatic polyesters are produced by polycondensation of monomer compounds selected from these aliphatic dicarboxylic acids and aliphatic diols. Two or more kinds of carboxylic acid components or alcohol components may be used.

  Further, for the purpose of providing a branch in the polymer for improving the melt viscosity, a trifunctional or higher polyfunctional carboxylic acid, alcohol or hydroxycarboxylic acid may be used as a component of the aliphatic polyester. When these components are used in a large amount, the resulting polymer has a cross-linked structure and may not be thermoplastic, or even if it is thermoplastic, a microgel partially having a highly cross-linked structure may be produced. Therefore, these non-trifunctional components are contained in such a small amount that they do not greatly affect the chemical properties and physical properties of the polymer. As the polyfunctional component, malic acid, tartaric acid, citric acid, trimellitic acid, pyromellitic acid, pentaerythritol, trimethylolpropane, or the like can be used.

  Among the methods for producing aliphatic polyesters, the direct polymerization method is a method for obtaining a high molecular weight product while removing water contained in the compound by selecting the above compound or generated during the polymerization. The indirect polymerization method selects the above compounds and polymerizes them to an oligomer level, and then, for the purpose of increasing the molecular weight, a small amount of chain extender, for example, diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate. This is a method of increasing the molecular weight using a compound. Alternatively, there is a method of obtaining aliphatic polyester carbonate using a carbonate compound.

Examples of the alkyl group having 1 to 8 carbon atoms represented by R _a , R _b and R _c in the general formula (I) include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, Examples include pentyl, tertiary pentyl, hexyl, heptyl, octyl, tertiary octyl, 2-ethylhexyl and the like. Examples of the alkoxy group having 1 to 8 carbon atoms represented by R _a , R _b and R _c include an alkoxy group corresponding to the above alkyl group.

Examples of the aryl group having 6 to 18 carbon atoms represented by R _a , R _b and R _c in the general formula (I) include phenyl, naphthyl and biphenyl.

Furthermore, as a cyclic structure in which any two of R _a , R _b and R _c in the general formula (I) are bonded (the number of carbon atoms is 10 to 18 as the total number of carbon atoms in the condensed ring), naphthyl Etc.

  The hydrocarbon which forms the n-valent C2-C30 hydrocarbon group represented by R in R and the hydrocarbon group which forms the n-valent C1-C30 hydrocarbon group represented by R 'in the general formula (I). As, for example, aliphatic saturated hydrocarbons such as linear or branched ethane, propane, butane, pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane, etc. Aliphatic unsaturated hydrocarbons such as ethylene, propene, butene, butadiene, and dodecene, and aromatic hydrocarbons such as benzene, naphthalene, anthracene, biphenyl, and terphenyl.

Examples of the heterocyclic ring represented by R and R ′ include those having the structures shown below.

In the general formula (I), R is preferably a heterocyclic ring or a group represented by the following formula (Ia), and n is preferably 1 or 2. In the following formula (Ia), R ′ is preferably an alkylene group having 2 to 22 carbon atoms.

化合物Ｎｏ．２

化合物Ｎｏ．３

化合物Ｎｏ．４

化合物Ｎｏ．５

化合物Ｎｏ．６

化合物Ｎｏ．７

化合物Ｎｏ．８

化合物Ｎｏ．９

化合物Ｎｏ．１０

More specifically, examples of the compound represented by the general formula (I) include the following compound Nos. 1-10 etc. are mentioned. However, this invention is not restrict | limited at all by the following compounds.
Compound No. 1

Compound No. 2

Compound No. 3

Compound No. 4

Compound No. 5

Compound No. 6

Compound No. 7

Compound No. 8

Compound No. 9

Compound No. 10

Further, R ₁ in the general formula (II) ~ (VII), R 2, R 3, R 4, R 5, R 6, R 7, R 8, R 9, R 10, R 11, R 12, R Examples of the alkyl group having 1 to 18 carbon atoms represented by ₁₃ , R ₁₄ and R ₁₅ include methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl, pentyl, tert-pentyl, and hexyl. , Heptyl, octyl, isooctyl, tertiary octyl, 2-ethylhexyl, nonyl, isononyl, decyl, isodecyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl and the like. Examples of the alkenyl group include vinyl, propenyl, butenyl, octenyl, oleyl and the like. Examples of the cycloalkyl group include cyclopentyl, cyclohexyl, cycloheptyl and the like.

Furthermore, it is represented by R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ , R ₈ , R ₉ , R ₁₀ , R ₁₁ and R ₁₂ in the general formulas (II) to (VII). Examples of the alkoxy group having 1 to 18 carbon atoms include an alkoxy group corresponding to the above alkyl group.

In the general formulas (II) to (VII), R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ , R ₈ , R ₉ , R ₁₀ , R ₁₁ and R ₁₂ Examples of the halogen atom include fluorine, chlorine, bromine and the like.

Furthermore, R ₁ in the general formula (II) ~ (VII), R 2, R 3, R 4, R 5, R 6, R 7, R 8, R 9, R 10, R 11, R 12, Examples of the aryl group having 6 to 18 carbon atoms represented by R ₁₃ , R ₁₄ and R ₁₅ include phenyl, naphthyl, biphenyl and the like.

化合物Ｎｏ．１２

化合物Ｎｏ．１３

化合物Ｎｏ．１４

化合物Ｎｏ．１５

化合物Ｎｏ．１６

化合物Ｎｏ．１７

化合物Ｎｏ．１８

化合物Ｎｏ．１９

化合物Ｎｏ．２０

化合物Ｎｏ．２１

化合物Ｎｏ．２２

化合物Ｎｏ．２３

化合物Ｎｏ．２４

化合物Ｎｏ．２５

More specifically, examples of the compounds represented by the general formulas (II) to (VII) include the following compound Nos. 11-25 etc. are mentioned. However, this invention is not restrict | limited at all by the following compounds.
Compound No. 11

Compound No. 12

Compound No. 13

Compound No. 14

Compound No. 15

Compound No. 16

Compound No. 17

Compound No. 18

Compound No. 19

Compound No. 20

Compound No. 21

Compound No. 22

Compound No. 23

Compound No. 24

Compound No. 25

  The amide compound is used in an amount of 0.01 to 10 parts by weight, preferably 0.05 to 5 parts by weight, and more preferably 0.1 to 3 parts by weight with respect to 100 parts by weight of the polylactic acid resin. When the amount is less than 0.01 parts by weight, the effect of addition is insufficient, and when the amount is more than 10 parts by weight, a phenomenon such as ejection on the surface of the polylactic acid-based resin composition occurs.

  Among the amide compounds, compounds having a benzoic acid amide structure, particularly decanedicarboxylic acid bisbenzoyl hydrazide, are preferable because they are particularly excellent in heat resistance of the obtained foamed polylactic acid resin molded product.

  Among the amide compounds, the compound having a condensed heterocyclic structure has a melting point of 200 ° C. or higher, which is higher than that of polylactic acid resin. In addition to being expected to be the core of crystallization at the start, it is preferable because there is little ejection from the resin.

  The method for foaming the polylactic acid-based resin in the present invention is not particularly limited, and any conventionally known method for producing a foamed resin composition can be used. For example, it can be produced by mixing a pyrolytic foaming agent or a volatile foaming agent with a polylactic acid resin, an amide compound and other blends and molding at a decomposition temperature or higher. Moreover, the intensity | strength of a foam can also be improved by bridge | crosslinking using a crosslinking agent or an electron beam.

  Examples of the heat decomposable foaming agent include various organic and inorganic heat decomposable foaming agents. Examples of the organic foaming agent include azodicarbonamide, N, N′-dinitrosopentamethylenetetramine, P -P'-oxybisbenzenesulfonyl hydrazide and the like. Examples of the inorganic foaming agent include sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, and calcium azide.

  Examples of the volatile blowing agent include aliphatic hydrocarbons such as propane, butane, pentane, isobutane, neopentane, isopentane, hexane, and butadiene, as well as methyl chloride, methylene chloride, dichlorofluoromethane, chlorotrifluoromethane, and dichlorodifluoro. Halogenated hydrocarbons such as methane, chlorodifluoromethane, and trichlorofluoromethane. In order to produce a foam using such a volatile foaming agent, a volatile foaming agent is injected while melting and kneading a raw material mainly composed of aliphatic polyester in an extruder, or volatile to the raw material. A foam can be produced by extruding a material impregnated with a foaming agent from the extruder into the atmosphere.

  Examples of the crosslinking agent include organic peroxides having a decomposition temperature equal to or higher than the melting point of the resin, and examples thereof include dicumyl peroxide, cumene hydroperoxide, methyl ethyl ketone peroxide, and t-butyl peroxyisopropyl carbonate.

In the present invention, ionizing radiation such as electron beam, β ray, and gamma ray can be used for crosslinking. In the case of crosslinking by radiation, irradiation of 1 Mrad to 50 Mrad is performed in an N ₂ atmosphere in order to prevent deterioration of the resin. If it is less than 1 Mrad, a crosslinking reaction does not occur, and if it exceeds 50 Mrad, the deterioration of the resin becomes severe. The thickness of the resin is desirably 1 mm or less, and more desirably 5 mm or less. If the thickness exceeds 1 mm, the radiation does not reach the inside, so that the bubbles inside are coarse and non-uniform during foaming.

  In the present invention, the method of blending various additives into polylactic acid is not particularly limited, and can be performed by a conventionally known method. For example, the lactic acid polymer powder or pellet and the additive components may be mixed by dry blending, or a part of the additive component may be preblended and the other components may be dry blended later. For example, they may be mixed using a mill roll, a Banbury mixer, a super mixer, etc., and kneaded using a single screw or twin screw extruder. This mixing and kneading is usually performed at a temperature of about 120 to 220 ° C. Further, an additive component may be added at the polymerization stage of the lactic acid-based polymer. Moreover, the method etc. which produce | generate the masterbatch which contains each additive component in high concentration, and add this to a lactic acid-type polymer can be used.

  Furthermore, the foamed polylactic acid-based resin composition of the present invention includes, as necessary, conventionally known plasticizers, antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, pigments, colorants, various fillers, charging agents. Various additives such as an inhibitor, a release agent, a fragrance, a lubricant, a flame retardant, a foaming agent, a filler, an antibacterial / antifungal agent, and a nucleating agent may be blended.

  The filler is not particularly limited, and hydrous magnesium silicate (talc), silica, calcium carbonate and the like can be used regardless of the particle diameter and the production method. Among these fillers, hydrous magnesium silicate is preferable because it has an excellent effect of promoting the formation of crystal nuclei, and the average particle size is more preferably 10 μm or less, and particularly preferably 1 to 5 μm. The use of hydrous magnesium silicate having an average particle diameter exceeding 10 μm is effective, but if it is 10 μm or less, the effect of promoting the formation of crystal nuclei is higher and the heat resistance of the molded product can be further improved.

  The amount of hydrous magnesium silicate (talc) is preferably 0.01 to 40 parts by weight, more preferably 0.01 to 30 parts by weight, based on 100 parts by weight of the polylactic acid resin. If the blending amount is less than 0.01 parts by weight, the effect of addition is not obtained so much that if it exceeds 40 parts by weight, not only the specific gravity of the resin composition increases, but also the impact resistance decreases.

  The foamed polylactic acid resin composition of the present invention has a crystallization peak temperature of 90 to 150 ° C. and a crystallization heat amount of 20 J / g or more, preferably 25 J / g or more in a scanning differential calorimeter (DSC). If the crystallization peak temperature is less than 90 ° C, the cooling time during the molding process becomes longer. On the other hand, if the crystallization peak temperature exceeds 150 ° C, the elastic modulus of the molded product is lowered even if the crystallization speed is high. Accordingly, it becomes difficult to take out. Further, if the heat of crystallization is less than 20 J / g, the moldability at the crystallizable temperature is deteriorated, the heat resistance of the obtained molded product is inferior, and the tensile strength and impact strength are also inferior.

  The present invention also relates to a heat-resistant foam-molded product obtained from the above-mentioned foamed polylactic acid-based resin composition.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.
Example 1
The blended components shown in Table 1 are dry blended, melt mixed in a twin-screw kneading extruder at 170 ° C., extruded into a strand form from a die, cooled with water, cut, and a foamed polylactic acid resin composition containing an amide compound Pellets were obtained.

  The obtained pellets were vacuum-dried at 110 ° C. and brought to a completely dry state, then melted and foamed using a spacer having a thickness of 5 mm in a compression molding machine at 220 ° C., and then held at 110 ° C. Made it. Using the obtained foam as a test piece, in accordance with JIS K7206, using Vicat softening temperature tester (manufactured by Toyo Seiki Seisakusho Co., Ltd., automatic HDT-VICAT test device), the temperature rising rate is 50 ° C./hour in an oil bath. The Vicat softening temperature was measured at a test load of 10 N. Higher Vicat softening temperature indicates better heat resistance. The results are shown in Table 1.

In addition, each formulation used for the Example and comparative example of Table 1 are as follows, and all the compounding quantities in Table 1 show a "weight part."
Polylactic acid: manufactured by Mitsui Chemicals, LACEA H-100
Foaming agent: Sankyo Kasei Co., Ltd., Cell microphone 306
Compound A: Chain amide compound: Compound No. 5
Compound B: Chain hydrazide compound: Compound No. 2
Compound C: Cyclic amide compound: Compound No. 21
Compound D: Cyclic hydrazide compound: Compound No. 11
Comparative amide compound: KK Trading Co., Ltd., ethylene bis (hydroxystearic acid) amide talc: Nihon Talc Co., Ltd., fine powder talc "Microace P-6"

  From the results of Examples 1 to 4 and Comparative Examples 1 and 2 shown in Table 1 above, the molded product obtained using the foamed polylactic acid-based resin composition of the present invention in which a specific amide compound is blended is an amide compound. It is clear that the heat resistance is higher than when not added (Comparative Example 1) or when known talc and ethylenebis (hydroxystearic acid) amide are used together (Comparative Example 2).

Claims (6)

A cyclic amide compound or a chain hydrazide compound represented by the following general formula (I) and a cyclic represented by any one of the following general formulas (II) to (VII) with respect to 100 parts by weight of polylactic acid A foamed polylactic acid resin composition comprising 0.01 to 10 parts by weight of one or more amide compounds selected from amide compounds or cyclic hydrazide compounds.

(In the formula (I), R _a , R _b and R _c are each independently a hydrogen atom, a hydroxy group, an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, or the number of carbon atoms. An aryl group of 6 to 18 or a cyclic structure (the number of carbon atoms of the cyclic structure is 10 to 18 as the total number of carbon atoms of the condensed ring), and R is a direct bond, the number of n-valent carbon atoms 2 to 30 hydrocarbon groups, heterocyclic rings, or the following formula (Ia),

(In the formula (Ia), R ′ represents an n-valent hydrocarbon group or heterocyclic ring having 1 to 30 carbon atoms, X represents a direct bond or an alkylene group having 1 to 20 carbon atoms, and n Represents a number of 1 to 3.), and n represents a number of 1 to 3. )

(In the formula (II) ~ (VII), A 1, A 2, A 3, A 4, A 5, A 6, A 7, A 8, A 9, B 1, B 2, B 3, B 4, B ⁵ , B ⁶ , B ⁷ , B ⁸ , B ⁹ , B ¹⁰ , B ¹¹ and B ¹² are each independently —CH ₂ —, —C (═O) —, —C (═S) —, —NH -, - NR ₁₃ -, or -S (= O) ₂ - _{represents, R 1, R 2, R} 3, R 4, R 5, R 6, R 7, R 8, R 9, R 10, R ₁₁ , R ₁₂ represents a hydrogen atom, a halogen atom, a hydroxy group, an alkyl group having 1 to 18 carbon atoms, an alkenyl group, an alkynyl group, an alkoxy group, a cycloalkyl group, or an aryl group having 6 to 18 carbon atoms; R ₁₃ is _{-NH 2, -NHR 14, -NHC (} = O) -R 15, an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group, an alkenyl group, or an aryl group having 6 to 18 carbon atoms R _14, R ₁₅ represents an alkyl group, a cycloalkyl group, an alkenyl group, or an aryl group having 6 to 18 carbon atoms having 1 to 18 carbon atoms. However, A ^1, any one of A ^2, A ³ One or more is —C (═O) — or —C (═S) —, and one or more is —NH— or —NR ₁₃ —, and any one of A ⁴ , A ⁵ , and A ⁶ One or more is —C (═O) — or —C (═S) —, one or more is —NH— or —NR ₁₃ —, and any one of A ⁷ , A ⁸ , and A ⁹ One or more is —C (═O) — or —C (═S) —, and one or more is —NH— or —NR ₁₃ —, and each of B ¹ , B ² , B ³ , B ⁴ Any one or more is —C (═O) — or —C (═S) —, and any one or more is —NH— or —NR ₁₃ —, and B ⁵ , B ⁶ , B ⁷ , any one of the B ⁸ Above is -C (= O) - or -C (= S) -, wherein 1 or more either is -NH- or -NR ₁₃ - and is, any ^{B 9, B 10, B 11} , B 12 Or at least one is —C (═O) — or —C (═S) —, and at least one is —NH— or —NR ₁₃ —.)   The foamed polylactic acid resin composition according to claim 1, wherein the amide compound is a compound having a benzoic acid amide structure.   The foamed polylactic acid resin composition according to claim 1, wherein the amide compound is a compound having a condensed heterocyclic structure.   The foamed polylactic acid resin composition according to claim 1, wherein the amide compound is decanedicarboxylic acid bisbenzoyl hydrazide.   The foamed polylactic acid resin composition according to claim 1, wherein the amide compound is phthalic hydrazide.   A heat-resistant polylactic acid-based resin molded product obtained by molding the foamed polylactic acid-based resin composition according to any one of claims 1 to 5.