JP2006008972A - Resin composition, resin molded article, and method for producing resin molded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polylactic acid composition that is excellent in heat resistance and whose dynamic property, chemical resistance etc., are improved without deteriorating its moldability, especially to provide a polylactic acid composition whose properties as described above are made improvable without deteriorating its transparency that is a specific character of polylactic acid. <P>SOLUTION: The resin composition comprises a polymer and/or prepolymer, a polyfunctional crosslinking agent and an inorganic fine particle and is treated by high energy ray irradiation, wherein the polymer and/or prepolymer are desirably a polylactic acid and it is more desirable that the resin composition is a polylactic acid composition etc., that are composed of a polylactic acid, a polyfunctional crosslinking agent and an inorganic fine particle and is treated by high energy ray irradiation. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a resin composition, a resin molded body, and a method for producing a resin molded body. More specifically, a resin composition such as a polylactic acid resin composition, which contains a polymer and / or prepolymer such as polylactic acid, a polyfunctional crosslinking agent and inorganic fine particles, and is treated with high energy rays, a molded product thereof, and production thereof Regarding the method.

  Conventionally, many prepolymers that are polymers or polymer precursors are chemically stable, can be molded in various ways, and are inexpensive, so that they are currently used in large quantities for a very wide range of applications. However, these polymers generally do not always have sufficient heat resistance, dimensional stability over time (creep properties), mechanical properties (strength, elastic modulus), and various improvements have been attempted.

  Examples of typical methods include copolymerization of different monomers, blending / alloying of different polymers, or a composite with an inorganic filler or an organic filler. However, copolymerization with different monomers has limitations on the polymerizable monomers and alteration of the produced polymer, and blends and alloys of different polymers make it opaque due to incompatibility, decrease in mechanical properties, decrease in thermal properties, etc. Often occurs. In the composite with filler, there are many problems such as opacification and deterioration of moldability.

Biodegradable resins are said to be decomposed by the activity of microorganisms after use, and eventually become carbon dioxide and water, and plant starch and cellulose can be used as raw materials, eliminating the need to use crude oil Great effects on resource conservation, global warming prevention and environmental conservation are expected.
However, since the biodegradable resin has a very simple molecular structure, the above-described drawbacks of the polymer are further remarkable, and the application cannot be broadened greatly.

  Polylactic acid resin can be made from renewable plant starches such as corn starch and potato starch, and it does not require the use of petroleum resources, and there is no generation of carbon dioxide gas that leads to resource problems and global warming. It is one of the materials that are highly expected as an environmentally friendly material. In addition, a major feature of polylactic acid resin that is different from other biodegradable resins is that it is highly transparent. For this reason, it is used in various films, sheets, packaging containers, and casings that require transparency. I am trying to do. The transparency of the polylactic acid depends on the crystallinity of the molded product of polylactic acid. For example, when heated at a temperature exceeding 100 ° C., the polylactic acid easily crystallizes (generates spherulites) and whitens (devitrifies). Of course, polylactic acid is essentially amorphous (for example, if the ratio of L-lactic acid constituting the polylactic acid resin is 30 mol% or less, the polylactic acid resin is essentially amorphous and does not crystallize even when heated. This amorphous polylactic acid has poor heat resistance (dimensional stability, heat distortion resistance) and has limited applications.

  In other words, it has not been possible to improve heat resistance of polylactic acid resin, which is very environmentally friendly, while maintaining its characteristic transparency. It is. Therefore, for expanding the use of polylactic acid, it is very important to improve the heat resistance while maintaining the transparency, which is a feature of the polylactic acid.

  In order to improve heat resistance, copolymerization of aromatic polyester components, copolymerization of amide components, or blends of other polymers having excellent heat resistance have been studied, but all of them have compatibility with polylactic acid. Insufficient devitrification and deterioration of physical properties due to phase separation or whitening and devitrification due to crystallization cannot be avoided, and sufficient improvement has not been achieved.

  In addition to the measures described above, as a method that may be used to modify the biodegradable resin, there is a method in which polymer molecular chains are crosslinked to form a network structure. By introducing a cross-linked structure, it is possible to substantially increase the molecular weight and decrease the molecular mobility, and to improve the heat resistance, mechanical properties, chemical resistance, etc. of the polymer. For example, in JP-A-10-251402, JP-A-2002-194221, JP-A-6-322358, and JP-A-2001-329070, a superabsorbent resin using a cross-linked product of glutamic acid or starch, etc. However, here, no proposals have been made that lead to improvements in heat resistance and mechanical properties of the target polymer of the present application (see Patent Documents 1 to 4).

  Also, JP 2002-69206 A, JP 2002-114921 A, JP 2003-165862 A, JP 11-276044 A, JP 11-279271 A, JP 11-279272 A, In JP-A-11-279391 and JP-A-2001-254010, a typical synthetic biodegradable resin such as polycaprolactone, polylactic acid, aliphatic polyester, or a derivative thereof is subjected to radiation crosslinking, electron beam crosslinking. It has been proposed to improve the properties such as the improvement of moldability (preventing sagging and foaming), the improvement of physical properties such as strength, the increase of shrinkage, etc. (See Patent Documents 5 to 12).

In addition, composite materials obtained by adding a natural product filler such as kenaf or bamboo fiber to a polylactic acid resin are also disclosed in Japanese Patent Application Laid-Open No. Hei, Japanese Patent Application Laid-Open No. Proceedings of academic societies p50 (2004)) et al., Kitagawa et al. (Kitakawa et al .: Abstracts of Molding Society p146, p474 (2004)), etc. And the material itself becomes totally opaque. In order to achieve sufficient heat resistance, 50% or more of kenaf is required. This is not only transparent, but also has almost no molding processability, so only a limited number of products can be obtained by a specific processing method. It cannot be said that this is a technique to be provided (see Patent Documents and Documents 5 to 12).
JP-A-10-251402 JP 2002-194221 A JP-A-6-322358 JP 2001-329070 A JP 2002-69206 A JP 2002-114921 A JP 2003-165862 A Japanese Patent Laid-Open No. 11-276044 JP-A-11-279271 JP 11-279272 A JP-A-11-279391 JP 2001-254010 A Japanese Patent Laid-Open No. 2004-255833 Japanese Patent Laid-Open No. 2003-201662 JP 2004-143438 A Inao et al .: Abstracts of Molding Processing Society p50 (2004) Kitagawa et al .: Abstracts of Japan Society for Mold Processing p146 (2004) Kitagawa et al .: Abstracts of Molding Processing Society p474 (2004)

  As described above, the conventional technique mainly introduces a very light crosslinking to a natural polymer to produce a highly water-absorbent resin and performs a slight crosslinking to maintain the viscosity at the time of melt molding. There are things far from improving the heat resistance, dimensional stability, and mechanical properties of the invention. In addition, when the glass transition point (Tg) or higher is heated due to the low degree of crosslinking, there is no effect on the restraint of local movement of the molecular chain, and there is no improvement in brittleness, which is a major drawback of polylactic acid in terms of physical properties. On the other hand, in the crystallized polymer, spherulites are generated throughout the polymer, and as a result, transparency is lost and physical properties such as brittleness are deteriorated. In particular, no effect can be expected for improving mechanical properties and heat resistance while maintaining transparency. Polylactic acid resin is the only transparent resin among biodegradable resins. However, if it is crystallized to improve heat resistance or composited with inorganic fine particles, the most characteristic transparency is lost.

  The present invention has been made in view of the circumstances as described above, and an object thereof is a polymer or prepolymer composition that has excellent heat resistance and improved mechanical properties, chemical resistance, and the like without degrading moldability. Is to provide. In particular, in the case of a transparent material, the polylactic acid resin composition, the polylactic acid resin molded body, and the method for producing the polylactic acid resin molded body that can improve the physical properties such as heat resistance and dimensional stability without reducing the transparency. Is to provide.

The resin composition according to claim 1 includes a polymer and / or a prepolymer, a polyfunctional crosslinking agent, and inorganic fine particles, and is characterized by being treated by high energy ray irradiation.
The resin composition according to claim 2 is characterized in that the polymer and / or the prepolymer are biodegradable.

    The resin composition according to claim 3 is characterized in that the gel fraction is 60% or more.

    The resin composition of claim 4 is characterized in that the polymer and / or prepolymer is polylactic acid.

    The resin composition according to claim 5 is characterized in that polylactic acid is copolymerized with at least 70% or more of L-lactic acid.

    The resin composition according to claim 6 is characterized in that it contains at least 3 parts by weight of a polyfunctional crosslinking agent per 100 parts by weight of polylactic acid.

  The resin composition of claim 7 is characterized in that the maximum length of the inorganic fine particles is 200 nm or less.

  The resin composition of claim 8 is characterized in that it contains at least 5 parts by weight of inorganic fine particles per 100 parts by weight of polylactic acid.

The resin composition according to claim 9 is characterized in that at least 10 kgy of high energy rays are irradiated.
The resin composition according to claim 10 is characterized in that the gel fraction measured in chloroform is 75% or more.

    The resin composition according to claim 11 is characterized in that the crystallinity by wide-angle X-ray diffraction after treatment for 30 minutes at 110 ° C. in air is at most 0.9 as compared with the untreated product.

The resin composition according to claim 12 is characterized in that an average coefficient of thermal expansion up to 30-120 ° C. is at most 5 × 10 ⁻⁴ .

The resin composition of claim 13 is characterized in that the light transmittance at 550 nm of the resin composition when heated at 130 ° C. for 30 minutes is at least 70% in terms of 0.2 mm thickness.
The resin molded body according to claim 14 is formed by molding the resin composition according to any one of claims 1 to 13 by at least one method selected from extrusion molding, injection molding, transfer molding, sheet mold molding, and powder molding. It is characterized by comprising.

      The resin molded body according to claim 15 is a particulate pellet.

      The resin molded body according to claim 16 is an extruded sheet.

      The resin molded body according to claim 17 is an inflation film.

      The resin molded body according to claim 18 is a fibrous material.

      The resin molded body according to claim 19 is a box-shaped object.

      The resin molded body according to claim 20 is a tubular product.

      The resin molded body according to claim 21 is a hollow particulate material.

      The resin molded body according to claim 22 is a foam molded body.

      The resin molded body according to claim 23 is an injection molded body.

      The resin molded body according to claim 24 is characterized in that the molded body has a light transmittance of 550 nm in terms of 0.2 mm thickness of at least 85%.

      The resin molded body according to claim 25 is characterized in that when the molded body is heat-treated in air at 130 ° C. for 30 minutes, the light transmittance at 550 nm in terms of 0.2 mm thickness of the molded body is at least 65%. .

The resin molded body according to claim 26 is characterized in that the thermal expansion coefficient of the molded body at 30 to 120 ° C. is at most 5 × 10 ⁻⁴ .

The resin molded body according to claim 27 is characterized in that a thermal expansion coefficient at 30-120 ° C. of a molded body obtained by heat-treating the molded body in air at 130 ° C. for 30 minutes is at most 0.5 × 10 ⁻⁴ . .

      The method for producing a resin molded body according to claim 28 is a method of performing high energy ray irradiation after melt molding a polylactic acid resin composition containing a polymer and / or prepolymer, a polyfunctional crosslinking agent, and inorganic fine particles. It is characterized by.

      The method for producing a resin molded body according to claim 29 is characterized in that the polymer and / or prepolymer is polylactic acid.

      The method for producing a resin molded body according to claim 30 is a method of melting and extruding a polylactic acid resin composition to form pellets, then irradiating the pellets with high energy rays, and further extruding, injection molding, transfer molding, powder molding. It is characterized by molding by at least one method selected from the following.

      The method for producing a resin molded body according to claim 31 includes: a polylactic acid resin composition is melt-extruded to form pellets, and the pellets are irradiated with high energy rays, and further from extrusion molding, injection molding, transfer molding, and powder molding. It is characterized in that it is molded by at least one selected method and then irradiated again with high energy rays.

  The method for producing a resin molded body according to claim 32 is characterized in that the dose of high energy ray irradiation performed after the second time is at least 20 KGy.

  The method for producing a resin molded body according to claim 33 is characterized in that after high-energy ray irradiation, a treatment for further deforming at least 0.1% cold or hot is performed.

    As described above, the resin composition and the resin molded body of the present invention are industrially easy and inexpensive to use materials having physical properties and performance such as strength and elastic modulus and moldability while maintaining transparency that has been difficult until now. In addition, unlike conventional cross-linked structures, there is no generation of VOCs (volatile organic compounds), bleed-outs, or discoloration from the molded body because no cross-linking aids or catalysts are used. This technology is extremely useful for industrial development and social development and for providing safe and stable products. In particular, to improve the hardness, chemical and physical stability of these parts by using them on the surface parts of electronic and electrical equipment casings, display windows, and various machine parts that require heat resistance and transparency. There is an effect that can be.

  Embodiments of the present invention will be described below, but the present invention is not limited thereto.

    The polymer of the present invention refers to a polymer having moldability and comprising a combination of specific monomers and having an average molecular weight of about 10,000 or more. For example, polyolefins such as polyethylene and polypropylene, or copolymers thereof. , Aromatic polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate or copolymers thereof, vinyl polymers such as polystyrene, polyvinyl chloride, or copolymers thereof, polymethyl methacrylate, polymethyl acrylate Acrylic polymers such as, or copolymers thereof, aliphatic polyamides such as nylon-6, nylon-66, nylon-610, or copolymers thereof, polycarbonates such as polycarbonate A, polycarbonate F, or the like Copolymer, poly Polyphenylenes such as acetal, polyphenylene ether and polyphenylene oxide or copolymers thereof, polyimides or copolymers thereof, aromatic polyamides, silicone polymers or copolymers thereof, polytetrafluoroethylene, polyperfluoro Fluoropolymers such as ethylene propylene or copolymers thereof, polyurethanes or copolymers thereof, polylactic acid or copolymers thereof, polycaprolactone, polybutyl succinate, polybutylene succinate adipate, etc. Degradable polymers or copolymers thereof, or mixtures of oligomers and monomers having a molecular weight of less than 10,000.

        Which of the above exemplified polymers is used is not particularly limited as long as it is selected depending on the application, purpose, molding method and the like. For example, when transparency and surface hardness are required, polystyrene or a derivative thereof, polymethyl methacrylate or a derivative thereof, polyethylene terephthalate, polyethylene naphthalate or a derivative thereof, modified nylon, polycarbonate, or a derivative thereof can be employed. For example, when biodegradation is required, polylactic acid or its derivative, polycaprolactone or its derivative, polybutylene succinate or its derivative, polyamino acid or its derivative, polyglycolic acid or its derivative, polyhydroxybutyrate, polyhydroxy Natural polymers such as valates, starch, gelatin, hyaluronic acid, chitosan / chitin, etc., or derivatives thereof can be used. The prepolymer means a polymer having a low degree of polymerization of the above-mentioned polymer, and usually has a molecular weight of less than 10,000 at most. Of the above exemplified polymers, polylactic acid is most preferred.

The polylactic acid resin used in the present invention may contain other commonly used polylactic acid, such as L-lactic acid or D-lactic acid, and other monomers, oligomers, or other polymers copolymerizable therewith, When the L-lactic acid component or the D-lactic acid component is lower than 70 mol%, the crystallinity of polylactic acid is lowered, and the heat resistance and solvent resistance when molded, mechanical properties such as strength, elongation, and elastic modulus are lowered. There may be limitations in molding methods, molding conditions and applications. In addition, since polylactic acid containing D-lactic acid as a main component has poor biodegradability, it is preferable that polylactic acid containing an L-lactic acid component is at least 70 mol%, preferably at least 80 mol%, more preferably at least 90 mol%. L-lactic acid resin. (Hereinafter abbreviated as polylactic acid.)
Polylactic acid is a ring-opening polymerization of a dimer (lactide) of lactic acid (for example, JP 07-300520 A, JP 07-305227 A, JP 7-305228 A, etc.) or dehydration condensation of lactic acid. It can be obtained by polymerization (for example, JP-A-6-122148, JP-A-7-133344, JP-A-7-228675, etc.), and the weight average molecular weight (Mw) is usually at least 100,000, preferably Is at least 120,000, more preferably 130,000-250,000. When the molecular weight is less than 100,000, sufficient strength and moldability cannot be expected. On the other hand, when the molecular weight is 250,000 or more, the moldability is not sufficient and the use of a plasticizer or the like is required and there is a practical problem. There is. The molecular weight can be easily adjusted by the initiator concentration, the catalyst amount, the polymerization time, or the like during the polymerization of polylactic acid.

    The amount and molecular weight of L-lactic acid in the polylactic acid resin may be selected within the above-mentioned range depending on the application, purpose, molding method and the like, and are not particularly limited. For example, when transparency and surface hardness are required, the amount of L-lactic acid is high, for example, 85 mol% or more, if necessary, 90% or more or 97% or more, and increase the molecular weight, for example, weight average A molecular weight of 150,000 or more is preferred. On the other hand, in order to improve the moldability, the molecular weight is preferably 180,000 or less, and the balanced molecular weight is 90,000 to 170,000.

  The polyfunctional cross-linking agent of the present invention is a compound that can be cross-linked with high energy rays, and needs to have two or more functional groups that generate radicals with high energy rays. As such a crosslinking agent, for example, atoms such as carbon, oxygen, nitrogen, sulfur, silicon, and phosphorus have a bonding form, and of course there are single (single) bonds, but carbon / carbon Bond, carbon / nitrogen bond, carbon / oxygen bond, oxygen / oxygen bond, oxygen / nitrogen bond, carbon / sulfur bond, sulfur / sulfur bond, nitrogen / nitrogen bond, carbon / phosphorus bond, oxygen / phosphorus bond, etc. You may have a double bond or a triple bond. Specific examples of such compounds include double bonds, preferably a plurality of such compounds, which are easily cleaved with high energy rays and easily generate radicals. For example, polyfunctional isocyanates, polyfunctional isocyanates, Examples include acrylates, polyfunctional methacrylates, polyfunctional epoxies, polyfunctional isocyanurates, and dienes. These may be used alone or in a mixture of two or more, but other crosslinkable compounds are also used. I can do it. Specific examples of these compounds include 1,2-diisocyanate ethane, 1,4-diisocyanate butane, 2,4-diisocyanate toluene (2,4-TDI), 2,6-diisocyanate toluene (2 , 6-TDI), 3,5-diisocyanate-o-xylene, 4,6-diisocyanate-m-xylene, 2,6-diisocyanate-p-xylene, 2,4-diisocyanate-1-chlorobenzene, 2,4- Diisocyanate-1-nitrobenzene, 2,5-diisocyanate-1-nitrobenzene, 4,4′-diphenylmethane diisocyanate (MDI), 2,4′-diphenylmethane diisocyanate, 3,3′-diphenylmethane diisocyanate, isophorone diisocyanate, cyclohexane diisocyanate , Ethylene oxide (EO) modified bisphenol A di (meth) acrylate, 1,4-butanediol di (meth) acrylate, diethylene glycol di (meth) acrylate, dipentaerythritol hexa (meth) acrylate, dipentaerythritol monohydroxypenta ( (Meth) acrylate, caprolactone modified dipentaerythritol hexa (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, polyethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, EO modified Trimethylolpropane tri (meth) acrylate, propylene oxide (PO) modified trimethylolpropane tri (meth) acrylate , Tris (acryloxyethyl) isocyanurate, tris (methacryloxyethyl) isocyanurate, 2,4-diisocyanatotoluene, 2,6-diisocyanatotoluene, triallyl cyanurate, triallyl isocyanurate, diallyl phthalate, Examples include diallylbenzene phosphonate.

  In the present invention, since a cross-linking reaction of a compound having a polyfunctional group is performed using a polyfunctional cross-linking agent, there is no need for a curing agent or heating in the reaction as shown in the above-mentioned conventional patent publications. Therefore, it is possible to irradiate high energy rays without selecting a process such as monomer, polymerization, molding, or the subsequent process. That is, for example, in the case of a thermal cross-linking reaction type, a cross-linking reaction occurs at the time of molding, the molding accuracy decreases, a sufficient cross-linking structure cannot be obtained, and the target performance cannot be obtained, or the reaction occurs in the molding machine. If the process proceeds too much, problems such as cross-linking and clogging of the resin in the molding machine are assumed. Since the present invention can completely separate the molding and the crosslinking, the target performance can be obtained without such trouble.

  The amount of the above-mentioned compound may be selected according to the purpose and performance, but is usually at least 3 parts by weight, preferably 5 parts by weight, more preferably 5-40 parts by weight, particularly preferably 100 parts by weight of the polylactic acid resin. Is 10-30 parts by weight. When the amount is less than 3 parts by weight, the formation of a crosslinked structure by high energy rays is insufficient, the transparency is excellent, and the performance with excellent heat resistance cannot be obtained. On the other hand, when the amount exceeds 40 parts by weight, not only the effect reaches saturation, but also an unreacted compound remains, which may cause a decrease in heat resistance and mechanical properties.

The inorganic fine particles contained in the resin composition of the present invention preferably have a maximum length of 200 nm (0.2 μm), more preferably at most 150 nm (0.15 μm), particularly preferably at most 100 nm (0.1 μm). For example, AL ₂ O ₃ , ZnO ₂ , TiO ₂ , Al (OH) ₃ , Mg (OH) ₂ , SiO ₂ , AL ₂ O ₃ , MgO, Y ₂ O ₃ , MgAl ₃ O ₄ , BeO, ZnO, Zr ₂ O ₃ , TiO _{2 and} other oxide fine particles, TiC, SiC, TaC, Mo ₂ C main component nitride fine particles, diamond-like carbon fine particles, carbon black, carbon nanotubes, fullerenes, carbon fiber fine particles, etc. Fine cleaved clay minerals such as fine particles, mica, sericite, montmorillonite, asbestos, synthetic cleaved minerals such as synthetic mica, synthetic smectite, or saponite, finely pulverized glass or plate glass fine particles, fine particles of glass fibers Glass fine particles, gold, silver, platinum, copper, nickel Etc. fine metal particles, or fibrillated cellulose, cotton, kenaf, natural resources asbestos etc., etc. can be exemplified. These fine particles may be used according to the purpose.For example, for sheet materials and box materials having excellent transparency, AL ₂ O ₃ , ZnO ₂ , TiO ₂ , Al ( OH) ₃ , Mg (OH) ₂ , SiO ₂ , AL ₂ O ₃ , MgO, Y ₂ O ₃ , MgAl ₃ O ₄ , BeO, ZnO, Zr ₂ O ₃ , TiO _{2 and} other fine oxide particles, mica, selenium It is preferable to use naturally cleaved clay minerals such as site, montmorillonite and asbestos, and synthetic cleaved minerals such as synthetic mica, synthetic smectite, and saponite. In particular, AL ₂ O ₃ , ZnO ₂ , TiO ₂ , Al (OH) ₃ , Mg (OH) ₂ , SiO ₂ , AL ₂ O ₃ , MgO, MgAl ₃ O ₄ , BeO, ZnO, Zr ₂ O ₃ , TiO Metal oxide fine particles such as ₂ and cleaved minerals such as montmorillonite, synthetic smectite, and saponite are preferable because the surface treatment of the organic compound can be performed on the fine particles in order to increase the affinity for polylactic acid. The organic compound is not particularly limited as long as it increases the affinity for polylactic acid, but usually a silane coupling agent or a titanium coupling agent can be used, for example, vinyltrimethylsilane, vinyltris (β-methoxyethoxy) silane, β- (3,4 epoxy cyclohexyl) ethyltrimethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-chloropropylmethoxysilane, γ- Aminopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-gridoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, β-3,4-epoxycyclohexylethyltrimethoxysilane, etc. or montmorillonite, smectite etc For cleaving minerals, low-molecular compounds having a quaternary ammonium group, such as octyltrimethylammonium chloride, decyltrimethylammonium chloride, lauryltrimethylammonium chloride, silylyltrimethylammonium chloride, cetyltrimethylammonium chloride, stearyltrimethyl Ammonium chloride, octyltriethylammonium chloride, decyltriethylammonium chloride, lauryltriethylammonium chloride, cisyltriethylammonium chloride, cetyltriethylammonium chloride, stearyltriethylammonium chloride, or their bromides, or other alkyls Ammonium halides can be suitably used.

  Although the effect of the inorganic fine particles is not exactly known, in a system that does not contain inorganic particles, the heat resistance and transparency of the resin composition and the molded body are insufficient even when a large amount of high energy rays are irradiated. This is because the cross-linking of polylactic acid molecules is advanced, but the effect of controlling the mobility with respect to the temperature of the molecule is small. That is, the molecular motion is generated from a very small range at the atomic and molecular level such as a change in bond angle and a rotational motion between adjacent carbon atoms, and it is impossible to limit all of them. By including the inorganic fine particles specified in the present invention, it can be presumed that the heat resistance and the transparency can be improved by dispersing in the molecule so that this just restricts the mobility of the molecule between the crosslinking points.

  The shape of the fine particles used here is not particularly limited as long as it does not adversely affect the above-described effect, but a spherical shape, an elliptical spherical shape, a plate shape, a rod shape, a tube shape, a honeycomb shape, or the like can be suitably used. . Other polymer light stabilizers, heat stabilizers, colorants, pigments, other moldability improvers, heat stabilizers, light-resistant stabilizers, and if necessary, dyes, pigments and the like can be used as necessary.

    High energy rays used in the present invention refers to those having sufficient energy to break some bonds of the above functional groups, for example, radiation such as electron beams, α rays, β rays, γ rays, Or it can raise ultraviolet rays, X-rays, synchrotron radiation X-rays, etc. with short wavelengths.

    If the radiation dose is, for example, γ rays, the process is processed even in a portion surrounded by a material such as a large molded body, composition, or metal having a very large transmittance, and can be used in various fields. . In addition, the penetration power and dose of electron beam irradiation can be adjusted by the accelerating voltage of the electron beam, and it is possible to process a large area relatively easily in terms of equipment. It is suitable for processing, has a short processing time, is relatively low in processing cost, and is highly practical. The irradiation dose of high energy rays is usually at least 10 kGy, preferably at least 20 kGy, more preferably 30-500 kGy, particularly preferably 40-300 KGy, although high dose processing of 1 MGy or more is possible depending on the purpose. It may be necessary for a long time, or the temperature may rise during processing, resulting in deterioration of physical properties or change in shape.

    The cross-linked structure generated by the action of high energy rays on these functional groups may be a cross-linked structure in the molecule or a pre-polymer molecule, but is preferably mainly composed of intermolecular cross-links. It is preferable to do. In the case where the main component is intermolecular crosslinking, a crosslinked product that is not dissolved by a solvent that dissolves the polymer or prepolymer can be obtained. Such a structure has a constant elastic modulus without fluidization even at a temperature equal to or higher than the melting point of the uncrosslinked body in a dynamic viscoelasticity measurement in which, for example, a constant tensile vibration is applied and its mechanical response is observed (FIGS. 2 to 3). reference). 2 to 3 are graphs showing temperature changes in storage elastic modulus and tangent loss of polylactic acid according to an embodiment of the present invention, respectively (both horizontal axis: temperature (° C.), vertical axis 1: Storage elastic modulus E ′ (MPa), Loss elastic modulus: E ″ (MPa), Vertical axis 2: Tangent loss tanδ).

    That is, it can be used without being deformed even under actual use conditions, and shows that the heat resistance has been improved, and has practically great utility. Such characteristics depend on the molecular weight between the crosslinking points, and the smaller the molecular weight, the greater the improvement in heat resistance. Therefore, the molecular weight between cross-linking points needs to be optimized depending on the intended use, performance and molding method. In particular, when maintaining transparency and improving heat resistance, chemical resistance, mechanical properties, etc., the molecular weight between cross-linking points is preferably such that spherulites are not generated by crystallization between cross-links. In this determination, the crosslinked product is heated to a temperature higher than the glass transition temperature of the uncrosslinked polymer and determined by the formation of spherulites. For example, it can be determined that ordinary crystalline polyethylene is heat-treated at 110 ° C. for about 10 minutes, and if it whitens, spherulites are generated, and if it remains transparent, it is determined that spherulites are not generated. In this case, the size of the majority of the spherulites produced is below the wavelength of light, preferably below 300 nm, more preferably below 200 nm, and most preferably below 100 nm. The size of the spherulite can be easily measured by a deflection microscope, an electron microscope or a light scattering method.

  Therefore, the crystallinity of the polylactic acid (the ratio of crystallinity defined by the following formula (1)) when subjected to heat treatment at 110 ° C. for 30 minutes for the crystallization conditions of the polylactic acid composition of the present invention is the control of the uncrosslinked treatment. Although it may be usually lower than the product, it is still preferably at most 0.9, more preferably 0.2 to 0.85. When this ratio is higher than 0.9, when it is crystallized by sufficient heat, it often loses transparency, and when it is lower than 0.2, the crystallization region decreases and the heat resistance may decrease. Control of transparency becomes easy. However, depending on the purpose and application, this value may be 0.2 or less. Here, evaluation of crystallinity can be performed by a commonly used evaluation method, but an X-ray diffraction method capable of measuring a sample as it is is preferable. As an X-ray diffraction method, for example, with reference to Masao Kadoto, Masato Kasai, “Polymer X-ray diffraction” (1968), the diffraction intensity of the amorphous part is subtracted from the total diffraction intensity, and the following formula (1 ) To obtain the crystallinity χc (%). For the measurement, it is necessary to select an appropriate method depending on the properties of the sample. For example, the powder method or the rotating sample method is a preferred method without being affected by the specific orientation of the sample.

Crystallinity χc (%) = (ΣIc) / (ΣI) x 100 (1)
However, I: Total diffraction intensity Ic: Diffraction intensity by crystal part The polylactic acid of the present invention is excellent in transparency since it has the above composition and structure. For example, the transmittance of light at 550 nm converted to a thickness of 0.2 mm is preferably at least 85%, more preferably at least 90%, and particularly preferably at least 95%. If the transmittance does not reach 85%, it may be difficult to apply to applications that require transparency and cleanliness. Further, in order to eliminate the influence on the transparency of heat received during use, the light transmittance in terms of 0.2 mm thickness after heating at 130 ° C. for 30 minutes, preferably at least 65%, more preferably at least 70%, Particularly preferred is a polylactic acid resin composition that is at least 75%. In a system that uses ordinary polylactic acid resin or radiation crosslinking aid but does not use inorganic fine particles, heating at 130 ° C for 30 minutes makes it completely opaque (devitrified) due to crystallization and spherulite formation, limiting its application In many cases, the quality during use is reduced, or the mechanical properties are reduced due to crystallization and spherulite formation.

    The degree of crosslinking varies depending on the application / purpose or processing method, but when immersed in a good solvent for the polymer at room temperature for 24 hours, the gel fraction (%) defined by the following formula (2) is usually at least 30%. %, Preferably at least 35%, more preferably at least 40%. For example, when aiming at a composition excellent in water absorption and ball oil properties, a relatively small gel fraction is preferable, while a molded body with improved heat resistance, strength and elastic modulus is preferably high. When the molded body has transparency to improve heat resistance, strength, elastic modulus, etc., the degree of crosslinking is further increased, and the gel fraction is usually at least 60% or more, preferably 75% or more, more preferably 85% or more. Most preferably, it is 90% or more. Of course, even if outside this range, there is a possibility of sufficient use depending on the intended performance and usage, so the above numbers are only a guide.

Gel fraction (%) = (W0-W1) / W0 × 100 (2)
However, W0: initial sample weight W1: Indicates the sample weight after collecting the undissolved sample after immersion for 24 hours and removing the solvent after drying.
The composition of the present invention is characterized by high heat resistance due to its high optical purity in polylactic acid, a crosslinked structure, and the like. The evaluation standard for heat resistance can be judged qualitatively by observing the deformation state of the specimen at a constant temperature, but quantitatively, the linear expansion coefficient α of the sample by TMA (Mechanical Thermal Analysis) Based on. This shows how much the sample is stretched or shrunk in the direction of stress in a certain temperature range by increasing the temperature by applying a certain force to the sample. Or it can judge also from the temperature dependence of the storage elastic modulus (E ') of the dynamic viscoelasticity normally used for the physical-property measurement. A feature of dynamic viscoelasticity evaluation is that results with good reproducibility are obtained in a short time. The linear expansion coefficient α is defined by the following equation (3).
Linear expansion coefficient α = (L-Lo) / (Lo x (T-To)) (3)
Lo: Length of sample at reference temperature (mm) L: Length of sample at measurement temperature (mm)
To: Reference temperature (30 ° C) T: Measurement temperature (120 ° C)
The composition of the present invention has a coefficient of linear expansion up to 30-120 ° C. represented by the above formula, usually at most 5 × 10 ⁻⁴ , preferably at most 1 × 10 ⁻⁴ , more preferably 5 × 10 ⁻⁵ . . This heat resistance can be manifested by restraint of molecular motion due to cross-linking between molecular chains. Alternatively, when the composition is heated at a temperature of 130 ° C. for 30 minutes, the polylactic acid composition has a linear expansion coefficient up to 30-120 ° C., usually at most 1 × 10 ⁻⁴ , preferably at most 5 × 10 ⁻⁵ , More preferably, it is 1 × 10 ⁻⁵ , which indicates that the thermal deformation is very small and the heat resistance is high.

  The resin composition of the present invention can be molded by a normal molding method. For example, a polylactic acid resin composition containing polylactic acid, a polyfunctional crosslinking agent and inorganic fine particles can be molded by a normal molding method such as extrusion molding, injection molding, transfer molding, sheet molding, powder molding, etc. The molded article of the present invention is obtained by irradiating with high energy rays after molding. Examples of the molded body include a molded body by injection molding, pellets extruded and cut into granules, a sheet by extrusion molding, a film, a rod-shaped body, a tubular body, a net-shaped body, and the like.

These molded products are irradiated with high energy rays in order to improve transparency, heat resistance or mechanical properties. The type of high-energy radiation may be selected according to the structure, size, and purpose of the molded body, but in general, a molded body that includes or is surrounded by a three-dimensional molded body or a metal member. Gamma rays having a large penetrating power are preferred. On the other hand, irradiation of electron beams capable of wide processing is preferred for films, sheets, fibers, cloths, coatings and the like. In this case, the irradiation dose is usually at least 10 kGy, preferably at least 20 kGy, more preferably 30-500 kGy, and particularly preferably 40-300 KGy. Depending on the purpose, a high dose treatment of 1 MGy or more is also possible. By doing so, the moldability, heat resistance and mechanical properties can be further improved. For example, the molded article of the present invention is excellent in transparency, and the light transmittance at 550 nm converted to a thickness of 0.2 mm is preferably at least 85%, more preferably at least 90%, and particularly preferably 95%. Further, the molded body of the present invention is excellent in heat resistance, and the transmittance of 550 nm light in the molded body heated in air at 130 ° C. for 30 minutes is preferably 65%, more preferably in terms of 0.2 mm thickness. Is 70%, particularly preferably 75%. On the other hand, in a molded body that does not satisfy the requirements of the present invention, polylactic acid is crystallized by heating to become white (devitrified), and the transparency is greatly reduced. In addition, since the molecular structure of the molded body has a cross-linked structure, the deformation resistance is also large. For example, when the molded body is heated from 30 ° C to 120 ° C at a rate of 5 ° C / min with a load of MPa The deformation amount in a certain direction can be expressed by the linear expansion coefficient of the above-described formula (3), but the molded body of the present invention is preferably at most 5 × 10 ⁻⁴ , more preferably. By having such a small linear expansion coefficient, the thermal stability of the molded body is greatly improved. Further, preferably, when the molded body of the present application is heated in air at 130 ° C. for 30 minutes, the linear expansion coefficient measured in the same manner of this molded body is preferably 0.5 × 10 ⁻⁴ , more preferably 1 × 10 ⁻⁵ . This value indicates that the heat resistance is equivalent to that of super engineering plastics, and it is possible to greatly expand the uses of the polylactic acid molded body. A reduction in the linear expansion coefficient can be achieved to some extent even in systems that do not contain inorganic fine particles, but it is not always sufficient, and the crosslink density with high energy rays is inevitably uneven, and large spherulites are generated during crystallization. Therefore, whitening (devitrification) cannot be avoided.

  When the molded body is a pellet, it is molded so that it can be used for normal melt molding. However, since it can be irradiated with higher energy rays after molding, the dose applied to the pellet does not need to be too high. Is at least 5KGy, preferably 10-50KGy. Even at such doses, the melt viscosity of polylactic acid can be raised to improve moldability, and the formation of a partially crosslinked structure can improve the thermal or mechanical stability of the molded body. The molded body in this case includes a sheet or film by T-die method, a film or split yarn by inflation method, a cylindrical molded body by extrusion method, a rod-shaped molded body or net-shaped molded body, and various molded bodies by injection molding method. These molded bodies can be used as they are, but they can be further irradiated with high energy rays to improve transparency, heat resistance, mechanical properties, dyeability, and the like. The irradiation dose in this case is usually at least 20 KGy, preferably 30 kGy, more preferably 40-100 kGy.

  Such a molded body is preferably provided with a strain of 0.1%, more preferably 0.3%, particularly preferably 0.5-5%, even after being irradiated with high energy rays and cold or hot below the crystallization temperature of polylactic acid. Although the detailed reason is unknown, physical properties such as dimensional stability or transparency can be further improved. It is necessary to select the optimum strain depending on the shape of the molded body, but for example, in the case of a sheet-like material, the rolling is about 0.5% with a cold rolling roller or a hot roller heated to 80 ° C at most. Dimensional stability and transparency are improved by cold drawing or hot drawing at a temperature of at most 80 ° C. This is presumably because the cross-linked composition or molded product can be transformed into a structure in which uniform strain is applied to the entire material by applying strain at a temperature at which molecular motion is not sufficient.

  The application of the resin composition of the present invention can be used in the field where a polylactic acid resin has been used, the field where a transparent resin has been used or the field where biodegradability is required, and is not particularly limited. For molded products with low gel fraction, various applications utilizing water swellability and oil swellability, and for those with high gel fraction, heat resistance, hardness, dimensional stability, transparency and chemical stability are utilized. A shaped body is conceivable. In particular, a film or sheet excellent in heat resistance and strength having very minute surface irregularities, a film or various molded articles excellent in transparency and dimensional stability, window materials, molded articles excellent in organic solvent retention and porosity Examples of such materials include non-conventional heat resistance, mechanical properties such as strength and elastic modulus, chemical resistance, and the like.

 Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

[Examples 1 to 4]
100 parts by weight of a pellet of polylactic acid resin (manufactured by BM Co., Ltd.) having a weight average molecular weight (Mw) of 152,000 and a melting point of 170.8 ° C. obtained by ring-opening LL-lactide was 8 in a 125 ° C. ventilator. Dried for a long time, sprinkled a portion (20 parts by weight) of triallyl isocyanurate (TAIC: manufactured by Aldrich) in the amount shown in Table 1 in a glove box dehumidified by flowing N ₂ gas, and evenly on the pellet surface It was mixed so that TAIC adhered. Next, the remaining polylactic acid, TAIC-treated polylactic acid, and 10 parts of organic smectite (CEN Chemical Co., Ltd. SEN) were thoroughly mixed in a sealed glass bottle and supplied to a biaxial kneader. The supply tank and feed port of the twin-screw kneader flowed N ₂ gas to eliminate the influence of air. The temperature of the twin-screw kneader is C1 / C2 / C3 / C4 / D = 140/190/200/210/180 (° C). After melt-kneading, 30mm wide and 0.5mm thick from the T die attached to the tip of the kneader. The sheet was horizontally extruded and cooled with a calendar roll to obtain a transparent polylactic acid film sheet (amorphous state). Next, this film sheet was cut to a length of 15 cm, placed in a polypropylene bag of aluminum ply, and the air inside was sufficiently substituted and removed with nitrogen, and γ rays (10 kGy / hr) using Co ⁶⁰ as the radiation source are shown in Table 1. The indicated dose was irradiated. The mechanical properties were evaluated by punching a film sheet into a dumbbell shape with a die and measuring it in an atmosphere of 25 ° C. and 60% relative humidity using an autograph AG-5000E manufactured by Shimadzu Corporation. The pulling speed was 100%.

[Comparative Example 1]
A comparative film sheet was obtained by performing the same operation as in Example 1 except that the polyfunctional crosslinking agent was 0 parts by weight.

  Each film sheet of Examples 1 to 4 and Comparative Example 1 was cut into a width of 15 mm and a length of 50 mm and placed in a ventilated dryer heated to 110 ° C. for 10 minutes, and the state was observed. The results are shown in Table 2. The sample of the comparative example started to be deformed and whitened (devitrified) immediately after being put into the dryer, and showed that the heat resistance and transparency were inferior.

Next, each sheet of Examples 1 to 4 and Comparative Example 1 was cut out to a width of 3 mm and a length of 5 mm, and 5 ° C./min from room temperature (25 ° C.) under N ₂ flow using a MTC1000 TMA apparatus manufactured by Mac Science. The temperature was increased at the rate of temperature increase, and the deformation of the sample was automatically recorded. The results were analyzed and Table 3 shows the average linear expansion coefficient from room temperature to 120 ° C. FIG. 1 shows TMA diagrams of No. 1 (Comparative Example 1), No. 4 (Example 3), and No. 5 (Example 4). It can be seen that the sample of the present invention has lower thermal deformation than the sample of Comparative Example 1. In particular, No. 4 (Example 3) and No. 5 (Example 4) are extremely stable.

[Examples 5 to 10]
The polylactic acid resin and triallyl isocyanurate used in Example 1 and the organically synthesized synthetic smectite (SPN made by Co-op Chemical) at 180 wt. The mixture was melt-mixed at 15 ° C. for 15 minutes to obtain a three-component compound. Next, using this compound, a sheet of 0.2 mm was formed in a hot press at a temperature of 190 ° C. and a pressure of 20 MPa over 3 minutes.

  Next, the film was irradiated with 50 KGy of an electron beam as it was using a high voltage electron beam irradiation apparatus (NHV Corporation). Various physical properties were obtained using this sheet sample. The sheet physical properties were the same as in Example 1-4, and the light transmittance was determined by measuring the light transmittance of 550 nm (Ubest-50 manufactured by JASCO) after heat treatment of the irradiated sheet at 130 ° C. for 30 minutes. As a control for light transmittance, the transmittance of a 0.2-mm-thick polylactic acid single sheet was set to 100%. The results are shown in Table 4.

Example 11
The sheet after irradiation in Example 7 was press-compressed by about 2% by applying a force of 50 MPa at 50 ° C. below the glass transition point of polylactic acid (Tg = 57 ° C.). This was treated and evaluated as in Example 7. The strength is 76 MPa, the elongation is 15%, the elastic modulus is 3410 MPa, the light transmittance of this compressed sheet after treatment at 130 ° C for 30 minutes is 85.7%, and the linear expansion coefficient at 30-120 ° C is 2.92 × 10-5. The similar linear expansion coefficient of the sheet before heat treatment was 4.71 × 10 −5. Moreover, the sheet | seat of the comparative example 2 and Example 7 was cut out to width 5mm and length 30mm, and dynamic viscoelasticity was measured in the uniaxial extension mode (use apparatus: Rheogel-E4000 frequency 100Hz made from UBM Co., Ltd.). Comparative Example 1 shows that flow deformation occurred when the temperature exceeded 180 ° C., but in Example 7, the heat resistance was improved to nearly 300 ° C.

Example 12
Comparative Examples 1, 3, and 4 Each of Examples 6, 7, 8, 9, and 10 having a thickness of 0.5 mm, a width of 10 mm, and a length of 60 mm is held at 130 ° C. The deformation state of the sheet sample after being left in the air for 30 minutes was observed. This evaluation corresponds to the heat distortion resistance. As a result, in Comparative Examples 1, 2, and 3, it was impossible to completely measure the sagging. In Comparative Example 4, it was 12 mm, whereas in Examples 6, 7, 8, 9, and 10, changes of 7 mm, 5 mm, 5 mm, 3 mm, and 3 mm were observed, respectively. It can be seen that the heat resistance is much higher. In addition, after the sample was first heat-treated at 120 ° C. for 20 minutes and then tested in the same manner, the deformation amounts were 5 mm, 6 mm, 5 mm, and 9 mm for the comparative examples 1, 2, 3, and 4, respectively 7 mm for the examples. It became 5mm, 5mm, 3mm, 3mm. Comparative Example 1-4 was crystallized and whitened (devitrified), but the sheet of the example clearly showed the high commercial value of the present invention with almost no change in transparency.

Example 13
The polylactic acid resin composition obtained in Example 9 was kneaded at 200 ° C. using a biaxial kneader (Technobel Co., Ltd.) to produce pellets having a diameter of 3 mm and a length of 4 mm. Using this pellet, it was melted at 210 ° C. by a multifilament spinning machine (manufactured by Chubu Chemical Machinery Co., Ltd.), extruded into the air, and spun to obtain an undrawn yarn. Subsequently, the undrawn yarn was stretched 4 times at a stretching temperature of 73 ° C. and continuously subjected to a constant length heat treatment at 150 ° C. to finally obtain a transparent fiber of 105 dTex / 38fil. The physical properties of this fiber were 3.2 g / dTex and an elongation of 38%. The drawn yarn was wound around a metal frame, the length was fixed, put in a polypropylene bag, the air inside was replaced with nitrogen, and γ rays were irradiated with 25 kGy using Co ⁶⁰ as a radiation source. Transparency was maintained even when the irradiated fiber was heated in air at 130 ° C. for 30 minutes, but the fiber of the resin of Comparative Example 1 was whitened by crystallization (devitrification). did.

Example 14
100 weight each of L-lactic acid / D-lactic acid = 75/25 (mol%) polylactic acid resin and triallyl isocyanurate, organic synthetic smectite (CEN Chemical Co., Ltd. SEN) and cellular as effervescent agent 30 parts by weight, 30 parts by weight, 5 parts by weight, and 5 parts by weight were melt-kneaded at 190 ° C for 30 minutes using a lab plast mill (Lab Kneader Mill TDR100-500 × 3 type manufactured by Toshin Co., Ltd.) to obtain a uniform composition. .
Subsequently, this composition was irradiated with γ rays at 10 kGy in the same manner as in Example 12. Next, the irradiated resin is put into a disk-shaped press container, heated to 230 ° C. to sufficiently decompose the foaming agent, and then decompressed to slowly inflate about 3 times, and then rapidly cooled to obtain a polylactic acid foam. It was. A foam having uniform fine foaming and a foam having sufficient strength were obtained.

[Examples 15 to 17]
Silane coupling agent (manufactured by Shin-Etsu Silicone, 3-glycidoxypropyl) having a terminal epoxy group as a multifunctional crosslinking agent in a methanol dispersion of silica fine particles with an average particle size of 20 nm (Nissan Chemical, silica concentration%) Trimethoxysilane) was added at 1.5% by weight per silica fine particle and reacted at room temperature for 17 hours. Subsequently, it was mixed and dissolved in polylactic acid (Tm = 171.5 ° C. Mw = 13.5) dissolved in dioxane to obtain a polylactic acid solution in which silica fine particles were uniformly dispersed. The solution had a slight bluish transparency. This solution was cast on a glass plate using a spiral coater (Matsuo Sangyo No.80) and dried on a hot plate at 60 ° C. for 10 minutes to evaporate methanol. A transparent and uniform sheet having a thickness of 50 μm was obtained. This sheet is put into a polypropylene bag with aluminum foil, the air inside is replaced with nitrogen, and γ-rays (10 kGy / hr) with Co ⁶⁰ as the radiation source are each irradiated with the doses shown in Table 5, and a crosslinked structure is formed in the sheet. Was generated.

[Comparative Example 5]
A comparative sheet was formed in the same manner as in Example 15 except that the silica fine particles and the multifunctional crosslinking agent were not added.

[Comparative Example 6]
A comparative sheet was formed by performing the same operation as in Example 15 except that the multifunctional crosslinking agent was not added.
Table 5 shows the properties of various sheets. It can be seen that a product having a crosslinked structure is excellent in solvent resistance, heat resistance and dimensional stability.
Further, when the obtained sheet was allowed to stand at 110 ° C. for 10 minutes at which polylactic acid crystallizes, Comparative Example 6 turned considerably white. This means the production of spherulites above visible light. On the other hand, in Examples 15 to 17, the transparency was considerably improved. This tendency tended to improve as the radiation dose increased.

Example 18
Montmorillonite (Kunimine Industries Kunipia F) was organically treated with cetyltrimethylammonium chloride (Sigma Aldrich Reagent) by a conventional method. The organic rate was 48%. Organized montmorillonite was dissolved in toluene and mixed with polymethacrylate (PMMA) (general grade manufactured by Mitsubishi Rayon Co., Ltd.) with a twin-screw kneader. The ratio of montmorillonite and PMMA was 7.5: 100 (weight cost). To the twin-screw kneader, PMMA was supplied from a pellet feeder and the montmorillonite solution was supplied by a gear pump. For kneading, a toluene solution of montmorillonite was directly added. At the same time, another extrusion was performed through a slit having a thickness of 0.3 mm and a width of 30 mm to obtain a transparent sheet having a thickness of 0.35 mm and a width of 30 mm. There is no toluene odor from the sheet, indicating that the toluene has been completely removed from the vent. The obtained sheet was irradiated with γ rays at 30 kGy in the same manner as in Example 1. As a control, a radiation-untreated sheet was used. The sheet of the present invention had a strength of 83 MPa, an elongation of 12%, and an elastic modulus of 2560 MPa.

[Comparative Example 7]
A sheet for comparison was obtained by performing the same operation as in Example 4 except that the γ-ray irradiation was not performed. The comparative sheet had a strength of 63 MPa, an elongation of 7%, and an elastic modulus of 1750 MPa.

    The polylactic acid composition of the present invention has a high degree of thermal stability, mechanical properties, transparency, solvent resistance, and moldability, and heat resistance and transparency, moldability, and chemical stability that have been difficult until now. Industrially used compositions or textile products that can be used effectively for sheets and films related to packaging materials that require frictional strength, sheets and cases for electronic and electrical equipment, display windows, various machine parts, etc. It can be easily obtained and is extremely useful for industry.

It is a graph which shows the TMA temperature change of the film sheet using the polylactic acid resin composition which concerns on one embodiment of this invention. It is a graph which shows the temperature change of the storage elastic modulus and tangent loss of polylactic acid which concerns on one embodiment of this invention. It is a graph which shows the temperature change of the storage elastic modulus and tangent loss of polylactic acid which concern on one embodiment of this invention.

Claims (33)

A resin composition comprising a polymer and / or a prepolymer, a polyfunctional crosslinking agent, and inorganic fine particles, and being treated by irradiation with high energy rays. The resin composition according to claim 1, wherein the polymer and / or the prepolymer is biodegradable. The resin composition according to claim 1 or 2, wherein the gel fraction is 60% or more. The resin composition according to any one of claims 1 to 3, wherein the polymer and / or prepolymer is polylactic acid. The resin composition according to claim 4, wherein polylactic acid is copolymerized with at least 70% or more of L-lactic acid. 6. The resin composition according to claim 4, wherein the polyfunctional crosslinking agent is contained at least 3 parts by weight per 100 parts by weight of polylactic acid. The resin composition according to any one of claims 4 to 6, wherein the maximum length of the inorganic fine particles is 200 nm or less. The resin composition according to any one of claims 4 to 7, comprising at least 5 parts by weight of inorganic fine particles per 100 parts by weight of polylactic acid. The resin composition according to any one of claims 1 to 8, wherein the high energy ray is irradiated with at least 10KGy. The resin composition according to any one of claims 1 to 9, wherein a gel fraction measured in chloroform is 75% or more. The resin composition according to any one of claims 1 to 10, wherein the degree of crystallinity by wide-angle X-ray diffraction after treatment at 110 ° C for 30 minutes in air is at most 0.9 as compared with an untreated product. 12. The resin composition according to claim 1, wherein an average coefficient of thermal expansion up to 30 to 120 ° C. is at most 5 × 10 ⁻⁴ . The light transmittance at 550 nm of the resin composition when the resin composition is heated at 130 ° C. for 30 minutes is at least 70% in terms of 0.2 mm thickness, 13. Resin composition. A resin molded body obtained by molding the resin composition according to any one of claims 1 to 13 by at least one method selected from extrusion molding, injection molding, transfer molding, sheet mold molding, and powder molding. The resin molded body according to claim 14, which is a particulate pellet. The resin molded product according to claim 14, which is an extruded sheet. The resin molded product according to claim 14, which is an inflation film. The resin molded product according to claim 14, which is a fibrous material. The resin molded product according to claim 14, which is a box-shaped product. The resin molded body according to claim 14, which is a cylindrical product. The resin molded product according to claim 14, which is a hollow particulate product. The resin molded body according to claim 14, which is a foam molded body. The resin molded body according to claim 14, which is an injection molded body. The resin molded body according to any one of claims 14 to 24, wherein the molded body has a light transmittance of 550 nm in terms of 0.2 mm thickness of at least 85%. The resin molded body according to any one of claims 14 to 24, wherein when the molded body is heat-treated in air at 130 ° C for 30 minutes, the light transmittance at 550 nm in terms of 0.2 mm thickness of the molded body is at least 65%. . 26. The resin molded body according to any one of claims 14 to 25, wherein a thermal expansion coefficient of the molded body at 30 to 120 ° C. is at most 5 × 10 ⁻⁴ . 27. The thermal expansion coefficient at 30-120 ° C. of a molded product obtained by heat-treating the molded product in air at 130 ° C. for 30 minutes is at most 0.5 × 10 ^−4. The resin molding as described. A method for producing a resin molded body, comprising subjecting a polylactic acid resin composition containing a polymer and / or a prepolymer, a polyfunctional crosslinking agent, and inorganic fine particles to melt molding, followed by irradiation with high energy rays. 29. The method for producing a resin molded body according to claim 28, wherein the polymer and / or prepolymer is polylactic acid. The polylactic acid resin composition is melt-extruded to form pellets, and then the pellets are irradiated with high energy rays and further molded by at least one method selected from extrusion molding, injection molding, transfer molding, and powder molding. The method for producing a resin molded body according to claim 29. The polylactic acid resin composition is melt-extruded to form pellets, the pellets are irradiated with high energy rays, further molded by at least one method selected from extrusion molding, injection molding, transfer molding, and powder molding, and then again high The method for producing a resin molded body according to claim 29 or 30, wherein energy beam irradiation is performed. 32. The method for producing a resin molded body according to claim 31, wherein the dose of the high-energy radiation performed after the second time is at least 20 KGy. 33. The method for producing a resin molded body according to any one of claims 28 to 32, wherein after the high energy ray irradiation, a treatment for further deforming at least 0.1% cold or hot is performed.