JP2008231365A - Polylactic acid-based resin composition and molded article made by molding the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition and its molded article having a high impact resistance-improving effect, having excellent mechanical strength, wet heat resistance and moldability, and being low in the dependency on a petroleum-based product. <P>SOLUTION: The resin composition comprises a crosslinked polylactic acid resin (A), a core shell-type graft copolymer (B), and a carbodiimide compound (C), wherein a mass ratio of (A) and (B), namely (A/B), is 70/30 to 99/1, and an amount of combined (C) is 0.1-5 pts.mass to a 100 pts.mass of the total of (A) and (B). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a crosslinked polylactic acid-based resin, a core-shell type graft copolymer, a resin composition comprising a carbodiimide compound, and a molded article obtained by molding the resin composition, and has mechanical strength, impact resistance, and heat and humidity resistance. The present invention relates to a resin composition having excellent moldability and low dependence on petroleum products, and a molded body obtained by molding the resin composition.

In recent years, biodegradable resins have attracted attention from the viewpoint of environmental conservation. Among them, polylactic acid is a crystalline polymer, has a higher melting point and higher heat resistance than other biodegradable resins. In addition, since it can be mass-produced, the cost is low and the utility is high. Furthermore, the raw material of polylactic acid can be produced using plants such as corn and sweet potato as raw materials, which can contribute to saving of depleted resources such as oil.
However, polylactic acid has not only a long molding cycle due to a low crystallization speed, but also has a drawback that the resulting molded article is inferior in mechanical strength, impact resistance, heat resistance and heat and humidity resistance. Therefore, as a means for solving such problems, for example, polylactic acid is blended with other petroleum-based biodegradable resins and hydrolysis inhibitors that are superior in performance to polylactic acid, so that the heat resistance and resistance of the molded product are improved. Studies have also been made to improve impact resistance and moist heat resistance (see, for example, Patent Document 1). However, even with this resin composition, the impact resistance was not sufficient. It is also known to blend a rubbery polymer such as an olefin copolymer with polylactic acid in order to improve the impact resistance of the resin. For example, a method of adding a modified olefin compound (see, for example, Patent Document 2) is known, but this method has an insufficient impact resistance improvement effect, and further improvement is required. Attempts have also been made to improve impact resistance by adding a multilayer structure polymer to polylactic acid (see, for example, Patent Document 3). However, even this method has not yet provided impact resistance enough to withstand actual use.
JP 2002-309074 A JP 9-316310 A JP 2006-160925 A

  The present invention provides a resin composition and a molded article having a high impact resistance improvement effect as compared with conventional resin compositions, and at the same time, having low mechanical dependence, wet heat resistance, and moldability and low dependence on petroleum products. It is to provide.

As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by using a core-shell type graft copolymer and a carbodiimide compound in a crosslinked polylactic acid resin. It was found and reached the present invention. That is, the gist of the present invention is as follows.
(1) A resin composition containing a crosslinked polylactic acid-based resin (樹脂), a core-shell type graft copolymer (B), and a carbodiimide compound (C), and the mass of (A) and (B) The ratio (A / B) is 70/30 to 99/1, and the blending amount of (C) is 0.1 to 5 parts by mass with respect to 100 parts by mass of the total amount of (A) and (B). The resin composition characterized by the above-mentioned.
(2) The resin composition according to (1), wherein the cross-linked polylactic acid-based resin (し た) has a cross-linked structure introduced into the polylactic acid-based resin by a peroxide.
(3) The resin composition according to (1), wherein the cross-linked polylactic acid resin (樹脂) is obtained by introducing a cross-linked structure into the polylactic acid resin with a peroxide and a cross-linking aid.
(4) The resin composition according to any one of (1) to (3), wherein the carbodiimide compound (C) has an isocyanate group at a terminal.
(5) A molded product obtained by molding the resin composition according to any one of (1) to (4).

  According to the present invention, by blending the core-shell type graft copolymer (B) and the carbodiimide compound (C) with the cross-linked polylactic acid resin (A), excellent mechanical strength, moisture and heat resistance, molding In addition to the properties, a resin composition having a low dependence on petroleum products with improved impact resistance is provided. This resin composition can be made into various molded articles by various molding methods, and has very high industrial utility value. In addition, since a biodegradable resin derived from a natural product is used, it can contribute to saving of depleted resources such as oil.

Hereinafter, the present invention will be described in detail.
In the present invention, the cross-linked polylactic acid resin (A) is a polylactic acid resin obtained by introducing a cross-linked structure, and the polylactic acid resin is mainly composed of polylactic acid.
As polylactic acid, it is desirable to use poly (L-lactic acid), poly (D-lactic acid), and a mixture or copolymer thereof. From the viewpoint of biodegradability, it is preferable that poly (L-lactic acid) is the main component.
In addition, the main component is one or more resins selected from polyglycolic acid, polycaprolactone, polybutylene succinate, polyethylene succinate, polybutylene adipate terephthalate, polybutylene succinate terephthalate, etc. as accessory components. What mixed with the polylactic acid resin may be used.

  Further, the melting point of polylactic acid mainly composed of poly (L-lactic acid) varies depending on the optical purity. However, in the present invention, the melting point is 160 ° C. or higher in consideration of the mechanical properties and heat resistance of the molded product. It is preferable that In the polylactic acid mainly composed of poly (L-lactic acid), in order to make the melting point 160 ° C. or higher, the ratio of the D-lactic acid component may be less than about 3 mol%.

  The melt flow rate of the polylactic acid resin at 190 ° C. and a load of 21.2 N is usually 0.1 to 50 g / 10 minutes, preferably 0.2 to 20 g / 10 minutes, and optimally 0.5 to 10 g / 10 minutes. is there. When the melt flow rate exceeds 50 g / 10 min, the melt viscosity is too low, and the mechanical properties and heat resistance of the molded product are inferior. When the melt flow rate is less than 0.1 g / 10 min, the load during the molding process becomes too high, and the operability may be lowered.

  The polylactic acid resin is produced by a known melt polymerization method or by further adding a solid phase polymerization method. As a method for adjusting the melt flow rate of the polylactic acid resin to a predetermined range, when the melt flow rate is too large, a small amount of chain extender, for example, diisocyanate compound, bisoxazoline compound, epoxy compound, acid anhydride And a method of increasing the molecular weight of the resin by using an object. Conversely, when the melt flow rate is too low, a method of mixing with a polylactic acid resin or a low molecular weight compound having a high melt flow rate can be used.

  As described above, the cross-linked polylactic acid-based resin (A) is a polylactic acid-based resin introduced with a cross-linked structure. As a form of cross-linking, even if the polylactic acid-based resin molecules are directly cross-linked, There are no particular restrictions on what is indirectly cross-linked via an agent, or a mixture of these.

  As a method for introducing a crosslinked structure into the polylactic acid-based resin, a known method such as electron beam irradiation or using a polyfunctional compound such as a polyvalent isocyanate compound can be applied. However, by using a peroxide in terms of crosslinking efficiency. Radical crosslinking is desirable.

Specific examples of peroxides include benzoyl peroxide, bis (butylperoxy) trimethylcyclohexane, bis (butylperoxy) cyclododecane, butylbis (butylperoxy) valerate, dicumyl peroxide, butylperoxybenzoate, dibutyl Examples thereof include peroxide, bis (butylperoxy) diisopropylbenzene, dimethyldi (butylperoxy) hexane, dimethyldi (butylperoxy) hexyne, and butylperoxycumene.
As for the compounding quantity of a peroxide, 0.1-20 mass parts is preferable with respect to 100 mass parts of polylactic acid-type resin, More preferably, it is 0.1-10 mass parts. Even if it exceeds 20 parts by mass, it can be used, but the effect is saturated and it is not economical. In addition, since a peroxide decomposes | disassembles and is consumed at the time of mixing with resin, even if it is used at the time of a mixing | blending, it may not remain in the obtained resin composition.

  In order to further improve the crosslinking efficiency, it is desirable to use a crosslinking aid together with the peroxide. Cross-linking aids include divinylbenzene, diallylbenzene, divinylnaphthalene, divinylphenyl, divinylcarbazole, divinylpyridine and their core-substituted compounds and related homologues, ethylene glycol diacrylate, butylene glycol diacrylate, triethylene glycol diacrylate , 1,6-hexanediol diacrylate, polyfunctional acrylic acid compounds such as tetramethylolmethane tetraacrylate, ethylene glycol dimethacrylate, butylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, 1,6 -Hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate, 1,10-decanediol dimethacrylate, Polyfunctional methacrylic acid compounds such as limethylolpropane trimethacrylate and tetramethylolmethane tetramethacrylate, polyvinyl esters of aliphatic and aromatic polycarboxylic acids such as divinyl phthalate, diallyl phthalate, diallyl maleate, bisacryloyloxyethyl terephthalate , Polyallyl esters, polyacryloyloxyalkyl esters, polymethacryloyloxyalkyl esters, diethylene glycol divinyl ether, hydroquinone divinyl ether, bisphenol A diallyl ether and other aliphatic and aromatic polyhydric alcohol polyvinyl ethers and polyallyl ethers, triallyl Cyanuric acid such as nurate and triallyl isocyanurate, or allyl esters of isocyanuric acid, Compounds having two or more triple bonds such as maleimide compounds such as ril phosphate, trisacryloxyethyl phosphate, N-phenylmaleimide, N, N'-m-phenylenebismaleimide, dipropargyl phthalate, dipropargyl maleate, etc. Multifunctional monomers can be used.

  Of these, (meth) acrylic acid ester compounds are particularly desirable from the viewpoint of crosslinking reactivity. Through this component, the polylactic acid resin component is cross-linked, and mechanical strength, heat resistance, and dimensional stability are improved. The (meth) acrylic acid ester compound has high reactivity with the biodegradable resin, it is difficult for the monomer to remain, its toxicity is relatively low, and the resin is less colored, so there are two or more (meth) acrylic compounds in the molecule. Compounds having a group or having one or more (meth) acrylic groups and one or more glycidyl groups or vinyl groups are preferred. Specific compounds include glycidyl methacrylate, glycidyl acrylate, glycerol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, allyloxy polyethylene glycol monoacrylate, allyloxy polyethylene glycol monomethacrylate, polyethylene glycol dimethacrylate, polyethylene glycol. Diacrylate, polypropylene glycol dimethacrylate, polypropylene glycol diacrylate, polytetramethylene glycol dimethacrylate, or a copolymer of alkylene glycol in which the alkylene glycol part has a different alkylene group may be used. Furthermore, butanediol methacrylate, butanediol Acrylate etc. It is.

  When a (meth) acrylic acid ester compound is blended as a crosslinking aid, the amount thereof is 0.01 to 20 parts by mass, preferably 0.05 to 10 parts by mass, with respect to 100 parts by mass of the polylactic acid resin. 0.1 to 5 parts by mass is preferable. It can also be used in excess of 20 parts by mass as long as the operability is not particularly hindered.

  Examples of the method for preparing the crosslinked polylactic acid-based resin (A) include a method in which a peroxide and a crosslinking aid are blended in the polylactic acid-based resin and melt-kneaded using a general extruder. . In order to improve the kneading state, it is preferable to use a twin screw extruder. The kneading temperature is preferably in the range of (melting point of polylactic acid resin + 5 ° C.) to (melting point of polylactic acid resin + 100 ° C.), and the kneading time is preferably 20 seconds to 30 minutes. If the temperature is lower or shorter than this range, kneading or reaction becomes insufficient, and if the temperature is higher or longer, the resin may be decomposed or colored. At the time of blending, when the crosslinking aid is in a solid state, a method of supplying using a dry blend or a powder feeder is preferable. When in a liquid state, it is directly injected into the barrel of the extruder using a pressure pump. The method is preferred.

  As a preferable method when the peroxide and the crosslinking aid are used in combination, there is a method in which the peroxide and / or the crosslinking aid is dissolved or dispersed in a medium and injected into a kneader, and the operability is greatly improved. be able to. That is, during melting and kneading of the polylactic acid resin component and the peroxide, a solution or dispersion of the crosslinking aid is injected, or during melting and kneading of the polylactic acid resin, the peroxide and the crosslinking aid are Melting and kneading can be performed by injecting a solution or dispersion.

As a medium for dissolving or dispersing the peroxide and / or the crosslinking aid, a general medium is used, and is not particularly limited, but a plasticizer excellent in compatibility with the polylactic acid resin is preferable.
For example, one or more selected from aliphatic polycarboxylic acid ester derivatives, aliphatic polyhydric alcohol ester derivatives, aliphatic oxyester derivatives, aliphatic polyether derivatives, aliphatic polyether polycarboxylic acid ester derivatives, etc. Examples include plasticizers. Specific compounds include dimethyl adipate, dibutyl adipate, triethylene glycol diacetate, methyl acetyl ricinoleate, acetyl tributyl citric acid, polyethylene glycol, dibutyl diglycol succinate, glycerin diacetomonocaprylate, glycerin diacetomonolaurate, etc. Is mentioned.
As a usage-amount of a plasticizer, it is 30 mass parts or less with respect to 100 mass parts of polylactic acid-type resin, Preferably, it is 0.1-20 mass parts. When the reactivity of the crosslinking agent is low, it is not necessary to use the plasticizer, but when the reactivity is high, it is preferable to use 0.1 parts by mass or more. In addition, since this medium may volatilize at the time of mixing with resin, even if it uses it at the time of manufacture, this medium may not be contained in the obtained resin composition.

In the present invention, the core-shell type graft copolymer (B) is a graft copolymer in which the core is composed of a polymer component having rubber elasticity and the shell is composed of a polymer component having thermoplasticity.
The rubbery type of the graft copolymer is not particularly limited as long as it is composed of a polymer component having rubber elasticity. For example, a rubber composed of a polymer obtained by polymerizing an acrylic component, a silicone component, a styrene component, a nitrile component, a conjugated diene component, a urethane component, an ethylene propylene component, or the like can be given.
Examples of acrylic components include ethyl acrylate units and butyl acrylate units, silicone components such as dimethylsiloxane units and phenylmethylsiloxane units, styrene components such as styrene units and α-methylstyrene units, and nitrile components. Examples of the conjugated diene component such as an acrylonitrile unit or a methacrylonitrile unit include a butanediene unit and an isoprene unit.
A rubber composed of a copolymer obtained by combining two or more of these components is also preferable. For example, (1) a rubber composed of a component obtained by copolymerizing and composing an acrylic component and a silicone component, (2 ) Rubber composed of a copolymer of acrylic and styrene components, (3) rubber composed of a copolymer of acrylic and conjugated diene components, and (4) copolymer of acrylic, silicone and styrene components. Examples thereof include rubber composed of polymerized components. In addition to these components, a rubber obtained by copolymerizing and crosslinking a crosslinkable component such as a divinylbenzene unit, an allyl acrylate unit, or a butylene glycol diacrylate unit is also preferable.

  In the present invention, the rubber component constituting the core-shell type graft copolymer (B) is preferably butadiene rubber, acrylic rubber, silicone rubber, or silicone acrylic rubber.

Butadiene rubber is a polymer consisting of only 1,3-butadiene monomer units, or 1,3-butadiene monomer units and one or more vinyl monomer units copolymerizable therewith. It is the polymer which becomes. In addition, it is preferable that content of the 1 or more types of copolymerizable vinyl monomer unit is 50% by mass or less in the butadiene rubber polymer.
Examples of vinyl monomers copolymerizable with 1,3-butadiene include aromatic vinyl compounds such as styrene and α-methylstyrene, alkyl methacrylates such as methyl methacrylate and ethyl methacrylate, ethyl acrylate, and n-butyl acrylate. Alkyl acrylates such as acrylonitrile, unsaturated nitriles such as acrylonitrile and methacrylonitrile, vinyl ethers such as methyl vinyl ether and butyl vinyl ether, vinyl halides such as vinyl chloride and vinyl bromide, vinylidene halides such as vinylidene chloride and vinylidene bromide And vinyl monomers having a glycidyl group such as glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, and ethylene glycol glycidyl ether.
In addition to the above, aromatic polyfunctional vinyl compounds such as divinylbenzene and divinyltoluene, polyhydric alcohols such as ethylene glycol dimethacrylate and 1,3-butanediol diacrylate, trimethacrylates, triacrylates, acrylics Crosslinkable monomers (crosslinking agents) such as carboxylic acid allyl esters such as allyl acid and allyl methacrylate, diallyl compounds such as diallyl phthalate and diallyl sebacate, and triallyl compounds such as triallyl triazine can be used. These can be used alone or in admixture of two or more.

As acrylic rubber, what contains 50-100 mass% of acrylic acid ester of a main structural unit and 50-0 mass% of vinyl-type monomers copolymerizable with this is mentioned.
The acrylic ester constituting the acrylic rubber is an acrylic alkyl ester having 2 to 8 carbon atoms in the alkyl group, and examples thereof include ethyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate.
Examples of vinyl monomers constituting the acrylic rubber include aromatic vinyls such as styrene and α-methylstyrene, alkyl methacrylates such as methyl methacrylate and ethyl methacrylate, unsaturated nitriles such as acrylonitrile and methacrylonitrile, methyl Vinyl ethers such as vinyl ether and butyl vinyl ether, vinyl halides such as vinyl chloride and vinyl bromide, vinylidene halides such as vinylidene chloride and vinylidene bromide, glycidyl groups such as glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, and ethylene glycol glycidyl ether And vinyl monomers having

Examples of the silicone acrylic rubber include rubber containing polyorganosiloxane and alkyl (meth) acrylate rubber. The rubber may be produced by any method, but the emulsion polymerization method is optimal. The polyorganosiloxane is not particularly limited, but is preferably a polyorganosiloxane containing a vinyl polymerizable functional group.
Examples of the dimethylsiloxane used in the production of the polyorganosiloxane include a dimethylsiloxane-based cyclic body having a 3-membered ring or more, and a 3- to 7-membered ring is preferable. Specific examples include hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, and the like. These may be used alone or in combination of two or more.

On the other hand, the shell of the core-shell type graft copolymer (B) is composed of a polymer component having thermoplasticity. The glass transition temperature of the polymer component constituting the shell is preferably higher than that of the polymer component constituting the rubber.
Polymers constituting the shell include unsaturated carboxylic acid alkyl ester units, glycidyl group-containing vinyl units, aliphatic vinyl units, aromatic vinyl units, vinyl cyanide units, maleimide units, unsaturated dicarboxylic acids. Examples thereof include polymers containing at least one unit selected from acid units or other vinyl units, among others, polymers containing unsaturated carboxylic acid alkyl ester units and glycidyl group-containing vinyl units. Is preferred.

  The unsaturated carboxylic acid alkyl ester unit is not particularly limited, but (meth) acrylic acid alkyl ester is preferably used. Specifically, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, (meth) acrylic N-hexyl acid, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, stearyl (meth) acrylate, octadecyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, ( Chloromethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2,3,4,5,6 (meth) acrylic acid -Pentahydroxyhexyl, 2,3,4,5-tetrahydroxypentyl (meth) acrylate, amino acid acrylate Examples include ethyl, propylaminoethyl acrylate, dimethylaminoethyl methacrylate, ethylaminopropyl methacrylate, phenylaminoethyl methacrylate, cyclohexylaminoethyl methacrylate, and the like, which are highly effective in improving dispersibility in resins. , Methyl (meth) acrylate and n-butyl (meth) acrylate are preferably used. These units can be used alone or in combination of two or more.

  The glycidyl group-containing vinyl-based unit is not particularly limited, and examples thereof include glycidyl (meth) acrylate, glycidyl itaconate, diglycidyl itaconate, allyl glycidyl ether, styrene-4-glycidyl ether, and 4-glycidyl styrene. From the viewpoint that the effect of improving impact resistance is great, glycidyl (meth) acrylate is preferably used. These units can be used alone or in combination of two or more.

  The aliphatic vinyl unit may be ethylene, propylene or butadiene, and the aromatic vinyl unit may be styrene, α-methylstyrene, 1-vinylnaphthalene, 4-methylstyrene, 4-propylstyrene, 4-cyclohexyl. Styrene, 4-dodecyl styrene, 2-ethyl-4-benzyl styrene, 4- (phenylbutyl) styrene, halogenated styrene, etc., as vinyl cyanide units, acrylonitrile, methacrylonitrile, ethacrylonitrile, etc. maleimide Units include maleimide, N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-isopropylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N- (p-bromophenyl) maleimide, N- (chlorophenyl) maleimide and other unsaturated dicarboxylic acid units such as maleic acid, maleic acid monoethyl ester, itaconic acid and phthalic acid, and other vinyl units such as acrylamide, methacrylamide, N-methylacrylamide, Butoxymethylacrylamide, N-propylmethacrylamide, N-vinyldiethylamine, N-acetylvinylamine, allylamine, methallylamine, N-methylallylamine, p-aminostyrene, 2-isopropenyl-oxazoline, 2-vinyl-oxazoline, 2 -Acroyl-oxazoline or 2-styryl-oxazoline can be mentioned. These units can be used alone or in combination of two or more.

  In the present invention, the mass ratio (A / B) between the cross-linked polylactic acid resin (Α) and the core-shell type graft copolymer (B) needs to be 70/30 to 99/1. When the blending amount of the core-shell type graft copolymer (B) is less than 1% by mass, the impact resistance tends to decrease, and when it exceeds 30% by mass, the moldability tends to decrease.

  The resin composition of the present invention contains a carbodiimide compound (C) in addition to the crosslinked polylactic acid-based resin (樹脂) and the core-shell type graft copolymer (B). By containing the carbodiimide compound (C), the heat-and-moisture resistance is improved, the compatibility by melt-kneading is further improved, and the mechanical properties are also improved.

  The carbodiimide compound (C) used in the present invention is a compound having one or more carbodiimide groups in the molecule. Specifically, 4,4′-dicyclohexylmethanecarbodiimide, tetramethylxylylenecarbodiimide, N, N-dimethylphenylcarbodiimide, N, N′-di-2,6-diisopropylphenylcarbodiimide and the like are exemplified, but not particularly limited.

  The carbodiimide compound (C) can be produced by a conventionally known method, and can be produced by a carbodiimide reaction involving a decarbonation reaction using a diisocyanate compound as a raw material. The carbodiimide compound (C) produced by such a method has an isocyanate group at the terminal unless the terminal blocking treatment is performed. In the present invention, it is desirable that the carbodiimide compound (C) has an isocyanate group at the terminal from the viewpoint of improvement in heat and moisture resistance and impact resistance. Since the isocyanate group has higher reactivity than the carbodiimide group, a higher effect can be obtained.

  The compounding quantity of a carbodiimide compound (C) needs to be 0.1-5 mass parts with respect to a total of 100 mass parts of crosslinked polylactic acid-type resin (A) and a core-shell type graft copolymer (B). It is preferable that it is 0.5-5 mass parts. When the compounding amount of the carbodiimide compound (C) is less than 0.01 parts by mass, the effects of improving the moist heat resistance and impact resistance of the resin composition of the present invention are not observed. This is not economically preferable.

  The resin composition of the present invention can be produced by melt-kneading the cross-linked polylactic acid resin (A), the core-shell type graft copolymer (B), and the carbodiimide compound (C) with an extruder. As conditions for melt-kneading, it is preferable that processing temperature shall be 170-190 degreeC.

  In addition, as described above, a polylactic acid resin, a peroxide, and a crosslinking aid are melt-kneaded using an extruder to prepare a crosslinked polylactic acid resin (A), and then a core-shell type graft copolymer (B ) And the carbodiimide compound (C) may be added to an extruder and further melt kneaded to produce a resin composition. That is, without taking out the prepared crosslinked polylactic acid resin (A), the crosslinking treatment of the polylactic acid resin and kneading of the core-shell type graft copolymer (B) and the carbodiimide compound (C) with one extruder. May be performed.

  Glass fibers may be used in the resin composition of the present invention for the purpose of improving mechanical strength and heat resistance. It is preferable that the compounding quantity is 1-50 mass parts with respect to 100 mass parts of resin compositions. As the glass fiber, a normal glass fiber is sufficient, and a surface treatment may be performed in order to enhance the adhesion to the resin. As an addition method, in an extruder, it can be added from a hopper or in the middle of kneading using a side feeder. Moreover, it can also use by diluting with a base resin at the time of shaping | molding by carrying out a masterbatch process of glass fiber.

As long as the properties of the resin composition of the present invention are not greatly impaired, pigments, heat stabilizers, antioxidants, weathering agents, flame retardants, plasticizers, lubricants, mold release agents, antistatic agents, fillers, crystals A nuclear material etc. can be added.
Examples of heat stabilizers and antioxidants include hindered phenols, phosphorus compounds, hindered amines, sulfur compounds, copper compounds, and alkali metal halides.
As the flame retardant, a halogen-based flame retardant, a phosphorus-based flame retardant, and an inorganic flame retardant can be used, but in consideration of the environment, it is desirable to use a non-halogen flame retardant. Non-halogen flame retardants include phosphorus flame retardants, hydrated metal compounds (aluminum hydroxide and magnesium hydroxide), N-containing compounds (melamine and guanidine), and inorganic compounds (borate and Mo compounds). It is done.
Inorganic fillers include talc, calcium carbonate, zinc carbonate, wollastonite, silica, alumina, magnesium oxide, calcium silicate, sodium aluminate, calcium aluminate, sodium aluminosilicate, magnesium silicate, glass balloon, carbon black, Examples thereof include zinc oxide, antimony trioxide, zeolite, hydrotalcite, metal fiber, metal whisker, ceramic whisker, potassium titanate, boron nitride, graphite, and carbon fiber. Examples of the organic filler include naturally occurring polymers such as starch, cellulose fine particles, wood flour, okara, fir shell, bran, and modified products thereof.
Examples of the inorganic crystal nucleus material include talc and kaolin. Examples of the organic crystal nucleus material include sorbitol compound, benzoic acid and its metal salt, phosphate metal salt, rosin compound, ethylene bis compound as amide compound. Oleic acid amide, methylene bisacrylic acid amide, ethylene bisacrylic acid amide, hexamethylene bis-9, 10-dihydroxystearic acid bisamide, p-xylylene bis-9, 10 dihydroxystearic acid amide, decanedicarboxylic acid dibenzoyl hydrazide, hexanedicarboxylic Acid dibenzoyl hydrazide, 1,4-cyclohexanedicarboxylic acid dicyclohexylamide, 2,6-naphthalenedicarboxylic acid dianilide, N, N ', N "-tricyclohexyltrimesic acid amide, trimesic acid tris (t- Tilamide), 1,4-cyclohexanedicarboxylic acid dianilide, 2,6-naphthalenedicarboxylic acid dicyclohexylamide, N, N'-dibenzoyl-1,4-diaminocyclohexane, N, N'-dicyclohexanecarbonyl-1,5-diamino Naphthalene, ethylenebisstearic acid amide, N, N′-ethylenebis (12-hydroxystearic acid) amide, octanedicarboxylic acid dibenzoyl hydrazide, etc. The method of mixing these with the resin composition of the present invention is as follows. There is no particular limitation.

  The resin composition of the present invention can be formed into various molded bodies by injection molding, blow molding, extrusion molding, inflation molding, and molding methods such as vacuum molding, pressure molding, and vacuum / pressure molding after sheet processing. In particular, an injection molding method is preferable, and in addition to a general injection molding method, gas injection molding, injection press molding, or the like can be employed. As an example of injection molding conditions suitable for the resin composition of the present invention, the cylinder temperature is not lower than the melting point or flow start temperature of polylactic acid, preferably 180 to 250 ° C., optimally 190 to 240 ° C., and The mold temperature is suitably not higher than the melting point of the resin composition (−20 ° C.). If the molding temperature is too low, the operability becomes unstable, such as defective filling in the molded product, and overload tends to occur. Conversely, if the molding temperature is too high, the resin composition decomposes and the resulting molded product Problems such as reduction in strength and coloring are likely to occur.

  The heat resistance of the resin composition of the present invention can be enhanced by promoting crystallization. As a method for this, for example, the crystallization can be promoted by devising the cooling conditions in the mold at the time of injection molding. In that case, the mold temperature is set to the polylactic acid (glass transition temperature). It is preferable to cool the glass transition temperature to not higher than + 20 ° C.) and not higher than (melting point−20 ° C.) for a predetermined time, and then not higher than the glass transition temperature. Further, as a method for promoting crystallization after molding, it is preferable to directly cool the glass transition temperature or lower and then heat-treat again at Tg or higher and (melting point −20 ° C.) or lower.

  Specific examples of the molded body include resin parts for electrical appliances such as various cases, agricultural materials such as containers and cultivation containers, resin parts for agricultural machinery, resin parts for fisheries operations such as floats and processed fishery products containers, dishes, Tableware and food containers such as cups and spoons, medical resin parts such as syringes and infusion containers, drain materials, fences, storage boxes, resin parts for housing, civil engineering, and building materials such as construction switchboards, cooler boxes, fan fans, and toys Such as resin parts for miscellaneous goods, automobile parts such as bumpers, instrument panels and door trims. Moreover, it can also be set as extrusion molded articles, such as a film, a sheet | seat, and a pipe, and a hollow molded article.

Hereinafter, the present invention will be described more specifically with reference to examples. The measuring method used for evaluation of the resin composition of an Example and a comparative example is as follows.
(1) Melt flow rate (MFR):
According to JIS standard K-7210 (test condition 4), it measured at 190 degreeC and the load 21.2N.
(2) Bending strength, bending elastic modulus, bending breaking strain:
Measured according to ISO 178.
(3) Charpy impact strength:
Measured according to ISO 179.
(4) DTUL (° C):
Based on ISO 75, the deflection temperature under load was measured at a load of 0.45 MPa.
(5) Moist heat resistance:
After the bending strength test piece was treated for 300 hours in an environment of a temperature of 60 ° C. and a humidity of 90% RH, the bending strength was measured, and the strength retention was calculated and evaluated.
(6) Molding cycle:
A molding test of an ISO dumbbell-shaped test piece was performed with an injection molding machine (Toshiba IS-80G). The mold was melted at a molding temperature of 190 ° C., and the mold was filled with the molten resin under the conditions of an injection time of 30 seconds and a mold temperature of 100 ° C. Molding cycle is good because the resin composition is injected into the mold (filling, holding pressure) and cooled, and then the molded product can be fixed to the mold or taken out without resistance, and there is no deformation due to the protruding pin. It was set as the time (seconds) until the mold could be released. The molding cycle is preferably 90 seconds or less from the viewpoint of economy. Therefore, no further evaluation was performed on those that took 100 seconds or longer.

The raw materials used in Examples and Comparative Examples of the present invention are shown below.
(1) Polylactic acid resin:
NatureWorks 6201D manufactured by Cargill Dow (MFR = 10 g / 10 min, melting point: 168 ° C.)
(2) Peroxide:
Di-t-butyl peroxide (manufactured by NOF Corporation)
(3) Crosslinking aid:
Polyethylene glycol dimethacrylate (Nippon Yushi Co., Ltd. BLEMER PDE-50)
(4) Plasticizer:
Glycerin diacetomonocaprate (PL-019 manufactured by Riken Vitamin)
(5) Core-shell type graft copolymer (B):
Butadiene rubber (Metbrene C-223A manufactured by Mitsubishi Rayon Co., Ltd., hereinafter abbreviated as C-223A)
Silicone / acrylic rubber (Metbrene S-2001 manufactured by Mitsubishi Rayon Co., Ltd., hereinafter abbreviated as S-2001)
Acrylic rubber (Metbrene W-450A manufactured by Mitsubishi Rayon Co., Ltd., hereinafter abbreviated as W-450A)
(6) Carbodiimide compound (C):
Terminal isocyanate group-containing product (LA-1 manufactured by Nisshinbo Co., Ltd., hereinafter abbreviated as LA-1)
Terminal isocyanate group-sealed product (Nisshinbo's HMV-8CA, hereinafter abbreviated as HMV-8CA)

Examples 1-8, Comparative Examples 1-3, 5-9
Using a twin-screw extruder (TEM-37BS manufactured by Toshiba Machine Co., Ltd.), 100 parts by mass of polylactic acid is supplied from the top feeder, and 0.2 parts by mass of peroxide is used by using a pump from the middle of the kneader. A solution prepared by dissolving 0.1 part by mass of a crosslinking aid in 1 part by mass of a plasticizer was poured, and melt kneading extrusion was performed at a processing temperature of 190 ° C. Then, the discharged resin was cut into pellets to obtain a crosslinked polylactic acid resin (A1). The obtained cross-linked polylactic acid resin had an MFR of 1.2 g / 10 min.
Cross-linked polylactic acid resin (A1), core-shell type graft copolymer (B), carbodiimide compound (C) at a compounding ratio shown in Table 1 using a twin screw extruder (TEM-37BS manufactured by Toshiba Machine Co., Ltd.) Was fed from the top feeder of the kneader and melt kneaded and extruded at a processing temperature of 190 ° C. Then, the discharged resin was cut into pellets to obtain a resin composition.
Next, the resin composition pellets were dried in a vacuum dryer under conditions of 70 ° C. × 8 h, and then a test piece was molded with an injection molding machine (Toshiba IS-80G) for evaluation.
For Comparative Example 6, the resin composition pellets were dried under conditions of 70 ° C. × 8 h in a vacuum dryer, and then a dumbbell-shaped test piece was molded using the above-described injection molding machine. The evaluation was not performed because it exceeded seconds.
In Comparative Example 7, the strand discharged from the twin-screw extruder could not be stably produced, so that it could not be processed into a pellet and a resin composition could not be obtained.

Example 9
Except not using a crosslinking adjuvant, it carried out similarly to Example 2, and obtained the pellet of the crosslinked polylactic acid-type resin (A2) and the pellet of the resin composition.
Next, the resin composition pellets were dried in a vacuum dryer under conditions of 70 ° C. × 8 h, and then a test piece was molded with an injection molding machine (Toshiba IS-80G) for evaluation.

Example 10
Using a twin-screw extruder (TEM-37BS manufactured by Toshiba Machine Co., Ltd.), 60 parts by mass of polylactic acid is supplied from the top feeder, and with 0.2 parts by mass of peroxide using a pump from the middle of the kneader. A solution prepared by dissolving 0.1 part by mass of a crosslinking aid in 1 part by mass of a plasticizer was injected to produce a crosslinked polylactic acid-based resin (A3) in the extruder. Further, from the side feeder of the extruder, Table 1 The core-shell type graft copolymer (B), the carbodiimide compound (C) and the like were added according to the formulation described in the above, and melt-kneading extrusion was performed at a processing temperature of 190 ° C. Then, the discharged resin was cut into pellets to obtain a resin composition.
Next, the resin composition pellets were dried in a vacuum dryer under conditions of 70 ° C. × 8 h, and then evaluated by molding a test piece with the above-described injection molding machine.

Comparative Example 4
Using a twin screw extruder (TEM-37BS manufactured by Toshiba Machine Co., Ltd.), polylactic acid, core-shell type graft copolymer (B), and carbodiimide compound (C) are supplied from the top feeder at the blending ratio shown in Table 1. In addition, a solution in which 0.1 part by mass of the crosslinking aid was dissolved in 1 part by mass of the plasticizer was injected from the middle of the kneading machine, and melt kneading extrusion was performed at a processing temperature of 190 ° C. Then, the discharged resin was cut into pellets to obtain a resin composition.
Next, after the resin composition pellets were dried in a vacuum dryer under the conditions of 70 ° C. × 8 h, the dumbbell-shaped test piece was molded with the above-described injection molding machine, and the molding cycle exceeded 100 seconds. Not evaluated.

  Table 1 summarizes the results of the various physical property evaluations.

About the resin composition of Examples 1-10, compared with Comparative Examples 1-9, it became the result of improving impact resistance greatly, having excellent mechanical strength, heat resistance, wet heat resistance, and a molding cycle. It was.
In Comparative Example 1, since the core-shell type graft copolymer (B) and the carbodiimide compound (C) were not blended, the results were inferior in impact resistance and moist heat resistance. In Comparative Example 2, since the core-shell type graft copolymer (B) was not blended, the impact resistance was inferior. In Comparative Example 3, since the carbodiimide compound (C) was not blended, the impact resistance was not greatly improved, and the heat and moisture resistance was inferior. In Comparative Example 5, since the blending amount of the core-shell type graft copolymer (B) did not reach the specified amount, the impact resistance was inferior. In Comparative Example 8, since the blending of the carbodiimide compound (C) did not reach the specified amount, the results were inferior in impact resistance and moist heat resistance. In Comparative Example 9, since the amount of the carbodiimide compound (C) exceeded the specified amount, the heat resistance and the molding cycle were inferior.

Claims (5)

A resin composition containing a cross-linked polylactic acid-based resin (と), a core-shell type graft copolymer (B), and a carbodiimide compound (C), wherein the mass ratio of (A) to (B) (A / B) is 70/30 to 99/1, and the blending amount of (C) is 0.1 to 5 parts by mass with respect to 100 parts by mass of the total amount of (A) and (B). A resin composition. The resin composition according to claim 1, wherein the cross-linked polylactic acid resin (樹脂) is obtained by introducing a cross-linked structure into the polylactic acid resin with a peroxide. The resin composition according to claim 1, wherein the cross-linked polylactic acid resin (樹脂) is obtained by introducing a cross-linked structure into the polylactic acid resin with a peroxide and a cross-linking aid. The resin composition according to any one of claims 1 to 3, wherein the carbodiimide compound (C) has an isocyanate group at a terminal. The molded object formed by shape | molding the resin composition in any one of Claims 1-4.