JP2010280768A - Polylactic acid-based resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aliphatic polyester-based resin composition having a practically satisfactory allowable temperature limit by using a polymer alloy technology as a physical-properties improving method for a resin and having moldability and low water vapor permeability, and a molded article using the same. <P>SOLUTION: This aliphatic polyester-based resin composition is a polylactic acid-based resin composition comprising 20 to 90 mass% of a polylactic acid (A), 10 to 80 mass% of a cyclic polyolefin (B), and 0.1 to 10 mass% of a compound (C), relative to 100 mass% of the whole resin composition, in which the compound (C) is a compound selected from a functional group-containing modified olefin resin containing a polyolefin and acryl, an epoxy group-containing acrylic polymer, and a core shell-type gum-containing polymer containing an epoxy group. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a polylactic acid resin composition.

  In recent years, depletion of fossil raw materials represented by crude oil has been regarded as a problem. Therefore, plants have attracted attention as a raw material for plastics that can replace fossil raw materials. Among them, aliphatic polyesters typified by polylactic acid obtained by fermentation from cereal resources are particularly attracting attention because they are excellent in moldability and rigidity, and large-scale commercial plants have been put into practical use.

  However, there is a limit to the application development of aliphatic polyester. This is because, for example, the glass transition point (Tg) of polylactic acid is about 60 ° C., and its heat resistance is 60 ° C. or less in an amorphous state, and therefore, it tends to cause whitening, deformation, etc. in an everyday use environment. It has been pointed out. Polylactic acid has crystallinity, and heat resistance is greatly improved by crystallization exceeding 60 ° C. However, since the crystallization speed is low, crystallization at the time of molding is insufficient, and post-crystallization step is required. This increases the cost. Furthermore, it cannot be said that heat resistance is sufficient even after post-crystallization.

  Furthermore, aliphatic polyesters including polylactic acid also have a problem of high moisture permeability.

  On the other hand, as a conventionally known method for improving the physical properties of a resin, there is a technique called polymer blend or polymer alloy. This is intended to improve impact resistance, flexibility, rigidity, heat resistance, barrier properties, etc. by forcibly mixing and kneading other resins with a certain resin.

  Some attempts to improve physical properties by mixing different kinds of resins with polylactic acid are also known. For example, a polylactic acid resin composition with improved impact resistance obtained by mixing 1 to 15% by weight of syndiotactic polypropylene with polylactic acid is known (Patent Document 1). Moreover, it is known that the impact resistance of polylactic acid is improved by mixing a modified olefin compound with polylactic acid (Patent Document 2). In addition, a polylactic acid resin composition having improved melting characteristics, mechanical characteristics, and impact resistance by mixing polylactic acid and a thermoplastic elastomer (ethylene-propylene-diene rubber) is known (patent) Reference 3). Moreover, the polylactic acid-type resin composition by which the improvement in heat resistance was improved by mixing polylactic acid and cyclic polyolefin is known (patent document 4).

JP-A-10-251498 JP 9-316310 A JP 2002-37987 A JP 2009-40949 A

  However, the polylactic acid-based resin composition obtained by the conventional technique has insufficient heat resistance when molded with a relatively low temperature mold for the purpose of obtaining a molded body using this resin composition. Only a molded body can be obtained. Moreover, the heat resistance is not sufficient at all in the composition in which the aliphatic polyester is rich (Patent Documents 1-3).

Moreover, in the polylactic acid-type resin in which the improvement of heat resistance was confirmed in Patent Document 4, polylactic acid having high heat resistance was originally used, and the types of polylactic acid that can be used are limited.
An object of the present invention is to use a polymer alloy technique as a method for improving the physical properties of a resin, so that a wide variety of polylactic acids can be used, which has a practically sufficient heat-resistant temperature, and has moldability and low moisture permeability. An object of the present invention is to provide a resin composition and a molded body using the same.

As a result of intensive studies to achieve the above-mentioned problems, the present inventors have found that a polylactic acid-based resin composition containing polylactic acid and a cyclic polyolefin and further containing a specific compound has heat resistance and low moisture permeability. As a result, the present invention has been completed.
That is, the gist of the present invention is as follows.

  (1) 10 to 80 mass% of cyclic polyolefin (B) consisting of 20 to 90 mass% of polylactic acid (A) and an addition copolymer of a cyclic olefin and an α-olefin or a hydrogenated product thereof, with 100% by mass as a whole. And compound (C) 0.1 to 10% by mass, the compound (C) is an epoxy group-containing modified olefin resin, an acrylic polymer containing an epoxy group, and a core-shell type containing an epoxy group A polylactic acid resin composition characterized by being selected from a rubber-containing polymer.

  (2) The polylactic acid-based resin composition according to (1), wherein the deflection temperature under load measured at a load of 0.45 MPa is 80 ° C. or higher under the conditions based on ASTM D648.

(3) The moisture permeability coefficient at 40 ° C. × 90% Rh when measured under the conditions based on the method B defined in JIS K7129 is 4 g · mm / m ² · day or less (1 ) Or (2) a polylactic acid resin composition.

  (4) A molded body characterized by using any of the polylactic acid resin compositions (1) to (3).

  According to the present invention, it is possible to obtain a polylactic acid-based resin composition that is excellent in heat resistance and moldability and excellent in low moisture permeability as compared with the conventional one. The molded body using this polylactic acid-based resin composition can be applied to fields where heat resistance is insufficient with conventional molded bodies using a polylactic acid-based resin composition.

  Hereinafter, the polylactic acid resin composition of the present invention and a molded body using the same will be described in detail.

[Polylactic acid resin composition]
The polylactic acid resin composition of the present invention contains polylactic acid (A), cyclic polyolefin (B) and compound (C).

<Polylactic acid (A)>
As the polylactic acid (A) in the present invention, any one of a homopolymer consisting of L-lactic acid or D-lactic acid, a copolymer of L-lactic acid and D-lactic acid, or a polymer generally called a stereocomplex, etc. You may use, and you may mix and use them. Although the content ratio of L-lactic acid / D-lactic acid in the polylactic acid (A) is not particularly limited, commercially available (L-lactic acid / D-lactic acid) = 0.2 / 99.8 to 99.99. There are those in the range of 8 / 0.2 (mol%), and they can be used without limitation.

  As a method for producing polylactic acid (A), L-lactic acid, D-lactic acid, and DL-lactic acid (racemic) are used as raw materials to once generate lactide, which is a cyclic dimer, and then perform ring-opening polymerization. And a one-step direct polymerization method in which the raw material is directly subjected to dehydration condensation in a solvent are known. The polylactic acid (A) used in the present invention may be obtained by any production method. Alternatively, if necessary, a solid phase polymerization method may be used in combination.

  The molecular weight of polylactic acid (A) is not particularly limited, but considering the strength of the molded body, at least the weight average molecular weight (Mw) is preferably 50,000 or more, more preferably in the range of 70,000 to 400,000. Most preferably, it is in the range of 80,000 to 250,000. The weight average molecular weight (Mw) here is measured at 40 ° C. using a gel permeation chromatography apparatus (GPC) equipped with a differential refractive index detector and tetrahydrofuran (THF) as an eluent. It is the value calculated | required in polystyrene conversion when doing.

  When the melt flow index (MFI) is used as an index of the molecular weight of polylactic acid, it can be used preferably if the MFI at 190 ° C. and 2.16 kg is in the range of 0.1 to 50 g / 10 min, more preferably The range is 0.2 to 40 g / 10 min.

  The polylactic acid (A) used in the present invention may be partially crosslinked. Moreover, it may be modified with an epoxy compound or the like. For the purpose of increasing the molecular weight of polylactic acid (A), chain extenders such as diisocyanate compounds, polyepoxy compounds, and acid anhydrides may be used. The addition amount is not particularly limited, but is preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the resin. In particular, polylactic acid (A) crosslinked with a (meth) acrylic compound and a peroxide is preferable because heat resistance is improved.

  As the (meth) acrylic compound, the reactivity with polylactic acid (A) is high, the monomer hardly remains, the toxicity is relatively low, and the resin is less colored. Therefore, two or more (meth) acrylic compounds in the molecule. Compounds having a group or having one or more glycidyl groups or vinyl groups are preferred. Specific examples of the compound include glycidyl methacrylate, trimethylolpropane trimethacrylate, polyethylene glycol dimethacrylate, and polyethylene glycol diacrylate.

  The addition amount of the (meth) acrylic compound is preferably 0.01 to 5 parts by mass and more preferably 0.05 to 3 parts by mass with respect to 100 parts by mass of the polylactic acid (A). If it is less than 0.01 parts by mass, it is difficult to obtain the required mechanical strength, heat resistance, and dimensional stability improvement effects based on the introduction of the crosslinked structure. On the other hand, when the amount exceeds 5 parts by mass, the degree of crosslinking is too strong and the operability tends to be hindered.

  The peroxide is added as an initiator for the radical reaction. Examples of peroxides include benzoyl peroxide, bis (butylperoxy) trimethylcyclohexane, bis (butylperoxy) methylcyclododecane, butylbis (butylperoxy) valerate, dicumyl peroxide, butylperoxybenzoate, dibutyl Examples thereof include peroxide, bis (butylperoxy) diisopropylbenzene, dimethyldi (butylperoxy) hexane, dimethyldi (butylperoxy) hexyne, and butylperoxycumene.

  The added amount of the peroxide is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the polylactic acid (A). If it is less than 0.01 part by mass, it is difficult to obtain the effect of improving mechanical strength, heat resistance and dimensional stability based on the introduction of a crosslinked structure. On the other hand, if it exceeds 10 parts by mass, the proportion of unused portion increases, which is disadvantageous in terms of cost.

<Cyclic polyolefin (B)>
The cyclic polyolefin (B) refers to a polymer compound having a main chain composed of carbon-carbon bonds and having a cyclic hydrocarbon structure in at least a part of the main chain. This cyclic hydrocarbon structure is introduced by using a compound (cyclic olefin) having at least one olefinic double bond in the cyclic hydrocarbon structure as represented by norbornene or tetracyclododecene as a monomer. Is done.

The cyclic polyolefin (B) used in the present invention comprises an addition copolymer of a cyclic olefin and an α-olefin or a hydrogenated product thereof.
Specific examples of the cyclic olefin include one-ring cyclic olefin such as cyclopentene, cyclohexene, cyclooctene, cyclopentadiene, 1,3-cyclohexadiene;
Bicyclo [2.2.1] hept-2-ene (common name: norbornene), 5-methyl-bicyclo [2.2.1] hept-2-ene, 5,5-dimethyl-bicyclo [2.2. 1] Hept-2-ene, 5-ethyl-bicyclo [2.2.1] hept-2-ene, 5-butyl-bicyclo [2.2.1] hept-2-ene, 5-ethylidene-bicyclo [ 2.2.1] hept-2-ene, 5-hexyl-bicyclo [2.2.1] hept-2-ene, 5-octyl-bicyclo [2.2.1] hept-2-ene, 5- Octadecyl-bicyclo [2.2.1] hept-2-ene, 5-methylidene-bicyclo [2.2.1] hept-2-ene, 5-vinyl-bicyclo [2.2.1] hept-2-ene Ene, 5-propenyl-bicyclo [2.2.1] hept-2-ene, etc. Cyclic olefin ring;
Tricyclo [4.3.0.1 ^2,5 ] deca-3,7-diene (common name: dicyclopentadiene), tricyclo [4.3.0.1 ^2,5 ] dec-3-ene; tricyclo [ 4.4.0.1 ^2,5 ] undeca-3,7-diene or tricyclo [4.4.0.1 ^2,5 ] undeca-3,8-diene or a partially hydrogenated product thereof (or cyclopentadiene) Tricyclo [4.4.0.1 ^2,5 ] undec-3-ene; 5-cyclopentyl-bicyclo [2.2.1] hept-2-ene, 5-cyclohexyl-bicyclo [2.2.1] hept-2-ene, 5-cyclohexenylbicyclo [2.2.1] hept-2-ene, 5-phenyl-bicyclo [2.2.1] hept-2-ene, etc. A tricyclic olefin;
Tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene (also simply referred to as tetracyclododecene), 8-methyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene, 8-ethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene, 8-methylidenetetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene, 8-ethylidenetetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene, 8-vinyltetracyclo [4,4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene, 8-propenyl-tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] a tetracyclic olefin such as dodec-3-ene;
8-cyclopentyl-tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene, 8-cyclohexyl-tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene, 8-cyclohexenyl-tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene, 8-phenyl-cyclopentyl-tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene; tetracyclo [7.4.1 ^3,6 . 0 ^1,9 . 0 ^2,7 ] tetradeca-4,9,11,13-tetraene (also referred to as 1,4-methano-1,4,4a, 9a-tetrahydrofluorene), tetracyclo [8.4.1 ^4,7 . 0 ^1,10 . 0 ^3,8 ] pentadeca-5,10,12,14-tetraene (also referred to as 1,4-methano-1,4,4a, 5,10,10-hexahydroanthracene); pentacyclo [6.6.1]. .1 ^3,6 . 0 ^2,7 . 0 ^9,14 ] -4-hexadecene, pentacyclo [6.5.1.1 ^3,6 . 0 ^2,7 . 0 ^9,13] -4-pentadecene, pentacyclo [7.4.0.0 ^2,7. 1 ^3,6 . 1 ^10,13] -4-pentadecene; heptacyclo [8.7.0.1 ^2,9. 1 ^4,7 . 1 ^11,17 . 0 ^3,8 . 0 ^12,16 ] -5-eicosene, heptacyclo [8.7.0.1 ^2,9 . 0 ^3,8 . 1 ^4,7 . 0 ^12,17 . 1 ^13,16 ] -14-eicosene; and polycyclic cyclic olefins such as a tetramer of cyclopentadiene.

These cyclic olefins can be used alone or in combination of two or more.
Specific examples of the α-olefin copolymerizable with the cyclic olefin include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 3-methyl-1-pentene, 3 -Ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1- 2-20 carbon atoms such as hexene, 3-ethyl-1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, preferably carbon number Examples thereof include 2 to 8 ethylene or α-olefin. These α-olefins can be used alone or in combination of two or more.

There are no particular limitations on the polymerization method of the cyclic olefin and the α-olefin and the hydrogenation method of the obtained polymer, and publicly known methods can be mentioned.
The cyclic polyolefin (B) is preferably an addition copolymer in which the α-olefin unit is ethylene and the cyclic olefin unit is norbornene. Examples of such α-olefin-cycloolefin addition copolymers include TOPAS 8007, 6013 and 6017 manufactured by Polyplastics, and Apel (APL) 8008T, 6013T and 6015T manufactured by Mitsui Chemicals. Can be mentioned.

<Compound (C)>
The compound (C) in the polylactic acid-based resin composition of the present invention needs to be at least one selected from the following <I> to <III>.

<I> Epoxy group-containing modified olefin resin <II> Acrylic polymer containing epoxy group <III> Core-shell type rubbery polymer containing epoxy group <I> “Epoxy group-containing modified olefin resin” It is preferable that 60 mass% or more of units composed of olefins such as propylene are included.

The number average molecular weight of the modified olefin resin is not particularly limited, but is preferably 5,000 or more, and more preferably 10,000 or more.
In addition, as the olefin resin to be modified (unmodified olefin resin), an olefin homopolymer and a copolymer of two or more olefins can be used. Specific examples thereof include polyethylene, polypropylene, polymethylpentene, ethylene / propylene random copolymer, ethylene / propylene block copolymer, ethylene / α-olefin copolymer, propylene / α-olefin copolymer, and the like. It is done.

  Next, <II> “acrylic polymer containing epoxy group” will be described. Among the acrylic polymers containing epoxy groups, preferred materials are styrene-acrylic copolymers and oligomers containing glycidyl groups as side chains. Useful examples are described in WO 03/066704. These materials are oligomers having styrene and acrylate building blocks with glycidyl groups incorporated as side chains. It is desirable to contain 5 to 30, preferably 7 to 25, more preferably 10 to 20 epoxy groups per oligomer chain. These polymeric materials generally have a molecular weight of greater than about 3000, preferably greater than about 4000, and more preferably greater than about 6000. These are commercially available from BASF LLC under the name Joncryl®.

  The “core-shell type rubber-containing polymer containing an epoxy group” of the above <III> will be described. The core-shell type rubbery polymer containing this epoxy group takes the form of a multilayer structure polymer containing a rubbery polymer. The outermost layer (shell layer) includes unsaturated carboxylic acid alkyl ester units, unsaturated carboxylic acid units, unsaturated glycidyl group-containing units, aliphatic vinyl units, aromatic vinyl units, vinyl cyanide units, maleimide units. , At least one selected from polymers containing unsaturated dicarboxylic acid units, unsaturated dicarboxylic acid anhydride units, and other vinyl units. Among them, at least one selected from unsaturated glycidyl group-containing units and unsaturated dicarboxylic anhydride units is preferable because it has high reactivity with polylactic acid end groups and can be expected to improve durability.

  As a monomer used as the raw material of the unsaturated carboxylic acid alkyl ester unit herein, an alkyl acrylate or alkyl methacrylate is preferably used, and methyl acrylate or methyl methacrylate is more preferably used.

  The average particle size of the multilayer structure polymer is preferably 1000 μm or less, more preferably 100 μm or less, further preferably 10 μm or less, and most preferably 1 μm or less. When it exceeds 1000 μm, the dispersed particle size is large and it is difficult to obtain good physical properties.

  In the multilayer structure polymer constituting the core-shell type rubbery polymer containing an epoxy group, the mass ratio of the core to the shell is 50% by mass or more and 90% by mass or less of the core layer with respect to the entire multilayer structure polymer. It is preferable that it is 60 mass% or more and 80 mass% or less. When the core layer is less than 50% by mass, good strength is hardly obtained, and when it exceeds 90% by mass, the reactivity is lowered.

  As the multilayer structure polymer, a commercial product that satisfies the above-described conditions may be used, or it may be prepared and used by a known method.

  Commercially available products of multilayer structure polymers include, for example, “Metablene (registered trademark)” manufactured by Mitsubishi Rayon Co., Ltd., “Kane Ace (registered trademark)” manufactured by Kaneka Chemical Co., Ltd., and “Paralloid (registered trademark)” manufactured by Rohm and Haas. In addition, “STAPHYLOID (registered trademark)” manufactured by GANTZ KASEI KOGYO CO., LTD. These can be used alone or in combination of two or more.

  As the rubber-containing polymer, a rubber-containing graft copolymer can be preferably used. Specific examples thereof include an unsaturated carboxylic acid ester monomer, an unsaturated carboxylic acid monomer, an aromatic vinyl monomer, and, if necessary, copolymerizable with these in the presence of a rubbery polymer. Examples thereof include a graft copolymer obtained by copolymerizing a monomer mixture composed of another vinyl monomer.

  As the rubbery polymer used for the graft copolymer, diene rubber, acrylic rubber, ethylene rubber and the like can be used. Specific examples include polybutadiene, styrene-butadiene copolymer, block copolymer of styrene-butadiene, acrylonitrile-butadiene copolymer, butyl acrylate-butadiene copolymer, polyisoprene, butadiene-methyl methacrylate copolymer. , Butyl acrylate-methyl methacrylate copolymer, butadiene-ethyl acrylate copolymer, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, ethylene-isoprene copolymer, ethylene-methyl acrylate copolymer A polymer etc. are mentioned. These rubbery polymers can be used alone or in a mixture of two or more.

  As the compound (C), an epoxy group-containing modified olefin resin <I>, an acrylic polymer containing an epoxy group <II>, and a core-shell type rubbery polymer containing an epoxy group <III> A plurality of them can also be used.

  The aliphatic polyester resin composition of the present invention comprises 100% by mass as a whole, polylactic acid (A) 20 to 90% by mass, cyclic polyolefin (B) 10 to 80% by mass, and compound (C) 0.1. -10 mass%.

  Content of polylactic acid (A) becomes like this. Preferably it is 26-85 mass%, More preferably, it is 25-50 mass%. When the content of the aliphatic polyester (A) is less than 20% by mass, there is a disadvantage that the impact strength is lowered, and when this content exceeds 90% by mass, there is a problem that the heat resistance is not improved. .

  Content of cyclic polyolefin (B) becomes like this. Preferably it is 15-70 mass%, More preferably, it is 20-60 mass%. When the content of the cyclic polyolefin resin is less than 10% by mass, the intended heat resistance cannot be obtained. On the other hand, when the content of the cyclic polyolefin resin exceeds 80% by mass, physical properties such as impact resistance are deteriorated. Also, the cost is disadvantageous.

  Content of a compound (C) becomes like this. Preferably it is 0.1-10 mass%, More preferably, it is 0.2-10 mass%. If the content of the compound (C) is less than 0.1% by mass, the effect of containing it may not be seen. If this exceeds 10% by mass, the amount of the alloy resin is reduced, and a large amount The effect of adding a compound cannot be expected.

  The polylactic acid-based resin composition of the present invention preferably has a deflection temperature under load measured at a load of 0.45 MPa under a condition based on ASTM D648 of 80 ° C. or higher. When the deflection temperature under load is 80 ° C. or higher, heat resistance can be obtained without using PLA with a low D-body weight.

The polylactic acid-based resin composition of the present invention has a moisture permeability coefficient at 40 ° C. × 90% Rh of 4 g · mm / m ² · day or less when measured under the conditions based on the method B defined in JIS K7129. As a result, there is a high possibility that it can be used even in a field requiring moisture resistance.

  The polylactic acid-based resin composition of the present invention includes a heat stabilizer, an antioxidant, a pigment, a weathering agent, a flame retardant, a plasticizer, a lubricant, a release agent, and an antistatic agent as long as the effects of the present invention are not impaired. , Fillers, dispersants, endblockers and the like may be added. Examples of heat stabilizers and antioxidants include phosphite organic compounds, hindered phenol compounds, benzotriazole compounds, triazine compounds, hindered amine compounds, sulfur compounds, copper compounds, alkali metal halides, or these. Can be used. These additives are generally added at the time of melt kneading or polymerization of the resin composition. Among inorganic fillers, talc, mica, montmorillonite, layered silicate, calcium carbonate, zinc carbonate, wollastonite, silica, alumina, magnesium oxide, calcium silicate, sodium aluminate, calcium aluminate, Sodium aluminosilicate, magnesium silicate, glass balloon, carbon black, zinc oxide, antimony trioxide, zeolite, hydrotalcite, metal fiber, metal whisker, ceramic whisker, potassium titanate, boron nitride, graphite, glass fiber, carbon fiber, etc. Is mentioned. Examples of the organic filler include naturally occurring polymers such as starch, cellulose fine particles, wood flour, okara, fir shell, bran and kenaf, and modified products thereof. Examples of the terminal blocking agent include carbodiimide, epoxy, oxazoline and the like.

  The polylactic acid-based resin composition of the present invention includes polyamide (nylon), polyethylene, polypropylene, polybutadiene, polystyrene, AS resin, ABS resin, poly (acrylic acid), poly (acrylic acid) as long as the effects of the present invention are not impaired. Acid ester), poly (methacrylic acid), poly (methacrylic ester), polybutylene terephthalate, polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyarylate, and copolymers thereof Can do.

[Production method of polylactic acid resin composition]
As a method for producing the polylactic acid resin composition of the present invention, any known method can be employed. For example, the method of melt-kneading aliphatic polyester (A), cyclic polyolefin (B), and compound (C) using an extruder, a kneader, etc. is mentioned.

[Molded body]
The resin composition of the present invention can be formed into various molded products by known molding methods such as injection molding, blow molding, and extrusion molding.

  As the injection molding method, in addition to a general injection molding method, a gas injection molding method, an injection press molding method, or the like can be adopted. The cylinder temperature at the time of injection molding needs to be not less than the melting point (Tm) of the aliphatic polyester (A) or not less than the flow start temperature, and is preferably in the range of 120 to 250 ° C. If the molding temperature is too low, it tends to cause molding defects or overloading of the device due to a decrease in fluidity of the resin. On the other hand, when the molding temperature is too high, the aliphatic polyester (A) is decomposed, and problems such as a decrease in strength and coloring of the molded product occur. On the other hand, the mold temperature is preferably set to a glass transition temperature (Tg) or higher and (Tm-30) ° C. or lower in order to promote crystallization for the purpose of improving the strength, heat resistance, and barrier properties of the molded body. Specifically, 70 ° C. to 120 ° C. is preferable in order to shorten the cycle time.

  Examples of the blow molding method include a direct blow method in which molding is performed directly from raw material pellets, and an injection blow molding method (stretch blow molding method) in which blow molding is performed after molding a preform (bottomed parison) by injection molding. Can be mentioned. Both hot parison method, which performs blow molding continuously after preforming, and cold parison method, where the preform is cooled and taken out from the mold and then heated again to perform blow molding are used. it can.

  As the extrusion molding method, a T-die method, a round die method, or the like can be applied. The extrusion molding temperature needs to be equal to or higher than the melting point (Tm) of the raw aliphatic polyester (A) or the flow start temperature, and is preferably in the range of 120 to 250 ° C. If the molding temperature is too low, the operation tends to be unstable or overloaded. On the other hand, when the molding temperature is too high, the aliphatic polyester is decomposed, and problems such as a decrease in strength and coloring of the extruded product occur. A film, a sheet, a pipe or the like can be produced by extrusion.

  The molded article of the present invention preferably has a deflection temperature under a load of 0.45 MPa and a temperature of 80 ° C. or higher under the conditions in accordance with ASTM D648, similarly to the resin composition itself. More preferably, it is 85 ° C. or higher.

The film or sheet as a molded body produced from the resin composition of the present invention is 40 ° C. × 90% Rh when measured under the conditions based on the B method defined in JIS K7129, as with the resin composition itself. The moisture permeability coefficient is preferably 4 g · mm / m ² · day or less. Here, the moisture permeability coefficient is a value specific to the composition, which is not dependent on the thickness, calculated by multiplying the water vapor permeability by the thickness of the sample. This value is an index of water vapor barrier properties, and the smaller the value, the better the barrier properties.

  Hereinafter, the present invention will be described more specifically based on examples. However, the present invention is not limited to these examples. Various physical properties in the following examples and comparative examples were measured and evaluated by the following methods.

(1) Heat resistance A resin molded product was injection-molded to obtain a molded piece of 127 mm (5 inches) × 12.7 mm (1/2 inch) × 3.2 mm (1/8 inch). Using this molded piece, the deflection temperature under load (DTUL) was measured under conditions based on ASTM D648. The load was 0.45 MPa.

(2) Moisture permeability Using a desktop test press manufactured by Tester Sangyo Co., Ltd., the resin composition pellets were pressed at 240 ° C. for about 3 minutes, and then rapidly cooled to give a press having a thickness of 200 to 300 μm as a molded body. A sheet was produced. The press sheet was conditioned in advance and then measured according to JIS K7129. That is, moisture permeability was evaluated under the conditions of 40 ° C. and relative humidity 90%. The moisture permeability coefficient is
(Moisture permeability coefficient) = (moisture permeability) x (sample thickness)
Calculated from This value is an index of the water vapor barrier property, and the smaller the value, the better the water vapor barrier property.

(3) Impact strength Using the same injection-molded piece as used in (1) above, impact strength was measured under conditions in accordance with JIS K7110.

(4) Moldability An injection-molded piece was produced under conditions of a mold temperature of 85 ° C. and a cooling time of 50 seconds. The moldability was judged according to the following criteria according to the degree of deformation at the time of ejection of the injection molded piece.

○: Almost no deformation at the time of protrusion △: Small degree of deformation at the time of protrusion ×: Significant deformation at the time of protrusion

[Polylactic acid resin composition]
The raw material components used for the preparation of the polylactic acid resin composition are shown below.

[Polylactic acid (A)]
(A-1): Polylactic acid (trade name: TE 6000, manufactured by Unitika Ltd.)
(A-2): Polylactic acid (trade name: 4032D, manufactured by Nature Works)

[Cyclic polyolefin (B)]
(B-1): Ethylene-norbornene addition copolymer (trade name: TOPAS 6013, manufactured by Polyplastics)
(B-2): Ethylene-norbornene addition copolymer (trade name: APL6013T, manufactured by Mitsui Chemicals, Inc.)

[Compound (C)]
(C-1): Glycidyl methacrylate-modified polyethylene (trade name: Bondfast E, manufactured by Sumitomo Chemical Co., Ltd.)
(C-2): Epoxy group-containing acrylic resin (trade name: Joncryl-ADR 4368, manufactured by BASF)
(C-3): Epoxy-containing polyolefin-acrylic copolymer (trade name: MODIPER A4200, manufactured by NOF Corporation)
(C-4): Acrylic core-shell type impact resistance improving resin (trade name: Metablen S-2200, manufactured by Mitsubishi Rayon Co., Ltd.)
(C-5): ethylene / acrylic acid / maleic anhydride terpolymer (trade name: Bondine TX8030, manufactured by ARKEMA)

[Polyolefin (D)]
(D-1): Polypropylene (trade name: HCPP K5019F, manufactured by Chisso Corporation)

[Examples 1 to 9]
Polylactic acid (A), cyclic polyolefin (B), and compound (C), as shown in Table 1, as the types and blending ratios, PCM30 type twin screw extruder (screw diameter 29 mm, L / D = 25, average groove) Using a depth of 2.5 mm), melt kneading was performed at 240 ° C. and a screw rotation speed of 200 rpm, extrusion was performed at a discharge rate of 150 g / min, and processing into pellets. The obtained pellets were dried to obtain a resin composition.

Using the CND-15 injection molding machine manufactured by Niigata Machine Techno Co., the obtained resin composition was subjected to a cylinder temperature of 230 ° C., a mold temperature of 85 ° C., a total time of injection and holding pressure of 12 seconds, and a cooling time of 50 seconds. The above-mentioned molded piece of 127 mm (5 inches) × 12.7 mm (1/2 inch) × 3.2 mm (1/8 inch) was obtained by injection molding under the conditions. Moreover, the above-mentioned press sheet was obtained from the resin composition. While evaluating the heat resistance and impact strength of the obtained test piece, the moisture permeability of the obtained press sheet was evaluated. Further, the moldability was evaluated as described above.
The composition of the obtained resin composition and the evaluation results are shown in Table 1.

[Comparative Examples 1-5]
Polylactic acid (A), cyclic polyolefin (B), compound (C), and polyolefin (D) having the types and blending ratios shown in Table 1, and producing a resin composition by the same method as in Examples 1 to 9 above. did. Further, injection molding and press molding were performed in the same manner as in Examples 1 to 9 described above, and the physical properties of the molded bodies were evaluated.

The composition of the obtained resin composition and the evaluation results are shown in Table 1.
Resins composed of the polylactic acid of Examples 1 to 9, the cyclic polyolefin, and the compound having an epoxy group were greatly improved in heat resistance as compared to those using only the polylactic acid of Comparative Examples 1 and 2.

  On the other hand, the improvement of heat resistance was not seen in Comparative Example 1 and Comparative Example 2 only with polylactic acid, or only with the addition of an epoxy group-containing compound to polylactic acid. In Comparative Example 3, an improvement in heat resistance was confirmed by adding a cyclic polyolefin to polylactic acid, but it could not be said to be a dramatic improvement. Since Comparative Example 4 was obtained by adding a compound having no epoxy group to polylactic acid and cyclic polyolefin, a substantial heat resistance improvement effect was not confirmed as compared with Comparative Example 3. In Comparative Example 5 in which polyolefin was added to polylactic acid, no significant improvement in heat resistance was confirmed.

  The polylactic acid resin composition containing polylactic acid (A), cyclic polyolefin (B) and specific compound (C) according to the present invention is easier to mold than conventional polylactic acid resins, Excellent heat resistance and moisture permeability. Therefore, it can be used as a casing, container, medical material, automobile material, various sheets, and other various industrial materials for electronic / electrical / communication equipment.

Claims (4)

  100% by mass as a whole, 20 to 90% by mass of polylactic acid (A), 10 to 80% by mass of cyclic polyolefin (B) comprising an addition copolymer of a cyclic olefin and an α-olefin or a hydrogenated product thereof, The compound (C) contains 0.1 to 10% by mass, and the compound (C) contains an epoxy group-containing modified olefin resin, an acrylic polymer containing an epoxy group, and a core-shell type rubbery material containing an epoxy group. A polylactic acid resin composition, wherein the composition is selected from polymers.   2. The polylactic acid-based resin composition according to claim 1, wherein the deflection temperature under load measured at a load of 0.45 MPa is 80 ° C. or higher under the conditions based on ASTM D648. 3. The moisture permeability coefficient at 40 ° C. × 90% Rh when measured under conditions conforming to the method B defined in JIS K7129 is 4 g · mm / m ² · day or less. The polylactic acid resin composition described.   A molded body comprising the polylactic acid resin composition according to any one of claims 1 to 3.