JP2005226054A - Aliphatic polyester resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aliphatic polyester resin composition capable of giving a molded article which is biodegradable and has good molding external appearances and excellent impact resistance. <P>SOLUTION: The aliphatic polyester resin composition is obtained by melt-kneading 100 pts. wt. of an aliphatic polyester resin (A), 1-60 pts. wt. of a modified conjugated diene polymer (B) modified with a compound bearing one or more polar groups selected from among an amino group, imino group, hydroxy group, epoxy group, carboxy group and acid anhydride group and 0.01-5 pts. wt. of a free radical initiator (C). <P>COPYRIGHT: (C)2005,JPO&amp;NCIPI

Description

  The present invention relates to a polylactic acid resin composition which is biodegradable, has a good molded appearance, and has excellent impact resistance, and a method for producing the same.

In recent years, biodegradable polymers that are decomposed by microorganisms and the like have attracted attention with increasing social demand for protection of the global environment.
Specific examples of biodegradable polymers include those that can be melt-molded such as aliphatic polyesters such as polybutylene succinate, polycaprolactone, and polylactic acid, and copolymers of terephthalic acid / 1,4-butanediol / adipic acid. Examples include polyester. Among these aliphatic polyesters, polylactic acid, which is widely distributed in nature and harmless to animals, plants and animals, has a melting point of 140 to 175 ° C., has sufficient heat resistance, has high strength and is relatively inexpensive. It is expected as a thermoplastic biodegradable resin. However, the impact resistance is low and improvement is required.

As means for improving the impact resistance of polylactic acid, a method of adding an aliphatic polyester such as polycaprolactone, a method of adding a polyester oligomer, a method of adding a polyester plasticizer, and the like are known. As shown, a dramatic improvement in impact resistance is not observed with a small amount of rubber component. In addition, when a large amount of rubber component is used, problems such as inferior molding processability and impaired surface appearance occur.
A technique of adding a free radical generator to polylactic acid is also known.
For example, there is an example in which melt tension is improved by reactive extrusion of an organic peroxide to polylactic acid (see, for example, Patent Documents 1 and 2).

In addition, for the purpose of developing a composition in which a biomass material and a biodegradable resin are combined, by heating and kneading an aliphatic polyester resin and a biomass material, an unsaturated carboxylic acid or a derivative thereof in the presence of a radical generator, There is also an example in which a method for producing a composite resin composition excellent in mechanical properties and heat fluid processability during molding is disclosed (for example, see Patent Document 3).
Japanese Patent Application Laid-Open No. 2001-26658 discloses a polylactic acid resin composition obtained by melt-kneading a resin component comprising polylactic acid and an aliphatic polyester component and an organic peroxide component in a temperature range of 150 to 250 ° C. It is said that a composition with improved elongation and melt tension is obtained.

In JP 2001-64379 A, polylactic acid and polyester other than polylactic acid and a radical reaction initiator are melt-mixed so that the polymers are compatible with each other, maintaining biodegradability and having high transparency. It is described that a composition having excellent mechanical properties can be obtained.
However, in these inventions, the dramatic improvement in impact resistance as shown in the present invention is not recognized.

Japanese Patent Laid-Open No. 10-120889 JP-A-8-503723 JP-A-8-245866 Japanese Patent Laid-Open No. 2001-26658 JP 2001-64379 A

  The present invention is intended to solve the above-described problems, and provides a polylactic acid resin composition that is biodegradable, has a good appearance of a molded product, and has excellent impact resistance, and a method for producing the same. .

As a result of intensive studies to solve the above-mentioned problems, the present inventor was obtained by adding a specific modified conjugated diene polymer and a free radical generator to a polylactic acid resin and melt-kneading them. The inventors have found that the resin composition exhibits excellent impact resistance and have completed the present invention.
That is, the present invention melt-kneads 100 parts by weight of a polylactic acid resin (A), 1 to 60 parts by weight of a modified conjugated diene polymer (B) and 0.01 to 5 parts by weight of a free radical generator (C). The present invention relates to a polylactic acid-based resin composition and a method for producing the same, and by molding the composition of the present invention, biodegradability and impact resistance are dramatically improved, and an excellent molded product. A molded product having an appearance can be obtained.

  By using the composition of the present invention, it is possible to obtain a molded article that is biodegradable, has a good molded appearance, and is excellent in impact resistance.

Hereinafter, the present invention will be specifically described.
Examples of the aliphatic polyester (A) of the present invention include a polymer mainly composed of an aliphatic hydroxycarboxylic acid and a polymer mainly composed of an aliphatic polycarboxylic acid and an aliphatic polyhydric alcohol. Specifically, polymers having aliphatic hydroxycarboxylic acid as a main component include polyglycolic acid, polylactic acid, poly-3-hydroxybutyric acid, poly-4-hydroxybutyric acid, poly-4-hydroxyvaleric acid, poly-3- Hydroxyhexanoic acid or polycaprolactone, etc., and examples of the polymer mainly composed of aliphatic polycarboxylic acid and aliphatic polyhydric alcohol include polyethylene adipate, polyethylene succinate, polybutylene adipate, or polybutylene succinate. Is mentioned. These aliphatic polyesters can be used alone or in combination of two or more. Among these aliphatic polyesters, a polymer containing hydroxycarboxylic acid as a main constituent is preferable, and a polylactic acid resin is particularly preferably used. These (a) components can use 1 or more types.

  The polylactic acid resin in the present invention is polylactic acid, a lactic acid-hydroxycarboxylic acid copolymer, and a mixture of polylactic acid and a lactic acid-hydroxycarboxylic acid copolymer, wherein the lactic acid ratio in the polymer is 75% by weight or more. As the polymer raw material, lactic acid and hydroxycarboxylic acid are used. As lactic acid, L-lactic acid, D-lactic acid, DL-lactic acid or a mixture thereof or lactide which is a cyclic dimer of lactic acid can be used. These lactic acids can be used in various combinations such that the L-lactic acid content in the obtained L-lactic acid polymer is 75% by weight or more. Examples of hydroxycarboxylic acids that can be used in combination with lactic acids include glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 4-hydroxyvaleric acid, 5-hydroxyvaleric acid, and 6-hydroxycaproic acid. Cyclic dimers such as glycolide, which is a dimer of glycolic acid, or cyclic ester intermediates such as ε-caprolactone can also be used.

  The polylactic acid resin used in the present invention is made from lactic acid having an L-lactic acid content of 75% by weight or more as a raw material, or a mixture of lactic acid and hydroxycarboxylic acid, and the L-lactic acid content in the mixture is 75% by weight. Direct dehydration polycondensation using the mixture prepared as described above as a raw material, or a cyclic dimer of lactide or hydroxycarboxylic acid, for example, a dimer of glycolic acid, which is a cyclic dimer of lactic acid. It can be obtained by a ring-opening polymerization method using a cyclic ester intermediate such as glycolide or ε-caprolactone.

  In the case of producing by direct dehydration condensation, the raw material lactic acid or lactic acid and hydroxycarboxylic acid are preferably subjected to azeotropic dehydration condensation in the presence of an organic solvent, particularly a phenyl ether solvent, and particularly preferably a solvent distilled by azeotropic distillation. Polymerization is performed by a method in which water is removed from the solvent and the solvent is brought into a substantially anhydrous state and returned to the reaction system to obtain a high molecular weight polylactic acid resin having strength suitable for the present invention. The weight average molecular weight of the polylactic acid-based resin is preferably a high molecular weight within the range that can be molded, and more preferably 30,000 or more. If the weight average molecular weight is less than 30,000, the strength of the molded product may be reduced and may not be suitable for practical use. Even if the weight average molecular weight is 1,000,000 or more, it can be used for the production of the molded product of the present invention if the moldability is devised. Further, if the weight average molecular weight exceeds 5 million, the moldability may be inferior.

  The modified conjugated diene polymer used as the component (B) in the present invention is at least one group selected from an amino group, an imino group, a hydroxyl group, an epoxy group, a carboxyl group, and an acid anhydride group, or two or more types. It is a conjugated diene polymer modified with a compound having a polar group. Here, the conjugated diene polymer is a homopolymer of conjugated diene, a copolymer of conjugated diene and vinyl aromatic hydrocarbon, or a hydrogenated product thereof. The polymer conjugated dienes include 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, and the like. Among them, one or more kinds can be used, and 1,3-butadiene, isoprene or a combination thereof is generally preferred. The aromatic vinyl compound is one of styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 1,3-dimethylstyrene, α-methylstyrene, vinylnaphthalene, vinylanthracene and the like. Alternatively, two or more types can be used, and styrene is generally preferable. The content of the aromatic vinyl compound in the copolymer is 50% by weight or less, preferably 40% by weight or less, more preferably 30% by weight or less. If it exceeds 50% by weight, the effect of imparting impact resistance is insufficient, which is not preferable. Both units may be copolymerized randomly, copolymerized in blocks, or a copolymer containing random copolymerized blocks, but preferably, for example, mainly composed of vinyl aromatic hydrocarbons. It is a block copolymer comprising at least one polymer block A and at least one polymer block B mainly composed of conjugated diene, or a hydrogenated product thereof. More preferably, it is a block copolymer comprising at least one polymer block A mainly composed of vinyl aromatic hydrocarbon and one polymer block B mainly composed of conjugated diene.

  Examples of the method for producing a copolymer of a conjugated diene polymer and a vinyl aromatic hydrocarbon used in the present invention include Japanese Patent Publication No. 36-19286, Japanese Patent Publication No. 43-171979, and Japanese Patent Publication No. 46-. No. 32415, JP-B 49-36957, JP-B 48-2423, JP-B 48-4106, JP-B 56-28925, JP-B 51-49567, JP-A 59-166518 And the methods described in JP-A-60-186577 and the like. The block copolymer obtained by these methods has, for example, a structure represented by the following general formula (for a hydrogenated product, a polymer structure before hydrogenation).

(AB) _n , (BA) _n , A- (BA) _n , B- (AB) _n ,
[(BA) _n ] _m- X, [(AB) _n ] _m- X,
[(BA) _n- B] _m- X, [(AB) _n- A] _m- X
(In the above formula, A is a polymer block mainly composed of vinyl aromatic hydrocarbons, and B is a polymer block mainly composed of conjugated dienes. X is a residue of a coupling agent or a polyfunctional organolithium compound. And n is an integer of 1 or more, generally an integer of 1 to 5, and m is an integer of 2 or more, generally an integer of 2 to 10.)

  In the above, the polymer block A mainly composed of vinyl aromatic hydrocarbon is preferably a vinyl aromatic hydrocarbon containing 50% by weight or more, more preferably 70% by weight or more of vinyl aromatic hydrocarbon and conjugated diene. The copolymer block or / and the vinyl aromatic hydrocarbon homopolymer block, and the polymer block B mainly composed of a conjugated diene is preferably an amount exceeding 50% by weight, more preferably 60%. A copolymer block of a conjugated diene and a vinyl aromatic hydrocarbon or / and a conjugated diene homopolymer block containing at least% by weight is shown. The vinyl aromatic hydrocarbons in the copolymer block may be distributed uniformly or in a tapered shape. In the copolymer block, a plurality of portions where the vinyl aromatic hydrocarbons are uniformly distributed and / or a portion where they are distributed in a tapered shape may coexist.

In the present invention, examples of the solvent used for the production of the conjugated diene polymer include aliphatic hydrocarbons such as butane, pentane, hexane, isopentane, heptane, octane, and isooctane, cyclopentane, methylcyclopentane, cyclohexane, and methyl. Cycloaliphatic hydrocarbons such as cyclohexane and ethylcyclohexane or aromatic hydrocarbons such as benzene, toluene, ethylbenzene and xylene can be used. These may be used alone or in combination of two or more.
In the present invention, the organolithium compound used as a polymerization initiator in the production of a conjugated diene polymer is a compound in which one or more lithium atoms are bonded in the molecule, for example, ethyl lithium, n-propyl lithium, isopropyl Lithium, n-butyllithium, sec-butyllithium, tert-butyllithium, hexamethylenedilithium, butadienyldilithium, isoprenyldilithium and the like can be used. These may be used alone or in combination of two or more. The organolithium compound may be added in one or more divided portions during the polymerization in the production of the block copolymer.

  In the present invention, for the purpose of controlling the polymerization rate during production of the conjugated diene polymer, controlling the microstructure of the polymerized conjugated diene moiety, controlling the reactivity ratio between the vinyl aromatic hydrocarbon and the conjugated diene, Randomizing agents can be used. Examples of polar compounds and randomizing agents include ethers, amines, thioethers, phosphines, phosphoramides, potassium or sodium salts of alkylbenzene sulfonic acids, potassium or sodium alkoxides, and the like. Specific examples of the ethers include dimethyl ether, diethyl ether, diphenyl ether, tetrahydrofuran, diethylene glycol dimethyl ether, and diethylene glycol dibutyl ether. Examples of amines include tertiary amines, trimethylamine, triethylamine, tetramethylethylenediamine, and other cyclic tertiary amines. Examples of phosphine and phosphoramide include triphenylphosphine and hexamethylphosphoramide.

In the present invention, the polymerization temperature for producing the conjugated diene polymer is preferably 10 to 150 ° C, more preferably 30 to 120 ° C.
The polymerization time varies depending on the conditions, but is preferably within 48 hours, particularly preferably 0.5 to 10 hours. The polymerization atmosphere is preferably an inert gas atmosphere such as nitrogen gas. The polymerization pressure is not particularly limited as long as it is within a range sufficient to maintain the monomer and solvent in a liquid phase within the above polymerization temperature range. Furthermore, it is preferable to pay attention so that impurities that inactivate the catalyst and the living polymer, for example, water, oxygen, carbon dioxide gas, and the like are not mixed in the polymerization system.

The modified conjugated diene polymer (B) used in the present invention has at least one or two or more polar groups selected from an amino group, an imino group, a hydroxyl group, an epoxy group, a carboxyl group, and an acid anhydride group. It is a conjugated diene polymer characterized by being modified with a compound having it. Particularly preferred polar groups are amino groups and / or imino groups. By modifying with an atomic group having such polarity, the effect of improving the impact resistance of the polylactic acid resin becomes very remarkable.
The modified conjugated diene polymer has a functional group related to the polymer block A and / or the polymer block B, or a polymer in which an atomic group having a functional group related to the polymer of the conjugated diene is bonded to the terminal. The aforementioned block copolymer having an atomic group bonded to the terminal (hereinafter referred to as a modified block copolymer) is particularly preferred. The structure of the modified block copolymer is represented by the following general formula, for example.

(AB) _n -Y, (BA) _n -Y,
A- (BA) _n -Y, B- (AB) _n -Y,
Y- (AB) _n -Y, YA- (BA) _n -Y,
Y-B- (AB) _n -Y,
_{[(B-A) n]} m -Y, [(A-B) n] m -Y,
[(BA) _n- B] _m- Y, [(AB) _n- A] _m- Y
(In the above formula, A is a polymer block mainly composed of vinyl aromatic hydrocarbon, B is a polymer block mainly composed of conjugated diene, and n is an integer of 1 or more, generally 1-5. And m is an integer of 2 or more, generally an integer of 2 to 10. Y is a modifier residue to which an atomic group having a functional group described below is bonded.
The modified block copolymer used in the present invention may be any mixture of modified block copolymers represented by the above general formula.

A method for obtaining a modified conjugated diene polymer is such that a modifying agent in which a functional group having a functional group is bonded to the living end of the conjugated diene polymer or an atomic group in which the functional group is protected by a known method is bonded. And a method of reacting the modifying agent. Depending on the type of modifier, the hydroxyl group or amino group may be an organometallic salt at the stage of reaction of the modifier, but in that case, treatment with a compound having active hydrogen such as water or alcohol is required. Can be converted into a hydroxyl group or an amino group. In the present invention, after the modifier is reacted with the living terminal of the conjugated diene polymer, a part of the conjugated diene polymer that is not modified may be mixed. The proportion of the unmodified conjugated diene polymer mixed in the modified conjugated diene polymer is preferably 70% by weight or less, more preferably 60% by weight or less, and still more preferably 50% by weight or less.
In the present invention, a silanol group, an alkoxy group that can be used to obtain a modified conjugated diene copolymer modified with an amino group, an imino group, a hydroxyl group, an epoxy group, a carboxyl group, and an acid anhydride group described later. Examples of the atomic group having at least one functional group selected from silane include atomic groups selected from the following general formula.

(In the above formula, R ⁹ and R ^{12 to} R ¹⁴ are each a hydrogen atom or a hydrocarbon group having 1 to 24 carbon atoms, or a carbon group having a functional group selected from a hydroxyl group, an epoxy group, a silanol group, and an alkoxysilane. the hydrocarbon group ^{.R 10} of 24 hydrocarbon chain having 1 to 30 carbon atoms or a hydroxyl group, a hydrocarbon chain having 1 to 30 carbon atoms having an epoxy group, a silanol group, a functional group selected from alkoxysilane. Note ^{R 9} , And R ^{12 to} R ¹⁴ and R ¹⁰ hydrocarbon chain are bonded with elements such as oxygen, nitrogen, silicon and the like in a bonding mode other than hydroxyl, epoxy, silanol, and alkoxysilane. R ¹¹ is hydrogen or an alkyl group having 1 to 8 carbon atoms.)
In the present invention, a silanol group, an alkoxysilane, which can be used to obtain a conjugated diene copolymer modified with an amino group, an imino group, a hydroxyl group, an epoxy group, and a carboxyl group and an acid anhydride group described later Examples of the modifying agent used to obtain a conjugated diene polymer having at least one atomic group having at least one functional group selected from the following are listed.

  For example, tetraglycidylmetaxylenediamine, tetraglycidyl-1,3-bisaminomethylcyclohexane, tetraglycidyl-p-phenylenediamine, tetraglycidyldiaminodiphenylmethane, diglycidylaniline, diglycidylorthotoluidine, γ-glycidoxyethyltrimethoxy Silane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxybutyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltripropoxysilane, γ-glycidoxypropyltributoxy Examples include silane.

  Also, γ-glycidoxypropyltriphenoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylethyldimethoxysilane, γ-glycidoxypropylethyldiethoxysilane, γ-glycidoxypropylmethyl Diethoxysilane, γ-glycidoxypropylmethyldipropoxysilane, γ-glycidoxypropylmethyldibutoxysilane, γ-glycidoxypropylmethyldiphenoxysilane, γ-glycidoxypropyldimethylmethoxysilane, γ-glycyl Sidoxypropyldiethylethoxysilane and γ-glycidoxypropyldimethylethoxysilane are exemplified.

  Also, γ-glycidoxypropyldimethylphenoxysilane, γ-glycidoxypropyldiethylmethoxysilane, γ-glycidoxypropylmethyldiisopropeneoxysilane, bis (γ-glycidoxypropyl) dimethoxysilane, bis (γ -Glycidoxypropyl) diethoxysilane, bis (γ-glycidoxypropyl) dipropoxysilane, bis (γ-glycidoxypropyl) dibutoxysilane, bis (γ-glycidoxypropyl) diphenoxysilane, bis (Γ-glycidoxypropyl) methylmesisilane and bis (γ-glycidoxypropyl) methylethoxysilane are mentioned.

  Also, bis (γ-glycidoxypropyl) methylpropoxysilane, bis (γ-glycidoxypropyl) methylbutoxysilane, bis (γ-glycidoxypropyl) methylphenoxysilane, tris (γ-glycidoxypropyl) Methoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-methacryloxymethyltrimethoxysilane, γ-methacryloxyethyltriethoxysilane, bis (γ-methacryloxypropyl) dimethoxysilane, Examples include tris (γ-methacryloxypropyl) methoxysilane, β- (3,4-epoxycyclohexyl) ethyl-trimethoxysilane, and β- (3,4-epoxycyclohexyl) ethyl-triethoxysilane.

  Β- (3,4-epoxycyclohexyl) ethyl-tripropoxysilane, β- (3,4-epoxycyclohexyl) ethyl-tributoxysilane, β- (3,4-epoxycyclohexyl) ethyl-triphenoxysilane, β- (3,4-epoxycyclohexyl) propyl-trimethoxysilane, β- (3,4-epoxycyclohexyl) ethyl-methyldimethoxysilane, β- (3,4-epoxycyclohexyl) ethyl-ethyldimethoxysilane, β- (3,4-epoxycyclohexyl) ethyl-ethyldiethoxysilane, β- (3,4-epoxycyclohexyl) ethyl-methyldiethoxysilane, β- (3,4-epoxycyclohexyl) ethyl-methyldipropoxysilane, β -(3,4-epoxycyclohexyl) ethyl And methyl dibutoxy silane.

  Β- (3,4-epoxycyclohexyl) ethyl-methyldiphenoxysilane, β- (3,4-epoxycyclohexyl) ethyl-dimethylmethoxysilane, β- (3,4-epoxycyclohexyl) ethyl-diethylethoxysilane Β- (3,4-epoxycyclohexyl) ethyl-dimethylethoxysilane, β- (3,4-epoxycyclohexyl) ethyl-dimethylpropoxysilane, β- (3,4-epoxycyclohexyl) ethyl-dimethylbutoxysilane, β -(3,4-epoxycyclohexyl) ethyl-dimethylphenoxysilane, β- (3,4-epoxycyclohexyl) ethyl-diethylmethoxysilane, β- (3,4-epoxycyclohexyl) ethyl-methyldiisopropeneoxysilane, 1,3-dimethyl-2 Imidazolidinone, 1,3-diethyl-2-imidazolidinone, N, N′-dimethylpropyleneurea, N-methylpyrrolidone, N- (1,3-dimethylbutylidene) -3- (triethoxysilyl)- 1-propanamine etc. are mentioned. Among these, 1,3-dimethyl-2-imidazolidinone and / or 1,3-diethyl-2-imidazolinone is preferable.

  By reacting the above modifier, a conjugated diene polymer (polymer block A and / or polymer block B in the case of a block copolymer) is added to a hydroxyl group, an epoxy group, an amino group, an imino group, a silanol group, an alkoxy group. A conjugated diene polymer having at least one residue of a modifying agent to which an atomic group having at least one functional group selected from silanes is bonded or a hydrogenated product thereof is obtained. The position where the residue of the modifier is bonded to the modified block copolymer is not particularly limited, but is preferably bonded to the polymer block A in order to obtain a composition having excellent physical properties at high temperatures.

  In the present invention, a hydrogenated product of a conjugated diene polymer is obtained by hydrogenating a conjugated diene polymer (in the case of a block copolymer, the block copolymer obtained above). The hydrogenation catalyst used in the case of hydrogenation is not particularly limited, and is conventionally known (1) supported by supporting a metal such as Ni, Pt, Pd, Ru on carbon, silica, alumina, diatomaceous earth, or the like. Type heterogeneous catalyst, (2) so-called Ziegler-type hydrogenation catalyst using an organic acid salt such as Ni, Co, Fe, Cr, or a transition metal salt such as acetylacetone salt and a reducing agent such as organic aluminum, (3) A homogeneous hydrogenation catalyst such as a so-called organometallic complex such as an organometallic compound such as Ti, Ru, Rh, or Zr is used. Specific examples of the hydrogenation catalyst include Japanese Patent Publication No. 42-8704, Japanese Patent Publication No. 43-6636, Japanese Patent Publication No. 63-4841, Japanese Patent Publication No. 1-337970, Japanese Patent Publication No. 1-53851, The hydrogenation catalyst described in Japanese Patent Publication No. 2-9041 can be used. Preferable hydrogenation catalysts include a mixture with a titanocene compound and / or a reducing organometallic compound.

As the titanocene compound, a compound described in JP-A-8-109219 can be used. Specific examples thereof include (substituted) cyclohexane such as biscyclopentadienyl titanium dichloride and monopentamethylcyclopentadienyl titanium trichloride. Examples thereof include compounds having at least one ligand having a pentadienyl skeleton, an indenyl skeleton, or a fluorenyl skeleton. Examples of the reducing organometallic compound include organic alkali metal compounds such as organolithium, organomagnesium compounds, organoaluminum compounds, organoboron compounds, and organozinc compounds.
The hydrogenation reaction is generally carried out in the temperature range of 0 to 200 ° C, preferably 30 to 150 ° C. The pressure of hydrogen used in the hydrogenation reaction is 0.1 to 15 MPa, preferably 0.2 to 10 MPa, and more preferably 0.3 to 5 MPa. The hydrogenation reaction time is 3 minutes to 10 hours, preferably 10 minutes to 5 hours. For the hydrogenation reaction, any of a batch process, a continuous process, or a combination thereof may be used.

  In the hydrogenated product of the modified conjugated diene polymer used in the present invention, the hydrogenation rate of the unsaturated double bond based on the conjugated diene can be arbitrarily selected according to the purpose. When obtaining a hydrogenated vinyl aromatic hydrocarbon elastomer having good thermal stability and weather resistance, more than 70%, preferably 75% or more of the unsaturated double bonds based on the conjugated diene compound in the polymer. It is recommended that 85% or more, particularly preferably 90% or more, be hydrogenated. In addition, when obtaining a hydrogenated product having good thermal stability, the hydrogenation rate is preferably 3 to 70%, alternatively 5 to 65%, particularly preferably 10 to 60%. In particular, in order to impart impact resistance, the hydrogenation rate is preferably 50% or less. The hydrogenation rate of the aromatic double bond based on the vinyl aromatic hydrocarbon in the copolymer is not particularly limited, but the hydrogenation rate is 50% or less, preferably 30% or less, more preferably 20%. The following is preferable. The hydrogenation rate can be known by a nuclear magnetic resonance apparatus (NMR).

The weight average molecular weight of the modified conjugated diene polymer used in the present invention is preferably 30,000 or more from the viewpoint of the impact strength improving effect of the composition, and preferably 1,000,000 or less, more preferably 60,000 to 800,000 from the viewpoint of workability. More preferably, it is 70 to 600,000. The weight average molecular weight is measured by gel permeation chromatography (GPC), and a calibration curve obtained by measuring the molecular weight of the chromatogram peak from a commercially available standard polystyrene (created using the peak molecular weight of standard polystyrene) Can be determined using
When the conjugated diene polymer is a block copolymer, the content of the vinyl aromatic hydrocarbon homopolymer block is determined by oxidative decomposition using di-tertiary butyl hydroperoxide using osmium tetroxide as a catalyst (IM KOLTHOFF, et-al., J. Polym. Sci. 1, 429 (1946)), a vinyl aromatic hydrocarbon homopolymer block component obtained by decomposing a modified block copolymer before hydrogenation (however, The amount of the component having a polymerization degree of 30 or less is removed) can be determined using an ultraviolet spectrophotometer or the like.

The solution of the conjugated diene polymer or its hydrogenated product obtained as described above can remove the catalyst residue as needed, and separate the conjugated diene polymer or its hydrogenated product from the solution. As a method for separating the solvent, for example, a method of adding a polar solvent which is a poor solvent for a polymer such as acetone or alcohol to the polymer solution, and precipitating the polymer, collecting the polymer solution in hot water with stirring. A method of charging and removing the solvent by steam stripping and recovering, or a method of directly heating the polymer solution and distilling off the solvent can be mentioned.
In addition, stabilizers, such as various phenol type stabilizers, phosphorus type stabilizers, sulfur type stabilizers, and amine type stabilizers, can be added to the modified conjugated diene polymer used in the present invention.

  In the present invention, a method for obtaining a modified conjugated diene polymer modified with a carboxyl group or an acid anhydride group is a functional group selected from the aforementioned hydroxyl group, amino group, imino group, epoxy group, silanol group, and alkoxysilane. And a method in which a modified conjugated diene polymer having at least one atomic group having at least one is bonded with a modifier having a carboxyl group or a modifier having an acid anhydride group.

Specific examples of the modifying agent having a carboxyl group include aliphatic carboxylic acids such as maleic acid, oxalic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, carbaryl acid, cyclohexanedicarboxylic acid, and cyclopentanedicarboxylic acid. And aromatic carboxylic acids such as acid, terephthalic acid, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid, trimesic acid, trimellitic acid, and pyromellitic acid.
Specific examples of the modifier having an acid anhydride group include maleic anhydride, itaconic anhydride, pyromellitic anhydride, cis-4-cyclohexane-1,2-dicarboxylic anhydride, 1,2,4,5- Examples thereof include benzenetetracarboxylic dianhydride and 5- (2,5-dioxytetrahydroxyfuryl) -3-methyl-3-cyclohexene-1,2-dicarboxylic-dicarboxylic anhydride.

  In addition, as another method for obtaining a modified conjugated diene polymer modified with a carboxyl group or an acid anhydride group, a conjugated diene polymer may be an α, β-unsaturated carboxylic acid or a derivative thereof such as an anhydride thereof, Examples of the method include graft modification with an esterified product, an amidated product, and an imidized product. Specific examples of α, β-unsaturated carboxylic acid or derivatives thereof include maleic anhydride, maleic anhydride imide, acrylic acid or ester thereof, methacrylic acid or ester thereof, endo-cis-bicyclo [2,2,1 ] -5-heptene-2,3-dicarboxylic acid or an anhydride thereof. The addition amount of the α, β-unsaturated carboxylic acid or derivative thereof is generally 0.01 to 20 parts by weight, preferably 0.1 to 10 parts by weight per 100 parts by weight of the vinyl aromatic hydrocarbon elastomer.

The blending amount of the modified conjugated diene polymer as the component (B) in the present invention is 1 part by weight or more from the viewpoint of improving impact resistance with respect to 100 parts by weight of the aliphatic polyester resin as the component (A). From the viewpoint of workability and appearance of the molded product, it is 60 parts by weight or less, preferably 3 to 50 parts by weight.
The (C) component free radical generator means a radical generator such as peroxide, but is not particularly limited. Examples of the free radical generator include t-butyl hydroperoxide, potassium persulfate, ammonium persulfate, azobiscyanovaleric acid, azobisisobutyronitrile, and the like. A redox catalyst comprising a combination of these free radical generators and sulfites and sulfoxylates can also be used. Examples of the organic oxide include ketone peroxides, hydroperoxides, diacyl peroxides, dialkyl peroxides, peroxyketals, alkyl peresters, and carbonates.

The free radical generator is 0.01 parts by weight or more from the viewpoint of improving impact resistance with respect to 100 parts by weight of the polylactic acid resin as component (A), and 5.0 from the viewpoint of molding processability and appearance of the molded product. It is melt-kneaded below 0.1 parts by weight, preferably 0.1 to 3.0 parts by weight.
In order to obtain the composition of the present invention, the mixing reaction method and mixing apparatus of the aliphatic polyester resin (A), the modified conjugated diene polymer (B) and the free radical generator (C) are the same as those used in a conventional kneading apparatus. Although it can be used and is not particularly limited, those which can be continuously processed are industrially advantageous and desirable, and generally known short-shaft and twin-screw extruders are used.
For example, the aliphatic polyester resin (A), the modified conjugated diene polymer (B), and the free radical generator (C) are mixed at a predetermined ratio, put into a hopper of a molding machine, melted, and immediately molded. Also good. Moreover, after each component is melt-mixed, it may be once pelletized and then melt-molded as necessary. In order to mix uniformly, the method of once pelletizing is preferable.

The melt extrusion temperature is appropriately selected in consideration of the melting point and mixing ratio of the biodegradable resin to be used, but is usually in the range of 100 to 250 ° C. It is preferable to select from the range of 120 to 220 ° C. The reaction melting time is preferably within 20 minutes, more preferably within 10 minutes.
The method for adding the free radical generator (C) is not particularly limited, but a mixture of the three components in advance as described above may be melt-mixed. If it is a liquid substance, a plunger pump, a tube pump, etc. A polylactic acid resin (A) and a modified conjugated diene polymer (B) may be added dropwise to a melt-mixed place using a highly quantitative feed pump.

When molding the aliphatic polyester resin composition of the present invention, injection molding, extrusion molding, blow molding, vacuum molding, compression molding, and the like similar to general plastics can be performed, such as rods, bottles, containers, etc. These various molded products can be easily obtained.
In the present invention, in order to promote crystallization of the aliphatic polyester resin composition, a crystal nucleating agent, a crystallization accelerator and the like can be blended. The crystal nucleating agent and the crystallization accelerator are not particularly limited, but talc, silica, aromatic organophosphate metal salt compounds, dibenzylidene sorbitol compounds, fatty acid amides, plant waxes and the like are preferable.
In order to crystallize the aliphatic polyester resin composition, there are a method of annealing the molded product at the crystallization temperature, and a method of setting the mold temperature to the crystallization temperature when molding the composition and holding it for a certain period of time. .

The method of holding the composition at a crystallization temperature for a certain period of time when molding the composition is such that, in injection molding, blow molding and compression molding, the mold temperature is changed from the crystallization start temperature to the end temperature when the scanning differential thermal analyzer (DSC) is cooled. The method of crystallizing the composition of the present invention in a mold may be used.
Furthermore, the aliphatic polyester composition of the present invention may include a conventionally known plasticizer, antioxidant, heat stabilizer, light stabilizer, ultraviolet absorber, antistatic agent, release agent, fragrance, lubricant as necessary. Various additives such as flame retardants, foaming agents, pigments, colorants, various fillers, fillers, antibacterial / antifungal agents, and the like may be blended.
Next, the present invention will be described with reference to examples and reference examples.

The characteristic evaluation of the resin composition molded article was as follows.
(1) Charpy impact strength (notched): Measured using a test piece of 80 mm × 10 mm × 4 mm in accordance with ISO179 standard.
Moreover, in Table 1, the definition prescribed | regulated to the same specification and the evaluation result of not destroying (non-break) were described.
(2) Molded appearance When the surface of the injection-molded product is observed, the surface is smooth and glossy, and the appearance is good. ○ The surface smoothness or gloss is slightly inferior. In the case of, it evaluated as x.

The characteristics evaluation of the polylactic acid resin was performed as follows.
(3) Molecular weight GPC [Tosoh HLC-8120GPC, detection RI, column is TSK gel GMHHR-M], the solvent was tetrahydrofuran, the measurement temperature was 40 ° C., and the weight average molecular weight was calculated in terms of commercially available standard polystyrene.
(4) Optical purity, L-form / D-form composition ratio Hydrolyzed with 1N-NaOH aqueous solution using HPLC [LC-10A-VP UV (254 nm) detection made by Shimadzu Corporation] equipped with optical isomer separation column, HCl Using the aqueous solution neutralized with the sample, the ratio of L-form and D-form was determined.

(5) Melting point and glass transition temperature Using DSC [Pyris 1 manufactured by Perkin Elmer], the melting point and glass transition temperature were determined by a temperature change of 20 ° C./min in a nitrogen atmosphere.
The properties of the block copolymer used as the conjugated diene polymer were evaluated as follows.
(6) Styrene content It computed from the absorption intensity of 262 nm using the ultraviolet spectrophotometer (Hitachi UV200).
(7) The amount of 1,2 bonds and the hydrogenation rate were measured using a nuclear magnetic resonance apparatus (DPX-400 manufactured by BRUCKER).

(8) Weight average molecular weight GPC [Measured by LC10 manufactured by Shimadzu Corporation, column by Shimpac GPC805 + GPC804 + GPC804 + GPC803 manufactured by Shimadzu Corporation], tetrahydrofuran was used as a solvent, and measurement conditions were performed at a temperature of 35 ° C. The weight average molecular weight was obtained by using a calibration curve (created using the peak molecular weight of standard polystyrene) obtained by measuring the molecular weight of the peak of the chromatogram from measurement of commercially available standard polystyrene. The molecular weight when there are a plurality of peaks in the chromatogram refers to the average molecular weight determined from the molecular weight of each peak and the composition ratio of each peak (determined from the area ratio of each peak in the chromatogram).

(9) Number average molecular weight of styrene homopolymer block A method of oxidatively decomposing a block copolymer with di-tert-butyl hydroperoxide using osmium tetroxide as a catalyst (IM KOLTHOFF, et-al., J. MoI. Polym.Sci. 1,429 (1946)), a styrene homopolymer block component was obtained from the block copolymer before hydrogenation (however, the component having a polymerization degree of 30 or less was removed), and GPC measurement of the component was performed. Determined by

(10) Content of styrene homopolymer block (block rate)
The styrene homopolymer block obtained by the above oxidative decomposition was analyzed with an ultraviolet spectrophotometer and calculated using the following formula.
Block ratio (%) = (% by weight of styrene homopolymer block in hydrogenated block copolymer) / (% by weight of total styrene in hydrogenated block copolymer) × 100
Polylactic acid-based resins used in the following examples are known, for example, “Polylactide” written by Hidehito Tsuji in Biopolymers Vol. 4 (Wiley-VCH 2002) PP129-178 and (A-1) and (A-2) two types of polylactic acid by ring-opening polymerization of lactide using a tin-based catalyst according to JP-A-H05-504731 Prepared.
The weight average molecular weight, the D-form content, the glass transition temperature, and the melting point of (A-1) are 210,000, 3.9%, 55 ° C, 157 ° C, respectively, and (A-2) is 200,000, 1 2%, 58 ° C, 170 ° C.
Furthermore, the manufacture example of the modified conjugated diene type polymer used in the following examples is shown.

[Production Example 1] Modified conjugated diene polymer; B-1
The autoclave with a stirrer and jacket is washed, dried, purged with nitrogen, charged with a cyclohexane solution (concentration 15% by weight) containing 85 parts by weight of pre-purified butadiene, and then n-butyllithium 1 using tetrahydrofuran After adding 1.5 moles to moles, the reactor internal temperature was maintained at 50 ° C. As a polymerization initiator, 0.1 part by weight of n-butyllithium was added with respect to 100 parts by weight of all monomers used. After the start of the reaction, the internal temperature of the reactor gradually increased due to heat generated by polymerization. After completion of the reaction, a cyclohexane solution containing 15 parts by weight of pre-purified styrene (concentration 15% by weight) was added to continue the polymerization, and the final reactor internal temperature reached about 70 ° C.
Next, an equimolar amount of 1,3-dimethyl-2-imidazolidinone (hereinafter referred to as modifier M1) as a modifier is added to the living polymer obtained in the above with respect to n-butyllithium used for polymerization. And reacted. Methanol was then added, and then 0.3 parts by weight of octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate as a stabilizer was added to 100 parts by weight of the polymer.
The resulting modified block copolymer (B-1) had a styrene content of 15% by weight, a block styrene content of 14% by weight, a vinyl bond content of 14%, and a weight average molecular weight of 1290,000.

[Production Example 2] Unmodified conjugated diene polymer; B-2
Polymerization was carried out in the same manner as in Production Example 1, but no modifier was added, methanol was added directly, and octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate was added as a stabilizer. An unmodified conjugated diene polymer (B-2) was obtained by adding 0.3 part by weight to 100 parts by weight of the polymer.

[Example 1]
With respect to 100 parts by weight of the polylactic acid resin A-1, 10 parts by weight of the modified diene polymer B-1 and 0.1 part by weight of perbutyl D (manufactured by NOF Corporation) as a free radical generator were dried. After blending, melt-kneading is performed at a cylinder temperature of 190 ° C. in a same-direction twin-screw extruder (Ikegai Iron Works Co., Ltd., PCM-30), the strand is cooled, cut, and pelletized resin composition Got. The obtained resin composition was injection-molded at a mold temperature of 30 ° C. and a cooling time of 30 seconds to obtain a test piece for evaluation.

[Example 2]
A test piece was obtained and evaluated in the same manner as in Example 1 except that the amount of the modified diene polymer was changed to 5 parts by weight.

[Example 3]
A test piece was obtained and evaluated in the same manner as in Example 1 except that the polylactic acid resin was changed to A-2.
The evaluation results of Examples 1 to 3 are shown in Table 1.

[Comparative Examples 1 and 2]
A test piece was obtained and evaluated in the same manner as in Examples 1 and 2 except that the free radical generator was removed.

[Comparative Example 3]
Except that the amount of the free radical generator was 6 parts by weight, melt-kneading was carried out in the same manner as in Example 1, but discharge unevenness and the like were caused, and the pellets could not be collected stably.

[Comparative Example 4]
A test piece was obtained and evaluated in the same manner as in Comparative Example 1 except that the unmodified conjugated diene polymer B-2 was used instead of the modified conjugated diene polymer.

[Comparative Example 5]
A test piece was obtained and evaluated in the same manner as in Example 1 except that the unmodified conjugated diene polymer B-2 was used instead of the modified conjugated diene polymer.

[Comparative Example 6]
A test piece was obtained and evaluated in the same manner as in Example 1 except that the amount of the modified conjugated diene polymer B-1 was 70 parts by weight. The evaluation results of Comparative Examples 1 to 6 are shown in Table 2.
Molded articles obtained from the resin composition of the present invention were all molded articles having good molded appearance and excellent impact resistance.

  The polylactic acid resin composition of the present invention can provide a molded article having a good molded appearance and excellent impact resistance. This composition is a film. As a sheet, an injection-molded body, a blow-molded body, and an extrusion-molded body, it can be used for automobile applications, electrical / electronic applications, packaging applications and the like.

Claims (6)

  An aliphatic polyester comprising 100 parts by weight of an aliphatic polyester resin (A), 1 to 60 parts by weight of a modified conjugated diene polymer (B) and 0.01 to 5 parts by weight of a free radical generator (C). Resin composition.   The aliphatic polyester resin composition according to claim 1, wherein the component (A) is a polylactic acid resin.   (B) Modified conjugated diene polymer in which component is modified with a compound having at least one polar group selected from an amino group, an imino group, a hydroxyl group, an epoxy group, a carboxyl group and an acid anhydride group The aliphatic polyester resin composition according to claim 1, wherein the composition is an aliphatic polyester resin composition.   (B) A modified conjugate in which the component is a compound having at least one polar group selected from an amino group, an imino group, a hydroxyl group, an epoxy group, a carboxyl group, and an acid anhydride group, and the terminal is modified The aliphatic polyester resin composition according to any one of claims 1 to 3, wherein the aliphatic polyester resin composition is a diene polymer.   The aliphatic polyester resin composition according to any one of claims 1 to 4, wherein the component (B) is a modified conjugated diene polymer having an amino group and / or an imino group.   The manufacturing method characterized by melt-mixing the aliphatic polyester resin composition in any one of Claims 1-3 using an extruder.