JP2003192883A - Polylactic acid-based resin composition, molded article and method for producing the molded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polylactic acid-based resin composition from which a molded article having excellent tensile strength, impact strength and heat resistance is obtained in good moldability and the heat resistant polylactic acid-based resin molded article from the composition and to provide a method for producing the molded article. <P>SOLUTION: This polylactic acid-based resin composition comprises 100 pts.wt. lactic acid-based polymer, 0.01-5.0 pts.wt. phosphate metal salt and 0.01-5.0 pts.wt. basic inorganic aluminum compound. This method for producing the molded article comprises melting the polylactic acid-based resin composition, filling the melted resin composition into a mold of a molding machine in which the molding temperature is set to a temperature not higher than a crystallization initiation temperature in DSC and not lower than the glass transition temperature and molding the resin composition while crystallizing the resin. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to excellent tensile strength,
The present invention relates to a polylactic acid-based resin composition in which a molded article having impact strength and heat resistance is obtained with good moldability, and a heat-resistant molded article obtained from the resin. Furthermore, the present invention relates to a method for producing a heat-resistant polylactic acid-based resin molded product.

[0002]

2. Description of the Related Art In recent years, from the viewpoint of protecting the natural environment, biodegradable polymers that decompose in the natural environment and molded articles thereof have been demanded, and researches on naturally degradable resins such as aliphatic polyesters have been actively conducted. . In particular, lactic acid-based polymers have a sufficiently high melting point of 140 to 180 ° C. and are excellent in transparency, and therefore, they are highly expected as packaging materials and molded articles that utilize transparency.

However, a container formed by injection molding of a lactic acid-based polymer has excellent rigidity, but has low heat resistance or low heat resistance and impact resistance. For example, hot water or a microwave oven is used for a packaging container. Can't
Limited use.

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

As a method for increasing the crystallization speed, for example,
In JP-A-60-86156, in order to promote crystallization of polyethylene terephthalate (PET), a wholly aromatic polyester fine powder containing terephthalic acid and resorcin as main constituent units as a crystal nucleating agent is added. Have been described. As described above, a method of adding a nucleating agent for promoting crystallization is known.

On the other hand, examples of adding such an additive to a biodegradable polymer include JP-A-5-70696 and JP-A-4-504731 (WO 90/0).
1521), US Pat. No. 5,180,765,
Japanese Patent Publication No. 6-504799 and Japanese Patent Laid-Open No. 4-22045.
No. 6 publication is mentioned.

Japanese Patent Laid-Open No. 5-70696 discloses a biodegradable material such as poly-3-hydroxybutyrate / poly-3-hydroxyvalerate copolymer, polycaprolactone or polylactic acid as a material for a plastic container. It is disclosed that 10 to 40% by weight of calcium carbonate and talc having an average particle diameter of 20 μm are mixed with plastic. However, this technique accelerates the decomposition of the biodegradable plastic after disposal by adding a large amount of an inorganic filler, and does not improve the heat resistance by crystallizing the polymer.

Japanese Laid-Open Patent Publication No. 4-504731 (WO 9
0/01521), it is described that the properties of hardness, strength and temperature resistance are changed by adding a filler of an inorganic compound such as silica or kaolinite to a lactide thermoplastic resin, Examples include L,
Calcium lactate 5 as a nucleating agent for DL-lactide copolymer
Blending the weight percentages on a heated roll at a temperature of 170 ° C. for 5 minutes states that the sheet is stiff, strong and cloudy with increased crystallinity.

Japanese Patent Publication No. 6-504799 discloses lactate and benzoate as nucleating agents. In the examples, 1% of calcium lactate is added to polylactide copolymer, and the mixture is treated for 2 minutes. Although injection molding was carried out in a mold maintained at a residence time of about 85 ° C, an example of further annealing at about 110 to 135 ° C in the mold due to insufficient crystallization is described.

In Japanese Unexamined Patent Publication (Kokai) No. 8-193165, talc, silica, and the like, which are commonly used as nucleating agents in lactic acid-based polymers,
Although injection molding was attempted using calcium lactate or the like, a molded product that can be used practically cannot be obtained because the crystallization rate is slow and the molded product is brittle. Therefore, even if such a lactic acid-based polymer is used for general injection molding, blow molding, and compression molding using ordinary talc, silica, etc., the crystallization rate is slow and the practical heat resistance of the obtained molded product is low. It is described that the application is limited because the impact resistance is not so strong as 100 ° C. or lower.

In Japanese Patent Application Laid-Open No. 4-220456, polyglycolic acid and its derivatives are added as a nucleating agent to poly L-lactide and the like to increase the crystallization rate, thereby shortening the injection molding cycle time, and It is described as having excellent mechanical properties. As an example of injection molding, the crystallization temperature without a nucleating agent is 22.6% with a cooling time of 60 seconds, and 45.5% with a nucleating agent added.
However, according to JP-A-8-193165, when the injection molding was actually attempted without adding a nucleating agent to the lactic acid-based polymer, the mold temperature as described in JP-A-4-220456 was It is described that molding could not be performed under the conditions of glass transition temperature or higher.

Japanese Unexamined Patent Publication No. 2001-226571 discloses that
It is described that a heat-shrinkable film was actually processed by using a sorbitol compound and a phosphoric acid ester metal salt as a nucleating agent in a lactic acid-based polymer to improve its heat-shrinkable property. However, as the nucleating agent, only one is used,
It is not a combination system.

[0013]

The object of the present invention is to solve the above-mentioned problems of the prior art, and to obtain a molded article having excellent tensile strength, impact strength and heat resistance with good moldability. To provide a composition. Another object of the present invention is to provide a molded article made of a polylactic acid-based resin composition having excellent heat resistance, tensile strength and impact strength. A further object of the present invention is to provide a method for producing a polylactic acid-based resin molded article which is excellent in heat resistance, tensile strength and impact strength from the polylactic acid-based resin composition.

[0014]

Means for Solving the Problems As a result of intensive investigations by the present inventors, an aromatic organic phosphoric acid ester metal salt and a basic inorganic aluminum compound were used as a crystal nucleating agent, and if necessary, a dibenzylidene sorbitol compound. It was found that the above object can be achieved by using at least one of a basic inorganic aluminum compound and an aliphatic carboxylic acid metal salt, and further by using talc as necessary, and the present invention is completed. Came to.

That is, the present invention is based on the lactic acid-based polymer 100.
In parts by weight, as a crystal nucleating agent, phosphoric acid ester metal salt 0.0
1 to 5.0 parts by weight and 0.01 to 5.0 parts by weight of a basic inorganic aluminum compound, and preferably has a crystallization peak temperature of 90 to 1 in a scanning differential calorimeter (DSC).
It is a polylactic acid-based resin composition having a temperature of 20 ° C. and a heat of crystallization of 20 J / g or more.

In the present invention, the phosphoric acid ester metal salt has the following general formula (1) or (2):

[Chemical 4] (In the formula (1), R ₁ represents a hydrogen atom or a carbon atom of 1
And R ₂ and R ₃ may be the same or different and each represents a hydrogen atom or a carbon atom of 1
~ 12 alkyl groups, M ₁ is an alkali metal atom,
Represents an alkaline earth metal atom, a zinc atom or an aluminum atom, p represents 1 or 2, q represents 0 when M ₁ is an alkali metal atom, an alkaline earth metal atom or a zinc atom, and M ₁ is aluminum When it is an atom, it represents 1 or 2. )

[Chemical 5] (In the formula (2), R ₄ , R ₅ and R ₆ may be the same or different and each represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, and M ₂ is an alkali metal atom or an alkaline earth atom. Represents a group metal atom, a zinc atom or an aluminum atom, p represents 1 or 2, q represents 0 when M ₂ is an alkali metal atom, an alkaline earth metal atom or a zinc atom, and M ₂ represents an aluminum atom. Where 1 or 2) is contained in the polylactic acid-based resin composition.

The present invention further comprises a crystal nucleating agent represented by the following general formula (3):

[Chemical 6] (In the formula (3), R ₇ and R ₈ may be the same or different and each represents a hydrogen atom or a carbon atom number of 1 to 4).
Represents an alkyl group. However, at least one of R ₇ and R ₈ represents an alkyl group having 1 to 4 carbon atoms. R ₉ and R _{10, which} may be the same or different, each represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. However,
At least one of R ₉ and R ₁₀ represents an alkyl group having 1 to 4 carbon atoms. The above polylactic acid-based resin composition contains at least one selected from the group consisting of a dibenzylidene sorbitol compound represented by the formula (4) and an aliphatic carboxylic acid metal salt.

The present invention is the above polylactic acid resin composition, which further contains hydrous magnesium silicate (talc) in addition to the crystal nucleating agent. The present invention is the above polylactic acid-based resin composition, wherein the hydrous magnesium silicate (talc) has an average particle size of 10 μm or less.

The present invention is a heat-resistant polylactic acid-based resin molded product obtained by molding any one of the above polylactic acid-based resin compositions.

The present invention relates to a molding machine in which any one of the above polylactic acid-based resin compositions is melted and the temperature is set to a temperature not lower than the crystallization start temperature and not lower than the glass transition temperature in a scanning differential calorimeter (DSC). It is a method for producing a heat-resistant polylactic acid-based resin molded product, which is characterized in that it is filled in a mold and molded while being crystallized.

The present invention provides the heat-resistant polylactic acid-based resin molded article as described above, wherein the mold temperature is set in a range from a crystallization start temperature to a crystallization end temperature or higher in a scanning differential calorimeter (DSC). Is a manufacturing method.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the lactic acid-based polymer includes a polylactic acid homopolymer and a polylactic acid copolymer. Further, it may be a blend polymer mainly composed of polylactic acid homopolymer and / or polylactic acid copolymer.

The weight average molecular weight of the lactic acid type polymer is generally 50,000 to 500,000, preferably 100,000 to 250,000. If the weight average molecular weight is less than 50,000, the physical properties required for practical use cannot be obtained, while if the weight average molecular weight exceeds 500,000, the moldability tends to deteriorate.

The molar ratio L / D of L-lactic acid unit and D-lactic acid unit in the lactic acid-based polymer is 100/0.
Although it may be any of 0 to 100, 7 units of either L-lactic acid or D-lactic acid is used to obtain a high melting point.
In order to obtain a melting point higher than 5 mol% or higher, it is preferable to contain 90 mol% or more of either L-lactic acid or D-lactic acid unit.

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

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

Examples of polyhydric alcohols are aromatic polyhydric alcohols such as those obtained by addition-reacting ethylene oxide on bisphenol, ethylene glycol, propylene glycol, butanediol, hexanediol, octanediol, glycerin, sorbitan, trimethylol. Examples thereof include aliphatic polyhydric alcohols such as propane and neopentyl glycol, and ether glycols such as diethylene glycol, triethylene glycol, polyethylene glycol and polypropylene glycol.

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

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

The lactic acid type polymer is synthesized by a conventionally known method. That is, direct dehydration condensation from a lactic acid monomer as described in JP-A-7-33861, JP-A-59-96123, Proc. It can be synthesized by ring-opening polymerization of a monomeric lactide.

When direct dehydration condensation is carried out, L-lactic acid, D-
Any lactic acid, DL-lactic acid, or a mixture of these may be used. Also, when ring-opening polymerization is performed, L-lactide, D-lactide, DL-lactide, m
Any lactide of eso-lactide or mixtures thereof may be used.

The lactide synthesis, purification and polymerization procedures are described, for example, in US Pat. No. 4,057,537, published European patent application No. 261572, Polymer Bulletin, 14, 49.
1-495 (1985), and Makromol Chem., 187, 1611-1628.
(1986) and others.

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

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

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

The blend polymer is a mixture obtained by mixing and melting a polylactic acid homopolymer and / or a lactic acid copolymer and an aliphatic polyester other than polylactic acid, which is molded by blending an aliphatic polyester other than polylactic acid. Flexibility and impact resistance can be imparted to the product.
The weight ratio of the blend is usually about 10 to 100 parts by weight of the aliphatic polyester other than polylactic acid with respect to 100 parts by weight of the polylactic acid homopolymer and / or lactic acid copolymer.

In the present invention, the aliphatic polyester other than polylactic acid (hereinafter, simply referred to as “aliphatic polyester”) may be a polymer of one kind or a composite of two or more kinds of polymers. A polymer composed of an acid component and an aliphatic alcohol component, ε
Examples thereof include aliphatic hydroxycarboxylic acid polymers obtained by ring-opening polymerization of cyclic anhydrides such as caprolactone. In order to obtain these, there are a method of directly polymerizing to obtain a high molecular weight material and an indirect method of polymerizing to a degree of an oligomer and then obtaining a high molecular weight material with a chain extender or the like. The aliphatic polyester may be a copolymer as long as it is a polymer mainly containing the above-mentioned aliphatic monomer component,
Alternatively, it may be a mixture with another resin.

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

Further, for the purpose of providing a branch in the polymer for the purpose of improving the melt viscosity, a polyfunctional carboxylic acid, alcohol or hydroxycarboxylic acid having a functionality of 3 or more may be used as a component of the aliphatic polyester. When these components are used in a large amount, the polymer obtained may have a crosslinked structure and become non-thermoplastic, or even if it is thermoplastic, it may partially form a microgel having a highly crosslinked structure. Therefore, these tri- or higher-functional components are contained in the polymer in a very small proportion, and are contained to such an extent that they do not greatly affect the chemical and physical properties of the polymer. As the polyfunctional component, malic acid, tartaric acid, citric acid, trimellitic acid, pyromellitic acid, pentaerythritol, trimethylolpropane or the like can be used.

Among the methods for producing an aliphatic polyester, the direct polymerization method is a method for obtaining a high molecular weight product by removing the water contained in the compound or generated during the polymerization by selecting the above compound. Further, the indirect polymerization method, after the above compound is selected and polymerized to an oligomer degree, a small amount of a chain extender, for example, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, diisocyanate compound such as diphenylmethane diisocyanate, for the purpose of increasing the molecular weight. Is a method for increasing the molecular weight. Alternatively, there is a method of obtaining an aliphatic polyester carbonate by using a carbonate compound.

The polylactic acid-based resin composition of the present invention contains 0.01 to 5.0 parts by weight of each of a phosphoric acid ester metal salt and a basic inorganic aluminum compound in 100 parts by weight of a lactic acid-based polymer.

In the present invention, the crystal nucleating agent is not particularly limited in kind, but it is preferable that it contains at least one kind of the aromatic organic phosphoric acid ester metal salt represented by the general formula (1) or (2).

In equation (1), R₁Is hydrogen atom or charcoal
It represents an alkyl group having 1 to 4 elementary atoms. R₁Charcoal
Examples of the alkyl group having 1 to 4 elementary atoms include methyl and ethyl.
Ru, propyl, isopropyl, butyl, sec-butyl, a
Sobutyl and the like can be mentioned. R ₂And R₃Are the same or
They may be different, respectively, the number of hydrogen atoms or carbon atoms
It represents an alkyl group of 1 to 12. R₂And R₃Indicated by
Examples of the alkyl group having 1 to 12 carbon atoms include methyl and ether.
Chill, propyl, isopropyl, butyl, sec-butyl,
Tert-butyl, amyl, tert-amyl, hexyl, hepti
Le, octyl, isooctyl, third octyl, 2-ethyl
Luhexyl, nonyl, isononyl, decyl, isodecyl
Le, undecyl, dodecyl, third dodecyl, etc.
Be done. M₁Is an alkali metal atom such as Li, Na or K,
Alkaline earth metal atoms such as Mg and Ca, zinc atoms or
Represents a luminium atom. p represents 1 or 2, q is M₁
Is an alkali metal atom, alkaline earth metal atom or zinc source
Represents 0 when a child, M₁When is an aluminum atom
Represents 1 or 2.

Among the phosphoric acid ester metal salts represented by the formula (1), preferable ones are, for example, R ₁ : H, R
Examples thereof include those having a ₂ : t-butyl group and an R ₃ : t-butyl group.

In equation (2), R_Four, R_FiveAnd R
₆May be the same or different and each is a hydrogen atom.
Alternatively, it represents an alkyl group having 1 to 12 carbon atoms. R_Four, R
_FiveAnd R ₆An alkyl group having 1 to 12 carbon atoms represented by
As R in the formula (1)₂And R₃I mentioned in
A similar alkyl group is exemplified. M₂Is Li, Na,
Alkali metal atom such as K, alkaline earth such as Mg and Ca
Represents a metal atom, a zinc atom or an aluminum atom. p is
1 or 2 and q is M₂Is an alkali metal atom,
When it is a rare earth metal atom or a zinc atom, it represents 0, and M₂But
When it is an aluminum atom, it represents 1 or 2.

Among the phosphoric acid ester metal salts represented by the formula (2), preferred ones include, for example, R ₄ : methyl group, R ₅ : t-butyl group, R ₆ : methyl group. .

Commercially available phosphoric acid ester metal salts include, for example, ADEKA STAB NA-10, NA-11, NA-21, NA-30 manufactured by Asahi Denka Kogyo Co., Ltd.
There are NA-35 and the like, and the type and grade can be arbitrarily selected according to the purpose of use.

The method for synthesizing the metal salt of an aromatic organic phosphoric acid ester is not particularly limited and may be one synthesized by any known method.

The polylactic acid-based resin composition of the present invention further comprises, as a crystal nucleating agent, in addition to the aromatic organic phosphoric acid ester metal salt and the basic inorganic aluminum compound, a dicarboxylic acid represented by the general formula (3). It is also preferable to contain at least one selected from a benzylidene sorbitol compound and an aliphatic carboxylic acid metal salt.

In the formula (3) representing the dibenzylidene sorbitol compound, R ₇ and R ₈ may be the same or different and each represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. However, at least one of R ₇ and R ₈ represents an alkyl group having 1 to 4 carbon atoms. Examples of the alkyl group having 1 to 4 carbon atoms represented by R ₇ and R ₈ include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl and sec-butyl, and the methyl group is preferable. R ₉ and R ₁₀ may be the same or different and each is a hydrogen atom or a carbon atom of 1
Represents an alkyl group of 4; However, at least one of R ₉ and R ₁₀ represents an alkyl group having 1 to 4 carbon atoms. R
Examples of the alkyl group having 1 to 4 carbon atoms represented by ₉ and R ₁₀ include the same alkyl groups as those described for R ₇ and R ₈ , and a methyl group is preferable. As the dibenzylidene sorbitol compound, R ₇ : methyl group, R ₈ : H, R
_{A 9} : methyl group and a R ₁₀ : H group are preferred.

The basic inorganic aluminum compound used in the present invention is an inorganic aluminum compound capable of adsorbing an acidic substance, and examples thereof include aluminum oxide, aluminum hydroxide, aluminum carbonate, and hydrotalcite represented by the following formula. And the like, and can be used regardless of the particle size and the presence or absence of crystal water.

Li _a Zn _b Mg _c Al _d (OH) _{a + 2b + 2c + 3d-2} CO ₃ .nH ₂ O (4) (in the formula, a is 0 to 5.0 and b is 0 to 3. 0, c is 0.1
-6.0, d shows 1.0-8.0, n shows 0-30. )

Hydrotalcite formation used in the present invention
The compound may be a natural product or a synthetic product.
You may. As a synthesizing method, Japanese Patent Publication No. 46-2280
Japanese Patent, Japanese Patent Publication No. 50-30039, Japanese Patent Publication No. 51-
29129, JP-A-61-174270,
Known methods described in JP-A-6-248109
Can be illustrated. Further, in the present invention,
Use regardless of the crystal structure, crystal particle size, etc.
It is possible to As a hydrotalcite compound
In particular, the compound represented by the general formula (4) is preferable,
A compound containing lithium is particularly preferable. Specifically
Is Li_1.8Mg_0.6Al_Four(OH)₁₈CO₃・ 3.6
H₂0, Li₂Al_Four(OH)₁₄CO₃・ 4H₂O, L
i_1.6Mg _1.2Al_Four(OH)₁₄CO₃, Li_2.4Mg
_0.3Al_Four(OH)₁₃CO₃・ 4.6H₂O, Li_3.2
Mg_2.4Al₂(OH)₁₂CO₃・ 3.3H₂O, Li
_2.4Mg_0.8Al₆(OH)₂₀CO₃・ 5.2H₂O
Which can be mentioned. Also, as a commercial product, Fuji Chemical Stock Association
The LMA made by the company is mentioned.

On the surface of the hydrotalcite compound, higher fatty acid such as stearic acid, higher fatty acid metal salt such as alkali metal oleate, organic sulfonic acid metal salt such as alkali metal dodecylbenzene sulfonate, higher fatty acid amide Those coated with a higher fatty acid ester or wax can also be used.

Examples of the aliphatic carboxylic acid constituting the aliphatic carboxylic acid metal salt used in the present invention include octylic acid, neooctylic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid,
Examples thereof include aliphatic carboxylic acids having 8 to 30 carbon atoms such as ricinoleic acid, behenic acid and triacontanoic acid.
Further, as the metal constituting the aliphatic carboxylic acid metal salt,
For example, alkali metals such as lithium, sodium and potassium; alkaline earth metals such as magnesium, calcium and barium; and other metals include aluminum, lead and zinc. These may be basic or neutral salts, preferably neutral salts.

The amount of the above-mentioned aromatic organic phosphoric acid ester metal salt and basic inorganic aluminum compound used as the crystal nucleating agent in the present invention is such that the lactic acid-based polymer 100 is added.
0.01 to 5.0 parts by weight with respect to parts by weight,
It is preferably 0.1 to 3 parts by weight. The amount of crystal nucleating agent is 0.
If the amount is less than 01 parts by weight, the effect of the addition may be insufficient, while if the amount exceeds 5.0 parts by weight, the physical properties of the molded product made from the polylactic acid resin deteriorate, which is not preferable. In the case where, as a crystal nucleating agent, in addition to the aromatic organic phosphate metal salt and the basic inorganic aluminum compound, at least one selected from the dibenzylidene sorbitol compound and the aliphatic carboxylic acid metal salt is used as an additional component. The use ratio of these is not particularly limited and is arbitrary. For example, in the total amount of the crystal nucleating agent, the aromatic organic phosphoric acid ester metal salt is added in an amount of 20 to 80.
It is advisable to use about the weight% and make the balance the additional component. The addition amount and the use ratio of the crystal nucleating agent are appropriately selected according to the type of lactic acid-based polymer and the target molded article.

The polylactic acid resin composition of the present invention is not particularly limited in kind, but hydrous magnesium silicate (talc) is more preferable.

The average particle size of hydrous magnesium silicate (talc) is preferably 10 μm or less, and 1 to 5 μm.
Is more preferable. Use of talc having an average particle size of more than 10 μm is also effective, but if it is 10 μm or less, the effect of promoting the formation of crystal nuclei is higher and the heat resistance of the molded product can be further improved.

The content of hydrous magnesium silicate (talc) is preferably 0.01 to 5.0 parts by weight,
More preferably, it is 0.01 to 3.0 parts by weight.
If the blending amount is less than 0.01 part by weight, the effect of addition is not obtained so much, and if the blending amount is 5.0 parts by weight or more, cloudiness may occur in the resin composition.

In the present invention, the method of adding each additive component of the crystal nucleating agent to the lactic acid-based polymer is not particularly limited, and a conventionally known method can be used. For example, lactic acid-based polymer powder or pellets and each additive component may be mixed by dry blending, or a part of the additive component may be preblended and the other component may be dry blended later. For example, a mill roll, a Banbury mixer, a super mixer or the like may be used for mixing, and a single-screw or twin-screw extruder may be used for kneading. This mixing and kneading is usually performed at a temperature of about 120 to 220 ° C. Further, an additive component may be added at the stage of polymerizing the lactic acid-based polymer. Further, a method of producing a masterbatch containing each component of the additive at a high concentration and adding the masterbatch to the lactic acid-based polymer can be used.

Further, in the polylactic acid resin composition of the present invention, if necessary, conventionally known plasticizers, antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, pigments, colorants and various fillers are included. , Antistatic agent, release agent, fragrance, lubricant,
Various additives such as flame retardants, foaming agents, fillers, antibacterial / antifungal agents, and other nucleating agents may be blended.

The polylactic acid resin composition of the present invention has a crystallization peak temperature of 90 in a scanning differential calorimeter (DSC).
To 120 ° C, preferably 95 to 115 ° C, and the heat of crystallization is 20 J / g or more, preferably 21 J / g or more. The upper limit of the heat of crystallization is not specified, but 6
It is about 0 J / g. If this crystallization peak temperature is less than 90 ° C., the cooling time during the molding process becomes long, while
When the crystallization peak temperature exceeds 120 ° C., the mold temperature is high and the cooling time is long, which results in a long molding cycle. Further, when the heat of crystallization is less than 20 J / g,
The moldability at the crystallizable temperature is poor, and the heat resistance of the resulting molded product is poor, and the tensile strength and impact strength are also poor.

The present invention also relates to a heat resistant molded article obtained from the above polylactic acid resin composition and a method for producing the same.

To crystallize the polylactic acid resin composition,
Although there is a method of annealing the molded product at a temperature at which it can be crystallized, there is a drawback that the molded product is easily deformed during the crystallization process of annealing. Therefore, when molding the polylactic acid-based resin composition composition, a method is conceivable in which the molding die is set to a temperature at which it can be crystallized and held for a certain period of time.

In the present invention, the polylactic acid-based resin composition is melted and crystallizable, that is, the temperature range not higher than the crystallization start temperature in a scanning differential calorimeter (DSC) and not lower than the glass transition temperature, preferably crystallization. Molding is performed while crystallizing by filling in a mold of a molding machine set in a temperature range of not higher than the starting temperature and not lower than the crystallization end temperature and holding the mold for a certain period of time. Since the polylactic acid-based resin composition of the present invention is configured to include the crystal nucleating agent as described above, crystallization is completed in the mold, and the polylactic acid-based resin composition excellent in heat resistance and impact resistance is obtained. A resin molded product is obtained.

Since the setting of the mold temperature depends on the type of the polylactic acid resin composition to be molded, the crystallization temperature (the crystallization peak temperature, the crystallization start temperature, the crystallization end temperature) is measured in advance by the DSC method. The temperature range is below the crystallization start temperature and above the glass transition temperature, preferably below the crystallization start temperature and above the crystallization end temperature. Within this temperature range, it is possible to easily crystallize and obtain a molded product with good dimensional accuracy. If it goes out of this range,
Crystallization becomes slow and solidification time at the time of molding becomes long, which is not suitable for practical use.

When molding the polylactic acid-based resin composition of the present invention, injection molding, blow molding, vacuum molding, compression molding and the like similar to general plastics can be carried out, such as rods, bottles and containers. Various molded articles can be easily obtained.

In the present invention and the following examples, the weight average molecular weight (Mw) of the lactic acid-based polymer is the polystyrene conversion value by GPC analysis, and the crystallization temperature and the crystallization calorie are the scanning differential calorimeters (manufactured by Shimadzu Corporation, DSC- 60)
A sample amount of 10 mg of pellet was heated from room temperature to 200 ° C. at 50 ° C./min and held for 5 minutes.
It was measured at a temperature decrease rate of ° C / min. The tensile test is J
The IS K 7113 (No. 1 test piece) and the Izod impact test conformed to JIS K 7110 (No. 2 test piece with notch), respectively.

In the present invention, the index of heat resistance is JIS
The high load deflection temperature of the K 7207A method was used. The high load deflection temperature is 1.8 MPa for a test piece in a heating bath.
The temperature of the heat transfer medium at the time when the temperature of the heat transfer medium is raised at a constant speed while the bending stress is applied and the test piece reaches the specified deflection amount. The high load deflection temperature of the heat-resistant polylactic acid-based resin molded article of the present invention varies depending on the amount of the crystal nucleating agent added,
For example, even in parts of household electric appliances that are not exposed to relatively high temperatures, it is practically 80 ° C or higher, preferably 90 ° C or higher, and more preferably 100 ° C or higher. The upper limit is not set, but it is about 140 ° C.

[0070]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

[Example 1] The compounding ingredients shown in Table 1 were dry blended, melt-mixed in a twin-screw kneading extruder at 200 ° C for an average of 4 minutes, extruded in a strand form from a die and cooled with water,
It was cut to obtain pellets of a lactic acid-based polymer composition containing a crystal nucleating agent. As a result of measuring DSC of the obtained pellets,
Crystallization peak temperature is 105 ° C, crystallization start temperature is 116
℃, crystallization end temperature is 95 ℃, heat of crystallization is 35 J / g
Met.

The pellets obtained are vacuum dried at 80 ° C.,
After making it dry, mold temperature is 100 ℃, cooling time is 4
A test piece for JIS physical property evaluation was obtained by injection molding for 5 seconds. Table 2 shows the evaluation results of these test pieces.

Example 2 Pellets of a lactic acid-based polymer composition were obtained in the same manner as in Example 1 except that the compounding ingredients shown in Table 1 were used. As a result of measuring DSC of the obtained pellets, the crystallization peak temperature was 114 ° C., the crystallization start temperature was 125 ° C., the crystallization end temperature was 104 ° C., and the crystallization heat was 3
It was 3 J / g. From the obtained pellets, JIS test pieces for physical property evaluation were obtained by injection molding in the same manner as in Example 1. Table 2 shows the evaluation results of these test pieces.

Example 3 Pellets of a lactic acid-based polymer composition were obtained in the same manner as in Example 1 except that the compounding ingredients shown in Table 1 were used. As a result of measuring DSC of the obtained pellets, the crystallization peak temperature was 99 ° C. and the crystallization start temperature was 1
04 ℃, crystallization end temperature is 83 ℃, heat of crystallization is 28J
/ G. From the obtained pellets, JIS test pieces for physical property evaluation were obtained by injection molding in the same manner as in Example 1.
Table 2 shows the evaluation results of these test pieces.

Example 4 Pellets of a lactic acid-based polymer composition were obtained in the same manner as in Example 1 except that the compounding ingredients shown in Table 1 were used. As a result of measuring DSC of the obtained pellets, the crystallization peak temperature was 112 ° C, the crystallization start temperature was 122 ° C, the crystallization end temperature was 101 ° C, and the crystallization heat amount was 4 ° C.
It was 2 J / g. From the obtained pellets, JIS test pieces for physical property evaluation were obtained by injection molding in the same manner as in Example 1. Table 2 shows the evaluation results of these test pieces.

Example 5 Pellets of a lactic acid-based polymer composition were obtained in the same manner as in Example 1 except that the compounding ingredients shown in Table 1 were used. As a result of measuring DSC of the obtained pellets, the crystallization peak temperature was 100 ° C., the crystallization start temperature was 105 ° C., the crystallization end temperature was 96 ° C., and the crystallization heat amount was 25.
It was J / g. From the obtained pellets, JIS test pieces for physical property evaluation were obtained by injection molding in the same manner as in Example 1. Table 2 shows the evaluation results of these test pieces.

[Comparative Example 1] As shown in Table 1, polylactic acid as a component was melt-mixed in a twin-screw kneading extruder at 200 ° C for an average of 4 minutes, extruded in a strand form from a die and cooled with water.
It was cut to obtain pellets of polylactic acid. As a result of measuring DSC of the obtained pellets, the crystallization peak temperature was 99 ° C,
The crystallization start temperature is 112 ° C, the crystallization end temperature is 85 ° C,
The heat of crystallization was 15 J / g.

The pellets obtained are vacuum dried at 80 ° C.,
After making it dry, mold temperature is 100 ℃, cooling time is 4
Injection molding was carried out under the condition of keeping it for 5 seconds, but the mold could not be removed. The pellets thus obtained are vacuum dried at 80 ° C. to be in an absolutely dry state, and then the mold temperature is 40 ° C. and the cooling time is 45 s.
A test piece for JIS physical property evaluation was obtained by injection molding while maintaining ec. Table 2 shows the evaluation results of these test pieces.

Comparative Example 2 Pellets of a lactic acid-based polymer composition were obtained in the same manner as in Example 1 except that the compounding ingredients shown in Table 1 were used. As a result of measuring DSC of the obtained pellets, the crystallization peak temperature was 101 ° C., the crystallization start temperature was 115 ° C., the crystallization end temperature was 90 ° C., and the heat of crystallization was 16 ° C.
It was J / g.

The pellets obtained are vacuum dried at 80 ° C.,
After making it dry, mold temperature is 100 ℃, cooling time is 4
Injection molding was carried out under the condition of keeping it for 5 seconds, but the mold could not be removed. The pellets thus obtained are vacuum dried at 80 ° C. to be in an absolutely dry state, and then the mold temperature is 40 ° C. and the cooling time is 45 s.
A test piece for JIS physical property evaluation was obtained by injection molding while maintaining ec. Table 2 shows the evaluation results of these test pieces.

[0081]

[Table 1]

[0082]

[Table 2]

From Tables 1 and 2, injection-molded articles were obtained using the lactic acid-based polymer compositions according to the present invention in Examples 1 to 5, so that all of the molded articles had heat resistance, tensile strength and tensile elasticity. Rate and Izod impact strength were excellent. In Examples 2 and 4, since talc was added to the lactic acid-based polymer composition in addition to the crystal nucleating agent, higher heat resistance was obtained. On the other hand, in Comparative Example 1, the crystal nucleating agent was not blended, the moldability was poor, and the heat resistance and strength of the molded product were poor. In Comparative Example 2, the crystal nucleating agent was blended, but the amount of heat of crystallization was small, so the moldability was poor, and the heat resistance and strength of the molded product were poor.

[0084]

According to the present invention, by blending a crystal nucleating agent with a lactic acid-based polymer, the crystallization rate of the lactic acid-based polymer can be increased without lowering the tensile strength and impact strength. Further, by subjecting this lactic acid-based polymer composition to a crystallization treatment in a mold, a molded article having excellent heat resistance can be obtained.

According to the present invention, there is provided a polylactic acid resin composition capable of obtaining a molded article having excellent tensile strength, impact strength and heat resistance with good moldability. Provided is a simple and highly efficient production method of a lactic acid-based resin molded product and a heat-resistant polylactic acid-based resin molded product.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08K 3/34 C08K 3/34 5/1575 5/1575 5/521 5/521 // B29K 67:00 B29K 67:00 (72) Inventor Etsuo Tobita 5-2-13 Shirahata, Saitama City, Saitama Asahi Denka Kogyo Co., Ltd. (72) Toshinori Kono 5-2-13 Shirahata, Saitama City, Saitama Asahi Denka Kogyo Co., Ltd. (72) Inventor Yuji Urayama 1 Nishinokyo Kuwabara-cho, Nakagyo-ku, Kyoto, Kyoto Prefecture Shimadzu Corporation Co., Ltd. (72) Inventor Kenji Kanamori 1 Nishinokyo Kuwabara-cho, Nakakyo-ku, Kyoto Prefecture Kyoto (72) Inventor, Shimadzu (72) Kuji Okuyama 1st term, Kuwabara-cho, Nishinokyo, Nakagyo-ku, Kyoto, Kyoto Prefecture F-term in Shimadzu Corporation (reference) 4F071 AA43 AB18 AB21 AB26 AB30 AC15 AF13 AF15 AF22 AF45 AH0 4 AH05 BB03 BB05 BB06 BC04 4F202 AA24A AA24D AB08 AB16 AB22 AR06 CA11 CB01 CN01 4F206 AA24A AA24D AB08 AB16 AB22 AR06 JA07 JF01 JF02 JN43 4J002 CF181 DE147 DE247 DJ047 EW046 GG01 GG02

Claims (12)

[Claims] 1. A polylactic acid resin composition containing 0.01 to 5.0 parts by weight of a phosphoric acid ester metal salt and 0.01 to 5.0 parts by weight of a basic inorganic aluminum compound in 100 parts by weight of a lactic acid polymer. . 2. A lactic acid-based polymer of 100 parts by weight contains 0.01 to 5.0 parts by weight of a crystal nucleating agent, and has a crystallization peak temperature of 90 to 120 ° C. in a scanning differential calorimeter (DSC).
And a polylactic acid resin composition having a heat of crystallization of 20 J / g or more. 3. A phosphoric acid ester metal salt is represented by the following general formula (1) or (2): (In the formula (1), R ₁ represents a hydrogen atom or a carbon atom of 1
And R ₂ and R ₃ may be the same or different and each represents a hydrogen atom or a carbon atom of 1
~ 12 alkyl groups, M ₁ is an alkali metal atom,
Represents an alkaline earth metal atom, a zinc atom or an aluminum atom, p represents 1 or 2, q represents 0 when M ₁ is an alkali metal atom, an alkaline earth metal atom or a zinc atom, and M ₁ is aluminum When it is an atom, it represents 1 or 2. ) [Chemical 2] (In the formula (2), R ₄ , R ₅ and R ₆ may be the same or different and each represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, and M ₂ is an alkali metal atom or an alkaline earth atom. Represents a group metal atom, a zinc atom or an aluminum atom, p represents 1 or 2, q represents 0 when M ₂ is an alkali metal atom, an alkaline earth metal atom or a zinc atom, and M ₂ represents an aluminum atom. When 1 or 2, the polylactic acid-based resin composition according to claim 1 or 2, containing at least one kind of an aromatic organic phosphoric acid ester metal salt. 4. The crystal nucleating agent is further represented by the following general formula (3): (In the formula (3), R ₇ and R ₈ may be the same or different and each represents a hydrogen atom or a carbon atom number of 1 to 4).
Represents an alkyl group. However, at least one of R ₇ and R ₈ represents an alkyl group having 1 to 4 carbon atoms. R ₉ and R _{10, which} may be the same or different, each represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. However,
At least one of R ₉ and R ₁₀ represents an alkyl group having 1 to 4 carbon atoms. The polylactic acid-based resin composition according to claim 3, comprising at least one selected from the group consisting of a dibenzylidene sorbitol compound represented by the formula (4) and an aliphatic carboxylic acid metal salt. 5. The polylactic acid-based resin composition according to claim 4, wherein the basic inorganic aluminum compound is at least one selected from aluminum hydroxide, aluminum oxide, aluminum carbonate and hydrotalcite compounds. 6. The hydrotalcite compound has the following general formula (4): Li _a Zn _b Mg _c Al _d (OH) _{a + 2b + 2c + 3d-2} CO ₃ .nH ₂ O (4) (wherein , A is 0 to 5.0, b is 0 to 3.0, and c is 0.1.
-6.0, d shows 1.0-8.0, n shows 0-30. The polylactic acid-type resin composition of any one of Claims 1-5 which is a compound represented by these. 7. The polylactic acid-based resin composition according to claim 6, wherein the hydrotalcite compound is a lithium-containing hydrotalcite compound in which a in the general formula (4) is 0.1 to 5. 8. Further hydrous magnesium silicate (talc)
The polylactic acid-based resin composition according to any one of claims 1 to 7, which comprises: 9. The polylactic acid resin composition according to claim 8, wherein the hydrous magnesium silicate (talc) has an average particle size of 10 μm or less. 10. A heat-resistant polylactic acid-based resin molded article obtained by molding the polylactic acid-based resin composition according to any one of claims 1 to 9. 11. A range in which the polylactic acid-based resin composition according to any one of claims 1 to 9 is melted and the temperature is not higher than the crystallization start temperature in a scanning differential calorimeter (DSC) and not lower than the glass transition temperature. Fill the mold of the molding machine whose temperature is set to
A method for producing a heat-resistant polylactic acid-based resin molded product, which comprises molding while crystallizing. 12. A scanning differential calorimeter (DS)
The method for producing a heat-resistant polylactic acid-based resin molded article according to claim 10, wherein the temperature is set in the range from the crystallization start temperature in C) to the crystallization end temperature or higher.