JP2012149122A - Method for producing molding of polylactic acid resin composition and molding obtained by the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a molding of a polylactic acid resin composition of which shrinkage by heating is significantly suppressed and also heat resistance, a weak point of a polylactic acid resin, is significantly improved.SOLUTION: The method for producing the molding of the polylactic acid resin composition is provided, which includes (1) a step of obtaining a composition including a polylactic acid resin and a liquid crystal polymer by blending 7-50 pts.wt. of the liquid crystal polymer relative to 100 pts.wt. of the polylactic acid resin with the polylactic acid resin and performing melt kneading at a temperature of 170-250°C, (2) a step of obtaining a molding by performing melt processing of the composition obtained in the step (1), and (3) a step of performing heat processing of the molding obtained in the step (2) at a temperature of 102-140°C for 5-55 minutes.

Description

  The present invention relates to a method for producing a molded product of a polylactic acid resin composition obtained by melt-processing a polylactic acid resin composition containing a polylactic acid resin and a liquid crystal polymer. Specifically, the present invention relates to a method for producing a polylactic acid resin composition molded article in which shrinkage due to heating is remarkably suppressed and heat resistance is improved.

  Most of the conventional polymers are made from petroleum resources. However, there is a risk that the petroleum resources will be depleted in the future, and the large amount of oil resources consumed makes it possible to store carbon dioxide that has been stored underground since the geological era. There are concerns that it will be released into the atmosphere and global warming will become more serious. From such a viewpoint of protecting the global environment, biodegradable polymers that are decomposed in a natural environment are attracting attention, and application to various environmentally-friendly products is being studied.

  Among them, recently, a polymer made of biomass has attracted attention from the viewpoint of preventing global warming. Polymers made of biomass are originally made from biomass assimilated by carbon dioxide by photosynthesis, so that the production is not only compatible with the natural material circulation cycle, but is also incinerated after use. Does not increase the concentration of carbon dioxide in the atmosphere.

  As such a polymer comprising biomass, polyhydroxybutyrate, polybutylene succinate, polylactic acid, and the like are known. Among these, polylactic acid can be produced not only as a biodegradable polymer but also in its toughness and high transparency because lactic acid or lactide as raw materials can be produced from natural plants relatively efficiently. It is widely used as a versatile polymer.

  However, the melting point of polylactic acid is about 170 ° C., and it cannot be said that it is sufficient for use as a general-purpose polymer, and improvements in mechanical properties and heat resistance are required.

  For this reason, studies have been made to blend the polylactic acid and a general-purpose resin material to make up for the above drawbacks. Patent Document 1 discloses a polymer alloy of polyester and polylactic acid derived from petroleum resources, but the amount of polylactic acid is small and it cannot be said that it is sufficient from the viewpoint of low environmental load. Patent Documents 2 to 4 disclose a resin composition in which polybutylene terephthalate or polyamide is dispersed in polylactic acid to improve mechanical properties and heat resistance, but the mechanical properties and heat resistance are not sufficient. .

  Further, Patent Document 5 discloses a thermoplastic resin composition having a phase structure in which polylactic acid and a crystalline aromatic polyester are blended so that the aromatic polyester is a continuous phase and the polylactic acid is a dispersed phase. However, in order to form such a special phase structure, in the blend of polylactic acid and aromatic polyester, it is necessary to adjust the viscosity ratio of the two to a specific range, or when performing melt-kneading. The manufacturing process becomes complicated, for example, a screw having a different configuration is required, and the polylactic acid content and heat resistance are not sufficiently satisfactory.

  In order to improve the disadvantages of such polylactic acid, the present applicant has previously proposed a polylactic acid resin composition having improved heat resistance by blending a liquid crystal polymer with polylactic acid (Patent Document 6). . By blending the liquid crystal polymer, the heat resistance of the polylactic acid resin composition was improved to a practical level, but there was room for further improvement in order to use it for various molded product applications.

Japanese Patent Laying-Open No. 2005-2000593 JP-A-2005-42045 JP 2003-238775 A JP 2004-51835 A JP 2007-224290 A JP 2010-180373 A

  An object of the present invention is to provide a method for producing a molded product of a polylactic acid resin composition in which shrinkage due to heating is remarkably suppressed and the heat resistance, which was a drawback of the polylactic acid resin, is greatly improved. .

  As a result of intensive investigations on improving the performance of the polylactic acid resin, the present inventors have obtained a molded product by melt-processing a composition obtained by blending a predetermined amount of a liquid crystal polymer into the polylactic acid resin, and then further satisfying predetermined conditions. As a result of the heat treatment, the present inventors have found that the shrinkage due to heating of the molded product obtained is remarkably suppressed and the heat resistance is remarkably improved, and the present invention has been completed.

That is, the present invention
1) A composition comprising a polylactic acid resin and 7 to 50 parts by weight of a liquid crystal polymer with respect to 100 parts by weight of the polylactic acid resin and melt-kneaded at a temperature of 170 to 250 ° C. Obtaining a product,
2) A step of melt-processing the composition obtained in step 1) to obtain a molded product, and
3) A step of heat-treating the molded product obtained in step 2) at a temperature of 102 to 140 ° C. for 5 to 55 minutes,
A method for producing a molded product of a polylactic acid resin composition containing

  The present invention also provides a polylactic acid resin composition molded article obtained by the above production method.

  The method for producing a polylactic acid resin composition molded product of the present invention can produce a molded product suitable for a practical level by a simple process. In addition, the polylactic acid resin composition molded article obtained by the production method of the present invention is remarkably suppressed from being shrunk by heating and has greatly improved the heat resistance that was a drawback of the polylactic acid resin. It can be used for molding applications, particularly for molded products that require dimensional stability under heating.

  In the present invention, the “polylactic acid resin” refers to a polymer containing L-lactic acid and / or D-lactic acid as a main constituent component and may contain a copolymer component other than lactic acid. The content of other copolymerization components other than lactic acid is 30 mol based on the total amount of monomers constituting the polylactic acid resin, that is, L-lactic acid and / or D-lactic acid, and other copolymerization components. % Or less, and preferably 10 mol% or less.

  In the present specification and claims, when referring to parts by weight, parts by weight of “polylactic acid resin” means “L-lactic acid and / or D-lactic acid as a main constituent component and other common components other than lactic acid”. A polymer which may contain a polymerization component, wherein the other copolymerization component is 30 mol% or less relative to the total amount of L-lactic acid and / or D-lactic acid and the other copolymerization component ” The weight part.

The other copolymerizable component other than lactic acid, ethylene glycol, profile propylene glycol, butanediol, heptanediol, hexanediol, octanediol, nonanediol, decanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, glycerine, Glycol compounds such as pentaerythritol, bisphenol A, polyethylene glycol, polypropylene glycol and polytetramethylene glycol, oxalic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, malonic acid, glutaric acid, cyclohexanedicarboxylic acid, terephthalic acid, Isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, bis (p-carboxyphenyl) methane, anthracene dicarboxylic acid, 4,4'-diphenyl ether di Dicarboxylic acids such as carboxylic acid, 5-sodium sulfoisophthalic acid, 5-tetrabutylphosphonium isophthalic acid, glycolic acid, hydroxypropionic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxycaproic acid, hydroxybenzoic acid and the like, and Examples include lactones such as caprolactone, valerolactone, propiolactone, undecalactone, and 1,5-oxepan-2-one.

  The polylactic acid resin used in the present invention preferably has a high optical purity of the lactic acid component from the viewpoint of compatibility. That is, among the total lactic acid components contained in the polylactic acid resin, those containing 80% or more of the L isomer or 80% or more of the D isomer are preferred, and 90% or more of the L isomer is contained or 90% of the D isomer is contained. %, More preferably 95% or more of L-form or 95% or more of D-form. In the present invention, polylactic acid having a high optical purity mainly composed of L-form or D-form may be used alone or a mixture thereof may be used.

  In addition, as a polylactic acid resin used in the present invention, a block copolymer of polylactic acid composed of a segment composed of L-lactic acid units (poly L-lactic acid) and a segment composed of D-lactic acid units (poly D-lactic acid) Coalescence can also be used.

  Examples of such a polylactic acid block copolymer include block copolymers described in JP-A No. 2002-356543 and International Publication No. WO2008 / 081617.

  The molecular weight and molecular weight distribution of the polylactic acid resin are not particularly limited as long as it can be molded by melting, but the weight average molecular weight is usually 10,000 or more, preferably 40,000 or more, more preferably. Is preferably 80,000 or more. The weight average molecular weight here refers to the molecular weight in terms of polystyrene measured by gel permeation chromatography.

  The melting point of the polylactic acid resin is not particularly limited, but is preferably 120 to 240 ° C, more preferably 160 to 230 ° C.

  As a method for producing the polylactic acid resin, a known polymerization method can be used, and examples thereof include a direct polymerization method from lactic acid and a ring-opening polymerization method via lactide.

  In the present invention, the liquid crystal polymer blended in the polylactic acid resin is a polyester or polyester amide that forms an anisotropic melt phase, and is particularly suitable if it is called a thermotropic liquid crystal polyester or a thermotropic liquid crystal polyester amide by those skilled in the art. Not limited.

  The property of the anisotropic molten phase can be confirmed by a normal deflection inspection method using an orthogonal deflector, that is, by observing a sample placed on a hot stage in a nitrogen atmosphere.

  The main repeating units constituting the liquid crystal polymer used in the present invention are aromatic oxycarbonyl repeating units, aromatic dicarbonyl repeating units, aromatic dioxy repeating units, aromatic aminooxy repeating units, aromatic diamino repeating units, aromatic amino One or more selected from a carbonyl repeating unit, an aromatic oxydicarbonyl repeating unit, and an aliphatic dioxy repeating unit.

  Further, the liquid crystal polymer used in the present invention may contain a repeating unit other than the main repeating unit as a constituent component within a range not impairing the object of the present invention, and may contain, for example, a thioester bond. . Examples of the monomer that gives such a bond include mercapto aromatic carboxylic acid, aromatic dithiol, and hydroxy aromatic thiol. The amount of the monomer that gives a repeating unit other than these main repeating units is aromatic oxycarbonyl repeating unit, aromatic dicarbonyl repeating unit, aromatic dioxy repeating unit, aromatic aminooxy repeating unit, aromatic diamino repeating unit. It is made into 10 mol% or less with respect to the total amount of the main monomer which gives a unit, an aromatic aminocarbonyl repeating unit, an aromatic oxydicarbonyl repeating unit, and an aliphatic dioxy repeating unit.

  The liquid crystal polymer composed of each of these repeating units may or may not form an anisotropic molten phase depending on the constituent components, the composition ratio in the polymer, and the sequence distribution, but the liquid crystal used in the present invention. Polymers are limited to those that form an anisotropic melt phase.

  Specific examples of the monomer that gives an aromatic oxycarbonyl repeating unit include, for example, parahydroxybenzoic acid, metahydroxybenzoic acid, orthohydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, and 5-hydroxy-2-naphthoic acid. Acid, 3-hydroxy-2-naphthoic acid, 4'-hydroxyphenyl-4-benzoic acid, 3'-hydroxyphenyl-4-benzoic acid, 4'-hydroxyphenyl-3-benzoic acid, their alkyl, alkoxy or Halogen-substituted products, and ester-forming derivatives such as acylated products, ester derivatives, and acid halides thereof can be mentioned. Among these, parahydroxybenzoic acid and 6-hydroxy-2-naphthoic acid are preferable from the viewpoint of easy adjustment of the characteristics and crystal melting temperature of the liquid crystal polymer from which they are obtained.

  Specific examples of the monomer giving the aromatic dicarbonyl repeating unit include, for example, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1 , 4-naphthalenedicarboxylic acid, aromatic dicarboxylic acids such as 4,4′-dicarboxybiphenyl, alkyl, alkoxy or halogen-substituted products thereof, ester derivatives thereof, and ester-forming derivatives such as acid halides. . Among these, terephthalic acid, 2,6-naphthalenedicarboxylic acid is preferable because it easily adjusts the mechanical properties, heat resistance, crystal melting temperature, and moldability of the liquid crystal polymer to an appropriate level.

  Specific examples of the monomer that gives an aromatic dioxy repeating unit include, for example, hydroquinone, resorcin, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 4,4′-dihydroxybiphenyl, 3,3′-dihydroxybiphenyl, 3,4′-dihydroxybiphenyl, aromatic diols such as 4,4′-dihydroxybiphenyl ether, alkyl, alkoxy or halogen substituents thereof, and And ester-forming derivatives such as acylated products. Among these, hydroquinone and 4,4'-dihydroxybiphenyl are preferable from the viewpoint of reactivity during polymerization and characteristics of the obtained liquid crystal polymer.

  Specific examples of the monomer that gives an aromatic aminooxy repeating unit include, for example, p-aminophenol, m-aminophenol, 4-amino-1-naphthol, 5-amino-1-naphthol, and 8-amino-2. -Aromatic amines such as naphthol and 4-amino-4'-hydroxybiphenyl, alkyl, alkoxy or halogen substituents thereof, and ester or amide-forming derivatives thereof such as acylated products thereof.

  Specific examples of the monomer that gives an aromatic diamino repeating unit include aromatic diamines such as p-phenylenediamine, m-phenylenediamine, 1,5-diaminonaphthalene, 1,8-diaminonaphthalene, and alkyls thereof. , Alkoxy- or halogen-substituted products, and amide-forming derivatives thereof such as acylated products thereof.

  Specific examples of the monomer that gives an aromatic aminocarbonyl repeating unit include aromatic aminocarboxylic acids such as p-aminobenzoic acid, m-aminobenzoic acid, 6-amino-2-naphthoic acid, and alkyls thereof. , Alkoxy- or halogen-substituted products, and ester or amide-forming derivatives thereof such as acylated products, ester derivatives, and acid halides.

  Specific examples of monomers that give aromatic oxydicarbonyl repeating units include hydroxy aromatic dicarboxylic acids such as 3-hydroxy-2,7-naphthalenedicarboxylic acid, 4-hydroxyisophthalic acid, and 5-hydroxyisophthalic acid. Examples include acids, alkyl, alkoxy or halogen-substituted products thereof, and ester-forming derivatives such as acylated products, ester derivatives, and acid halides thereof.

  Specific examples of the monomer that gives an aliphatic dioxy repeating unit include aliphatic diols such as ethylene glycol, 1,4-butanediol, 1,6-hexanediol, and acylated products thereof. Polyesters containing aliphatic dioxy repeating units, such as polyethylene terephthalate and polybutylene terephthalate, are converted into the above aromatic oxycarboxylic acids, aromatic dicarboxylic acids, aromatic diols, aromatic hydroxyamines, aromatic diamines, aromatics. A liquid crystal polymer containing an aliphatic dioxy repeating unit can also be obtained by reacting with an aminocarboxylic acid, an aromatic oxydicarboxylic acid and an acylated product, an ester derivative, an acid halide or the like thereof.

  As described above, the repeating unit contained in the liquid crystal polymer used in the present invention and the monomer that gives it have been described. The liquid crystal polymer used in the present invention has a crystal melting temperature of 170 to 250 ° C. measured by a differential scanning calorimeter. Preferably, a temperature of 180 to 230 ° C. is suitable. If a liquid crystal polymer having a crystal melting temperature in the range of 170 to 250 ° C. is used, the liquid crystal polymer can be blended with the polylactic acid resin while suppressing the decomposition of polylactic acid, and the liquid crystal polymer is uniformly distributed in the polylactic acid continuous phase. A dispersed polylactic acid resin composition is obtained.

  If the crystal melting temperature of the liquid crystal polymer is lower than 170 ° C., the load on the stirring motor may increase during melt kneading, and the kneader may be damaged. Even if kneading is possible, The liquid crystal polymer phase tends to be non-uniformly dispersed. Moreover, when it exceeds 250 degreeC, decomposition | disassembly of polylactic acid becomes remarkable and there exists a tendency for sufficient performance not to be obtained.

  As the liquid crystal polymer satisfying the crystal melting temperature range of 170 to 250 ° C., a liquid crystal polyester composed of repeating units represented by the following formulas [I] to [IV] is particularly preferably used.

In the present specification and claims, “consisting of repeating units represented by the following formulas [I] to [IV]” means that the liquid crystal polymer is represented by the formulas [I] to [IV] as its constituent components. It means that other repeating units may be contained as long as the crystal melting temperature of the liquid crystal polymer is in the range of 170 to 250 ° C. in addition to the repeating units.
In the present specification and claims, p + q + r + s = 100 mol%.

［Ａｒ_１およびＡｒ_２は、それぞれ一種以上の２価の芳香族基を表し、ｐ、ｑ、ｒおよびｓは、各繰返し単位の液晶ポリエステル中での組成比（モル％）であり、以下の式を満たすものである：
０．４≦ｐ／ｑ≦２．０
２≦ｒ≦１５、および
２≦ｓ≦１５］。 Furthermore, in the present specification and claims, the “divalent aromatic group” means an aromatic group having two substituents capable of forming an ester bond or an amide bond.

[Ar ₁ and Ar ₂ each represent one or more divalent aromatic groups, and p, q, r and s are the composition ratios (mol%) in the liquid crystal polyester of each repeating unit, Which satisfies the formula:
0.4 ≦ p / q ≦ 2.0
2 ≦ r ≦ 15, and 2 ≦ s ≦ 15].

A preferable range of p, q, r, and s satisfies the following formula.
35 ≦ p ≦ 48,
35 ≦ q ≦ 48,
2 ≦ r ≦ 15, and 2 ≦ s ≦ 15.

および/または

であり、
Ａｒ₂が、

および／または

であるものである。 In the formulas [III] and [IV], Ar ₁ and Ar ₂ are preferably
Ar ₁ is

And / or

And
Ar ₂ is

And / or

It is what is.

  As the liquid crystal polymer in the present invention, a blend of two or more liquid crystal polymers may be used for the purpose of improving fluidity during molding.

  Hereinafter, a method for producing a liquid crystal polymer used in the present invention will be described.

  The production method of the liquid crystal polymer used in the present invention is not particularly limited, and a known polycondensation method for forming an ester bond or an amide bond composed of a combination of the above monomers, for example, a melt acidosis method, a slurry polymerization method, or the like is used. Can do.

  The melt acidosis method is a method in which a monomer is first heated to form a molten liquid of a reactant, and the reaction is continued to obtain a molten polymer, which is a preferred method for producing the liquid crystal polymer used in the present invention. It is. Note that a vacuum may be applied to facilitate removal of volatiles (for example, acetic acid, water, etc.) by-produced in the final stage of the condensation.

  The slurry polymerization method is a method of reacting in the presence of a heat exchange fluid, and the solid product is obtained in a state suspended in a heat exchange medium.

  In both cases of the melt acidification method and the slurry polymerization method, the polymerizable monomer component used in producing the liquid crystal polymer is a modified form in which hydroxyl groups and / or amino groups are acylated, that is, as a lower acylated product. It can also be used for the reaction. The lower acyl group preferably has 2 to 5 carbon atoms, more preferably 2 or 3 carbon atoms. Particularly preferred is a method using an acetylated product of the monomer in the reaction.

  The acylated product of the monomer may be prepared by separately acylating and synthesized in advance, or it may be generated in the reaction system by adding an acylating agent such as acetic anhydride to the monomer during the production of the liquid crystal polymer. it can.

  In any case of the melt acidification method or the slurry polymerization method, a catalyst may be used as needed during the reaction.

  Specific examples of the catalyst include organotin compounds such as dialkyltin oxide (for example, dibutyltin oxide) and diaryltin oxide; antimony trioxide; titanium dioxide; organotitanium compounds such as alkoxytitanium silicate and titanium alkoxide; alkali or alkali of carboxylic acid Examples include earth metal salts (for example, potassium acetate); inorganic acid salts (for example, potassium sulfate); Lewis acid (for example, boron trifluoride); gaseous acid catalysts such as hydrogen halide (for example, hydrogen chloride).

  The ratio of the catalyst used is usually 10 to 1000 ppm, preferably 20 to 200 ppm, based on the monomer weight.

  The liquid crystal polymers obtained by such a polycondensation reaction are each extracted from the polymerization reaction tank in a molten state, and then processed into pellets, flakes, or powders.

  In addition, polylactic acid resin and liquid crystal polymer are blended with polymers other than polylactic acid resin and liquid crystal polymer, and those with additives such as particles, flame retardant, antistatic agent, etc., as long as their properties are not impaired. May be provided. The blending amount of these additives with respect to the polylactic acid resin and the liquid crystal polymer is 0.1 to 20 parts by weight with respect to 100 parts by weight of the polylactic acid resin and the liquid crystal polymer.

The method for producing the polylactic acid resin composition molded article of the present invention comprises:
1) A composition comprising a polylactic acid resin and 7 to 50 parts by weight of a liquid crystal polymer with respect to 100 parts by weight of the polylactic acid resin and melt-kneaded at a temperature of 170 to 250 ° C. Obtaining a product,
2) A step of melt-processing the composition obtained in step 1) to obtain a molded product, and
3) A step of heat-treating the molded product obtained in step 2) at a temperature of 102 to 140 ° C. for 5 to 55 minutes,
Preferably, in the above production method, the composition obtained in step 1) is melt processed to 127 (length) × 12.7 (width) × 3.2 (thickness) mm. It is a composition having a shrinkage ratio represented by the following formula of less than 1% when the test piece is heat-treated at a temperature of 110 ° C. for 30 minutes. To:
Shrinkage rate (%) = [length in the vertical direction before heating (mm) −length in the vertical direction after heating (mm)]
/ Longitudinal length before heating (mm) × 100.

  When a polylactic acid resin is molded alone, there is a problem that the molded product shrinks by heating. For example, when a test piece having the same shape as described above is prepared, the shrinkage rate is as high as 2 to 5%. It was not suitable for molded products for heat-resistant applications.

  On the other hand, the polylactic acid resin composition molded product of the present invention obtained by the method for producing a molded product of the polylactic acid resin composition of the present invention is to provide a molded product that is remarkably suppressed from shrinkage due to heating and has excellent dimensional accuracy. Is something that can be done.

  The shrinkage ratio is preferably less than 1%, more preferably less than 0.8%, and even more preferably less than 0.5%.

  Moreover, the polylactic acid resin composition molded article of the present invention was measured for the above-mentioned strip-shaped test piece by measuring the deflection temperature under load (T1) before heating and the deflection temperature under load (T2) after heating. (T2 / T1) is 1.3 or more, preferably 1.5 or more, more preferably 1.6 or more. This shows that the deflection temperature under load was significantly improved by subjecting the polylactic acid resin composition to a heat treatment after being melt-processed into a molded product. The upper limit of (T2 / T1) is about 2.5.

  The deflection temperature (T2) after heating of the strip-shaped test piece is improved to 70 ° C. or higher, preferably 80 ° C. or higher, more preferably 90 ° C. or higher. It can be applied to molded products for heat-resistant applications. The upper limit of T2 is about 150 ° C.

  On the other hand, when the polylactic acid resin is molded alone, even if the molded product is heated alone, T2 / T1 is about 1.2, and the deflection temperature under load does not improve so much. T2) is also about 65 ° C., which is difficult to use for heat resistant applications.

Hereinafter, the manufacturing method of the polylactic acid resin composition molded article of the present invention will be described.
In the method for producing a polylactic acid resin composition molded article of the present invention, first, in step 1), 7 to 50 parts by weight of a liquid crystal polymer is blended with the polylactic acid resin described above with respect to 100 parts by weight of the polylactic acid resin. The composition containing a polylactic acid resin and a liquid crystal polymer is obtained by melt-kneading at a temperature of 170 to 250 ° C.

  The compounding amount of the liquid crystal polymer with respect to 100 parts by weight of the polylactic acid resin is 7 to 50 parts by weight, preferably 8 to 45 parts by weight, more preferably 10 to 43 parts by weight, and further preferably 11 to 25 parts by weight. Good part.

  When the blending amount of the liquid crystal polymer with respect to 100 parts by weight of the polylactic acid resin is less than 7 parts by weight, the shrinkage suppressing effect and the heat resistance improving effect of the obtained polylactic acid resin composition molded product cannot be sufficiently expected. When the blending amount of the liquid crystal polymer exceeds 50 parts by weight, the amount of biomass used decreases, which departs from the gist of the present invention to provide a polymer that contributes to the suppression of the increase in carbon dioxide concentration in the atmosphere.

  If the melt kneading temperature is lower than 170 ° C., the load on the stirring motor may increase during kneading and the kneader may be damaged, and even if kneading is possible, the dispersion of the liquid crystal polymer phase is not uniform. Tend to be. On the other hand, when the melt kneading temperature exceeds 250 ° C., the decomposition of polylactic acid becomes remarkable, and there is a tendency that sufficient performance cannot be obtained.

  In the melt kneading of the polylactic acid resin and the liquid crystal polymer in step 1), a kneading machine such as a Banbury mixer, a kneader, a single screw or a twin screw extruder is used. For example, when a twin screw extruder is used, it is performed while the vent port is evacuated at a specific energy (extruder work amount per discharge amount (kW · h / kg)) of 0.1 to 0.25. However, the present invention is not limited to this, and it may be performed in an inert gas atmosphere.

  The composition containing the polylactic acid resin and the liquid crystal polymer thus obtained by melt-kneading is processed into a pellet, flake, or powder, and then subjected to step 2).

  Step 2) is a step in which the composition obtained in step 1) is melt processed to obtain a molded product. In step 2), a molded product in a solid form having a desired shape and size is obtained by a conventionally known melt processing method, for example, injection molding at a temperature of 200 to 250 ° C., and then subjected to step 3).

  Step 3) is a step of heat-treating the molded product obtained in step 2) at a temperature of 102 to 140 ° C. for 5 to 55 minutes. In such a heat treatment step, the solid-form molded product having a desired shape and size melt-processed as described above is heat-treated at a temperature of 102 to 140 ° C. for 5 to 55 minutes so that the solid form is maintained. The heating temperature is preferably 102 to 130 ° C, more preferably 102 to 120 ° C. The heating time is preferably 10 to 50 minutes, more preferably 15 to 45 minutes. When the heating temperature is 102 ° C. or the heating time is less than 5 minutes, the effect of improving heat resistance by heating is not sufficiently exhibited, and when the heating temperature is 140 ° C. or the heating time exceeds 55 minutes, it may be melted or decomposed. There is.

  The heat treatment in step 3) is performed using a heating means such as an oven, and may be performed under normal pressure or under reduced pressure, preferably in an inert gas atmosphere.

  As mentioned above, after melt-kneading the composition obtained by melt-kneading the polylactic acid resin and the liquid crystal polymer to form a molded article, the polylactic acid resin composition molded article obtained by performing heat treatment is The shrinkage due to heating is suppressed and the heat resistance is greatly improved. This is significantly superior to the case where a molded product obtained by molding a polylactic acid resin alone is heat-treated.

  In step 1) and / or step 2) of the production method of the present invention, for the purpose of improving the compatibility between the polylactic acid resin and the liquid crystal polymer, 0.5 to 10 parts by weight with respect to 100 parts by weight of the polylactic acid resin. Preferably, 1 to 5 parts by weight of a compatibilizer may be added.

  When the compounding amount of the compatibilizer is less than 0.5 parts by weight, a sufficient compatibility improving effect cannot be obtained, and when it exceeds 10 parts by weight, the melt viscosity of the polylactic acid resin composition obtained by step 1) is remarkably high. There is a tendency to increase and decrease fluidity.

  In the present specification and claims, the compatibilizing agent means one having a function of localizing at the interface between phases of each polymer constituting the blend polymer and reducing the interfacial tension between these phases.

  Preferable examples of the compatibilizing agent include a carboxyl group-reactive compound, a polymer having a carboxyl group, an epoxy group or an acid anhydride group.

  In the present invention, the carboxyl group-reactive compound used as the compatibilizer is not particularly limited as long as it is a compound reactive with the carboxyl end group of the polylactic acid resin, but the thermal decomposition of the polylactic acid resin is not limited. It is more preferable if it is reactive with the carboxyl group of the acidic low molecular compound produced by hydrolysis or the like, and it is also a compound reactive with the hydroxyl group end group of the acidic low molecular compound produced by thermal decomposition. More preferred.

  Examples of such carboxyl group-reactive compounds include bisphenol A, resorcinol, hydroquinone, pyrocatechol, bisphenol F, saligenin, 1,3,5-trihydroxybenzene, bisphenol S, trihydroxy-diphenyldimethylmethane, 4,4 ′. -Bisphenol-glycidyl ether type epoxy compounds such as dihydroxybiphenyl, 1,5-dihydroxynaphthalene, cashew phenol, 2,2,5,5-tetrakis (4-hydroxyphenyl) hexane, glycidyl ester type epoxy such as glycidyl phthalate Compounds, glycidylamine epoxy compounds such as N-glycidylaniline, glycidylimide compounds, alicyclic epoxy compounds, polyfunctional epoxy compounds containing two or more epoxy groups, 2 Oxazoline compounds such as 2′-m-phenylenebis (2-oxazoline) and 2,2′-p-phenylenebis (2-oxazoline), oxazine compounds, N, N′-di-2,6-diisopropylphenylcarbodiimide, At least one functional group selected from carbodiimide compounds such as 2,6,2 ′, 6′-tetraisopropyldiphenylcarbodiimide, polycarbodiimide, epoxy group, amino group, isocyanate group, hydroxyl group, mercapto group, and ureido group It is preferable to use at least one kind of compound selected from organic silane compounds such as alkoxysilanes having a polyvalent epoxy compound, an epoxy group, an organic silane compound having an isocyanate group, and a carbodiimide compound. Multifunctional Epoxy compounds, carbodiimide compounds. As the carboxyl group-reactive compound, one or more compounds can be arbitrarily selected and used.

  Moreover, you may use for a mixing | blending in the form with which the carboxyl group-reactive compound used as these compatibilizing agents was made to react with the compound which has a carboxyl group which comprises lactic acid and / or a liquid crystal polymer.

  Examples of the polymer having a carboxyl group, an epoxy group or an acid anhydride group used as a compatibilizing agent in the present invention include ethylene / (meth) acrylate glycidyl copolymer, ethylene / ethyl (meth) acrylate-g. -Maleic anhydride copolymer ("g" represents graft, the same applies hereinafter), ethylene / glycidyl (meth) acrylate-g-methyl (meth) acrylate copolymer, ethylene / ethyl (meth) acrylate / Maleic anhydride copolymer-g- (meth) acrylic acid methyl copolymer, an epoxy group-containing polymer compound obtained by epoxidizing a double bond part of a polymer having a double bond, epichlorohydrin to a novolac type phenol resin A reacted novolac type epoxy resin can be used.

  In the method for producing a molded product of the polylactic acid resin composition of the present invention, an inorganic filler and / or an organic filler may be further blended in step 1) and / or step 2) if necessary.

  Examples of the inorganic filler and / or organic filler that may be blended in the method for producing a molded article of the polylactic acid resin composition of the present invention include, for example, glass fiber, silica alumina fiber, alumina fiber, carbon fiber, and potassium titanate fiber. , Aluminum borate fiber, aramid fiber, talc, mica, graphite, wollastonite, dolomite, clay, glass flake, glass beads, glass balloon, calcium carbonate, barium sulfate, and titanium oxide The above is mentioned. In these, glass fiber is preferable at the point which the balance of a physical property and cost is excellent.

  The blending amount of the inorganic filler and / or the organic filler is 0.1 to 200 parts by weight, preferably 1 to 100 parts by weight with respect to 100 parts by weight of the total amount of the polylactic acid resin and the liquid crystal polymer.

  In the method for producing a molded product of the polylactic acid resin composition of the present invention, if necessary, in the step 1) and / or step 2), in addition to the polylactic acid resin and the liquid crystal polymer, further within the range not impairing the object of the present invention. You may mix | blend another resin component. Examples of other resin components include polyamides, polyesters, polyacetals, polyphenylene ethers and modified products thereof, and thermoplastic resins such as polysulfone, polyethersulfone, polyetherimide, and polyamideimide, phenol resins, epoxy resins, and polyimide resins. And other thermosetting resins.

  Other resin components can be blended alone or in combination of two or more. The compounding amount of the other resin component is 0.1 to 100 parts by weight, preferably 0.1 to 80 parts by weight, based on 100 parts by weight of the total amount of the polylactic acid resin and the liquid crystal polymer. .

  In the method for producing a polylactic acid resin composition molded article of the present invention, a crystal nucleating agent that promotes the formation of crystal nuclei of the polylactic acid resin can be added in step 1) and / or step 2).

  As the crystal nucleating agent used in the present invention, those generally used as a polymer crystal nucleating agent can be used without particular limitation, and both inorganic crystal nucleating agents and organic crystal nucleating agents can be used. . Specific examples of inorganic crystal nucleating agents include talc, kaolinite, montmorillonite, synthetic mica, clay, zeolite, silica, graphite, carbon black, zinc oxide, magnesium oxide, titanium oxide, calcium sulfide, boron nitride, calcium carbonate, Examples thereof include metal salts of barium sulfate, aluminum oxide, neodymium oxide and phenylphosphonate. These inorganic crystal nucleating agents are preferably modified with an organic substance in order to enhance dispersibility in the composition. The average particle size of the inorganic crystal nucleating agent is preferably 10 μm or less, more preferably 5 μm or less, and particularly preferably 3 μm or less. Specific examples of organic crystal nucleating agents include sodium benzoate, potassium benzoate, lithium benzoate, calcium benzoate, magnesium benzoate, barium benzoate, lithium terephthalate, sodium terephthalate, potassium terephthalate, calcium oxalate , Sodium laurate, potassium laurate, sodium myristate, potassium myristate, calcium myristate, sodium octacosanoate, calcium octacosanoate, sodium stearate, potassium stearate, lithium stearate, calcium stearate, magnesium stearate, stearic acid Barium, sodium montanate, calcium montanate, sodium toluate, sodium salicylate, potassium salicylate, zinc salicylate, aluminum Organic carboxylic acid metal salts such as minium dibenzoate, potassium dibenzoate, lithium dibenzoate, sodium β-naphthalate, sodium cyclohexanecarboxylate, organic sulfonates such as sodium p-toluenesulfonate, sodium sulfoisophthalate, lauric acid amide , Stearic acid amide, ethylene bis lauric acid amide, ethylene bis stearic acid amide, palmitic acid amide, hydroxy stearic acid amide, erucic acid amide, trimesic acid tris (t-butylamide), organic carboxylic acid amides such as terephthalic acid dianilide, low Density polyethylene, high density polyethylene, polypropylene, polyisopropylene, polybutene, poly-4-methylpentene, poly-3-methylbutene-1, polyvinyl Sodium or potassium salt of a polymer having a carboxyl group such as a polymer such as loalkane, polyvinyltrialkylsilane, high melting point polylactic acid, sodium salt of ethylene-acrylic acid or methacrylic acid copolymer, sodium salt of styrene-maleic anhydride copolymer (So-called ionomers), benzylidene sorbitol and derivatives thereof, phosphorus compound metal salts such as sodium-2,2′-methylenebis (4,6-di-t-butylphenyl) phosphate, and 2,2-methylbis (4,6 -Di-t-butylphenyl) sodium and the like.

As the crystal nucleating agent used in the production method of the present invention, at least one selected from talc, organic carboxylic acid metal salts and organic carboxylic acid amides is preferable among those exemplified above. Preferable talc includes talc having an average particle size of 0.5 to 7 μm and a ratio of SiO ₂ and MgO in the component excluding a loss during combustion of 93% by weight or more. The crystal nucleating agent may be used alone or in combination of two or more.

  The compounding amount of the crystal nucleating agent is preferably 0.01 to 30 parts by weight, more preferably 0.05 to 20 parts by weight, with respect to 100 parts by weight of the total amount of the polylactic acid resin and the liquid crystal polymer. Part by weight is particularly preferred.

  The compatibilizer, inorganic filler and / or organic filler, other resin component and crystal nucleating agent described above are combined with the polylactic acid resin and the liquid crystal polymer in step 1), together with a Banbury mixer, kneader, uniaxial or biaxial. You may mix | blend with a polylactic acid resin composition by melt-kneading using an extruder etc., or you may mix | blend when melt-processing the composition containing a polylactic acid resin and a liquid crystal polymer in process 2). .

  The polylactic acid resin composition molded article obtained by the production method of the present invention is suppressed in shrinkage due to heating and has excellent heat resistance, so that it is a mechanical part, electrical / electronic part, building / civil engineering member, household / office supplies. It can be used for various purposes such as furniture parts and daily necessities. It is particularly suitable for applications that require dimensional accuracy under heating, such as electrical / electronic parts such as connectors, relays and switches, computer-related parts, motor parts, optical equipment such as cameras and watches, precision machine-related parts, etc. .

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to a following example.

In the examples and comparative examples, the following were used as the polylactic acid resin and the liquid crystal polymer.
Polylactic acid resin: NatureWorks Co. polylactic L- lactic ^acid, Ingeo TM 3001D (number average molecular weight 76000, weight average molecular weight 146,000, crystalline melting temperature 169 ° C.).
Liquid crystal polymer: Aromatic liquid crystal polyester (parahydroxybenzoic acid / 6-hydroxy-2-naphthoic acid / hydroquinone / terephthalic acid copolymer, crystal melting temperature 220 ° C.) manufactured by Ueno Pharmaceutical Co., Ltd.

(Measurement of shrinkage rate)
The length [D1] of the test piece before heating and the length [D2] of the test piece after heating were measured and calculated by the following equations.
Shrinkage rate (%) = [length in the vertical direction before heating (mm) −length in the vertical direction after heating (mm)]
/ Longitudinal length before heating (mm) × 100

(Measurement of deflection temperature under load)
According to ASTM D648, the load was 1.82 MPa and the temperature increase rate was 2 ° C./min.

(Tensile strength and elongation)
Using an INSTRON 5567 (universal testing machine manufactured by Instron Japan Company Limited), the distance between spans was 64 mm and the tensile speed was 5 mm / min.

(Bending strength)
A three-point bending test was performed using an INSTRON 5567 (universal testing machine manufactured by Instron Japan Company Limited) at a span distance of 50 mm and a compression speed of 1.3 mm / min.

(Flexural modulus)
Measured according to ASTM D790.

(Izod impact strength)
Measured according to ASTM D256.

Example 1
27.0 g of polylactic acid resin and 3.0 g of a liquid crystal polymer were mixed and dried under reduced pressure at 80 ° C. for 10 hours. This dried product was extruded using a twin screw extruder PM30 manufactured by Ikegai Co., Ltd. while kneading at a cylinder temperature of 220 ° C. and a screw rotation speed of 150 rpm to prepare a composition containing a polylactic acid resin and a liquid crystal polymer.

  Subsequently, this composition was injection-molded at a cylinder temperature of 240 ° C. and a mold temperature of 40 ° C. using an injection molding machine (manufactured by Nissei Plastic Industry Co., Ltd. UH1000-110) having a clamping pressure of 110 tons, 127 × 12.7. A 3.2 mm strip test piece A (unheated test piece) was prepared.

  Subsequently, the test piece A was heat-processed at 110 degreeC for 30 minute (s) by oven, and the test piece B (heat-processing test piece) was created.

  The physical properties of the obtained test pieces A and B were measured. The results are shown in Table 1.

(Examples 2-4, Comparative Examples 1-2)
Test pieces A and B were prepared in the same manner as in Example 1 except that the blending amounts of the polylactic acid resin and the liquid crystal polymer were as shown in Table 1, and the physical properties were measured. The results are shown in Table 1.

  Each of the molded products of Examples 1 to 4 had a shrinkage rate of 0.5% or less, and the shrinkage due to heating was remarkably suppressed. Moreover, the ratio (T2 / T1) of the deflection temperature under load before and after heating was 1.5 or more, and the heat resistance improvement effect by heating was remarkable.

  On the other hand, the molded products of Comparative Examples 1 and 2 have a shrinkage ratio of more than 1%, and are not inhibited from shrinkage due to heating, and the ratio of load deflection temperatures before and after heating (T2 / T1) is also 1. .3, and the effect of improving heat resistance was small.

Table 1

Claims (10)

1) A composition comprising a polylactic acid resin and 7 to 50 parts by weight of a liquid crystal polymer with respect to 100 parts by weight of the polylactic acid resin and melt-kneaded at a temperature of 170 to 250 ° C. Obtaining a product,
2) A step of melt-processing the composition obtained in step 1) to obtain a molded product, and
3) A step of heat-treating the molded product obtained in step 2) at a temperature of 102 to 140 ° C. for 5 to 55 minutes,
The manufacturing method of the polylactic acid resin composition molded article containing this. The composition obtained in the step 1) is melt-processed to form a strip-shaped test piece of 127 (length) × 12.7 (width) × 3.2 (thickness) mm. 2. The polylactic acid resin composition molding according to claim 1, wherein the composition has a shrinkage ratio represented by the following formula of less than 1% when heated at a temperature of 110 ° C. for 30 minutes. Product manufacturing method:
Shrinkage rate (%) = [length in the vertical direction before heating (mm) −length in the vertical direction after heating (mm)]
/ Longitudinal length before heating (mm) × 100.   The ratio (T2 / T1) between the deflection temperature under load (T1) before heating the strip-shaped specimen for 30 minutes at a temperature of 110 ° C. and the deflection temperature under load (T2) after heating under the same conditions is 1. The method for producing a molded product of the polylactic acid resin composition according to claim 2, which is 3 or more.   The method for producing a molded product of a polylactic acid resin composition according to claim 2 or 3, wherein a deflection temperature under load (T2) after heat-treating the strip-shaped test piece at a temperature of 110 ° C for 30 minutes is 70 ° C or more. .   The method for producing a polylactic acid resin composition molded article according to any one of claims 1 to 4, wherein the liquid crystal polymer has a crystal melting temperature measured by a differential scanning calorimeter of 170 to 250 ° C. The method for producing a polylactic acid resin composition molded article according to any one of claims 1 to 5, wherein the liquid crystal polymer is a liquid crystal polyester composed of repeating units represented by the following formulas [I] to [IV]:

[Ar ₁ and Ar ₂ each represent one or more divalent aromatic groups, and p, q, r, and s are composition ratios (mol%) in the liquid crystal polyester resin of each repeating unit, Which satisfies the formula:
0.4 ≦ p / q ≦ 2.0
2 ≦ r ≦ 15, and 2 ≦ s ≦ 15]. The method for producing a molded product of a polylactic acid resin composition according to claim 6, wherein the composition ratio of the repeating units represented by the formulas [I] to [IV] satisfies the following formula:
35 ≦ p ≦ 48,
35 ≦ q ≦ 48,
2 ≦ r ≦ 15, and 2 ≦ s ≦ 15. Ar ₁ is

And / or

And
Ar ₂ is

And / or

The method for producing a molded product of the polylactic acid resin composition according to claim 6 or 7.   A polylactic acid resin composition molded article obtained by the method according to claim 1.   The polylactic acid resin composition molded article according to claim 9, wherein the molded article is an electrical / electronic part, a computer-related part, a motor part, or an optical instrument / precision machine-related part.