JP2003301097A - Resin composition and molded article thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition excellent in moldability, bleed-out resistance and heat resistance; and a molded article made thereof. <P>SOLUTION: This resin composition comprises a polylactic acid resin, a polyacetal resin, and a crystallization accelerator. As the crystallization accelerator, a crystal nucleating agent and/or a plasticizer is used and the compounding amount of the crystallization accelerator is preferably 30-0.01 pts.wt. with respect to 100 pts.wt. the sum of the polylactic acid resin and the polyacetal resin. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention comprises a polylactic acid resin, a polyacetal resin and a crystallization accelerator,
The present invention relates to a resin composition having excellent moldability, bleed-out resistance, and heat resistance, and a molded product made from the resin composition.

[0002]

2. Description of the Related Art Polylactic acid resin has a high melting point and can be melt-molded, so that it is expected as a practically excellent biodegradable polymer. However, since the polylactic acid resin has a slow crystallization rate, there is a limit in crystallizing it and using it as a molded article. For example, in the case of injection molding a polylactic acid resin, there have been practical problems such as long molding cycle time and heat treatment after molding, and large deformation during molding and heat treatment.

As one of the methods for improving the moldability of polylactic acid resin, a method of adding a crystallization accelerator has been studied so far, but the problem that the improvement effect by the method is still insufficient has been a problem. there were. Further, when a plasticizer is used as the crystallization accelerator, there is a problem in that the plasticizer bleeds out during heat treatment and the polymer itself becomes brittle.

On the other hand, the technique of blending two or more polymers is widely known as a polymer alloy, and this polymer alloy is widely used for the purpose of improving the defects of individual polymers. However, 2
When more than one kind of polymer is mixed, the dispersibility between the polymers is poor in many cases, and it is not possible to process into the shape of a pellet or a molded product, or there is a tendency to exhibit inferior properties.

However, in rare cases, two kinds of polymers sometimes form a uniform amorphous phase, and these kinds of polymers are generally compatible or miscible polymer alloys and may exhibit excellent properties such as transparency. Expected, but few.

As a polymer compatible with a polylactic acid resin, polyethylene glycol (for example, Non-Patent Document 1
However, when these polymers are mixed, there is a problem that the crystallinity of the polylactic acid resin is significantly reduced. .

Polyvinylphenol (see, for example, Non-Patent Document 3) is known as a polymer compatible with the polyacetal resin, but since polyvinylphenol generally has a low molecular weight, in this case, after mixing, There was a problem that the physical properties of the resin deteriorate.

[0008]

[Non-Patent Document 1] Polymer 37 (26), 58.
49-5857 (1996)

[Non-Patent Document 2] Polymer 39 (26), 68.
91-6897 (1998)

[Non-Patent Document 3] Polymer 33 (4), 760.
-Page 766 (1992)

[0009]

The object of the present invention has been achieved as a result of studying the solution of the above-mentioned problems in the prior art, and the object is to achieve moldability and bleed-out resistance. To provide a resin composition excellent in heat resistance and heat resistance, and a molded article made of the resin composition.

[0010]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that a resin composition containing a polylactic acid resin, a polyacetal resin and a crystallization accelerator has the above-mentioned properties. The inventors have found that they exhibit excellent properties that match their purposes, and have reached the present invention.

That is, the resin composition of the present invention is characterized by containing a polylactic acid resin, a polyacetal resin and a crystallization accelerator.

In the resin composition of the present invention, the total of the polylactic acid resin and the polyacetal resin is 10
When the amount is 0 part by weight, the compounding amount of the crystallization accelerator is 3
0 parts by weight or less and 0.01 parts by weight or more, when the total amount of the polylactic acid resin and the polyacetal resin is 100 parts by weight, the blending amount of the polylactic acid resin is 99 parts by weight or less and 50 parts by weight or more, particularly 99 parts by weight or less and 60 parts by weight or more, the polylactic acid resin and the polyacetal resin in the resin composition are compatibilized, and the crystallization temperature at the time of temperature decrease derived from the polyacetal resin of the resin composition is
The temperature is lower than the crystallization temperature of the used polyacetal resin alone when the temperature is lowered, the polyacetal resin is a polyacetal copolymer, the crystallization accelerator is a crystal nucleating agent and / or a plasticizer, the crystal The crystallization accelerator is at least one crystal nucleating agent selected from talc, an organic carboxylic acid metal salt and an organic carboxylic acid amide, and the crystallization accelerator comprises a polyester plasticizer and a polyalkylene glycol plasticizer. At least one selected plasticizer, and the crystallization accelerator is selected from a copolymer of polylactic acid and an aliphatic polyester plasticizer or a copolymer of polylactic acid and a polyalkylene glycol plasticizer. It is preferable that all of them are at least one kind of plasticizer. By use can be expected to obtain a more excellent effect.

The molded article of the present invention is characterized by comprising any of the resin compositions described above.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.

The polylactic acid resin used in the present invention is L
-A polymer having lactic acid and / or D-lactic acid as a main component, but may contain a copolymerization component other than lactic acid. Specific examples of the other monomer units here include ethylene glycol, propylene glycol, butanediol, heptanediol, hexanediol,
Octanediol, nonanediol, decanediol,
Glycol compounds such as 1,4-cyclohexanedimethanol, neopentyl glycol, glycerin, pentaerythritol, bisphenol A, polyethylene glycol, polypropylene glycol and polytetramethylene glycol, oxalic acid, adipic acid, sebacic acid, azelaic acid, dodecane Dionic acid, malonic acid, glutaric acid, cyclohexanedicarboxylic acid, terephthalic acid,
Dicarboxylic acids such as isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, bis (p-carboxyphenyl) methane, anthracene dicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, 5-sodium sulfoisophthalic acid and 5-tetrabutylphosphonium isophthalic acid , Hydroxycarboxylic acids such as glycolic acid, hydroxypropionic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxycaproic acid and hydroxybenzoic acid, caprolactone, valerolactone, propiolactone, undecalactone and 1,5-oxepane-2-one Examples thereof include lactones. The content of such a copolymerization component is preferably 30 mol% or less, and more preferably 10 mol% or less, based on the total monomer components.

In the present invention, from the viewpoint of compatibility, it is preferable to use a polylactic acid resin in which the lactic acid component has a high optical purity. That is, in the total lactic acid component of the polylactic acid resin, L-form is contained in 70% or more, or D-form is contained in 70% or more, and L-form is contained in 80% or more.
Alternatively, it is particularly preferable that the D-form is 80% or more, and the L-form is 90% or more, or the D-form is 90% or more.
% Or more, more preferably 98% or more in the L form or 98% or more in D form. Moreover, the upper limit of the content of the L-form or D-form is usually 100% or less.

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.

The molecular weight and molecular weight distribution of the polylactic acid resin are not particularly limited as long as it can be substantially molded, but the weight average molecular weight is usually 10,000 or more, preferably 40,000 or more, Further, it is desirable that it is 80,000 or more. The weight average molecular weight as referred to herein means a polymethylmethacrylate (PMMA) -equivalent molecular weight measured by gel permeation chromatography.

The melting point of the polylactic acid resin is not particularly limited, but it is preferably 120 ° C. or higher, more preferably 150 ° C. or higher, and particularly preferably 160 ° C. or higher.

The polyacetal resin used in the present invention is a polymer having an oxymethylene unit as a main repeating unit, and is obtained by a polymerization reaction of formaldehyde or trioxane as a main raw material, a so-called polyacetal homopolymer, or mainly from an oxymethylene unit. And may be any so-called polyacetal copolymer containing 15% by weight or less of an oxyalkylene unit having 2 to 8 adjacent carbon atoms in the main chain, and a copolymer containing another structural unit, that is, It may be a block copolymer, a terpolymer or a cross-linked polymer, and these may be used alone or in combination of two or more, but from the viewpoint of thermal stability, a polyacetal copolymer is preferable.

The method for producing the polyacetal resin in the present invention is not particularly limited, and the polyacetal resin can be produced by a known method. As an example of a typical method for producing a polyacetal homopolymer, high-purity formaldehyde is introduced into an organic solvent containing an organic amine, an organic or inorganic tin compound, or a basic polymerization catalyst such as a metal hydroxide. Polymerization, the polymer is separated by filtration, and then heated in acetic anhydride in the presence of sodium acetate to acetylate the polymer terminal, and the like.

Further, as a typical method for producing a polyacetal copolymer, high-purity trioxane and a copolymerization component such as ethylene oxide and 1,3-dioxolane are introduced into an organic solvent such as cyclohexane to prepare boron trifluoride. After a cationic polymerization using a Lewis acid catalyst such as a diethyl ether complex, the catalyst is deactivated and the end groups are stabilized, or in a self-cleaning stirrer without using any solvent. To, after introducing the trioxane, the copolymerization component and the catalyst to perform bulk polymerization,
Further, a method of producing by decomposing and removing the unstable terminal can be mentioned.

The viscosity of these polyacetal resins is not particularly limited as long as it can be used as a molding material, but the melt index (MI) according to the ASTM D1238 method can be measured at a temperature of 190 ° C.
MI measured with a load of 2.16 Kg is 1.0 to 50 g / 1
It is preferably in the range of 0 minutes, and is 1.5 to 35.
It is particularly preferable that it is g / 10 minutes.

As the polyacetal resin, it is preferable to use a resin containing a heat stabilizer and a generated gas scavenger in advance, and 2,2'-methylenebis (4-)
Methyl-6-t-butylphenol), calcium ricinolate, cyanoguanazine, hexamethylenebis (3,5-t-butyl-4-hydroxyhydrocyanate), melamine-formaldehyde resin, nylon 6/66, nylon 66/610 / 6, nylon 612
/ 6, tetrakis [methylene (3,5-di-t-butyl-4-hydroxyhydrocyanate)] methane, 1,
6-hexanediol bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol [3- (3,5-di-t-butyl-5-methyl-4-) Hydroxyphenyl) propionate] is preferably contained.

Formaldehyde, which has a high possibility of exerting a strong influence on the characteristics of the composition itself, such as impairing the durability of the composition by promoting the decomposition of the polyacetal resin, is used at most 500 times as much as the polyacetal resin.
It is preferable to keep it at less than ppm, further 250
It is preferable to keep it below ppm, and further 10
It is preferable to keep it below 0 ppm. In order to achieve such a formaldehyde content, as described above, after the polymerization of the polyacetal homopolymer, the polymer terminal is acetylated, or after the polyacetal copolymer is polymerized, the unstable terminal is decomposed and removed by a stabilizing treatment. It is preferable to use the polyacetal resin obtained by the above. Formaldehyde content in the resin composition,
1 g of powder obtained by crushing the resin composition is treated with 100 m of water.
It can be measured by stirring formaldehyde in 50.degree. C. for 6 hours at 50.degree. C., extracting formaldehyde, and quantifying it by the acetylacetone method.

The crystallization accelerator used in the present invention can be selected from a wide variety of compounds, but a crystal nucleating agent that promotes the formation of crystal nuclei of a polymer or a polymer that is softened to facilitate movement and to grow crystals. A plasticizer that promotes the above can be preferably used.

The compounding amount of the crystallization accelerator used in the present invention is 1 in total of the polylactic acid resin and the polyacetal resin.
When the amount is 00 parts by weight, the amount is preferably 30 parts by weight or less and 0.01 parts by weight or more, and 20 parts by weight or less 0.05.
It is more preferably at least 10 parts by weight, still more preferably at most 10 parts by weight and at most 0.1 parts by weight, still more preferably at most 5 parts by weight and at least 0.1 parts by weight.

As the crystal nucleating agent used as a crystallization accelerator in the present invention, those generally used as a polymer crystal nucleating agent can be used without particular limitation. Either can be used. Specific examples of the inorganic crystal nucleating agent include talc, kaolinite, montmorillonite, synthetic mica, clay,
Examples thereof include zeolite, silica, graphite, carbon black, zinc oxide, magnesium oxide, titanium oxide, calcium sulfide, boron nitride, calcium carbonate, barium sulfate, aluminum oxide, neodymium oxide, and metal salts of 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, and 5 μm
The following is more preferable, and 3 μm or less is particularly preferable.

Specific examples of the organic crystal nucleating agent 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, myristic acid Sodium, potassium myristate, calcium myristate, sodium octacosanate, calcium octacosanate, sodium stearate, potassium stearate, lithium stearate, calcium stearate, magnesium stearate, barium stearate, sodium montanate, calcium montanate, toluyl Sodium acid, sodium salicylate, potassium salicylate, zinc salicylate, aluminum dibenzoate, potassium Organic carboxylic acid metal salts such as dibenzoate, lithium dibenzoate, sodium β-naphthalate, sodium cyclohexanecarboxylate, sodium p-toluenesulfonate, organic sulfonates such as sodium sulfoisophthalate, lauric acid amide, stearic acid amide, Organic carboxylic acid amides such as ethylenebislauric acid amide, ethylenebisstearic acid amide, palmitic acid amide, hydroxystearic acid amide, erucic acid amide, trimesic acid tris (t-butylamide), terephthalic acid dianilide, low density polyethylene, high density Polyethylene, polypropylene, polyisopropylene, polybutene, poly-4-methylpentene, poly-3-methylbutene-1, polyvinylcycloalkane, polyvinyltriaki Polymers such as silane, high melting point polylactic acid, sodium salt of ethylene-acrylic acid or methacrylic acid copolymer, styrene-
Sodium salt or potassium salt of polymer having carboxyl group such as sodium salt of maleic anhydride copolymer (so-called ionomer), benzylidene sorbitol and its derivatives, sodium-2,2'-methylenebis (4,6-di-t-butyl) Examples thereof include phosphorus compound metal salts such as phenyl) phosphate, and 2,2-methylbis (4,6-di-t-butylphenyl) sodium.

As the crystal nucleating agent used in the present invention, among those exemplified above, at least one selected from talc, organic carboxylic acid metal salt and organic carboxylic acid amide is particularly preferable. As a preferable talc, there can be mentioned talc having an average particle size of 0.5 to 7 μm and a ratio of SiO 2 and MgO in a component excluding a loss during combustion of 93% by weight or more. The crystal nucleating agent used in the present invention may be a single type or a combination of two or more types.

The compounding amount of the crystal nucleating agent is 100 parts by weight of the polylactic acid resin and the polyacetal resin in total.
The range of 0.01 to 30 parts by weight is preferable, and 0.05 to 1
The range of 0 parts by weight is more preferable, and the range of 0.1 to 5 parts by weight is further preferable. In particular, when an inorganic crystal nucleus material is used, it is preferably in the range of 0.1 to 5 parts by weight from the viewpoint of the effect as a crystal nucleus material, and from talc, an organic carboxylic acid metal salt and an organic carboxylic acid amide. Even when using at least one selected crystal nucleus material, 0.1 to 5
It is preferably part by weight.

As the plasticizer used in the present invention, those generally well known can be used. Examples thereof include polyester plasticizers, glycerin plasticizers, polycarboxylic acid ester plasticizers and phosphoric acid esters. Examples thereof include plasticizers, polyalkylene glycol plasticizers and epoxy plasticizers.

Specific examples of the polyester plasticizer include:
Acid components such as adipic acid, sebacic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, and propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, ethylene Examples thereof include polyesters composed of diol components such as glycol and diethylene glycol, polyesters composed of hydroxycarboxylic acid such as polycaprolactone, and the like. These polyesters may be end-capped with a monofunctional carboxylic acid or monofunctional alcohol, or may be end-capped with an epoxy compound or the like.

Specific examples of the glycerin-based plasticizer include glycerin monoacetomonolaurate, glycerin diacetomonolaurate, glycerin monoacetomonostearate, glycerin diacetomonooleate and glycerin monoacetomonomonate. .

Specific examples of the polycarboxylic acid type plasticizer include phthalic acid esters such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate, diheptyl phthalate, dibenzyl phthalate and butylbenzyl phthalate. Tributyl trimellitate, trioctyl trimellitate, trihexyl trimellitate, and other trimellitic acid esters, diisodecyl adipate, sebacic acid esters such as n-octyl-n-decyl adipate adipic acid, triethyl acetylcitrate, and acetyl citrate. Examples include citric acid esters such as tributyl acid, azelaic acid esters such as di-2-ethylhexyl azelate, dibutyl sebacate, and sebacic acid esters such as di-2-ethylhexyl sebacate. That.

Specific examples of the phosphate ester plasticizer include phosphorus such as tributyl phosphate, tri-2-ethylhexyl phosphate, trioctyl phosphate, triphenyl phosphate, diphenyl-2-ethylhexyl phosphate and tricresyl phosphate. Examples thereof include acid esters and aliphatic or aromatic condensed phosphoric acid esters.

Specific examples of the polyalkylene glycol type plasticizer include polyethylene glycol, polypropylene glycol, poly (ethylene oxide / propylene oxide) block and / or random copolymer, polytetramethylene glycol, ethylene oxide addition polymer of bisphenols. , Propylene oxide addition polymers of bisphenols, polyalkylene glycols such as bisphenol tetrahydrofuran addition polymers or their terminal epoxy modified compounds, terminal ester modified compounds, and terminal blocking compounds such as terminal ether modified compounds. .

The epoxy plasticizer generally refers to an epoxy triglyceride composed of an alkyl epoxy stearate and soybean oil. In addition, a so-called epoxy-based plasticizer mainly containing bisphenol A and epichlorohydrin is used. Epoxy resins can also be used.

Specific examples of other plasticizers include benzoic acid esters of aliphatic polyols such as neopentyl glycol dibenzoate, diethylene glycol dibenzoate and triethylene glycol di-2-ethylbutyrate, and fatty acid amides such as stearic acid amide. , Aliphatic carboxylic acid esters such as butyl oleate, methyl acetylricinoleate, oxyacid esters such as butyl acetylricinoleate, pentaerythritol, various sorbitols, polyacrylic acid esters, polycarboxylic acid vinyl esters, silicone oils, and paraffins And so on.

The molecular weight of the plasticizer used in the present invention is 10
It is preferably 0 or more and 30,000 or less, more preferably 500 or more and 20,000 or less, and particularly preferably 1000 or more and 10,000 or less.

Further, a block or graft copolymer of the above plasticizer with polylactic acid or polyacetal can also be usefully used as the plasticizer.

Among the above-exemplified plasticizers, at least one selected from polyester plasticizers and polyalkylene glycol plasticizers is particularly preferable as the plasticizer used in the present invention. Further, at least one selected from a copolymer of polylactic acid and an aliphatic polyester plasticizer or a copolymer of polylactic acid and a polyalkylene glycol plasticizer can also be preferably used. The plasticizer used in the present invention may be a single type or a combination of two or more types.

The amount of the plasticizer blended is 0. 0 with respect to 100 parts by weight of the total of the polylactic acid resin and the polyacetal resin.
The range of 01 to 30 parts by weight is preferable, the range of 0.1 to 20 parts by weight is more preferable, the range of 0.5 to 10 parts by weight is further preferable, and the range of 0.1 to 5 parts by weight is further preferable. .

In the present invention, the crystal nucleating agent and the plasticizer may be used alone, but it is preferable to use both in combination. Among them, at least one selected from talc, metal salt of organic carboxylic acid, organic carboxylic acid amide, polyester plasticizer, polyalkylene glycol plasticizer, copolymer of polylactic acid and aliphatic polyester plasticizer, polylactic acid And at least one selected from copolymers of polyalkylene glycol-based plasticizers are preferably used in combination.

The present invention is characterized in that a resin composition having excellent moldability, bleed-out resistance and heat resistance can be obtained, but the characteristics exhibited by the composition of the polylactic acid and the polyacetal resin are different. That is, when the total amount of the polylactic acid resin and the polyacetal resin is 100 parts by weight, a resin composition containing not less than 99 parts by weight of the polylactic acid resin and not less than 50 parts by weight, particularly not less than 99 parts by weight and not less than 60 parts by weight, , Is useful in improving the properties of polylactic acid resin, and this resin composition is particularly effective in improving moldability, bleed-out resistance and heat resistance. In addition, this composition may be biodegradable by taking advantage of the characteristics of polylactic acid.

Further, when the total amount of the polylactic acid resin and the polyacetal resin is 100 parts by weight, a resin containing 99 parts by weight or less of the polyacetal resin and 50 parts by weight or more, and particularly 99 parts by weight or more and 60 parts by weight or more of the polyacetal resin. In the composition, it is possible to improve the properties of the polyacetal resin, and it is particularly effective in improving the processability and flexibility.

In the resin composition of the present invention, it is preferable that the polylactic acid resin and the polyacetal resin are compatibilized. "Compatibilization" as used herein is used to describe the formation of a mixture of polymers that forms a homogeneous phase within the amorphous phase at the molecular level. That is, if one or both of the formulations form both crystalline and amorphous phases,
Compatibility means that the amorphous phases are mixed at the molecular level.

The determination of compatibility in a formulation can be done in several ways. The most common method for judging compatibility is the glass transition temperature.
In compatible formulations, the glass transition temperature varies from that of each alone and often exhibits a single glass transition temperature. As a method for measuring the glass transition temperature, either a method of measuring with a differential scanning calorimeter (DSC) or a method of measuring with a dynamic viscoelasticity test can be used.

However, since the polyacetal resin is highly crystalline, there is a problem that the glass transition temperature becomes unclear when the content of the polyacetal resin is large. In this case, the crystallization temperature of the polyacetal resin can be used to judge the compatibility. That is,
This is because when the polyacetal resin forms a compatible blend with a resin having a slower crystallization rate than itself, the crystallization rate of the polyacetal resin is lower than that of a single substance. Therefore, this decrease in the crystallization rate can be judged by the crystallization temperature at the time of temperature decrease measured by DSC.

For example, Polymer 38 (25),
6135-6143 (1997) reported that blends of aliphatic polyester poly (3-hydroxybutyrate) and polymethylene oxide (polyacetal) were incompatible, but in this case DSC
It is shown that the crystallization temperature of the polyacetal in the composition when measured in 1. is almost the same as the crystallization temperature of the polyacetal alone.

On the other hand, Non-Patent Document 3 reports that the polyacetal and the polyvinylphenol are compatible with each other. In this case, the crystallization temperature of the polyacetal in the composition when the temperature is lowered is that of the polyacetal alone. It has been shown to decrease compared to the crystallization temperature.

In the resin composition of the present invention, the crystallization temperature of the polyacetal resin in the resin composition when the temperature is lowered is lower than the crystallization temperature of the polyacetal resin alone. The preferred reduction in crystallization temperature depends on the composition. Then, this crystallization temperature tends to decrease more as the optical purity of the polylactic acid resin used increases.

When the total amount of the polylactic acid resin and the polyacetal resin is 100 parts by weight, DSC of 99 parts by weight or less and more than 60 parts by weight of polylactic acid resin and 1 part by weight or more and less than 40 parts by weight of polyacetal resin are blended. Therefore, the decrease in the crystallization temperature of the polyacetal resin measured at a temperature lowering rate of 20 ° C./min is preferably 5 ° C. or higher, more preferably 7 ° C. or higher, and particularly preferably 10 ° C. or higher. When the total amount of the polylactic acid resin and the polyacetal resin is 100 parts by weight, the polylactic acid resin 60-
When 40 parts by weight and 40 to 60 parts by weight of the polyacetal resin are blended, the decrease in the crystallization temperature of the polyacetal resin measured by DSC at a temperature decrease rate of 20 ° C./min is 2
It is preferably at least 0 ° C, more preferably at least 4 ° C. When the total amount of polylactic acid resin and polyacetal resin is 100 parts by weight, when less than 40 parts by weight of polylactic acid resin and 1 part by weight or more and more than 60 parts by weight of polyacetal resin and 99 parts by weight or less are blended, the temperature decrease rate by DSC The decrease in the crystallization temperature of the polyacetal resin measured at 20 ° C./min is preferably 0.2 ° C. or higher,
It is more preferably 0.5 ° C. or higher, particularly preferably 1 ° C. or higher.

Also, when films are made from compatible formulations, optically transparent films are obtained, whereas films made from incompatible formulations are generally opaque. Therefore, this method can also be used as a determination of compatibility. However, when a crystalline resin is used, it may become opaque due to crystallization. Therefore, the fact that the film is opaque does not mean that the film is incompatible. When the content of the polylactic acid resin is relatively large, is effective for determining compatibility.

For example, in the region where the polylactic acid resin content is high in the resin composition of the present invention, a substantially transparent film having a film thickness of about 100 μm can be formed by rapid cooling to 0 ° C., for example. , Moreover, the film thickness 100
It is possible to form a film having a light transmittance of 90% or more in μm.

Further, the substantially transparent film thus obtained is characterized by excellent toughness and post-processability such as stretching because of the large amount of the compatibilized polymer. The same applies to other molded articles such as fibers.

For the resin composition of the present invention, fillers (glass fiber, carbon fiber, natural fiber, organic fiber, ceramic fiber, ceramic beads, asbestos, wollastonite, Talc, clay, mica, sericite, zeolite, bentonite, dolomite, kaolin, fine silicic acid, feldspar powder,
Potassium titanate, shirasu balloon, calcium carbonate,
Magnesium carbonate, barium sulfate, calcium oxide, aluminum oxide, titanium oxide, aluminum silicate, silicon oxide, gypsum, Novacrite, dawsonite, clay, wood powder, paper powder, etc.), stabilizers (antioxidants, UV absorbers, etc.) , Lubricants, release agents, flame retardants (bromine flame retardants, phosphorus flame retardants, antimony compounds, melamine compounds, etc.),
Coloring agents including dyes and pigments can be added.

With respect to the resin composition of the present invention, other thermoplastic resins (for example, polyolefin, polyamide, acrylic resin, polyphenylene sulfide resin, polyether ether ketone resin, etc.) may be used as long as the object of the present invention is not impaired. Polyesters, polysulfones, polyphenylene oxides, polyimides and polyetherimides) and thermosetting resins (eg phenolic resins, melamine resins, polyester resins, silicone resins and epoxy resins), and soft thermoplastic resins (eg ethylene / glycidyl methacrylate) Polymer, ethylene / propylene terpolymer, soft polyolefin polymer such as ethylene / butene-1 copolymer, polyester elastomer and polyamide elastomer) It is possible to further contain a least.

The resin composition of the present invention has a unique property and can be processed into various molded articles by a method such as injection molding or extrusion molding. The mold temperature for injection molding is, from the viewpoint of crystallization,
30 ° C or higher is preferable, 60 ° C or higher is more preferable, and 7
0 ° C or higher is more preferable, from the viewpoint of deformation of the test piece, 140 ° C or lower is preferable, 120 ° C or lower is more preferable, and 110 ° C or lower is further preferable.

Examples of molded articles made of the resin composition of the present invention include injection molded articles, extrusion molded articles, blow molded articles, films, fibers and sheets. In the case of films, unstretched, uniaxially stretched, In the case of fibers, various films such as biaxially drawn films can be used as various fibers such as undrawn yarn, drawn yarn and super drawn yarn.

The molded products, films and fibers of the present invention are used for electric / electronic parts (various housings, gears, gears, etc.), building members, civil engineering members, agricultural materials, automobile parts (automobile interior / exterior parts, etc.). ) And daily necessities.

[0062]

The present invention will now be described in more detail by way of examples, which should not be construed as limiting the present invention. [Examples 1 to 13 and Comparative Examples 1 to 11] Content of D body is 2
%, Poly L lactic acid resin having a weight average molecular weight of 170,000 in terms of PMMA, ASTM D1238 method, load 2.
A polyacetal copolymer having a melt index value of 27 g / 10 minutes measured at 16 Kg and 190 ° C. and a melting point of 170 ° C. (Amylas S73 manufactured by Toray Industries, Inc.
1) and various crystallization accelerators shown in Table 1, respectively.
Further, the resin compositions were obtained by mixing at the ratios shown in Table 2 and melt-kneading with a uniaxial extruder having a diameter of 40 mm at a temperature of 210 ° C. and a rotation speed of 50 rpm.

The contents of the crystallization accelerator used here are as follows.

A-1: Polyethylene glycol (Katayama Chemical Co., Ltd., molecular weight 2000) A-2: Polybutylene adipate (Sanyo Chemical Co., Ltd., molecular weight 1000) A-3: Neopentyl glycol dibenzoate (Katayama Chemical Co., Ltd.) A -4: Polyoxyethylene oxypropylene block copolymer (manufactured by Asahi Denka Co., Ltd., Pluronic F68) A-5: Polyethylene glycol-polylactic acid block copolymer B-1: Talc (manufactured by Fuji Talc Co., LMS300, average particle size) 1.4 μm) B-2: Synthetic mica (ME-10 manufactured by Corp Chemical)
0, average particle size 6 μm) B-3: Barium stearate (Katayama Chemical Co., Ltd.) B-4: Ethylenebislauric acid amide (Nippon Kasei Co., Sripax L) Incidentally, A-5 polyethylene glycol-polylactic acid block. The copolymer was produced by the method of Production Example 1 below. (Production Example 1) 71 parts by weight of polyethylene glycol having an average molecular weight of 10,000 and 29 parts by weight of L-lactide were mixed with 0.025 part by weight of tin octylate at 140 ° C. in a nitrogen atmosphere in a reaction vessel equipped with a stirrer. 30 minutes, 180
Polymerization was carried out at 60 ° C. for 60 minutes to obtain a block copolymer of polyethylene glycol and polylactic acid having a polylactic acid segment having an average molecular weight of 2,000.

The glass transition temperature (Tg) and the crystallization temperature (Tc) of the polyacetal resin when the temperature of the polyacetal resin was lowered were determined by using a differential scanning calorimeter (DSC) to increase and decrease the temperature by 20 ° C./min. It was measured under the conditions. The crystallization temperature of the polyacetal resin alone when the temperature was lowered was 140 ° C. The results are shown in Tables 1 and 2.

The resin composition thus obtained was injection molded under the conditions of a cylinder temperature of 210 ° C. and a mold temperature shown in Tables 1 and 2 to obtain test pieces. The tensile strength of the obtained test piece was measured according to ASTM method D638.
Thermal deformation temperature (load 0.45 MPa) according to method D648
Were measured respectively. Moreover, after heat-treating the test piece at 140 ° C. for 10 hours, the tensile strength of the test piece was measured,
The appearance of bleed-out on the surface of the test piece and the deformation of the test piece were visually observed. The results are also shown in Tables 1 and 2.

[0067]

[Table 1]

[0068]

[Table 2]

As is clear from the results shown in Tables 1 and 2, the resin composition of the present invention and the molded article made from the resin composition were
It has excellent moldability, bleed-out resistance and heat resistance.

[0070]

As described above, the resin composition of the present invention is excellent in moldability, bleed-out resistance and heat resistance, and a molded article made of this resin composition has these excellent characteristics. It can be utilized for various applications such as electric / electronic parts, building materials, civil engineering materials, agricultural materials, automobile parts and daily necessities.

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Claims (12)

[Claims] 1. A resin composition comprising a polylactic acid resin, a polyacetal resin, and a crystallization accelerator. 2. When the total amount of the polylactic acid resin and the polyacetal resin is 100 parts by weight, the compounding amount of the crystallization accelerator is 30 parts by weight or less and 0.01 parts by weight or more. Item 2. The resin composition according to item 1. 3. The compounding amount of the polylactic acid resin is 99 parts by weight or less and 50 parts by weight or more, when the total amount of the polylactic acid resin and the polyacetal resin is 100 parts by weight. The resin composition according to 2. 4. The compounding amount of the polylactic acid resin is 99 parts by weight or less and 60 parts by weight or more when the total amount of the polylactic acid resin and the polyacetal resin is 100 parts by weight. The resin composition described. 5. The resin composition according to any one of claims 1 to 4, wherein the polylactic acid resin and the polyacetal resin in the resin composition are compatibilized with each other. 6. The crystallization temperature of the resin composition derived from the polyacetal resin at the time of temperature decrease is lower than the crystallization temperature of the used polyacetal resin alone at the time of temperature decrease. The resin composition according to any one of items. 7. The resin composition according to claim 1, wherein the polyacetal resin is a polyacetal copolymer. 8. The resin composition according to any one of claims 1 to 7, wherein the crystallization accelerator is a crystal nucleating agent and / or a plasticizer. 9. The resin composition according to claim 8, wherein the crystallization accelerator is at least one crystal nucleating agent selected from talc, organic carboxylic acid metal salts and organic carboxylic acid amides. . 10. The resin composition according to claim 8, wherein the crystallization accelerator is at least one plasticizer selected from polyester plasticizers and polyalkylene glycol plasticizers. 11. The crystallization accelerator is at least one plasticizer selected from a copolymer of polylactic acid and an aliphatic polyester plasticizer or a copolymer of polylactic acid and a polyalkylene glycol plasticizer. The resin composition according to claim 8, wherein 12. A molded article comprising the resin composition according to any one of claims 1 to 11.