JP4232473B2 - Resin composition and molded article comprising the same - Google Patents

Description

【００６８】
表１の結果から明らかなように、ポリ乳酸樹脂、ポリアセタール樹脂、その他の熱可塑性樹脂の３者を含有する本発明の樹脂組成物は、比較例に示したものよりも、成形性、機械特性、耐熱性、表面外観に優れていることがわかる。
【００６９】
［実施例６〜１１、比較例８〜１６］
Ｄ体の含有量が１．２％であり、ヘキサフルオロイソプロパノールを溶媒に用いゲルパーミエーションクロマトグラフィーで測定したＰＭＭＡ換算の重量平均分子量が１６万であるポリＬ乳酸樹脂、ＡＳＴＭ法Ｄ１２３８に準じて１９０℃で測定したメルトインデックス値が９ｇ／１０分であり融点が１７０℃であるポリアセタールコポリマー（東レ社製アミラスＳ７６１）、ガラス繊維（日東紡社製３Ｊ９４８）および下記に示した各種熱可塑性樹脂を、それぞれ表２に示した割合で混合し、３０ｍｍ径の２軸押出機により、シリンダー温度２２０℃、回転数１００ｒｐｍの条件で溶融混練を行い、樹脂組成物を得た。
【００７０】
なお、表２における熱可塑性樹脂の符号は、次の内容を示すものである。
Ａ−４：ポリスチレン樹脂（旭化成社製“スタイロン”６７９）
Ａ−５：ＡＳ樹脂（旭化成社製“スタイラック”７６９）
Ａ−６：ポリカーボネート樹脂（三菱エンジニアリングプラスチック社製“ユーピロン”Ｈ４０００）
Ａ−７：セルロースアセテートプロピオネート樹脂（ダイセル化学社製“ＣＡＰ”）
得られた樹脂組成物について、差動走査熱量計（ＤＳＣ）を用い、ポリ乳酸樹脂由来のガラス転移温度（Ｔｇ）およびポリアセタール樹脂由来の降温時の結晶化温度（Ｔｃ）を、昇降温速度２０℃／分で測定した結果を表２に併せて示す。なお、その他の熱可塑性樹脂由来のガラス転移温度がある場合は、そのガラス転移温度についても記載した。
【００７１】
また、得られた樹脂組成物について、シリンダー温度２１０℃、金型温度４０℃で射出成形を行い、３．２ｍ厚の曲げ試験用の試験片を得た。このとき、試験片の変形、表面外観を目視で観察した。また、得られた試験片を用い、ＡＳＴＭＤ７９０に準じて曲げ試験を行った。また、試験片を７０℃で１２時間結晶化処理を行った後の変形を観察した、なお、試験片の変形は４段階で評価した（変形がないものを◎、若干変形があるが目視ではほとんどわからないものを○、目視で変形が確認できるものを△、変形が大きく形が変わったものを×とする）。これらの結果を表２に併せて示す。なお、表面外観の評価は以下のように４段階で行った。
４：透明感がなく、表面の荒れが少ない。
３：透明感はないが、表面の荒れが多い。
２：表面の荒れは少ないが、透明感がある。
１：透明感があり、表面の荒れが多い。
【００７２】
【表２】

【００７３】
表２の結果から明らかなように、ポリ乳酸樹脂、ポリアセタール樹脂、その他の熱可塑性樹脂の３者を含有する本発明の樹脂組成物は、比較例に示したものよりも、成形性、機械特性、耐熱性、表面外観、寸法安定性に優れていることがわかる。
【００７４】
【発明の効果】
以上説明したように、本発明の樹脂組成物は、優れた成形性、機械特性、耐熱性、表面外観、寸法安定性を有するものであり、この樹脂組成物からなる本発明の成形品は、上記の特性を生かして、電気・電子部品、建築土木部材、自動車部品、農業資材、包装材料、衣料および日用品など各種用途に有効に利用することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention is a resin composition excellent in moldability, mechanical properties, heat resistance, surface appearance, and dimensional stability, comprising polylactic acid resin, polyacetal resin, and other thermoplastic resins (excluding acrylic resin). And a molded article made of the same.
[0002]
[Prior art]
Polylactic acid resin is expected as a practically excellent biodegradable polymer because it has a high melting point and can be melt-molded. In the future, it is also expected to be used as a general-purpose polymer made from bio raw materials. However, since the polylactic acid resin has a low crystallization rate, there is a limit to crystallization and use as a molded product. For example, when polylactic acid resin is injection-molded, it requires a long molding cycle time and heat treatment after molding, and it has practically great heat resistance and dimensional stability such as large deformation during molding and heat treatment. There was a problem. Further, since the polylactic acid resin has a low crystallization speed, the surface appearance of the obtained molded product, in particular, the texture was inferior.
In particular, in order to use for various design parts, it is necessary to improve the texture.
[0003]
Polyacetal resin, on the other hand, is widely used as an injection-molded product because of its excellent balance of mechanical properties and moldability, but even higher dimensional stability is achieved when fibrous reinforcement is used. Was requested. In addition, since polyacetal resin has a large specific gravity, it is necessary to reduce the specific gravity in order to use it widely in automobile parts and the like.
[0004]
The technique of blending and using 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, when two or more kinds of polymers are mixed, in many cases, the dispersibility between the polymers is poor, and the polymer cannot be processed into the shape of a pellet or a molded product, or tends to exhibit inferior characteristics. This tendency is particularly remarkable in polyacetal.
[0005]
However, in rare cases, two types of polymers may form a uniform amorphous phase, and this type is generally expected to exhibit excellent properties as a compatible or miscible polymer alloy. There are few.
[0006]
Polyethylene glycol (for example, see Non-Patent Document 1) and polymethyl methacrylate (for example, see Non-Patent Document 2) are known as polymers compatible with polylactic acid resin, but when these polymers are mixed However, there is a problem that the strength and crystallinity of the polylactic acid resin are greatly reduced.
[0007]
Moreover, as a polymer compatible with polyacetal, only polyvinylphenol (for example, see Non-Patent Document 3) is known. However, since polyvinylphenol generally has a low molecular weight, the resin physical properties after mixing are reduced. There was a problem.
[0008]
Patent Document 1 discloses a resin composition containing an aliphatic polyester and a small amount of formaldehyde for the purpose of imparting biodegradability to polyacetal. Among them, as an example of aliphatic polyester, various aliphatic compounds are disclosed. Although the example of use of polylactic acid is disclosed with polyester, in the invention described in the publication, the problems of the polylactic acid resin and polyacetal resin described above cannot be solved. In the invention described in the publication, polylactic acid is treated in the same manner as other aliphatic polyesters, and no special recognition is made regarding the compatibility with polyacetal.
[0009]
[Non-Patent Document 1]
Polymer 37 (26), 5849-5857 (1996).
[Non-Patent Document 2]
Polymer 39 (26), pages 6891-6897 (1998)
[Non-Patent Document 3]
Polymer 33 (4), pages 760-766 (1992)
[Patent Document 1]
Japanese Patent Application Laid-Open No. 5-43772 (page 2, example)
[0010]
[Problems to be solved by the invention]
The present invention has been achieved as a result of studying the solution of the problems in the prior art described above as an issue.
[0011]
Accordingly, an object of the present invention is to provide a resin composition excellent in moldability, mechanical properties, heat resistance, surface appearance, and dimensional stability, and a molded product comprising the same.
[0012]
[Means for Solving the Problems]
The present inventors have found that a resin composition containing a polylactic acid resin, a polyacetal resin, and other thermoplastic resins (excluding an acrylic resin) has excellent characteristics that meet the above-mentioned purpose. The invention has been reached.
[0013]
That is, the present invention includes polylactic acid resin, polyacetal resin, and other thermoplastic resins selected from polyethylene resin, polypropylene resin, aliphatic polyketone resin, polystyrene resin, acrylonitrile-styrene resin, polycarbonate resin and cellulose ester resin. It provides the resin composition characterized by including.
[0014]
In the resin composition of the present invention,
When the total of the polylactic acid resin and the polyacetal resin is 100 parts by weight, the content of the polylactic acid resin is 99 parts by weight or less and 50 parts by weight or more,
When the total of the polylactic acid resin and the polyacetal resin is 100 parts by weight, the content of the polyacetal resin is 99 parts by weight or less and more than 50 parts by weight,
When the total of the polylactic acid resin and the polyacetal resin is 100 parts by weight, the content of the other thermoplastic resin is 100 parts by weight or less, 1 part by weight or more,
The polylactic acid resin and the polyacetal resin in the resin composition are compatible,
The polyacetal resin is a polyacetal copolymer ;
Further containing a reinforcing material, and
The polylactic acid resin is a polylactic acid resin containing 98% or more of L-form or 98% or more of D-form among total lactic acid components,
However, all are mentioned as preferable conditions, and when these conditions are applied, acquisition of a more excellent effect can be expected.
[0015]
The molded article of the present invention is characterized by comprising the above resin composition.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
[0017]
The polylactic acid resin used in the present invention is a polymer mainly composed of L-lactic acid and / or D-lactic acid, but may contain other copolymerization components other than lactic acid. Other copolymerization components include ethylene glycol, propylene glycol, butanediol, heptanediol, hexanediol, octanediol, nonanediol, decanediol, 1,4-cyclohexanedimethanol, neopentylglycol, glycerin, Glycol compounds such as pentaerythritol, bisphenol A, polyethylene glycol, polypropylene glycol and polytetramethylene glycol, oxalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, malonic acid, glutaric acid, cyclohexanedicarboxylic acid Acid, terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, bis (p-carboxyphenyl) methane, anthracene dicarboxylic acid, 4,4'-diphenyl ether 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. As such a copolymer component, it is preferable to set it as content of 30 mol% or less normally in all the monomer components, and it is preferable that it is 10 mol% or less.
[0018]
In the present invention, it is preferable to use a polylactic acid resin having a high optical purity of the lactic acid component from the viewpoint of compatibility. That is, among the total lactic acid components of the polylactic acid resin, it is preferable that the L isomer is contained at 80% or more, or the D isomer is contained at 80% or more, the L isomer is contained at 90% or more, or the D isomer is 90% or more. It is particularly preferable that the L-form is contained at 95% or more, or the D-form is more preferably contained at 95% or more, the L-form is contained at 98% or more, or the D-form is contained at 98% or more. Further preferred. Moreover, the upper limit of the content of L-form or D-form is usually 100% or less.
[0019]
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, and further 80,000. The above is desirable. The weight average molecular weight here refers to the molecular weight in terms of polymethyl methacrylate (PMMA) measured by gel permeation chromatography.
[0020]
The melting point of the polylactic acid resin is not particularly limited, but is preferably 120 ° C. or higher, more preferably 150 ° C. or higher, and particularly preferably 160 ° C. or higher. The melting point of the polylactic acid resin is usually increased by increasing the optical purity of the lactic acid component, and the polylactic acid resin having a melting point of 120 ° C. or higher contains 90% or more of the L form or 90% or more of the D form. In addition, the polylactic acid resin having a melting point of 150 ° C. or higher contains 95% or more of the L isomer or 95% or more of the D isomer, and the polylactic acid resin having a melting point of 160 ° C. or higher Can be obtained by containing 98% or more of D or 98% or more of D-form.
[0021]
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.
[0022]
The polyacetal resin used in the present invention is a polymer having an oxymethylene unit as a main repeating unit, and is mainly composed of a so-called polyacetal homopolymer obtained by a polymerization reaction using formaldehyde or trioxane as a main raw material, and mainly an oxymethylene unit. It may be any so-called polyacetal copolymer containing 15% by weight or less of oxyalkylene units having 2 to 8 adjacent carbon atoms in the chain, and also a copolymer containing other structural units, ie a block copolymer, a terpolymer Either a polymer or a crosslinked polymer may be used, and these may be used alone or in combination of two or more. From the viewpoint of thermal stability, a polyacetal copolymer is preferable.
[0023]
There is no restriction | limiting in particular about the manufacturing method of the polyacetal resin in this invention, It can manufacture by a well-known method. As an example of a typical method for producing a polyacetal homopolymer, high-purity formaldehyde is introduced into an organic solvent containing a basic polymerization catalyst such as an organic amine, an organic or inorganic tin compound, or a metal hydroxide. Examples thereof include a method of polymerizing and filtering the polymer, followed by heating in acetic anhydride in the presence of sodium acetate to acetylate the polymer terminal.
[0024]
Further, as an example of a typical method for producing a polyacetal copolymer, a high purity trioxane and a copolymer component such as ethylene oxide and 1,3-dioxolane are introduced into an organic solvent such as cyclohexane, and boron trifluoride diethyl ether is used. After cationic polymerization using a Lewis acid catalyst such as a complex, a method of manufacturing by deactivating the catalyst and stabilizing the end groups, or into a self-cleaning stirrer without using any solvent Examples thereof include a method in which trioxane, a copolymerization component and a catalyst are introduced and bulk polymerization is performed, and then the unstable terminal is further decomposed and removed.
[0025]
The viscosity of these polyacetal resins is not particularly limited as long as it can be used as a molding material, but melt index (MI) can be measured by the ASTM D1238 method, and MI measured at a temperature of 190 ° C. and a load of 2.16 kg. Is preferably in the range of 1.0 to 50 g / 10 min, particularly preferably in the range of 1.5 to 35 g / 10 min.
[0026]
Further, as the polyacetal resin, it is preferable to use a resin containing a heat stabilizer or a generated gas scavenger in advance, and 2,2′-methylenebis (4-methyl-6-tert-butylphenol), calcium ricinolate, Cyanoguanazine, hexamethylene bis (3,5-t-butyl-4-hydroxyhydrocyanate), melamine, melamine-formaldehyde resin, nylon 6/66, nylon 66/610/6, nylon 612/6, tetrakis [methylene ( 3,5-di-tert-butyl-4-hydroxyhydrocyanate)] methane, 1,6-hexanediol bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], tri Ethylene glycol [3- (3,5-di-tert-butyl-5-methyl-4-hydro It is preferred that at least one of xylphenyl) propionate] is contained.
[0027]
In addition, it is preferable not to add formaldehyde which has a high possibility of strongly affecting the properties of the composition itself, such as impairing the durability of the composition by promoting the decomposition of the polyacetal resin, but it is included in the polyacetal resin. Considering the amount of formaldehyde, it is preferable that the polyacetal resin is kept at less than 500 ppm at most, more preferably less than 250 ppm, and further preferably less than 100 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 polymerization of the polyacetal copolymer, the unstable terminal is decomposed and removed. It is preferable to use a polyacetal resin subjected to the above. The formaldehyde content in the resin composition is determined by stirring 1 g of powder obtained by pulverizing the resin composition in 100 ml of water at 50 ° C. for 6 hours, extracting formaldehyde, and quantifying it by the acetylacetone method. Can be measured.
[0028]
Examples of other thermoplastic resins used in the present invention include crystalline thermoplastic resins such as polyethylene resins, polypropylene resins, and aliphatic polyketone resins.
[0031]
Preferred crystalline thermoplastic resins include polyethylene resins, polypropylene resins, and aliphatic polyketone resins.
[0032]
When such a crystalline thermoplastic resin is used, characteristics such as a good surface appearance can be further imparted to the resin composition of the present invention.
[0033]
Examples of the amorphous thermoplastic resin include polystyrene resin, acrylonitrile-styrene resin, polycarbonate resin, and cellulose ester resin (cellulose acetate resin, cellulose acetate propionate resin, and the like).
[0035]
In the present invention, by using such an amorphous thermoplastic resin, characteristics such as dimensional stability can be further imparted to the resin composition of the present invention.
[0036]
The content of the other thermoplastic resin is preferably 100 parts by weight or less and 1 part by weight or more, and 70 parts by weight or less and 3 parts by weight or more when the total of the polylactic acid resin and the polyacetal resin is 100 parts by weight. More preferably, it is particularly preferably 50 parts by weight or less and 5 parts by weight or more.
[0037]
In the present invention, a composition excellent in moldability, mechanical properties, heat resistance, surface appearance, and dimensional stability by blending polylactic acid resin, polyacetal, and other thermoplastic resins (excluding acrylic resin) Although the product is obtained, the characteristic which shows especially an effect changes with compounding compositions of a polylactic acid resin and a polyacetal resin.
[0038]
That is, when the total of the polylactic acid resin and the polyacetal resin is 100 parts by weight, in the resin composition containing 99 parts by weight or less of the polylactic acid resin, particularly 60 parts by weight or more of 99 parts by weight or less. The composition is useful in improving the properties of the polylactic acid resin, and this composition has particularly remarkable effects of improving moldability, heat resistance, surface appearance and dimensional stability. Further, this composition may be biodegradable by taking advantage of the properties of polylactic acid resin.
[0039]
On the other hand, when the total of the polylactic acid resin and the polyacetal resin is 100 parts by weight, in the resin composition containing 99 parts by weight or less of the polyacetal resin and more than 50 parts by weight, particularly 99 parts by weight or less, It is possible to improve the properties of the polyacetal resin, and in particular, it is effective for improving dimensional stability and reducing the weight.
[0040]
In the present invention, the polylactic acid resin and the polyacetal resin are usually compatible in the composition. “Compatibilization” as used herein is used to explain that both form a homogeneous phase in the amorphous phase at the molecular level. That is, when one or both of the formulations forms both a crystalline phase and an amorphous phase, compatibilization means that the amorphous phase mixes at the molecular level.
[0041]
The determination of compatibility in a formulation can be made in several ways. The most common method for judging the compatibility is a method for judging by the glass transition temperature. In compatible formulations, the glass transition temperature varies from that of each alone, often exhibiting a single glass transition temperature. As a method for measuring the glass transition temperature, any of a method of measuring by a differential scanning calorimeter (DSC) and a method of measuring by a dynamic viscoelasticity test can be used.
[0042]
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, as the compatibility judgment, the crystallization temperature of the polyacetal resin can be used. That is, when the polyacetal resin forms a compatible compound with a resin having a slower crystallization rate than the polyacetal resin itself, the crystallization rate of the polyacetal resin is lower than that of a single substance. Therefore, the decrease in the crystallization rate can be determined by the crystallization temperature at the time of temperature decrease measured by DSC.
[0043]
For example, Polymer 38 (25), 6135-6143 (1997) reported that a blend of poly (3-hydroxybutyrate) and polymethylene oxide (polyacetal), which are aliphatic polyesters, is incompatible. However, in this case, it is shown that the crystallization temperature of polyacetal in the composition measured by DSC is almost the same as the crystallization temperature of polyacetal alone.
[0044]
On the other hand, the non-patent document 3 reports that polyacetal and polyvinylphenol are compatible. In this case, the crystallization temperature of the polyacetal in the composition when the temperature is lowered is the crystallization temperature of the polyacetal alone. It is shown that it decreases compared to
[0045]
In the resin composition of the present invention, the crystallization temperature of the polyacetal resin in the resin composition when the temperature falls is lower than the crystallization temperature of the polyacetal resin alone. The preferred decrease in crystallization temperature depends on the composition. The crystallization temperature tends to decrease as the optical purity of the polylactic acid resin used increases.
[0046]
When the total amount of polylactic acid resin and polyacetal resin is 100 parts by weight, when blending 99 parts by weight or less of polylactic acid resin and 50 parts by weight or more of polyacetal resin and 1 part by weight or more and 50 parts by weight or less of polyacetal resin, the temperature lowering rate by DSC The decrease in the crystallization temperature of the polyacetal resin measured at 20 ° C./min is preferably 2 ° C. or higher, more preferably 3 ° C. or higher, and particularly preferably 4 ° C. or higher. In particular, when the total amount of polylactic acid resin and polyacetal resin is 100 parts by weight, when blending polylactic acid resin 99 parts by weight or less and more than 60 parts by weight and polyacetal resin 1 part by weight or more and less than 40 parts by weight, The decrease in the crystallization temperature of the polyacetal resin measured at a temperature decrease rate of 20 ° C./min is preferably 5 ° C. or higher, more preferably 7 ° C. or higher, and particularly preferably 10 ° C. or higher.
[0047]
When the total amount of polylactic acid resin and polyacetal resin is 100 parts by weight, when blending less than 50 parts by weight of polylactic acid resin and 1 part by weight or more and more than 50 parts by weight of polyacetal resin, the rate of temperature decrease by DSC The decrease in the crystallization temperature of the polyacetal resin measured at 20 ° C./min is preferably 0.2 ° C. or higher, more preferably 0.5 ° C. or higher, and particularly preferably 1 ° C. or higher. In particular, when the total amount of the polylactic acid resin and the polyacetal resin is 100 parts by weight, when less than 50 parts by weight of the polylactic acid resin and 40 parts by weight or more and more than 60 parts by weight of the polyacetal resin are blended, The decrease in the crystallization temperature of the polyacetal resin measured at a temperature decrease rate of 20 ° C./min is preferably 0.5 ° C. or higher, more preferably 1 ° C. or higher, and particularly preferably 2 ° C. or higher.
[0048]
When polylactic acid resin and polyacetal resin contain other thermoplastic resins other than acrylic resin, in many cases, other thermoplastic resins are not compatible with the other two resins, and polylactic acid resin And the influence of the polyacetal resin on the glass transition temperature and crystallization temperature is small.
[0049]
In the present invention, a greater effect can be obtained by simply mixing a thermoplastic resin other than an acrylic resin with a polylactic acid resin or a polyacetal resin. The cause of this is not clear, but this is considered to be due to the high compatibility between the polylactic acid resin and the polyacetal resin.
[0050]
For the resin composition of the present invention, it is preferable to further contain a reinforcing material, and the reinforcing material to be used is a fibrous, plate-like, granular or powdery material usually used for reinforcing thermoplastic resins. Can be used. Specifically, glass fiber, asbestos fiber, carbon fiber, graphite fiber, metal fiber, potassium titanate whisker, aluminum borate whisker, magnesium whisker, silicon whisker, wollastonite, sepiolite, asbestos, slag fiber, zonolite, Elastadite, gypsum fiber, silica fiber, silica-alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber and other inorganic fibrous reinforcements, polyester fiber, nylon fiber, acrylic fiber, regenerated cellulose fiber, acetate fiber, Organic fibrous reinforcements such as kenaf, ramie, cotton, jute, hemp, sisal, flax, linen, silk, Manila hemp, sugar cane, wood pulp, paper waste and wool, glass flakes, non-swellable mica, graphite, metal foil, ceramic Beads, talc, clay, mica, sericite, zeolite, bentonite, dolomite, kaolin, finely divided silicic acid, feldspar powder, potassium titanate, shirasu balloon, calcium carbonate, magnesium carbonate, barium sulfate, calcium oxide, aluminum oxide, titanium oxide And plate-like and granular reinforcing materials such as aluminum silicate, silicon oxide, gypsum, novaculite, dosonite, wood powder, paper powder and white clay. Among these reinforcing materials, inorganic fibrous reinforcing materials are preferable, and glass fiber, wollastonite, aluminum borate whisker and potassium titanate whisker are particularly preferable. The use of organic fibrous reinforcing materials is also preferable, and natural fibers and regenerated fibers are more preferable from the viewpoint of taking advantage of the biodegradability of the polylactic acid resin.
[0051]
The reinforcing material may be coated or focused with a thermoplastic resin such as an ethylene / vinyl acetate copolymer or a thermosetting resin such as an epoxy resin, or with a coupling agent such as aminosilane or epoxysilane. It may be processed.
[0052]
Further, the compounding amount of the reinforcing material is preferably 200 parts by weight or less and 0.1 parts by weight or more, more preferably 100 parts by weight or less and 0.5 parts by weight or more with respect to 100 parts by weight of the total of the polylactic acid resin and the polyacetal resin .
[0053]
As long as the object of the present invention is not impaired, stabilizers (antioxidants, light stabilizers, etc.), flame retardants (bromine flame retardants, phosphorus flame retardants, antimony compounds, melamine compounds, etc.), lubricants, mold release agents, Colorants including dyes and pigments, nucleating agents (talc, organic carboxylic acid metal salts, organic carboxylic acid amides, etc.) and plasticizers (polyester plasticizers, glycerin plasticizers, polycarboxylic acid ester plasticizers, phosphorus Acid ester plasticizers, polyalkylene glycol plasticizers, epoxy plasticizers, etc.) can be added.
[0054]
For the resin composition of the present invention, other resins (such as thermosetting resins such as phenol resin, melamine resin, polyester resin, silicone resin and epoxy resin) may be used as long as the object of the present invention is not impaired. Further, it can be contained.
[0055]
The method for producing the resin composition of the present invention is not particularly limited. For example, after pre-blending a polylactic acid resin, a polyacetal resin, other thermoplastic resins and other additives as necessary, A method of uniformly melting and kneading using a single-screw or twin-screw extruder above the melting point can be preferably mentioned. Alternatively, a method of melt-kneading a polylactic acid resin and a polyacetal resin in advance and then melt-kneading another thermoplastic resin and, if necessary, other additives can also be used.
[0056]
The resin composition of the present invention is a composition having unique characteristics, and can be processed and used for various molded products by a method such as injection molding or extrusion molding. The mold temperature for injection molding is preferably 30 ° C. or higher, more preferably 40 ° C. or higher, further preferably 50 ° C. or higher from the viewpoint of crystallization, and 140 ° C. or lower from the viewpoint of deformation of the test piece. Preferably, 120 ° C. or lower is more preferable, and 110 ° C. or lower is further preferable.
[0057]
Examples of the molded product of the present invention obtained from the above resin composition include injection molded products, extrusion molded products, blow molded products, films, sheets, bottles, fibers and the like, unstretched films / sheets, uniaxially stretched films, Any of various films and sheets such as a biaxially stretched film, a laminate film, and a foamed sheet, and various fibers such as an unstretched yarn, a stretched yarn, and a super-stretched yarn can be suitably used. In addition, these molded products include electrical / electronic parts (various housings, gears, gears, etc.), construction civil engineering members, automobile parts (interior / exterior parts, etc.), sliding parts, agricultural materials, packaging materials, clothing and daily necessities. It can be used for various purposes, and in particular, can be usefully used as various design parts.
[0058]
【Example】
The present invention will be described in more detail below by way of examples, but these examples do not limit the present invention.
[0059]
[Examples 1 to 5, Comparative Examples 1 to 7]
A poly-L lactic acid resin having a D-form content of 1.2% and a weight average molecular weight of 160,000 in terms of PMMA measured by gel permeation chromatography using hexafluoroisopropanol as a solvent, according to ASTM method D1238 A polyacetal copolymer having a melt index value measured at 190 ° C. and a load of 2.16 kg of 27 g / 10 min and a melting point of 170 ° C. (“Amirasu” S731 manufactured by Toray Industries, Inc.) and various crystalline thermoplastic resins shown below, Each was mixed in the ratio shown in Table 1, and melt-kneaded with a 30 mm diameter twin screw extruder under conditions of a cylinder temperature of 220 ° C. and a rotation speed of 150 rpm to obtain a resin composition.
[0060]
In addition, the code | symbol of the thermoplastic resin in Table 1 shows the following content.
A-1: Polypropylene (“Nobren” Y101, manufactured by Sumitomo Chemical Co., Ltd.)
A-2: High-density polyethylene (“Hi-Zex” 2200J manufactured by Mitsui Chemicals, Inc.)
A-3: Aliphatic polyketone (manufactured by Shell "Carillon" P1000).
[0061]
About the obtained resin composition, using a differential scanning calorimeter (DSC), the glass transition temperature (Tg) derived from the polylactic acid resin and the crystallization temperature (Tc) at the time of the temperature decrease derived from the polyacetal resin were increased and decreased by 20 The results measured at ° C./min are also shown in Table 1.
[0062]
Further, the obtained resin composition was injection-molded at a cylinder temperature of 210 ° C. and a mold temperature of 60 ° C. to obtain a 3.2 mm-thick test piece for a bending test. At this time, the deformation and surface appearance of the test piece during molding were visually observed. Moreover, the bending test was done according to ASTM method D790 using the obtained test piece. Moreover, the deformation | transformation after processing the obtained test piece at 140 degreeC for 1 hour in a hot-air oven was observed visually. These results are also shown in Table 1. In addition, the deformation of the test piece was evaluated in four stages (◎ if there is no deformation, ○ if there is some deformation but hardly visible by visual inspection, △ if you can visually confirm the deformation, △ the deformation has changed greatly in shape. The surface appearance was evaluated in three stages as follows.
[0063]
A: No transparency, gloss, and excellent texture.
[0064]
○: No transparency, but pearly luster.
[0065]
Δ: The surface of the test piece is slightly transparent.
[0066]
X: The test piece is transparent or transparent and inferior in texture.
[0067]
[Table 1]

[0068]
As is clear from the results in Table 1, the resin composition of the present invention containing the three components of polylactic acid resin, polyacetal resin, and other thermoplastic resins has moldability and mechanical properties higher than those shown in the comparative examples. It can be seen that it is excellent in heat resistance and surface appearance.
[0069]
[Examples 6 to 11, Comparative Examples 8 to 16]
A poly-L lactic acid resin having a D-form content of 1.2% and a weight average molecular weight of 160,000 in terms of PMMA measured by gel permeation chromatography using hexafluoroisopropanol as a solvent, according to ASTM method D1238 A polyacetal copolymer (Amylas S761 manufactured by Toray Industries, Inc.) having a melt index value of 9 g / 10 minutes and a melting point of 170 ° C. measured at 190 ° C., glass fiber (3J948 manufactured by Nittobo Co., Ltd.), and various thermoplastic resins shown below. These were mixed in the proportions shown in Table 2, and melt kneaded with a 30 mm diameter twin screw extruder under conditions of a cylinder temperature of 220 ° C. and a rotation speed of 100 rpm to obtain a resin composition.
[0070]
In addition, the code | symbol of the thermoplastic resin in Table 2 shows the following content.
A-4: Polystyrene resin ("Styron" 679 manufactured by Asahi Kasei Corporation)
A-5: AS resin ("Stylac" 769 manufactured by Asahi Kasei Corporation)
A-6: Polycarbonate resin ("Iupilon H4000" manufactured by Mitsubishi Engineering Plastics)
A-7: Cellulose acetate propionate resin ("CAP" manufactured by Daicel Chemical Industries)
About the obtained resin composition, using a differential scanning calorimeter (DSC), the glass transition temperature (Tg) derived from the polylactic acid resin and the crystallization temperature (Tc) at the time of the temperature decrease derived from the polyacetal resin were increased and decreased by 20 The results measured at ° C./min are also shown in Table 2. In addition, when there was a glass transition temperature derived from other thermoplastic resins, the glass transition temperature was also described.
[0071]
The obtained resin composition was injection-molded at a cylinder temperature of 210 ° C. and a mold temperature of 40 ° C. to obtain a 3.2 m-thick test piece for a bending test. At this time, the deformation and surface appearance of the test piece were visually observed. Moreover, the bending test was done according to ASTM D790 using the obtained test piece. In addition, the deformation of the test piece after crystallization treatment at 70 ° C. for 12 hours was observed, and the deformation of the test piece was evaluated in four stages (A with no deformation is ◎, but there is some deformation but visually ○ for those that are almost unknown, △ for those whose deformation can be visually confirmed, and × for those whose deformation has changed greatly). These results are also shown in Table 2. The surface appearance was evaluated in four stages as follows.
4: There is no sense of transparency, and there is little surface roughness.
3: There is no transparency, but the surface is rough.
2: There is little surface roughness, but there is a sense of transparency.
1: There is a feeling of transparency and the surface is rough.
[0072]
[Table 2]

[0073]
As is clear from the results in Table 2, the resin composition of the present invention containing the three components of polylactic acid resin, polyacetal resin, and other thermoplastic resins is more moldable and mechanical than the one shown in the comparative example. It can be seen that it is excellent in heat resistance, surface appearance and dimensional stability.
[0074]
【The invention's effect】
As described above, the resin composition of the present invention has excellent moldability, mechanical properties, heat resistance, surface appearance, and dimensional stability, and the molded product of the present invention comprising this resin composition is Utilizing the above characteristics, it can be effectively used in various applications such as electric / electronic parts, building civil engineering members, automobile parts, agricultural materials, packaging materials, clothing and daily necessities.

Claims (9)

It contains polylactic acid resin, polyacetal resin, and other thermoplastic resins selected from polyethylene resin, polypropylene resin, aliphatic polyketone resin, polystyrene resin, acrylonitrile-styrene resin, polycarbonate resin and cellulose ester resin. A resin composition characterized.    2. The resin composition according to claim 1, wherein when the total of the polylactic acid resin and the polyacetal resin is 100 parts by weight, the content of the polylactic acid resin is 99 parts by weight or less and 50 parts by weight or more. .    2. The resin composition according to claim 1, wherein when the total of the polylactic acid resin and the polyacetal resin is 100 parts by weight, the content of the polyacetal resin is 99 parts by weight or less and more than 50 parts by weight.    The content of the other thermoplastic resin is 100 parts by weight or less and 1 part by weight or more when the total of the polylactic acid resin and the polyacetal resin is 100 parts by weight. 2. The resin composition according to item 1.    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.    The resin composition according to claim 1, wherein the polyacetal resin is a polyacetal copolymer.   Furthermore, a reinforcing material is contained, The resin composition of any one of Claims 1-6 characterized by the above-mentioned. The polylactic acid resin is a polylactic acid resin containing 98% or more of L-form or 98% or more of D-form among total lactic acid components. The resin composition described in 1. The molded article which consists of a resin composition of any one of Claims 1-8 .