JP2018123277A - Polylactic acid-based thermoplastic resin composition and molded article thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polylactic acid-based thermoplastic resin composition capable of giving a molded article improved in slidability, scratch resistance, wear resistance, and impact resistance, and to provide a molded article thereof.SOLUTION: The polylactic acid-based thermoplastic resin composition contains 0.3-3.5 pts.wt. of an organically modified siloxane compound (B) based on 100 pts.wt. of the total of a polylactic acid resin (A) and a rubber-reinforced resin (C). The organically modified siloxane compound (B) is a compound in which an organically modified siloxane (b-1) and a thermoplastic resin (b-2) are chemically bonded, or a mixture of the organically modified siloxane (b-1) and the thermoplastic resin (b-2). The thermoplastic resin (b-2) contains a polyolefin and/or a polyamide. The rubber-reinforced resin (C) comprises a graft copolymer (C-1) obtained by graft-polymerizing a rubbery polymer (c) with a vinyl monomer, and a copolymer (C-2). The rubbery polymer (c) contains a silicone/acrylic composite rubber.SELECTED DRAWING: None

Description

  The present invention relates to a polylactic acid-based thermoplastic resin composition having improved slidability, scratch resistance, and abrasion resistance of a molded product to be obtained. The present invention also relates to a molded article formed by molding this polylactic acid-based thermoplastic resin composition.

L-lactic acid, which is a raw material for polylactic acid resin, is produced by fermentation using sugars extracted from corn, straw and the like. Plants of L-lactic acid raw materials take in carbon atoms of carbon dioxide in the atmosphere by photosynthesis to synthesize organic compounds and make plant bodies based on this. Therefore, even if the plant is burned to generate carbon dioxide, the carbon atoms in the carbon dioxide that are discharged into the air are the carbon atoms that originally existed in the air. It is said that it does not affect the increase or decrease in total carbon (carbon neutral). Polylactic acid resins are expected to be put to practical use in various fields due to their characteristics such as high rigidity and transparency as characteristics of the resins.
However, the polylactic acid resin is required to be further improved as a resin that can replace various plastics.

Polylactic acid thermoplastic resin composition, which is a mixture of polylactic acid resin and styrene resin, has the same physical properties as general-purpose ABS, excellent color development, and the advantages of considering environmental issues due to the combination of plant-derived components. Compared with ABS resin, its use is limited from the viewpoint of material properties. For example, in OA equipment internal parts and parts that are complexly joined, switch parts, vibration equipment, vehicle car audio fitting parts, etc., if the slidability is poor, a squeaking noise (friction noise) is generated. However, the conventional polylactic acid-based thermoplastic resin composition cannot satisfy the required sliding property.
In all applications, scratch resistance and wear resistance are usually required.

  In order to prevent the squeaking noise (friction noise) caused by low slidability, it is common to apply non-woven fabric, and apply grease to the mating part to improve sliding, but material recycling From the viewpoint of this, it is essential to thoroughly separate and remove foreign substances, and it is preferable to use a single material. Non-woven fabric and grease are recognized as foreign substances, and it is very difficult to separate and remove them.

  Conventionally, the following proposals have been made as techniques for improving the slidability and scratch resistance of a polylactic acid resin molded product.

  Patent Document 1 discloses a polyacetal resin composition having excellent frictional wear characteristics by blending a polyacetal component, a slidability improving polymer component and a polylactic acid component as slidability improving components. Although this material is very excellent in slidability, polyacetal is concerned about the influence of formaldehyde contained in the gas generated when kneaded at high temperature on the human body.

  Patent Document 2 discloses a polylactic acid-based thermoplastic resin composition in which a rubber-reinforced resin containing a (meth) acrylic acid-based resin component and a maleimide-based resin component is blended with polylactic acid. Although this is excellent in scratch resistance, it cannot be said that the sliding property is sufficient.

Patent Document 3 proposes that the organically modified siloxane compound used in the present invention is blended for improving the slidability of the polycarbonate resin molded product. Not only the slidability between materials but also the effect of improving the slidability between different materials is not clarified.
Polycarbonate resin and polylactic acid resin have different basic structures. From the viewpoint of compatibility, slidability and scratch resistance are not expressed well, and impact resistance is also poor because compatibility causes poor delamination and lowers polycarbonate. The property improving agent applied to the resin cannot be directly applied to the polylactic acid resin.

Japanese Patent Laid-Open No. 2004-231829 JP 2007-63368 A Japanese Patent Laying-Open No. 2015-67706

  The present invention provides a polylactic acid-based thermoplastic resin composition having improved slidability, scratch resistance, abrasion resistance, impact resistance, and heat resistance of the obtained molded article, and a molded article thereof. Let it be an issue.

As a result of diligent efforts to verify and improve the prior art, the present inventors have slidability by blending a polylactic acid resin with a rubber-reinforced resin using a silicone / acrylic composite rubber and a specific organic modified siloxane compound. The inventors have found that a polylactic acid-based thermoplastic resin composition having practically sufficient characteristics in scratch resistance and abrasion resistance can be obtained, and the present invention has been achieved.
The gist of the present invention is as follows.

[1] A polylactic acid-based thermoplastic resin containing 0.3 to 3.5 parts by weight of the organically modified siloxane compound (B) with respect to 100 parts by weight of the total of the polylactic acid resin (A) and the rubber-reinforced resin (C). The composition, wherein the organically modified siloxane compound (B) is a compound in which an organically modified siloxane (b-1) and a thermoplastic resin (b-2) are chemically bonded, or an organically modified siloxane (B-1) and a thermoplastic resin (b-2), wherein the thermoplastic resin (b-2) contains polyolefin and / or polyamide, and the rubber-reinforced resin (C) It is composed of a graft copolymer (C-1) and a copolymer (C-2) obtained by graft polymerization of the polymer (c) with a vinyl monomer, and the rubbery polymer (c) is a silicone / acrylic polymer. Polylactic acid characterized by containing composite rubber Thermoplastic resin composition.

[2] In [1], 5 to 40 parts by weight of the graft copolymer (C-1) and 100% by weight of the total amount of the polylactic acid resin (A) and the rubber-reinforced resin (C) A polylactic acid-based thermoplastic resin composition comprising 30 to 70 parts by weight of (C-2).

[3] In [1] or [2], the rubber-reinforced resin (C) is obtained by graft-polymerizing a vinyl cyanide monomer and an aromatic vinyl monomer to the rubber polymer (c). Graft copolymer (C-1) and at least one vinyl monomer selected from vinyl cyanide monomers, aromatic vinyl monomers, (meth) acrylic acid ester monomers and maleimide compounds A polylactic acid-based thermoplastic resin composition comprising a copolymer (C-2) obtained by copolymerizing a monomer.

[4] The polylactic acid thermoplastic resin composition according to any one of [1] to [3], wherein the silicone / acrylic composite rubber is a polyorganosiloxane / alkyl (meth) acrylate composite rubber. .

[5] The polylactic acid thermoplastic resin composition according to any one of [1] to [4], further comprising a silicone oil (D).

[6] A polylactic acid-based thermoplastic resin molded article obtained by molding the polylactic acid-based thermoplastic resin composition according to any one of [1] to [5].

According to the present invention, it is possible to provide a polylactic acid-based thermoplastic resin composition having improved slidability, scratch resistance, abrasion resistance, impact resistance, and heat resistance.
According to the present invention, by providing a practical polylactic acid-based thermoplastic resin composition as described above, the use of a polylactic acid resin that is a plant-derived resin is expanded, and the practice of the philosophy of carbon neutral is promoted. It can contribute to reduction of environmental load.

  The molded product formed by molding the polylactic acid-based thermoplastic resin composition of the present invention has excellent sliding properties, scratch resistance, abrasion resistance, impact resistance, and heat resistance, so that it can be used as an internal component of OA equipment. It is suitable for parts that come into contact with dissimilar materials, such as switch parts, vibrating devices, and fitting parts of vehicle car audio.

  Hereinafter, embodiments of the present invention will be described in detail.

In the present invention, the weight average molecular weight (Mw) of the polylactic acid resin (A), the weight average molecular weight (Mw) of the acetone-soluble component of the rubber-reinforced resin (C), and the weight average molecular weight of the copolymer (C-2) (Mw) is a polystyrene (PS) conversion value measured by dissolving in tetrahydrofuran (THF) with gel permeation chromatography (GPC).
In the present invention, the “resin component” refers to the total of the polylactic acid resin (A), the rubber-reinforced resin (C), and other resins that may be further contained as necessary.

[Polylactic acid-based thermoplastic resin composition]
The polylactic acid-based thermoplastic resin composition of the present invention (hereinafter sometimes referred to as “the resin composition of the present invention”) is a total of 100 of the polylactic acid resin (A) and the specific rubber-reinforced resin (C). The specific organically modified siloxane compound (B) is contained in an amount of 0.3 to 3.5 parts by weight with respect to parts by weight.

[Polylactic acid resin (A)]
The polylactic acid resin (A) applied to the polylactic acid-based thermoplastic resin composition of the present invention can be obtained by known means such as a method of directly dehydrating condensation polymerization of lactic acid or a method of ring-opening polymerization of lactide. it can.

  There are three types of optical isomers, L-form, D-form, and DL-form, in the polylactic acid resin, and commercially available polylactic acid resins have L-form purity close to 100%. From the viewpoint of crystallization, the polylactic acid resin (A) used in is preferably 98% or higher in optical purity of L-form or D-form. In addition, the polylactic acid resin (A) may be a copolymer containing other copolymer components as long as the effects of the present invention are not impaired.

Other copolymerization components contained in the polylactic acid resin (A) include ethylene glycol, propylene glycol, butanediol, heptanediol, hexanediol, octanediol, nonanediol, decanediol, 1,4-cyclohexanedimethano -Glycol compounds such as diol, neopentyl glycol, glycerin, pentaerythritol, bisphenol A, polyethylene glycol, polypropylene glycol, polytetramethylene glycol; oxalic acid, succinic 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, Dicarboxylic acids such as' -diphenyl ether dicarboxylic acid, 5-sodium sulfoisophthalic acid, 5-tetrabutylphosphonium isophthalic acid; hydroxycarboxylic acids such as glycolic acid, hydroxypropionic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxycaproic acid, hydroxybenzoic acid Examples include acids; lactones such as caprolactone, valerolactone, propiolactone, undecalactone, and 1,5-oxepan-2-one. The content of such a copolymer component is usually preferably 30 mol% or less and more preferably 10 mol% or less in all monomer components in the polylactic acid resin (A).

  The molecular weight and molecular weight distribution of the polylactic acid resin (A) are not particularly limited as long as it can be substantially molded, but the weight average molecular weight (Mw) is usually 10,000 or more, preferably 5 It is desirable that it is 10,000 or more, and 100,000 or more. Although there is no restriction | limiting in particular about the upper limit of the weight average molecular weight of a polylactic acid resin (A), The weight average molecular weight of the polylactic acid resin which exists in a market normally is 400,000 or less.

  The weight average molecular weight (Mw) of the polylactic acid resin (A) can be measured by GPC (solvent THF) as described above. However, when the polylactic acid resin is in a pellet form, it is difficult to dissolve in THF. In this case, after dissolving in chloroform, the polymer component is precipitated using methanol, and the dried polymer component is dissolved in THF, and the weight average molecular weight (Mw) of the soluble component is measured. can do. Further, it can be dissolved by heating as necessary.

  Said polylactic acid resin (A) may be used individually by 1 type, and 2 or more types may be mixed and used for it.

  Specific examples of such a polylactic acid resin include “INGEO” manufactured by Nature Works, “Levoda” manufactured by China Marine Biomaterials Co., Ltd., and any of these can be used in the present invention.

[Organic Modified Siloxane Compound (B)]
The organically modified siloxane compound (B) used in the present invention is a compound in which an organically modified siloxane (b-1) and a thermoplastic resin (b-2) are chemically bonded, or an organically modified siloxane (b- 1) A mixture of a thermoplastic resin (b-2), wherein the thermoplastic resin (b-2) contains a polyolefin and / or a polyamide.

  The structure of the siloxane contained in the organically modified siloxane compound (B) is not particularly limited. The method for organically modifying the siloxane is not particularly limited as long as it is a method for obtaining an organically modified siloxane (b-1) that can be chemically bonded to the thermoplastic resin (b-2).

  Examples of the thermoplastic resin (b-2) include polyamide (nylon 6, nylon 66, etc.), polyolefin (polyethylene, polypropylene, etc.), polyester (polyethylene terephthalate, polybutylene terephthalate, etc.), polycarbonate, polyamideimide, polyphenylene sulfide, polyphenylene oxide. , Polysulfone, polyethersulfone, polyetheretherketone, polyetherimide, styrene resin (polystyrene, ABS resin, etc.), liquid crystal polyester, copolymer (for example, copolymer of acrylonitrile and styrene, nylon 6 and nylon 66) And the like, and mixtures thereof (including alloys), etc., but in the present invention, among these, polyolefin and / or polyamide, preferably polyol As an essential component of the fin.

  The content of the organically modified siloxane compound (B) in the resin composition of the present invention is 0.3 to 3 with respect to a total of 100 parts by weight of the polylactic acid resin (A) and the rubber-reinforced resin (C) described later. 0.5 parts by weight, preferably 0.4 to 3.0 parts by weight, more preferably 0.5 to 2.5 parts by weight in terms of improving dispersibility and sliding properties. . If the content of the organically modified siloxane compound (B) is less than this range, the effect of improving the slidability, scratch resistance and wear resistance cannot be obtained sufficiently, and the object of the present invention can be achieved. Absent. If the content of the organically modified siloxane compound (B) is larger than this range, a polylactic acid-based thermoplastic resin composition having excellent dispersibility cannot be obtained.

[Rubber reinforced resin (C)]
The rubber-reinforced resin (C) used in the present invention is composed of a graft copolymer (C-1) and a copolymer (C-2) obtained by graft polymerization of a vinyl monomer to a rubbery polymer (c). Become.

<Graft copolymer (C-1)>
The rubbery polymer (c) used for the graft copolymer (C-1) contains a silicone / acrylic composite rubber as an essential component. When the rubbery polymer (c) contains the silicone / acrylic composite rubber, the slidability of the molded product obtained from the resin composition of the present invention is further improved as compared with the case of using another rubbery polymer. Become good.

  Hereinafter, the graft copolymer (C-1) using a silicone / acrylic composite rubber as the rubbery polymer (c) may be referred to as “composite rubber-based graft copolymer (C-1)”. The rubbery polymer (c) made of silicone / acrylic composite rubber may be referred to as “silicone / acrylic composite rubbery polymer (c)”.

  The silicone / acrylic composite rubber composite structure includes a core-shell structure in which the core layer of the silicone rubber component is covered with an acrylic rubber component; the core layer of the acrylic rubber component is covered with a silicone rubber component Core-shell structure; Silicon rubber component and acrylic rubber component are intertwined with each other; Polyorganosiloxane segment and polyalkyl (meth) acrylate segment are linearly and sterically bonded to each other to form a net-like rubber The structure etc. which are structures are mentioned.

  The silicone rubber component of the silicone / acrylic composite rubber is mainly composed of polyorganosiloxane, and among them, polyorganosiloxane containing a vinyl polymerizable functional group is preferable. The acrylic rubber component in the silicone / acrylic composite rubber is preferably one in which an alkyl (meth) acrylate (f) and a polyfunctional monomer (g) as a crosslinking agent are polymerized.

  The silicone / acrylic composite rubber is prepared, for example, by emulsion polymerization of a monomer that forms the silicone / acrylic composite rubber in the presence of a polymerization initiator. According to the emulsion polymerization method, the particle size of the silicone / acrylic composite rubber can be easily controlled. The average particle size of the silicone / acrylic composite rubbery polymer (c) is preferably 0.1 to 0.6 μm because the impact resistance of the resin composition of the present invention can be further increased. The average particle diameter of the rubber polymer (c) can be measured by an optical method before graft polymerization. Further, after graft polymerization, the average particle diameter can be calculated using a transmission electron microscope (TEM) after dyeing the rubber polymer with a dyeing agent.

  The rubbery polymer (c) of the graft copolymer (C-1) used in the present invention may contain a rubbery polymer other than the silicone / acrylic composite rubber, and the silicone / acrylic composite rubber. Examples of other rubbery polymers include butadiene rubbers such as polybutadiene, styrene / butadiene copolymers, and acrylate / butadiene copolymers, and conjugated diene rubbers such as styrene / isoprene copolymers; One type or two or more types of acrylic rubber such as butyl acid and olefin rubber such as ethylene / propylene copolymer may be used. However, the rubbery polymer (c) contains a rubbery polymer other than the silicone / acrylic composite rubber in order to reliably obtain the effect of using the silicone / acrylic composite rubber as the rubbery polymer (c). In this case, the ratio of the rubbery polymer other than the silicone / acrylic composite rubber in the rubbery polymer (c) is preferably 50% by weight or less, particularly 30% by weight or less, particularly preferably 0 to 23% by weight.

  The polyorganosiloxane / alkyl (meth) acrylate composite rubber obtained by using the polyorganosiloxane suitable for the present invention, the alkyl (meth) acrylate (f) and the polyfunctional monomer (g) will be described below. .

  The polyorganosiloxane / alkyl (meth) acrylate composite rubber is prepared by adding, for example, an alkyl (meth) acrylate (f) to a latex of a polyorganosiloxane rubber, and allowing a normal radical polymerization initiator to act. Polyorganosiloxane / alkyl (meth) acrylate with a structure in which polyalkyl (meth) acrylate particles are dispersed in the siloxane phase, and polyorganosiloxane rubber and polyalkyl (meth) acrylate rubber are alternately entangled and reintegrated. Manufactured as a composite rubber particle.

  Specifically, a radical initiator is added in advance to the polyorganosiloxane rubber latex, and alkyl (meth) acrylate (f) is added dropwise thereto to initiate polymerization of the alkyl (meth) acrylate (f). That is, the dropped alkyl (meth) acrylate (f) is impregnated in the polyorganosiloxane and swells the polyorganosiloxane. In this state, polymerization of the alkyl (meth) acrylate (f) proceeds to form composite rubber particles. Thus, the composite rubber particle prepared by emulsion polymerization can be graft-polymerized with a vinyl monomer described later.

  The alkyl (meth) acrylate (f) may be added all at once to the latex polyorganosiloxane, or may be added continuously or intermittently. Moreover, it is preferable that the polyalkyl acrylate rubber has a crosslinked structure with a polyfunctional monomer (g).

(Polyorganosiloxane)
The polyorganosiloxane constituting the polyorganosiloxane / alkyl (meth) acrylate composite rubber is not particularly limited, but is preferably a polyorganosiloxane containing a vinyl polymerizable functional group. The polyorganosiloxane having a vinyl polymerizable functional group can be obtained by polymerizing dimethyl polysiloxane, a siloxane having a vinyl polymerizable functional group, and, if necessary, a siloxane-based crosslinking agent.

  Examples of the dimethylpolysiloxane used for the production of the polyorganosiloxane include a trimer or higher cyclic dimethylpolysiloxane, which is not particularly limited, but a 3- to 7-mer is preferable. Specific examples include hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecamethylcyclohexasiloxane. These can be used individually by 1 type or in mixture of 2 or more types. From the viewpoint of easy control of the particle size distribution, it is preferable to use octamethylcyclotetrasiloxane as the main component.

  The siloxane having a vinyl polymerizable functional group has a vinyl polymerizable functional group and has a reactive group that can be bonded to the dimethylpolysiloxane via a siloxane bond. In consideration of reactivity, it is preferable to use various alkoxysilane compounds containing a vinyl polymerizable functional group. Specifically, β-methacryloyloxyethyldimethoxymethylsilane, γ-methacryloyloxypropyldimethoxymethylsilane, γ-methacryloyloxypropylmethoxydimethylsilane, γ-methacryloyloxypropyltrimethoxysilane, γ-methacryloyloxypropylethoxydiethylsilane, γ-methacryloyloxypropylethoxydiethoxymethylsilane, methacryloyloxysilane such as δ-methacryloyloxybutyldiethoxymethylsilane, vinylsiloxane such as tetramethyltetravinylcyclotetrasiloxane, vinylphenylsilane such as p-vinylphenyldimethoxymethylsilane Further, mercapts such as γ-mercaptopropyldimethoxymethylsilane, γ-mercaptopropyltrimethoxysilane, etc. Siloxane, and the like. These vinyl polymerizable functional group-containing siloxanes can be used alone or as a mixture of two or more.

  The ratio of the above-mentioned dimethylpolysiloxane used in the production of the polyorganosiloxane having a vinyl polymerizable functional group and the above siloxane having a vinyl polymerizable functional group is dimethylpolysiloxane with respect to 100 parts by weight of the total. 97 to 99.8 parts by weight, siloxane having a vinyl polymerizable functional group is 0.2 to 3 parts by weight, in particular, dimethylpolysiloxane is 99 to 99.7 parts by weight, and siloxane having a vinyl polymerizable functional group is 0. The ratio is preferably 3 to 1 part by weight, and if the amount of dimethylpolysiloxane is larger than this range and the amount of siloxane having a vinyl polymerizable functional group is small, the molding appearance is inferior. On the other hand, when the amount of dimethylpolysiloxane is small and the amount of siloxane having a vinyl polymerizable functional group is large, the impact resistance is poor.

  Examples of the siloxane crosslinking agent include trifunctional or tetrafunctional silane crosslinking agents such as trimethoxymethylsilane, triethoxyphenylsilane, tetramethoxysilane, tetraethoxysilane, and tetrabutoxysilane. A siloxane type crosslinking agent can be used individually by 1 type or in mixture of 2 or more types. A siloxane-based crosslinking agent is not necessarily required, but when a polyorganosiloxane is produced, it is preferable to use a siloxane-based crosslinking agent. The siloxane-based crosslinking agent is preferably used in a proportion of 0.2 to 3% by weight, particularly 0.3 to 1% by weight, based on the polyorganosiloxane, from the viewpoint of the balance between the molded appearance and the impact resistance.

  The production method of the polyorganosiloxane having a vinyl polymerizable functional group is not particularly limited, but dimethylpolysiloxane and a vinyl polymerizable functional group-containing siloxane, or a siloxane mixture containing a siloxane-based crosslinking agent as the emulsifier is used as an emulsifier. The emulsion emulsified with water is made into fine particles using a homomixer that makes fine particles by shearing force generated by high-speed rotation or a homogenizer that makes fine particles by jet output from a high-pressure generator, and then at high temperature using an acid catalyst. There is a method of polymerizing and then neutralizing the acid with an alkaline substance. In this case, examples of the method for adding the acid catalyst used for the polymerization include a method of mixing with a siloxane mixture, an emulsifier and water, and a method of dropping an emulsion in which the siloxane mixture is finely divided into a high-temperature acid aqueous solution at a constant rate. .

  The emulsifier used in producing the polyorganosiloxane is not particularly limited, but an anionic emulsifier and a nonionic emulsifier are preferable. Examples of the anionic emulsifier include sodium alkylbenzene sulfonate, sodium diphenyl ether disulfonate, sodium alkyl sulfate, polyoxyethylene alkyl sodium sulfate, polyoxyethylene nonyl phenyl ether sodium sulfate, polyoxyethylene alkyl sodium phosphate, polyoxyethylene alkyl phosphoric acid. Calcium is mentioned. Examples of the nonionic emulsifier include polyoxyethylene alkyl ether, polyoxyethylene distyrenated phenyl ether, and polyoxyethylene tribenzyl phenyl ether. These emulsifiers can be used individually by 1 type or in mixture of 2 or more types.

  The method of mixing the siloxane mixture, emulsifier and water includes mixing by high-speed stirring, mixing by a high-pressure emulsifier such as a homogenizer, etc., but the method using a homogenizer narrows the distribution of the particle size of the polyorganosiloxane latex. This is the preferred method.

  Examples of the acid catalyst used for the polymerization of polyorganosiloxane include sulfonic acids such as aliphatic sulfonic acid, aliphatic substituted benzenesulfonic acid, and aliphatic substituted naphthalenesulfonic acid, and mineral acids such as sulfuric acid, hydrochloric acid, and nitric acid. These acid catalysts can be used alone or in combination of two or more.

  The polymerization temperature for obtaining the polyorganosiloxane is not particularly limited, but is preferably 50 ° C or higher, more preferably 70 ° C or higher, for example, 75 to 85 ° C. The polymerization time for obtaining the polyorganosiloxane is not particularly limited, but is preferably 2 hours or longer, more preferably 5 hours or longer, for example 7 to 10 hours. The polymerization can be stopped by cooling the reaction solution and neutralizing the latex to pH 6 to 8 with an alkaline substance such as sodium hydroxide, potassium hydroxide, sodium carbonate, aqueous ammonia solution or the like.

(Alkyl (meth) acrylate (f))
Examples of the alkyl (meth) acrylate (f) constituting the polyorganosiloxane / alkyl (meth) acrylate composite rubber include methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate. Alkyl acrylate; alkyl methacrylate having 6 or more carbon atoms in the alkyl group, such as hexyl methacrylate, 2-ethylhexyl methacrylate, n-dodecyl methacrylate, and the like. From the viewpoint of impact resistance, n-butyl acrylate is preferable among the alkyl (meth) acrylates (f). These alkyl (meth) acrylates (f) may be used alone or in combination of two or more.

  In the production of the polyorganosiloxane / alkyl (meth) acrylate composite rubber, the ratio of the alkyl (meth) acrylate (f) is 100% by weight of the total of the polyorganosiloxane and the alkyl (meth) acrylate (f). It is preferable that it is 50 to 97% by weight. In particular, it is preferably used at a ratio of 80 to 94% by weight. If the amount of alkyl (meth) acrylate used is less than this range, the impact resistance and the molded appearance, particularly the molded appearance, will be inferior, while if it is greater, the impact resistance will be inferior.

(Polyfunctional monomer (g))
In the production of a polyorganosiloxane / alkyl (meth) acrylate composite rubber, in order to introduce a cross-linked structure into the polyalkyl (meth) acrylate component obtained from the above alkyl (meth) acrylate (f), there are many crosslinking agents. It is preferable to polymerize by adding a functional monomer (g). The polymerized polyfunctional monomer (g) contained in the polyorganosiloxane / alkyl (meth) acrylate composite rubber is a vinyl monomer described later in the production of the graft copolymer (C-1). Also functions as a graft crossing point for graft bonding. Examples of the polyfunctional monomer (g) include allyl (meth) acrylate, butylene di (meth) acrylate, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, 1,3-butylene glycol di ( Examples include (meth) acrylate, 1,4-butylene glycol di (meth) acrylate, triallyl cyanurate, and triallyl isocyanurate. These may be used alone or in combination of two or more.

  Although there is no restriction | limiting in particular in the usage-amount of a polyfunctional monomer (g), it is 0.1 with respect to a total of 100 weight part of a polyfunctional monomer (g) and an alkyl (meth) acrylate (f). It is preferable that it is the quantity used as -5.0 weight part.

(Manufacture of polyorganosiloxane / alkyl (meth) acrylate composite rubber)
As a method for producing a polyorganosiloxane / alkyl (meth) acrylate composite rubber, for example, an alkyl (meth) acrylate (f) and a polyfunctional monomer (g) are added to a latex of polyorganosiloxane, and known. And a method of obtaining a latex of a composite rubber by polymerization using a radical polymerization initiator. Examples of the method of adding the alkyl (meth) acrylate (f) and the polyfunctional monomer (g) to the polyorganosiloxane latex include, for example, the alkyl (meth) acrylate (f) and the polyfunctional monomer to the polyorganosiloxane latex. And a method in which the alkyl (meth) acrylate (f) and the polyfunctional monomer (g) are added dropwise to the polyorganosiloxane latex at a constant rate.

  When producing a latex of a polyorganosiloxane / alkyl (meth) acrylate composite rubber, an emulsifier can be added to stabilize the latex and control the average particle size of the composite rubber. Examples of the emulsifier used in the production of the polyorganosiloxane / alkyl (meth) acrylate composite rubber latex include the same emulsifiers as used in the production of the polyorganosiloxane latex described above. Nonionic emulsifiers are preferred.

  Although it does not specifically limit as a polymerization initiator, For example, the redox initiator which combined the peroxide, the azo initiator, or the oxidizing agent and the reducing agent is mentioned. Among these, it is preferable to use a redox initiator, particularly a combination of ferrous sulfate, ethylenediaminetetraacetic acid disodium salt, a reducing agent and a peroxide.

  Examples of the peroxide include organic peroxides such as diisopropylbenzene hydroperoxide, p-menthane hydroperoxide, cumene hydroperoxide, and t-butyl hydroperoxide. These can be used alone or in combination of two or more. Examples of the reducing agent include sodium formaldehyde sulfoxylate (Longalite), L-ascorbic acid, fructose, dextrose, sorbose, and inositol. These may be used alone or in combination of two or more.

  The polymerization temperature for obtaining the polyorganosiloxane / alkyl (meth) acrylate composite rubber is not particularly limited, but is preferably 50 ° C or higher, more preferably 60 ° C or higher, for example, 60 to 80 ° C. The polymerization time for obtaining the polyorganosiloxane / alkyl (meth) acrylate composite rubber is not particularly limited, but is preferably 30 minutes or longer, more preferably 1 hour or longer, for example 1 to 2 hours.

  The polyorganosiloxane / alkyl (meth) acrylate composite rubber latex is produced as described above, and the gel content of the composite rubber in the latex is preferably 50 to 99% by weight, more preferably 60 to 95. % By weight, particularly preferably 70 to 85% by weight. When the gel content is within this range, the properties of the resulting resin composition, in particular, the impact strength can be improved.

  In order to measure the gel content of the composite rubber, specifically, the weighed composite rubber was dissolved in a suitable solvent at room temperature (23 ° C.) for 20 hours, and then fractionated with a 100 mesh wire mesh. The insoluble matter remaining on the wire mesh is weighed after drying at 60 ° C. for 24 hours. The ratio (% by weight) of the insoluble content relative to the composite rubber before fractionation is determined and used as the gel content of the composite rubber. As the solvent used for dissolving the composite rubber, acetone is used for easy measurement.

(Production of composite rubber-based graft copolymer (C-1))
The composite rubber-based graft copolymer (C-1) is preferably a vinyl monomer component 50 that can be graft-polymerized in the presence of 50 to 90% by weight of the silicone / acrylic composite rubbery polymer (c). 10 wt% can be obtained by graft polymerization (however, the total of the rubber polymer (c) and the monomer component is 100 wt%). Here, if the rubbery polymer (c) is not less than the above lower limit, the resulting polylactic acid-based thermoplastic resin molded article has good impact resistance, and if it is not more than the above upper limit, the impact resistance is good. A decrease can be prevented.

  Examples of the vinyl monomer component that can be graft-polymerized to the rubber polymer (c) include a vinyl cyanide monomer and an aromatic vinyl monomer. Two or more types can be selected and used.

  Examples of the vinyl cyanide monomer include acrylonitrile and methacrylonitrile, and acrylonitrile is particularly preferable. Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, p-methylstyrene, bromostyrene, and the like, and styrene and α-methylstyrene are particularly preferable.

  These monomer components may optionally contain a monomer modified with a functional group. Examples of such monomers include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and itaconic acid. And fumaric acid. These can be used individually by 1 type or in mixture of 2 or more types. The proportion of use is preferably 30% by weight or less, particularly preferably 10% by weight or less, based on 100% by weight of the total monomer components.

  As the vinyl monomer component to be grafted to the silicone / acrylic composite rubber polymer (c) of the composite rubber-based graft copolymer (C-1), among the above exemplified monomers, in particular vinyl cyanide-based A combination of a monomer and an aromatic vinyl monomer is preferred. As a combination of a vinyl cyanide monomer and an aromatic vinyl monomer, acrylonitrile is used as the vinyl cyanide monomer, styrene is used as the aromatic vinyl monomer, and a polylactic acid type is particularly obtained. This is preferable from the viewpoint of further improving the impact resistance of the thermoplastic resin molded article. In this case, the weight composition ratio of the vinyl cyanide monomer and the aromatic vinyl monomer is preferably in the range of 20/80 to 35/65, more preferably 25/75 to 30/70. By being in this range, the dispersibility becomes good.

  Graft polymerization can be carried out by known emulsion polymerization, suspension polymerization, solution polymerization, and bulk polymerization, and may be a combination of these polymerization methods. The composite rubber-based graft copolymer (C-1) is emulsified. It is preferable to produce by graft polymerization, and the emulsion graft polymerization at that time is performed by a radical polymerization technique using an emulsifier.

  The radical polymerization initiator used in the graft polymerization is not particularly limited, but a peroxide, an azo initiator, or a redox initiator combined with an oxidizing agent / reducing agent is used. Of these, redox initiators are preferred, especially ferrous sulfate, sodium pyrophosphate, glucose, hydroperoxide, ferrous sulfate, ethylenediaminetetraacetic acid disodium salt, reducing agent (Longalite), hydroperoxide Redox initiators are preferred.

  There are no particular restrictions on the emulsifier, but since it has excellent latex stability during emulsion polymerization and can increase the polymerization rate, various kinds of sodium sarcosinate, potassium fatty acid, sodium fatty acid, dipotassium alkenyl succinate, rosin acid soap, etc. An anionic emulsifier selected from carboxylates, alkyl sulfates, sodium alkylbenzene sulfonate, sodium polyoxyethylene nonylphenyl ether sulfate and the like is preferably used. These are properly used according to the purpose. The emulsifier used for the preparation of the silicone / acrylic composite rubbery polymer (c) can be used as it is, and no additional emulsifier can be added during the emulsion graft polymerization.

  A latex of a composite rubber-based graft copolymer (C-1) is obtained by graft polymerization of a vinyl monomer onto the silicone / acrylic composite rubber-like polymer (c) by emulsion polymerization, and the resulting composite rubber The latex of the composite graft copolymer (C-1) can be obtained by coagulating the latex of the composite graft copolymer (C-1), followed by washing, dehydration, and drying steps.

The weight average molecular weight (Mw) of the acetone-soluble component of the composite rubber graft copolymer (C-1) thus obtained is preferably in the range of 50,000 to 600,000, more preferably 50,000. It is in the range of ˜550,000, more preferably 50,000 to 450,000. The molecular weight of the acetone-soluble component can also be expressed by a reduced viscosity, and the reduced viscosity of the acetone-soluble component of the composite rubber-based graft copolymer (C-1) is in the range of 0.1 to 0.9 dl / g. The range is preferably 0.2 to 0.8 dl / g, more preferably 0.3 to 0.7 dl / g. Impact resistance of the resulting polylactic acid-based thermoplastic resin molded article when the weight-average molecular weight (Mw) or reduced viscosity of the acetone-soluble component of the composite rubber-based graft copolymer (C-1) is not less than the above lower limit. The resin composition of the present invention has good moldability when it has sufficient properties and is not more than the above upper limit. The acetone-soluble component is a polymer of a vinyl monomer that is not graft-polymerized to the rubbery polymer (c) that is produced when a vinyl-based monomer is graft-polymerized to the rubbery polymer (c). It corresponds to the product.
Specifically, the reduced viscosity of the acetone-soluble component is determined by the method described in the Examples section below.

  The graft ratio of the composite rubber-based graft copolymer (C-1) ((acetone insoluble matter weight / rubber polymer weight-1) × 100) is preferably 15 to 120% by weight, and further 20 More preferably, it is -85 weight%. When the graft ratio of the composite rubber-based graft copolymer (C-1) is not less than the above lower limit, the dispersibility of the composite rubber-based graft copolymer (C-1) and the resulting polylactic acid-based thermoplastic resin molding Good impact strength of the product. Moreover, impact resistance becomes favorable because a graft ratio is below the said upper limit. The copolymer grafted on the rubber polymer (c) may have a structure occluded not only inside but also inside the rubber polymer (c).

  Here, the acetone-soluble component is a polymer similar to the copolymer (C-2), and is a polymer not grafted to the rubbery polymer (c). Acetone-soluble components are often generated simultaneously with the grafting of the vinyl monomer component to the rubbery polymer (c). Therefore, the composite rubber-based graft copolymer (C-1) includes an acetone-soluble component and an acetone-insoluble component.

  In addition, it is difficult to specify in detail how the rubbery polymer (c) and the vinyl monomer component are polymerized in the composite rubber-based graft copolymer (C-1). In other words, there is a situation (impossible / unpractical circumstances) that it is impossible or directly impractical to specify the composite rubber-based graft copolymer (C-1) by its structure or characteristics. To do.

  As the composite rubber-based graft copolymer (C-1), two or more composite rubber-based graft copolymers (C-1) having different polymerization methods and component compositions may be mixed and used.

<Copolymer (C-2)>
Examples of the vinyl monomer component forming the copolymer (C-2) include a vinyl cyanide monomer, an aromatic vinyl monomer, a (meth) acrylic acid ester monomer, and a maleimide compound. 2 or more types can be selected and used, respectively.

  Examples of the vinyl cyanide monomer include acrylonitrile and methacrylonitrile, and acrylonitrile is particularly preferable. Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, p-methylstyrene, bromostyrene, and the like, and styrene and α-methylstyrene are particularly preferable. Examples of the methacrylic acid ester monomer include methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, and derivatives thereof. Among these, methyl methacrylate is particularly preferable. Examples of the acrylate monomer include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, and derivatives thereof. Among these, methyl acrylate is particularly preferable. Examples of the maleimide compound include N-phenylmaleimide, N-cyclohexylmaleimide and the like.

  As the vinyl monomer component of the copolymer (C-2), among the above exemplified monomers, a combination of a vinyl cyanide monomer and an aromatic vinyl monomer is dispersible and heat resistant. From the viewpoint, a combination of a methacrylic acid ester monomer and an acrylic acid ester monomer is preferable from the viewpoint of impact resistance. As a combination of a vinyl cyanide monomer and an aromatic vinyl monomer, acrylonitrile is used as the vinyl cyanide monomer, styrene is used as the aromatic vinyl monomer, and polylactic acid-based heat is obtained. This is preferable from the viewpoint of further improving the impact resistance of the plastic resin molded product. In this case, the weight composition ratio of the vinyl cyanide monomer and the aromatic vinyl monomer is preferably in the range of 20/80 to 35/65, more preferably 25/75 to 30/70. By being in this range, the dispersibility becomes good. Further, as a combination of a methacrylic ester monomer and an acrylate ester monomer, methyl methacrylate as a methacrylic ester monomer, methyl acrylate as an acrylate ester monomer, It is preferable from the viewpoint of the compatibility of the obtained polylactic acid-based thermoplastic resin molded article with polylactic acid. In this case, the weight composition ratio of the methacrylic ester monomer and the acrylate ester monomer is preferably 100/0 to 50/50, and more preferably 99/1 to 80/20. By being in this range, the compatibility with the polylactic acid resin (A) becomes good.

  The weight average molecular weight (Mw) of the copolymer (C-2) is preferably in the range of 30,000 to 300,000, more preferably in the range of 50,000 to 250,000. When the weight average molecular weight of the copolymer (C-2) is lower than this range, the resulting polylactic acid-based thermoplastic resin molded article has insufficient impact resistance, and when it exceeds this range, There is a risk that molding processability is lowered.

<Content in resin composition>
In the resin composition of the present invention, the content of the composite rubber-based graft copolymer (C-1) and the copolymer (C-2) of the rubber-reinforced resin (C) is such that the polylactic acid resin (A) and the rubber-reinforced It is within the range of 5 to 40 parts by weight of the composite rubber-based graft copolymer (C-1) and 30 to 70 parts by weight of the copolymer (C-2) with respect to a total of 100 parts by weight with the resin (C). More preferably, the composite rubber graft copolymer (C-1) 7 to 38 parts by weight, the copolymer (C-2) 32 to 68 parts by weight, and still more preferably the composite rubber graft copolymer (C -1) 9-36 parts by weight, copolymer (C-2) 34-66 parts by weight. When the ratio of the composite rubber-based graft copolymer (C-1) and the copolymer (C-2) is within this range, slidability, scratch resistance, wear resistance, impact resistance, heat resistance, It is preferable from the viewpoint of impact resistance and heat resistance.

[Silicone oil (D)]
The resin composition of the present invention may further contain a silicone oil (D). By including the silicone oil (D), the resin composition can be made more excellent in impact resistance.

  The silicone oil (D) is not particularly limited as long as it has a polyorganosiloxane structure, and may be an unmodified silicone oil or a modified silicone oil. However, the organically modified siloxane compound (B) is not included in this.

Examples of the unmodified silicone oil include dimethyl silicone oil, methylphenyl silicone oil, methyl hydrogen silicone oil, and the like.

  These silicone oils (D) may be used individually by 1 type, and may be used in combination of 2 or more type.

  When the resin composition of the present invention contains a silicone oil (D), the content of the silicone oil (D) is preferably 3 with respect to a total of 100 parts by weight of the polylactic acid resin (A) and the rubber-reinforced resin (C). It is not more than parts by weight, more preferably 0.05 to 2 parts by weight. If the content of the silicone oil (D) is too small, the above effect by blending the silicone oil (D) cannot be sufficiently obtained, but if too much, the resin tends to slip in the melt kneader during melt kneading, Care must be taken in manufacturing such as checking the kneading state.

[Other ingredients]
In addition to the polylactic acid resin (A), organically modified siloxane compound (B), rubber-reinforced resin (C), and silicone oil (D), the resin composition of the present invention contains various additives and other resins. Can be blended. In this case, various additives include known antioxidants, ultraviolet absorbers, lubricants, plasticizers, stabilizers, mold release agents, antistatic agents, colorants (pigments, dyes, etc.), flame retardants (halogen-based flame retardants). 1 type, or 2 or more types, such as a flame retardant, a phosphorus flame retardant, an antimony compound), a drip inhibitor, an antibacterial agent, a fungicide, a coupling agent, and an anti-hydrolysis agent.

  Other resins include AS resin, polystyrene resin, polycarbonate resin, nylon resin, methacrylic resin, polyvinyl chloride resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyphenylene ether resin, polyethylene resin, polyethylene naphthalate resin, polypropylene. Examples include resins, polypropylene terephthalate resins, polyphenylene sulfide resins, polyacetal resins, polyimide resins, phenol resins, melamine resins, silicone resins, unsaturated polyester resins, and epoxy resins. Moreover, what blended these 2 or more types may be sufficient, and you may mix | blend the said resin modified | denatured with the compatibilizer, the functional group, etc. further.

  However, when the resin composition of the present invention contains the above-mentioned other resin, the above-mentioned other resin is 50 parts by weight or less, particularly 30 parts by weight or less based on 100 parts by weight of the resin component. It is preferable in terms of effective use of the resin (A) and improvement of characteristics by the rubber reinforced resin (C).

<Production and molding of polylactic acid-based thermoplastic resin composition>
The method for pelletizing the resin composition of the present invention is not particularly limited, and for example, a twin screw extruder, a Banbury mixer, a heating roll, and the like can be used, among which melt kneading with a twin screw extruder is preferable, If necessary, resins and other additives can be blended by side feed or the like.

  The resin composition of the present invention can be molded into various molded products by a normal molding method such as injection molding, blow molding, sheet molding, vacuum molding, etc., and injection molding is particularly suitable as the molding method. .

  In addition, when preparing each component of the resin composition of the present invention, or when mixing, kneading, or molding these components, the resin waste, etc., is crushed as it is or in some cases and melt-recycled. Can be used. In this case, it can be recovered during molding, but it can also be recovered separately and used as a raw material in the above-described pellet manufacturing process.

〔Molding〕
Although there is no restriction | limiting in particular as a use of the polylactic acid-type thermoplastic resin molded product of this invention formed by shape | molding the resin composition of this invention, The outstanding slidability, scratch resistance, abrasion resistance, and also resistance to resistance. Due to impact and heat resistance, it is suitable for home appliances such as housing parts for white goods such as refrigerators and washing machines and internal parts of office automation equipment, and for automobiles, such as switch parts, vibrating equipment, and car car audio fitting parts. be able to.

Hereinafter, the present invention will be described more specifically with reference to synthesis examples, examples, reference examples, and comparative examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded. Absent.
In the following, “part” means “part by weight”.

The weight average molecular weight was measured by a standard PS (polystyrene) conversion method using Tosoh Co., Ltd. product: GPC (gel permeation chromatography, solvent; THF).
The average particle diameter of the rubber polymer was determined by a dynamic light scattering method using Nikkiso Co., Ltd .: Microtrac Model: 9230UPA.
The weight composition ratio of the monomer was determined using FT-IR manufactured by Horiba Ltd.

  The reduced viscosity of the acetone-soluble part of the graft copolymer was measured at 25 ° C. using an Ubbelohde viscometer for the N, N-dimethylformamide solution produced so that the concentration of the acetone-soluble part was 0.2 g / dl. The reduced viscosity of ηsp / C (unit: dl / g) was measured.

[Polylactic acid resin (A)]
Polylactic acid resin (A): Polylactic acid resin (L-form / D-form = 98/2 (weight ratio),
Weight average molecular weight (Mw) = 140,000, melting point = 171 ° C.)

[Organic Modified Siloxane Compound (B)]
Organically modified siloxane compound (B-1): “TEGOMER (registered trademark) AntiScratch 100” (compound of organically modified siloxane and polyolefin) manufactured by Evonik Industries
Organically modified siloxane compound (B-2): “TEGOMER (registered trademark) AntiScratch 200” (compound of organically modified siloxane and polyamide) manufactured by Evonik Industries
Organically modified siloxane compound (B-3): “TEGOMER (registered trademark) H-Si 6440” (compound of organically modified siloxane and polyester) manufactured by Evonik Industries

[Rubber reinforced resin (C)]
[Synthesis Example 1: Production of Graft Copolymer (C-1-1)]
A graft copolymer (C-1-1) using a composite rubber of polysiloxane rubber and polybutyl acrylate rubber as a rubbery polymer (c) was obtained by the following method.

<Production of polyorganosiloxane / polybutyl acrylate composite rubber polymer (c-1)>
98 parts of octamethyltetracyclosiloxane and 2 parts of γ-methacryloxypropyldimethoxymethylsilane were mixed to obtain 100 parts of a siloxane-based mixture. To this was added 300 parts of distilled water in which 0.67 parts of sodium dodecylbenzenesulfonate was dissolved, and the mixture was stirred at 10000 rpm for 2 minutes with a homomixer, and then passed once through the homogenizer at a pressure of 30 MPa. A siloxane latex was obtained.
Separately, 2 parts of dodecylbenzenesulfonic acid and 98 parts of distilled water were injected into a reactor equipped with a reagent injection vessel, a condenser, a jacket heater and a stirrer to prepare a 2% aqueous solution of dodecylbenzenesulfonic acid. . While this aqueous solution was heated to 85 ° C., the premixed organosiloxane latex was added dropwise over 4 hours, and the temperature was maintained for 1 hour after the completion of the addition and cooled.
The reaction solution was allowed to stand at room temperature for 48 hours and then neutralized with an aqueous sodium hydroxide solution to obtain a polyorganosiloxane latex (L-1). A part of the polyorganosiloxane latex (L1) was dried at 170 ° C. for 30 minutes to obtain a solid content concentration of 17.3%.

  Next, 119.5 parts of polyorganosiloxane latex (L-1) and 0.8 part of sodium polyoxyethylene alkylphenyl ether sulfate were placed in a reactor equipped with a reagent injection container, a condenser, a jacket heater and a stirrer. Charge, 203 parts of distilled water was added and mixed. Thereafter, a mixture consisting of 53.2 parts of n-butyl acrylate, 0.21 part of allyl methacrylate, 0.11 part of 1,3-butylene glycol dimethacrylate and 0.13 part of t-butyl hydroperoxide was added. The atmosphere was purged with nitrogen by passing a nitrogen stream through the reactor, and the temperature was raised to 60 ° C. An aqueous solution in which 0.0001 part of ferrous sulfate, 0.0003 part of ethylenediaminetetraacetic acid disodium salt and 0.24 part of Rongalite are dissolved in 10 parts of distilled water when the temperature inside the reactor reaches 60 ° C. Was added to initiate radical polymerization.

  The liquid temperature rose to 78 ° C. by polymerization of the acrylate component. This state was maintained for 1 hour to complete the polymerization of the acrylate component, and a latex of a composite rubber polymer (c-1) of polyorganosiloxane and polybutyl acrylate rubber was obtained. The average particle diameter of this polyorganosiloxane / polybutyl acrylate composite rubber polymer (c-1) was 120 μm.

<Production of graft copolymer (C-1-1)>
After the liquid temperature inside the reactor dropped to 60 ° C., an aqueous solution in which 0.4 part of Rongalite was dissolved in 10 parts of distilled water was added. Subsequently, 11.1 parts of acrylonitrile, 33.2 parts of styrene, and 0.2 part of t-butyl hydroperoxide were dropped and polymerized over about 1 hour. After holding for 1 hour after the completion of dropping, an aqueous solution in which 0.0002 parts of ferrous sulfate, 0.0006 parts of ethylenediaminetetraacetic acid disodium salt and 0.25 parts of Rongalite were dissolved in 10 parts of distilled water was added. Subsequently, 7.4 parts of acrylonitrile, 22.2 parts of styrene, and 0.1 part of t-butyl hydroperoxide were dripped over about 40 minutes, and were superposed | polymerized. After holding for 1 hour after the completion of dropping, the mixture was cooled and graft copolymer (C-1-) obtained by grafting acrylonitrile-styrene copolymer onto polyorganosiloxane / polybutylacrylate composite rubber polymer (c-1). The latex of 1) was obtained.

Next, 150 parts of an aqueous solution in which calcium acetate was dissolved at a rate of 5% was heated to 60 ° C. and stirred. In the calcium acetate aqueous solution, 100 parts of the graft copolymer (C-1-1) latex was gradually dropped and solidified. The obtained solidified product was separated, washed, and dried to obtain a dry powder of the graft copolymer (C-1-1).
The graft copolymer (C-1-1) had an acetone soluble content of 26% and a graft rate of 45%. Further, the reduced viscosity of the acetone-soluble component was 0.60 dl / g.

[Synthesis Example 2: Production of Graft Copolymer (C-1-2)]
A rubber-containing graft copolymer was synthesized by the emulsion polymerization method with the following composition.

[Combination]
Styrene (ST) 25 parts Acrylonitrile (AN) 10 parts Polybutadiene latex 65 parts (as solids)
Disproportionated potassium rosinate 1 part Potassium hydroxide 0.03 part t-dodecyl mercaptan (t-DM) 0.04 part Cumene hydroperoxide 0.3 part Ferrous sulfate 0.007 part Sodium pyrophosphate 0.1 Part Crystalline glucose 0.3 part Distilled water 190 part

  An autoclave is charged with distilled water, disproportionated potassium rosinate, potassium hydroxide and polybutadiene latex (gel content 80% by weight, average particle size 0.3 μm), heated to 60 ° C., ferrous sulfate, sodium pyrophosphate Crystalline glucose was added and ST, AN, t-DM and cumene hydroperoxide were continuously added over 2 hours while maintaining the temperature at 60 ° C., and then the temperature was raised to 70 ° C. and maintained for 1 hour to complete the reaction. . An antioxidant was added to the ABS latex obtained by this reaction, then coagulated with sulfuric acid, sufficiently washed with water, and dried to obtain an ABS graft copolymer (C-1-2).

[Synthesis Example 3: Production of Graft Copolymer (C-1-3)]
<Production of crosslinked ethylene / α-olefin copolymer (c-3)>
Mitsui Chemicals Co., Ltd. 100 parts EPDM (EPT3012P, ethylene content is 82 mol% and contains 1 mol% 5-ethylidene-2-norbornene as a non-conjugated diene component) dissolved in 566 parts n-hexane, Mitsui Chemicals 10 parts of acid-modified polyethylene (High Wax 2203A) manufactured by the company was added, and 4.5 parts of oleic acid was further added and completely dissolved. Separately, 0.5 part of ethylene glycol was added to an aqueous solution in which 0.9 part of KOH was dissolved in 700 parts of water, and the mixture was kept at 60 ° C., and the polymer solution prepared earlier was gradually added and emulsified. Stir. Next, a part of the solvent and water was distilled off to obtain a latex having a particle size of 0.4 to 0.6 μm. To this latex, 1.5 parts of divinylbenzene and 1.0 part of di-t-butylperoxytrimethylcyclohexane are added to 100 parts of EPDM, which is a rubber component, and reacted at 120 ° C. for 1 hour to form a crosslinked ethylene / α-olefin. A copolymer (c-3) was obtained.

<Production of graft copolymer C-1-3>
Put a cross-linked ethylene / α-olefin copolymer (c-3) (70 parts as solid content of ethylene / propylene copolymer) in a stainless polymerization tank equipped with a stirrer, and solidify in the cross-linked ethylene / α-olefin copolymer. Ion exchange water was added so that the partial concentration was 30% by weight, and 0.006 part of ferrous sulfate, 0.3 part of sodium pyrophosphate and 0.35 part of fructose were added, and the temperature was set to 80 ° C. Styrene (23.4 parts), acrylonitrile (6.6 parts) and cumene hydroperoxide (0.6 parts) were continuously added for 150 minutes, and the polymerization temperature was kept at 80 ° C. to carry out emulsion polymerization. After the polymerization, an antioxidant is added to the aqueous dispersion containing the graft copolymer, solids are precipitated with sulfuric acid, and after washing, dehydration and drying, the AES graft copolymer (C-1- 3) was obtained.

[Synthesis Example 4: Production of Graft Copolymer (C-1-4)]
In the raw material formulation of Synthesis Example 2, 60 parts (as solid content) of polybutyl acrylate (gel content: 65% by weight, average particle size: 0.34 μm) was used as the rubbery polymer, and methyl methacrylate (as the monomer) Graft copolymerization was carried out in the same manner as in Synthesis Example 2 except that 36 parts of MMA and 4 parts of methyl acrylate (MA) were reacted to obtain a graft copolymer (C-1-4).

Rubber content of rubber-containing graft copolymers (C-1-2) to (C-1-4) produced in Synthesis Examples 2, 3, and 4, weight composition ratio of monomers, graft ratio, and acetone When the weight average molecular weight of the solute was measured, it was as follows.
Graft copolymer (C-1-2): rubber content = 66.2 wt%
AN / ST = 28/72
Graft ratio = 40% by weight
Weight average molecular weight (Mw) = 154,000
Graft copolymer (C-1-3): rubber content = 70.0 wt%
AN / ST = 33/67
Graft rate = 34% by weight
Weight average molecular weight (Mw) = 50,000
Graft copolymer (C-1-4): rubber content = 62.3 wt%
MMA / MA = 90/10
Graft ratio = 35% by weight
Weight average molecular weight (Mw) = 70,000

[Copolymer (C-2)]
[Synthesis Example 5: Production of copolymer (C-2-1)]
A copolymer was synthesized by a suspension polymerization method as follows.
In a nitrogen-substituted reactor, 120 parts of water, 0.002 part of sodium alkylbenzene sulfonate, 0.5 part of polyvinyl alcohol, 0.3 part of azoisobutylnitrile, 0.5 part of t-DM, 11 parts of acrylonitrile, 5 parts of styrene, A monomer mixture consisting of 69 parts of methyl methacrylate and 15 parts of α-methylstyrene was used. The mixture was heated at a starting temperature of 60 ° C. for 5 hours and then reached 120 ° C. while sequentially adding a portion of styrene. Furthermore, after reacting at 120 ° C. for 4 hours, the polymer was taken out to obtain a copolymer (C-2-1).

<Synthesis Example 6: Production of copolymer (C-2-2)>
Using a monomer mixture consisting of 26 parts of acrylonitrile and 74 parts of styrene, polymerization was carried out in the same manner as in Synthesis Example 5 except that a part of styrene was added successively, to obtain a copolymer (C-2-2) Got.

When the weight composition ratio and weight average molecular weight (Mw) of the monomer of the copolymer produced in Synthesis Examples 5 and 6 were measured, it was as follows.
Copolymer (C-2-1): AN / ST / MMA / α-methylstyrene = 11/5/69/15
Weight average molecular weight (Mw) = 90,000
Copolymer (C-2-2): AN / ST = 26/74
Weight average molecular weight (Mw) = 110,000

(Silicone oil (D))
Dimethyl silicone oil (manufactured by Dow Corning Toray, “SH200-100cs”) was used as the silicone oil (D).

[Production and evaluation of polylactic acid-based thermoplastic resin composition pellets]
Each of the above components is mixed at a blending ratio shown in Tables 1-2, and melt-mixed with a twin-screw extruder (“TEX-30α” manufactured by Nippon Steel Works) at 200-240 ° C. to form a pellet. A pellet of a lactic acid thermoplastic resin composition was prepared.

Various test pieces were molded from these resin pellets at 200 to 240 ° C. with a 2 ounce injection molding machine (manufactured by Toshiba Corporation), and the impact resistance, scratch resistance, and heat resistance were measured by the following methods.
Impact resistance: Charpy impact value (KJ / m ² ): ISO 179 (normal temperature)
Scratch resistance: pencil hardness JIS K-5400
Heat resistance: Deflection temperature under load (° C): ISO 75 (measurement load 0.45 MPa)

  In addition, slidability, wear resistance, and dispersibility were evaluated by the following methods.

Sliding property: Using an EFM-III-N type tester manufactured by Orientec Co., Ltd., the dynamic friction coefficient was measured under the following conditions.
Specimen shape: Cylindrical shape with outer diameter 25.6mm, inner diameter 20mm, height 15mm
(Sliding area 200mm ² )
Rotational speed: 100mm / sec Test load: 1.5kg (Test machine load)
Rotation time: 5 minutes
Test item: against polycarbonate (partner material made of polycarbonate)
Polystyrene (partner material made of polystyrene)
Same material (same specimen)

Abrasion resistance: Using a dual surface abrasion tester (Daiei Kagaku Seiki Seisakusho), a surface abrasion test is performed under the following conditions to check for scratches and abrasions on the surface of the molded product, and whether powder is attached to the gauze. It observed visually and evaluated by the following reference | standard and judged (circle) to be practical.
Mating material: 8 pieces of gauze stacked Load: 1kg
Wear count: 100 reciprocations <Evaluation criteria>
○: No scratches or wear on the molded product
×: Slight scratches and wear on the molded product

Dispersibility: The surface appearance state (unevenness) of the injection-molded product was evaluated as dispersibility according to the following criteria, and ○ was judged to be practical.
<Evaluation criteria>
○: Uneven surface appearance
Δ: Slightly uneven surface appearance
×: Unevenness on the entire surface appearance

[Examples and Comparative Examples]
Tables 1 and 2 show the results of Examples 1 to 13 and Comparative Examples 1 to 7.

[Discussion]
The following can be understood from Tables 1 and 2.
By using the polylactic acid-based thermoplastic resin compositions of Examples 1 to 13 that satisfy the requirements of the claims of the present invention, molded articles having excellent slidability, scratch resistance, wear resistance, and further impact resistance and heat resistance. Can be obtained. In addition, since it is excellent in slidability and wear resistance, reduction of squeaking noise can be expected.

On the other hand, the comparative example 1 which does not contain an organic modified siloxane compound (B) is inferior in slidability. In Comparative Example 2, since the organically modified siloxane compound (B) is small, the slidability is inferior, and since the organically modified siloxane compound (B) is too small, it is difficult to uniformly disperse in the resin and the dispersibility is also inferior. It has become. Since Comparative Example 3 has a large amount of the organically modified siloxane compound (B), the dispersibility is poor.
As in Comparative Example 4, when (B-3), which is a compound of an organically modified siloxane and polyester, is used, the slidability is remarkably lowered, and the wear resistance and scratch resistance are inferior.
From the comparison between the results of Comparative Examples 5, 6, and 7 and Example 11, the graft copolymers (C-1) were graft copolymers (C-1-2), (C-1-3), (C It can be seen that the graft copolymer (C-1-1) using the silicone / acrylic composite rubber is more slidable than the -1-4).

  The polylactic acid-based thermoplastic resin composition of the present invention is excellent in slidability, scratch resistance, wear resistance, and dispersibility, so that the surface appearance of the resulting molded product is also good. It can be made excellent in characteristics such as impact resistance and heat resistance. Molded articles formed by molding the polylactic acid-based thermoplastic resin composition of the present invention are worn in contact with dissimilar materials such as OA equipment internal parts, switch parts, vibrating equipment, vehicle car audio fitting parts, It is a material suitable for applications such as parts that generate scratches and stagnation, and can be used in a variety of applications according to market needs. It is also effective in reducing

Claims (6)

A polylactic acid-based thermoplastic resin composition containing 0.3 to 3.5 parts by weight of the organically modified siloxane compound (B) with respect to 100 parts by weight of the total of the polylactic acid resin (A) and the rubber-reinforced resin (C). There,
The organically modified siloxane compound (B) is a compound in which an organically modified siloxane (b-1) and a thermoplastic resin (b-2) are chemically bonded, or an organically modified siloxane (b-1) and It is a mixture with the thermoplastic resin (b-2),
The thermoplastic resin (b-2) contains polyolefin and / or polyamide,
The rubber reinforced resin (C) comprises a graft copolymer (C-1) obtained by graft polymerization of a rubbery polymer (c) with a vinyl monomer and a copolymer (C-2).
The polylactic acid thermoplastic resin composition, wherein the rubbery polymer (c) contains a silicone / acrylic composite rubber.   In Claim 1, 5-40 weight part of graft copolymers (C-1) and copolymer (C-) with respect to a total of 100 weight part of polylactic acid resin (A) and rubber reinforced resin (C). 2) 30-70 weight part of polylactic acid-type thermoplastic resin composition characterized by the above-mentioned.   The graft copolymer according to claim 1 or 2, wherein the rubber-reinforced resin (C) is obtained by graft-polymerizing a vinyl cyanide monomer and an aromatic vinyl monomer to the rubbery polymer (c). C-1) is copolymerized with at least one vinyl monomer selected from a vinyl cyanide monomer, an aromatic vinyl monomer, a (meth) acrylic acid ester monomer, and a maleimide compound. A polylactic acid-based thermoplastic resin composition characterized by comprising a copolymer (C-2).   4. The polylactic acid-based thermoplastic resin composition according to claim 1, wherein the silicone / acrylic composite rubber is a polyorganosiloxane / alkyl (meth) acrylate composite rubber.   The polylactic acid-based thermoplastic resin composition according to any one of claims 1 to 4, further comprising a silicone oil (D).   A polylactic acid-based thermoplastic resin molded article obtained by molding the polylactic acid-based thermoplastic resin composition according to any one of claims 1 to 5.