JP6884464B2 - Polylactic acid-based thermoplastic resin composition and its molded product - Google Patents

Description

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

L-lactic acid, which is a raw material for polylactic acid resin, is produced by a fermentation method using sugars extracted from corn, potatoes and the like. Plants, which are raw materials for L-lactic acid, take in carbon atoms of carbon dioxide in the atmosphere by photosynthesis to synthesize organic compounds, and based on this, the body of the plant is made. Therefore, even if a plant is burned to generate carbon dioxide, the carbon atoms in the carbon dioxide emitted into the air are those that the plant has taken in the carbon atoms that originally existed in the air. It is said that it does not affect the increase or decrease in the total amount of carbon (carbon neutral). Further, the polylactic acid resin is expected to be put into practical use in various fields due to its characteristics such as high rigidity and high transparency.
However, as a resin that can replace various plastics, polylactic acid resin needs further improvement.

The polylactic acid-based thermoplastic resin composition, which is a mixture of polylactic acid-based resin and styrene-based resin, has the advantages of physical properties comparable to general-purpose ABS, excellent color development, and consideration for environmental problems due to the combination of plant-derived components, but is general-purpose. Compared to ABS resin, its use is limited from the viewpoint of material properties. For example, in the internal parts of OA equipment, switch parts, vibrating equipment, fitting parts of vehicle car audio, etc., where parts are joined in a complicated manner, squeaking noise (rubbing noise) is generated if the slidability is poor, so sliding characteristics However, the conventional polylactic acid-based thermoplastic resin composition cannot satisfy the required slidability characteristics.
In addition, scratch resistance and wear resistance are usually required in all applications.

In order to prevent squeaking noise (rubbing noise) caused by low slidability, a means to attach a non-woven fabric and a technique to improve slippage by applying grease to the fitting part are common, but material recycling From this point of view, it is essential to thoroughly separate and remove foreign substances, and it is more preferable to use a single material. Non-woven fabrics and grease are recognized as foreign substances, and it is very difficult to separate and remove them.

Conventionally, the following have been proposed as a technique for improving the slidability and scratch resistance of polylactic acid resin molded products.

Patent Document 1 discloses a polyacetal resin composition having excellent frictional wear characteristics by blending a polyacetal component, a slidability-improving polymer component as a slidability-improving component, and a polylactic acid component. Although this product has very excellent slidability, polyacetal is concerned about the influence of formaldehyde contained in the gas generated when kneading at a 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 product has excellent scratch resistance, it cannot be said to have sufficient slidability.

Patent Document 3 proposes that the organically modified siloxane compound used in the present invention is blended for improving the slidability of a polycarbonate resin molded product, but the effect when blended with a polylactic acid resin, particularly the same. Not only the slidability between materials but also the effect of improving the slidability between different materials has not been clarified.
Polycarbonate resin and polylactic acid resin have different basic structures, and from the viewpoint of compatibility, slidability and scratch resistance do not develop well, and poor compatibility with impact also causes layered peeling and decreases, so polycarbonate It is not that the property improver applied to the resin can be directly applied to the polylactic acid resin.

Japanese Unexamined Patent Publication No. 2004-231829 Japanese Unexamined Patent Publication No. 2007-633368 JP-A-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 product, and a molded product thereof. Make it an issue.

As a result of diligent efforts to verify and improve the prior art, the present inventors have added a rubber-reinforced resin using a silicone / acrylic composite rubber and a specific organically modified siloxane compound to the polylactic acid resin to make it slidable. The present invention has been made by finding that a polylactic acid-based thermoplastic resin composition having practically sufficient properties in scratch resistance and abrasion resistance can be obtained.
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 a total of 100 parts by weight of the polylactic acid resin (A) and the rubber reinforced resin (C). In the composition, 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. It is a mixture of (b-1) and a thermoplastic resin (b-2), the thermoplastic resin (b-2) contains polyolefin and / or polyamide, and the rubber reinforced resin (C) has a rubbery weight. It is composed of a graft copolymer (C-1) and a copolymer (C-2) obtained by graft-polymerizing the coalescence (c) with a vinyl-based monomer, and the rubbery polymer (c) is a silicone / acrylic type. A polylactic acid-based thermoplastic resin composition comprising a composite rubber.

[2] In [1], 5 to 40 parts by weight of the graft copolymer (C-1) and the copolymer with respect to 100 parts by weight of the total of the polylactic acid resin (A) and the rubber reinforced resin (C). A polylactic acid-based thermoplastic resin composition containing 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-based monomer and an aromatic vinyl-based monomer on a rubber polymer (c). At least one vinyl-based single selected from the graft copolymer (C-1), vinyl cyanide-based monomer, aromatic vinyl-based monomer, (meth) acrylic acid ester-based monomer, and maleimide compound. A polylactic acid-based thermoplastic resin composition, which comprises a copolymer (C-2) obtained by copolymerizing a monomer.

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

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

[6] A polylactic acid-based thermoplastic resin molded product 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 such a practical polylactic acid-based thermoplastic resin composition, the use of the polylactic acid resin, which is a plant-derived resin, is expanded, and the practice of the carbon-neutral idea is promoted. It can contribute to the reduction of environmental load.

The molded product obtained by molding the polylactic acid-based thermoplastic resin composition of the present invention has excellent slidability, scratch resistance, abrasion resistance, impact resistance, and heat resistance. It is suitable for parts that come into contact with dissimilar materials, such as switch parts, vibrating equipment, and fitting parts for vehicle car audio.

Embodiments of the present invention will be described in detail below.

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 obtained by dissolving it in tetrahydrofuran (THF) by gel permeation chromatography (GPC) and measuring it in terms of polystyrene (PS).
Further, 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 if necessary.

[Polylactic acid-based thermoplastic resin composition]
The polylactic acid-based thermoplastic resin composition of the present invention (hereinafter, may be referred to as “resin composition of the present invention”) is a total of 100 of the polylactic acid resin (A) and the specific rubber reinforced resin (C). It contains 0.3 to 3.5 parts by weight of the specific organically modified siloxane compound (B) 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 a known means such as a method of directly dehydrating and polycondensing lactic acid, a method of ring-opening polymerization of lactide, or the like. it can.

There are three types of optical isomers of L-form, D-form, and DL-form in the polylactic acid resin, and some commercially available polylactic acid resins have an L-form purity close to 100%. From the viewpoint of crystallization, the polylactic acid resin (A) used in is preferably L-form or D-form having an optical purity of 98% or more. Further, the polylactic acid resin (A) may be a copolymer containing other copolymerization 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, bropylene glycol, butanediol, heptanediol, hexanediol, octanediol, nonandiole, decanediol, and 1,4-cyclohexanedimetano. Glycol compounds such as ool, neopentyl glycol, glycerin, pentaerythritol, bisphenol A, polyethylene glycol, polypropylene glycol, polytetramethylene glycol; oxalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, dodecandioic acid , Maronic acid, glutaric acid, cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, bis (p-carboxyphenyl) methane, anthracendicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, 5-sodium sulfo Dicarboxylic acids such as isophthalic acid, 5-tetrabutylphosphonium isophthalic acid; hydroxycarboxylic acids such as glycolic acid, hydroxypropionic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxycaproic acid, hydroxybenzoic acid; caprolactone, valerolactone, propiolactone , Undecalactone, lactones such as 1,5-oxepan-2-one and the like. The content of such a copolymerization component is usually preferably 30 mol% or less, and more preferably 10 mol% or less of all the 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 they 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 further 100,000 or more. The upper limit of the weight average molecular weight of the polylactic acid resin (A) is not particularly limited, but the weight average molecular weight of the polylactic acid resin existing in the ordinary market is 400,000 or less.

The weight average molecular weight (Mw) of the polylactic acid resin (A) can be measured with GPC (solvent THF) as described above, but when the polylactic acid resin is in the form of pellets, it is difficult to dissolve in THF. In that case, after dissolving in chloroform, the polymer component is precipitated with methanol, and the dried polymer component is dissolved in THF to measure the weight average molecular weight (Mw) of the soluble component. can do. It can also be dissolved by heating if necessary.

The above polylactic acid resin (A) may be used alone or in combination of two or more.

Specific examples of such a polylactic acid resin include “INGEO” manufactured by Nature Works and “Revoda” manufactured by China Marine Biomaterials Co., Ltd., all of which 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-). A mixture of 1) and 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 can obtain an organically modified siloxane (b-1) that can be chemically bonded to the thermoplastic resin (b-2).

The thermoplastic resin (b-2) includes polyamide (nylon 6, nylon 66, etc.), polyolefin (polyethylene, polypropylene, etc.), polyester (polyethylene terephthalate, polybutylene terephthalate, etc.), polycarbonate, polyamideimide, polyphenylene sulfide, polyphenylene oxide. , Polysulfone, polyethersulfone, polyether ether ketone, polyetherimide, styrene resin (polystyrene, ABS resin, etc.), liquid crystal polyester, copolymer (for example, copolymer of acrylonitrile and styrene, nylon 6 and nylon 66). , Etc.), mixtures thereof (including alloys), etc., but in the present invention, among these, polyolefin and / or polyamide, preferably polyester, is essential.

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 100 parts by weight in total of the polylactic acid resin (A) and the rubber reinforced resin (C) described later. It is in the range of .5 parts by weight, but preferably 0.4 to 3.0 parts by weight, more preferably 0.5 to 2.5 parts by weight, from the viewpoint of improving dispersibility and slidability. .. If the content of the organically modified siloxane compound (B) is less than this range, the effects of improving slidability, scratch resistance, and abrasion resistance cannot be sufficiently obtained, and the object of the present invention can be achieved. Absent. Further, 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) formed by graft-polymerizing a vinyl-based monomer on 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. Since the rubber polymer (c) contains a 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 where other rubber polymers are used. Become good.

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

The composite structure of the silicone / acrylic composite rubber is a core shell structure in which the core layer of the silicone rubber component is covered with the acrylic rubber component; the core layer of the acrylic rubber component is covered with the silicone rubber component. Core-shell structure; Silicone 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 mesh-like rubber. Examples include structures that are structures.

The silicone rubber component of the silicone / acrylic composite rubber contains polyorganosiloxane as a main component, and among them, polyorganosiloxane containing a vinyl polymerizable functional group is preferable. The acrylic rubber component in the silicone / acrylic composite rubber is preferably a polymer of an alkyl (meth) acrylate (f) and a polyfunctional monomer (g) as a cross-linking agent.

The silicone / acrylic composite rubber is prepared, for example, by emulsion polymerization of a monomer forming the silicone / acrylic composite rubber in the presence of a polymerization initiator. According to the emulsification polymerization method, it is easy to control the particle size of the silicone / acrylic composite rubber. The average particle size of the silicone / acrylic composite rubber 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 size of the rubbery polymer (c) can be measured by an optical method before graft polymerization. In addition, after graft polymerization, the rubbery polymer is stained with a dyeing agent, and then the average particle size can be calculated using a transmission electron microscope (TEM).

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 may be contained. Examples of the rubbery polymer other than the above include butadiene rubbers such as polybutadiene, styrene / butadiene copolymers, acrylic acid ester / butadiene copolymers, and conjugated diene rubbers such as styrene / isoprene copolymers; polyacrylics. Examples thereof include one or more types of acrylic rubber such as butyl acid acid and olefin rubber such as ethylene / propylene copolymer. However, in order to surely obtain the effect of using the silicone / acrylic composite rubber as the rubber polymer (c), the rubber polymer (c) contains a rubber polymer other than the silicone / acrylic composite rubber. In this case, the proportion of the rubber polymer other than the silicone / acrylic composite rubber in the rubber polymer (c) is preferably 50% by weight or less, particularly 30% by weight or less, particularly preferably 0 to 23% by weight.

Hereinafter, a polyorganosiloxane / alkyl (meth) acrylate-based composite rubber obtained by using a polyorganosiloxane, an alkyl (meth) acrylate (f), and a polyfunctional monomer (g) suitable for the present invention will be described. ..

The polyorganosiloxane / alkyl (meth) acrylate-based composite rubber is prepared by, for example, adding an alkyl (meth) acrylate (f) to the latex of the polyorganosiloxane rubber and allowing an ordinary radical polymerization initiator to act on the polyorgano. Polyorganosiloxane / alkyl (meth) acrylate having 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 recombined. Manufactured as a system composite rubber particle.

Specifically, a radical initiator is added to the polyorganosiloxane rubber latex in advance, and an 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 with the polyorganosiloxane to swell the polyorganosiloxane. In this state, the polymerization of the alkyl (meth) acrylate (f) proceeds to form composite rubber particles. The composite rubber particles prepared by emulsion polymerization in this manner can be graft-polymerized with a vinyl-based monomer described later.

The alkyl (meth) acrylate (f) may be added collectively to the latex-like polyorganosiloxane, or may be added continuously or intermittently. Further, the polyalkyl acrylate rubber preferably has a crosslinked structure with a polyfunctional monomer (g).

(Polyorganosiloxane)
The polyorganosiloxane constituting the polyorganosiloxane / alkyl (meth) acrylate-based 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 dimethylpolysiloxane, a siloxane having a vinyl polymerizable functional group, and a siloxane-based cross-linking agent, if necessary.

Examples of the dimethylpolysiloxane used for producing the polyorganosiloxane include cyclic dimethylpolysiloxane having a trimer or more, and are not particularly limited, but those having a trimer of 3 to 7 are preferable. Specific examples thereof include hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecamethylcyclohexasiloxane. These can be used alone or in admixture of two or more. From the viewpoint of ease of controlling the particle size distribution, it is preferable to use octamethylcyclotetrasiloxane as the main component.

Further, the siloxane having a vinyl polymerizable functional group is one that contains a vinyl polymerizable functional group and has a reactive group that can be bonded to the above-mentioned dimethylpolysiloxane via a siloxane bond, and is different from dimethylpolysiloxane. Considering the reactivity, it is preferable to use various alkoxysilane compounds containing a vinyl polymerizable functional group. Specifically, β-methacryloyloxyethyl dimethoxymethylsilane, γ-methacryloyloxypropyldimethoxymethylsilane, γ-methacryloyloxypropylmethoxydimethylsilane, γ-methacryloyloxypropyltrimethoxysilane, γ-methacryloyloxypropylethoxydiethylsilane, Methacryloyloxysilane such as γ-methacryloyloxypropylethoxydiethoxymethylsilane, δ-methacryloyloxybutyldiethoxymethylsilane, vinylsiloxane such as tetramethyltetravinylcyclotetrasiloxane, vinylphenylsilane such as p-vinylphenyldimethoxymethylsilane Further, mercaptosiloxanes such as γ-mercaptopropyldimethoxymethylsilane and γ-mercaptopropyltrimethoxysilane can be mentioned. 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 producing a polyorganosiloxane having a vinyl polymerizable functional group to the above-mentioned siloxane having a vinyl polymerizable functional group is dimethylpolysiloxane with respect to 100 parts by weight in total. 97 to 99.8 parts by weight, siloxane having a vinyl polymerizable functional group is 0.2 to 3 parts by weight, particularly 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 molded appearance is deteriorated. On the contrary, if the amount of dimethylpolysiloxane is small and the amount of siloxane having a vinyl polymerizable functional group is large, the impact resistance becomes inferior.

Examples of the siloxane-based cross-linking agent include trifunctional or tetra-functional silane-based cross-linking agents such as trimethoxymethylsilane, triethoxyphenylsilane, tetramethoxysilane, tetraethoxysilane, and tetrabutoxysilane. The siloxane-based cross-linking agent may be used alone or in combination of two or more. A siloxane-based cross-linking agent is not always required, but it is preferable to use a siloxane-based cross-linking agent when producing polyorganosiloxane. The siloxane-based cross-linking 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, in terms of the balance between the molded appearance and impact resistance.

The method for producing a polyorganosiloxane having a vinyl-polymerizable functional group is not particularly limited, but a dimethylpolysiloxane and a vinyl-polymerizable functional group-containing siloxane, or, if necessary, a siloxane mixture containing a siloxane-based cross-linking agent is used as an emulsifier. The emulsion emulsified with water is atomized using a homomixane that atomizes with shearing force due to high-speed rotation, a homogenizer that atomizes with the jet output of a high-pressure generator, etc., and then at high temperature using an acid catalyst. Examples include a method of polymerizing and then neutralizing the acid with an alkaline substance. In that case, as a method of adding the acid catalyst used for polymerization, a method of mixing with a siloxane mixture, an emulsifier and water, 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, and the like can be mentioned. ..

The emulsifier used in producing the polyorganosiloxane is not particularly limited, but anionic emulsifiers and nonionic emulsifiers are preferable. Examples of anionic emulsifiers include sodium alkylbenzene sulfonate, sodium diphenyl ether disulfonate, sodium alkyl sulfate, sodium polyoxyethylene alkyl sulfate, sodium polyoxyethylene nonylphenyl ether sulfate, sodium polyoxyethylene alkyl phosphate, and polyoxyethylene alkyl phosphate. Calcium can be mentioned. Examples of the nonionic emulsifier include polyoxyethylene alkyl ether, polyoxyethylene distyrene phenyl ether, and polyoxyethylene tribenzyl phenyl ether. These emulsifiers can be used alone or in admixture of two or more.

Methods for mixing the siloxane mixture, emulsifier, and water include mixing by high-speed stirring and mixing with a high-pressure emulsifier such as a homogenizer, but the method using a homogenizer narrows the distribution of the particle size of 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 more, more preferably 5 hours or more, for example, 7 to 10 hours. The polymerization can be stopped by cooling the reaction solution and neutralizing the latex with an alkaline substance such as sodium hydroxide, potassium hydroxide, sodium carbonate, or an aqueous ammonia solution to pH 6 to 8.

(Alkyl (meth) acrylate (f))
Examples of the alkyl (meth) acrylate (f) constituting the polyorganosiloxane / alkyl (meth) acrylate-based 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 can be mentioned. From the viewpoint of impact resistance, n-butyl acrylate is preferable among alkyl (meth) acrylates (f). One of these alkyl (meth) acrylates (f) may be used alone, or two or more thereof may be used in combination.

In the production of the polyorganosiloxane / alkyl (meth) acrylate-based composite rubber, the ratio of the above alkyl (meth) acrylate (f) is 100% by weight based on the total of the polyorganosiloxane and the alkyl (meth) acrylate (f). When it is, it is preferably 50 to 97% by weight. In particular, it is preferably used in a proportion of 80 to 94% by weight. If the amount of the alkyl (meth) acrylate used is less than this range, the impact resistance and the molded appearance, particularly the molded appearance, are inferior, and if the amount is large, the impact resistance is inferior.

(Polyfunctional monomer (g))
In the production of polyorganosiloxane / alkyl (meth) acrylate-based composite rubber, a large amount is used as a cross-linking agent in order to introduce a cross-linked structure into the polyalkyl (meth) acrylate component obtained from the above-mentioned alkyl (meth) acrylate (f). It is preferable to add a functional monomer (g) for polymerization. The polymerized polyfunctional monomer (g) contained in the polyorganosiloxane / alkyl (meth) acrylate-based composite rubber is a vinyl-based 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, butyrene (meth) acrylate, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, and 1,3-butylene glycol di ( Examples thereof include meta) 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.

The amount of the polyfunctional monomer (g) used is not particularly limited, but is 0.1 based on 100 parts by weight of the total of the polyfunctional monomer (g) and the alkyl (meth) acrylate (f). The amount is preferably ~ 5.0 parts by weight.

(Manufacture of polyorganosiloxane / alkyl (meth) acrylate-based composite rubber)
As a method for producing a polyorganosiloxane / alkyl (meth) acrylate-based composite rubber, for example, an alkyl (meth) acrylate (f) and a polyfunctional monomer (g) are added to the latex of the polyorganosiloxane, and it is known. A method of obtaining a latex of a composite rubber by polymerization using the radical polymerization initiator of the above can be mentioned. As a method of adding the alkyl (meth) acrylate (f) and the polyfunctional monomer (g) to the latex of the polyorganosiloxane, for example, the alkyl (meth) acrylate (f) and the polyfunctional monomer (f) and the polyfunctional monomer (g) are added to the latex of the polyorganosiloxane. Examples thereof include a method of adding the sex monomer (g) all at once and a method of dropping the alkyl (meth) acrylate (f) and the polyfunctional monomer (g) onto the latex of the polyorganosiloxane at a constant rate.

When producing a latex of a polyorganosiloxane / alkyl (meth) acrylate-based 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 when producing the latex of the polyorganosiloxane / alkyl (meth) acrylate-based composite rubber include the same emulsifiers used when producing the latex of the polyorganosiloxane described above, and include an anionic emulsifier and an anionic emulsifier. Nonionic emulsifiers are preferred.

The polymerization initiator is not particularly limited, and examples thereof include peroxides, azo-based initiators, and redox-based initiators in which an oxidizing agent / reducing agent is combined. Among these, it is preferable to use a redox-based initiator, particularly a combination of ferrous sulfate, ethylenediaminetetraacetic acid disodium salt, reducing agent, and peroxide.

Examples of the peroxide include organic peroxides such as diisopropylbenzene hydroperoxide, p-menthan hydroperoxide, cumen 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 (longalit), 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-based 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-based composite rubber is not particularly limited, but is preferably 30 minutes or more, more preferably 1 hour or more, for example, 1 to 2 hours.

The polyorganosiloxane / alkyl (meth) acrylate-based 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 70-85% by weight. When the gel content is within this range, the characteristics of the obtained resin composition, particularly the impact resistance, can be improved.

To measure the gel content of the composite rubber, specifically, the weighed composite rubber is dissolved in an appropriate solvent at room temperature (23 ° C.) for 20 hours, and then separated by a 100-mesh wire mesh. Then, the insoluble matter remaining on the wire mesh is dried at 60 ° C. for 24 hours and then weighed. Determine the ratio (% by weight) of the insoluble content to the composite rubber before preparative use, and use this as the gel content of the composite rubber. When acetone is used as the solvent used for dissolving the composite rubber, the measurement can be easily performed.

(Manufacture of composite rubber-based graft copolymer (C-1))
The composite rubber-based graft copolymer (C-1) is preferably a vinyl-based monomer component 50 that can be graft-polymerized in the presence of 50 to 90% by weight of the above-mentioned silicone / acrylic composite rubber polymer (c). It can be obtained by graft-polymerizing 10% by weight (however, the total of the rubbery polymer (c) and the monomer component is 100% by weight). Here, when the rubber polymer (c) is at least the above lower limit value, the impact resistance of the obtained polylactic acid-based thermoplastic resin molded product is good, and when it is at least the above upper limit value, the impact resistance is high. It is possible to prevent the decrease.

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

Examples of the vinyl cyanide-based monomer include acrylonitrile and methacrylic nitrile, and acrylonitrile is particularly preferable. Examples of the aromatic vinyl-based monomer include styrene, α-methylstyrene, p-methylstyrene, bromstyrene and the like, and styrene and α-methylstyrene are particularly preferable.

In addition, these monomer components may contain a monomer modified by a functional group as a case, and examples of such a monomer include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and itaconic acid. , Fumaric acid and the like. Each of these can be used alone or in combination of two or more. The usage ratio is preferably 30% by weight or less, particularly preferably 10% by weight or less, based on 100% by weight of the total monomer components.

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

The graft polymerization can be carried out by a known emulsion polymerization, suspension polymerization, solution polymerization, or massive polymerization, and a method combining these polymerization methods may be used, but the composite rubber-based graft copolymer (C-1) is emulsified. It is preferably produced by graft polymerization, and the emulsion graft polymerization at that time is carried out 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-based initiator, or a redox-based initiator in which an oxidizing agent / reducing agent is combined is used. Of these, redox-based initiators are preferable, and in particular, ferrous sulfate, sodium pyrophosphate, glucose, and hydroperoxide are combined, and ferrous sulfate, disodium ethylenediamine tetraacetate, reducing agent (longalit), and hydroperoxide are combined. Redox-based initiators are preferred.

The emulsifier is not particularly limited, but various types such as sodium sarcosinate, fatty acid potassium, fatty acid sodium, alkenyl dipotassium succinate, and loginate soap can be used because the latex has excellent stability during emulsification and polymerization and the polymerization rate can be increased. An anionic emulsifier selected from carboxylates, alkyl sulfates, sodium alkylbenzene sulfonate, sodium polyoxyethylene nonylphenyl ether sulfate and the like is preferably used. These are used properly according to the purpose. It is also possible to use the emulsifier used for preparing the silicone / acrylic composite rubber polymer (c) as it is and not to add the emulsifier at the time of emulsification graft polymerization.

A latex of the composite rubber-based graft copolymer (C-1) was obtained by graft-polymerizing a vinyl-based monomer to the silicone / acrylic-based composite rubber polymer (c) by emulsification polymerization, and the obtained composite rubber. The latex of the system-based graft copolymer (C-1) is solidified, and the powder of the composite rubber-based graft copolymer (C-1) can be obtained through washing, dehydration, and drying steps.

The weight average molecular weight (Mw) of the acetone-soluble component of the composite rubber-based 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 the 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. It is preferably in the range of 0.2 to 0.8 dl / g, more preferably 0.3 to 0.7 dl / g. Impact resistance of the obtained polylactic acid-based thermoplastic resin molded product 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 at least the above lower limit value. When the properties are sufficient and not more than the above upper limit value, the moldability of the resin composition of the present invention becomes good. The acetone-soluble component is a polymer of a vinyl-based monomer that is not graft-polymerized on the rubber-based monomer (c) that is generated when a vinyl-based monomer is graft-polymerized on the rubber-based polymer (c). It corresponds to the product.
Specifically, the reduced viscosity of the acetone-soluble component is determined by the method described in the section of Examples described later.

The graft ratio ((acetone insoluble weight / rubber polymer weight-1) x 100) of the composite rubber-based graft copolymer (C-1) is preferably 15 to 120% by weight, more preferably 20%. More preferably, it is ~ 85% by weight. When the graft ratio of the composite rubber-based graft copolymer (C-1) is equal to or higher than the above lower limit, the dispersibility of the composite rubber-based graft copolymer (C-1) and the obtained polylactic acid-based thermoplastic resin molding The impact strength of the product is improved. Further, when the graft ratio is not more than the above upper limit value, the impact resistance is improved. The copolymer grafted on the rubbery polymer (c) may have a structure that occludes not only the outside but also the inside of the rubbery polymer (c).

Here, the acetone-soluble component is a polymer similar to the copolymer (C-2) and is not grafted on the rubbery polymer (c). The acetone-soluble component is often produced at the same time when the vinyl-based monomer component is grafted onto the rubbery polymer (c). Therefore, the composite rubber-based graft copolymer (C-1) contains an acetone-soluble component and an acetone-insoluble component.

In the composite rubber-based graft copolymer (C-1), it is difficult to specify in detail how the rubber-based polymer (c) and the vinyl-based monomer component are polymerized. That is, there is a situation (impossible / impractical situation) in which the composite rubber-based graft copolymer (C-1) cannot be directly specified by its structure or property, or is almost impractical. To do.

As the composite rubber-based graft copolymer (C-1), two or more kinds of 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-based monomer component forming the copolymer (C-2) include vinyl cyanide-based monomers, aromatic vinyl-based monomers, (meth) acrylic acid ester-based monomers, and maleimide compounds. As mentioned above, two or more kinds of the above-mentioned monomers can be selected and used.

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

As the vinyl-based monomer component of the copolymer (C-2), the combination of the vinyl cyanide-based monomer and the aromatic vinyl-based monomer among the above-exemplified monomers has dispersibility and heat resistance. From the viewpoint, it is preferable, and a combination of the methacrylic acid ester-based monomer and the acrylic acid ester-based monomer is preferable from the viewpoint of impact resistance. As a combination of the vinyl cyanide-based monomer and the aromatic vinyl-based monomer, acrylonitrile as the vinyl cyanide-based monomer and styrene as the aromatic vinyl-based monomer are particularly obtained. It 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-based monomer and the aromatic vinyl-based monomer is preferably in the range of 20/80 to 35/65, and more preferably 25/75 to 30/70. Within this range, the dispersibility is good. Further, as a combination of the methacrylic acid ester-based monomer and the acrylate-based monomer, methyl methacrylate is used as the methacrylic acid ester-based monomer, and methyl acrylate is particularly used as the acrylate-based monomer. It is preferable from the viewpoint of compatibility of the obtained polylactic acid-based thermoplastic resin molded product with polylactic acid. In this case, the weight composition ratio of the methacrylic acid ester-based monomer and the acrylic acid ester-based monomer is preferably 100/0 to 50/50, and further in the range of 99/1 to 80/20. Within 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 impact resistance of the obtained polylactic acid-based thermoplastic resin molded product is insufficient, and when it exceeds this range, the impact resistance is insufficient. , There is a risk that the molding processability will decrease.

<Content in resin composition>
In the resin composition of the present invention, the contents of the composite rubber-based graft copolymer (C-1) and the copolymer (C-2) of the rubber reinforced resin (C) are the polylactic acid resin (A) and the rubber reinforced. The range is 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 100 parts by weight of the resin (C) in total. Is preferable, more preferably 7 to 38 parts by weight of the composite rubber-based graft copolymer (C-1), 32 to 68 parts by weight of the copolymer (C-2), and even more preferably the composite rubber-based graft copolymer (C). -1) The range is 9 to 36 parts by weight and 34 to 66 parts by weight of the copolymer (C-2). When the ratio of the composite rubber-based graft copolymer (C-1) and the copolymer (C-2) is in this range, slidability, scratch resistance, wear resistance, impact resistance, and heat resistance, in particular, It is preferable because it is excellent in impact resistance and heat resistance.

[Silicone oil (D)]
The resin composition of the present invention may further contain a silicone oil (D), and by containing the silicone oil (D), it 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, methyl phenyl silicone oil, and methyl hydrogen silicone oil.

These silicone oils (D) may be used alone or in combination of two or more.

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 less 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 of blending the silicone oil (D) cannot be sufficiently obtained, but if it is too large, 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 above polylactic acid resin (A), organically modified siloxane compound (B), rubber reinforced resin (C), and silicone oil (D), the resin composition of the present invention further contains various additives and other resins. Can be blended. In this case, the various additives include known antioxidants, ultraviolet absorbers, lubricants, plasticizers, stabilizers, mold release agents, antistatic agents, colorants (pigments, dyes, etc.), and flame retardants (halogen-based difficulties). (Flame retardant, phosphorus flame retardant, antimony compound, etc.), drip inhibitor, antibacterial agent, antifungal agent, coupling agent, hydrolysis resistant agent, etc.

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, and polypropylene. Examples thereof include resins, polypropylene terephthalate resins, polyphenylene sulfide resins, polyacetal resins, polyimide resins, phenol resins, melamine resins, silicone resins, unsaturated polyester resins and epoxy resins. Further, two or more kinds of these may be blended, and the above resin modified with a compatibilizer, a functional group or the like may be further blended.

However, when the resin composition of the present invention contains the above-mentioned other resin, the polylactic acid is such that the above-mentioned other resin is 50 parts by weight or less, particularly 30 parts by weight or less with respect to 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).

<Manufacturing 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, or the like can be used. Among them, melt-kneading by a twin-screw extruder is preferable. If necessary, a resin or other additives can be added by side feeding or the like.

The resin composition of the present invention can be molded into various molded products by ordinary molding methods such as injection molding, blow molding, sheet molding, and vacuum molding, and injection molding is particularly preferable as the molding method. ..

The resin scraps and the like generated when preparing each component of the resin composition of the present invention, or when mixing, kneading, and molding these components are left as they are or, in some cases, crushed and melt-regenerated. Can be offered to. In this case, it is possible to collect it during molding, but it is also possible to collect it separately and use it as a raw material in the above-mentioned pellet manufacturing process.

〔Molding〕
The application of the polylactic acid-based thermoplastic resin molded product of the present invention formed by molding the resin composition of the present invention is not particularly limited, but its excellent slidability, scratch resistance, abrasion resistance, and further Due to its impact resistance and heat resistance, it is preferably used for housing members of white goods such as refrigerators and washing machines and internal parts of OA equipment in home appliances, and for switch parts and vibrating equipment, fitting parts of vehicle car audios, etc. in automobiles. be able to.

Hereinafter, the present invention will be described in more detail with reference to Synthesis Examples, Examples, Reference Examples and Comparative Examples, but the present invention is not limited to the following Examples as long as the gist thereof is not exceeded. Absent.
In the following, "part" shall mean "part by weight".

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

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

[Polylactic acid resin (A)]
Polylactic acid resin (A): Polylactic acid resin (L body / D body = 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" manufactured by Evonik Industries, Ltd. (compound of organically modified siloxane and polyolefin)
Organically modified siloxane compound (B-2): "TEGOMER (registered trademark) AntiScratch 200" manufactured by Evonik Industries, Ltd. (compound of organically modified siloxane and polyamide)
Organically modified siloxane compound (B-3): "TEGOMER (registered trademark) H-Si 6440" manufactured by Ebony Industry Co., Ltd. (compound of organically modified siloxane and polyester)

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

<Manufacture of polyorganosiloxane / polybutylacrylate 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, 300 parts of distilled water in which 0.67 parts of sodium dodecylbenzenesulfonate was dissolved was added, and after stirring with a homomixer at 10000 rpm / 2 minutes, the homogenizer was passed once at a pressure of 30 MPa to ensure a stable premixed organon. 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 container, a cooling tube, a jacket heater and a stirrer to prepare a 2% aqueous solution of dodecylbenzenesulfonic acid. .. With this aqueous solution 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 to cool.
This 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 determine the solid content concentration, which was 17.3%.

Next, 119.5 parts of polyorganosiloxane latex (L-1) and 0.8 parts of polyoxyethylene alkylphenyl ether sodium sulfate were placed in a reactor equipped with a reagent injection container, a cooling tube, a jacket heater and a stirrer. After charging, 203 parts of distilled water was added and mixed. Then, 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. By passing a nitrogen stream through this reactor, nitrogen was replaced in the atmosphere, and the temperature was raised to 60 ° C. An aqueous solution prepared by dissolving 0.0001 parts of ferrous sulfate, 0.0003 parts of disodium ethylenediaminetetraacetate and 0.24 parts of longalit in 10 parts of distilled water when the temperature inside the reactor reaches 60 ° C. Was added to initiate radical polymerization.

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

<Manufacturing of graft copolymer (C-1-1)>
After the liquid temperature inside the reactor was lowered to 60 ° C., an aqueous solution prepared by dissolving 0.4 part of Longarit in 10 parts of distilled water was added. Then, a mixed solution of 11.1 parts of acrylonitrile, 33.2 parts of styrene and 0.2 parts of t-butyl hydroperoxide was added dropwise over about 1 hour for polymerization. After holding for 1 hour after the completion of the dropping, an aqueous solution prepared by dissolving 0.0002 parts of ferrous sulfate, 0.0006 parts of disodium ethylenediaminetetraacetate and 0.25 parts of longalit in distilled water was added. Then, a mixed solution of 7.4 parts of acrylonitrile, 22.2 parts of styrene and 0.1 part of t-butyl hydroperoxide was added dropwise over about 40 minutes for polymerization. A graft copolymer (C-1-) in which an acrylonitrile-styrene copolymer is grafted onto a polyorganosiloxane / polybutylacrylate composite rubber polymer (c-1) after holding for 1 hour after completion of the dropping and cooling. The latex of 1) was obtained.

Next, 150 parts of an aqueous solution in which calcium acetate was dissolved at a ratio of 5% was heated to 60 ° C. and stirred. 100 parts of the graft copolymer (C-1-1) latex was gradually added dropwise to the calcium acetate aqueous solution to solidify it. The obtained coagulated product was separated, washed, and then dried to obtain a dry powder of the graft copolymer (C-1-1).
The acetone-soluble content of the graft copolymer (C-1-1) was 26%, and the graft ratio was 45%. 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 an emulsification polymerization method with the following composition.

[Mixing]
Styrene (ST) 25 parts Acrylonitrile (AN) 10 parts Polybutadiene latex 65 parts (as solid content)
Potassium disproportionate 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 Crystallized glucose 0.3 part Distilled water 190 part

Distilled water, potassium disproportionate, potassium hydroxide and polybutadiene latex (gel content 80% by weight, average particle size 0.3 μm) are charged in an autoclave, heated to 60 ° C, and then ferrous sulfate and sodium pyrophosphate. , Crystalline glucose was added, and ST, AN, t-DM and cumenhydroperoxide were continuously added over 2 hours while being maintained 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 such a reaction, and then the mixture was coagulated with sulfuric acid, washed thoroughly 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)>
After dissolving 100 parts of EPDM manufactured by Mitsui Chemicals, Inc. (EPT3012P, ethylene content is 82 mol% and containing 1 mol% of 5-ethylidene-2-norbornene as a non-conjugated diene component) in 566 parts of n-hexane, Mitsui Chemicals 10 parts of acid-modified polyethylene (High Wax 2203A) manufactured by the same company was added, and 4.5 parts of oleic acid was further added to completely dissolve the mixture. 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 to keep the temperature at 60 ° C. Stirred. Then, 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 dit-butylperoxytrimethylcyclohexane are added to 100 parts of EPDM, which is a rubber component, and reacted at 120 ° C. for 1 hour to crosslink ethylene / α-olefin. A copolymer (c-3) was obtained.

<Manufacture of Graft Copolymer C-1-3>
A crosslinked ethylene / α-olefin copolymer (c-3) (70 parts as a solid content of the ethylene / propylene copolymer) was placed in a stainless polymer tank equipped with a stirrer, and the crosslinked ethylene / α-olefin copolymer was solidified. Ion-exchanged water was added so that the partial concentration was 30% by weight, 0.006 part of ferrous sulfate, 0.3 part of sodium pyrophosphate and 0.35 part of fructose were charged, and the temperature was adjusted to 80 ° C. 23.4 parts of styrene, 6.6 parts of acrylonitrile and 0.6 parts of cumene hydroperoxide 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, the solid content is precipitated with sulfuric acid, and after the steps of 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 a solid content) of butyl polyacrylate (gel content 65% by weight, average particle size 0.34 μm) was used as the rubber polymer, and methyl methacrylate (as a solid content) was used. A graft copolymer (C-1-4) was obtained by performing graft polymerization in the same manner as in Synthesis Example 2 except that 36 parts of MMA) and 4 parts of methyl acrylate (MA) were reacted.

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

[Copolymer (C-2)]
[Synthesis Example 5: Production of Copolymer (C-2-1)]
The copolymer was synthesized by the suspension polymerization method as follows.
120 parts of water, 0.002 parts of sodium alkylbenzene sulfonate, 0.5 parts of polyvinyl alcohol, 0.3 parts of azoisobutylnitrile, 0.5 parts of t-DM, 11 parts of acrylonitrile, 5 parts of styrene in a nitrogen-substituted reactor. A monomer mixture consisting of 69 parts of methyl methacrylate and 15 parts of α-methylstyrene was used, and a part of styrene was sequentially added and heated from a starting temperature of 60 ° C. for 5 hours, and then reached 120 ° C. Further, 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)>
A monomer mixture consisting of 26 parts of acrylonitrile and 74 parts of styrene was used, and polymerization was carried out in the same manner as in Synthesis Example 5 except that a part of styrene was sequentially added to obtain a copolymer (C-2-2). Got

The weight composition ratio and the weight average molecular weight (Mw) of the monomers of the copolymers produced in Synthesis Examples 5 and 6 were measured and found to be 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))
As the silicone oil (D), dimethyl silicone oil (manufactured by Toray Dow Corning, "SH200-100cs") was used.

[Manufacturing and evaluation of polylactic acid-based thermoplastic resin composition pellets]
Each of the above components is mixed at the blending ratios shown in Tables 1 and 2, melt-mixed at 200 to 240 ° C. with a twin-screw extruder (“TEX-30α” manufactured by Japan Steel Works), and pelletized to make a poly. Pellets of a lactic acid-based thermoplastic resin composition were prepared.

Various test pieces were formed from these resin pellets with a 2 ounce injection molding machine (manufactured by Toshiba Corporation) at 200 to 240 ° C., and 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 (measured load 0.45 MPa)

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

Slidability: The dynamic friction coefficient was measured under the following conditions using an EFM-III-N type testing machine manufactured by Orientec Co., Ltd.
Specimen shape: Cylindrical shape with outer diameter of 25.6 mm, inner diameter of 20 mm, and height of 15 mm
(Sliding area 200 mm ² )
Rotation speed: 100 mm / sec Test load: 1.5 kg (load of tester)
Rotation time: 5 minutes
Test item: Against polycarbonate (the mating material is made of polycarbonate)
Against polystyrene (the mating material is made of polystyrene)
Same type material (same test pieces)

Abrasion resistance: Using a dual flat surface abrasion tester (Daei Kagaku Seiki Seisakusho), perform a flat surface wear test under the following conditions to check for scratches and wear on the surface of the molded product and the presence or absence of powder adhering to the gauze. It was visually observed and evaluated according to the following criteria, and ○ was judged to be practical.
Mating material: 8 layers of gauze Load: 1 kg
Number of wears: 100 round trips <Evaluation criteria>
◯: There are no scratches or wear on the molded product.
X: There are slight scratches and wear on the molded product.

Dispersibility: The state (unevenness) of the surface appearance of the injection-molded product was evaluated as dispersibility according to the following criteria, and ○ was judged to be practical.
<Evaluation criteria>
◯: No unevenness in surface appearance
Δ: There is some unevenness in the surface appearance
×: There is 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 seen 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 present invention, a molded product having excellent slidability, scratch resistance, abrasion resistance, impact resistance, and heat resistance can be obtained. Obtainable. In addition, since it is excellent in slidability and wear resistance, it can be expected to reduce squeaking noise.

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

The polylactic acid-based thermoplastic resin composition of the present invention is excellent in slidability, scratch resistance, abrasion resistance, and dispersibility, so that the surface appearance of the obtained molded product is also good, and further. It can also be excellent in characteristics such as impact resistance and heat resistance. The molded product obtained by molding the polylactic acid-based thermoplastic resin composition of the present invention is worn by contact with dissimilar materials such as internal parts of OA equipment, switch parts, vibrating equipment, and fitting parts of vehicle car audio. It is a material suitable for applications such as parts that generate scratches and squeaks, and can be used for various purposes according to the needs of the market. Its industrial usefulness is extremely high, and it has an environmental load. 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 a total of 100 parts by weight of the polylactic acid resin (A) and the rubber reinforced resin (C). There,
Organic modified siloxane compound (B) is a compound in which an organic modified siloxane (b-1) and the thermoplastic resin (b-2) is chemically bonded,
The thermoplastic resin (b-2) contains polyolefin and / or polyamide.
The rubber reinforced resin (C) is composed of a graft copolymer (C-1) and a copolymer (C-2) obtained by graft-polymerizing the rubbery polymer (c) with a vinyl-based monomer.
A polylactic acid-based thermoplastic resin composition, wherein the rubbery polymer (c) contains a silicone / acrylic composite rubber. In claim 1, 5 to 40 parts by weight of the graft copolymer (C-1) and the copolymer (C-) are added to 100 parts by weight of the total of the polylactic acid resin (A) and the rubber reinforced resin (C). A polylactic acid-based thermoplastic resin composition containing 30 to 70 parts by weight of 2). In claim 1 or 2, a graft copolymer obtained by graft-polymerizing a vinyl cyanide-based monomer and an aromatic vinyl-based monomer on a rubbery polymer (c) by the rubber reinforced resin (C). Copolymerization of C-1) with at least one vinyl-based monomer selected from vinyl cyanide-based monomers, aromatic vinyl-based monomers, (meth) acrylic acid ester-based monomers, and maleimide compounds. A polylactic acid-based thermoplastic resin composition comprising a copolymer (C-2) made of. The polylactic acid-based thermoplastic resin composition according to any one of claims 1 to 3, wherein the silicone / acrylic composite rubber is a polyorganosiloxane / alkyl (meth) acrylate-based 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 product obtained by molding the polylactic acid-based thermoplastic resin composition according to any one of claims 1 to 5.