Graft copolymer resin composition

Abstract

The purpose of the present invention is to provide a graft copolymer resin composition excellent in impact resistance, the graft copolymer resin composition comprising a graft copolymer resin which can be efficiently polymerized, while using a raw material contributing to carbon neutral. The graft copolymer resin composition according to the present invention comprises a graft copolymer resin obtained by graft-polymerizing an aromatic vinyl-based monomer and another vinyl-based monomer copolymerizable with the aromatic vinyl-based monomer into deproteinized natural rubber, the graft copolymer resin composition characterized in that the graft copolymer resin has a graft ratio of 75%-185%, and the graft copolymer resin has a reduced viscosity [IV] of 0.75 dl / g or less.

Description

Graft copolymer resin composition

[0001] The present invention relates to a graft copolymer resin composition.

[0002] Styrene-based resins, typified by ABS resin, have excellent moldability and balance of mechanical properties, as well as excellent paintability and electrical insulation properties, and are therefore used in a wide range of fields, such as vehicle interior and exterior parts, building materials, home appliances, electrical and electronic devices, office equipment parts, and office automation equipment.

[0003] In recent years, efforts have been made to replace the rubber component used in the styrene-based resin with natural rubber instead of synthetic rubber, with the aim of reducing the environmental load and from the viewpoint of carbon neutrality.

[0004] It is known that when natural rubber is used, aggregates are generated during polymerization, which inhibits the polymerization. To solve this problem, it has been known to previously deproteinize natural rubber, as described in Patent Document 1.

[0005] JP 2011-225791 A

[0006] However, even with deproteinized natural rubber, there are limitations to reducing aggregates and efficiently polymerizing it.

[0007] Furthermore, conventionally known graft copolymer resins using natural rubber, such as those disclosed in Patent Document 1, still have insufficient graft ratios, and resin compositions using the graft copolymer resins tend to have poor impact resistance.

[0008] Therefore, an object of the present invention is to provide a graft copolymer resin composition that uses raw materials that contribute to carbon neutrality, contains a graft copolymer resin that can be polymerized efficiently, and has excellent impact resistance.

[0009] As a result of intensive research conducted by the present inventors to solve the above-mentioned problems, they have found that a deproteinized natural rubber contains a graft copolymer resin obtained by graft-polymerizing an aromatic vinyl monomer and another vinyl monomer copolymerizable with the aromatic vinyl monomer, and the graft ratio and reduced viscosity [IV] of the graft copolymer resin are within specific ranges, and the graft copolymer resin contains a graft copolymer resin that can be efficiently polymerized while using raw materials that contribute to carbon neutrality, and has excellent impact resistance.

[0010] That is, the present invention provides a graft copolymer resin composition comprising a graft copolymer resin obtained by graft polymerizing an aromatic vinyl monomer and another vinyl monomer copolymerizable with the aromatic vinyl monomer onto deproteinized natural rubber, the graft copolymer resin having a graft ratio of 75 to 185% and a reduced viscosity [IV] of 0.75 dL / g or less. The graft ratio of 75 to 185% allows the graft copolymer resin to exhibit impact resistance, and the reduced viscosity [IV] of 0.75 dL / g or less allows efficient polymerization while exhibiting impact resistance and reducing aggregates.

[0011] In the graft copolymer resin composition, the mass ratio of the deproteinized natural rubber to the aromatic vinyl monomer and the other vinyl monomer in the graft copolymer resin is preferably 30:70 to 50:50.

[0012] In the graft copolymer resin composition, the graft ratio of the graft copolymer resin is preferably 120 to 140%.

[0013] The graft copolymer resin composition preferably contains a rosin acid emulsifier.

[0014] The graft copolymer resin composition preferably contains 0.5% by mass or less of the aggregates relative to 100% by mass of the total of the aggregates and the latex of the graft copolymer resin.

[0015] The present invention also provides a method for producing a graft copolymer resin composition, which includes a step of producing a latex of a graft copolymer resin by an emulsion polymerization method, in which the amount of the aggregates after polymerization is 0.5% by mass or less, relative to 100% by mass of the total of the aggregates and the latex of the graft copolymer resin.

[0016] The graft copolymer resin composition of the present invention contains a graft copolymer resin that can be efficiently polymerized using raw materials that contribute to carbon neutrality, and has excellent impact resistance.

[0017] [Graft Copolymer Resin Composition] The graft copolymer resin composition of the present invention contains a graft copolymer resin obtained by graft polymerizing an aromatic vinyl monomer and another vinyl monomer copolymerizable with the aromatic vinyl monomer (hereinafter, the "other vinyl monomer copolymerizable with the aromatic vinyl monomer" may be referred to as the "other vinyl monomer") onto deproteinized natural rubber, thereby using a raw material that contributes to carbon neutrality. The graft ratio of the graft copolymer resin is 75 to 185%, and the reduced viscosity [IV] is 0.75 dl / g or less, so that the graft copolymer resin composition has excellent impact resistance and can reduce aggregates, thereby enabling efficient polymerization.

[0018] The content of the rubber component contained in the graft copolymer resin composition is preferably 5 to 40% by mass, more preferably 10 to 35% by mass, and even more preferably 15 to 30% by mass, relative to the total amount (100% by mass) of the graft copolymer resin composition. A rubber component content of 5% by mass or more can provide higher impact resistance. Furthermore, a rubber component content of 40% by mass or less can provide good fluidity. In the present invention, when a rubber component is contained as part of the resin, only the content of the rubber component is considered as the content of the rubber component.

[0019] The graft copolymer resin composition has a notched Charpy impact strength (NC) according to ISO 179 (test piece thickness: 4 mm, measurement temperature: 23°C) of 10 kJ / m ２ More preferably, 15 kJ / m or more ２More preferably, 20 kJ / m ２ More preferably, it is 25 kJ / m or more. ２ The Charpy impact value is 10 kJ / m or more. ２ If the impact strength is 100 kJ / m or more, the impact resistance is more excellent. ２ It may be the following:

[0020] The melt volume flow rate (MVR) of the graft copolymer resin composition according to ISO 1133 at 220°C under a load of 10 kg is 4 to 30 cm ３ / 10 minutes is preferable, and 5 to 30 cm ３ / 10 minutes, more preferably 8 to 27 cm ３ When the MVR is within the above range, good fluidity can be exhibited.

[0021] <Graft Copolymer Resin> The graft copolymer resin contained in the graft copolymer resin composition is obtained by graft polymerizing an aromatic vinyl monomer and another vinyl monomer copolymerizable with the aromatic vinyl monomer onto deproteinized natural rubber.

[0022] The graft copolymer resin generally mainly contains a graft polymer in which the aromatic vinyl monomer and the other vinyl monomer are grafted onto the deproteinized natural rubber, but may also contain a copolymer in which a monomer component containing the aromatic vinyl monomer and the other vinyl monomer that are not grafted onto the deproteinized natural rubber is copolymerized.

[0023] The graft ratio of the graft copolymer resin, as measured by the method described in the Examples below, is 75 to 185%, preferably 85 to 170%, more preferably 100 to 150%, and even more preferably 120 to 140%. By adjusting the graft ratio within the above range, impact resistance can be exhibited and aggregates can be reduced.

[0024] The graft copolymer resin has a reduced viscosity [IV] of 0.75 dl / g or less, preferably 0.15 to 0.72 dl / g, more preferably 0.30 to 0.65 dl / g, and even more preferably 0.35 to 0.60 dl / g. When the reduced viscosity [IV] is 0.15 dl / g or more, impact resistance can be exhibited, and when the reduced viscosity is 0.75 dl / g or less, aggregates can be reduced and polymerization can be performed efficiently.

[0025] The reduced viscosity [IV] can be determined by the following method. Fractionation method: Approximately 2 g of graft copolymer resin and 60 ml of acetone are placed in an Erlenmeyer flask and immersed for 24 hours. The mixture is then centrifuged at 12,000 rpm for 30 minutes using a centrifuge to separate it into a soluble and an insoluble portion. The insoluble portion is obtained by drying overnight at room temperature using vacuum drying. The soluble portion is obtained by precipitating the acetone-soluble portion in methanol and then drying overnight at room temperature using vacuum drying. Reduced viscosity [IV] (dl / g): The acetone-soluble portion is dissolved in N,N-dimethylformamide to prepare a solution with a concentration of 0.4 g / 100 ml, and the reduced viscosity [IV] is determined from the flow time measured at 30°C using a Cannon-Fenske viscometer.

[0026] The amount of aggregates during polymerization of the graft copolymer resin is preferably 0.5% by mass or less, more preferably 0.45% by mass or less, even more preferably 0.4% by mass or less, and particularly preferably 0.3% by mass or less, relative to 100% by mass of the total of the aggregates and the graft copolymer resin latex described below. Having the aggregate content of 0.5% by mass or less can improve polymerization efficiency. The lower limit is not particularly limited, and may be 0% by mass. In the present invention, the aggregates refer to components that are not filtered through a 100-mesh wire screen and are recovered when the graft copolymer resin latex is filtered through a 100-mesh wire screen after polymerization. The aggregates contain the deproteinized natural rubber as a main component, and may also contain other components exemplified as components of the graft copolymer resin composition of the present invention and compounds derived from each of the components.

[0027] (Deproteinized Natural Rubber) The graft copolymer resin contains structural units derived from deproteinized natural rubber. Since the deproteinized natural rubber is less susceptible to polymerization inhibition by proteins, a graft copolymer resin with a high graft ratio can be obtained. In addition, the deproteinized natural rubber is an environmentally friendly raw material that contributes to carbon neutrality. Furthermore, by blending a graft copolymer resin containing structural units derived from the deproteinized natural rubber, a resin composition with improved impact resistance can be obtained. Only one type of deproteinized natural rubber may be used, or two or more types may be used.

[0028] The deproteinized natural rubber can be obtained by removing proteins from natural rubber latex using a known deproteinization method, such as adding a protease to natural rubber latex to decompose proteins, washing natural rubber latex with a surfactant, adding urea or other urea-based protein denaturing agent to natural rubber latex to decompose proteins, or a combination of these methods.

[0029] Specifically, the deproteinized natural rubber preferably has a nitrogen content of 1.0% by mass or less, more preferably 0.5% by mass or less, and even more preferably 0.3% by mass or less. A nitrogen content of 1.0% by mass or less reduces aggregates of the graft copolymer resin, facilitating efficient polymerization. The lower limit is not particularly limited and may be 0% by mass.

[0030] The graft copolymer resin may contain rubber components other than the deproteinized natural rubber, but from the viewpoint of using it as an environmentally friendly and carbon-neutral raw material, the content of the deproteinized natural rubber relative to the total amount (100% by mass) of rubber components contained in the graft copolymer resin is preferably 95% by mass or more, more preferably 99% by mass or more, and may even be 100% by mass. In other words, it is preferable that the graft copolymer resin does not contain any rubber components other than the deproteinized natural rubber.

[0031] The average particle size of the deproteinized natural rubber is not particularly limited, but from the viewpoint of graft polymerization efficiency, it is preferably 400 to 1,000 nm, more preferably 500 to 800 nm, and even more preferably 600 to 700 nm. An average particle size of 400 nm or more can exhibit impact resistance. Furthermore, an average particle size of 1,000 nm or less can achieve a good appearance.

[0032] The content of the structural units derived from the deproteinized natural rubber is preferably 25 to 55% by mass, more preferably 30 to 50% by mass, and even more preferably 40 to 50% by mass, relative to the total amount (100% by mass) of the graft copolymer resin. Having a deproteinized natural rubber content of 25% by mass or more can facilitate the exertion of impact resistance. Having a content of 55% by mass or less can reduce aggregates and facilitate efficient polymerization.

[0033] (Aromatic vinyl monomer) The graft copolymer resin contains a structural unit derived from an aromatic vinyl monomer. The aromatic vinyl monomer is a component that is graft polymerized with the deproteinized natural rubber to form the graft copolymer resin. The aromatic vinyl monomer may also be derived from biomass. Only one type of aromatic vinyl monomer may be used, or two or more types may be used.

[0034] Examples of the aromatic vinyl monomer include monomers having a styrene structure (styrene monomers). Examples of the styrene monomer include styrene, α-methylstyrene, m-methylstyrene, p-methylstyrene, p-ethylstyrene, p-isobutylstyrene, p-t-butylstyrene, bromostyrene, and chloromethylstyrene. Among these, styrene and α-methylstyrene are preferred.

[0035] The content of the constituent units derived from the aromatic vinyl monomer is preferably 25 to 55% by mass, more preferably 30 to 50% by mass, and even more preferably 35 to 45% by mass, relative to the total amount (100% by mass) of the graft copolymer resin. By having the content of the constituent units derived from the aromatic vinyl monomer within the above range, the graft ratio can be sufficiently improved.

[0036] The content of the structural units derived from the aromatic vinyl monomer is preferably 60 to 90% by mass, more preferably 65 to 85% by mass, and even more preferably 70 to 80% by mass, relative to 100% by mass of the total of the structural units derived from the aromatic vinyl monomer and the structural units derived from the other vinyl monomers. By having the content of the structural units derived from the aromatic vinyl monomer within the above range, the graft ratio can be sufficiently improved.

[0037] (Other vinyl monomers copolymerizable with aromatic vinyl monomers) The graft copolymer resin contains, in addition to the aromatic vinyl monomers, other monomers copolymerizable with the aromatic vinyl monomers. Examples of the other vinyl monomers include vinyl cyanide monomers, (meth)acrylic acid ester monomers, amide monomers, and unsaturated carboxylic acid monomers. Biomass-derived vinyl monomers can also be used as the other vinyl monomers. Only one type of the other vinyl monomers may be used, or two or more types may be used.

[0038] Examples of the vinyl cyanide monomer include nitrile group-containing monomers such as acrylonitrile, methacrylonitrile, ethacrylonitrile, and fumaronitrile. Examples of the (meth)acrylic acid ester monomer include alkyl (meth)acrylates having an alkyl group that may have a substituent, such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, phenyl (meth)acrylate, 4-t-butylphenyl (meth)acrylate, dibromophenyl (meth)acrylate, and chlorophenyl (meth)acrylate. Examples of the amide monomer include amide group-containing monomers such as acrylamide and methacrylamide. Examples of the unsaturated carboxylic acid monomer include carboxy group-containing monomers such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, and itaconic acid.

[0039] The content of the structural units derived from the other vinyl-based monomers is preferably 5 to 25% by mass, more preferably 7 to 20% by mass, and even more preferably 10 to 15% by mass, relative to the total amount (100% by mass) of the graft copolymer resin. By having the content of the structural units derived from the other vinyl-based monomers within the above range, the graft ratio can be sufficiently improved.

[0040] The content of the structural units derived from the other vinyl monomers is preferably 10 to 40% by mass, more preferably 15 to 35% by mass, and even more preferably 20 to 30% by mass, relative to 100% by mass of the total of the structural units derived from the aromatic vinyl monomers and the structural units derived from the other vinyl monomers. By having the content of the structural units derived from the other vinyl monomers within the above range, the graft ratio can be sufficiently improved.

[0041] The mass ratio of the aromatic vinyl monomer and the other vinyl monomer to the deproteinized natural rubber is preferably 30:70 to 50:50. This ratio makes it easy to reduce aggregates, efficiently polymerize, and achieve an appropriate graft ratio.

[0042] In order to promote the polymerization reaction of the graft copolymer resin, it is preferable to use an emulsifier. That is, the graft copolymer resin composition preferably contains an emulsifier. By using the emulsifier, the graft polymerization of the graft copolymer resin can be carried out efficiently. The emulsifier can be one that is suitable for the polymerization method. Only one type of emulsifier may be used, or two or more types may be used.

[0043] Examples of the emulsifier include anionic emulsifiers such as sulfate ester emulsifiers of higher alcohols, alkylbenzenesulfonic acid emulsifiers, alkyldiphenyletherdisulfonic acid emulsifiers, aliphatic sulfonic acid emulsifiers, aliphatic carboxylic acid emulsifiers, dehydroabietic acid emulsifiers, formalin condensate emulsifiers of naphthalenesulfonic acid, and sulfate ester emulsifiers of nonionic surfactants; and nonionic emulsifiers such as alkyl ester emulsifiers of polyethylene glycol, alkylphenyl ether emulsifiers, and alkyl ether emulsifiers.

[0044] Among these, from the viewpoint of reducing the amount of emulsifier remaining in the graft copolymer resin and improving impact resistance, the emulsifier is preferably an aliphatic carboxylic acid emulsifier. Examples of the aliphatic carboxylic acid emulsifier include fatty acid emulsifiers having 8 to 20 carbon atoms and rosin acid emulsifiers, with rosin acid emulsifiers being particularly preferred. When a rosin acid emulsifier is used as the emulsifier, the impact resistance of the graft copolymer resin can be further improved compared to when other emulsifiers are used. Examples of the rosin acid emulsifier include disproportionated potassium rosinate and disproportionated sodium rosinate.

[0045] The amount of the emulsifier used is preferably 0.5 to 5 parts by mass, and more preferably 0.7 to 3 parts by mass, per 100 parts by mass of the total of the deproteinized natural rubber and vinyl monomers constituting the graft copolymer resin. When the amount of the emulsifier used is 0.5 parts by mass or more, the graft copolymerization can proceed easily. Furthermore, when the amount is 5 parts by mass or less, the amount of residual emulsifier can be reduced, making it easier to exhibit impact resistance.

[0046] The graft copolymer resin preferably contains a reaction initiator. Known or commonly used reaction initiators can be used as the reaction initiator depending on the resin used and the desired physical properties. In particular, it is preferable to use a radical polymerization initiator as the reaction initiator for the graft copolymer resin. Only one type of the reaction initiator may be used, or two or more types may be used.

[0047] The radical polymerization initiator may be oil-soluble or water-soluble, and examples thereof include organic peroxides such as benzoyl peroxide, azobisisobutyronitrile, lauroyl peroxide, t-butyl peroxylaurate, t-butyl peroxymonocarbonate, t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, and paramenthane hydroperoxide; and persulfates such as potassium persulfate, ammonium persulfate, and sodium persulfate.

[0048] In addition, in order to increase the polymerization efficiency of the graft copolymer resin, it is preferable to use the reaction initiator in combination with a reducing agent. That is, the graft copolymer resin composition may contain a reducing agent. Examples of the reducing agent include a mixture of a sugar such as glucose, sucrose, or fructose with pyrophosphate; tetraethylenepentamine, triethylenetetramine, sodium pyrobisulfite, sodium hydrogensulfite, ferrous sulfate, L-ascorbic acid, and salts thereof. In addition, the reducing agent may be used alone or in combination of two or more.

[0049] The content of the reaction initiator is preferably 0.1 to 1 part by mass, and more preferably 0.15 to 0.5 parts by mass, per 100 parts by mass of the total of the deproteinized natural rubber and vinyl monomer constituting the graft copolymer resin.

[0050] When the reducing agent is used, the amount used is preferably 0.05 to 1 part by mass, and more preferably 0.07 to 0.5 parts by mass, per 100 parts by mass of the total of the deproteinized natural rubber and vinyl monomer constituting the graft copolymer resin.

[0051] In addition, the graft copolymer resin may contain a chain transfer agent to adjust the graft ratio and reduced viscosity [IV]. The chain transfer agent may be used alone or in combination of two or more.

[0052] As the chain transfer agent, known or conventional chain transfer agents can be used, and examples thereof include mercaptans such as octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n-hexamethyl mercaptan, n-tetradecyl mercaptan, t-tetradecyl mercaptan, etc.; terpinolenes; α-methylstyrene dimer, etc. The chain transfer agent can be added to the graft copolymer resin composition all at once or continuously.

[0053] When the chain transfer agent is contained, the content thereof is preferably more than 0 to 0.5 parts by mass, more preferably more than 0 to 0.3 parts by mass, and even more preferably more than 0 to 0.15 parts by mass, per 100 parts by mass of the total of the deproteinized natural rubber and vinyl monomer constituting the graft copolymer resin.

[0054] The graft copolymer resin can be produced by any known or conventional method, specifically emulsion polymerization, suspension polymerization, solution polymerization, bulk polymerization, or a combination thereof. Among these, emulsion polymerization is preferred. The aromatic vinyl monomer and other vinyl monomers used to produce the graft copolymer resin may be polymerized by adding them all at once in the presence of the deproteinized natural rubber, or by adding them continuously. Alternatively, the graft copolymer resin may be polymerized by a combination of these methods. Furthermore, all or a portion of the deproteinized natural rubber may be added during the polymerization.

[0055] The graft copolymer resin prepared by the above method is in a latex state. It is preferable to separate water from the latex of the graft copolymer resin and recover the graft copolymer resin. A method for separating and recovering the graft copolymer resin from the latex containing the graft copolymer resin includes, for example, a precipitation method in which a precipitating agent is added to the latex, heated and stirred, and the precipitated graft copolymer resin is separated, washed with water, dehydrated, and dried. Examples of the precipitating agent include aqueous solutions of sulfuric acid, acetic acid, calcium chloride, magnesium sulfate, etc. One precipitating agent may be used alone, or two or more precipitating agents may be used. Furthermore, an antioxidant may be added to the latex containing the graft copolymer resin, if necessary.

[0056] The graft copolymer resin composition can be prepared by, for example, mixing and melt-kneading the graft copolymer resin with various thermoplastic resins. Examples of the thermoplastic resin include polystyrene, styrene-acrylonitrile copolymer, styrene-methyl methacrylate copolymer, polymethyl methacrylate, styrene-maleic anhydride copolymer, styrene-maleimide copolymer, styrene-acrylonitrile-maleimide copolymer, rubber-reinforced polystyrene (HIPS), acrylonitrile-butadiene-styrene resin (ABS resin), acrylonitrile-ethylene propylene-styrene resin (AES resin), methyl methacrylate-butadiene-styrene resin (MBS resin), acrylonitrile-n-butyl acrylate-styrene resin (AAS resin), polycarbonate, polyamide, polybutylene terephthalate, polyethylene terephthalate, and polyolefin resins. Bioplastics and recycled resins can also be used. The graft copolymer resin composition may not contain the thermoplastic resin, and may contain only the graft copolymer resin.

[0057] When the graft copolymer resin is mixed with the thermoplastic resin to form a graft copolymer resin composition, the content of the graft copolymer resin is not particularly limited and can be appropriately adjusted taking into consideration the types of graft copolymer resin and thermoplastic resin, etc. For example, it can be 20 to 60% by mass, and preferably 30 to 55% by mass, relative to the total amount (100% by mass) of the graft copolymer resin composition. By including the graft copolymer resin, chemical resistance (particularly chemical resistance to sunscreen creams) can be exhibited.

[0058] The graft copolymer resin composition may contain other components in addition to the above-mentioned components. Examples of the other components include flow agents, fillers, heat stabilizers, antioxidants, UV absorbers, antioxidants, antistatic agents, plasticizers, lubricants, flame retardants, antibacterial agents, fluorescent brighteners, fluorescent dyes, other colorants, light diffusing agents, crystal nucleating agents, flow modifiers, impact modifiers, infrared absorbers, photochromic agents, and photocatalytic antifouling agents. The content of the other components is preferably 30% by mass or less, more preferably 10% by mass or less, and may even be 0% by mass, based on the total amount (100% by mass) of the graft copolymer resin composition.

[0059] The graft copolymer resin composition can be obtained in the form of pellets by melt-kneading the graft copolymer resin, the thermoplastic resin, and, if necessary, the other components, using a known device such as a Banbury mixer, a roll mill, a twin-screw extruder, etc. The pellets of the graft copolymer resin composition thus obtained can be molded into a desired shape by injection molding, extrusion molding, compression molding, injection-compression molding, blow molding, etc.

[0060] The graft copolymer resin composition thus obtained contains a graft copolymer resin in which an aromatic vinyl monomer and another vinyl monomer copolymerizable with the aromatic vinyl monomer are graft polymerized onto deproteinized natural rubber, and therefore uses raw materials that contribute to carbon neutrality, and can be made to have excellent impact resistance.

[0061] The present invention will be specifically described below using examples, but the present invention is not limited by these examples. Unless otherwise specified, the units of values ​​in the tables are parts by mass.

[0062] Production Example 1 Production of Copolymer (C-1) A copolymer (C-1) consisting of 74.5% by mass of styrene and 25.5% by mass of acrylonitrile was obtained by a known bulk polymerization method. The reduced viscosity of the obtained copolymer (C-1) was measured by the method described below, and was found to be 0.62 dl / g.

[0063] Example 1 Graft Copolymer Resin (A-1) A nitrogen-purged glass reactor was charged with 120 parts by mass of deionized water and 40 parts by mass (solids content) of deproteinized natural rubber (trade name "SELATEX3821", manufactured by UNIMAC RUBBER CO., LTD., nitrogen content 0.15% by mass or less), and nitrogen substitution was performed. After nitrogen substitution, the temperature inside the reactor was raised to 60°C, and when it reached 60°C, an aqueous solution prepared by dissolving 0.09 parts by mass of glucose, 0.05 parts by mass of anhydrous sodium pyrophosphate, and 0.0015 parts by mass of ferrous sulfate in 8.0 parts by mass of deionized water was added. After the temperature reached 65°C, a mixture of 45 parts by mass of styrene (ST) as an aromatic vinyl monomer and 15 parts by mass of acrylonitrile (AN) as another vinyl monomer copolymerizable with the aromatic vinyl monomer, and an emulsifier aqueous solution prepared by dissolving 1.0 part by mass of disproportionated potassium rosinate (trade name "Diplodin K-25", manufactured by Toho Chemical Industry Co., Ltd.) and 0.23 part by mass of t-butyl hydroperoxide (TBHP) in 22 parts by mass of deionized water were continuously added dropwise (continuous addition) over 6 hours. After the dropwise addition, the temperature in the vessel was raised to 70°C and the mixture was aged for 2 hours to obtain a graft copolymer resin (A-1) of Example 1 in a latex state.

[0064] Graft copolymer resin powder (B-1) Deionized water was added to a single-tank coagulation tank equipped with a stirring blade so that the slurry concentration would be 18% when 100 parts by mass of the graft copolymer resin (solid content equivalent) was added to the tank. Then, 4.5 parts by mass of magnesium sulfate and 0.80 parts by mass of sulfuric acid were added, and the temperature was raised to 94°C. After reaching 94°C, 100 parts by mass of graft copolymer resin (A-1) was added. After the addition, the temperature was raised to 97°C and maintained for 1 minute, followed by washing with water, dehydration, and drying in a hot air dryer at 85°C for 12 hours to obtain graft copolymer resin powder (B-1) of Example 1.

[0065] Graft copolymer resin powder (B-1) and copolymer (C-1) were added in the proportions shown in Table 1, and appropriate amounts of ethylene bisstearamide (EBS) and silicone oil were also added and mixed. The mixture was then melt-kneaded at 230°C using an 18 mm twin-screw extruder (trade name "TEM-18SS", manufactured by Toshiba Machine Co., Ltd.) and pelletized to obtain pellets of the graft copolymer resin composition of Example 1.

[0066] Graft copolymer resins (A-2 to A-9, A-12 to A-13) of Examples 2 to 9 and 12 to 13 in latex state were obtained in the same manner as in Example 1, except that the amounts of emulsifier, continuous addition time, disproportionated potassium rosinate, TBHP, and glucose were changed as shown in Table 1 relative to the graft copolymer resin (A-1) of Example 1.

[0067] Graft copolymer resin powders (B-2 to B-9, B-12 to B-13) Graft copolymer resin powders (B-2 to B-9, B-12 to B-13) of Examples 2 to 9 and 12 to 13 were obtained in the same manner as for graft copolymer resin powder (B-1), except that 100 parts by mass of each of graft copolymer resins (A-2 to A-9, A-12 to A-13) was added instead of graft copolymer resin (A-1).

[0068] Pellets of the graft copolymer resin compositions of Examples 2 to 9 and 12 to 13 were obtained in the same manner as in Example 1, except that the graft copolymer resin powder (B-2 to B-9, B-12 to B-13) was used instead of the graft copolymer resin powder (B-1).

[0069] Example 11, Comparative Example 1 Graft Copolymer Resins (A-11, A-15) Graft copolymer resins (A-11, A-15) of Example 11 and Comparative Example 1 in a latex state were obtained by the same production method as in Example 1 for graft copolymer resin (A-1), except that the type of emulsifier was changed to potassium oleate, and the amount of emulsifier, addition time, TBHP, and glucose were changed as shown in Table 1.

[0070] Graft copolymer resin powders (B-11, B-15) Graft copolymer resin powders (B-11, B-15) of Example 11 and Comparative Example 1 were obtained in the same manner as for graft copolymer resin powder (B-1), except that 100 parts by mass of each of graft copolymer resins (A-11, A-15) was added instead of graft copolymer resin (A-1).

[0071] Pellets of the graft copolymer resin compositions of Example 11 and Comparative Example 1 were obtained in the same manner as in Example 1, except that the graft copolymer resin powder (B-11, B-15) was used instead of the graft copolymer resin powder (B-1).

[0072] Example 10, Comparative Example 2 Graft copolymer resins (A-10, A-16) Graft copolymer resins (A-10, A-16) of Example 10 and Comparative Example 2 in a latex state were obtained by the same production method as in Example 1, except that tert-dodecyl mercaptan was used as a chain transfer agent for the graft copolymer resin (A-1), and the amounts of the emulsifier, the addition time, TBHP, and glucose were changed as shown in Table 1.

[0073] Graft copolymer resin powders (B-10, B-16) of Example 10 and Comparative Example 2 were obtained in the same manner as for graft copolymer resin powder (B-1), except that 100 parts by mass of each of graft copolymer resins (A-10, A-16) was added instead of graft copolymer resin (A-1).

[0074] Pellets of the graft copolymer resin compositions of Example 10 and Comparative Example 2 were obtained in the same manner as in Example 1, except that the graft copolymer resin powders (B-10, B-16) were used instead of the graft copolymer resin powder (B-1).

[0075] Example 14 Graft Copolymer Resin (A-14) A nitrogen-purged glass reactor was charged with 120 parts by mass of deionized water and 40 parts by mass (solids) of deproteinized natural rubber (trade name "SELATEX3821", manufactured by UNIMAC RUBBER CO., LTD., nitrogen content 0.15% by mass or less), and nitrogen substitution was performed. After nitrogen substitution, the temperature inside the reactor was raised to 60°C, and then a mixed solution of 3.75 parts by mass of acrylonitrile and 11.25 parts by mass of styrene and an aqueous solution prepared by dissolving 0.4 parts by mass of glucose, 0.1 parts by mass of anhydrous sodium pyrophosphate, and 0.001 parts by mass of ferrous sulfate in 8.0 parts by mass of deionized water were added. After the temperature reached 65°C, an emulsifier aqueous solution prepared by dissolving 0.4 parts by mass of disproportionated potassium rosinate and 0.07 parts by mass of t-butyl hydroperoxide in 5 parts by mass of deionized water was added and stirred for 30 minutes. After 30 minutes, a mixed solution of 11.25 parts by mass of acrylonitrile and 33.75 parts by mass of styrene and an emulsifier aqueous solution prepared by dissolving 1.6 parts by mass of disproportionated potassium rosinate and 0.28 parts by mass of t-butyl hydroperoxide in 20 parts by mass of deionized water were continuously added dropwise over 4 hours. After the addition, the temperature in the vessel was raised to 70°C and the mixture was aged for 2 hours to obtain graft copolymer resin (A-14).

[0076] Graft copolymer resin powder (B-14) Graft copolymer resin powder (B-14) of Example 14 was obtained in the same manner as for graft copolymer resin powder (B-1), except that 100 parts by mass of graft copolymer resin (A-14) was added instead of graft copolymer resin (A-1).

[0077] Pellets of the graft copolymer resin composition of Example 14 were obtained in the same manner as in Example 1, except that the graft copolymer resin powder (B-14) was used instead of the graft copolymer resin powder (B-1).

[0078] [Evaluation] The following evaluations were carried out on the above graft copolymer resin latex, the above graft copolymer resin powder, and the above graft copolymer resin composition pellets. The results are shown in Table 1.

[0079] (1) Amount of Aggregates (% by mass) The latexes (A-1 to A-16) of the graft copolymer resins of Examples 1 to 14 and Comparative Examples 1 and 2 were recovered by filtering through a 100-mesh wire net (wire diameter 0.1 mm, mesh size 0.154 mm, void ratio 36.5%), and the recovered material was dried at 140°C for 6 hours to obtain aggregates. The weight of the latex obtained by polymerization was designated as X, the weight of the aggregates as Y, and the amount of aggregates (%) was calculated from the following formula: Amount of Aggregates [% by mass] = {Y / (X + Y)} × 100

[0080] (2) Graft Ratio (%) Approximately 3.0 (A) g of the graft copolymer resin powder (B-1 to B-16) of Examples 1 to 14 and Comparative Examples 1 and 2 above was immersed in 40 mL of acetone overnight. The insoluble matter and the solution were then separated by centrifugation (12,000 rpm x 30 minutes). The resulting solution was reprecipitated using methanol, and the precipitate was collected by filtration. The separated insoluble matter and precipitate were vacuum-dried overnight to obtain an acetone-insoluble matter and a soluble matter. The masses of these were measured, and the mass-based yield and graft ratio were calculated using the following formula, where the mass of the acetone-insoluble matter was (a) g and the mass of the acetone-soluble matter was (b) g. Note that a yield of 95% or higher is required to calculate the graft ratio. Yield (%) = ((a + b) / A) × 100 Graft ratio (%) = (a - (a + b) × theoretical amount of rubber in A (%)) / ((a + b) × theoretical amount of rubber in A (%)) × 100

[0081] (3) Reduced Viscosity [IV] The acetone-soluble portion of each of the graft copolymer resin powders (B-1 to B-16) of Examples 1 to 14 and Comparative Examples 1 and 2 was dissolved in N,N-dimethylformamide to prepare a solution having a concentration of 0.4 g / 100 ml. The reduced viscosity [IV] was determined from the flow time measured at 30°C using a Cannon-Fenske viscometer.

[0082] (4) Impact Resistance Various test pieces were molded in accordance with ISO 294 using pellets of the graft copolymer resin compositions of Examples 1 to 14 and Comparative Examples 1 and 2, and impact resistance was measured. Impact resistance was measured in accordance with ISO 179, with a thickness of 4 mm, by notched Charpy impact value (NC).

[0083] (5) Melt Volume Flow Rate (MVR) Using pellets of the graft copolymer resin compositions of Examples 1 to 14 and Comparative Examples 1 and 2, melt volume flow rates (MVR) were measured in accordance with ISO 1133 under conditions of 220°C and a load of 10 kg.

[0084]

[0085] The graft copolymer resin compositions of Examples 1 to 14 contained a graft copolymer resin obtained by polymerizing deproteinized natural rubber with an aromatic vinyl monomer and another vinyl monomer copolymerizable with the aromatic vinyl monomer, thereby using raw materials that contribute to carbon neutrality, and were able to exhibit sufficient impact resistance and polymerize efficiently because the graft ratio was 75 to 185% and the reduced viscosity [IV] was 0.75 dl / g or less. On the other hand, efficient polymerization was not possible when the graft ratio was outside the range of 75 to 185% or when the reduced viscosity [IV] exceeded 0.75, resulting in large amounts of aggregates (Comparative Examples 1 and 2).

[0086] Variations of the present invention are described below. [Appendix 1] A graft copolymer resin composition comprising a graft copolymer resin obtained by graft-polymerizing deproteinized natural rubber with an aromatic vinyl monomer and another vinyl monomer copolymerizable with the aromatic vinyl monomer, wherein the graft copolymer resin has a graft ratio of 75 to 185%, and a reduced viscosity [IV] of 0.75 dl / g or less. [Appendix 2] The graft copolymer resin composition according to Appendices 1, wherein the graft copolymer resin has a mass ratio of the deproteinized natural rubber to the aromatic vinyl monomer and the other vinyl monomer of 30:70 to 50:50. [Appendix 3] The graft copolymer resin composition according to Appendices 1 or 2, wherein the graft ratio of the graft copolymer resin is 120 to 140%. [Appendix 4] The graft copolymer resin composition according to any one of Appendices 1 to 3, further comprising a rosin acid emulsifier. [Appendix 5] The graft copolymer resin composition according to any one of Appendices 1 to 4, wherein the amount of the aggregates is 0.5% by mass or less relative to 100% by mass of the total of the aggregates and the latex of the graft copolymer resin. [Appendix 6] A method for producing a graft copolymer resin composition, comprising a step of producing a latex of a graft copolymer resin by an emulsion polymerization method, wherein the amount of the aggregates is 0.5% by mass or less relative to 100% by mass of the total of the aggregates after polymerization and the latex of the graft copolymer resin.

Claims

1. A graft copolymer resin composition comprising a graft copolymer resin in which an aromatic vinyl monomer and another vinyl monomer copolymerizable with the aromatic vinyl monomer are graft polymerized onto deproteinized natural rubber, the graft copolymer resin having a graft ratio of 75 to 185%, and a reduced viscosity [IV] of 0.75 dl / g or less.

2. The graft copolymer resin composition according to claim 1, wherein the mass ratio of the deproteinized natural rubber to the aromatic vinyl monomer and the other vinyl monomer in the graft copolymer resin is 30:70 to 50:

50.

3. The graft copolymer resin composition according to claim 1 or 2, wherein the graft ratio of the graft copolymer resin is 120 to 140%.

4. The graft copolymer resin composition according to claim 1 or 2, which contains a rosin acid emulsifier.

5. A graft copolymer resin composition according to claim 1 or 2, wherein the amount of the aggregates is 0.5% by mass or less relative to 100% by mass of the total of the aggregates and the latex of the graft copolymer resin.

6. A method for producing a graft copolymer resin composition, comprising a step of producing a latex of a graft copolymer resin by emulsion polymerization, wherein the amount of the aggregates after polymerization is 0.5% by mass or less relative to 100% by mass of the total of the aggregates and the latex of the graft copolymer resin.

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