JP2011225791A - Rubber-modified aromatic vinyl-based resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aromatic vinyl-based resin composition which uses deproteinized natural rubber as a rubber component, and is excellent in shock resistance and the surface appearance of a molded product.SOLUTION: The rubber-modified aromatic vinyl-based resin composition contains a graft copolymer (A) which is obtained by being polymerized with a vinyl-based monomer (b) containing an aromatic vinyl compound and optionally the other monomer which can be copolymerized with the aromatic vinyl compound, under the existence of a rubber polymer (a) composed of 3 to 90 mass% of deproteinized natural rubber (a1) whose nitrogen content ratio is not higher than 0.1 mass% and 10 to 97 mass% of synthetic rubber (a2), (however, the sum of the component (a1) and the component (a2) is 100 mass%). Furthermore, the composition may contain a (co)polymer (B) of a vinyl monomer.

Description

  The present invention relates to an aromatic vinyl resin composition modified with a deproteinized natural rubber.

  Rubber-modified thermoplastic resins represented by ABS resin, AES resin, and AAS resin have excellent rigidity, impact resistance, heat distortion resistance, etc., so various miscellaneous goods, automotive interior and exterior materials, home appliances and OA equipment Widely used in housings and parts.

  Such a rubber-modified thermoplastic resin can be typically obtained by polymerizing a vinyl monomer in the presence of a rubber component. This rubber component is used for the purpose of reinforcing the resin, and various synthetic rubbers are used depending on the purpose. For example, butadiene rubber is used for ABS resin, ethylene-α-olefin rubber is used for AES resin, acrylic rubber is used for AAS resin, and rubber-modified thermoplastic resins using silicone rubber as a rubber component are also known. . Of these, ABS resins using butadiene rubber as the rubber component are the most widely used because they are relatively inexpensive, versatile and excellent in impact resistance. However, the improvement in impact resistance depending on the synthetic rubber has already reached its limit, and in order to obtain a rubber component that imparts further impact resistance, it has been required to find a method that has not been available so far.

  Natural rubber, on the other hand, is superior to various synthetic rubbers in mechanical properties and strength, and has traditionally ranged from industrial products such as automobile tires, belts, and adhesives to household items such as gloves. Used as a raw material for various rubber products. However, even if solid natural rubber is kneaded with AS resin or the like, the impact resistance is not improved due to the low dispersed particle diameter and interfacial strength of the rubber. It is also known to graft polymerize vinyl monomers to natural rubber latex, but the impurities present in natural rubber, especially proteins, inhibit the graft polymerization reaction, so that grafting is limited and high impact resistance is achieved. The effect of improving sex was not obtained.

  In recent years, technology for removing proteins from natural rubber has progressed, and various technologies using deproteinized natural rubber have been proposed. Many of them relate to applications as raw materials for various rubber products (Patent Document 1). To 4). In addition, it has already been proposed to improve the impact resistance by blending a modifier obtained by graft polymerization of a vinyl monomer with deproteinized natural rubber into polylactic acid (see Patent Document 5). ). However, in this proposal, only (meth) acrylic acid ester or vinyl acetate is used as the vinyl monomer, the graft ratio is as low as 7 to 10%, and the modification of resins other than polylactic acid is improved. No mention of quality applications.

Japanese Patent No. 2905005 JP 2002-245904 A Japanese Patent No. 4140715 JP 2005-216881 A JP 2009-84333 A

  Accordingly, an object of the present invention is to provide an aromatic vinyl resin composition modified by using deproteinized natural rubber as a rubber component, which has excellent impact resistance and surface appearance of a molded product. To do.

  As a result of diligent research for the above purpose, the present inventor has grafted an aromatic vinyl monomer to a rubber polymer obtained by mixing a deproteinized natural rubber and a synthetic rubber at a predetermined ratio. The rubber-modified aromatic vinyl resin composition obtained in this way was found to be excellent in impact resistance and molded article surface appearance, and the present invention was completed.

  Thus, according to the present invention, a rubbery polymer comprising 3 to 90% by mass of deproteinized natural rubber (a1) having a nitrogen content of 0.1% by mass or less and 10 to 97% by mass of synthetic rubber (a2). In the presence of (a) (wherein the total of component (a1) and component (a2) is 100% by mass), an aromatic vinyl compound and optionally other monomers copolymerizable with the aromatic vinyl compound A rubber-modified aromatic vinyl resin composition comprising a graft copolymer (A) obtained by polymerizing a vinyl monomer (b) is provided. The rubber-modified aromatic vinyl resin composition may further contain a (co) polymer (B) of a vinyl monomer.

  According to the present invention, a mixture containing a deproteinized natural rubber and a synthetic rubber in a predetermined ratio is used as a rubber polymer, and an aromatic vinyl monomer is graft-polymerized on the rubber polymer. Therefore, the rubber-modified aromatic vinyl resin composition having better impact resistance and surface appearance of the molded product than those obtained by using ordinary natural rubber or synthetic rubber alone as the rubbery polymer. Is obtained.

  Further, since the rubber-modified aromatic vinyl resin composition of the present invention contains carbon neutral deproteinized natural rubber as a rubber polymer, not only a graft polymer having a high graft ratio can be obtained. It is environmentally friendly and does not cause protein rot or odor problems due to ammonia treatment.

  The present invention will be described in detail below. In the present specification, “(co) polymerization” means homopolymerization and copolymerization, “(meth) acryl” means acryl and / or methacryl, and “(meth) acrylate” Means acrylate and / or methacrylate.

Ingredient (A)
The graft copolymer (A) used in the present invention comprises 3 to 90% by mass of deproteinized natural rubber (a1) having a nitrogen content of 0.1% by mass or less, and 10 to 97% by mass of synthetic rubber (a2). Can be copolymerized with an aromatic vinyl compound and, if desired, with the aromatic vinyl compound in the presence of a rubbery polymer (a) comprising a total of 100% by mass of component (a1) and component (a2) It is obtained by polymerizing a vinyl monomer (b) containing another monomer.

  The deproteinized natural rubber (a1) constituting the rubber polymer (a) is not particularly limited as long as the nitrogen content is 0.1% by mass or less.

  The deproteinized natural rubber (a1) can be obtained by removing the protein in the natural rubber latex by a known deproteinization method. Deproteinization methods include, for example, a method of degrading protein by adding a proteolytic enzyme to natural rubber latex, a method of washing natural rubber latex with a surfactant, and a modification of urea or other urea-based protein to natural rubber latex. Examples include a method of degrading proteins by adding an agent, a combination thereof, and the like. Specific examples include the methods described in JP-A-6-56902, JP-A-2004-99696, JP-A-2009-84333, and the like.

  The degree of deproteinization of natural rubber latex can be represented by the nitrogen content of natural rubber. This nitrogen content is determined by the Rubber Research Institute of Malaysia (1973), 'SMR Bulletin No. It is obtained by the Kjeldahl's method described in 7 'etc. The nitrogen content of the deproteinized natural rubber (a1) used in the present invention needs to be 0.1% by weight or less, preferably 0.08% by weight or less, more preferably 0.05% by weight or less. Particularly preferably, it is 0.03% by weight or less. If the nitrogen content of the deproteinized natural rubber is too high, the graft polymerization of the vinyl monomer will be hindered, and the effect of improving the impact resistance of the resin will not be sufficient. May be damaged. Deproteinized natural rubber has stable quality compared to normal natural rubber, has excellent thermal stability, and is resistant to spoilage, and can be stored for a long time. In addition, normal natural rubber is treated with ammonia to prevent the contained protein from decaying. However, when the ammonia-treated latex is deproteinized, most of the ammonia component is also removed at the same time. There is an advantage that the above problem does not occur.

  The volume average particle diameter (Mean volume particle diameter) of the deproteinized natural rubber (a1) used in the present invention depends on the particle diameter of the natural rubber latex used as a starting material, but is usually 20 to 25000 nm, preferably 50. It is -10000 nm, More preferably, it is 100-5000 nm, More preferably, it is 300-1500 nm, Most preferably, it is 500-1500 nm. The volume average particle diameter is preferably in this range from the viewpoint of improving impact resistance. The gel content of the component (a1) is not particularly defined, but is preferably 10 to 90%, more preferably 30 to 70%. If the gel content is within this range, a higher impact resistance improving effect can be obtained. The said component (a1) can be used individually by 1 type or in combination of 2 or more types.

  The synthetic rubber (a2) is not particularly limited, and may be a diene rubber or a non-diene rubber. Examples of the diene rubber include polybutadiene, butadiene / styrene copolymer, butadiene / acrylonitrile copolymer, and hydrogenated products thereof. Examples of the non-diene rubber include an ethylene / propylene copolymer, an ethylene / propylene / non-conjugated diene copolymer, an ethylene / 1-butene copolymer, and an ethylene / 1-butene / non-conjugated diene copolymer. Examples include ethylene-α-olefin copolymer rubber, acrylic rubber, silicone rubber, and silicone / acrylic composite rubber. Of these, polybutadiene, butadiene / styrene copolymer, acrylic rubber and silicone rubber are preferable, and polybutadiene and butadiene / styrene copolymer are more preferable. The styrene content of the butadiene / styrene copolymer is usually 30% by mass or less, preferably 20% by mass or less, and more preferably 10% by mass or less. If the styrene content is too high, the impact resistance improving effect may not be sufficient.

  The volume average particle diameter of the synthetic rubber (a2) is usually 20 to 10,000 nm, preferably 50 to 5000 nm, more preferably 80 to 2000 nm, and particularly preferably 50 to 500 nm. The volume average particle diameter is preferably in this range from the viewpoint of improving impact resistance. The gel content of the component (a2) is not particularly limited, but is preferably 10% or more, more preferably 30 to 97%, and still more preferably 50 to 95%. If the gel content is within this range, a higher impact resistance improving effect can be obtained. The said component (a2) can be used individually by 1 type or in combination of 2 or more types.

  In the present invention, the rubber polymer (a) is composed of 3 to 90% by mass of the component (a1) and 10 to 97% by mass of the synthetic rubber (a2) (however, the component (a1) and the component (a2)). Is 100% by mass). The blending ratio ((a1) / (a2)) of the component (a1) and the component (a2) is preferably 90/10 to 5/95, more preferably 70/30 to 10/90% by mass, particularly preferably. Is 50 / 50-15 / 85 mass%. When the blending ratio of the components (a1) and (a2) is within the above range, the impact resistance improving effect and the molded product surface appearance are sufficient.

The volume average particle diameter of the whole rubber polymer (a) composed of the components (a1) and (a2) is usually 100 to 1200 nm, preferably 350 to 950 nm, more preferably 400 to It is 790 nm, particularly preferably 450 to 640 nm. If this volume average particle diameter is less than 100 nm, the impact resistance improving effect may not be sufficient, and if it exceeds 1200 nm, the impact resistance improving effect or the molded product surface appearance may not be sufficient.
There is no restriction | limiting in particular in the mixing method of the said component (a1) and (a2), if both are obtained by emulsion polymerization, you may mix with latex, and component (a2) is ethylene-alpha-olefin. If it is obtained by solution polymerization such as a system copolymer rubber, it is dissolved in an organic solvent, dispersed in an aqueous dispersion together with an emulsifier, and stirred and emulsified with a homogenizer or the like, and then regenerated by a known method. After emulsification, it may be mixed with the latex of component (a1).

  The vinyl monomer (b) is composed of an aromatic vinyl compound and, if desired, another monomer copolymerizable with the aromatic vinyl compound. Among these, aromatic vinyl compounds include styrene, α-methylstyrene, other methylstyrene, vinyl xylene, monochlorostyrene, dichlorostyrene, monobromostyrene, dibromostyrene, fluorostyrene, pt-butylstyrene, ethylstyrene. , Vinyl naphthalene, and the like. These may be used alone or in combination of two or more. A preferred aromatic vinyl compound is styrene, α-methylstyrene, or an aromatic vinyl compound containing 50% by mass or more of styrene. The amount of the aromatic vinyl compound used is preferably 50 to 95% by mass, more preferably 60 to 90% by mass, and still more preferably 65 to 85% by mass with respect to the entire vinyl monomer (b). It is preferable that the amount of the aromatic vinyl compound used is within this range from the viewpoint of the moldability of the rubber-modified aromatic vinyl resin composition of the present invention and the molded appearance of the resulting molded product.

Other monomers copolymerizable with the aromatic vinyl compound include vinyl cyanide compounds such as acrylonitrile and methacrylonitrile; methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, octyl acrylate, 2 -Acrylic acid alkyl esters such as ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate; methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, dodecyl methacrylate, octadecyl methacrylate , Phenyl methacrylate Methacrylic acid alkyl esters such as benzyl methacrylate; unsaturated acid anhydrides such as maleic anhydride and itaconic anhydride; unsaturated acids such as acrylic acid and methacrylic acid; maleimide, N-methylmaleimide, N-butylmaleimide, Examples include imide compounds of α, β-unsaturated dicarboxylic acids such as N-phenylmaleimide and N-cyclohexylmaleimide, and epoxy group-containing unsaturated compounds such as glycidyl acrylate, glycidyl methacrylate and allyl glycidyl ether, preferably vinyl cyanide. A compound, alkyl acrylate ester and alkyl methacrylate ester are mentioned, More preferably, a vinyl cyanide compound and alkyl methacrylate ester are mentioned, Especially preferably, a vinyl cyanide compound is mentioned. These other monomers can be selected according to the purpose. For example, when a vinyl cyanide compound is used, chemical resistance, impact resistance, and compatibility with a polymer having polarity can be improved. it can. Further, when a methacrylic acid alkyl ester compound is used, the surface hardness and scratch resistance of the molded product can be improved. Moreover, when an imide compound of α, β-unsaturated dicarboxylic acid is used, the heat distortion resistance can be improved. These other monomers can be used individually by 1 type or in mixture of 2 or more types. The amount of these other monomers used may be in a range that does not impair the effects of the present invention, and preferably 5 to 50% by mass when the total amount of the vinyl monomer (b) is 100% by mass. More preferably, it is 10-40 mass%, More preferably, it is 15-35 mass%. If the amount of these other monomers used exceeds 50% by mass, the moldability of the composition of the present invention and the appearance of the resulting molded product may be impaired. There is a possibility that the modification effect expected to be obtained by using the monomer cannot be sufficiently obtained.
A preferred combination of the vinyl monomer (b) in the component (A) is styrene / acrylonitrile, styrene / methyl methacrylate, or styrene / acrylonitrile / methyl methacrylate.

  The content of the rubber polymer (a) in the rubber-modified aromatic vinyl resin composition is usually 5 to 40% by mass, preferably 8 to 100% by mass with respect to 100% by mass of the rubber-modified aromatic vinyl resin composition. It is 35 mass%, More preferably, it is 10-30 mass%. If the content of component (a) is outside the above range, the resulting molded article may have insufficient impact resistance.

  The graft ratio of the graft copolymer (A) is usually 20 to 100%, preferably 25 to 80%, more preferably 30 to 60%. If the graft ratio is less than 20%, the interfacial strength between the rubber and the resin may be low, and the impact resistance improving effect may not be sufficient. If the graft ratio exceeds 100%, the polymerization stability may be reduced, or the impact resistance The improvement effect may be insufficient. The graft ratio can be easily adjusted by the kind and amount of the polymerization initiator, the polymerization temperature, the amount of the monomer, and the like.

  This graft ratio (mass%) is calculated | required by following Formula (1).

  Graft ratio (% by mass) = {(TS) / S} × 100 (1)

  In the above formula (1), T is a mixture of 1 g of the graft copolymer (A) in 20 ml of acetone (acetonitrile when the rubbery polymer (a) is an acrylic rubber) and shaken with a shaker for 2 hours. Then, it is the mass (g) of insoluble matter obtained by centrifuging for 60 minutes with a centrifuge (rotation speed: 23,000 rpm) and separating the insoluble matter and the soluble matter, and S is the graft copolymer (A) Mass (g) of component (a) contained in 1 g.

  In addition, the intrinsic viscosity [η] (measured in methyl ethyl ketone) at 30 ° C. of the soluble matter of acetone of the graft copolymer (A) (acetonitrile when the rubbery polymer (a) is an acrylic rubber) is usually It is 0.2 to 1.5 dl / g, preferably 0.2 to 1.0 dl / g, more preferably 0.3 to 0.8 dl / g. If the intrinsic viscosity [η] is less than 0.2 dl / g, the impact resistance improving effect may not be sufficient, and if it exceeds 1.5 dl / g, the moldability may not be sufficient. The intrinsic viscosity [η] can be controlled by changing the type and amount of the polymerization initiator, chain transfer agent, emulsifier, solvent, and the like, as well as the polymerization time and the polymerization temperature.

  The intrinsic viscosity [η] was measured by the following method. First, acetone-soluble components separated in the graft ratio measurement were collected, dried to remove acetone, and then dissolved in methyl ethyl ketone to prepare five samples having different concentrations. It calculated | required from the result of having measured the reduced viscosity of each density | concentration using the Ubbelohde viscometer in 30 degreeC warm water. The unit is dl / g.

  The polymerization method of the graft copolymer (A) is not particularly limited, and can be carried out by emulsion polymerization, suspension polymerization, solution polymerization, bulk polymerization, or a radical graft polymerization method combining them. Among these, it is preferable to use emulsion polymerization in which the rubbery polymer (a) is supplied in a latex state. For the radical graft polymerization, usually used polymerization solvents (in the case of solution polymerization), polymerization initiators, chain transfer agents, emulsifiers (in the case of emulsion polymerization), suspending agents (in the case of suspension polymerization), etc. Can be used. Further, the vinyl monomer (b) used for producing the graft copolymer (A) is polymerized by adding monomer components all together in the presence of the total amount of the rubbery polymer (a). Alternatively, polymerization may be carried out by dividing or continuously adding. Moreover, you may superpose | polymerize by the method of combining these. Furthermore, you may superpose | polymerize by adding the whole quantity or one part of rubber-like polymer (a) in the middle of superposition | polymerization.

  The solvent used in the solution polymerization method is an inert polymerization solvent used in ordinary radical polymerization, for example, aromatic hydrocarbons such as ethylbenzene and toluene, ketones such as methyl ethyl ketone and acetone, dichloromethylene, carbon tetrachloride, etc. Organic solvents such as halogenated hydrocarbons are used. The usage-amount of a solvent is 20-200 mass parts normally with respect to 100 mass parts of total amounts of the said component (a) and component (b), Preferably it is 50-150 mass parts.

  As the polymerization initiator, a general initiator suitable for the polymerization method is used. As the polymerization initiator for solution polymerization, for example, organic peroxides such as ketone peroxide, dialkyl peroxide, diacyl peroxide, peroxy ester, hydroperoxide, t-butyl peroxyisopropyl carbonate, and the like can be used. The polymerization initiator can be added to the polymerization system all at once or continuously. The usage-amount of a polymerization initiator is 0.05-2 mass% normally with respect to a monomer component, Preferably it is 0.2-0.8 mass%.

  Examples of the polymerization initiator for emulsion polymerization include organic hydroperoxides typified by cumene hydroperoxide, t-butyl hydroperoxide, diisopropylbenzene hydroperoxide, paramentane hydroperoxide, and sugar-containing pyrroline. A redox system in combination with a reducing agent typified by an acid formulation, a sulfoxylate formulation, or a peroxide such as persulfate, azobisisobutyronitrile, benzoyl peroxide, or the like can be used. Of these, organic hydroperoxides represented by cumene hydroperoxide, t-butyl hydroperoxide, diisopropylbenzene hydroperoxide, paramentane hydroperoxide and the like, sugar-containing pyrophosphate formulation, sulfoxylate formulation A redox system in combination with a reducing agent represented by The initiator may be oil-soluble or water-soluble, and may be used in combination of oil-solubility and water-solubility. The ratio of the water-soluble initiator added in combination is usually 50% by mass or less, preferably 25% by mass or less of the total addition amount. Furthermore, the polymerization initiator can be added to the polymerization system all at once or continuously. The usage-amount of a polymerization initiator is 0.1-1.5 mass% normally with respect to a monomer component, Preferably it is 0.2-0.7 mass%.

  Examples of the chain transfer agent include mercaptans such as octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n-hexadecyl mercaptan, n-tetradecyl mercaptan, t-tetradecyl mercaptan, tetraethylthiuram sulfide, tetrachloride. Examples thereof include hydrocarbons such as carbon, ethylene bromide and pentaphenylethane, or dimer of acrolein, methacrolein, allyl alcohol, 2-ethylhexyl thioglycolate, and α-methylstyrene. These chain transfer agents can be used alone or in combination of two or more. The method of using the chain transfer agent may be any of batch addition, divided addition, or continuous addition. The usage-amount of a chain transfer agent is 0-5 mass% normally with respect to a monomer component.

  Examples of the emulsifier include anionic surfactants, nonionic surfactants, and amphoteric surfactants. Among these, examples of the anionic surfactant include higher alcohol sulfates, alkylbenzene sulfonates, fatty acid sulfonates, phosphate salts, and fatty acid salts. Further, as the nonionic surfactant, an ordinary polyethylene glycol alkyl ester type, alkyl ether type, alkylphenyl ether type, or the like is used. Further, examples of the amphoteric surfactant include those having a carboxylate, sulfate ester, sulfonate, and phosphate ester salt as the anion moiety, and an amine salt, quaternary ammonium salt, and the like as the cation moiety. The usage-amount of an emulsifier is 0.1-5 mass% normally with respect to a monomer component. In addition, the polymerization temperature in the case of graft polymerization is 10-160 degreeC normally, Preferably it is 30-120 degreeC.

  In the graft copolymer (A) obtained by polymerizing the vinyl monomer (b) in the presence of the rubber polymer (a), the vinyl monomer component is usually grafted to the rubber polymer. Copolymers and ungrafted components in which the vinyl monomer component is not grafted to the rubber polymer (that is, homopolymers and copolymers of vinyl monomer components) are included. This ungrafted component may be structurally the same as the following (co) polymer (B).

Ingredient (B)
The rubber-modified aromatic vinyl resin composition of the present invention may be a so-called graft-blend type composition containing the (co) polymer (B) in addition to the graft copolymer (A).
The (co) polymer (B) is obtained by polymerizing the vinyl monomer (b) in the absence of the rubbery polymer (a). As the vinyl monomer (b), one or more of the vinyl monomers described for the component (A) can be appropriately selected and used. It may be the same as or different from the composition of the system monomer (b). The preferred vinyl monomer (b) is composed of an aromatic vinyl compound and optionally other monomers copolymerizable with the aromatic vinyl compound. The amount of the aromatic vinyl compound used is preferably 50 to 95% by mass, more preferably 60 to 90% by mass, and still more preferably 65 to 85% by mass with respect to the entire vinyl monomer (b). It is preferable that the amount of the aromatic vinyl compound used is within this range from the viewpoint of the moldability of the rubber-modified aromatic vinyl resin composition of the present invention and the molded appearance of the resulting molded product.
A preferable combination of the vinyl monomer (b) in the component (B) is styrene / acrylonitrile, styrene / methyl methacrylate, or styrene / acrylonitrile / methyl methacrylate.

  The intrinsic viscosity [η] of component (B) (measured in methyl ethyl ketone at 30 ° C.) is usually 0.2 to 1.5 dl / g, preferably 0.2 to 1.0 dl / g, more preferably 0. .3 to 0.8 dl / g. If the intrinsic viscosity [η] is less than 0.2 dl / g, the impact resistance improving effect may not be sufficient, and if it exceeds 1.5 dl / g, the moldability may not be sufficient. The intrinsic viscosity [η] can be controlled by changing the type and amount of the polymerization initiator, chain transfer agent, emulsifier, solvent, and the like, as well as the polymerization time and the polymerization temperature.

  The intrinsic viscosity [η] was measured by the following method. First, the above component (B) was dissolved in methyl ethyl ketone to prepare 5 samples having different concentrations. It calculated | required from the result of having measured the reduced viscosity of each density | concentration using the Ubbelohde viscometer in 30 degreeC warm water. The unit is dl / g.

  There is no restriction | limiting in particular in the polymerization method of the said component (B), The said component (B) can be polymerized by the method similar to the said component (A) except not using a rubbery polymer.

Other Components The rubber-modified aromatic vinyl resin composition of the present invention may contain an additive depending on the purpose, application, etc. within the range not impairing the effects of the present invention. Such additives include flow agents, fillers, heat stabilizers, antioxidants, UV absorbers, anti-aging agents, antistatic agents, plasticizers, lubricants, flame retardants, antibacterial agents, fluorescent whitening agents, fluorescent dyes , Other colorants, light diffusing agents, crystal nucleating agents, flow modifiers, impact modifiers, infrared absorbers, photochromic agents, photocatalytic antifouling agents, polymerization initiators and the like. These can be used alone or in combination of two or more.

  Further, the rubber-modified aromatic vinyl resin composition of the present invention may be used by blending with other thermoplastic resins. Other thermoplastic resins are not particularly limited. For example, polystyrene, styrene / acrylonitrile copolymer, styrene / maleic anhydride copolymer, (meth) acrylic acid ester / styrene copolymer, and other styrene-based (co) polymers. Coalesced (but not corresponding to component (B)); rubber-modified styrenic resins such as ABS resin, AES resin, ASA resin and the like that do not contain natural rubber; ethylene, such as polyethylene, polypropylene, ethylene / propylene copolymer; Olefin (co) polymer composed of at least one kind of α-olefin having 3 to 10 carbon atoms and olefin resins such as modified polymers thereof (chlorinated polyethylene, etc.) and cyclic olefin copolymers; ionomer, ethylene / acetic acid Ethylene copolymers such as vinyl copolymers and ethylene / vinyl alcohol copolymers; From vinyl chloride resins such as vinyl chloride, ethylene / vinyl chloride copolymers, polyvinylidene chloride; (co) polymers using one or more (meth) acrylates such as polymethyl methacrylate (PMMA) Acrylic resin: Polyamide resin such as polyamide 6, polyamide 6,6, polyamide 6,12 (PA); Polyester resin such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate, polylactic acid Polyacetal resin (POM); Polycarbonate resin (PC); Polyarylate resin; Polyphenylene ether; Polyphenylene sulfide; Fluororesin such as polytetrafluoroethylene and polyvinylidene fluoride; Liquid crystal polymer; Polyimide, Polyamideimide, Polyether Imide resins such as ruimide; Ketone resins such as polyether ketone and polyether ether ketone; Sulfone resins such as polysulfone and polyethersulfone; Urethane resins; Polyvinyl acetate; Polyethylene oxide; Polyvinyl alcohol; Polyvinyl ether; Examples include butyral; phenoxy resin; photosensitive resin; biodegradable plastic. These can be used individually by 1 type or in combination of 2 or more types.

  As a method of mixing the component (A), the component (B), the additive, or the other thermoplastic resin, for example, using various extruders, Banbury mixers, kneaders, rolls, feeder ruders, etc. There is a method of kneading the components, preferably a method using an extruder or a Banbury mixer. When kneading each component, each component may be kneaded at once or may be added and kneaded in several times. The kneading may be carried out by adding in multiple stages with an extruder, kneading with a Banbury mixer, a kneader or the like, and then pelletizing with an extruder.

  EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to the following Example. “Parts” and “%” are based on mass unless otherwise specified.

<Evaluation method>
Various evaluation methods used in this example are as follows.

(1) Graft polymerization mode The latex mode during graft polymerization was visually observed and evaluated according to the following criteria.
○: Aggregates are not observed in the latex.
Δ: Aggregates are observed in the latex.
X: A large amount of aggregates is observed in the latex.

(2) Measurement of particle diameter of rubber polymer The volume average particle diameter of latex particles in the rubber polymer latex was measured at room temperature using “Microtrack UPA150” (trade name) manufactured by HONEYWELL. The unit is nm. It is known that there is no substantial difference between the latex particle diameter of the rubber polymer and the rubber particle diameter in the resin composition of the same rubber polymer, and the former agrees with the latter. To do.

(3) Measurement of gel content of rubbery polymer The rubber component was coagulated by dropping a rubbery polymer latex while stirring an aqueous solution of 5% by mass of calcium chloride. The precipitated rubber was taken out, washed thoroughly with water, chopped to a size of 2 mm square, and dried at 30 ° C. for 2 weeks using a vacuum dryer to obtain a dry rubber. A fixed amount (r) of the dried rubber was put into 100 times the amount of toluene, allowed to stand at 30 ° C. for 48 hours and immersed, and then filtered through a 200 mesh wire net to obtain an insoluble matter. It dried at 60 degreeC for 12 hours using the vacuum dryer, the insoluble content (s) was obtained, and the gel content rate was computed from the following.
Gel content (%) = (s / r) × 100

(4) Coagulation mode of graft copolymer latex The mode of the slurry (mixture of water and resin powder) at the time of coagulation was indicated by the following criteria.
○: Formation of coarse particles and turbidity of slurry due to insufficient solidification are not observed.
Δ: Some turbidity is observed in the slurry due to the formation of coarse particles and insufficient solidification.
X: There is much turbidity of slurry due to the formation of coarse particles and insufficient solidification.

(5) Graft rate Measured by the above method.

(6) Intrinsic viscosity Measured by the above method.

(7) Charpy impact strength Measured according to ISO 179. Load 2J, the unit is kJ / ^{m 2.}

(8) Surface appearance of molded product Using an electric injection molding machine “Erject NEX80” (trade name) manufactured by Nissei Plastic Industry Co., Ltd., a flat molded product of 80 mm × 55 mm × 2.4 mm was obtained by injection molding. . The molding temperature was 220 ° C and the mold temperature was 50 ° C. The surface of the obtained molded product was visually observed, and the determination result was displayed according to the following criteria.
○: Good surface appearance. Flow marks are not allowed.
Δ: Surface appearance is somewhat inferior. Some flow marks are recognized.
X: The surface appearance is inferior. A flow mark is allowed.

(9) Low-temperature impact fracture mode Using a high-speed impact tester, HITS-P10, manufactured by Shimadzu Corporation, using a flat-plate molded product with a thickness of 2.4 mm and a striking rod with a pedestal punch diameter of 12.7 mm and a tip R of 12.7 mm The fracture mode when the product was punched was observed under the test condition of 0 ° C. The mode of destruction was indicated by the following criteria.
○: The punched part was destroyed in a ductile manner.
Δ: Ductile breakage, but cracked in the orientation method of the resin molded product.
X: The punched portion penetrated brittlely.

Production Example 1 ( Production of Deproteinized Natural Rubber Latex (a1))
High ammonia latex (HA latex, Kjeldahl's method) with a rubber concentration of 60.2 wt% and ammonia content of 0.7 wt% manufactured by Soctech (Malaysia) as a natural rubber latex, 0.38 %, Hereinafter also referred to as “HANR”), and this was diluted so that the rubber concentration was 30% by weight. 1.0 part by weight of anionic surfactant sodium lauryl sulfate (SLS) was added to 100 parts by weight of the rubber content of the latex to stabilize the latex. Next, 0.2 parts by weight of urea was added as a protein modifying agent to 100 parts by weight of the rubber content of the latex, and the protein was subjected to protein modification treatment by allowing to stand at 60 ° C. for 60 minutes.

  The latex that had been subjected to the protein denaturation treatment was centrifuged at 13000 rpm for 30 minutes. The upper cream thus separated was dispersed in a 1% aqueous solution of a surfactant so that the rubber concentration was 30%, and the second centrifugation treatment was performed in the same manner as described above. Furthermore, deproteinized natural rubber latex (a1) was obtained by redispersing the obtained cream in a 1% aqueous solution of a surfactant. The resulting natural rubber particles had a volume average particle size of 990 nm and a gel content of 55%. The amount of protein contained in this rubber was 0.028% in terms of nitrogen content (N%) by the Kjeldahl method.

Production Example 2 ( Production of Diene Synthetic Rubber Latex (a2-1))
After replacing the inside of a 10 L capacity pressure vessel equipped with a stirrer, raw material and auxiliary agent addition device, thermometer, heating device, etc. with nitrogen, 100 parts of water, 100 parts of 1,3-butadiene, t-dodecyl mercaptan. 3 parts, potassium persulfate 0.3 part, higher fatty acid sodium soap 0.5 part, disproportionated potassium rosinate 1.5 part, β-naphthalenesulfonic acid formalin condensate sodium salt 0.15 part, carbonic acid as electrolyte After charging 1 part of sodium hydride and reacting at 50-70 ° C. for 40 hours with stirring, the reaction was terminated by cooling to obtain a diene synthetic rubber latex (a2-1). At this time, the polymerization conversion was 95%, the volume average particle diameter was 300 nm, and the gel content was 80%.

Production Example 3 ( Production of Styrene-Butadiene Synthetic Rubber Latex (a2-2))
After replacing the inside of the same reactor used in Production Example 2 with nitrogen, water 200 parts, 1,3-butadiene 90 parts, styrene 10 parts, t-dodecyl mercaptan 0.3 parts, potassium persulfate 0 .3 parts, 3 parts of higher fatty acid sodium soap, 0.1 part of disproportionated potassium rosinate, 0.05 part of sodium salt of β-naphthalene sulfonic acid formalin condensate, 1 part of sodium pyrophosphate as electrolyte, stirred While reacting at 50 to 70 ° C. for 20 hours, the reaction was terminated by cooling. At this time, the polymerization conversion was 95%, the volume average particle diameter was 90 nm, and the gel content was 90%. When the completion of the reaction was confirmed, the internal temperature was raised again to 40 ° C. while stirring. When the internal temperature reached 40 ° C., a suspension obtained by dispersing 2 parts of acetic anhydride in 40 parts of water with a homogenizer was charged into the reactor, and stirring was stopped while maintaining the internal temperature of the reactor at 40 ° C. The particle size was enlarged. After 10 minutes of particle size enlargement treatment, an aqueous solution in which 1.5 parts of potassium hydroxide is dissolved in 28.5 parts of water, and a sodium salt of β-naphthalenesulfonic acid formalin condensate in 22.5 parts of water. An aqueous solution in which 5 parts were dissolved was added and stirred to complete the enlargement treatment, thereby obtaining an enlarged synthetic rubber latex (a2-2). The resulting synthetic rubber particles had a volume average particle diameter of 700 nm.

Example 1 (Composite Rubber Graft Copolymer (A1))
A vinyl monomer (b) was prepared by mixing 45 parts of styrene (ST), 15 parts of acrylonitrile (AN) and 0.25 part of t-dodecyl mercaptan. Also, a solution in which 0.25 part of sodium pyrophosphate, 0.35 part of dextrose, and 0.005 part of ferrous sulfate were dissolved in 10 parts of water (hereinafter abbreviated as “RED aqueous solution-1”) was prepared. did. Furthermore, an aqueous solution (hereinafter abbreviated as “OXI aqueous solution-1”) in which 1 part of disproportionated potassium rosinate and 0.3 part of diisopropylbenzene hydroperoxide were dissolved in 10 parts of water was prepared. Next, 220 parts of water and 6 parts of the above deproteinized natural rubber latex (a1) in terms of solid content were added to a 10 L glass reactor equipped with a stirrer, raw material and auxiliary agent addition device, thermometer, heating device and the like. And 34 parts of synthetic rubber latex (a2-1) in terms of solid content, and further 0.25 parts of disproportionated potassium rosinate and 0.75 parts of sodium salt of β-naphthalenesulfonic acid formalin condensate were added. The internal temperature was raised to 40 ° C. with stirring under a nitrogen stream. When the temperature reached 40 ° C., 85% by mass of RED aqueous solution-1 was added to the reactor. Immediately thereafter, the vinyl monomer (b) and 85 mass% equivalent of OXI aqueous solution-1 were continuously added over 5 hours to proceed the reaction. The internal temperature was raised to 60 ° C. from the start of polymerization, and then maintained at this temperature. Five hours after the start of polymerization, the remaining 15% by mass of RED aqueous solution-1 and the remaining 15% by mass of OXI aqueous solution-1 were added to the reactor and held at the same temperature for 1 hour. Later the polymerization was terminated. This copolymer latex was coagulated, washed with water and dried to obtain a powdery composite rubber graft copolymer (A1). Table 1 shows the particle diameter, polymerization mode, coagulation mode, graft ratio, and intrinsic viscosity of the entire rubber polymer.
The particle size of the entire rubber polymer is uniform between 6 parts of the deproteinized natural rubber latex (a1) in terms of solid content and 34 parts of the synthetic rubber latex (a2-1) in terms of solid content. It was obtained by separately preparing a latex mixture mixed with and subjecting the mixture to measurement.
Examples 2-4, Comparative Examples 1-4
Polymerization was carried out in the same manner as in Example 1 except that the formulation shown in Table 1 was used, to obtain a graft copolymer latex. Here, in Comparative Example 2, polymerization was performed using the high ammonia latex (HANR) used in Production Example 1 as it was instead of the deproteinized natural rubber latex (a1), and the polymerization state was poor. A large amount of agglomerates were generated therein, and polymerization was extremely difficult, but a latex of a graft copolymer was obtained. These latexes were coagulated, washed with water and dried to obtain a powdered graft copolymer. Table 1 shows the results of the particle size, polymerization mode, coagulation mode, graft ratio, and intrinsic viscosity of the entire rubber polymer.
In addition, the particle diameter of the whole rubber polymer was obtained by separately preparing a latex mixture in which the rubber latex having the composition shown in Table 1 was uniformly mixed, and subjecting the mixture to measurement, as in Example 1.

Test Example (Performance Evaluation of Resin Composition (Examples 1-4, Comparative Examples 1-4)
Further, the graft copolymers obtained in Examples 1 to 4 and Comparative Examples 1 to 4, the AS resin, and the antioxidant were charged into a Henschel mixer at the blending ratio shown in Table 1 and mixed. Then, using a single screw extruder (model name “DMG type 40 mm Magic Vent Extruder”, manufactured by Nippon Placon Co., Ltd.), melt kneading at a temperature of 160 to 220 ° C. and pellets (rubber-modified aromatic vinyl resin composition) Product). The various evaluations described above were performed using this pellet. The results are shown in Table 1. In addition, the abbreviation of AS resin and antioxidant of Table 1 means the following.
(C) AS resin (acrylonitrile / styrene copolymer)
C1: AS resin “Sunrex SAN-C” (trade name) manufactured by Techno Polymer Co., Ltd.
(D) Antioxidant (stabilizer)
D1: Phosphorous antioxidant “JP-650” (trade name) manufactured by Johoku Chemical Industry Co., Ltd. (Tris (2,4-di-t-butylphenyl) phosphite)
D2: Phenol antioxidant “Irganox 1010” (trade name) (pentaerythrityl tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate]) manufactured by Ciba Specialty Chemicals

As is clear from the results in Table 1, the composite rubber graft copolymers of Examples 1 to 4 in which deproteinized natural rubber latex and synthetic rubber are used in a predetermined ratio are excellent in polymerization mode and coagulation mode. The composition using the graft copolymer has high impact strength, and is excellent in a low-temperature impact fracture mode and a molded product surface appearance.
The copolymer (B-1) of Comparative Example 1 has a low synthetic rubber content outside the scope of the present invention, but the composition using this has low impact strength and low temperature impact fracture. The situation is also bad.
The copolymer (B-2) of Comparative Example 2 is an example using natural rubber that has not been deproteinized, but it is inferior in the polymerization mode at the time of graft polymerization and is slightly worse in the coagulation mode. Has a very low impact strength, a low-temperature impact fracture mode and a molded product surface appearance.
The copolymers of Comparative Examples 3 and 4 are examples in which a synthetic rubber is used alone as a rubbery polymer, but a composition using these has a lower impact strength than the composition of the present invention. .

  The rubber-modified aromatic vinyl resin composition of the present invention is superior to conventional rubber-modified aromatic vinyl resin compositions in impact resistance, molded product surface appearance, and the like. It can be used as a molding material for molded products that require high impact resistance such as housings and parts of home appliances and OA equipment.

Claims (7)

  A rubbery polymer (a) comprising 3 to 90% by mass of deproteinized natural rubber (a1) having a nitrogen content of 0.1% by mass or less and 10 to 97% by mass of synthetic rubber (a2) (however, the component ( a vinyl monomer comprising an aromatic vinyl compound and optionally another monomer copolymerizable with the aromatic vinyl compound in the presence of a1) and component (a2) is 100% by mass) A rubber-modified aromatic vinyl resin composition comprising a graft copolymer (A) obtained by polymerizing the body (b).   The rubber-modified aromatic vinyl resin composition according to claim 1, further comprising a (co) polymer (B) of a vinyl monomer.   The rubber-modified aromatic vinyl resin composition according to claim 1 or 2, wherein the content of the rubber polymer (a) is 5 to 40 parts by mass with respect to 100 parts by mass of the rubber-modified aromatic vinyl resin composition. object.   The rubber-modified aromatic vinyl resin composition according to any one of claims 1 to 3, wherein the nitrogen content of the component (a1) is 0.05% by mass or less.   The rubber-modified aromatic vinyl resin composition according to any one of claims 1 to 4, wherein the component (a) has a volume average particle diameter of 100 to 1200 nm.   The rubber-modified aromatic vinyl resin composition according to any one of claims 1 to 5, wherein the volume average particle diameter of the component (a1) is 300 to 1500 nm.    A molded article comprising the rubber-modified aromatic vinyl resin composition according to any one of claims 1 to 6.