JP2006096830A - Rubber composition and molded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition having excellent moldability, extremely excellent mechanical properties and good low-temperature characteristics and oil resistance. <P>SOLUTION: The composition having excellent moldability, extremely excellent mechanical properties and good low-temperature characteristics and oil resistance is composed of (A) a nitrile rubber and (B) a polyorganosiloxane graft polymer. The composition has excellent moldability and the obtained molded article has good mechanical properties, low-temperature characteristics and oil resistance. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rubber composition comprising a nitrile rubber having both low temperature characteristics and oil resistance and a polyorganosiloxane graft polymer.

  Nitrile rubber is known as a copolymer (NBR) composed of acrylonitrile and butadiene, and has excellent heat resistance, oil resistance and compression set resistance. Widely used for packing, gaskets, etc. However, generally, there is a problem of embrittlement at a low temperature, and further improvement of the low temperature characteristics has been desired.

  Although the addition of a plasticizer is known as an effective method for the above-mentioned problem of low temperature embrittlement of nitrile rubber, there are cases where mechanical properties are deteriorated and there is a risk of bleeding of the plasticizer. It was.

  It is also known that among nitrile rubber copolymer components, increasing the amount of butadiene improves embrittlement at low temperatures, but there is a problem that the oil resistance decreases as the amount of butadiene increases. It was.

On the other hand, silicone (polyorganosiloxane) is known as a material excellent in cold resistance and the like, and a technique for adding it to nitrile rubber and imparting its characteristics is disclosed (Patent Document 1). However, silicone is inherently a material that does not mix with other organic rubbers, and it is difficult to disperse silicones well in nitrile rubber, and the amount of addition is limited, giving the silicone characteristics sufficiently. In addition, there was a risk of physical deterioration and bleeding. (See Patent Document 1)
JP-A-56-76441

  An object of the present invention is to develop a composition comprising a nitrile rubber and a polyorganosiloxane-based graft polymer, which are excellent in molding processability, excellent in mechanical properties, and have both low temperature characteristics and oil resistance.

  As a result of intensive studies to solve the above problems, the present inventors have found that a rubber composition comprising (A) a nitrile rubber and (B) a polyorganosiloxane-based graft polymer has low temperature characteristics and oil resistance. And it discovered that it was excellent in mechanical physical properties, and came to complete this invention. That is, this invention is based on the following structures.

  A rubber composition comprising (A) a nitrile rubber and (B) a polyorganosiloxane-based graft polymer (Claim 1).

  The rubber composition according to claim 1, comprising (A) 50 to 98% by weight of nitrile rubber and (B) 50 to 2% by weight of a polyorganosiloxane-based graft polymer.

  (B) The polyorganosiloxane graft polymer is a polyorganosiloxane graft polymer having a graft component content of 5 to 40% by weight and a polyorganosiloxane content of 95 to 60% by weight. The rubber composition according to 1 or 2 (Claim 3).

  (B) A polyorganosiloxane-based graft polymer having an alkyl methacrylate content of 5 to 99.5% by weight and an alkyl acrylate content of 95 to 0.5% by weight in the entire graft component of the polyorganosiloxane-based graft polymer. The rubber composition according to any one of claims 1 to 3, wherein the rubber composition is a coalescence (claim 4).

  The rubber composition according to any one of claims 1 to 4, wherein the polyorganosiloxane-based graft polymer (B) is obtained by seed polymerization.

  The rubber composition according to any one of claims 1 to 5, wherein the polyorganosiloxane-based graft polymer (B) is polymerized using a mercapto group-containing compound as a graft crossing agent (claim 6).

  The rubber composition according to any one of claims 1 to 6, wherein the polyorganosiloxane-based graft polymer (B) is polymerized using a polyfunctional monomer (claim 7).

The molded object which consists of a rubber composition of any one of Claim 1 to 7 (Claim 8).

  The rubber composition can provide a material having excellent low-temperature characteristics, oil resistance, and mechanical properties.

  Below, the composition of this invention is demonstrated in detail. The rubber composition of the present invention is a rubber composition comprising (A) a nitrile rubber and (B) a polyorganosiloxane-based graft copolymer.

  The nitrile rubber (A) in the present invention is known as a copolymer (NBR) composed of acrylonitrile and butadiene, and these can be widely used. It is also possible to use nitrile rubber (HNBR) obtained by hydrogenating unsaturated bonds in the molecule of nitrile rubber, those obtained by copolymerizing components other than acrylonitrile and butadiene, those introduced with a functional group, and the like. These nitrile rubbers are generally vulcanized using a vulcanizing agent, a vulcanization accelerator, a vulcanization aid, and the like, thereby making it possible to obtain rubber materials that are further excellent in various properties. The vulcanizing agent, vulcanization accelerator, vulcanization aid, etc. used in the present invention are not particularly limited, and various known compounds can be widely used.

  As the nitrile rubber, those having an acrylonitrile amount of about 10 to 50% are widely used. Particularly, nitrile rubber having a large amount of acrylonitrile, for example, 25% or more, and further 30% or more, is excellent in oil resistance, but is said to be particularly inferior in cold resistance. By combination, it is possible to greatly improve the cold resistance which is the subject.

  Next, the polyorganosiloxane graft polymer (B) in the present invention will be described. The polyorganosiloxane graft polymer is blended and dispersed in the nitrile rubber which is the matrix resin of the composition. Even if it is below the embrittlement temperature of rubber | gum alone which is matrix resin, destruction by embrittlement does not occur and it becomes possible to express favorable low-temperature characteristics. In addition, low temperature properties such as elastic recovery characteristics at low temperatures (TR characteristics) and low temperature torsion characteristics (Geman torsion characteristics) can be improved, and low temperature elastic recovery temperature and tensile permanent strain characteristics at low temperatures can be achieved. It is possible to improve.

  The composition of the polyorganosiloxane-based graft polymer (B) is not particularly limited, but 0 to 10% by weight of the monomer (d2) is polymerized in the presence of 60 to 95% by weight of the polyorganosiloxane (d1). Furthermore, a copolymer obtained by polymerizing 5 to 40% by weight of the vinyl monomer (d3) (100% by weight in total of (d1), (d2) and (d3)) is preferable. The monomer (d2) is composed of 50 to 100% by weight of a polyfunctional monomer (x) containing two or more polymerizable unsaturated bonds in the molecule, and other copolymerizable vinyl monomers ( y) A monomer composed of 0 to 50% by weight.

  Furthermore, it is preferable that the content of the graft component combining the monomer (d2) and the vinyl monomer (d3) is 5 to 40% by weight and the polyorganosiloxane content is 95 to 60% by weight. In particular, it is more preferably 95 to 75% by weight.

  The polyorganosiloxane (d1) used in the present invention is not particularly limited in its production method, and can be obtained by ordinary emulsion polymerization. However, seed polymerization is also used because of the advantage that the particle size distribution in the latex state can be narrowed. Can do. The seed polymer used for seed polymerization is not limited to rubber components such as butyl acrylate rubber, butadiene rubber, butadiene-styrene and butadiene-acrylonitrile rubber, but butyl acrylate-styrene copolymer, styrene-acrylonitrile copolymer, etc. The polymer may be used.

  A chain transfer agent may be used for the polymerization of the seed polymer. In the polymerization of the polyorganosiloxane (d1), a graft crossing agent and, if necessary, a crosslinking agent can be used. In the production of polyorganosiloxane, the particle size distribution can be controlled to be small by using seeds, and when used in the composition of the present invention, the properties of the resulting molded product, for example, low temperature characteristics and tensile properties are greatly improved. preferable. The amount of the seed polymer used in the polymerization of the seed is preferably 0.1 to 10% by weight based on the organosiloxane used.

The organosiloxane specifically used is represented by the general formula R _m SiO _{(4-m) / 2} (wherein R is a substituted or unsubstituted monovalent hydrocarbon group, and m is an integer of 0 to 3). And has a linear, branched or cyclic structure, and an organosiloxane having a cyclic structure is preferred from the viewpoint of availability and cost. Examples of the substituted or unsubstituted monovalent hydrocarbon group of the organosiloxane include a methyl group, an ethyl group, a propyl group, a phenyl group, and a substituted hydrocarbon group obtained by substituting them with a cyano group. it can.

  Specific examples of the organosiloxane include hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), dodecamethylcyclohexasiloxane (D6), and trimethyltriphenylcyclotrisiloxane. In addition to cyclic compounds such as these, linear or branched organosiloxanes can be mentioned. At least one of these organosiloxanes can be used.

  Examples of the graft crossing agent that can be used in the present invention include p-vinylphenylmethyldimethoxysilane, p-vinylphenylethyldimethoxysilane, 2- (p-vinylphenyl) ethylmethyldimethoxysilane, and 3- (p-vinylbenzo Iroxy) propylmethyldimethoxysilane, p-vinylphenylmethyldimethoxysilane, vinylmethyldimethoxysilane, tetravinyltetramethylcyclosiloxane, allylmethyldimethoxysilane, mercaptopropylmethyldimethoxysilane, mercaptopropyltrimethoxysilane, mercaptopropyltriethoxysilane , (Meth) acryloxypropylmethyldimethoxysilane, (meth) acryloxypropyltrimethoxysilane, (meth) acryloxypropyltriethoxysilane, etc. And the like. The proportion of the grafting agent used is preferably 0.1 to 10% by weight based on the organosiloxane.

  If the amount of the grafting agent used is more than 10% by weight, the low-temperature properties (especially impact resistance) of the final molded product may be deteriorated. If the amount of the grafting agent used is less than 0.1% by weight, solidification / heat treatment is performed. Sometimes a large lump is formed and a decent resin powder cannot be obtained, or the workability of the final molded body may be lowered.

  In the synthesis of the polyorganosiloxane (d1) used in the present invention, a crosslinking agent can be added if necessary. Examples of the crosslinking agent include trifunctional crosslinking agents such as methyltrimethoxysilane, phenyltrimethoxysilane, and ethyltriethoxysilane, tetraethoxysilane, 1,3bis [2- (dimethoxymethylsilyl) ethyl] benzene, 1,4-bis [2- (dimethoxymethylsilyl) ethyl] benzene, 1,3-bis [1- (dimethoxymethylsilyl) ethyl] benzene, 1,4-bis [1- (dimethoxymethylsilyl) ethyl] benzene 1- [1- (dimethoxymethylsilyl) ethyl] -3- [2- (dimethoxymethylsilyl) ethyl] benzene, 1- [1- (dimethoxymethylsilyl) ethyl] -4- [2-dimethoxymethylsilyl] And tetrafunctional cross-linking agents such as ethyl] benzene.

  At least one kind of these crosslinking agents can be used. The addition amount of the crosslinking agent is preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the organosiloxane. When the addition amount of the crosslinking agent is more than 10 parts by weight, the flexibility of the polyorganosiloxane (d1) is impaired, and the impact resistance at low temperature of the rubber material obtained from the rubber composition may be lowered.

  The average particle diameter of the latex polyorganosiloxane (d1) is preferably 0.008 to 0.6 μm, and more preferably 0.08 to 0.4 μm. It is difficult to stably obtain those having an average particle diameter of less than 0.008 μm, and if it exceeds 0.6 μm, the impact resistance of the final molded product may be deteriorated.

  Specific examples of the polyfunctional monomer (x) include allyl methacrylate, ethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, divinylbenzene and the like. At least one of these can be used.

  Specific examples of the copolymerizable monomer (y) include aromatic vinyl monomers such as styrene and α-methylstyrene, vinyl cyanide monomers such as acrylonitrile, methyl acrylate, and acrylic acid. Examples thereof include (meth) acrylic acid ester monomers such as ethyl, methyl methacrylate, ethyl methacrylate and butyl methacrylate, and vinyl monomers containing an epoxy group in the molecule such as glycidyl methacrylate. At least one of these can be used.

    The monomer (d2) composed of the monomer (y) copolymerizable with the polyfunctional monomer (x), particularly, contains the polysiloxane (d1) in the polyorganosiloxane-based graft polymer (B). When the amount is as high as 75% by weight or more, the graft polymer resin can be powdered.

  Further, as the graft crossing agent used for the component (d1), generally, a graft crossing agent that is insufficient in grafting efficiency at the time of graft polymerization of the vinyl monomer (d3) described below, specifically, for example, In the case of using a mercapto group-containing compound such as mercaptopropylmethyldimethoxysilane described in JP-A-60-252613, the use of the component (d2) contributes to the grafting of the vinyl monomer (d3). It is possible to greatly reduce the polymer component (free polymer component) that does not, and more efficient graft polymerization. Due to such effects, it is possible to effectively improve the physical properties of the molded article obtained from the rubber composition according to the present invention, for example, low temperature characteristics and tensile characteristics.

  As the monomer (d2), the polyfunctional monomer (x) is preferably 50 to 100% by weight, more preferably 90 to 100% by weight, and the copolymerizable monomer (y) is preferably 0 to 100% by weight. It is preferably 50% by weight, more preferably 0 to 10% by weight.

  The amount of the monomer (d2) used is preferably 0 to 10% by weight, more preferably 0.5 to 10% by weight in the polyorganosiloxane-based graft polymer (B). The more the amount used, the better the state of the powder, but if it exceeds 10% by weight, the low-temperature properties (especially impact resistance) of the final molded product may deteriorate.

  The vinyl monomer (d3) used in the present invention ensures compatibility between the polyorganosiloxane graft polymer (B) and the nitrile rubber (A), and makes the polyorganosiloxane graft polymer (B) uniform. It is a component used to disperse in. Specific examples of the monomer include the same monomers as the other copolymerizable monomer (y).

  Specifically, aromatic vinyl monomers such as styrene and α-methylstyrene, vinyl cyanide monomers such as acrylonitrile, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, methacrylic acid (Meth) acrylic acid ester monomers such as methyl, ethyl methacrylate and butyl methacrylate, vinyl monomers containing an epoxy group in the molecule such as glycidyl methacrylate, ethylenic unsaturation such as methacrylic acid and acrylic acid Examples thereof include carboxylic acids, and at least one of them can be used. Here, the vinyl monomer (d3) is selected so that the solubility parameter value of the polymer obtained by polymerizing the vinyl monomer (d3) is close to the solubility parameter value of the nitrile rubber that is the matrix resin. It is preferable to do.

  By selecting the solubility parameter of the polymer obtained by polymerizing the vinyl monomer (d3) to be close to the solubility parameter of the nitrile rubber, the polyorganosiloxane graft copolymer in the rubber is selected. The dispersion state of the polymer is excellent, and the low temperature characteristics of the molded body can be greatly improved. On the other hand, if the solubility parameter value is too different, the dispersion state of the polyorganosiloxane graft copolymer is not excellent, and the polyorganosiloxane graft polymer once dispersed may be re-aggregated. It becomes difficult to impart excellent low-temperature characteristics by the siloxane-based graft copolymer.

  When (meth) acrylic acid ester monomers are used as the component (d3), the alkyl methacrylate content is 5 to 99.5% by weight, further 5 to 97% by weight, alkyl acrylate. The content is preferably 95 to 0.5% by weight, more preferably 95 to 3% by weight. When the alkyl methacrylate content is more than 99.5% by weight, the heat resistance may decrease due to thermal decomposability.

  When further heat resistance is required, it is preferable that 0.5 to 10% by weight of methacrylic acid or acrylic acid is contained in the entire graft component of the polyorganosiloxane graft polymer.

  Specific examples of the radical initiator used in the production of the polyorganosiloxane (d1) of the present invention include organic peroxides such as cumene hydroperoxide, t-butyl hydroperoxide, benzoyl peroxide, and t-butyl peroxyisopropyl carbonate. And inorganic peroxides such as potassium persulfate and ammonium persulfate, and azo compounds such as 2,2′-azobisisobutyronitrile and 2,2′-azobis-2,4-dimethylvaleronitrile. Redox such as ferrous sulfate-sodium formaldehydesulfoxylate-ethylenediaminetetraacetic acid 2Na salt, ferrous sulfate-glucose-sodium pyrophosphate, ferrous sulfate-sodium pyrophosphate-sodium phosphate When performed in the system, the polymerization is completed even at a low polymerization temperature.

  The method for separating the polymer from the polyorganosiloxane graft copolymer (B) latex obtained by emulsion polymerization is not particularly limited. For example, a metal salt such as calcium chloride, magnesium chloride or magnesium sulfate is added to the latex. Examples of the method include coagulation, separation, water washing, dehydration, and drying of the latex. A spray drying method can also be used.

  Regarding the content of the nitrile rubber (A) and the polyorganosiloxane graft polymer (B), the nitrile rubber (A) is 50 to 98% by weight, more preferably 65 to 97% by weight in the whole rubber composition. The siloxane-based graft polymer (B) is preferably 50 to 2% by weight, more preferably 35 to 3% by weight (100% by weight in total of A and B). If the content of the polyorganosiloxane-based graft polymer (B) is more than 50% by weight, the oil resistance may be lowered. If the content is less than 2% by weight, the low-temperature characteristics may be insufficiently improved.

  A lubricant, an inorganic filler, and a thermoplastic resin can be blended with the rubber composition of the present invention. As for the blending amount, a preferable range is 0.1 to 10 parts by weight of a lubricant, 0.1 to 100 parts by weight of an inorganic filler, and 0.1 to 100 parts by weight of a thermoplastic resin with respect to 100 parts by weight of the rubber composition. And a thermoplastic resin composition is obtained. These thermoplastic resin compositions improve the strength and molding processability of a molded product obtained by molding the rubber composition of the present application.

  Examples of the lubricant include fatty acids such as stearic acid and palmitic acid, fatty acid metal salts such as calcium stearate, zinc stearate, magnesium stearate, potassium palmitate and sodium palmitate, polyethylene wax, polypropylene wax, and montanic acid wax. Waxes, low molecular weight polyolefins such as low molecular weight polyethylene and low molecular weight polypropylene, polyorganosiloxanes such as dimethylpolysiloxane, octadecylamine, alkyl phosphates, fatty acid esters, amide-based lubricants such as ethylenebisstearylamide, 4-fluoride Fluorine resin powder such as ethylene resin, molybdenum disulfide powder, silicone resin powder, silicone rubber powder, silica, etc. are mentioned, but it is not limited to these.

  These may be used alone or in combination of two or more. Of these, stearic acid, zinc stearate, calcium stearate, magnesium stearate, and ethylene bisstearyl amide are preferable from the viewpoint of low friction and processability on the resin surface.

  Examples of inorganic fillers include titanium oxide, zinc sulfide, zinc oxide, carbon black, calcium carbonate, calcium silicate, clay, kaolin, silica, mica powder, alumina, glass fiber, metal fiber, potassium titanate whisker, and water. Examples include, but are not limited to, lastnite, mica, talc, glass flake, milled fiber, and metal powder. These may be used alone or in combination. Among these, carbon black and titanium oxide are preferable from the viewpoint of high elastic modulus and silica and weather resistance and pigment.

  Examples of the thermoplastic resin include polyvinyl chloride resin, polyethylene resin, polypropylene resin, cyclic olefin copolymer resin, polymethyl methacrylate resin, polystyrene resin, polyphenylene ether resin, polycarbonate resin, polyester resin, Examples thereof include polyamide resins, polyacetal resins, polyphenylene sulfide resins, polysulfone resins, polyimide resins, polyetherimide resins, polyetherketone resins, polyetheretherketone resins, polyamideimide resins, and imidized polymethylmethacrylate resins. These may be used alone or in combination of two or more.

  The composition of the present invention further includes stabilizers (anti-aging agents, light stabilizers, UV absorbers, etc.), flexibility imparting agents, flame retardants, mold release agents, antistatic agents, antibacterial agents, depending on the required properties. A mold agent or the like may be added. These additives may be appropriately selected and used according to the required physical properties, workability, and the like.

  Examples of stabilizers (anti-aging agent, light stabilizer, ultraviolet absorber, etc.) include, but are not limited to, the following compounds.

  Anti-aging agents include phenyl α-naphthylamine (PAN), octyl diphenylamine, N, N′-diphenyl-p-phenylenediamine (DPPD), N, N′-di-β-naphthyl-p-phenylenediamine ( DNPD), N- (1,3-dimethyl-butyl) -N′-phenyl-p-phenylenediamine, N-phenyl-N′-isopropyl-p-phenylenediamine (IPPN), N, N′-diallyl-p -Phenylenediamine, phenothiazine derivative, diallyl-p-phenylenediamine mixture, alkylated phenylenediamine, 4,4'-α, α-dimethylbenzyldiphenylamine, p, p-toluenesulfonylaminodiphenylamine, N-phenyl-N '-( 3-methacryloyloxy-2-hydropropyl) -p-pheny Diamine, diallylphenylenediamine mixture, diallyl-p-phenylenediamine mixture, N- (1-methylheptyl) -phenyl-p-phenylenediamine, amine-based antioxidants such as diphenylamine derivatives, 2-mercaptobenzimidazole (MBI) ) Imidazole anti-aging agents, phenolic anti-aging agents such as 2,6-di-t-butyl-4-methylphenol, phosphate anti-aging agents such as nickel diethyl-dithiocarbamate, triphenyl phosphite Secondary anti-aging agents such as

  Examples of light stabilizers and ultraviolet absorbers include 4-t-butylphenyl salicylate, 2,4-dihydroxybenzophenone, 2,2′dihydroxy-4-methoxybenzophenone, ethyl-2-cyano-3,3′-diphenyl. Acrylate, 2-ethylhexyl-2-diano-3,3′-diphenyl acrylate, 2-hydroxy-5-chlorobenzophenone, 2-hydroxy-4-methoxybenzophenone-2-hydroxy-4-octoxybenzophenone, monoglycol salicy Rate, oxalic acid amide, 2,2 ′, 4,4′-tetrahydroxybenzophenone and the like. These stabilizers may be used alone or in combination of two or more.

  Examples of the flexibility-imparting agent include plasticizers, softeners, oligomers, oils (animal oil, vegetable oil, etc.) usually used in thermoplastic resins and rubbers, petroleum fractions (kerosene, light oil, heavy oil, naphtha, etc.). However, it is preferable to use one having excellent affinity with the nitrile rubber (A) or the polyorganosiloxane graft polymer (B). Among these, low-volatility plasticizers with low heat loss are adipic acid derivatives, phthalic acid derivatives, glutaric acid derivatives, trimellitic acid derivatives, pyromellitic acid derivatives, polyester plasticizers, glycerin derivatives, epoxy derivatives polyester polymerized plastics. An agent, a polyether polymerization type plasticizer and the like are preferably used.

  Examples of the softener include process oils such as petroleum process oils such as paraffinic oils, naphthenic process oils, and aromatic process oils.

  Examples of the plasticizer include dimethyl phthalate, diethyl phthalate, di-n-butyl phthalate, di- (2-ethylhexyl) phthalate, diheptyl phthalate, diisodecyl phthalate, di-n-octyl phthalate, and phthalic acid. Phthalic acid derivatives such as diisononyl, ditridecyl phthalate, octyldecyl phthalate, butyl benzyl phthalate, dicyclohexyl phthalate; isophthalic acid derivatives such as dimethyl isophthalate; tetrahydrophthal such as di- (2-ethylhexyl) tetrahydrophthalic acid Acid derivatives; dimethyl adipate, dibutyl adipate, di-n-hexyl adipate, di- (2-ethylhexyl) adipate, dioctyl adipate, isononyl adipate, diisodecyl adipate, dibutyl diglycol adipate, etc. Adipic acid derivatives; azelaic acid derivatives such as di-2-ethylhexyl azelate; sebacic acid derivatives such as dibutyl sebacate; dodecanedioic acid derivatives; maleic acid derivatives such as dibutyl maleate and di-2-ethylhexyl maleate; fumaric acid Fumaric acid derivatives such as dibutyl; p-oxybenzoic acid derivatives such as 2-ethylhexyl p-oxybenzoate; trimellitic acid derivatives such as tris-2-ethylhexyl trimellitic acid; pyromellitic acid derivatives; citric acid derivatives such as acetyltributyl citrate Itaconic acid derivative; oleic acid derivative; ricinoleic acid derivative; stearic acid derivative; other fatty acid derivative; sulfonic acid derivative; phosphoric acid derivative; glutaric acid derivative; dibasic acid such as adipic acid, azelaic acid, phthalic acid and glycol Polyester plasticizers that are polymers with monohydric alcohols, glycol derivatives, glycerin derivatives, paraffin derivatives such as chlorinated paraffins, epoxy derivatives polyester polymerized plasticizers, polyether polymerized plasticizers, ethylene carbonate, propylene Examples thereof include carbonate derivatives such as carbonate, benzenesulfonic acid derivatives such as N-butylbenzeneamide, and the like, but are not limited thereto, and those that are widely marketed as plasticizers for rubber or thermoplastic resins, etc. Various plasticizers can be used.

  Examples of the oil include vegetable oils such as castor oil, cottonseed oil, sesame oil, rapeseed oil, soybean oil, palm oil, palm oil, peanut oil, pine oil, tall oil, sesame oil, and camellia oil.

  Examples of other flexibility imparting agents include polybutene oil, spindle oil, machine oil, tricresyl phosphate, and the like.

  Examples of the flame retardant include, but are not limited to, triphenyl phosphate, tricresyl phosphate, decabromobiphenyl, decabromobiphenyl ether, and antimony trioxide. These flame retardants may be used alone or in combination of two or more.

  In order to improve the compatibility between the nitrile rubber (A) and the polyorganosiloxane-based graft polymer (B), various graft polymers and block polymers may be added as a compatibilizing agent.

  Examples of the compatibilizer include the Kraton series (manufactured by Shell Japan Co., Ltd.), the Tuftec series (manufactured by Asahi Kasei Kogyo Co., Ltd.), Dynalon (manufactured by Nippon Synthetic Rubber Co., Ltd.), and Epofriend (manufactured by Daicel Chemical Industries, Ltd.). ), Septon (manufactured by Kuraray Co., Ltd.), Nofaloy (manufactured by Nippon Oil & Fats Co., Ltd.), Lexpearl (manufactured by Nippon Polyolefin Co., Ltd.), Bond First (manufactured by Sumitomo Chemical Co., Ltd.), Bondine (Sumitomo Chemical Industries ( Co., Ltd.), Admer (Mitsui Chemicals Co., Ltd.), Umex (Sanyo Kasei Kogyo Co., Ltd.), VMX (Mitsubishi Chemical Co., Ltd.), Modiper (Nippon Yushi Co., Ltd.), Staphyroid (Takeda) Examples include commercial products such as Yakuhin Kogyo Co., Ltd. and Reeta (Toagosei Co., Ltd.). These can be appropriately selected and used according to the combination of the polyorganosiloxane-based graft polymer (B) used to supplement the physical properties of the nitrile rubber (A).

  The rubber composition in the present invention is easily produced by kneading a predetermined amount of each component with a mixer such as a Banbury mixer, a kneader, an intermixer, a two-roll mill, or a plast mill used for general rubber kneading. It is possible.

  The rubber composition thus obtained is molded into a shape according to the molding purpose by a molding method such as injection molding or hot press molding, and vulcanized as necessary to obtain a molded product. As a vulcanization temperature, a temperature of 80 ° C. or higher is usually suitable, preferably 100 to 200 ° C., and vulcanization is performed at this temperature for about 1 to 60 minutes. Further, if necessary, post-vulcanization can be performed at a temperature of about 80 to 200 ° C. for about 1 to 48 hours to improve physical properties.

  The temperature at the time of kneading may be adjusted according to the melting temperature of the nitrile rubber (A), the polyorganosiloxane-based graft polymer (B) to be used, and the lubricant and / or inorganic filler and / or thermoplastic resin. Well, for example, it can be pelletized by melt-kneading at 20 to 300 ° C.

  The rubber composition of the present invention can be used as a molded article. Examples of the molding include arbitrary molding methods such as extrusion molding, compression molding, blow molding, calendar molding, vacuum molding, foam molding, and injection molding.

  The rubber material obtained from the present invention can be widely used mainly in applications such as gaskets, packings, sealing materials, vibration proofing, waterproofing, and exercise equipment. As these uses, for example, it is suitably used for automobiles, electricity, electronics, architecture, sporting goods, particularly automobiles, electricity, and electronic parts.

 For example, in the automobile field, it can be used as a body part as a sealing material for maintaining airtightness, an anti-vibration material for glass, an anti-vibration material for vehicle body parts, particularly a wind seal gasket and a door glass gasket. As chassis parts, it can be used for vibration-proof and sound-proof engines and suspension rubbers, especially engine mount rubbers. As engine parts, they can be used for hoses for cooling, fuel supply, exhaust control, etc., sealing materials for engine oil, and the like. It can also be used for exhaust gas cleaning device parts and brake parts.

 As electrical and electronic parts, it can be used for packing, O-rings, belts and the like. Specifically, decorations for lighting fixtures, waterproof packings, anti-vibration rubbers, insect-proof packings, anti-vibration / sound absorption and air sealing materials for cleaners, drip-proof covers for electric water heaters, waterproof packings, heater parts Packing, electrode packing, safety valve diaphragm, hose for sake can, waterproof packing, solenoid valve, waterproof packing for steam microwave oven and jar rice cooker, water tank packing, water absorption valve, water receiving packing, connection hose, belt, heat insulation Oil packing for combustion equipment such as heater packing, steam outlet seal, O-ring, drain packing, pressure tube, blower tube, feed / intake packing, anti-vibration rubber, oil filler packing, oil meter packing, oil feed tube, Speaker gaskets, speaker edges, turntables for acoustic equipment such as diaphragm valves and air pipes Seat, belts, pulleys, and the like.

 In the construction field, it can be used for structural gaskets (zipper gaskets), air membrane roof materials, waterproof materials, fixed sealing materials, vibration-proof materials, sound-proof materials, setting blocks, sliding materials, and the like.

 In the sports field, it can be used for all-weather pavement materials, gymnasium floors, etc. as sports floors, shoe sole materials, midsole materials, etc. as sports shoes, golf balls etc. as ball for ball games.

 In the field of anti-vibration rubber, it can be used as anti-vibration rubber for automobiles, anti-vibration rubber for railway vehicles, anti-vibration rubber for aircraft, anti-vibration materials, and the like.

 In the marine and civil engineering fields, structural materials include rubber expansion joints, bearings, waterstops, waterproof sheets, rubber dams, elastic pavements, anti-vibration pads, protective bodies, etc., rubber molds, rubber packers, rubber skirts as construction secondary materials , Sponge mats, mortar hoses, mortar strainers, etc., rubber sheets, air hoses, etc. as construction auxiliary materials, rubber buoys, wave-absorbing materials, etc. as safety measures products, oil fences, silt fences, antifouling materials, marine hoses, etc. Can be used for draging hoses, oil skimmers, etc. In addition, it can be used for sheet rubber, mats, foam boards and the like.

  Next, the composition of the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

<Method for producing molded article for evaluation>
First, a predetermined amount of nitrile rubber, an antioxidant, a vulcanization accelerator, and a vulcanizer are mixed using a mixing roll “191-TM” (manufactured by Yasuda Seiki Seisakusho Co., Ltd.) under predetermined conditions (pre-roll rotation). Number: 19 rpm, front / rear roll rotation ratio: 1: 1.25, between rolls: 1 mm, kneading time: 3 minutes). Further, 50 parts by weight of polyorganosiloxane-based graft polymer particles are added to 100 parts by weight of nitrile rubber, and 1.5 parts by weight of sulfur as a crosslinking agent is added to 100 parts by weight of nitrile rubber. By kneading, a sheet-like sample was obtained. The sheet-like sample thus obtained is press-molded using a press machine according to predetermined conditions (press temperature: 160 ° C., press pressure: 11 MPa, press time: 19 minutes), and is 2 mm thick. A molded body was obtained. Each evaluation below was performed using the obtained sheet-like molded object.

<Tensile property evaluation method>
According to the method described in JIS K7113, measurement was performed using an autograph AG-10TB type manufactured by Shimadzu Corporation. The measurement was performed at n = 3, and the average values of strength (unit: MPa) and elongation (unit:%) when the test piece broke were adopted. As the test piece, a nitrile rubber composition sheet-like molded body produced by a predetermined method having a JIS-2 (1/3) shape and a thickness of about 2 mm was used. The test was conducted at a test speed of 23 ° C. and 50 mm / min. In principle, the test piece was conditioned at a temperature of 23 ± 2 ° C. and a relative humidity of 50 ± 5% for 48 hours or more before the test.

<Oil resistance evaluation method>
In accordance with ASTM D638, a sheet-like molded body of a nitrile rubber composition produced by a predetermined method was ASTM Oil No. 1 maintained at 150 ° C. 3 was immersed for 72 hours, and the weight change rate (% by weight) was determined.

<Low temperature embrittlement evaluation method>
In accordance with JIS K7216, a 2 mm thick sheet-like molded body of a nitrile rubber composition produced by a predetermined method was cut into 38 × 6 mm, and a low temperature embrittlement temperature measuring instrument “standard model S type (dry ice type)” ( Toyo Seiki Co., Ltd.) was used to measure the low temperature embrittlement temperature using a mixture of dry ice and methanol as a refrigerant.

(Production Example 1)
Mix 400 parts by weight of water and 12 parts by weight (solid content) of 10% aqueous sodium dodecylbenzenesulfonate in a 5-neck flask equipped with a stirrer, reflux condenser, nitrogen inlet, additional monomer port, and thermometer. Then, the temperature was raised to 50 ° C., and after the liquid temperature reached 50 ° C., nitrogen substitution was performed. Thereafter, 10 parts by weight of butyl acrylate and 3 parts by weight of t-dodecyl mercaptan were added. After 30 minutes, 0.01 parts by weight of paramentane hydroperoxide (solid content), 0.3 parts of sodium formaldehyde sulfoxylate (SFS), 0.01 parts by weight of disodium ethylenediaminetetraacetate (EDTA), ferrous sulfate 0.0025 part by weight was added and stirred for 1 hour. A mixed solution of 90 parts by weight of butyl acrylate, 27 parts by weight of t-dodecyl mercaptan and 0.09 parts by weight of paramentane hydroperoxide (solid content) was continuously added over 3 hours. Thereafter, post-polymerization was performed for 2 hours to obtain a latex containing a seed polymer.

  Next, 2 parts by weight (solid content) of the above seed polymer was charged into a 5-neck flask equipped with a stirrer, reflux cooling water, nitrogen blowing port, monomer addition port, and thermometer. Thereafter, 300 parts by weight of pure water (including the amount brought in from the latex containing the seed polymer), 0.49 parts by weight of 15% aqueous sodium dodecylbenzenesulfonate (solid content), 98 parts by weight of octamethylcyclotetrasiloxane, methacrylate A mixture composed of 2.94 parts by weight of roxypropylmethyldimethoxysilane was stirred at 7000 rpm for 5 minutes with a homomixer to prepare an emulsion of a polyorganosiloxane-forming component and added all at once.

  Next, 1.5 parts by weight (solid content) of a 10% aqueous dodecylbenzenesulfonic acid solution was added, and then the system was heated to 80 ° C. under a nitrogen stream while stirring the system. After reaching 80 ° C., stirring was continued at 80 ° C. for 9 hours, then cooled to 25 ° C. and allowed to stand for 18 hours. Thereafter, the pH was adjusted to 6.5 with sodium hydroxide to complete the polymerization, and a latex containing polyorganosiloxane particles was obtained.

  Subsequently, in a 5-neck flask equipped with a stirrer, a reflux condenser, a nitrogen inlet, a monomer addition port and a thermometer, 340 parts by weight of pure water (including the amount brought in from the latex containing organosiloxane particles), and The polyorganosiloxane particles 80 parts by weight (solid content) were charged, and the system was heated to 40 ° C. under a nitrogen stream while stirring the system. After reaching 40 ° C., 0.39 parts by weight of sodium formaldehyde sulfoxylate (SFS), 0.0048 parts by weight of disodium ethylenediaminetetraacetate (EDTA) and 0.0012 parts by weight of ferrous sulfate were added, and then methyl methacrylate. A mixture of 15 parts by weight, 5 parts by weight of ethyl acrylate, and 0.08 part by weight of cumene hydroperoxide (solid content) was added dropwise over 1 hour, and after completion of addition, polyorganosiloxane was further continued for 1 hour. A latex of a graft polymer was obtained.

  Subsequently, the latex was diluted with pure water to a solid content concentration of 15%, and then 4 parts by weight (solid content) of 25% aqueous calcium chloride solution was added to obtain a coagulated slurry. The coagulated slurry was heated to 75 ° C., cooled to 50 ° C., dehydrated, and dried to obtain a polyorganosiloxane graft polymer powder.

(Production Example 2)
2 parts by weight (solid content) of the seed polymer prepared in Production Example 1 was charged into a 5-neck flask equipped with a stirrer, reflux cooling water, nitrogen inlet, monomer addition port, and thermometer. Thereafter, 300 parts by weight of pure water (including the amount brought in from the latex containing the seed polymer), 0.49 parts by weight of 15% sodium dodecylbenzenesulfonate aqueous solution (solid content), 98 parts by weight of octamethylcyclotetrasiloxane, mercapto A mixture composed of 2.94 parts by weight of propylmethyldimethoxysilane was stirred at 7000 rpm for 5 minutes with a homomixer to prepare an emulsion of a polyorganosiloxane-forming component and added all at once.

  Next, 1.5 parts by weight (solid content) of a 10% aqueous dodecylbenzenesulfonic acid solution was added, and then the system was heated to 80 ° C. under a nitrogen stream while stirring the system. After reaching 80 ° C., stirring was continued at 80 ° C. for 9 hours, then cooled to 25 ° C. and allowed to stand for 18 hours. Thereafter, the pH was adjusted to 6.5 with sodium hydroxide to complete the polymerization, and a latex containing polyorganosiloxane particles was obtained.

  Subsequently, in a 5-neck flask equipped with a stirrer, a reflux condenser, a nitrogen inlet, a monomer addition port and a thermometer, 340 parts by weight of pure water (including the amount brought in from the latex containing organosiloxane particles), and The polyorganosiloxane particles 80 parts by weight (solid content) were charged, and the system was heated to 40 ° C. under a nitrogen stream while stirring the system. After reaching 40 ° C., 0.39 parts by weight of sodium formaldehyde sulfoxylate (SFS), 0.0048 parts by weight of disodium ethylenediaminetetraacetate (EDTA) and 0.0012 parts by weight of ferrous sulfate were added, and then allyl methacrylate A mixture of 3 parts by weight and cumene hydroperoxide 0.16 part by weight (solid content) was added, and stirring was continued at 40 ° C. for 1 hour. Thereafter, a mixture of 15 parts by weight of methyl methacrylate, 5 parts by weight of ethyl acrylate, and 0.08 part by weight of cumene hydroperoxide (solid content) was added dropwise over 1 hour, and stirring was continued for 1 hour after the addition was completed. As a result, a latex of a polyorganosiloxane graft polymer was obtained.

  Subsequently, the latex was diluted with pure water to a solid content concentration of 15%, and then 4 parts by weight (solid content) of 25% aqueous calcium chloride solution was added to obtain a coagulated slurry. The coagulated slurry was heated to 75 ° C., cooled to 50 ° C., dehydrated, and dried to obtain a polyorganosiloxane graft polymer powder.

(Production Example 3)
In a five-necked flask equipped with a stirrer, reflux condenser, nitrogen inlet, monomer addition port and thermometer, 340 parts by weight of pure water (including the amount brought in from latex containing organosiloxane particles), and production example 80 parts by weight (solid content) of the polyorganosiloxane particles obtained in 2 were charged, and the system was heated to 40 ° C. under a nitrogen stream while stirring the system. After reaching 40 ° C., 0.39 parts by weight of sodium formaldehyde sulfoxylate (SFS), 0.0048 parts by weight of disodium ethylenediaminetetraacetate (EDTA) and 0.0012 parts by weight of ferrous sulfate were added, and then methyl methacrylate. A mixture of 15 parts by weight, 5 parts by weight of ethyl acrylate, and 0.08 part by weight of cumene hydroperoxide (solid content) was added dropwise over 1 hour, and stirring was continued for 1 hour after the addition was completed. A latex of a graft polymer was obtained.

  Subsequently, after the latex was diluted with pure water to a solid content concentration of 15%, 4 parts by weight of 25% calcium chloride aqueous solution (solid content) was added and coagulated to form a large mass. After dehydration and drying, a polyorganosiloxane graft polymer was obtained, but it became a large lump and did not become a good powder.

Example 1
Nitrile rubber (made by Nippon Zeon, trade name Nipol 1041) 100 parts by weight and polyorganosiloxane graft polymer particles 50 parts by weight obtained in Production Example 1, zinc oxide 5 parts by weight (manufactured by Shodo Chemical Co., Ltd., zinc oxide II), 1 part by weight of stearic acid (manufactured by NOF Corporation), 1 part by weight of vulcanization accelerator (manufactured by Ouchi Shinsei Chemical Co., Ltd., MBTS), and 1.5 parts by weight of vulcanizing agent (manufactured by Hosoi Chemical Co., sulfur) A sheet-like sample was obtained using a mixing roll “191-TM” (manufactured by Yasuda Seiki Seisakusho Co., Ltd.). The sheet-like sample thus obtained was press-molded according to a predetermined method to obtain a sheet-like molded body having a thickness of 2 mm. Tensile properties, low temperature embrittlement temperature, and oil resistance were measured using the obtained sheet-like molded product. The results are shown in Table 1.

(Comparative Example 1)
In the method described in the examples, a polyorganosiloxane-based graft polymer was not added, and the same sheet-like molded product was prepared and the characteristics were evaluated. The results are shown in Table 1.

(Example 2)
Hydrogenated nitrile rubber (manufactured by Nippon Zeon, trade name Zetpol 1010) 100 parts by weight and polyorganosiloxane-based graft polymer particles 50 parts by weight obtained in Production Example 2, zinc oxide 5 parts by weight (manufactured by Shodo Chemical Co., Ltd., zinc oxide II) Seeds), 1 part by weight of stearic acid (manufactured by NOF Corporation), 1 part by weight of vulcanization accelerator (manufactured by Ouchi Shinsei Chemical, MBTS), and 1.5 parts by weight of vulcanizing agent (manufactured by Hosoi Chemical, sulfur) According to the method, a sheet-like sample was obtained using a mixing roll “191-TM” (manufactured by Yasuda Seiki Seisakusho). The sheet-like sample thus obtained was press-molded according to a predetermined method to obtain a sheet-like molded body having a thickness of 2 mm.

(Comparative Example 2)
In the method described in Example 2, the polyorganosiloxane-based graft polymer obtained in Production Example 3 was used as the polyorganosiloxane-based graft polymer. Thus, a good molded product could not be obtained.

Claims (8)

  A rubber composition comprising (A) a nitrile rubber and (B) a polyorganosiloxane-based graft polymer.   The rubber composition according to claim 1, comprising (A) 50 to 98% by weight of nitrile rubber and (B) 50 to 2% by weight of a polyorganosiloxane-based graft polymer.   (B) The polyorganosiloxane graft polymer is a polyorganosiloxane graft polymer having a graft component content of 5 to 40% by weight and a polyorganosiloxane content of 95 to 60% by weight. The rubber composition according to 1 or 2.   (B) A polyorganosiloxane-based graft polymer having an alkyl methacrylate content of 5 to 99.5% by weight and an alkyl acrylate content of 95 to 0.5% by weight in the entire graft component of the polyorganosiloxane-based graft polymer. The rubber composition according to any one of claims 1 to 3, wherein the rubber composition is a coalescence.   The rubber composition according to any one of claims 1 to 4, wherein the polyorganosiloxane-based graft polymer (B) is obtained by seed polymerization. The rubber composition according to any one of claims 1 to 5, wherein the polyorganosiloxane-based graft polymer (B) is polymerized using a mercapto group-containing compound as a graft crossing agent. The rubber composition according to any one of claims 1 to 6, wherein the polyorganosiloxane graft polymer (B) is polymerized using a polyfunctional monomer.
  The molded object which consists of a rubber composition of any one of Claim 1 to 7.