WO2019124462A1 - Rubber composition and rubber molded article - Google Patents

Rubber composition and rubber molded article Download PDF

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Publication number
WO2019124462A1
WO2019124462A1 PCT/JP2018/046871 JP2018046871W WO2019124462A1 WO 2019124462 A1 WO2019124462 A1 WO 2019124462A1 JP 2018046871 W JP2018046871 W JP 2018046871W WO 2019124462 A1 WO2019124462 A1 WO 2019124462A1
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WIPO (PCT)
Prior art keywords
mass
parts
rubber
rubber composition
molded article
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PCT/JP2018/046871
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French (fr)
Japanese (ja)
Inventor
和志 坂手
太賀 國井
義彦 山口
Original Assignee
内山工業株式会社
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Publication date
Application filed by 内山工業株式会社 filed Critical 内山工業株式会社
Priority to CN201880081318.3A priority Critical patent/CN111479867A/en
Priority to JP2019560544A priority patent/JP7244086B2/en
Priority to DE112018006565.0T priority patent/DE112018006565T5/en
Publication of WO2019124462A1 publication Critical patent/WO2019124462A1/en

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K3/00—Materials not provided for elsewhere
    • C09K3/10—Materials in mouldable or extrudable form for sealing or packing joints or covers
    • C09K3/1006—Materials in mouldable or extrudable form for sealing or packing joints or covers characterised by the chemical nature of one of its constituents
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/02—Elements
    • C08K3/04—Carbon
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/34—Silicon-containing compounds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/34—Silicon-containing compounds
    • C08K3/36—Silica
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/0008—Organic ingredients according to more than one of the "one dot" groups of C08K5/01 - C08K5/59
    • C08K5/0016—Plasticisers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L9/00—Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
    • C08L9/02—Copolymers with acrylonitrile
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K2200/00—Chemical nature of materials in mouldable or extrudable form for sealing or packing joints or covers
    • C09K2200/02—Inorganic compounds
    • C09K2200/0243—Silica-rich compounds, e.g. silicates, cement, glass
    • C09K2200/0252—Clays
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K2200/00—Chemical nature of materials in mouldable or extrudable form for sealing or packing joints or covers
    • C09K2200/02—Inorganic compounds
    • C09K2200/0243—Silica-rich compounds, e.g. silicates, cement, glass
    • C09K2200/0252—Clays
    • C09K2200/026—Kaolin
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K2200/00—Chemical nature of materials in mouldable or extrudable form for sealing or packing joints or covers
    • C09K2200/06—Macromolecular organic compounds, e.g. prepolymers
    • C09K2200/0607—Rubber or rubber derivatives
    • C09K2200/0612—Butadiene-acrylonitrile rubber

Definitions

  • the present invention relates to a rubber composition and a rubber molded article obtained by crosslinking the same.
  • Rubber molded articles are used in a wide range of applications, taking advantage of their elastic properties. Above all, they are suitably used for automotive parts such as gaskets for sealing fluid and seals for bearings used for axles.
  • the rubber molded article of patent document 1 As a rubber molded article used for a bearing, the rubber molded article of patent document 1 is mentioned, for example.
  • Patent Document 1 100 parts by mass of nitrile rubber (A), 1 to 30 parts by mass of conductive carbon black (B) having a DBP oil absorption of 150 mL / 100 g or more and 1000 mL / 100 g or less, and silylated clay (C) 5 A rubber composition containing ⁇ 60 parts by weight is described. And since a rubber molded article obtained by vulcanizing this rubber composition is excellent in conductivity and weatherability, it is supposed to be suitably used as a seal for bearings.
  • the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a rubber molded article excellent in heat resistance and low temperature resistance. Another object of the present invention is to provide a rubber composition for obtaining such a rubber molded article.
  • the above-mentioned subjects are 100 parts by mass of nitrile rubber (A), 5 to 100 parts by mass of carbon black (B), 5 to 75 parts by mass of calcined kaolin (C), 5 to 75 parts by mass of diatomaceous earth (D), and plasticizer (E) And 5) containing 1 to 30 parts by mass, the acrylonitrile unit content of the nitrile rubber (A) is 25 to 30% by mass, and the heating loss ratio of the plasticizer (E) after leaving at 150 ° C. for 24 hours is 5
  • the problem is solved by providing a rubber composition characterized in that it is not more than mass%.
  • the rubber composition further contain 0.1 to 10 parts by mass of an antioxidant (F). Moreover, it is preferable that the said rubber composition contains dithio carbamate and microcrystalline wax as an antiaging agent (F).
  • the rubber composition preferably further contains 0.5 to 10 parts by mass of paraffin wax (G) having a melting point of 45 to 100 ° C.
  • a rubber molded article obtained by vulcanizing the above rubber composition is a preferred embodiment of the present invention.
  • a seal or a gasket made of the above-mentioned rubber molded article is also a preferred embodiment of the present invention.
  • a rubber molded article excellent in heat resistance and low temperature resistance can be provided.
  • the rubber composition for obtaining such a rubber molded article can be provided.
  • the present invention comprises 100 parts by mass of nitrile rubber (A), 5 to 100 parts by mass of carbon black (B), 5 to 75 parts by mass of calcined kaolin (C), 5 to 75 parts by mass of diatomaceous earth (D), and a plasticizer (E) And 5) containing 1 to 30 parts by mass, the acrylonitrile unit content of the nitrile rubber (A) is 25 to 30% by mass, and the heating loss ratio of the plasticizer (E) after leaving at 150 ° C. for 24 hours is 5 It is the rubber composition characterized by being below mass%.
  • Nirile rubber (A) As a nitrile rubber (A) used by this invention, the copolymer of an acrylonitrile and a 1, 3- butadiene is mentioned. Hydrogenation to the double bond remaining in the 1,3-butadiene unit after polymerization is optional. Non-hydrogenated nitrile rubber and hydrogenated nitrile rubber can be properly used properly.
  • the content of acrylonitrile units of the nitrile rubber (A) is 25 to 30% by mass. From the viewpoint of the balance between heat resistance and low temperature resistance, it is important that the content of the acrylonitrile unit is in the above range.
  • the content of the acrylonitrile unit is preferably 26% by mass or more.
  • the content of acrylonitrile units is preferably 29% by mass or less.
  • the nitrile rubber (A) used in the present invention may contain a structural unit derived from another copolymerizable monomer as long as the effect of the present invention is not impaired.
  • it may contain a functional group such as a carboxyl group or a carboxylic acid anhydride group.
  • the copolymerization amount of such other monomers is usually 10 mol% or less, preferably 5 mol% or less, and more preferably 2 mol% or less.
  • the Mooney viscosity (ML 1 +4 , 100 ° C.) of the nitrile rubber (A) is preferably 10 to 120. From the viewpoint of the moldability of the rubber composition, the Mooney viscosity is preferably 10 or more, and more preferably 20 or more. On the other hand, the Mooney viscosity is preferably 120 or less, more preferably 100 or less, from the viewpoint of the strength of the rubber molded article.
  • a nitrile rubber (A) may be used individually by 1 type, and may mix and use 2 or more types.
  • the content of the acrylonitrile unit in the mixed nitrile rubber and the Mooney viscosity are taken as an average value taking into consideration the blending ratio of the nitrile rubber.
  • Carbon black (B) The type of carbon black (B) used in the present invention is not particularly limited, and SAF, ISAF, HAF, FEF, GPF, MAF, SRF, FT, MT, etc. can be used, and in terms of the balance between performance and cost. FEF, FT, MT, SRF, MAF are preferred. As carbon black (B), two or more types of carbon black can be used in combination.
  • the content of carbon black (B) is 5 to 100 parts by mass with respect to 100 parts by mass of nitrile rubber (A). When the content of the carbon black (B) is less than 5 parts by mass, the tensile strength of the rubber molded article is insufficient.
  • the content of carbon black (B) is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, and still more preferably 30 parts by mass or more. On the other hand, when the content of carbon black (B) exceeds 100 parts by mass, the formability is deteriorated.
  • the content of carbon black (B) is preferably 90 parts by mass or less, and more preferably 80 parts by mass or less.
  • the average primary particle size of the carbon black (B) is not particularly limited, and is usually 5 to 200 nm.
  • the average primary particle diameter of the carbon black (B) is preferably 40 nm or less, and preferably 30 nm or less, from the viewpoint that the tensile strength of the rubber molded product can be improved even if the compounding amount to the rubber composition is small. It is more preferable that
  • the rubber composition of the present invention comprises calcined kaolin (C) and diatomaceous earth (D).
  • kaolin is a natural clay mineral containing hydrous aluminum silicate (composition formula: Al 2 Si 2 O 5 (OH) 4 ) as a main component. And after baking kaolin refines this clay mineral, baking water is removed at high temperature.
  • diatomaceous earth is a deposit composed of fossil shells of diatoms, which is a kind of single cell algae, and is mainly composed of silicon dioxide (SiO 2 ).
  • the rubber molded product obtained by blending only the calcined kaolin (C) among the calcined kaolin (C) and the diatomaceous earth (D) is heated and thereby the hardness is excessively increased and the elongation is decreased. .
  • the glass transition point is too high. Therefore, the content of each of the calcined kaolin (C) and the diatomaceous earth (D) in the rubber molding is important.
  • the content of the calcined kaolin (C) is 5 to 75 parts by mass with respect to 100 parts by mass of the nitrile rubber (A).
  • the content of the calcined kaolin (C) is preferably 10 parts by mass or more, and more preferably 15 parts by mass or more.
  • the content of the calcined kaolin (C) is preferably 70 parts by mass or less, and more preferably 60 parts by mass or less.
  • the content of diatomaceous earth (D) is 5 to 75 parts by mass with respect to 100 parts by mass of nitrile rubber (A).
  • the content of diatomaceous earth (D) is preferably 10 parts by mass or more, and more preferably 15 parts by mass or more.
  • the content of diatomaceous earth (D) is preferably 70 parts by mass or less, and more preferably 60 parts by mass or less.
  • the total amount of the calcined kaolin (C) and the diatomaceous earth (D) is preferably 100 parts by mass or less and more preferably 80 parts by mass or less with respect to 100 parts by mass of the nitrile rubber (A).
  • the mass ratio [(C) / (D)] of calcined kaolin (C) to diatomaceous earth (D) is usually 90/10 to 10/90, preferably 80/20. 20 to 80, more preferably 70/30 to 30/70.
  • the calcined kaolin (C) may be surface-treated with a fatty acid, a surfactant, a silane coupling agent or the like. Further, the diatomaceous earth (D) may be similarly surface-treated with a fatty acid, a surfactant, a silane coupling agent or the like.
  • the rubber composition of the present invention contains a plasticizer (E).
  • a plasticizer (E) having a heating loss ratio of 5% by mass or less after standing at 150 ° C. for 24 hours.
  • the heating loss ratio is preferably 4% by mass or less, more preferably 3% by mass or less, and still more preferably 2.5% by mass or less.
  • the heating loss ratio in the present specification is a value obtained by subtracting the mass of the rubber composition after heating from the mass of the rubber composition before heating divided by the mass of the rubber composition before heating and expressed as a percentage. It is a representation. The details of the method for measuring the heating loss rate are as described in the examples below.
  • the type of the plasticizer (E) used in the present invention is not particularly limited as long as the heating loss ratio is as described above, and a plasticizer generally used in a rubber composition is used.
  • a plasticizer generally used in a rubber composition is used.
  • phthalic acid derivatives tetrahydrophthalic acid derivatives, adipic acid derivatives, azelaic acid derivatives, sebacic acid derivatives, dodecane-2-acid derivatives, maleic acid derivatives, fumaric acid derivatives, trimellitic acid derivatives, pyromellitic acid derivatives, citric acid Derivatives, oleic acid derivatives, ricinoleic acid derivatives, stearic acid derivatives, sulfonic acid derivatives, phosphoric acid derivatives, glutaric acid derivatives, glycol derivatives, glycerin derivatives, paraffin derivatives, epoxy derivatives, polymeric plasticizers (polyesters, polyethers, etc.), etc. Can be mentioned.
  • These plasticizers
  • the content of the plasticizer (E) is 1 to 30 parts by mass with respect to 100 parts by mass of the nitrile rubber (A). When the content of the plasticizer (E) is less than 1 part by mass, the effect of blending the plasticizer (E) becomes insufficient.
  • the content of the plasticizer (E) is preferably 2 parts by mass or more, and more preferably 5 parts by mass or more. On the other hand, when content of a plasticizer (E) exceeds 30 mass parts, there exists a possibility that a plasticizer (E) may bleed.
  • the content of the plasticizer (E) is preferably 25 parts by mass or less, and more preferably 20 parts by mass or less.
  • the rubber composition further contains an antiaging agent (F).
  • the antiaging agent (F) include dithiocarbamates, microcrystalline waxes, naphthylamines, diphenylamines, p-phenylenediamines, quinolines, hydroquinones, phenols, and ion-containings.
  • the antiaging agent (F) contains both dithiocarbamate and microcrystalline wax.
  • microcrystalline wax is a wax mainly extracted from the vacuum distillation residue of crude oil, and branched hydrocarbon (isoparaffin) and saturated cyclic hydrocarbon (cycloparaffin) compared to paraffin wax (G) described later.
  • dithiocarbamates include nickel diethyldithiocarbamate and nickel dibutyldithiocarbamate.
  • the content of the antiaging agent (F) is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the nitrile rubber (A). If the content of the antiaging agent (F) is less than 0.1 parts by mass, the ozone resistance of the rubber molded product may be insufficient.
  • the content of the antiaging agent (F) is more preferably 1 part by mass or more, and still more preferably 2 parts by mass or more. On the other hand, when the content of the antiaging agent (F) exceeds 10 parts by mass, bloom may occur.
  • the content of the antioxidant (F) is more preferably 8 parts by mass or less.
  • the mass ratio of dithiocarbamate (X) to microcrystalline wax (Y) in the antiaging agent (F) [(X) / (Y)] is usually 90/10 to 10/90, preferably 80/20 to 20/80, more preferably 70/30 to 30/70.
  • paraffin wax (G) In the present invention, it is preferable that the rubber composition further contains a paraffin wax (G) from the viewpoint of further improving the ozone resistance of the rubber molded article.
  • paraffin wax (G) refers to one obtained by separating and extracting a hydrocarbon with good crystallinity from a vacuum distillation distillate of crude oil, which contains a linear hydrocarbon (normal paraffin) as a main component.
  • paraffin wax (G) is usually added to a rubber composition in order to improve kneadability and mold releasability at the time of production of a rubber molded article. For these reasons, paraffin wax (G) and the microcrystalline wax (anti-aging agent) described above are clearly distinguished by those skilled in the art.
  • the melting point of paraffin wax (G) is preferably 45 to 100.degree. By using paraffin wax (G) having a melting point in this range, the ozone resistance of the rubber molded article can be further improved.
  • the melting point is more preferably 48 ° C. or more, further preferably 50 ° C. or more. On the other hand, the melting point is more preferably 90 ° C. or less, still more preferably 80 ° C. or less.
  • the content of paraffin wax (G) is preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of nitrile rubber (A). When the content of the paraffin wax (G) is in this range, the ozone resistance of the rubber molded article can be further improved.
  • the content of the paraffin wax (G) is more preferably 0.7 parts by mass or more. On the other hand, the content of paraffin wax (G) is more preferably 5 parts by mass or less.
  • the above rubber composition contains components other than nitrile rubber (A), carbon black (B), calcined kaolin (C), diatomaceous earth (D) and plasticizer (E) within the range that the effects of the present invention are not inhibited. You may include it.
  • a vulcanizing agent in addition to the anti-aging agent (F) described above, a vulcanizing agent, a vulcanizing aid, a vulcanization accelerator, a vulcanization retarder, an adhesive, an acid acceptor, a coloring agent, a filler, processing
  • Various additives such as auxiliary agents, coupling agents and lubricants can be mentioned.
  • the method for producing the rubber molded article of the present invention is not particularly limited, preferred production methods include nitrile rubber (A), carbon black (B), calcined kaolin (C), diatomaceous earth (D), plasticizer (E) and The method includes a kneading step of kneading a vulcanizing agent to obtain a rubber composition, a molding step of molding the rubber composition, and a vulcanization step of vulcanizing the rubber composition.
  • the method of mixing the above-mentioned components in the kneading step is not particularly limited, and kneading can be performed using an open roll, a kneader, a Banbury mixer, an intermixer, an extruder, or the like. Above all, it is preferable to knead using a Banbury mixer, an intermixer or a kneader.
  • the temperature during kneading is preferably 20 to 140.degree.
  • the rubber composition of the present invention is obtained by molding the rubber composition thus obtained in a molding step and subsequently vulcanizing in a vulcanization step.
  • injection molding, extrusion molding, compression molding, roll molding and the like can be mentioned. Among them, injection molding and compression molding are preferable. At this time, it may be vulcanized after being molded in advance, or may be vulcanized simultaneously with molding.
  • the vulcanization temperature is preferably 150 to 230 ° C. in general.
  • the vulcanization time is usually 0.1 to 60 minutes.
  • a heating method for vulcanization a general method used for vulcanization of rubber such as compression heating, steam heating, oven heating, hot air heating and the like is used.
  • the method of vulcanization is not particularly limited, and examples thereof include sulfur vulcanization and peroxide vulcanization.
  • Sulfur or a sulfur-containing compound is used as a vulcanizing agent at the time of sulfur vulcanization.
  • an organic peroxide is used as a vulcanizing agent at the time of peroxide vulcanization.
  • the amount of the vulcanizing agent used at this time is usually 0.1 to 10 parts by mass with respect to 100 parts by mass of the nitrile rubber (A).
  • the rubber molded article of the present invention is suitably used for a seal or a gasket mounted on an automobile.
  • the seal may, for example, be a bearing seal, an oil seal or a shaft seal.
  • the gasket include a gasket for a cylinder head cover, a gasket for an oil pan, and the like.
  • Nitrile rubber (A1) JSR Corporation “N241” (Acrylonitrile unit content: 29%, Mooney viscosity (ML 1 + 4 , 100 ° C.): 56) ⁇ Nitrile rubber (A2) JSR Corporation “N 240 S” (Acrylonitrile unit content: 26%, Mooney viscosity (ML 1 + 4 , 100 ° C.): 56) ⁇ Nitrile rubber (A3) Nippon Zeon Co., Ltd. “Nipol DN 2850” (Acrylonitrile unit content: 28%, Mooney viscosity (ML 1 + 4 , 100 ° C.): 50)
  • Anti-aging agent (F1) Alkyl diphenylamine (brand name "NOCRACK ODA” made by Ouchi Emerging Chemical Industry Co., Ltd.)
  • Anti-aging agent (F2) Dibutyl dithiocarbamate nickel (trade name "NOCLAK NBC” manufactured by Ouchi Shinko Chemical Co., Ltd.)
  • Anti-aging agent (F3) Microcrystalline wax made by Ouchi Emerging Chemical Industry Co., Ltd.
  • Paraffin wax 135" (melting point: 58 ° C, oil content: 0.3% by mass, penetration: 13 (25 ° C), 21 (35 ° C), viscosity: 3.9 mm 2 / s / 100 ° C., Saybolt color: +30, density: 0.911 g / cm 3 (25 ° C.), 0.775 g / cm 3 (70 ° C.), flash point: 234 ° C., average molecular weight: 389 (gas chromatography method))
  • Example 1 (Production of rubber sheet) The mixture having the composition shown below was kneaded using an open roll at a temperature of 20 to 100 ° C. for 10 to 30 minutes to obtain a rubber composition. Then, using this rubber composition, an unvulcanized rubber sheet having a thickness of 2 mm was produced (hereinafter, may be simply referred to as an unvulcanized rubber sheet).
  • Nitrile rubber 100 parts by mass Carbon black (B1): 50 parts by mass Calcined kaolin (C): 25 parts by mass Diatomaceous earth (D): 25 parts by mass Plasticizer (E1): 15 parts by mass Anti-aging agent (F1): 2 parts by mass Anti-aging agent (F2): 1 part by mass Anti-aging agent (F3): 1 part by mass Active zinc flower: 5 parts by mass Stearic acid: 1 part by mass Sulfur: 1.5 parts by mass Vulcanization accelerator (DM): 1 part by mass Curing accelerator (TT): 1 part by mass
  • the obtained unvulcanized rubber sheet was press-cured at 120 ° C. for 10 minutes to obtain a vulcanized rubber sheet having a thickness of 2 mm (hereinafter sometimes referred to simply as a vulcanized rubber sheet).
  • Three sheets of this vulcanized rubber sheet were stacked, and measurement was performed at 23 ° C. and 50% relative humidity using a type A durometer, and the peak value was read. As a result, the A hardness was 71.
  • tensile strength (MPa) and elongation (%) were measured at a tensile speed of 500 mm / min at a temperature of 23 ° C. and a relative humidity of 50%. As a result, the tensile strength was 12.9 MPa and the elongation was 360%.
  • the tensile test was performed according to JIS K6251, and the measurement of hardness was performed according to JIS K6253.
  • Thermal aging test The vulcanized rubber sheet was heated at 170 ° C. for 70 hours. After heating, three sheets of this vulcanized rubber sheet were stacked, and measurement was performed at 23 ° C. and 50% relative humidity using a type A durometer, and the peak value was read. Further, using the vulcanized rubber sheet after the heating, the tensile strength (MPa) and the elongation (%) were measured at a tensile speed of 500 mm / min at 23 ° C. and a relative humidity of 50%. The heat aging test was conducted in accordance with JIS K6257.
  • the heat aging characteristic was evaluated by calculating the change of the value with respect to the said normal-state physical property.
  • the hardness change was +5 points.
  • the hardness change is a value obtained by subtracting the A hardness before heating from the A hardness after heating.
  • the tensile strength change rate was + 4%.
  • the rate of change in tensile strength is the value obtained by subtracting the value of tensile strength before heating from the value of tensile strength after heating divided by the value of tensile strength before heating and expressed as a percentage. is there. When this value is positive, it shows that tensile strength rose by heating, and when negative, it shows that tensile strength fell.
  • the rate of change in elongation was calculated by the same calculation method, the rate of change in elongation was -33%. The results are shown in Table 1.
  • Measurement condition 1 Static extension ratio 20%, Temperature 40 ° C, Humidity 10%, Leave for 4 hours under atmosphere of ozone concentration 50 pphm
  • Measurement condition 2 Static extension ratio 5%, Temperature 23 ° C, Humidity 10%, Ozone concentration For 48 hours in an atmosphere of 200 pphm
  • Measurement condition 3 For 48 hours in an atmosphere of a static elongation of 5%, a temperature of 23 ° C., a humidity of 65%, and an ozone concentration of 200 pphm
  • the glass transition temperature (° C.) of the rubber molded article is shown in Table 1.
  • the glass transition temperature (° C.) shown in Table 1 is a glass transition start temperature measured at a temperature rising rate of 10 ° C./minute using a differential scanning calorimeter (DSC). The lower the glass transition temperature (° C.), the better the low temperature resistance.
  • Heating loss rate of plasticizer (E) The rubber composition obtained in the above "preparation of rubber sheet” was placed in an oven at 150 ° C., and left for 24 hours to determine the heating loss ratio of the plasticizer (E).
  • the heating loss ratio was represented by a value obtained by subtracting the mass of the rubber composition after heating from the mass of the rubber composition before heating divided by the mass of the rubber composition before heating.
  • the heating loss ratio of the plasticizer (E) was 2%.
  • Examples 2 to 15 and Comparative Examples 1 to 4 A rubber composition was obtained in the same manner as in Example 1 except that in the above-mentioned "Production of Vulcanized Rubber Sheet", the types and amounts of the components were changed as shown in Tables 1 to 3. And evaluation similar to Example 1 was performed using the obtained rubber composition. The results are shown in Tables 1 to 3.

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  • Organic Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Engineering & Computer Science (AREA)
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  • Compositions Of Macromolecular Compounds (AREA)
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Abstract

A rubber composition that is characterized by containing 100 parts by mass of a nitrile rubber (A), 5–100 parts by mass of carbon black (B), 5–75 parts by mass of fired kaolin (C), 5–75 parts by mass of diatomaceous earth (D), and 1–30 parts by mass of a plasticizer (E), the nitrile rubber (A) having an acrylonitrile unit content of 25–30 mass%, and the plasticizer (E) having a loss on heating of no more than 5 mass% after being left for 24 hours at 150°C. The present invention makes it possible to provide a rubber molded article that has excellent heat resistance and low-temperature resistance. The present invention also makes it possible to provide a rubber composition for obtaining such a rubber molded article.

Description

ゴム組成物及びゴム成形品Rubber composition and rubber molded article
　本発明はゴム組成物及びそれを架橋してなるゴム成形品に関する。 The present invention relates to a rubber composition and a rubber molded article obtained by crosslinking the same.
　ゴム成形品は、その弾性的性質を生かして、幅広い用途に用いられている。中でも、流体を封止するためのガスケットや車軸に用いられるベアリングのシールなど、自動車用部品に好適に用いられている。 Rubber molded articles are used in a wide range of applications, taking advantage of their elastic properties. Above all, they are suitably used for automotive parts such as gaskets for sealing fluid and seals for bearings used for axles.
　ベアリングに用いられるゴム成形品として、例えば特許文献１に記載のゴム成形品が挙げられる。特許文献１には、ニトリルゴム（Ａ）１００質量部、ＤＢＰ吸油量が１５０ｍＬ／１００ｇ以上１０００ｍＬ／１００ｇ以下の導電性カーボンブラック（Ｂ）１～３０質量部及びシリル化されたクレー（Ｃ）５～６０質量部を含有するゴム組成物が記載されている。そして、このゴム組成物を加硫して得られるゴム成形品は、導電性及び耐候性に優れているので、ベアリング用のシールとして好適に用いられるとされている。 As a rubber molded article used for a bearing, the rubber molded article of patent document 1 is mentioned, for example. In Patent Document 1, 100 parts by mass of nitrile rubber (A), 1 to 30 parts by mass of conductive carbon black (B) having a DBP oil absorption of 150 mL / 100 g or more and 1000 mL / 100 g or less, and silylated clay (C) 5 A rubber composition containing ̃60 parts by weight is described. And since a rubber molded article obtained by vulcanizing this rubber composition is excellent in conductivity and weatherability, it is supposed to be suitably used as a seal for bearings.
　ところで、自動車は高温の地域や寒冷地など過酷な環境下で使用されることも少なくないため、自動車用部品に用いられるゴム成形品には、このような使用に耐えうる物性が要求される。また、近年、自動車用部品に求められる性能も厳しくなっていて、それに伴ってゴム成形品に要求される物性も厳しくなっている。そのため、より優れた耐熱性及び耐低温性を有するゴム成形品が望まれていた。 By the way, since automobiles are often used under severe environments such as high temperature areas and cold regions, rubber molded articles used for automobile parts are required to have physical properties that can withstand such use. Further, in recent years, the performance required for automotive parts has become severe, and the physical properties required for rubber molded articles have become severe along with it. Therefore, a rubber molded article having more excellent heat resistance and low temperature resistance has been desired.
国際公開第２０１７／０３３９８６号International Publication No. 2017/033986
　本発明は上記課題を解決するためになされたものであり、耐熱性及び耐低温性に優れたゴム成形品を提供することを目的とする。また本発明は、このようなゴム成形品を得るためのゴム組成物を提供することを目的とする。 The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a rubber molded article excellent in heat resistance and low temperature resistance. Another object of the present invention is to provide a rubber composition for obtaining such a rubber molded article.
　上記課題は、ニトリルゴム（Ａ）１００質量部、カーボンブラック（Ｂ）５～１００質量部、焼成カオリン（Ｃ）５～７５質量部、珪藻土（Ｄ）５～７５質量部、及び可塑剤（Ｅ）１～３０質量部を含有し、ニトリルゴム（Ａ）のアクリロニトリル単位の含有量が２５～３０質量％であり、かつ１５０℃で２４時間放置後の可塑剤（Ｅ）の加熱減量率が５質量％以下であることを特徴とするゴム組成物を提供することによって解決される。 The above-mentioned subjects are 100 parts by mass of nitrile rubber (A), 5 to 100 parts by mass of carbon black (B), 5 to 75 parts by mass of calcined kaolin (C), 5 to 75 parts by mass of diatomaceous earth (D), and plasticizer (E) And 5) containing 1 to 30 parts by mass, the acrylonitrile unit content of the nitrile rubber (A) is 25 to 30% by mass, and the heating loss ratio of the plasticizer (E) after leaving at 150 ° C. for 24 hours is 5 The problem is solved by providing a rubber composition characterized in that it is not more than mass%.
　このとき、前記ゴム組成物が、老化防止剤（Ｆ）０．１～１０質量部をさらに含有することが好ましい。また、前記ゴム組成物が、老化防止剤（Ｆ）として、ジチオカルバミン酸塩及びマイクロクリスタリンワックスを含有してなることが好ましい。また、前記ゴム組成物が、融点が４５～１００℃のパラフィンワックス（Ｇ）０．５～１０質量部をさらに含有してなることも好ましい。 At this time, it is preferable that the rubber composition further contain 0.1 to 10 parts by mass of an antioxidant (F). Moreover, it is preferable that the said rubber composition contains dithio carbamate and microcrystalline wax as an antiaging agent (F). The rubber composition preferably further contains 0.5 to 10 parts by mass of paraffin wax (G) having a melting point of 45 to 100 ° C.
　上記ゴム組成物を加硫してなるゴム成形品が本発明の好適な実施態様である。また、上記ゴム成形品からなるシール又はガスケットも本発明の好適な実施態様である。 A rubber molded article obtained by vulcanizing the above rubber composition is a preferred embodiment of the present invention. In addition, a seal or a gasket made of the above-mentioned rubber molded article is also a preferred embodiment of the present invention.
　本発明により、耐熱性及び耐低温性に優れたゴム成形品を提供することができる。また、このようなゴム成形品を得るためのゴム組成物を提供することができる。 According to the present invention, a rubber molded article excellent in heat resistance and low temperature resistance can be provided. Moreover, the rubber composition for obtaining such a rubber molded article can be provided.
　本発明は、ニトリルゴム（Ａ）１００質量部、カーボンブラック（Ｂ）５～１００質量部、焼成カオリン（Ｃ）５～７５質量部、珪藻土（Ｄ）５～７５質量部、及び可塑剤（Ｅ）１～３０質量部を含有し、ニトリルゴム（Ａ）のアクリロニトリル単位の含有量が２５～３０質量％であり、かつ１５０℃で２４時間放置後の可塑剤（Ｅ）の加熱減量率が５質量％以下であることを特徴とするゴム組成物である。 The present invention comprises 100 parts by mass of nitrile rubber (A), 5 to 100 parts by mass of carbon black (B), 5 to 75 parts by mass of calcined kaolin (C), 5 to 75 parts by mass of diatomaceous earth (D), and a plasticizer (E) And 5) containing 1 to 30 parts by mass, the acrylonitrile unit content of the nitrile rubber (A) is 25 to 30% by mass, and the heating loss ratio of the plasticizer (E) after leaving at 150 ° C. for 24 hours is 5 It is the rubber composition characterized by being below mass%.
［ニトリルゴム（Ａ）］
　本発明で用いられるニトリルゴム（Ａ）としては、アクリロニトリルと１，３－ブタジエンの共重合体が挙げられる。重合後の１，３－ブタジエン単位に残存する二重結合への水素添加は任意である。水素添加されていないニトリルゴムと水素添加されたニトリルゴムとを適宜使い分けることができる。 [Nitrile rubber (A)]
As a nitrile rubber (A) used by this invention, the copolymer of an acrylonitrile and a 1, 3- butadiene is mentioned. Hydrogenation to the double bond remaining in the 1,3-butadiene unit after polymerization is optional. Non-hydrogenated nitrile rubber and hydrogenated nitrile rubber can be properly used properly.
　本発明において、ニトリルゴム（Ａ）のアクリロニトリル単位の含有量は２５～３０質量％である。耐熱性と耐低温性とのバランスの観点から、アクリロニトリル単位の含有量が上記範囲であることが重要である。アクリロニトリル単位の含有量は２６質量％以上であることが好ましい。一方、アクリロニトリル単位の含有量は２９質量％以下であることが好ましい。１，３－ブタジエン単位の含有量は水素添加されたものも含めて、残りの全部又は大部分を占める。 In the present invention, the content of acrylonitrile units of the nitrile rubber (A) is 25 to 30% by mass. From the viewpoint of the balance between heat resistance and low temperature resistance, it is important that the content of the acrylonitrile unit is in the above range. The content of the acrylonitrile unit is preferably 26% by mass or more. On the other hand, the content of acrylonitrile units is preferably 29% by mass or less. The content of 1,3-butadiene units, including hydrogenated ones, accounts for all or most of the remainder.
　本発明で用いられるニトリルゴム（Ａ）は、本発明の効果を阻害しない範囲であれば、他の共重合可能な単量体由来の構成単位を含んでいてもかまわない。例えば、カルボキシル基又はカルボン酸無水物基のような官能基を含むものであってもよい。このような他の単量体の共重合量は、通常、１０モル％以下であり、５モル％以下であることが好ましく、２モル％以下であることがより好ましい。 The nitrile rubber (A) used in the present invention may contain a structural unit derived from another copolymerizable monomer as long as the effect of the present invention is not impaired. For example, it may contain a functional group such as a carboxyl group or a carboxylic acid anhydride group. The copolymerization amount of such other monomers is usually 10 mol% or less, preferably 5 mol% or less, and more preferably 2 mol% or less.
　ニトリルゴム（Ａ）のムーニー粘度（ＭＬ１＋４、１００℃）は１０～１２０であることが好ましい。ゴム組成物の成形性の観点から、ムーニー粘度は、１０以上であることが好ましく、２０以上であることがより好ましい。一方、ゴム成形品の強度の観点から、ムーニー粘度は１２０以下であることが好ましく、１００以下であることがより好ましい。 The Mooney viscosity (ML 1 +4 , 100 ° C.) of the nitrile rubber (A) is preferably 10 to 120. From the viewpoint of the moldability of the rubber composition, the Mooney viscosity is preferably 10 or more, and more preferably 20 or more. On the other hand, the Mooney viscosity is preferably 120 or less, more preferably 100 or less, from the viewpoint of the strength of the rubber molded article.
　ニトリルゴム（Ａ）は、１種類を単独で用いてもよく、２種類以上を混合して用いてもよい。ここで、ニトリルゴムを混合して使用する場合、混合後のニトリルゴムにおけるアクリロニトリル単位の含有量やムーニー粘度はニトリルゴムの配合比を考慮した平均値とする。 A nitrile rubber (A) may be used individually by 1 type, and may mix and use 2 or more types. Here, when using a mixture of nitrile rubber, the content of the acrylonitrile unit in the mixed nitrile rubber and the Mooney viscosity are taken as an average value taking into consideration the blending ratio of the nitrile rubber.
［カーボンブラック（Ｂ）］
　本発明で用いられるカーボンブラック（Ｂ）の種類は特に限定されず、ＳＡＦ、ＩＳＡＦ、ＨＡＦ、ＦＥＦ、ＧＰＦ、ＭＡＦ、ＳＲＦ、ＦＴ、ＭＴ等を用いることができ、性能とコストのバランスの点からＦＥＦ、ＦＴ、ＭＴ、ＳＲＦ、ＭＡＦが好適である。カーボンブラック（Ｂ）として、２種類以上のカーボンブラックを組み合わせて用いることもできる。 [Carbon black (B)]
The type of carbon black (B) used in the present invention is not particularly limited, and SAF, ISAF, HAF, FEF, GPF, MAF, SRF, FT, MT, etc. can be used, and in terms of the balance between performance and cost. FEF, FT, MT, SRF, MAF are preferred. As carbon black (B), two or more types of carbon black can be used in combination.
　カーボンブラック（Ｂ）の含有量は、ニトリルゴム（Ａ）１００質量部に対して５～１００質量部である。カーボンブラック（Ｂ）の含有量が５質量部未満の場合、ゴム成形品の引張強さが不十分となる。カーボンブラック（Ｂ）の含有量は１０質量部以上であることが好ましく、２０質量部以上であることがより好ましく、３０質量部以上であることがさらに好ましい。一方、カーボンブラック（Ｂ）の含有量が１００質量部を超えると、成形性が悪化する。カーボンブラック（Ｂ）の含有量は９０質量部以下であることが好ましく、８０質量部以下であることがより好ましい。 The content of carbon black (B) is 5 to 100 parts by mass with respect to 100 parts by mass of nitrile rubber (A). When the content of the carbon black (B) is less than 5 parts by mass, the tensile strength of the rubber molded article is insufficient. The content of carbon black (B) is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, and still more preferably 30 parts by mass or more. On the other hand, when the content of carbon black (B) exceeds 100 parts by mass, the formability is deteriorated. The content of carbon black (B) is preferably 90 parts by mass or less, and more preferably 80 parts by mass or less.
　カーボンブラック（Ｂ）の平均一次粒子径は特に限定されず、通常、５～２００ｎｍである。ゴム組成物への配合量が少量であってもゴム成形品の引張強さを向上させることができる観点から、カーボンブラック（Ｂ）の平均一次粒子径が４０ｎｍ以下であることが好ましく、３０ｎｍ以下であることがより好ましい。 The average primary particle size of the carbon black (B) is not particularly limited, and is usually 5 to 200 nm. The average primary particle diameter of the carbon black (B) is preferably 40 nm or less, and preferably 30 nm or less, from the viewpoint that the tensile strength of the rubber molded product can be improved even if the compounding amount to the rubber composition is small. It is more preferable that
［焼成カオリン（Ｃ）、珪藻土（Ｄ）］
　本発明のゴム組成物は、焼成カオリン（Ｃ）と珪藻土（Ｄ）とを含む。ここでカオリンは、含水ケイ酸アルミニウム（組成式：Al2Si2O5(OH)4）を主成分とする天然の粘土鉱物である。そして、焼成カオリンは、この粘土鉱物を精製した後に、高温で焼き結晶水を除去したものである。一方、珪藻土は、単細胞藻類の一種である珪藻の殻の化石よりなる堆積物であり、二酸化ケイ素（SiO2）が主成分である。 [Calcinated kaolin (C), diatomaceous earth (D)]
The rubber composition of the present invention comprises calcined kaolin (C) and diatomaceous earth (D). Here, kaolin is a natural clay mineral containing hydrous aluminum silicate (composition formula: Al 2 Si 2 O 5 (OH) 4 ) as a main component. And after baking kaolin refines this clay mineral, baking water is removed at high temperature. On the other hand, diatomaceous earth is a deposit composed of fossil shells of diatoms, which is a kind of single cell algae, and is mainly composed of silicon dioxide (SiO 2 ).
　焼成カオリン（Ｃ）及び珪藻土（Ｄ）のうち、焼成カオリン（Ｃ）だけを配合して得られたゴム成形品は、加熱されることによって、硬度が上昇し過ぎるとともに、伸びが小さくなってしまう。一方、珪藻土（Ｄ）だけを配合して得られたゴム成形品は、ガラス転移点が上がりすぎてしまう。したがって、ゴム成形物における、焼成カオリン（Ｃ）及び珪藻土（Ｄ）それぞれの含有量が重要である。 The rubber molded product obtained by blending only the calcined kaolin (C) among the calcined kaolin (C) and the diatomaceous earth (D) is heated and thereby the hardness is excessively increased and the elongation is decreased. . On the other hand, in the rubber molded product obtained by blending only diatomaceous earth (D), the glass transition point is too high. Therefore, the content of each of the calcined kaolin (C) and the diatomaceous earth (D) in the rubber molding is important.
　焼成カオリン（Ｃ）の含有量は、ニトリルゴム（Ａ）１００質量部に対して５～７５質量部である。焼成カオリン（Ｃ）の含有量は、１０質量部以上であることが好ましく、１５質量部以上であることがより好ましい。一方、焼成カオリン（Ｃ）の含有量は７０質量部以下であることが好ましく、６０質量部以下であることがより好ましい。 The content of the calcined kaolin (C) is 5 to 75 parts by mass with respect to 100 parts by mass of the nitrile rubber (A). The content of the calcined kaolin (C) is preferably 10 parts by mass or more, and more preferably 15 parts by mass or more. On the other hand, the content of the calcined kaolin (C) is preferably 70 parts by mass or less, and more preferably 60 parts by mass or less.
　珪藻土（Ｄ）の含有量は、ニトリルゴム（Ａ）１００質量部に対して５～７５質量部である。珪藻土（Ｄ）の含有量は、１０質量部以上であることが好ましく、１５質量部以上であることがより好ましい。一方、珪藻土（Ｄ）の含有量は７０質量部以下であることが好ましく、６０質量部以下であることがより好ましい。 The content of diatomaceous earth (D) is 5 to 75 parts by mass with respect to 100 parts by mass of nitrile rubber (A). The content of diatomaceous earth (D) is preferably 10 parts by mass or more, and more preferably 15 parts by mass or more. On the other hand, the content of diatomaceous earth (D) is preferably 70 parts by mass or less, and more preferably 60 parts by mass or less.
　焼成カオリン（Ｃ）及び珪藻土（Ｄ）の合計量は、ニトリルゴム（Ａ）１００質量部に対して、１００質量部以下であることが好ましく、８０質量部以下であることがより好ましい。また、ゴム組成物における、焼成カオリン（Ｃ）と珪藻土（Ｄ）との質量比［（Ｃ）／（Ｄ）］は、通常、９０／１０～１０／９０であり、好適には８０／２０～２０／８０であり、より好適には７０／３０～３０／７０である。なお、焼成カオリン（Ｃ）は、脂肪酸、界面活性剤、シランカップリング剤等で表面処理されたものであってもよい。また、珪藻土（Ｄ）についても、同様に、脂肪酸、界面活性剤、シランカップリング剤等で表面処理されたものであってもよい。 The total amount of the calcined kaolin (C) and the diatomaceous earth (D) is preferably 100 parts by mass or less and more preferably 80 parts by mass or less with respect to 100 parts by mass of the nitrile rubber (A). In the rubber composition, the mass ratio [(C) / (D)] of calcined kaolin (C) to diatomaceous earth (D) is usually 90/10 to 10/90, preferably 80/20. 20 to 80, more preferably 70/30 to 30/70. The calcined kaolin (C) may be surface-treated with a fatty acid, a surfactant, a silane coupling agent or the like. Further, the diatomaceous earth (D) may be similarly surface-treated with a fatty acid, a surfactant, a silane coupling agent or the like.
［可塑剤（Ｅ）］
　本発明のゴム組成物は可塑剤（Ｅ）を含む。本発明においては、１５０℃で２４時間放置後の加熱減量率が５質量％以下である可塑剤（Ｅ）を用いることが重要である。加熱減量率が５質量％を超える場合、加熱するとゴム成形品の硬度が上昇し、耐熱性に優れたゴム成形品を得ることができない。加熱減量率は、４質量％以下であることが好ましく、３質量％以下であることがより好ましく、２．５質量％以下であることがさらに好ましい。ここで本明細書における加熱減量率とは、加熱前のゴム組成物の質量から、加熱後のゴム組成物の質量を差し引いた値を、加熱前のゴム組成物の質量で除して百分率として表したものである。加熱減量率の測定方法の詳細は、後の実施例に記載した通りである。 [Plasticizer (E)]
The rubber composition of the present invention contains a plasticizer (E). In the present invention, it is important to use a plasticizer (E) having a heating loss ratio of 5% by mass or less after standing at 150 ° C. for 24 hours. When the heating loss ratio exceeds 5% by mass, when heated, the hardness of the rubber molded article is increased, and a rubber molded article excellent in heat resistance can not be obtained. The heating loss ratio is preferably 4% by mass or less, more preferably 3% by mass or less, and still more preferably 2.5% by mass or less. Here, the heating loss ratio in the present specification is a value obtained by subtracting the mass of the rubber composition after heating from the mass of the rubber composition before heating divided by the mass of the rubber composition before heating and expressed as a percentage. It is a representation. The details of the method for measuring the heating loss rate are as described in the examples below.
　本発明で用いられる可塑剤（Ｅ）は、加熱減量率が上述のものであればその種類は特に限定されず、一般にゴム組成物に混合される可塑剤が用いられる。例えば、フタル酸誘導体、テトラヒドロフタル酸誘導体、アジピン酸誘導体、アゼライン酸誘導体、セバシン酸誘導体、ドデカン－２－酸誘導体、マレイン酸誘導体、フマル酸誘導体、トリメリット酸誘導体、ピロメリット酸誘導体、クエン酸誘導体、オレイン酸誘導体、リシノール酸誘導体、ステアリン酸誘導体、スルホン酸誘導体、リン酸誘導体、グルタール酸誘導体、グリコール誘導体、グリセリン誘導体、パラフィン誘導体、エポキシ誘導体、重合型可塑剤（ポリエステル、ポリエーテルなど）等が挙げられる。これらの可塑剤は１種を単独で、または２種以上を組み合わせて使用することができる。 The type of the plasticizer (E) used in the present invention is not particularly limited as long as the heating loss ratio is as described above, and a plasticizer generally used in a rubber composition is used. For example, phthalic acid derivatives, tetrahydrophthalic acid derivatives, adipic acid derivatives, azelaic acid derivatives, sebacic acid derivatives, dodecane-2-acid derivatives, maleic acid derivatives, fumaric acid derivatives, trimellitic acid derivatives, pyromellitic acid derivatives, citric acid Derivatives, oleic acid derivatives, ricinoleic acid derivatives, stearic acid derivatives, sulfonic acid derivatives, phosphoric acid derivatives, glutaric acid derivatives, glycol derivatives, glycerin derivatives, paraffin derivatives, epoxy derivatives, polymeric plasticizers (polyesters, polyethers, etc.), etc. Can be mentioned. These plasticizers can be used alone or in combination of two or more.
　可塑剤（Ｅ）の含有量は、ニトリルゴム（Ａ）１００質量部に対して１～３０質量部である。可塑剤（Ｅ）の含有量が１質量部未満の場合、可塑剤（Ｅ）を配合する効果が不十分となる。可塑剤（Ｅ）の含有量は２質量部以上であることが好ましく、５質量部以上であることがより好ましい。一方、可塑剤（Ｅ）の含有量が３０質量部を超える場合、可塑剤（Ｅ）がブリードするおそれがある。可塑剤（Ｅ）の含有量は２５質量部以下であることが好ましく、２０質量部以下であることがより好ましい。 The content of the plasticizer (E) is 1 to 30 parts by mass with respect to 100 parts by mass of the nitrile rubber (A). When the content of the plasticizer (E) is less than 1 part by mass, the effect of blending the plasticizer (E) becomes insufficient. The content of the plasticizer (E) is preferably 2 parts by mass or more, and more preferably 5 parts by mass or more. On the other hand, when content of a plasticizer (E) exceeds 30 mass parts, there exists a possibility that a plasticizer (E) may bleed. The content of the plasticizer (E) is preferably 25 parts by mass or less, and more preferably 20 parts by mass or less.
［老化防止剤（Ｆ）］
　本発明において、前記ゴム組成物が、老化防止剤（Ｆ）をさらに含有してなることが好ましい。老化防止剤（Ｆ）としては、ジチオカルバミン酸塩、マイクロクリスタリンワックス、ナフチルアミン系、ジフェニルアミン系、ｐ－フェニレンジアミン系、キノリン系、ヒドロキノン系、フェノール系、含イオン系などが挙げられる。中でも、老化防止剤（Ｆ）はジチオカルバミン酸塩及びマイクロクリスタリンワックスの両方が含まれていることが好ましい。老化防止剤（Ｆ）が、ジチオカルバミン酸塩及びマイクロクリスタリンワックスの両方を含有することにより、耐オゾン性に優れたゴム成形品を得ることができる。ここで、マイクロクリスタリンワックスとは、主として原油の減圧蒸留残さ油分から取り出されるワックスのことをいい、後述するパラフィンワックス（Ｇ）に比べ、分岐炭化水素（イソパラフィン）や飽和環状炭化水素（シクロパラフィン）を多く含むものである。ジチオカルバミン酸塩としては、ジエチルジチオカルバミン酸ニッケル、ジブチルジチオカルバミン酸ニッケルなどが挙げられる。 [Anti-aging agent (F)]
In the present invention, it is preferable that the rubber composition further contains an antiaging agent (F). Examples of the antiaging agent (F) include dithiocarbamates, microcrystalline waxes, naphthylamines, diphenylamines, p-phenylenediamines, quinolines, hydroquinones, phenols, and ion-containings. Among them, it is preferable that the antiaging agent (F) contains both dithiocarbamate and microcrystalline wax. When the antiaging agent (F) contains both dithiocarbamate and microcrystalline wax, a rubber molded article having excellent ozone resistance can be obtained. Here, microcrystalline wax is a wax mainly extracted from the vacuum distillation residue of crude oil, and branched hydrocarbon (isoparaffin) and saturated cyclic hydrocarbon (cycloparaffin) compared to paraffin wax (G) described later. Contains many. Examples of dithiocarbamates include nickel diethyldithiocarbamate and nickel dibutyldithiocarbamate.
　老化防止剤（Ｆ）の含有量は、ニトリルゴム（Ａ）１００質量部に対して０．１～１０質量部であることが好ましい。老化防止剤（Ｆ）の含有量が、０．１質量部未満の場合、ゴム成形品の耐オゾン性が不十分となるおそれがある。老化防止剤（Ｆ）の含有量は、１質量部以上であることがより好ましく、２質量部以上であることがさらに好ましい。一方、老化防止剤（Ｆ）の含有量が、１０質量部を超える場合、ブルームが発生するおそれがある。老化防止剤（Ｆ）の含有量は、８質量部以下であることがより好ましい。 The content of the antiaging agent (F) is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the nitrile rubber (A). If the content of the antiaging agent (F) is less than 0.1 parts by mass, the ozone resistance of the rubber molded product may be insufficient. The content of the antiaging agent (F) is more preferably 1 part by mass or more, and still more preferably 2 parts by mass or more. On the other hand, when the content of the antiaging agent (F) exceeds 10 parts by mass, bloom may occur. The content of the antioxidant (F) is more preferably 8 parts by mass or less.
　老化防止剤（Ｆ）としてジチオカルバミン酸塩とマイクロクリスタリンワックスとを併用する場合、老化防止剤（Ｆ）における、ジチオカルバミン酸塩（Ｘ）とマイクロクリスタリンワックス（Ｙ）との質量比［（Ｘ）／（Ｙ）］は、通常、９０／１０～１０／９０であり、好適には８０／２０～２０／８０であり、より好適には７０／３０～３０／７０である。 When dithiocarbamate and microcrystalline wax are used in combination as antiaging agent (F), the mass ratio of dithiocarbamate (X) to microcrystalline wax (Y) in the antiaging agent (F) [(X) / (Y)] is usually 90/10 to 10/90, preferably 80/20 to 20/80, more preferably 70/30 to 30/70.
［パラフィンワックス（Ｇ）］
　本発明において、ゴム成形品の耐オゾン性をより向上させる観点から、前記ゴム組成物が、パラフィンワックス（Ｇ）をさらに含有してなることが好ましい。ここでパラフィンワックス（Ｇ）とは、原油の減圧蒸留留出油分から、結晶性の良い炭化水素を分離抽出したものをいい、直鎖状炭化水素（ノルマルパラフィン）を主成分として含むものである。またパラフィンワックス（Ｇ）は、通常、ゴム成形品の製造時において、混練性や金型離型性を向上させるためにゴム組成物に配合するものである。これらの理由から、パラフィンワックス（Ｇ）と、上述したマイクロクリスタリンワックス（老化防止剤）とは、当業者において明確に区別されている。 [Paraffin wax (G)]
In the present invention, it is preferable that the rubber composition further contains a paraffin wax (G) from the viewpoint of further improving the ozone resistance of the rubber molded article. Here, paraffin wax (G) refers to one obtained by separating and extracting a hydrocarbon with good crystallinity from a vacuum distillation distillate of crude oil, which contains a linear hydrocarbon (normal paraffin) as a main component. Further, paraffin wax (G) is usually added to a rubber composition in order to improve kneadability and mold releasability at the time of production of a rubber molded article. For these reasons, paraffin wax (G) and the microcrystalline wax (anti-aging agent) described above are clearly distinguished by those skilled in the art.
　パラフィンワックス（Ｇ）の融点は４５～１００℃であることが好ましい。融点がこの範囲であるパラフィンワックス（Ｇ）を用いることにより、ゴム成形品の耐オゾン性をより向上させることができる。融点は４８℃以上であることがより好ましく、５０℃以上であることがさらに好ましい。一方、融点は９０℃以下であることがより好ましく、８０℃以下であることがさらに好ましい。 The melting point of paraffin wax (G) is preferably 45 to 100.degree. By using paraffin wax (G) having a melting point in this range, the ozone resistance of the rubber molded article can be further improved. The melting point is more preferably 48 ° C. or more, further preferably 50 ° C. or more. On the other hand, the melting point is more preferably 90 ° C. or less, still more preferably 80 ° C. or less.
　パラフィンワックス（Ｇ）の含有量は、ニトリルゴム（Ａ）１００質量部に対して０．５～１０質量部であることが好ましい。パラフィンワックス（Ｇ）の含有量がこの範囲であることにより、ゴム成形品の耐オゾン性をより向上させることができる。パラフィンワックス（Ｇ）の含有量は０．７質量部以上であることがより好ましい。一方、パラフィンワックス（Ｇ）の含有量は５質量部以下であることがより好ましい。 The content of paraffin wax (G) is preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of nitrile rubber (A). When the content of the paraffin wax (G) is in this range, the ozone resistance of the rubber molded article can be further improved. The content of the paraffin wax (G) is more preferably 0.7 parts by mass or more. On the other hand, the content of paraffin wax (G) is more preferably 5 parts by mass or less.
　上記ゴム組成物は、本発明の効果が阻害されない範囲において、ニトリルゴム（Ａ）、カーボンブラック（Ｂ）、焼成カオリン（Ｃ）、珪藻土（Ｄ）及び可塑剤（Ｅ）以外の他の成分を含んでいてもかまわない。他の成分としては、上述した老化防止剤（Ｆ）の他に、加硫剤、加硫助剤、加硫促進剤、加硫遅延剤、接着剤、受酸剤、着色剤、フィラー、加工助剤、カップリング剤、滑剤など、各種の添加剤が挙げられる。 The above rubber composition contains components other than nitrile rubber (A), carbon black (B), calcined kaolin (C), diatomaceous earth (D) and plasticizer (E) within the range that the effects of the present invention are not inhibited. You may include it. As other components, in addition to the anti-aging agent (F) described above, a vulcanizing agent, a vulcanizing aid, a vulcanization accelerator, a vulcanization retarder, an adhesive, an acid acceptor, a coloring agent, a filler, processing Various additives such as auxiliary agents, coupling agents and lubricants can be mentioned.
　本発明のゴム成形品の製造方法は特に限定されないが、好適な製造方法は、ニトリルゴム（Ａ）、カーボンブラック（Ｂ）、焼成カオリン（Ｃ）、珪藻土（Ｄ）、可塑剤（Ｅ）及び加硫剤を混練してゴム組成物を得る混練工程と、前記ゴム組成物を成形する成形工程と、前記ゴム組成物を加硫する加硫工程とを備える方法である。 Although the method for producing the rubber molded article of the present invention is not particularly limited, preferred production methods include nitrile rubber (A), carbon black (B), calcined kaolin (C), diatomaceous earth (D), plasticizer (E) and The method includes a kneading step of kneading a vulcanizing agent to obtain a rubber composition, a molding step of molding the rubber composition, and a vulcanization step of vulcanizing the rubber composition.
　混練工程において上記成分を混合する方法は特に限定されず、オープンロール、ニーダ、バンバリーミキサ、インターミキサ、押出機などを用いて混練することができる。中でも、バンバリーミキサ、インターミキサ又はニーダを用いて混練することが好ましい。混練時の温度は２０～１４０℃とすることが好ましい。 The method of mixing the above-mentioned components in the kneading step is not particularly limited, and kneading can be performed using an open roll, a kneader, a Banbury mixer, an intermixer, an extruder, or the like. Above all, it is preferable to knead using a Banbury mixer, an intermixer or a kneader. The temperature during kneading is preferably 20 to 140.degree.
　こうして得られたゴム組成物を成形工程で成形し、引き続いて加硫工程で加硫することによって、本発明のゴム成形品が得られる。 The rubber composition of the present invention is obtained by molding the rubber composition thus obtained in a molding step and subsequently vulcanizing in a vulcanization step.
　ゴム組成物の成形方法としては、射出成形、押出成形、圧縮成形、ロール成形などが挙げられる。中でも射出成形と圧縮成形が好適である。このとき、予め成形した後に加硫させてもよいし、成形と同時に加硫させてもよい。加硫温度は、通常１５０～２３０℃であることが好ましい。加硫時間は、通常０．１～６０分である。加硫させるための加熱方法としては、圧縮加熱、スチーム加熱、オーブン加熱、熱風加熱などのゴムの加硫に用いられる一般的な方法が用いられる。 As a method of forming the rubber composition, injection molding, extrusion molding, compression molding, roll molding and the like can be mentioned. Among them, injection molding and compression molding are preferable. At this time, it may be vulcanized after being molded in advance, or may be vulcanized simultaneously with molding. The vulcanization temperature is preferably 150 to 230 ° C. in general. The vulcanization time is usually 0.1 to 60 minutes. As a heating method for vulcanization, a general method used for vulcanization of rubber such as compression heating, steam heating, oven heating, hot air heating and the like is used.
　また、ゴム成形品の形状や寸法などによっては、表面が加硫していても内部まで十分に加硫していない場合があるので、さらに加熱して二次加硫を行ってもよい。 Further, depending on the shape and size of the rubber molded product, even if the surface is vulcanized, the inside may not be sufficiently vulcanized. Therefore, secondary vulcanization may be performed by further heating.
　加硫の方法は特に限定されず、硫黄加硫、過酸化物加硫などが挙げられる。硫黄加硫する際の加硫剤としては、硫黄や硫黄含有化合物が用いられる。また、過酸化物加硫する際の加硫剤としては有機過酸化物が用いられる。このとき用いられる加硫剤の量はニトリルゴム（Ａ）１００質量部に対して通常０．１～１０質量部である。 The method of vulcanization is not particularly limited, and examples thereof include sulfur vulcanization and peroxide vulcanization. Sulfur or a sulfur-containing compound is used as a vulcanizing agent at the time of sulfur vulcanization. Moreover, an organic peroxide is used as a vulcanizing agent at the time of peroxide vulcanization. The amount of the vulcanizing agent used at this time is usually 0.1 to 10 parts by mass with respect to 100 parts by mass of the nitrile rubber (A).
　以上説明したように本発明によれば、耐熱性及び耐低温性に優れたゴム成形品を得ることができる。したがって、このような特性を活かして、本発明のゴム成形品は自動車に搭載されるシール又はガスケットに好適に用いられる。シールとしては、ベアリングシール、オイルシール、軸シールなどが挙げられる。ガスケットとしては、シリンダヘッドカバー用のガスケット、オイルパン用のガスケットなどが挙げられる。 As described above, according to the present invention, a rubber molded article excellent in heat resistance and low temperature resistance can be obtained. Therefore, taking advantage of such characteristics, the rubber molded article of the present invention is suitably used for a seal or a gasket mounted on an automobile. The seal may, for example, be a bearing seal, an oil seal or a shaft seal. Examples of the gasket include a gasket for a cylinder head cover, a gasket for an oil pan, and the like.
　以下の実施例で使用した原料は以下の通りである。 The raw materials used in the following examples are as follows.
・ニトリルゴム（Ａ１）
ＪＳＲ株式会社製「Ｎ２４１」（アクリロニトリル単位の含有量：２９％、ムーニー粘度（ＭＬ１＋４、１００℃）：５６）
・ニトリルゴム（Ａ２）
ＪＳＲ株式会社製「Ｎ２４０Ｓ」（アクリロニトリル単位の含有量：２６％、ムーニー粘度（ＭＬ１＋４、１００℃）：５６）
・ニトリルゴム（Ａ３）
日本ゼオン株式会社製「Ｎｉｐｏｌ ＤＮ２８５０」（アクリロニトリル単位の含有量：２８％、ムーニー粘度（ＭＬ１＋４、１００℃）：５０） ・ Nitrile rubber (A1)
JSR Corporation "N241" (Acrylonitrile unit content: 29%, Mooney viscosity (ML 1 + 4 , 100 ° C.): 56)
・ Nitrile rubber (A2)
JSR Corporation “N 240 S” (Acrylonitrile unit content: 26%, Mooney viscosity (ML 1 + 4 , 100 ° C.): 56)
・ Nitrile rubber (A3)
Nippon Zeon Co., Ltd. “Nipol DN 2850” (Acrylonitrile unit content: 28%, Mooney viscosity (ML 1 + 4 , 100 ° C.): 50)
・カーボンブラック（Ｂ１）
旭カーボン株式会社製ＦＥＦ（Fast Extruding Furnace）「旭＃６０」（平均一次粒子径：４５ｎｍ）
・カーボンブラック（Ｂ２）
東海カーボン社製の「シースト３」（平均一次粒子径：２８ｎｍ） ・ Carbon black (B1)
Asahi Carbon Co., Ltd. FEF (Fast Extruding Furnace) "Asahi # 60" (average primary particle diameter: 45 nm)
・ Carbon black (B2)
"Siest 3" manufactured by Tokai Carbon (average primary particle diameter: 28 nm)
・焼成カオリン（Ｃ）
竹原化学工業株式会社製の商品名「Satintone No.5」
・珪藻土（Ｄ）
昭和化学工業株式会社製の商品名「ラヂオライト Ｆ」 ・ Firing kaolin (C)
Brand name "Satintone No. 5" manufactured by Takehara Chemical Industry Co., Ltd.
・ Diatomaceous earth (D)
Brand name "Radiolight F" manufactured by Showa Chemical Industry Co., Ltd.
・可塑剤（Ｅ１）
株式会社ＡＤＥＫＡ製のトリメリット酸エステル系可塑剤「アデカサイザー Ｃ－９Ｎ」
・可塑剤（Ｅ２）
株式会社ＡＤＥＫＡ製のポリエーテルエステル系可塑剤「アデカサイザー ＰＮ－２８０」
・可塑剤（Ｅ３）
株式会社ＡＤＥＫＡ製のＤＯＡ（ビス(2-エチルヘキシル)アジペート） ・ Plasticizer (E1)
Trimellitic acid ester plasticizer "ADEKACIZER C-9N" manufactured by ADEKA Corporation
・ Plasticizer (E2)
ADEKA Corporation polyetherester plasticizer "Adekasizer PN-280"
・ Plasticizer (E3)
DOA (bis (2-ethylhexyl) adipate) manufactured by ADEKA Corporation
・老化防止剤（Ｆ１）
アルキルジフェニルアミン（大内新興化学工業株式会社製の商品名「ノクラックＯＤＡ」）
・老化防止剤（Ｆ２）
ジブチルジチオカルバミン酸ニッケル（大内新興化学工業株式会社製の商品名「ノクラックＮＢＣ」）
・老化防止剤（Ｆ３）
大内新興化学工業株式会社製のマイクロクリスタリンワックス商品名「サンノック」 ・ Anti-aging agent (F1)
Alkyl diphenylamine (brand name "NOCRACK ODA" made by Ouchi Emerging Chemical Industry Co., Ltd.)
・ Anti-aging agent (F2)
Dibutyl dithiocarbamate nickel (trade name "NOCLAK NBC" manufactured by Ouchi Shinko Chemical Co., Ltd.)
・ Anti-aging agent (F3)
Microcrystalline wax made by Ouchi Emerging Chemical Industry Co., Ltd.
・加硫促進剤（ＤＭ）
大内新興化学工業株式会社製「ノクセラーＤＭ－Ｐ」（化学名：ジ-２-ベンゾチアゾリルジスルフィド）
・加硫促進剤（ＴＴ）
大内新興化学工業株式会社製「ノクセラーＴＴ－Ｐ」（化学名：テトラメチルチウラムジスルフィド） ・ Vulcanization accelerator (DM)
Ouchi Emerging Chemical Industry Co., Ltd. "Noxceler DM-P" (chemical name: di-2-benzothiazolyl disulfide)
・ Vulcanization accelerator (TT)
Ouchi Emerging Chemical Industry Co., Ltd. "Noxceler TT-P" (chemical name: tetramethylthiuram disulfide)
・パラフィンワックス（Ｇ）
日本精蝋社製の品名「パラフィンワックス１３５」（融点：５８℃、油分：０．３質量％、針入度：１３（２５℃）、２１（３５℃）、粘度：３．９ｍｍ２／ｓ／１００℃、セーボルト色：＋３０、密度：０．９１１ｇ／ｃｍ３（２５℃）、０．７７５ｇ／ｃｍ３（７０℃）、引火点：２３４℃、平均分子量：３８９（ガスクロマトフィー法）） ・ Paraffin wax (G)
Product name "paraffin wax 135" (melting point: 58 ° C, oil content: 0.3% by mass, penetration: 13 (25 ° C), 21 (35 ° C), viscosity: 3.9 mm 2 / s / 100 ° C., Saybolt color: +30, density: 0.911 g / cm 3 (25 ° C.), 0.775 g / cm 3 (70 ° C.), flash point: 234 ° C., average molecular weight: 389 (gas chromatography method))
実施例１
（ゴムシートの作製）
　以下に示す組成の混合物を、オープンロールを用いて温度２０～１００℃で１０～３０分間混練してゴム組成物を得た。そして、このゴム組成物を用いて、厚さ２ｍｍの未加硫ゴムシートを作製した（以下、単に未加硫ゴムシートと称すことがある）。
　・ニトリルゴム（Ａ１）：１００質量部
　・カーボンブラック（Ｂ１）：５０質量部
　・焼成カオリン（Ｃ）：２５質量部
　・珪藻土（Ｄ）：２５質量部
　・可塑剤（Ｅ１）：１５質量部
　・老化防止剤(Ｆ１)：２質量部
　・老化防止剤(Ｆ２)：１質量部
　・老化防止剤(Ｆ３)：１質量部
　・活性亜鉛華：５質量部
　・ステアリン酸：１質量部
　・硫黄：１．５質量部
　・加硫促進剤（ＤＭ）：１質量部
　・加硫促進剤（ＴＴ）：１質量部 Example 1
(Production of rubber sheet)
The mixture having the composition shown below was kneaded using an open roll at a temperature of 20 to 100 ° C. for 10 to 30 minutes to obtain a rubber composition. Then, using this rubber composition, an unvulcanized rubber sheet having a thickness of 2 mm was produced (hereinafter, may be simply referred to as an unvulcanized rubber sheet).
Nitrile rubber (A1): 100 parts by mass Carbon black (B1): 50 parts by mass Calcined kaolin (C): 25 parts by mass Diatomaceous earth (D): 25 parts by mass Plasticizer (E1): 15 parts by mass Anti-aging agent (F1): 2 parts by mass Anti-aging agent (F2): 1 part by mass Anti-aging agent (F3): 1 part by mass Active zinc flower: 5 parts by mass Stearic acid: 1 part by mass Sulfur: 1.5 parts by mass Vulcanization accelerator (DM): 1 part by mass Curing accelerator (TT): 1 part by mass
［評価］
（加硫特性）
　得られた未加硫ゴムシートを試料とし、ＪＩＳ Ｋ６３００－２に準拠し、ＪＳＲトレーディング株式会社製の「キュラストメーター７」を用いて測定した。測定温度１８０℃で５分間の加硫曲線を測定し、縦軸をトルク、横軸を時間としたグラフのトルクの最小値ＭＬ（ｋｇｆ・ｃｍ）、最大値ＭＨ（ｋｇｆ・ｃｍ）、ＭＨの１０％のトルクになるまでの時間Ｔ１０（分）及びＭＨの９０％のトルクになるまでの時間Ｔ９０（分）を求めた。その結果、Ｔ１０が０．７分、Ｔ９０が１．１分、ＭＬが３．７ｋｇｆ・ｃｍ及びＭＨが５５．１ｋｇｆ・ｃｍであった。 [Evaluation]
(Vulcanization characteristics)
The obtained unvulcanized rubber sheet was used as a sample, and measured in accordance with JIS K6300-2 using "Kurast meter 7" manufactured by JSR Trading Corporation. Measure the vulcanization curve at a measurement temperature of 180 ° C for 5 minutes, and measure the minimum value of torque torque ML (kgf cm), maximum value MH (kgf cm), MH in the graph with the vertical axis as torque and the horizontal axis as time. The time T10 (minutes) to reach 10% torque and the time T90 (minutes) to reach 90% torque of MH were determined. As a result, T10 was 0.7 minutes, T90 was 1.1 minutes, ML was 3.7 kgf · cm and MH was 55.1 kgf · cm.
（常態物性）
　得られた未加硫ゴムシートを用い、１２０℃で１０分間プレス加硫して、厚さ２ｍｍの加硫ゴムシートを得た（以下、単に加硫ゴムシートと称すことがある）。この加硫ゴムシートを３枚重ね、タイプＡデュロメータを用いて、２３℃、相対湿度５０％において測定を行い、ピーク値を読み取った。その結果、Ａ硬度は７１であった。また、上記加硫ゴムシートを用いて、２３℃、相対湿度５０％において、引張速度５００ｍｍ／分の引張速度で、引張強さ（ＭＰａ）と伸び（％）を測定した。その結果、引張強さは１２．９ＭＰａであり、伸びは３６０％であった。引張試験はＪＩＳ Ｋ６２５１に準拠して行い、硬度の測定はＪＩＳ Ｋ６２５３に準拠して行った。 (Normal physical properties)
The obtained unvulcanized rubber sheet was press-cured at 120 ° C. for 10 minutes to obtain a vulcanized rubber sheet having a thickness of 2 mm (hereinafter sometimes referred to simply as a vulcanized rubber sheet). Three sheets of this vulcanized rubber sheet were stacked, and measurement was performed at 23 ° C. and 50% relative humidity using a type A durometer, and the peak value was read. As a result, the A hardness was 71. Further, using the vulcanized rubber sheet, tensile strength (MPa) and elongation (%) were measured at a tensile speed of 500 mm / min at a temperature of 23 ° C. and a relative humidity of 50%. As a result, the tensile strength was 12.9 MPa and the elongation was 360%. The tensile test was performed according to JIS K6251, and the measurement of hardness was performed according to JIS K6253.
（熱老化試験）
　上記加硫ゴムシートを１７０℃で７０時間加熱した。加熱後、この加硫ゴムシートを３枚重ね、タイプＡデュロメータを用いて、２３℃、相対湿度５０％において測定を行い、ピーク値を読み取った。また、上記加熱後の加硫ゴムシートを用いて、２３℃、相対湿度５０％において、引張速度５００ｍｍ／分の引張速度で、引張強さ（ＭＰａ）と伸び（％）を測定した。熱老化試験は、ＪＩＳ Ｋ６２５７に準拠して行った。 (Thermal aging test)
The vulcanized rubber sheet was heated at 170 ° C. for 70 hours. After heating, three sheets of this vulcanized rubber sheet were stacked, and measurement was performed at 23 ° C. and 50% relative humidity using a type A durometer, and the peak value was read. Further, using the vulcanized rubber sheet after the heating, the tensile strength (MPa) and the elongation (%) were measured at a tensile speed of 500 mm / min at 23 ° C. and a relative humidity of 50%. The heat aging test was conducted in accordance with JIS K6257.
　そして、上記常態物性に対する値の変化を計算することで熱老化特性を評価した。その結果、硬さ変化は＋５ポイントであった。この硬さ変化とは、加熱後のＡ硬度から加熱前のＡ硬度を差し引いた値である。 And the heat aging characteristic was evaluated by calculating the change of the value with respect to the said normal-state physical property. As a result, the hardness change was +5 points. The hardness change is a value obtained by subtracting the A hardness before heating from the A hardness after heating.
　また、引張強さ変化率は＋４％であった。この引張強さ変化率とは、加熱後の引張強さの値から加熱前の引張強さの値を差し引いた値を、加熱前の引張強さの値で除して百分率で表したものである。この値が正のときは、加熱することによって引張強さが上昇したことを示し、負のときは引張強さが低下したことを示す。同様の計算方法で伸び変化率を計算したところ、伸び変化率は－３３％であった。結果を表１に示す。 In addition, the tensile strength change rate was + 4%. The rate of change in tensile strength is the value obtained by subtracting the value of tensile strength before heating from the value of tensile strength after heating divided by the value of tensile strength before heating and expressed as a percentage. is there. When this value is positive, it shows that tensile strength rose by heating, and when negative, it shows that tensile strength fell. When the rate of change in elongation was calculated by the same calculation method, the rate of change in elongation was -33%. The results are shown in Table 1.
（静的オゾン劣化試験）
　上記加硫ゴムシートを用い、下記の測定条件１～３で示される雰囲気下にそれぞれ加硫ゴムシートを放置した後に表面観察を行った。ゴムシート表面に亀裂が生じていた場合を「亀裂の有無」で「あり」とし、亀裂が生じていなかった場合を「亀裂の有無」で「なし」とした。結果を表１に示す。静的オゾン劣化試験は、ＪＩＳ Ｋ６２５９に準拠して行った。
　　測定条件１：静的伸張率２０％、温度４０℃、湿度１０％、オゾン濃度５０ｐｐｈｍの雰囲気下に４時間放置
　　測定条件２：静的伸張率５％、温度２３℃、湿度１０％、オゾン濃度２００ｐｐｈｍの雰囲気下に４８時間放置
　　測定条件３：静的伸張率５％、温度２３℃、湿度６５％、オゾン濃度２００ｐｐｈｍの雰囲気下に４８時間放置 (Static ozone deterioration test)
The surface of the vulcanized rubber sheet was observed after leaving the vulcanized rubber sheet to stand under the atmosphere indicated by the following measurement conditions 1 to 3 using the above-mentioned vulcanized rubber sheet. The case where a crack was generated on the surface of the rubber sheet was regarded as "presence or absence of a crack", and the case where no crack was generated was regarded as "none" as a "presence or absence of a crack". The results are shown in Table 1. The static ozone deterioration test was performed in accordance with JIS K6259.
Measurement condition 1: Static extension ratio 20%, Temperature 40 ° C, Humidity 10%, Leave for 4 hours under atmosphere of ozone concentration 50 pphm Measurement condition 2: Static extension ratio 5%, Temperature 23 ° C, Humidity 10%, Ozone concentration For 48 hours in an atmosphere of 200 pphm Measurement condition 3: For 48 hours in an atmosphere of a static elongation of 5%, a temperature of 23 ° C., a humidity of 65%, and an ozone concentration of 200 pphm
（ガラス転移温度）
　ゴム成形品のガラス転移温度（℃）を表１に示す。表１に示すガラス転移温度（℃）は、示差走査熱量計（ＤＳＣ）を用いて昇温速度１０℃／分で測定したガラス転移開始温度である。ガラス転移温度（℃）が低いほど耐低温性に優れている。 (Glass-transition temperature)
The glass transition temperature (° C.) of the rubber molded article is shown in Table 1. The glass transition temperature (° C.) shown in Table 1 is a glass transition start temperature measured at a temperature rising rate of 10 ° C./minute using a differential scanning calorimeter (DSC). The lower the glass transition temperature (° C.), the better the low temperature resistance.
（可塑剤（Ｅ）の加熱減量率）
　上記「ゴムシートの作製」において得られたゴム組成物を１５０℃のオーブンに入れ、２４時間放置することで可塑剤（Ｅ）の加熱減量率を求めた。ここで加熱減量率は、加熱前のゴム組成物の質量から、加熱後のゴム組成物の質量を差し引いた値を、加熱前のゴム組成物の質量で除して百分率で表した。その結果、可塑剤（Ｅ）の加熱減量率は２％であった。 (Heating loss rate of plasticizer (E))
The rubber composition obtained in the above "preparation of rubber sheet" was placed in an oven at 150 ° C., and left for 24 hours to determine the heating loss ratio of the plasticizer (E). Here, the heating loss ratio was represented by a value obtained by subtracting the mass of the rubber composition after heating from the mass of the rubber composition before heating divided by the mass of the rubber composition before heating. As a result, the heating loss ratio of the plasticizer (E) was 2%.
実施例２～１５及び比較例１～４
　上記「加硫ゴムシートの作製」において、成分の種類及び量を表１～３に示すように変更した以外は実施例１と同様にしてゴム組成物を得た。そして、得られたゴム組成物を用いて実施例１と同様の評価を行った。結果を表１～３に示す。 Examples 2 to 15 and Comparative Examples 1 to 4
A rubber composition was obtained in the same manner as in Example 1 except that in the above-mentioned "Production of Vulcanized Rubber Sheet", the types and amounts of the components were changed as shown in Tables 1 to 3. And evaluation similar to Example 1 was performed using the obtained rubber composition. The results are shown in Tables 1 to 3.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
  
Figure JPOXMLDOC01-appb-T000002
  
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003

Claims (6)

  1. 　ニトリルゴム（Ａ）１００質量部、カーボンブラック（Ｂ）５～１００質量部、焼成カオリン（Ｃ）５～７５質量部、珪藻土（Ｄ）５～７５質量部、及び可塑剤（Ｅ）１～３０質量部を含有し、
    　ニトリルゴム（Ａ）のアクリロニトリル単位の含有量が２５～３０質量％であり、かつ
    　１５０℃で２４時間放置後の可塑剤（Ｅ）の加熱減量率が５質量％以下であることを特徴とするゴム組成物。     100 parts by mass of nitrile rubber (A), 5 to 100 parts by mass of carbon black (B), 5 to 75 parts by mass of calcined kaolin (C), 5 to 75 parts by mass of diatomaceous earth (D), and 1 to 30 plasticizers (E) Contains parts by mass,
    The acrylonitrile unit content of the nitrile rubber (A) is 25 to 30% by mass, and the heating loss ratio of the plasticizer (E) after leaving at 150 ° C. for 24 hours is 5% by mass or less. Rubber composition.
  2. 　老化防止剤（Ｆ）０．１～１０質量部をさらに含有してなる請求項１に記載のゴム組成物。 The rubber composition according to claim 1, further comprising 0.1 to 10 parts by mass of an antiaging agent (F).
  3. 　老化防止剤（Ｆ）として、ジチオカルバミン酸塩及びマイクロクリスタリンワックスを含有してなる請求項２に記載のゴム組成物。 The rubber composition according to claim 2, comprising dithiocarbamate and microcrystalline wax as an antiaging agent (F).
  4. 　融点が４５～１００℃のパラフィンワックス（Ｇ）０．５～１０質量部をさらに含有してなる請求項１～３のいずれかに記載のゴム組成物。 The rubber composition according to any one of claims 1 to 3, further comprising 0.5 to 10 parts by mass of paraffin wax (G) having a melting point of 45 to 100 ° C.
  5. 　請求項１～４のいずれかに記載のゴム組成物を加硫してなるゴム成形品。 A rubber molded article obtained by vulcanizing the rubber composition according to any one of claims 1 to 4.
  6. 　請求項５に記載のゴム成形品からなるシール又はガスケット。 A seal or gasket comprising the rubber molded article according to claim 5.
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