WO2020095964A1

WO2020095964A1 - Rubber composition, vulcanized object, and vulcanized molded object

Info

Publication number: WO2020095964A1
Application number: PCT/JP2019/043557
Authority: WO
Inventors: 貴史砂田; 敦典近藤
Original assignee: デンカ株式会社
Priority date: 2018-11-09
Filing date: 2019-11-06
Publication date: 2020-05-14
Also published as: JP2022013964A

Abstract

A rubber composition which comprises 100 parts by mass of a chloroprene-based rubber, 20-80 parts by mass of carbon black, and 0.2-30 parts by mass of a zinc powder, wherein the chloroprene-based rubber includes structural units derived from an unsaturated nitrile monomer in an amount of 3-20 mass% and the carbon black has a crystal lattice in which the average C-axis-direction layer stack height LC is 2 nm or greater.

Description

Rubber composition, vulcanized product and vulcanized molded article

The present invention relates to a rubber composition, a vulcanized product and a vulcanized molded product.

Chloroprene rubber is excellent in ozone resistance and chemical resistance, and by utilizing its characteristics, it is used in a wide range of fields such as automobile parts, adhesives, and various industrial rubber parts. Further, in recent years, the performance required for industrial rubber parts has remarkably increased, and in addition to the above-mentioned improvement in ozone resistance and chemical resistance, excellent rubber processing stability, heat resistance, compression set, etc. It has been demanded.

In order to satisfy the above-mentioned required characteristics, for example, a technique of adding specific carbon black and zinc powder to chloroprene rubber to improve heat resistance (see, for example, Patent Document 1 below), and a specific plasticizer are further combined. Therefore, a technique for improving heat resistance (for example, see Patent Document 2 below) has been proposed.

JP-A-11-323020 Japanese Patent No. 4092270

In the field of chloroprene rubber, for a rubber composition for obtaining a vulcanized molded article, in addition to improving heat resistance as described above, it is required to obtain excellent oil resistance. It is required to obtain excellent heat resistance and oil resistance without lowering the mechanical strength and cold resistance.

An object of one aspect of the present invention is to provide a rubber composition capable of obtaining a vulcanized molded article having excellent mechanical strength, heat resistance, oil resistance and cold resistance. Another aspect of the present invention is to provide a vulcanized product and a vulcanized molded product of the rubber composition.

One aspect of the present invention comprises 100 parts by mass of chloroprene rubber, 20 to 80 parts by mass of carbon black, and 0.2 to 30 parts by mass of zinc powder, wherein the chloroprene rubber is an unsaturated nitrile unit amount. Provided is a rubber composition having 3 to 20% by mass of a body-derived structural unit and having an average stacking height LC of 2 nm or more in the C-axis direction of the layer plane in the crystal lattice of the carbon black.

Another aspect of the present invention provides a vulcanized product of the above rubber composition.

Another aspect of the present invention provides a vulcanized molded product of the above rubber composition.

According to one aspect of the present invention, in the field of chloroprene rubber, vulcanization molding that improves mechanical strength, heat resistance, oil resistance and cold resistance at the same time and is excellent in mechanical strength, heat resistance, oil resistance and cold resistance. A rubber composition for obtaining a body can be provided. According to another aspect of the present invention, a vulcanized product and a vulcanized molded product of the rubber composition can be provided. These rubber compositions, vulcanized products, and vulcanized molded products include transmission belts, conveyor belts, hoses, wipers, sealing materials (packings, gaskets, etc.), rolls, air springs, vibration damping materials, adhesives, boots, rubbers. It can be used as a material for rubber products used for pulling cloth, sponge, rubber lining and the like.

Hereinafter, modes for carrying out the present invention will be described. The embodiments described below are examples of typical embodiments of the present invention, and the scope of the present invention should not be construed narrowly.

In the present specification, the numerical range indicated by using "to" indicates the range including the numerical values before and after "to" as the minimum value and the maximum value, respectively. In the numerical ranges described stepwise in this specification, the upper limit value or the lower limit value of the numerical range of a certain stage can be arbitrarily combined with the upper limit value or the lower limit value of the numerical range of another stage. In the numerical range described in this specification, the upper limit value or the lower limit value of the numerical range may be replaced with the values shown in the examples. Unless otherwise specified, the materials exemplified in the present specification can be used alone or in combination of two or more kinds. The content of each component in the composition means the total amount of the plurality of substances present in the composition, unless a plurality of substances corresponding to each component are present in the composition, unless otherwise specified.

<Rubber composition>
The rubber composition of the present embodiment (chloroprene rubber composition) is a chloroprene rubber having a structural unit derived from an unsaturated nitrile monomer (unsaturated nitrile monomer unit), a specific carbon black, and a zinc powder. And contain. The rubber composition of the present embodiment contains 100 parts by mass of chloroprene rubber, 20 to 80 parts by mass of carbon black, and 0.2 to 30 parts by mass of zinc powder. The above-mentioned chloroprene rubber has 3 to 20% by mass of structural units derived from an unsaturated nitrile monomer. The average stacking height LC in the C-axis direction of the layer plane in the crystal lattice of the above carbon black is 2 nm or more. The amount of the structural unit derived from the unsaturated nitrile monomer means the amount of the structural unit derived from the unsaturated nitrile monomer in the total amount of the chloroprene rubber contained in the rubber composition of the present embodiment. When the rubber composition of the present embodiment contains a plurality of chloroprene-based rubbers having different amounts of structural units derived from unsaturated nitrile monomers, the amount of structural units derived from unsaturated nitrile monomers described above is plural. The average value of the amount of the structural unit derived from the unsaturated nitrile monomer in the chloroprene rubber. The same applies to the amounts of the structural units derived from the chloroprene monomer described below.

(Chloroprene rubber)
The chloroprene rubber is obtained by polymerizing a chloroprene monomer (a chloroprene monomer), and has a structural unit derived from the chloroprene monomer (chloroprene monomer unit). The chloroprene rubber in the rubber composition of the present embodiment contains a chloroprene rubber A (chloroprene-unsaturated nitrile copolymer) obtained by copolymerizing a chloroprene monomer and an unsaturated nitrile monomer. The chloroprene rubber A has a structural unit derived from a chloroprene monomer (chloroprene monomer unit) and a structural unit derived from an unsaturated nitrile monomer (unsaturated nitrile monomer unit).

The unsaturated nitrile monomer may, for example, be acrylonitrile, methacrylonitrile, ethacrylonitrile or phenylacrylonitrile. The unsaturated nitrile monomer is preferably acrylonitrile (acrylonitrile monomer) from the viewpoint of easy production and excellent oil resistance. The unsaturated nitrile monomer may be used alone or in combination of two or more.

The amount (copolymerization amount) of the structural unit derived from the unsaturated nitrile monomer in the chloroprene rubber is 3 to 20 mass% based on the total amount of the chloroprene rubber contained in the rubber composition of the present embodiment. If the amount of the structural unit derived from the unsaturated nitrile monomer is less than 3% by mass, the oil resistance of the obtained vulcanized product and vulcanized molded product will not be improved. When the amount of the structural unit derived from the unsaturated nitrile monomer exceeds 20% by mass, the cold resistance of the obtained vulcanized product and vulcanized molded product decreases.

The amount of the structural unit derived from the unsaturated nitrile monomer in the chloroprene rubber is preferably 5% by mass or more, more preferably 7% by mass or more, and further preferably from the viewpoint of easily obtaining excellent oil resistance. Is 8% by mass or more, particularly preferably 9% by mass or more, and most preferably 10% by mass or more. The amount of the structural unit derived from the unsaturated nitrile monomer is preferably less than 20% by mass, more preferably 17% by mass or less, and further preferably 15% by mass, from the viewpoint of easily obtaining excellent cold resistance. Or less, particularly preferably 12% by mass or less, and very preferably 10% by mass or less. From these viewpoints, the amount of the structural unit derived from the unsaturated nitrile monomer is preferably 5 to 17% by mass, more preferably 9 to 17% by mass. The amount of the structural unit derived from the unsaturated nitrile monomer may be preferably more than 10% by mass, more preferably 12% by mass or more, and further preferably 15 from the viewpoint of easily obtaining excellent mechanical strength. It is at least mass%, particularly preferably at least 18 mass%. The amount of the structural unit derived from the unsaturated nitrile monomer is preferably less than 10% by mass, more preferably 8% by mass or less, and further preferably 6% by mass from the viewpoint that further excellent cold resistance can be easily obtained. % Or less, particularly preferably 5% by mass or less.

The amount of the structural unit derived from the unsaturated nitrile monomer contained in the chloroprene rubber can be calculated from the content of nitrogen atom in the polymer. Specifically, the content of nitrogen atoms in 100 mg of chloroprene rubber was measured using an elemental analyzer (Sumigraph 220F: manufactured by Sumika Chemical Analysis Service Co., Ltd.), and the amount of structural units derived from unsaturated nitrile monomer was measured. Can be calculated. The elemental analysis can be performed under the following conditions. For example, the electric furnace temperature is set to 900 ° C., the reduction furnace is 600 ° C., the column temperature is 70 ° C., and the detector temperature is 100 ° C., oxygen is 0.2 ml / min as a combustion gas, and helium is 80 ml / min as a carrier gas. Flow. The calibration curve can be prepared using aspartic acid (10.52%) having a known nitrogen content as a standard substance.

The amount of the structural unit derived from the unsaturated nitrile monomer in the chloroprene rubber A is preferably within the following range based on the total amount of the chloroprene rubber A. The amount of the structural unit derived from the unsaturated nitrile monomer is preferably 3% by mass or more, more preferably 4% by mass or more, and further preferably 5% by mass or more, from the viewpoint of easily obtaining excellent oil resistance. It is particularly preferably at least 7% by mass, very preferably at least 8% by mass, very preferably at least 9% by mass, and even more preferably at least 10% by mass. The amount of the structural unit derived from the unsaturated nitrile monomer is preferably 40% by mass or less, more preferably 35% by mass or less, further preferably 30% by mass or less, particularly preferably from the viewpoint of easily obtaining excellent cold resistance. Is 25% by mass or less, very preferably 20% by mass or less, very preferably less than 20% by mass, still more preferably 17% by mass or less, further preferably 15% by mass or less, particularly preferably 12% by mass or less. % Or less, very preferably less than 11% and very preferably 10% or less. From these viewpoints, the amount of the structural unit derived from the unsaturated nitrile monomer is preferably 3 to 40% by mass, more preferably 4 to 40% by mass. The amount of the structural unit derived from the unsaturated nitrile monomer may be preferably more than 10% by mass, more preferably 12% by mass or more, and further preferably 15 from the viewpoint of easily obtaining excellent mechanical strength. It is at least mass%, particularly preferably at least 18 mass%. The amount of the structural unit derived from the unsaturated nitrile monomer is preferably less than 10% by mass, more preferably 8% by mass or less, and further preferably 6% by mass from the viewpoint that further excellent cold resistance can be easily obtained. % Or less, particularly preferably 5% by mass or less. The chloroprene rubber A may have structural units derived from unsaturated nitrile monomers in the respective amounts described above in the main chain.

The amount of structural units derived from the chloroprene monomer in the chloroprene rubber is preferably within the following range based on the total amount of the chloroprene rubber. The amount of the structural unit derived from the chloroprene monomer is preferably 80% by mass or more, more preferably more than 80% by mass, further preferably 83% by mass or more, from the viewpoint of easily obtaining excellent cold resistance. Is more preferable, 85% by mass or more is very preferable, 88% by mass or more is very preferable, 89% by mass or more is very preferable, and 90% by mass or more is even more preferable. The amount of the structural unit derived from the chloroprene monomer is preferably 97% by mass or less, more preferably 95% by mass or less, and further preferably 93% by mass or less, from the viewpoint that excellent oil resistance is easily obtained. %, Particularly preferably 92% by mass or less, very preferably 91% by mass or less, and very preferably 90% by mass or less. From these viewpoints, the amount of the structural unit derived from the chloroprene monomer is preferably 80 to 97 mass%. The amount of the structural unit derived from the chloroprene monomer is preferably less than 90% by mass, more preferably 88% by mass or less, and further preferably 85% by mass or less, from the viewpoint that more excellent cold resistance can be easily obtained. And particularly preferably 82% by mass or less. The amount of the structural unit derived from the chloroprene monomer is preferably 90% by mass or more, more preferably 92% by mass or more, and further preferably 94% by mass, from the viewpoint of easily obtaining excellent mechanical strength. It is above, and particularly preferably 95% by mass or more. The amount of structural units derived from chloroprene monomer, for example, when the chloroprene rubber is composed of structural units derived from chloroprene monomer and structural units derived from unsaturated nitrile monomer, from the total amount of chloroprene rubber It can be obtained by subtracting the amount of the structural unit derived from the unsaturated nitrile monomer.

The amount of the structural unit derived from the chloroprene monomer in the chloroprene rubber A is preferably in the following range based on the total amount of the chloroprene rubber A. The amount of the structural unit derived from the chloroprene monomer is preferably 60% by mass or more, more preferably 65% by mass or more, and further preferably 70% by mass or more, from the viewpoint of easily obtaining excellent cold resistance. Yes, particularly preferably 75% by mass or more, very preferably 80% by mass or more, very preferably more than 80% by mass, even more preferably 83% by mass or more, further preferably 85% by mass. % Or more, particularly preferably 88% by mass or more, very preferably more than 89% by mass, and very preferably 90% by mass or more. The amount of the structural unit derived from the chloroprene monomer is preferably 97% by mass or less, more preferably 96% by mass or less, and further preferably 95% by mass or less, from the viewpoint that excellent oil resistance is easily obtained. %, Particularly preferably 93% by mass or less, very preferably 92% by mass or less, very preferably 91% by mass or less, and even more preferably 90% by mass or less. From these viewpoints, the amount of the structural unit derived from the chloroprene monomer is preferably 60 to 97% by mass, more preferably 60 to 96% by mass. The amount of the structural unit derived from the chloroprene monomer is preferably 90% by mass or more, more preferably 92% by mass or more, and further preferably 94% by mass, from the viewpoint that further excellent cold resistance can be easily obtained. More preferably, it is 95 mass% or more. The amount of the structural unit derived from the chloroprene monomer is preferably less than 90% by mass, more preferably 88% by mass or less, and further preferably 85% by mass or less, from the viewpoint of easily obtaining excellent mechanical strength. And particularly preferably 82% by mass or less. The chloroprene rubber A may have structural units derived from the above-mentioned amounts of the chloroprene monomer in the main chain.

The monomer copolymerizable with the chloroprene monomer is not limited to the unsaturated nitrile monomer. Examples of monomers copolymerizable with the chloroprene monomer include 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, styrene, isoprene, butadiene, acrylic acid, and acrylic acid esters. And methacrylic acid, esters of methacrylic acid, and the like. The amount of structural units derived from 1-chloro-1,3-butadiene contained in the chloroprene rubber may be less than 1% by mass based on the total amount of the chloroprene rubber.

The chloroprene rubber in the rubber composition of the present embodiment may include chloroprene rubber B having no structural unit derived from an unsaturated nitrile monomer. By using the chloroprene rubber B in combination with the chloroprene rubber A, the structural unit amount derived from the unsaturated nitrile monomer in the chloroprene rubber in the rubber composition of the present embodiment can be easily adjusted by dilution. The chloroprene-based rubber may be a mixture containing chloroprene-based rubber A and chloroprene-based rubber B (for example, a mixture of chloroprene-based rubber A and chloroprene-based rubber B).

The amount of the structural unit derived from the chloroprene monomer in the chloroprene rubber B is determined from the viewpoint that a vulcanized product and a vulcanized molded article having excellent mechanical strength, heat resistance, oil resistance and cold resistance can be easily obtained. Based on the total amount of B, preferably 80% by mass or more, more preferably 90% by mass or more, further preferably 95% by mass or more, particularly preferably 98% by mass or more, and very preferably 99% by mass or more. It is at least mass%. The structural units constituting the chloroprene rubber B are substantially composed of structural units derived from the chloroprene monomer (substantially 100% by mass of the structural units constituting the chloroprene rubber B are structural units derived from the chloroprene monomer). A) embodiment. The chloroprene rubber B may have structural units derived from the above-mentioned amounts of the chloroprene monomer in the main chain.

The chloroprene-based rubber in the rubber composition of the present embodiment is, as one aspect X, a chloroprene-based rubber A having 4 to 40% by mass of a structural unit derived from an unsaturated nitrile monomer, and an unsaturated nitrile monomer-derived rubber. It is preferable to include chloroprene rubber B having no structural unit. By adjusting the amount of the structural unit derived from the unsaturated nitrile monomer in the chloroprene rubber A within this range, the chloroprene rubber A can be easily obtained with good production efficiency, and the chloroprene rubber in the rubber composition of the present embodiment can be easily obtained. Since the amount of the structural unit derived from the unsaturated nitrile monomer therein can be easily adjusted, a vulcanized product and a vulcanized molded product having excellent mechanical strength, heat resistance, oil resistance and cold resistance can be easily obtained. In the embodiment X, the chloroprene rubber A may have 4 to 40% by mass of the structural unit derived from the unsaturated nitrile monomer and 60 to 96% by mass of the structural unit derived from the chloroprene monomer. As the amount of the structural unit derived from the unsaturated nitrile monomer and the amount of the structural unit derived from the chloroprene monomer in the chloroprene rubber A, each of the preferable ranges described above for the chloroprene rubber A can be used. In Aspect X, the chloroprene rubber A may have a structural unit derived from a monomer copolymerizable with the chloroprene monomer as a structural unit other than the structural unit derived from the unsaturated nitrile monomer. As the monomer copolymerizable with the chloroprene monomer, the above-mentioned monomers can be used.

In the above aspect X, the chloroprene rubber B may have a structural unit derived from a chloroprene monomer of 80 to 100% by mass, and the structural unit derived from the chloroprene monomer is 80% by mass or more and less than 100% by mass, It may have a structural unit derived from a monomer copolymerizable with the chloroprene monomer in an amount of more than 0% by mass and 20% by mass or less. As the monomer copolymerizable with the chloroprene monomer, the above-mentioned monomers can be used. As the amount of the structural unit derived from the chloroprene monomer in the chloroprene rubber B in the embodiment X, each of the preferable ranges described above for the chloroprene rubber B can be used.

The polymer structure of the chloroprene copolymer having a structural unit derived from a chloroprene monomer and a structural unit derived from a monomer copolymerizable with the chloroprene monomer is not particularly limited, and a block copolymer Alternatively, it may be a statistical copolymer.

A statistical copolymer of a chloroprene monomer and an unsaturated nitrile monomer (eg, acrylonitrile) can be produced, for example, by continuously adding the chloroprene monomer or intermittently adding 10 times or more after the initiation of the polymerization reaction. At that time, the time at the start of the polymerization reaction is set to t (0), and n is an integer of 1 or more. Determining the amount of chloroprene monomer added at time dt (n + 1) between time t (n) and time t (n + 1) based on the total amount of polymerization conversion of the monomer and unsaturated nitrile monomer, The ratio of unreacted chloroprene monomer to unsaturated nitrile monomer can be kept constant.

Statistical copolymers are described in J. C. Randall, as described in POLYMER SEQUENCE DETERMINATION, Carbon-13 NMR Methods, Academic Press, New York, 1977, pp. 71-78, by Bernoulli's statistical model, or by the primary or secondary model of Markov. It means that it is a copolymer. For example, when the statistical copolymer of a chloroprene monomer and acrylonitrile is composed of a binary monomer, the following Mayo-Lewis formula (I) shows that the chloroprene monomer and acrylonitrile at the start of polymerization are When the ratio is d [M1] / d [M2] and the chloroprene monomer is M1 defined in the following Mayo-Lewis formula (I), the reactivity ratios r1 and r2 are r0. The range of 3 to 3000 and the range of r2 of 10 ⁻⁵ to 3.0 are preferable for obtaining the statistical copolymer.

The number average molecular weight (Mn), weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of the chloroprene rubber (for example, chloroprene rubber A) contained in the rubber composition of the present embodiment are mechanical strength and heat resistance. From the viewpoint of easily obtaining a vulcanized product and a vulcanized molded article having excellent oil resistance and cold resistance, the following range is preferable. The number average molecular weight, the weight average molecular weight and the molecular weight distribution can be measured by the methods described in Examples below.

The number average molecular weight is preferably 100 × 10 ³ or more, more preferably 110 × 10 ³ or more, further preferably 120 × 10 ³ or more, and particularly preferably 130 × 10 ³ or more. The number average molecular weight is preferably 300 × 10 ³ or less, more preferably 200 × 10 ³ or less, further preferably 150 × 10 ³ or less, and particularly preferably 140 × 10 ³ or less. From these viewpoints, the number average molecular weight is preferably 100 × 10 ³ to 300 × 10 ³ .

The weight average molecular weight is preferably 200 × 10 ³ or more, more preferably 300 × 10 ³ or more, further preferably 350 × 10 ³ or more, particularly preferably 400 × 10 ³ or more, and very preferably Is 450 × 10 ³ or more. The weight average molecular weight is preferably 1000 × 10 ³ or less, more preferably 800 × 10 ³ or less, further preferably 600 × 10 ³ or less, particularly preferably 500 × 10 ³ or less, and very preferably Is 480 × 10 ³ or less. From these viewpoints, the weight average molecular weight is preferably 200 × 10 ³ to 1000 × 10 ³ .

The molecular weight distribution is preferably 2 or more, more preferably 2.5 or more, even more preferably 3 or more, particularly preferably 3.1 or more, and most preferably 3.2 or more. The molecular weight distribution is preferably 4 or less, more preferably 3.8 or less, further preferably 3.5 or less, and particularly preferably 3.4 or less. From these viewpoints, the molecular weight distribution is preferably 2-4.

Chloroprene rubber can be obtained by, for example, emulsion polymerization. The polymerization initiator used in emulsion polymerization is not particularly limited, and known polymerization initiators generally used in emulsion polymerization of chloroprene monomer can be used. Examples of the polymerization initiator include organic peroxides such as potassium persulfate, ammonium persulfate, sodium persulfate, hydrogen peroxide, and t-butyl hydroperoxide.

The emulsifier used in emulsion polymerization is not particularly limited, and a known emulsifier generally used in emulsion polymerization of chloroprene monomer can be used. As the emulsifier, an alkali metal salt of a saturated or unsaturated fatty acid having 6 to 22 carbon atoms, an alkali metal salt of rosin acid or disproportionated rosin acid (eg potassium rosinate), a formalin condensate of β-naphthalenesulfonic acid Alkali metal salts (for example, sodium salts) of

The molecular weight modifier used in emulsion polymerization is not particularly limited, and known molecular weight modifiers generally used in emulsion polymerization of chloroprene monomer can be used. Examples of the molecular weight modifier include long-chain alkyl mercaptans such as n-dodecyl mercaptan, t-dodecyl mercaptan and n-octyl mercaptan; xanthogen compounds such as diisopropylxanthogen disulfide and diethylxanthogen disulfide; iodoform; benzyl 1-pyrrole dithiocarbamate (alias) Benzyl 1-pyrrole carbodithioate), benzyl phenyl carbodithioate, 1-benzyl-N, N-dimethyl-4-aminodithiobenzoate, 1-benzyl-4-methoxydithiobenzoate, 1-phenylethylimidazole dithiocarbamate (alias) 1-phenylethylimidazole carbodithioate), benzyl-1- (2-pyrrolidinone) dithiocarbamate (also known as benzyl-1- (2-pyrrolidinone) Carbodithioate), benzylphthalimidyldithiocarbamate (also known as benzylphthalimidylcarbodithioate), 2-cyanoprop-2-yl-1-pyrroledithiocarbamate (also known as 2-cyanoprop-2-yl-1-pyrrolecarbodithio) Ate), 2-cyanobut-2-yl-1-pyrroledithiocarbamate (also known as 2-cyanobut-2-yl-1-pyrrolecarbodithioate), benzyl-1-imidazoledithiocarbamate (also known as benzyl-1-imidazolecarbodithio) A)), 2-cyanoprop-2-yl-N, N-dimethyldithiocarbamate, benzyl-N, N-diethyldithiocarbamate, cyanomethyl-1- (2-pyrrolidone) dithiocarbamate, 2- (ethoxycarbonylbenzyl) prop 2-yl-N, N-diethyldithiocarbamate, 1-phenylethyldithiobenzoate, 2-phenylprop-2-yldithiobenzoate, 1-acetic acid-1-yl-ethyldithiobenzoate, 1- (4-methoxyphenyl) Ethyldithiobenzoate, benzyldithioacetate, ethoxycarbonylmethyldithioacetate, 2- (ethoxycarbonyl) prop-2-yldithiobenzoate, 2-cyanoprop-2-yldithiobenzoate, t-butyldithiobenzoate, 2,4,4 -Trimethylpent-2-yldithiobenzoate, 2- (4-chlorophenyl) -prop-2-yldithiobenzoate, 3-vinylbenzyldithiobenzoate, 4-vinylbenzyldithiobenzoate, benzyldiethoxyphosphinyl Dithioformate, t-butyltrithioperbenzoate, 2-phenylprop-2-yl-4-chlorodithiobenzoate, naphthalene-1-carboxylic acid-1-methyl-1-phenyl-ethyl ester, 4-cyano-4- Methyl-4-thiobenzylsulfanyl butyric acid, dibenzyl tetrathioterephthalate, carboxymethyl dithiobenzoate, poly (ethylene oxide) with dithiobenzoate end groups, 4-cyano-4-methyl-4-thiobenzylsulfanyl butyric acid end group Having poly (ethylene oxide), 2-[(2-phenylethanethioyl) sulfanyl] propanoic acid, 2-[(2-phenylethanethioyl) sulfanyl] succinic acid, 3,5-dimethyl-1H-pyrazole-1 -Potassium carbodithioate, cyanomethyl-3, -Dimethyl-1H pyrazole-1-carbodithioate, cyanomethylmethyl- (phenyl) dithiocarbamate, benzyl-4-chlorodithiobenzoate, phenylmethyl-4-chlorodithiobenzoate, 4-nitrobenzyl-4-chlorodithiobenzoate, Phenylprop-2-yl-4-chlorodithiobenzoate, 1-cyano-1-methylethyl-4-chlorodithiobenzoate, 3-chloro-2-butenyl-4-chlorodithiobenzoate, 2-chloro-2-butenyl Dithiobenzoate, benzyl dithioacetate, 3-chloro-2-butenyl-1H-pyrrole-1-dithiocarboxylic acid, 2-cyanobutan-2-yl-4-chloro-3,5-dimethyl-1H-pyrazole-1-carbo Dithioate, cyanomethylmethyl Phenyl) carbamodithioate, 2-cyano-2-propyldodecyltrithiocarbonate, dibenzyltrithiocarbonate, butylbenzyltrithiocarbonate, 2-[[(butylthio) thioxomethyl] thio] propionic acid, 2- [[(Dodecylthio) thioxomethyl] thio] propionic acid, 2-[[(butylthio) thioxomethyl] thio] succinic acid, 2-[[(dodecylthio) thioxomethyl] thio] succinic acid, 2-[[(dodecylthio) thioxomethyl] thio ] -2-Methylpropionic acid, 2,2 ′-[carbonothioylbis (thio)] bis [2-methylpropionic acid], 2-amino-1-methyl-2-oxoethylbutyltrithiocarbonate, benzyl -2-[(2-hydroxyethyl) amino] -1-methyl-2-oxy Thioethyltrithiocarbonate, 3-[[[(t-butyl) thio] thioxomethyl] thio] propionic acid, cyanomethyldodecyltrithiocarbonate, diethylaminobenzyltrithiocarbonate, dibutylaminobenzyltrithiocarbonate, etc. Examples thereof include carbonyl compounds.

The polymerization temperature and the final conversion rate of the monomer are not particularly limited, but the polymerization temperature is preferably 0 to 50 ° C, more preferably 20 to 50 ° C. It is preferable to carry out the polymerization so that the final conversion rate of the monomer falls within the range of 40 to 95% by mass. In order to adjust the final conversion rate, the polymerization may be stopped by adding a polymerization inhibitor that stops the polymerization reaction when the desired conversion rate is reached.

The polymerization inhibitor is not particularly limited, and known polymerization inhibitors generally used in emulsion polymerization of chloroprene monomer can be used. Examples of the polymerization inhibitor include phenothiazine (thiodiphenylamine), 4-tert-butylcatechol, and 2,2-methylenebis-4-methyl-6-tert-butylphenol.

The chloroprene rubber can be obtained, for example, by removing unreacted monomers by a steam stripping method, adjusting the pH of the latex, and then subjecting it to conventional freeze-coagulation, water washing, hot-air drying and other steps. ..

Chloroprene rubber is classified into mercaptan modified chloroprene rubber, xanthogen modified chloroprene rubber, sulfur modified chloroprene rubber, dithiocarbonate chloroprene rubber, trithiocarbonate chloroprene rubber and carbamate chloroprene rubber depending on the type of molecular weight modifier.

The above chloroprene rubber can be obtained by the above chloroprene rubber polymerization method, and the above chloroprene rubber A can be obtained by polymerizing without adding an unsaturated nitrile monomer. In order to mix the chloroprene rubber A and the chloroprene rubber B, a kneading device such as a conventionally known mixer, Banbury mixer, kneader mixer, or two roll can be used.

(Carbon black)
The rubber composition of this embodiment contains carbon black. The rubber composition of the present embodiment contains carbon black (hereinafter, referred to as “specific carbon black”) having an average stacking height LC in the C-axis direction of the layer plane in the crystal lattice (crystallite) of 2 nm or more. If the average stacking height LC is less than 2 nm, the heat resistance of the vulcanized product and vulcanized molded product obtained by vulcanizing the rubber composition is not sufficient. The average stacking height LC is preferably 2.5 nm or more from the viewpoint of easily obtaining a vulcanized product and a vulcanized molded article having excellent heat resistance. The average stacking height LC can be obtained by X-ray diffraction. Specifically, X-ray diffraction is performed using CuKα rays under the conditions of measurement range 2θ = 10 to 40 ° and slit width 0.5 °. Using the obtained diffraction line of the (002) plane, the crystallite size Lc can be obtained by the Scherrer's formula: Lc (nm) = ((K × λ) / (β × cos θ)) / 10. Here, K is a form factor constant of 0.9, λ is an X-ray wavelength of 0.154 nm, θ is an angle indicating a maximum value in the (002) diffraction line absorption band, and β is a half value in the (002) diffraction line absorption band. The width (radian).

The average particle size of the specific carbon black is preferably 60 nm or less from the viewpoint of easily obtaining a vulcanized product and a vulcanized molded product having excellent mechanical strength, heat resistance, oil resistance and cold resistance. The average particle size of the specific carbon black is a value measured using an electron microscope in accordance with JIS Z8901.

The DBP (dibutyl phthalate) oil absorption of the specific carbon black is 100 to 350 ml / 100 g from the viewpoint of easily obtaining a vulcanized product and a vulcanized molded product having excellent mechanical strength, heat resistance, oil resistance and cold resistance. 120 to 300 ml / 100 g is more preferable, and 140 to 300 ml / 100 g is further preferable. The specific carbon black has an average particle size of 60 nm or less, and a DBP oil absorption of these, from the viewpoint of easily obtaining a vulcanized product and a vulcanized molded product having excellent mechanical strength, heat resistance, oil resistance and cold resistance. The range is preferably. The DBP oil absorption of the specific carbon black is a value measured by the oil absorption A method of JIS K 6217-4.

The rubber composition of the present embodiment may contain carbon black other than carbon black having an average stacking height LC of 2 nm or more in the C-axis direction of the layer plane in the crystal lattice, if necessary. As such carbon black, various carbon blacks conventionally used for rubber can be used.

As the carbon black blended in the rubber composition of the present embodiment, thermal black by thermal decomposition method, acetylene black, etc., furnace black by incomplete combustion method, channel black, etc. can all be used. Among the carbon blacks, acetylene black is a carbon black obtained by thermally decomposing acetylene gas, has a remarkable degree of crystallization, has a highly developed structure, and has a large oil absorption. The specific carbon black is preferably acetylene black from the viewpoint of having a great effect of improving the heat resistance of the vulcanized product of the rubber composition and the vulcanized molded product.

The content of the specific carbon black is 20 to 80 parts by mass with respect to 100 parts by mass of the chloroprene rubber. If the content of the specific carbon black exceeds 80 parts by mass, scorch is likely to occur due to a decrease in processability, and a vulcanized molded product cannot be obtained. Further, the cold resistance of the vulcanized product and the vulcanized molded product is reduced. If the content of the specific carbon black is less than 20 parts by mass, the heat resistance of the vulcanized product and the vulcanized molded product will decrease.

The content of the specific carbon black is preferably in the following range with respect to 100 parts by mass of the chloroprene rubber. From the viewpoint of easily obtaining excellent mechanical strength and heat resistance, the content of the specific carbon black is preferably 25 parts by mass or more, more preferably 30 parts by mass or more, and further preferably 35 parts by mass or more. It is particularly preferably 40 parts by mass or more. The content of the specific carbon black is preferably less likely to cause scorch because the deterioration of the processability is easily suppressed, a vulcanized molded body is easily obtained, and, from the viewpoint of easily obtaining excellent heat resistance and cold resistance, preferably It is 70 parts by mass or less, more preferably 60 parts by mass or less, further preferably 50 parts by mass or less, and particularly preferably 40 parts by mass or less. From these viewpoints, the content of the specific carbon black is preferably 25 to 70 parts by mass.

The content of the specific carbon black is the content of the carbon black (included in the rubber composition from the viewpoint of easily obtaining a vulcanized product and a vulcanized molded article having excellent mechanical strength, heat resistance, oil resistance and cold resistance. Based on the total amount of carbon black), it is preferably 80% by mass or more, more preferably 90% by mass or more, further preferably 95% by mass or more, particularly preferably 98% by mass or more, and very preferably Is 99% by mass or more. It may be an aspect in which the carbon black is substantially composed of the specific carbon black (substantially 100% by mass of the carbon black is the specific carbon black).

The content of carbon black (the total amount of carbon black contained in the rubber composition) is preferably in the following range with respect to 100 parts by mass of the chloroprene rubber. The content of carbon black is preferably 20 parts by mass or more, more preferably 25 parts by mass or more, further preferably 30 parts by mass or more, from the viewpoint of easily obtaining excellent mechanical strength and heat resistance. It is particularly preferably 35 parts by mass or more, and most preferably 40 parts by mass or more. The content of carbon black is preferably 80, from the viewpoint that scorch is unlikely to occur because a decrease in processability is easily suppressed, a vulcanized molded body is easily obtained, and that excellent heat resistance and cold resistance are easily obtained. The amount is not more than 70 parts by mass, more preferably not more than 70 parts by mass, further preferably not more than 60 parts by mass, particularly preferably not more than 50 parts by mass, and most preferably not more than 40 parts by mass. From these viewpoints, the content of carbon black is preferably 20 to 80 parts by mass, more preferably 25 to 70 parts by mass.

(Zinc powder)
The rubber composition of the present embodiment contains zinc powder. The particle size of the zinc powder is preferably 200 mesh.

The content of zinc powder is 0.2 to 30 parts by mass with respect to 100 parts by mass of chloroprene rubber. If the content of the zinc powder is less than 0.2 parts by mass, the heat resistance of the vulcanized product and the vulcanized molded product will not be sufficiently improved. When the content of the zinc powder exceeds 30 parts by mass, the mechanical properties of the vulcanized product and the vulcanized molded product deteriorate.

The zinc powder content is preferably in the following range with respect to 100 parts by mass of chloroprene rubber. The content of the zinc powder is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, further preferably 2 parts by mass or more, particularly from the viewpoint of easily obtaining excellent heat resistance. It is preferably 3 parts by mass or more, very preferably 4 parts by mass or more, and very preferably 5 parts by mass or more. The content of the zinc powder is preferably 25 parts by mass or less, more preferably 20 parts by mass or less, further preferably 15 parts by mass or less, and particularly preferably, from the viewpoint of easily obtaining excellent mechanical properties. Is 10 parts by mass or less, and most preferably 5 parts by mass or less. From these viewpoints, the content of zinc powder is preferably 0.5 to 25 parts by mass, more preferably 2 to 20 parts by mass.

(Other ingredients)
The rubber composition of the present embodiment may contain various additives (chemicals) usually used in the rubber industry as components other than the chloroprene rubber, carbon black and zinc powder. Examples of additives include vulcanizing agents, fillers, reinforcing agents, plasticizers, processing aids, lubricants, antioxidants, silane coupling agents, vulcanization accelerators, scorch inhibitors, and softeners.

As the vulcanizing agent, components generally used for vulcanizing chloroprene rubber can be used. As the vulcanizing agent, sulfur; an organic vulcanizing agent such as thiourea-based, guanidine-based, thiuram-based, thiazole-based; a mixture of 3-methylthiazolidinethione-2-thiazole and phenylene dimaleimide; 1,2-dimercapto-1,3,4-thiadiazole derivative; beryllium, magnesium, zinc, calcium, barium, germanium, titanium, tin, zirconium, antimony, vanadium, bismuth, molybdenum, tungsten, tellurium, selenium, iron, nickel Examples include simple substances of metals such as cobalt, cobalt and osmium, oxides and hydroxides. The vulcanizing agents may be used alone or in combination of two or more. As the vulcanizing agent, a thiourea-based organic vulcanizing agent is preferable. Examples of the thiourea-based organic vulcanizing agent include ethylenethiourea, diethylthiourea, trimethylthiourea, triethylthiourea and N, N'-diphenylthiourea, and at least one selected from the group consisting of trimethylthiourea and ethylenethiourea is preferable. As the vulcanizing agent, at least one selected from the group consisting of calcium oxide, zinc oxide, antimony dioxide, antimony trioxide and magnesium oxide is also preferable from the viewpoint of high vulcanization effect. The content of the vulcanizing agent may be 0.1 to 15 parts by mass with respect to 100 parts by mass of the chloroprene rubber.

The filler or reinforcing agent can be used for adjusting the hardness of the rubber composition or improving the mechanical strength. A compound corresponding to a vulcanizing agent can also be used as the filler or the reinforcing agent. As the filler or the reinforcing agent, silica; alumina such as γ-alumina and α-alumina (Al ₂ O ₃ ); alumina monohydrate such as boehmite and diaspore (Al ₂ O ₃ .H ₂ O); gibbsite, Aluminum hydroxide [Al (OH) ₃ ] such as bayerite; aluminum carbonate [Al ₂ (CO ₃ ) ₂ ]; magnesium hydroxide [Mg (OH) ₂ ]; magnesium carbonate (MgCO ₃ ); talc (3MgO.4SiO) ₂ · H ₂ O); attapulgite (5MgO · 8SiO ₂ · 9H ₂ O); titanium white (TiO ₂ ); titanium black (TiO _2n-1 ); calcium oxide (CaO); calcium hydroxide [Ca (OH) ₂ ]; magnesium aluminum oxide _{_{(MgO · Al 2 O 3)}} ; clay _{_{_{(Al 2 O 3 · 2SiO 2}}} ); kaolin (Al ₂ _{_{_{3 · 2SiO 2 · 2H 2 O}}} ); pyrophyllite _{_{_{(Al 2 O 3 · 4SiO 2}}} · H 2 O); bentonite _{_{_{(Al 2 O 3 · 4SiO 2}}} · 2H 2 O); aluminum silicate _(Al 2 SiO ₅ , Al ₄ .3SiO ₄ .5H ₂ O etc.); magnesium silicate (Mg ₂ SiO ₄ , MgSiO ₃ etc.); calcium silicate (Ca ₂ SiO ₄ etc.); aluminum calcium silicate (Al ₂ O ₃ .CaO. 2SiO ₂ ); magnesium calcium silicate (CaMgSiO ₄ ); calcium carbonate (CaCO ₃ ); zirconium oxide (ZrO ₂ ); zirconium hydroxide [ZrO (OH) ₂ · nH ₂ O]; zirconium carbonate [Zr (CO _3). ) _2]; as various zeolites, hydrogen atom for correcting the charge, and the alkali metal or alka Such as crystalline aluminosilicates including earth metals. The filler or the reinforcing agent may be used alone or in combination of two or more. The content of the filler or the reinforcing agent may be adjusted according to the physical properties required in the rubber composition, the vulcanized product and the vulcanized molded product, and is not particularly limited. The content of the filler or the reinforcing agent may be 15 to 200 parts by mass based on 100 parts by mass of the chloroprene rubber.

The plasticizer is not particularly limited as long as it is compatible with rubber. Examples of the plasticizer include vegetable oils such as rapeseed oil, linseed oil, castor oil, and coconut oil; phthalate plasticizers, DUP (diundecyl phthalate), DOS (dioctyl sebacate), DOA (dioctyl adipate), ester plasticizers, Examples include ether ester plasticizers, thioether plasticizers, aromatic oils, naphthene oils, lubricating oils, process oils, petroleum plasticizers such as paraffin, liquid paraffin, petrolatum and petroleum asphalt. The plasticizers may be used alone or in combination of two or more, depending on the properties required in the rubber composition, vulcanized product and vulcanized molded product. The content of the plasticizer is not particularly limited and may be 3 to 50 parts by mass with respect to 100 parts by mass of the chloroprene rubber.

A processing aid or a lubricant is used for kneading or vulcanizing and molding a rubber composition so that it can be easily peeled off from a roll, a molding die, a screw of an extruder, or the like. Can be used to improve Examples of processing aids or lubricants include fatty acids such as stearic acid; paraffin-based processing aids such as polyethylene; and fatty acid amides. The processing aids or lubricants may be used alone or in combination of two or more. The content of the processing aid or the lubricant is not particularly limited and may be 0.5 to 5 parts by mass with respect to 100 parts by mass of the chloroprene rubber.

Aging resistance can further improve heat resistance. As the anti-aging agent, use a primary anti-aging agent that is used for ordinary rubber applications and that traps radicals to prevent autooxidation, and / or a secondary anti-aging agent that detoxifies hydroperoxide. You can The content of the primary antioxidant, the content of the secondary antioxidant, and / or the content (total amount) of the antioxidant contained in the rubber composition is preferably 100 parts by mass of the chloroprene rubber. Is 0.1 to 10 parts by mass, more preferably 1 to 5 parts by mass. The antioxidants can be used alone or in combination of two or more.

Examples of primary anti-aging agents include phenolic anti-aging agents, amine anti-aging agents, acrylate anti-aging agents, imidazole anti-aging agents, carbamic acid metal salts and waxes. Examples of the secondary antiaging agent include phosphorus antiaging agents, sulfur antiaging agents, imidazole antiaging agents, and the like. The antiaging agent is not particularly limited, but N-phenyl-1-naphthylamine, alkylated diphenylamine, octylated diphenylamine, 4,4′-bis (α, α-dimethylbenzyl) diphenylamine, p- (p-toluenesulfonyl) Amido) diphenylamine, N, N'-di-2-naphthyl-p-phenylenediamine, N, N'-diphenyl-p-phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine, N-phenyl- N '-(1,3-dimethylbutyl) -p-phenylenediamine, N-phenyl-N'-(3-methacryloyloxy-2-hydroxypropyl) -p-phenylenediamine, 1,1,3-tris- ( 2-Methyl-4-hydroxy-5-tert-butylphenyl) butane, 4,4′- Butylidene bis- (3-methyl-6-tert-butylphenol), 2,2-thiobis (4-methyl-6-tert-butylphenol), 7-octadecyl-3- (4'-hydroxy-3 ', 5'-di -Tert-butylphenyl) propionate, tetrakis- [methylene-3- (3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate] methane, pentaerythritol-tetrakis [3- (3,5- Di-tert-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [bis 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propio , 2,4-bis (n-octylthio) -6- (4-hydroxy-3,5-di-tert-butylanilino) -1,3,5-triazine, tris- (3,5-di- tert-Butyl-4-hydroxybenzyl) -isocyanurate, 2,2-thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], N, N′-hexamethylene Bis (3,5-di-tert-butyl-4-hydroxy) -hydrocinnamide, 2,4-bis [(octylthio) methyl] -o-cresol, 3,5-di-tert-butyl-4-hydroxy Benzyl-phosphonate-diethyl ester, tetrakis [methylene (3,5-di-tert-butyl-4-hydroxyhydrocinnamate)] methane, octade 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid ester, 3,9-bis [2- {3- (3-tert-butyl-4-hydroxy-5-methylphenyl) ) Propionyloxy} -1,1-dimethylethyl] -2,4,8,10-tetraoxaspiro [5.5] undecane, tris (nonylphenyl) phosphite, tris (mixed mono- and di-nonylphenyl) ) Phosphite, diphenyl mono (2-ethylhexyl) phosphite, diphenyl monotridecyl phosphite, diphenyl isodecyl phosphite, diphenyl isooctyl phosphite, diphenyl nonylphenyl phosphite, triphenyl phosphite, tris (Tridecyl) Phosphate, To Liisodecyl phosphite, tris (2-ethylhexyl) phosphite, tris (2,4-di-tert-butylphenyl) phosphite, tetraphenyl dipropylene glycol diphosphite, tetraphenyl tetra (tridecyl) pentaerythritol tetra Phosphite, 1,1,3-tris (2-methyl-4-di-tridecylphosphite-5-tert-butylphenyl) butane, 4,4'-butylidenebis- (3-methyl-6-tert-butyl) -Di-tridecyl phosphite), 2,2'-ethylidene bis (4,6-di-tert-butylphenol) fluorophosphite, 4,4'-isopropylidene-diphenol alkyl (C12-C15) phosphite, Cyclic neopentane tetrayl bis 2,4-di-tert-butylphenylphosphite), cyclic neopentanetetraylbis (2,6-di-tert-butyl-4-phenylphosphite), cyclic neopentanetetraylbis (nonylphenylphosphite) , Bis (nonylphenyl) pentaerythritol diphosphite, dibutyl hydrogen phosphite, distearyl pentaerythritol diphosphite, hydrogenated bisphenol A pentaerythritol phosphite polymer and the like.

The silane coupling agent can enhance the adhesiveness between the rubber component such as chloroprene rubber and the filler or the reinforcing agent, and further improve the mechanical strength. The silane coupling agent may be added at the time of kneading the rubber composition or may be added in the form of a surface treatment with a filler or a reinforcing agent in advance. The silane coupling agent may be used alone or in combination of two or more. The silane coupling agent is not particularly limited, but is bis- (3-triethoxysilylpropyl) tetrasulfide, bis- (3-trimethoxynylpropyl) tetrasulfide, bis- (3-methyldimethoxysilylpropyl) tetrasulfide. , Bis- (2-triethoxysilylethyl) tetrasulfide, bis- (3-triethoxysilylpropyl) disulfide, bis- (3-trimethoxysilylpropyl) disulfide, bis- (3-triethoxysilylpropyl) trisulfide , 3-hexanoylthiopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, 3-decanoylthiopropyltriethoxysilane, 3-lauroylthiopropyltriethoxysilane, 2-hexanoylthioethyltri Toxysilane, 2-octanoylthioethyltriethoxysilane, 2-decanoylthioethyltriethoxysilane, 2-lauroylthioethyltriethoxysilane, 3-hexanoylthiopropyltrimethoxysilane, 3-octanoylthiopropyltrimethoxysilane , 3-decanoylthiopropyltrimethoxysilane, 3-lauroylthiopropyltrimethoxysilane, 2-hexanoylthioethyltrimethoxysilane, 2-octanoylthioethyltrimethoxysilane, 2-decanoylthioethyltrimethoxysilane, 2-lauroylthioethyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-aminopropyl Remethoxysilane, 3-aminopropyltriethoxysilane, γ-grindoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyltetrasulfide, 3-trimethoxysilylpropyl benzothiazolyl tetrasulfide, 3-trimethoxysilylpropyl methacryloyl monosulfide, methyltrimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, dimethyldimethoxysilane, trimethylethoxysilane, trimethylmethoxysilane, Isobutyltrimethoxysilane, n-decyltrimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, diphenyldimethoxysilane, diphenyldi Toxysilane, hexyltrimethoxysilane, octadecylmethyldimethoxysilane, octadecyltrimethoxysilane, methyltrichlorosilane, dimethyldichlorosilane, triphenylphenylsilane, heptadecafluorodecylmethyldichlorosilane, heptadecafluorodecyltrichlorosilane, triethylchlorosilane and the like. Be done.

The rubber composition of this embodiment may include a compound represented by the following general formula (1). Examples of the compound represented by the general formula (1) include polyethylene glycol dibenzoate, polyethylene glycol di-2-ethylhexoate, tetraethylene glycol di- (2-ethyl hexoate), polyethylene glycol bis ( 2-ethylhexoate), triethylene glycol dipelargonate, triethylene glycol diheptanoate, triethylene glycol caprate caprylate, tetraethylene glycol diheptanoate and the like.

(In the formula, R ¹ and R ² each independently represent an alkyl group having 1 to 20 carbon atoms or a phenyl group, and n represents an integer of 1 to 20.)

The content of the compound represented by the general formula (1) may be in the following range with respect to 100 parts by mass of the chloroprene rubber. The content of the compound represented by the general formula (1) may be less than 0.1 parts by mass, 0.05 parts by mass or less, or 0.01 parts by mass or less. The content of the compound represented by the general formula (1) may be 0 parts by mass or more, and may exceed 0 parts by mass. The rubber composition of the present embodiment may not contain the compound represented by the general formula (1), and the content may be 0 parts by mass.

The rubber composition of the present embodiment can be manufactured by the same method as a normal rubber composition. Specifically, it can be obtained by kneading chloroprene rubber, carbon black, zinc powder and other components with a kneader, a Banbury, a roll or the like at a temperature not higher than the vulcanization temperature.

As described in detail above, the rubber composition of the present embodiment uses a chloroprene rubber having a specific amount of a structural unit derived from an unsaturated nitrile monomer as a rubber component, and a specific amount of carbon black and zinc powder. Therefore, heat resistance and oil resistance can be improved without lowering mechanical strength and cold resistance. This makes it possible to realize a rubber composition capable of obtaining a vulcanized product and a vulcanized molded product having excellent mechanical strength, heat resistance, oil resistance, and cold resistance.

<Vulcanized product>
The vulcanized product of the present embodiment is a vulcanized product of the rubber composition of the present embodiment described above, and can be obtained by vulcanizing the rubber composition of the present embodiment described above. The method for vulcanizing the rubber composition is not particularly limited, and examples thereof include press vulcanization, injection vulcanization, direct kettle vulcanization, indirect kettle vulcanization, direct steam continuous vulcanization, normal pressure continuous vulcanization, continuous vulcanization. It may be vulcanized by a vulcanizing method such as a vulcanizing press.

Vulcanization conditions such as vulcanization temperature and vulcanization time are not particularly limited and can be set as appropriate. The vulcanization temperature is preferably 130 to 200 ° C., more preferably 140 to 190 ° C., from the viewpoint of easily obtaining excellent productivity and processing stability.

Since the vulcanized product of this embodiment uses the rubber composition of this embodiment, it has excellent mechanical strength, heat resistance, oil resistance, and cold resistance.

<Molded body>
The molded body according to this embodiment is a molded body of the rubber composition according to this embodiment, and can be obtained by molding the rubber composition according to this embodiment into a shape according to the purpose. The vulcanized molded product of the present embodiment is a vulcanized molded product of the rubber composition of the present embodiment. The vulcanized molded article of this embodiment can be obtained by molding the rubber composition of this embodiment into a shape according to the purpose and vulcanizing it during or after molding. It can also be obtained by forming a vulcanized product into a shape suitable for the purpose.

The molding method is not particularly limited, but press molding, injection molding, extrusion molding or the like can be applied. For example, when the molded body is a transmission belt, a conveyor belt, an air spring, a sealing material (packing, gasket, etc.), a vibration damping material, a hose, a roll, etc., it may be formed by press molding, injection molding, extrusion molding, or the like. it can.

Since the vulcanized molded article of this embodiment uses the rubber composition of this embodiment, it has excellent mechanical strength, heat resistance, oil resistance, and cold resistance. The vulcanized molded article of this embodiment includes a transmission belt, a conveyor belt, a hose, a wiper, a sealing material (packing, gasket, etc.), a roll, an air spring, a vibration isolator, an adhesive, a boot, a rubberized cloth, a sponge, and a rubber. It can be used as a lining. The rubber composition and the vulcanized product of the present embodiment can be used to obtain a vulcanized molded product used for these applications. The vulcanized molded article of the present embodiment is excellent in mechanical strength, heat resistance, oil resistance and cold resistance, and therefore, it can be suitably used in applications where it has been difficult to achieve with conventional CR (chloroprene rubber) and the like. it can.

(Transmission belt and conveyor belt)
The power transmission belt and the conveyor belt are mechanical elements used in the winding power transmission device, and are parts for transmitting power from the prime mover to the driven car. The power transmission belt and the conveyor belt are often used around a pulley set on a shaft. BACKGROUND ART Transmission belts and conveyor belts are widely used in a wide range of machines such as automobiles, general industrial belts, and various conveyor belts because of their light weight, quietness, and freedom of shaft angle. The types of belts are diversifying, and transmission belts such as flat belts, timing belts, V belts, rib belts, and round belts; conveyor belts are used according to the application of the machine. In order to efficiently transmit power, the belt applied with a high tension repeats rotational deformation. Therefore, in conventional transmission belts and conveyor belts, NR (natural rubber), SBR (styrene-butadiene rubber), CR, NBR ( Elastomer materials such as nitrile rubber) and HNBR (hydrogenated nitrile rubber) are used. Since CR has excellent rubber physical properties, it is used in automobiles, general industrial belts, various conveyor belts, etc. However, it is a constant technical problem to improve mechanical strength in order to withstand high tension. Further, belts and the like of machine tools used at construction sites are sometimes used in an environment where they are exposed to splashed oil, so improvement in oil resistance is required.

The rubber composition of the present embodiment can enhance the mechanical strength and oil resistance of the transmission belt and the conveyor belt. This makes it possible to manufacture a belt that can be used even in an environment where it is exposed to splashed oil, which was difficult to achieve with conventional CR.

(hose)
The hose is a bendable tube, and is freely bent and used for work (watering, etc.) that requires portability and mobility. Further, since the hose is less likely to cause fatigue fracture due to deformation as compared with a hard pipe (metal pipe or the like), the hose is used for pipes (portion of automobiles and the like) in a portion accompanied by vibration. The most common of these is the rubber hose. Rubber hoses are made of NR, CR, EPDM (ethylene / propylene / diene rubber), SBR, NBR, ACM (acrylic rubber), AEM (ethylene / acrylic rubber), HNBR, ECO (epichlorohydrin rubber), FKM (fluorine rubber), etc. Examples thereof include a water supply hose, an oil supply hose, an air supply hose, a steam hose, a hydraulic high pressure hose, and a hydraulic low pressure hose. CR is mainly used in high-pressure hydraulic hoses because of its good mechanical strength that can withstand the pressure of high-pressure fluid, but it is common to use NBR as the inner layer because of its lack of oil resistance. is there. However, it is difficult to bond CR and NBR having greatly different chemical structures, and if bonding is insufficient, there is a problem of peeling at the interface. Therefore, a material having good mechanical strength and oil resistance is eagerly desired. Further, as a hose that is in direct contact with a non-polar liquid, the oil resistance of CR is insufficient, and improvement is essential.

The rubber composition of the present embodiment can enhance the mechanical strength and oil resistance of the hose. This makes it possible to manufacture a hose that is in direct contact with a non-polar liquid, which was difficult to achieve with conventional CR.

(Wiper)
For windshields and rear windshields of automobiles, trains, aircraft, ships, construction machines, etc., wipe or remove rainwater, muddy water, oil stains, seawater, ice, snow, dust, etc. adhering to the surface to improve visibility. Therefore, a wiper is usually provided to ensure driving safety. A wiper blade is attached to a portion of the wiper that comes into contact with the glass surface, and NR, CR and the like are used as materials for the conventional wiper blade. CR is used for a wiper for an automobile because it has mechanical strength and durability to withstand repeated deformation, and has excellent wiping properties. However, since CR has insufficient oil resistance, there is a problem that the wiping property deteriorates when the rubber material swells due to oil stains. Therefore, a wiper blade having excellent oil resistance is required in an environment where there is much oil stain.

The rubber composition of the present embodiment can enhance the mechanical strength and oil resistance of the wiper. As a result, it is possible to manufacture a wiper that can be used even in an environment where there is much oil stain, which was difficult to achieve with conventional CR.

(Seal material)
The sealing material is a component that prevents liquid or gas from leaking and prevents dust or foreign matter such as rainwater or dust from entering the inside of the machine, and plays an important role in maintaining the performance of the machine. Examples of the sealing material include gaskets used for fixed applications, packing used for moving parts and movable parts, and the like. In a gasket whose seal portion is fixed by bolts or the like, various elastomers are used as materials for soft gaskets such as O-rings and rubber sheets depending on the purpose. Further, the packing is used for a shaft of a pump or a motor, a rotating part such as a movable part of a valve, a reciprocating part such as a piston, a connecting part of a coupler, and a water stop part of a water faucet. The hydraulic equipment having a relatively low pressure or the oil seal used for sealing the lubricating oil ensures the hermeticity by the elasticity of the elastomer. In these elastomer seal materials, CR has good mechanical strength and is used as a polar gas or liquid seal material. On the other hand, the CR oil resistance is insufficient for use as a seal material for non-polar liquids such as engine oil or gear oil, and improvement is essential.

The rubber composition of the present embodiment can enhance the mechanical strength and oil resistance of the sealing material. This makes it possible to manufacture a non-polar liquid sealant such as engine oil or gear oil, which has been difficult to achieve with conventional CR.

Sealing materials for engine head cover gasket, oil pan gasket, oil seal, lip seal packing, O-ring, transmission seal gasket, crankshaft, camshaft seal gasket, valve stem, power steering seal belt cover seal, constant velocity joint Examples include boot materials, rack and pinion boot materials, diaphragms, and the like.

(roll)
The roll is manufactured by adhesively coating a metal core such as an iron core with rubber, and is generally manufactured by spirally winding a rubber sheet around a metal iron core. For the rolls, rubber materials such as NBR, EPDM, and CR are used according to the required characteristics of various applications such as papermaking, various metal manufacturing, printing, general industry, agricultural machinery such as hulling, and food processing. .. CR is used in a wide range of roll applications because it has good mechanical strength to withstand the friction of the objects it conveys. On the other hand, the oil resistance is insufficient as a roll used in an environment where oil adheres, such as when manufacturing industrial materials for iron making or paper making, products, etc., and improvement is required. Further, there is a problem that a roll that conveys a heavy load is deformed by a load, and improvement is required.

The rubber composition of the present embodiment can improve the mechanical strength and oil resistance of the roll. This makes it possible to manufacture a roll that is used in an environment where oil adheres, which was difficult to achieve with conventional CR.

(Air spring)
The air spring is a spring device that utilizes the elasticity of compressed air. Used in air suspensions for automobiles, buses, trucks, etc. Examples of the air spring include a bellows type and a sleeve type (a kind of diaphragm type), both of which can increase the air pressure by allowing the piston to enter the air chamber. In some cases, it is used in an environment where it is exposed to splashed oil, and improvement in oil resistance is required.

The rubber composition of the present embodiment can enhance the mechanical strength and oil resistance of the air spring. As a result, it is possible to manufacture an air spring that can be used even in an environment where there is much oil stain, which was difficult to achieve with conventional CR.

(Vibration isolator)
The anti-vibration material is a rubber that prevents the transmission of vibrations, and is used, for example, for the purpose of soundproofing or shock absorption, and for the purpose of preventing the vibration generated from a machine from spreading to the outside. For example, in automobiles or various vehicles, a vibration damping material is used as a constituent material of a torsional damper, an engine mount, a muffler hanger, etc., in order to absorb noise when driving an engine and prevent noise. Natural rubber having excellent vibration damping properties is widely used as the vibration damping material, but CR is used as the vibration damping material used in construction heavy machinery and the like where oil is scattered. When the vibration-proof material swells due to the adhesion of oil, the mechanical strength is lowered, and the vibration-proof material is broken at an early stage. Therefore, improvement is required.

The rubber composition of the present embodiment can enhance the mechanical strength and oil resistance of the vibration damping material. As a result, it is possible to manufacture a vibration-proof material (vibration-proof rubber) that can be used even in an environment where oil is scattered, which was difficult to achieve with conventional CR.

(adhesive)
CR is used as an adhesive for a wide range of materials such as civil engineering and construction, plywood, furniture, shoes, wet suits, and automobile interior materials because CR has contact properties and is excellent in initial adhesive strength. Among these, since CR has excellent initial adhesive strength and heat resistant adhesive strength, the demand as a one-component adhesive for polyurethane foam, which is widely used as a material for furniture or automobile interior materials, is greatly expanding. High aesthetics are required for the interior of automobiles, but the oil resistance of CR is insufficient. Therefore, if splashes of various oils or fuels used in automobiles adhere to the adherend, they may peel off at the interface, The surface of the adherend may be curved. Therefore, an adhesive material having a high oil resistance has been earnestly desired.

The rubber composition of the present embodiment can enhance the mechanical strength and oil resistance of the adhesive. This makes it possible to manufacture an adhesive that is superior to the conventional CR.

(boots)
The boot is a member having a bellows shape whose outer diameter gradually increases from one end to the other end, and is a boot for a constant velocity joint cover and a boot for a ball joint cover ( Dust cover boots) and rack and pinion gear boots. In boots, CR is often used because physical strength required to withstand large deformation is required. In recent years, the operating space of boots has been narrowed with the progress of lightweight and compact technology for vehicles, so that the heat removal efficiency is reduced and the thermal environment is becoming more severe. Therefore, it is required to improve the reliability of the non-polar liquid such as oil and grease contained in the boot under a high temperature atmosphere.

The rubber composition of the present embodiment can enhance the mechanical strength and oil resistance of the boot. This makes it possible to manufacture a boot that is more reliable than a conventional CR with respect to non-polar liquids such as oil and grease contained therein.

(Rubber cloth)
The rubberized cloth is a composite material of rubber and cloth woven fabric (fiber) in which rubber is attached to cloth, and is stronger than a rubber sheet, and is excellent in water resistance, airtightness and the like. Utilizing these characteristics, it is widely used for applications such as inflatable boats, tent materials, clothes such as rain fluff, architectural waterproof sheets, and cushioning materials. As the rubber material used for the rubberized cloth, CR, NBR, EPDM, etc. are generally used. Among them, CR is widely used for pulling cloths used outdoors such as inflatable boats because it has excellent mechanical strength and weather resistance. On the other hand, the oil resistance is insufficient for use in a rubberized cloth sheet material used in an environment where oil is scattered, such as in an automobile or a construction site, and improvement is required.

The rubber composition of this embodiment can enhance the mechanical strength and oil resistance of the rubberized fabric. As a result, it is possible to manufacture a rubberized cloth that can be used even in an environment where oil is scattered, which was difficult to achieve with conventional CR.

(sponge)
A sponge is a porous substance with innumerable fine holes inside. The pores can take the form of both open and closed cells. When the pores are large enough and continuous, the sponge has the property of absorbing the liquid when it is immersed in the liquid and replacing the air in the pores, and releasing the liquid easily when external force is applied. Have. Also, if the pores are small, it can be used as an excellent cushioning material or heat insulating material. Since CR has excellent mechanical strength and rubber elasticity, it is widely used for sponges, and is used for anti-vibration members, sponge seal parts, wet suits, shoes and the like. In any application, improvement of oil resistance is required to prevent swelling deformation, discoloration, etc. due to oil.

The rubber composition of the present embodiment can enhance the mechanical strength and oil resistance of the sponge. As a result, it is possible to manufacture a sponge that is difficult to achieve with conventional CR and is unlikely to undergo swelling deformation, discoloration, etc. due to oil.

(Rubber lining)
The rubber lining is used to prevent corrosion of metal by adhering a rubber sheet to a metal surface such as a pipe or a tank. Rubber linings are also used where electrical or abrasion resistance is required. As the conventional rubber lining, NR, CR, EPDM, SBR and the like are used, but the oil resistance may be insufficient, and it is required to improve the oil resistance.

The rubber composition of the present embodiment can improve oil resistance as a rubber lining. As a result, it is possible to prevent the corrosion of the pipe or tank with oil, which is difficult with the conventional rubber material.

Hereinafter, the present invention will be described in more detail based on examples. The embodiments described below are examples of typical embodiments of the present invention, and the scope of the present invention should not be construed narrowly.

<Manufacture of chloroprene rubber>
(Production Example 1: Chloroprene rubber 1 (acrylonitrile copolymerization amount: 5% by mass))
In a polymerization vessel having an internal volume of 3 liter equipped with a heating / cooling jacket and a stirrer, 32 parts by mass of chloroprene monomer, 14 parts by mass of acrylonitrile monomer, 0.5 part by mass of diethylxanthogen disulfide, 200 parts by mass of pure water, rosin acid 5.00 parts by mass of potassium (manufactured by Harima Kasei Co., Ltd.), 0.40 parts by mass of sodium hydroxide, and 2.0 parts by mass of sodium salt of β-naphthalenesulfonic acid formalin condensate (manufactured by Kao Co., Ltd.) were added. .. Next, 0.1 part by mass of potassium persulfate was added as a polymerization initiator, and then emulsion polymerization was carried out at a polymerization temperature of 40 ° C. under a nitrogen stream. The addition of the chloroprene monomer started 20 seconds after the start of the polymerization, and the addition flow rate was adjusted with a solenoid valve based on the change in the amount of heat of the refrigerant for 10 seconds after the start of the polymerization. It was performed continuously by adjusting. When the polymerization rate with respect to the total amount of the chloroprene monomer and the acrylonitrile monomer reached 50%, phenothiazine as a polymerization inhibitor was added to terminate the polymerization. Then, the unreacted monomer in the reaction solution was removed under reduced pressure to obtain a chloroprene-acrylonitrile copolymer latex.

The polymerization rate of the chloroprene-acrylonitrile copolymer latex was calculated from the dry mass of the chloroprene-acrylonitrile copolymer latex air-dried. Specifically, it was calculated from the following formula (II). In the formula, the solid content concentration means the concentration of solid content obtained by heating 2 g of sampled chloroprene-acrylonitrile copolymer latex at 130 ° C. and removing volatile components such as solvent (water), volatile chemicals and raw materials [mass %]. The total amount charged is the total amount of raw materials, reagents and solvent (water) charged in a polymerization vessel from the start of polymerization to a certain time. The evaporation residue is the mass of the chemicals and raw materials charged from the start of the polymerization to a certain time and remaining as a solid content together with the polymer without being volatilized under the condition of 130 ° C. The monomer charging amount is the total of the amount of the monomer initially charged in the polymerization vessel and the amount of the monomer added by a certain time from the start of polymerization. The "monomer" referred to here is the total amount of the chloroprene monomer and the acrylonitrile monomer.
Polymerization rate [%] = {(total charged amount [g] × solid content concentration [mass%] / 100) − (evaporation residue [g])} / monomer charged amount [g] × 100 ( II)

A sheet was obtained by adjusting the pH of the above-mentioned chloroprene-acrylonitrile copolymer latex to pH 7.0 and freeze-coagulating it on a metal plate cooled to -20 ° C to break the emulsion. This sheet was washed with water and then dried at 130 ° C. for 15 minutes to obtain solid chloroprene rubber 1.

The number average molecular weight (Mn), the weight average molecular weight (Mw) and the molecular weight distribution (Mw / Mn) of the chloroprene rubber 1 were measured at high speed after the chloroprene rubber 1 was made into a solution having a sample adjusted concentration of 0.1 mass% with THF. It was measured by a GPC device (TOSOH HLC-8320GPC: manufactured by Tosoh Corporation) (standard polystyrene conversion). At that time, the TSK guard column HHR-H was used as a pre-column, three HSKgel GMHHR-H were used as an analytical column, and the sample pump pressure was 8.0 to 9.5 MPa, the flow rate was 1 ml / min, and the flow rate was 40 ° C. It was detected by the total.

The outflow time and the molecular weight were obtained using a calibration curve prepared by measuring 9 points of standard polystyrene samples with known molecular weights as shown below.
Mw = 8.42 × 10 ⁶ , 1.09 × 10 ⁶ , 7.06 × 10 ⁵ , 4.27 × 10 ⁵ , 1.90 × 10 ⁵ , 9.64 × 10 ⁴ , 3.79 × 10 ^4. 1,74 × 10 ⁴ , 2.63 × 10 ³

The amount of structural units derived from the unsaturated nitrile monomer contained in the chloroprene rubber 1 was calculated from the content of nitrogen atoms in the chloroprene rubber 1. Specifically, the content of nitrogen atoms in 100 mg of chloroprene rubber 1 was measured using an elemental analyzer (Sumigraph 220F: manufactured by Sumika Analytical Center Co., Ltd.), and the amount of structural units derived from an acrylonitrile monomer was calculated. did. The elemental analysis was performed under the following conditions. The electric furnace temperature was set to 900 ° C. for the reaction furnace, 600 ° C. for the reduction furnace, 70 ° C. for the column temperature, and 100 ° C. for the detector temperature. .. The calibration curve was prepared using aspartic acid (10.52%) with a known nitrogen content as a standard substance.

The chloroprene rubber 1 had a number average molecular weight (Mn) of 130 × 10 ³ g / mol, a weight average molecular weight (Mw) of 442 × 10 ³ g / mol, and a molecular weight distribution (Mw / Mn) of 3.4. The amount of structural units derived from the acrylonitrile monomer was 5% by mass.

(Production Example 2: Chloroprene rubber 2 (acrylonitrile copolymerization amount: 10% by mass))
In a polymerization vessel having an internal volume of 3 liters equipped with a heating / cooling jacket and a stirrer, 24 parts by mass of chloroprene monomer, 24 parts by mass of acrylonitrile monomer, 0.5 part by mass of diethylxanthogen disulfide, 200 parts by mass of pure water, rosin acid 5.00 parts by mass of potassium (manufactured by Harima Kasei Co., Ltd.), 0.40 parts by mass of sodium hydroxide, and 2.0 parts by mass of sodium salt of β-naphthalenesulfonic acid formalin condensate (manufactured by Kao Co., Ltd.) were added. .. Next, 0.1 part by mass of potassium persulfate was added as a polymerization initiator, and then emulsion polymerization was carried out at a polymerization temperature of 40 ° C. under a nitrogen stream. The addition of the chloroprene monomer started 20 seconds after the start of the polymerization, and the addition flow rate was adjusted with a solenoid valve based on the change in the amount of heat of the refrigerant for 10 seconds after the start of the polymerization. It was performed continuously by adjusting. When the polymerization rate with respect to the total amount of the chloroprene monomer and the acrylonitrile monomer reached 50%, phenothiazine as a polymerization inhibitor was added to terminate the polymerization. Then, the unreacted monomer in the reaction solution was removed under reduced pressure to obtain a chloroprene-acrylonitrile copolymer latex.

Solid chloroprene rubber 2 was obtained by freeze-coagulating, washing with water and drying the above chloroprene-acrylonitrile copolymer latex in the same manner as in Production Example 1.

As a result of analysis in the same manner as in Production Example 1, the chloroprene rubber 2 had a number average molecular weight (Mn) of 139 × 10 ³ g / mol, a weight average molecular weight (Mw) of 480 × 10 ³ g / mol, and a molecular weight distribution ( Mw / Mn) was 3.3. The amount of structural units derived from the acrylonitrile monomer was 10% by mass.

(Production Example 3: Chloroprene rubber 3 (acrylonitrile copolymerization amount: 15% by mass))
In a polymerization vessel having an internal volume of 3 liters equipped with a heating / cooling jacket and a stirrer, 16 parts by mass of chloroprene monomer, 33 parts by mass of acrylonitrile monomer, 0.5 parts by mass of diethylxanthogen disulfide, 200 parts by mass of pure water, rosin acid 5.00 parts by mass of potassium (manufactured by Harima Kasei Co., Ltd.), 0.40 parts by mass of sodium hydroxide, and 2.0 parts by mass of sodium salt of β-naphthalenesulfonic acid formalin condensate (manufactured by Kao Co., Ltd.) were added. .. Next, 0.1 part by mass of potassium persulfate was added as a polymerization initiator, and then emulsion polymerization was carried out at a polymerization temperature of 40 ° C. under a nitrogen stream. The addition of the chloroprene monomer started 20 seconds after the start of the polymerization, and the addition flow rate was adjusted with a solenoid valve based on the change in the amount of heat of the refrigerant for 10 seconds after the start of the polymerization. It was performed continuously by adjusting. When the polymerization rate with respect to the total amount of the chloroprene monomer and the acrylonitrile monomer reached 50%, phenothiazine as a polymerization inhibitor was added to terminate the polymerization. Then, the unreacted monomer in the reaction solution was removed under reduced pressure to obtain a chloroprene-acrylonitrile copolymer latex.

Solid chloroprene rubber 3 was obtained by freeze-coagulating, washing with water and drying the above chloroprene-acrylonitrile copolymer latex in the same manner as in Production Example 1.

As a result of analysis by the same method as in Production Example 1, the chloroprene rubber 3 had a number average molecular weight (Mn) of 131 × 10 ³ g / mol, a weight average molecular weight (Mw) of 451 × 10 ³ g / mol, and a molecular weight distribution ( Mw / Mn) was 3.4. The amount of structural units derived from the acrylonitrile monomer was 15% by mass.

(Production Example 4: Chloroprene rubber 4 (acrylonitrile copolymerization amount: 20% by mass))
In a polymerization vessel having an internal volume of 3 liter equipped with a heating / cooling jacket and a stirrer, 10 parts by mass of chloroprene monomer, 40 parts by mass of acrylonitrile monomer, 0.5 part by mass of diethylxanthogen disulfide, 200 parts by mass of pure water, rosin acid 5.00 parts by mass of potassium (manufactured by Harima Kasei Co., Ltd.), 0.40 parts by mass of sodium hydroxide, and 2.0 parts by mass of sodium salt of β-naphthalenesulfonic acid formalin condensate (manufactured by Kao Co., Ltd.) were added. .. Next, 0.1 part by mass of potassium persulfate was added as a polymerization initiator, and then emulsion polymerization was carried out at a polymerization temperature of 40 ° C. under a nitrogen stream. The addition of the chloroprene monomer started 20 seconds after the start of the polymerization, and the addition flow rate was adjusted with a solenoid valve based on the change in the amount of heat of the refrigerant for 10 seconds after the start of the polymerization. It was performed continuously by adjusting. When the polymerization rate with respect to the total amount of the chloroprene monomer and the acrylonitrile monomer reached 50%, phenothiazine as a polymerization inhibitor was added to terminate the polymerization. Then, the unreacted monomer in the reaction solution was removed under reduced pressure to obtain a chloroprene-acrylonitrile copolymer latex.

Solid chloroprene rubber 4 was obtained by freeze-coagulating, washing with water and drying the above-mentioned chloroprene-acrylonitrile copolymer latex in the same manner as in Production Example 1.

As a result of analysis by the same method as in Production Example 1, the number average molecular weight (Mn) of the chloroprene rubber 4 was 135 × 10 ³ g / mol, the weight average molecular weight (Mw) was 457 × 10 ³ g / mol, and the molecular weight distribution ( Mw / Mn) was 3.3. The amount of structural units derived from the acrylonitrile monomer was 20% by mass.

(Production Example 5: Chloroprene rubber 5 (acrylonitrile copolymerization amount: 1% by mass))
In a polymerization vessel having an internal volume of 3 liters equipped with a heating / cooling jacket and a stirrer, 37 parts by mass of chloroprene monomer, 4 parts by mass of acrylonitrile monomer, 0.5 part by mass of diethylxanthogen disulfide, 200 parts by mass of pure water, rosin acid 5.00 parts by mass of potassium (manufactured by Harima Kasei Co., Ltd.), 0.40 part by mass of sodium hydroxide, and 2.0 parts by mass of sodium salt of β-naphthalenesulfonic acid formalin condensate (manufactured by Kao Co., Ltd.) were added. .. Next, 0.1 part by mass of potassium persulfate was added as a polymerization initiator, and then emulsion polymerization was carried out at a polymerization temperature of 40 ° C. under a nitrogen stream. The addition of the chloroprene monomer started 20 seconds after the start of the polymerization, and the addition flow rate was adjusted with a solenoid valve based on the change in the amount of heat of the refrigerant for 10 seconds after the start of the polymerization. It was performed continuously by adjusting. When the polymerization rate with respect to the total amount of the chloroprene monomer and the acrylonitrile monomer reached 50%, phenothiazine as a polymerization inhibitor was added to terminate the polymerization. Then, the unreacted monomer in the reaction solution was removed under reduced pressure to obtain a chloroprene-acrylonitrile copolymer latex.

Solid chloroprene rubber 5 was obtained by freeze-coagulating, washing with water and drying the above chloroprene-acrylonitrile copolymer latex in the same manner as in Production Example 1.

As a result of analysis in the same manner as in Production Example 1, the chloroprene rubber 5 had a number average molecular weight (Mn) of 136 × 10 ³ g / mol, a weight average molecular weight (Mw) of 460 × 10 ³ g / mol, and a molecular weight distribution ( Mw / Mn) was 3.2. The amount of structural units derived from the acrylonitrile monomer was 1% by mass.

(Production Example 6: Chloroprene rubber 6 (acrylonitrile copolymerization amount: 25% by mass))
In a polymerization vessel having an internal volume of 3 liter equipped with a heating / cooling jacket and a stirrer, 7 parts by mass of chloroprene monomer, 45 parts by mass of acrylonitrile monomer, 0.5 part by mass of diethylxanthogen disulfide, 200 parts by mass of pure water, rosin acid 5.00 parts by mass of potassium (manufactured by Harima Kasei Co., Ltd.), 0.40 parts by mass of sodium hydroxide, and 2.0 parts by mass of sodium salt of β-naphthalenesulfonic acid formalin condensate (manufactured by Kao Co., Ltd.) were added. .. Next, 0.1 part by mass of potassium persulfate was added as a polymerization initiator, and then emulsion polymerization was carried out at a polymerization temperature of 40 ° C. under a nitrogen stream. The addition of the chloroprene monomer started 20 seconds after the start of the polymerization, and the addition flow rate was adjusted with a solenoid valve based on the change in the amount of heat of the refrigerant for 10 seconds after the start of the polymerization. It was performed continuously by adjusting. When the polymerization rate with respect to the total amount of the chloroprene monomer and the acrylonitrile monomer reached 50%, phenothiazine as a polymerization inhibitor was added to terminate the polymerization. Then, the unreacted monomer in the reaction solution was removed under reduced pressure to obtain a chloroprene-acrylonitrile copolymer latex.

Solid chloroprene rubber 6 was obtained by freeze-coagulating, washing with water and drying the above-mentioned chloroprene-acrylonitrile copolymer latex in the same manner as in Production Example 1.

As a result of analysis by the same method as in Production Example 1, the number average molecular weight (Mn) of the chloroprene rubber 6 was 135 × 10 ³ g / mol, the weight average molecular weight (Mw) was 459 × 10 ³ g / mol, and the molecular weight distribution ( Mw / Mn) was 3.3. The amount of structural units derived from the acrylonitrile monomer was 25% by mass.

<Production of evaluation sheet>
The above-mentioned chloroprene rubber (chloroprene-acrylonitrile copolymer) 1 to 6 and the compounds shown in Tables 1 and 2 were mixed using an 8-inch roll and then dispensed to obtain a rubber composition. Then, this rubber composition was subjected to press vulcanization at 160 ° C. for 20 minutes to prepare a rubber sheet for evaluation (evaluation sheet) having a sheet length of 200 mm, a sheet width of 15 mm and a thickness of 2.1 mm. The amounts of zinc oxide used shown in Tables 1 and 2 are the total amounts of the two types of zinc oxide.

The compounds used in Tables 1 and 2 are as follows.
Mercaptan-modified chloroprene rubber: Denka Co., Ltd., raw rubber Mooney viscosity ML _{1 + 4} (100 ° C.) = 60
Carbon black A: acetylene black, manufactured by Denka Co., Ltd., Denka Black granular product, average stacking height in the C-axis direction of the layer plane in the crystal lattice = 3.5 nm, average particle size = 35 nm, DBP oil absorption = 210 ml / 100 g
Carbon black B: manufactured by Tokai Carbon Co., Ltd., SEAST SO, FEF carbon, average stacking height in the C-axis direction of the layer plane in the crystal lattice = 1.6 nm, average particle size = 43 nm, DBP oil absorption = 115 ml / 100 g.
Zinc powder: Sakai Chemical Industry Co., Ltd., zinc powder # 7, average particle size = 4 μm
Vulcanizing agent (zinc oxide): Sakai Chemical Industry Co., Ltd., 2 types of zinc oxide,
Vulcanization accelerator: Kawaguchi Chemical Industry Co., Ltd., Accel (registered trademark) 22-S, ethylene thiourea Lubricant / processing aid: Shin Nippon Rika Co., Ltd., stearic acid 50S
Anti-aging agent: Ouchi Shinko Chemical Co., Ltd., Nocrac (registered trademark) CD, 4,4'-bis (α, α-dimethylbenzyl) diphenylamine Plasticizer: Daihachi Chemical Co., Ltd., dioctyl sebacate oxidation Magnesium: Kyowa Mag (registered trademark) 150 manufactured by Kyowa Chemical Industry Co., Ltd.

<Evaluation>
The following evaluation was performed using the above-mentioned evaluation sheet. The evaluation results are shown in Tables 1 and 2.

(Mechanical strength (tensile strength (TB)))
A test piece was prepared based on JIS K6250. A tensile test was performed based on JIS K 6251, and the tensile strength (TB) was measured as the mechanical strength of each test piece (vulcanized product). When the tensile strength (TB) is 22 MPa or more, it is evaluated as "A (especially good)", when it is 18 MPa or more and less than 22 MPa, it is evaluated as "B (good)", and when it is 15 MPa or more and less than 18 MPa. C (somewhat good) was evaluated, and when it was less than 15 MPa, it was evaluated as "D (bad)".

(Heat-resistant)
A test piece was prepared based on JIS K6250. The hardness of the test piece was measured by leaving the test piece in a gear oven at 120 ° C. for 72 hours. A hardness change of less than 8 is evaluated as "A (especially good)", a hardness change of 8 or more and less than 10 is evaluated as "B (good)", and a hardness change of 10 or more and less than 12 is "C (somewhat good). "Good""was evaluated, and when 12 or more was evaluated as" D (bad) ".

(Oil resistance)
A test piece was prepared based on JIS K6250. Based on JIS K 6258, an oil resistance test (test conditions: 100 ° C. × 72 hours) was performed using IRM903 oil, and the volume change rate (ΔV) was measured. When the volume change rate is less than 30%, it is evaluated as "A (particularly good)", and when it is 30% or more and less than 45%, it is evaluated as "B (good)" and 45% or more and less than 60%. The case was evaluated as "C (somewhat good)", and the case of 60% or more was evaluated as "D (bad)".

(Cold resistance)
A test piece was prepared based on JIS K6250. A low temperature twisting test (Geman twisting test) was performed based on JIS K 6261 to measure a twisting angle A at 23 ± 2 ° C. Then, from the twist angle B corresponding to the modulus of 10 times the value of the twist angle A, the temperature T10 corresponding to the angle of the twist angle B was measured. When T10 is less than -25 ° C, it is evaluated as "A (especially good)", and when T10 is -25 ° C or more and less than -18 ° C, it is evaluated as "B (good)", -18 ° C or more and -10 ° C. When it was less than "C" (somewhat good), it was evaluated as "C (somewhat good)", and when it was -10 ° C or more, it was evaluated as "D (bad)".

From the results shown in Table 1 and Table 2, a rubber composition containing 100 parts by mass of a chloroprene rubber having 3 to 20% by mass of a structural unit derived from an unsaturated nitrile monomer, and a specific amount of specific carbon black and zinc powder. It was found that a vulcanized product and a vulcanized molded product having excellent mechanical strength, heat resistance, oil resistance and cold resistance can be obtained. Since the vulcanized product and the vulcanized molded product have these properties, they are a transmission belt, a conveyor belt, a hose, a wiper, a sealing material (packing, gasket, etc.), a roll, an air spring, a vibration isolator, an adhesive, a boot. It can be suitably used as a vulcanized molded product such as a rubberized cloth, a sponge, and a rubber lining.

Claims

Contains 100 parts by mass of chloroprene rubber, 20 to 80 parts by mass of carbon black, and 0.2 to 30 parts by mass of zinc powder,
The chloroprene rubber has 3 to 20% by mass of a structural unit derived from an unsaturated nitrile monomer,
A rubber composition in which the average stacking height LC in the C-axis direction of the layer plane in the crystal lattice of the carbon black is 2 nm or more.
The chloroprene rubber comprises a chloroprene rubber A having 4 to 40% by mass of a structural unit derived from an unsaturated nitrile monomer, and a chloroprene rubber B having no structural unit derived from an unsaturated nitrile monomer. The rubber composition according to claim 1, which comprises:
The rubber composition according to claim 1 or 2, wherein the carbon black is acetylene black.
The rubber composition according to any one of claims 1 to 3, wherein the unsaturated nitrile monomer is acrylonitrile.
A vulcanized product of the rubber composition according to any one of claims 1 to 4.
A vulcanized molded product of the rubber composition according to any one of claims 1 to 4.