Rubber composition, vulcanized product, and vulcanized molded article

Abstract

Provided is a rubber composition with which it is possible to obtain a vulcanized product and a vulcanized molded product having excellent wear resistance. According to the present invention, there is provided a rubber composition containing a chloroprene rubber, silica, a silane coupling agent, and a hydrate, the rubber composition containing 5-80 parts by mass of silica and 0.5-20 parts by mass or more of hydrate per 100 parts by mass of the chloroprene rubber, and the rubber composition containing 5-80 parts by mass of silica and 0.5-20 parts by mass of hydrate per 100 parts by mass of the chloroprene rubber. The content of a silane coupling agent is 0.5-15 parts by mass per 100 parts by mass of the silica, and the rubber composition satisfies at least one of the following conditions i) and ii): condition i) the rubber composition contains 3-methyl-thiazolidine-2-thione, and in the rubber composition, the content of 3-methyl-thiazolidine-2-thione is 0.5-15 parts by mass per 100 parts by mass of the chloroprene-based rubber, and the content of 3-methyl-thiazolidine-2-thione is 0.5-15 parts by mass per 100 parts by mass of the chloroprene-based rubber. The composition contains 0.1 to 3.0 parts by mass of 3-methyl-thiazolidine-2-thioketone; condition ii) the rubber composition contains a compound A and a compound B. The compound A is at least one compound selected from the group consisting of thiourea compounds, 3-methyl-thiazolidine-2-thione, and bis (5-mercapto-1, 3, 4-thiadiazol-2-yl) disulfides, and the compound B is at least one compound selected from the group consisting of thiourea compounds, 3-methyl-thiazolidine-2-thione, and bis (5-mercapto-1, 3, 4-thiadiazol-2-yl) disulfides. The compound B is at least one compound selected from the group consisting of thiuram-based compounds, sulfinamide-based compounds, thiazole-based compounds, guanidine-based compounds, benzimidazole-based compounds, N-phenyl-N-(trichloromethylthio) benzsulfonamide, and diazabicyclo-undecene-based compounds, and the content of the compound B is 100 parts by mass per 100 parts by mass of the chloroprene rubber. The rubber composition contains 0.1 to 3.0 parts by mass of a compound A and 0.01 to 3.0 parts by mass of a compound B.

Description

Technical Field

[0001] Chloroprene rubber has excellent mechanical properties, ozone resistance, and chemical resistance, and is widely used in automotive parts, adhesives, various industrial rubber parts, etc. due to its characteristics. In recent years, the performance requirements for rubber parts have increased significantly. For example, further improvement in abrasion resistance is required. Background Art

[0002] Patent Document 1 discloses a composition for chloroprene-based vulcanized rubber, which contains 100 parts by mass of a polymer for chloroprene-based vulcanized rubber, 0.5 to 6 parts by mass of an acid acceptor, 0.2 to 3 parts by mass of a lubricant, 1 to 5 parts by mass of an anti-aging agent, 10 to 120 parts by mass of carbon black, 0.1 to 20 parts by mass of a filler other than carbon black, 2 to 40 parts by mass of a softening agent, 0.2 to 5 parts by mass of a processing aid, 0.5 to 10 parts by mass of a metal oxide, and 0.5 to 5 parts by mass of a vulcanization accelerator; the polymer for chloroprene-based vulcanized rubber, in terms of the ratio of each monomer constituting the polymer, when the total amount of all monomers is set to 100% by mass, is a copolymer composed of 80 to 97% by mass of 2-chloro-1,3-butadiene (chloroprene) (C-1) and 20 to 3% by mass of 2,3-dichloro-1,3-butadiene (C-2), or a copolymer composed of 79.8 to 96.8% by mass of 2-chloro-1,3-butadiene (chloroprene) (C-1), 20 to 3% by mass of 2,3-dichloro-1,3-butadiene (C-2), and 0.2 to 17% by mass of a monomer copolymerizable therewith (C-3), and the Mooney viscosity (ML1+4(100°C)) of the polymer is in the range of 100 to 135.

[0003] In addition, Patent Document 2 discloses a rubber composition for a flame-retardant hose, which contains a rubber component, carbon black, and silica, wherein the rubber component is only chloroprene rubber, or only chloroprene rubber and styrene-butadiene rubber.

[0004] [Prior Art Documents]

[0005] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-211345

[0007] [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-019947 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] However, there is still room for improvement in the abrasion resistance of the resulting sulfide and vulcanized molded article of the existing chloroprene rubber composition. The present invention has been completed in view of the above circumstances, and an object thereof is to provide a rubber composition capable of obtaining a sulfide and a vulcanized molded article having excellent abrasion resistance.

[0010] Means for Solving the Problem

[0011] According to the present invention, there is provided a rubber composition comprising a chloroprene rubber, silica, a silane coupling agent, and a hydrate. In the rubber composition, 5 to 80 parts by mass of silica and 0.5 part by mass or more and less than 20 parts by mass of the hydrate are contained with respect to 100 parts by mass of the chloroprene rubber, and 0.5 to 15 parts by mass of the silane coupling agent is contained with respect to 100 parts by mass of the silica, and the rubber composition satisfies at least one of the following conditions i) and ii).

[0012] Condition i) The rubber composition contains 3-methyl-thiazolidine-2-thione, and 0.1 to 3.0 parts by mass of 3-methyl-thiazolidine-2-thione is contained with respect to 100 parts by mass of the chloroprene rubber in the rubber composition.

[0013] Condition ii) The rubber composition contains Compound A and Compound B. Compound A is at least one selected from thiourea compounds, 3-methyl-thiazolidine-2-thione, and bis(5-mercapto-1,3,4-thiadiazol-2-yl) disulfide, and Compound B is at least one selected from thiuram compounds, sulfenamide compounds, thiazole compounds, guanidine compounds, benzimidazole compounds, N-phenyl-N-(trichloromethylthio)benzenesulfonamide, and diazabicycloundecene compounds. 0.1 to 3.0 parts by mass of Compound A and 0.01 to 3.0 parts by mass of Compound B are contained with respect to 100 parts by mass of the chloroprene rubber in the rubber composition.

[0014] Generally, in a rubber composition containing a chloroprene rubber, when silica as a filler and a vulcanization accelerator that provides sulfur as a crosslinking agent are used in combination, vulcanization may not proceed sufficiently. Here, the reason why vulcanization does not proceed sufficiently when silica and the vulcanization accelerator are combined is presumed to be that the silica surface is covered with silanol groups and becomes acidic, or that the vulcanization is inhibited because the vulcanization accelerator is adsorbed on the silica surface. As a result of intensive studies by the present inventors, it has been found that by using a certain amount of a specific compound and / or using a combination of a certain amount of a specific compound A and a specific compound B in a chloroprene rubber composition containing silica, a rubber composition that can be vulcanized sufficiently and can obtain a vulcanizate and a vulcanized molded article having excellent abrasion resistance can be produced, and thus the present invention has been completed.

[0015] The following exemplify various embodiments of the present invention. The embodiments shown below can be combined with each other.

[0016] [1] A rubber composition comprising a chloroprene rubber, silica, a silane coupling agent, and a hydrate. In the rubber composition, 5 to 80 parts by mass of silica and 0.5 part by mass or more and less than 20 parts by mass of the hydrate are contained with respect to 100 parts by mass of the chloroprene rubber, and 0.5 to 15 parts by mass of the silane coupling agent is contained with respect to 100 parts by mass of the silica. The rubber composition satisfies at least one of the following conditions i) and ii).

[0017] Condition i) The rubber composition contains 3-methyl-thiazolidine-2-thione, and 0.1 to 3.0 parts by mass of 3-methyl-thiazolidine-2-thione is contained with respect to 100 parts by mass of the chloroprene rubber in the rubber composition.

[0018] Condition ii) The rubber composition contains compound A and compound B. Compound A is at least one selected from the group consisting of thiourea compounds, 3-methyl-thiazolidine-2-thione, and bis(5-mercapto-1,3,4-thiadiazol-2-yl) disulfide, and compound B is at least one selected from the group consisting of thiuram compounds, sulfenamide compounds, thiazole compounds, guanidine compounds, benzimidazole compounds, N-phenyl-N-(trichloromethylthio) benzenesulfonamide, and diazabicycloundecene compounds. 0.1 to 3.0 parts by mass of compound A and 0.01 to 3.0 parts by mass of compound B are contained with respect to 100 parts by mass of the chloroprene rubber in the rubber composition.

[0019] [2] The rubber composition according to [1], wherein the chloroprene rubber contains an unsaturated nitrile monomer unit.

[0020] [3] The rubber composition according to [1] or [2], wherein the silane coupling agent is a silane coupling agent containing an amino group in its structure.

[0021] [4] The rubber composition according to any one of [1] to [3], wherein the hydrate is a hydrate that releases H2O in the temperature range of 100°C to 250°C.

[0022] [5] The rubber composition according to any one of [1] to [4], wherein the hydrate is selected from at least one hydrate of a hydrotalcite compound, a hydrated salt, and a metal hydroxide represented by the following chemical formula (1):

[0023] [M 2+ 1-x M 3+ x (OH)2] x+ [A n- x / n ·mH2O] x- (1)

[0024] (M 2+ : selected from at least one divalent metal ion of Mg 2+ , Mn 2+ , Fe 2+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ ; M 3+ : selected from at least one trivalent metal ion of Al 3+ , Fe 3+ , Cr 3+ , Co 3+ , In 3+ ; A n- : selected from at least one n-valent anion of OH - , F - , Cl - , Br - , NO3 - , CO3 2- , SO4 2- , Fe(CN)6 3- , CH3COO - ; X: 0 < X ≤ 0.33)

[0025] [6] The rubber composition according to [5], wherein the hydrate is selected from Mg 4.3 Al2(OH) 12.6 CO3·3.5H2O, Mg3ZnAl2(OH) 12 CO3·3H2O, Mg 4.5Al2(OH) 13 CO3·3.5H2O, Mg 4.5 Al2(OH) 13 CO3, Mg4Al2(OH) 12 CO3·3.5H2O, Mg6Al2(OH) 16 CO3·4H2O, Mg5Al2(OH) 14 CO3·4H2O, Mg3Al2(OH) 10 At least one hydrate of the hydrotalcite compound represented by CO3·1.7H2O.

[0026] [7] The rubber composition according to any one of [1] to [6], wherein the BET specific surface area of the silica is 50 to 300 m 2 / g.

[0027] [8] The rubber composition according to any one of [1] to [7], wherein the rubber composition contains Compound A and Compound B, and in the rubber composition, 10 to 100 parts by mass of Compound B is contained relative to 100 parts by mass of Compound A.

[0028] [9] A rubber composition containing a chloroprene rubber, silica, a silane coupling agent, and a hydrate, wherein the rubber composition is pressure-vulcanized at 160 °C for 40 minutes to obtain a vulcanized molded article, and the wear volume ΔV of the vulcanized molded article in the Akron wear test based on JIS K6264-2 is 50 mm 3 or less.

[0029]

[10] The rubber composition according to [9], wherein the durometer hardness (Type A) specified in JIS K6253 of the vulcanized molded article is 30 to 90.

[0030]

[11] The rubber composition according to [9] or

[10] , wherein in the rubber composition, 5 to 80 parts by mass of the silica and 0.5 parts by mass or more and less than 20 parts by mass of the hydrate are contained relative to 100 parts by mass of the chloroprene rubber, and in the rubber composition, 0.5 to 15 parts by mass of the silane coupling agent is contained relative to 100 parts by mass of the silica.

[0031]

[12] The rubber composition according to any one of [9] to

[11] , the rubber composition contains at least one of 3-methyl-thiazolidine-2-thione, compound A, and compound B, compound A is at least one selected from thiourea compounds, 3-methyl-thiazolidine-2-thione, and bis(5-mercapto-1,3,4-thiadiazol-2-yl) disulfide, and compound B is at least one selected from thiuram compounds, sulfenamide compounds, thiazole compounds, guanidine compounds, benzimidazole compounds, N-phenyl-N-(trichloromethylthio)benzenesulfonamide, and diazabicycloundecene compounds.

[0032]

[13] A sulfide which is a sulfide of the rubber composition according to any one of [1] to

[12] .

[0033]

[14] A vulcanized molded article which is a vulcanized molded article of the rubber composition according to any one of [1] to

[12] .

[0034] Effects of the Invention

[0035] According to the rubber composition of the present invention, a sulfide and a vulcanized molded article having excellent abrasion resistance can be obtained. In addition, by utilizing its characteristics, the obtained sulfide and vulcanized molded article are suitably used as materials for, for example, drive belts or conveyor belts for general industrial use, air springs for automobiles, anti-vibration rubbers, hoses, windshield wipers, impregnated products, seals, adhesives, protective covers, rubber fabrics, rubber rollers, etc. The sulfide and vulcanized molded article according to an embodiment of the present invention can also be used as a component that particularly requires abrasion resistance. As an example, the sulfide and vulcanized molded article according to an embodiment of the present invention can be suitably used as a rubber roller that requires abrasion resistance, such as a rubber roller for embossing. Detailed Embodiments

[0036] Hereinafter, embodiments of the present invention will be exemplified to explain the present invention in detail. The present invention is not limited by any of these descriptions. The respective characteristic matters of the following embodiments of the present invention can be combined with each other. In addition, each characteristic matter independently constitutes an invention.

[0037] <First Aspect>

[0038] 1. Rubber Composition

[0039] The rubber composition of the present invention contains a chloroprene rubber, silica, a silane coupling agent, and a hydrate, and also contains 3-methyl-thiazolidine-2-thione and / or compounds A and B.

[0040] 1.1 Chloroprene Rubber

[0041] The chloroprene rubber of the present invention refers to a rubber containing a chloroprene-based polymer having a monomer unit (monomer unit = structural unit) of chloroprene (2-chloro-1,3-butadiene). As the chloroprene-based polymer, a chloroprene homopolymer, a chloroprene copolymer (a copolymer of chloroprene and a monomer copolymerizable with chloroprene) can be mentioned. The polymer structure of the chloroprene polymer is not particularly limited.

[0042] In addition, commercially available 2-chloro-1,3-butadiene may contain a small amount of 1-chloro-1,3-butadiene impurities. Such 2-chloro-1,3-butadiene containing a small amount of 1-chloro-1,3-butadiene can also be used as the chloroprene monomer in the present embodiment.

[0043] The chloroprene rubber according to an embodiment of the present invention preferably contains an unsaturated nitrile monomer unit. In the chloroprene rubber according to an embodiment of the present invention, when the rubber is set to 100% by mass, the content rate of the unsaturated nitrile monomer unit is preferably 25% by mass or less, more preferably less than 25% by mass, and further preferably 1% by mass or more and less than 25% by mass. The content rate of the unsaturated nitrile monomer unit in the chloroprene rubber according to an embodiment of the present invention is, for example, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24% by mass or less, less than 25% by mass, 25% by mass or less, and can also be within the range between any two values exemplified herein. By controlling the content rate of the unsaturated nitrile monomer unit in the rubber composition to 25% by mass or less, the water resistance and cold resistance of the sulfide of the rubber composition and the vulcanized molded article can be further improved. In addition, by making the content rate of the unsaturated nitrile monomer unit 1% by mass or more, the obtained rubber composition has sufficient oil resistance.

[0044] Examples of the unsaturated nitrile include acrylonitrile, methacrylonitrile, ethyl acrylonitrile, phenyl acrylonitrile, etc. The unsaturated nitrile can be used alone or in combination of two or more. From the viewpoints of easily obtaining excellent moldability and easily obtaining excellent breaking strength, breaking elongation, hardness, tear strength, and oil resistance of the vulcanized molded article, the unsaturated nitrile preferably contains acrylonitrile.

[0045] The content of the unsaturated nitrile monomer unit contained in the chloroprene rubber can be calculated from the content of nitrogen atoms in the chloroprene rubber. Specifically, the content of nitrogen atoms in 100 mg of the chloroprene rubber is measured using an elemental analyzer (SUMIGRAPH 220F: manufactured by Sumika Chemical Analysis Service, Ltd.), and the content of the structural unit derived from the unsaturated nitrile monomer can be calculated. The measurement of elemental analysis can be carried out under the following conditions. For example, the temperature of the electric furnace is set at 900 °C for the reaction furnace and 600 °C for the reduction furnace, the column temperature is set at 70 °C, the detector temperature is set at 100 °C, oxygen is used as the combustion gas and flows at a flow rate of 0.2 mL / min, and helium is used as the carrier gas and flows at a flow rate of 80 mL / min. Aspartic acid (10.52%) with a known nitrogen content can be used as a reference material to draw a calibration curve.

[0046] In the chloroprene rubber according to one embodiment of the present invention, when the rubber is 100% by mass, it preferably contains 60 to 100% by mass of chloroprene monomer units. The content rate of chloroprene monomer units in the rubber is, for example, 60, 65, 70, 75, 80, 85, 90, 95, 99, 100% by mass, and may also be within the range between any two values exemplified herein. By setting the content rate of chloroprene monomer units within the above numerical range, a rubber composition capable of providing a molded product with excellent balance of hardness, tensile strength, and cold resistance can be obtained.

[0047] The chloroprene rubber according to one embodiment of the present invention may also have monomer units other than the chloroprene monomer and the unsaturated nitrile monomer. As the monomer units other than the chloroprene monomer and the unsaturated nitrile monomer, there is no particular limitation as long as they are monomer units capable of copolymerizing with the chloroprene monomer or capable of copolymerizing with the chloroprene monomer and the unsaturated nitrile monomer. Examples of the monomer units include: (meth)acrylates ((meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, etc.), hydroxyalkyl (meth)acrylates (2-hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, etc.), 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, butadiene, isoprene, ethylene, styrene, sulfur, etc.

[0048] In one embodiment of the present invention, the chloroprene rubber, when the rubber is set to 100% by mass, may contain 0 to 20% by mass of monomer units other than chloroprene monomer and unsaturated nitrile monomer. The content rate of monomer units other than chloroprene monomer and unsaturated nitrile monomer in the rubber is, for example, 0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20% by mass, and may be within the range between any two values exemplified herein. By adjusting the copolymerization amount of monomers other than chloroprene monomer and unsaturated nitrile monomer to the above range, the copolymerization effect of these monomers can be exerted without impairing the properties of the obtained rubber composition.

[0049] In addition, the chloroprene rubber in one embodiment of the present invention may be composed of only chloroprene monomer units and unsaturated nitrile monomer units, or may be composed of only chloroprene monomer units.

[0050] In the rubber composition of the present invention, one kind of chloroprene rubber may be used alone or two or more kinds may be used in combination.

[0051] When the rubber composition of one embodiment of the present invention contains two or more kinds of chloroprene rubbers, it is preferable that the total content rate of unsaturated nitrile monomer units contained in the two or more kinds of chloroprene rubbers contained in the rubber composition is 25% by mass or less.

[0052] The chloroprene-based polymer contained in the chloroprene rubber of the present invention (for example, chloroprene homopolymer, chloroprene copolymer, etc.) may be a sulfur-modified chloroprene polymer, a mercaptan-modified chloroprene polymer, a xanthate-modified chloroprene polymer, a dithiocarbonate-based chloroprene polymer, a trithiocarbonate-based chloroprene polymer, a urethane-based chloroprene polymer, etc.

[0053] From the viewpoint of easily obtaining excellent hardness, tensile strength, and cold resistance with good balance, the weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (polydispersity of molecular weight, Mw / Mn) of the chloroprene rubber may be within the following ranges.

[0054] The weight average molecular weight of the chloroprene rubber may be 10×10 3 g / mol or more, 50×10 3 g / mol or more, 100×10 3 g / mol or more, 300×10 3 g / mol or more, 400×10 3 g / mol or more, or 450×10 3 g / mol or more. The weight average molecular weight of the chloroprene rubber may be 5000×10 3 g / mol or less, 3000×103 less than g / mol, 2000×10 3 less than g / mol, 1000×10 3 less than g / mol, 800×10 3 less than g / mol or 500×10 3 less than g / mol. From the above viewpoints, the weight-average molecular weight of the chloroprene rubber can be 10×10 3 ~5000×10 3 g / mol, 100×10 3 ~2000×10 3 g / mol or 300×10 3 ~1000×10 3 g / mol.

[0055] The number-average molecular weight of the chloroprene rubber can be 1×10 3 g / mol or more, 5×10 3 g / mol or more, 10×10 3 g / mol or more, 50×10 3 g / mol or more, 100×10 3 g / mol or more or 130×10 3 g / mol or more. The number-average molecular weight of the chloroprene rubber can be 1000×10 3 g / mol or less, 800×10 3 g / mol or less, 500×10 3 g / mol or less, 300×10 3 g / mol or less, 200×10 3 g / mol or less or 150×10 3 g / mol or less. From the above viewpoints, the number-average molecular weight of the chloroprene rubber can be 1×10 3 ~1000×10 3 g / mol, 10×10 3 ~500×10 3 g / mol or 50×10 3 ~300×10 3 g / mol.

[0056] The molecular weight distribution of the chloroprene rubber may be 1.0 or more, 1.5 or more, 2.0 or more, 2.5 or more, 3.0 or more, 3.2 or more, or 3.4 or more. The molecular weight distribution of the chloroprene rubber may be 10 or less, 8.0 or less, 5.0 or less, 4.0 or less, 3.8 or less, 3.5 or less, or 3.4 or less. From the above viewpoints, the molecular weight distribution of the chloroprene rubber may be 1.0 to 10, 2.0 to 5.0, or 2.5 to 4.0.

[0057] The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the chloroprene rubber can be measured by gel permeation chromatography (GPC) and converted to polystyrene equivalents, and can be specifically determined according to the methods described in the examples.

[0058] 1.2 Method for producing chloroprene rubber

[0059] The method for producing the chloroprene rubber of the present invention is not particularly limited, and can be obtained by a production method including an emulsion polymerization step of emulsion-polymerizing a raw material monomer containing a chloroprene monomer.

[0060] In the emulsion polymerization step of the embodiment of the present invention, an emulsifier, a dispersant, a catalyst, a chain transfer agent, etc. are appropriately used to emulsion-polymerize the chloroprene monomer or a monomer containing a chloroprene monomer and an unsaturated nitrile monomer. When the required final conversion rate is reached, a polymerization terminator is added to obtain a latex containing a chloroprene-based polymer containing chloroprene monomer units. Next, unreacted monomers can be removed from the polymerization liquid obtained in the emulsion polymerization step. The method is not particularly limited, and for example, it can be steam stripping. Subsequently, the pH is adjusted and conventional steps such as freezing and solidification, washing with water, and hot air drying are performed to obtain a chloroprene rubber containing a chloroprene-based polymer.

[0061] As the polymerization initiator used in the emulsion polymerization, there is no particular limitation, and known polymerization initiators commonly used in the emulsion polymerization of chloroprene can be used. Examples of the polymerization initiator include organic peroxides such as potassium persulfate, ammonium persulfate, sodium persulfate, hydrogen peroxide, and tert-butyl hydroperoxide.

[0062] The emulsifier used in the emulsion polymerization is not particularly limited, and known emulsifiers commonly used in the emulsion polymerization of chloroprene can be used. Emulsifiers include, for example, alkali metal salts of saturated or unsaturated fatty acids having 6 to 22 carbon atoms, alkali metal salts of rosin acid or disproportionated rosin acid (such as potassium rosin), alkali metal salts of formalin condensates of β-naphthalenesulfonic acid (such as sodium salt), etc.

[0063] There is no particular limitation on the molecular weight regulator used in emulsion polymerization, and known molecular weight regulators commonly used in the emulsion polymerization of chloroprene can be used. For example, there are mercaptan compounds, xanthate compounds, dithiocarbonate compounds, trithiocarbonate compounds, and urethane compounds. As the molecular weight regulator of the chloroprene rubber according to an embodiment of the present invention, xanthate compounds, dithiocarbonate compounds, trithiocarbonate compounds, and urethane compounds can be preferably used.

[0064] There is no particular limitation on the polymerization temperature and the final conversion rate of the monomer. The polymerization temperature can be, for example, 0 to 50 °C or 10 to 50 °C. Polymerization can be carried out so that the final conversion rate of the monomer is in the range of 40 to 95% by mass. To adjust the final conversion rate, when the desired conversion rate is reached, a polymerization terminator that stops the polymerization reaction can be added to terminate the polymerization reaction.

[0065] There is no particular limitation on the polymerization terminator, and known polymerization terminators commonly used in the emulsion polymerization of chloroprene can be used. Examples of the polymerization terminator include phenothiazine (thiodiphenylamine), 4-tert-butylcatechol, 2,2-methylenebis-4-methyl-6-tert-butylphenol, etc.

[0066] The chloroprene rubber according to an embodiment of the present invention can be obtained, for example, by removing unreacted monomers by steam stripping method, adjusting the pH value of the above latex, and then through conventional processes such as freezing and solidifying, washing with water, and hot air drying.

[0067] Chloroprene rubbers are classified into mercaptan-modified type, xanthate-modified type, sulfur-modified type, dithiocarbonate type, trithiocarbonate type, and urethane type according to the type of molecular weight regulator.

[0068] 1.3 3-Methyl-thiazolidine-2-thione, Compound A, and Compound B

[0069] The rubber composition according to the present invention satisfies at least one of the following conditions i) and ii).

[0070] Condition i) The rubber composition contains 3-methyl-thiazolidine-2-thione, and contains 0.1 to 3.0 parts by mass of 3-methyl-thiazolidine-2-thione relative to 100 parts by mass of the chloroprene rubber.

[0071] The rubber composition described in condition ii) contains compound A and compound B. Compound A is at least one selected from thiourea compounds, 3-methyl-thiazolidine-2-thione, and bis(5-mercapto-1,3,4-thiadiazol-2-yl) disulfide. Compound B is at least one selected from thiuram compounds, sulfenamide compounds, thiazole compounds, guanidine compounds, benzimidazole compounds, N-phenyl-N-(trichloromethylthio) benzenesulfonamide, and diazabicycloundecene compounds. With respect to 100 parts by mass of the chloroprene rubber, the rubber composition contains 0.1 to 3.0 parts by mass of compound A and 0.01 to 3.0 parts by mass of compound B.

[0072] Conventionally, when silica as a filler is used in combination with a vulcanization accelerator that provides sulfur as a crosslinking agent in a rubber composition containing a chloroprene rubber, vulcanization may not proceed sufficiently. Here, the reason why vulcanization cannot proceed sufficiently when silica and a vulcanization accelerator are combined is presumed to be that the surface of silica is covered with silanol groups and becomes acidic, or the vulcanization accelerator is adsorbed on the surface of silica, inhibiting vulcanization. As a result of intensive studies by the present inventors, it has been found that in a chloroprene rubber composition containing silica, by satisfying the above-mentioned condition i) and / or ii), vulcanization can proceed sufficiently, and a rubber composition capable of obtaining a vulcanizate and a vulcanized molded article having excellent abrasion resistance can be produced, thus completing the present invention. According to one embodiment of the present invention, vulcanization proceeds sufficiently, so that a vulcanizate and a vulcanized molded article having excellent abrasion resistance, tensile properties such as tensile strength at cut and elongation at cut, and / or excellent compression set resistance can be obtained. In addition, according to the present invention, by adjusting the types and amounts of the ingredients of the rubber composition, particularly by adjusting the amount of a filler such as silica, the hardness of the obtained vulcanizate and vulcanized molded article can be freely adjusted, and vulcanizates and vulcanized molded articles having various hardnesses, excellent abrasion resistance, tensile properties, and / or excellent compression set resistance can be obtained according to the use and the use environment. For example, vulcanizates and vulcanized molded articles having a relatively low hardness, excellent abrasion resistance, tensile properties, and / or excellent compression set resistance can be designed.

[0073] When the rubber composition of the present invention satisfies condition i), the rubber composition contains 3-methyl-thiazolidine-2-thione (the following formula). At this time, in the rubber composition, 0.1 to 3.0 parts by mass of 3-methyl-thiazolidine-2-thione is contained relative to 100 parts by mass of the chloroprene rubber. The content rate of 3-methyl-thiazolidine-2-thione relative to 100 parts by mass of the chloroprene rubber is, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0 parts by mass, and may also be within the range between any two values exemplified herein.

[0074] [Chemical formula 1]

[0075]

[0076] In addition, when the rubber composition contains 3-methyl-thiazolidine-2-thione, the rubber composition may not contain the following compound B. For example, relative to 100 parts by mass of the chloroprene rubber, 3.0 parts by mass or less of compound B may be contained.

[0077] When the rubber composition of the present invention satisfies condition ii), the rubber composition contains compound A and compound B. Compound A is at least one selected from the group consisting of thiourea compounds, 3-methyl-thiazolidine-2-thione, and bis(5-mercapto-1,3,4-thiadiazol-2-yl) disulfide.

[0078] Examples of the thiourea compound may include compounds having a thiourea structure. Examples of the thiourea compound may include the compounds represented by the following formula.

[0079] [Chemical formula 2]

[0080]

[0081] In the above formula, R 11 ~R 14 may each independently be hydrogen or an organic group, may be hydrogen or a hydrocarbon group, and the hydrocarbon group may be an alkyl group or an aryl group. Examples of the thiourea compound include ethylene thiourea, diethyl thiourea (N,N'-diethyl thiourea), trimethyl thiourea, diphenyl thiourea (N,N'-diphenyl thiourea), or 1,3-trimethylene 2-thiourea, etc.

[0082] Bis(5-mercapto-1,3,4-thiadiazol-2-yl) disulfide is represented by the following formula.

[0083] [Chemical formula 3]

[0084]

[0085] Compound B is at least one selected from thiuram compounds, sulfonamide compounds, thiazole compounds, guanidine compounds, benzimidazole compounds, N-phenyl-N-(trichloromethylthio)benzenesulfonamide or diazabicycloundecene compounds (excluding the compounds listed for Compound A). Compound B is preferably at least one selected from thiuram compounds, thiazole compounds, guanidine compounds, benzimidazole compounds, N-phenyl-N-(trichloromethylthio)benzenesulfonamide or diazabicycloundecene compounds (excluding the compounds listed for Compound A).

[0086] The thiuram compound contains a compound having one or more structures represented by the following formula.

[0087] [Chemical Formula 4]

[0088]

[0089] In the above formula, R 21 , R 22 , R 23 , R 24 can each independently be an organic group, preferably a hydrocarbon group. The hydrocarbon group can be an alkyl group having 1 to 12 carbon atoms or a cycloalkyl group having 1 to 12 carbon atoms. R 21 and R 22 as well as R 23 and R 24 can be connected to each other to form a cyclic structure (such as a cycloalkyl group). n can be an integer of 1 or more, can be 1 to 4, preferably 1 or 2, more preferably 2.

[0090] Examples of the thiuram compound include tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide, tetrabutylthiuram disulfide, tetra(2-ethylhexyl)thiuram disulfide, tetramethylthiuram monosulfide, bis(pentamethylene)tetrasulfide, etc.

[0091] Examples of the sulfonamide compound include a compound containing a sulfonamide structure. Examples of the sulfonamide compound include N-cyclohexyl-2-benzothiazolesulfonamide, N-oxydiethylene-2-benzothiazolesulfonamide, etc. The sulfonamide compound can be a compound having a sulfonamide structure and a thiazole skeleton.

[0092] As thiazole compounds, compounds having a thiazole skeleton (except for the compounds listed as Compound A) can be cited, and those having a benzothiazole skeleton are more preferable. Examples of thiazole compounds include 2-mercaptobenzothiazole, di-2-benzothiazole disulfide, zinc salt of 2-mercaptobenzothiazole, cyclohexylamine salt of 2-mercaptobenzothiazole, 2-(4'-morpholinodithio)benzothiazole, N-cyclohexylbenzothiazole-2-sulfenamide, N-cyclohexyl-2-benzothiazolesulfenamide, N-oxydiethylene-2-benzothiazolesulfenamide, etc. The thiazole compound may be a compound having a thiazole skeleton and a sulfenamide structure.

[0093] Guanidine compounds can be cited as compounds having a guanidine skeleton. Examples of guanidine compounds include 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, di-o-tolylguanidine salt of catechol borate, etc.

[0094] As benzimidazole compounds, compounds containing a benzimidazole skeleton can be cited. Examples of benzimidazole compounds include 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, and zinc salt of 2-mercaptomethylbenzimidazole.

[0095] N-phenyl-N-(trichloromethylthio)benzenesulfonamide is represented by the following formula.

[0096] [Chemical formula 5]

[0097]

[0098] Examples of diazabicycloundecene compounds include compounds having a diazabicycloundecene skeleton. Examples of diazabicycloundecene compounds include 1,8-diazabicyclo[5.4.0]undecene-7.

[0099] In the rubber composition, 0.1 to 3.0 parts by mass of Compound A is contained with respect to 100 parts by mass of the chloroprene rubber. With respect to 100 parts by mass of the chloroprene rubber, the content of Compound A is, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0 parts by mass, and may also be within the range between any two values exemplified here.

[0100] In the rubber composition, 0.01 to 3.0 parts by mass of Compound B is contained relative to 100 parts by mass of the chloroprene rubber. The content of Compound B relative to 100 parts by mass of the chloroprene rubber is, for example, 0.01, 0.02, 0.03, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0 parts by mass, and can also be within the range between any two values exemplified herein.

[0101] When the rubber composition contains Compound A and Compound B, the rubber composition preferably contains 10 to 100 parts by mass of Compound B relative to 100 parts by mass of Compound A. The content of Compound B relative to 100 parts by mass of Compound A is, for example, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 parts by mass, and can also be within the range between any two values exemplified herein.

[0102] As Compound A, the above-mentioned compound can be used alone or two or more compounds can be used in combination. As Compound B, the above-mentioned compound can be used alone or two or more compounds can be used in combination. When the rubber composition contains 3-methyl-thiazolidine-2-thione and Compound B, the rubber composition preferably contains 0.1 to 3.0 parts by mass of 3-methyl-thiazolidine-2-thione and 0.1 to 3.0 parts by mass of Compound B. When the rubber composition contains 3-methyl-thiazolidine-2-thione, Compound A other than 3-methyl-thiazolidine-2-thione and Compound B, in the rubber composition, the total content of Compound A including 3-methyl-thiazolidine-2-thione is preferably 0.1 to 3.0 parts by mass, and more preferably the content of Compound B is 0.1 to 3.0 parts by mass.

[0103] The rubber composition may further contain a compound other than 3-methyl-thiazolidine-2-thione, Compound A, and Compound B, which can be used as a vulcanizing agent and / or vulcanization accelerator for chloroprene rubber. With respect to 100 parts by mass of the chloroprene rubber, the content of the vulcanizing agent and vulcanization accelerator other than 3-methyl-thiazolidine-2-thione, Compound A, and Compound B may be, for example, 0.01, 0.02, 0.03, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0 parts by mass, or may also be within the range between any two values exemplified herein. The rubber composition according to one embodiment of the present invention may not contain a vulcanizing agent and vulcanization accelerator other than 3-methyl-thiazolidine-2-thione, Compound A, and Compound B. Examples of the vulcanizing agent and vulcanization accelerator other than 3-methyl-thiazolidine-2-thione, Compound A, and Compound B include sulfur, a vulcanization accelerator of dithiocarbamate type, or a vulcanization accelerator of xanthate type.

[0104] The rubber composition according to one embodiment of the present invention may further contain an organic peroxide. When using an organic peroxide, with respect to 100 parts by mass of the chloroprene rubber, the content of the organic peroxide may be 3.0 parts by mass or less. The addition amount of the organic peroxide is, for example, 0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0 parts by mass, or may also be within the range between any two values exemplified herein. The rubber composition according to one embodiment of the present invention may not contain an organic peroxide.

[0105] 1.4 silica

[0106] Silica is added to the rubber composition as a filler, and its type is not particularly limited. As silica, for example, wet silica (hydrated silicic acid), dry silica (anhydrous silicic acid), and colloidal silica can be used, and wet silica is preferably used.

[0107] From the viewpoints of processability and the physical properties obtained, silica with a BET specific surface area of 50 to 300 m 2 / g is preferably used. The BET specific surface area is, for example, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300 m 2 / g, or may also be within the range between any two values exemplified herein.

[0108] The addition amount of silica is 5 to 80 parts by mass with respect to 100 parts by mass of the chloroprene rubber. The content of silica with respect to 100 parts by mass of the chloroprene rubber is, for example, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, and may also be within the range between any two values exemplified herein.

[0109] The rubber composition in one embodiment of the present invention may also contain fillers other than silica. Examples of fillers other than silica include furnace black such as SAF, ISAF, HAF, EPC, XCF, FEF, GPF, HMF, SRF, modified carbon black such as hydrophilic carbon black, channel black, lampblack, pyrolytic carbon black such as FT, MT, acetylene black, Ketjen black, clay, talc, and calcium carbonate.

[0110] When the filler contained in the rubber composition is set to 100% by mass, the rubber composition according to one embodiment of the present invention preferably contains 50% by mass or more of silica. When the filler contained in the rubber composition is 100% by mass, the content of silica is, for example, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100% by mass, and may also be within the range between any two values exemplified herein. The rubber composition according to one embodiment of the present invention may not contain fillers other than silica.

[0111] 1.5 Silane Coupling Agent

[0112] The rubber composition in one embodiment of the present invention contains a silane coupling agent. In the rubber composition in one embodiment of the present invention, the silane coupling agent is not particularly limited, and a silane coupling agent used in commercially available rubber compositions can be used. For example, there are vinyl-based coupling agents, epoxy-based coupling agents, styryl-based coupling agents, methacrylic acid-based coupling agents, acrylic acid-based coupling agents, amino-based coupling agents, polysulfide-based coupling agents, and mercapto-based coupling agents. From the viewpoint of good reactivity between the silane coupling agent and the chloroprene rubber, it is preferable to contain a silane coupling agent having an amino group in its structure, that is, it is preferable to contain an amino-based coupling agent.

[0113] Specifically, examples of the silane coupling agent include 3-methacryloxypropyltrimethoxysilane, bis-(3-triethoxysilylpropyl)tetrasulfide, bis-(3-trimethoxysilylpropyl)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-hexanoylthioethyltriethoxysilane, 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-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, 3-trimethoxysilylpropylbenzothiazoletetrasulfide, 3-trimethoxysilylpropylmethacryloylmonosulfide, methyltrimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, dimethyldimethoxysilane, trimethylethoxysilane, trimethylmethoxysilane, isobutyltrimethoxysilane, n-decyltrimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, hexyltrimethoxysilane, octadecylmethyldimethoxysilane, octadecyltrimethoxysilane, methyltrichlorosilane, dimethyldichlorosilane, triphenylchlorosilane, heptadecafluorodecylmethyldichlorosilane, heptadecafluoro-trichlorosilane, triethylchlorosilane, etc. Among them, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, and N-2-(aminoethyl)-3-aminopropyltrimethoxysilane are preferred.

[0114] According to a rubber composition in an embodiment of the present invention, with respect to 100 parts by mass of silica contained in the rubber composition, 0.5 to 15 parts by mass of a silane coupling agent can be contained, for example, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 parts by mass, and can also be within the range between any two values exemplified herein. These can be used alone or in combination of two or more. By including the above silane coupling agent and setting the content rate of the silane coupling agent within the above numerical range, the dispersibility of the silica filler in the rubber can be improved, the reinforcing effect between the rubber and the silica filler can be enhanced, and the generation of scorching can be suppressed.

[0115] 1.6 hydrate

[0116] The hydrate preferably has a structure that releases H2O during mixing and vulcanization processes. More preferably, it is a hydrate that releases H2O in the temperature range of 100°C to 250°C, and further preferably, it is a hydrate that releases H2O in the temperature range of 100°C to 150°C. This promotes the reaction between the silane coupling agent and silica, thereby enabling good physical properties and good vulcanization speed to be obtained.

[0117] There is no particular limitation on the hydrate, and hydrates used in commercially available rubber compositions can be used. For example, hydrotalcite compounds, hydrated salts, and metal hydroxides represented by the following chemical formula (1) can be used.

[0118] [M 2+ 1-x M 3+ x (OH)2] x+ [A n-x / n ·mH2O] x- (1)

[0119] In the above formula (1),

[0120] M 2+ : at least one divalent metal ion selected from Mg 2+ , Zn 2+ and the like;

[0121] M 3+ : at least one trivalent metal ion selected from Al 3+ , Fe 3+ and the like;

[0122] A n- : at least one n-valent anion selected from CO3 2- , Cl ― , NO3 - and the like;

[0123] X: 0 < X ≤ 0.33.

[0124] Examples of the hydrotalcite compound include: Mg 4.3 Al2(OH) 12.6 CO3·3.5H2O, Mg3ZnAl2(OH) 12 CO3·3H2O, Mg 4.5 Al2(OH) 13 CO3·3.5H2O, Mg 4.5 Al2(OH) 13 CO3, Mg4Al2(OH) 12 CO3·3.5H2O, Mg6Al2(OH) 16 CO3·4H2O, Mg5Al2(OH) 14 CO3·4H2O, Mg3Al2(OH) 10 CO3·1.7H2O, etc., and particularly preferably Mg 4.3 Al2(OH) 12.6 CO3·3.5H2O, Mg3ZnAl2(OH) 12 CO3·3H2O.

[0125] Examples of the hydrated salt include: Al2O3·3H2O, Al2O3·H2O, Na2SO4·10H2O, CaSO4·2H2O, NaHCO3·Na2CO3·2H2O, MgSO4·7H2O, etc., and particularly preferably Al2O3·3H2O.

[0126] Examples of the hydroxide include: Ca(OH)2, Al(OH)3, Mg(OH)2, Zn(OH)2, etc., and particularly preferably Mg(OH)2.

[0127] Relative to 100 parts by mass of the chloroprene rubber, the content of the hydrate is 0.5 part by mass or more and less than 20 parts by mass, preferably 1 part by mass or more and less than 20 parts by mass, and more preferably 4 to 10 parts by mass. The addition amount of the hydrate can be, for example, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 parts by mass, less than 20 parts by mass, or also within the range between any two values exemplified herein. By using the hydrate within this range, a rubber composition having excellent abrasion resistance can be obtained.

[0128] 1.7 Acid acceptor

[0129] The rubber composition of an embodiment of the present invention may contain an acid acceptor. Examples of the acid acceptor include metal oxides, and examples of the metal oxides include zinc oxide, magnesium oxide, lead oxide, red lead, ferric oxide, titanium dioxide, calcium oxide, etc. The metal oxide preferably contains zinc oxide, and more preferably is zinc oxide.

[0130] 1.8 Plasticizer

[0131] As the plasticizer, any plasticizer compatible with the chloroprene rubber can be used without particular limitation. For example, vegetable oils such as rapeseed oil, phthalate plasticizers, DOS (dioctyl sebacate), DBS (dibutyl sebacate), DOA (dioctyl adipate), ester plasticizers, ether ester plasticizers, thioether plasticizers, aromatic oils, naphthenic oils, etc. can be cited. These can be used alone or in combination of two or more. With respect to 100 parts by mass of the chloroprene rubber contained in the rubber composition, the addition amount of the plasticizer can be 0 part by mass to 50 parts by mass, for example, 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50 parts by mass, and can also be within the range between any two values exemplified here.

[0132] 1.9 Lubricant, processing aid

[0133] The rubber composition of the present invention may further contain a lubricant and / or a processing aid. The addition of the lubricant and the processing aid is mainly to improve the processing performance, for example, to make the rubber composition easier to peel off from rolls, molding dies, screws of extruders, etc. The lubricant and the processing aid include, for example, fatty acids such as stearic acid, paraffin processing aids such as polyethylene, fatty acid amides, petrolatum, ointments, etc. These can be used alone or in combination of two or more. The rubber composition of the present invention, with respect to 100 parts by mass of the chloroprene rubber contained in the rubber composition, may contain 1 to 15 parts by mass of the lubricant and the processing aid, or may contain 1 to 10 parts by mass of the lubricant and the processing aid. The content of the lubricant and the processing aid is, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 parts by mass, and can also be within the range between any two values exemplified here.

[0134] 1.10 Others

[0135] In addition to the above components, the rubber composition of the present invention may also contain anti-aging agents, antioxidants, flame retardants, vulcanization retarders, etc. within the range that does not impair the effects of the present invention. Examples of anti-aging agents and antioxidants include anti-ozone aging agents, phenolic anti-aging agents, amine anti-aging agents, acrylate anti-aging agents, waxes, phosphorus anti-aging agents, etc. Examples of amine antioxidants include 4,4'-bis(α,α-dimethylbenzyl)diphenylamine. In the rubber composition of the present invention, based on 100 parts by mass of the chloroprene rubber contained in the rubber composition, a total of 0.1 to 10 parts by mass of anti-aging agents and antioxidants can be contained.

[0136] 2. Method for manufacturing rubber composition

[0137] The rubber composition according to one embodiment of the present invention is obtained by kneading a chloroprene rubber and other required components at a temperature below the vulcanization temperature. As a device for kneading raw material components, for example, conventionally known kneaders, Banbury mixers, kneaders, open rolls, etc. can be cited.

[0138] 3. Characteristics of rubber composition

[0139] The rubber composition according to one embodiment of the present invention preferably has the following characteristics.

[0140] <Hardness of vulcanized molded body>

[0141] For the rubber composition according to one embodiment of the present invention, the durometer hardness (Type A) specified in JIS K6253 of the vulcanized molded body of the rubber composition can be adjusted to 30 to 90. The durometer hardness (Type A) of the vulcanized molded body of the rubber composition is, for example, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, and can also be within the range between any two values exemplified herein. By adjusting the types and amounts of the ingredients of the rubber composition, especially by adjusting the amount of the filler (especially silica) blended, the durometer hardness (Type A) of the vulcanized molded body of the rubber composition can be controlled. The durometer hardness (Type A) of the vulcanized molded body of the rubber composition can be determined by the method described in the examples. According to the present invention, even when the hardness is adjusted to a lower level, a vulcanizate and a vulcanized molded body having excellent abrasion resistance, tensile properties, and compression set resistance can be obtained.

[0142] <Tensile properties of vulcanized molded body>

[0143] Regarding the rubber composition according to an embodiment of the present invention, preferably, the vulcanized molded body of the rubber composition has a tensile strength at break based on JIS K 6251 of 16 MPa or more. The tensile strength at break of the vulcanized molded body of the rubber composition is, for example, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40 MPa, and may also be within the range between any two values exemplified herein. According to an embodiment of the present invention, while containing silica, sufficient vulcanization can be carried out, and a vulcanizate and a vulcanized molded body having sufficient tensile strength can be obtained.

[0144] Regarding the rubber composition according to an embodiment of the present invention, the elongation at break of the vulcanized molded body of the rubber composition based on JIS K6251 may be 300 to 1200%. The elongation at break of the vulcanized molded body of the rubber composition is, for example, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200%, and may also be within the range between any two values exemplified herein.

[0145] The tensile strength at cut and the elongation at cut of the vulcanized molded body of the rubber composition can be determined by the method described in the examples.

[0146] <Compression set resistance>

[0147] According to the rubber composition according to an embodiment of the present invention, when the vulcanized molded body of the rubber composition is tested under the test conditions of 70 °C for 24 hours based on JIS K6262:2013, the compression set rate can reach 35% or less. The compression set rate is, for example, 0, 5, 10, 15, 20, 25, 30, 35%, and may also be within the range between any two values exemplified herein. The compression set rate of the vulcanized molded body of the rubber composition can be determined by the method described in the examples.

[0148] <Abrasion resistance>

[0149] According to the rubber composition according to an embodiment of the present invention, preferably, the wear volume ΔV based on the Akron abrasion test (1000 abrasions) according to JIS K6264-2:2019 is 50 mm 3 or less. The wear volume ΔV is, for example, 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50 mm 3 , and may also be within the range between any two values exemplified herein. The wear volume ΔV of the vulcanized molded body of the rubber composition can be determined by the method described in the examples.

[0150] 4. Unvulcanized molded body, vulcanizate and vulcanized molded body

[0151] The unvulcanized molded body of the present embodiment uses the rubber composition of the present embodiment and is a molded body (molded product) of the rubber composition (in an unvulcanized state) of the present embodiment. The manufacturing method of the unvulcanized molded body of the present embodiment includes a step of molding the rubber composition (in an unvulcanized state) of the present embodiment. The unvulcanized molded body of the present embodiment is formed from the rubber composition (in an unvulcanized state) of the present embodiment.

[0152] The sulfide of the present embodiment is the sulfide of the rubber composition of the present embodiment. The manufacturing method of the sulfide of the present embodiment includes a step of vulcanizing the rubber composition of the present embodiment.

[0153] The vulcanized molded body of the present embodiment is the vulcanized molded body of the rubber composition of the present embodiment. The vulcanized molded body of the present embodiment is formed using the sulfide of the present embodiment and is a molded body (molded product) of the sulfide of the present embodiment. The vulcanized molded body of the present embodiment is formed from the sulfide of the present embodiment.

[0154] The vulcanized molded body of the present embodiment can be obtained by molding the sulfide obtained by vulcanizing the rubber composition (in an unvulcanized state) of the present embodiment, or by vulcanizing the molded body obtained by molding the rubber composition (in an unvulcanized state) of the present embodiment. The vulcanized molded body of the present embodiment can be obtained by vulcanizing after or during the molding of the rubber composition of the present embodiment. The manufacturing method of the vulcanized molded body of the present embodiment includes a step of molding the sulfide of the present embodiment or a step of vulcanizing the unvulcanized molded body of the present embodiment.

[0155] The unvulcanized molded body, sulfide, and vulcanized molded body of the present embodiment can be used as rubber components in various industrial fields such as buildings, structures, ships, railways, coal mines, and automobiles. The rubber composition of the present invention has excellent abrasion resistance, so it can be used as various components that require these properties. The rubber composition, sulfide, and vulcanized molded body of one embodiment of the present invention can be used as rubber components in various industrial fields such as buildings, structures, ships, railways, coal mines, and automobiles, and can be used as rubber components for automobiles (such as automotive seals), hose materials, rubber molds, gaskets, rubber rollers, industrial cables, industrial conveyor belts, sponges, etc. In particular, it can be used as components that require abrasion resistance. For example, the sulfide and vulcanized molded body of one embodiment of the present invention are suitable for use as rubber rollers. Another example is that the sulfide and vulcanized molded body of one embodiment of the present invention are suitable for use as rubber rollers for embossing that particularly require abrasion resistance.

[0156] (Automotive rubber components)

[0157] Automobile rubber parts include gaskets, oil seals, and sealing gaskets, etc. They are components that prevent the leakage of liquids and gases in machines and equipment, and prevent sundries and foreign objects such as rainwater and dust from entering the interior of machines and equipment. Specifically, there are gaskets used for fixed purposes and oil seals and sealing gaskets for moving parts and movable parts. For gaskets that fix the sealing part with bolts, etc., soft gaskets such as O-rings or rubber sheets use various materials according to the purpose. In addition, sealing gaskets are also used for rotating parts such as pumps, motor shafts, movable parts like valves, reciprocating parts like pistons, connecting parts of couplings, and water-stop parts of faucets, etc. The rubber composition of the present invention can improve wear resistance. Thus, seals that can be used in harsh environments can be manufactured, which is difficult to achieve with conventional rubber compositions.

[0158] (Hose material)

[0159] Hose material is a bendable tube. Specific examples include water supply hoses, oil supply hoses, gas supply hoses, steam hoses, high and low pressure hydraulic hoses, etc. The rubber composition of the present invention can improve the wear resistance of hose material while maintaining the processing performance of the unvulcanized material. Thus, hose materials that can be used in harsh environments can be manufactured, which is difficult to achieve with conventional rubber compositions.

[0160] (Rubber mold)

[0161] Rubber molds include anti-vibration rubbers, shock-absorbing materials, protective covers, etc. Anti-vibration rubbers and shock-absorbing materials are rubbers that prevent the transmission and diffusion of vibration. Specific examples include torsional shock absorbers, engine mounts, muffler hangers, etc. that absorb vibration and prevent noise during the operation of engines for automobiles and various vehicles. The rubber composition of the present invention can improve the wear resistance of anti-vibration rubbers and shock-absorbing materials. Thus, anti-vibration rubbers and shock-absorbing materials that can be used in harsh environments can be manufactured, which is difficult to achieve with conventional rubber compositions.

[0162] In addition, the protective cover is a bellows-shaped component whose outer diameter gradually increases from one end face to the other end. Specifically, there are protective covers for constant velocity joint covers to protect drive components such as automobile drive systems, protective covers for ball joint covers (dust boot sleeves), protective covers for rack and pinions, etc. The rubber composition of the present invention can improve wear resistance. Thus, protective covers that can be used in harsh environments can be manufactured, which is difficult to achieve with conventional rubber compositions.

[0163] (Gaskets, etc.)

[0164] Washers, oil seals, and gaskets are components that prevent leakage of liquids and gases in machines and equipment, as well as the intrusion of garbage and foreign objects such as rainwater or dust into the interior. Specifically, there are washers for fixed applications, oil seals, and gaskets used in moving parts and movable parts. For washers that fix the sealed part with bolts, etc., soft washers such as O-rings and rubber sheets use various materials according to the application. And gaskets are used in pumps, motor shafts, rotating parts such as the movable parts of valves, reciprocating parts such as pistons, connecting parts of couplings, water-stopping parts of faucets, etc. The rubber composition of the present invention can improve the wear resistance of these components. Thus, seals that can be used in harsh environments can be manufactured, which is difficult to achieve with conventional rubber compositions.

[0165] (Rubber roller)

[0166] A rubber roller is made by bonding rubber to a metal core such as an iron core. Generally, it is made by spirally winding a rubber sheet around a metal iron core. Rubber rollers use rubber materials such as NBR, EPDM, and CR according to the characteristics required for various applications such as papermaking, various metal manufacturing, film manufacturing, printing, general industrial use, agricultural machinery use such as rice milling, and food processing use. CR has good mechanical strength to withstand the friction when handling objects, so it is widely used in rubber rollers. In addition, there is a problem that rubber rollers for handling heavy objects are deformed due to the load, and improvements are being sought. The rubber composition of the present invention can improve the wear resistance of rubber rollers. Thus, a rubber roller for embossing with excellent wear resistance can be manufactured, which is difficult to achieve with conventional rubber compositions.

[0167] (Industrial cable)

[0168] Industrial cables are linear components for transmitting electrical and optical signals. They are made by coating a good conductor such as copper or copper alloy or an optical fiber with an insulating coating, and a wide variety of industrial cables can be manufactured according to their structure and installation location. The rubber composition of the present invention can improve the wear resistance of industrial cables. Thus, industrial cables that can be used in harsh environments can be manufactured, which is difficult to achieve with conventional rubber compositions.

[0169] (Industrial conveyor belt)

[0170] Industrial conveyor belts are available in rubber, resin, and metal, and are selected according to a variety of usage methods. Among them, rubber conveyor belts are widely used because of their low price, but when used in environments where there is a lot of friction and collision with the transported objects, phenomena such as damage caused by deterioration occur. The rubber composition of the present invention can improve the wear resistance of industrial conveyor belts. Thus, industrial conveyor belts that can be used in harsh environments can be manufactured, which is difficult to achieve with conventional rubber compositions.

[0171] (Sponge)

[0172] A sponge is a porous material with countless tiny pores inside, and it is specifically used in shock-proof components, sponge seals, diving suits, shoes, etc. The rubber composition of the present invention can improve the acid resistance and water resistance of the sponge. In addition, due to the use of chloroprene rubber, the flame retardancy of the sponge can also be improved. Thus, a sponge that can be used in harsh environments (which is difficult to achieve with conventional rubber compositions) can be manufactured, and a sponge with excellent flame retardancy can be manufactured. Moreover, the hardness of the obtained sponge can be appropriately adjusted by adjusting the content of the foaming agent, etc.

[0173] As the molding methods of the rubber composition (uncured state) and the vulcanizate of the present embodiment, compression molding, extrusion molding, calendering molding, etc. can be cited. The vulcanization temperature of the rubber composition can be appropriately set according to the composition of the rubber composition, and can be 140 - 220 °C, or can also be 160 - 190 °C. The vulcanization time of the vulcanized rubber composition can be appropriately set according to the composition of the rubber composition, the shape of the uncured molded body, etc.

[0174] <The Second Viewpoint>

[0175] 1. Rubber composition

[0176] The rubber composition of an embodiment of the present invention is a rubber composition containing chloroprene rubber, silica, silane coupling agent, and hydrate. The rubber composition is pressure-vulcanized at 160 °C for 40 minutes to obtain a vulcanized molded body. In the Akron abrasion test of the vulcanized molded body based on JIS K 6264-2, the abrasion volume ΔV when rotating 1000 times is 50 mm 3 or less.

[0177] According to the rubber composition of the second viewpoint, in the rubber composition containing chloroprene rubber, silica, silane coupling agent, and hydrate, by adjusting the abrasion volume ΔV of the vulcanized molded body of the rubber composition to 50 mm 3 or less, a rubber composition capable of obtaining a vulcanized molded body with excellent abrasion resistance, tensile properties, and compression set resistance can be made.

[0178] The following mainly explains the differences from the first viewpoint.

[0179] Regarding 1.1 Chloroprene rubber, the manufacturing method of 1.2 Chloroprene rubber is the same as that of the first viewpoint.

[0180] 1.3 3-Methyl-thiazolidine-2-thione, Compound A and Compound B

[0181] The rubber composition according to the second aspect may contain at least one of 3-methyl-thiazolidine-2-thione, Compound A, and Compound B. Compound A is at least one selected from the group consisting of thiourea compounds, 3-methyl-thiazolidine-2-thione, and bis(5-mercapto-1,3,4-thiadiazol-2-yl) disulfide, and Compound B is at least one selected from the group consisting of thiuram compounds, sulfenamide compounds, thiazole compounds, guanidine compounds, benzimidazole compounds, N-phenyl-N-(trichloromethylthio)benzenesulfonamide, and diazabicycloundecene compounds.

[0182] By blending the above compounds into a chloroprene rubber composition containing silica, vulcanization can be carried out more sufficiently, thereby producing a rubber composition capable of obtaining a vulcanizate and a vulcanized molded article having excellent abrasion resistance.

[0183] In the rubber composition according to the second aspect, the total content of 3-methyl-thiazolidine-2-thione, Compound A, and Compound B may be 0.1 to 3.0 parts by mass relative to 100 parts by mass of the chloroprene rubber. Specifically, for example, the total content of 3-methyl-thiazolidine-2-thione, Compound A, and Compound B relative to 100 parts by mass of the chloroprene rubber is 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0 parts by mass, and may also be within the range between any two values exemplified herein.

[0184] In the rubber composition according to the second aspect, the content of 3-methyl-thiazolidine-2-thione may be 0 to 3.0 parts by mass relative to 100 parts by mass of the chloroprene rubber. Specifically, for example, it is 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0 parts by mass, and may also be within the range between any two values exemplified herein.

[0185] In the rubber composition according to the second aspect, the content of Compound A may be 0 to 3.0 parts by mass relative to 100 parts by mass of the chloroprene rubber. Specific examples are 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0 parts by mass, and may also be within the range between any two of the values exemplified herein.

[0186] In the rubber composition according to the second aspect, the content of Compound B may be 0 to 3.0 parts by mass relative to 100 parts by mass of the chloroprene rubber. Specific examples are 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0 parts by mass, and may also be within the range between any two of the values exemplified herein.

[0187] Specific examples of 3-methyl-thiazolidine-2-thione, Compound A, and Compound B are the same as those in the first aspect.

[0188] The rubber composition according to the second aspect more preferably satisfies at least one of the following conditions i) and ii).

[0189] Condition i): The rubber composition contains 3-methyl-thiazolidine-2-thione, and contains 0.1 to 3.0 parts by mass of 3-methyl-thiazolidine-2-thione relative to 100 parts by mass of the chloroprene rubber.

[0190] Condition ii): The rubber composition contains Compound A and Compound B, where Compound A is at least one selected from the group consisting of thiourea compounds, 3-methyl-thiazolidine-2-thione, and bis(5-mercapto-1,3,4-thiadiazol-2-yl) disulfide, Compound B is at least one selected from the group consisting of thiuram compounds, sulfenamide compounds, thiazole compounds, guanidine compounds, benzimidazole compounds, N-phenyl-N-(trichloromethylthio) benzenesulfonamide, and diazabicycloundecene compounds, and the rubber composition contains 0.1 to 3.0 parts by mass of Compound A and 0.01 to 3.0 parts by mass of Compound B relative to 100 parts by mass of the chloroprene rubber.

[0191] Regarding conditions i) and / or ii), they are the same as those in the first aspect.

[0192] Regarding 1.4 silica, 1.5 silane coupling agent, 1.6 hydrate, 1.7 acid acceptor, 1.8 plasticizer, 1.9 lubricant, processing aid, 1.10 other components, the manufacturing method of the rubber composition is the same as in the first aspect.

[0193] 3. Characteristics of the rubber composition

[0194] <Abrasion resistance>

[0195] For the rubber composition according to the second aspect, when the rubber composition is pressure-vulcanized at 160 °C for 40 minutes to obtain a vulcanized molded article, the wear volume ΔV when the vulcanized molded article rotates (abrasive wheel rotation speed) 1000 times in the Akron abrasion test based on JIS K 6264-2 is 50 mm 3 or less. The wear volume ΔV is, for example, 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50 mm 3 , or may be within the range between any two values exemplified herein. The wear volume ΔV of the vulcanized molded article of the rubber composition can be determined by the method described in the examples.

[0196] For the rubber composition according to the second aspect, by adjusting the wear volume ΔV of the vulcanized molded article of the rubber composition to 50 mm 3 or less in a rubber composition containing a chloroprene rubber, silica, silane coupling agent, and hydrate, a rubber composition capable of obtaining a vulcanized molded article having excellent abrasion resistance, tensile properties, and compression set resistance can be produced. By adjusting the types and amounts of the respective components in the rubber composition, the wear volume ΔV of the vulcanized molded article of the rubber composition can be controlled.

[0197] <Hardness of the vulcanized molded article>

[0198] Regarding the rubber composition according to the second aspect, the rubber composition is compression-molded at 160 °C for 40 minutes to obtain a vulcanized molded article, and the durometer hardness (Type A) specified in JIS K 6253 of the vulcanized molded article of the rubber composition may be 30 to 90. The durometer hardness (Type A) of the vulcanized molded article of the rubber composition is, for example, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, and may also be within the range between any two values exemplified herein. By adjusting the types and amounts of the ingredients of the rubber composition, particularly by adjusting the amount of the filler (especially silica), the durometer hardness (Type A) of the vulcanized molded article of the rubber composition can be controlled. In addition, the durometer hardness (Type A) of the vulcanized molded article of the rubber composition can also be determined by the method described in the examples. According to the present invention, even when the hardness is adjusted to a lower level, vulcanizates and vulcanized molded articles having excellent abrasion resistance, tensile properties, and compression set resistance can be obtained. And according to one embodiment of the present invention, by adjusting the types and amounts of the ingredients of the rubber composition so that the hardness is within the above numerical range, the types and amounts of the ingredients containing silica, silane coupling agent, and hydrate can be indirectly adjusted, and vulcanizates and vulcanized molded articles having appropriate hardness and more excellent abrasion resistance, tensile properties, and compression set resistance can be obtained.

[0199] The tensile properties and compression set resistance of the vulcanized molded article of the rubber composition according to the second aspect are the same as those of the first aspect.

[0200] Regarding 4. The unvulcanized molded article, vulcanizate, and vulcanized molded article are the same as those of the first aspect.

[0201] [Examples]

[0202] The present invention will be described in more detail below with reference to examples, but the present invention should not be construed as being limited to these examples.

[0203] [Manufacture of Chloroprene-Acrylonitrile Copolymer Rubber]

[0204] In a polymerization tank with an internal volume of 3 L equipped with a heating and 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, 5.00 parts by mass of potassium rosinate (manufactured by Halima 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 Corporation) were added. 0.1 part by mass of potassium persulfate as a polymerization initiator was added, and emulsion polymerization was carried out at a polymerization temperature of 40 °C and under a nitrogen gas stream. The chloroprene monomer was added in portions starting 20 seconds after the start of polymerization. According to the heat change of the refrigerant within 10 seconds from the start of polymerization, the flow rate of the portionwise addition was adjusted with a solenoid valve, and then the flow rate was readjusted every 10 seconds for continuous addition. When the polymerization rate relative to the total amount of the chloroprene monomer and acrylonitrile monomer reached 50%, 0.02 part by mass of phenothiazine as a polymerization terminator was added to stop the polymerization. Thereafter, the unreacted monomers in the reaction solution were removed under reduced pressure to obtain a chloroprene-acrylonitrile copolymer latex.

[0205] The above polymerization rate [%] of the chloroprene-acrylonitrile copolymer latex is calculated from the dry mass when the chloroprene-acrylonitrile copolymer latex is air-dried. Specifically, it is calculated according to the following formula (A). In the formula, "solid content concentration" is the concentration [mass%] of the solid content obtained by heating 2 g of the sampled chloroprene-acrylonitrile copolymer latex at 130 °C to remove volatile components such as solvents (water), volatile chemicals, and raw materials. "Total input amount" refers to the total amount [g] of raw materials, reagents, and solvents (water) introduced into the polymerization tank from the start of polymerization to a certain time. "Evaporation residue amount" refers to the mass [g] of the chemicals that do not volatilize under the condition of 130 °C among the chemicals and raw materials introduced from the start of polymerization to a certain time and remain as solid components together with the polymer. "Monomer input amount" is the sum of the monomers initially introduced into the polymerization tank and the monomers added in portions from the start of polymerization to a certain time [g]. Here, "monomer" refers to the total amount of chloroprene and acrylonitrile.

[0206] Polymerization rate = {[(Total input amount × Solid content concentration / 100) - Evaporation residue amount] / Monomer input amount} × 100…(A)

[0207] The pH value of the chloroprene-acrylonitrile copolymer latex was adjusted to 7.0 using acetic acid or sodium hydroxide, and then the chloroprene-acrylonitrile copolymer latex was frozen and solidified on a metal plate cooled to -20 °C until emulsion breakage to obtain a sheet. After washing the sheet with water, it was dried at 130 °C for 15 minutes to obtain solid chloroprene-acrylonitrile copolymer rubber (chloroprene-acrylonitrile copolymer).

[0208] After adjusting the above-mentioned chloroprene-acrylonitrile copolymer rubber to a solution with a concentration of 0.1% by mass using THF, the weight-average molecular weight (Mw), number-average molecular weight (Mn), and molecular weight distribution (Mw / Mn) (in terms of standard polystyrene conversion) of the chloroprene-acrylonitrile copolymer rubber were measured by a high-speed GPC device (TOSOH HLC-8320GPC: manufactured by TOSOH Corporation). At this time, a TSK guard column HHR-H was used as a pre-column, and three HSKgel GMHHR-H columns were used as analytical columns. Elution was carried out under the conditions of a sampling pump pressure of 8.0 - 9.5 MPa, a flow rate of 1 mL / min, and a temperature of 40 °C, and detection was performed using a differential refractometer.

[0209] The elution time and molecular weight were obtained from a calibration curve drawn by measuring standard polystyrene samples (a total of 9) with known molecular weights listed below.

[0210] 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

[0211] 、1.74×10 4 、2.63×10 3

[0212] The weight-average molecular weight (Mw) of the chloroprene-acrylonitrile copolymer rubber is 473×10 3 g / mol, the number-average molecular weight (Mn) is 138×10 3 g / mol, and the molecular weight distribution (Mw / Mn) is 3.4.

[0213] The content of the monomer unit of acrylonitrile contained in the chloroprene-acrylonitrile copolymer rubber was calculated from the content of nitrogen atoms in the chloroprene-acrylonitrile copolymer rubber. Specifically, using an elemental analyzer (SUMIGRAPH 220F: manufactured by Sumika Chemical Analysis Service, Ltd.), the content of nitrogen atoms in 100 mg of the chloroprene-acrylonitrile copolymer rubber was measured, and the content of the monomer unit of acrylonitrile was calculated. The content of the monomer unit of acrylonitrile is 9.9% by mass.

[0214] The above elements are analyzed as follows. The temperature of the electric furnace is set at 900 °C for the reaction furnace and 600 °C for the reduction furnace, the column temperature is set at 70 °C, and the detector temperature is set at 100 °C. Oxygen is used as the combustion gas and flows at 0.2 mL / min, and helium is used as the carrier gas and flows at 80 mL / min. A calibration curve is prepared using aspartic acid with a known nitrogen content (10.52%) as the standard substance.

[0215] <Manufacture of Rubber Composition>

[0216] As shown in Tables 1 to 3, the respective components are mixed and kneaded with an 8-inch open mill to obtain the rubber compositions of the examples and comparative examples. In addition, since the viscosity of the mixture is too high, the heat generation during processing increases, and the cross-linking reaction causes the rubber composition of Comparative Example 1 to harden. Furthermore, the rubber compositions of Comparative Examples 5 to 12 do not undergo a vulcanization reaction even when heated and molded, and do not exhibit rubber elasticity.

[0217] The respective components used to obtain the rubber composition are as follows.

[0218] (Chloroprene Rubber)

[0219] Chloroprene rubber containing acrylonitrile: the above-mentioned chloroprene-acrylonitrile copolymer rubber;

[0220] Thiol-modified chloroprene rubber: "S-40V" manufactured by Denka Co., Ltd.

[0221] (Filler)

[0222] Silica Nipsil AQ: "Nipsil AQ" manufactured by Tosoh Silica Co., Ltd. (BET specific surface area 187 m 2 / g);

[0223] Silica Carplex 1120: "Carplex 1120", (BET specific surface area 120 m 2 / g, average particle diameter 12 μm).

[0224] (Silane Coupling Agent)

[0225] Silane coupling agent containing an amino group: "KBM-573" manufactured by Shin-Etsu Chemical Co., Ltd., N-phenyl-3-aminopropyltrimethoxysilane.

[0226] [Chemical Formula 6]

[0227]

[0228] Silane coupling agent without an amino group: "KBM-503" manufactured by Shin-Etsu Chemical Co., Ltd., 3-methacryloxypropyltrimethoxysilane.

[0229] [Chemical 7]

[0230]

[0231] (Compound A and 3-methyl-thiazolidine-2-thione)

[0232] Thiourea compound Nocceler TMU: Manufactured by Ouchi Shinko Chemical Industry Co., Ltd., "Nocceler TMU", trimethylthiourea;

[0233] Thiourea compound Accel 22S: Manufactured by Kawaguchi Chemical Industry Co., Ltd., "Accel 22S", ethylenethiourea;

[0234] Bis(5-mercapto-1,3,4-thiadiazol-2-yl) disulfide: Manufactured by MLPC International, "MIXLAND+SD 75GAF250";

[0235] 3-methyl-thiazolidine-2-thione: Manufactured by LANXESS, "Rhenogran MTT-80".

[0236] (Compound B)

[0237] Thiuram compound Nocceler TT: Manufactured by Ouchi Shinko Chemical Industry Co., Ltd., "Nocceler TT", tetramethylthiuram disulfide;

[0238] Sulfenamide compound Nocceler CZ: Manufactured by Ouchi Shinko Chemical Industry Co., Ltd., "NoccelerCZ", N-cyclohexyl-2-benzothiazolesulfenamide;

[0239] Thiazole compound Nocceler DM: Manufactured by Ouchi Shinko Chemical Industry Co., Ltd., "Nocceler DM", bis-2-benzothiazolyl disulfide;

[0240] Guanidine compound Nocceler DT: Manufactured by Ouchi Shinko Chemical Industry Co., Ltd., "Nocceler DT", 1,3-di-o-tolylguanidine;

[0241] DBU (diazabicycloundecene) compound Rhenogran XLA-60: Manufactured by LANXESS, "Rhenogran XLA-60", a synthetic mixture containing 60% by mass of active amine (DBU) and a retarder;

[0242] Benzimidazole compound Nocrac MB: Manufactured by Ouchi Shinko Chemical Industry Co., Ltd., "Nocrac MB", mercaptobenzimidazole;

[0243] N-Phenyl-N-(trichloromethylthio)benzenesulfonamide: Manufactured by LANXESS Corporation as "VULKALENT E / C".

[0244] (Hydrate)

[0245] DHT-4A: Manufactured by Kyowa Chemical Industry Co., Ltd. as "DHT-4A", Mg 4.3 Al2(OH) 12.6 CO3·3.5H2O;

[0246] ZHT-4A: Manufactured by Kyowa Chemical Industry Co., Ltd. as "ZHT-4A", Mg3ZnAl2(OH) 12 CO3·3H2O.

[0247] Acid acceptor ZnO: Manufactured by Sakai Chemical Industry Co., Ltd. as "Type 2 Zinc Oxide";

[0248] Plasticizer RS-700: Manufactured by ADEKA Corporation as "ADEKA SIZER RS-700", polyether esters;

[0249] Lubricant stearic acid: Manufactured by Shin Nippon Rika Co., Ltd. as "Stearic Acid 50S";

[0250] Antioxidant Nocrac CD: Manufactured by Ouchi Shinko Chemical Industry Co., Ltd. as "Nocrac CD", 4,4'-bis(α,α-dimethylbenzyl)diphenylamine.

[0251] <Hardness (Type A durometer)>

[0252] The obtained rubber composition was pressure-vulcanized at 160 °C for 40 minutes according to JIS K6299 and then formed into a sheet-shaped vulcanized molded body with a thickness of 2 mm. The durometer hardness (Type A) specified in JIS K 6253 of the obtained sheet-shaped vulcanized molded body was measured using GS-610 (manufactured by TECLOCK Corporation). The results are shown in Tables 1 to 4.

[0253] <Tensile properties>

[0254] The obtained rubber composition was pressure-vulcanized at 160 °C for 40 minutes according to JIS K6299 and then formed into a sheet-shaped vulcanized molded body with a thickness of 2 mm. Based on JIS K 6251, the above sheet-shaped vulcanized molded body was formed into dumbbell-shaped No. 3 test pieces with a thickness of 2 mm, and 4 test pieces were prepared. Using AGS-X manufactured by Shimadzu Corporation, the tensile strength at break and the elongation at break of each test piece were measured at a tensile speed of 500 mm / min. The results are shown in Tables 1 to 4.

[0255] <Compression set resistance>

[0256] For a cylindrical vulcanized molded body with a diameter of 29 mm and a height of 12.5 mm obtained by pressure vulcanization treatment at 160 °C for 50 minutes, the compression set resistance was measured under the test conditions of 70 °C for 24 hours based on JIS K 6262:2013. The results are shown in Tables 1 to 4.

[0257] <Abrasion resistance>

[0258] The obtained rubber composition was subjected to pressure vulcanization treatment at 160 °C for 40 minutes to prepare a vulcanized molded body with a diameter of 63.6 mm, a thickness of 12.7 mm, and a central hole of 12.7 mm. For the prepared vulcanized molded body, the Akron abrasion test (abrasion 1000 times, abrasion volume ΔV, unit: mm 3 ) was carried out in accordance with JIS K 6264-2:2019. The results are shown in Tables 1 to 4.

[0259] [Table 1]

[0260]

[0261] [Table 2]

[0262]

[0263] [Table 3]

[0264]

[0265] [Table 4]

[0266]

Claims

1. A rubber composition comprising a chloroprene rubber, silica, a silane coupling agent, and a hydrate, In the rubber composition, 5 to 80 parts by mass of silica and more than 0.5 part by mass and less than 20 parts by mass of the hydrate are contained per 100 parts by mass of the chloroprene rubber, and in the rubber composition, 0.5 to 15 parts by mass of the silane coupling agent are contained per 100 parts by mass of the silica, The rubber composition satisfies at least one of the following conditions i) and ii): Condition i) The rubber composition contains 3-methyl-thiazolidine-2-thione, and in the rubber composition, 0.1 to 3.0 parts by mass of 3-methyl-thiazolidine-2-thione are contained per 100 parts by mass of the chloroprene rubber; Condition ii) The rubber composition contains Compound A and Compound B, Compound A is at least one selected from thiourea compounds, 3-methyl-thiazolidine-2-thione, and bis(5-mercapto-1,3,4-thiadiazol-2-yl) disulfide, Compound B is at least one selected from thiuram compounds, sulfenamide compounds, thiazole compounds, guanidine compounds, benzimidazole compounds, N-phenyl-N-(trichloromethylthio)benzenesulfonamide, and diazabicycloundecene compounds, in the rubber composition, 0.1 to 3.0 parts by mass of Compound A and 0.01 to 3.0 parts by mass of Compound B are contained per 100 parts by mass of the chloroprene rubber.

2. The rubber composition according to claim 1, wherein the chloroprene rubber contains an unsaturated nitrile monomer unit.

3. The rubber composition according to claim 1 or 2, wherein the silane coupling agent is a silane coupling agent having an amino group in its structure.

4. The rubber composition according to claim 1 or 2, wherein the hydrate is a hydrate that releases H2O in the temperature range of 100°C to 250°C.

5. The rubber composition according to claim 1 or 2, wherein the hydrate is a hydrate of at least one selected from hydrotalcite compounds, hydrated salts, and metal hydroxides represented by the following chemical formula (1); [M 2+ 1-x M 3+ x (OH)2] x+ [A n- x / n ·mH2O] x- (1) M 2+ : at least one divalent metal ion selected from Mg 2+ , Mn 2+ , Fe 2+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ ; M 3+ : at least one trivalent metal ion selected from Al 3+ , Fe 3+ , Cr 3+ , Co 3+ , In 3+ ; A n- : at least one n-valent anion selected from OH - , F - , Cl - , Br - , NO3 - , CO3 2- , SO4 2- , Fe(CN)6 3- , CH3COO - ; X: 0 < X ≤ 0.

33.

6. The rubber composition according to claim 5, wherein the hydrate is selected from Mg 4.3 Al2(OH) 12.6 CO3·3.5H2O, Mg3ZnAl2(OH) 12 CO3·3H2O, Mg 4.5 Al2(OH) 13 CO3·3.5H2O, Mg 4.5 Al2(OH) 13 CO3, Mg4Al2(OH) 12 CO3·3.5H2O, Mg6Al2(OH) 16 CO3·4H2O, Mg5Al2(OH) 14 CO3·4H2O, Mg3Al2(OH) 10 at least one hydrate of a hydrotalcite compound represented by CO3·1.7H2O.

7. The rubber composition according to claim 1 or 2, wherein the BET specific surface area of the silica is 50 to 300 m 2 / g.

8. The rubber composition according to claim 1 or 2, the rubber composition contains Compound A and Compound B, in the rubber composition, 10 to 100 parts by mass of Compound B are contained per 100 parts by mass of Compound A.

9. A rubber composition comprising a chloroprene rubber, silica, a silane coupling agent, and a hydrate, When the rubber composition is compression-molded under the conditions of 160°C and 40 minutes to obtain a vulcanized molded article, the wear volume ΔV of the vulcanized molded article in the Akron abrasion test based on JIS K 6264-2 is 50 mm when rotated 1000 times. 3 as follows.

10. The rubber composition according to claim 9, wherein the durometer hardness (Type A) specified in JIS K6253 of the vulcanized molded body is 30 to 90.

11. The rubber composition according to claim 9 or 10, wherein in the rubber composition, 5 to 80 parts by mass of the silica and more than 0.5 part by mass and less than 20 parts by mass of the hydrate are contained per 100 parts by mass of the chloroprene rubber, In the rubber composition, 0.5 to 15 parts by mass of the silane coupling agent is contained relative to 100 parts by mass of the silica.

12. The rubber composition according to claim 9 or 10, wherein the rubber composition contains at least one of 3-methyl-thiazolidine-2-thione, compound A, and compound B. Compound A is at least one selected from thiourea compounds, 3-methyl-thiazolidine-2-thione, and bis(5-mercapto-1,3,4-thiadiazol-2-yl) disulfide. Compound B is at least one selected from thiuram compounds, sulfenamide compounds, thiazole compounds, guanidine compounds, benzimidazole compounds, N-phenyl-N-(trichloromethylthio) benzenesulfonamide, and diazabicycloundecene compounds.

13. A sulfide which is a sulfide of the rubber composition according to claim 1 or 9.

14. A vulcanized molded article which is a vulcanized molded article of the rubber composition according to claim 1 or 9.

Images