Rubber compositions, vulcanized products, and vulcanized molded articles

Abstract

The present invention provides a rubber composition that can produce vulcanized products and vulcanized molded articles with excellent gas barrier properties, flexural fatigue resistance, and heat resistance. [Solution] According to the present invention, a rubber composition is provided which includes chloroprene rubber and butyl rubber, wherein the rubber composition contains 0.1 to 99 parts by mass of chloroprene rubber per 100 parts by mass of rubber contained in the rubber composition, and the chloroprene rubber contains chloroprene rubber containing unsaturated nitrile monomer units.

Description

[Technical Field]

[0001] The present invention relates to rubber compositions, vulcanized products, and vulcanized molded articles.

[0002] Rubber compositions, leveraging their properties, are used in a wide range of applications, such as power transmission belts and conveyor belts for general industrial use, air springs for automobiles, vibration-damping rubber, hoses, wipers, immersion products, sealing parts, adhesives, boots, rubberized fabrics, and rubber rolls. Furthermore, the properties required of rubber components have increased significantly in recent years. [Background technology]

[0003] Patent Document 1 discloses a rubber composition for tire vulcanization bladder, characterized by comprising 100 parts by mass of a rubber component containing 90 parts by mass or more of butyl rubber consisting of butyl rubber and / or halogenated butyl rubber, blended with 1 to 20 parts by mass of an alkylphenol-formaldehyde condensate and 0.1 to 10 parts by mass of a citraconimide compound. Furthermore, Patent Document 2 discloses a rubber composition for bladders containing a butyl rubber component and zinc oxide with an average primary particle diameter of 15 to 190 nm. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2016-098294 [Patent Document 2] Japanese Patent Publication No. 2010-285225 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, it has been difficult to simultaneously improve gas barrier properties, flexural fatigue resistance, and heat resistance in vulcanized products and vulcanized molded articles obtained from conventional rubber compositions. The present invention has been made in view of these circumstances, and provides a rubber composition that can obtain vulcanized products and vulcanized molded articles with excellent gas barrier properties, flexural fatigue resistance, and heat resistance. [Means for solving the problem]

[0006] According to the present invention, a rubber composition is provided which includes chloroprene rubber and butyl rubber, wherein the rubber composition contains 0.1 to 99 parts by mass of chloroprene rubber when the total amount of rubber in the rubber composition is 100 parts by mass, and the chloroprene rubber contains chloroprene rubber containing unsaturated nitrile monomer units.

[0007] Conventionally, butyl rubber has been known to possess excellent gas barrier properties and heat resistance. However, it has been difficult to further improve flexural fatigue resistance while maintaining gas barrier properties and heat resistance in vulcanized products and vulcanized molded articles obtained from rubber compositions containing butyl rubber. Through diligent research, the inventors have discovered that by specifying the type and amount of chloroprene rubber in a chloroprene rubber composition containing butyl rubber and chloroprene rubber, it is possible to obtain vulcanized products and vulcanized molded articles with excellent gas barrier properties, flexural fatigue resistance, and heat resistance, thus completing the present invention.

[0008] The following are examples of various embodiments of the present invention. The embodiments shown below can be combined with each other. [1] A rubber composition comprising chloroprene rubber and butyl rubber, wherein the rubber composition contains 0.1 to 99 parts by mass of chloroprene rubber per 100 parts by mass of rubber contained in the rubber composition, and the chloroprene rubber contains chloroprene rubber containing unsaturated nitrile monomer units. [2] The rubber composition according to [1], wherein the rubber composition contains a total of 0.1 to 10.0 parts by mass of a thiourea compound, 3-methyl-thiazoldin-2-thion, and a thiadiazole compound per 100 parts by mass of rubber contained in the rubber composition. [3] The rubber composition according to [1] or [2], wherein the butyl rubber comprises halogenated butyl rubber. [4] The rubber composition according to any one of [1] to [3], wherein the rubber composition contains a total of 0.1 to 10.0 parts by mass of a thiuram compound, a thiazole compound, and a sulfenamide compound per 100 parts by mass of rubber contained in the rubber composition. [5] The rubber composition according to any one of [1] to [4], wherein the chloroprene rubber contains 1 to 25% by mass of unsaturated nitrile monomer units based on 100% by mass of the chloroprene rubber. [6] The rubber composition according to any one of [1] to [5], wherein the rubber composition contains 1 to 30 parts by mass of compound A having at least one ester structure and a molecular weight of 300 to 1000, per 100 parts by mass of rubber contained in the rubber composition. A vulcanized product of a rubber composition described in any of [7][1] to [6]. A vulcanized molded article of the vulcanized product described in [8][7]. [Effects of the Invention]

[0009] The rubber composition according to the present invention provides vulcanized products and vulcanized molded articles with excellent gas barrier properties, flexural fatigue resistance, and heat resistance. Furthermore, the vulcanized products and vulcanized molded articles according to the present invention have excellent gas barrier properties, flexural fatigue resistance, and heat resistance. In addition to known applications (for example, power transmission belts and conveyor belts for general industry, air springs for automobiles, vibration-damping rubber, hoses, wipers, immersion products, sealing parts, adhesives, boots, rubberized fabrics, and rubber rolls), the vulcanized products and vulcanized molded articles according to the present invention can be suitably used, taking advantage of their properties, as materials for tire inner liners, tubes, curing bladders, rubber stoppers for pharmaceuticals, wire coatings, vibration-damping materials, hoses, linings, condenser packings, gaskets, etc., as an example. The vulcanized products and vulcanized molded articles according to one embodiment of the present invention can be suitably used in applications requiring particularly excellent gas barrier properties, flexural fatigue resistance, and heat resistance, such as tire inner liners, tubes, and curing bladders.

[0010] 1. Rubber composition The rubber composition according to the present invention is a rubber composition comprising chloroprene rubber and butyl rubber, wherein the rubber composition contains 0.1 to 99 parts by mass of chloroprene rubber when the total amount of rubber in the rubber composition is 100 parts by mass, and the chloroprene rubber contains chloroprene rubber containing unsaturated nitrile monomer units.

[0011] 1.1 Chloroprene-based rubber The chloroprene-based rubber according to the present invention refers to a rubber containing a chloroprene-based polymer having chloroprene (2-chloro-1,3-butadiene) as a monomer unit (monomer unit = structural unit). Examples of chloroprene-based polymers include chloroprene homopolymers and chloroprene copolymers (polymers of chloroprene and monomers copolymerizable with chloroprene). The polymer structure of the chloroprene-based polymer is not particularly limited.

[0012] It should be noted that commercially available 2-chloro-1,3-butadiene may contain small amounts of 1-chloro-1,3-butadiene as an impurity. Such 2-chloro-1,3-butadiene containing small amounts of 1-chloro-1,3-butadiene can also be used as the chloroprene monomer in this embodiment.

[0013] The chloroprene-based rubber according to the present invention contains chloroprene-based rubber containing unsaturated nitrile monomer units. The chloroprene-based rubber according to the present invention may contain one or more types of chloroprene-based rubber. The chloroprene rubber according to one embodiment of the present invention may contain chloroprene rubber containing one or more unsaturated nitrile monomer units. Furthermore, the chloroprene rubber according to one embodiment of the present invention may further contain chloroprene rubber that does not contain one or more unsaturated nitrile monomer units.

[0014] Chloroprene-based rubber according to one embodiment of the present invention (chloroprene-based rubber containing unsaturated nitrile monomer units and chloroprene-based rubber not containing unsaturated nitrile monomer units) may also have monomer units derived from monomers other than chloroprene monomers and unsaturated nitrile monomers. There are no particular restrictions on the monomers other than chloroprene monomers as long as they can copolymerize with chloroprene monomers, but examples include (meth)acrylic acid esters ((meth)acrylate, (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. As an example, a chloroprene-based rubber according to one embodiment of the present invention may contain 2,3-dichloro-1,3-butadiene monomer units.

[0015] The chloroprene rubber containing an unsaturated nitrile monomer unit according to an embodiment of the present invention can have a content rate of the unsaturated nitrile monomer unit of 1 to 25% by mass, preferably 1 to 20% by mass, and more preferably 5 to 20% by mass when the chloroprene rubber containing the unsaturated nitrile monomer unit is 100% by mass. The content rate of the unsaturated nitrile monomer unit in the chloroprene rubber containing the unsaturated nitrile monomer unit according to an embodiment of the present invention is, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25% by mass, and may be within the range between any two of the numerical values exemplified herein. By setting the content rate of the unsaturated nitrile monomer unit in the rubber composition to be not more than the above upper limit, the water resistance and cold resistance of the vulcanized molded body of the rubber composition are further improved. Further, by containing the unsaturated nitrile monomer unit, the oil resistance of the vulcanized molded body of the rubber composition is improved.

[0016] When the chloroprene rubber according to an embodiment of the present invention contains two or more kinds of chloroprene rubbers, the content rate based on the total amount of the unsaturated nitrile monomer units contained in the two or more kinds of chloroprene rubbers is preferably within the above numerical range with respect to 100% by mass of the total of the two or more kinds of chloroprene rubbers contained in the rubber composition. That is, the chloroprene rubber according to an embodiment of the present invention preferably contains 1 to 25% by mass of the unsaturated nitrile monomer unit with respect to 100% by mass of the chloroprene rubber, and the content rate of the unsaturated nitrile monomer unit may be within the range between any two of the numerical values exemplified above. Further, the chloroprene rubber according to an embodiment of the present invention preferably contains 1 to 25% by mass of the acrylonitrile monomer unit with respect to 100% by mass of the chloroprene rubber, and the content rate of the acrylonitrile monomer unit may be within the range between any two of the numerical values exemplified above.

[0017] Examples of the unsaturated nitrile include acrylonitrile, methacrylonitrile, ethacrylonitrile, phenylacrylonitrile, etc. The unsaturated nitrile can be used alone or in combination of two or more kinds. From the viewpoint of easily obtaining excellent moldability and from the viewpoint of easily obtaining excellent breaking strength, breaking elongation, hardness, tear strength, and oil resistance in the vulcanized molded body, it is preferable to contain acrylonitrile.

[0018] 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, using an elemental analyzer (Sumigraph 220F: manufactured by Sumitomo Chemical Analysis Center Co., Ltd.), the content of nitrogen atoms in 100 mg of chloroprene rubber is measured, and the content of the structural unit derived from the unsaturated nitrile monomer can be calculated. The measurement of elemental analysis can be performed under the following conditions. For example, the electric furnace temperature is set to 900 °C for the reaction furnace, 600 °C for the reduction furnace, 70 °C for the column temperature, and 100 °C for the detector temperature, and oxygen is flowed at 0.2 mL / min as the combustion gas and helium is flowed at 80 mL / min as the carrier gas. The calibration curve can be prepared using aspartic acid (10.52%) with a known nitrogen content as a standard substance.

[0019] The chloroprene rubber according to one embodiment of the present invention preferably contains 75 to 100% by mass of chloroprene monomer units, more preferably 80 to 100% by mass, when the chloroprene rubber is 100% by mass. The content rate of the chloroprene monomer units in the chloroprene rubber is, for example, 75, 80, 85, 90, 95, 99, 100% by mass, and may be within the range between any two of the numerical values exemplified herein. By setting the content rate of the chloroprene monomer units within the above numerical range, a rubber composition capable of obtaining a molded body excellent in the balance of hardness, tensile strength, and cold resistance can be obtained.

[0020] The chloroprene-based rubber according to one embodiment of the present invention may contain 0 to 20% by mass of monomer units other than chloroprene monomer units and unsaturated nitrile monomer units when the chloroprene-based rubber is considered to be 100% by mass. The content of monomer units other than chloroprene monomer units and unsaturated nitrile monomer units in the chloroprene-based rubber may be, for example, 0, 2, 4, 6, 8, 10, 12, 14, 16, 18, or 20% by mass, and may be within the range of any two of the values ​​exemplified herein. By adjusting the copolymerization amount of monomers other than chloroprene monomers and unsaturated nitrile monomers to the above range, the effects of copolymerizing these monomers can be expressed without impairing the properties of the resulting rubber composition.

[0021] In the case of a rubber composition according to one embodiment of the present invention that contains two or more types of chloroprene rubber, it is preferable that the content rate based on the total amount of each monomer unit contained in the two or more types of chloroprene rubber, relative to 100% by mass of the total of the two or more types of chloroprene rubber contained in the rubber composition, is within the above numerical range.

[0022] The chloroprene polymer (chloroprene homopolymer, chloroprene copolymer, etc.) contained in the chloroprene rubber according to the present invention may be sulfur-modified chloroprene polymer, mercaptan-modified chloroprene polymer, xanthogene-modified chloroprene polymer, dithiocarbonate-based chloroprene polymer, trithiocarbonate-based chloroprene polymer, carbamate-based chloroprene polymer, etc.

[0023] 1.2 Method for manufacturing chloroprene rubber The method for producing chloroprene rubber according to the present invention is not particularly limited, but it can be obtained by a production method that includes an emulsion polymerization step in which raw material monomers containing chloroprene monomers are emulsion polymerized. In the emulsion polymerization process according to one embodiment of the present invention, a raw material monomer containing chloroprene monomers is emulsion polymerized using an emulsifier, dispersant, catalyst, chain transfer agent, etc. as appropriate, and when the desired final conversion rate is reached, a polymerization termination agent is added to obtain a latex containing a chloroprene polymer containing chloroprene monomer units. Next, unreacted monomers can be removed from the polymerization solution obtained in the emulsion polymerization process. The method for this is not particularly limited, and for example, steam stripping can be used. After that, the pH is adjusted, and chloroprene rubber containing a chloroprene polymer can be obtained by going through processes such as conventional freeze-solidification, water washing, and hot air drying.

[0024] There are no particular restrictions on the polymerization initiator used in emulsion polymerization; known polymerization initiators commonly used in the emulsion polymerization of chloroprene can be used. Examples of polymerization initiators include potassium persulfate, ammonium persulfate, sodium persulfate, hydrogen peroxide, and organic peroxides such as t-butyl hydroperoxide.

[0025] There are no particular restrictions on the emulsifier used in emulsion polymerization, and any known emulsifier commonly used in the emulsion polymerization of chloroprene can be used. Examples of emulsifiers include alkali metal salts of saturated or unsaturated fatty acids having 6 to 22 carbon atoms, alkali metal salts of rosinic acid or disproportionated rosinic acid (e.g., potassium rosinate), and alkali metal salts of formalin condensates of β-naphthalenesulfonic acid (e.g., sodium salt).

[0026] There are no particular restrictions on the molecular weight modifier used in emulsion polymerization, and known molecular weight modifiers commonly used in the emulsion polymerization of chloroprene can be used, such as mercaptan compounds, xanthogene compounds, dithiocarbonate compounds, trithiocarbonate compounds, and carbamate compounds. In one embodiment of the present invention, xanthogene compounds, dithiocarbonate compounds, trithiocarbonate compounds, and carbamate compounds can be suitably used as molecular weight modifiers for chloroprene-based rubber.

[0027] The polymerization temperature and the final conversion rate of the monomer are not particularly limited, but the polymerization temperature may be, for example, 0 to 50°C or 10 to 50°C. Polymerization may be carried out so that the final conversion rate of the monomer falls within the range of 40 to 95% by mass. To adjust the final conversion rate, a polymerization inhibitor can be added to stop the polymerization reaction when the desired conversion rate is reached.

[0028] There are no particular restrictions on the polymerization inhibitor; any known polymerization inhibitor commonly used in the emulsion polymerization of chloroprene can be used. Examples of polymerization inhibitors include phenothiazine (thiodiphenylamine), 4-t-butylcatechol, and 2,2-methylenebis-4-methyl-6-t-butylphenol.

[0029] A chloroprene-based rubber according to one embodiment of the present invention can be obtained, for example, by removing unreacted monomers by steam stripping, adjusting the pH of the latex, and then following conventional freeze-solidification, water washing, and hot-air drying processes.

[0030] Chloroprene-based rubbers are classified into mercaptan-modified type, xanthogene-modified type, sulfur-modified type, dithiocarbonate type, trithiocarbonate type, and carbamate type, depending on the type of molecular weight modifier used.

[0031] 1.3 Butyl rubber The rubber composition according to the present invention includes butyl rubber. In the present invention, butyl rubber means rubber containing a butyl polymer containing monomer units derived from isobutylene. That is, butyl rubber contains isobutylene monomer units. Furthermore, butyl rubber according to one embodiment of the present invention may contain isobutylene monomer units and isoprene monomer units, that is, it may include copolymers obtained by copolymerizing raw material monomers containing isobutylene and isoprene. Butyl rubber may contain 0.5 to 10 mol% isoprene monomer units. The isoprene monomer unit content is expressed as the isoprene monomer unit content (mol%) when the total number of moles of isobutylene monomer units, isoprene monomer units, and other monomer units (if present) contained in the butyl rubber is taken as 100 mol%.

[0032] The butyl rubber according to the present invention may include one or more types of butyl rubber. The butyl rubber according to one embodiment of the present invention may include one or more types selected from regular butyl rubber (non-halogenated butyl rubber) and halogenated butyl rubber. The butyl rubber according to one embodiment of the present invention may include halogenated butyl rubber. The butyl rubber according to one embodiment of the present invention may be halogenated butyl rubber. Examples of halogenated butyl rubber include chlorinated butyl rubber and brominated butyl rubber. When halogenated butyl rubber is considered as 100% by mass, halogenated butyl rubber may contain 0.1 to 5.0% by mass of halogen, preferably 0.5 to 3.0% by mass. The halogen content in halogenated butyl rubber may be, for example, 0.1, 0.2, 0.3, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0% by mass, and may be within the range of any two of the values ​​exemplified here.

[0033] The butyl rubber according to one embodiment of the present invention preferably contains 75 to 100% by mass of isobutylene monomer units, and more preferably 80 to 100% by mass, when the butyl rubber is considered to be 100% by mass. The content of chloroprene monomer units in the butyl rubber is, for example, 75, 80, 85, 90, 95, 99, or 100% by mass, and may be within the range of any two of the values ​​exemplified herein.

[0034] 1.4 Other Rubbers The rubber composition according to one embodiment of the present invention may also include rubbers other than chloroprene rubber and butyl rubber. Examples of other rubbers include natural rubber (NR), hydrogenated acrylonitrile butadiene rubber (H-NBR), acrylonitrile butadiene rubber (NBR), chlorosulfonated polyethylene (CSM), ethylene-propylene-diene rubber (EPDM), isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), epoxidized natural rubber (ENR), acrylonitrile butadiene rubber (NBR), styrene-isoprene-butadiene copolymer rubber (SIBR), epichlorohydrin rubber (CO), acrylic rubber (ACM), urethane rubber (U), silicone rubber (Q), fluororubber (FKM), and polysulfide rubber (T). The rubber composition according to one embodiment of the present invention may include chloroprene rubber, butyl rubber, and natural rubber.

[0035] 1.5 Rubber content The rubber composition according to the present invention contains 0.1 to 99 parts by mass of chloroprene rubber when the total amount of rubber in the rubber composition is 100 parts by mass. According to the present invention, by including chloroprene rubber containing unsaturated nitrile monomer units, even if the content is small, the flexural fatigue resistance is significantly improved. The content of chloroprene rubber is preferably 0.1 to 90 parts by mass, more preferably 0.1 to 70 parts by mass, and even more preferably 0.3 to 50 parts by mass. The chloroprene rubber content may be, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 99 parts by mass, and may be within the range of any two of the values ​​exemplified here.

[0036] The rubber composition according to the present invention may contain 1 to 99.9 parts by mass of butyl rubber when the total amount of rubber in the rubber composition is 100 parts by mass, preferably 10 to 99.9 parts by mass, more preferably 30 to 99.9 parts by mass, and even more preferably 50 to 99.9 parts by mass. The butyl rubber content may be, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 96, 97, 98, 99, 99.5, or 99.9 parts by mass, and may be within the range of any two of the values ​​exemplified herein.

[0037] The rubber composition according to the present invention may contain a total of 50 to 100 parts by mass of chloroprene-based rubber and butyl-based rubber per 100 parts by mass of rubber contained in the rubber composition, preferably 70 to 100 parts by mass, and more preferably 90 to 100 parts by mass. The total content of chloroprene-based rubber and butyl-based rubber may be, for example, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100 parts by mass, and may be within the range of any two of the values ​​exemplified here. The rubber composition according to the present invention may contain 0 to 50 parts by mass, 0 to 30 parts by mass, or 0 to 10 parts by mass of rubber other than chloroprene-based rubber and butyl-based rubber per 100 parts by mass of rubber contained in the rubber composition.

[0038] 1.6 Vulcanizing agents and vulcanizing accelerators The rubber composition according to the present invention may contain a vulcanizing agent. Furthermore, the rubber composition according to the present invention may contain a vulcanization accelerator. The types of vulcanizing agents and vulcanization accelerators are not particularly limited as long as they do not impair the effects of the present invention. The vulcanizing agents and vulcanization accelerators preferably contribute to the vulcanization of butyl rubber and / or chloroprene rubber, and more preferably contribute to the vulcanization of both butyl rubber and chloroprene rubber.

[0039] One or more vulcanizing agents can be freely selected and used. Sulfur can be used as an example of a vulcanizing agent. In the rubber composition according to one embodiment of the present invention, if regular butyl rubber is included as the butyl rubber, it is preferable to include sulfur. The content of the vulcanizing agent can be 0 to 10.0 parts by mass, preferably 0 to 5.0 parts by mass, per 100 parts by mass of rubber contained in the rubber composition, for example, 0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7, 8, 9, or 10.0 parts by mass, and may be within the range of any two of the values ​​exemplified here. Note that the rubber composition according to the present invention may also not contain a vulcanizing agent.

[0040] A rubber composition according to one embodiment of the present invention may contain a vulcanization accelerator. The rubber composition according to one embodiment of the present invention may contain 0 to 10.0 parts by mass of a vulcanization accelerator per 100 parts by mass of rubber contained in the rubber composition. The content of the vulcanization accelerator may be, for example, 0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, or 10.0 parts by mass, and may be within the range of any two of the values ​​exemplified here. The rubber composition according to the present invention may also not contain a vulcanization accelerator.

[0041] One or more types of vulcanization accelerators can be freely selected and used. Examples of vulcanization accelerators include thiram compounds, 3-methyl-thiazoldin-2-thion, thiadiazole compounds, dithiocarbamate compounds, thiourea compounds, guanidine compounds, xanthogenic acid compounds, thiazole compounds, and sulfenamide compounds.

[0042] The rubber composition according to one embodiment of the present invention preferably contains at least one selected from a thiram-based compound, 3-methyl-thiazoldin-2-thion, and a thiadiazole-based compound. The rubber composition according to one embodiment of the present invention preferably contains at least a thiram-based compound. The rubber composition according to one embodiment of the present invention preferably contains a total of 0.1 to 10.0 parts by mass of a thiourea-based compound, 3-methyl-thiazoldin-2-thion, and a thiadiazole-based compound per 100 parts by mass of rubber contained in the rubber composition, and more preferably contains a total of 0.3 to 5.0 parts by mass. The total content of thiourea compounds, 3-methyl-thiazoldin-2-thion, and thiadiazole compounds is, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, and 10.0 parts by mass, and may be within the range of any two of the values ​​exemplified here. A rubber composition containing one selected from thiourea compounds, 3-methyl-thiazoldin-2-thion, and thiadiazole compounds as a vulcanization accelerator, and particularly containing their total content within the above numerical range, allows for sufficient vulcanization of chloroprene rubber and butyl rubber, resulting in a vulcanized product and a vulcanized molded article with superior gas barrier properties, flexural fatigue resistance, and heat resistance.

[0043] Examples of thiourea compounds include compounds having a thiourea structure. Examples of thiourea compounds include compounds represented by the following formula.

[0044] [ka]

[0045] In the above formula, R 11 ~R 14Each of these can independently be hydrogen or an organic group, or hydrogen or a hydrocarbon group, and the hydrocarbon group can be an alkyl group or an aryl group. Examples of thiourea compounds include ethylenethiourea, diethylthiourea (N,N'-diethylthiourea), trimethylthiourea, diphenylthiourea (N,N'-diphenylthiourea), and 1,3-trimethylene-2-thiourea.

[0046] 3-methyl-thiazoldin-2-thione is represented by the following formula.

[0047] [ka]

[0048] An example of a thiadiazole compound is di(5-mercapto-1,3,4-thiadiazole-2-yl) disulfide, which is represented by the following formula.

[0049] [ka]

[0050] The rubber composition according to one embodiment of the present invention preferably contains any one selected from thiuram compounds, thiazole compounds, and sulfenamide compounds. The rubber composition according to one embodiment of the present invention preferably contains a total of 0.1 to 10.0 parts by mass, more preferably 0.1 to 5.0 parts by mass, of thiuram compounds, thiazole compounds, and sulfenamide compounds with respect to 100 parts by mass of the rubber contained in the rubber composition. The total content of the thiuram compound, thiazole compound, and sulfenamide compound may be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0 parts by mass, and may be within the range between any two of the numerical values exemplified herein. By containing at least one selected from thiuram compounds, thiazole compounds, and sulfenamide compounds as a vulcanization accelerator, particularly within the above numerical range, a rubber composition capable of obtaining a vulcanized product and a vulcanized molded body having further excellent flex fatigue resistance can be obtained.

[0051] Examples of the thiuram compound include compounds containing one or more structures represented by the following formula.

[0052]

Chemical formula

[0053] In the above formula, R 21 , R 22 , R 23 , R 24 can each independently be an organic group and is 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 , R 23 and R 24 may each be linked to form a cyclic structure (for example, a cycloalkyl group). n can be an integer of 1 or more, can be 1 to 4, is preferably 1 or 2, and more preferably 2. Examples of thiuram compounds include tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide, tetrabutylthiuram disulfide, tetrakis(2-ethylhexyl)thiuram disulfide, tetramethylthiuram monosulfide, and dipentamethylenethiuram tetrasulfide.

[0054] Examples of sulfenamide compounds include compounds having a sulfenamide structure. Examples of sulfenamide compounds include N-cyclohexyl-2-benzothiazolylsulfenamide and N-oxydiethylene-2-benzothiazolylsulfenamide. Sulfenamide compounds may also be compounds having both a sulfenamide structure and a thiazole skeleton.

[0055] Examples of thiazole compounds include compounds having a thiazole skeleton (excluding the compounds listed as Compound A), and it is more preferable that they have a benzothiazole skeleton. Examples of thiazole compounds include 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, 2-mercaptobenzothiazole zinc salt, cyclohexylamine salt of 2-mercaptobenzothiazole, 2-(4'-morpholinodithio)benzothiazole, N-cyclohexylbenzothiazole-2-sulfenamide, N-cyclohexyl-2-benzothiazolylsulfenamide, and N-oxydiethylene-2-benzothiazolylsulfenamide. Thiazole compounds may also be compounds having a thiazole skeleton and a sulfenamide structure.

[0056] The rubber composition according to one embodiment of the present invention may also contain other vulcanization accelerators other than thiourea compounds, thiram compounds, thiazole compounds, and sulfenamide compounds. Examples of other vulcanization accelerators include dithiocarbamate compounds, guanidine compounds, xanthogenic acid compounds, and benzimidazole compounds.

[0057] Examples of dithiocarbamate compounds include sodium dibutyldithiocarbamate, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc N-ethyl-N-phenyldithiocarbamate, zinc N-pentamethylenedithiocarbamate, copper dimethyldithiocarbamate, ferric dimethyldithiocarbamate, and tellurium diethyldithiocarbamate. Examples of guanidine compounds include 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, and di-o-tolylguanidine salts of dicatecholborate. Examples of xanthogenic salt compounds include zinc butylxanthonate and zinc isopropylxanthonate. Examples of benzimidazole compounds include compounds having a benzimidazole skeleton. Examples of benzimidazole compounds include 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, and zinc salts of 2-mercaptomethylbenzimidazole.

[0058] A rubber composition according to one embodiment of the present invention preferably contains any one selected from a thiourea compound, 3-methyl-thiazoldin-2-thion, and a thiadiazole compound, and any one selected from a thiram compound, a thiazole compound, and a sulfenamide compound, and more preferably the total content of the thiourea compound, 3-methyl-thiazoldin-2-thion, and the thiadiazole compound is within the above numerical range, and the total content of the thiram compound, the thiazole compound, and the sulfenamide compound is within the above numerical range.

[0059] 1.7 Metal Oxides A rubber composition according to one embodiment of the present invention may contain a metal oxide. The metal oxide can function as an acid acceptor and / or as an acid acceptor. Examples of metal oxides include zinc oxide, magnesium oxide, lead oxide, trilead tetroxide, iron oxide, titanium dioxide, calcium oxide, and the like. The metal oxide preferably contains at least one of zinc oxide and magnesium oxide, and may contain both zinc oxide and magnesium oxide.

[0060] The rubber composition according to one embodiment of the present invention may contain 0.1 to 15.0 parts by mass of metal oxide per 100 parts by mass of rubber contained in the rubber composition, and more preferably 0.5 to 10.0 parts by mass. The content of the metal oxide is, for example, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0, and 15.0 parts by mass, and may be within the range of any two of the values ​​exemplified herein.

[0061] A rubber composition according to one embodiment of the present invention may contain zinc oxide. Zinc oxide can function as an acid acceptor and / or as an acid acceptor. A rubber composition according to one embodiment of the present invention may contain 0.1 to 10.0 parts by mass of zinc oxide per 100 parts by mass of rubber contained in the rubber composition, and more preferably 0.5 to 5.0 parts by mass. The zinc oxide content may be, for example, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, or 10.0 parts by mass, and may be within the range of any two of the values ​​exemplified herein.

[0062] A rubber composition according to one embodiment of the present invention may contain metal oxides other than zinc oxide. The metal oxides other than zinc oxide can function as acid acceptors. A rubber composition according to one embodiment of the present invention may contain 0.1 to 10.0 parts by mass of metal oxides other than zinc oxide per 100 parts by mass of rubber contained in the rubber composition, and more preferably 0.5 to 5.0 parts by mass. The content of metal oxides other than zinc oxide may be, for example, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, or 10.0 parts by mass, and may be within the range of any two of the values ​​exemplified here.

[0063] 1.8 Plasticizers The rubber composition according to one embodiment of the present invention may contain a plasticizer. The plasticizer is preferably a plasticizer compatible with chloroprene rubber and / or butyl rubber, and more preferably a plasticizer compatible with both chloroprene rubber and butyl rubber. Examples of plasticizers include 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, paraffinic oils, etc. These can be used individually or in combination of two or more.

[0064] A rubber composition according to one embodiment of the present invention may contain 0 to 50 parts by mass of plasticizer per 100 parts by mass of rubber contained in the rubber composition. The plasticizer content may be, for example, 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50 parts by mass, and may be within the range of any two of the values ​​exemplified herein.

[0065] A rubber composition according to one embodiment of the present invention preferably contains compound A having at least one ester structure and a molecular weight of 300 to 1000. Compound A can be a plasticizer. Compound A preferably contains DOS (dioctyl sebacate), DBS (dibutyl sebacate), DOA (bis(2-ethylhexyl) adipate), DOZ (bis(2-ethylhexyl) azelaate), DINA (diisononyl adipate), DIDA (diisodecyl adipate), and DOP (bis(2-ethylhexyl) phthalate), and more preferably contains at least DOS (dioctyl sebacate). Compound A that satisfies the above requirements has particularly excellent affinity with chloroprene-based rubber and butyl-based rubber, and can further improve the properties of the resulting vulcanized product and vulcanized molded article. Compound A has at least one ester structure, and may have two or more. Compound A has a molecular weight (weight-average molecular weight) of 300 to 1000, preferably 300 to 700. The molecular weight of compound A may be, for example, 300, 400, 500, 600, 700, 800, 900, or 1000, and may be within the range of any two of the values ​​exemplified here.

[0066] A rubber composition according to one embodiment of the present invention contains compound A in proportion to 100 parts by mass of rubber contained in the rubber composition. It can contain 1 to 30 parts by mass. The content of compound A may be, for example, 0, 5, 10, 15, 20, 25, or 30 parts by mass, and may be within the range of any two of the values ​​exemplified here.

[0067] 1.9 Filler A rubber composition according to one embodiment of the present invention may contain fillers. Examples of fillers include furnace carbon black such as SAF, ISAF, HAF, EPC, XCF, FEF, GPF, HMF, and SRF; modified carbon black such as hydrophilic carbon black; channel black, fume black, thermal carbon such as FT and MT; acetylene black; Ketjen black; silica; clay; talc; and calcium carbonate. A rubber composition according to one embodiment of the present invention may contain one or more types of fillers.

[0068] The rubber composition according to one embodiment of the present invention may contain a total of 20 to 90 parts by mass of filler per 100 parts by mass of rubber contained in the rubber composition, preferably 35 to 80 parts by mass. The filler content may be, for example, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, or 90 parts by mass, and may be within the range of any two of the values ​​exemplified herein. The rubber composition according to one embodiment of the present invention can adjust the hardness of vulcanized products and vulcanized molded articles by including the filler content within the above numerical range.

[0069] 1.10 Lubricants and processing aids The rubber composition according to the present invention may further contain a lubricant and / or processing aid. The lubricant and processing aid are added mainly to improve processability, such as making it easier for the rubber composition to peel off rolls, molds, extruder screws, etc. Examples of lubricants and processing aids include fatty acids such as stearic acid, paraffin-based processing aids such as polyethylene, fatty acid amides, petrolatum, and Factis. The rubber composition according to one embodiment of the present invention may contain one or more types of lubricants and / or processing aids.

[0070] The rubber composition according to the present invention may contain a total of 0 to 15 parts by mass of lubricants and processing aids per 100 parts by mass of rubber contained in the rubber composition, and may also contain 1 to 10 parts by mass. The total content of lubricants and processing aids may be, for example, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 parts by mass, and may be within the range of any two of the values ​​exemplified herein. The rubber composition according to the present invention may also not contain lubricants and / or processing aids.

[0071] 1.11 Others In addition to the components described above, the rubber composition according to the present invention may further contain components such as organic peroxides, silane coupling agents, co-crosslinking agents (e.g., maleimide compounds), stabilizers, flame retardants, and vulcanization retardants, to the extent that they do not impede the effects of the present invention. Examples of anti-aging agents and antioxidants include ozone anti-aging agents, phenolic anti-aging agents, amine anti-aging agents, acrylate anti-aging agents, waxes, and phosphorus anti-aging agents. An example of an amine anti-aging agent is 4,4'-bis(α,α-dimethylbenzyl)diphenylamine. The rubber composition according to the present invention may contain a total of 0.1 to 10 parts by mass of anti-aging agents and antioxidants per 100 parts by mass of rubber contained in the rubber composition.

[0072] 2. Method for producing rubber composition A rubber composition according to one embodiment of the present invention is obtained by kneading rubber and other required components at a temperature below the vulcanization temperature. A method for producing a rubber composition according to one embodiment of the present invention may include a mixing step of mixing rubber and other required components at a temperature below the vulcanization temperature. Examples of kneading equipment include conventionally known kneading equipment such as mixers, Banbury mixers, kneader mixers, and open rolls.

[0073] 3. Properties of rubber compositions The rubber composition according to the ACT preferably has the following properties.

[0074] <Hardness of vulcanized molded products> The rubber composition according to one embodiment of the present invention has a durometer hardness (Type A) of a vulcanized molded article of the rubber composition that can be 30 to 90, preferably 40 to 80. The durometer hardness (Type A) of a vulcanized molded article of the rubber composition can be, for example, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, or 90, and may be within the range of any two of the values ​​exemplified herein.

[0075] <Gas barrier properties of vulcanized molded products> In one embodiment of the present invention, the air permeability index of the vulcanized molded article of the rubber composition is preferably 160 or less, relative to the air permeability index of 100 for a vulcanized molded article of a rubber composition containing only butyl rubber. The air permeability index relative to the air permeability index of 100 for a vulcanized molded article of a rubber composition containing only butyl rubber is, for example, 90, 100, 110, 120, 130, 140, 150, 160, and may be within the range of any two of the values ​​exemplified here. <Heat resistance of vulcanized molded products> A rubber composition according to one embodiment of the present invention has an elongation at break EB0 measured according to JIS K 6251 for a vulcanized molded body of the rubber composition, and an elongation at break EB0 measured according to JIS K 6251 after the vulcanized molded body is heated at 150°C for 72 hours. i The change in elongation at break, ΔEB, which is the difference between -65 and -0, is preferably between -65 and -0. ΔEB may be, for example, -65, -60, -55, -50, -45, -40, -35, -30, -25, -20, -15, -10, -5, or 0, and may be within the range of any two of the values ​​exemplified here.

[0076] <Oil resistance of vulcanized molded products> In one embodiment of the present invention, the rubber composition preferably has a volume change rate ΔV of 0 to 340 before and after immersion of a vulcanized molded article of the rubber composition in a test oil (high-lubricating oil for automobiles, ASTM No. 3, IRM 903 oil) at 130°C for 72 hours. The volume change rate ΔV is, for example, 0, 10, 20, 30, 40, 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, 310, 320, 330, 340, and may be within the range of any two of the values ​​exemplified here.

[0077] <Flexural fatigue resistance of vulcanized molded articles> In one embodiment of the present invention, when a dematcher bending fatigue test is performed using a vulcanized molded article of the rubber composition, under conditions of a stroke of 58 mm, a speed of 300 ± 10 rpm, and room temperature, based on JIS K 6260, it is preferable that the number of bending tests at the time of crack occurrence is 1.5 million or more. The number of bending tests at the time of crack occurrence may be, for example, 1.5 million, 2 million, 2.5 million, 3 million, 3 million, 4 million, 4 million, 5 million, 5 million, 6 million, 6 million, 7 million, 7 million, 8 million, 8 million, 9 million, 9 million, or 10 million, and may be within the range of any two of the values ​​exemplified here.

[0078] <Dynamic heat generation of vulcanized molded articles> In one embodiment of the present invention, when a constant strain flexometer test is performed using a vulcanized molded article of the rubber composition, under the conditions of 55°C, strain of 0.175 inches, load of 55 pounds, and vibration frequency of 1,800 cycles per minute, in accordance with JIS K 6265:2018, the measured heat generation is preferably between 0 and 70°C. The heat generation may be, for example, 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, or 70°C, and may be within the range of any two of the values ​​exemplified herein.

[0079] The properties of the above rubber composition can be determined by the values ​​obtained when the rubber composition is vulcanized into a molded article using the conditions and methods described in the Examples, and measured using the method described in the Examples. Furthermore, the properties of the vulcanized molded article of the rubber composition can be controlled by adjusting the type and amount of rubber composition compounding. For example, the flexural fatigue resistance of the vulcanized molded article can be adjusted by adjusting the amount of chloroprene-based rubber compounding and the amount of unsaturated nitrile monomer units contained in the chloroprene-based rubber.

[0080] 4. Unvulcanized molded articles, vulcanized articles, and vulcanized molded articles An unvulcanized molded article according to one embodiment of the present invention uses a rubber composition according to one embodiment of the present invention and is a molded article of the rubber composition (unvulcanized state) according to one embodiment of the present invention. A method for manufacturing an unvulcanized molded article according to one embodiment of the present invention comprises a step of molding the rubber composition (unvulcanized state) according to one embodiment of the present invention. An unvulcanized molded article according to one embodiment of the present invention consists of the rubber composition (unvulcanized state) according to one embodiment of the present invention.

[0081] A vulcanized product according to one embodiment of the present invention is a vulcanized product of a rubber composition according to one embodiment of the present invention. A method for producing a vulcanized product according to one embodiment of the present invention comprises the step of vulcanizing a rubber composition according to one embodiment of the present invention.

[0082] A vulcanized molded article according to one embodiment of the present invention is a vulcanized molded article of a rubber composition according to one embodiment of the present invention. A vulcanized molded article according to one embodiment of the present invention uses a vulcanized product according to one embodiment of the present invention and is a molded article (molded product) of a vulcanized product according to one embodiment of the present invention. A vulcanized molded article according to one embodiment of the present invention consists of a vulcanized product according to one embodiment of the present invention.

[0083] A vulcanized molded article according to one embodiment of the present invention can be obtained by molding a vulcanized product obtained by vulcanizing a rubber composition (unvulcanized state) according to one embodiment of the present invention, or by vulcanizing a molded article obtained by molding a rubber composition (unvulcanized state) according to one embodiment of the present invention. A vulcanized molded article according to one embodiment of the present invention can be obtained by vulcanizing a rubber composition according to one embodiment of the present invention after molding or during molding. A method for manufacturing a vulcanized molded article according to one embodiment of the present invention comprises the steps of molding a vulcanized product according to one embodiment of the present invention, or vulcanizing an unvulcanized molded article according to one embodiment of the present invention.

[0084] A vulcanized molded article according to one embodiment of the present invention preferably has the hardness, gas barrier properties, heat resistance, oil resistance, flexural fatigue resistance, and / or dynamic heat generation properties described above.

[0085] The unvulcanized molded articles, vulcanized articles, and vulcanized molded articles according to this embodiment can be used as rubber parts in various industrial fields such as buildings, structures, ships, railways, coal mines, and automobiles, and can be used in known applications such as rubber components for automobiles (e.g., automotive sealing materials), hose materials, rubber molds, gaskets, rubber rolls, industrial cables, industrial conveyor belts, and sponges. The vulcanized articles and vulcanized molded articles according to the present invention have excellent gas barrier properties, flexural fatigue resistance, and heat resistance, and can be used as various components in which these properties are particularly required. As an example, the vulcanized articles and vulcanized molded articles according to one embodiment of the present invention can be suitably used as materials for tire inner liners, tubes, curing bladders, pharmaceutical rubber stoppers, wire coatings, vibration damping materials, hoses, linings, condenser packings, gaskets, etc., and can be suitably used in applications in which particularly excellent gas barrier properties are required, such as tire inner liners, tubes, and curing bladders.

[0086] (Components for automobile tires, components for tire manufacturing) Examples of components for automobile tires and tire manufacturing include tire inner liners, tubes, and curing bladders. A tire inner liner is a rubber sheet that replaces the tube and is attached to the inside of a tubeless tire. By attaching the inner liner, air leakage is prevented and the tire pressure is maintained. A curing bladder is a jig used in the molding of tires. During tire molding, the prototype of the tire is placed in a mold, and the bladder is placed in the cavity of the tire. The bladder is inflated, and the tire is pressed against the mold, pressurized, and heated to mold and vulcanize the tire. The vulcanized products and vulcanized molded articles obtained from the rubber composition according to the present invention have excellent gas barrier properties, flexural fatigue resistance, and heat resistance. Therefore, it is possible to manufacture highly reliable and long-lasting components such as tire inner liners, tubes, and curing bladders that can withstand repeated deformation while maintaining the gas barrier properties and heat resistance required for these applications.

[0087] (Rubber components for automobiles) Automotive rubber components include gaskets, oil seals, and packings, which are parts used in machinery and equipment to prevent leakage of liquids and gases, and to prevent the intrusion of dirt and foreign matter such as rainwater and dust. Specifically, there are gaskets used for fixed applications, and oil seals and packings used in moving parts. For gaskets where the sealing part is fixed with bolts, various materials are used depending on the purpose, in addition to soft gaskets such as O-rings and rubber sheets. Packings are used in rotating parts such as the shafts of pumps and motors and the movable parts of valves, reciprocating parts such as pistons, coupler connections, and water-stopping parts of water faucets. The rubber composition of the present invention can enhance gas barrier properties, flexural fatigue resistance, and heat resistance. This makes it possible to manufacture highly reliable, long-life automotive rubber components that can withstand repeated deformation while maintaining gas barrier properties and heat resistance, which was difficult with conventional rubber compositions.

[0088] (Hose material) Hose materials are flexible tubes, and specifically include high and low-pressure hoses for water, oil, air, steam, and hydraulics. The rubber composition of the present invention can improve the gas barrier properties, bending fatigue resistance, and heat resistance of hose materials while maintaining the processability of the unvulcanized material. As a result, it is possible to manufacture highly reliable, long-lasting hose materials that can withstand repeated deformation while maintaining gas barrier properties and heat resistance, which was difficult with conventional rubber compositions.

[0089] (Rubber molded object) Rubber-shaped products include vibration-damping rubber, vibration-damping materials, and boots. Vibration-damping rubber and vibration-damping materials are rubber that prevents the transmission and propagation of vibrations. Specifically, they include torsional dampers, engine mounts, and muffler hangers for automobiles and various other vehicles that absorb vibrations during engine operation and prevent noise. The rubber composition of the present invention can improve the gas barrier properties, flexural fatigue resistance, and heat resistance of vibration-damping rubber and vibration-damping materials. This makes it possible to manufacture vibration-damping rubber and vibration-damping materials that can be used for long periods even in harsh environments, which was difficult with conventional rubber compositions. Furthermore, boots are bellows-shaped components whose outer diameter gradually increases from one end to the other. Specifically, examples include constant velocity joint cover boots, ball joint cover boots (dust cover boots), and rack and pinion gear boots for protecting drive components such as automobile drive systems. The rubber composition of the present invention can enhance gas barrier properties, flexural fatigue resistance, and heat resistance. This makes it possible to manufacture boots that can be used for longer periods even in harsher environments than conventional rubber compositions.

[0090] (Gaskets, etc.) Gaskets, oil seals, and packings are components in machinery and equipment that prevent leakage of liquids and gases, as well as the intrusion of dirt and foreign matter such as rainwater and dust. Specifically, there are gaskets used for fixed applications and oil seals and packings used in moving parts. For gaskets where the sealing portion is fixed with bolts, various materials are used depending on the purpose, as opposed to soft gaskets such as O-rings and rubber sheets. Packings are used in rotating parts such as the shafts of pumps and motors and the movable parts of valves, reciprocating parts such as pistons, coupler connections, and water-stopping parts of water faucets. The rubber composition of the present invention can improve the gas barrier properties, flexural fatigue resistance, and heat resistance of these components. This makes it possible to manufacture highly reliable, long-life seals that can withstand repeated deformation while maintaining gas barrier properties and heat resistance, which was difficult with conventional rubber compositions.

[0091] (Rubber roll) Rubber rolls are manufactured by bonding and covering a metal core, such as an iron core, with rubber. Generally, they are manufactured by spirally winding a rubber sheet around a metal core. Rubber rolls are made from various rubber materials such as NBR, EPDM, and CR, depending on the required characteristics for various applications, including papermaking, various metal manufacturing, film manufacturing, printing, general industrial use, agricultural machinery such as rice hulling machines, and food processing. CR is used in a wide range of rubber roll applications because it has good mechanical strength that can withstand the friction of the objects being conveyed. Furthermore, rubber rolls that convey heavy objects have the problem of deforming under load, and improvements are needed. The rubber composition of the present invention can improve the gas barrier properties, flexural fatigue resistance, and heat resistance of rubber rolls. This makes it possible to manufacture embossing rubber rolls that can be used for long periods even in harsh environments, which was difficult with conventional rubber compositions.

[0092] (Industrial cables) Industrial cables are linear components used to transmit electrical and optical signals. They consist of good conductors such as copper or copper alloys, or optical fibers, covered with an insulating coating layer. A wide variety of industrial cables are manufactured depending on their structure and installation location. The rubber composition of the present invention can improve the gas barrier properties, bending fatigue resistance, and heat resistance of industrial cables. This makes it possible to manufacture highly reliable, long-life industrial cables that can withstand repeated deformation while maintaining gas barrier properties and heat resistance, which were difficult to achieve with conventional rubber compositions.

[0093] (Industrial conveyor belt) Industrial conveyor belts are available in rubber, resin, and metal, and are selected according to a wide variety of applications. Among these, rubber conveyor belts are inexpensive and widely used, but they are prone to deterioration and damage, especially in environments with high friction and collision with conveyed materials. The rubber composition of the present invention can improve the gas barrier properties, flexural fatigue resistance, and heat resistance of industrial conveyor belts. This makes it possible to manufacture industrial conveyor belts that can be used for long periods even in harsh environments, which was difficult with conventional rubber compositions.

[0094] (sponge) Sponge is a porous material with countless fine pores inside, and is specifically used in vibration damping materials, sponge seal components, wetsuits, shoes, and the like. The rubber composition of the present invention can improve the gas barrier properties, flexural fatigue resistance, and heat resistance of sponge. Furthermore, because it uses chloroprene-based rubber, it can also improve the flame retardancy of the sponge. This makes it possible to manufacture sponges that can be used for long periods even in harsh environments, which was difficult with conventional rubber compositions, and sponges with excellent flame retardancy. In addition, the hardness of the resulting sponge can be adjusted as appropriate by adjusting the content of the foaming agent, etc.

[0095] Methods for forming the rubber composition (unvulcanized) and vulcanized product according to this embodiment include press molding, extrusion molding, and calendering. The temperature for vulcanizing the rubber composition can be set appropriately according to the composition of the rubber composition, and may be 140 to 220°C or 160 to 190°C. The vulcanization time for vulcanizing the rubber composition can be set appropriately depending on the composition of the rubber composition, the shape of the unvulcanized molded product, etc. [Examples]

[0096] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0097] <Method for producing chloroprene rubber (acrylonitrile (AN) 10% by mass)> In a 3L polymerization vessel equipped with a heating / cooling jacket and a stirrer, 24 parts by mass of chloroprene (monomer), 24 parts by mass of acrylonitrile (monomer), 0.5 parts by mass of diethylxanthogen disulfide, 200 parts by mass of pure water, 5.00 parts by mass of potassium rosinate (manufactured by Harima Chemicals, Inc.), 0.40 parts by mass of sodium hydroxide, and 2.0 parts by mass of sodium salt of β-naphthalene sulfonic acid formalin condensate (manufactured by Kao Corporation) were added. Next, 0.1 parts by mass of potassium persulfate was added as a polymerization initiator, and emulsion polymerization was carried out at a polymerization temperature of 40°C under a nitrogen atmosphere. The chloroprene was added in small amounts starting 20 seconds after the start of polymerization, and the addition flow rate was adjusted using a solenoid valve based on the change in the heat quantity of the refrigerant during the first 10 seconds of polymerization, and then readjusted every 10 seconds thereafter to continue the process. When the polymerization rate reached 50% of the total amount of chloroprene and acrylonitrile, 0.02 parts by mass of phenothiazine, a polymerization inhibitor, was added to stop the polymerization. Subsequently, unreacted monomers were removed from the reaction solution under reduced pressure to obtain a chloroprene-based rubber latex containing the chloroprene-acrylonitrile copolymer.

[0098] The polymerization rate [%] of chloroprene latex mentioned above was calculated from the dry mass of the chloroprene latex after air drying. Specifically, it was calculated using the following formula (A). In the formula, "solid content concentration" is the concentration of solids [mass %] obtained by heating 2 g of sampled chloroprene latex at 130°C and removing volatile components such as solvent (water), volatile chemicals, and raw materials. "Total amount charged" is the total amount [g] of raw materials, reagents, and solvent (water) charged into the polymerization tank from the start of polymerization to a certain time. "Evaporation residue" is the mass [g] of chemicals [g] that remain as solids with the polymer without volatilizing under 130°C conditions, out of the chemicals and raw materials charged from the start of polymerization to a certain time. "Amount of monomer charged" is the sum of the amount [g] of monomers initially charged into the polymerization tank and the amount of monomers added from the start of polymerization to a certain time. Here, "monomer" refers to the total amount of chloroprene and acrylonitrile. Polymerization rate = {[(Total amount charged × Solid content concentration / 100) - Evaporation residue] / Amount of monomer charged} × 100 ... (A)

[0099] The monomer content of acrylonitrile in chloroprene-based rubber was calculated from the nitrogen atom content in chloroprene-acrylonitrile copolymer rubber. Specifically, the nitrogen atom content in 100 mg of chloroprene-based rubber A-2 was measured using an elemental analyzer (Sumigraph 220F: manufactured by Sumika Analysis Center Co., Ltd.), and the monomer content of acrylonitrile was calculated.

[0100] The elemental analysis described above was performed as follows: The electric furnace temperatures were set to 900°C for the reactor, 600°C for the reduction furnace, 70°C for the column, and 100°C for the detector. Oxygen gas was flowed at 0.2 mL / min as the combustion gas, and helium gas at 80 mL / min as the carrier gas. A calibration curve was created using aspartic acid (10.52%) with a known nitrogen content as the standard substance. The monomer content of acrylonitrile in the chloroprene-based rubber obtained by the above manufacturing method was 10.0% by mass (chloroprene-based rubber AN 10%).

[0101] <Method for manufacturing chloroprene rubber> By changing the amount of acrylonitrile monomer added during the polymerization process, we obtained chloroprene rubber AN5%, in which the acrylonitrile monomer unit content in the chloroprene rubber was 5.0% by mass, and chloroprene rubber AN20%, in which the acrylonitrile monomer unit content was 20.0% by mass.

[0102] <Preparation of rubber composition> The rubber compositions of the examples and comparative examples were obtained by mixing each component according to the formulations described in Tables 1 to 3 and kneading them in an 8-inch open roll.

[0103] The components used to obtain the rubber composition are as follows: (Chloroprene-based rubber) Acrylonitrile-containing chloroprene rubber: The above-mentioned chloroprene-acrylonitrile copolymer rubber (chloroprene-based rubber AN 5%, chloroprene-based rubber AN 10%, chloroprene-based rubber AN 20%) Unsaturated nitrile-free chloroprene rubber: "M-42" manufactured by Denka Co., Ltd.

[0104] (Butyl rubber) Halogenated butyl rubber CIIR1066: Chlorinated butyl rubber, manufactured by ENEOS Material Co., Ltd., CIIR1066, Cl 1.2% by mass BIIR2244: Brominated butyl rubber, manufactured by ENEOS Material Co., Ltd., BIIR2244, Br 2.0% by mass Non-halogenated butyl rubber RIIR268: Regular butyl rubber, manufactured by ENEOS Material Co., Ltd., RIIR 268, isoprene 1.7 mol%,

[0105] (Vulcanization accelerator) Thiourea compounds Accel 22S: Manufactured by Kawaguchi Chemical Industry Co., Ltd., ethylene thiourea Noxellar TMU: Manufactured by Ouchi Shinko Chemical Industry Co., Ltd., trimethylthiourea 3-Methyl-thiazoldin-2-thion: Manufactured by Lanxess, Renogran MTT-80 Thiazole compounds Noxellar DM: Di-2-benzothiazolyl disulfide, manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Thiadianazole compounds MIXLAND+SD 75 GA F250: Manufactured by MLPC International, di(5-mercapto-1,3,4-thiadiazole-2-yl) disulfide Thiuram compounds Noxellar TT: Manufactured by Ouchi Shinko Chemical Industry Co., Ltd., tetramethylthiuram disulfide Sulfenamide compounds Noxellar CZ: Manufactured by Ouchi Shinko Chemical Industry Co., Ltd., N-cyclohexyl-2-benzothiazolyl sulfenamide (Vulcanizing agent) Sulfur: Manufactured by Hosoi Chemical Industry Co., Ltd., finely powdered sulfur, 200 mesh. (Plasticizer) DOS: Manufactured by Shin-Nippon Rika Co., Ltd., Sanso-sizer DOS, di-2-ethylhexyl sebacate, molecular weight 427

[0106] [ka] Castor oil: Industrial grade No. 1 castor oil, manufactured by Fukoku Oil Co., Ltd.

[0107] (filling material) FEF: Carbon Black, manufactured by Asahi Carbon Co., Ltd., Asahi #60UG

[0108] (Metal oxides) Kyowa Mag 150: Manufactured by Kyowa Chemical Industry Co., Ltd., magnesium oxide. Zinc oxide (2 types): Manufactured by Sakai Chemical Industry Co., Ltd., zinc oxide,

[0109] (Lubricant) Stearic acid: Manufactured by Shin-Nippon Rika Co., Ltd., Stearic acid 50S

[0110] (Anti-aging agent) Nocrack CD: Manufactured by Ouchi Shinko Chemical Industry Co., Ltd., 4,4'-bis(α,α-dimethylbenzyl)diphenylamine

[0111] <Hardness (Type A Durometer)> The obtained rubber composition was press-vulcanized at 170°C for 20 minutes according to JIS K 6299 to produce a 2 mm thick sheet-like vulcanized molded article. The obtained sheet-like vulcanized molded article was measured for durometer hardness (Type A) as specified in JIS K 6253 using a GS-610 (manufactured by Teclock Co., Ltd.). The results are shown in Tables 1 to 3.

[0112] <Gas barrier properties> A 2 mm thick vulcanized sheet was prepared by press vulcanizing the obtained rubber composition at 170°C for 20 minutes according to JIS K 6299. The air permeability of the obtained vulcanized sheet was measured at 25°C using an air permeability tester M-C1 (manufactured by Toyo Seiki Co., Ltd.). The air permeability (JIS K 6275-1:2022) is shown as an index, with the air permeability of the vulcanized sheet of Comparative Example 4 set to 100. A smaller index indicates lower air permeability and better gas barrier properties.

[0113] <Heat resistance (change in elongation when cut after heating)> The obtained rubber composition was press-vulcanized at 170°C for 20 minutes according to JIS K 6299 to produce a 2 mm thick sheet-like vulcanized molded body. The obtained sheet-like vulcanized molded body was molded into a dumbbell-shaped test piece (Type 3), and the elongation at break (EB0) was measured according to JIS K 6251. Next, the vulcanized molded body was heated at 150°C for 72 hours, and the elongation at break (EB0) was measured again according to JIS K 6251. i The following measurements were taken. The change in elongation at break (ΔEB) before and after the heat resistance test was calculated from the elongation at break (EB0) before heating and the elongation at break (EBi) after heating.

[0114] <Oil resistance> A 2 mm thick vulcanized sheet was prepared by press-vulcanizing the obtained rubber composition at 170°C for 20 minutes, according to JIS K 6299. Test specimens measuring 25 mm in length and 20 mm in width were punched out from the sheet-like vulcanized molded body. The obtained test specimens were immersed in a test oil (high-lubricating oil for automobiles, ASTM No. 3, IRM 903 oil) at 130°C for 72 hours. The volume change rate ΔV was calculated in accordance with JIS K 6258.

[0115] <Flexural fatigue resistance> The obtained rubber composition was press-vulcanized at 170°C for 20 minutes to produce a vulcanized molded article for dematcher flexural fatigue testing. Using the obtained vulcanized article, a dematcher flexural fatigue test was performed according to JIS K 6260. Under conditions of a stroke of 58 mm, a speed of 300 ± 10 rpm, and room temperature, the number of flexural tests (in tens of thousands) at which cracks occurred was measured to evaluate flexural fatigue resistance. Measurements were performed up to 5 million cycles. The number of flexural tests at which cracks occurred was evaluated according to the following criteria.

[0116] <Dynamic heating properties> A rubber composition was press-vulcanized at 170°C for 20 minutes to obtain a cylindrical vulcanized molded body with a diameter of 15 mm and a height of 25 mm. Based on JIS K 6265:2018, the heat generation was evaluated using a Goodrich Flexometer and a constant strain flexometer test. The constant strain flexometer test is a test method for evaluating the fatigue characteristics due to heat generation inside a test piece by applying a dynamic repeated load to a test piece such as vulcanized rubber. Specifically, a static initial load is applied to the test piece under constant temperature conditions, and then a sinusoidal vibration of constant amplitude is applied, and the amount of heat generation and creep of the test piece that changes over time is measured. The test method was based on JIS K 6265:2018 and was carried out under conditions of 55°C, strain of 0.175 inches, load of 55 pounds, and vibration frequency of 1,800 times per minute, and the heat generation (°C) was measured.

[0117] [Table 1]

[0118] Table 2

[0119] Table 3

Claims

1. A rubber composition comprising chloroprene rubber and butyl rubber, The rubber composition contains 0.1 to 99 parts by mass of the chloroprene-based rubber with respect to 100 parts by mass of the rubber contained in the rubber composition. The chloroprene-based rubber contains chloroprene-based rubber containing unsaturated nitrile monomer units. Rubber composition.

2. The rubber composition according to claim 1, wherein the rubber composition contains a total of 0.1 to 10.0 parts by mass of a thiourea compound, 3-methyl-thiazoldin-2-thion, and a thiadiazole compound per 100 parts by mass of rubber contained in the rubber composition.

3. The rubber composition according to claim 1 or claim 2, wherein the butyl rubber comprises halogenated butyl rubber.

4. The rubber composition according to claim 1 or claim 2, wherein the rubber composition contains a total of 0.1 to 10.0 parts by mass of a thiuram-based compound, a thiazole-based compound, and a sulfenamide-based compound per 100 parts by mass of rubber contained in the rubber composition.

5. The rubber composition according to claim 1 or claim 2, wherein the chloroprene rubber contains 1 to 25% by mass of unsaturated nitrile monomer units based on 100% by mass of the chloroprene rubber.

6. The rubber composition according to claim 1 or claim 2, wherein the rubber composition contains 1 to 30 parts by mass of compound A having at least one ester structure and a molecular weight of 300 to 1000, per 100 parts by mass of rubber contained in the rubber composition.

7. A vulcanized product of the rubber composition according to claim 1 or claim 2.

8. A vulcanized molded article of the vulcanized product according to claim 7.

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