Chloroprene-unsaturated nitrile copolymer latex, rubber components, rubber compositions, vulcanized molded articles, and methods for producing chloroprene-unsaturated nitrile copolymer latex.

Abstract

The present invention provides a chloroprene-unsaturated nitrile copolymer latex that exhibits excellent storage stability at high temperatures for extended periods, and a chloroprene-unsaturated nitrile copolymer latex in which the rubber component of the chloroprene-unsaturated nitrile copolymer latex is used to provide a rubber composition with excellent oil resistance. [Solution] According to the present invention, a chloroprene-unsaturated nitrile copolymer latex is provided, comprising a chloroprene-unsaturated nitrile copolymer containing chloroprene monomer units and unsaturated nitrile monomer units, wherein the chloroprene-unsaturated nitrile copolymer has a nitrogen content of 0.5% by mass or more as measured by combustion, and the content of hydrolyzed unsaturated nitrile in the chloroprene-unsaturated nitrile copolymer latex is 0.10 to 9.00 parts by mass per 100 parts by mass of the chloroprene-unsaturated nitrile copolymer.

Description

[Technical Field]

[0001] The present invention relates to chloroprene-unsaturated nitrile copolymer latex, rubber components, rubber compositions, vulcanized molded articles, and a method for producing chloroprene-unsaturated nitrile copolymer latex. [Background technology]

[0002] Chloroprene latex and chloroprene rubber, which contain chloroprene polymers, have excellent mechanical properties, ozone resistance, and chemical resistance. These properties make them suitable for a wide range of applications, including automotive parts, adhesives, and various industrial rubber components.

[0003] For example, Patent Document 1 describes a copolymer in which, when the total amount of all monomers is taken as 100% by mass, the fractions of each monomer constituting the polymer consist of 80-97% by mass of 2-chloro-1,3-butadiene (chloroprene) (C-1) and 20-3% by mass of 2,3-dichloro-1,3-butadiene (C-2), or 79.8-96.8% by mass of 2-chloro-1,3-butadiene (chloroprene) (C-1), 20-3% by mass of 2,3-dichloro-1,3-butadiene (C-2), and 0.2-17% by mass of monomers copolymerizable with these (C-3). A chloroprene-based vulcanizable rubber composition is disclosed, comprising 100 parts by mass of a chloroprene-based vulcanizable rubber polymer having a Mooney viscosity (ML1+4 (100℃)) of 100 to 135, 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 antioxidant, 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 softener, 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. Furthermore, Patent Document 2 discloses a rubber composition for flame-retardant hoses that contains a rubber component, carbon black, and silica, wherein the rubber component is either chloroprene rubber only, or chloroprene rubber and styrene-butadiene rubber only.

[0004] Patent Document 3 discloses a statistical copolymer latex containing chloroprene monomer units and unsaturated nitrile monomer units, wherein the unsaturated nitrile monomer unit content is 5 to 20% by mass, and the toluene-insoluble portion of the statistical copolymer obtained by freeze-drying the statistical copolymer latex is 50 to 100% by mass relative to 100% by mass of the statistical copolymer. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2012-211345 [Patent Document 2] Japanese Patent Publication No. 2017-019947 [Patent Document 3] WO2019 / 211975 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, conventional chloroprene latex had room for improvement in its storage stability at high temperatures over long periods. Furthermore, it was difficult to obtain a chloroprene latex that exhibited excellent storage stability at high temperatures over long periods and also had excellent oil resistance in vulcanized molded articles of rubber compositions using the rubber component of said chloroprene latex.

[0007] The present invention has been made in view of these circumstances, and provides a chloroprene-unsaturated nitrile copolymer latex that exhibits excellent storage stability at high temperatures and for long periods of time, and a chloroprene-unsaturated nitrile copolymer latex in which a vulcanized molded article of a rubber composition using the rubber component of the chloroprene-unsaturated nitrile copolymer latex exhibits excellent oil resistance. Furthermore, the present invention provides the rubber component of the chloroprene-unsaturated nitrile copolymer latex, a rubber composition containing the rubber component, a vulcanized molded article of the rubber composition, and a method for producing the chloroprene-unsaturated nitrile copolymer latex. [Means for solving the problem]

[0008] The present invention provides a chloroprene-unsaturated nitrile copolymer latex comprising a chloroprene-unsaturated nitrile copolymer containing chloroprene monomer units and unsaturated nitrile monomer units, wherein the chloroprene-unsaturated nitrile copolymer has a nitrogen content of 0.5% by mass or more as measured by combustion, and the content of hydrolyzed unsaturated nitrile in the chloroprene-unsaturated nitrile copolymer latex is 0.10 to 9.00 parts by mass per 100 parts by mass of the chloroprene-unsaturated nitrile copolymer.

[0009] Through diligent research, the inventors discovered that by adjusting the manufacturing conditions of the chloroprene-unsaturated nitrile copolymer latex, it is possible to control the nitrogen content in the chloroprene-unsaturated nitrile copolymer and the content of hydrolyzed unsaturated nitrile in the chloroprene-unsaturated nitrile copolymer latex, thereby obtaining a chloroprene-unsaturated nitrile copolymer latex with excellent storage stability at high temperatures and for long periods of time, and a chloroprene-unsaturated nitrile copolymer latex with excellent oil resistance in vulcanized molded articles of rubber compositions using the rubber component of the chloroprene-unsaturated nitrile copolymer latex. This led to the completion of the present invention.

[0010] The following are examples of various embodiments of the present invention. The embodiments shown below can be combined with each other. [1] A chloroprene-unsaturated nitrile copolymer latex comprising a chloroprene-unsaturated nitrile copolymer containing chloroprene monomer units and unsaturated nitrile monomer units, wherein the chloroprene-unsaturated nitrile copolymer has a nitrogen content of 0.5% by mass or more as measured by combustion, and the content of hydrolyzed unsaturated nitrile in the chloroprene-unsaturated nitrile copolymer latex is 0.10 to 9.00 parts by mass per 100 parts by mass of the chloroprene-unsaturated nitrile copolymer. [2] The chloroprene-unsaturated nitrile copolymer latex according to [1], wherein the chloroprene-unsaturated nitrile copolymer has a functional group having a structure represented by Chemical Formula (1) or Chemical Formula (2).

[0011] [Chemical formula] (In Chemical Formula (1), R 1 represents any one of hydrogen, chlorine, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted mercapto group, and a substituted or unsubstituted heterocyclyl group.)

[0012] [Chemical formula] [3] The unsaturated nitrile monomer unit is an acrylonitrile monomer unit, the acrylonitrile bond amount measured in accordance with JIS K 6451-1 of the chloroprene-unsaturated nitrile copolymer is 2% by mass or more, and the content of the hydrolyzate of acrylonitrile with respect to 100 parts by mass of the chloroprene-unsaturated nitrile copolymer in the chloroprene-unsaturated nitrile copolymer latex is 0.10 to 9.00 parts by mass. The chloroprene-unsaturated nitrile copolymer latex according to [1] or [2]. [4] The rubber component of the chloroprene-unsaturated nitrile copolymer latex according to any one of [1] to [3]. [5] A rubber composition containing the rubber component according to [4]. [6] A vulcanized molded product of the rubber composition according to [5]. [7] A transmission belt, a conveyor belt, a hose, a wiper, an immersion product, a seal part, an adhesive, a boot, a rubber draw cloth, a rubber roll, an anti-vibration rubber or a sponge product, which is the vulcanized molded product according to [6]. [8] A method for producing a chloroprene-unsaturated nitrile copolymer latex comprising a chloroprene monomer unit and an unsaturated nitrile monomer unit, wherein the production method comprises a polymerization step of polymerizing raw material monomers comprising a chloroprene monomer and an unsaturated nitrile monomer in an aqueous solution containing water to obtain a chloroprene-unsaturated nitrile copolymer, wherein the amount of water is less than 150 parts by mass when the total amount of raw material monomers used in the polymerization step is 100 parts by mass. [Effects of the Invention]

[0013] The chloroprene-unsaturated nitrile copolymer latex according to the present invention exhibits excellent storage stability at high temperatures and for extended periods. Furthermore, a vulcanized molded article of a rubber composition containing the rubber component of the chloroprene-unsaturated nitrile copolymer latex according to the present invention has excellent oil resistance. Because the chloroprene-unsaturated nitrile copolymer latex according to the present invention exhibits excellent storage stability at high temperatures and for extended periods, it can be stored while maintaining excellent quality in its chloroprene-unsaturated nitrile copolymer latex state. Additionally, because a vulcanized molded article of a rubber composition using its rubber component exhibits excellent oil resistance, these properties allow it to be used in a variety of applications and components. [Modes for carrying out the invention]

[0014] The present invention will be described in detail below with reference to embodiments of the present invention. The present invention is not limited in any way by these descriptions. The features of the embodiments of the present invention shown below can be combined with each other. Furthermore, each feature constitutes an invention independently.

[0015] 1. Chloroprene-unsaturated nitrile copolymer latex The chloroprene-unsaturated nitrile copolymer latex according to the present invention contains a chloroprene-unsaturated nitrile copolymer. Furthermore, the chloroprene-unsaturated nitrile copolymer has a nitrogen content of 0.5% by mass or more as measured by combustion, and the content of hydrolyzed unsaturated nitrile in the chloroprene-unsaturated nitrile copolymer latex is 0.10 to 9.00 parts by mass per 100 parts by mass of the chloroprene-unsaturated nitrile copolymer.

[0016] 1.1 Chloroprene-unsaturated nitrile copolymer The chloroprene-unsaturated nitrile copolymer according to the present invention contains chloroprene monomer units and unsaturated nitrile monomer units. That is, the chloroprene-unsaturated nitrile copolymer according to the present invention contains monomer units (monomer units = structural units) derived from chloroprene (2-chloro-1,3-butadiene) and also contains monomer units derived from unsaturated nitrile. The chloroprene-unsaturated nitrile copolymer according to the present invention may have structures derived from monomer units other than chloroprene monomer units and unsaturated nitrile monomer units, to the extent that it does not impair the objective of the present invention.

[0017] 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.

[0018] Examples of unsaturated nitriles include acrylonitrile, methacrylonitrile, ethacrylonitrile, and phenylacrylonitrile. Unsaturated nitriles can be used individually or in combination of two or more. From the viewpoint of easily obtaining excellent moldability and easily obtaining excellent tensile strength, elongation at break, hardness, tear strength, and oil resistance in vulcanized molded articles, it is preferable that the unsaturated nitrile includes acrylonitrile.

[0019] The chloroprene-unsaturated nitrile copolymer according to the present invention has a nitrogen content of 0.5% by mass or more, as measured by combustion. The nitrogen content may be, for example, 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, or 7.0% by mass, and may be within the range of any two of the values ​​exemplified herein.

[0020] The nitrogen content of a chloroprene-unsaturated nitrile copolymer can be determined by analyzing the chloroprene-unsaturated nitrile copolymer, obtained by freeze-drying or methanol precipitation from chloroprene-unsaturated nitrile copolymer latex, using an elemental analyzer after combustion. Specifically, it can be analyzed by the method described in the examples. The nitrogen in the chloroprene-unsaturated nitrile copolymer can originate from the unsaturated nitrile monomer units within the chloroprene-unsaturated nitrile copolymer, and this can be controlled by adjusting the amount of unsaturated nitrile in the raw material monomers during the polymerization of the chloroprene-unsaturated nitrile copolymer.

[0021] In the chloroprene-unsaturated nitrile copolymer according to one embodiment of the present invention, the content of unsaturated nitrile monomer units is preferably 2% by mass or more. The content of unsaturated nitrile monomer units may be, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25% by mass, and may be within the range of any two of the values ​​exemplified herein.

[0022] The chloroprene-unsaturated nitrile copolymer according to one embodiment of the present invention preferably has an acrylonitrile binding amount (content of acrylonitrile monomer units) of 2% by mass or more, as measured in accordance with JIS K 6451-1. The acrylonitrile binding amount (content of acrylonitrile monomer units) may be, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25% by mass, and may be within the range of any two of the values ​​exemplified herein.

[0023] The content of unsaturated nitrile monomer units and acrylonitrile monomer units in the chloroprene-unsaturated nitrile copolymer can be calculated based on the nitrogen content measured by the combustion method. In particular, the amount of acrylonitrile bonded (content of acrylonitrile monomer units) can be calculated based on JIS K 6451-1. Specifically, it can be analyzed by the method described in the examples. By setting the content of unsaturated nitrile monomer units and acrylonitrile monomer units to be above the lower limit, the resulting rubber composition and vulcanized molded articles will have sufficient oil resistance. Furthermore, by setting the content of unsaturated nitrile monomer units and acrylonitrile monomer units to be below the upper limit, the water resistance and cold resistance of the resulting rubber composition and vulcanized molded articles will be further improved.

[0024] The chloroprene-unsaturated nitrile copolymer according to one embodiment of the present invention preferably contains 60 to 100% by mass of chloroprene monomer units when the chloroprene-unsaturated nitrile copolymer is considered to be 100% by mass. The content of chloroprene monomer units in the chloroprene-unsaturated nitrile copolymer is, for example, 60, 65, 70, 75, 80, 85, 90, 95, 99, or 100% by mass, and may be within the range of any two of the values ​​exemplified herein. By setting the content of chloroprene monomer units within the above numerical range, a rubber composition can be obtained that yields a molded article with an excellent balance of hardness, tensile strength, and cold resistance.

[0025] The chloroprene-unsaturated nitrile copolymer according to one embodiment of the present invention may also have monomer units other than chloroprene monomers and unsaturated nitrile monomers. Examples of monomer units other than chloroprene monomers are not particularly limited as long as they are copolymerizable with chloroprene monomers or chloroprene monomers and unsaturated nitrile monomers, but include (meth)acrylic acid esters ((meth)acrylic acid, (meth)acrylic acid, butyl (meth)acrylic acid, 2-ethylhexyl (meth)acrylic acid, 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.

[0026] The chloroprene-unsaturated nitrile copolymer according to one embodiment of the present invention may contain 0 to 20% by mass of monomer units other than chloroprene monomers and unsaturated nitrile monomers when the chloroprene-unsaturated nitrile copolymer is considered to be 100% by mass. The content of monomer units other than chloroprene monomers and unsaturated nitrile monomers in the chloroprene-unsaturated nitrile copolymer 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 here. By adjusting the copolymerization amount of monomers other than chloroprene monomers and unsaturated nitrile monomers within this range, the effects of copolymerizing these monomers can be expressed without impairing the properties of the resulting rubber composition. Furthermore, the chloroprene-unsaturated nitrile copolymer according to one embodiment of the present invention may consist only of chloroprene monomer units and unsaturated nitrile monomer units.

[0027] The chloroprene-unsaturated nitrile copolymer latex according to one embodiment of the present invention may contain one chloroprene-unsaturated nitrile copolymer, or it may contain two or more chloroprene-unsaturated nitrile copolymers. In the case of a chloroprene-unsaturated nitrile copolymer latex according to one embodiment of the present invention, if it contains two or more chloroprene-unsaturated nitrile copolymers, it is preferable that the content rate based on the total mass of total nitrogen, total unsaturated nitrile monomer units, total acrylonitrile monomer units, etc., contained in the two or more chloroprene-unsaturated nitrile copolymers is within the above numerical range, relative to 100% by mass of the total of the two or more chloroprene-unsaturated nitrile copolymers contained in the chloroprene-unsaturated nitrile copolymer latex.

[0028] A chloroprene-unsaturated nitrile copolymer according to one embodiment of the present invention may have a functional group having a structure represented by chemical formula (1) or chemical formula (2).

[0029] [ka]

[0030] In chemical formula (1), R1 represents one of the following: hydrogen, chlorine, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted mercapto group, or a substituted or unsubstituted heterocyclyl group.

[0031] [ka]

[0032] Functional groups with the structure represented by chemical formula (1) or chemical formula (2) can be introduced by carrying out the polymerization step of the chloroprene-unsaturated nitrile copolymer in the presence of a RAFT agent. Compounds that can be used to introduce functional groups with the structure represented by chemical formula (1) or chemical formula (2) will be described later in the section on manufacturing methods. A rubber composition containing a chloroprene-unsaturated nitrile copolymer latex according to one embodiment of the present invention has a sufficiently long scorch time because the chloroprene-unsaturated nitrile copolymer has a functional group having a structure represented by chemical formula (1) or chemical formula (2).

[0033] 1.2 Hydrolyzed products of unsaturated nitriles The chloroprene-unsaturated nitrile copolymer according to the present invention has a content of 0.10 to 9.00 parts by mass of hydrolyzed unsaturated nitrile per 100 parts by mass of chloroprene-unsaturated nitrile copolymer in the chloroprene-unsaturated nitrile copolymer latex. Generally, unsaturated nitriles are thought to be hydrolyzed and decomposed through amides, alcohols, and ethers, ultimately resulting in carboxylic acids and ammonia. In the present invention, the hydrolysates of unsaturated nitriles may include amides, nitriles, alcohols, ethers, carboxylic acids, and ammonia derived from unsaturated nitriles. In the present invention, the hydrolysates of unsaturated nitriles may be compounds derived from unsaturated nitriles, including compounds containing a cyano group, a compound containing an amide group, a compound containing a carboxyl group, and a compound containing an amino group (including ammonia).

[0034] If the unsaturated nitrile is acrylonitrile, the hydrolysis product of the unsaturated nitrile can include acrylamide, 2-cyanoethanol, 2-cyanoethyl ether, acrylic acid, and ammonia. If the unsaturated nitrile is methacrylonitrile, the hydrolysis product of the unsaturated nitrile can include methacrylamide, 3-hydroxy-2-methylpropanenitrile, 3-(2-cyanopropoxy)-2-methylpropanenitrile, methacrylic acid, and ammonia. If it is phenylacrylonitrile, it may contain 3-phenylpropionamide, α-(hydroxymethyl)benzeneacetonitrile, α,α'-[oxybis(methylene)]bis[α-methylbenzeneacetonitrile], 2-phenylpropionic acid, and ammonia, or it may be 3-phenylpropionamide, α-(hydroxymethyl)benzeneacetonitrile, α,α'-[oxybis(methylene)]bis[α-methylbenzeneacetonitrile], 2-phenylpropionic acid, and ammonia.

[0035] The chloroprene-unsaturated nitrile copolymer according to the present invention has a content of hydrolyzed unsaturated nitrile in the chloroprene-unsaturated nitrile copolymer latex of 0.10 to 9.00 parts by mass per 100 parts by mass of the chloroprene-unsaturated nitrile copolymer, for example, 0.10, 0.20, 0.50, 1.00, 1.50, 2.00, 2.50, 3.00, 3.50, 4.00, 4.50, 5.00, 5.50, 6.00, 6.50, 7.00, 7.50, 8.00, 8.50, 9.00% by mass, and may be within the range of any two of the values ​​exemplified herein. Furthermore, the chloroprene-unsaturated nitrile copolymer according to one embodiment of the present invention may have a total content of amides, nitriles, alcohols, ethers, carboxylic acids, and ammonia derived from unsaturated nitrile within the above numerical range, or the content of amides, nitriles, alcohols, and ethers derived from unsaturated nitrile may be within the above numerical range. Furthermore, the chloroprene-unsaturated nitrile copolymer according to one embodiment of the present invention may have a total content of acrylamide, 2-cyanoethanol, 2-cyanoethyl ether, acrylic acid, ammonia, methacrylamide, 3-hydroxy-2-methylpropanenitrile, 3-(2-cyanopropoxy)-2-methylpropanenitrile, methacrylic acid, 3-phenylpropionamide, α-(hydroxymethyl)benzeneacetonitrile, α,α'-[oxybis(methylene)]bis[α-methylbenzeneacetonitrile], and 2-phenylpropionic acid within the above numerical range, and the total content of acrylamide, 2-cyanoethanol, 2-cyanoethyl ether, methacrylamide, 3-hydroxy-2-methylpropanenitrile, 3-(2-cyanopropoxy)-2-methylpropanenitrile, 3-phenylpropionamide, α-(hydroxymethyl)benzeneacetonitrile, and α,α'-[oxybis(methylene)]bis[α-methylbenzeneacetonitrile] within the above numerical range.

[0036] In the chloroprene-unsaturated nitrile copolymer according to the present invention, it is preferable that the content of acrylonitrile hydrolysate per 100 parts by mass of chloroprene-unsaturated nitrile copolymer in the chloroprene-unsaturated nitrile copolymer latex is within the above numerical range. For example, the content of unsaturated nitrile hydrolysate can be the total content of 2-cyanoethanol, 2-cyanoethyl ether, and acrylamide, and the content of acrylonitrile hydrolysate can be the total content of 2-cyanoethanol, 2-cyanoethyl ether, and acrylamide. In the chloroprene-unsaturated nitrile copolymer according to the present invention, it is preferable that the total content of 2-cyanoethanol, 2-cyanoethyl ether, and acrylamide per 100 parts by mass of chloroprene-unsaturated nitrile copolymer in the chloroprene-unsaturated nitrile copolymer latex is within the above numerical range.

[0037] In one embodiment of the present invention, the chloroprene-unsaturated nitrile copolymer can contain 0.05 to 8.00 parts by mass of 2-cyanoethanol per 100 parts by mass of the chloroprene-unsaturated nitrile copolymer in the chloroprene-unsaturated nitrile copolymer latex. The 2-cyanoethanol content can be, for example, 0.05, 0.10, 0.20, 0.50, 1.00, 1.50, 2.00, 2.50, 3.00, 3.50, 4.00, 4.50, 5.00, 5.50, 6.00, 6.50, 7.00, 7.50, or 8.00% by mass, and may be within the range of any two of the values ​​exemplified here.

[0038] In one embodiment of the present invention, the chloroprene-unsaturated nitrile copolymer can contain 0.05 to 8.00 parts by mass of 2-cyanoethyl ether per 100 parts by mass of the chloroprene-unsaturated nitrile copolymer in the chloroprene-unsaturated nitrile copolymer latex. The 2-cyanoethyl ether content may be, for example, 0.05, 0.10, 0.20, 0.50, 1.00, 1.50, 2.00, 2.50, 3.00, 3.50, 4.00, 4.50, 5.00, 5.50, 6.00, 6.50, 7.00, 7.50, or 8.00 parts by mass, and may be within the range of any two of the values ​​exemplified herein.

[0039] The chloroprene-unsaturated nitrile copolymer according to one embodiment of the present invention may have an acrylamide content of 0.05 to 8.00 parts by mass per 100 parts by mass of the chloroprene-unsaturated nitrile copolymer in the chloroprene-unsaturated nitrile copolymer latex. The acrylamide content may be, for example, 0.05, 0.10, 0.20, 0.50, 1.00, 1.50, 2.00, 2.50, 3.00, 3.50, 4.00, 4.50, 5.00, 5.50, 6.00, 6.50, 7.00, 7.50, or 8.00% by mass, and may be within the range of any two of the values ​​exemplified here.

[0040] The chloroprene-unsaturated nitrile copolymer according to one embodiment of the present invention exhibits excellent storage stability at high temperatures for extended periods due to the content of hydrolyzed unsaturated nitrile within the above numerical range, and the vulcanized molded article of the rubber composition containing the rubber component of the chloroprene-unsaturated nitrile copolymer latex has excellent oil resistance. The content of hydrolyzed unsaturated nitrile can be controlled by adjusting the manufacturing conditions during polymerization of the chloroprene-unsaturated nitrile copolymer, particularly the amount of water and alkali relative to the raw material monomers used for polymerization, the type and amount of raw material monomers used in the formulation, the timing of additive addition, the polymerization temperature, and the concentration of each monomer in the polymerization solution.

[0041] The content of hydrolysates of unsaturated nitrile in chloroprene-unsaturated nitrile copolymer latex can be determined by gas chromatography, for example, by analyzing a solution of chloroprene-unsaturated nitrile copolymer latex diluted with tetrahydrofuran using a gas chromatograph (GC) system. Specifically, it can be analyzed by the method described in the examples. Alternatively, since ammonia, one of the hydrolysates of unsaturated nitrile, has a strong pungent odor, its presence or absence can be confirmed by the presence or absence of a pungent odor in the polymerization solution. Also, based on the decomposition mechanism, carboxylic acids are thought to be generated simultaneously with ammonia, so the presence or absence of ammonia generation can be confirmed by the presence or absence of carboxylic acid generation. For example, if the ammonia concentration in chloroprene-unsaturated nitrile copolymer latex is 1 ppm or higher, a pungent odor can be detected in the working environment. For example, the ammonia concentration in chloroprene-unsaturated nitrile copolymer latex can be less than 1 ppm. Furthermore, the ammonia concentration can be analyzed by ion chromatography. Carboxylic acids can also be analyzed by ion chromatography, liquid chromatography, or gas chromatography.

[0042] The chloroprene-unsaturated nitrile copolymer latex according to one embodiment of the present invention may include not only the chloroprene-unsaturated nitrile copolymer and hydrolysates of unsaturated nitriles, but also compounds used during the polymerization of the chloroprene-unsaturated nitrile copolymer.

[0043] 1.3 Properties of Chloroprene-Unsaturated Nitrile Copolymer Latex The chloroprene-unsaturated nitrile copolymer latex according to one embodiment of the present invention can have its solid content concentration adjusted according to the application. The solid content concentration is not particularly limited, but for example, it may be 40, 45, 50, 55, 60, 65, or 70% by mass, and may be within the range of any two of the values ​​exemplified herein.

[0044] When a chloroprene-unsaturated nitrile copolymer latex according to one embodiment of the present invention is adjusted to a solid content concentration of 50% by mass and stored at 40°C for 4 months, it is preferable that the viscosity is less than 1000 cps. The viscosity after storage at 40°C for 4 months may be, for example, 100, 200, 300, 400, 500, 600, 700, 800, 900, or 950 cps, and may be within the range of any two of the values ​​exemplified herein. The viscosity can be measured using a B-type viscometer, and specifically, it can be analyzed by the method described in the examples.

[0045] 2. Method for producing chloroprene-unsaturated nitrile copolymer latex The method for producing the chloroprene-unsaturated nitrile copolymer latex according to the present invention is not particularly limited. A method for producing a chloroprene-unsaturated nitrile copolymer latex containing a chloroprene-unsaturated nitrile copolymer containing chloroprene monomer units and unsaturated nitrile monomer units according to one embodiment of the present invention may include a polymerization step in which raw material monomers containing chloroprene monomers and unsaturated nitrile monomers are polymerized in an aqueous solution containing water to obtain a chloroprene-unsaturated nitrile copolymer. Furthermore, when the total amount of raw material monomers used in the polymerization step is 100 parts by mass, the amount of water can be less than 150 parts by mass.

[0046] In the polymerization process, a chloroprene-unsaturated nitrile copolymer can be obtained by polymerizing raw material monomers, including chloroprene monomer and unsaturated nitrile monomer, in an aqueous solution containing water.

[0047] The raw material monomers include chloroprene monomers and unsaturated nitrile monomers, and may also include other monomers besides chloroprene monomers and unsaturated nitrile monomers. The other monomers are as described above. It is preferable to adjust the blending ratio of each monomer in the raw material monomers so that the content of chloroprene monomer units, unsaturated nitrile monomer units, and other monomer units in the resulting chloroprene-unsaturated nitrile copolymer falls within the numerical range described above.

[0048] The raw material monomers can be partially added initially and partially added after polymerization has begun. For example, the polymerization process may include a first addition step in which at least a portion of the raw material monomers, including chloroprene and unsaturated nitrile, are added, and a second addition step in which the remaining raw material monomers are added.

[0049] In the first addition step according to one embodiment of the present invention, when the total chloroprene monomer added in the polymerization step is 100 parts by mass, at least 10 parts by mass of chloroprene monomer can be added. For example, 10, 20, 30, 40, 50, 60, or 70 parts by mass can be added, and the amount may be within the range of any two of the values ​​exemplified here. Also, in the first addition step, when the total unsaturated nitrile added in the polymerization step is 100 parts by mass, at least 50 parts by mass of unsaturated nitrile can be added. For example, 50, 60, 70, 80, 90, or 100 parts by mass can be added, and the amount may be within the range of any two of the values ​​exemplified here. In the first addition step according to one embodiment of the present invention, the above-mentioned amounts of raw material monomers, emulsifier, and optionally RAFT agent and molecular weight are added to water. After this, a polymerization initiator is added and polymerization is started.

[0050] In the second addition step according to one embodiment of the present invention, when the total chloroprene monomer added in the polymerization step is 100 parts by mass, at least 30 parts by mass of chloroprene monomer can be added. For example, 30, 40, 50, 60, or 70 parts by mass can be added, and the amount may be within the range of any two of the values ​​exemplified here. Also, in the second addition step, when the total unsaturated nitrile added in the polymerization step is 100 parts by mass, 0, 10, 20, or 30 parts by mass of unsaturated nitrile can be added, and the amount may be within the range of any two of the values ​​exemplified here. Unsaturated nitrile does not need to be added in the second addition step. In the second addition step, it is preferable to divide and add the remaining raw material monomer in two or more steps. In the second addition step, the remaining raw material monomer can be divided and added in, for example, 2, 4, 6, 8, 10, 12, 14, 16, 18, or 20 steps, and the number of steps may be within the range of any two of the values ​​exemplified here. Furthermore, in the second additive step, the remaining raw material monomers can be continuously added at a constant flow rate.

[0051] During polymerization, it is preferable to add the raw material monomers in divided portions so that, when the amount of unreacted monomers in the polymerization solution (for example, the sum of chloroprene monomers and acrylonitrile monomers) is 100 parts by mass, the amount of unsaturated nitrile monomers in the polymerization solution is maintained at 20 to 90 parts by mass. The amount of unsaturated nitrile monomers relative to 100 parts by mass of unreacted monomers in the polymerization solution is, 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 here.

[0052] In the polymerization process according to one embodiment of the present invention, when the total amount of raw material monomers used in the polymerization process is 100 parts by mass, the amount of water can be less than 150 parts by mass. The amount of water may be, for example, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, or 149 parts by mass, and may be within the range of any two of the values ​​exemplified here. In the polymerization process according to one embodiment of the present invention, the amount of water used can be reduced compared to conventional manufacturing methods, thereby reducing the amount of hydrolysates produced from unsaturated nitriles. Furthermore, hydrolysates of unsaturated nitriles, such as acrylamide, 2-cyanoethanol, and 2-cyanoethyl ether, place a significant burden on wastewater treatment. Reducing the production of these hydrolysates offers significant advantages from the standpoint of reducing environmental impact and lowering the effort and cost of wastewater treatment.

[0053] There are no particular restrictions on the emulsifier used in emulsion polymerization, and any known emulsifier commonly used in the emulsion polymerization of chloroprene polymers 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).

[0054] The amount of emulsifier added is preferably 0.2 to 20 parts by mass, and more preferably 2 to 10 parts by mass, per 100 parts by mass of the total raw material monomers used in the polymerization process.

[0055] 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 the chloroprene-unsaturated nitrile copolymer.

[0056] As polymerization initiators, known radical polymerization initiators can be used, such as potassium persulfate, benzoyl peroxide, hydrogen peroxide, and azo compounds.

[0057] In the polymerization step according to one embodiment of the present invention, a RAFT agent can be used, and by carrying out polymerization in the presence of a known RAFT agent, terminal structures represented by chemical formula (1) or chemical formula (2) can be introduced into the chloroprene-unsaturated nitrile copolymer.

[0058] [ka]

[0059] In chemical formula (1), R1 represents one of the following: hydrogen, chlorine, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted mercapto group, or a substituted or unsubstituted heterocyclyl group.

[0060] [ka]

[0061] The compounds used to derive the structure represented by the above chemical formula (1) are not particularly limited and can be general compounds, such as dithiocarbamates and dithioesters. Specifically, these include benzyl 1-pyrrole carbodithioate (common name: benzyl 1-pyrrole dithiocarbamate), benzylphenyl carbodithioate, 1-benzyl-N,N-dimethyl-4-aminodithiobenzoate, 1-benzyl-4-methoxydithiobenzoate, 1-phenylethylimidazole carbodithioate (common name: 1-phenylethylimidazole dithiocarbamate), and benzyl-1-(2-pyrrolidinone)carbodithio Oate) (common name: benzyl-1-(2-pyrrolidinone)dithiocarbamate), benzylphthalimidylcarboditioate, (common name: benzylphthalimidyldithiocarbamate), 2-cyanoprop-2-yl-1-pyrrolecarboditioate, (common name: 2-cyanoprop-2-yl-1-pyrroledithiocarbamate), 2-cyanobuto-2-yl-1-pyrrolecarboditioate, (common name: 2-cyanobuto-2-yl- 1-Pyrrole dithiocarbamate), benzyl-1-imidazole carbodithioate (common name benzyl-1-imidazole dithiocarbamate), 2-cyanoprop-2-yl-N,N-dimethyldithiocarbamate, benzyl-N,N-diethyldithiocarbamate, cyanomethyl-1-(2-pyrrolidone)dithiocarbamate, 2-(ethoxycarbonylbenzyl)prop-2-yl-N,N-diethyldithiocarbamate, 1-Fe Nylethyldithiobenzoate, 2-phenylprop-2-yldithiobenzoate, 1-1-ylethyldithiobenzoate, 1-(4-methoxyphenyl)ethyldithiobenzoate, benzyldithioacetate, ethoxycarbonylmethyldithioacetate, 2-(ethoxycarbonyl)prop-2-yldithiobenzoate, 2-cyanoprop-2-yldithiobenzoate, tert-butyldithiobenzoate, 2,4,4-Trimethylpenta-2-yldithiobenzoate, 2-(4-chlorophenyl)-prop-2-yldithiobenzoate, 3-vinylbenzyldithiobenzoate, 4-vinylbenzyldithiobenzoate, benzyldiethoxyphosphenyldithioformate, tert-butyltrithioperbenzoate, 2-phenylprop-2-yl-4-chlorodithiobenzoate, naphthalene-1-carboxylic acid-1-methyl-1-phenylethyl Tel, 4-cyano-4-methyl-4-thiobenzylsulfanylbutyrate, dibenzyltetrathioterephthalate, carboxymethyldithiobenzoate, poly(ethylene oxide) with dithiobenzoate-terminated groups, poly(ethylene oxide) with 4-cyano-4-methyl-4-thiobenzylsulfanylbutyrate-terminated groups, 2-[(2-phenylethanes)sulfanyl]propanoic acid, 2-[(2-phenylethanes)sulfanyl]succinic acid, 3,5 -Dimethyl-1H-pyrazole-1-carbodhithioate potassium, cyanomethyl-3,5-dimethyl-1H-pyrazole-1-carbodhithioate, cyanomethyl-N-methyl-N-phenyldithiocarbamate cyanomethylmethyl, benzyl-4-chlorodithiobenzoate, phenylmethyl-4-chlorodithiobenzoate 4-nitrobenzyl-4-chlorodithiobenzoate, phenylprop-2-yl-4-chlorodithiobenzoate, 1- Examples include cyano-1-methylethyl-4-chlorodithiobenzoate, 3-chloro-2-butenyl-4-chlorodithiobenzoate, 2-chloro-2-butenyldithiobenzoate, benzyldithioacetate, 3-chloro-2-butenyl-1H-pyrrole-1-dithiocarboxylic acid, 2-cyanobutan-2-yl-4-chloro-3,5-dimethyl-1H-pyrazole-1-carboditioate, and cyanomethylmethyl(phenyl)carbamodithioate. Among these, benzyl-1-pyrrolecarboditioate and benzylphenylcarboditioate are particularly preferred.

[0062] The compound used to derive the structure represented by the above chemical formula (2) is not particularly limited and can be a general compound, for example, 2-cyano-2-propyldodecyltrithiocarbonate, dibenzyltrithiocarbonate, butylbenzyltrithiocarbonate, 2-[[(butylthio)thioxomethyl]thio]propionic acid, 2-[[(dodecylthio)thioxomethyl]thio]propionic acid, 2-[[(butylthio)thioxomethyl]thio]succinic acid, 2-[[(dodecylthio)thioxomethyl]thio]succinic acid, 2-[[(dodecylthio)thioxomethyl]thio Examples of trithiocarbonates include ]-2-methylpropionic acid, 2,2′-[carbonothioylbis(thio)]bis[2-methylpropionic acid], 2-amino-1-methyl-2-oxoethylbutyltrithiocarbonate, benzyl 2-[(2-hydroxyethyl)amino]-1-methyl-2-oxoethyltrithiocarbonate, 3-[[[(tert-butyl)thio]thioxomethyl]thio]propionic acid, cyanomethyldodecyltrithiocarbonate, diethylaminobenzyltrithiocarbonate, and dibutylaminobenzyltrithiocarbonate. Among these, dibenzyltrithiocarbonate and butylbenzyltrithiocarbonate are particularly preferred.

[0063] The amount of RAFT agent added can be 0.05 to 10 parts by mass per 100 parts by mass of the raw material monomer, for example, 0.05, 0.1, 0.2, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 parts by mass, and may be within the range of any two of the values ​​exemplified here. The chloroprene-unsaturated nitrile copolymer according to one embodiment of the present invention has a terminal structure represented by chemical formula (1) or chemical formula (2), thereby making it possible to sufficiently lengthen the scorch time of the rubber composition containing the rubber component of the chloroprene-unsaturated nitrile copolymer latex.

[0064] 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.

[0065] 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.

[0066] Furthermore, the chloroprene-unsaturated nitrile copolymer latex obtained by the manufacturing method of one embodiment of the present invention may optionally contain freeze stabilizers, emulsifying stabilizers, viscosity modifiers, antioxidants, preservatives, etc., after polymerization, to the extent that they do not impair the effects of the present invention.

[0067] 3. The rubber component of chloroprene-unsaturated nitrile copolymer latex. One embodiment of the present invention is the rubber component of the chloroprene-unsaturated nitrile copolymer described above. The method for obtaining the rubber component of the chloroprene-unsaturated nitrile copolymer latex is not particularly limited. For example, the rubber component of the chloroprene-unsaturated nitrile copolymer can be obtained by mixing chloroprene-unsaturated nitrile copolymer latex with a large amount of methanol, allowing it to precipitate, filtering, and drying. Alternatively, the rubber component of the chloroprene-unsaturated nitrile copolymer can be obtained by freeze-drying the chloroprene-unsaturated nitrile copolymer latex. Specifically, the pH of the chloroprene-unsaturated nitrile copolymer latex can be adjusted, freeze-dried, washed with water, and hot-air dried. The rubber component of the chloroprene-unsaturated nitrile copolymer includes the methanol precipitate of the chloroprene-unsaturated nitrile copolymer latex and the freeze-dried product of the chloroprene-unsaturated nitrile copolymer latex.

[0068] In one embodiment of the present invention, the rubber component, when used in a rubber composition with the composition described in the examples, preferably has a scorch time of 11 minutes or more. The scorch time can be determined by performing a Mooney scorch test using an L-type rotor at a test temperature of 125°C, based on JIS K 6300-1, and taking the time it takes for the measured Mooney viscosity to increase by 5M. The scorch time can be controlled by adjusting the manufacturing conditions during polymerization of the chloroprene-unsaturated nitrile copolymer, particularly by adjusting the type and amount of raw materials used, and by adjusting the terminal structure of the chloroprene-unsaturated nitrile copolymer.

[0069] In one embodiment of the present invention, a rubber component is prepared by preparing a rubber composition having the composition described in the example, press-vulcanizing the rubber composition at 170°C for 20 minutes according to JIS K 6250 to produce a vulcanized molded body, and it is preferable that the volume change when the vulcanized molded body is immersed in a test oil (high-lubricating oil for automobiles, ASTM No. 3, IRM 903 oil) at 130°C for 72 hours is less than 45% by mass.

[0070] 4. Rubber composition A rubber composition according to one embodiment of the present invention contains the above-mentioned rubber component. In addition to the above-mentioned rubber component, the rubber composition according to the present invention may optionally contain a vulcanizing agent, a vulcanization accelerator, an antioxidant, a filler, a reinforcing agent, a silane coupling agent, a plasticizer, a softener, a lubricant, and a processing aid, and may further contain components such as stabilizers, flame retardants, and vulcanization retardants, to the extent that they do not impair the effects of the present invention.

[0071] 4.1 Vulcanizing agent The rubber composition according to the present invention may contain a vulcanizing agent. The type of vulcanizing agent is not particularly limited as long as it does not impair the effects of the present invention. Preferably, the vulcanizing agent is one that can be used for vulcanizing chloroprene-based rubber. One or more types of vulcanizing agents can be freely selected and used. Examples of vulcanizing agents include sulfur, zinc oxide, and organic peroxides.

[0072] Examples of metal oxides include zinc oxide. The metal oxide preferably contains zinc oxide, and more preferably is zinc oxide.

[0073] Examples of organic peroxides include dicumyl peroxide, benzoyl peroxide, 1,1-bis(t-butylperoxy)-3,5,5-trimethylcyclohexane, diisobutyryl peroxide, cumyl peroxyneodecanoate, di-n-propyl peroxydicarbonate, diisopropyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, di(4-t-butylcyclohexyl)peroxydicarbonate, and di(2-ethylhexyl) peroxydicarbonate. (sil) peroxydicarbonate, t-hexyl peroxyneodecanoate, t-butyl peroxyneodecanoate, t-butyl peroxyneoheptanoate, t-hexyl peroxypivalate, t-butyl peroxypivalate, di(3,5,5-trimethylhexanoyl) peroxide, dilauroyl peroxide, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, disuccinate peroxide, 2,5-dimethyl-2,5-di(2-ethylhexanoyl peroxy)hexane, t-hexyl peroxide Oxy-2-ethylhexanoate, di(4-methylbenzoyl)peroxide, t-butylperoxy-2-ethylhexanoate, di(3-methylbenzoyl)peroxide, benzoyl(3-methylbenzoyl)peroxide, dibenzoylperoxide, 1,1-di(t-butylperoxy)-2-methylcyclohexane, 1,1-di(t-hexylperoxy)-3,3,5-trimethylcyclohexane, 1,1-di(t-hexylperoxy)cyclohexane, 1,1-di(t-butylperoxy)cyclohexane, 2, 2-di(4,4-di-(t-butylperoxy)cyclohexyl)propane, t-hexylperoxyisopropyl monocarbonate, t-butylperoxymaleic acid, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, t-butylperoxyisopropyl monocarbonate, t-butylperoxy2-ethylhexyl monocarbonate, t-hexylperoxybenzoate, 2,5-di-methyl-2,5-di(benzoylperoxy)hexane, t-butylperoxyacetate, 2,Examples include 2-di-(t-butylperoxy)butane, t-butylperoxybenzoate, n-butyl4,4-di-(t-butylperoxy)valerate, 1,4-bis[(t-butylperoxy)isopropyl]benzene, di-t-hexyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, t-butylcumyl peroxide, di-t-butyl peroxide, p-menthane hydroperoxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexyn-3, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, and t-butyl hydroperoxide. Among these, it is preferable that at least one is selected from dicumyl peroxide, 1,4-bis[(t-butylperoxy)isopropyl]benzene, t-butyl α-cumyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, and 2,5-dimethyl-2,5-bis(t-butylperoxy)hexyn-3, and particularly preferable is 1,4-bis[(t-butylperoxy)isopropyl]benzene.

[0074] The rubber composition according to the present invention preferably contains 3 to 15 parts by mass of a vulcanizing agent relative to the rubber components, from the viewpoint of ensuring processing safety and obtaining a good vulcanized product. The content of the vulcanizing agent is, for example, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 parts by mass per 100 parts by mass of the rubber components contained in the rubber composition, and may be within the range of any two of the values ​​exemplified here.

[0075] 4.2 Acid absorbers A rubber composition according to one embodiment of the present invention may contain an acid acceptor. Examples of acid acceptors include magnesium oxide, lead oxide, trilead tetroxide, iron oxide, titanium dioxide, calcium oxide, and hydrotalcite. Hydrotalcite represented by the following formula can be used. [M 2+ 1-x M 3+ x(OH)2] x+ [A n-x / n ·mH2O] x-

[0076] In the above formula, M 2+ : Mg 2+ , Zn 2+ and at least one divalent metal ion selected from the group consisting of M 3+ : Al 3+ , Fe 3+ and at least one trivalent metal ion selected from the group consisting of A n- : Co3 2- , Cl ― , NO3 2- and at least one n-type anion selected from the group consisting of X can be set such that 0 < X ≤ 0.33.

[0077] Examples of hydrotalcite 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. Particularly preferred are Mg 4.3 Al₂(OH) 12.6 CO₃·3.5H₂O, Mg₃ZnAl₂(OH) 12 CO₃·3H₂O.

[0078] The amount of acid acceptor added can be 0.1 to 15 parts by mass per 100 parts by mass of rubber component. The amount of hydrotalcite added can be, for example, 0.1, 0.2, 0.3, 0.5, 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 here. Hydrotalcite can be used alone or in combination of two or more types.

[0079] 4.3 Vulcanization accelerators The rubber composition according to the present invention may contain a vulcanization accelerator, and may contain 0.3 to 5.0 parts by mass of the vulcanization accelerator per 100 parts by mass of the rubber composition. The content of the vulcanization accelerator may be, for example, 0.3, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0 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 be made without a vulcanization accelerator.

[0080] The type of vulcanization accelerator is not particularly limited as long as it does not impair the effects of the present invention. Preferably, the vulcanization accelerator is one that can be used for vulcanizing chloroprene rubber. One or more types of vulcanization accelerators can be freely selected and used. Examples of vulcanization accelerators include thiram-based, dithiocarbamate-based, thiourea-based, guanidine-based, xanthogenicate-based, and thiazole-based agents.

[0081] Examples of thiram-based vulcanization accelerators include tetramethylthiram disulfide (TMTD), tetraethylthiram disulfide, tetrabutylthiram disulfide, tetrakis(2-ethylhexyl)thiram disulfide, tetramethylthiram monosulfide, and dipentamethylenethiram tetrasulfide. Examples of dithiocarbamate-based vulcanization accelerators include sodium dibutyldithiocarbamate, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc N-ethyl-N-phenyldithiocarbamate, zinc N-pentamethylenedithiocarbamate, copper dimethyldithiocarbamate, ferric dimethyldithiocarbamate, and tellurium diethyldithiocarbamate. Examples of thiourea-based vulcanization accelerators include thiourea compounds such as ethylenethiourea, diethylthiourea (N,N'-diethylthiourea), trimethylthiourea, diphenylthiourea (N,N'-diphenylthiourea), and 1,3-trimethylene-2-thiourea. Examples of guanidine-based vulcanization accelerators include 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, and di-o-tolylguanidine salts of dicatecholborate. Examples of xanthogenic acid-based vulcanization accelerators include zinc butylxanthonate and zinc isopropylxanthonate. Examples of thiazole-based vulcanization accelerators include 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, 2-mercaptobenzothiazole zinc salt, cyclohexylamine salt of 2-mercaptobenzothiazole, 2-(4'-morpholinodithio)benzothiazole, and N-cyclohexylbenzothiazole-2-sulfenamide. These can be used individually or in combination of two or more types.

[0082] 4.4 Filling materials (reinforcement materials) The rubber composition according to the present invention may contain a filler. Examples of fillers (reinforcements) 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. These can be used individually or in combination of two or more.

[0083] The rubber composition according to one embodiment of the present invention may contain 5 to 130 parts by mass of filler per 100 parts by mass of rubber component. The filler content may be, for example, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, or 130 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 appropriately adjust the hardness of a vulcanized molded article by including the filler content within the above numerical range.

[0084] 4.5 Silane coupling agents A rubber composition according to one embodiment of the present invention may contain a silane coupling agent. If the rubber composition according to one embodiment of the present invention contains silica as a filler, it is preferable to include a silane coupling agent. There are no particular restrictions on the silane coupling agent, and those used in commercially available rubber compositions can be used, for example, vinyl coupling agents, epoxy coupling agents, styryl coupling agents, methacrylic coupling agents, acrylic coupling agents, amino coupling agents, polysulfide coupling agents, and mercapto coupling agents. In particular, vinyl coupling agents, methacrylic coupling agents, and acrylic coupling agents that initiate the reaction under high-temperature conditions during crosslinking are preferred from the viewpoint of scorch resistance and reinforcing effect.

[0085] The rubber composition according to one embodiment of the present invention may contain 0.5 to 15 parts by mass of a silane coupling agent per 100 parts by mass of silica contained in the rubber composition, for example, 0.5, 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. These can be used individually or in combination of two or more. By including the above-mentioned silane coupling agent and setting the content of the silane coupling agent within the above-mentioned numerical range, it is possible to improve the dispersibility of silica filler in the rubber, the reinforcing effect between the rubber and silica filler, and suppress the occurrence of scorch.

[0086] 4.6 Plasticizers There are no particular restrictions on the plasticizer as long as it is compatible with chloroprene-unsaturated nitrile copolymer rubber. Examples 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, etc. These can be used individually or in combination of two or more. The amount of plasticizer added can be 0 to 50 parts by mass per 100 parts by mass of rubber components in the rubber composition. For example, it can be 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 here.

[0087] 4.7 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. These can be used individually or in combination of two or more. The rubber composition according to the present invention may contain 0.5 to 15 parts by mass of lubricants and processing aids per 100 parts by mass of rubber components, and may also contain 1 to 10 parts by mass. The content of lubricants and processing aids may be, for example, 0.5, 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 here.

[0088] 4.8 Other The rubber composition according to the present invention may further contain, in addition to the above-mentioned components, components such as antioxidants, antioxidants, flame retardants, and vulcanization retardants, to the extent that they do not impede the effects of the present invention. Examples of antioxidants and antioxidants include ozone antioxidants, phenolic antioxidants, amine antioxidants, acrylate antioxidants, imidazole antioxidants, aromatic secondary amine antioxidants, metal carbamate salts, waxes, phosphorus antioxidants, and sulfur antioxidants. Examples of imidazole antioxidants include 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, and zinc salts of 2-mercaptobenzimidazole. The rubber composition according to the present invention may contain a total of 0.1 to 10 parts by mass of antioxidants and antioxidants per 100 parts by mass of rubber components contained in the rubber composition.

[0089] 4.9 Properties of Rubber Compositions The rubber composition according to one embodiment of the present invention preferably has a scorch time of 11 minutes or more. The scorch time can be defined as the time it takes for the measured Mooney viscosity to increase by 5M when a Mooney scorch test is performed using an L-type rotor at a test temperature of 125°C, in accordance with JIS K 6300-1.

[0090] 5. Method for producing rubber composition A rubber composition according to one embodiment of the present invention is obtained by kneading the rubber component of a chloroprene-unsaturated nitrile copolymer latex and other necessary components at a temperature below the vulcanization temperature. Examples of kneading equipment for the raw material components include conventionally known kneading equipment such as mixers, Banbury mixers, kneader mixers, and open rolls.

[0091] 6. 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] In one embodiment of the present invention, it is preferable that the volume change of a vulcanized molded article when immersed in a test oil (high-lubricating oil for automobiles, ASTM No. 3, IRM 903 oil) at 130°C for 72 hours is less than 45% by mass.

[0096] An unvulcanized molded article, vulcanized product, and vulcanized molded article according to one embodiment of the present invention can be used as rubber parts in various industrial fields such as buildings, structures, ships, railways, coal mines, and automobiles. The rubber composition according to the present invention has excellent oil resistance and can therefore be used as various components where these properties are required. The rubber composition, vulcanized product, and vulcanized molded article according to one embodiment of the present invention can be used as rubber parts in various industrial fields such as buildings, structures, ships, railways, coal mines, and automobiles, and can be used for rubber parts such as automotive rubber components (e.g., automotive sealing materials), hose materials, rubber molds, gaskets, rubber rolls, industrial cables, industrial conveyor belts, and sponges. In particular, it can be used as a power transmission belt, conveyor belt, hose, wiper, immersion product, sealing part, adhesive, boot, rubber-coated fabric, rubber roll, vibration-damping rubber, or sponge product.

[0097] (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, 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. In gaskets where the sealing part 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 enhance oil resistance. This makes it possible to manufacture automotive parts with excellent oil resistance, which was difficult with conventional rubber compositions.

[0098] (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 oil resistance of hose materials while maintaining the processability of the unvulcanized material. This makes it possible to manufacture hose materials with excellent oil resistance, which was difficult to achieve with conventional rubber compositions.

[0099] (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 oil resistance of vibration-damping rubber and vibration-damping materials. This makes it possible to manufacture vibration-damping rubber and vibration-damping materials with excellent oil resistance, 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 oil resistance. This makes it possible to manufacture boots that can be used in harsher environments than conventional rubber compositions.

[0100] (Gaskets, etc.) Gaskets, oil seals, and packings are components used in machinery and equipment to 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. In gaskets where the sealing portion is fixed with bolts or the like, 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 oil resistance of these components. This makes it possible to manufacture sealing components with excellent oil resistance, which was difficult to achieve with conventional rubber compositions.

[0101] (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 oil resistance of rubber rolls. This makes it possible to manufacture embossing rubber rolls with excellent oil resistance, which was difficult with conventional rubber compositions.

[0102] (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 oil resistance of industrial cables. This makes it possible to manufacture industrial cables with superior oil resistance, which was difficult to achieve with conventional rubber compositions.

[0103] (Industrial conveyor belt) Industrial conveyor belts are made of rubber, resin, or 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 oil resistance of industrial conveyor belts. This makes it possible to manufacture industrial conveyor belts with excellent oil resistance that can be used in harsh environments, which was difficult with conventional rubber compositions.

[0104] (sponge) Sponge is a porous material with countless fine pores inside, and is specifically used in vibration damping components, sponge seal parts, wetsuits, shoes, and the like. The rubber composition of the present invention can improve the acid resistance and water resistance of sponge. Furthermore, because it uses chloroprene-unsaturated nitrile copolymer rubber, it can also improve the flame retardancy of sponge. This makes it possible to manufacture sponges with excellent oil resistance and flame retardancy for use in harsh environments, which was difficult with conventional rubber compositions. In addition, the hardness of the resulting sponge can be adjusted as appropriate by adjusting the content of the foaming agent, etc.

[0105] Methods for forming a rubber composition (unvulcanized) and a vulcanized product according to one embodiment of the present invention 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]

[0106] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0107] (Example 1) In a 3-liter polymerization vessel equipped with a heating / cooling jacket and a stirrer, 23 parts by mass of chloroprene monomer, 35 parts by mass of acrylonitrile monomer, 100 parts by mass of pure water, 5.0 parts by mass of disproportionated potassium rosinate (manufactured by Harima Chemicals, Inc.), 0.4 parts by mass of potassium hydroxide, 1.0 part by mass of sodium salt of β-naphthalene sulfonic acid formalin condensate (manufactured by Kao Corporation), and 0.2 parts by mass of butylbenzyl trithiocarbonate were added. 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. During polymerization, when the amount of unreacted monomers in the polymerization solution (total of chloroprene monomers and acrylonitrile monomers) was 100 parts by mass, the amount of unsaturated nitrile monomers in the polymerization solution was maintained at 70 parts by mass ± 20 parts by mass. Chloroprene monomers were added 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 of the refrigerant during the first 10 seconds of polymerization. Thereafter, the flow rate was readjusted every 10 seconds to continue the process. When the polymerization rate reached 65% of the total amount of chloroprene and acrylonitrile, 0.02 parts by mass of phenothiazine, a polymerization stopper, was added to stop the polymerization. Next, unreacted monomers and organic solvents were removed and the mixture was concentrated by vacuum distillation to obtain chloroprene-unsaturated nitrile copolymer latex 1 with a solid content of 50% by mass.

[0108] (Example 2, Comparative Examples 1-4) Chloroprene-unsaturated nitrile copolymer latexes 2, 4-7 were obtained in the same manner as in Example 1, except that the amount of chloroprene monomer initially added, the amount of acrylonitrile monomer, the amount of water, the amount of chloroprene monomer added in installments, and the amount of unsaturated nitrile monomer relative to the unreacted monomers in the polymerization solution maintained during polymerization were as shown in Table 1.

[0109] (Example 3) Chloroprene-unsaturated nitrile copolymer latex 3 was obtained in the same manner as in the examples, except that the amount of chloroprene monomer initially added, the amount of acrylonitrile monomer, the amount of water, the amount of chloroprene monomer added in installments, and the amount of unsaturated nitrile monomer relative to the unreacted monomers in the polymerization solution maintained during polymerization were as shown in Table 1, and 0.5 parts by mass of diisopropyl xanthogen disulfide was used instead of 0.2 parts by mass of RAFT agent.

[0110] (Content of hydrolyzed unsaturated nitriles in chloroprene-unsaturated nitrile copolymer latex) Approximately 1 g of the chloroprene-unsaturated nitrile copolymer latex from each example and comparative example was weighed, diluted to 25 ml with tetrahydrofuran, and the resulting solution was analyzed using a gas chromatography (GC) system to calculate the content of chloroprene-unsaturated nitrile copolymer, acrylamide, 2-cyanoethanol, and 2-cyanoethyl ether in the chloroprene-unsaturated nitrile copolymer latex. Device name: 8890GC system Column: DB-1 0.32mmφ×30m (film thickness 5.0μm) Column temperature: 50°C (5 min) → 50°C / min → 100°C → 15°C / min → 300°C (30 min) Inlet temperature: 270℃ Detector temperature: 300℃ Detector: FID Furthermore, the chloroprene-unsaturated nitrile copolymer latex used in the examples and comparative examples did not emit a pungent odor, and no ammonia or carboxylic acid was observed to be generated.

[0111] (Viscosity after storage at 40°C for 4 months) The chloroprene-unsaturated nitrile copolymer latex (solid content concentration 50% by mass) according to each example and comparative example was stored at 40°C for 4 months, and then its viscosity was measured using a Type B viscometer under the following conditions. Measuring instrument: "VISCOMETER TVB-20L" manufactured by Toki Sangyo Co., Ltd. Spindle rotor: 2M (disc shape with a radius of 19mm and a thickness of 7mm) Rotation speed: 30 rpm

[0112] The following evaluation criteria were used. ○: Less than 1000 cps ×: 1000 cps or more

[0113] <Precipitation of rubber components> The pH of the chloroprene-unsaturated nitrile copolymer latex in each example and comparative example was adjusted to 7.0 using acetic acid or sodium hydroxide. Then, the chloroprene-acrylonitrile copolymer latex was emulsified and destroyed by freeze-coagulation on a metal plate cooled to -20°C to obtain a sheet. After washing this sheet with water, it was dried at 130°C for 15 minutes to obtain solid chloroprene-acrylonitrile copolymer rubber components (chloroprene-acrylonitrile copolymers 1 to 7).

[0114] (Nitrogen content and acrylonitrile bond amount) Using chloroprene-acrylonitrile copolymers 1-7, the nitrogen content in the chloroprene-unsaturated nitrile copolymer was measured by combustion, and the amount of acrylonitrile bound was calculated from the nitrogen content. The analytical method was based on JIS K6451-1:2016, using an automated analyzer with a combustion method (Dumas method) to calculate the nitrogen content in the sample, and from the nitrogen content, the amount of acrylonitrile monomer units (amount of bound acrylonitrile) was calculated.

[0115] Specifically, the nitrogen atom content in 100 mg of chloroprene-unsaturated nitrile copolymer was measured using an elemental analyzer (Sumigraph 220F: manufactured by Sumika Analysis Center Co., Ltd.), and the monomer content of acrylonitrile was calculated. The elemental analysis was performed as follows: The electric furnace temperature was 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%), whose nitrogen content is known, as a standard substance.

[0116] <Preparation of rubber composition> A rubber composition was prepared using the rubber components (chloroprene-acrylonitrile copolymers 1-7) in the chloroprene-unsaturated nitrile copolymer latex obtained by freeze-drying chloroprene-acrylonitrile copolymer latexes 1-7 as described above. Specifically, 100 parts by mass of the rubber component were used. • Anti-aging agent (4,4'-bis(α,α-dimethylbenzyl)diphenylamine (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., Nocrack CD)) 3 parts by mass, • Anti-aging agent (N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., Nocrack 6C)) 1 part by mass, • Acid acceptor (magnesium oxide (manufactured by Kyowa Chemical Industry Co., Ltd., Kyowa Mag 150)) 4 parts by mass, • Zinc oxide (manufactured by Sakai Chemical Industry Co., Ltd., zinc oxide type 2) 5 parts by mass, • Vulcanization accelerator (trimethylthiourea (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., Noxellar TMU)) 1 part by mass, • Filler material (carbon black FEF (manufactured by Asahi Carbon Co., Ltd., Asahi #60)) 50 parts by mass, • Plasticizer (ether ester-based plasticizer (ADEKA Corporation, ADEKA Sizer RS-700)) 10 parts by mass, • Lubricant (Stearic Acid (manufactured by Shin Nippon Rika Co., Ltd., Stearic Acid 50S)) 1 part by mass The following were added and kneaded in an 8-inch open roll to obtain rubber compositions 1 to 7.

[0117] (Scorch time) The scorch times of rubber compositions 1 to 7 were evaluated. Specifically, for each rubber composition, a Mooney scorch test was performed using an L-type rotor at a test temperature of 125°C, in accordance with JIS K 6300-1. The time it took for the measured Mooney viscosity to increase by 5M was defined as the scorch time. The obtained scorch times were evaluated according to the following evaluation criteria. ○: 11 minutes or more ×: Less than 11 minutes

[0118] <Fabrication of curing molded bodies> Vulcanized molded articles were prepared using the above rubber compositions 1 to 7. Specifically, the obtained rubber compositions 1 to 7 were press-vulcanized at 170°C for 20 minutes according to JIS K 6250 to produce sheet-like vulcanized molded articles with a thickness of 2 mm. (Oil resistance) Test specimens measuring 25 mm in length and 20 mm in width were punched out from the aforementioned sheet-like vulcanized molded body to obtain test specimens. The obtained test specimens were immersed in test oil (high-lubricity automotive oil, 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. The obtained volume change rate ΔV was evaluated according to the following criteria. ○: Less than 45% ×: 45% or more

[0119] [Table 1]

Claims

1. A chloroprene-unsaturated nitrile copolymer latex comprising a chloroprene-unsaturated nitrile copolymer containing chloroprene monomer units and unsaturated nitrile monomer units, The chloroprene-unsaturated nitrile copolymer has a nitrogen content of 0.5% by mass or more, as measured by combustion. The content of hydrolyzed unsaturated nitrile in the chloroprene-unsaturated nitrile copolymer latex is 0.1 parts by mass of the chloroprene-unsaturated nitrile copolymer. Chloroprene-unsaturated nitrile copolymer latex, in an amount of approximately 9.00 parts by mass.

2. The chloroprene-unsaturated nitrile copolymer latex according to claim 1, wherein the chloroprene-unsaturated nitrile copolymer has a functional group having a structure represented by chemical formula (1) or chemical formula (2). 【Chemistry 1】 (In chemical formula (1), R １ (This represents hydrogen, chlorine, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted mercapto group, or a substituted or unsubstituted heterocyclyl group.) 【Chemistry 2】

3. The unsaturated nitrile monomer unit is an acrylonitrile monomer unit, The chloroprene-unsaturated nitrile copolymer has an acrylonitrile bond content of 2% by mass or more, as measured in accordance with JIS K 6451-1. The chloroprene-unsaturated nitrile copolymer latex according to claim 1 or claim 2, wherein the content of hydrolyzed acrylonitrile in the chloroprene-unsaturated nitrile copolymer latex is 0.10 to 9.00 parts by mass per 100 parts by mass of the chloroprene-unsaturated nitrile copolymer.

4. The rubber component of the chloroprene-unsaturated nitrile copolymer latex according to claim 1 or claim 2.

5. A rubber composition comprising the rubber component described in claim 4.

6. A vulcanized molded article of the rubber composition according to claim 5.

7. The vulcanized molded body according to claim 6, which is a transmission belt, conveyor belt, hose, wiper, immersion product, sealing part, adhesive, boot, rubberized fabric, rubber roll, vibration-damping rubber or sponge product.

8. A method for producing a chloroprene-unsaturated nitrile copolymer latex containing a chloroprene-unsaturated nitrile copolymer comprising chloroprene monomer units and unsaturated nitrile monomer units, The above manufacturing method includes a polymerization step of polymerizing raw material monomers, which include a chloroprene monomer and an unsaturated nitrile monomer, in an aqueous solution containing water to obtain a chloroprene-unsaturated nitrile copolymer. A manufacturing method wherein, when the total amount of raw material monomers used in the polymerization step is 100 parts by mass, the amount of water is less than 150 parts by mass.

Images