WO2024203716A1

WO2024203716A1 - Chloroprene/unsaturated nitrile copolymer latex, rubber component, rubber composition, vulcanized molded body, and production method for chloroprene/unsaturated nitrile copolymer latex

Info

Publication number: WO2024203716A1
Application number: PCT/JP2024/011009
Authority: WO
Inventors: 渉西野; 遼太郎安藤
Original assignee: デンカ株式会社
Priority date: 2023-03-28
Filing date: 2024-03-21
Publication date: 2024-10-03

Abstract

Problem: To provide a chloroprene/unsaturated nitrile copolymer latex that has excellent storage stability at high temperatures over long periods of time, the chloroprene/unsaturated nitrile copolymer latex being such that vulcanized molded bodies of a rubber composition that uses a rubber component of the chloroprene/unsaturated nitrile copolymer latex have excellent oil resistance and generate little heat. Solution: The present invention provides a chloroprene/unsaturated nitrile copolymer latex that includes a chloroprene/unsaturated nitrile copolymer that includes chloroprene monomer units and unsaturated nitrile monomer units, the nitrogen content of the chloroprene/unsaturated nitrile copolymer as measured by the combustion method being at least 0.5 mass%, the chloroprene/unsaturated nitrile copolymer having a functional group that has the structure represented by chemical formula (1), and the unsaturated nitrile hydrolysate content of the chloroprene/unsaturated nitrile copolymer latex being 0.10–9.00 parts by mass per 100 parts by mass of the chloroprene/unsaturated nitrile copolymer.

Description

Chloroprene-unsaturated nitrile copolymer latex, rubber component, rubber composition, vulcanized molded product, and method for producing chloroprene-unsaturated nitrile copolymer latex

The present invention relates to a chloroprene-unsaturated nitrile copolymer latex, a rubber component, a rubber composition, a vulcanized molded product, and a method for producing the chloroprene-unsaturated nitrile copolymer latex.

Chloroprene latex and chloroprene rubber, which contain chloroprene polymers, have excellent mechanical properties, ozone resistance, and chemical resistance, and these properties are used in a wide range of fields, including automotive parts, adhesives, and various industrial rubber parts.

For example, Patent Document 1 discloses a copolymer in which the proportions of the monomers constituting the polymer are, when the total amount of all monomers is taken as 100% by mass, 80 to 97% by mass of 2-chloro-1,3-butadiene (chloroprene) (C-1) and 20 to 3% by mass of 2,3-dichloro-1,3-butadiene (C-2); or a copolymer in which 79.8 to 96.8% by mass of 2-chloro-1,3-butadiene (chloroprene) (C-1), 20 to 3% by mass of 2,3-dichloro-1,3-butadiene (C-2) and 0.2 to 17% by mass of a monomer (C-3) copolymerizable therewith are The present invention discloses a composition for chloroprene-based vulcanized rubber, which comprises 100 parts by mass of a polymer for chloroprene-based vulcanized rubber, the polymer being a copolymer consisting of the above-mentioned copolymer and having a Mooney viscosity (ML1+4(100°C)) in the range 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 a flame-retardant hose, which contains a rubber component, carbon black, and silica, and in which the rubber component is composed only of chloroprene rubber, or is composed only of chloroprene rubber and styrene-butadiene rubber.

Patent Document 3 discloses a statistical copolymer latex containing chloroprene monomer units and unsaturated nitrile monomer units, with an unsaturated nitrile monomer unit content of 5 to 20% by mass, and wherein 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.

JP 2012-211345 A JP 2017-019947 A WO2019/211975

However, conventional chloroprene-based latexes have room for improvement in terms of storage stability at high temperatures for long periods of time. In addition, it has been difficult to obtain a chloroprene-based latex that has excellent storage stability at high temperatures for long periods of time, has excellent oil resistance in a vulcanized molded product of a rubber composition that uses the rubber component of the chloroprene-based latex, and generates little heat in a dynamic environment.

The present invention has been made in consideration of these circumstances, and provides a chloroprene-unsaturated nitrile copolymer latex that has excellent storage stability at high temperatures for long periods of time, and that has excellent oil resistance in a vulcanized molded product of a rubber composition using the rubber component of the chloroprene-unsaturated nitrile copolymer latex and generates little heat in a dynamic environment. The present invention also provides a rubber component of the chloroprene-unsaturated nitrile copolymer latex, a rubber composition containing the rubber component, a vulcanized molded product of the rubber composition, and a method for producing the chloroprene-unsaturated nitrile copolymer latex.

According to the present invention, there is provided a chloroprene-unsaturated nitrile copolymer latex containing 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 a combustion method, the chloroprene-unsaturated nitrile copolymer has a functional group having a structure represented by chemical formula (1), and the content of the unsaturated nitrile hydrolyzate 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.

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.

The inventors conducted extensive research and discovered that by adjusting the manufacturing conditions for the chloroprene-unsaturated nitrile copolymer latex and controlling the nitrogen content and structure in the chloroprene-unsaturated nitrile copolymer, as well as the content of unsaturated nitrile hydrolysates in the chloroprene-unsaturated nitrile copolymer latex, it is possible to obtain a chloroprene-unsaturated nitrile copolymer latex that has excellent storage stability at high temperatures for long periods of time, that has excellent oil resistance in a vulcanized molded product of a rubber composition that uses the rubber component of the chloroprene-unsaturated nitrile copolymer latex, and that generates little heat in dynamic environments, thereby completing the present invention.

Various embodiments of the present invention will be described below. The embodiments described below can be combined with each other.
[1] A chloroprene-unsaturated nitrile copolymer latex containing 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 a combustion method, the chloroprene-unsaturated nitrile copolymer has a functional group having a structure represented by chemical formula (1), and the content of an unsaturated nitrile hydrolyzate in the chloroprene-unsaturated nitrile copolymer latex is 0.10 to 9.00 parts by mass relative to 100 parts by mass of the chloroprene-unsaturated nitrile copolymer.

(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.)
[2] The chloroprene-unsaturated nitrile copolymer latex according to [1], wherein the unsaturated nitrile monomer unit is an acrylonitrile monomer unit, the chloroprene-unsaturated nitrile copolymer has an acrylonitrile bond amount of 2 mass% or more measured in accordance with JIS K6451-1, and the chloroprene-unsaturated nitrile copolymer latex has a content of acrylonitrile hydrolysate of 0.10 to 9.00 mass parts relative to 100 mass parts of the chloroprene-unsaturated nitrile copolymer.
[3] A rubber component of the chloroprene-unsaturated nitrile copolymer latex according to [1] or [2].
[4] A rubber composition comprising the rubber component according to [3].
[5] A vulcanized molded article of the rubber composition according to [4].
[6] The vulcanization molded article according to [5], which is a power transmission belt, a conveyor belt, a hose, a wiper, a dipping product, a sealing part, an adhesive, a boot, a rubber-coated cloth, a rubber roll, a vibration-proof rubber or a sponge product.
[7] A method for producing a chloroprene-unsaturated nitrile copolymer latex containing a chloroprene-unsaturated nitrile copolymer containing a chloroprene monomer unit and an unsaturated nitrile monomer unit, the method comprising a polymerization step of polymerizing raw material monomers containing a chloroprene monomer and an unsaturated nitrile monomer in an aqueous solution containing water in the presence of a xanthogen compound to obtain the chloroprene-unsaturated nitrile copolymer, and the amount of the water is less than 150 parts by mass when the total amount of the raw material monomers used in the polymerization step is taken as 100 parts by mass.

The chloroprene-unsaturated nitrile copolymer latex of the present invention has excellent storage stability at high temperatures for long periods of time. In addition, a vulcanized molded product of a rubber composition containing the rubber component of the chloroprene-unsaturated nitrile copolymer latex of the present invention has excellent oil resistance and generates little heat in dynamic environments. Since the chloroprene-unsaturated nitrile copolymer latex of the present invention has excellent storage stability at high temperatures for long periods of time, it can be stored while maintaining its excellent quality in the state of the chloroprene-unsaturated nitrile copolymer latex, and since a vulcanized molded product of a rubber composition using the rubber component has excellent oil resistance and generates little heat in dynamic environments, these properties can be utilized for a variety of applications and components.

The present invention will be described in detail below by illustrating 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 can be an invention independently.

1. Chloroprene-unsaturated nitrile copolymer latex The chloroprene-unsaturated nitrile copolymer latex according to the present invention contains a chloroprene-unsaturated nitrile copolymer. The chloroprene-unsaturated nitrile copolymer has a nitrogen content of 0.5% by mass or more as measured by a combustion method, has a functional group having a structure represented by chemical formula (1), and the content of the unsaturated nitrile hydrolysate in the chloroprene-unsaturated nitrile copolymer latex is 0.10 to 9.00 parts by mass relative to 100 parts by mass of the chloroprene-unsaturated nitrile copolymer.

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 an unsaturated nitrile. The chloroprene-unsaturated nitrile copolymer according to the present invention may have a structure derived from a monomer unit other than the chloroprene monomer unit and the unsaturated nitrile monomer unit, as long as the object of the present invention is not impaired.

Note that commercially available 2-chloro-1,3-butadiene may contain a small amount of 1-chloro-1,3-butadiene as an impurity. 2-chloro-1,3-butadiene containing such a small amount of 1-chloro-1,3-butadiene can also be used as the chloroprene monomer in this embodiment.

Examples of unsaturated nitriles include acrylonitrile, methacrylonitrile, ethacrylonitrile, and phenylacrylonitrile. The unsaturated nitriles may be used alone or in combination of two or more. It is preferable that the unsaturated nitrile contains acrylonitrile, 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 product.

The chloroprene-unsaturated nitrile copolymer according to the present invention has a nitrogen content of 0.5% by mass or more as measured by a combustion method. 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 a range between any two of the values exemplified here.

The nitrogen content of the chloroprene-unsaturated nitrile copolymer can be determined by analyzing the chloroprene-unsaturated nitrile copolymer obtained by freeze-drying or methanol precipitation from the chloroprene-unsaturated nitrile copolymer latex using an elemental analyzer by a combustion method. Specifically, the analysis can be performed by the method described in the Examples.
The nitrogen in the chloroprene-unsaturated nitrile copolymer can be derived from the unsaturated nitrile monomer units in the chloroprene-unsaturated nitrile copolymer, and can be controlled by adjusting the amount of unsaturated nitrile in the raw material monomer during polymerization of the chloroprene-unsaturated nitrile copolymer.

The chloroprene-unsaturated nitrile copolymer according to one embodiment of the present invention preferably has an unsaturated nitrile monomer unit content of 2.0% by mass or more. The unsaturated nitrile monomer unit content 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 a range between any two of the numerical values exemplified here.

The chloroprene-unsaturated nitrile copolymer according to one embodiment of the present invention preferably has an acrylonitrile bond content (content of acrylonitrile monomer units) of 2 mass% or more, measured in accordance with JIS K 6451-1. The acrylonitrile bond content (content of acrylonitrile monomer units) is, 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 mass%, and may be within a range between any two of the numerical values exemplified here.

The content of unsaturated nitrile monomer units and the content of acrylonitrile monomer units in the chloroprene-unsaturated nitrile copolymer can be calculated based on the nitrogen content measured by the combustion method, and in particular, the amount of acrylonitrile bonds (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 the above lower limit or higher, the resulting rubber composition and vulcanized molded product will have sufficient oil resistance. In addition, by setting the content of unsaturated nitrile monomer units and acrylonitrile monomer units to the above upper limit or lower, the resulting rubber composition and vulcanized molded product will have improved water resistance and cold resistance.

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 taken as 100% by mass. The content of chloroprene monomer units in the chloroprene-unsaturated nitrile copolymer may be, for example, 60, 65, 70, 75, 80, 85, 90, 95, 99, or 100% by mass, and may be within a range between any two of the numerical values exemplified here. By setting the content of chloroprene monomer units within the above numerical range, a rubber composition can be obtained that can give a molded article with an excellent balance of hardness, tensile strength, and cold resistance.

The chloroprene-unsaturated nitrile copolymer according to one embodiment of the present invention may also have a monomer unit other than the chloroprene monomer and the unsaturated nitrile monomer. The monomer unit other than the chloroprene monomer and the unsaturated nitrile monomer is not particularly limited as long as it is copolymerizable with the chloroprene monomer or the chloroprene monomer and the unsaturated nitrile monomer, and examples of the monomer unit include esters of (meth)acrylic acid (methyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, etc.), hydroxyalkyl (meth)acrylates (2-hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, etc.), 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, butadiene, isoprene, ethylene, styrene, sulfur, etc.

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 the chloroprene monomer and the unsaturated nitrile monomer when the chloroprene-unsaturated nitrile copolymer is taken as 100% by mass. The content of the monomer units other than the chloroprene monomer and the unsaturated nitrile monomer 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 a range between any two of the numerical values exemplified here. By adjusting the copolymerization amount of the monomer other than the chloroprene monomer and the unsaturated nitrile monomer to this range, the effect of copolymerizing these monomers can be expressed without impairing the properties of the obtained rubber composition.
Furthermore, the chloroprene-unsaturated nitrile copolymer according to one embodiment of the present invention may be composed only of chloroprene monomer units and unsaturated nitrile monomer units.

The chloroprene-unsaturated nitrile copolymer latex according to one embodiment of the present invention may contain one kind of chloroprene-unsaturated nitrile copolymer, or may contain two or more kinds of chloroprene-unsaturated nitrile copolymers.
When the chloroprene-unsaturated nitrile copolymer latex according to one embodiment of the present invention contains two or more kinds of chloroprene-unsaturated nitrile copolymers, it is preferable that the content based on the total mass of total nitrogen, total unsaturated nitrile monomer units, total acrylonitrile monomer units, etc. contained in the two or more kinds of chloroprene-unsaturated nitrile copolymers is within the above-mentioned numerical range with respect to 100% by mass of the two or more kinds of chloroprene-unsaturated nitrile copolymers in total contained in the chloroprene-unsaturated nitrile copolymer latex.

The chloroprene-unsaturated nitrile copolymer according to one embodiment of the present invention has a functional group having a structure represented by chemical formula (1).

The functional group having the structure represented by chemical formula (1) can be introduced by carrying out the polymerization process of the chloroprene-unsaturated nitrile copolymer in the presence of a xanthogen compound. Xanthogen compounds that can be used to introduce the functional group having the structure represented by chemical formula (1) will be described later in the section on the production method.
The vulcanized molded article of the rubber composition containing the rubber component of the chloroprene-unsaturated nitrile copolymer latex according to the present invention has excellent oil resistance and generates little heat under dynamic environments because the chloroprene-unsaturated nitrile copolymer has a functional group having a structure represented by chemical formula (1).

1.2 Hydrolyzate of Unsaturated Nitrile In the chloroprene-unsaturated nitrile copolymer according to the present invention, the content of the hydrolyzate of the 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.
In general, it is considered that unsaturated nitriles are hydrolyzed to amides, alcohols, and ethers, and are finally decomposed to carboxylic acids and ammonia. In the present invention, the hydrolyzate of the unsaturated nitrile may contain amides, nitriles, alcohols, ethers, carboxylic acids, and ammonia derived from the unsaturated nitrile. In the present invention, the hydrolyzate of the unsaturated nitrile may be a compound derived from the unsaturated nitrile, and may be a compound containing a cyano group, a compound containing an amide group, a compound containing a carboxy group, and a compound containing an amino group (including ammonia).

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

The chloroprene-unsaturated nitrile copolymer according to the present invention has a content of unsaturated nitrile hydrolysate in the chloroprene-unsaturated nitrile copolymer latex relative to 100 parts by mass of the chloroprene-unsaturated nitrile copolymer, which is 0.10 to 9.00 parts by mass, 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, or 9.00% by mass, and may be within a range between any two of the numerical values exemplified here. In addition, the chloroprene-unsaturated nitrile copolymer according to one embodiment of the present invention may have a total content of amide, nitrile, alcohol, ether, carboxylic acid, and ammonia derived from unsaturated nitrile within the above numerical range, and the content of amide, nitrile, alcohol, and ether derived from unsaturated nitrile may be within the above numerical range. In addition, 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-mentioned 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] may be within the above-mentioned numerical range.

The chloroprene-unsaturated nitrile copolymer according to the present invention is preferably such that the content of acrylonitrile hydrolysates per 100 parts by mass of the chloroprene-unsaturated nitrile copolymer in the chloroprene-unsaturated nitrile copolymer latex is within the above numerical range. In one example, the content of unsaturated nitrile hydrolysates can be the total content of 2-cyanoethanol, 2-cyanoethyl ether, and acrylamide, and the content of acrylonitrile hydrolysates can be the total content of 2-cyanoethanol, 2-cyanoethyl ether, and acrylamide. The chloroprene-unsaturated nitrile copolymer according to the present invention is preferably such that the total content of 2-cyanoethanol, 2-cyanoethyl ether, and acrylamide per 100 parts by mass of the chloroprene-unsaturated nitrile copolymer in the chloroprene-unsaturated nitrile copolymer latex is within the above numerical range.

In one embodiment of the present invention, the chloroprene-unsaturated nitrile copolymer latex may have a 2-cyanoethanol content of 0.05 to 8.00 parts by mass relative to 100 parts by mass of the chloroprene-unsaturated nitrile copolymer. The 2-cyanoethanol 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 a range between any two of the numerical values exemplified here.

In one embodiment of the present invention, the chloroprene-unsaturated nitrile copolymer latex may have a 2-cyanoethyl ether content of 0.05 to 8.00 parts by mass relative to 100 parts by mass of the chloroprene-unsaturated nitrile copolymer. 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 a range between any two of the numerical values exemplified here.

In one embodiment of the present invention, the chloroprene-unsaturated nitrile copolymer latex may have an acrylamide content of 0.05 to 8.00 parts by mass relative to 100 parts by mass of the chloroprene-unsaturated nitrile copolymer. 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 a range between any two of the numerical values exemplified here.

The chloroprene-unsaturated nitrile copolymer according to one embodiment of the present invention has an unsaturated nitrile hydrolysate content within the above numerical range, and therefore has excellent storage stability at high temperatures for long periods of time, and a vulcanized molded product of a rubber composition containing a rubber component of the chloroprene-unsaturated nitrile copolymer latex has excellent oil resistance and generates little heat in a dynamic environment. The content of unsaturated nitrile hydrolysates can be controlled by adjusting the production conditions during polymerization of the chloroprene-unsaturated nitrile copolymer, in particular the amount of water and the amount of alkali relative to the raw material monomers used in polymerization, the type and amount of the raw material monomers mixed, as well as the timing of addition, polymerization temperature, and the concentration of each monomer in the polymerization liquid.

The content of unsaturated nitrile hydrolysates in the chloroprene-unsaturated nitrile copolymer latex can be determined by analyzing a solution obtained by diluting the chloroprene-unsaturated nitrile copolymer latex with tetrahydrofuran using gas chromatography, for example, a gas chromatograph (GC) system. Specifically, the analysis can be performed using the method described in the Examples. As another method, since ammonia, one of the hydrolysates of unsaturated nitriles, has a strong irritating odor, the presence or absence of the generation of ammonia can be confirmed by the presence or absence of an irritating odor in the polymerization liquid. In addition, since carboxylic acid is considered to be generated simultaneously with ammonia based on the mechanism of decomposition, the presence or absence of carboxylic acid generation can be confirmed by the presence or absence of ammonia generation. As an example, if the concentration of ammonia in the chloroprene-unsaturated nitrile copolymer latex is 1 ppm or more, the irritating odor can be detected in the working environment. As an example, the concentration of ammonia in the chloroprene-unsaturated nitrile copolymer latex can be less than 1 ppm. The concentration of ammonia can also be analyzed by ion chromatography. In addition, carboxylic acid can also be analyzed by ion chromatography, liquid chromatography, or gas chromatography.

The chloroprene-unsaturated nitrile copolymer latex according to one embodiment of the present invention can contain compounds used in the polymerization of the chloroprene-unsaturated nitrile copolymer, in addition to the chloroprene-unsaturated nitrile copolymer and the hydrolyzate of the unsaturated nitrile.

1.3 Characteristics of Chloroprene-Unsaturated Nitrile Copolymer Latex The chloroprene-unsaturated nitrile copolymer latex according to one embodiment of the present invention can have a solid content adjusted according to the application. The solid content is not particularly limited, and may be, for example, 40, 45, 50, 55, 60, 65, or 70% by mass, or may be within a range between any two of the values exemplified here.

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

2. Method for Producing Chloroprene-Unsaturated Nitrile Copolymer Latex There is no particular limitation on the method for producing the chloroprene-unsaturated nitrile copolymer latex according to the present invention.
A method for producing a chloroprene-unsaturated nitrile copolymer latex including a chloroprene-unsaturated nitrile copolymer including a chloroprene monomer unit and an unsaturated nitrile monomer unit according to one embodiment of the present invention can include a polymerization step of polymerizing raw material monomers including a chloroprene monomer and an unsaturated nitrile monomer in an aqueous solution containing water in the presence of a xanthogen compound to obtain a chloroprene-unsaturated nitrile copolymer. In addition, when the total raw material monomers used in the polymerization step are taken as 100 parts by mass, the amount of the water can be less than 150 parts by mass.

In the polymerization process, raw material monomers including chloroprene monomer and unsaturated nitrile monomer are polymerized in an aqueous solution containing water to obtain a chloroprene-unsaturated nitrile copolymer.

The raw material monomers include chloroprene monomer and unsaturated nitrile monomer, and may include other monomers in addition to chloroprene monomer and unsaturated nitrile monomer. 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 ranges described above.

A portion of the raw material monomers can be added initially, and a portion can be added in portions after the start of polymerization. As an example, the polymerization process can include a first addition step of adding at least a portion of the raw material monomers including chloroprene and unsaturated nitrile, and a second addition step of adding the remaining raw material monomers.

In the first addition step according to one embodiment of the present invention, when the total amount of chloroprene monomers added in the polymerization step is taken as 100 parts by mass, at least 10 parts by mass of chloroprene monomer can be added, for example, 10, 20, 30, 40, 50, 60, 70 parts by mass can be added, and it may be within a range between any two of the numerical values exemplified here. In addition, in the first addition step, when the total amount of unsaturated nitriles added in the polymerization step is taken as 100 parts by mass, at least 50 parts by mass of unsaturated nitrile can be added, for example, 50, 60, 70, 80, 90, 100 parts by mass can be added, and it may be within a range between any two of the numerical values exemplified here.
In the first addition step according to one embodiment of the present invention, the raw material monomer, emulsifier, and optionally RAFT agent and molecular weight are added to water in the above amounts. Then, a polymerization initiator is added to start polymerization.

In the second addition step according to one embodiment of the present invention, when the total amount of 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 may be within a range between any two of the numerical values exemplified here. In addition, when the total amount of 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 may be within a range between any two of the numerical values exemplified here. In the second addition step, it is not necessary to add unsaturated nitrile. In the second addition step, it is preferable to add the remaining raw material monomer in two or more separate portions. In the second addition step, the remaining raw material monomer can be added in separate portions, for example, 2, 4, 6, 8, 10, 12, 14, 16, 18, or 20 portions, and the number of separate additions may be within a range between any two of the numerical values exemplified here. In the second addition step, the remaining raw material monomers can also be added continuously at a constant flow rate.

During polymerization, it is preferable to add the raw material monomers in portions so that the amount of unsaturated nitrile monomer in the polymerization liquid is maintained at 20 to 90 parts by mass when the amount of unreacted monomer in the polymerization liquid (e.g., the total of chloroprene monomer and acrylonitrile monomer) is 100 parts by mass. The amount of unsaturated nitrile monomer relative to 100 parts by mass of unreacted monomer in the polymerization liquid 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 a range between any two of the numerical values exemplified here.

In the polymerization step according to one embodiment of the present invention, the amount of water can be less than 150 parts by mass when the total amount of raw material monomers used in the polymerization step is 100 parts by mass. The amount of water can be, for example, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, or 149 parts by mass, or can be within a range between any two of the values exemplified here.
In the polymerization step according to one embodiment of the present invention, the amount of hydrolyzed unsaturated nitriles produced can be reduced by reducing the amount of water compared to conventional production methods. In addition, hydrolyzed unsaturated nitriles, such as acrylamide, 2-cyanoethanol, and 2-cyanoethyl ether, impose a large burden on wastewater treatment, and therefore reducing the production of these hydrolyzed products is also advantageous in terms of reducing the environmental load and the effort and cost required for wastewater treatment.

The emulsifier used in emulsion polymerization is not particularly limited, and any known emulsifier generally used in 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 rosin acid or disproportionated rosin acid (e.g. potassium rosinate), and alkali metal salts of formalin condensates of β-naphthalenesulfonic acid (e.g. sodium salt).

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.

At least a xanthogen compound is used as a molecular weight regulator in emulsion polymerization. In the polymerization process according to one embodiment of the present invention, in addition to the xanthogen compound, a known molecular weight regulator that is generally used in emulsion polymerization of chloroprene can be used in combination. Other molecular weight regulators include, for example, mercaptan compounds, dithiocarbonate compounds, trithiocarbonate compounds, and carbamate compounds.

In the polymerization process according to the present invention, the terminal structure represented by chemical formula (1) can be introduced into the chloroprene-unsaturated nitrile copolymer by carrying out the polymerization in the presence of a xanthogen compound.

Examples of xanthogen compounds include dialkyl xanthogen disulfides such as dimethyl xanthogen disulfide, diethyl xanthogen disulfide, diisopropyl xanthogen disulfide, and dibutyl xanthogen trisulfide. Other examples include dialkyl xanthogen trisulfides such as diethyl xanthogen trisulfide, diisopropyl xanthogen trisulfide, and dibutyl xanthogen trisulfide. Furthermore, dialkyl xanthogens having four or more sulfur atoms linking xanthogens, such as dialkyl xanthogen polysulfides such as diethyl xanthogen polysulfide, diisopropyl xanthogen polysulfide, and dibutyl xanthogen polysulfide, can also be used. From the viewpoint of solubility in chloroprene monomer, the number of carbon atoms in the alkyl group of these dialkyl xanthogen sulfide compounds is preferably 1 to 10, and more preferably 1 to 6.

The amount of molecular weight modifier added is not particularly limited, but is preferably 0.002 to 20 parts by mass per 100 parts by mass of the chloroprene monomer and the unsaturated nitrile monomer combined. The amount of xanthogen compound added is preferably 0.002 to 20 parts by mass per 100 parts by mass of the chloroprene monomer and the unsaturated nitrile monomer combined. By setting the amount within such a range, the polymerization reaction can be easily controlled, and an appropriate amount of the functional group represented by chemical formula (1) can be introduced into the chloroprene-unsaturated nitrile copolymer.

As the polymerization initiator, a known radical polymerization initiator can be used, such as potassium persulfate, benzoyl peroxide, hydrogen peroxide, and azo compounds. A known RAFT agent can also be used during polymerization. In one embodiment of the present invention, a RAFT agent does not need to be used during polymerization.

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. The polymerization may be carried out so that the final conversion rate of the monomer falls within the range of 40 to 95% by mass. In order to adjust the final conversion rate, a polymerization terminator that stops the polymerization reaction may be added to terminate the polymerization when the desired conversion rate is reached.

There are no particular limitations on the polymerization terminator, and any known polymerization terminator commonly used in emulsion polymerization of chloroprene can be used. Examples of polymerization terminators include phenothiazine (thiodiphenylamine), 4-t-butylcatechol, and 2,2-methylenebis-4-methyl-6-t-butylphenol.

Furthermore, to the chloroprene-unsaturated nitrile copolymer latex obtained by the manufacturing method of one embodiment of the present invention, freezing stabilizers, emulsion stabilizers, viscosity modifiers, antioxidants, preservatives, etc. can be added as desired after polymerization, within the scope that does not impair the effects of the present invention.

3. Rubber component of chloroprene-unsaturated nitrile copolymer latex One embodiment of the present invention is the rubber component of the chloroprene-unsaturated nitrile copolymer. The method for obtaining the rubber component of the chloroprene-unsaturated nitrile copolymer latex is not particularly limited. As an example, the rubber component of the chloroprene-unsaturated nitrile copolymer can be obtained by mixing the chloroprene-unsaturated nitrile copolymer latex with a large amount of methanol, precipitating, filtering, and drying. As an example, the rubber component of the chloroprene-unsaturated nitrile copolymer can be obtained by freeze-drying the chloroprene-unsaturated nitrile copolymer latex, specifically, by adjusting the pH of the chloroprene-unsaturated nitrile copolymer latex, freeze-drying, washing with water, and drying with hot air. The rubber component of the chloroprene-unsaturated nitrile copolymer includes a methanol precipitate of the chloroprene-unsaturated nitrile copolymer latex and a freeze-dried product of the chloroprene-unsaturated nitrile copolymer latex.

In one embodiment of the rubber component, a rubber composition having the composition described in the examples is prepared, and the rubber composition is press-vulcanized at 170°C for 20 minutes in accordance with JIS K 6250 to produce a vulcanized molded product. When the vulcanized molded product is immersed in a test oil (high-grade automotive lubricating oil, ASTM No. 3, IRM 903 oil) at 130°C for 72 hours, the volume change is preferably less than 45% by mass.

In the rubber component according to one embodiment of the present invention, a rubber composition having the composition described in the Examples is prepared, and the rubber composition is press-vulcanized at 170°C for 20 minutes to produce a cylindrical vulcanized molded product having a diameter of 15 mm and a height of 25 mm. The vulcanized molded product is then evaluated in a constant strain flexometer test based on JIS K 6265:2018 under conditions of 50°C, strain of 0.175 inches, load of 55 pounds, and vibration frequency of 1,800 times per minute. The heat generation (ΔT) is preferably less than 45°C.
The heat generation property can be evaluated by a Goodrich Flexometer (JIS K 6265:2018). The Goodrich Flexometer is a test method for evaluating fatigue properties due to heat generation inside a test piece of vulcanized rubber or the like by applying a dynamic repeated load to the test piece, and more specifically, a static initial load is applied to the test piece under constant temperature conditions, and a sine vibration of a constant amplitude is further applied to measure the heat generation temperature and creep amount of the test piece that change over time.

4. Rubber Composition The rubber composition according to one embodiment of the present invention includes the above-mentioned rubber component. In addition to the above-mentioned rubber component, the rubber composition according to the present invention may include a vulcanizing agent, a vulcanization accelerator, an antioxidant, a filler, a reinforcing material, a silane coupling agent, a plasticizer, a softener, a lubricant, a processing aid, and may further include components such as a stabilizer, a flame retardant, and a vulcanization retarder, as long as the effects of the present invention are not impaired.

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. The vulcanizing agent is preferably a vulcanizing agent that can be used for vulcanizing chloroprene-based rubber. One or more vulcanizing agents may be freely selected and used. Examples of the vulcanizing agent include sulfur, zinc oxide, and organic peroxide.

An example of a metal oxide is zinc oxide. The metal oxide preferably contains zinc oxide, and more preferably is zinc oxide.

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, di(2-ethylhexyl) 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-tetramethylbutylperoxy-2-ethylhexanoate, disuccinic acid peroxide, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane, t-hexylperoxy-2-ethylhexanoate, di(4-methylbenzoyl)peroxide, t-butylperoxy-2-ethylhexanoate, di(3-methylbenzoyl)peroxide, benzoyl(3-methylbenzoyl)peroxide, dibenzoyl peroxide, 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-butylperoxy butylperoxyacetate, 2,2-di-(t-butylperoxy)butane, t-butylperoxybenzoate, n-butyl 4,4-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)hexyne-3, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, and t-butyl hydroperoxide. Among these, at least one 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)hexyne-3 is preferred, with 1,4-bis[(t-butylperoxy)isopropyl]benzene being particularly preferred.

The rubber composition according to the present invention preferably contains 3 to 15 parts by mass of a vulcanizing agent relative to the rubber component contained in the rubber composition, from the viewpoint of ensuring processing safety and being able to obtain a good vulcanizate. 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 relative to 100 parts by mass of the rubber component contained in the rubber composition, and may be within a range between any two of the numerical values exemplified here.

4.2 Acid Acceptor The rubber composition according to one embodiment of the present invention may contain an acid acceptor. Examples of the acid acceptor include magnesium oxide, lead oxide, lead tetroxide, iron trioxide, titanium dioxide, calcium oxide, and hydrotalcite. As the hydrotalcite, one represented by the following formula may be used.
[M ²⁺ _1-x M ³⁺ _x (OH) ₂ ] ^x+ [A _n-x/n・mH ₂ O] ^x-

In the above formula,
M ²⁺ : at least one divalent metal ion selected from Mg ²⁺ , Zn ²⁺ , etc. M ³⁺ : at least one trivalent metal ion selected from Al ³⁺ , Fe ³⁺ , etc. A ^n- : at least one n-type anion selected from CO ₃ ^2- , Cl ^- , NO ₃ ^2- , etc. X: 0<X≦0.33.

Examples of _hydrotalcite include _Mg4.3Al2 ( _OH ) _{12.6CO3.3.5H2O} , _Mg3ZnAl2 (OH) _12CO3.3H2O _, _Mg4.5Al2 ₍ _OH ₎ _13CO3.3.5H2O _, _Mg4.5Al2 ( _OH ) _13CO3 , _Mg4Al2 ₍ _OH ) _12CO3.3.5H2O _, _Mg6Al2 ₍ _OH ₎ _16CO3.4H2O _, _Mg5Al2 ₍ _OH ) _14CO3.4H2O , _and _Mg3Al2 ( _OH ) _10CO3.1.7H2O _. _Particularly _preferred _is _Mg4.3 _Al2 ₍ _OH ) _{12.6CO3.3.5H2O} , _Mg3ZnAl2 ₍ _OH ₎ _12CO3.3H2O .

The amount of acid acceptor added may be 0.1 to 15 parts by mass per 100 parts by mass of the rubber component. The amount of hydrotalcite added may 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 a range between any two of the numerical values exemplified here. Hydrotalcite may be used alone or in combination of two or more types.

4.3 Vulcanization Accelerator 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 relative to 100 parts by mass of the rubber composition contained in the rubber composition. The content of the vulcanization accelerator is, 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 a range between any two of the numerical values exemplified here. The rubber composition according to the present invention may not contain a vulcanization accelerator.

The type of vulcanization accelerator is not particularly limited as long as it does not impair the effects of the present invention. The vulcanization accelerator is preferably one that can be used for vulcanization of chloroprene-based rubber. One or more vulcanization accelerators can be freely selected and used. Examples of vulcanization accelerators include thiuram-based, dithiocarbamate-based, thiourea-based, guanidine-based, xanthogenate-based, and thiazole-based.

Examples of thiuram vulcanization accelerators include tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide, tetrabutylthiuram disulfide, tetrakis(2-ethylhexyl)thiuram disulfide, tetramethylthiuram monosulfide, and dipentamethylenethiuram tetrasulfide.
Examples of the dithiocarbamate vulcanization accelerator include sodium dibutyldithiocarbamate, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc N-ethyl-N-phenyldithiocarbamate, zinc N-pentamethylenedithiocarbamate, copper dimethyldithiocarbamate, ferric dimethyldithiocarbamate, and tellurium diethyldithiocarbamate.
Examples of the thiourea-based vulcanization accelerator include thiourea compounds such as ethylene thiourea, diethyl thiourea (N,N'-diethyl thiourea), trimethyl thiourea, diphenyl thiourea (N,N'-diphenyl thiourea), and 1,3-trimethylene-2-thiourea.
Examples of the guanidine-based vulcanization accelerator include 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, and di-o-tolylguanidine salts of dicatechol borate.
Examples of the xanthogenate-based vulcanization accelerator include zinc butylxanthogenate and zinc isopropylxanthogenate.
Examples of the thiazole-based vulcanization accelerator 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 may be used alone or in combination of two or more.

4.4 Filler (reinforcement)
The rubber composition according to the present invention may contain a filler.
Examples of the filler (reinforcing material) 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, lamp black, thermal carbon such as FT and MT, acetylene black, ketjen black, silica, clay, talc, and calcium carbonate. These may be used alone or in combination of two or more.

The rubber composition according to one embodiment of the present invention may contain 5 to 130 parts by mass of a filler per 100 parts by mass of the 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, or may be within a range between any two of the numerical values exemplified here. By containing the filler content within the above numerical range, the rubber composition according to one embodiment of the present invention can appropriately adjust the hardness of the vulcanized molded body.

4.5 Silane coupling agent The rubber composition according to one embodiment of the present invention may contain a silane coupling agent. When the rubber composition according to one embodiment of the present invention contains silica as a filler, it is preferable that the rubber composition contains a silane coupling agent. The silane coupling agent is not particularly limited, 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, from the viewpoint of scorch resistance and reinforcing effect, vinyl coupling agents, methacrylic coupling agents, and acrylic coupling agents that start reacting under high temperature conditions during crosslinking are preferred.

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 a range between any two of the numerical values exemplified here. These may be used alone or in combination of two or more. By containing the above silane coupling agent and setting the content of the silane coupling agent within the above numerical range, it is possible to improve the dispersibility of the silica filler in the rubber and the reinforcing effect between the rubber and the silica filler, and also to suppress the occurrence of scorch.

4.6 Plasticizer The plasticizer is not particularly limited as long as it is compatible with the chloroprene-unsaturated nitrile copolymer rubber, and examples thereof include vegetable oils such as rapeseed oil, phthalate-based plasticizers, DOS (dioctyl sebacate), DBS (dibutyl sebacate), DOA (dioctyl adipate), ester-based plasticizers, ether ester-based plasticizers, thioether-based plasticizers, aromatic oils, naphthenic oils, and the like. These can be used alone or in combination of two or more. The amount of plasticizer added can be 0 to 50 parts by mass relative to 100 parts by mass of the rubber component contained in the rubber composition, and 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 between any two of the numerical values exemplified here.

4.7 Lubricant, Processing Aid The rubber composition according to the present invention may further contain a lubricant and/or a processing aid. The lubricant and processing aid are mainly added to improve processability, such as making the rubber composition easier to peel off from rolls, molding dies, extruder screws, etc. Examples of the lubricant and processing aid include fatty acids such as stearic acid, paraffin processing aids such as polyethylene, fatty acid amides, vaseline, factice, etc. These may be used alone 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 the lubricant and processing aid per 100 parts by mass of the rubber component, and may also be 1 to 10 parts by mass. The content of the lubricant and processing aid 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 a range between any two of the numerical values exemplified here.

4.8 Others In addition to the above-mentioned components, the rubber composition according to the present invention may further contain components such as an antiaging agent, an antioxidant, a flame retardant, and a vulcanization retarder, as long as the effects of the present invention are not impaired. Examples of the antiaging agent and the antioxidant include ozone antiaging agents, phenolic antiaging agents, amine antiaging agents, acrylate antiaging agents, imidazole antiaging agents, aromatic secondary amine antiaging agents, carbamic acid metal salts, waxes, phosphorus antiaging agents, and sulfur antiaging agents. Examples of the imidazole antiaging agents include 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, and zinc salts of 2-mercaptobenzimidazole. The rubber composition according to the present invention may contain 0.1 to 10 parts by mass of the antiaging agent and the antioxidant in total, relative to 100 parts by mass of the rubber component contained in the rubber composition.

5. Method for Producing Rubber Composition The rubber composition according to one embodiment of the present invention is obtained by kneading the rubber component of the chloroprene-unsaturated nitrile copolymer latex and other necessary components at a temperature equal to or lower than the vulcanization temperature. Examples of the device for kneading the raw material components include conventional kneading devices such as a mixer, a Banbury mixer, a kneader mixer, and an open roll.

6. Unvulcanized molded body, vulcanized product, and vulcanized molded body The unvulcanized molded body according to one embodiment of the present invention uses the rubber composition according to one embodiment of the present invention, and is a molded body (molded product) of the rubber composition (unvulcanized state) according to one embodiment of the present invention. The manufacturing method of the unvulcanized molded body according to one embodiment of the present invention includes a step of molding the rubber composition (unvulcanized state) according to one embodiment of the present invention. The unvulcanized molded body according to one embodiment of the present invention is made of the rubber composition (unvulcanized state) according to one embodiment of the present invention.

The vulcanizate according to one embodiment of the present invention is a vulcanizate of the rubber composition according to one embodiment of the present invention. The method for producing the vulcanizate according to one embodiment of the present invention includes a step of vulcanizing the rubber composition according to one embodiment of the present invention.

The vulcanized molded product according to one embodiment of the present invention is a vulcanized molded product of a rubber composition according to one embodiment of the present invention. The vulcanized molded product according to one embodiment of the present invention uses a vulcanizate according to one embodiment of the present invention, and is a molded product (molded article) of the vulcanizate according to one embodiment of the present invention. The vulcanized molded product according to one embodiment of the present invention is made of a vulcanizate according to one embodiment of the present invention.

The vulcanized molded product 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, and can also be obtained by vulcanizing a molded product obtained by molding a rubber composition (unvulcanized state) according to one embodiment of the present invention. The vulcanized molded product 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 or during molding. The method for producing a vulcanized molded product according to one embodiment of the present invention includes a step of molding a vulcanized product according to one embodiment of the present invention, or a step of vulcanizing an unvulcanized molded product according to one embodiment of the present invention.

The vulcanized molded article according to one embodiment of the present invention preferably has a volume change of less than 45% by mass when immersed in a test oil (high-strength lubricating oil for automobiles, ASTM No. 3, IRM 903 oil) at 130°C for 72 hours. In addition, the vulcanized molded article according to one embodiment of the present invention is preferably cylindrical with a diameter of 15 mm and a height of 25 mm, and has a heat generation (ΔT) of less than 45°C as determined by evaluation using a constant strain flexometer test based on JIS K 6265:2018 under conditions of 50°C, strain of 0.175 inches, load of 55 pounds, and vibration frequency of 1,800 times per minute.

The unvulcanized molded body, vulcanized product, and vulcanized molded body 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 generates little heat in dynamic environments, so it can be used as various components where these properties are required. The rubber composition, vulcanized product, and vulcanized molded body 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 parts (e.g., automotive seal materials), hose materials, rubber molded products, gaskets, rubber rolls, industrial cables, industrial conveyor belts, and sponges. In particular, they can be used as transmission belts, conveyor belts, hoses, wipers, immersion products, seal parts, adhesives, boots, rubber-coated cloth, rubber rolls, anti-vibration rubber, or sponge products.

(Rubber parts for automobiles)
Rubber components for automobiles include gaskets, oil seals, and packings, which are components that prevent leakage of liquids and gases and intrusion of garbage and foreign objects such as rainwater and dust into machines and devices. Specifically, there are gaskets used for fixed applications and oil seals and packings used for moving parts and movable parts. For gaskets in which the sealing part is fixed with bolts or the like, various materials are used according to the purpose, as opposed to soft gaskets such as O-rings and rubber sheets. In addition, packings are used for rotating parts such as the shafts of pumps and motors, moving parts of valves, reciprocating parts such as pistons, connecting parts of couplers, water stop parts of water faucets, etc. The rubber composition of the present invention can increase oil resistance and reduce heat generation in dynamic environments. This makes it possible to manufacture automobile parts that have excellent oil resistance and generate less heat in dynamic environments, which was difficult to achieve with conventional rubber compositions.

(Hose material)
Hose materials are flexible pipes, and specifically include high- and low-pressure hoses for water supply, oil supply, air supply, steam, and hydraulic use. The rubber composition of the present invention can improve the oil resistance of the hose material and reduce heat generation in a dynamic environment while maintaining the processability of the unvulcanized product. This makes it possible to manufacture, for example, a hose material that has excellent oil resistance and generates little heat in a dynamic environment, which was difficult to achieve with conventional rubber compositions.

(Rubber mold)
The rubber molded products include anti-vibration rubber, vibration-damping materials, boots, etc. Anti-vibration rubber and vibration-damping materials are rubbers that prevent the transmission and spread of vibrations, and specifically include torsional dampers, engine mounts, muffler hangers, etc. for automobiles and various vehicles that absorb vibrations during engine operation to prevent noise. The rubber composition of the present invention can increase the oil resistance of anti-vibration rubber and vibration-damping materials and reduce heat generation in dynamic environments. This makes it possible to produce anti-vibration rubber and vibration-damping materials that have excellent oil resistance and generate less heat in dynamic environments, which was difficult to do with conventional rubber compositions.
A boot is a bellows-shaped member whose outer diameter gradually increases from one end to the other end, and specific examples include boots for constant velocity joint covers, boots for ball joint covers (dust cover boots), and boots for rack and pinion gears, which are used to protect drive parts such as automobile drive systems. The rubber composition of the present invention can improve oil resistance and reduce heat generation in dynamic environments. This makes it possible to manufacture boots that can be used in harsher environments than conventional rubber compositions.

(Gaskets, etc.)
Gaskets, oil seals and packings are components that prevent leakage of liquids or gases and intrusion of garbage or foreign objects such as rainwater or dust into machines or equipment. Specifically, there are gaskets used for fixed applications and oil seals and packings used for moving parts. For gaskets where the sealing part is fixed with bolts or the like, various materials are used according to the purpose, as opposed to soft gaskets such as O-rings and rubber sheets. Packings are also used for rotating parts such as the shafts of pumps and motors, moving parts of valves, reciprocating parts such as pistons, connecting parts of couplers, water stop parts of water faucets, etc. The rubber composition of the present invention can increase the oil resistance of these members and reduce heat generation in dynamic environments. This makes it possible to manufacture sealing members that have excellent oil resistance and generate less heat in dynamic environments, which was difficult to achieve with conventional rubber compositions.

(Rubber roll)
A rubber roll is manufactured by adhesively covering a metal core such as an iron core with rubber, and is generally manufactured by spirally winding a rubber sheet around a metal iron core. Rubber materials such as NBR, EPDM, and CR are used for rubber rolls according to the required characteristics of various applications such as papermaking, various metal manufacturing, film manufacturing, printing, general industrial use, agricultural equipment such as rice hullers, and food processing. CR has good mechanical strength that can withstand the friction of the objects being transported, so it is used in a wide range of rubber roll applications. Furthermore, there is a problem that rubber rolls that transport heavy objects are deformed by load, and improvements are required. The rubber composition of the present invention can increase the oil resistance of the rubber roll and reduce heat generation in a dynamic environment. This makes it possible to manufacture an embossing rubber roll that has excellent oil resistance and generates little heat in a dynamic environment, which was difficult to achieve with conventional rubber compositions.

(Industrial cables)
Industrial cables are linear components for transmitting electrical or optical signals. They are made by covering a good conductor such as copper or a copper alloy, or an optical fiber, with an insulating covering layer, and a wide variety of industrial cables are manufactured depending on their structure and installation location. The rubber composition of the present invention can increase the oil resistance of industrial cables and reduce heat generation in dynamic environments. This makes it possible to manufacture industrial cables that have excellent oil resistance and generate less heat in dynamic environments, which was difficult to achieve with conventional rubber compositions.

(Industrial conveyor belts)
Industrial conveyor belts are available in rubber, resin, and metal, and are selected according to a wide variety of usage methods. Among these, rubber conveyor belts are inexpensive and widely used, but when used in an environment where there is a lot of friction and collision with the transported goods, they have been damaged due to deterioration. The rubber composition of the present invention can increase the oil resistance of industrial conveyor belts and reduce heat generation in dynamic environments. This makes it possible to manufacture industrial conveyor belts that have excellent oil resistance and generate little heat in dynamic environments, which can be used in harsh environments that were difficult to achieve with conventional rubber compositions.

(sponge)
A sponge is a porous material with numerous fine holes inside, and is specifically used in vibration-proofing materials, sponge seal parts, wet suits, shoes, etc. The rubber composition of the present invention can improve the acid resistance and water resistance of the sponge. In addition, since a chloroprene-unsaturated nitrile copolymer rubber is used, it is also possible to improve the flame retardancy of the sponge. This makes it possible to produce a sponge with excellent oil resistance and low heat generation in dynamic environments, which are used in harsh environments that were difficult to achieve with conventional rubber compositions, and a sponge with excellent flame retardancy. Furthermore, the hardness of the sponge obtained can be appropriately adjusted by adjusting the content of the foaming agent, etc.

Methods for molding the rubber composition (unvulcanized state) and vulcanized product according to one embodiment of the present invention include press molding, extrusion molding, calendar molding, and the like. The temperature for vulcanizing the rubber composition may 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 may be set appropriately according to the composition of the rubber composition, the shape of the unvulcanized molded product, and the like.

The present invention will be explained in more detail below based on examples, but the present invention should not be interpreted as being limited to these.

Example 1
A 3-liter polymerization vessel equipped with a heating/cooling jacket and a stirrer was charged with 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 Co., Ltd.), 0.4 parts by mass of potassium hydroxide, 1.0 part by mass of sodium salt of β-naphthalenesulfonic acid formalin condensate (manufactured by Kao Corporation), and 0.5 parts by mass of diisopropyl xanthogen disulfide. 0.1 parts by mass of potassium persulfate was added as a polymerization initiator, and emulsion polymerization was carried out under a nitrogen stream at a polymerization temperature of 40° C. During the polymerization, the chloroprene monomer was added in portions so that the amount of the unsaturated nitrile monomer in the polymerization liquid was maintained at 70 parts by mass ± 20 parts by mass when the amount of unreacted monomers in the polymerization liquid (the total of the chloroprene monomer and the acrylonitrile monomer) was taken as 100 parts by mass. The chloroprene monomer was added in portions 20 seconds after the start of polymerization, and the amount of the portion added was adjusted with an electromagnetic valve based on the change in the heat quantity of the refrigerant for 10 seconds from the start of polymerization, and the flow rate was readjusted every 10 seconds thereafter, so that the polymerization was carried out continuously. When the polymerization rate relative to the total amount of chloroprene and acrylonitrile reached 65%, 0.02 parts by mass of phenothiazine, a polymerization terminator, was added to terminate the polymerization.
Next, unreacted monomers, organic solvents, etc. were removed by distillation under reduced pressure, and the residue was concentrated to obtain a chloroprene-unsaturated nitrile copolymer latex 1 having a solid content of 50% by mass.

(Example 2, Comparative Examples 1 to 4)
Chloroprene-unsaturated nitrile copolymer latexes 2 to 6 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 portions, and the amount of unsaturated nitrile monomer relative to the unreacted monomer in the polymerization liquid maintained during polymerization were as shown in Table 1.

(Comparative Example 5)
The amount of chloroprene monomer initially added, the amount of acrylonitrile monomer, the amount of water, the amount of chloroprene monomer added in portions, and the amount of unsaturated nitrile monomer relative to the unreacted monomer in the polymerization liquid maintained during polymerization were as shown in Table 1, and chloroprene-unsaturated nitrile copolymer latex 7 was obtained in the same manner as in Example, except that 0.2 part by mass of benzyl butyl trithiocarbonate was used instead of 0.5 part by mass of diisopropyl xanthogen disulfide.

(Content of Unsaturated Nitrile Hydrolyzate in Chloroprene-Unsaturated Nitrile Copolymer Latex)
About 1 g of the chloroprene-unsaturated nitrile copolymer latex according to each of the Examples and Comparative Examples was weighed out and diluted to 25 ml with tetrahydrofuran. The obtained solution was analyzed by pyrolysis gas chromatography to calculate the contents of the chloroprene-unsaturated nitrile copolymer, acrylamide, 2-cyanoethanol and 2-cyanoethyl ether in the chloroprene-unsaturated nitrile copolymer latex.
Gas chromatography: Instrument name: Agilent Technologies 8890GC system; Column: DB-1 0.32 mmφ x 30 m (film thickness 5.0 μm)
Column temperature: 50°C (5 min) → 50°C/min → 100°C → 15°C/min → 300°C (30 min)
Inlet temperature: 270℃
Detector temperature: 300°C
Detector: FID
The chloroprene-unsaturated nitrile copolymer latexes according to the examples and comparative examples did not give off an irritating odor, and no generation of ammonia or carboxylic acid was observed.

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

The evaluation was based on the following criteria.
○: Less than 1000 cps ×: 1000 cps or more

<Segregation of rubber components>
The pH of the chloroprene-unsaturated nitrile copolymer latex according to each of the Examples and Comparative Examples was adjusted to 7.0 using acetic acid or sodium hydroxide, and then the chloroprene-acrylonitrile copolymer latex was freeze-coagulated on a metal plate cooled to −20° C. to break the emulsion and obtain a sheet. The sheet was washed with water and then dried at 130° C. for 15 minutes to obtain a solid chloroprene-acrylonitrile copolymer rubber component (chloroprene-acrylonitrile copolymers 1 to 7).

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

Specifically, an elemental analyzer (Sumigraph 220F: manufactured by Sumika Chemical Analysis Center Co., Ltd.) was used to measure the nitrogen atom content in 100 mg of chloroprene-unsaturated nitrile copolymer, and the content of acrylonitrile monomer units was calculated. Elemental analysis was performed as follows. The electric furnace temperatures were set at 900°C for the reactor, 600°C for the reduction furnace, 70°C for the column, and 100°C for the detector, and oxygen gas was flowed at 0.2 mL/min as the combustion gas and helium gas was flowed at 80 mL/min as the carrier gas. A calibration curve was created using aspartic acid (10.52%), which has a known nitrogen content, as the standard substance.

<Preparation of Rubber Composition>
Rubber compositions were prepared using the rubber components (chloroprene-acrylonitrile copolymers 1 to 7) in the chloroprene-unsaturated nitrile copolymer latexes obtained by freeze-drying the chloroprene-acrylonitrile copolymer latexes 1 to 7 as described above.
Specifically, 100 parts by mass of the rubber component,
Antiaging agent (4,4'-bis(α,α-dimethylbenzyl)diphenylamine (Nocrac CD, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.)) 3 parts by mass,
Antiaging agent (N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., Nocrac 6C)) 1 part by mass,
Acid acceptor (magnesium oxide (Kyowamag 150, manufactured by Kyowa Chemical Industry Co., Ltd.)) 4 parts by mass,
Zinc oxide (manufactured by Sakai Chemical Industry Co., Ltd., zinc oxide type 2) 5 parts by mass,
- 1 part by mass of vulcanization accelerator (trimethylthiourea (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., Noccela TMU)),
Filler (carbon black FEF (Asahi Carbon Co., Ltd., Asahi #60)) 50 parts by mass,
Plasticizer (ether ester plasticizer (ADEKA Cizer RS-700, manufactured by ADEKA CORPORATION)) 10 parts by mass,
One part by mass of a lubricant (stearic acid (Stearic Acid 50S, manufactured by New Japan Chemical Co., Ltd.)) was added, and the mixture was kneaded with an 8-inch open roll to obtain Rubber Compositions 1 to 7.

<Preparation of vulcanized molded body>
The above rubber compositions 1 to 7 were used to prepare vulcanized molded articles. Specifically, the obtained rubber compositions 1 to 7 were press-vulcanized at 170°C for 20 minutes based on JIS K 6250 to prepare sheet-shaped vulcanized molded articles having a thickness of 2 mm. The rubber compositions 1 to 7 were also press-vulcanized at 170°C for 20 minutes to prepare vulcanized molded articles for Goodrich tests (cylindrical vulcanized molded articles having a diameter of 15 mm and a height of 25 mm).

(Oil resistance)
A test piece measuring 25 mm in length and 20 mm in width was punched out from the sheet-like vulcanized molded product. The test piece was immersed in a test oil (high-grade lubricating oil for automobiles, ASTM No. 3, IRM 903 oil) at 130°C for 72 hours. The volume change rate ΔV was calculated according to JIS K 6258. The volume change rate ΔV was evaluated according to the following criteria.
○: Less than 45% by weight ×: 45% by weight or more

(Feverish)
The heat generation was evaluated using a Goodrich Flexometer (JIS K 6265:2018). The Goodrich Flexometer is a test method for evaluating fatigue properties due to heat generation inside a test piece by applying a dynamic repeated load to a test piece such as vulcanized rubber. In detail, a static initial load is applied to the test piece under a constant temperature condition, and a sine vibration of a constant amplitude is further applied to measure the heat generation temperature and creep amount of the test piece that change over time. The test method conforms to JIS K 6265:2018, and heat generation (ΔT) was measured under conditions of 50°C, strain of 0.175 inches, load of 55 pounds, and vibration frequency of 1,800 times per minute, and evaluated according to the following evaluation criteria.
○: Less than 45°C ×: 45°C or higher

Claims

A chloroprene-unsaturated nitrile copolymer latex comprising a chloroprene-unsaturated nitrile copolymer comprising 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 a combustion method,
The chloroprene-unsaturated nitrile copolymer has a functional group having a structure represented by chemical formula (1),
The chloroprene-unsaturated nitrile copolymer latex has a content of an unsaturated nitrile hydrolysate of 0.10 to 9.00 parts by mass based on 100 parts by mass of the chloroprene-unsaturated nitrile copolymer.
(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.)
The unsaturated nitrile monomer unit is an acrylonitrile monomer unit,
The chloroprene-unsaturated nitrile copolymer has an acrylonitrile bond amount of 2 mass% or more as measured in accordance with JIS K 6451-1,
The chloroprene-unsaturated nitrile copolymer latex according to claim 1, wherein the content of the acrylonitrile hydrolyzate in the chloroprene-unsaturated nitrile copolymer latex is 0.10 to 9.00 parts by mass based on 100 parts by mass of the chloroprene-unsaturated nitrile copolymer.
The rubber component of the chloroprene-unsaturated nitrile copolymer latex according to claim 1 or 2.
A rubber composition comprising the rubber component according to claim 3.
A vulcanized molded article of the rubber composition according to claim 4.
The vulcanized molded article according to claim 5, which is a transmission belt, a conveyor belt, a hose, a wiper, a dipping product, a sealing part, an adhesive, a boot, a rubber-coated cloth, a rubber roll, a vibration-proof rubber or a sponge product.
A method for producing a chloroprene-unsaturated nitrile copolymer latex comprising a chloroprene-unsaturated nitrile copolymer containing chloroprene monomer units and unsaturated nitrile monomer units, comprising:
The production method includes a polymerization step of polymerizing raw material monomers including a chloroprene monomer and an unsaturated nitrile monomer in an aqueous solution containing water in the presence of a xanthogen compound to obtain a chloroprene-unsaturated nitrile copolymer,
The production method, wherein the amount of the water is less than 150 parts by mass when the total amount of the raw material monomers used in the polymerization step is 100 parts by mass.