Chloroprene polymer, chloroprene polymer composition, vulcanized molded article and roll

Abstract

A chloroprene polymer which has a structural unit derived from chloroprene and a structural unit derived from an unsaturated nitrile, wherein: the 1H-NMR spectrum of this chloroprene polymer as determined in a deuterated chloroform solvent has a peak top at 5.80 to 6.00 ppm; with respect to the 1H-NMR spectrum, the peak area ratio of the peak area A of 5.80 to 6.00 ppm to the peak area B of 4.05 to 6.20 ppm, namely A / B is more than 1.1 / 100 but not more than 2.3 / 100; and the content of the structural unit derived from an unsaturated nitrile is more than 0% by mass but not more than 23% by mass.

Description

[Technical field]

[0001] The present invention relates to a chloroprene polymer, a chloroprene polymer composition, a vulcanized molded article, a roll, and the like. [Background technology]

[0002] Chloroprene polymers are widely used as materials for industrial rubber products. However, there is a problem that the oil resistance of vulcanized molded products obtained using chloroprene polymers is insufficient and they cannot be used in oily environments such as around engines. In response to this, a method for producing a chloroprene copolymer copolymerized with an unsaturated nitrile is known as a means for improving oil resistance (see, for example, Patent Document 1 below). The chloroprene copolymer copolymerized with an unsaturated nitrile can be vulcanized and molded to be used for products such as transmission belts, conveyor belts, hoses, and wipers (see, for example, Patent Documents 2 and 3 below). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 55-145715 [Patent Document 2] JP 2012-82289 A [Patent Document 3] International Publication No. 2013 / 015043 Summary of the Invention [Problem to be solved by the invention]

[0004] However, for chloroprene polymers, in addition to obtaining excellent oil resistance in a vulcanized molded article, it is required to obtain excellent moldability while obtaining excellent compression set and cold resistance in a vulcanized molded article.

[0005] One aspect of the present invention is to provide a chloroprene polymer that can provide a vulcanized molded article having excellent oil resistance, compression set and cold resistance while obtaining excellent moldability. Another aspect of the present invention is to provide a chloroprene polymer composition containing the chloroprene polymer. Another aspect of the present invention is to provide a vulcanized molded article of the chloroprene polymer composition. Another aspect of the present invention is to provide a roll including the vulcanized molded article. [Means for solving the problem]

[0006] One aspect of the present invention relates to a chloroprene polymer having a chloroprene-derived structural unit and an unsaturated nitrile-derived structural unit, the chloroprene polymer having a peak top at 5.80 to 6.00 ppm in a H-NMR spectrum measured in a deuterated chloroform solvent, the peak area ratio A / B of a peak area A from 5.80 to 6.00 ppm to a peak area B from 4.05 to 6.20 ppm in the H-NMR spectrum being greater than 1.1 / 100 and not greater than 2.3 / 100, and the content of the unsaturated nitrile-derived structural unit being greater than 0 mass% and not greater than 23 mass%.

[0007] Another aspect of the present invention relates to a chloroprene polymer composition containing the above-mentioned chloroprene polymer.

[0008] Another aspect of the present invention relates to a vulcanized molded article of the above-mentioned chloroprene polymer composition.

[0009] Another aspect of the present invention relates to a roll comprising a vulcanized molded product of a chloroprene polymer composition, the chloroprene polymer composition containing a chloroprene polymer, the chloroprene polymer having a chloroprene-derived structural unit and an unsaturated nitrile-derived structural unit, the chloroprene polymer having a peak top at 5.80 to 6.00 ppm in a 1H-NMR spectrum measured in a deuterated chloroform solvent, the peak area ratio A / B of a peak area A at 5.80 to 6.00 ppm and a peak area B at 4.05 to 6.20 ppm in the 1H-NMR spectrum being greater than 1.1 / 100 and not greater than 2.3 / 100, and the content of the unsaturated nitrile-derived structural unit being greater than 0 mass% and not greater than 23 mass%. Effect of the Invention

[0010] According to one aspect of the present invention, there is provided a chloroprene polymer which can provide a vulcanized molded article having excellent oil resistance, compression set and cold resistance while obtaining excellent moldability. According to another aspect of the present invention, there is provided a chloroprene polymer composition containing the chloroprene polymer. According to another aspect of the present invention, there is provided a vulcanized molded article of the chloroprene polymer composition. According to another aspect of the present invention, there is provided a roll including the vulcanized molded article. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the preferred embodiments. However, the present invention is not limited to the preferred embodiments described below.

[0012] The numerical range "A or more" means A and a range exceeding A. The numerical range "A or less" means A and a range less than A. In the numerical ranges described in stages in this specification, the upper limit or lower limit of a numerical range in a certain stage can be arbitrarily combined with the upper limit or lower limit of a numerical range in another stage. In the numerical ranges described in this specification, the upper limit or lower limit of the numerical range may be replaced with a value shown in the examples. Unless otherwise specified, the materials exemplified in this specification can be used alone or in combination of two or more types. The content of each component in the composition means the total amount of the multiple substances present in the composition when multiple substances corresponding to each component are present in the composition, unless otherwise specified.

[0013] A "peak" in an NMR spectrum is a convex inflection point in the NMR spectrum, and includes not only peaks that show a clear convexity but also shoulder shapes. When there are multiple peaks in a specific chemical shift (horizontal axis) range in an NMR spectrum, the "peak area" in that range is the sum of the peak areas of the multiple peaks.

[0014] <Chloroprene polymer> The chloroprene polymer according to this embodiment is a chloroprene-unsaturated nitrile copolymer having structural units derived from chloroprene (chloroprene units, chloroprene bond units) and structural units derived from unsaturated nitrile (unsaturated nitrile units, unsaturated nitrile bond units). The chloroprene polymer according to this embodiment has chloroprene and unsaturated nitrile as monomer units. The content of the structural units derived from unsaturated nitrile is more than 0 mass% and 23 mass% or less based on the total amount of the chloroprene polymer.

[0015] The chloroprene polymer according to the present embodiment has a peak top at 5.80 to 6.00 ppm in a 1H-NMR spectrum measured in a deuterated chloroform solvent. In the 1H-NMR spectrum of the chloroprene polymer according to the present embodiment, the peak area ratio A / B of the peak area A at 5.80 to 6.00 ppm and the peak area B at 4.05 to 6.20 ppm is more than 1.1 / 100 and not more than 2.3 / 100.

[0016] The chloroprene polymer according to this embodiment has excellent moldability, and can achieve a scorch time of, for example, more than 8 minutes (preferably 10 minutes or more, and more preferably 11 minutes or more) as measured in accordance with JIS K 6300-1.

[0017] According to the chloroprene polymer of this embodiment, a vulcanized molded product having excellent oil resistance, compression set, and cold resistance can be obtained. According to the chloroprene polymer of this embodiment, a vulcanized molded product having excellent oil resistance, compression set, and cold resistance can be obtained by the evaluation method described in the examples. As a vulcanized molded product obtained using 100 parts by mass of chloroprene polymer, 1 part by mass of trimethylthiourea, 3 parts by mass of 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, 1 part by mass of stearic acid, 1 part by mass of N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine, 50 parts by mass of carbon black FEF, 10 parts by mass of ether ester plasticizer, 4 parts by mass of magnesium oxide, and 5 parts by mass of zinc oxide, a vulcanized molded product having excellent oil resistance, compression set, and cold resistance can be obtained. The chloroprene polymer according to this embodiment has oil resistance such that a volume change measured in accordance with JIS K 6258 of less than 60% (preferably less than 50%, more preferably 45% or less) can be achieved, a compression set measured in accordance with JIS K 6262 of less than 40% (preferably 25% or less, more preferably 23% or less) can be achieved, and a cold resistance such that a temperature T10 measured in accordance with JIS K 6261 of less than -3°C (preferably less than -8°C, more preferably -10°C or less) can be achieved.

[0018] Examples of the unsaturated nitrile include acrylonitrile, methacrylonitrile, ethacrylonitrile, and phenylacrylonitrile. The unsaturated nitrile may be used alone or in combination of two or more. The unsaturated nitrile may contain acrylonitrile from the viewpoint of easily obtaining excellent moldability and from the viewpoint of easily obtaining excellent oil resistance, compression set, and cold resistance in the vulcanized molded product.

[0019] The content of the unsaturated nitrile-derived structural unit contained in the chloroprene polymer is more than 0% by mass and 23% by mass or less based on the total amount of the chloroprene polymer. If the content of the unsaturated nitrile-derived structural unit is 0% by mass, the oil resistance of the vulcanized molded article is not improved. If the content of the unsaturated nitrile-derived structural unit exceeds 23% by mass, the cold resistance of the vulcanized molded article is reduced.

[0020] The content of the structural unit derived from the unsaturated nitrile may be 1% by mass or more, 2% by mass or more, 3% by mass or more, 5% by mass or more, 7% by mass or more, 8% by mass or more, 9% by mass or more, 10% by mass or more, more than 10% by mass, 12% by mass or more, 15% by mass or more, 18% by mass or more, or 20% by mass or more, from the viewpoint of easily obtaining excellent oil resistance. The content of the structural unit derived from the unsaturated nitrile may be 22% by mass or less, 21% by mass or less, 20% by mass or less, less than 20% by mass, 17% by mass or less, 15% by mass or less, 12% by mass or less, 11% by mass or less, less than 11% by mass, 10% by mass or less, less than 10% by mass, 8% by mass or less, 6% by mass or less, 5% by mass or less, less than 5% by mass, 4% by mass or less, or 3% by mass or less, from the viewpoint of easily obtaining excellent cold resistance. From these viewpoints, the content of the structural unit derived from the unsaturated nitrile may be 3 to 20 mass %, 3 to 10 mass %, 5 to 17 mass %, 9 to 17 mass %, or 10 to 20 mass %.

[0021] The content of the structural unit derived from the unsaturated nitrile contained in the chloroprene polymer can be calculated from the content of the nitrogen atom in the copolymer. Specifically, the content of the nitrogen atom in 100 mg of the chloroprene polymer can be measured using an elemental analyzer (Sumigraph 220F: manufactured by Sumika Chemical Analysis Center Co., Ltd.), and the content of the structural unit derived from the unsaturated nitrile can be calculated. The measurement of the elemental analysis can be performed under the following conditions. For example, the electric furnace temperature is set to 900°C for the reactor, 600°C for the reduction furnace, 70°C for the column temperature, and 100°C for the detector temperature, and oxygen is flowed at 0.2 mL / min as the combustion gas and helium is flowed at 80 mL / min as the carrier gas. The calibration curve can be created using aspartic acid (10.52%) with a known nitrogen content as a standard substance.

[0022] The content of the structural unit derived from chloroprene may be in the following range based on the total amount of the chloroprene polymer. From the viewpoint of easily obtaining excellent cold resistance, the content of the structural unit derived from chloroprene may be 77% by mass or more, 78% by mass or more, 79% by mass or more, 80% by mass or more, more than 80% by mass, 83% by mass or more, 85% by mass or more, 88% by mass or more, 89% by mass or more, more than 89% by mass, 90% by mass or more, more than 90% by mass, 92% by mass or more, 94% by mass or more, 95% by mass or more, more than 95% by mass, 96% by mass or more, or 97% by mass or more. From the viewpoint of easily obtaining excellent oil resistance, the content of the structural unit derived from chloroprene may be less than 100 mass%, 99 mass% or less, 98 mass% or less, 97 mass% or less, 95 mass% or less, 93 mass% or less, 92 mass% or less, 91 mass% or less, 90 mass% or less, less than 90 mass%, 88 mass% or less, 85 mass% or less, 82 mass% or less, or 80 mass% or less. From these viewpoints, the content of the structural unit derived from chloroprene may be 77 mass% or more and less than 100 mass%, 80 to 97 mass%, 90 to 97 mass%, 83 to 95 mass%, 83 to 91 mass%, or 80 to 90 mass%. For example, when the chloroprene polymer is composed of a structural unit derived from chloroprene and a structural unit derived from an unsaturated nitrile, the content of the structural unit derived from chloroprene can be obtained by subtracting the content of the structural unit derived from an unsaturated nitrile from the total amount of the chloroprene polymer.

[0023] The monomer to be copolymerized with chloroprene is not limited to unsaturated nitrile. Examples of monomers copolymerizable with chloroprene include 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, styrene, isoprene, butadiene, acrylic acid, esters of acrylic acid, methacrylic acid, esters of methacrylic acid, etc. The content of structural units derived from 1-chloro-1,3-butadiene contained in the chloroprene polymer may be less than 1 mass% based on the total amount of the chloroprene polymer.

[0024] The polymer structure of the chloroprene polymer is not particularly limited, and may be a block copolymer or a statistical copolymer.

[0025] A statistical copolymer of chloroprene and an unsaturated nitrile can be produced, for example, by continuously adding chloroprene or by intermittently adding chloroprene 10 or more times after the start of the polymerization reaction. In this case, the time when the polymerization reaction starts is defined as t(0) and n is an integer of 1 or more, and the amount of chloroprene added during the time dt(n+1) between time t(n) and time t(n+1) is determined based on the total amount of polymerization conversion of chloroprene and unsaturated nitrile during the time dt(n) between time t(n-1) and time t(n), thereby making it possible to keep the ratio of unreacted chloroprene to unsaturated nitrile constant.

[0026] A statistical copolymer means a copolymer that can be described by a Bernoulli statistical model or a first-order or second-order Markov statistical model, as described in JC Randal "POLYMER SEQUENCE DETERMINATION, Carbon-13 NMR Method" Academic Press, New York, 1977, pages 71-78. When a statistical copolymer of chloroprene and an unsaturated nitrile is composed of two monomers, the ratio of chloroprene to the unsaturated nitrile at the start of polymerization in the following Mayo-Lewis formula (I) is d[M1] / d[M2], and chloroprene is M1 as defined in the following Mayo-Lewis formula (I), where r1 is in the range of 0.3 to 3000 and r2 is in the range of 10 -5 A statistical copolymer may be obtained with the .alpha.-3.0 range.

[0027]

number

[0028] The chloroprene polymer can be obtained, for example, by emulsion polymerization. The polymerization initiator used in emulsion polymerization is not particularly limited, and any known polymerization initiator generally used in emulsion polymerization of chloroprene can be used. Examples of the polymerization initiator include organic peroxides such as potassium persulfate, ammonium persulfate, sodium persulfate, hydrogen peroxide, and t-butyl hydroperoxide.

[0029] The emulsifier used in emulsion polymerization is not particularly limited, and any known emulsifier generally used in emulsion polymerization of chloroprene can be used. Examples of the emulsifier 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).

[0030] The molecular weight regulator used in emulsion polymerization is not particularly limited, and known molecular weight regulators generally used in emulsion polymerization of chloroprene can be used. Examples of molecular weight regulators include long-chain alkyl mercaptans such as n-dodecyl mercaptan, t-dodecyl mercaptan, and n-octyl mercaptan; xanthogen compounds such as diisopropyl xanthogen disulfide and diethyl xanthogen disulfide; iodoform; benzyl 1-pyrrole dithiocarbamate (also known as benzyl 1-pyrrole carbodithioate), benzyl phenyl carbodithioate, 1-benzyl-N,N-dimethyl-4-aminodithiobenzoate, and 1-benzyl-4-methylphenyl dithiocarbamate. Benzyl-1-(2-pyrrolidinone)dithiocarbamate (also known as benzyl-1-(2-pyrrolidinone)carbodithioate), benzyl phthalimidyl dithiocarbamate (also known as benzyl phthalimidyl carbodithioate), 2-cyanoprop-2-yl-1-pyrrole dithiocarbamate (also known as 2-cyanoprop-2-yl-1-pyrrole carbodithioate), dithioate), 2-cyanobut-2-yl-1-pyrrole dithiocarbamate (also known as 2-cyanobut-2-yl-1-pyrrole carbodithioate), benzyl-1-imidazole dithiocarbamate (also known as benzyl-1-imidazole carbodithioate), 2-cyanoprop-2-yl-N,N-dimethyldithiocarbamate, benzyl-N,N-diethyldithiocarbamate, cyanomethyl-1-(2-pyrrolidone)dithiocarbamate, 2-(ethoxycarbonylbenzyl)prop- 2-yl-N,N-diethyl dithiocarbamate, 1-phenylethyl dithiobenzoate, 2-phenylprop-2-yl dithiobenzoate, 1-acetate-1-yl-ethyl dithiobenzoate, 1-(4-methoxyphenyl)ethyl dithiobenzoate, benzyl dithioacetate, ethoxycarbonylmethyl dithioacetate, 2-(ethoxycarbonyl)prop-2-yl dithiobenzoate, 2-cyanoprop-2-yl dithiobenzoate, t-butyl dithiobenzoate, 2,4,4-Trimethylpent-2-yldithiobenzoate, 2-(4-chlorophenyl)-prop-2-yldithiobenzoate, 3-vinylbenzyldithiobenzoate, 4-vinylbenzyldithiobenzoate, benzyldiethoxyphosphinyldithioformate, t-butyltrithioperbenzoate, 2-phenylprop-2-yl-4-chlorodithiobenzoate, naphthalene-1-carboxylic acid-1-methyl-1-phenyl-ethyl ester, 4-cyano-4-methyl-4-thiobenzylsulfanylbutyric acid, dibenzyltetrathioterephthalate, carboxymethyldithiobenzoate, poly(ethylene oxide) with dithiobenzoate end groups, poly(ethylene oxide) with 4-cyano-4-methyl-4-thiobenzylsulfanylbutyric acid end groups, 2-[(2-phenylethanethioyl)sulfanyl]propanoic acid , 2-[(2-phenylethanethioyl)sulfanyl]succinic acid, potassium 3,5-dimethyl-1H-pyrazole-1-carbodithioate, cyanomethyl-3,5-dimethyl-1H-pyrazole-1-carbodithioate, cyanomethylmethyl-(phenyl)dithiocarbamate, benzyl-4-chlorodithiobenzoate, phenylmethyl-4-chlorodithiobenzoate, 4-nitrobenzyl-4-chlorodithiobenzoate, phenylprop-2-yl-4-chlorodithiobenzoate, 1-cyano-1-methylethyl-4-chlorodithiobenzoate, 3-chloro-2-butenyl-4-chlorodithiobenzoate, 2-chloro-2-butenyl dithiobenzoate, benzyl dithioacetate, 3-chloro-2-butenyl-1H-pyrrole-1-dithiocarboxylic acid, 2-cyanobutan-2-yl-4-chloro-3,5-Dimethyl-1H-pyrazole-1-carbodithioate, cyanomethylmethyl(phenyl)carbamodithioate, 2-cyano-2-propyldodecyltrithiocarbonate, dibenzyltrithiocarbonate, butylbenzyltrithiocarbonate, 2-[[(butylthio)thioxomethyl]thio]propionic acid, 2-[[(dodecylthio)thioxomethyl]thio]propionic acid, 2-[[(butylthio)thioxomethyl]thio]succinic acid, 2-[[(dodecylthio)thioxomethyl]thio]succinic acid, 2-[[(dodecylthio)thioxomethyl]thio] thiocarbonyl compounds such as 2-methylpropionic acid, 2,2'-[carbonothioylbis(thio)]bis[2-methylpropionic acid], 2-amino-1-methyl-2-oxoethylbutyl trithiocarbonate, benzyl-2-[(2-hydroxyethyl)amino]-1-methyl-2-oxoethyltrithiocarbonate, 3-[[[(t-butyl)thio]thioxomethyl]thio]propionic acid, cyanomethyldodecyltrithiocarbonate, diethylaminobenzyltrithiocarbonate, and dibutylaminobenzyltrithiocarbonate.

[0031] 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 (polymerization rate) of the monomer falls within the range of 40 to 95 mass%, 40 to 60 mass%, 40 to 55 mass%, 40 mass% or more and less than 55 mass%, 40 to 50 mass%, etc. The chloroprene polymer according to the present embodiment may be a chloroprene polymer obtained by polymerizing a monomer containing chloroprene and an unsaturated nitrile until the final conversion rate falls within the above-mentioned range. In order to adjust the final conversion rate, a polymerization inhibitor that stops the polymerization reaction may be added to stop the polymerization when the desired conversion rate is reached.

[0032] The polymerization inhibitor is not particularly limited, and any known polymerization inhibitor generally used in emulsion polymerization of chloroprene can be used. Examples of the polymerization inhibitor include phenothiazine (thiodiphenylamine), 4-t-butylcatechol, 2,2-methylenebis-4-methyl-6-t-butylphenol, etc.

[0033] The chloroprene polymer can be obtained, for example, by removing unreacted monomers by steam stripping, adjusting the pH of the latex, and then passing through conventional steps such as freeze coagulation, water washing, and hot air drying.

[0034] The method for producing a chloroprene polymer according to the present embodiment may include a polymerization step of obtaining a first composition by polymerizing a monomer composition containing chloroprene and an unsaturated nitrile, a monomer removal step of obtaining a second composition by removing unreacted monomers in the first composition, a pH adjustment step of obtaining a third composition by adjusting the pH of the second composition, a freeze-coagulation step of obtaining a fourth composition by subjecting the third composition to freeze-coagulation, and a drying step of obtaining a chloroprene polymer by subjecting the fourth composition to a drying treatment. The chloroprene polymer according to the present embodiment may be a chloroprene polymer obtained by such a production method.

[0035] The method for producing a chloroprene polymer according to this embodiment may not include a step of subjecting the second composition to a heat treatment between the monomer removing step and the pH adjusting step, and may not include a step of subjecting the second composition to a heat treatment at 55 to 70°C for 1 to 7 hours. The method for producing a chloroprene polymer according to this embodiment may include a water washing step of washing the fourth composition with water after the freeze-coagulation step. The method for producing a chloroprene polymer according to this embodiment may not include a step of subjecting the fourth composition to a heat treatment at 140°C or higher (e.g., 140 to 180°C) after the freeze-coagulation step, and the drying step may include a drying treatment of the fourth composition at less than 140°C (135°C or lower, 130°C or lower, etc.). The method for producing a chloroprene polymer according to this embodiment may not include a step of subjecting the chloroprene polymer to a heat treatment after the drying step, and may not include a step of subjecting the chloroprene polymer to a heat treatment at 55 to 100°C (e.g., 55 to 80°C) for 3 to 120 hours (e.g., 12 to 120 hours).

[0036] Chloroprene polymers are classified into mercaptan-modified, xanthogen-modified, sulfur-modified, dithiocarbonate-based, trithiocarbonate-based and carbamate-based types depending on the type of molecular weight regulator.

[0037] The chloroprene polymer has a peak top at 5.80 to 6.00 ppm in a 1H-NMR spectrum measured in deuterated chloroform solvent. In the 1H-NMR spectrum of the chloroprene polymer, the peak area ratio A / B of the peak area A at 5.80 to 6.00 ppm and the peak area B at 4.05 to 6.20 ppm is more than 1.1 / 100 and not more than 2.3 / 100. When the peak area ratio A / B exceeds 1.1, excellent compression set is easily obtained. When the peak area ratio A / B is not more than 2.3 / 100, excellent moldability is easily obtained.

[0038] A peak (e.g., a group of peaks) having a peak top at 5.80 to 6.00 ppm is a peak derived from vinyl hydrogen in the 1,2-isomer of the chloroprene structural unit in the chloroprene polymer. A peak (e.g., a group of peaks) having a peak top at 4.05 to 6.20 ppm is a peak derived from vinyl hydrogen in the chloroprene structural unit in the chloroprene polymer. In other words, a peak area ratio A / B of the peak area A at 5.80 to 6.00 ppm and the peak area B at 4.05 to 6.20 ppm of 0.9 / 100 to 1.1 / 100 indicates that 0.9 / 100 to 1.1 / 100 of the chloroprene structural units in the chloroprene polymer are 1,2-isomers.

[0039] From the viewpoint of easily obtaining excellent compression set, the peak area ratio A / B may be 1.2 / 100 or more, 1.3 / 100 or more, 1.5 / 100 or more, 1.8 / 100 or more, or 2.0 / 100 or more. From the viewpoint of easily obtaining excellent moldability, the peak area ratio A / B may be 2.0 / 100 or less, 1.8 / 100 or less, 1.5 / 100 or less, 1.3 / 100 or less, or 1.2 / 100 or less. From these viewpoints, the peak area ratio A / B may be more than 1.1 / 100 and 2.0 / 100 or less, 1.2 / 100 to 2.0 / 100, more than 1.2 / 100 and 2.0 / 100 or less, 1.2 / 100 to 1.5 / 100, or 1.5 / 100 to 2.0 / 100.

[0040] The peak area ratio A / B of the chloroprene polymer can be adjusted by adjusting the polymerization temperature when chloroprene and an unsaturated nitrile are copolymerized. For example, to increase the peak area ratio A / B, the polymerization temperature can be set to 50 to 100°C (e.g., 60 to 100°C) for copolymerization.

[0041] The chloroprene polymer may have a peak top at 4.13 to 4.23 ppm in a 1H-NMR spectrum measured in deuterated chloroform solvent, from the viewpoint of easily obtaining excellent moldability and easily obtaining excellent oil resistance, compression set, and cold resistance in a vulcanized molded product.

[0042] In the 1H-NMR spectrum, the peak area ratio C / B of the peak area C at 4.13 to 4.23 ppm and the peak area B at 4.05 to 6.20 ppm may be in the following range from the viewpoint of easily obtaining excellent moldability and easily obtaining excellent oil resistance, compression set, and cold resistance in the vulcanized molded product. The peak area ratio C / B may be more than 0 / 100, and may be 0.01 / 100 or more, more than 0.01 / 100, 0.02 / 100 or more, or 0.03 / 100 or more. The peak area ratio C / B may be 0.5 / 100 or less, less than 0.5 / 100, 0.4 / 100 or less, 0.3 / 100 or less, 0.2 / 100 or less, 0.1 / 100 or less, 0.05 / 100 or less, or 0.03 / 100 or less. From these viewpoints, the peak area ratio C / B may be greater than 0 / 100 and not greater than 0.5 / 100, greater than 0 / 100 and not greater than 0.2 / 100, greater than 0 / 100 and not greater than 0.05 / 100, 0.03 / 100 to 0.2 / 100, or 0.03 / 100 to 0.05 / 100.

[0043] The peak (e.g., a group of peaks) having a peak top at 4.13 to 4.23 ppm is a peak derived from a structure in which water is added to the 1,2-isomer of the chloroprene structural unit in the chloroprene polymer. In other words, the peak area ratio C / B of the peak area C at 4.13 to 4.23 ppm to the peak area B at 4.05 to 6.20 ppm represents the ratio of the structure in which water is added to the 1,2-isomer in the chloroprene structural unit in the chloroprene polymer.

[0044] Since water is added to the 1,2-isomer of the structural unit of chloroprene by heating, in order to increase the peak area ratio C / B of the chloroprene polymer, a chloroprene polymer latex obtained by copolymerizing chloroprene with an unsaturated nitrile may be heat-treated, for example, at 50 to 70° C. for 5 minutes to 10 hours. At this time, since the above-mentioned peak area ratio A / B decreases, a sufficient amount of 1,2-isomer may be introduced into the chloroprene polymer in advance.

[0045] The 1H-NMR spectrum can be measured as follows. The above-mentioned chloroprene polymer is purified with xylene and methanol, and freeze-dried to obtain a sample. The sample is then dissolved in deuterated chloroform, and the 1H-NMR spectrum can be measured. The measurement data can be corrected based on the peak of chloroform (7.24 ppm) in deuterated chloroform used as a solvent.

[0046] <Chloroprene polymer composition> The chloroprene polymer composition (chloroprene-unsaturated nitrile copolymer composition) according to this embodiment contains the chloroprene polymer according to this embodiment. The chloroprene polymer composition according to this embodiment may be a vulcanizate of the chloroprene polymer.

[0047] The content of the chloroprene polymer in the chloroprene polymer composition according to this embodiment may be in the following ranges based on the total amount of the chloroprene polymer composition. The content of the chloroprene polymer may be 10% by mass or more, 20% by mass or more, 30% by mass or more, 40% by mass or more, or 45% by mass or more. The content of the chloroprene polymer may be 90% by mass or less, 80% by mass or less, 70% by mass or less, 60% by mass or less, or 50% by mass or less. From these viewpoints, the content of the chloroprene polymer may be 10 to 90% by mass.

[0048] The chloroprene polymer composition according to the present embodiment may contain additives other than the chloroprene polymer, such as vulcanizing agents, plasticizers, antioxidants, fillers, vulcanization accelerators, vulcanization rate regulators, processing aids, softeners, and scorch inhibitors.

[0049] Examples of the vulcanizing agent include sulfur, morpholine compounds (dithiodimorpholine, etc.), and metal elements, oxides, and hydroxides of metals such as beryllium, magnesium, zinc, calcium, barium, germanium, titanium, tin, zirconium, antimony, vanadium, bismuth, molybdenum, tungsten, tellurium, selenium, iron, nickel, cobalt, and osmium. Examples of the vulcanizing agent include magnesium oxide and zinc oxide. Examples of the plasticizer include ether ester plasticizers, aromatic hydrocarbon plasticizers, and dioctyl sebacate. Examples of the antioxidant include ozone antioxidants, phenol-based antioxidants, amine-based antioxidants, acrylate-based antioxidants, imidazole-based antioxidants, carbamic acid metal salts, waxes, alkylated diphenylamines (4,4'-bis(α,α-dimethylbenzyl)diphenylamine, N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine, octylated diphenylamine, etc.). Examples of the filler include carbon black, silica, clay, talc, calcium carbonate, factice, and the like. Examples of the vulcanization accelerator include thiourea compounds (such as ethylene thiourea and trimethyl thiourea); guanidine compounds; thiuram compounds; and thiazole compounds. The vulcanization rate regulator may, for example, be tetramethylthiuram disulfide. Processing aids include stearic acid and the like.

[0050] <Molded body and vulcanized molded body> The molded article according to this embodiment is a molded article of the chloroprene polymer or the chloroprene polymer composition according to this embodiment, and can be obtained by molding the chloroprene polymer or the chloroprene polymer composition according to this embodiment into a shape according to the purpose.

[0051] The vulcanized molded article according to the present embodiment is a vulcanized molded article of the chloroprene polymer or chloroprene polymer composition according to the present embodiment. The vulcanized molded article according to the present embodiment can be obtained by molding the chloroprene polymer or chloroprene polymer composition according to the present embodiment into a shape according to the purpose and vulcanizing during or after molding, or can be obtained by molding the vulcanizate according to the present embodiment into a shape according to the purpose.

[0052] The molding method is not particularly limited. For example, when the molded article is a power transmission belt, a conveyor belt, a hose, a wiper, etc., it can be formed by press molding, injection molding, extrusion molding, etc. The vulcanized molded article is excellent in oil resistance, compression set, and cold resistance because it uses the chloroprene polymer according to this embodiment. The chloroprene rubber composition can be suitably used as a vulcanized molded article such as a power transmission belt, a conveyor belt, a hose, a wiper, a sealing material (packing, gasket, oil seal, diaphragm, etc.), a roll (rubber roll), an air spring, a vibration isolator, an adhesive, a boot, a rubber-coated cloth, a sponge, and a rubber lining by vulcanization molding.

[0053] The vulcanized molded article according to this embodiment can be used as a transmission belt, a conveyor belt, a hose, a wiper, a sealing material (packing, gasket, oil seal, diaphragm, etc.), a roll (rubber roll), an air spring, a vibration-proof material, an adhesive, a boot, a rubber-coated cloth, a sponge, a rubber lining, etc. The chloroprene polymer and the chloroprene polymer composition according to this embodiment can be used to obtain a vulcanized molded article for these applications.

[0054] The vulcanization molded article according to this embodiment can be suitably used as a roll (rubber roll). The roll includes a core and the vulcanization molded article according to this embodiment, and the vulcanization molded article covers at least a part of the surface (outer circumferential surface) of the core. The core may be a metal core, for example, an iron core. The core may be a rubber core, for example, the core of the vulcanization molded article according to this embodiment.

[0055] One aspect of the roll (rubber roll) according to the present embodiment is a roll having a vulcanized molded product of a chloroprene polymer composition, the chloroprene polymer composition containing a chloroprene polymer, the chloroprene polymer having a chloroprene-derived structural unit and an unsaturated nitrile-derived structural unit, the chloroprene polymer having a peak top at 5.80 to 6.00 ppm in a 1H-NMR spectrum measured in a deuterated chloroform solvent, a peak area ratio A / B of a peak area A at 5.80 to 6.00 ppm and a peak area B at 4.05 to 6.20 ppm in the 1H-NMR spectrum being more than 1.1 / 100 and not more than 2.3 / 100, and the content of the unsaturated nitrile-derived structural unit being more than 0 mass% and not more than 23 mass%.

[0056] The roll can be used for various purposes such as papermaking, metal manufacturing (e.g., steel manufacturing), printing, general industry, agricultural machinery (e.g., for hulling rice), food processing, etc. The roll can be used in a cleaning process for cleaning a metal plate, for example, in a cleaning process for cleaning a metal plate in a basic environment (e.g., an environment with a hydrogen ion exponent (pH) of 13 or more).

[0057] The sponge is obtained by mixing the chloroprene polymer or chloroprene polymer composition according to this embodiment with a metal oxide, a plasticizer, a filler, and the like using a roll, a Banbury mixer, an extruder, or the like, and then adding a foaming agent during vulcanization to cause foaming. A sponge is a porous material with numerous fine holes inside. The holes can be open, closed, or a mixture of open and closed. When the holes are large enough and open, the sponge has the property of absorbing liquid by replacing the air in the holes when immersed in liquid, and of easily releasing the liquid when external force is applied. When the holes are small, the sponge can be used as an excellent cushioning material, heat insulating material, etc. The chloroprene polymer or vulcanizate of the chloroprene polymer composition according to the present embodiment can be widely used as a sponge, specifically, it can be used for vibration-proofing materials, sponge seal parts, wet suits, shoes, etc. The density of the sponge is 0.10 to 0.80 g / cm 3 , 0.10~0.50g / cm3 , or 0.10 to 0.35 g / cm 3 By adjusting the density of the sponge within this range, the weight of the sponge itself can be reduced while maintaining mechanical strength such as tensile strength. The density of the sponge can be adjusted by adjusting the amount of foaming agent used when foaming the chloroprene polymer or chloroprene polymer composition, the foaming conditions, etc. The density of the sponge can be measured in accordance with JIS K 7222. The type C durometer hardness of the sponge may be 5 to 70, or 5 to 60. By adjusting the type C durometer hardness of the sponge within this range, a sponge excellent in impact absorption, processability, water absorption, breathability, sound absorption, etc. can be obtained. The type C durometer hardness of the sponge can be adjusted by adjusting the blending amount of the foaming agent when foaming the chloroprene polymer or chloroprene polymer composition, vulcanization and foaming conditions, etc. The type C durometer hardness of the sponge can be measured in accordance with JIS K 6253-3. The sponge made of the chloroprene polymer or chloroprene polymer composition according to the present embodiment has excellent heat resistance and cold resistance, and can be used in a temperature environment of −40° C. to 140° C. In addition, the sponge made of the chloroprene polymer or chloroprene polymer composition according to the present embodiment has excellent oil resistance and chemical resistance, and can be used in an environment where lubricating oils such as engine oil and refrigeration oil or fuel oil are splashed, and in an environment where resistance to acid, alkali, alcohol, etc. are required. EXAMPLES

[0058] The present invention will be described in more detail below with reference to examples. Note that the examples described below are representative examples of the present invention, and the scope of the present invention should not be construed as being narrowed by these examples.

[0059] <Production of Polymer> (Polymer 1) In a polymerization vessel having an internal volume of 3 L equipped with a heating / cooling jacket and a stirrer, 37 parts by mass of chloroprene (monomer), 37 parts by mass of acrylonitrile (monomer), 0.5 parts by mass of diethyl xanthogen disulfide, 200 parts by mass of pure water, 5.00 parts by mass of potassium rosinate (manufactured by Harima Chemicals Co., Ltd.), 0.40 parts by mass of sodium hydroxide, and 2.0 parts by mass of sodium salt of β-naphthalenesulfonic acid formalin condensate (manufactured by Kao Corporation) were added. Next, 0.1 parts by mass of potassium persulfate was added as a polymerization initiator, and emulsion polymerization was carried out under a nitrogen atmosphere at a polymerization temperature of 70°C. The portionwise addition of chloroprene was started 20 seconds after the start of polymerization, and the portionwise addition flow rate was adjusted with a solenoid 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 addition was carried out continuously. When the polymerization rate relative to the total amount of chloroprene and acrylonitrile reached 50% by mass, 0.1 parts by mass of a polymerization inhibitor, phenothiazine, was added to terminate the polymerization. After that, the unreacted monomers in the reaction solution were removed under reduced pressure to obtain a chloroprene polymer latex (chloroprene-acrylonitrile copolymer latex).

[0060] The polymerization rate of the chloroprene polymer latex was calculated from the dry mass of the chloroprene polymer latex after air drying. Specifically, it was calculated from the following formula (II). In the formula, the solid content concentration is the concentration [mass %] of the solid content obtained by heating 2 g of the sampled chloroprene polymer latex at 130°C and excluding volatile components such as the solvent (water), volatile chemicals, and raw materials. The total charge amount is the total amount of raw materials, reagents, and solvent (water) charged in the polymerization vessel from the start of polymerization to a certain time. The evaporation residue is the mass of chemicals that do not volatilize under the condition of 130°C and remain as solids together with the polymer, among the chemicals and raw materials charged from the start of polymerization to a certain time. The monomer charge amount is the sum of the amount of monomer charged in the polymerization vessel at the beginning and the amount of monomer added in portions from the start of polymerization to a certain time. The "monomer" is the total amount of chloroprene and acrylonitrile. Conversion rate [%] = [{(total charge amount [g] × solid concentration [mass%] / 100) - (evaporation residue [g])} / monomer charge amount [g]] × 100 (II)

[0061] The above-mentioned chloroprene polymer latex was adjusted to pH 7.0, and then freeze-coagulated on a metal plate cooled to -20°C to break the emulsion, yielding a sheet. The sheet was washed with water and then dried at 130°C for 15 minutes to obtain a solid chloroprene polymer (chloroprene-acrylonitrile copolymer, polymer 1).

[0062] The amount of structural units derived from acrylonitrile contained in the chloroprene polymer was calculated from the content of nitrogen atoms in the chloroprene polymer. Specifically, the content of nitrogen atoms in 100 mg of chloroprene polymer was measured using an elemental analyzer (Sumigraph 220F: manufactured by Sumika Chemical Analysis Center Co., Ltd.), and the amount of structural units derived from acrylonitrile was calculated. The measurement of elemental analysis was performed under the following conditions. The electric furnace temperature was set to 900°C for the reactor, 600°C for the reduction furnace, 70°C for the column temperature, and 100°C for the detector temperature, and oxygen was flowed at 0.2 mL / min as the combustion gas and 80 mL / min as the carrier gas for helium. The calibration curve was created using aspartic acid (10.52%) with a known nitrogen content as a standard substance. The amount of structural units derived from acrylonitrile in the chloroprene polymer was 10% by mass.

[0063] The above-mentioned chloroprene polymer was purified with xylene and methanol, and freeze-dried again to obtain a sample. The sample was dissolved in deuterated chloroform, and then 1H-NMR spectrum was measured. The measurement data was corrected based on the peak of chloroform (7.24 ppm) in deuterated chloroform used as a solvent.

[0064] As a result of the measurement, the peak area ratio A / B of the peak area A from 5.80 to 6.00 ppm and the peak area B from 4.05 to 6.20 ppm of the chloroprene polymer was 1.5 / 100, and the peak area ratio C / B of the peak area C from 4.13 to 4.23 ppm and the peak area B from 4.05 to 6.20 ppm was 0.03 / 100.

[0065] (Polymer 2) A chloroprene polymer (chloroprene-acrylonitrile copolymer, polymer 2) was obtained in the same manner as for polymer 1, except that the polymerization temperature was changed to 59°C. The amount of structural units derived from acrylonitrile in the chloroprene polymer and the 1H-NMR spectrum were measured in the same manner as for polymer 1. The amount of structural units derived from acrylonitrile was 10% by mass, the peak area ratio A / B was 1.2 / 100, and the peak area ratio C / B was 0.03 / 100.

[0066] (Polymer 3) A chloroprene polymer (chloroprene-acrylonitrile copolymer, polymer 3) was obtained in the same manner as for polymer 1, except that the polymerization temperature was changed to 100°C. The amount of structural units derived from acrylonitrile in the chloroprene polymer and the 1H-NMR spectrum were measured in the same manner as for polymer 1. The amount of structural units derived from acrylonitrile was 10 mass%, the peak area ratio A / B was 2.0 / 100, and the peak area ratio C / B was 0.03 / 100.

[0067] (Polymer 4) A chloroprene polymer (chloroprene-acrylonitrile copolymer, polymer 4) was obtained in the same manner as for polymer 1, except that the amount of chloroprene used was changed to 32.1 parts by mass and the amount of acrylonitrile used was changed to 10.7 parts by mass. The amount of structural units derived from acrylonitrile in the chloroprene polymer and the 1H-NMR spectrum were measured in the same manner as for polymer 1, and the amount of structural units derived from acrylonitrile was 3% by mass, the peak area ratio A / B was 1.5 / 100, and the peak area ratio C / B was 0.03 / 100.

[0068] (Polymer 5) A chloroprene polymer (chloroprene-acrylonitrile copolymer, polymer 5) was obtained by the same procedure as for the above-mentioned polymer 1, except that the amount of chloroprene used was changed to 13.1 parts by mass and the amount of acrylonitrile used was changed to 39.3 parts by mass. The amount of structural units derived from acrylonitrile in the chloroprene polymer and the 1H-NMR spectrum were measured by the same procedure as for the above-mentioned polymer 1. The amount of structural units derived from acrylonitrile was 20% by mass, the peak area ratio A / B was 1.5 / 100, and the peak area ratio C / B was 0.03 / 100.

[0069] (Polymer X1) A chloroprene polymer (Polymer X1) was obtained in the same manner as for Polymer 1, except that the amount of chloroprene used was changed to 100 parts by mass, the amount of acrylonitrile used was changed to 0 parts by mass, and chloroprene was not added separately. The amount of structural units derived from acrylonitrile in the chloroprene polymer obtained in the same manner as Polymer 1 was measured, and the amount of structural units derived from acrylonitrile was found to be 0% by mass, the peak area ratio A / B was 1.5 / 100, and the peak area ratio C / B was 0.03 / 100.

[0070] (Polymer X2) A chloroprene polymer (chloroprene-acrylonitrile copolymer, polymer X2) was obtained in the same manner as for the above-mentioned polymer 1, except that the amount of chloroprene used was changed to 8.1 parts by mass and the amount of acrylonitrile used was changed to 46 parts by mass. The amount of structural units derived from acrylonitrile in the chloroprene polymer and the 1H-NMR spectrum were measured in the same manner as for the above-mentioned polymer 1. As a result, the amount of structural units derived from acrylonitrile was 25% by mass, the peak area ratio A / B was 1.5 / 100, and the peak area ratio C / B was 0.02 / 100.

[0071] (Polymer X3) A chloroprene polymer (chloroprene-acrylonitrile copolymer, polymer X3) was obtained in the same manner as for the above-mentioned polymer 1, except that the polymerization temperature was changed to 20°C. The amount of structural units derived from acrylonitrile in the chloroprene polymer and the 1H-NMR spectrum were measured in the same manner as for the above-mentioned polymer 1. The amount of structural units derived from acrylonitrile was 10 mass%, the peak area ratio A / B was 0.8 / 100, and the peak area ratio C / B was 0.03 / 100.

[0072] (Polymer X4) A chloroprene polymer (chloroprene-acrylonitrile copolymer, polymer X4) was obtained in the same manner as for the above-mentioned polymer 1, except that the polymerization temperature was changed to 120°C. The amount of structural units derived from acrylonitrile in the chloroprene polymer and the 1H-NMR spectrum were measured in the same manner as for the above-mentioned polymer 1. The amount of structural units derived from acrylonitrile was 10% by mass, the peak area ratio A / B was 2.5 / 100, and the peak area ratio C / B was 0.03 / 100.

[0073] <Preparation of polymer composition> A polymer composition was obtained by kneading 100 parts by mass of the polymer having the polymer number shown in Table 1, 1 part by mass of trimethylthiourea (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., Noccela TMU), 3 parts by mass of 4,4'-bis(α,α-dimethylbenzyl)diphenylamine (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., Nocrac CD), 1 part by mass of stearic acid (manufactured by New Japan Chemical Co., Ltd., Stearic acid 50S), 1 part by mass of N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., Nocrac 6C), 50 parts by mass of carbon black FEF (manufactured by Asahi Carbon Co., Ltd., Asahi #60), 10 parts by mass of an ether ester plasticizer (manufactured by ADEKA Corporation, Adeka Cizer RS-700), 4 parts by mass of magnesium oxide (manufactured by Kyowa Chemical Industry Co., Ltd., Kyowa Mag 150), and 5 parts by mass of zinc oxide (manufactured by Sakai Chemical Industry Co., Ltd., zinc oxide type 2).

[0074] <Evaluation of moldability> The above-mentioned polymer composition was used to perform a Mooney scorch test in accordance with JIS K 6300-1 to obtain the scorch time. The evaluation results are shown in Table 1. A scorch time of more than 8 minutes was evaluated as good.

[0075] <Evaluation of vulcanized molded products> The above-mentioned polymer composition was press-vulcanized under the conditions of 160° C.×20 minutes to prepare a sheet-like vulcanized molded product having a thickness of 2 mm. The vulcanized molded product was evaluated as follows. The evaluation results are shown in Table 1.

[0076] (Oil resistance) The oil resistance of the vulcanized molded article was measured in accordance with JIS K 6258. The volume change rate (ΔV) after immersion at 100°C for 72 hours was calculated using ASTM No. 3 oil (IRM903, manufactured by Japan Sun Oil Co., Ltd.) as the oil type. A volume change rate of less than 60% was evaluated as good.

[0077] (Compression set) Using the above-mentioned vulcanized molded article, the compression set was measured under test conditions of 130° C. and 72 hours in accordance with JIS K 6262. A compression set of less than 40% was evaluated as good.

[0078] (cold resistance) Using the above-mentioned vulcanized molded product, the Gehman torsion test (T10) was measured in accordance with JIS K 6261. T10 is the temperature at which the torsional modulus becomes 10 times that at room temperature (23°C), and the lower the number, the better the cold resistance. A T10 value of less than -3°C was evaluated as good.

[0079] [Table 1]

Claims

1. A chloroprene polymer having a structural unit derived from chloroprene and a structural unit derived from an unsaturated nitrile, the chloroprene polymer has a peak top at 5.80 to 6.00 ppm and a peak top at 4.13 to 4.23 ppm in a H-NMR spectrum measured in a deuterated chloroform solvent; In the 1H-NMR spectrum, a peak area ratio A / B between a peak area A at 5.80 to 6.00 ppm and a peak area B at 4.05 to 6.20 ppm is greater than 1.1 / 100 and not greater than 2.3 / 100, and a peak area ratio C / B between a peak area C at 4.13 to 4.23 ppm and the peak area B is greater than 0.01 / 100; The content of the structural unit derived from chloroprene is 77% by mass or more and less than 100% by mass, The chloroprene polymer has a content of structural units derived from the unsaturated nitrile of more than 0 mass% and not more than 23 mass%.

2. The chloroprene polymer according to claim 1, wherein the peak area ratio A / B is greater than 1.2 / 100 and is not greater than 2.0 / 100.

3. 3. The chloroprene polymer according to claim 1, wherein the peak area ratio C / B is greater than 0.01 / 100 and not greater than 0.05 / 100.

4. A chloroprene polymer composition comprising the chloroprene polymer according to any one of claims 1 to 3.

5. A vulcanized molded article of the chloroprene polymer composition according to claim 4.

6. A roll provided with a vulcanized molded article of a chloroprene polymer composition, The chloroprene polymer composition contains a chloroprene polymer, The chloroprene polymer has a structural unit derived from chloroprene and a structural unit derived from an unsaturated nitrile, the chloroprene polymer has a peak top at 5.80 to 6.00 ppm and a peak top at 4.13 to 4.23 ppm in a H-NMR spectrum measured in a deuterated chloroform solvent; In the 1H-NMR spectrum, a peak area ratio A / B between a peak area A at 5.80 to 6.00 ppm and a peak area B at 4.05 to 6.20 ppm is greater than 1.1 / 100 and not greater than 2.3 / 100, and a peak area ratio C / B between a peak area C at 4.13 to 4.23 ppm and the peak area B is greater than 0.01 / 100; The content of the structural unit derived from chloroprene is 77% by mass or more and less than 100% by mass, The content of the structural unit derived from the unsaturated nitrile is more than 0 mass % and 23 mass % or less.

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