Chloroprene polymer latex composition and dip-molded article

Abstract

Provided is a chloroprene polymer latex composition with which a dip-molded article having excellent flexibility and excellent tensile strength at break can be obtained. According to the present invention, provided is a chloroprene polymer latex composition containing a chloroprene polymer latex (A), a metal oxide (B), a vulcanization accelerator (C), sulfur (D), and an aromatic heterocyclic compound (E), the chloroprene polymer rubber obtained by freeze-drying the chloroprene polymer latex (A) having a toluene-insoluble component of 50-95% by mass, the chloroprene polymer latex composition contains 0.3-15.0 parts by mass of the metal oxide (B), 0.02-1.50 parts by mass of the vulcanization accelerator (C), 0.01-0.75 parts by mass of the sulfur (D), and 0.1-10.0 parts by mass of the heteroaromatic compound (E) per 100 parts by mass of the solid content of the chloroprene polymer latex (A), and the content of the metal oxide (B), the vulcanization accelerator (C), the sulfur (D), and the heteroaromatic compound (E) is 100 parts by mass of the solid content of the chloroprene polymer latex (A). The vulcanization accelerator (C) contains at least one of thiuram-based, dithiocarbamate-based, thiourea-based, guanidine-based, xanthate-based, and thiazole-based vulcanization accelerators, and the heteroaromatic compound (E) is represented by chemical formula (1).

Description

[Technical field]

[0001] The present invention relates to a chloroprene polymer latex composition and a dip-molded article. [Background Technology]

[0002] Chloroprene-based polymers are known as materials for dip-molded products such as medical surgical gloves, medical examination gloves, industrial gloves, balloons, catheters, and rubber boots.

[0003] Various technologies have been proposed for chloroprene polymers used in dip-molded products. Patent Document 1 describes improving damping performance by mixing a low-molecular-weight chloroprene polymer with a number-average molecular weight of 500 to 50,000 for use in vibration-damping rubber. Patent Document 2 describes a polychloroprene latex with a pH of 7 to 14 for use in dip-molded products. The latex contains 100 parts by mass of a modified polychloroprene obtained by copolymerizing chloroprene with methacrylic acid, 90 to 150 parts by mass of water, 1 to 5 parts by mass of an emulsifier, and 0.5 to 2.5 parts by mass of potassium ions. Patent Document 3 describes a thiol-modified polychloroprene latex for use in dip-molded products. This latex is obtained by copolymerizing chloroprene with 2,3-dichloro-1,3-butadiene. In the 13C-solid-state NMR spectrum of the polychloroprene, the peak area (A) of 126.2 to 127.6 ppm, the peak area (B) of 122.0 to 126.2 ppm, and the peak area (C) of 129.9 to 130.3 ppm fall within the range represented by the following general formula (I). Patent Document 4 describes a chloroprene polymer latex for use in dip-molded products. By containing both high-molecular-weight and low-molecular-weight polymers, this latex achieves both excellent flexibility and mechanical properties in the vulcanized rubber produced by dip molding.

[0004] [Prior Art Document] [Patent Document]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 7-292165 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-114342 [Patent Document 3] International Publication No. 2019 / 009038 [Patent Document 4] Japanese Patent Application Publication No. 2019-143002 [Summary of the invention] [Problems to be Solved by the Invention]

[0006] Similar to dip-molded articles obtained using natural rubber and polyisoprene, dip-molded articles using chloroprene-based polymers tend to require flexibility and high mechanical properties. Furthermore, improved flexibility is closely related to improved wear feel and film texture. Therefore, there is a desire for chloroprene-based polymer latex compositions that can produce dip-molded articles exhibiting both excellent flexibility and tensile strength at break.

[0007] The present invention has been made in view of such circumstances, and aims to provide a chloroprene polymer latex composition capable of producing a dip-molded article having excellent flexibility and tensile strength at break, which has been difficult to achieve with conventional chloroprene polymer latex compositions.

[0008] Various embodiments of the present invention are described below. The embodiments described below can be combined with each other.

[0009] [1] A chloroprene polymer latex composition comprising a chloroprene polymer latex (A), a metal oxide (B), a vulcanization accelerator (C), sulfur (D), and an aromatic heterocyclic compound (E), wherein the toluene-insoluble content of the chloroprene polymer rubber obtained by freeze-drying the chloroprene polymer latex (A) is 50 to 95% by mass, and the chloroprene polymer latex composition contains 50 to 95% by mass of the metal oxide (B), a vulcanization accelerator (C), sulfur (D), and an aromatic heterocyclic compound (E) relative to 100 parts by mass of the solid content of the chloroprene polymer latex (A). : 0.3 to 15.0 parts by mass of the metal oxide (B), 0.02 to 1.50 parts by mass of the vulcanization accelerator (C), 0.01 to 0.75 parts by mass of the sulfur (D), and 0.1 to 10.0 parts by mass of the aromatic heterocyclic compound (E), wherein the vulcanization accelerator (C) comprises at least one of a thiuram-based, dithiocarbamate-based, thiourea-based, guanidine-based, xanthate-based, and thiazole-based vulcanization accelerator, and the aromatic heterocyclic compound (E) is represented by chemical formula (1). In the above chemical formula (1), X represents a hydrogen atom or a metal atom. Furthermore, R1 to R4 each represent a hydrogen atom, an alkyl group which may have a substituent, an ether group which may have a substituent, a nitro group, an amino group, or a carboxyl group. R1 to R4 may be the same or different. [2] The chloroprene polymer latex composition according to [1], further comprising 0.5 to 10.0 parts by mass of an antioxidant per 100 parts by mass of the solid content of the chloroprene polymer latex (A). [3] The chloroprene polymer latex composition according to [1] or [2], wherein the composition has a peak with a weight average molecular weight of 5,000 to 80,000 in the molecular weight distribution of the tetrahydrofuran-soluble component in the chloroprene polymer latex (A) measured by gel permeation chromatography. [4] The chloroprene polymer latex composition according to any one of [1] to [3], wherein the chloroprene polymer latex composition is molded by an immersion coagulation method and subjected to a heat drying treatment at 140°C for 60 minutes to obtain an immersion molded body, and the ratio RB / RA of the total peak area amount RB of abietic acid, neoabietic acid, palustric acid, levopimaric acid and their salts to the total peak area amount RA of dehydroabietic acid, pimaric acid, isopimaric acid, dihydroabietic acid and their salts, obtained by gas chromatography analysis of an extract obtained by extracting the immersion molded body with an ethanol / toluene azeotropic mixture specified in JIS K 6229, is 0.10 or more. [5] The chloroprene polymer latex composition according to any one of [1] to [4], wherein the chloroprene polymer latex composition is molded by an immersion coagulation method and then subjected to a heat drying treatment at 140°C for 60 minutes to obtain an immersion molded body, wherein the immersion molded body has a modulus at 100% elongation of 0.65 MPa or less and a tensile strength at break of 19.0 MPa or more as measured in accordance with JIS K 6251. [6] A dip-molded article comprising the chloroprene polymer latex composition according to any one of [1] to [5]. [7] The dip molded article according to [6], which is an industrial or household glove, a medical glove, a balloon, a catheter, or a boot. [Effects of the Invention]

[0010] The chloroprene polymer latex composition of the present invention can produce a dip-molded article having excellent flexibility and tensile strength at break. Furthermore, the obtained dip-molded article can be used as various materials requiring flexibility and tensile strength at break, utilizing its properties. Specifically, it can be used as industrial or household gloves, medical gloves, balloons, catheters, and boots. [Specific implementation method]

[0011] The following examples illustrate the embodiments of the present invention and describe the present invention in detail. The present invention is not limited by these descriptions. The various features of the embodiments of the present invention shown below can be combined with each other. In addition, the invention is established independently for each feature.

[0012] 1. Chloroprene polymer latex composition The chloroprene polymer latex composition of the present invention comprises a chloroprene polymer latex (A), a metal oxide (B), a vulcanization accelerator (C), sulfur (D), and an aromatic heterocyclic compound (E). The components that may be included in the chloroprene polymer latex composition of the present invention are described below.

[0013] 1.1 Chloroprene polymer latex (A) The chloroprene polymer latex (A) of the present invention contains a chloroprene polymer. The chloroprene polymer of the present invention refers to a polymer containing monomer units derived from 2-chloro-1,3-butadiene (hereinafter also referred to as chloroprene).

[0014] <Monomer Units That Can Be Contained in Chloroprene-Based Polymers> The chloroprene-based polymer according to one embodiment of the present invention may be a copolymer of chloroprene and other monomers copolymerizable with chloroprene. Examples of the other monomers include 1-chloro-1,3-butadiene, 2,3-dichloro-1,3-butadiene, isoprene, styrene, methacrylic acid, acrylonitrile, and sulfur. The other monomers may be used alone or in combination of two or more.

[0015] The chloroprene polymer according to one embodiment of the present invention preferably contains chloroprene monomer units and 2,3-dichloro-1,3-butadiene monomer units. The chloroprene polymer according to one embodiment of the present invention preferably contains 0 to 30% by mass of 2,3-dichloro-1,3-butadiene monomer units, more preferably 8 to 20% by mass, and even more preferably 10 to 17% by mass, relative to 100% by mass of the total of the chloroprene monomer units and the 2,3-dichloro-1,3-butadiene monomer units. The content of 2,3-dichloro-1,3-butadiene monomer units may be, for example, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30% by mass, and may also be within a range between any two of the values ​​exemplified herein.

[0016] The chloroprene polymer latex (A) according to one embodiment of the present invention may contain 70 to 100% by mass of chloroprene monomer units relative to 100% by mass of the chloroprene polymer contained in the chloroprene polymer latex (A). The content of the chloroprene monomer units may be, for example, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or 100% by mass, and may be within a range between any two of the values ​​exemplified herein.

[0017] The chloroprene polymer latex (A) according to one embodiment of the present invention may contain 0 to 30% by mass of other monomer units other than chloroprene monomer units and 2,3-dichloro-1,3-butadiene monomer units, based on 100% by mass of the chloroprene polymer contained in the chloroprene polymer latex (A). The content of other monomer units may be, for example, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30% by mass, or may be within a range between any two of the values ​​exemplified herein. The chloroprene polymer according to one embodiment of the present invention may also be composed of chloroprene monomer units and 2,3-dichloro-1,3-butadiene monomer units.

[0018] When the chloroprene polymer latex (A) according to one embodiment of the present invention contains two or more different chloroprene polymers, or is a mixture of two or more different chloroprene polymer latexes, the content of each monomer unit refers to the total of the monomer units in all the chloroprene polymers contained in the chloroprene polymer latex (A).

[0019] <Toluene-insoluble components> The chloroprene polymer latex (A) of the present invention has a toluene-insoluble content of 50 to 95% by mass. The chloroprene polymer latex (A) of one embodiment of the present invention more preferably has a toluene-insoluble content of 55 to 85% by mass. Examples of the toluene-insoluble content include 50, 55, 60, 65, 70, 75, 80, 85, 90, and 95% by mass, and may also be within a range between any two of these values.

[0020] The toluene-insoluble content can be determined by immersing a chloroprene polymer rubber obtained by freeze-drying a chloroprene polymer latex in toluene for 16 hours, denoting the freeze-dried chloroprene polymer rubber as Ag and the gel component (insoluble content) separated from the mixture dissolved in toluene as Bg, using the following formula. Specifically, the toluene-insoluble content can be determined by the method described in the Examples. Toluene insoluble content (gel content) = B / A x 100 (%)

[0021] The toluene-insoluble content can be controlled by adjusting the production conditions of the chloroprene polymer rubber, for example, by adjusting the polymerization formulation (such as the type and amount of the chain transfer agent, polymerization temperature, polymerization time, polymerization conversion rate, etc.) contained in the chloroprene polymer latex (A), and by adjusting the type and amount of the polymer blended.

[0022] <Weight Average Molecular Weight> The chloroprene polymer latex (A) according to one embodiment of the present invention may have a peak with a weight average molecular weight of 200,000 to 1,500,000 in the molecular weight distribution of the tetrahydrofuran-soluble component in the chloroprene polymer latex (A) measured by gel permeation chromatography. Furthermore, the chloroprene polymer latex (A) according to one embodiment of the present invention preferably has a peak with a weight average molecular weight of 5,000 to 80,000 in the molecular weight distribution of the tetrahydrofuran-soluble component in the chloroprene polymer latex (A) measured by gel permeation chromatography. In one embodiment of the present invention, the chloroprene polymer latex (A) is preferably prepared by mixing the chloroprene polymer latex (A) with a large amount of methanol, precipitating, filtering, and drying the obtained chloroprene polymer, and dissolving the obtained chloroprene polymer in tetrahydrofuran to obtain a sample. In the molecular weight distribution of the sample measured by gel permeation chromatography, a peak having a weight average molecular weight of 200,000 to 1,500,000 and / or a peak having a weight average molecular weight of 5,000 to 80,000 is detected.

[0023] In the chloroprene polymer latex (A) according to one embodiment of the present invention, it is preferred that the chloroprene polymer latex (A) be mixed with a large amount of methanol, precipitated, filtered, and dried, and the resulting chloroprene polymer be dissolved in tetrahydrofuran to obtain a sample, wherein a peak having a weight average molecular weight of 200,000 to 1,500,000 is detected in the molecular weight distribution of the sample measured by gel permeation chromatography, and preferably a peak having a weight average molecular weight of 5,000 to 80,000 is further detected. Furthermore, it is preferred that a peak having a weight average molecular weight of 300,000 to 1,500,000 is detected in the molecular weight distribution, and more preferably a peak having a weight average molecular weight of 5,000 to 50,000 is detected. Furthermore, it is preferred that a peak having a weight average molecular weight of 500,000 to 1,500,000 is detected in the molecular weight distribution, and more preferably a peak having a weight average molecular weight of 8,000 to 30,000 is detected.

[0024] The chloroprene polymer latex (A) according to one embodiment of the present invention may contain two or more polymers having different weight-average molecular weights, chloroprene polymer α, and chloroprene polymer β. The monomer units that may be contained in chloroprene polymer α and chloroprene polymer β, and their contents, are as described above for the monomer units that may be contained in chloroprene polymers. The chloroprene polymer α and chloroprene polymer β according to one embodiment of the present invention may have different weight-average molecular weights. The difference between the weight-average molecular weights of chloroprene polymer α and chloroprene polymer β according to one embodiment of the present invention is preferably 100,000 or greater, and more preferably 400,000 or greater. The difference between the weight average molecular weight of the chloroprene polymer α and the weight average molecular weight of the chloroprene polymer β described below is, for example, 100,000, 200,000, 300,000, 400,000, 500,000, 600,000, 700,000, 800,000, 900,000, 1,000,000, 1,200,000, 1,300,000, 1,400,000, or 1,500,000, and may be within a range between any two of the values ​​exemplified here.

[0025] For example, the weight average molecular weight of chloroprene polymer α may be smaller than that of chloroprene polymer β. The weight average molecular weight of chloroprene polymer α may be 5,000 to 80,000. The weight average molecular weight of chloroprene polymer α is, for example, 5,000, 6,000, 7,000, 8,000, 9,000, 10,000, 11,000, 12,000, 13,000, 14,000, 15,000, 16,000, 17,000, 18,000, 19,000, 20,000, 21,000, The value may be within a range between any two of the values ​​exemplified herein.

[0026] For example, the weight average molecular weight of chloroprene polymer β may be greater than that of chloroprene polymer α. The weight average molecular weight of chloroprene polymer β may be 200,000 to 1,500,000. Examples of the weight average molecular weight of chloroprene polymer β include 200,000, 300,000, 400,000, 500,000, 600,000, 700,000, 800,000, 900,000, 1,000,000, 1,100,000, 1,200,000, 1,300,000, 1,400,000, and 1,500,000. The weight average molecular weight of chloroprene polymer β may also be within a range between any two of the values ​​exemplified herein.

[0027] The chloroprene polymer latex (A) according to one embodiment of the present invention preferably contains 5 to 40% by mass of chloroprene polymer α, based on 100% by mass of the polymer contained in the chloroprene polymer latex (A). The content of chloroprene polymer α may be, for example, 5, 10, 15, 20, 25, 30, 35, or 40% by mass, or may be within a range between any two of the values ​​exemplified herein.

[0028] The chloroprene polymer latex (A) according to one embodiment of the present invention preferably contains 60 to 95% by mass of chloroprene polymer β, based on 100% by mass of the polymer contained in the chloroprene polymer latex (A). The content of chloroprene polymer β is, for example, 60, 65, 70, 75, 80, 85, 90, or 95% by mass, and may also be within a range between any two of the values ​​exemplified here.

[0029] The weight-average molecular weight can be determined, for example, by mixing a chloroprene polymer latex (A) with a large amount of methanol, dissolving the resulting chloroprene polymer in tetrahydrofuran after precipitation, filtration, and drying to obtain a sample, and analyzing the sample using gel permeation chromatography (GPC). GPC measurement conditions can be as described in the Examples. The weight-average molecular weight can be controlled by adjusting the production conditions, specifically, by adjusting the polymerization recipe of the chloroprene polymer (recipe such as the type and amount of chain transfer agent, polymerization temperature, polymerization time, polymerization conversion, etc.).

[0030] 1.2 Method for producing chloroprene polymer latex (A) The method for producing the chloroprene polymer latex (A) of the present invention is not particularly limited, and the chloroprene polymer latex (A) can be obtained, for example, by the following method. The method for producing a chloroprene polymer latex (A) according to the first embodiment of the present invention may include a polymerization step of polymerizing raw material monomers containing chloroprene to obtain the chloroprene polymer latex. The obtained chloroprene polymer latex may be directly used as the chloroprene polymer latex (A). The method for producing a chloroprene polymer latex (A) according to the second embodiment of the present invention may include: a polymerization step of polymerizing raw material monomers containing chloroprene to obtain a chloroprene polymer latex; and a mixing step of mixing two or more latexes to obtain the chloroprene polymer latex (A). The method for producing the chloroprene polymer latex (A) according to the third embodiment of the present invention may include: a first polymerization step of polymerizing raw material monomers containing chloroprene to obtain chloroprene-based polymer α; and a second polymerization step of polymerizing chloroprene-based polymer β in the presence of chloroprene-based polymer α; or A first polymerization step of polymerizing raw material monomers containing chloroprene to obtain a chloroprene-based polymer β; and a second polymerization step of polymerizing a chloroprene-based polymer α in the presence of the chloroprene-based polymer β.

[0031] The following describes a method for producing a chloroprene polymer latex (A) according to a first embodiment of the present invention. The method for producing a chloroprene polymer latex (A) according to one embodiment of the present invention may include a polymerization step of polymerizing raw material monomers containing chloroprene to obtain the chloroprene polymer latex.

[0032] In the polymerization step, the raw monomers include chloroprene and may also include other monomers copolymerizable with chloroprene. The other monomers copolymerizable with chloroprene are as described above. It is preferred to adjust the type and amount of each monomer so that the type and content of each monomer unit in the obtained polymer are within the above-mentioned numerical range. As an example, the copolymerization amount of 2,3-dichloro-1,3-butadiene in the chloroprene polymer contained in the chloroprene polymer latex can be in the range of 0 to 30 mass % relative to the total of 100 mass % of the chloroprene monomer and 2,3-dichloro-1,3-butadiene contained in the chloroprene polymer. In this case, the amount of 2,3-dichloro-1,3-butadiene added before the start of emulsion polymerization is preferably in the range of 0 to 30 mass % relative to the total of 100 mass parts of the chloroprene monomer and 2,3-dichloro-1,3-butadiene monomer. From the viewpoint of controlling polymerization, the amount of 2,3-dichloro-1,3-butadiene added is more preferably 5 to 25 parts by mass relative to 100 parts by mass of the total of the chloroprene monomer and the 2,3-dichloro-1,3-butadiene monomer.

[0033] Chloroprene polymers can be produced by polymerizing the starting monomers using various polymerization methods, including emulsion polymerization, solution polymerization, suspension polymerization, and bulk polymerization. Among these polymerization methods, emulsion polymerization is preferred due to its advantages, including ease of control, ease of polymer extraction from the polymerization-terminated solution, and relatively high polymerization speed.

[0034] Emulsion polymerization is a type of free radical polymerization in which the raw monomers are put into a reaction tank together with a chain transfer agent, water, an alkali (for example, a metal hydroxide such as potassium hydroxide or sodium hydroxide), an emulsifier (dispersant), a reducing agent (for example, sodium bisulfite), and a polymerization initiator to carry out polymerization.

[0035] The type of chain transfer agent used in emulsion polymerization is not particularly limited. For example, long-chain alkyl mercaptans such as n-dodecyl mercaptan and tert-dodecyl mercaptan, dialkyl xanthogen disulfides such as diisopropyl xanthogen disulfide and diethyl xanthogen disulfide, and known chain transfer agents commonly used in emulsion polymerization of chloroprene such as iodoform can be used. The chain transfer agent is preferably a long-chain alkyl mercaptan, more preferably n-dodecyl mercaptan.

[0036] By adjusting the type and amount of the chain transfer agent, the weight average molecular weight of the obtained chloroprene polymer latex can be adjusted.

[0037] For example, to obtain a chloroprene polymer latex containing chloroprene polymer β having a weight-average molecular weight of 200,000 to 1,500,000, the amount of chain transfer agent added before the start of emulsion polymerization is preferably 0.01 parts by mass or more relative to 100 parts by mass of the raw monomers (e.g., 100 parts by mass of the total of chloroprene and 2,3-dichloro-1,3-butadiene). From the perspective of obtaining a chloroprene polymer latex containing chloroprene polymer β having a weight-average molecular weight of 200,000 to 1,500,000, the amount of chain transfer agent added is more preferably 0.02 to 0.05 parts by mass, for example, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09 parts by mass, or less than 0.10 parts by mass. The amount may also be within a range between any two of the values ​​exemplified herein. When the amount of the chain transfer agent, particularly long-chain alkyl mercaptans, added is 0.01 parts by mass or more, the storage stability of the latex is further improved. When the amount added is less than 0.10 parts by mass, particularly less than 0.05 parts by mass, the toluene-insoluble component increases, and the tensile strength at break of the dip-molded article containing the obtained chloroprene polymer latex increases.

[0038] As another example, to obtain a chloroprene polymer latex containing chloroprene polymer α in which a peak with a weight-average molecular weight of 5,000 to 80,000 is detected in the molecular weight distribution, the amount of chain transfer agent added before the start of emulsion polymerization is preferably 1.0 to 10.0 parts by mass relative to 100 parts by mass of the monomers. In this case, the amount of chain transfer agent added is, for example, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, or 10.0 parts by mass, and may also be within a range between any two of the values ​​exemplified here.

[0039] In the method for producing the chloroprene polymer latex (A) according to the first embodiment of the present invention, the chloroprene polymer latex obtained in the polymerization step can be directly used as the chloroprene polymer latex (A). In this case, in the polymerization step, it is preferred to obtain a chloroprene polymer latex containing chloroprene polymer β having a weight-average molecular weight of 200,000 to 1,500,000.

[0040] The emulsifier preferably comprises rosin acid and / or a rosin salt. Examples of rosin salts include alkali metal salts such as sodium salts and potassium salts. The amount of rosin acid and a rosin salt added may be 3.0 to 7.0 parts by mass relative to 100 parts by mass of the raw material monomers used. The amount of rosin acid and a rosin salt added may be, for example, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, or 7.0 parts by mass, or may be within a range between any two of the values ​​exemplified herein. The use of rosin acids can prevent aggregation of the rubber solids and pH fluctuations when blending with the base latex.

[0041] Abietic acid and / or abietic acid salt may contain a conjugated resin acid component and a non-conjugated resin acid component. Examples of the conjugated resin acid component include abietic acid, neoabietic acid, palustric acid, levopimaric acid, and salts thereof. Examples of the non-conjugated resin acid component include dehydroabietic acid, pimaric acid, isopimaric acid, dihydropimaric acid, dihydroabietic acid, and salts thereof.

[0042] The ratio (RB / RA) of the total peak area of ​​abietic acid, neoabietic acid, palustric acid, levopimaric acid, and their salts relative to the total peak area of ​​dehydroabietic acid, pimaric acid, isopimaric acid, dihydroabietic acid, and their salts, as determined by gas chromatography analysis of the extract obtained by extraction with an ethanol / toluene azeotropic mixture as specified in JIS K 6229, of the abietic acid and abietic acid salt used in the emulsion polymerization step, can be 0.10 to 0.70. The RB / RA of the abietic acid and abietic acid salt can be, for example, 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, or 0.70, or can be within a range between any two of the values ​​exemplified herein. By adjusting the type and amount of the abietic acid and / or abietic acid salt, the RB / RA of the resulting dip-molded article of the chloroprene polymer latex composition can be adjusted.

[0043] The emulsifier may also include emulsifiers and dispersants other than rosin acid and rosin salts. Cationic, anionic, and nonionic emulsifiers and dispersants may be used as emulsifiers and dispersants other than rosin acid and rosin salts. In one embodiment of the present invention, the emulsifier used in the emulsion polymerization step may include rosin acid and / or rosin salts, as well as anionic emulsifiers and dispersants. From the perspective of stabilizing the chloroprene polymer latex when the pH adjuster is added, sulfate-based and sulfonate-based anionic emulsifiers and dispersants are preferably used in combination. Specifically, alkyl sulfonates having 8 to 20 carbon atoms, alkyl aryl sulfates, condensates of sodium β-naphthalenesulfonate and formaldehyde, and sodium alkyl diphenyl ether disulfonate may be used. The amount of the anionic emulsifier and dispersant added may be 0.05 to 5.0 parts by mass relative to 100 parts by mass of the raw monomers. The amount of the anionic emulsifier or dispersant added is, for example, 0.05, 0.1, 0.2, 0.3, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0 parts by mass relative to 100 parts by mass of the raw monomers, and may be within a range between any two of the values ​​exemplified here.

[0044] The pH of the aqueous emulsion at the start of emulsion polymerization is preferably between 10.5 and 13.5. The aqueous emulsion refers to a mixture of the chain transfer agent and monomers (such as chloroprene and 2,3-dichloro-1,3-butadiene) immediately before the start of emulsion polymerization, including cases where the composition is changed by adding the components later or in batches. A pH of 10.5 or higher at the start of emulsion polymerization allows for more stable control of the polymerization reaction. A pH of 13.5 or lower suppresses excessive viscosity increases during polymerization, allowing for more stable control of the polymerization reaction.

[0045] The polymerization temperature of the emulsion polymerization is preferably within the range of 5 to 55° C. A temperature of 5° C. or higher prevents the emulsion from freezing, while a temperature of 55° C. or lower prevents the chloroprene monomer from evaporating or boiling, which is more preferred.

[0046] As the polymerization initiator, potassium persulfate, benzoyl peroxide, ammonium persulfate, hydrogen peroxide, and the like, which are generally used in radical polymerization, can be used.

[0047] The polymerization conversion rate is preferably in the range of 50% to 95%. The polymerization reaction is terminated by adding a polymerization terminator. A polymerization conversion rate of 50% or higher tends to increase the toluene-insoluble content, resulting in a higher tensile strength at break of the resulting impregnated molded article. This also offers advantages in terms of production costs. A polymerization conversion rate of less than 95% avoids a decrease in polymerization reactivity due to a reduction in unreacted monomers, thereby preventing a decrease in productivity.

[0048] Examples of the polymerization terminator include diethylhydroxylamine, thiodiphenylamine, 4-tert-butylcatechol, 2,2'-methylenebis-4-methyl-6-tert-butylphenol, etc. After the emulsion polymerization, unreacted monomers can be removed by conventional methods such as reduced pressure distillation.

[0049] Furthermore, to the chloroprene polymer latex obtained by the production method of one embodiment of the present invention, a freeze stabilizer, an emulsion stabilizer, a viscosity modifier, an antioxidant, a preservative, etc. may be optionally added after polymerization within a range that does not impair the effects of the present invention.

[0050] For example, in the polymerization step, all the raw monomers and reagents used in the polymerization step may be added to the polymerization vessel before the start of polymerization, and then the polymerization may be started. Alternatively, at least a portion of the raw monomers and / or reagents used in the polymerization step may be added to the polymerization vessel before the start of polymerization, and the remaining portion may be added after the start of polymerization.

[0051] In the polymerization step, at least a portion of the raw monomers and reagents are added to the polymerization vessel before polymerization begins. When the remaining raw monomers and / or reagents are added after polymerization begins, the remaining raw monomers and / or reagents may be added all at once, in multiple portions, or continuously at a constant flow rate. In one embodiment of the present invention, at least a portion of the raw monomers may be added in portions after polymerization begins. For example, when chloroprene and 2,3-dichloro-1,3-butadiene are used as the raw monomers, a portion of the chloroprene may be added in portions after polymerization begins.

[0052] As an example, the portioned addition of the remaining raw material monomers and / or reagents can be initiated when the polymerization rate of the raw material monomers added before the start of polymerization reaches 50-95%. The polymerization rate at the start of the portioned addition can be, for example, 50, 55, 60, 65, 70, 75, 80, 85, 90, or 95%, or can be within a range between any two of the values ​​exemplified herein.

[0053] When at least a portion of the raw material monomers are added after the start of polymerization, up to 50 parts by mass of 100 parts by mass of all the raw material monomers used in the polymerization step may be added after the start of polymerization. In this case, the amount of raw material monomers added after the start of polymerization can be, for example, 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50 parts by mass, or can be within a range between any two of the values ​​exemplified here. For example, the portioned addition of raw material monomers, such as chloroprene, can be performed continuously over 30 to 300 minutes.

[0054] The method for producing the chloroprene polymer latex (A) according to the second embodiment of the present invention will be described below. The method for producing the chloroprene polymer latex (A) according to the second embodiment of the present invention may include a polymerization step and a mixing step.

[0055] The method for producing the chloroprene polymer latex (A) according to the second embodiment of the present invention may include a polymerization step of polymerizing raw material monomers containing chloroprene to obtain a chloroprene polymer latex. The polymerization step may include a polymerization step of polymerizing raw material monomers containing chloroprene to obtain a latex containing a chloroprene polymer α, and a polymerization step of polymerizing raw material monomers containing chloroprene to obtain a latex containing a chloroprene polymer β. In the polymerization step, the amount of the chain transfer agent is preferably adjusted according to the target weight average molecular weight. In the polymerization step of the second embodiment, the types, amounts, and polymerization conditions of each reagent can be the same as those described in the polymerization step of the first embodiment.

[0056] The method for producing a chloroprene polymer latex (A) according to the second embodiment of the present invention may include a mixing step of mixing two or more latexes to obtain the chloroprene polymer latex (A). In this mixing step, a latex containing a chloroprene polymer α having a weight-average molecular weight of 5,000 to 80,000 and a latex containing a chloroprene polymer β having a weight-average molecular weight of 200,000 to 1,500,000 may be mixed to obtain the chloroprene polymer latex (A). In the mixing step, the two or more chloroprene polymer latexes may be mixed using a known method. In the mixing step, for example, the chloroprene polymer latex (A) may be obtained by stirring and mixing using a paddle at 30 to 300 rpm for 20 seconds to 3 minutes, and, for example, at 100 rpm for 1 minute.

[0057] The following describes a method for producing a chloroprene polymer latex (A) according to a third embodiment of the present invention. The method for producing a chloroprene polymer latex (A) according to the third embodiment of the present invention may include: a first polymerization step of polymerizing raw material monomers containing chloroprene to obtain chloroprene-based polymer α; and a second polymerization step of polymerizing chloroprene-based polymer β in the presence of chloroprene-based polymer α; or A first polymerization step of polymerizing raw material monomers containing chloroprene to obtain a chloroprene-based polymer β; and a second polymerization step of polymerizing a chloroprene-based polymer α in the presence of the chloroprene-based polymer β.

[0058] In the first polymerization step, the amount of the chain transfer agent and other factors are preferably adjusted according to the target weight-average molecular weight. Furthermore, in the method for producing a chloroprene polymer latex according to the third embodiment of the present invention, a polymerization terminator may not be used in the first polymerization step. Other than that, the types, amounts, and polymerization conditions of the various reagents in the first polymerization step may be the same as those described for the polymerization step in the first embodiment.

[0059] The third embodiment of the present invention may include a second polymerization step of polymerizing the chloroprene-based polymer β in the presence of the chloroprene-based polymer α, or a second polymerization step of polymerizing the chloroprene-based polymer α in the presence of the chloroprene-based polymer β.

[0060] In the second polymerization step, the chloroprene polymer α (or chloroprene polymer β) can be added to the polymerization solution in any form. For example, the polymerization solution obtained by polymerizing the chloroprene polymer α (or chloroprene polymer β) can be used directly. As an example, when the chloroprene polymer α (or chloroprene polymer β) is polymerized by emulsion polymerization, a latex containing the chloroprene polymer α (or chloroprene polymer β) can be added to the polymerization solution of the chloroprene polymer β or the chloroprene polymer α. Alternatively, for example, the chloroprene polymer α (or chloroprene polymer β) can be precipitated from the polymerization solution obtained by polymerizing the chloroprene polymer α (or chloroprene polymer β), and the precipitated chloroprene polymer α (or chloroprene polymer β) can be added to the polymerization solution of the chloroprene polymer β (or chloroprene polymer α). For example, when chloroprene polymer α (or chloroprene polymer β) is polymerized by emulsion polymerization, chloroprene polymer α (or chloroprene polymer β) may be precipitated using methanol and then added to a polymerization solution of chloroprene polymer β (or chloroprene polymer α). Alternatively, a rubber component (chloroprene polymer α (or chloroprene polymer β)) obtained by freeze-drying a latex containing chloroprene polymer α (or chloroprene polymer β) may be added to a polymerization solution of chloroprene polymer β (or chloroprene polymer α).

[0061] When chloroprene polymer β is polymerized in the second polymerization step, the amount of chloroprene polymer α added can be 5.0 to 60.0 parts by mass based on 100 parts by mass of the chloroprene monomer (or raw material monomer). Examples of the amount of chloroprene polymer α added include 5.0, 10.0, 15.0, 20.0, 25.0, 30.0, 35.0, 40.0, 50.0, and 60.0 parts by mass, and may also be within a range between any two of these exemplified values. Furthermore, when chloroprene polymer α is polymerized in the second polymerization step, the amount of chloroprene polymer β added can be 40.0 to 95.0 parts by mass based on 100 parts by mass of the chloroprene monomer (or raw material monomer). Examples of the amount of chloroprene polymer β added include 40.0, 50.0, 60.0, 65.0, 70.0, 75.0, 80.0, 85.0, 90.0, and 95.0 parts by mass, and may also be within a range between any two of these exemplified values.

[0062] In the second polymerization step, the types and amounts of each monomer are preferably adjusted so that the content of each monomer unit in the resulting chloroprene polymer latex (A) falls within the above-described numerical ranges. Other than that, the types, amounts, and polymerization conditions of each reagent in the second polymerization step can be the same as those described for the polymerization step above.

[0063] The chloroprene polymer latex containing the chloroprene polymer α having a weight average molecular weight of 5,000 to 80,000 and / or the chloroprene polymer β having a weight average molecular weight of 200,000 to 1,500,000 obtained by the above production method can be used as the chloroprene polymer latex (A) of the present invention.

[0064] 1.3 Metal oxide (B) The chloroprene polymer latex composition of the present invention contains 0.3 to 15.0 parts by mass of a metal oxide (B) per 100 parts by mass of the solid content of the chloroprene polymer latex (A). The content of the metal oxide (B) is, for example, 0.3, 0.5, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0, or 15.0 parts by mass, or may be within a range between any two of the values ​​exemplified herein. When the content of the metal oxide (B) is greater than or equal to the lower limit, the tensile strength at break is improved due to the crosslinking effect between the polymers. When the content of the metal oxide (B) is less than or equal to the upper limit, a dip-molded article having excellent flexibility can be obtained.

[0065] The type of metal oxide (B) is not particularly limited and may be at least one of zinc oxide, lead oxide, lead tetroxide, magnesium oxide, aluminum oxide, iron oxide, beryllium oxide, and titanium oxide. The metal oxide preferably comprises zinc oxide. Zinc oxide is generally believed to function as a scavenger for dechlorinated atoms in chloroprene polymers. The metal oxide (B) may be used alone or in combination of two or more.

[0066] 1.4 Vulcanization accelerator (C) The chloroprene polymer latex composition of the present invention contains 0.02 to 1.50 parts by mass of a vulcanization accelerator (C) per 100 parts by mass of the solid content of the chloroprene polymer latex (A). The content of the vulcanization accelerator (C) is, for example, 0.02, 0.04, 0.06, 0.08, 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, 0.90, 1.00, 1.10, 1.20, 1.30, 1.40, or 1.50 parts by mass, and may also be within a range between any two of the values ​​exemplified herein. The chloroprene polymer latex composition of the present invention contains a specific amount of vulcanization accelerator (C) (a smaller amount than that of conventional chloroprene polymer latex compositions), thereby reducing the risk of allergies and costs, and providing a dip-molded article having both excellent flexibility and tensile strength at break.

[0067] The vulcanization accelerator (C) of the present invention comprises at least one of thiuram-based, dithiocarbamate-based, thiourea-based, guanidine-based, xanthate-based, and thiazole-based vulcanization accelerators. The vulcanization accelerator (C) may be used alone or in combination of two or more.

[0068] Examples of the thiourea vulcanization accelerator include compounds having a thiourea structure. Examples of the thiourea vulcanization accelerator include compounds represented by the following formula.

[0069] [Chemistry 5]

[0070] In the above formula, R 11 ~R 14 Each of the thiourea compounds may be independently hydrogen or an organic group, and may be hydrogen or a hydrocarbon group. The hydrocarbon group may be an alkyl group or an aryl group. Examples of thiourea compounds include ethylenethiourea, diethylthiourea (N,N'-diethylthiourea), trimethylthiourea, diphenylthiourea (N,N'-diphenylthiourea), and 1,3-trimethylene-2-thiourea.

[0071] Examples of the thiuram-based vulcanization accelerator include compounds containing one or more structures represented by the following formulae.

[0072] [Chemistry 6]

[0073] In the above formula, R 21 、R 22 、R 23 、R 24 Each of them can be an organic group independently, preferably a hydrocarbon group. The hydrocarbon group can be an alkyl group having 1 to 12 carbon atoms or a cycloalkyl group having 1 to 12 carbon atoms. 21 With R 22 、R 23 With R 24 They may be linked to form a cyclic structure (eg, a cycloalkyl group). n may be an integer greater than or equal to 1, and may be 1 to 4, preferably 1 or 2, and more preferably 2.

[0074] Examples of the thiuram-based vulcanization accelerator include tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide, tetrabutylthiuram disulfide, tetrakis(2-ethylhexyl)thiuram disulfide, tetramethylthiuram monosulfide, and bis(pentamethylene)thiuram tetrasulfide.

[0075] Examples of the dithiocarbamate-based vulcanization accelerator include compounds composed of ions represented by the following formula and metal ions. [Chemistry 7]

[0076] In the above formula, R 31 ~R 32 Each of them can be an organic group, or a hydrocarbon group. The hydrocarbon group can be an alkyl group, an aryl group, or an aralkyl group. 31 With R 32 They can also be linked to form a cycloalkyl group. Examples of metal ions include zinc, sodium, copper, iron, nickel, and tellurium. Examples of the dithiocarbamate-based vulcanization accelerator include sodium dibutyldithiocarbamate, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc N-ethyl-N-phenyldithiocarbamate, zinc N-pentamethylenedithiocarbamate, copper dimethyldithiocarbamate, iron (III) dimethyldithiocarbamate, and tellurium diethyldithiocarbamate.

[0077] Examples of the guanidine-based compound include compounds having a guanidine skeleton. Examples of the guanidine-based compound include 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, and di-o-tolylguanidine salt of dicatechol borate.

[0078] Examples of the xanthate-based vulcanization accelerator include compounds composed of ions represented by the following formula and metal ions.

[0079] [Chemistry 8]

[0080] In the above formula, R 41 It can be an organic group or a hydrocarbon group. The hydrocarbon group can be an alkyl group. Examples of metal ions include zinc, sodium, copper, nickel, and tellurium. Examples of xanthate-based vulcanization accelerators include butyl zinc xanthate and isopropyl zinc xanthate.

[0081] Examples of the thiazole compound include compounds having a thiazole skeleton, and more preferably a benzothiazole skeleton. Examples of the thiazole compound include 2-mercaptobenzothiazole, di-2-benzothiazole disulfide, 2-mercaptobenzothiazole zinc salt, cyclohexylamine salt of 2-mercaptobenzothiazole, 2-(4'-morpholinyldithio)benzothiazole, N-cyclohexylbenzothiazole-2-sulfenamide, N-cyclohexyl-2-benzothiazolesulfenamide, and N-oxydiethylene-2-benzothiazolesulfenamide.

[0082] 1.5 Sulfur (D) The chloroprene polymer latex composition of the present invention contains 0.01 to 0.75 parts by mass of sulfur (D) per 100 parts by mass of the solid content of the chloroprene polymer latex (A). The content of sulfur (D) is, for example, 0.01, 0.02, 0.03, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, or 0.75 parts by mass, or may be within a range between any two of the values ​​exemplified here. The chloroprene polymer latex composition of the present invention, by containing a specific amount of sulfur (D) (a smaller amount than that of conventional chloroprene polymer latex compositions), can reduce the risk of allergies and costs, and can produce a dip-molded article having both excellent flexibility and tensile strength at break.

[0083] 1.6 Aromatic heterocyclic compounds (E) The chloroprene polymer latex composition of the present invention contains 0.1 to 10.0 parts by mass of the aromatic heterocyclic compound (E) based on 100 parts by mass of the solid content of the chloroprene polymer latex (A). The aromatic heterocyclic compound (E) can be represented by the chemical formula (1) and has a benzimidazole structure. In addition, the compound having this structure is sometimes used mainly as a secondary antioxidant in the formulation of the rubber composition.

[0084] [Chemistry 1]

[0085] In chemical formula (1), X of the mercapto group represents a hydrogen atom or a metal atom. X may be a group in which X is a hydrogen atom and has a thiol group. Alternatively, X may be a metal atom, and examples of the metal atom include zinc, sodium, copper, nickel, and tellurium, with zinc being preferred.

[0086] In the chemical formula (1), R1 to R4 each represent a hydrogen atom, an alkyl group which may have a substituent, an ether group which may have a substituent, a nitro group, an amino group, or a carboxyl group. R1 to R4 may be the same or different. The aromatic heterocyclic compound (E) may be used alone or in combination of two or more.

[0087] Examples of the aromatic heterocyclic compound (E) include 2-mercaptobenzimidazole, 5-methyl-2-mercaptobenzimidazole, 4-methyl-2-mercaptobenzimidazole, 5-methoxy-2-mercaptobenzimidazole, 4-methoxy-2-mercaptobenzimidazole, 5-nitro-2-mercaptobenzimidazole, 5-amino-2-mercaptobenzimidazole, 5-carboxy-2-mercaptobenzimidazole, and zinc salts of 2-mercaptobenzimidazole. Among these, 2-mercaptobenzimidazole, 5-methyl-2-mercaptobenzimidazole, 4-methyl-2-mercaptobenzimidazole, 5-methoxy-2-mercaptobenzimidazole, 4-methoxy-2-mercaptobenzimidazole, and zinc salts of 2-mercaptobenzimidazole are preferred.

[0088] The amount of the aromatic heterocyclic compound (E) added is preferably 0.1 to 10.0 parts by mass relative to 100 parts by mass of the solid content of the chloroprene polymer latex (A) contained in the chloroprene polymer latex composition. The content of the aromatic heterocyclic compound (E) is, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, or 10.0 parts by mass, or may be within the range between any two of the values ​​exemplified herein. If the content of the aromatic heterocyclic compound (E) is above the lower limit, the dip molded article can exhibit very high tensile strength at break. If the content of the aromatic heterocyclic compound (E) is below the upper limit, the stability of the chloroprene polymer latex composition can be ensured. By having the content of the aromatic heterocyclic compound (E) within the above numerical range, the softness and tensile strength at break of the dip molded article can be greatly improved. The aromatic heterocyclic compound (E) may be used alone or in combination of two or more.

[0089] 1.7 Antioxidants The chloroprene polymer latex composition of the present invention may contain 0.5 to 10.0 parts by mass of an antioxidant per 100 parts by mass of the solid content of the chloroprene polymer latex (A). The type of antioxidant is not particularly limited, and phenolic antioxidants, amine antioxidants, heat-resistant antioxidants (aging agents), ozone-resistant antioxidants, and the like can be used (however, aromatic heterocyclic compounds (E) are excluded). When the obtained dip-molded article is used in medical gloves, phenolic antioxidants can be used from the perspectives of color tone, texture, and sanitation of the dip-molded article. Hindered phenolic antioxidants are particularly effective in achieving these effects. Examples of hindered phenolic antioxidants include 2,2'-methylenebis(4-ethyl-6-tert-butylphenol), 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 4,4'-butylenebis(3-methyl-6-tert-butylphenol), 4,4'-thiobis(3-methyl-6-tert-butylphenol), the butylation reaction product of p-cresol and dicyclopentadiene, 2,5'-di-tert-butylhydroquinone, and 2,5'-di-tert-amylhydroquinone. Among them, generally, from the viewpoint of being dispersible in aqueous materials, a butylated reaction product of p-cresol and dicyclopentadiene is preferred. The antioxidant may be used alone or in combination of two or more.

[0090] The antioxidant content is preferably 0.5 to 10.0 parts by mass per 100 parts by mass of the solid content of the chloroprene polymer latex (A) contained in the chloroprene polymer latex composition. Examples of the antioxidant content include 0.5, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, and 10.0 parts by mass, and may also be within a range between any two of the values ​​exemplified herein. When the antioxidant content is above the lower limit, changes in the color tone of the dip-molded article can be suppressed. When the antioxidant addition amount is below the upper limit, the stability of the chloroprene polymer latex composition can be ensured. Furthermore, from the perspective of the physical balance between the flexibility and tensile strength at break of the resulting dip-molded article, the antioxidant addition amount is more preferably 0.5 to 5.0 parts by mass.

[0091] 2. Physical Properties of Chloroprene Polymer Latex Composition <Toluene swelling degree> The chloroprene polymer latex composition according to one embodiment of the present invention is molded by an immersion coagulation method and then heat-dried at 140°C for 60 minutes to obtain an immersion molded article. The immersion molded article preferably has a toluene swelling degree of 12.0 or less, more preferably 10.0 or less. The toluene swelling degree is represented by formula (1). Formula (1): Toluene swelling degree = 1 + (W2 / W1-1)(P1 / P2)(1 / r) In formula (1), W1 represents the mass of the impregnated molded article before immersing it in toluene, W2 represents the mass of the impregnated molded article after immersing it in toluene, P1 represents the specific gravity of the chloroprene polymer component in the chloroprene polymer latex (A), P2 represents the specific gravity of toluene, and r represents the mass fraction of the chloroprene polymer component in the impregnated molded article. Here, the chloroprene polymer component in the chloroprene polymer latex (A) can be obtained by mixing the chloroprene polymer latex (A) with methanol to precipitate it, filtering it, and drying it. The specific gravity of the chloroprene polymer component in the chloroprene polymer latex (A) and the specific gravity of toluene can be values ​​measured at 20°C, and P2 can be 0.867. P1 can be the specific gravity of the chloroprene polymer component in the chloroprene polymer latex (A) measured at 20°C, and P1 can be 1.23.

[0092] The toluene swelling degree of the dip molded article of the chloroprene polymer latex composition is, for example, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, or 12.0, and may be within a range between any two of the values ​​exemplified here. The toluene swelling degree of a dip-molded article of a chloroprene polymer latex composition is believed to be correlated with the degree of crosslinking of the chloroprene polymer latex, and it is speculated that the higher the degree of crosslinking, the lower the swelling degree. The chloroprene polymer latex of the present invention, by setting the toluene swelling degree to 12.0 or less, can produce a dip-molded article having superior tensile strength at break and flexibility.

[0093] The toluene swelling degree can be measured by the method described in the Examples. The toluene swelling degree can be adjusted by appropriately selecting the method for producing the chloroprene polymer latex composition. For example, a chloroprene polymer latex composition having a toluene swelling degree of 12.0 or less can be obtained by a production method comprising a polymerization step of polymerizing chloroprene polymer β (or chloroprene polymer α) in the presence of chloroprene polymer α (or chloroprene polymer β), as described above.

[0094] <Ratio RB / RA of the total peak area amount RB of abietic acid, neoabietic acid, palustric acid, levopimaric acid, and their salts to the total peak area amount RA of dehydroabietic acid, pimaric acid, isopimaric acid, dihydroabietic acid, and their salts> In one embodiment of the present invention, a chloroprene polymer latex composition is molded by an immersion coagulation method and heat-dried at 140°C for 60 minutes to obtain an immersion molded article. The immersion molded article is extracted with an ethanol / toluene azeotropic mixture as specified in JIS K 6229, and the extract is subjected to gas chromatography analysis. The ratio RB / RA of the total peak area of ​​abietic acid, neoabietic acid, palustric acid, levopimaric acid, and their salts relative to the total peak area of ​​dehydroabietic acid, pimaric acid, isopimaric acid, dihydroabietic acid, and their salts is preferably 0.10 or greater, more preferably 0.10 or greater and 0.70 or less, and even more preferably 0.15 or greater and 0.50 or less. RB / RA is, for example, 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, or 0.70, and may also be within a range between any two of the values ​​exemplified herein. By setting RB / RA within the above numerical range, the tensile strength at break of the impregnated molded article can be further improved.

[0095] RB / RA can be determined by molding a chloroprene polymer latex composition by an immersion coagulation method, followed by heat drying at 140°C for 60 minutes to obtain an immersion molded article. The immersion molded article is then placed in a flask with a condenser, extracted with an ethanol / toluene azeotropic mixture as specified in JIS K 6229, treated with hydrochloric acid, and then analyzed by gas chromatography. The RB / RA ratio can also be calculated using the method described in the Examples. RB / RA can be controlled by adjusting the type and ratio of rosin acid and rosin salt added as emulsifiers during the production of the chloroprene polymer latex.

[0096] A chloroprene polymer latex composition according to one embodiment of the present invention is formed by a dip-coagulation method and then heat-dried at 140°C for 60 minutes to obtain a dip-molded article. The dip-molded article preferably has a modulus at 100% elongation of 0.65 MPa or less, more preferably 0.60 MPa, as measured in accordance with JIS K 6251. The modulus at 100% elongation is exemplified by 0.30, 0.35, 0.4, 0.45, 0.50, 0.55, 0.60, or 0.65 MPa, and may also be within a range between any two of the values ​​exemplified herein.

[0097] The chloroprene polymer latex composition according to one embodiment of the present invention is molded by a dipping coagulation method and then heat-dried at 140°C for 60 minutes to obtain a dip-molded article. The dip-molded article preferably has a tensile strength at break of 19.0 MPa or greater, more preferably 20.0 MPa or greater, as measured in accordance with JIS K 6251. Examples of the tensile strength at break include 19.0, 20.0, 21.0, 22.0, 23.0, 24.0, and 25.0 MPa, and may also be within a range between any two of the values ​​exemplified herein.

[0098] The tensile strength at break and the modulus at 100% elongation of the impregnated molded article of the chloroprene polymer latex composition can be controlled by adjusting the type and amount of the chloroprene polymer latex composition, as well as the polymerization formula and conditions, weight-average molecular weight, and toluene-insoluble content of the chloroprene polymer latex used.

[0099] 3. Method for producing chloroprene polymer latex composition The method for producing a chloroprene polymer latex composition according to one embodiment of the present invention may include a raw material mixing step of mixing raw materials including a chloroprene polymer latex (A), a metal oxide (B), a vulcanization accelerator (C), sulfur (D), an aromatic heterocyclic compound (E), and other necessary reagents. In the mixing step, an aqueous dispersion containing the metal oxide (B), the vulcanization accelerator (C), sulfur (D), the aromatic heterocyclic compound (E), and other necessary reagents may be prepared in advance, and then the chloroprene polymer latex (A) and the aqueous dispersion may be mixed. The mixing step can be performed using a known mixing device such as a ball mill.

[0100] 4. Dip-molded articles (dip-molded films and membranes) A dip-molded article according to one embodiment of the present invention is a dip-molded article of the aforementioned chloroprene polymer latex composition. The dip-molded article according to one embodiment of the present invention is obtained by dip-molding the chloroprene polymer latex composition of the present invention, either alone or in combination with another chloroprene polymer latex composition. The article exhibits a low modulus at 100% elongation, is flexible, and exhibits excellent mechanical properties such as strength and elongation. For example, the article may exhibit the aforementioned modulus at 100% elongation and / or tensile strength at break. The article can be suitably used as industrial or household gloves, medical gloves, balloons, catheters, or boots.

[0101] The thickness (e.g., minimum thickness) of the dip-molded article can be 0.01 to 0.50 mm. Examples of the thickness of the dip-molded article include 0.01, 0.05, 0.10, 0.20, 0.30, 0.40, and 0.50 mm, and may also be within a range between any two of the values ​​exemplified herein. The thickness of the dip-molded article can be adjusted by factors such as the time the mold is immersed in the polymer latex composition and the solids concentration of the chloroprene polymer latex composition. To reduce the thickness of the dip-molded article, the immersion time can be shortened or the solids concentration of the chloroprene polymer latex composition can be reduced.

[0102] 5. Method for manufacturing impregnated molded body The method for producing a dip-molded article according to one embodiment of the present invention may include a dip-molding step of dip-molding the chloroprene polymer latex composition of the present invention to obtain a dip-molded article.

[0103] As the method for the dip molding of one embodiment of the present invention, for example, dip coagulation method, simple dip method, thermosensitive dip method, electrodeposition method etc. can be enumerated.From the viewpoint of easily manufacturing and easily obtaining the dip molding body of certain thickness, dip coagulation method can be used.Specifically, the ceramic forming die coated with calcium system coagulation liquid is immersed in the dip molding body forming composition, and the dip molding body is formed and solidified with composition.Then, after removing water-soluble impurities by leaching, it is dried, and then formed into dip molding coating (rubber coating) by heating and vulcanization, and the dip molding coating is subsequently demoulded.Thus, a membranous dip molding body can be obtained.

[0104] The method for producing an impregnated molded article according to one embodiment of the present invention may include a drying step of heating and drying the impregnated molded article.

[0105] The heating and drying temperature can be appropriately set depending on the composition of the chloroprene polymer latex composition and can be 120-180°C. The heating temperature is preferably 120-150°C. Examples of the heating temperature include 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, and 220°C, and can also be within a range between any two of the values ​​exemplified here. The heating time can be appropriately set depending on the composition of the chloroprene polymer latex composition, the shape of the unvulcanized molded article, and other factors, and can be 10-300 minutes. The heating time is, for example, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, or 300 minutes, and may be within a range between any two of the values ​​exemplified here. As an example, the impregnated article according to one embodiment of the present invention may be obtained by heat drying at 140°C for 60 minutes. [Example]

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

[0107] First, the method for preparing the chloroprene polymer latex used in Examples will be described.

[0108] <Preparation of Chloroprene Polymer Latex A-1> (Polymerization Step of Chloroprene-Based Polymer α-1) In a 30-liter polymerization tank, 64 parts by mass of chloroprene (monomer), 9 parts by mass of 2,3-dichloro-1,3-butadiene, 90 parts by mass of pure water, 4.5 parts by mass of a conjugated resin acid-based rosin acid (trade name "HARTALL R-WW", manufactured by Harima Chemicals Co., Ltd.), 3.4 parts by mass of n-dodecylmercaptan, 1.6 parts by mass of potassium hydroxide, 0.5 parts by mass of a sodium salt of a β-naphthalenesulfonic acid-formalin condensate (trade name "DEMOLN", manufactured by Kao Corporation), and 0.5 parts by mass of sodium bisulfite were added. Polymerization was carried out at a polymerization temperature of 35°C under a nitrogen stream while continuously adding a 0.35% by mass aqueous solution of potassium persulfate as a polymerization initiator. When the polymerization rate of the added monomers reached 80%, 27 parts by mass of chloroprene (monomer) was continuously added over 100 minutes. When the polymerization rate of the initially charged monomers and the continuously added monomers reached 91%, the addition of the potassium persulfate aqueous solution was stopped to terminate the polymerization, thereby obtaining a polymerization solution. The polymerization solution was then subjected to reduced pressure distillation to remove unreacted monomers, and then concentrated to obtain a latex containing chloroprene polymer α-1 having a solids concentration of 60% by mass.

[0109] (Chloroprene-based polymer precipitation using methanol) The resulting latex containing chloroprene polymer α-1 was mixed with a large amount of methanol to precipitate chloroprene polymer α-1, which was then filtered and dried to obtain a chloroprene polymer. This chloroprene polymer was used to prepare chloroprene polymers β-1, β-23, and chloroprene polymer latex A-14, described below.

[0110] (Polymerization Step of Chloroprene-Based Polymer β-1) In a polymerization tank having an internal volume of 30 L, 28.3 parts by mass of the chloroprene polymer precipitated from the latex containing the chloroprene polymer α-1, 91 parts by mass of chloroprene (monomer), 9 parts by mass of 2,3-dichloro-1,3-butadiene, 110 parts by mass of pure water, 5.8 parts by mass of a conjugated resin acid-based rosin acid (trade name "HARTALL R-WW", manufactured by Harima Chemicals Co., Ltd.), 2 parts by mass of potassium hydroxide, 0.5 parts by mass of a sodium salt of a β-naphthalenesulfonic acid-formalin condensate (trade name "DEMOL N", manufactured by Kao Corporation), 0.5 parts by mass of sodium bisulfite, and 0.03 parts by mass of thiourea dioxide were added. Polymerization was carried out at a polymerization temperature of 14° C. under a nitrogen stream, while continuously adding a 0.35% by mass aqueous solution of potassium persulfate as a polymerization initiator. When the polymerization rate reached 85%, 0.1 parts by mass of diethylhydroxylamine was added as a polymerization terminator to terminate the polymerization, thereby obtaining a polymerization solution. The polymerization solution was subjected to reduced pressure distillation to remove unreacted monomers, and then concentrated to obtain chloroprene polymer latex A-1 containing chloroprene polymer β-1 and having a solids concentration of 60% by mass.

[0111] 50 ml of the chloroprene polymer latex A-1 was sampled, and the remaining chloroprene polymer latex A-1 was used to prepare a dip-molded article for evaluation.

[0112] The sampled chloroprene polymer latex was mixed with a large amount of methanol to precipitate the chloroprene polymer, which was then filtered and dried to obtain a chloroprene polymer sample. The weight-average molecular weight of the obtained chloroprene polymer latex was measured. The weight-average molecular weight of chloroprene polymer latex A-1 was measured, and a peak derived from chloroprene polymer α-1 with a weight-average molecular weight of 5,000 to 80,000 and a peak derived from chloroprene polymer β-1 with a weight-average molecular weight of 200,000 to 1,500,000 were confirmed. Furthermore, the toluene-insoluble content of the chloroprene polymer rubber obtained by freeze-drying the chloroprene polymer latex was measured. The respective measurement methods are described below.

[0113] <Preparation of Chloroprene Polymer Latex A-13> (Synthesis of Chloroprene Polymer β-13) In a 30 L polymerization tank were added 91 parts by mass of chloroprene (monomer), 9 parts by mass of 2,3-dichloro-1,3-butadiene, 110 parts by mass of pure water, 4.7 parts by mass of a conjugated resin acid-based rosin acid (trade name "HARTALL R-WW", manufactured by Harima Chemicals Co., Ltd.), 0.02 parts by mass of n-dodecylmercaptan, 1.6 parts by mass of potassium hydroxide, 0.4 parts by mass of a sodium salt of a β-naphthalenesulfonic acid-formalin condensate (trade name "DEMOL N", manufactured by Kao Corporation), and 0.4 parts by mass of sodium bisulfite. Polymerization was carried out at a polymerization temperature of 40°C under a nitrogen stream while continuously adding a 0.35% by mass aqueous solution of potassium persulfate as a polymerization initiator. When the polymerization rate of the added monomers reached 85%, 0.01 parts by mass of diethylhydroxylamine was added as a polymerization terminator to terminate the polymerization. The polymerization solution was distilled under reduced pressure to remove unreacted monomers, and then concentrated to obtain chloroprene polymer latex A-13 containing chloroprene polymer β-13 at a solids concentration of 60% by mass. The weight-average molecular weight and toluene-insoluble content were analyzed in the same manner as for chloroprene polymer latex A-1.

[0114] <Preparation of Chloroprene Polymer Latex A-14> (Synthesis of Chloroprene Polymer β-14) In a 30 L polymerization tank were added 91 parts by mass of chloroprene (monomer), 9 parts by mass of 2,3-dichloro-1,3-butadiene, 110 parts by mass of pure water, 4.7 parts by mass of a conjugated resin acid-based rosin acid (trade name "HARTALL R-WW", manufactured by Harima Chemicals Co., Ltd.), 0.02 parts by mass of n-dodecylmercaptan, 1.6 parts by mass of potassium hydroxide, 0.4 parts by mass of a sodium salt of a β-naphthalenesulfonic acid-formalin condensate (trade name "DEMOL N", manufactured by Kao Corporation), 0.4 parts by mass of sodium bisulfite, and 0.03 parts by mass of thiourea dioxide. Polymerization was carried out at a polymerization temperature of 14°C under a nitrogen stream while continuously adding a 0.35% by mass aqueous solution of potassium persulfate as a polymerization initiator. When the polymerization rate of the added monomers reached 85%, 0.01 parts by mass of diethylhydroxylamine was added as a polymerization terminator to terminate the polymerization. The polymerization liquid was distilled under reduced pressure to remove unreacted monomers, and then concentrated to obtain a latex containing the chloroprene polymer β-14 having a solid content concentration of 60% by mass.

[0115] (Preparation of Chloroprene Polymer Latex A-14) The latex containing the chloroprene polymer α-1 and the latex containing the chloroprene polymer β-14 were mixed at a solids ratio of 25:75 to obtain chloroprene polymer latex A-14. The weight-average molecular weight and toluene-insoluble content were analyzed in the same manner as for chloroprene polymer latex A-1.

[0116] <Preparation of Chloroprene Polymer Latex A-15> (Polymerization of Chloroprene-Based Polymer α-15) To a 30-liter polymerization tank were added 64 parts by mass of chloroprene (monomer), 9 parts by mass of 2,3-dichloro-1,3-butadiene, 77 parts by mass of pure water, 17.6 parts by mass of a gum rosin-based disproportionated rosin aqueous solution (trade name "RONDIS K-25," 25% solids, manufactured by Arakawa Chemical Industries, Ltd.), 3.4 parts by mass of n-dodecylmercaptan, 0.8 parts by mass of potassium hydroxide, 0.5 parts by mass of a sodium salt of a β-naphthalenesulfonic acid formalin condensate (trade name "DEMOL N," manufactured by Kao Corporation), and 0.5 parts by mass of sodium bisulfite. Polymerization was carried out at a polymerization temperature of 35°C under a nitrogen stream while continuously adding a 0.35% by mass aqueous solution of potassium persulfate as a polymerization initiator. When the polymerization rate of the added monomers reached 80%, 27 parts by mass of chloroprene (monomer) was continuously added over 100 minutes. When the polymerization rate of the initially added monomers and the continuously added monomers reached 91%, the addition of the potassium persulfate aqueous solution was stopped to terminate the polymerization, thereby obtaining a polymerization solution. The polymerization solution was subjected to reduced pressure distillation to remove unreacted monomers, and then concentrated to obtain a latex containing chloroprene polymer α-15 with a solids concentration of 60% by mass. The obtained latex containing chloroprene polymer α-15 was mixed with a large amount of methanol to precipitate the chloroprene polymer α-15, and then filtered and dried to obtain the chloroprene polymer. This latex was used to prepare chloroprene polymer β-15, which will be described later.

[0117] (Preparation of Chloroprene Polymer β-15) In a 30 L polymerization tank were added 28.3 parts by mass of a chloroprene polymer precipitated from a latex containing a chloroprene polymer α-15, 91 parts by mass of chloroprene (monomer), 9 parts by mass of 2,3-dichloro-1,3-butadiene, 100 parts by mass of pure water, 18.5 parts by mass of a gum rosin-based disproportionated rosin aqueous solution (trade name "RONDIS K-25", 25% solids, manufactured by Arakawa Chemical Industries, Ltd.), 0.8 parts by mass of potassium hydroxide, 0.5 parts by mass of a sodium salt of a β-naphthalenesulfonic acid formalin condensate (trade name "DEMOL N", manufactured by Kao Corporation), 0.5 parts by mass of sodium bisulfite, and 0.03 parts by mass of thiourea dioxide. Polymerization was carried out at a polymerization temperature of 14° C. under a nitrogen stream, while continuously adding a 0.35% by mass aqueous solution of potassium persulfate as a polymerization initiator. When the polymerization rate reached 85%, 0.1 parts by mass of diethylhydroxylamine was added as a polymerization terminator to terminate the polymerization, yielding a polymerization solution. The polymerization solution was subjected to reduced pressure distillation to remove unreacted monomers, and then concentrated to yield chloroprene polymer latex A-15 containing chloroprene polymer β-15, having a solids concentration of 60% by mass. The weight-average molecular weight and toluene-insoluble content were analyzed in the same manner as for chloroprene polymer latex A-1.

[0118] <Preparation of Chloroprene Polymer Latex A-17> (Polymerization of Chloroprene-Based Polymer α-17) In a 30-liter polymerization tank, 60 parts by mass of chloroprene (monomer), 8 parts by mass of 2,3-dichloro-1,3-butadiene, 90 parts by mass of pure water, 4.5 parts by mass of a conjugated resin acid-based rosin acid (trade name "HARTALL R-WW", manufactured by Harima Chemicals Co., Ltd.), 3 parts by mass of n-dodecylmercaptan, 1.5 parts by mass of potassium hydroxide, and 0.5 parts by mass of a sodium salt of a β-naphthalenesulfonic acid-formalin condensate (trade name "DEMOL N", manufactured by Kao Corporation) were added. Polymerization was carried out at a polymerization temperature of 40°C under a nitrogen stream while continuously adding a 0.35% by mass aqueous solution of potassium persulfate as a polymerization initiator. When the polymerization rate of the added monomers reached 65%, 32 parts by mass of chloroprene (monomer) was continuously added over 100 minutes. When the polymerization rate of the initially charged monomers and the continuously added monomers reached 88%, 0.1 parts by mass of diethylhydroxylamine was added as a polymerization terminator to terminate the polymerization, thereby obtaining a polymerization solution. The polymerization solution was then subjected to reduced pressure distillation to remove unreacted monomers, and then concentrated to obtain a latex containing chloroprene polymer α-17 having a solids concentration of 60% by mass.

[0119] (Polymerization of Chloroprene-Based Polymer β-17) In a 30 L polymerization tank, 91 parts by mass of chloroprene (monomer), 9 parts by mass of 2,3-dichloro-1,3-butadiene, 90 parts by mass of pure water, 4.5 parts by mass of a conjugated resin acid-based rosin acid (trade name "HARTALL R-WW", manufactured by Harima Chemicals Co., Ltd.), 0.02 parts by mass of n-dodecylmercaptan, 1.5 parts by mass of potassium hydroxide, and 0.5 parts by mass of a sodium salt of a β-naphthalenesulfonic acid-formalin condensate (trade name "DEMOL N", manufactured by Kao Corporation) were added. Polymerization was carried out at a polymerization temperature of 25°C under a nitrogen stream while continuously adding a 0.35% by mass aqueous solution of potassium persulfate as a polymerization initiator. When the polymerization rate of the added monomers reached 82%, 0.01 parts by mass of diethylhydroxylamine was added as a polymerization terminator to terminate the polymerization. The polymerization liquid was distilled under reduced pressure to remove unreacted monomers, and then concentrated to obtain a latex containing the chloroprene polymer β-17 having a solid content concentration of 60% by mass.

[0120] (Preparation of Chloroprene Polymer A-17) Chloroprene polymer latex A-17 was obtained by mixing a latex containing chloroprene polymer α-17 and a latex containing chloroprene polymer β-17 at a solid content ratio of 25:75. The weight average molecular weight and toluene insoluble content were analyzed in the same manner as for chloroprene polymer latex A-1.

[0121] <Preparation of Chloroprene Polymer Latex A-23> (Synthesis of Chloroprene Polymer β-23) In a polymerization tank having an internal volume of 30 L, 85 parts by mass of the chloroprene polymer precipitated from the latex containing the chloroprene polymer α-1, 9 parts by mass of chloroprene (monomer), 9 parts by mass of 2,3-dichloro-1,3-butadiene, 110 parts by mass of pure water, 8.5 parts by mass of a conjugated resin acid-based rosin acid (trade name "HARTALL R-WW", manufactured by Harima Chemicals Co., Ltd.), 3 parts by mass of potassium hydroxide, 0.7 parts by mass of a sodium salt of a β-naphthalenesulfonic acid-formalin condensate (trade name "DEMOL N", manufactured by Kao Corporation), 0.7 parts by mass of sodium bisulfite, and 0.03 parts by mass of thiourea dioxide were added. Polymerization was carried out at a polymerization temperature of 14° C. under a nitrogen stream, while continuously adding a 0.35% by mass aqueous solution of potassium persulfate as a polymerization initiator. When the polymerization rate reached 85%, 0.1 parts by mass of diethylhydroxylamine was added as a polymerization terminator to terminate the polymerization, thereby obtaining a polymerization solution. The polymerization solution was then subjected to reduced pressure distillation to remove unreacted monomers, and then concentrated to obtain chloroprene polymer latex A-23 containing chloroprene polymer β-23 at a solids concentration of 60% by mass.

[0122] <Analysis Method of Chloroprene Polymer Latex> The chloroprene polymer latex was analyzed by the following method. (Measurement of Weight Average Molecular Weight of Chloroprene Polymer Latex) The weight average molecular weight was measured by gel permeation chromatography (GPC) under the following measurement conditions by dissolving a sample of the chloroprene polymer obtained by precipitating the chloroprene polymer latex with methanol, filtering, and drying in 20 ml of tetrahydrofuran as described above. Device name: HLC-8320 (manufactured by Tosoh Corporation) Chromatographic columns: 3 TSKgel GMHHR-H connected in series Temperature: 40℃ Detection: Differential Refractive Index Solvent: tetrahydrofuran Calibration curve: Prepared using standard polystyrene (PS).

[0123] (Toluene insoluble content) The chloroprene polymer rubber obtained by freeze-drying the obtained chloroprene polymer latex was cut into 2 mm squares to obtain a test piece. After placing the test piece in a conical beaker, 80 g of toluene was used to dissolve the test piece for 16 hours. After that, after centrifugation, a 200 mesh metal mesh was used to separate the gel component (insoluble component). Then, the mass of the dried product was measured after the gel component was dried. When the freeze-dried chloroprene polymer rubber was set as Ag and the gel component (insoluble component) separated from the mixture after dissolving in toluene was set as Bg, the toluene-insoluble component in the chloroprene polymer rubber was calculated by the following formula. Toluene insoluble content (gel content) = B / A x 100 (%)

[0124] (Example 1) <Preparation of Chloroprene Polymer Latex Composition> 2 parts by mass of type 2 zinc oxide as a metal oxide (B), 0.5 parts by mass of Nocceler BZ as a vulcanization accelerator (C), 0.25 parts by mass of sulfur (D), 2 parts by mass of Nocrac PBK as an antioxidant, 1 part by mass of an aromatic heterocyclic compound (E) represented by Chemical Formula 2, and 0.1 part by mass of a sodium salt of a β-naphthalenesulfonic acid formalin condensate (trade name "DEMOL N", manufactured by Kao Corporation) were added to water and mixed at 20° C. for 16 hours using a ceramic ball mill to prepare an aqueous dispersion. Chloroprene polymer latex A-1 was mixed with the aqueous dispersion, and water was added to achieve a solids concentration of 30% by mass to prepare a chloroprene polymer latex composition. The resulting chloroprene polymer latex composition contained the reagents in the amounts listed in Table 1 relative to the solids content of the chloroprene polymer latex.

[0125] <Preparation of Immersion Molded Film> A ceramic cylinder with an outer diameter of 50 mm (manufactured by Shinko Co., Ltd.) was immersed for 1 second in a coagulation solution consisting of 62 parts by mass of water, 35 parts by mass of calcium nitrate tetrahydrate, and 3 parts by mass of calcium carbonate, then removed. After drying for 3 minutes, it was immersed for 2 minutes in the chloroprene polymer latex composition prepared according to the above procedure. The cylinder was then rinsed with running water at 45°C for 1 minute and dried at 140°C for 60 minutes to prepare a dip-molded film for evaluation (dip-molded film).

[0126] (Examples 2 to 15, Comparative Examples 1 to 8) The types of chloroprene polymer latex used are listed in Tables 1 to 3, and the aqueous dispersion was adjusted so that the amounts of each reagent were as shown in Tables 1 to 3. A chloroprene polymer latex composition and an evaluation dip-molded film (dip-molded film) were prepared in the same manner as in Example 1.

[0127] Metal oxide (B) Type 2 zinc oxide: Zinc oxide, manufactured by Sakai Chemical Industry Co., Ltd., "Type 2 zinc oxide"

[0128] Vulcanization accelerator (C) Nocceler BZ: Zinc dibutyldithiocarbamate, manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Nocceler C: N,N'-diphenylthiourea, "Nocceler C" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Nocceler TET: Tetraethylthiuram disulfide, "Nocceler TET" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Nocceler D: 1,3-diphenylguanidine, "Nocceler D" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Nocceler TP: Sodium dibutyldithiocarbamate, "Nocceler TP" manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0129] Aromatic heterocyclic compounds (E) Chemical formula 2: Aromatic heterocyclic compound represented by chemical formula (2)

[0130] [Chemistry 2]

[0131] Chemical formula 3: Aromatic heterocyclic compound represented by chemical formula (3) [Chemistry 3]

[0132] Chemical formula 4: Aromatic heterocyclic compound represented by chemical formula (4) [Chemistry 4]

[0133] antioxidants Antioxidant: Butylation product of p-cresol and dicyclopentadiene, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., Nocrac PBK

[0134] <Evaluation of Impregnation Molded Article> (film thickness) The thickness (film thickness) of the dip-molded film for evaluation was measured at three locations in the center using a test piece thickness meter (manufactured by Kobunshi Keiki Co., Ltd., trade name: ASKER SDA-12). The minimum thickness was determined as the thickness of the dip-molded film for evaluation. The results are shown in Tables 1 to 3.

[0135] (Determination of tensile properties) The evaluation dip-molded films were used to measure the modulus at 100% elongation and the tensile strength at break in accordance with JIS K 6251. The results are shown in Tables 1 to 3.

[0136] (Toluene swelling degree) The evaluation dip-molded film was cut into 10 mm x 15 mm pieces to obtain test pieces. The pre-immersion mass W1 of the obtained test piece was measured, and the test piece was then immersed in toluene at 23°C for 20 hours. After immersion, the test piece was removed from the toluene, the toluene on the film surface was wiped off, and the post-immersion mass W2 was measured. The toluene swelling degree was calculated from the measured pre-immersion mass W1 and post-immersion mass W2 using the following formula (1). The results are shown in Table 1. Formula (1): Toluene swelling degree = 1 + (W2 / W1-1)(P1 / P2)(1 / r) P1: Specific gravity of the chloroprene polymer component in the chloroprene polymer latex (A) P2: specific gravity of toluene r: Mass fraction of the chloroprene polymer component in the dip molded article Calculations were performed with P1 set to 1.23 and P2 set to 0.867. The chloroprene polymer component in the chloroprene polymer latex (A) can be obtained by mixing the chloroprene polymer latex (A) of the Examples and Comparative Examples with methanol to precipitate the chloroprene polymer component, followed by filtration and drying. The specific gravity of the chloroprene polymer component in the filtered and dried chloroprene polymer latex (A) was calculated by measuring the density of the chloroprene polymer obtained by the above method at room temperature (20°C). In addition, the toluene swelling degree of Example 1 was 9.2, and the toluene swelling degree of Example 14 was 13.8.

[0137] 3 g of the above-mentioned evaluation impregnation molded film was cut into 2 mm squares to obtain test pieces. This test piece was placed in an eggplant-shaped flask equipped with a condenser, extracted with an ethanol / toluene azeotropic mixture (ETA solution) as specified in JIS K 6229, and treated with hydrochloric acid to obtain an extract. This extract was then subjected to gas chromatography under the following conditions. The total peak area (RA) of dehydroabietic acid, pimaric acid, isopimaric acid, dihydroabietic acid, and their salts was determined from the gas chromatography results. Furthermore, the total peak area amount RB of abietic acid, neoabietic acid, palustric acid, levopimaric acid, and their salts was determined, and the ratio RB / RA ((conjugated resin acid component b) / (non-conjugated resin acid component a)) of the total peak area amount RB of abietic acid, neoabietic acid, palustric acid, levopimaric acid, and their salts to the total peak area amount RA of dehydroabietic acid, pimaric acid, isopimaric acid, dihydroabietic acid, and their salts in the evaluation dip molded film was calculated.

[0138] [Gas chromatography measurement conditions] Column used: FFAP (Film thickness 0.3μm) Detector: FID Column temperature: 200°C (hold for 90 minutes) → 250°C Heating rate: 10℃ / min Inlet temperature: 270℃ Detector temperature: 270°C Injection volume: 2 μL

[0139] [Table 1]

[0140] [Table 2]

[0141] [Table 3]

Claims

1. A chloroprene polymer latex composition comprising a chloroprene polymer latex (A), a metal oxide (B), a vulcanization accelerator (C), sulfur (D), and an aromatic heterocyclic compound (E). The toluene-insoluble content of the chloroprene polymer rubber obtained by freeze-drying the chloroprene polymer latex (A) is 50 to 95% by mass. The chloroprene polymer latex composition contains, relative to 100 parts by mass of the solid content of the chloroprene polymer latex (A): 0.3 to 15.0 parts by mass of the metal oxide (B), 0.02 to 1.50 parts by mass of the vulcanization accelerator (C), 0.01 to 0.75 parts by mass of sulfur (D), and 0.1 to 10.0 parts by mass of the aromatic heterocyclic compound (E), The vulcanization accelerator (C) comprises at least one of thiuram-based, dithiocarbamate-based, thiourea-based, guanidine-based, xanthate-based, and thiazole-based vulcanization accelerators. The aromatic heterocyclic compound (E) is represented by chemical formula (1): In the chemical formula (1), X represents a hydrogen atom or a metal atom, and R1 to R4 each represent a hydrogen atom, an alkyl group which may have a substituent, an ether group which may have a substituent, a nitro group, an amino group, or a carboxyl group, and R1 to R4 may be the same or different.

2. The chloroprene polymer latex composition according to claim 1, wherein The antioxidant is contained in an amount of 0.5 to 10.0 parts by mass based on 100 parts by mass of the solid content of the chloroprene polymer latex (A).

3. The chloroprene polymer latex composition according to claim 1 or 2, wherein The molecular weight distribution of the tetrahydrofuran-soluble component in the chloroprene polymer latex (A) measured by gel permeation chromatography has a peak having a weight average molecular weight of 5,000 to 80,000.

4. The chloroprene polymer latex composition according to claim 1 or 2, wherein The chloroprene polymer latex composition is molded by an immersion coagulation method and heat-dried at 140° C. for 60 minutes to obtain an immersion molded article. The immersion molded article is extracted with an ethanol / toluene azeotropic mixture specified in JIS K 6229, and the extract is subjected to gas chromatography analysis, wherein the ratio RB / RA of the total peak area amount RB of abietic acid, neoabietic acid, palustric acid, levopimaric acid, and salts thereof to the total peak area amount RA of dehydroabietic acid, pimaric acid, isopimaric acid, dihydroabietic acid, and salts thereof is 0.10 or more.

5. The chloroprene polymer latex composition according to claim 1 or 2, wherein The chloroprene polymer latex composition is molded by an immersion coagulation method and heat-dried at 140° C. for 60 minutes to obtain a dip-molded body having a modulus of 0.65 MPa or less at 100% elongation and a tensile strength at break of 19.0 MPa or more as measured in accordance with JIS K6251. A dip-molded article comprising the chloroprene polymer latex composition according to claim 1 or 2.

7. The dip molded article according to claim 6, which is industrial or household gloves, medical gloves, balloons, catheters or boots.

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