Chloroprene-based block copolymer latex composition, composition for forming dip-molded body, dip-molded body, and coating composition

Abstract

Provided is a chloroprene-based block copolymer latex composition which has high mechanical stability and which forms fewer aggregates when shear force is applied. In addition, when a composition for a specific purpose is prepared using the chloroprene-based block copolymer latex composition according to the present invention, a composition (for example, a composition for forming a dip-molded body or a coating composition) which has excellent mechanical stability and which forms fewer aggregates when shear force is applied can be obtained. The present invention provides a chloroprene-based block copolymer latex composition comprising a chloroprene-based block copolymer that includes a polymer block (A) and a chloroprene-based polymer block (B), wherein: the polymer block (A) includes a monomer unit derived from a monomer (A); the monomer (A) is a monomer from which a polymer having a glass transition temperature of 80°C or higher is obtained through homopolymerization; and the total content of aromatic compounds having 7-10 carbon atoms in the chloroprene-based block copolymer latex composition is 0.020-0.240 parts by mass with respect to 100 parts by mass of the solid content in the chloroprene-based block copolymer latex composition.

Description

Chloroprene-based block copolymer latex composition, composition for forming dip-molded body, dip-molded body, and coating composition

[0001] The present invention relates to a chloroprene block copolymer latex composition, a composition for forming a dip-molded article, a dip-molded article, and a coating composition.

[0002] Compositions containing chloroprene polymers are used in various fields, such as dip-molded articles (dip products), fiber treatment agents, paper processing agents, pressure-sensitive adhesives, adhesives, elastic asphalt (modified asphalt), and elastic cement.

[0003] For example, various techniques relating to dip-molded articles containing chloroprene polymers have been proposed. Patent Document 1 describes a polychloroprene latex with a pH of 7 to 14, which contains 100 parts by mass of modified polychloroprene obtained by copolymerizing chloroprene and 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, in relation to dip-molded article product applications.

[0004] JP 2014-114342 A

[0005] However, conventional compositions containing chloroprene polymers have low mechanical stability and may generate aggregates when shear force is applied. The present invention has been made in view of these circumstances and provides a chloroprene block copolymer latex composition that has high mechanical stability and generates little aggregates when shear force is applied. Furthermore, when a composition for a specific purpose is prepared using the chloroprene block copolymer latex composition of the present invention, a composition that has excellent mechanical stability and generates little aggregates when shear force is applied (e.g., a composition for forming a dip-molded body or a coating composition) can be obtained.

[0006] According to the present invention, there is provided a chloroprene-based block copolymer latex composition comprising a chloroprene-based block copolymer comprising a polymer block (A) and a chloroprene-based polymer block (B), wherein the polymer block (A) comprises monomer units derived from a monomer (A), and the monomer (A) is a monomer that, upon homopolymerization, gives a polymer having a glass transition temperature of 80°C or higher, and the chloroprene-based block copolymer latex composition has a total content of aromatic compounds having 7 to 10 carbon atoms of 0.020 to 0.240 parts by mass per 100 parts by mass of the solids content in the chloroprene-based block copolymer latex composition.

[0007] As a result of intensive investigations, the present inventors have found that, in a chloroprene-based block copolymer latex composition containing a chloroprene-based block copolymer, the mechanical stability can be improved by making the chloroprene-based block copolymer have a specific polymer block (A) and a chloroprene-based polymer block (B) and by adjusting the content of the aromatic compound having 7 to 10 carbon atoms in the chloroprene-based block copolymer latex composition to an extremely high level, which has led to the completion of the present invention.

[0008] Various embodiments of the present invention are exemplified below. The embodiments shown below can be combined with each other. [1] A chloroprene-based block copolymer latex composition containing a chloroprene-based block copolymer including a polymer block (A) and a chloroprene-based polymer block (B), wherein the polymer block (A) contains monomer units derived from a monomer (A), which is a monomer that, upon homopolymerization, gives a polymer having a glass transition temperature of 80°C or higher, and the chloroprene-based block copolymer latex composition contains 0.020 to 0.240 parts by mass of aromatic compounds having 7 to 10 carbon atoms per 100 parts by mass of solids in the chloroprene-based block copolymer latex composition. [2] The chloroprene-based block copolymer latex composition according to [1], wherein the aromatic compound having 7 to 10 carbon atoms includes at least one selected from the group consisting of toluene, ethylbenzene, cumene, xylene, diethylbenzene, propyltoluene, styrene, and divinylbenzene. [3] The chloroprene-based block copolymer latex composition according to [1] or [2], containing 7.0 to 15.0% by mass of the polymer block (A) relative to 100% by mass of the chloroprene-based block copolymer. [4] The chloroprene-based block copolymer latex composition according to any one of [1] to [3], wherein the polymer block (A) has a number-average molecular weight of 14,000 to 30,000. [5] The chloroprene-based block copolymer latex composition according to any one of [1] to [4], wherein the polymer block (A) contains a monomer unit derived from the aromatic compound having 7 to 10 carbon atoms. [6] A composition for forming a dip-molded body, comprising the chloroprene-based block copolymer latex composition according to any one of [1] to [5]. [7] A dip-molded body of the composition for forming a dip-molded body according to [6]. [8] A coating composition, comprising the chloroprene-based block copolymer latex composition according to any one of [1] to [5].

[0009] The chloroprene-based block copolymer latex composition according to the present invention has high mechanical stability, generates little aggregates when shear force is applied, and exhibits excellent uniform dispersion of the chloroprene-based block copolymer and excellent storage stability. The chloroprene-based block copolymer latex composition according to the present invention makes it possible to prepare compositions for various applications that exhibit excellent uniform dispersion and storage stability of the chloroprene-based block copolymer. For example, the chloroprene-based block copolymer latex composition according to the present invention can be used as a composition for forming a dip-molded body or a coating composition.

[0010] The present invention will be described in detail below by illustrating embodiments of the present invention. The present invention is not limited by these descriptions. The features of the embodiments of the present invention described below can be combined with each other. Furthermore, each feature can be an invention independently.

[0011] 1. Chloroprene-Based Block Copolymer Latex Composition The chloroprene-based block copolymer latex composition according to the present invention comprises a chloroprene-based block copolymer including a polymer block (A) and a chloroprene-based polymer block (B), wherein the polymer block (A) contains monomer units derived from a monomer (A), and the monomer (A) is a monomer that, upon homopolymerization, gives a polymer having a glass transition temperature of 80° C. or higher. The chloroprene-based block copolymer latex composition has a total content of aromatic compounds having 7 to 10 carbon atoms of 0.020 to 0.240 parts by mass per 100 parts by mass of the solids content in the chloroprene-based block copolymer latex composition.

[0012] 1.1 Chloroprene-Based Block Copolymer 1.1.1 Polymer Block (A) The polymer block (A) contains monomer units derived from the monomer (A). That is, in the present invention, the monomer (A) is included in the raw material monomers of the polymer block (A). The monomer (A) is a monomer that, upon homopolymerization, gives a polymer having a glass transition temperature of 80°C or higher. By using such a monomer to form a polymer block, the tensile strength at break of the resulting molded article is improved. The monomer (A) is preferably a monomer that, upon homopolymerization, gives a polymer having a glass transition temperature of 85°C or higher. From the viewpoint of moldability, the monomer (A) is preferably a monomer that, upon homopolymerization, gives a polymer having a glass transition temperature of 150°C or lower, and more preferably a monomer that gives a polymer having a glass transition temperature of 120°C or lower. The glass transition temperature of the polymer obtained by homopolymerization of the monomer (A) is, for example, 80, 85, 90, 95, 100, 105, 110, 120, 130, 140, or 150°C, and may be within a range between any two of the values ​​exemplified here.

[0013] In this specification, the glass transition temperature refers to the extrapolated glass transition end temperature (Teg) measured in accordance with JIS K 7121. For example, the glass transition temperature can be measured using a differential scanning calorimeter (DSC1 (manufactured by Mettler Toledo)), and specifically, the glass transition temperature can be measured by the method described in the examples.

[0014] The monomer (A) is preferably a monomer that, when homopolymerized to form a homopolymer (A) having a weight-average molecular weight of 10,000 to 100,000, the homopolymer has the above-mentioned glass transition temperature, and more preferably a monomer that, when homopolymerized to form a homopolymer (A) having a weight-average molecular weight of 14,000 to 30,000, the homopolymer has the above-mentioned glass transition temperature.

[0015] Examples of the monomer unit derived from the monomer (A) include an aromatic vinyl monomer unit and a methyl methacrylate monomer unit. The polymer block (A) preferably contains an aromatic vinyl monomer unit, and more preferably contains a styrene monomer unit.

[0016] The polymer block (A) according to one embodiment of the present invention preferably contains a monomer unit derived from an aromatic compound having 7 to 10 carbon atoms. When the chloroprene block copolymer latex composition contains multiple types of aromatic compounds having 7 to 10 carbon atoms, the polymer block (A) according to one embodiment of the present invention can contain any multiple types of aromatic compounds having 7 to 10 carbon atoms among the multiple types of aromatic compounds having 7 to 10 carbon atoms. In one embodiment of the present invention, the polymerization step of the polymer block (A) is highly precisely controlled, and the amount of the remaining raw material monomer during polymerization of the polymer block (A) can be adjusted, thereby adjusting the total content of aromatic compounds having 7 to 10 carbon atoms in the finally obtained chloroprene block copolymer latex composition.

[0017] The polymer block (A) may contain one or more monomer units derived from the monomer (A). Furthermore, the polymer block (A) may contain monomer units other than the monomer units derived from the monomer (A) as long as the object of the present invention is not impaired. The polymer block (A) may contain 70% by mass or more of the monomer units derived from the monomer (A) when the polymer block (A) is taken as 100% by mass. The content of the monomer units derived from the monomer (A) may be, for example, 70, 75, 80, 85, 90, 95, or 100% by mass, or may be within a range between any two of the values ​​exemplified here. The polymer block (A) may also be composed of monomer units derived from the monomer (A).

[0018] From the viewpoint of the mechanical properties and moldability of the resulting chloroprene-based block copolymer, the number-average molecular weight of the polymer block (A) can be 10,000 or more, preferably 14,000 or more, and more preferably 14,000 to 30,000. The number-average molecular weight of the polymer block (A) is, for example, 10,000, 14,000, 15,000, 20,000, 25,000, 30,000, 35,000, 40,000, 45,000, 50,000, 55,000, 60,000, 65,000, 70,000, 75,000, 80,000, 85,000, 90,000, 95,000, or 100,000, and may be within a range between any two of the numerical values ​​exemplified here.

[0019] From the viewpoint of moldability of the resulting chloroprene-based block copolymer, the molecular weight distribution of the polymer block (A) is preferably 2.00 or less. The molecular weight distribution of the polymer block (A) is, for example, 1.10, 1.20, 1.30, 1.40, 1.50, 1.60, 1.70, 1.80, 1.90, or 2.00, and may be within a range between any two of the values ​​exemplified here. The number average molecular weight and molecular weight distribution of the polymer block (A) can be polystyrene-equivalent values ​​measured by gel permeation chromatography (GPC), and can be measured by the method described in the examples.

[0020] The glass transition temperature of the polymer block (A) is, for example, 80, 85, 90, 95, 100, 105, 110, 120, 130, 140, or 150° C., and may be within a range between any two of the values ​​exemplified here. The glass transition temperature can be measured using a differential scanning calorimeter (DSC1 (manufactured by Mettler Toledo)), and specifically, it can be measured by the method described in the examples.

[0021] 1.1.2 Chloroprene-Based Polymer Block (B) The chloroprene-based polymer block (B) according to the present invention contains chloroprene monomer units derived from a chloroprene monomer (2-chloro-1,3-butadiene). Furthermore, the chloroprene-based polymer block (B) may have a structure derived from a monomer other than the chloroprene monomer, as long as the object of the present invention is not impaired.

[0022] The chloroprene polymer block (B) according to one embodiment of the present invention may contain 70% by mass or more of chloroprene monomer units, based on 100% by mass of the chloroprene polymer block (B). The content of the chloroprene monomer units may be, for example, 70, 75, 80, 85, 90, 95, or 100% by mass, or may be within a range between any two of the values ​​exemplified here.

[0023] The chloroprene polymer block (B) according to one embodiment of the present invention may contain 30% by mass or less of other monomer units than chloroprene monomer units, based on 100% by mass of the chloroprene polymer block (B). The content of other monomer units than chloroprene monomer units is, for example, 0, 0.05, 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, or 30% by mass, and may be within a range between any two of the values ​​exemplified here.

[0024] Examples of monomer units other than chloroprene monomer units include unsaturated nitriles such as 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, styrene, isoprene, butadiene, acrylonitrile, and methacrylonitrile, as well as monomer units derived from polyfunctional monomers. The polyfunctional monomer can be a compound having two or more radically polymerizable groups in the molecule. The polyfunctional monomer can have multiple polymerizable substituents that are independent of each other. The polyfunctional monomer can have at least one pair of non-conjugated polymerizable substituents, and among the multiple polymerizable substituents, at least one pair of polymerizable substituents can be separated from each other by at least one atom, three atoms, or five atoms. The polymerizable substituent can be a vinyl group or a carbon-carbon double bond. From the viewpoints of flexibility, tensile strength at break, and moldability of the resulting chloroprene-based block copolymer, the polyfunctional monomer unit according to one embodiment of the present invention is preferably a monomer unit represented by chemical formula (1) or an aromatic polyene monomer unit.

[0025]

[0026] In chemical formula (1), R １ and R ２ each independently represents hydrogen, chlorine, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted mercapto group, or a substituted or unsubstituted heterocyclyl group. １represents a saturated or unsaturated hydrocarbon group, a saturated or unsaturated cyclic hydrocarbon group, a saturated or unsaturated hydrocarbon group containing a hetero atom, or a saturated or unsaturated cyclic hydrocarbon group containing a hetero atom. １ is oxygen, sulfur or -NR ０ represents a structure represented by R ０ represents any one of hydrogen, chlorine, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted mercapto group, and a substituted or unsubstituted heterocyclyl group.

[0027] Examples of the monomer represented by chemical formula (1) include 1,9-nonanediol dimethacrylate, 1,9-nonanediol diacrylate, neopentyl glycol dimethacrylate, neopentyl glycol diacrylate, 1,6-hexanediol dimethacrylate, 1,6-hexanediol diacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, polyethylene glycol dimethacrylate, polyethylene glycol diacrylate, and N,N'-diacryloyl-4,7,10-trioxa-1,13-tridecanediamine. Examples of the aromatic polyene monomer include aromatic polyenes having 10 to 30 carbon atoms and having multiple double bonds (vinyl groups) and one or more aromatic groups. Examples of the aromatic polyene monomer include o-divinylbenzene, p-divinylbenzene, m-divinylbenzene, 1,4-divinylnaphthalene, 3,4-divinylnaphthalene, 2,6-divinylnaphthalene, 1,2-divinyl-3,4-dimethylbenzene, and 1,3-divinyl-4,5,8-tributylnaphthalene, and preferably use one or a mixture of two or more of o-divinylbenzene, para-divinylbenzene, and meta-divinylbenzene. When the chloroprene polymer block (B) according to one embodiment of the present invention contains a monomer unit derived from a polyfunctional monomer, the monomer unit derived from the polyfunctional monomer may contain a monomer unit derived from an aromatic compound having 7 to 10 carbon atoms. Furthermore, when the chloroprene polymer block (B) according to one embodiment of the present invention contains a monomer unit derived from a polyfunctional monomer, the monomer unit derived from the polyfunctional monomer may contain an aromatic polyene monomer unit, and the aromatic polyene monomer may contain a monomer unit derived from an aromatic compound having 7 to 10 carbon atoms. When the chloroprene block copolymer latex composition contains a plurality of aromatic compounds having 7 to 10 carbon atoms, the polyfunctional monomer unit according to one embodiment of the present invention may contain any of a plurality of aromatic compounds having 7 to 10 carbon atoms from among the plurality of aromatic compounds having 7 to 10 carbon atoms.In one embodiment of the present invention, the polymerization process of the chloroprene block copolymer is highly precisely controlled, and the amount of the raw material monomer remaining during polymerization of the chloroprene polymer block (B) is adjusted, thereby making it possible to adjust the total content of the aromatic compounds having 7 to 10 carbon atoms in the finally obtained chloroprene block copolymer latex composition.

[0028] Furthermore, the polyfunctional monomer may not contain 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, styrene, acrylonitrile, methacrylonitrile, isoprene, or butadiene. Furthermore, the chloroprene-based polymer block (B) according to one embodiment of the present invention may not contain 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, styrene, acrylonitrile, methacrylonitrile, isoprene, or butadiene. The chloroprene-based polymer block (B) according to one embodiment of the present invention may not contain a monomer unit derived from a polyfunctional monomer.

[0029] 1.1.3 Content of Each Component in Chloroprene-Based Block Copolymer The chloroprene-based block copolymer according to one embodiment of the present invention preferably contains 7.0 to 15.0 mass% of polymer block (A) relative to 100 mass% of the chloroprene-based block copolymer. The content of polymer block (A) is, for example, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0, or 15.0 mass%, and may be within a range between any two of the values ​​exemplified here. When the content of polymer block (A) is equal to or greater than the above-mentioned lower limit, the tensile strength at break of the resulting dip-molded article containing the chloroprene-based block copolymer is further improved. When the content of polymer block (A) is equal to or less than the above-mentioned upper limit, the elongation at break of the resulting dip-molded article containing the chloroprene-based block copolymer is further improved.

[0030] The chloroprene-based block copolymer according to one embodiment of the present invention preferably contains 85 to 97% by mass of the chloroprene-based polymer block (B) relative to 100% by mass of the chloroprene-based block copolymer, and may contain, for example, 85, 90, 95, 96, or 97% by mass, or may be within a range between any two of the numerical values ​​exemplified herein. The chloroprene-based block copolymer according to one embodiment of the present invention preferably contains 70 to 100% by mass of the polymer block (A) and the chloroprene-based polymer block (B) in total, relative to 100% by mass of the chloroprene-based block copolymer, and may be, for example, 70, 75, 80, 85, 90, 95, or 100% by mass, or may be within a range between any two of the numerical values ​​exemplified herein.

[0031] The chloroprene-based block copolymer according to one embodiment of the present invention may be composed of a polymer block (A) and a chloroprene-based polymer block (B), and may not contain any other polymer blocks. The chloroprene-based block copolymer may be a diblock copolymer of the polymer block (A) and the chloroprene-based polymer block (B).

[0032] In addition, the chloroprene-based block copolymer according to one embodiment of the present invention may have a functional group having a structure represented by chemical formula (1) or chemical formula (2).

[0033]

[0034] In chemical formula (2), R ３ represents any one of hydrogen, chlorine, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted mercapto group, and a substituted or unsubstituted heterocyclyl group.

[0035]

[0036] The functional group having the structure represented by chemical formula (2) or chemical formula (3) can be introduced by carrying out the polymerization step of the chloroprene-based block copolymer, for example, polymerization step 1 and / or polymerization step 2 described below, in the presence of a RAFT agent. Compounds that can be used to introduce the functional group having the structure represented by chemical formula (2) or chemical formula (3) will be described later in the section on production method.

[0037] There are no particular restrictions on the weight average molecular weight of the chloroprene block copolymer, but from the viewpoint of moldability, it is preferably 50,000 to 600,000, and particularly preferably 100,000 to 500,000.

[0038] 1.1.4 Aromatic Compound Having 7 to 10 Carbon Atoms The chloroprene block copolymer latex composition according to the present invention contains an aromatic compound having 7 to 10 carbon atoms. Examples of the aromatic compound having 7 to 10 carbon atoms include toluene, o-xylene, m-xylene, p-xylene, styrene, ethylbenzene, 2-ethyltoluene, 3-ethyltoluene, 4-ethyltoluene, cumene, 2-propyltoluene, 3-propyltoluene, 4-propyltoluene, 1,2-diethylbenzene, 1,3-diethylbenzene, 1,4-diethylbenzene, o-divinylbenzene, p-divinylbenzene, and m-divinylbenzene. The aromatic compound having 7 to 10 carbon atoms may include an aromatic compound in which one or more hydrogen atoms of the above-mentioned aromatic compounds have been substituted with a hydroxyl group, amino group, nitro group, carbonyl group, carboxyl group, isocyanato group, or the like. The aromatic compound having 7 to 10 carbon atoms may also include aromatic compounds in which one or more hydrogen atoms of the above-mentioned aromatic compounds have been substituted with a halogen (chlorine atom, bromine atom, iodine atom, fluorine atom). The aromatic compound having 7 to 10 carbon atoms may also include aromatic compounds substituted with a substituent containing a carbon atom, such as salicylic acid and acetophenone, which have 6 carbon atoms before substitution. The aromatic compound having 7 to 10 carbon atoms according to one embodiment of the present invention may include at least one selected from the group consisting of toluene, ethylbenzene, cumene, xylene, diethylbenzene, propyltoluene, styrene, divinylbenzene, and aromatic compounds in which one of the hydrogen atoms has been substituted, and may include at least one selected from the group consisting of toluene, ethylbenzene, cumene, xylene, diethylbenzene, propyltoluene, styrene, and divinylbenzene. The aromatic compound having 7 to 10 carbon atoms according to one embodiment of the present invention may include at least one of the group consisting of toluene, ethylbenzene, xylene, styrene, divinylbenzene, and aromatic compounds in which one of the hydrogen atoms of these aromatic compounds is substituted, and may include at least one of the group consisting of toluene, ethylbenzene, xylene, styrene, and divinylbenzene.The aromatic compound having 7 to 10 carbon atoms according to one embodiment of the present invention may include at least one of the group consisting of toluene, xylene, styrene, ethylbenzene, and aromatic compounds in which one of the hydrogen atoms of these aromatic compounds is substituted, and may include at least one of the group consisting of toluene, xylene, styrene, and ethylbenzene.

[0039] The aromatic compound having 7 to 10 carbon atoms according to one embodiment of the present invention may have, for example, 7, 8, 9, or 10 carbon atoms, or may be within a range between any two of the numerical values ​​exemplified herein. The aromatic compound having 7 to 10 carbon atoms according to one embodiment of the present invention may have a molecular weight of 80 to 135. The aromatic compound having 7 to 10 carbon atoms according to one embodiment of the present invention may have, for example, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, or 135 carbon atoms, or may be within a range between any two of the numerical values ​​exemplified herein.

[0040] In the chloroprene block copolymer latex composition according to the present invention, the total content of the aromatic compounds having 7 to 10 carbon atoms is 0.020 to 0.240 parts by mass relative to 100 parts by mass of the solid content in the chloroprene block copolymer latex composition. The total content of the aromatic compounds having 7 to 10 carbon atoms relative to 100 parts by mass of the solid content in the chloroprene-based block copolymer latex composition is, for example, 0.020, 0.030, 0.040, 0.050, 0.060, 0.070, 0.080, 0.090, 0.100, 0.110, 0.120, 0.130, 0.140, 0.150, 0.160, 0.170, 0.180, 0.190, 0.200, 0.210, 0.220, 0.230, or 0.240 parts by mass, and may be within a range between any two of the numerical values ​​exemplified here.

[0041] The chloroprene block copolymer latex composition according to the present invention has a highly controlled total content of aromatic compounds having 7 to 10 carbon atoms per 100 parts by mass of solids in the chloroprene block copolymer latex composition, which is presumably why the dispersibility of the chloroprene block copolymer in the chloroprene block copolymer latex composition is improved and the composition has excellent mechanical stability. Furthermore, when a composition for a specific purpose is prepared using the chloroprene block copolymer latex composition according to the present invention (e.g., a composition for forming a dip-molded product or a coating composition), the resulting composition (e.g., a composition for forming a dip-molded product or a coating composition) contains a chloroprene block copolymer latex composition having a highly controlled total content of aromatic compounds having 7 to 10 carbon atoms, resulting in a composition in which the chloroprene block copolymer and various chemicals contained in the composition (e.g., a chemical agent that exhibits crosslinking function, a lipophilic chemical agent, etc.) are uniformly dispersed, thereby improving the mechanical stability of the composition for forming a dip-molded product, etc. For example, a composition for forming an immersion-molded body containing the chloroprene-based block copolymer latex composition of the present invention has excellent storage stability because the components are uniformly dispersed in the composition and have excellent mechanical stability, and an immersion-molded body produced from the composition for forming an immersion-molded body has improved mechanical properties such as tensile strength at break and elongation at break, and has a moderate stress at 500% elongation.Furthermore, a coating composition for forming a coating film containing the chloroprene-based block copolymer latex composition of the present invention has excellent storage stability because the components are uniformly dispersed in the composition and have excellent mechanical stability, and can form a coating film (molded body) having excellent tensile strength at break and elongation at break, and a moderate stress at 500% elongation.

[0042] The content of aromatic compounds having 7 to 10 carbon atoms per 100 parts by mass of solids in the chloroprene-based block copolymer latex composition can be analyzed by gas chromatography, and specifically, can be calculated by the method described in the Examples. The total content of aromatic compounds having 7 to 10 carbon atoms per 100 parts by mass of solids in the chloroprene-based block copolymer latex composition can be adjusted by adding an aromatic compound having 7 to 10 carbon atoms to the chloroprene-based block copolymer latex. Furthermore, when raw materials used in the polymerization of the chloroprene-based block copolymer latex contain aromatic compounds having 7 to 10 carbon atoms, or when there is a possibility that aromatic compounds having 7 to 10 carbon atoms are generated as by-products during the production of the chloroprene-based block copolymer, the content of aromatic compounds having 7 to 10 carbon atoms can be controlled by adjusting the polymerization conditions of the chloroprene-based block copolymer (for example, adjusting the amount and timing of initiator addition) and the production conditions of the chloroprene-based block copolymer latex composition, such as the production conditions of the chloroprene-based polymer, including the latex concentration conditions and dilution conditions.

[0043] In the chloroprene-based block copolymer latex composition according to one embodiment of the present invention, the total content of 4-chlorovinylbenzene, 2-methylbenzyl chloride, and 3-methylbenzyl chloride is preferably 0.00100 parts by mass or less relative to 100 parts by mass of the solid content in the chloroprene-based block copolymer latex composition. The total content of 4-chlorovinylbenzene, 2-methylbenzyl chloride, and 3-methylbenzyl chloride relative to 100 parts by mass of the solid content in the chloroprene-based block copolymer latex composition is, for example, 0, 0.00010, 0.00020, 0.00030, 0.00040, 0.00050, 0.00060, 0.00070, 0.00080, 0.00090, or 0.00100 parts by mass, and may be within a range between any two of the values ​​exemplified here. In the chloroprene block copolymer latex composition according to one embodiment of the present invention, the total content of compounds in which one or more hydrogen atoms bonded to an aromatic ring are substituted with a chlorine atom or a substituent containing a chlorine atom can be within the above-mentioned numerical range, and the total content of compounds in which one or more hydrogen atoms bonded to an aromatic ring are substituted with a halogen or a substituent containing a halogen can be within the above-mentioned numerical range, relative to 100 parts by mass of the solid content of the chloroprene block copolymer latex composition.

[0044] The chloroprene-based block copolymer latex composition according to one embodiment of the present invention may be free of 4-chlorovinylbenzene, 2-methylbenzyl chloride, 3-methylbenzyl chloride, and 4-methylbenzyl chloride, and may be free of compounds in which one or more hydrogen atoms bonded to an aromatic ring are substituted with chlorine atoms, and compounds substituted with a substituent containing a chlorine atom. Furthermore, the chloroprene-based block copolymer latex composition according to one embodiment of the present invention may be free of compounds in which one or more hydrogen atoms bonded to an aromatic ring are substituted with halogen, and compounds substituted with a substituent containing a halogen. For example, the content of these compounds containing chlorine or the like can be controlled by appropriately controlling the polymerization conditions for the chloroprene-based block copolymer to suppress the production of by-products.

[0045] The chloroprene-based block copolymer latex composition according to one embodiment of the present invention preferably has a solids concentration of 50% by mass and exhibits an aggregate generation rate (mechanical stability) of 2.0% by mass or less when subjected to a shear force of 10 minutes at a load of 10 kg and a rotation speed of 1,000 rpm. The aggregate generation rate of the chloroprene-based block copolymer latex composition is, for example, 0, 0.50, 1.00, 1.50, or 2.00% by mass, and may be within a range between any two of the values ​​exemplified here. When the aggregate generation rate of the chloroprene-based block copolymer latex composition is within the above range, the mechanical stability of various compositions containing the chloroprene-based block copolymer latex composition is further improved. For example, the mechanical properties such as tensile strength at break and elongation at break of a dip-molded body produced from the composition for forming a dip-molded body are further improved, and the dip-molded body has an appropriate stress at 500% elongation.

[0046] The aggregate formation rate can be expressed by the following formula, and specifically, can be determined by the method described in the Examples. Aggregate formation rate (mechanical stability) (mass %)=Dry mass of aggregates [g] / Solids mass of chloroprene-based block copolymer latex composition [g]×100 The aggregate formation rate of the chloroprene-based block copolymer latex composition can be controlled, for example, by adjusting the polymerization conditions of the chloroprene-based block copolymer latex, the presence or absence of addition of an aromatic compound having 7 to 10 carbon atoms and the amount of the aromatic compound to the chloroprene-based block copolymer latex, and thereby adjusting the total content of the aromatic compound having 7 to 10 carbon atoms.

[0047] In a chloroprene-based block copolymer latex composition according to one embodiment of the present invention, when a test composition for forming an immersion molded body is prepared containing 2 parts by mass of a butylation reaction product of p-cresol and dicyclopentadiene and 0.1 parts by mass of a sodium salt of a β-naphthalenesulfonic acid formalin condensate per 100 parts by mass of the solids content of the chloroprene-based block copolymer latex composition, the test composition for forming an immersion molded body preferably exhibits an aggregate generation rate (mechanical stability) of 2.0% by mass or less when a shear force of a 10 kg load and a rotation speed of 1,000 rpm is applied for 10 minutes. The aggregate generation rate of the test composition for forming an immersion molded body may be, for example, 0, 0.50, 1.00, 1.50, or 2.00% by mass, and may be within a range between any two of the values ​​exemplified herein. When the aggregate generation rate of the composition for forming an immersion molded body is within the above numerical range, the uniformity, dispersibility, and stability of the composition for forming an immersion molded body itself are increased, and the immersion molded body produced from the composition for forming an immersion molded body has improved mechanical properties such as tensile strength at break and elongation at break, and has an appropriate stress at 500% elongation.

[0048] The aggregate formation rate can be evaluated by the method for measuring the mechanical stability of the composition for forming a dip-molded body described in the Examples. The aggregate formation rate of the composition for forming a dip-molded body can be controlled, for example, by adjusting the production conditions of the chloroprene-based block copolymer latex, the presence or absence and amount of an aromatic compound having 7 to 10 carbon atoms added to the chloroprene-based block copolymer latex, adjusting the total content of the aromatic compound having 7 to 10 carbon atoms, and thereby adjusting the aggregate formation rate of the chloroprene-based block copolymer latex composition.

[0049] In the chloroprene block copolymer latex composition according to one embodiment of the present invention, a dip-molded body obtained by dip-molding the composition for forming a test dip-molded body having the above-described formulation by a dip coagulation method and then heat-drying the body for 30 minutes at 130° C. preferably has a tensile strength at break of 17.5 MPa or more. Specific examples of the tensile strength at break of the dip-molded body include 17.5, 18.0, 19.0, 20.0, 21.0, 22.0, 23.0, 24.0, 25.0, 26.0, 27.0, 28.0, 29.0, and 30.0 MPa, and may be within a range between any two of the values ​​exemplified here.

[0050] In the chloroprene block copolymer latex composition according to one embodiment of the present invention, the dip-molded body obtained by dip-molding the composition for forming a test dip-molded body having the above-described formulation by a dip coagulation method and then heat-drying the resulting body for 30 minutes at 130° C. preferably has an elongation at break of 800% or more. The elongation at break of the dip-molded body may be, for example, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, or 1700%, or may be within a range between any two of the values ​​exemplified here.

[0051] In the chloroprene block copolymer latex composition according to one embodiment of the present invention, a dip-molded body obtained by dip-molding a test dip-molded body composition having the above-described formulation by a dip coagulation method and then heat-drying the body at 130°C for 30 minutes preferably has a stress at 500% elongation of 4.0 MPa or less. The tensile strength at break of the dip-molded body is, for example, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, or 4.0 MPa, and may be within a range between any two of the values ​​exemplified here. The tensile strength at break, elongation at break, and stress at 500% elongation can be measured according to JIS K 6251, and specifically, can be evaluated by the method described in the examples.

[0052] The chloroprene-based block copolymer latex composition according to one embodiment of the present invention has excellent uniform dispersibility of the chloroprene-based block copolymer and excellent mechanical stability, and therefore, when a composition for a specific purpose, such as a composition for forming an immersion molded body or a coating composition, is prepared, a composition can be obtained in which the chloroprene-based block copolymer and various chemicals contained in each composition (e.g., a crosslinking chemical, a lipophilic chemical, etc.) are uniformly dispersed. The immersion molded body and coating film (molded body) produced from the composition for forming an immersion molded body and the coating composition containing the chloroprene-based block copolymer latex composition according to one embodiment of the present invention have excellent tensile strength at break, elongation at break, and moderate stress at 500% elongation and moderate stress at 500% elongation. Therefore, by taking advantage of these properties, they can be used as various parts requiring excellent tensile strength at break, elongation at break, and / or moderate stress at 500% elongation. For example, the coating composition according to one embodiment of the present invention can be used, in particular, as an automotive coating or a mid-coat coating, to form a coating film (molded product) having excellent tensile strength at break, elongation at break, and / or a moderate stress at 500% elongation. Incidentally, as an example, the mid-coat coating can be an intermediate coating that can be applied on top of a base coating, and a base coating or a top coating can be applied on top of that.

[0053] 2. Method for Producing Chloroprene-Based Block Copolymer Latex Composition The method for producing the chloroprene-based block copolymer latex composition of the present invention is not particularly limited, and the composition can be obtained, for example, by the following production method. The method for producing the chloroprene-based block copolymer latex composition of the present invention can include a polymerization step 1 in which raw material monomers containing monomer (A) are polymerized to obtain polymer block (A), and a polymerization step 2 in which raw material monomers containing chloroprene are polymerized to obtain a chloroprene-based block copolymer latex containing a chloroprene-based block copolymer containing a chloroprene-based polymer block (B), and the composition can be produced by a production method including a two-stage polymerization step.

[0054] The polymerization mode is not particularly limited, and the composition can be produced by known methods such as solution polymerization, emulsion polymerization, and bulk polymerization, with emulsion polymerization being preferred. In each polymerization step, raw material monomers can be emulsion-polymerized using an emulsifier, dispersant, polymerization initiator, RAFT agent, reducing agent, and the like, as appropriate. In addition, in polymerization step 2, a polymerization terminator can be added when a target conversion is reached to obtain a chloroprene-based block copolymer latex. After the polymerization step, unreacted monomers may be removed by a concentration method such as vacuum distillation. In addition, the method for producing a chloroprene-based block copolymer latex composition according to one embodiment of the present invention may include a step of adding an aromatic compound having 7 to 10 carbon atoms to a chloroprene-based block copolymer latex containing a chloroprene-based block copolymer.

[0055] <Polymerization Step 1> In polymerization step 1, raw material monomers including monomer (A) are polymerized to obtain polymer block (A). In one embodiment of the present invention, polymer block (A) can be synthesized by living radical polymerization of raw material monomers including monomer (A). The raw material monomers are preferably blended so that the composition of polymer block (A) is as described above, and the type and blending amount of monomer (A) in polymer block (A) are as described above. The glass transition temperature of the polymer block (A) obtained here is, for example, 80, 85, 90, 95, 100, 105, 110, 120, 130, 140, or 150°C, and may be within a range between any two of the values ​​exemplified here.

[0056] (Emulsifier) ​​The emulsifier used in the polymerization is not particularly limited, but anionic and / or nonionic emulsifiers are preferred from the viewpoint of emulsion stability. In particular, rosin acid and / or alkali metal rosinate salts are preferred because they can provide the resulting chloroprene-based block copolymer with appropriate strength and prevent excessive shrinkage and breakage. The concentration of the emulsifier can be 5 to 50 parts by mass per 100 parts by mass of the raw material monomers from the viewpoint of efficient polymerization reaction.

[0057] The emulsifier may also include emulsifiers and dispersants other than rosin acid and alkali metal rosinate. In one embodiment of the present invention, the emulsifier used in the emulsion polymerization process may include rosin acid and / or alkali metal rosinate, and an anionic emulsifier or dispersant. As the anionic emulsifier or dispersant, it is preferable to use a sulfate- or sulfonate-based anionic emulsifier or dispersant in combination, from the viewpoint of stabilizing the chloroprene-based block copolymer latex when a pH adjuster is added. Specific examples include alkyl sulfonates having 8 to 20 carbon atoms, alkyl aryl sulfates, condensates of sodium naphthalene sulfonate and formaldehyde, and sodium alkyl diphenyl ether disulfonate.

[0058] (Initiator) As the initiator, a radical polymerization initiator can be used. As the radical polymerization initiator, known radical polymerization initiators can be used, such as potassium persulfate, benzoyl peroxide, hydrogen peroxide, and azo compounds.

[0059] In polymerization step 1 according to one embodiment of the present invention, the initiator may be added in an amount of, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, or 3.0 parts by mass per 100 parts by mass of the raw material monomers, and the amount of initiator added may be within a range between any two of the values ​​exemplified here. In polymerization step 1 according to one embodiment of the present invention, the initiator may be added in multiple portions. In addition to the initial addition at the start of polymerization, additional initiator may be added after the start of polymerization. The number of additional additions may be at least one or more times, and may be two or more times. Additional addition includes continuous addition at a constant flow rate. In polymerization step 1 according to one embodiment of the present invention, the amount of additional initiator added relative to 100% by mass of the initiator used in polymerization step 1 is, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20% by mass, and may be within a range between any two of the values ​​exemplified here. In polymerization step 1 according to one embodiment of the present invention, the timing for additionally adding the initiator may be when the polymerization rate reaches, for example, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99%, and may be within a range between any two of the values ​​exemplified here. In polymerization step 1 according to one embodiment of the present invention, the additional addition of the initiator is carried out to highly adjust the progress of polymerization, thereby adjusting the amount of raw material monomer in the resulting latex of block polymer (A).

[0060] (RAFT Agent) In a production method according to one embodiment of the present invention, a RAFT agent can be used, and by carrying out polymerization in the presence of a known RAFT agent, it is possible to introduce a terminal structure represented by chemical formula (2) or chemical formula (3) into a chloroprene-based block copolymer.

[0061]

[0062] In chemical formula (2), R ３represents any one of hydrogen, chlorine, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted mercapto group, and a substituted or unsubstituted heterocyclyl group.

[0063]

[0064] The compound leading to the structure represented by the above chemical formula (3) is not particularly limited, and general compounds can be used, such as dithiocarbamates and dithioesters. Specific examples include benzyl 1-pyrrolecarbodithioate (common name: benzyl 1-pyrroledithiocarbamate), benzylphenylcarbodithioate, 1-benzyl-N,N-dimethyl-4-aminodithiobenzoate, 1-benzyl-4-methoxydithiobenzoate, 1-phenylethylimidazolecarbodithioate (common name: 1-phenylethylimidazoledithiocarbamate), benzyl-1-(2-pyrrolidinone)carbodithioate, and the like. benzyl phthalimidyl carbodithioate, (common name: benzyl phthalimidyl dithiocarbamate), 2-cyanoprop-2-yl-1-pyrrole carbodithioate, (common name: 2-cyanoprop-2-yl-1-pyrrole dithiocarbamate), 2-cyanoprop-2-yl-1-pyrrole carbodithioate, (common name: 2-cyanoprop-2-yl-1-pyrrole dithiocarbamate), 2-cyanobut-2-yl-1-pyrrole carbodithioate, (common name: 2-cyanobut-2-yl- 1-pyrrole dithiocarbamate), benzyl-1-imidazolecarbodithioate, (trivial name benzyl-1-imidazole dithiocarbamate), 2-cyanoprop-2-yl-N,N-dimethyldithiocarbamate, benzyl-N,N-diethyldithiocarbamate, cyanomethyl-1-(2-pyrrolidone)dithiocarbamate, 2-(ethoxycarbonylbenzyl)prop-2-yl-N,N-diethyldithiocarbamate, 1-phenyl nylethyl dithiobenzoate, 2-phenylprop-2-yldithiobenzoate, 1-acetate-1-yl-ethyl dithiobenzoate, 1-(4-methoxyphenyl)ethyl dithiobenzoate, benzyl dithioacetate, ethoxycarbonylmethyl dithioacetate, 2-(ethoxycarbonyl)prop-2-yldithiobenzoate, 2-cyanoprop-2-yldithiobenzoate, tert-butyl dithiobenzoate, 2,4,4-Trimethylpent-2-yldithiobenzoate, 2-(4-chlorophenyl)-prop-2-yldithiobenzoate, 3-vinylbenzyl dithiobenzoate, 4-vinylbenzyl dithiobenzoate, benzyl diethoxyphosphinyldithioformate, tert-butyl trithioperbenzoate, 2-phenylprop-2-yl-4-chlorodithiobenzoate, naphthalene-1-carboxylic acid-1-methyl-1-phenyl-ethyl ester, 4-cyano-4-methyl-4-thiobenzylsulfanylbutyric acid, dibenzyl tetrathioterephthalate, carboxymethyl dithiobenzoate, poly(ethylene oxide) with dithiobenzoate end groups, poly(ethylene oxide) with 4-cyano-4-methyl-4-thiobenzylsulfanylbutyric acid end groups, 2-[(2-phenylethanethioyl)sulfanyl]propanoic acid, 2-[(2-phenylethanethioyl)sulfanyl]succinic acid , 3,5-dimethyl-1H-pyrazole-1-carbodithioate potassium, cyanomethyl-3,5-dimethyl-1H-pyrazole-1-carbodithioate, cyanomethyl-N-methyl-N-phenyldithiocarbamate, benzyl-4-chlorodithiobenzoate, phenylmethyl-4-chlorodithiobenzoate, 4-nitrobenzyl-4-chlorodithiobenzoate, phenylprop-2-yl-4-chlorodithiobenzoate, 1-cyano Examples of suitable chlorodithiobenzoates include 1-methylethyl-4-chlorodithiobenzoate, 3-chloro-2-butenyl-4-chlorodithiobenzoate, 2-chloro-2-butenyldithiobenzoate, benzyl dithioacetate, 3-chloro-2-butenyl-1H-pyrrole-1-dithiocarboxylic acid, 2-cyanobutan-2-yl 4-chloro-3,5-dimethyl-1H-pyrazole-1-carbodithioate, and cyanomethylmethyl(phenyl)carbamodithioate. Of these, benzyl 1-pyrrolecarbodithioate and benzylphenylcarbodithioate are particularly preferred.

[0065] The compound leading to the structure represented by the above chemical formula (2) is not particularly limited, and a general compound can be used, for example, 2-cyano-2-propyldodecyltrithiocarbonate, dibenzyltrithiocarbonate, butylbenzyltrithiocarbonate, 2-[[(butylthio)thioxomethyl]thio]propionic acid, 2-[[(dodecylthio)thioxomethyl]thio]propionic acid, 2-[[(butylthio)thioxomethyl]thio]succinic acid, 2-[[(dodecylthio)thioxomethyl]thio]succinic acid, 2-[[(dodecylthio)thioxomethyl]thio] ]-2-methylpropionic acid, 2,2'-[carbonothioylbis(thio)]bis[2-methylpropionic acid], 2-amino-1-methyl-2-oxoethylbutyl trithiocarbonate, benzyl 2-[(2-hydroxyethyl)amino]-1-methyl-2-oxoethyltrithiocarbonate, 3-[[[(tert-butyl)thio]thioxomethyl]thio]propionic acid, cyanomethyldodecyltrithiocarbonate, diethylaminobenzyl trithiocarbonate, dibutylaminobenzyl trithiocarbonate, and other trithiocarbonates are particularly preferred.

[0066] The amount of the RAFT agent added can be 0.1 to 10 parts by mass relative to 100 parts by mass of the raw material monomer, for example, 0.1, 0.2, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 parts by mass, and may be within a range between any two of the numerical values ​​exemplified here.

[0067] In the polymerization step, sodium hydroxide and / or potassium hydroxide can be used. In addition, in the polymerization step, a reducing agent can be added. Examples of the reducing agent include potassium pyrosulfite, potassium sulfite, potassium hydrogen sulfite, potassium phosphate, potassium hydrogen phosphate, sodium hydrogen sulfite, sodium sulfate, and thiourea dioxide.

[0068] (Polymerization Conditions) The polymerization temperature may be appropriately determined depending on the type of monomer, but is preferably 10 to 100°C, particularly preferably 20 to 80°C.

[0069] <Polymerization Step 2> In the polymerization step 2, raw material monomers including a chloroprene monomer (and, if necessary, other monomers such as a polyfunctional monomer) are added to the latex containing the polymer block (A) obtained in the polymerization step 1, and polymerization is carried out to obtain a chloroprene block copolymer latex containing a chloroprene block copolymer containing a chloroprene polymer block (B). The raw material monomers may be added all at once, or may be added initially and then additionally. The type and amount of each monomer charged are preferably adjusted so that the content of each monomer unit in the resulting chloroprene polymer block (B) and chloroprene block copolymer falls within the above-mentioned numerical range.

[0070] The polymerization temperature in polymerization step 2 is preferably 10 to 50°C from the viewpoint of ease of polymerization control. The polymerization reaction is terminated by adding a polymerization terminator. Examples of polymerization terminators include thiodiphenylamine, 4-tert-butylcatechol, and 2,2'-methylenebis-4-methyl-6-tert-butylphenol. After completion of polymerization, unreacted monomers can be removed by a conventional method such as vacuum distillation.

[0071] To the latex containing the chloroprene-based block copolymer obtained in the polymerization step 2, a freezing 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 object of the present invention.

[0072] The chloroprene-based block copolymer latex according to one embodiment of the present invention can contain the chloroprene-based block copolymer and water. The liquid obtained at the end of polymerization by the polymerization method described in the above production method can be used as the chloroprene-based block copolymer latex as is. When the chloroprene-based block copolymer latex according to the present invention is obtained by emulsion polymerization, the chloroprene-based block copolymer latex can further contain raw materials used in the emulsion polymerization step, such as an emulsifier. Alternatively, the chloroprene-based block copolymer can be recovered from a latex containing the chloroprene-based block copolymer, and then the recovered chloroprene-based block copolymer can be forcibly emulsified using an emulsifier to obtain the chloroprene-based block copolymer latex. The method for recovering the chloroprene-based block copolymer from a latex containing the chloroprene-based block copolymer is not particularly limited, and known methods can be used, such as a method of recovering the chloroprene-based block copolymer by immersion in a coagulation liquid or a method of precipitating the chloroprene-based block copolymer using a poor solvent such as methanol.

[0073] A production method according to one embodiment of the present invention may include a concentration step in which the chloroprene-based block copolymer latex is concentrated by vacuum distillation or the like. The concentration step can remove unreacted monomers and adjust the solids concentration of the chloroprene-based block copolymer latex. A production method according to one embodiment of the present invention may include one or more concentration steps. The concentration step may be, for example, one, two, three, four, or five times, or may be within a range between any two of the values ​​exemplified herein. A production method according to one embodiment of the present invention may include a dilution step in which the chloroprene-based block copolymer latex is diluted by adding water, thereby diluting the concentrations of the components in the chloroprene-based block copolymer latex and adjusting the solids concentration of the chloroprene-based block copolymer latex. A production method according to one embodiment of the present invention may include one or more dilution steps. The concentration step may be, for example, one, two, three, four, or five times, or may be within a range between any two of the values ​​exemplified herein. When there is a possibility that the raw materials used in the polymerization of the chloroprene-based block copolymer contain aromatic compounds having 7 to 10 carbon atoms, or when there is a possibility that aromatic compounds having 7 to 10 carbon atoms are generated as by-products during the production of the chloroprene-based block copolymer, the content of the aromatic compounds having 7 to 10 carbon atoms can be controlled by adjusting the concentration conditions and number of concentration steps, or the dilution conditions and number of dilution steps of the chloroprene-based block copolymer latex.

[0074] (Solid Content Concentration) The solid content concentration of the chloroprene-based block copolymer latex is not particularly limited, but can be adjusted to 40 to 65 mass %. The solid content concentration of the chloroprene-based block copolymer latex can be controlled by adjusting the blending ratio including a solvent such as water during emulsion polymerization of the chloroprene-based block copolymer, or by the concentration process and dilution process.

[0075] A method for producing a chloroprene-based block copolymer latex composition according to one embodiment of the present invention may include an aromatic compound addition step of adding an aromatic compound having 7 to 10 carbon atoms to the chloroprene-based block copolymer latex. The types of aromatic compounds to be added are as described above. In the aromatic compound addition step, the aromatic compound having 7 to 10 carbon atoms can be added so that the total content of the aromatic compound having 7 to 10 carbon atoms per 100 parts by mass of the solid content in the chloroprene-based block copolymer latex composition obtained falls within the above-described numerical range. As an example, in the aromatic compound addition step, a total of 0.020 to 0.240 parts by mass of the aromatic compound having 7 to 10 carbon atoms is added per 100 parts by mass of the solid content in the chloroprene-based block copolymer latex composition. The total amount of the aromatic compounds having 7 to 10 carbon atoms added is, for example, 0.020, 0.030, 0.040, 0.050, 0.060, 0.070, 0.080, 0.090, 0.100, 0.110, 0.120, 0.130, 0.140, 0.150, 0.160, 0.170, 0.180, 0.190, 0.200, 0.210, 0.220, 0.230, or 0.240 parts by mass, and may be within a range between any two of the numerical values ​​exemplified here.

[0076] In one embodiment of the present invention, a composition containing a chloroprene block copolymer and an aromatic compound having 7 to 10 carbon atoms obtained after performing the concentration step, dilution step, and / or aromatic compound addition step as necessary can be referred to as a chloroprene block copolymer latex composition.

[0077] 3. Composition for Forming Immersion Molded Products The composition for forming an immersion molded product according to one embodiment of the present invention comprises the chloroprene-based block copolymer latex composition described above. The composition for forming an immersion molded product according to one embodiment of the present invention comprises a chloroprene-based block copolymer and an aromatic compound having 7 to 10 carbon atoms, and the total content of the aromatic compound having 7 to 10 carbon atoms is preferably 0.020 to 0.240 parts by mass per 100 parts by mass of the solid content of the chloroprene-based block copolymer contained in the composition for forming an immersion molded product. The composition for forming an immersion molded product according to one embodiment of the present invention may contain, for example, an antioxidant, and may contain other components depending on the purpose and application. Examples of raw materials that may be contained in the composition for forming an immersion molded product according to one embodiment of the present invention include a vulcanizing agent, a vulcanization accelerator, a filler or reinforcing agent, a plasticizer, a processing aid or lubricant, an antioxidant, a silane coupling agent, and a surfactant.

[0078] <Antiaging Agent> The composition for forming an immersion molded body according to one embodiment of the present invention may contain an antioxidant. The composition for forming an immersion molded body according to one embodiment of the present invention may contain 0.5 to 5.0 parts by mass of the antioxidant per 100 parts by mass of the solid content of the chloroprene-based block copolymer contained in the composition for forming an immersion molded body. The content of the antioxidant is, for example, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0 parts by mass, and may be within a range between any two of the numerical values ​​exemplified here.

[0079] Antiaging agents are used to improve heat resistance, and include primary antioxidants that capture radicals to prevent autoxidation and secondary antioxidants that neutralize hydroperoxides. Examples of primary antioxidants include phenol-based antioxidants, amine-based antioxidants, acrylate-based antioxidants, imidazole-based antioxidants, metal carbamates, and waxes. Examples of secondary antioxidants include phosphorus-based antioxidants, sulfur-based antioxidants, and imidazole-based antioxidants. Examples of antioxidants include, but are not limited to, N-phenyl-1-naphthylamine, alkylated diphenylamine, octylated diphenylamine, 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, p-(p-toluenesulfonylamido)diphenylamine, N,N'-di-2-naphthyl-p-phenylenediamine, N,N'-diphenyl-p-phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine, N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine, N-phenyl-N'-(3-methacryloyloxy-2-hydroxypropyl)-p-phenylenediamine, 1,1,3-tris-(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 4,4'-butylidenebis-(3-methyl-6-t-butylphenol), 2,2-thiobis(4-methyl-6-t-butylphenyl) methylphenol), 7-octadecyl-3-(4'-hydroxy-3',5'-di-t-butylphenyl)propionate, tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, pentaerythritol-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], triethylene glycol-bis[3-(3-t-butyl-5-methyl butyl-4-hydroxyphenyl)propionate], 1,6-hexanediol-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 2,4-bis(n-octylthio)-6-(4-hydroxy-3,5-di-t-butylanilino)-1,3,5-triazine, tris-(3,5-di-t-butyl-4-hydroxybenzyl)-isocyanurate, 2,2-thio-diethylenebis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], N,N'-hexamethylenebis(3,5-di-t-butyl-4-hydroxy)-hydrocinnaamide, 2,4-bis[(octylthio)methyl]-o-cresol, 3,5-di-t-butyl-4-hydroxybenzyl-phosphonate-diethyl ester, tetrakis[methylene(3,5-di-t-butyl-4-hydroxyhydrocinnamate)]methane, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate tris(nonylphenyl) phosphite, tris(mixed mono- and di-nonylphenyl) phosphite, diphenyl mono(2-ethylhexyl) phosphite, diphenyl monotridecyl phosphite, diphenyl isodecyl phosphite, diphenyl isodecyl phosphite, diphenyl methyl phosphate ... diphenyl isooctyl phosphite, diphenyl nonylphenyl phosphite, triphenyl phosphite, tris(tridecyl) phosphite, triisodecyl phosphite, tris(2-ethylhexyl) phosphite, tris(2,4-di-t-butylphenyl) phosphite, tetraphenyldipropylene glycol diphosphite, tetraphenyltetra(tridecyl)pentaerythritol tetraphosphite, 1,1,3-tris(2- Methyl-4-di-tridecylphosphite-5-t-butylphenyl)butane, 4,4'-butylidenebis-(3-methyl-6-t-butyl-di-tridecylphosphite), 2,2'-ethylidenebis(4,6-di-t-butylphenol)fluorophosphite, 4,4'-isopropylidene-diphenol alkyl (C12-C15) phosphite, cyclic neopentanetetraylbis(2,4-di-t-butylphenyl phosphite), cyclic neopentanetetraylbis(2,6-di-t-butyl-4-phenyl phosphite), cyclic neopentanetetraylbis(nonylphenyl phosphite), bis(nonylphenyl)pentaerythritol diphosphite, dibutyl hydrogen phosphite, distearyl pentaerythritol diphosphite, hydrogenated bisphenol A pentaerythritol phosphite polymer, 2-mercaptobenzimidazole, butylated reaction product of p-cresol and dicyclopentadiene, etc.

[0080] <Vulcanizing Agent and Vulcanization Accelerator> The composition for forming a dip-molded body according to one embodiment of the present invention may contain a vulcanizing agent and / or a vulcanization accelerator. Furthermore, the composition for forming a dip-molded body according to one embodiment of the present invention may not contain sulfur or the aforementioned thiuram-based, dithiocarbamate-based, thiourea-based, guanidine-based, xanthogenate-based, thiazole-based, or other vulcanization accelerators. That is, the composition for forming a dip-molded body includes those containing a vulcanizing agent but not a vulcanization accelerator, those containing a vulcanization accelerator but not a vulcanizing agent, those containing a vulcanization accelerator and a vulcanization accelerator, and those containing neither a vulcanizing agent nor a vulcanization accelerator. Whether or not a vulcanizing agent and a vulcanization accelerator are added may be determined depending on the desired dip-molded body.

[0081] Examples of vulcanizing agents include, but are not limited to, sulfur. The amount of vulcanizing agent added can be 0 to 5.0 parts by mass per 100 parts by mass of the solid content of the chloroprene-based block copolymer contained in the composition for forming a dip-molded body. The amount of vulcanizing agent added can be, for example, 0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0 parts by mass, and may be within a range between any two of the values ​​exemplified here.

[0082] A vulcanization accelerator is a chemical added during the vulcanization of raw rubber to act with the vulcanizing agent to increase the vulcanization speed, thereby shortening the vulcanization time, lowering the vulcanization temperature, reducing the amount of vulcanizing agent, and improving the physical properties of the vulcanized rubber. It usually refers to a chemical that accelerates the sulfur vulcanization reaction.

[0083] Examples of vulcanization accelerators include, but are not limited to, thiuram-based, dithiocarbamate-based, thiourea-based, guanidine-based, xanthogenate-based, thiazole-based, etc. These may be used alone or in combination of two or more types as required.

[0084] Examples of thiuram vulcanization accelerators include tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, tetrakis(2-ethylhexyl)thiuram disulfide, tetramethylthiuram monosulfide, and dipentamethylenethiuram tetrasulfide.

[0085] Examples of the dithiocarbamate vulcanization accelerator include sodium dibutyldithiocarbamate, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc N-ethyl-N-phenyldithiocarbamate, zinc N-pentamethylenedithiocarbamate, copper dimethyldithiocarbamate, ferric dimethyldithiocarbamate, and tellurium diethyldithiocarbamate, and zinc dibutyldithiocarbamate is particularly preferred.

[0086] Examples of the thiourea-based vulcanization accelerator include ethylene thiourea, N,N'-diethyl thiourea, trimethyl thiourea, and N,N'-diphenyl thiourea.

[0087] Examples of the guanidine vulcanization accelerator include 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, and di-o-tolylguanidine salts of dicatechol borate.

[0088] Examples of xanthogenate-based vulcanization accelerators include zinc butylxanthogenate and zinc isopropylxanthogenate.

[0089] Examples of the thiazole vulcanization accelerator include 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, 2-mercaptobenzothiazole zinc salt, 2-mercaptobenzothiazole cyclohexylamine salt, and 2-(4'-morpholinodithio)benzothiazole.

[0090] The amount of vulcanization accelerator added can be 0 to 5.0 parts by mass per 100 parts by mass of the solid content of the chloroprene-based block copolymer contained in the composition for forming an immersion molded body. The amount of vulcanization accelerator added can be, for example, 0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0, and can be within a range between any two of the values ​​exemplified here. The immersion molded body according to one embodiment of the present invention has sufficient mechanical strength without vulcanization and can be excellent in elongation at break and hardness. Therefore, from the viewpoints of reducing allergies and reducing costs, the composition can be free of vulcanizing agents and vulcanization accelerators.

[0091] 4. Coating Composition A coating composition according to one embodiment of the present invention comprises the chloroprene block copolymer latex composition described above. The coating composition according to one embodiment of the present invention comprises a chloroprene block copolymer and an aromatic compound having 7 to 10 carbon atoms. Preferably, the total content of the aromatic compound having 7 to 10 carbon atoms is 0.020 to 0.240 parts by mass per 100 parts by mass of the solids content of the chloroprene block copolymer latex composition in the coating composition. The coating composition according to one embodiment of the present invention may contain, for example, an antioxidant, and may contain other components depending on the purpose and application. Examples of raw materials that may be contained in the coating composition according to one embodiment of the present invention include vulcanizing agents, vulcanization accelerators, fillers or reinforcing agents, plasticizers, processing aids and lubricants, antioxidants, silane coupling agents, surfactants, etc. The types and amounts of each component are as described above for the composition for forming dip-molded bodies.

[0092] 5. Dip-molded body and coating film (molded body) An immersion-molded body according to one embodiment of the present invention can be a dip-molded body of the above-mentioned composition for forming a dip-molded body. The immersion-molded body can be suitably used for gloves, balloons, catheters, and boots. A coating film (molded body) according to one embodiment of the present invention can be a coating film (molded body) of the above-mentioned paint composition. The coating film (molded body) can be suitably used for an intermediate coating film for automobiles, etc.

[0093] (Tensile Strength at Break) The immersion molded article and coating film (molded article) according to one embodiment of the present invention preferably have a tensile strength at break of, for example, 17.5 MPa or more, measured in accordance with JIS K 6251. Specific examples of the tensile strength at break of the immersion molded article include 17.5, 18.0, 19.0, 20.0, 21.0, 22.0, 23.0, 24.0, 25.0, 26.0, 27.0, 28.0, 29.0, and 30.0 MPa, and may be within a range between any two of the numerical values ​​exemplified here.

[0094] (Elongation at Break) The dip-molded article and coating film (molded article) according to one embodiment of the present invention preferably have an elongation at break of 800% or more as measured in accordance with JIS K 6251. The elongation at break is, for example, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, or 1700%, and may be within a range between any two of the values ​​exemplified here.

[0095] (Stress at 500% Elongation) The dip-molded body and coating film (molded body) according to one embodiment of the present invention have a stress at 500% elongation measured in accordance with JIS K 6251 of, for example, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, or 4.0 MPa, and may be within a range between any two of the numerical values ​​exemplified here.

[0096] 6. Method for producing an immersion molded body and a coating film (molded body) A method for producing an immersion molded body according to one embodiment of the present invention can include a dip molding step of immersion molding the above-mentioned composition for forming an immersion molded body to obtain a immersion molded body, and a heat treatment step. Also, a method for producing a coating film (molded body) according to one embodiment of the present invention can include a molding step of molding the above-mentioned coating composition by any method, and a heat treatment step.

[0097] Examples of dip molding methods according to one embodiment of the present invention include the immersion coagulation method, simple immersion method, thermal immersion method, and electrodeposition method. The immersion coagulation method can be used from the viewpoints of ease of production and the ease of obtaining a dip-molded body of a uniform thickness. Specifically, a ceramic mold coated with a calcium-based coagulation liquid is immersed in a dip-molded body composition, and the dip-molded body composition is coagulated. Water-soluble impurities are then removed by leaching, followed by drying. A dip-molded film (rubber film) is then formed by heating, and the dip-molded film is then demolded. This allows a film-like dip-molded body to be obtained.

[0098] A molding method according to one embodiment of the present invention can include, for example, a step of pouring the coating composition into any desired location such as a mold, drying it, and obtaining a coating film (molded product, for example, a film).

[0099] A method for producing a dip-molded body and a coating film (molded body) according to one embodiment of the present invention can include a heat treatment step of heat-treating the dip-molded body and the coating film (molded body).

[0100] The heat treatment temperature may be 120 to 180° C., and preferably 120 to 150° C. The heat treatment temperature may be, for example, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, or 220° C., or may be within a range between any two of the values ​​exemplified here. The heat treatment time may be appropriately set depending on the composition, shape, etc. of the chloroprene-based block copolymer, and may be 10 to 300 minutes. The heat treatment time may be, 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, or may be within a range between any two of the values ​​exemplified here. As an example, a dip-molded body according to one embodiment of the present invention may be heat-treated at 130°C for 30 minutes.

[0101] The present invention will be described in more detail below based on examples, but the present invention should not be construed as being limited to these examples.

[0102] Example 1 (Polymerization Step 1) Synthesis of Polymer Block (A-1) Polymerization was carried out using a 10 L autoclave equipped with a stirrer and a heating / cooling jacket. 3,419 g of pure water, 151 g of disproportionated potassium rosinate (manufactured by Harima Chemicals Group Co., Ltd.), 2.16 g of potassium hydroxide, 17.1 g of sodium salt of β-naphthalenesulfonic acid formalin condensate (manufactured by Kao Corporation, product name: Demol N), 332 g of styrene monomer, and 5.91 g of butylbenzyl trithiocarbonate were charged, and the internal temperature was raised to 80°C and the mixture was stirred at 200 rpm under a nitrogen stream. 3.72 g of 2,2'-azobis[2-(2-imidazolin-2-yl)propane]dihydrogen chloride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., product name: VA-044) was added as a polymerization initiator to initiate polymerization. When the polymerization rate reached 95%, 0.30 g of a polymerization initiator, 2,2'-azobis[2-(2-imidazolin-2-yl)propane]dihydrogen chloride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., product name: VA-044), was added. Polymerization was continued until the polymerization rate reached 99%. 20 ml of the obtained latex was sampled for property measurement, and the remaining latex was used in polymerization step 2.

[0103] The sampled latex was mixed with a large amount of methanol to precipitate the resin, which was then filtered and dried to obtain a sample of polymer block (A-1). The number average molecular weight, molecular weight distribution, and glass transition temperature of the polymer block (A-1) were determined from the obtained sample by analysis. The measurement methods will be described later.

[0104] (Polymerization Step 2) Synthesis of Chloroprene-Based Polymer Block (B-1) After polymerization step 1, when the internal temperature had cooled to 45°C, 3528 g of chloroprene monomer and 1,9-nonanediol diacrylate were slowly added over 2 hours to conduct polymerization. When the polymerization rate of the chloroprene monomer reached 82%, the polymerization was terminated by adding a 10 wt% aqueous solution of N,N-diethylhydroxylamine, a polymerization terminator, and unreacted chloroprene monomer was removed by vacuum distillation. Water was added to the mixture to adjust the solids concentration to 40% by mass, and this was further concentrated to a solids concentration of 50% by mass, followed by the addition of 0.1 g of styrene. For physical property measurements, 20 ml of the resulting latex was sampled, and the remaining latex was used to prepare a composition for forming a dip-molded body, from which a dip-molded body was produced.

[0105] The sampled latex was used to analyze the content of aromatic compounds having 7 to 10 carbon atoms and evaluate mechanical stability. Furthermore, the aromatic compounds having 7 to 10 carbon atoms were mixed with a large amount of methanol to precipitate a resin component, which was then filtered and dried to obtain a chloroprene-based block copolymer sample. The contents (mass%) of the polymer block (A-1) and the chloroprene-based polymer block (B-1) of the chloroprene-based block copolymer were determined from the obtained sample by analysis. The analytical results are shown in Table 1. The measurement method will be described later.

[0106] (Examples 2 to 6, Comparative Examples 1 to 3) In the polymerization step 1 and the polymerization step 2, a chloroprene-based block copolymer latex was obtained in the same manner as in Example 1, except that the type and amount of each agent added and the polymerization conditions were as shown in the table.

[0107] [Analysis of Polymer Block (A)] <Measurement of Number Average Molecular Weight and Molecular Weight Distribution of Polymer Block (A)> The number average molecular weight and molecular weight distribution are values ​​measured by gel permeation chromatography (GPC) in terms of polystyrene, and are values ​​measured under the measurement conditions described below. Apparatus name: HLC-8320 (manufactured by Tosoh Corporation) Column: Three TSKgel GMHHR-H columns in series Temperature: 40°C Detection: Differential refractive index Solvent: Tetrahydrofuran Calibration curve: Prepared using standard polystyrene (PS).

[0108] <Glass Transition Temperature of Polymer Block (A)> The glass transition temperature was measured using a differential scanning calorimeter according to JIS K 7121 by the following method. Apparatus name: DSC1 (manufactured by Mettler Toledo) Procedure: In a nitrogen gas flow of 50 ml / min, the sample was heated to 120°C at a heating rate of 10°C / min, maintained at 120°C for 10 minutes, cooled to -60°C, and then heated to 120°C at a heating rate of 10°C / min to obtain a DSC curve. The glass transition temperature was determined as the temperature at the intersection of a straight line extending the base line on the higher temperature side toward the lower temperature side and a tangent line drawn on the curve on the higher temperature side of the peak at the point where the slope is maximum.

[0109] [Analysis of Chloroprene-Based Block Copolymer Latex Composition] <Measurement of Contents of Polymer Block (A) and Chloroprene-Based Polymer Block (B) in Chloroprene-Based Block Copolymer> Pyrolysis gas chromatogram and １ Measurement was carried out using H-NMR by the following method. Pyrolysis gas chromatogram Apparatus name: HP5890-II Column: DB-5 0.25 mmφ×30 m (film thickness 1.0 μm) Column temperature: 50°C (5 min) → 10°C / min → 150°C → 25°C / min → 300°C Injection port temperature: 250°C Detector temperature: 280°C Detector: FID １ H-NMR Apparatus name: JNM-ECX-400 (manufactured by JEOL Ltd.) Procedure: A chloroprene-based block copolymer consisting of a polymer block (A) and a chloroprene-based polymer block (B) not containing an unsaturated nitrile monomer unit was measured by pyrolysis gas chromatogram, and the area ratio of the peak derived from the polymer block (A) to the peak derived from the chloroprene-based polymer block (B) and １A calibration curve was prepared from the contents of polymer block (A) and chloroprene polymer block (B) in the chloroprene-based block copolymer obtained by H-NMR measurement. The sampled latex was mixed with methanol to precipitate a chloroprene-based block copolymer sample, which was then measured by pyrolysis gas chromatography. From the area ratio of the peak derived from polymer block (A) to the peak derived from chloroprene-based polymer block (B), the contents of polymer block (A) and chloroprene-based polymer block (B) in the chloroprene-based block copolymer were determined using the calibration curve prepared above.

[0110] <Concentration and Content of Aromatic Compounds Having 7 to 10 Carbon Numbers> The chloroprene block copolymer latex composition was analyzed by gas chromatography (headspace method). 0.03 g of the chloroprene polymer latex composition was collected in a vial, sealed, and measured under the following conditions. (Gas Chromatography Conditions) Apparatus: Agilent GC-8890 Column: DB-1 φ0.25 mm × 60 m (film thickness: 1 μm) Column temperature: 50°C → 5°C / min → 300°C Inlet temperature: 270°C Detector temperature: 300°C Detector: FID The concentration [ppm] of aromatic compounds having 7 to 10 carbon atoms in the chloroprene polymer latex composition was determined using a calibration curve of the area of ​​the peaks derived from aromatic compounds having 7 to 10 carbon atoms obtained by the measurement and the content of aromatic compounds having 7 to 10 carbon atoms. The results are shown in Table 1. From the determined concentrations of the aromatic compounds having 7 to 10 carbon atoms in the chloroprene polymer latex composition, the amount (parts by mass) of the aromatic compounds having 7 to 10 carbon atoms per 100 parts by mass of the solid content in the chloroprene polymer latex composition was calculated using the following formula. The results are shown in Table 1. Amount (parts by mass) of the aromatic compounds having 7 to 10 carbon atoms per 100 parts by mass of the solid content in the chloroprene polymer latex composition=100×(concentration (ppm) of the aromatic compounds having 7 to 10 carbon atoms) / 1,000,000×100 / (solid content (% by mass) of the chloroprene polymer latex composition) In Examples 1 to 3, 5, and 6 and Comparative Examples 1 to 3, styrene was detected as the aromatic compound having 7 to 10 carbon atoms at the concentrations shown in Table 1. In Example 4, styrene and divinylbenzene were detected at the concentrations shown in Table 1.

[0111] <Mechanical Stability> Using a Marlon testing apparatus, a shear force of 10 kg load and 1,000 rpm was applied to 50 g of a chloroprene-based block copolymer latex composition having a solid content concentration of 50% by mass for 10 minutes, and the amount of aggregates generated was evaluated. After applying the shear force under the above conditions, the aggregates adhering to the rotor of the Marlon testing apparatus were collected on a SUS80 mesh wire screen, washed with pure water, dried under reduced pressure, and then their masses were measured. The aggregate generation rate was calculated from the measured dry mass of the aggregates using the following formula and evaluated according to the following criteria: Aggregate Generation Rate (Mechanical Stability) (mass %) = Dry Mass of Aggregates [g] / Mass of Solids of Chloroprene-Based Block Copolymer Latex Composition [g] × 100. Excellent: The aggregate generation rate was 0.01% by mass or more and 1.00% by mass or less. Excellent: The aggregate generation rate was greater than 1.00% by mass and 2.00% by mass or less. Bad: The aggregate generation rate was greater than 2.00% by mass.

[0112] [Evaluation of Composition for Forming Dip Molded Body] <Preparation of Composition for Forming Dip Molded Body> 2 parts by mass of a butylated p-cresol and dicyclopentadiene condensate compound (Nocrac PBK, manufactured by Ouchi Shinko Chemical Co., Ltd.) as an antioxidant, 0.1 parts by mass of a sodium salt of β-naphthalenesulfonic acid formalin condensate (Demol N, manufactured by Kao Corporation) as a dispersant, and water were added to 100 parts by mass of the chloroprene block copolymer in the chloroprene block copolymer latex composition (converted to solids content), so that the solids concentration of the blend was 30% by mass, and the mixture was mixed at 20°C for 16 hours using a ceramic ball mill to prepare a composition for forming a dip molded body.

[0113] <Mechanical Stability> Using a Marlon testing apparatus, 50 g of a composition for forming a dip-molded body with a solid content concentration of 30% was subjected to a shear force of 10 kg under a load of 1000 rpm for 10 minutes, and the amount of aggregates generated was evaluated. After applying the shear force under the above conditions, the aggregates adhering to the rotor of the Marlon testing apparatus were collected on a SUS80 mesh wire screen, washed with pure water, dried under reduced pressure, and then their masses were measured. The aggregate generation rate was calculated from the measured dry mass of the aggregates using the following formula to provide an index of mechanical stability. A smaller value of the aggregate generation rate indicates better stability against shear force and better mechanical stability. Aggregate generation rate (mechanical stability) (mass %) = dry mass of aggregates [g] / mass of solids of chloroprene-based block copolymer latex composition [g] × 100. Excellent: The aggregate generation rate was 0.01% by mass or more and 1.00% by mass or less. Good: The aggregate generation rate was greater than 1.00% by mass and 2.00% by mass or less. ×: The rate of agglomeration was more than 2.00% by mass.

[0114] [Evaluation of Molded Products] (Film Production) A ceramic cylinder with an outer diameter of 50 mm was immersed for 1 second in a coagulation liquid containing 62 parts by mass of water, 35 parts by mass of potassium nitrate tetrahydrate, and 3 parts by mass of calcium carbonate, and then removed. After drying for 4 minutes, the cylinder was immersed for 2 minutes in the composition for forming a dip-molded product prepared above. The cylinder was then washed with running water at 45°C for 1 minute and heat-treated at 130°C for 30 minutes to remove moisture, producing a test dip-molded product (140 x 150 mm, thickness: 0.2 mm).

[0115] (Stress at 500% Elongation, Tensile Strength at Break, Elongation at Break) Using the dip-molded test specimens, the stress at 500% elongation, tensile strength at break, and elongation at break were measured according to JIS K 6251:2017.

[0116]

Claims

1. A chloroprene-based block copolymer latex composition comprising a chloroprene-based block copolymer comprising a polymer block (A) and a chloroprene-based polymer block (B), wherein the polymer block (A) comprises monomer units derived from a monomer (A), and the monomer (A) is a monomer which, upon homopolymerization, gives a polymer having a glass transition temperature of 80°C or higher, and wherein the chloroprene-based block copolymer latex composition has a total content of aromatic compounds having 7 to 10 carbon atoms of 0.020 to 0.240 parts by mass per 100 parts by mass of solids in the chloroprene-based block copolymer latex composition.

2. The chloroprene block copolymer latex composition according to claim 1, wherein the aromatic compound having 7 to 10 carbon atoms comprises at least one selected from the group consisting of toluene, ethylbenzene, cumene, xylene, diethylbenzene, propyltoluene, styrene and divinylbenzene.

3. The chloroprene block copolymer latex composition according to claim 1 or 2, comprising 7.0 to 15.0% by mass of the polymer block (A) relative to 100% by mass of the chloroprene block copolymer.

4. The chloroprene block copolymer latex composition according to claim 1 or 2, wherein the number average molecular weight of the polymer block (A) is 14,000 to 30,000.

5. The chloroprene block copolymer latex composition according to claim 1 or 2, wherein the polymer block (A) contains a monomer unit derived from the aromatic compound having 7 to 10 carbon atoms.

6. A composition for forming a dip-molded product, comprising the chloroprene block copolymer latex composition according to claim 1 or 2.

7. A dip-molded body made from the composition for forming a dip-molded body according to claim 6.

8. A coating composition comprising the chloroprene block copolymer latex composition according to claim 1 or 2.

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