Chloroprene-based block copolymer, latex, latex composition and rubber composition

Abstract

The present invention provides a chloroprene-based block copolymer, a latex, a latex composition, and a rubber composition that can obtain a product having excellent tensile properties and good flexibility even without using a vulcanizing agent and a vulcanization accelerator. A chloroprene-based block copolymer contains 5 to 30% by mass of a polymer block (A) derived from a monomer that gives a polymer having a glass transition temperature of 80°C or higher upon homopolymerization; and 70 to 95% by mass of a chloroprene-based polymer block (B) having a chloroprene monomer unit and a polyfunctional monomer unit.

Description

Technical Field

[0001] The present invention relates to a chloroprene-based block copolymer, a latex, a latex composition, and a rubber composition. Background Art

[0002] Currently, various technologies related to chloroprene-based block copolymers have been proposed. For example, it is known that a copolymer obtained by polymerizing chloroprene using a polystyrene containing an azo group as an initiator (for example, refer to Patent Document 1); a copolymer obtained by polymerizing a polychloroprene esterified with dithiocarbamic acid and an aromatic vinyl monomer (for example, refer to Patent Document 2); a copolymer formed by connecting a chloroprene-based polymer and a hydrophilic oligomer or a hydrophilic polymer (for example, refer to Patent Document 3); a copolymer having a block of an aromatic vinyl compound polymer and a block of a chloroprene polymer and having determined the number-average molecular weight of the whole and the number-average molecular weight of the block of the chloroprene polymer (for example, refer to Patent Document 4); a copolymer having a block of an acrylate polymer and a block of a chloroprene polymer (for example, refer to Patent Document 5).

[0003] In addition, as a method of causing chemical bonding between molecules without vulcanization, the technique described in Patent Document 6 is known.

[0004] [Prior Art Documents]

[0005] [Patent Documents]

[0006] Patent Document 1: Japanese Patent Laid-Open No. 3-207710

[0007] Patent Document 2: Japanese Patent Laid-Open No. 3-212414

[0008] Patent Document 3: Japanese Patent Laid-Open No. 2007-297502

[0009] Patent Document 4: International Publication No. 2018 / 181801

[0010] Patent Document 5: International Publication No. 2019 / 026914

[0011] Patent Document 6: Japanese Patent Laid-Open No. 2014-221901 Summary of the Invention

[0012] Problems to be Solved by the Invention

[0013] Conventionally, in order to obtain the required mechanical strength, vulcanizing agents such as sulfur, zinc oxide, and magnesium oxide inevitably had to be used in polychloroprene-based rubber compositions; and vulcanization accelerators such as thiuram-based, dithiocarbamate-based, thiourea-based, guanidine-based, xanthate-based, and thiazole-based accelerators. Vulcanization accelerators are type IV allergenic substances that cause skin diseases such as dermatitis. Therefore, reducing or not using vulcanization accelerators has become an important issue. In addition, not using vulcanization accelerators can not only reduce allergies but also lower costs. Therefore, it is desired to develop a rubber composition that exhibits sufficient mechanical strength without using vulcanization accelerators.

[0014] Therefore, an object of the present invention is to provide a chloroprene-based block copolymer, latex, latex composition, and rubber composition that can obtain a product having excellent tensile properties and good flexibility even without using a vulcanizing agent and a vulcanization accelerator.

[0015] Means for Solving the Problems

[0016] The gist of the present invention is as follows.

[0017] (1) A chloroprene-based block copolymer containing 5 to 30% by mass of a polymer block (A) derived from a monomer that gives a polymer having a glass transition temperature of 80°C or higher upon homopolymerization; and 70 to 95% by mass of a chloroprene-based polymer block (B) having a chloroprene monomer unit and a polyfunctional monomer unit.

[0018] (2) The chloroprene-based block copolymer according to (1), wherein the molded body of the latex composition containing the chloroprene-based block copolymer has a breaking tensile strength of 17 MPa or more as measured according to JIS K6251 after heat treatment at 130°C for 30 minutes.

[0019] (3) The chloroprene-based block copolymer according to (1) or (2), wherein the number average molecular weight of the polymer block (A) is 10,000 or more.

[0020] (4) The chloroprene-based block copolymer according to any one of (1) to (3), wherein the molecular weight distribution of the polymer block (A) is 2.0 or less.

[0021] (5) The chloroprene-based block copolymer according to any one of (1) to (4), wherein the polymer block (A) is a polymer block composed of aromatic vinyl monomer units.

[0022] (6) The chloroprene-based block copolymer according to any one of (1) to (5), wherein the polyfunctional monomer is a monomer represented by the chemical formula (1) or an aromatic polyene monomer.

[0023]

Chemical Formula 1

[0024]

[0025] (In Chemical Formula (1), R 1 and R 2 each independently represent any one of hydrogen, chlorine, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted aryl, substituted or unsubstituted mercapto, and substituted or unsubstituted heterocyclic group. W 1 represents any one of a saturated or unsaturated hydrocarbon group, a saturated or unsaturated cyclic hydrocarbon group, a saturated or unsaturated hydrocarbon group containing a heteroatom, and a saturated or unsaturated cyclic hydrocarbon group containing a heteroatom. Z 1 represents oxygen, sulfur, or a structure represented by -NR 0 -. R 0 represents any one of hydrogen, chlorine, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted aryl, substituted or unsubstituted mercapto, and substituted or unsubstituted heterocyclic group.)

[0026] (7) The chloroprene-based block copolymer according to any one of (1) to (6), which has a functional group having a structure represented by Chemical Formula (2) or Chemical Formula (3).

[0027] [Chemical Formula 2]

[0028]

[0029] (In Chemical Formula (2), R 3 represents any one of hydrogen, chlorine, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted aryl, substituted or unsubstituted mercapto, and substituted or unsubstituted heterocyclic group.)

[0030] [Chemical Formula 3]

[0031]

[0032] (8) A latex containing the chloroprene-based block copolymer according to any one of (1) to (7).

[0033] (9) A latex composition containing 100 parts by mass of the latex according to (8) and 0.5 to 5.0 parts by mass of an anti-aging agent.

[0034] (10) A rubber composition containing the chloroprene-based block copolymer according to any one of (1) to (7).

[0035] (11) A rubber composition composed of the latex according to (8).

[0036] (12) A rubber composition, which is composed of the latex composition as described in (9).

[0037] Effects of the Invention

[0038] According to the present invention, there are provided a chloroprene-based block copolymer, a latex, a latex composition, and a rubber composition which can obtain a product having excellent tensile properties and good flexibility even without using a vulcanizing agent and a vulcanization accelerator. Detailed Description of Embodiments

[0039] Hereinafter, embodiments of the present invention will be described in detail. It should be noted that in this specification and the claims, "A to B" means A or more and B or less.

[0040] <Chloroprene-based Block Copolymer>

[0041] The chloroprene-based block copolymer is a block copolymer containing a polymer block (A) derived from a monomer capable of obtaining a polymer having a glass transition temperature of 80 °C or higher during homopolymerization and a chloroprene-based polymer block (B) having a chloroprene monomer and a polyfunctional monomer unit. The chloroprene-based block copolymer further includes a copolymer having a structure in which block copolymers are chemically bonded to each other through the polyfunctional monomer units contained in the chloroprene-based polymer block (B).

[0042] [Polymer Block (A)]

[0043] The polymer block (A) is a polymer block derived from a monomer capable of obtaining a polymer having a glass transition temperature of 80 °C or higher during homopolymerization. By using such a monomer, the breaking tensile strength of the obtained chloroprene-based block copolymer can be improved. Monomers capable of obtaining a polymer having a glass transition temperature of 85 °C or higher are preferably used. From the viewpoint of moldability, monomers capable of obtaining a polymer having a glass transition temperature of 150 °C or lower are preferably used, and monomers capable of obtaining a polymer having a glass transition temperature of 120 °C or lower are particularly preferred. The glass transition temperature is, for example, 80, 85, 90, 95, 100, 105, 110, 120, 130, 140, 150 °C, and may also be within the range between any two of the values exemplified herein. It should be noted that in this specification, the glass transition temperature is the extrapolated glass transition end temperature (Teg) measured according to JIS K 7121. When the polymer block (A) is a polymer block obtained by polymerizing a monomer (A), when the monomer A is homopolymerized to form a homopolymer (A) having a number average molecular weight of 10,000 to 30,000, the homopolymer (A) preferably has the above-mentioned glass transition temperature.

[0044] As the monomer units constituting the polymer block (A), aromatic vinyl monomer units, methyl methacrylate monomer units, and acrylonitrile monomer units can be mentioned. Units derived from aromatic vinyl monomers are preferably used, and styrene units are suitably used. Within the range not impairing the object of the present invention, the polymer block (A) may also be a polymer block obtained by copolymerizing these monomers with each other or a polymer block composed of these monomers and copolymerizable monomer units.

[0045] From the viewpoints of the tensile properties and moldability of the obtained chloroprene-based block copolymer, the number-average molecular weight of the polymer block (A) is preferably 10,000 or more. The number-average molecular weight of the polymer block (A) can be, for example, 10000, 15000, 20000, 25000, 30000, and can also be within the range between any two of the values exemplified herein. In addition, the molecular weight distribution of the polymer block (A) is preferably 2.0 or less from the viewpoint of moldability. The molecular weight distribution of the polymer block (A) can be, for example, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, and can also be within the range between any two of the values exemplified herein.

[0046] It should be noted that in this specification, the number-average molecular weight and the weight-average molecular weight are values in terms of polystyrene measured by gel permeation chromatography (GPC), and are the measured values under the following measurement conditions.

[0047] Apparatus name: HLC-8320 (manufactured by Tosoh Corporation)

[0048] Column: 3 TSKgel GMHHR-H columns in series

[0049] Temperature: 40 °C

[0050] Detection: Differential refractive index

[0051] Solvent: Tetrahydrofuran

[0052] Standard curve: Prepared using standard polystyrene (PS).

[0053] [Chloroprene-based polymer block (B)]

[0054] The chloroprene-based polymer block (B) is a polymer block having chloroprene monomer (2-chloro-1,3-butadiene) units and polyfunctional monomer units. It should be noted that within the range not impairing the object of the present invention, the chloroprene-based polymer block (B) may also be a polymer block composed of chloroprene monomer units, polyfunctional monomer units, and monomer units copolymerizable with these monomers.

[0055] The content of each constituent unit in the chloroprene polymer block (B) is not particularly limited. Preferably, the chloroprene monomer unit is 90 to 99.95% by mass, and the polyfunctional monomer unit is 0.05 to 10% by mass. The content of the polyfunctional monomer unit in the chloroprene polymer block (B) is, for example, 0.05, 0.50, 1.00, 2.00, 3.00, 4.00, 5.00, 6.00, 7.00, 8.00, 9.00, 10.00% by mass, and can also be within the range between any two values exemplified herein.

[0056] [Polyfunctional monomer]

[0057] The polyfunctional monomer is a compound having two or more free-radical polymerizable groups in the molecule. From the viewpoints of the flexibility, breaking tensile strength, and moldability of the obtained chloroprene block copolymer, monomers represented by Chemical Formula (1) and aromatic polyene monomers are preferably used. As the monomer represented by Chemical Formula (1), 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, N,N'-dacryloyl-4,7,10-trioxa-1,13-tridecanediamine are particularly preferably used. As the aromatic polyene monomer, it is an aromatic polyene having 10 or more and 30 or less carbon atoms and having multiple double bonds (vinyl groups) and one or more aromatic groups. For example, units derived from aromatic polyene monomers such as o-divinylbenzene, p-divinylbenzene, m-divinylbenzene, 1,4-divinylnaphthalene, 3,4-divinylnaphthalene, 2,6-divinylnaphthalene, 1,2-divinyl-3,4-dimethylbenzene, 1,3-divinyl-4,5,8-tributylnaphthalene are exemplified, and any one or a mixture of two or more of o-divinylbenzene unit, p-divinylbenzene unit, and m-vinylbenzene unit is preferably used.

[0058] [Chemical Formula 4]

[0059]

[0060] (In Chemical Formula (1), R 1 and R 2 each independently represent any one of hydrogen, chlorine, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted aryl, substituted or unsubstituted mercapto, and substituted or unsubstituted heterocyclic group. W 1represents any one of a saturated or unsaturated hydrocarbon group, a saturated or unsaturated cyclic hydrocarbon group, a saturated or unsaturated hydrocarbon group containing a heteroatom, and a saturated or unsaturated cyclic hydrocarbon group containing a heteroatom. Z 1 represents oxygen, sulfur or -NR 0 - represents the structure. 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 heterocyclic group.)

[0061] The content of each constituent unit of the chloroprene-based block copolymer is 5 to 30% by mass of the polymer block (A) and 70 to 95% by mass of the chloroprene-based polymer block (B), preferably 5 to 15% by mass of the polymer block (A) and 85 to 95% by mass of the chloroprene-based polymer block (B). When the polymer block (A) is 5% by mass or more, the breaking tensile strength of the obtained chloroprene-based block copolymer is improved. When the polymer block (A) is 30% by mass or less, the flexibility of the obtained chloroprene-based block copolymer is improved. The polymer block (A) is preferably 15% by mass or less. When the chloroprene-based polymer block (B) is 70% by mass or more, the flexibility of the obtained chloroprene-based block copolymer is improved. The chloroprene-based polymer block (B) is preferably 85% by mass or more. When the chloroprene-based polymer block (B) is 95% by mass or less, the breaking tensile strength of the obtained chloroprene-based block copolymer is improved. When the chloroprene-based block copolymer is set to 100% by mass, the content rate of the polymer block (A) contained in the chloroprene-based block copolymer is, for example, 5, 10, 15, 20, 25, 30% by mass, and may also be within the range between any two of the values exemplified herein.

[0062] The chloroprene-based block copolymer according to one embodiment of the present invention may be composed of the polymer block (A) and the polymer block (B), and may not contain other polymer blocks. The chloroprene-based block copolymer may be a diblock copolymer of the polymer block (A)-the polymer block (B).

[0063] The weight-average molecular weight of the chloroprene-based block copolymer is not particularly limited, and is preferably 50,000 to 600,000 from the viewpoint of moldability, and particularly preferably 100,000 to 500,000.

[0064] For the chloroprene-based block copolymer of this embodiment, it is preferable that the breaking tensile strength measured according to JIS K 6251 after heat-treating the molded body of the latex composition containing the chloroprene-based block copolymer at 130°C for 30 minutes is 17 MPa or more. The breaking tensile strength is more preferably 18 MPa or more, more preferably 19 MPa or more, and further preferably 20 MPa or more. The upper limit is not particularly limited, for example, it is 30 MPa or less.

[0065] In addition, for the chloroprene-based block copolymer of the present embodiment, it is preferable that the elongation at break measured according to JIS K6251 after heat-treating the molded body of the latex composition containing the chloroprene-based block copolymer at 130°C for 30 minutes is 900% or more, more preferably 905% or more, and further preferably 910% or more. There is no particular limitation on the upper limit, for example, it is 1300% or less.

[0066] For the chloroprene-based block copolymer of the present embodiment, it is preferable that the 500% modulus of elongation measured according to JIS K 6251 after heat-treating the molded body of the latex composition containing the chloroprene-based block copolymer at 130°C for 30 minutes is 3.0 MPa or less, more preferably 2.9 MPa or less, and further preferably 2.8 MPa or less. There is no particular limitation on the lower limit, for example, it is 1.0 MPa or more.

[0067] For the chloroprene-based block copolymer of the present embodiment, it is preferable that the molded body composed of the latex composition containing the latex containing the chloroprene-based block copolymer and the rubber composition has the above-mentioned tensile strength, elongation at break, and 500% modulus of elongation after heat-treating at 130°C for 30 minutes. A vulcanizing agent and a vulcanization accelerator may not be used during molding. For measuring the tensile strength, the molded body can be obtained by the method described in the examples.

[0068] In order to adjust the tensile strength at break, elongation at break, and 500% modulus of elongation of the molded body of the latex composition containing the chloroprene-based block copolymer, it is only necessary to adjust the content of the polyfunctional monomer units contained in the chloroprene-based polymer block (B) or adjust the content of the polymer block (A) in the chloroprene-based block copolymer.

[0069] [Manufacturing method of chloroprene-based block copolymer]

[0070] The manufacturing method of the chloroprene-based block copolymer according to the present invention will be described. The polymerization method is not particularly limited, and known methods such as solution polymerization, emulsion polymerization, and bulk polymerization can be used, but emulsion polymerization is preferred in terms of obtaining the desired chloroprene-based block copolymer.

[0071] As long as the desired chloroprene-based block copolymer can be obtained, the polymerization method is not particularly limited, and it is preferably manufactured by a manufacturing method via two-step polymerization processes, that is, polymerization process 2 for synthesizing the chloroprene-based polymer block (B) is carried out after polymerization process 1 for synthesizing the polymer block (A).

[0072] (Polymerization process 1)

[0073] In polymerization step 1, the monomers constituting the polymer block (A) are subjected to living radical polymerization to synthesize the polymer block (A). As described above, the polymer block (A) obtained here preferably has the above-mentioned glass transition temperature. The emulsifier used in the polymerization is not particularly limited, and from the viewpoint of emulsion stability, an anionic or non-ionic emulsifier is preferred. In particular, for the reason of making the obtained chloroprene-based block copolymer have appropriate strength and preventing excessive shrinkage and breakage, a rosin acid metal salt is preferably used. From the viewpoint of effectively carrying out the polymerization reaction, the concentration of the emulsifier is preferably 5 to 50% by mass based on 100% by mass of the monomers constituting the polymer block (A). As the radical polymerization initiator, known radical polymerization initiators can be used, such as potassium persulfate, benzoyl peroxide, hydrogen peroxide, azo compounds, etc. The polymerization temperature can be appropriately determined according to the monomer type, and is preferably 10 to 100 °C, particularly preferably 20 to 80 °C.

[0074] (Polymerization step 2)

[0075] In polymerization step 2, chloroprene monomer and polyfunctional monomer are added to the latex containing the polymer block (A) obtained in the above polymerization step 1 for polymerization to obtain a latex containing the target chloroprene-based block copolymer. The chloroprene monomer and polyfunctional monomer can be added all at once or in batches. From the viewpoint of easy polymerization, the polymerization temperature in polymerization step 2 is preferably 10 to 50 °C. The polymerization reaction can be terminated by adding a polymerization terminator. As the polymerization terminator, for example, thiodiphenylamine, 4-tert-butylcatechol, 2,2'-methylenebis-4-methyl-6-tert-butylphenol, etc. can be used. The unreacted monomers after the polymerization can be removed by conventional methods such as vacuum distillation.

[0076] Within the scope not impairing the object of the present invention, a freezing stabilizer, an emulsion stabilizer, a viscosity modifier, an antioxidant, a preservative, etc. can be arbitrarily added to the latex containing the chloroprene-based block copolymer obtained in polymerization step 2 after the polymerization.

[0077] (Recovery step)

[0078] The method for recovering the chloroprene-based block copolymer from the latex containing the chloroprene-based block copolymer is not particularly limited, and known methods such as a method of recovering by impregnation in a coagulating liquid and a method of precipitating with a poor solvent such as methanol can be adopted.

[0079] The chloroprene-based block copolymer preferably has a functional group having a structure represented by the following chemical formula (2) or chemical formula (3).

[0080] [Chemical formula 5]

[0081]

[0082] (In Chemical Formula (2), R 3 represents any one of hydrogen, chlorine, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted aryl, substituted or unsubstituted mercapto group, and substituted or unsubstituted heterocyclic group.)

[0083]

Chemical Formula 6

[0084]

[0085] The terminal structure represented by the above chemical formula (2) or chemical formula (3) is introduced into the chloroprene-based block copolymer by polymerization in the presence of a known RAFT agent. The compound for introducing the structure represented by the above chemical formula (2) is not particularly limited, and ordinary compounds can be used. For example, dithiocarbamates and dithioesters can be mentioned. Specifically, benzyl-1-pyrrol dithiocarboxylate (common name: benzyl 1-pyrrol dithiocarbamate), benzyl phenyl dithiocarboxylate, 1-benzyl-N,N-dimethyl-4-aminodithiobenzoate, 1-benzyl-4-methoxydithiobenzoate, 1-phenylethyl imidazole dithiocarboxylate (common name: 1-phenylethyl imidazole dithiocarbamate), benzyl-1-(2-pyrrolidone) dithiocarboxylate) (common name: benzyl-1-(2-pyrrolidone) dithiocarbamate), benzyl phthalimido dithiocarboxylate (common name: benzyl phthalimido dithiocarbamate), 2-cyanopropyl-2-yl-1-pyrrol dithiocarboxylate (common name: 2-cyanopropyl-2-yl-1-pyrrol dithiocarbamate), 2-cyanobutyl-2-yl-1-pyrrol dithiocarboxylate (common name: 2-cyanobutyl-2-yl-1-pyrrol dithiocarbamate), benzyl-1-imidazole dithiocarboxylate (common name: benzyl-1-imidazole dithiocarbamate), 2-cyanopropyl-2-yl-N,N-dimethyldithiocarbamate, benzyl-N,N-diethyldithiocarbamate, cyanomethyl-1-(2-pyrrolidone) dithiocarbamate, 2-(ethoxycarbonylbenzyl)propyl-2-yl-N,N-diethyldithiocarbamate, 1-phenylethyl dithiobenzoate, 2-phenylpropyl-2-yl dithiobenzoate, 1-acetoxy-1-ethyl dithiobenzoate, 1-(4-methoxyphenyl)ethyl dithiobenzoate, benzyl dithioacetate, ethoxycarbonylmethyl dithioacetate, 2-(ethoxycarbonyl)propyl-2-yl dithiobenzoate, 2-cyanopropyl-2-yl dithiobenzoate, tert-butyl dithiobenzoate, 2,4,4-trimethylpent-2-yl dithiobenzoate, 2-(4-chlorophenyl)-propyl-2-yl dithiobenzoate, 3-vinylbenzyl dithiobenzoate, 4-vinylbenzyl dithiobenzoate, benzyl diethoxyphosphinyldithiocarboxylate, tert-butyl trithioperbenzoate, 2-phenylpropyl-2-yl-4-chlorodithiobenzoate, naphthalene-1-carboxylic acid-1-methyl-1-phenyl-ethyl ester, 4-cyano-4-methyl-4-thiobenzyl mercaptobutyric acid, dibenzyl tetrathioterephthalate, carboxymethyl dithiobenzoate, poly(ethylene oxide) having a dithiobenzoate terminal group, poly(ethylene oxide) having a 4-cyano-4-methyl-4-thiobenzyl mercaptobutyric acid terminal group, 2-[(2-phenylethane sulfonyl)mercapto]propanoic acid, 2-[(2-phenylethane sulfonyl)mercapto]succinic acid, 3,Potassium 5-dimethyl-1H-pyrazole-1-dithiocarboxylate, cyanomethyl 3,5-dimethyl-1H-pyrazole-1-dithiocarboxylate, cyanomethyl methyl(phenyl)dithiocarbamate, benzyl 4-chlorodithiobenzoate, phenylmethyl 4-chlorodithiobenzoate, 4-nitrobenzyl 4-chlorodithiobenzoate, phenylpropan-2-yl 4-chlorodithiobenzoate, 1-cyano-1-methylethyl 4-chlorodithiobenzoate, 3-chloro-2-butenyl 4-chlorodithiobenzoate, 2-chloro-2-butenyl dithiobenzoate, benzyl dithioacetate, 3-chloro-2-butenyl 1H-pyrrole-1-dithiocarboxylic acid, 2-cyanobutane-2-yl 4-chloro-3,5-dimethyl-1H-pyrazole-1-dithiocarboxylate, cyanomethyl methyl(phenyl)aminodithiocarbamate. Among them, benzyl 1-pyrrole dithiocarboxylate and benzyl phenyl dithiocarboxylate are particularly preferably used.,

[0086] There is no particular limitation on the compound for deriving the compound having the structure represented by the above chemical formula (3), and general compounds can be used. For example, 2-cyano-2-propyldodecyl trithiocarbonate, dibenzyl trithiocarbonate, butylbenzyl trithiocarbonate, 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′-[carbonylbis(thio)]bis[2-methylpropionic acid], 2-amino-1-methyl-2-oxoethyl butyl trithiocarbonate, benzyl 2-[(2-hydroxyethyl)amino]-1-methyl-2-oxoethyl trithiocarbonate, 3-[[[(tert-butyl)thio]thioxomethyl]thio]propionic acid, cyanomethyldodecyl trithiocarbonate, diethylaminobenzyl trithiocarbonate, dibutylaminobenzyl trithiocarbonate and other trithiocarbonates can be cited. Among them, dibenzyl trithiocarbonate and butylbenzyl trithiocarbonate are particularly preferably used.

[0087] <Latex>

[0088] The latex according to this embodiment is a latex containing the above chloroprene-based block copolymer. An impregnated molded article can be obtained by impregnating this latex into a coagulating liquid. The impregnated molded article can be applied to gloves, balloons, catheters, boots and the like.

[0089] The latex of the present embodiment can be obtained by directly using the liquid at the end of polymerization obtained by the polymerization method described in the manufacturing method of the above-mentioned chloroprene-based block copolymer as the latex; or by forcibly emulsifying the recovered chloroprene-based block copolymer with an emulsifier to obtain the latex, etc. Among them, the method of directly using the liquid at the end of polymerization obtained by polymerization as the latex can simply obtain the latex, so it is preferred.

[0090] <Latex composition · Rubber composition>

[0091] The latex composition according to the present embodiment contains a chloroprene-based block copolymer. In addition, the rubber composition according to the present embodiment is a rubber composition containing the above-mentioned chloroprene-based block copolymer. The raw materials other than the chloroprene-based block copolymer are not particularly limited and can be appropriately selected according to the purpose and use. Examples of the raw materials that can be contained in the latex composition · rubber composition containing the chloroprene-based block copolymer include a vulcanizing agent, a vulcanization accelerator, a filler or a reinforcing agent, a plasticizer, a processing aid or a lubricant, an anti-aging agent, a silane coupling agent, etc.

[0092] The latex composition · rubber composition of the present embodiment may contain a vulcanizing agent or a vulcanization accelerator. When the latex composition · rubber composition according to an embodiment of the present invention contains a vulcanizing agent and / or a vulcanization accelerator, when the latex composition · rubber composition is set to 100% by mass, the total content rate of the vulcanizing agent and the vulcanization accelerator can be 5% by mass or less, preferably 1% by mass or less, more preferably 0.1% by mass. However, the latex composition · rubber composition of the present embodiment can exhibit sufficient mechanical strength even without vulcanization. Therefore, from the viewpoints of reducing allergies and costs, it is preferred not to contain a vulcanizing agent and a vulcanization accelerator.

[0093] Antioxidants are used to improve the heat resistance of rubber compositions. There are primary antioxidants that prevent autooxidation by scavenging free radicals and secondary antioxidants that render hydroperoxides harmless. These antioxidants can be added in a proportion of 0.1 part by mass or more and 10 parts by mass or less, preferably in the range of 2 parts by mass or more and 5 parts by mass or less, relative to 100 parts by mass of the latex component in the latex composition / rubber composition. These antioxidants can be used alone or in combination of two or more. It should be noted that as primary antioxidants, phenolic antioxidants, amine antioxidants, acrylate antioxidants, imidazole antioxidants, metal carbamates, and waxes can be cited. In addition, as secondary antioxidants, phosphorus antioxidants, sulfur antioxidants, imidazole antioxidants, etc. can be cited. Examples of antioxidants are not particularly limited, and examples include N-phenyl-1-naphthylamine, alkylated diphenylamine, octylated diphenylamine, 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, p-(p-toluenesulfonamide)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-tert-butylphenyl)butane, 4,4'-butylidenebis(3-methyl-6-tert-butylphenol), 2,2-thiobis(4-methyl-6-tert-butylphenol), 7-octadecyl-3-(4'-hydroxy-3',5'-di-tert-butylphenyl)propionate, tetra-[methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane, pentaerythritol-tetra[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], triethylene glycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2,4-bis(n-octylthio)-6-(4-hydroxy-3,5-di-tert-butylanilino)-1,3,5-triazine, tris(3,5-di-tert-butyl-4-hydroxybenzyl)-isocyanurate, 2,2-thio-diethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxy)-hydrocinnamide, 2,4-bis[(octylthio)methyl]-o-cresol, 3,5-di-tert-butyl-4-hydroxybenzyl-phosphonate-diethyl ester, tetra[methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate)]methane, octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and 3,9-bis[2-{3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy}-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5.5] Undecane, tris(nonylphenyl) phosphite, tris(mixture of mono- and di-nonylphenyl) phosphite, diphenyl mono(2-ethylhexyl) phosphite, diphenyl monotridecyl phosphite, diphenyl isodecyl phosphite, diphenyl isooctyl phosphite, diphenyl nonylphenyl phosphite, triphenyl phosphite, tris(tridecyl) phosphite, trisisodecyl phosphite, tris(2-ethylhexyl) phosphite, tris(2,4-di-tert-butylphenyl) phosphite, tetraphenyldipropylene glycol diphosphite, tetraphenyltetrakis(tridecyl)pentaerythritol tetraphosphite, 1,1,3-tris(2-methyl-4-ditridecylphosphite-5-tert-butylphenyl)butane, 4,4'-butylidenebis(3-methyl-6-tert-butyl-ditridecylphosphite), 2,2'-ethylidenebis(4,6-di-tert-butylphenol) fluorophosphite, 4,4'-isopropylidenediphenol alkyl (C12-C15) phosphite, cyclic neopentanetetrayl bis(2,4-di-tert-butylphenylphosphite), cyclic neopentanetetrayl bis(2,6-di-tert-butyl-4-phenylphosphite), cyclic neopentanetetrayl bis(nonylphenylphosphite), bis(nonylphenyl)pentaerythritol diphosphite, dibutyl hydrogen phosphite, distearylpentaerythritol diphosphite and hydrogenated bisphenol A pentaerythritol phosphite polymer, 2-mercaptobenzimidazole, butylated reaction product of p-cresol and dicyclopentadiene, etc.

[0094] The above rubber composition can be produced by using known equipment or devices according to a conventional method.

[0095]

Examples

[0096] The following examples and comparative examples illustrate the present invention, but these are only examples and do not limit the content of the present invention.

[0097] (Example 1)

[0098] (Polymerization step 1) Synthesis of polymer block (A-1)

[0099] Polymerization was carried out using an autoclave with a capacity of 10 L equipped with a stirrer and a jacket for heating and cooling. 4666 g of pure water, 224 g of potassium disproportionated rosin (manufactured by Harima Chemicals Group, Inc.), 36.4 g of potassium hydroxide, 18.7 g of sodium salt of β-naphthalene sulfonic acid formaldehyde condensate (manufactured by Kao Corporation, trade name: Demol N), 350 g of styrene monomer, and 6.07 g of butyl benzyl trithiocarbonate were charged, and the internal temperature was set to 80 °C, and stirring was carried out at 200 rpm under a nitrogen stream. 3.82 g of 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (manufactured by Fujifilm Wako Pure Chemical Corporation, trade name: VA-044), which is a polymerization initiator, was added to initiate polymerization. 20 ml of the obtained latex was sampled to measure physical properties, and the remaining latex was used for Polymerization Step 2.

[0100] The sampled latex was mixed with a large amount of methanol to precipitate the resin component, and the sample of polymer block (A-1) was obtained by filtration and drying. The number average molecular weight, molecular weight distribution, and glass transition temperature of polymer block (A) were determined by analyzing the obtained sample. The analysis results are shown in Table 1. It should be noted that the measurement methods for "number average molecular weight", "molecular weight distribution", and "glass transition temperature" will be described below.

[0101] (Polymerization Step 2) Synthesis of chloroprene-based polymer block (B-1)

[0102] After Polymerization Step 1, when the internal temperature dropped to 45 °C, 4480 g of chloroprene monomer and 91.4 g of 1,9-nonanediol dimethacrylate were slowly added over 2 hours for polymerization. When the polymerization rate of the chloroprene monomer reached 80%, a polymerization terminator, a 10 wt% aqueous solution of N,N-diethylhydroxylamine, was added to terminate the polymerization, and the unreacted chloroprene monomer was removed by vacuum distillation. 20 ml of the obtained latex was sampled to measure physical properties, and the remaining latex was used to prepare an evaluation film.

[0103] The sampled latex was mixed with a large amount of methanol to precipitate the resin component, and the sample of the chloroprene-based block copolymer was obtained by filtration and drying. The contents (mass%) of polymer block (A-1) and chloroprene-based polymer block (B-1) in the chloroprene-based block copolymer were determined by analyzing the obtained sample. The analysis results are shown in Table 1. It should be noted that the measurement method will be described below.

[0104] (Example 2)

[0105] (Polymerization Step 1) Synthesis of polymer block (A-2)

[0106] Polymerization was carried out in an autoclave with a use capacity of 10 L equipped with a stirrer and a jacket for heating and cooling. 3333 g of pure water, 160 g of potassium disproportionated rosin (manufactured by Harima Chemicals Group, Inc.), 26.0 g of potassium hydroxide, 13.3 g of sodium salt of β-naphthalene sulfonic acid formaldehyde condensate (manufactured by Kao Corporation, trade name: Demol N), 250 g of styrene monomer, and 4.33 g of butyl benzyl trithiocarbonate were charged, and the internal temperature was set to 80 °C, and stirring was carried out at 200 rpm under a nitrogen stream. 2.73 g of 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (manufactured by Fujifilm Wako Pure Chemical Corporation, trade name: VA-044), which is a polymerization initiator, was added to initiate polymerization. 20 ml was sampled from the obtained latex to measure physical properties, and the remaining latex was used for polymerization step 2. The number average molecular weight, molecular weight distribution, and glass transition temperature of the polymer block (A-2) were determined by analysis in the same manner as in Example 1. The analysis results are shown in Table 1.

[0107] (Polymerization step 2) Synthesis of chloroprene-based polymer block (B-2)

[0108] After polymerization step 1, when the internal temperature dropped to 45 °C, 5584 g of chloroprene monomer and 114.0 g of 1,9-nonanediol dimethacrylate were slowly added over 2 hours for polymerization. When the polymerization rate of the chloroprene monomer reached 80%, a polymerization terminator, a 10 wt% aqueous solution of N,N-diethylhydroxylamine, was added to terminate the polymerization, and the unreacted chloroprene monomer was removed by vacuum distillation. 20 ml was sampled from the obtained latex to measure physical properties, and an evaluation film was prepared using the remaining latex. The contents (mass%) of the polymer block (A-2) and the chloroprene-based polymer block (B-2) of the chloroprene-based block copolymer were determined by analysis in the same manner as in Example 1. The analysis results are shown in Table 1.

[0109] (Example 3)

[0110] (Polymerization step 1) Synthesis of polymer block (A-3)

[0111] Polymerization was carried out in an autoclave with a use capacity of 10 L equipped with a stirrer and a jacket for heating and cooling. 5733 g of pure water, 275 g of potassium disproportionated rosin (manufactured by Harima Chemicals Group, Inc.), 44.7 g of potassium hydroxide, 22.9 g of sodium salt of β-naphthalene sulfonic acid formaldehyde condensate (manufactured by Kao Corporation, trade name: Demol N), 430 g of styrene monomer, and 7.45 g of butyl benzyl trithiocarbonate were charged, and the internal temperature was adjusted to 80 °C, and stirring was carried out at 200 rpm under a nitrogen stream. 4.69 g of 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (manufactured by Fujifilm Wako Pure Chemical Corporation, trade name: VA-044), which is a polymerization initiator, was added to initiate polymerization. 20 ml was sampled from the obtained latex to measure physical properties, and the remaining latex was used for polymerization step 2. The number average molecular weight, molecular weight distribution, and glass transition temperature of the polymer block (A-3) were determined by analysis in the same manner as in Example 1. The analysis results are shown in Table 1.

[0112] (Polymerization step 2) Synthesis of chloroprene-based polymer block (B-3)

[0113] After polymerization step 1, when the internal temperature dropped to 45 °C, 3094 g of chloroprene monomer and 63.1 g of 1,9-nonanediol dimethacrylate were slowly added over 2 hours for polymerization. When the polymerization rate of the chloroprene monomer reached 80%, a polymerization terminator, a 10 wt% aqueous solution of N,N-diethylhydroxylamine, was added to terminate the polymerization, and the unreacted chloroprene monomer was removed by vacuum distillation. 20 ml was sampled from the obtained latex to measure physical properties, and an evaluation film was prepared using the remaining latex. The contents (mass %) of the polymer block (A-3) and the chloroprene-based polymer block (B-3) of the chloroprene-based block copolymer were determined by analysis in the same manner as in Example 1. The analysis results are shown in Table 1.

[0114] (Example 4)

[0115] (Polymerization step 1) Synthesis of polymer block (A-4)

[0116] Polymerization was carried out using an autoclave with a capacity of 10 L equipped with a stirrer and a jacket for heating and cooling. 4666 g of pure water, 224 g of potassium disproportionated rosin (manufactured by Harima Chemicals Group, Inc.), 36.4 g of potassium hydroxide, 18.7 g of sodium salt of β-naphthalene sulfonic acid formaldehyde condensate (manufactured by Kao Corporation, trade name: Demol N), 350 g of styrene monomer, and 6.07 g of butyl benzyl trithiocarbonate were charged, and the internal temperature was set to 80 °C, and stirring was carried out at 200 rpm under a nitrogen stream. 3.82 g of 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (manufactured by Fujifilm Wako Pure Chemical Corporation, trade name: VA-044), which is a polymerization initiator, was added to initiate polymerization. 20 ml was sampled from the obtained latex to measure physical properties, and the remaining latex was used for Polymerization Step 2. The number average molecular weight, molecular weight distribution, and glass transition temperature of the polymer block (A-4) were determined by analysis in the same manner as in Example 1. The analysis results are shown in Table 1.

[0117] (Polymerization Step 2) Synthesis of chloroprene-based polymer block (B-4)

[0118] After Polymerization Step 1, when the internal temperature dropped to 45 °C, 4480 g of chloroprene monomer and 91.4 g of 1,9-nonanediol diacrylate (LIGHT ACRYLATE 1.9ND-A (manufactured by Kyoeisha Chemical Co., Ltd.)) were slowly added over 2 hours for polymerization. When the polymerization rate of the chloroprene monomer reached 80%, a polymerization terminator, a 10 wt% aqueous solution of N,N-diethylhydroxylamine, was added to terminate the polymerization, and the unreacted chloroprene monomer was removed by vacuum distillation. 20 ml was sampled from the obtained latex to measure physical properties, and an evaluation film was prepared using the remaining latex. The contents (mass %) of the polymer block (A-4) and the chloroprene-based polymer block (B-4) of the chloroprene-based block copolymer were determined by analysis in the same manner as in Example 1. The analysis results are shown in Table 1.

[0119] (Example 5)

[0120] (Polymerization Step 1) Synthesis of polymer block (A-5)

[0121] Polymerization was carried out using an autoclave with a capacity of 10 L equipped with a stirrer and a jacket for heating and cooling. 4666 g of pure water, 224 g of potassium disproportionated rosin (manufactured by Harima Chemicals Group, Inc.), 36.4 g of potassium hydroxide, 18.7 g of sodium salt of β-naphthalene sulfonic acid formaldehyde condensate (manufactured by Kao Corporation, trade name: Demol N), 350 g of styrene monomer, and 6.07 g of butyl benzyl trithiocarbonate were charged. The internal temperature was set at 80 °C, and stirring was carried out at 200 rpm under a nitrogen stream. 3.82 g of 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (manufactured by Fujifilm Wako Pure Chemical Corporation, trade name: VA-044), used as a polymerization initiator, was added to initiate polymerization. 20 ml was sampled from the resulting latex to measure physical properties, and the remaining latex was used for polymerization step 2. The number average molecular weight, molecular weight distribution, and glass transition temperature of the polymer block (A-5) were determined by analysis in the same manner as in Example 1. The analysis results are shown in Table 1.

[0122] (Polymerization step 2) Synthesis of chloroprene-based polymer block (B-5)

[0123] After polymerization step 1, when the internal temperature dropped to 45 °C, 4480 g of chloroprene monomer and 91.4 g of Light Ester EG (manufactured by Kyoeisha Chemical Co., Ltd.), used as ethylene glycol dimethacrylate, were slowly added over 2 hours for polymerization. When the polymerization rate of the chloroprene monomer reached 80%, a polymerization terminator, a 10 wt% aqueous solution of N,N-diethylhydroxylamine, was added to terminate the polymerization, and the unreacted chloroprene monomer was removed by vacuum distillation. 20 ml was sampled from the resulting latex to measure physical properties, and an evaluation film was prepared using the remaining latex. The contents (mass%) of the polymer block (A-5) and the chloroprene-based polymer block (B-5) in the chloroprene-based block copolymer were determined by analysis in the same manner as in Example 1. The analysis results are shown in Table 1.

[0124] (Example 6)

[0125] (Polymerization step 1) Synthesis of polymer block (A-6)

[0126] Polymerization was carried out in an autoclave with a capacity of 10 L equipped with a stirrer and a jacket for heating and cooling. 4666 g of pure water, 224 g of potassium disproportionated rosin (manufactured by Harima Chemicals Group, Inc.), 36.4 g of potassium hydroxide, 18.7 g of sodium salt of β-naphthalene sulfonic acid formaldehyde condensate (manufactured by Kao Corporation, trade name: Demol N), 350 g of styrene monomer, and 6.07 g of butyl benzyl trithiocarbonate were charged, and the internal temperature was set to 80 °C, and stirring was carried out at 200 rpm under a nitrogen stream. 3.82 g of 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (manufactured by Fujifilm Wako Pure Chemical Corporation, trade name: VA-044), which is a polymerization initiator, was added to initiate polymerization. 20 ml was sampled from the obtained latex to measure physical properties, and the remaining latex was used for polymerization step 2. The number average molecular weight, molecular weight distribution, and glass transition temperature of the polymer block (A-6) were determined by analysis in the same manner as in Example 1. The analysis results are shown in Table 1.

[0127] (Polymerization step 2) Synthesis of chloroprene-based polymer block (B-6)

[0128] After polymerization step 1, when the internal temperature dropped to 45 °C, 4480 g of chloroprene monomer and 93.3 g of divinylbenzene were slowly added over 2 hours for polymerization. When the polymerization rate of the chloroprene monomer reached 80%, a polymerization terminator, a 10 wt% aqueous solution of N,N-diethylhydroxylamine, was added to terminate the polymerization, and the unreacted chloroprene monomer was removed by vacuum distillation. 20 ml was sampled from the obtained latex to measure physical properties, and an evaluation film was prepared using the remaining latex. The contents (mass%) of the polymer block (A-6) and the chloroprene-based polymer block (B-6) of the chloroprene-based block copolymer were determined by analysis in the same manner as in Example 1. The analysis results are shown in Table 1.

[0129] (Example 7)

[0130] (Polymerization step 1) Synthesis of polymer block (A-7)

[0131] Polymerization was carried out in an autoclave with a capacity of 10 L equipped with a stirrer and a jacket for heating and cooling. 4666 g of pure water, 224 g of potassium disproportionated rosin (manufactured by Harima Chemicals Group, Inc.), 36.4 g of potassium hydroxide, 18.7 g of sodium salt of β-naphthalene sulfonic acid formaldehyde condensate (manufactured by Kao Corporation, trade name: Demol N), 350 g of styrene monomer, and 6.07 g of butyl benzyl trithiocarbonate were charged. The internal temperature was set to 80 °C, and stirring was carried out at 200 rpm under a nitrogen stream. 3.82 g of 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (manufactured by Fujifilm Wako Pure Chemical Corporation, trade name: VA-044), which is a polymerization initiator, was added to initiate polymerization. 20 ml of the obtained latex was sampled to measure physical properties, and the remaining latex was used for polymerization step 2. The number average molecular weight, molecular weight distribution, and glass transition temperature of the polymer block (A-7) were determined by analysis in the same manner as in Example 1. The analysis results are shown in Table 1.

[0132] (Polymerization step 2) Synthesis of chloroprene-based polymer block (B-7)

[0133] After polymerization step 1, when the internal temperature dropped to 45 °C, 4480 g of chloroprene monomer and 91.4 g of triallyl isocyanurate were slowly added over 2 hours for polymerization. At the moment when the polymerization rate of the chloroprene monomer reached 80%, a polymerization terminator, a 10 wt% aqueous solution of N,N-diethylhydroxylamine, was added to terminate the polymerization, and the unreacted chloroprene monomer was removed by vacuum distillation. 20 ml of the obtained latex was sampled to measure physical properties, and an evaluation film was prepared using the remaining latex. The contents (mass%) of the polymer block (A-7) and the chloroprene-based polymer block (B-7) in the chloroprene-based block copolymer were determined by analysis in the same manner as in Example 1. The analysis results are shown in Table 1.

[0134] (Example 8)

[0135] (Polymerization step 1) Synthesis of polymer block (A-8)

[0136] Polymerization was carried out in an autoclave with a capacity of 10 L equipped with a stirrer and a jacket for heating and cooling. 4666 g of pure water, 224 g of potassium disproportionated rosin (manufactured by Harima Chemicals Group, Inc.), 36.4 g of potassium hydroxide, 18.7 g of sodium salt of β-naphthalene sulfonic acid formaldehyde condensate (manufactured by Kao Corporation, trade name: Demol N), 350 g of styrene monomer, and 6.07 g of butyl benzyl trithiocarbonate were charged. The internal temperature was set to 80 °C, and stirring was carried out at 200 rpm under a nitrogen stream. 3.82 g of 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (manufactured by Fujifilm Wako Pure Chemical Corporation, trade name: VA-044), which is a polymerization initiator, was added to initiate polymerization. 20 ml of the resulting latex was sampled to measure physical properties, and the remaining latex was used for Polymerization Step 2. The number-average molecular weight, molecular weight distribution, and glass transition temperature of the polymer block (A-8) were determined by analysis in the same manner as in Example 1. The analysis results are shown in Table 1.

[0137] (Polymerization Step 2) Synthesis of chloroprene-based polymer block (B-8)

[0138] After Polymerization Step 1, when the internal temperature dropped to 45 °C, 4480 g of chloroprene monomer and 91.4 g of hydroxypivalic acid neopentyl glycol acrylate adduct (manufactured by Kyoeisha Chemical Co., Ltd., trade name: LIGHT ACRYLATE HPP-A) were slowly added over 2 hours for polymerization. At the moment when the polymerization rate of the chloroprene monomer reached 80%, polymerization was terminated by adding a polymerization terminator, a 10 wt% aqueous solution of N,N-diethylhydroxylamine, and the unreacted chloroprene monomer was removed by vacuum distillation. 20 ml of the resulting latex was sampled to measure physical properties, and an evaluation film was prepared using the remaining latex. The contents (mass%) of the polymer block (A-8) and the chloroprene-based polymer block (B-8) of the chloroprene-based block copolymer were determined by analysis in the same manner as in Example 1. The analysis results are shown in Table 1.

[0139] (Example 9)

[0140] (Polymerization Step 1) Synthesis of polymer block (A-9)

[0141] Polymerization was carried out in an autoclave with a use capacity of 10 L equipped with a stirrer and a jacket for heating and cooling. 4666 g of pure water, 224 g of potassium disproportionated rosin (manufactured by Harima Chemicals Group, Inc.), 36.4 g of potassium hydroxide, 18.7 g of sodium salt of β-naphthalene sulfonic acid formaldehyde condensate (manufactured by Kao Corporation, trade name: Demol N), 350 g of styrene monomer, and 6.07 g of butyl benzyl trithiocarbonate were charged. The internal temperature was set to 80 °C, and stirring was carried out at 200 rpm under a nitrogen stream. 3.82 g of 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (manufactured by Fujifilm Wako Pure Chemical Corporation, trade name: VA-044), which is a polymerization initiator, was added to initiate polymerization. 20 ml was sampled from the obtained latex to measure physical properties, and the remaining latex was used for Polymerization Step 2. The number average molecular weight, molecular weight distribution, and glass transition temperature of the polymer block (A-9) were determined by analysis in the same manner as in Example 1. The analysis results are shown in Table 1.

[0142] (Polymerization Step 2) Synthesis of chloroprene-based polymer block (B-9)

[0143] After Polymerization Step 1, when the internal temperature dropped to 45 °C, 4480 g of chloroprene monomer and 91.4 g of trimethylolpropane triacrylate (manufactured by Kyoeisha Chemical Co., Ltd.) were slowly added over 2 hours for polymerization. When the polymerization rate of the chloroprene monomer reached 80%, a polymerization terminator, a 10 wt% aqueous solution of N,N-diethylhydroxylamine, was added to terminate the polymerization, and the unreacted chloroprene monomer was removed by vacuum distillation. 20 ml was sampled from the obtained latex to measure physical properties, and an evaluation film was prepared using the remaining latex. The contents (mass %) of the polymer block (A-9) and the chloroprene-based polymer block (B-9) in the chloroprene-based block copolymer were determined by analysis in the same manner as in Example 1. The analysis results are shown in Table 1.

[0144] (Example 10)

[0145] (Polymerization Step 1) Synthesis of polymer block (A-10)

[0146] Polymerization was carried out in an autoclave with a capacity of 10 L equipped with a stirrer and a jacket for heating and cooling. 6667 g of pure water, 320 g of potassium disproportionated rosin (manufactured by Harima Chemicals Group, Inc.), 52.0 g of potassium hydroxide, 26.7 g of sodium salt of β-naphthalene sulfonic acid formaldehyde condensate (manufactured by Kao Corporation, trade name: Demol N), 500 g of styrene monomer, and 6.50 g of butyl benzyl trithiocarbonate were charged, and the internal temperature was set to 80 °C, and stirring was carried out at 200 rpm under a nitrogen stream. 4.09 g of 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (manufactured by Fujifilm Wako Pure Chemical Corporation, trade name: VA-044), which is a polymerization initiator, was added to initiate polymerization. 20 ml was sampled from the obtained latex to measure physical properties, and the remaining latex was used for Polymerization Step 2. The number average molecular weight, molecular weight distribution, and glass transition temperature of the polymer block (A-10) were determined by analysis in the same manner as in Example 1. The analysis results are shown in Table 1.

[0147] (Polymerization Step 2) Synthesis of chloroprene-based polymer block (B-10)

[0148] After Polymerization Step 1, when the internal temperature dropped to 45 °C, 1607 g of chloroprene monomer and 32.8 g of 1,9-nonanediol dimethacrylate were slowly added over 2 hours for polymerization. When the polymerization rate of the chloroprene monomer reached 80%, a polymerization terminator, a 10 wt% aqueous solution of N,N-diethylhydroxylamine, was added to terminate the polymerization, and the unreacted chloroprene monomer was removed by vacuum distillation. 20 ml was sampled from the obtained latex to measure physical properties, and an evaluation film was prepared using the remaining latex. The contents (mass %) of the polymer block (A-10) and the chloroprene-based polymer block (B-10) of the chloroprene-based block copolymer were determined by analysis in the same manner as in Example 1. The analysis results are shown in Table 1.

[0149] (Example 11)

[0150] (Polymerization Step 1) Synthesis of polymer block (A-11)

[0151] Polymerization was carried out in an autoclave with a capacity of 10 L equipped with a stirrer and a jacket for heating and cooling. 4666 g of pure water, 224 g of potassium disproportionated rosin (manufactured by Harima Chemicals Group, Inc.), 36.4 g of potassium hydroxide, 18.7 g of sodium salt of β-naphthalene sulfonic acid formaldehyde condensate (manufactured by Kao Corporation, trade name: Demol N), 350 g of methyl methacrylate monomer, and 4.14 g of butyl-2-cyanopropyl trithiocarbonate were charged, and the internal temperature was set at 80 °C, and stirring was carried out at 200 rpm under a nitrogen stream. 2.87 g of 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (manufactured by Fujifilm Wako Pure Chemical Corporation, trade name: VA-044), which is a polymerization initiator, was added to initiate polymerization. 20 ml was sampled from the obtained latex to measure physical properties, and the remaining latex was used for polymerization step 2. The number average molecular weight, molecular weight distribution, and glass transition temperature of the polymer block (A-11) were determined by analysis in the same manner as in Example 1. The analysis results are shown in Table 1.

[0152] (Polymerization step 2) Synthesis of chloroprene-based polymer block (B-11)

[0153] After polymerization step 1, when the internal temperature dropped to 45 °C, 4424 g of chloroprene monomer and 90.3 g of 1,9-nonanediol dimethacrylate were slowly added over 2 hours for polymerization. When the polymerization rate of the chloroprene monomer reached 80%, a polymerization terminator, a 10 wt% aqueous solution of N,N-diethylhydroxylamine, was added to terminate the polymerization, and the unreacted chloroprene monomer was removed by vacuum distillation. 20 ml was sampled from the obtained latex to measure physical properties, and an evaluation film was prepared using the remaining latex. The contents (mass%) of the polymer block (A-11) and the chloroprene-based polymer block (B-11) of the chloroprene-based block copolymer were determined by analysis in the same manner as in Example 1. The analysis results are shown in Table 1.

[0154] (Example 12)

[0155] (Polymerization step 1) Synthesis of polymer block (A-12)

[0156] Polymerization was carried out in an autoclave with a use capacity of 10 L equipped with a stirrer and a jacket for heating and cooling. 4666 g of pure water, 224 g of potassium disproportionated rosin (manufactured by Harima Chemicals Group, Inc.), 36.4 g of potassium hydroxide, 18.7 g of sodium salt of β-naphthalene sulfonic acid formaldehyde condensate (manufactured by Kao Corporation, trade name: Demol N), 350 g of styrene monomer, and 6.07 g of butyl benzyl trithiocarbonate were charged, and the internal temperature was set to 80 °C, and stirring was carried out at 200 rpm under a nitrogen stream. 3.82 g of 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (manufactured by Fujifilm Wako Pure Chemical Corporation, trade name: VA-044), which is a polymerization initiator, was added to initiate polymerization. 20 ml was sampled from the obtained latex to measure physical properties, and the remaining latex was used for polymerization step 2. The number average molecular weight, molecular weight distribution, and glass transition temperature of the polymer block (A-12) were determined by analysis in the same manner as in Example 1. The analysis results are shown in Table 1.

[0157] (Polymerization Step 2) Synthesis of Chloroprene-based Polymer Block (B-12)

[0158] After polymerization step 1, when the internal temperature dropped to 45 °C, 4480 g of chloroprene monomer and 91.4 g of N,N'-diallyl-4,7,10-trioxa-1,13-tridecanediamine were slowly added over 2 hours for polymerization. When the polymerization rate of the chloroprene monomer reached 80%, a polymerization terminator, a 10 wt% aqueous solution of N,N-diethylhydroxylamine, was added to terminate the polymerization, and the unreacted chloroprene monomer was removed by vacuum distillation. 20 ml was sampled from the obtained latex to measure physical properties, and an evaluation film was prepared using the remaining latex. The contents (mass %) of the polymer block (A-12) and the chloroprene-based polymer block (B-12) of the chloroprene-based block copolymer were determined by analysis in the same manner as in Example 1. The analysis results are shown in Table 1.

[0159] (Comparative Example 1)

[0160] (Polymerization Step 1) Synthesis of Polymer Block (A-13)

[0161] Polymerization was carried out using an autoclave with a capacity of 10 L equipped with a stirrer and a jacket for heating and cooling. 3067 g of pure water, 147 g of potassium disproportionated rosin (manufactured by Harima Chemicals Group, Inc.), 23.9 g of potassium hydroxide, 12.3 g of sodium salt of β-naphthalene sulfonic acid formaldehyde condensate (manufactured by Kao Corporation, trade name: Demol N), 230 g of styrene monomer, and 3.99 g of butyl benzyl trithiocarbonate were charged. The internal temperature was set to 80 °C, and stirring was carried out at 200 rpm under a nitrogen stream. 2.51 g of 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (manufactured by Fujifilm Wako Pure Chemical Corporation, trade name: VA-044), which is a polymerization initiator, was added to initiate polymerization. 20 ml of the obtained latex was sampled to measure physical properties, and the remaining latex was used for Polymerization Step 2 in the same manner as in Example 1. The number-average molecular weight, molecular weight distribution, and glass transition temperature of the polymer block (A-13) were determined. The analysis results are shown in Table 1.

[0162] (Polymerization Step 2) Synthesis of chloroprene-based polymer block (B-13)

[0163] After Polymerization Step 1, when the internal temperature dropped to 45 °C, 7278 g of chloroprene monomer and 148.5 g of 1,9-nonanediol dimethacrylate were slowly added over 2 hours for polymerization. When the polymerization rate of the chloroprene monomer reached 80%, a polymerization terminator, a 10 wt% aqueous solution of N,N-diethylhydroxylamine, was added to terminate the polymerization, and the unreacted chloroprene monomer was removed by vacuum distillation. 20 ml of the obtained latex was sampled to measure physical properties, and an evaluation film was prepared using the remaining latex. The contents (mass%) of the polymer block (A-13) and the chloroprene-based polymer block (B-13) in the chloroprene-based block copolymer were determined in the same manner as in Example 1. The analysis results are shown in Table 1.

[0164] (Comparative Example 2)

[0165] (Polymerization Step 1) Synthesis of polymer block (A-14)

[0166] Polymerization was carried out in an autoclave with a capacity of 10 L equipped with a stirrer and a jacket for heating and cooling. 6667 g of pure water, 320 g of potassium disproportionated rosin (manufactured by Harima Chemicals Group, Inc.), 52.0 g of potassium hydroxide, 26.7 g of sodium salt of β-naphthalene sulfonic acid formaldehyde condensate (manufactured by Kao Corporation, trade name: Demol N), 500 g of styrene monomer, and 4.27 g of butyl benzyl trithiocarbonate were charged, and the internal temperature was set to 80 °C, and stirring was carried out at 200 rpm under a nitrogen stream. 2.69 g of 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (manufactured by Fujifilm Wako Pure Chemical Corporation, trade name: VA-044), which is a polymerization initiator, was added to initiate polymerization. 20 ml was sampled from the obtained latex to measure physical properties, and the remaining latex was used for polymerization step 2. The number average molecular weight, molecular weight distribution, and glass transition temperature of the polymer block (A-14) were determined by analysis in the same manner as in Example 1. The analysis results are shown in Table 1.

[0167] (Polymerization step 2) Synthesis of chloroprene-based polymer block (B-14)

[0168] After polymerization step 1, when the internal temperature dropped to 45 °C, 1607 g of chloroprene monomer and 32.8 g of 1,9-nonanediol dimethacrylate were slowly added over 2 hours for polymerization. When the polymerization rate of the chloroprene monomer reached 80%, a polymerization terminator, a 10 wt% aqueous solution of N,N-diethylhydroxylamine, was added to terminate the polymerization, and the unreacted chloroprene monomer was removed by vacuum distillation. 20 ml was sampled from the obtained latex to measure physical properties, and an evaluation film was prepared using the remaining latex. The contents (mass %) of the polymer block (A-14) and the chloroprene-based polymer block (B-14) of the chloroprene-based block copolymer were determined by analysis in the same manner as in Example 1. The analysis results are shown in Table 1.

[0169] (Comparative Example 3)

[0170] Synthesis of copolymer of only chloroprene-based polymer block (B-15)

[0171] Polymerization was carried out in a 10 L autoclave equipped with a stirrer and a jacket for heating and cooling. 3600 g of pure water, 175 g of potassium disproportionated rosin (manufactured by Harima Chemicals Group, Inc.), 28.4 g of potassium hydroxide, 16.0 g of sodium salt of β-naphthalene sulfonic acid formaldehyde condensate (manufactured by Kao Corporation, trade name: Demol N), 4000 g of chloroprene monomer, 81.6 g of 1,9-nonanediol dimethacrylate, and 4.72 g of butyl benzyl trithiocarbonate were charged. The internal temperature was set at 45 °C, and stirring was carried out at 200 rpm under a nitrogen stream. 2.96 g of 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (manufactured by Fujifilm Wako Pure Chemical Corporation, trade name: VA-044), used as a polymerization initiator, was added to initiate polymerization. At the moment when the polymerization rate of the chloroprene monomer reached 80%, a polymerization terminator, a 10 wt% aqueous solution of N,N-diethylhydroxylamine, was added to terminate the polymerization, and the unreacted chloroprene monomer was removed by vacuum distillation. 20 ml was sampled from the resulting latex to measure physical properties, and the remaining latex was used to prepare an evaluation film.

[0172] (Comparative Example 4)

[0173] (Polymerization Step 1) Synthesis of Polymer Block (A-16)

[0174] Polymerization was carried out in a 10 L autoclave equipped with a stirrer and a jacket for heating and cooling. 4616 g of pure water, 206 g of potassium disproportionated rosin (manufactured by Harima Chemicals Group, Inc.), 2.3 g of potassium hydroxide, 46.2 g of sodium salt of β-naphthalene sulfonic acid formaldehyde condensate (manufactured by Kao Corporation, trade name: Demol N), 462 g of styrene monomer, and 9.2 g of butyl benzyl trithiocarbonate were charged. The internal temperature was set at 80 °C, and stirring was carried out at 200 rpm under a nitrogen stream. 6.0 g of 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (manufactured by Fujifilm Wako Pure Chemical Corporation, trade name: VA-044), used as a polymerization initiator, was added to initiate polymerization. 20 ml was sampled from the resulting latex to measure physical properties, and the remaining latex was used for Polymerization Step 2. The number-average molecular weight, molecular weight distribution, and glass transition temperature of the polymer block (A-16) were determined by analysis in the same manner as in Example 1. The analysis results are shown in Table 1.

[0175] (Polymerization Step 2) Synthesis of Chloroprene-based Polymer Block (B-16)

[0176] After the polymerization step 1, when the internal temperature drops to 45 °C, 4154 g of chloroprene monomer is slowly added over 2 hours for polymerization. At the moment when the polymerization rate of the chloroprene monomer reaches 80%, a 10 wt% aqueous solution of the polymerization terminator N,N - diethylhydroxylamine is added to terminate the polymerization, and the unreacted chloroprene monomer is removed by vacuum distillation. 20 ml is sampled from the obtained latex to measure physical properties, and the remaining latex is used to prepare an evaluation film. In the same manner as in Example 1, the contents (mass %) of the polymer block (A - 16) and the chloroprene - based polymer block (B - 16) of the chloroprene - based block copolymer are determined by analysis. The analysis results are shown in Table 1.

[0177] (Comparative Example 5)

[0178] (Polymerization step 1) Synthesis of polymer block (A - 17)

[0179] Polymerization is carried out using a 10 L autoclave equipped with a stirrer and a heating - cooling jacket. 4616 g of pure water, 206 g of potassium disproportionated rosin (manufactured by Harima Chemicals Group, Inc.), 2.3 g of potassium hydroxide, 46.2 g of sodium salt of β - naphthalene sulfonic acid formaldehyde condensate (manufactured by Kao Corporation, trade name: Demol N), 692 g of styrene monomer, and 9.2 g of butyl benzyl trithiocarbonate are charged, the internal temperature is set to 80 °C, and stirring is carried out at 200 rpm under a nitrogen stream. 6.0 g of 2,2’ - azobis[2 - (2 - imidazolin - 2 - yl)propane] dihydrochloride (manufactured by Fujifilm Wako Pure Chemical Corporation, trade name: VA - 044), which is a polymerization initiator, is added to initiate polymerization. 20 ml is sampled from the obtained latex to measure physical properties, and the remaining latex is used for the polymerization step 2. In the same manner as in Example 1, the number - average molecular weight, molecular weight distribution, and glass transition temperature of the polymer block (A - 17) are determined by analysis. The analysis results are shown in Table 1.

[0180] (Polymerization step 2) Synthesis of chloroprene - based polymer block (B - 17)

[0181] After the polymerization step 1, when the internal temperature drops to 45 °C, 3924 g of chloroprene monomer is slowly added over 2 hours for polymerization. At the moment when the polymerization rate of the chloroprene monomer reaches 80%, a 10 wt% aqueous solution of the polymerization terminator N,N - diethylhydroxylamine is added to terminate the polymerization, and the unreacted chloroprene monomer is removed by vacuum distillation. 20 ml is sampled from the obtained latex to measure physical properties, and the remaining latex is used to prepare an evaluation film. In the same manner as in Example 1, the contents (mass %) of the polymer block (A - 17) and the chloroprene - based polymer block (B - 17) of the chloroprene - based block copolymer are determined by analysis. The analysis results are shown in Table 1.

[0182] (Comparative Example 6)

[0183] Synthesis of Triblock Copolymer

[0184] (Synthesis of the First Block)

[0185] Polymerization was carried out in a 10 L autoclave equipped with a stirrer and a heating / cooling jacket. 4613 g of pure water, 204.4 g of potassium disproportionated rosin (manufactured by Harima Chemicals Group, Inc.), 2.3 g of potassium hydroxide, 46.1 g of sodium salt of β-naphthalene sulfonic acid formaldehyde condensate (manufactured by Kao Corporation, trade name: Demol N), 230 g of styrene monomer, and 9.2 g of benzyl-1-pyrrolidinedithiocarboxylate were charged, and the internal temperature was set to 80 °C, and stirred at 200 rpm under a nitrogen stream. 6.0 g of 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (manufactured by Fujifilm Wako Pure Chemical Corporation, trade name: VA-044), which is a polymerization initiator, was added to initiate polymerization. 20 ml of the resulting latex was sampled to measure physical properties, and the remaining latex was used for the subsequent polymerization process. The number average molecular weight, molecular weight distribution, and glass transition temperature of the first block were determined by analysis in the same manner as in Example 1. The analysis results are shown in Table 2.

[0186] (Synthesis of the Second Block)

[0187] After the synthesis of the first block, when the internal temperature dropped to 45 °C, 4424 g of chloroprene monomer was added for polymerization. At the moment when the polymerization rate of the chloroprene monomer reached 80%, polymerization was terminated by adding a 10 wt% aqueous solution of N,N-diethylhydroxylamine as a polymerization terminator, and the unreacted chloroprene monomer was removed by vacuum distillation. The resulting latex was used for the subsequent polymerization process.

[0188] (Synthesis of the Third Block)

[0189] After the synthesis of the second block, the internal temperature was raised to 80 °C, 230 g of styrene monomer was charged, and 6.0 g of 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (manufactured by Fujifilm Wako Pure Chemical Corporation, trade name: VA-044), which is a polymerization initiator, was added to initiate polymerization. After polymerization, it was cooled to 25 °C to terminate polymerization. 20 ml of the resulting latex was sampled to measure physical properties, and an evaluation film was prepared using the remaining latex. The contents (mass %) of the styrene blocks as the first and third blocks and the chloroprene block as the second block in the synthesized triblock copolymer were determined by analysis in the same manner as in Example 1. The analysis results are shown in Table 2.

[0190] (Comparative Example 7)

[0191] Preparation of a Mixture of a Homopolymer of Polymer Block (A) and a Homopolymer of a Chloroprene-Based Polymer Block (B)

[0192] (Synthesis of homopolymer of polymer block (A))

[0193] Polymerization was carried out using a 10 L autoclave equipped with a stirrer and a heating / cooling jacket. 4666 g of pure water, 224 g of potassium disproportionated rosin (manufactured by Harima Chemicals Group, Inc.), 36.4 g of potassium hydroxide, 18.7 g of sodium salt of β-naphthalene sulfonic acid formaldehyde condensate (manufactured by Kao Corporation, trade name: Demol N), 350 g of styrene monomer, and 6.07 g of butyl benzyl trithiocarbonate were charged, and the internal temperature was adjusted to 80 °C, and stirred at 200 rpm under a nitrogen stream. 3.82 g of 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (manufactured by Fujifilm Wako Pure Chemical Corporation, trade name: VA-044), which is a polymerization initiator, was added to initiate polymerization. When the polymerization rate of the styrene monomer reached 95%, polymerization was terminated by adding a 10 wt% aqueous solution of the polymerization terminator N,N-diethylhydroxylamine. 20 ml was sampled from the obtained latex to measure physical properties. The number average molecular weight, molecular weight distribution, and glass transition temperature of the homopolymer of polymer block (A) were determined by analysis in the same manner as in Example 1. The analysis results are shown in Table 3.

[0194] (Synthesis of homopolymer of chloroprene-based polymer block (B))

[0195] Polymerization was carried out using a 10 L autoclave equipped with a stirrer and a heating / cooling jacket. 3960 g of pure water, 193 g of potassium disproportionated rosin (manufactured by Harima Chemicals Group, Inc.), 31.2 g of potassium hydroxide, 17.6 g of sodium salt of β-naphthalene sulfonic acid formaldehyde condensate (manufactured by Kao Corporation, trade name: Demol N), 4400 g of chloroprene monomer, 89.8 g of 1,9-nonanediol dimethacrylate, and 5.19 g of butyl benzyl trithiocarbonate were charged, and the internal temperature was adjusted to 45 °C, and stirred at 200 rpm under a nitrogen stream. 3.26 g of 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (manufactured by Fujifilm Wako Pure Chemical Corporation, trade name: VA-044), which is a polymerization initiator, was added to initiate polymerization. When the polymerization rate of the chloroprene monomer reached 80%, polymerization was terminated by adding a 10 wt% aqueous solution of the polymerization terminator N,N-diethylhydroxylamine, and the unreacted chloroprene monomer was removed by vacuum distillation.

[0196] (Mixing of homopolymer latex of polymer block (A) and homopolymer latex of chloroprene-based polymer block (B))

[0197] 4000 g of the homopolymer latex of the obtained polymer block (A) and 4000 g of the homopolymer latex of the chloroprene-based polymer block (B) were put into an autoclave with a capacity of 10 L equipped with a stirrer and a heating / cooling jacket, the internal temperature was raised to 45 °C, and stirring was carried out at 200 rpm. 20 ml was sampled from the obtained latex to measure physical properties, and the remaining latex was used to prepare an evaluation film. In the same manner as in Example 1, the contents (mass %) of the homopolymer of the polymer block (A) and the homopolymer of the chloroprene-based polymer block (B) in the polymer obtained by mixing were determined by analysis. The analysis results are shown in Table 3.

[0198] [Analysis]

[0199] (Measurement of the number-average molecular weight and molecular weight distribution of the polymer block (A))

[0200] The molecular weight distribution of the number-average molecular weight is a value in terms of polystyrene measured by gel permeation chromatography (GPC), and is a measured value under the following measurement conditions.

[0201] Apparatus name: HLC-8320 (manufactured by Tosoh Corporation)

[0202] Column: 3 TSKgel GMHHR-H columns connected in series

[0203] Temperature: 40 °C

[0204] Detection: Differential refractive index

[0205] Solvent: Tetrahydrofuran

[0206] Standard curve: Prepared using standard polystyrene (PS).

[0207] (Glass transition temperature of the polymer block (A))

[0208] The glass transition temperature was measured by the following method using a differential scanning calorimeter according to JIS K 7121.

[0209] Apparatus name: DSC1 (manufactured by Mettler Toledo)

[0210] Procedure: Under a nitrogen gas flow rate of 50 ml / min, the temperature was raised to 120 °C at a heating rate of 10 °C / min, maintained at 120 °C for 10 minutes, then cooled to -60 °C, and then raised to 120 °C at a heating rate of 10 °C / min. Based on the obtained DSC curve, the temperature at the intersection of the straight line extending the high-temperature side baseline to the low-temperature side and the tangent line drawn from the point with the largest gradient on the high-temperature side curve of the peak was taken as the glass transition temperature.

[0211] (Determination of the contents of the polymer block (A) and the chloroprene-based polymer block (B) in the chloroprene-based block copolymer)

[0212] It is measured by pyrolysis gas chromatography and 1H-NMR according to the following method.

[0213] Pyrolysis gas chromatography device name: HP5890-II

[0214] Column: DB-5 0.25mmφ×30m (film thickness 1.0μm)

[0215] Column temperature: 50°C (5 min) → 10°C / min → 150°C → 25°C / min → 300°C

[0216] Inlet temperature: 250°C

[0217] Detector temperature: 280°C

[0218] Detector: FID

[0219] 1H-NMR device name: JNM-ECX-400 (manufactured by JEOL Ltd.)

[0220] Procedure: Measure a chloroprene-based block copolymer composed of a polymer block (A) and a chloroprene-based polymer block (B) without a polyfunctional monomer unit by pyrolysis gas chromatography. Draw a standard curve based on the area ratio of the peaks from the polymer block (A) and the peaks from the chloroprene-based polymer block (B) and the contents of the polymer block (A) and the chloroprene-based polymer block (B) in the chloroprene-based block copolymer obtained by measuring 1H-NMR. Mix the sampled latex with methanol and measure the sample of the precipitated chloroprene-based block copolymer by pyrolysis gas chromatography. Based on the area ratio of the peaks from the polymer block (A) and the peaks from the chloroprene-based polymer block (B), use the above-drawn standard curve to determine the contents of the polymer block (A) and the chloroprene-based polymer block (B) in the chloroprene-based block copolymer.

[0221] [Preparation of Samples for Tensile Test]

[0222] (Preparation of Latex Containing Chloroprene-based Block Copolymer)

[0223] Relative to 100 parts by mass (in terms of solid content) of the chloroprene-based block copolymer in the latex obtained in polymerization step 2, add 2 parts by mass of the butylated reaction product of p-cresol and dicyclopentadiene (trade name “NOCRAC PBK”, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) as an anti-aging agent, 0.3 parts by mass of sodium lauryl sulfate (trade name “EMAR 10”, manufactured by Kao Corporation), and water. Prepare a complex with a solid content concentration of 30% by mass and mix it at 20°C for 16 hours using a pottery ball mill.

[0224] (Preparation of Film)

[0225] A pottery cylinder with an outer diameter of 50 mm was immersed in a coagulating liquid containing 62 parts by mass of water, 35 parts by mass of potassium nitrate tetrahydrate, and 3 parts by mass of calcium carbonate for 1 second and then taken out. After drying for 4 minutes, it was immersed in the latex prepared above for 2 minutes. Then, it was washed with running water at 45 °C for 1 minute and heat-treated at 130 °C for 30 minutes to remove moisture, and a film for tensile test (140 × 150 mm, thickness: 0.2 mm) was produced.

[0226] [Evaluation of Tensile Properties]

[0227] After heat-treating the produced film at 130 °C for 30 minutes, the 500% elongation modulus, breaking tensile strength, and breaking elongation were measured according to JIS K 6251. A 500% elongation modulus of 3.0 MPa or less, a breaking tensile strength of 17 MPa or more, and a breaking elongation of 900% or more were regarded as qualified.

[0228]

Table 1

[0229]

[0230]

[0231]

Table 2

[0232]

[0233]

Table 3

[0234]

[0235] In Examples 1 to 12, no vulcanizing agent and vulcanization accelerator were used, but the 500% elongation modulus was 3.0 MPa or less, the flexibility was excellent, the breaking tensile strength was 17 MPa or more, the breaking elongation was 900% or more, and the tensile properties were excellent. On the other hand, in Comparative Examples 1 to 7, any physical properties of flexibility and tensile properties were poor.

Claims

1. A chloroprene-based block copolymer, comprising: 5 to 10% by mass of a polymer block (A) derived from a monomer that forms a polymer having a glass transition temperature of 80°C or higher upon homopolymerization; and 85 to 95% by mass of a chloroprene-based polymer block (B) having chloroprene monomer units and polyfunctional monomer units, The number average molecular weight of the polymer block (A) is 10,000 or more, The molecular weight distribution of the polymer block (A) is 2.0 or less, The content of polyfunctional monomer units in the chloroprene-based polymer block (B) is 0.05 to 10.00% by mass, The polyfunctional monomer is a monomer represented by the chemical formula (1) or an aromatic polyene monomer, In Chemical Formula (1), R 1 and R 2 each independently represent any one of hydrogen, chlorine, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted aryl, substituted or unsubstituted mercapto, and substituted or unsubstituted heterocyclic group. W 1 represents any one of a saturated or unsaturated hydrocarbon group and a saturated or unsaturated hydrocarbon group containing a heteroatom. Z 1 represents oxygen, sulfur, or a structure represented by -NR 0 -. R 0 represents any one of hydrogen, chlorine, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted aryl, substituted or unsubstituted mercapto, and substituted or unsubstituted heterocyclic group.

2. The chloroprene-based block copolymer according to claim 1, wherein, After heat-treating a molded article of the latex composition containing the chloroprene-based block copolymer at 130°C for 30 minutes, the breaking tensile strength measured according to JIS K 6251 is 17 MPa or more.

3. The chloroprene-based block copolymer according to claim 1 or 2, wherein, The polymer block (A) is a polymer block composed of aromatic vinyl monomer units.

4. The chloroprene-based block copolymer according to claim 1 or 2, wherein, The said W 1 represents any one of a saturated or unsaturated cyclic hydrocarbon group and a saturated or unsaturated cyclic hydrocarbon group containing a heteroatom.

5. The chloroprene-based block copolymer according to claim 1 or 2, which has a functional group having a structure represented by the chemical formula (2) or the chemical formula (3), [Chemical formula 2] [Chemical formula 3] In Chemical Formula (2), R 3 represents any one of hydrogen, chlorine, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted aryl, substituted or unsubstituted mercapto group, and substituted or unsubstituted heterocyclic group.

6. A latex containing the chloroprene-based block copolymer according to any one of claims 1 to 5.

7. A latex composition containing 100 parts by mass of the latex according to claim 6 and 0.5 to 5.0 parts by mass of an anti-aging agent.

8. A rubber composition containing the chloroprene-based block copolymer according to any one of claims 1 to 5.

9. A rubber composition composed of the latex according to claim 6.

10. A rubber composition composed of the latex composition according to claim 7.

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