Chloroprene-based block copolymer, chloroprene-based block copolymer latex, chloroprene-based block copolymer latex composition, immersion molded article, rubber composition, and molded article

Abstract

This invention provides a chloroprene-based block copolymer latex composition and a chloroprene-based block copolymer latex, which can be prepared to produce molded articles with excellent hardness, tensile strength at break, and elongation at break by heat treatment at low temperatures. [Solution] A chloroprene-based block copolymer is provided, comprising a polymer block (A) and a chloroprene-based polymer block (B), wherein the polymer block (A) comprises monomer units derived from monomer (A), and monomer (A) is a monomer from which a polymer with a glass transition temperature of 80°C or higher can be obtained during homopolymerization; the chloroprene-based polymer block (B) comprises chloroprene monomer units and unsaturated nitrile monomer units; and the chloroprene-based block copolymer has a nitrogen content of 0.10 to 0.90% by mass as measured by combustion.

Description

Technical Field

[0001] Chloroprene rubber is used in various fields such as dip-molded articles (dip products), fiber treating agents, paper treating agents, adhesives, binders, elastic asphalt (modified asphalt), and elastic cement. Since chloroprene rubber has physical properties similar to those of natural rubber in terms of texture, etc., it has been considered as a substitute material for natural rubber (see, for example, Patent Documents 1 and 2 below).

Prior Art Documents

Patent Documents

[0002]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0003] Conventionally, the method for manufacturing a molded article containing chloroprene rubber has a heat treatment step at a high temperature, and mechanical properties, etc. are exhibited by the heat treatment at a high temperature. However, it has been difficult to obtain a molded article having excellent mechanical properties by heat treatment at a low temperature, for example, below 100°C.

[0004] The present invention has been made in view of these circumstances, and provides a chloroprene-based block copolymer and a chloroprene-based block copolymer latex that can be prepared by heat treatment at low temperatures to obtain a molded article having excellent hardness, tensile strength at break, and elongation at break. The present invention also provides a chloroprene-based block copolymer latex composition and a rubber composition containing the chloroprene-based block copolymer, as well as a dipping molded article of the chloroprene-based block copolymer latex composition having excellent hardness, tensile strength at break, and elongation at break, and a molded article of the rubber composition having excellent hardness, tensile strength at break, and elongation at break. [Means for solving the problem]

[0005] The present invention provides 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 monomer (A), and monomer (A) is a monomer from which a polymer with a glass transition temperature of 80°C or higher can be obtained during homopolymerization; the chloroprene-based polymer block (B) comprises chloroprene monomer units and unsaturated nitrile monomer units; and the chloroprene-based block copolymer has a nitrogen content of 0.55 to 3.20% by mass as measured by combustion.

[0006] The following are examples of various embodiments of the present invention. The embodiments shown below can be combined with each other. [1] 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 monomer (A), wherein monomer (A) is a monomer from which a polymer having a glass transition temperature of 80°C or higher can be obtained during homopolymerization, and the chloroprene-based polymer block (B) comprises chloroprene monomer units and unsaturated nitrile monomer units, wherein the chloroprene-based block copolymer has a nitrogen content of 0.55 to 3.20% by mass as measured by combustion. [2] The chloroprene-based block copolymer according to [1], comprising 3.0 to 15.0% by mass of the polymer block (A) with respect to 100% by mass of the chloroprene-based block copolymer. [3] The chloroprene-based block copolymer according to [1] or [2], wherein the unsaturated nitrile monomer unit is an acrylonitrile monomer unit. [4] A chloroprene block copolymer according to any one of [1] to [3], wherein a molded article of a chloroprene block copolymer latex composition containing the chloroprene block copolymer is heat-treated at 80°C for 30 minutes, and the test molded article obtained has a tensile strength at break of 9 MPa or more, measured in accordance with JIS K 6251, an elongation at break of 1900% or more, measured in accordance with JIS K 6251, and a hardness of 32 or more, measured using a Type A durometer indenter in accordance with JIS K 6253-3. [5] The chloroprene-based block copolymer according to any one of [1] to [4], wherein the number average molecular weight of the polymer block (A) is 10,000 or more. [6] The chloroprene-based block copolymer according to any one of [1] to [5], wherein the molecular weight distribution of the polymer block (A) is 2.0 or less. [7] The chloroprene-based block copolymer according to any one of [1] to [6], wherein the polymer block (A) comprises aromatic vinyl monomer units. [8] A chloroprene-based block copolymer according to any one of [1] to [7], having a functional group having a structure represented by chemical formula (1) or chemical formula (2).

[0007] [ka]

[0008] [ka] (In chemical formula (1), R1 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.) A chloroprene-based block copolymer latex comprising a chloroprene-based block copolymer described in any one of items [9][1] to [8] and water. A chloroprene-based block copolymer latex composition comprising the chloroprene-based block copolymer latex and an antioxidant as described in

[10] [9], wherein the chloroprene-based block copolymer latex composition comprises 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 latex.

[11] The chloroprene-based block copolymer latex composition according to

[10] , wherein the content of the vulcanizing agent and the vulcanization accelerator is 5.0 parts by mass or less per 100 parts by mass of the solid content of the chloroprene-based block copolymer latex. A dipping molded body of the chloroprene-based block copolymer latex composition described in

[12]

[10] . A rubber composition comprising the chloroprene-based block copolymer described in

[13] [1] to [8]. A molded article of the rubber composition described in

[14]

[13] . [Effects of the Invention]

[0009] According to the chloroprene-based block copolymer and chloroprene-based block copolymer latex of the present invention, chloroprene-based block copolymer latex compositions and rubber compositions can be prepared by heat treatment at low temperatures, which can yield molded articles having excellent hardness, tensile strength at break, and elongation at break. According to the chloroprene-based block copolymer latex compositions and rubber compositions of the present invention, immersion-molded articles and molded articles having excellent hardness, tensile strength at break, and elongation at break can be obtained by heat treatment at low temperatures. These immersion-molded articles and molded articles can be used as various components requiring excellent hardness, tensile strength at break, and / or elongation at break, taking advantage of their properties. For example, the chloroprene-based block copolymer latex composition and rubber composition can be used as paints, particularly automotive paints and intermediate coatings, to form coating films (molded articles) having excellent hardness, tensile strength at break, and elongation at break. For example, the intermediate coating can be an undercoat that can be applied on top of a primer, and a base coat or topcoat can be applied on top of it for further use. [Modes for carrying out the invention]

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

[0011] 1. Chloroprene-based block copolymers The chloroprene-based block copolymer according to the present invention comprises a polymer block (A) and a chloroprene-based polymer block (B). Polymer block (A) contains monomer units derived from monomer (A), which is a monomer from which a polymer with a glass transition temperature of 80°C or higher can be obtained during homopolymerization. Chloroprene-based polymer block (B) contains chloroprene monomer units and unsaturated nitrile monomer units, and the chloroprene-based block copolymer has a nitrogen content of 0.55 to 3.20% by mass as measured by the combustion method.

[0012] 1.1 Polymer block (A) The polymer block (A) contains monomer units derived from monomer (A). That is, in the present invention, monomer (A) is included in the raw material monomers of polymer block (A). Monomer (A) is a monomer from which a polymer having a glass transition temperature of 80°C or higher can be obtained upon bulk polymerization. By using such a monomer as the polymer block, the tensile strength at break of the resulting molded body is improved. Monomer (A) is preferably a monomer from which a polymer having a glass transition temperature of 85°C or higher can be obtained upon bulk polymerization. From the viewpoint of moldability, monomer (A) is preferably a monomer from which a polymer having a glass transition temperature of 150°C or lower can be obtained upon bulk polymerization, and more preferably a monomer from which a polymer having a glass transition temperature of 120°C or lower can be obtained upon bulk polymerization. The glass transition temperature of the polymer during the bulk polymerization of monomer (A) is, for example, 80, 85, 90, 95, 100, 105, 110, 120, 130, 140, 150°C, and may be within the range between any two of the values exemplified herein.

[0013] In this specification, the glass transition temperature refers to the extrapolated glass transition end temperature (Teg) measured in accordance with JIS K 7121. As an example, it 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.

[0014] Monomer (A) is preferably a monomer such that when monomer (A) is bulk polymerized to form a homopolymer (A) having a weight average molecular weight of 10,000 to 100,000, the homopolymer has the above glass transition temperature. More preferably, when the homopolymer (A) has a weight average molecular weight of 10,000 to 50,000, the homopolymer has the above 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) can contain one or more monomer units derived from the monomer (A). Further, the polymer block (A) may have 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) can be one containing 70% by mass or more of the monomer units derived from the monomer (A) when the polymer block (A) is 100% by mass. The content rate of the monomer units derived from the monomer (A) is, for example, 70, 75, 80, 85, 90, 95, 100% by mass, and may be within the range between any two of the values exemplified here. The polymer block (A) can also be composed of the monomer units derived from the monomer (A).

[0017] From the viewpoints of the mechanical properties and moldability of the resulting 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) is, for example, 10,000, 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, 100,000, and may be within the range between any two of the values exemplified here.

[0018] The molecular weight distribution of polymer block (A) is preferably 2.00 or less from the viewpoint of the moldability of the resulting chloroprene-based block copolymer. The molecular weight distribution of polymer block (A) may be, 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 the range of any two of the values ​​exemplified here. The number-average molecular weight and molecular weight distribution of polymer block (A) can be measured as polystyrene-converted values ​​by gel permeation chromatography (GPC), and can be measured by the method described in the examples.

[0019] The glass transition temperature of polymer block (A) is, for example, 80, 85, 90, 95, 100, 105, 110, 120, 130, 140, or 150°C, and may be within the range of any two of the values ​​exemplified herein. The glass transition temperature can be measured using a differential scanning calorimeter (DSC1 (Mettler Toledo)), and specifically by the method described in the examples.

[0020] 1.2 Chloroprene-based polymer block (B) The chloroprene polymer block (B) according to the present invention contains chloroprene monomer units derived from chloroprene monomer (2-chloro-1,3-butadiene) and unsaturated nitrile monomer units. Furthermore, the chloroprene polymer block (B) may have a structure derived from monomer units other than chloroprene monomer units and unsaturated nitrile monomer units, to the extent that it does not impair the objectives of the present invention.

[0021] The chloroprene polymer block (B) according to one embodiment of the present invention may contain 75% by mass or more of chloroprene monomer units when the chloroprene polymer block (B) is considered to be 100% by mass. The content of chloroprene monomer units may be, for example, 75, 80, 85, 90, 95, or 100% by mass, and may be within the range of any two of the values ​​exemplified herein.

[0022] The chloroprene polymer block (B) according to the present invention has unsaturated nitrile monomer units. The chloroprene polymer block (B) according to one embodiment of the present invention may contain 2.0 to 13.0% by mass of unsaturated nitrile monomer units when the chloroprene polymer block (B) is considered as 100% by mass. The content of unsaturated nitrile monomer units in the chloroprene polymer block (B) may be, for example, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0, or 13.0 parts by mass, and may be within the range of any two of the values ​​exemplified herein.

[0023] Examples of unsaturated nitrile monomer units include acrylonitrile monomer units, methacrylonitrile monomer units, ethacrylonitrile monomer units, and phenylacrylonitrile monomer units. Unsaturated nitrile monomer units can be used individually or in combination of two or more types. From the viewpoint of easily obtaining excellent moldability and easily obtaining excellent tensile strength at break, elongation at break, etc. in immersion molded articles, it is preferable that the unsaturated nitrile monomer units include acrylonitrile monomer units.

[0024] According to one embodiment of the present invention, a chloroprene-based block copolymer can be obtained that includes a polymer block (A) and a chloroprene-based polymer block (B) containing chloroprene monomer units and unsaturated nitrile monomer units. By specifying the nitrogen content of the chloroprene-based block copolymer, a chloroprene-based block copolymer latex and a chloroprene-based block copolymer latex composition can be obtained that can be molded into an article having excellent hardness, tensile strength at break, and / or elongation at break by heat treatment at low temperatures. Furthermore, with the chloroprene-based block copolymer according to one embodiment of the present invention, a molded article with the above properties can be obtained even if the amount of vulcanizing agent and vulcanization accelerator used is reduced or not used.

[0025] The chloroprene polymer block (B) according to one embodiment of the present invention may contain 10% by mass or less of other monomer units other than chloroprene monomer units and unsaturated nitrile monomer units when the chloroprene polymer block (B) is considered to be 100% by mass. The content of other monomer units other than chloroprene monomer units and unsaturated nitrile monomer units may be, for example, 0, 0.05, 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10% by mass, and may be within the range of any two of the values ​​exemplified herein.

[0026] Other monomer units besides chloroprene monomer units and unsaturated nitrile monomer units include, for example, monomer units derived from 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, styrene, isoprene, butadiene, and polyfunctional monomers. Polyfunctional monomers can be compounds having two or more radical polymerization groups in their molecules. Polyfunctional monomers can have multiple polymerizable substituents that are independent of each other. Polyfunctional monomers can have at least one pair of non-conjugated polymerizable substituents, and of the multiple polymerizable substituents, at least one pair of polymerizable substituents can be separated by at least one atom, three or more atoms, or five or more atoms.

[0027] Furthermore, the polyfunctional monomer does not have to contain 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, styrene, acrylonitrile, methacrylonitrile, isoprene, or butadiene. Also, the chloroprene polymer block (B) according to one embodiment of the present invention does not have to contain monomer units derived from 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, styrene, isoprene, butadiene, or the polyfunctional monomer.

[0028] 1.3 Content of each component in chloroprene-based block copolymers The chloroprene-based block copolymer according to one embodiment of the present invention has a nitrogen content of 0.55 to 3.20% by mass, as measured by the combustion method. The nitrogen content may be, for example, 0.55, 0.60, 0.70, 0.80, 0.90, 1.00, 1.10, 1.20, 1.30, 1.40, 1.50, 1.60, 1.70, 1.80, 1.90, 2.00, 2.10, 2.20, 2.30, 2.40, 2.50, 2.60, 2.70, 2.80, 2.90, 3.00, 3.10, or 3.20% by mass, and may be within the range of any two of the values ​​exemplified here.

[0029] The chloroprene-based block copolymer according to one embodiment of the present invention can have an unsaturated nitrile monomer unit content (particularly the acrylonitrile monomer unit content (acrylonitrile bond amount)) measured by the combustion method (Dumas method) in accordance with JIS K 6451-1:2016, which is 1.9 to 12.6% by mass. The content of unsaturated nitrile monomer units in the chloroprene polymer block (B) is, for example, 1.9, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10.0, 10.5, 11.0, 11.5, 12.0, 12.1, 12.2, 12.3, 12.4, 12.5, and 12.6% by mass, and may be within the range of any two of the values ​​exemplified here.

[0030] The nitrogen content and the content of unsaturated nitrile monomer units can be controlled by appropriately selecting the type and amount of raw materials used in the production of chloroprene-based block copolymers, and in particular by appropriately selecting the type of unsaturated nitrile and adjusting the amount added during the polymerization process of the chloroprene-based polymer block (B). The nitrogen content and the unsaturated nitrile monomer unit content can be determined by calculating the nitrogen content in the sample using an automated analyzer based on the combustion method (Dumas method) according to JIS K 6451-1:2016, and then calculating the unsaturated nitrile monomer unit content (particularly the acrylonitrile monomer unit content (acrylonitrile binding amount)) from the nitrogen content. Specifically, this can be determined by the method described in the examples.

[0031] The chloroprene-based block copolymer according to one embodiment of the present invention preferably contains 3.0 to 15.0% by mass of polymer block (A) and more preferably 8.0 to 10.5% by mass of polymer block (A) per 100% by mass of chloroprene-based block copolymer. The content of polymer block (A) is, for example, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0, or 15.0% by mass, and may be within the range of any two of the values ​​exemplified herein. If the content of polymer block (A) is above the lower limit, the tensile strength at break of the immersion molded article containing the obtained chloroprene-based block copolymer is further improved. If the polymer block (A) is below the upper limit, the elongation at break of the immersion molded article containing the obtained chloroprene-based block copolymer is further improved.

[0032] The chloroprene-based block copolymer according to one embodiment of the present invention preferably contains 85 to 97% by mass of chloroprene-based polymer block (B) per 100% by mass of chloroprene-based block copolymer, for example, it can contain 85, 90, 95, 96, or 97% by mass, and may be within the range of any two of the values ​​exemplified herein. The chloroprene-based block copolymer according to one embodiment of the present invention preferably contains a total of 70 to 100% by mass of polymer block (A) and chloroprene-based polymer block (B) per 100% by mass of chloroprene-based block copolymer, for example, 70, 75, 80, 85, 90, 95, or 100% by mass, and may be within the range of any two of the values ​​exemplified herein.

[0033] The chloroprene-based block copolymer according to one embodiment of the present invention may consist of a polymer block (A) and a chloroprene-based polymer block (B), and may not contain other polymer blocks. The chloroprene-based block copolymer may be a diblock copolymer of polymer block (A) and chloroprene-based polymer block (B).

[0034] Furthermore, 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).

[0035] [ka]

[0036] In chemical formula (1), R3 represents one of the following: 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.

[0037] [ka]

[0038] Functional groups of the structure represented by chemical formula (1) or chemical formula (2) can be introduced by carrying out the polymerization process 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 functional groups of the structure represented by chemical formula (1) or chemical formula (2) will be described later in the section on manufacturing methods.

[0039] The weight-average molecular weight of the chloroprene-based block copolymer is not particularly limited, but from the viewpoint of moldability, it is preferably 500,000 to 600,000, and particularly preferably 100,000 to 500,000.

[0040] 1.4 Physical properties of chloroprene-based block copolymers (Tensile strength at break) In one embodiment of the present invention, the chloroprene-based block copolymer preferably has a tensile strength at break of 9 MPa or more, measured in accordance with JIS K 6251, obtained by heat-treating a molded article of a chloroprene-based block copolymer latex composition containing the chloroprene-based block copolymer at 80°C for 30 minutes, as well as a test molded article. The tensile strength at break may be, for example, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0, 15.0, 16.0, 17.0, 18.0, 19.0, or 20.0 MPa, and may be within the range of any two of the values ​​exemplified here.

[0041] (Elongation upon cutting) The chloroprene-based block copolymer according to one embodiment of the present invention preferably has an elongation at break of 1900% or more, measured in accordance with JIS K 6251, after heat-treating a molded article of a chloroprene-based block copolymer latex composition containing the chloroprene-based block copolymer at 80°C for 30 minutes. The elongation at break may be, for example, 1900, 2000, 2100, 2200, 2300, 2400, 2500, 2600, 2700, 2800, 2900, or 3000 MPa, and may be within the range of any two of the values ​​exemplified herein.

[0042] (Hardness) The chloroprene-based block copolymer according to one embodiment of the present invention preferably has a hardness of 32 or higher, as measured using a Type A durometer indenter in accordance with JIS K 6253-3, after heat-treating a molded article of a chloroprene-based block copolymer latex composition containing the chloroprene-based block copolymer at 80°C for 30 minutes to obtain a test molded article. The hardness may be, for example, 32, 35, 40, 45, 50, 55, or 60, and may be within the range of any two of the values ​​exemplified herein.

[0043] The test molded article can be obtained by pouring a chloroprene block copolymer latex composition, prepared by adding 2 parts by mass of a butylated compound of p-cresol and dicyclopentadiene as an antioxidant and water to 100 parts by mass (solid content basis) of chloroprene block copolymer to a solid content concentration of 30% by mass, into a mold and drying for 3 days, and then heat-treating the molded article at 80°C for 30 minutes. The test molded article may be free of vulcanizing agents and vulcanization accelerators. Specifically, the test molded article can be obtained by the method described in the examples. The tensile strength, elongation at break, and hardness of the test molded articles can be adjusted by controlling the type and amount of raw materials used in the production of chloroprene-based block copolymers, as well as the polymerization conditions.

[0044] 2. Method for producing chloroprene-based block copolymers The method for producing the chloroprene-based block copolymer according to the present invention is not particularly limited, but can be obtained by the following method, for example. The method for producing the chloroprene-based block copolymer according to one embodiment of the present invention may include a polymerization step 1 in which raw material monomers containing monomer (A) are polymerized to obtain a polymer block (A), and a polymerization step 2 in which raw material monomers containing chloroprene and unsaturated nitrile are polymerized to obtain a chloroprene-based block copolymer containing a chloroprene-based polymer block (B), and can be produced by a two-step polymerization method.

[0045] The polymerization method is not particularly limited and can be produced by known methods such as solution polymerization, emulsion polymerization, and bulk polymerization, but emulsion polymerization is preferred. In each polymerization step, the raw material monomers can be emulsion-polymerized using emulsifiers, dispersants, polymerization initiators, RAFT agents, reducing agents, etc. as appropriate. In polymerization step 2, when the desired polymerization rate is reached, a polymerization stopper can be added to obtain a chloroprene-based block copolymer latex. After the polymerization steps, unreacted monomers may be removed by concentration methods such as vacuum distillation.

[0046] <Polymerization step 1> In polymerization step 1, a polymer block (A) can be obtained by polymerizing raw material monomers containing monomer (A). In one embodiment of the present invention, a polymer block (A) can be synthesized by living radical polymerization of raw material monomers containing monomer (A). The raw material monomers are preferably blended so that the composition of the polymer block (A) is as described above, and the type and amount of monomer (A) in the 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, 150°C, and may be within the range of any two of the values ​​exemplified here.

[0047] While there are no particular limitations on the emulsifier used in polymerization, anionic and / or nonionic emulsifiers are preferred from the viewpoint of emulsification stability. In particular, rosin acid and / or alkali metal rosinate salts are preferred because they can give the resulting chloroprene block copolymer appropriate strength and prevent excessive shrinkage and damage. From the viewpoint of efficiently carrying out the polymerization reaction, the concentration of the emulsifier can be 5 to 50 parts by mass per 100 parts by mass of the raw material monomer.

[0048] The emulsifier may also include emulsifiers and dispersants other than rosin acid and alkali metal salts of rosinate. In one embodiment of the present invention, the emulsifier used in the emulsion polymerization step may include rosin acid and / or alkali metal salts of rosinate, along with anionic emulsifiers and dispersants. As anionic emulsifiers and dispersants, it is preferable to use sulfate-based or sulfonate-based anionic emulsifiers and dispersants in combination, from the viewpoint of stabilizing the chloroprene-based block copolymer latex when pH adjusters are added. Specifically, examples include alkyl sulfonates with 8 to 20 carbon atoms, alkylaryl sulfates, condensates of sodium naphthalene sulfonate and formaldehyde, and sodium alkyldiphenyl ether disulfonate.

[0049] (Initiator) As radical polymerization initiators, known radical polymerization initiators can be used, such as potassium persulfate, benzoyl peroxide, hydrogen peroxide, and azo compounds.

[0050] (RAFT agent) In a manufacturing 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, terminal structures represented by chemical formula (1) or chemical formula (2) can be introduced into a chloroprene-based block copolymer.

[0051] [ka]

[0052] In chemical formula (1), R3 represents one of the following: 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.

[0053] [ka]

[0054] The compounds used to derive the structure represented by the above chemical formula (1) are not particularly limited and can be general compounds, such as dithiocarbamates and dithioesters. Specifically, these include benzyl 1-pyrrole carbodithioate (common name: benzyl 1-pyrrole dithiocarbamate), benzylphenyl carbodithioate, 1-benzyl-N,N-dimethyl-4-aminodithiobenzoate, 1-benzyl-4-methoxydithiobenzoate, 1-phenylethylimidazole carbodithioate (common name: 1-phenylethylimidazole dithiocarbamate), and benzyl-1-(2-pyrrolidinone)carbodithio Oate) (common name: benzyl-1-(2-pyrrolidinone)dithiocarbamate), benzylphthalimidylcarboditioate, (common name: benzylphthalimidyldithiocarbamate), 2-cyanoprop-2-yl-1-pyrrolecarboditioate, (common name: 2-cyanoprop-2-yl-1-pyrroledithiocarbamate), 2-cyanobuto-2-yl-1-pyrrolecarboditioate, (common name: 2-cyanobuto-2-yl- 1-Pyrrole dithiocarbamate), benzyl-1-imidazole carbodithioate (common 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-Fe Nylethyldithiobenzoate, 2-phenylprop-2-yldithiobenzoate, 1-1-ylethyldithiobenzoate, 1-(4-methoxyphenyl)ethyldithiobenzoate, benzyldithioacetate, ethoxycarbonylmethyldithioacetate, 2-(ethoxycarbonyl)prop-2-yldithiobenzoate, 2-cyanoprop-2-yldithiobenzoate, tert-butyldithiobenzoate, 2,4,4-Trimethylpenta-2-yldithiobenzoate, 2-(4-chlorophenyl)prop-2-yldithiobenzoate, 3-vinylbenzyldithiobenzoate, 4-vinylbenzyldithiobenzoate, benzyldiethoxyphosphenyldithioformate, tert-butyltrithioperbenzoate, 2-phenylprop-2-yl-4-chlorodithiobenzoate, naphthalene-1-carboxylic acid-1-methyl-1-phenyl-ethyl ester, 4-cyano-4-methyl-4-thiobenzylsulfanylbutyrate, dibenzyltetrathioterephthalate, carboxymethyldithiobenzoate, poly(ethylene oxide) with dithiobenzoate-terminated groups, poly(ethylene oxide) with 4-cyano-4-methyl-4-thiobenzylsulfanylbutyrate-terminated groups, 2-[(2-phenylethanesulfaneol)sulfanyl]propanoic acid, 2-[(2-phenylethanesulfaneol)sulfanyl]succinic acid , 3,5-dimethyl-1H-pyrazole-1-carbodhithioate potassium, cyanomethyl-3,5-dimethyl-1H-pyrazole-1-carbodhithioate, cyanomethyl-N-methyl-N-phenyldithiocarbamate, benzyl-4-chlorodithiobenzoate, phenylmethyl-4-chlorodithiobenzoate 4-nitrobenzyl-4-chlorodithiobenzoate, phenylprop-2-yl-4-chlorodithiobenzoate, 1-cyano Examples include 1-methylethyl-4-chlorodithiobenzoate, 3-chloro-2-butenyl-4-chlorodithiobenzoate, 2-chloro-2-butenyldithiobenzoate, benzyldithioacetate, 3-chloro-2-butenyl-1H-pyrrole-1-dithiocarboxylic acid, 2-cyanobutan-2-yl-4-chloro-3,5-dimethyl-1H-pyrazole-1-carboditioate, and cyanomethylmethyl(phenyl)carbamodithioate. Among these, benzyl-1-pyrrolecarboditioate and benzylphenylcarboditioate are particularly preferred.

[0055] The compound used to derive the structure represented by the above chemical formula (2) is not particularly limited and can be a general compound, 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 Examples of trithiocarbonates include ]-2-methylpropionic acid, 2,2′-[carbonothioylbis(thio)]bis[2-methylpropionic acid], 2-amino-1-methyl-2-oxoethylbutyltrithiocarbonate, benzyl 2-[(2-hydroxyethyl)amino]-1-methyl-2-oxoethyltrithiocarbonate, 3-[[[(tert-butyl)thio]thioxomethyl]thio]propionic acid, cyanomethyldodecyltrithiocarbonate, diethylaminobenzyltrithiocarbonate, and dibutylaminobenzyltrithiocarbonate. Among these, dibenzyltrithiocarbonate and butylbenzyltrithiocarbonate are particularly preferred.

[0056] The amount of RAFT agent added can be 0.1 to 10 parts by mass per 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 the range of any two of the values ​​exemplified here.

[0057] In the polymerization process, sodium hydroxide and / or potassium hydroxide can be used. Furthermore, a reducing agent can be added during the polymerization process. Examples of reducing agents include potassium pyrosulfite, potassium sulfite, potassium bisulfite, potassium phosphate, potassium hydrogen phosphate, sodium bisulfite, sodium sulfate, and thiourea dioxide.

[0058] (Polymerization conditions) The polymerization temperature can be appropriately determined depending on the type of monomer, but 10 to 100°C is preferred, and 20 to 80°C is particularly preferred.

[0059] <Polymerization step 2> In polymerization step 2, a chloroprene monomer, an unsaturated nitrile, etc., is added to the latex containing the polymer block (A) obtained in polymerization step 1 and polymerized to obtain a chloroprene-based block copolymer latex containing a chloroprene-based polymer block (B).

[0060] Chloroprene monomer and unsaturated nitrile may be added all at once or in separate additions. In polymerization step 2 according to one embodiment of the present invention, the raw material monomers can be added in separate additions. For example, polymerization step 2 may include a first addition step of adding at least a portion of the raw material monomers, including chloroprene and unsaturated nitrile, and a second addition step of adding the remaining raw material monomers.

[0061] In the first addition step, when the total chloroprene monomer added in polymerization step 2 is 100 parts by mass, at least 20 parts by mass of chloroprene monomer can be added. For example, 20, 30, 40, 50, 60, or 70 parts by mass can be added, and the amount may be within the range of any two of the values ​​exemplified here. Also, in the first addition step, when the total unsaturated nitrile added in polymerization step 2 is 100 parts by mass, at least 50 parts by mass of unsaturated nitrile can be added. For example, 50, 60, 70, 80, 90, or 100 parts by mass can be added, and the amount may be within the range of any two of the values ​​exemplified here. In the first addition step, at least a portion of the raw material monomer can be added over a period of 0.1 to 5.0 hours, for example, over 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0 hours, and may be within the range of any two of the values ​​exemplified here.

[0062] In the second addition step, when the total chloroprene monomer added in polymerization step 2 is 100 parts by mass, at least 30 parts by mass of chloroprene monomer can be added. For example, 30, 40, 50, 60, or 70 parts by mass can be added, and the amount may be within the range of any two of the values ​​exemplified here. Also, in the second addition step, when the total unsaturated nitrile added in polymerization step 2 is 100 parts by mass, 0, 10, 20, or 30 parts by mass of unsaturated nitrile can be added, and the amount may be within the range of any two of the values ​​exemplified here. In the second addition step, at least a portion of the raw material monomer can be added over 1 to 10 hours. For example, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, and the amount may be within the range of any two of the values ​​exemplified here. The second addition step can be started immediately after the first addition step. Unsaturated nitrile does not need to be added in the second addition step.

[0063] 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 stopped by adding a polymerization stopper. Examples of polymerization stoppers include thiodiphenylamine, 4-tertiary butylcatechol, and 2,2'-methylenebis-4-methyl-6-tertiary butylphenol. Unreacted monomers after polymerization can be removed by conventional methods such as vacuum distillation.

[0064] The latex containing the chloroprene-based block copolymer obtained in polymerization step 2 may optionally contain freeze stabilizers, emulsifying stabilizers, viscosity modifiers, antioxidants, preservatives, etc., after polymerization, as long as it does not impair the objectives of the present invention.

[0065] <Recovery Process> There are no particular limitations on the method for recovering the chloroprene block copolymer from latex containing the chloroprene block copolymer. Known methods such as immersion in a coagulation solution or precipitation using a poor solvent such as methanol can be used.

[0066] 3. Chloroprene-based block copolymer latex A chloroprene-based block copolymer latex according to one embodiment of the present invention may contain the above-mentioned 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 directly as chloroprene-based block copolymer latex. Alternatively, the recovered chloroprene-based block copolymer can be forcibly emulsified using an emulsifier to obtain chloroprene-based block copolymer latex.

[0067] 4. Chloroprene-based block copolymer latex composition and rubber composition A chloroprene-based block copolymer latex composition according to one embodiment of the present invention may contain the above-mentioned chloroprene-based block copolymer latex and an antioxidant. A molded body can be obtained by immersing the chloroprene-based block copolymer latex composition in a coagulation solution and molding it. A rubber composition according to one embodiment of the present invention may contain the chloroprene-based block copolymer described above. The rubber composition can be molded by any method to obtain a molded article.

[0068] The chloroprene-based block copolymer latex composition and rubber composition according to one embodiment of the present invention contain a chloroprene-based block copolymer and may contain other components depending on the purpose and application. Examples of raw materials that may be contained in the chloroprene-based block copolymer latex composition and rubber composition include vulcanizing agents, vulcanization accelerators, fillers or reinforcing agents, plasticizers, processing aids or lubricants, antioxidants, silane coupling agents, and surfactants.

[0069] <Anti-aging agent> The chloroprene-based block copolymer latex composition and rubber composition according to one embodiment of the present invention may contain an antioxidant. The chloroprene-based block copolymer latex composition according to one embodiment of the present invention may contain 0.5 to 5.0 parts by mass of an antioxidant per 100 parts by mass of solids of the chloroprene-based block copolymer. The amount of the antioxidant may be, 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 the range of any two of the values ​​exemplified herein.

[0070] Anti-aging agents are used to improve the heat resistance of rubber compositions. They include primary anti-aging agents that prevent auto-oxidation by capturing radicals, and secondary anti-aging agents that neutralize hydroperoxides. Examples of primary anti-aging agents include phenolic anti-aging agents, amine anti-aging agents, acrylate anti-aging agents, imidazole anti-aging agents, metal carbamates, and waxes. Examples of secondary anti-aging agents include phosphorus anti-aging agents, sulfur anti-aging agents, and imidazole anti-aging agents. Examples of anti-aging agents, though not limited to them, include N-phenyl-1-naphthylamine, alkylated diphenylamine, octylated diphenylamine, 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, p-(p-toluenesulfonylamide)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-butylphenol), 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-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-hydroxybenzylphosphonate-diethyl ester, Tetrakis[methylene(3,5-di-t-butyl-4-hydroxyhydrocinnamate)]methane, Octadecyl-3-(3,5-di-t- Butyl-4-hydroxyphenyl)propionate and 3,9-bis[2-{3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy}-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane, tris(nonylphenyl) phosphite, tris(mixed mono- and di-nonylphenyl) phosphite, diphenyl mono(2-ethylhexyl) phosphite, diphenyl monotridecyl phosphite, diphenyl iso Decyl phosphite, 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-tri Su(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-diphenolalkyl(C12~C15)phosphite, cyclic neopentanetetraylbis(2,4-di-t-butylphenylphosphite), cyclic neopentanetetraylbis(2,Examples include 6-di-t-butyl-4-phenyl phosphite, cyclic neopentanetetraylbis(nonylphenyl phosphite), bis(nonylphenyl)pentaerythritol diphosphite, dibutylhydrogen phosphite, distearyl pentaerythritol diphosphite and hydrogenated bisphenol A pentaerythritol phosphite polymer, 2-mercaptobenzimidazole, and butylation reaction products of p-cresol and dicyclopentadiene.

[0071] <Vulcanizing agents and vulcanizing accelerators> The chloroprene-based block copolymer latex composition and rubber composition according to one embodiment of the present invention may also contain a vulcanizing agent and / or a vulcanization accelerator. Furthermore, the chloroprene-based block copolymer latex composition and rubber composition according to one embodiment of the present invention do not necessarily contain sulfur and the aforementioned vulcanization accelerators such as thiram-based, dithiocarbamate-based, thiourea-based, guanidine-based, xanthogenicate-based, and thiazole-based agents. In other words, the chloroprene-based block copolymer latex composition and rubber composition include those containing a vulcanizing agent but not a vulcanization accelerator, those containing a vulcanizing agent but including a vulcanization accelerator, those containing a vulcanizing agent and a vulcanization accelerator, and those not containing a vulcanizing agent and a vulcanization accelerator. Whether or not to include a vulcanizing agent and a vulcanization accelerator should be determined according to the target immersion molded article or molded article.

[0072] 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 block copolymer contained in the chloroprene block copolymer latex composition. Examples of the amount of vulcanizing agent added are 0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, and 5.0, and may be within the range of any two of the values ​​exemplified here.

[0073] A vulcanization accelerator is a chemical added to raw rubber during the vulcanization process to increase the vulcanization rate, shorten the vulcanization time, lower the vulcanization temperature, reduce the amount of vulcanizing agent used, and improve the physical properties of the vulcanized rubber. It usually refers to a chemical that accelerates the sulfur vulcanization reaction.

[0074] Examples of vulcanization accelerators include, but are not limited to, thiram-based, dithiocarbamate-based, thiourea-based, guanidine-based, xanthogenicate-based, and thiazole-based agents. These can be used alone or in combination of two or more as needed.

[0075] Examples of thiram-based vulcanization accelerators include tetramethylthiram disulfide, tetraethylthiram disulfide, tetrabutylthiram disulfide, tetrakis(2-ethylhexyl)thiram disulfide, tetramethylthiram monosulfide, and dipentamethylenethiram tetrasulfide.

[0076] Examples of dithiocarbamate-based vulcanization accelerators include sodium dibutyldithiocarbamate, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc N-ethyl-N-phenyldithiocarbamate, zinc N-pentamethylenedithiocarbamate, copper dimethyldithiocarbamate, ferric dimethyldithiocarbamate, and tellurium diethyldithiocarbamate, with zinc dibutyldithiocarbamate being particularly preferred.

[0077] Examples of thiourea-based vulcanization accelerators include ethylenethiourea, N,N'-diethylthiourea, trimethylthiourea, and N,N'-diphenylthiourea.

[0078] Examples of guanidine-based vulcanization accelerators include 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, and di-o-tolylguanidine salts of dicatecholborate.

[0079] Examples of xanthogenic acid-based vulcanization accelerators include zinc butylxanthonate and zinc isopropylxanthonate.

[0080] Examples of thiazole-based vulcanization accelerators include 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, 2-mercaptobenzothiazole zinc salt, cyclohexylamine salt of 2-mercaptobenzothiazole, and 2-(4'-morpholinodithio)benzothiazole.

[0081] 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 block copolymer contained in the chloroprene block copolymer latex composition. 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 may be within the range of any two of the values ​​exemplified here. The chloroprene block copolymer latex composition and rubber composition according to one embodiment of the present invention can have sufficient mechanical strength without vulcanization and can exhibit excellent elongation at break and hardness. For this reason, from the viewpoint of reducing allergies and costs, the vulcanizing agent and vulcanization accelerator can be omitted.

[0082] 5. Immersed molded body and molded body An immersion molded article according to one embodiment of the present invention can be an immersion molded article of the above-mentioned chloroprene-based block copolymer latex composition. Furthermore, the molded article according to one embodiment of the present invention can be a molded article of the above-mentioned rubber composition. Immersion-molded bodies can be suitably used for gloves, balloons, catheters, and boots, while the molded bodies can be suitably used for automotive intermediate coatings, etc.

[0083] (Tensile strength at break) The molded article and immersion-molded article according to one embodiment of the present invention preferably have a tensile strength at break of 9 MPa or more, as measured in accordance with JIS K 6251. The tensile strength at break may be, for example, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0, 15.0, 16.0, 17.0, 18.0, 19.0, or 20.0 MPa, and may be within the range of any two of the values ​​exemplified herein.

[0084] (Elongation upon cutting) The molded article and immersion-molded article according to one embodiment of the present invention preferably have an elongation at break of 1900% or more, as measured in accordance with JIS K 6251. The elongation at break may be, for example, 1900, 2000, 2100, 2200, 2300, 2400, 2500, 2600, 2700, 2800, 2900, or 3000 MPa, and may be within the range of any two of the values ​​exemplified herein.

[0085] (Hardness) The molded article and immersion-molded article according to one embodiment of the present invention preferably have a hardness of 32 or higher, as measured using a Type A durometer indenter measured in accordance with JIS K 6253-3. The hardness may be, for example, 32, 35, 40, 45, 50, 55, or 60, and may be within the range of any two of the values ​​exemplified herein.

[0086] 6. Immersion molded body and method for manufacturing the molded body A method for producing a dipping molded article according to one embodiment of the present invention may include a dipping molding step of dipping the above-mentioned chloroprene-based block copolymer latex composition to obtain a dipping molded article, and a heat treatment step. Furthermore, a method for manufacturing a molded article according to one embodiment of the present invention may include a molding step of molding the above-mentioned chloroprene-based block copolymer latex composition and / or rubber composition by any method, and a heat treatment step.

[0087] Examples of immersion molding methods according to one embodiment of the present invention include immersion solidification method, simple immersion method, heat-sensitive immersion method, and electrodeposition method. From the viewpoint of ease of manufacturing and ease of obtaining an immersion molded body of a certain thickness, the immersion solidification method can be used. Specifically, a ceramic mold coated with a calcium-based coagulation solution is immersed in a chloroprene-based block copolymer latex composition, and the chloroprene-based block copolymer latex composition is solidified. Then, after removing water-soluble impurities by leaching and drying, an immersion molded film (rubber coating) is formed by heating, and the immersion molded film is released from the mold. This makes it possible to obtain a film-like immersion molded body.

[0088] A molding method according to one embodiment of the present invention may include, for example, the step of pouring the above-mentioned chloroprene-based block copolymer latex composition and / or rubber composition into a mold or any other suitable medium, drying it, and obtaining a molded body (e.g., a film).

[0089] An immersion molded body and a method for manufacturing the molded body according to one embodiment of the present invention may include a heat treatment step of heat-treating the immersion molded body and the molded body.

[0090] The heat treatment temperature can be set appropriately according to the composition of the chloroprene block copolymer and may be between 20 and 180°C. The heating temperature is preferably between 70 and 120°C. Examples of heating temperatures include 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, and 180°C, and may be within the range of any two of the values ​​exemplified here. The heating time can be set appropriately according to the composition, shape, etc., of the chloroprene block copolymer and may be between 0 and 300 minutes. The heating time can be, for example, 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, or 300 minutes, and may be within the range of any two of the values ​​exemplified here. As an example, an immersion molded body according to one embodiment of the present invention can be heat-treated at 80°C for 30 minutes. [Examples]

[0091] The present invention will be described below with reference to examples and comparative examples, but these are all illustrative and do not limit the scope of the present invention.

[0092] (Example 1) (Polymerization process 1) Synthesis of polymer block (A-1) Polymerization was carried out using a 10L autoclave equipped with a stirrer and a heating / cooling jacket. 3419g of pure water, 151g of potassium disproportionate rosinate (Harima Chemicals Group Co., Ltd.), 2.16g of potassium hydroxide, 17.1g of sodium salt of β-naphthalene sulfonic acid formalin condensate (Kao Corporation, product name: Demol N), 332g of styrene monomer, and 5.91g of butylbenzyl trithiocarbonate were charged, and the mixture was stirred at 200 rpm under a nitrogen stream at an internal temperature of 80°C. 3.72g of 2,2'-azobis[2-(2-imidazolin-2-yl)propane]dihydrogen chloride (Fujifilm Wako Pure Chemical Industries, Ltd., product name: VA-044) was added as a polymerization initiator to start the polymerization. 20ml of the obtained latex was sampled for property measurement, and the remaining latex was used in polymerization step 2.

[0093] The sampled latex was mixed with a large amount of methanol to precipitate the resin component, and 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 polymer block (A-1) were determined by analysis of the obtained sample. The measurement method will be described later.

[0094] (Polymerization step 2) Synthesis of chloroprene polymer block (B-1) After polymerization step 1, once the internal temperature had dropped to 45°C, 994 g of chloroprene monomer and 288 g of acrylonitrile were slowly added over 0.5 hours to carry out polymerization (first addition step). Immediately after the first addition, 2318 g of chloroprene monomer was slowly added over 3.5 hours to carry out polymerization (second addition step). When the polymerization rate of the chloroprene monomer reached 80%, polymerization was stopped by adding a 10 wt% aqueous solution of N,N-diethylhydroxylamine, which is a polymerization stopper, and the unreacted chloroprene monomer was removed by vacuum distillation. For physical property measurement, 20 ml of the obtained latex was sampled, and an evaluation film was prepared using the remaining latex.

[0095] The sampled latex was mixed with a large amount of methanol to precipitate the resin component, and then filtered and dried to obtain a sample of chloroprene-based block copolymer. From the obtained sample, the content (mass%) of chloroprene-based block copolymer polymer block (A-1) and chloroprene-based polymer block (B-1), the nitrogen content measured by combustion, and the acrylonitrile monomer unit content were determined by analysis. The analysis results are shown in Table 1. The measurement method will be described later.

[0096] (Examples 2-4, Comparative Examples 1-4) 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, as well as the polymerization conditions, were as shown in the table in polymerization steps 1 and 2.

[0097] [analysis] (Measurement of number-average molecular weight and molecular weight distribution of polymer block (A)) The number-average molecular weight and molecular weight distribution are polystyrene-converted values ​​measured by gel permeation chromatography (GPC), and are measured under the measurement conditions described below. Device name: HLC-8320 (manufactured by Tosoh Corporation) Column: Three TSKgel GMHHR-H columns in series. Temperature: 40℃ Detection: Differential refractive index Solvent: tetrahydrofuran Calibration curve: Prepared using standard polystyrene (PS).

[0098] (Glass transition temperature of polymer block (A)) The glass transition temperature was measured using a differential scanning calorimeter in accordance with JIS K 7121, using the following method. Device name: DSC1 (manufactured by Mettler Toledo) Procedure: Under a nitrogen flow 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. From the DSC curve obtained, the temperature at the intersection of a straight line extending the high-temperature side pace line toward the low-temperature side and a tangent line drawn at the point where the slope of the peak curve on the high-temperature side is maximum was defined as the glass transition temperature.

[0099] (Measurement of the content of polymer block (A) and chloroprene polymer block (B) in the chloroprene-based block copolymer) Pyrolysis gas chromatogram and 1 The measurement was performed using 1H-NMR by the following method. Pyrolysis gas chromatogram. Instrument name: HP5890-II Column: DB-5 0.25mmφ×30m (film thickness 1.0μm) Column temperature: 50°C (5 min) → 10°C / min → 150°C → 25°C / min → 300°C Inlet temperature: 250℃ Detector temperature: 280℃ Detector: FID 1 H-NMR spectrometer name: JNM-ECX-400 (manufactured by JEOL Ltd.) Procedure: A chloroprene-based block copolymer consisting of polymer block (A) and a chloroprene-based polymer block (B) that does not contain unsaturated nitrile monomer units is measured by pyrolysis gas chromatogram, and the area ratio of the peak derived from polymer block (A) to the peak derived from chloroprene-based polymer block (B) is calculated. 1 A calibration curve was created from the content of polymer blocks (A) and chloroprene polymer blocks (B) in the chloroprene-based block copolymer obtained by measuring 1H-NMR. A sample of the chloroprene-based block copolymer precipitated by mixing sampled latex with methanol was measured by pyrolysis gas chromatogram, and the content of polymer blocks (A) and chloroprene polymer blocks (B) in the chloroprene-based block copolymer was determined using the calibration curve created above, based on the area ratio of the peak derived from polymer block (A) and the peak derived from chloroprene polymer block (B).

[0100] (Nitrogen content and acrylonitrile monomer content) The nitrogen content in chloroprene-based block copolymers was measured by combustion, and the acrylonitrile monomer unit content was calculated from the nitrogen content. The analytical method followed JIS K6451-1:2016, using an automated analyzer with a combustion method (Dumas method) to calculate the nitrogen content in the sample. From this nitrogen content, the acrylonitrile monomer unit content (amount of bound acrylonitrile) was calculated. The acrylonitrile monomer unit content in chloroprene-based polymer block (B) was calculated based on the nitrogen content in the chloroprene-based block copolymer and the content of polymer block (A) and chloroprene-based polymer block (B) within the block copolymer.

[0101] Specifically, the nitrogen atom content in 100 mg of chloroprene-based block copolymer was measured using an elemental analyzer (Sumigraph 220F: manufactured by Sumika Analysis Center Co., Ltd.), and the monomer content of acrylonitrile was calculated. The elemental analysis was performed as follows: The electric furnace temperature was set to 900°C for the reactor, 600°C for the reduction furnace, 70°C for the column, and 100°C for the detector. Oxygen gas was flowed at 0.2 mL / min as the combustion gas, and helium gas at 80 mL / min as the carrier gas. A calibration curve was created using aspartic acid (10.52%), whose nitrogen content is known, as a standard substance.

[0102] [Preparation of samples for tensile testing] (Preparation of chloroprene block copolymer latex compositions containing chloroprene block copolymers) To 100 parts by mass (in terms of solid content) of the chloroprene-based block copolymer obtained in polymerization step 2, 2 parts by mass of a butylated compound of p-cresol and dicyclopentadiene condensate (Nocrack PBK, manufactured by Ouchi Shinko Chemical Co., Ltd.) and water were added as an antioxidant to adjust the solid content of the mixture to 30% by mass. The mixture was then mixed using a ceramic ball mill at 20°C for 16 hours to prepare a chloroprene-based block copolymer latex composition.

[0103] (Film production) The above-mentioned chloroprene-based block copolymer latex composition was poured into a mold and dried at room temperature for 3 days to produce a film (140 x 150 mm, thickness: 0.2 mm).

[0104] [Evaluation of molded products] The prepared film was heat-treated at 80°C for 30 minutes to obtain a test molded body. (Hardness) Test molded bodies were stacked to a thickness of 6.00 ± 0.20 mm, and their hardness was measured at 23°C using a Type A durometer indenter, in accordance with JIS K 6253-3:2012.

[0105] (Tensile strength at break, elongation at break) Using test molded specimens, the tensile strength at break and elongation at break were measured in accordance with JIS K 6251:2017.

[0106] [Table 1]

[0107] [Table 2]

Claims

1. A chloroprene-based block copolymer comprising a polymer block (A) and a chloroprene-based polymer block (B), The polymer block (A) includes monomer units derived from monomer (A), The monomer (A) is a monomer that yields a polymer with a glass transition temperature of 80°C or higher during homopolymerization. The chloroprene polymer block (B) comprises chloroprene monomer units and unsaturated nitrile monomer units. The chloroprene-based block copolymer is a chloroprene-based block copolymer having a nitrogen content of 0.55 to 3.20% by mass, as measured by combustion.

2. The chloroprene-based block copolymer according to claim 1, comprising 3.0 to 15.0% by mass of the polymer block (A) with respect to 100% by mass of the chloroprene-based block copolymer.

3. The chloroprene-based block copolymer according to claim 1 or claim 2, wherein the unsaturated nitrile monomer unit is an acrylonitrile monomer unit.

4. The chloroprene block copolymer according to claim 1 or 2, wherein a molded article of a chloroprene block copolymer latex composition containing the chloroprene block copolymer is heat-treated at 80°C for 30 minutes, and the tensile strength at break obtained in accordance with JIS K 6251 is 9 MPa or more, the elongation at break measured in accordance with JIS K 6251 is 1900% or more, and the hardness measured using a type A durometer indenter in accordance with JIS K 6253-3 is 32 or more.

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

6. The chloroprene-based block copolymer according to claim 1 or claim 2, wherein the molecular weight distribution of the polymer block (A) is 2.0 or less.

7. The chloroprene-based block copolymer according to claim 1 or claim 2, wherein the polymer block (A) contains aromatic vinyl monomer units.

8. A chloroprene-based block copolymer according to claim 1 or claim 2, having a functional group having a structure represented by chemical formula (1) or chemical formula (2). 【Chemistry 1】 【Chemistry 2】 (In chemical formula (1), R １ (This 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.)

9. A chloroprene-based block copolymer latex comprising the chloroprene-based block copolymer described in claim 1 or claim 2 and water.

10. A chloroprene-based block copolymer latex composition comprising the chloroprene-based block copolymer latex described in claim 9 and an antioxidant, A chloroprene-based block copolymer latex composition comprising 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 latex.

11. The chloroprene-based block copolymer latex composition according to claim 10, wherein the content of the vulcanizing agent and the vulcanization accelerator is 5.0 parts by mass or less per 100 parts by mass of the solid content of the chloroprene-based block copolymer latex.

12. A dipping molded body of the chloroprene-based block copolymer latex composition according to claim 10.

13. A rubber composition comprising the chloroprene-based block copolymer described in claim 1 or claim 2.

14. A molded article of the rubber composition according to claim 13.

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