Chloroprene-based polymer, chloroprene-based polymer latex, chloroprene-based polymer latex composition, dip-molded article, rubber composition, and molded article

Abstract

The present invention provides a chloroprene-based polymer that is capable of preparing a rubber composition and a chloroprene-based polymer latex composition with which it is possible to obtain, by means of a heat treatment at a low temperature, a molded article that has an adequate elongation at 500% elongation and a high tensile strength at break. The present invention specifically provides a chloroprene-based polymer which has an epoxy equivalent of 3,000 to 20,000 as determined in accordance with JIS K7236.

Description

Chloroprene polymer, chloroprene polymer latex, chloroprene polymer latex composition, dip-molded article, rubber composition, and molded article

[0001] Chloroprene rubber is used in various fields, such as dip-molded bodies (dip products), fiber treatment agents, paper processing agents, pressure-sensitive adhesives, adhesives, elastic asphalt (modified asphalt), elastic cement, etc. Chloroprene rubber has physical properties similar to those of natural rubber in terms of feel, etc., and therefore has been investigated as a substitute for natural rubber (see, for example, Patent Documents 1 and 2 listed below).

[0002] International Publication No. 2019 / 009038 Japanese Patent Application Laid-Open No. 2019-143002

[0003] Conventionally, a method for producing a molded article containing chloroprene rubber includes a high-temperature heat treatment step, and the high-temperature heat treatment develops mechanical properties, etc. However, it has been difficult to obtain a molded article having flexibility and 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 the above circumstances and provides a chloroprene polymer and a chloroprene polymer latex from which a chloroprene polymer latex composition and a rubber composition can be prepared that can be heat-treated at low temperature to give a molded article having a suitable elongation at 500% elongation and high tensile strength at break. The present invention also provides a chloroprene polymer latex composition and a rubber composition containing the chloroprene polymer, as well as a dip-molded article of the chloroprene polymer latex composition having a suitable elongation at 500% elongation and high tensile strength at break, and a molded article of the rubber composition having a suitable elongation at 500% elongation and high tensile strength at break.

[0005] According to the present invention, there is provided a chloroprene polymer having an epoxy equivalent weight of 3,000 to 20,000 as measured in accordance with JIS K 7236.

[0006] Various embodiments of the present invention are exemplified below. The embodiments shown below can be combined with each other. [1] A chloroprene-based polymer, wherein the chloroprene-based polymer has an epoxy equivalent of 3,000 to 20,000 as measured in accordance with JIS K 7236. [2] The chloroprene-based polymer according to [1], wherein the chloroprene-based polymer contains monomer units derived from a monomer (A), the monomer (A) being a monomer that, upon homopolymerization, gives a polymer having a glass transition temperature of 80°C or higher, and the content of the monomer units derived from the monomer (A) relative to 100% by mass of the chloroprene-based polymer is 15% by mass or less. [3] The chloroprene polymer according to [2], wherein the chloroprene polymer is a chloroprene block copolymer comprising a polymer block (A) containing monomer units derived from the monomer (A) and a chloroprene polymer block (B), wherein the chloroprene polymer block (B) contains chloroprene monomer units. [4] The chloroprene polymer according to [3], wherein the polymer block (A) has a number average molecular weight of 10,000 or more. [5] The chloroprene polymer according to [3] or [4], wherein the polymer block (A) has a molecular weight distribution of 2.0 or less. [6] The chloroprene polymer according to any of [2] to [5], wherein the monomer units derived from the monomer (A) include aromatic vinyl monomer units. [7] The chloroprene polymer according to any one of [1] to [6], wherein a molded article of a chloroprene polymer latex composition containing the chloroprene polymer is heat-treated at 80°C for 30 minutes, and the obtained test molded article has a tensile strength at break of 17.0 MPa or more, as measured in accordance with JIS K 6251. [8] A chloroprene polymer latex comprising the chloroprene polymer according to any one of [1] to [7] and water. [9] A chloroprene polymer latex composition comprising the chloroprene polymer latex according to [8] and a curing agent.

[10] The chloroprene polymer latex composition according to [9], wherein a total amount of a vulcanizing agent and a vulcanization accelerator is 5.0 parts by mass or less per 100 parts by mass of the solid content of the chloroprene polymer latex.

[11] A dip-molded article of the chloroprene polymer latex composition according to [9] or

[10] .

[12] A rubber composition comprising the chloroprene polymer according to any one of [1] to [7].

[13] A molded article of the rubber composition according to

[12] .

[0007] The chloroprene polymer of the present invention can be used to prepare a chloroprene polymer latex composition and a rubber composition that can be heat-treated at low temperatures to give a molded article having a suitable elongation at 500% elongation and high tensile strength at break. The chloroprene polymer latex composition and the rubber composition of the present invention can be heat-treated at low temperatures to give a molded article having a suitable elongation at 500% elongation and high tensile strength at break. Taking advantage of their properties, the dip-molded articles and molded articles can be used as various components that require a suitable elongation at 500% elongation and high tensile strength at break. For example, the chloroprene polymer latex composition and the rubber composition can be used as a paint, particularly an automotive paint or a pre-coating paint, to form a coating film (molded article) having a suitable elongation at 500% elongation and high tensile strength at break. For example, the paint can be used as an intermediate paint (pre-coating paint) that can be applied over a primer paint, and a base paint or a top coat can be applied thereon.

[0008] The present invention will be described in detail below by illustrating embodiments of the present invention. The present invention is not limited by these descriptions. The features of the embodiments of the present invention described below can be combined with each other. Furthermore, each feature can be an invention independently.

[0009] 1. Chloroprene-Based Polymer The chloroprene-based polymer according to the present invention contains chloroprene monomer units derived from a chloroprene monomer (2-chloro-1,3-butadiene). The chloroprene-based polymer according to the present invention may contain monomer units derived from a monomer containing an epoxy group.

[0010] The chloroprene polymer according to the present invention has an epoxy equivalent of 3,000 to 20,000 as measured in accordance with JIS K 7236. The epoxy equivalent indicates the mass of a resin (polymer) containing one equivalent of epoxy groups. The chloroprene polymer according to the present invention has an epoxy equivalent within a specific range, i.e., contains a specific amount of epoxy groups, which allows the chloroprene polymers to form an appropriate crosslinked structure even when heated at low temperatures. Therefore, it is believed that molded articles of the chloroprene polymer latex composition and rubber composition containing the chloroprene polymer according to the present invention have an appropriate elongation at 500% elongation and high tensile strength at break. Furthermore, the chloroprene polymer latex composition and rubber composition containing the chloroprene polymer according to one embodiment of the present invention can be heat-treated at low temperatures to obtain molded articles having an appropriate elongation at 500% elongation, high tensile strength at break, and high elongation at break. Furthermore, the chloroprene polymer latex composition and rubber composition containing the chloroprene polymer according to one embodiment of the present invention can give molded articles having excellent properties by heat treatment at low temperature, even if the amounts of a vulcanizing agent and a vulcanization accelerator used are reduced or even if no vulcanizing agent and a vulcanization accelerator are used.

[0011] The epoxy equivalent of the chloroprene polymer according to the present invention is, for example, 3,000, 4,000, 5,000, 6,000, 7,000, 8,000, 9,000, 10,000, 11,000, 12,000, 13,000, 14,000, 15,000, 16,000, 17,000, 18,000, 19,000, or 20,000, and may be within a range between any two of the numerical values ​​exemplified here.

[0012] The epoxy equivalent can be measured by the method described in the Examples. The epoxy equivalent can be controlled by adjusting the production conditions of the chloroprene polymer, and can be controlled by adjusting the type and amount of a monomer having an epoxy group in the polymerization recipe.

[0013] The epoxy group-containing monomer is not particularly limited as long as it is copolymerizable with chloroprene and can impart epoxy groups to the resulting chloroprene-based polymer. From the perspective of use in emulsion polymerization, the epoxy group-containing monomer preferably has 6 or more carbon atoms. The carbon number of the epoxy group-containing monomer is, for example, 6, 7, 8, 9, 10, 11, or 12, and may be within a range between any two of the carbon numbers exemplified here. It preferably contains a glycidyl group, and preferably contains at least one selected from glycidyl methacrylate, glycidyl acrylate, and (3,4-epoxycyclohexyl)methyl acrylate, and preferably contains glycidyl methacrylate and / or glycidyl acrylate.

[0014] A chloroprene polymer according to one embodiment of the present invention may contain 5.0% by mass or less of monomer units derived from a monomer containing an epoxy group, based on 100% by mass of the chloroprene polymer. The content of the monomer units derived from a monomer containing an epoxy group 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% by mass, or may be within a range between any two of the values ​​exemplified here.

[0015] The chloroprene polymer may have a structure derived from a monomer unit other than the chloroprene monomer unit. The monomer other than the chloroprene monomer is not particularly limited as long as it is copolymerizable with the chloroprene monomer, and examples thereof include (meth)acrylic acid esters (methyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, etc.), hydroxyalkyl (meth)acrylates (2-hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, etc.), 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, butadiene, isoprene, unsaturated nitriles, ethylene, styrene, sulfur, etc.

[0016] A chloroprene polymer according to one embodiment of the present invention preferably contains monomer units derived from a monomer (A). Here, the monomer (A) may be a monomer that, upon homopolymerization, gives a polymer having a glass transition temperature of 80°C or higher. By containing monomer units derived from the monomer (A), the chloroprene polymer according to one embodiment of the present invention further improves the tensile strength at break of the resulting molded article. A chloroprene polymer according to one embodiment of the present invention may contain monomer units derived from one or more types of monomer (A).

[0017] The monomer (A) is preferably a monomer that, upon homopolymerization, gives a polymer having a glass transition temperature of 85° C. or higher. From the viewpoint of moldability, the monomer (A) is preferably a monomer that, upon homopolymerization, gives a polymer having a glass transition temperature of 150° C. or lower, and more preferably a monomer that gives a polymer having a glass transition temperature of 120° C. or lower. The glass transition temperature of the polymer upon homopolymerization of the monomer (A) is, for example, 80, 85, 90, 95, 100, 105, 110, 120, 130, 140, or 150° C., and may be within a range between any two of the values ​​exemplified here.

[0018] In this specification, the glass transition temperature refers to the extrapolated glass transition end temperature (Teg) measured in accordance with JIS K 7121. For example, the glass transition temperature can be measured using a differential scanning calorimeter (DSC1 (manufactured by Mettler Toledo)), and specifically, the glass transition temperature can be measured by the method described in the examples.

[0019] The monomer (A) is preferably a monomer that, when homopolymerized to form a homopolymer (A) having a weight-average molecular weight of 10,000 to 100,000, has the above-mentioned glass transition temperature, and more preferably a monomer that, when homopolymerized to form a homopolymer (A) having a weight-average molecular weight of 10,000 to 50,000, has the above-mentioned glass transition temperature.

[0020] Examples of the monomer units derived from the monomer (A) include aromatic vinyl monomer units and methyl methacrylate monomer units. The monomer units derived from the monomer (A) preferably contain aromatic vinyl monomer units, and more preferably contain styrene monomer units.

[0021] A chloroprene polymer according to one embodiment of the present invention may contain 75% by mass or more of chloroprene monomer units, based on 100% by mass of the chloroprene polymer. The content of the chloroprene monomer units may be, for example, 75, 80, 85, 90, 95, or 100% by mass, or may be within a range between any two of the values ​​exemplified here.

[0022] A chloroprene polymer according to one embodiment of the present invention may contain 15% by mass or less of monomer units derived from the monomer (A) relative to 100% by mass of the chloroprene polymer. The content of the monomer units derived from the monomer (A) may be, for example, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15% by mass, and may be within a range between any two of the values ​​exemplified here.

[0023] A chloroprene polymer according to one embodiment of the present invention may contain monomer units other than those derived from the chloroprene polymer and the monomer (A). The chloroprene polymer according to one embodiment of the present invention may contain 20% by mass or less of monomer units other than those derived from the chloroprene polymer and the monomer (A), based on 100% by mass of the chloroprene polymer. The content of the monomer units derived from the monomer (A) may be, for example, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or 20% by mass, and may be within a range between any two of the values ​​exemplified here.

[0024] The chloroprene-based polymer according to one embodiment of the present invention may be a random copolymer or a block copolymer. When the chloroprene-based polymer according to one embodiment of the present invention is a random copolymer, the chloroprene-based polymer may be a random copolymer containing chloroprene monomer units and monomer units derived from a monomer containing an epoxy group, or a random copolymer containing chloroprene monomer units, monomer units derived from a monomer containing an epoxy group, and monomer units derived from monomer (A). The chloroprene-based polymer may be a random copolymer containing chloroprene monomer units and monomer units derived from a monomer containing an epoxy group, or a random copolymer containing chloroprene monomer units, monomer units derived from a monomer containing an epoxy group, and monomer units derived from monomer (A).

[0025] When the chloroprene polymer according to one embodiment of the present invention is a block copolymer, the chloroprene polymer may be a chloroprene block copolymer containing a polymer block (A) and a chloroprene polymer block (B). Here, the polymer block (A) may contain monomer units derived from the monomer (A), and the chloroprene polymer block (B) may contain chloroprene monomer units. The chloroprene polymer according to one embodiment of the present invention includes the polymer block (A) containing monomer units derived from the monomer (A) whose glass transition temperature is equal to or higher than a specific temperature upon homopolymerization, thereby further improving the mechanical strength of a molded article containing the chloroprene polymer.

[0026] The polymer block (A) according to one embodiment of the present invention contains a monomer unit derived from the monomer (A) and may contain one or more types of monomer units derived from the monomer (A). The monomer units derived from the monomer (A) are as described above. Furthermore, the polymer block (A) may contain a monomer unit other than the monomer unit derived from the monomer (A), as long as the object of the present invention is not impaired. The polymer block (A) may contain a monomer unit derived from a monomer containing an epoxy group. The polymer block (A) may not contain a monomer unit derived from a monomer containing an epoxy group. When the polymer block (A) does not contain a monomer unit derived from a monomer containing an epoxy group, the chloroprene polymer block (B) may contain a monomer unit derived from a monomer containing an epoxy group.

[0027] The polymer block (A) can contain 70% by mass or more of monomer units derived from the monomer (A) when the polymer block (A) is taken as 100% by mass. The content of the monomer units derived from the monomer (A) is, for example, 70, 75, 80, 85, 90, 95, or 100% by mass, and may be within a range between any two of the values ​​exemplified here. The polymer block (A) can also be composed of monomer units derived from the monomer (A).

[0028] The number-average molecular weight of the polymer block (A) is preferably 10,000 or more from the viewpoint of the mechanical properties and moldability of the resulting chloroprene polymer. 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, or 100,000, and may be within a range between any two of the numerical values ​​exemplified here.

[0029] The molecular weight distribution of the polymer block (A) is preferably 2.00 or less from the viewpoint of moldability of the resulting chloroprene polymer. The molecular weight distribution of the polymer block (A) is, for example, 1.10, 1.20, 1.30, 1.40, 1.50, 1.60, 1.70, 1.80, 1.90, or 2.00, and may be within a range between any two of the values ​​exemplified here. The number average molecular weight and molecular weight distribution of the polymer block (A) can be polystyrene-equivalent values ​​measured by gel permeation chromatography (GPC), and can be measured by the method described in the examples.

[0030] The glass transition temperature of the polymer block (A) is, for example, 80, 85, 90, 95, 100, 105, 110, 120, 130, 140, or 150° C., and may be within a range between any two of the values ​​exemplified here. The glass transition temperature of the polymer block (A) 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.

[0031] The chloroprene polymer block (B) contains chloroprene monomer units derived from a chloroprene monomer (2-chloro-1,3-butadiene). The chloroprene polymer block (B) preferably contains monomer units derived from a monomer containing an epoxy group.

[0032] The chloroprene polymer block (B) may contain 5.0% by mass or less of monomer units derived from a monomer containing an epoxy group, based on 100% by mass of the chloroprene polymer block (B). The content of the monomer units derived from a monomer containing an epoxy group is, for example, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0% by mass, and may be within a range between any two of the values ​​exemplified here.

[0033] The chloroprene polymer block (B) may have a structure derived from a monomer unit other than the chloroprene monomer unit and the monomer unit derived from the epoxy group-containing monomer, as long as the object of the present invention is not impaired. The monomer other than the chloroprene monomer is not particularly limited as long as it is copolymerizable with the chloroprene monomer, and examples thereof include esters of (meth)acrylic acid (methyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, etc.), hydroxyalkyl (meth)acrylates (2-hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, etc.), 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, butadiene, isoprene, unsaturated nitrile, ethylene, styrene, sulfur, etc.

[0034] The chloroprene polymer block (B) according to one embodiment of the present invention may contain 75% by mass or more of chloroprene monomer units, based on 100% by mass of the chloroprene polymer block (B). The content of the chloroprene monomer units may be, for example, 75, 80, 85, 90, 95, or 100% by mass, or may be within a range between any two of the values ​​exemplified here.

[0035] The chloroprene polymer according to one embodiment of the present invention has an epoxy equivalent within a specific range and further contains the polymer block (A) and the chloroprene polymer block (B). This enables the flexibility and mechanical properties of a molded article obtained by a low-temperature heat treatment to be further improved.

[0036] The chloroprene polymer block (B) according to one embodiment of the present invention may contain 20% by mass or less of other monomer units than chloroprene monomer units and monomer units derived from epoxy group-containing monomers, when the chloroprene polymer block (B) is taken as 100% by mass. The content of other monomer units than chloroprene monomer units and monomers containing epoxy groups is, for example, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or 20% by mass, and may be within a range between any two of the values ​​exemplified here.

[0037] In a chloroprene polymer according to one embodiment of the present invention, the polymer block (A) and / or the chloroprene polymer block (B) may contain monomer units derived from a monomer containing an epoxy group. From the viewpoint of achieving both a moderate elongation at 500% elongation and high tensile strength at break at a higher level, it is preferred that the chloroprene polymer block (B) contains monomer units derived from a monomer containing an epoxy group. In addition, in a chloroprene polymer according to one embodiment of the present invention, only the chloroprene polymer block (B) may contain monomer units derived from a monomer containing an epoxy group.

[0038] A chloroprene polymer according to one embodiment of the present invention may contain 15.0% by mass or less of polymer block (A), preferably 3.0 to 15.0% by mass, of polymer block (A) relative to 100% by mass of the chloroprene polymer. The content of polymer block (A) may be, for example, 0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0, or 15.0% by mass, or may be within a range between any two of the values ​​exemplified here. When the content of polymer block (A) is equal to or greater than the lower limit, the tensile strength at break of the resulting dip-molded article containing the chloroprene polymer is further improved. When the content of polymer block (A) is equal to or less than the upper limit, the elongation at break of the resulting dip-molded article containing the chloroprene polymer is further improved.

[0039] The chloroprene polymer according to one embodiment of the present invention preferably contains 85% by mass or more of the chloroprene polymer block (B) relative to 100% by mass of the chloroprene polymer, and may contain, for example, 85, 90, 95, 96, 97, 98, 99, or 100% by mass, or may be within a range between any two of the numerical values ​​exemplified herein. The chloroprene polymer according to one embodiment of the present invention preferably contains 70 to 100% by mass in total of the polymer block (A) and the chloroprene polymer block (B) relative to 100% by mass of the chloroprene polymer, and may be, for example, 70, 75, 80, 85, 90, 95, or 100% by mass, or may be within a range between any two of the numerical values ​​exemplified herein.

[0040] A chloroprene-based polymer according to one embodiment of the present invention may be composed of a polymer block (A) and a chloroprene-based polymer block (B), and may not contain any other polymer blocks. The chloroprene-based polymer may be a diblock copolymer of the polymer block (A) and the chloroprene-based polymer block (B).

[0041] The chloroprene polymer 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).

[0042]

[0043] In chemical formula (1), R １ represents any one of hydrogen, chlorine, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted mercapto group, and a substituted or unsubstituted heterocyclyl group.

[0044]

[0045] The functional group having the structure represented by chemical formula (1) or chemical formula (2) can be introduced by carrying out a polymerization step of a chloroprene polymer, for example, a polymerization step described below, in the presence of a RAFT agent. Compounds that can be used to introduce the functional group having the structure represented by chemical formula (1) or chemical formula (2) will be described later in the section on production methods.

[0046] The number-average molecular weight of the chloroprene polymer is not particularly limited, but from the viewpoint of moldability, it is preferably 50,000 to 800,000, and particularly preferably 100,000 to 600,000. The number-average molecular weight of the chloroprene polymer is, for example, 50,000, 100,000, 150,000, 200,000, 250,000, 300,000, 350,000, 400,000, 450,000, 500,000, 550,000, 600,000, 650,000, 700,000, 750,000, or 800,000, and may be within a range between any two of the numerical values ​​exemplified here.

[0047] 1.2 Physical Properties of Chloroprene Polymer (Tensile Strength at Break) The chloroprene polymer according to one embodiment of the present invention preferably has a tensile strength at break of 17.0 MPa or more, measured in accordance with JIS K 6251 on a test molded article obtained by heat-treating a molded article of a chloroprene polymer latex composition containing the chloroprene polymer at 80°C for 30 minutes. The tensile strength at break is, for example, 17.0, 18.0, 19.0, 20.0, 21.0, 22.0, 23.0, 24.0, 25.0, 26.0, 27.0, 28.0, 29.0, or 30.0 MPa, and may be within a range between any two of the values ​​exemplified here.

[0048] (Elongation at Break) In the chloroprene polymer according to one embodiment of the present invention, a test molded article obtained by heat-treating a molded article of a chloroprene polymer latex composition containing the chloroprene polymer at 80°C for 30 minutes preferably has an elongation at break of 800% or more as measured in accordance with JIS K 6251. The elongation at break is, for example, 800, 900, 1000, 1100, 1200, 1300, 1400, or 1500%, and may be within a range between any two of the values ​​exemplified here.

[0049] (Stress at 500% Elongation) In the chloroprene polymer according to one embodiment of the present invention, a molded article of a chloroprene polymer latex composition containing the chloroprene polymer is heat-treated at 80°C for 30 minutes, and the resulting test molded article preferably has a stress at 500% elongation of 4.0 MPa or less, as measured in accordance with JIS K 6251. The stress at 500% elongation is, for example, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, or 4.0 MPa, and may be within a range between any two of the values ​​exemplified here.

[0050] The test molded body can be obtained by adding a curing agent (hexanediol) to 100 parts by mass (solid content equivalent) of a chloroprene polymer, mixing the mixture using a Magstick stirrer at 20°C for 30 minutes, and then pouring the resulting chloroprene polymer latex composition into a mold, drying it for 3 days, and molding the resulting molded body. The amount of curing agent can be adjusted based on the epoxy equivalent of the chloroprene polymer, for example, 0.2 to 5.0 parts by mass per 100 parts by mass of the solid content of the chloroprene polymer. For example, the test molded body can be one of the formulations shown in Examples (e.g., the formulation of Example 1 or Example 3). The test molded body can be one that does not contain a vulcanizing agent or vulcanization accelerator. Specifically, the test molded body can be obtained by the method described in the Examples. The tensile strength at break, elongation at break, and hardness of the test molded body can be adjusted by controlling the type and amount of raw materials used and the polymerization conditions during the production of the chloroprene polymer.

[0051] 2. Method for Producing Chloroprene Polymer The method for producing the chloroprene polymer according to the present invention is not particularly limited, but the chloroprene polymer can be obtained, for example, by the following production method. The method for producing a chloroprene polymer according to one embodiment of the present invention may include a polymerization step of polymerizing raw material monomers including chloroprene and a monomer having an epoxy group to obtain the chloroprene polymer.

[0052] <Polymerization Step> The polymerization method is not particularly limited, and the polymer can be produced by known methods such as solution polymerization, emulsion polymerization, and bulk polymerization, but emulsion polymerization is preferred. In the polymerization step, raw material monomers can be emulsion-polymerized using an emulsifier, a dispersant, a polymerization initiator, a RAFT agent, a reducing agent, and the like, as appropriate. In the polymerization step, a polymerization terminator can be added when a target polymerization rate is reached, thereby obtaining a chloroprene polymer latex. After the polymerization step, unreacted monomers may be removed by a concentration method such as vacuum distillation.

[0053] (Raw Material Monomers) The raw material monomers are preferably blended so that the chloroprene polymer has the composition described above.

[0054] (Emulsifier) ​​The emulsifier used in the polymerization is not particularly limited, but anionic and / or nonionic emulsifiers are preferred from the viewpoint of emulsion stability. In particular, rosin acid and / or alkali metal rosinate salts are preferred because they can provide the resulting chloroprene polymer with appropriate strength and prevent excessive shrinkage and breakage. The concentration of the emulsifier can be 3 to 50 parts by mass per 100 parts by mass of the raw material monomers from the viewpoint of efficient polymerization reaction.

[0055] The emulsifier may also include emulsifiers and dispersants other than rosin acid and alkali metal rosinate. In one embodiment of the present invention, the emulsifier used in the emulsion polymerization step may include rosin acid and / or alkali metal rosinate, and an anionic emulsifier or dispersant. As the anionic emulsifier or dispersant, it is preferable to use a sulfate- or sulfonate-based anionic emulsifier or dispersant in combination, from the viewpoint of stabilizing the chloroprene polymer latex when a pH adjuster is added. Specific examples include alkyl sulfonates having 8 to 20 carbon atoms, alkyl aryl sulfates, condensates of sodium naphthalene sulfonate and formaldehyde, and sodium alkyl diphenyl ether disulfonate.

[0056] (Initiator) As the radical polymerization initiator, known radical polymerization initiators can be used, and examples thereof include potassium persulfate, benzoyl peroxide, hydrogen peroxide, and azo compounds.

[0057] (RAFT Agent) In the production method according to one embodiment of the present invention, a RAFT agent can be used, and the terminal structure represented by chemical formula (1) or chemical formula (2) can be introduced into the chloroprene polymer by carrying out polymerization in the presence of a known RAFT agent.

[0058]

[0059] In chemical formula (1), R １ represents any one of hydrogen, chlorine, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted mercapto group, and a substituted or unsubstituted heterocyclyl group.

[0060]

[0061] The compound leading to the structure represented by the above chemical formula (1) is not particularly limited, and general compounds can be used, such as dithiocarbamates and dithioesters. Specific examples include benzyl 1-pyrrolecarbodithioate (common name: benzyl 1-pyrroledithiocarbamate), benzylphenylcarbodithioate, 1-benzyl-N,N-dimethyl-4-aminodithiobenzoate, 1-benzyl-4-methoxydithiobenzoate, 1-phenylethylimidazolecarbodithioate (common name: 1-phenylethylimidazoledithiocarbamate), benzyl-1-(2-pyrrolidinone)carbodithioate, and the like. benzyl phthalimidyl carbodithioate, (common name: benzyl phthalimidyl dithiocarbamate), 2-cyanoprop-2-yl-1-pyrrole carbodithioate, (common name: 2-cyanoprop-2-yl-1-pyrrole dithiocarbamate), 2-cyanoprop-2-yl-1-pyrrole carbodithioate, (common name: 2-cyanoprop-2-yl-1-pyrrole dithiocarbamate), 2-cyanobut-2-yl-1-pyrrole carbodithioate, (common name: 2-cyanobut-2-yl- 1-pyrrole dithiocarbamate), benzyl-1-imidazolecarbodithioate, (trivial name benzyl-1-imidazole dithiocarbamate), 2-cyanoprop-2-yl-N,N-dimethyldithiocarbamate, benzyl-N,N-diethyldithiocarbamate, cyanomethyl-1-(2-pyrrolidone)dithiocarbamate, 2-(ethoxycarbonylbenzyl)prop-2-yl-N,N-diethyldithiocarbamate, 1-phenyl nylethyl dithiobenzoate, 2-phenylprop-2-yldithiobenzoate, 1-acetate-1-yl-ethyl dithiobenzoate, 1-(4-methoxyphenyl)ethyl dithiobenzoate, benzyl dithioacetate, ethoxycarbonylmethyl dithioacetate, 2-(ethoxycarbonyl)prop-2-yldithiobenzoate, 2-cyanoprop-2-yldithiobenzoate, tert-butyl dithiobenzoate, 2,4,4-Trimethylpent-2-yldithiobenzoate, 2-(4-chlorophenyl)-prop-2-yldithiobenzoate, 3-vinylbenzyl dithiobenzoate, 4-vinylbenzyl dithiobenzoate, benzyl diethoxyphosphinyldithioformate, tert-butyl trithioperbenzoate, 2-phenylprop-2-yl-4-chlorodithiobenzoate, naphthalene-1-carboxylic acid-1-methyl-1-phenyl-ethyl ester, 4-cyano-4-methyl-4-thiobenzylsulfanylbutyric acid, dibenzyl tetrathioterephthalate, carboxymethyl dithiobenzoate, poly(ethylene oxide) with dithiobenzoate end groups, poly(ethylene oxide) with 4-cyano-4-methyl-4-thiobenzylsulfanylbutyric acid end groups, 2-[(2-phenylethanethioyl)sulfanyl]propanoic acid, 2-[(2-phenylethanethioyl)sulfanyl]succinic acid , 3,5-dimethyl-1H-pyrazole-1-carbodithioate potassium, cyanomethyl-3,5-dimethyl-1H-pyrazole-1-carbodithioate, cyanomethyl-N-methyl-N-phenyldithiocarbamate, benzyl-4-chlorodithiobenzoate, phenylmethyl-4-chlorodithiobenzoate, 4-nitrobenzyl-4-chlorodithiobenzoate, phenylprop-2-yl-4-chlorodithiobenzoate, 1-cyano Examples of suitable chlorodithiobenzoates include 1-methylethyl-4-chlorodithiobenzoate, 3-chloro-2-butenyl-4-chlorodithiobenzoate, 2-chloro-2-butenyldithiobenzoate, benzyl dithioacetate, 3-chloro-2-butenyl-1H-pyrrole-1-dithiocarboxylic acid, 2-cyanobutan-2-yl 4-chloro-3,5-dimethyl-1H-pyrazole-1-carbodithioate, and cyanomethylmethyl(phenyl)carbamodithioate. Of these, benzyl 1-pyrrolecarbodithioate and benzylphenylcarbodithioate are particularly preferred.

[0062] The compound leading to the structure represented by the above chemical formula (2) is not particularly limited, and a general compound can be used, for example, 2-cyano-2-propyldodecyltrithiocarbonate, dibenzyltrithiocarbonate, butylbenzyltrithiocarbonate, 2-[[(butylthio)thioxomethyl]thio]propionic acid, 2-[[(dodecylthio)thioxomethyl]thio]propionic acid, 2-[[(butylthio)thioxomethyl]thio]succinic acid, 2-[[(dodecylthio)thioxomethyl]thio]succinic acid, 2-[[(dodecylthio)thioxomethyl]thio] ]-2-methylpropionic acid, 2,2'-[carbonothioylbis(thio)]bis[2-methylpropionic acid], 2-amino-1-methyl-2-oxoethylbutyl trithiocarbonate, benzyl 2-[(2-hydroxyethyl)amino]-1-methyl-2-oxoethyltrithiocarbonate, 3-[[[(tert-butyl)thio]thioxomethyl]thio]propionic acid, cyanomethyldodecyltrithiocarbonate, diethylaminobenzyl trithiocarbonate, dibutylaminobenzyl trithiocarbonate, and other trithiocarbonates are particularly preferred.

[0063] The amount of the RAFT agent added can be 0 to 10 parts by mass relative to 100 parts by mass of the raw material monomer, for example, 0, 0.1, 0.2, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 parts by mass, and may be within a range between any two of the numerical values ​​exemplified here.

[0064] In the polymerization step, sodium hydroxide and / or potassium hydroxide can be used. In addition, in the polymerization step, a reducing agent can be added. Examples of the reducing agent include potassium pyrosulfite, potassium sulfite, potassium hydrogen sulfite, potassium phosphate, potassium hydrogen phosphate, sodium hydrogen sulfite, sodium sulfate, and thiourea dioxide.

[0065] (Polymerization Conditions) From the viewpoint of ease of polymerization control, the polymerization temperature is preferably 10 to 50°C. The polymerization reaction is terminated by adding a polymerization terminator. Examples of polymerization terminators include thiodiphenylamine, 4-tert-butylcatechol, and 2,2'-methylenebis-4-methyl-6-tert-butylphenol. After completion of polymerization, unreacted monomers can be removed by a conventional method such as vacuum distillation.

[0066] To the latex containing a chloroprene polymer obtained in the polymerization step, a freezing stabilizer, an emulsion stabilizer, a viscosity modifier, an antioxidant, a preservative, etc. may be optionally added after polymerization within a range that does not impair the object of the present invention.

[0067] <Recovery Step> The method for recovering the chloroprene polymer from the chloroprene polymer-containing latex is not particularly limited, and known methods can be used, such as a method of recovering the chloroprene polymer by immersing the polymer in a coagulation liquid or a method of precipitating the polymer using a poor solvent such as methanol.

[0068] When the chloroprene polymer according to one embodiment of the present invention is a chloroprene block copolymer, the method for producing the chloroprene polymer can include a polymerization step 1 in which raw material monomers including monomer (A) are polymerized to obtain polymer block (A), and a polymerization step 2 in which raw material monomers including chloroprene and a monomer containing an epoxy group are polymerized to obtain a chloroprene block copolymer including chloroprene polymer block (B), and the chloroprene polymer can be produced by a production method involving two polymerization steps. Hereinafter, a production method in which the chloroprene polymer is a chloroprene block copolymer will be described, focusing on the differences from the above-mentioned polymerization steps.

[0069] The polymerization mode is not particularly limited and is as described above. In each polymerization step, the raw material monomers can be emulsion-polymerized using an emulsifier, a dispersant, a polymerization initiator, a RAFT agent, a reducing agent, and the like as appropriate. In addition, in polymerization step 2, a polymerization terminator can be added when the target polymerization rate is reached to obtain a chloroprene-based block copolymer latex. Furthermore, after the polymerization step, unreacted monomers may be removed by a concentration method such as vacuum distillation.

[0070] <Polymerization Step 1> In polymerization step 1, raw material monomers including monomer (A) are polymerized to obtain polymer block (A). In one embodiment of the present invention, polymer block (A) can be synthesized by living radical polymerization of raw material monomers including monomer (A). The raw material monomers are preferably blended so that the composition of polymer block (A) is as described above, and the type and blending amount of monomer (A) in polymer block (A) are as described above. The glass transition temperature of the polymer block (A) obtained here is, for example, 80, 85, 90, 95, 100, 105, 110, 120, 130, 140, or 150°C, and may be within a range between any two of the values ​​exemplified here.

[0071] (Emulsifier) ​​The emulsifier used in the polymerization is not particularly limited, but preferably contains at least one selected from anionic and nonionic emulsifiers from the viewpoint of emulsion stability. In particular, it is preferable to use rosin acid and / or an alkali metal salt of rosin acid, because this can provide the resulting chloroprene polymer with appropriate strength and prevent excessive shrinkage and breakage. The concentration of the emulsifier can be 3 to 50 parts by mass per 100 parts by mass of the raw material monomers from the viewpoint of efficient polymerization reaction.

[0072] The emulsifier may also include emulsifiers and dispersants other than rosin acid and alkali metal rosinate. In one embodiment of the present invention, the emulsifier used in the emulsion polymerization step may include rosin acid and / or alkali metal rosinate, and an anionic emulsifier or dispersant. As the anionic emulsifier or dispersant, it is preferable to use a sulfate- or sulfonate-based anionic emulsifier or dispersant in combination, from the viewpoint of stabilizing the chloroprene polymer latex when a pH adjuster is added. Specific examples include alkyl sulfonates having 8 to 20 carbon atoms, alkyl aryl sulfates, condensates of sodium naphthalene sulfonate and formaldehyde, and sodium alkyl diphenyl ether disulfonate.

[0073] (Initiator) As the radical polymerization initiator, known radical polymerization initiators can be used, and examples thereof include potassium persulfate, benzoyl peroxide, hydrogen peroxide, and azo compounds.

[0074] (RAFT Agent) The type and amount of the RAFT agent are the same as those in the polymerization method described above.

[0075] In the polymerization step, sodium hydroxide and / or potassium hydroxide can be used. In addition, in the polymerization step, a reducing agent can be added. Examples of the reducing agent include potassium pyrosulfite, potassium sulfite, potassium hydrogen sulfite, potassium phosphate, potassium hydrogen phosphate, sodium hydrogen sulfite, sodium sulfate, and thiourea dioxide.

[0076] (Polymerization Conditions) The polymerization temperature may be appropriately determined depending on the type of monomer, but is preferably 10 to 100°C, and particularly preferably 20 to 90°C.

[0077] <Polymerization Step 2> In the polymerization step 2, a chloroprene monomer, a monomer containing an epoxy group, and the like are added to the latex containing the polymer block (A) obtained in the polymerization step 1, and polymerized to obtain a chloroprene block copolymer latex containing a chloroprene block copolymer containing a chloroprene polymer block (B).

[0078] The polymerization temperature in polymerization step 2 is preferably 10 to 50°C from the viewpoint of ease of polymerization control. The polymerization reaction is terminated by adding a polymerization terminator. Examples of polymerization terminators include thiodiphenylamine, 4-tert-butylcatechol, and 2,2'-methylenebis-4-methyl-6-tert-butylphenol. After completion of polymerization, unreacted monomers can be removed by a conventional method such as vacuum distillation.

[0079] To the latex containing the chloroprene-based block copolymer obtained in the polymerization step 2, a freezing stabilizer, an emulsion stabilizer, a viscosity modifier, an antioxidant, a preservative, etc. may be optionally added after polymerization within a range that does not impair the object of the present invention.

[0080] <Recovery Step> The recovery step is as described above.

[0081] 3. Chloroprene Polymer Latex The chloroprene polymer latex according to one embodiment of the present invention can contain the above-described chloroprene polymer and water. The liquid obtained at the end of polymerization by the polymerization method described in the above production method can be used as a chloroprene polymer latex as it is. Alternatively, the recovered chloroprene polymer can be forcibly emulsified using an emulsifier to obtain a chloroprene polymer latex.

[0082] 4. Chloroprene Polymer Latex Composition and Rubber Composition The chloroprene polymer latex composition according to one embodiment of the present invention contains the chloroprene polymer latex described above and may further contain a curing agent. The chloroprene polymer latex composition according to one embodiment of the present invention may also contain an antioxidant. A dip-molded article can be obtained by immersing the chloroprene polymer latex composition in a coagulation liquid and molding it. The rubber composition according to one embodiment of the present invention may contain the chloroprene polymer described above and may further contain a curing agent. The rubber composition can be molded by any method to obtain a molded article.

[0083] The chloroprene polymer latex composition and the rubber composition according to one embodiment of the present invention contain a chloroprene polymer and may contain other components depending on the purpose or application. Examples of raw materials that may be contained in the chloroprene polymer latex composition and the rubber composition include a vulcanizing agent, a vulcanization accelerator, a filler or a reinforcing agent, a plasticizer, a processing aid or lubricant, an antioxidant, a silane coupling agent, and a surfactant.

[0084] <Curing Agent> The curing agent is water-soluble or water-dispersible, may have two or more reactive functional groups, and preferably has the function of crosslinking the epoxy groups contained in the chloroprene polymer. The reactive functional groups contained in the curing agent preferably include at least one of a hydroxyl group, an isocyanate group, and an amino group. A chloroprene polymer latex composition according to one embodiment of the present invention may contain 0.2 to 5.0 parts by mass of a curing agent per 100 parts by mass of the solid content of the chloroprene polymer. The content of the curing agent may be, for example, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0, or may be within a range between any two of the values ​​exemplified here. The amount of curing agent added can be adjusted according to the epoxy equivalent of the chloroprene polymer.

[0085] The curing agent may include one or more of polyols, polyisocyanates, and polyamines. Examples of polyols include diols, triols, and polyols having four or more hydroxyl groups. Examples of diols include ethylene glycol, propanediol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, naphthalenediol, isomers thereof, hydroquinone, catechol, and resorcinol. Examples of triols include glycerin, 1,2,3-butanetriol, 1,2,4-butanetriol, benzenetriol, benzenetetraol, and isomers thereof. Other polyols include the MACRYNAL series (MACRYNAL VSM 2521w / 42WAB, VSM 6299w / 42WA, SM 6810w / 42WA, SM 6826w / 43WA, etc.) manufactured by Daicel Allnex Co., Ltd. Polyisocyanates include the Aquanate series (Aquanate 105, 130, 140, 200, 210, etc.) manufactured by Tosoh Corporation. Examples of polyamines include the Tomide series (Tomide TXS-53-C, TXH-674-B, etc.) and the Fujicure series (Fujicure FXH-927, FXH-935, FXH-940, FXH-941, FXH-919, FXH-918-FA, etc.), manufactured by T&K TOKA Corporation.

[0086] The chloroprene polymer latex composition and the rubber composition according to one embodiment of the present invention contain a curing agent, and therefore, even if the amounts of a vulcanizing agent and a vulcanization accelerator used are small, a molded article that satisfies both a suitable elongation at 500% elongation and high tensile strength at break can be obtained by heat treatment at a low temperature.

[0087] <Antiaging Agent> The chloroprene polymer latex composition and the rubber composition according to one embodiment of the present invention may contain an antioxidant. The chloroprene polymer latex composition according to one embodiment of the present invention may contain 0.5 to 5.0 parts by mass of the antioxidant per 100 parts by mass of the solid content of the chloroprene polymer. The content of the antioxidant is, for example, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0 parts by mass, and may be within a range between any two of the values ​​exemplified here.

[0088] Antiaging agents are used to improve the heat resistance of rubber compositions. They include primary antioxidants, which trap radicals to prevent autoxidation, and secondary antioxidants, which neutralize hydroperoxides. Examples of primary antioxidants include phenol-based antioxidants, amine-based antioxidants, acrylate-based antioxidants, imidazole-based antioxidants, metal carbamates, and waxes. Examples of secondary antioxidants include phosphorus-based antioxidants, sulfur-based antioxidants, and imidazole-based antioxidants. Examples of antioxidants include, but are not limited to, N-phenyl-1-naphthylamine, alkylated diphenylamine, octylated diphenylamine, 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, p-(p-toluenesulfonylamido)diphenylamine, N,N'-di-2-naphthyl-p-phenylenediamine, N,N'-diphenyl-p-phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine, N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine, N-phenyl-N'-(3-methacryloyloxy-2-hydroxypropyl)-p-phenylenediamine, 1,1,3-tris-(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 4,4'-butylidenebis-(3-methyl-6-t-butylphenol), 2,2-thiobis(4- methyl-6-t-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-hydroxybenzyl-phosphonate-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 bis(2-methyl-4-di-tridecylphosphite-5-t-butylphenyl)butane, 4,4'-butylidenebis-(3-methyl-6-t-butyl-di-tridecylphosphite), 2,2'-ethylidenebis(4,6-di-t-butylphenol)fluorophosphite, 4,4'-isopropylidene-diphenol alkyl (C12-C15) phosphite, cyclic neopentanetetraylbis(2,4-di-t-butylphenyl phosphite), cyclic neopentanetetraylbis(2,6-di-t-butyl-4-phenyl phosphite), cyclic neopentanetetraylbis(nonylphenyl phosphite), bis(nonylphenyl)pentaerythritol diphosphite, dibutyl hydrogen phosphite, distearyl pentaerythritol diphosphite, hydrogenated bisphenol A pentaerythritol phosphite polymer, 2-mercaptobenzimidazole, butylated reaction product of p-cresol and dicyclopentadiene, etc.

[0089] <Vulcanizing Agent and Vulcanization Accelerator> The chloroprene polymer latex composition and rubber composition according to one embodiment of the present invention may contain a vulcanizing agent and / or a vulcanization accelerator. The chloroprene polymer latex composition and rubber composition according to one embodiment of the present invention may not contain sulfur or the aforementioned thiuram-based, dithiocarbamate-based, thiourea-based, guanidine-based, xanthogenate-based, thiazole-based, or other vulcanization accelerators. That is, the chloroprene polymer latex composition and rubber composition include those containing a vulcanizing agent but not a vulcanization accelerator, those containing no vulcanizing agent but a vulcanization accelerator, those containing a vulcanizing agent and a vulcanization accelerator, and those containing no vulcanizing agent or a vulcanization accelerator. Whether or not a vulcanizing agent and a vulcanization accelerator are added may be determined depending on the desired dip-molded article or molded article.

[0090] 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 polymer contained in the chloroprene polymer latex composition. The amount of vulcanizing agent added can be, for example, 0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0, and may be within a range between any two of the values ​​exemplified here.

[0091] A vulcanization accelerator is a chemical added during the vulcanization of raw rubber to act with the vulcanizing agent to increase the vulcanization speed, thereby shortening the vulcanization time, lowering the vulcanization temperature, reducing the amount of vulcanizing agent, and improving the physical properties of the vulcanized rubber. It usually refers to a chemical that accelerates the sulfur vulcanization reaction.

[0092] Examples of vulcanization accelerators include, but are not limited to, thiuram-based, dithiocarbamate-based, thiourea-based, guanidine-based, xanthogenate-based, thiazole-based, etc. These may be used alone or in combination of two or more types as required.

[0093] Examples of thiuram vulcanization accelerators include tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, tetrakis(2-ethylhexyl)thiuram disulfide, tetramethylthiuram monosulfide, and dipentamethylenethiuram tetrasulfide.

[0094] Examples of the dithiocarbamate vulcanization accelerator include sodium dibutyldithiocarbamate, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc N-ethyl-N-phenyldithiocarbamate, zinc N-pentamethylenedithiocarbamate, copper dimethyldithiocarbamate, ferric dimethyldithiocarbamate, and tellurium diethyldithiocarbamate, and zinc dibutyldithiocarbamate is particularly preferred.

[0095] Examples of the thiourea-based vulcanization accelerator include ethylene thiourea, N,N'-diethyl thiourea, trimethyl thiourea, and N,N'-diphenyl thiourea.

[0096] Examples of the guanidine vulcanization accelerator include 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, and di-o-tolylguanidine salts of dicatechol borate.

[0097] Examples of xanthogenate-based vulcanization accelerators include zinc butylxanthogenate and zinc isopropylxanthogenate.

[0098] Examples of the thiazole vulcanization accelerator include 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, 2-mercaptobenzothiazole zinc salt, 2-mercaptobenzothiazole cyclohexylamine salt, and 2-(4'-morpholinodithio)benzothiazole.

[0099] The amount of the vulcanization accelerator added can be 0 to 5.0 parts by mass per 100 parts by mass of the solid content of the chloroprene polymer contained in the chloroprene polymer latex composition. The amount of the 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 a range between any two of the numerical values ​​exemplified here. In the chloroprene polymer latex composition and rubber composition according to one embodiment of the present invention, the total content of the vulcanizing agent and the vulcanization accelerator per 100 parts by mass of the solid content of the chloroprene polymer latex (or the total content of the vulcanizing agent and the vulcanization accelerator per 100 parts by mass of the chloroprene polymer contained in the rubber composition) can be 5.0 parts by mass or less. The total content of the vulcanizing agent and vulcanization accelerator is, 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 a range between any two of the values ​​exemplified here. Even without containing a vulcanizing agent or a vulcanization accelerator, the rubber composition has a moderate elongation at 500% elongation and high tensile strength at break. Therefore, from the viewpoints of reducing allergies and reducing costs, the rubber composition may be free of a vulcanizing agent or a vulcanization accelerator.

[0100] 5. Dip-molded article and molded article A dip-molded article according to one embodiment of the present invention can be a dip-molded article of the chloroprene polymer latex composition. Also, a molded article according to one embodiment of the present invention can be a molded article of the rubber composition. The dip-molded article can be suitably used for gloves, balloons, catheters, and boots, and the molded article can be suitably used for intermediate coatings for automobiles, etc.

[0101] (Tensile Strength at Break) The molded article and dip-molded article according to one embodiment of the present invention preferably have a tensile strength at break of 17.0 MPa or more as measured in accordance with JIS K 6251. The tensile strength at break is, for example, 17.0, 18.0, 19.0, 20.0, 21.0, 22.0, 23.0, 24.0, 25.0, 26.0, 27.0, 28.0, 29.0, or 30.0 MPa, and may be within a range between any two of the values ​​exemplified here.

[0102] (Elongation at Break) The molded article and dip-molded article according to one embodiment of the present invention preferably have an elongation at break of 1900% or more, measured in accordance with JIS K 6251. The elongation at break is preferably, for example, 800% or more. The elongation at break may be, for example, 800, 900, 1000, 1100, 1200, 1300, 1400, or 1500%, or may be within a range between any two of the values ​​exemplified here.

[0103] (Stress at 500% Elongation) The molded article and dip-molded article according to one embodiment of the present invention preferably have a stress at 500% elongation of 4.0 MPa or less, measured in accordance with JIS K 6251. The stress at 500% elongation is, for example, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, or 4.0 MPa, and may be within a range between any two of the values ​​exemplified here.

[0104] 6. Dip-molded article and method for producing a molded article A method for producing a dip-molded article according to one embodiment of the present invention may include a dip-molding step of dip-molding the chloroprene polymer latex composition to obtain a dip-molded article, and a heat-treatment step. Also, a method for producing a molded article according to one embodiment of the present invention may include a molding step of molding the chloroprene polymer latex composition and / or the rubber composition by any method, and a heat-treatment step.

[0105] Examples of dip-molding methods according to one embodiment of the present invention include the immersion coagulation method, simple immersion method, thermal immersion method, and electrodeposition method. The immersion coagulation method can be used from the viewpoints of ease of production and the ease of obtaining a dip-molded product of a uniform thickness. Specifically, a ceramic mold coated with a calcium-based coagulation liquid is immersed in a chloroprene polymer latex composition to coagulate the chloroprene polymer latex composition. Water-soluble impurities are then removed by leaching, followed by drying. A dip-molded film (rubber film) is then formed by heating, and the dip-molded film is then demolded. This allows for the production of a film-like dip-molded product.

[0106] A molding method according to one embodiment of the present invention may include, for example, a step of pouring the chloroprene polymer latex composition and / or the rubber composition into a mold or other suitable container, drying the composition, and obtaining a molded product (e.g., a film).

[0107] The dip molded body and the method for manufacturing the molded body according to one embodiment of the present invention may include a heat treatment step of heat treating the dip molded body and the molded body.

[0108] The heat treatment temperature may be set appropriately depending on the composition of the chloroprene polymer, and may be 20 to 180°C. The heating temperature is preferably 70 to 120°C. The heating temperature may be, for example, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, or 180°C, or may be within a range between any two of the values ​​exemplified here. The heating time may be set appropriately depending on the composition, shape, etc. of the chloroprene polymer, and may be 0 to 300 minutes. The heating time may 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, or may be within a range between any two of the values ​​exemplified here. As an example, a dip-molded body according to one embodiment of the present invention may be heat-treated at 80°C for 30 minutes.

[0109] The present invention will be described in more detail below based on examples, but the present invention should not be construed as being limited to these examples.

[0110] Example 1 (Polymerization Step) Synthesis of Chloroprene Polymer Polymerization was carried out using a 10 L autoclave equipped with a stirrer and a heating / cooling jacket. 3922 g of purified water, 174 g of disproportionated potassium rosinate (manufactured by Harima Chemicals, Inc.), 174 g of potassium hydroxide, 19.6 g of sodium salt of β-naphthalenesulfonic acid formalin condensate (manufactured by Kao Corporation, trade name: Demol N), 5.10 g of butylbenzyl trithiocarbonate, 3412 g of chloroprene monomer, and 88.0 g of glycidyl methacrylate (GMA) were charged, the internal temperature was raised to 45°C, and the autoclave was stirred at 200 rpm under a nitrogen stream. 3.20 g of potassium persulfate (manufactured by ADEKA Corporation) was added as a polymerization initiator to initiate polymerization. When the polymerization rate of the chloroprene monomer reached 80%, a 10 wt % aqueous solution of N,N-diethylhydroxylamine, which was a polymerization terminator, was added to terminate the polymerization, and unreacted chloroprene monomer was removed by distillation under reduced pressure to obtain a latex containing a chloroprene polymer. 20 ml of the obtained latex was sampled for measuring physical properties, and the remaining latex was used to prepare a film for evaluation.

[0111] The sampled latex was mixed with a large amount of methanol to precipitate the resin, which was then filtered and dried to obtain a chloroprene polymer sample. The epoxy equivalent and number average molecular weight were determined by analysis. The analytical results are shown in Table 1. The measurement methods will be described later.

[0112] Example 2, Comparative Example 1 A latex containing a chloroprene polymer was obtained in the same manner as in Example 1, except that the amounts of chloroprene monomer and glycidyl methacrylate (GMA) charged were as shown in Tables 1 and 2.

[0113] Example 3 (Polymerization Step 1) Synthesis of Polymer Block (A) Polymerization was carried out using a 10 L autoclave equipped with a stirrer and a heating / cooling jacket. 3,419 g of pure water, 151 g of disproportionated potassium rosinate (manufactured by Harima Chemicals Group Co., Ltd.), 2.16 g of potassium hydroxide, 17.1 g of sodium salt of β-naphthalenesulfonic acid formalin condensate (manufactured by Kao Corporation, product name: Demol N), 332 g of styrene monomer, and 5.91 g of butylbenzyl trithiocarbonate were charged, and the internal temperature was raised to 80°C and the mixture was stirred at 200 rpm under a nitrogen stream. 3.72 g of 2,2'-azobis[2-(2-imidazolin-2-yl)propane]dihydrogen chloride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., product name: VA-044) was added as a polymerization initiator to initiate polymerization. For measuring physical properties, 20 ml of the obtained latex was sampled, and the remaining latex was used in the polymerization step 2.

[0114] The sampled latex was mixed with a large amount of methanol to precipitate the resin, which was then filtered and dried to obtain a sample of polymer block (A). The number average molecular weight, molecular weight distribution, and glass transition temperature of the polymer block (A) were determined by analysis of the obtained sample. The measurement methods will be described later.

[0115] (Polymerization Step 2) Synthesis of Chloroprene-Based Polymer Block (B) After polymerization step 1, when the internal temperature decreased to 45°C, 3,492 g of chloroprene monomer and 108 g of glycidyl methacrylate (GMA) were added and polymerization was carried out. When the polymerization rate of the chloroprene monomer reached 80%, a 10 wt% aqueous solution of N,N-diethylhydroxylamine, which was a polymerization terminator, was added to terminate the polymerization, and unreacted chloroprene monomer was removed by distillation under reduced pressure. For measuring physical properties, 20 ml of the obtained latex was sampled, and the remaining latex was used to prepare a film for evaluation.

[0116] The sampled latex was mixed with a large amount of methanol to precipitate the resin, which was then filtered and dried to obtain a chloroprene-based block copolymer sample. The contents (mass%) of the polymer block (A) and the chloroprene-based polymer block (B) of the chloroprene-based block coblock copolymer, the epoxy equivalent, and the number average molecular weight were determined from the obtained sample by analysis. The analytical results are shown in Table 1.

[0117] (Examples 4 to 7, Comparative Examples 2 to 5) Latices containing chloroprene-based block copolymers were obtained in the same manner as in Example 3, except that in the polymerization step 1 and the polymerization step 2, the types and amounts of each agent added were as shown in the tables.

[0118] [Analysis] (Measurement of number average molecular weight and molecular weight distribution of polymer block (A), and number average molecular weight of chloroprene polymer) The number average molecular weight and molecular weight distribution are values ​​measured by gel permeation chromatography (GPC) in terms of polystyrene, and are values ​​measured under the measurement conditions described below. Apparatus name: HLC-8320 (manufactured by Tosoh Corporation) Column: Three TSKgel GMHHR-H columns in series Temperature: 40°C Detection: differential refractive index Solvent: tetrahydrofuran Calibration curve: prepared using standard polystyrene (PS).

[0119] (Glass Transition Temperature of Polymer Block (A)) The glass transition temperature was measured using a differential scanning calorimeter according to JIS K 7121 by the following method. Apparatus name: DSC1 (manufactured by Mettler Toledo) Procedure: Under a nitrogen gas flow of 50 ml / min, the sample was heated to 120°C at a heating rate of 10°C / min, maintained at 120°C for 10 minutes, cooled to -60°C, and then heated to 120°C at a heating rate of 10°C / min to obtain a DSC curve. The glass transition temperature was determined as the temperature at the intersection of a straight line extending the base line on the higher temperature side toward the lower temperature side and a tangent line drawn on the curve on the higher temperature side of the peak at the point where the slope is maximum.

[0120] (Measurement of the Contents of Polymer Block (A) and Chloroprene-Based Polymer Block (B) in Chloroprene-Based Polymer) Pyrolysis Gas Chromatogram １Measurement was carried out using H-NMR by the following method. Pyrolysis gas chromatogram Apparatus name: HP5890-II Column: DB-5 0.25 mmφ×30 m (film thickness 1.0 μm) Column temperature: 50°C (5 min) → 10°C / min → 150°C → 25°C / min → 300°C Injection port temperature: 250°C Detector temperature: 280°C Detector: FID １ H-NMR Apparatus name: JNM-ECX-400 (manufactured by JEOL Ltd.) Procedure: A chloroprene-based block copolymer consisting of a polymer block (A) and a chloroprene-based polymer block (B) not containing a glycidyl methacrylate monomer unit was measured by pyrolysis gas chromatogram, and the area ratio of the peak derived from the polymer block (A) to the peak derived from the chloroprene-based polymer block (B) and １ A calibration curve was prepared from the contents of polymer block (A) and chloroprene polymer block (B) in the chloroprene block copolymer obtained by H-NMR measurement. The sampled latex was mixed with methanol to precipitate a chloroprene polymer sample, which was then analyzed by pyrolysis gas chromatography. From the area ratio of the peak derived from polymer block (A) to the peak derived from chloroprene polymer block (B), the contents of polymer block (A) and chloroprene polymer block (B) in the chloroprene polymer were determined using the calibration curve prepared above.

[0121] (Epoxy Equivalent of Chloroprene-Based Polymer) The epoxy equivalent of the chloroprene-based polymer was measured in accordance with JIS K 7236 (2001). Specifically, a precisely weighed sample was dissolved in chloroform, and acetic acid and a tetraethylammonium bromide acetate solution were added thereto. Then, potentiometric titration was performed using a 0.1 mol / L perchloric acid acetate standard solution, and the content of epoxy group-containing monomer units and the epoxy equivalent were calculated.

[0122] [Preparation of Samples for Tensile Test] (Preparation of Chloroprene Polymer Latex Compositions Containing Chloroprene Polymers) A curing agent (hexanediol) was added in an amount shown in Tables 1 and 2 relative to 100 parts by mass (solid content equivalent) of the chloroprene polymer in the latex, and the mixture was mixed at 20°C for 30 minutes using a Magstick Stirrer to prepare a chloroprene polymer latex composition.

[0123] (Film Preparation) The chloroprene polymer latex composition was poured into a mold and dried at room temperature for 3 days to prepare a film (140×150 mm, thickness: 0.2 mm).

[0124] [Evaluation of Molded Article] The prepared film was heat-treated at 80° C. for 30 minutes to obtain a molded article for testing.

[0125] (Stress at 500% Elongation, Tensile Strength at Break, Elongation at Break) Using the test molded body, the stress at 500% elongation, tensile strength at break, and elongation at break were measured based on JIS K 6251:2017.

[0126]

[0127]

Claims

1. A chloroprene polymer, wherein the chloroprene polymer has an epoxy equivalent weight of 3,000 to 20,000 as measured in accordance with JIS K 7236.

2. A chloroprene-based polymer according to claim 1, comprising monomer units derived from a monomer (A), the monomer (A) being a monomer that, upon homopolymerization, gives a polymer having a glass transition temperature of 80°C or higher, and the content of the monomer units derived from the monomer (A) relative to 100% by mass of the chloroprene-based polymer is 15% by mass or less.

3. A chloroprene-based polymer according to claim 2, wherein the chloroprene-based polymer is a chloroprene-based block copolymer comprising a polymer block (A) containing a monomer unit derived from the monomer (A) and a chloroprene-based polymer block (B), and the chloroprene-based polymer block (B) contains a chloroprene monomer unit.

4. The chloroprene polymer according to claim 3, wherein the number average molecular weight of the polymer block (A) is 10,000 or more.

5. The chloroprene polymer according to claim 3 or 4, wherein the molecular weight distribution of the polymer block (A) is 2.0 or less.

6. A chloroprene polymer according to claim 2 or 3, wherein the monomer units derived from the monomer (A) include aromatic vinyl monomer units.

7. The chloroprene polymer according to claim 1 or 2, wherein a molded article of a chloroprene polymer latex composition containing the chloroprene polymer is heat-treated at 80°C for 30 minutes to obtain a test molded article, which has a tensile strength at break of 17.0 MPa or more as measured in accordance with JIS K 6251.

8. A chloroprene polymer latex comprising the chloroprene polymer according to claim 1 or 2 and water.

9. A chloroprene polymer latex composition comprising the chloroprene polymer latex according to claim 8 and a curing agent.

10. The chloroprene polymer latex composition according to claim 9, wherein the total content of the vulcanizing agent and the vulcanization accelerator per 100 parts by mass of the solid content of the chloroprene polymer latex is 5.0 parts by mass or less.

11. A dip-molded article of the chloroprene polymer latex composition according to claim 9.

12. A rubber composition comprising the chloroprene polymer according to claim 1 or 2.

13. A molded article of the rubber composition according to claim 12.

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