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

Abstract

The present invention provides a chloroprene-based block copolymer, a chloroprene-based block copolymer latex, a chloroprene-based block copolymer latex composition, a rubber composition, and a chloroprene-based block copolymer that can be obtained to produce a dipping molded article with high flexibility and low tensile permanent strain. [Solution] According to the present invention, 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, polyfunctional 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

[0004] , , ,

[0001] The present invention relates to a chloroprene-based block copolymer, a chloroprene-based block copolymer latex, a chloroprene-based block copolymer latex composition, a rubber composition, and an immersion molded article.

Background Art

[0002] As surgical gloves, natural rubber and isoprene rubber are widely used. Gloves made of natural rubber and isoprene have low modulus and excellent texture. However, for gloves made of natural rubber, type I allergy due to latex protein, and for gloves made of isoprene, type IV allergy due to a vulcanization accelerator (such as di-o-tolylguanidine (DOTG), etc.) are problems, and an allergen-free alternative material is desired. On the other hand, chloroprene rubber is used in various fields such as immersion molded articles (immersion products), fiber treating agents, paper processing agents, adhesives, binders, elastic asphalt (modified asphalt), elastic cement, etc. Chloroprene rubber has physical properties similar to those of natural rubber in terms of texture, etc., and has been considered as an alternative material for natural rubber (for example, see Patent Documents 1 to 2 below).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, immersion-molded articles obtained using chloroprene polymer latex sometimes exhibited inferior flexibility compared to immersion-molded articles using natural rubber or isoprene rubber. Furthermore, films obtained by immersion molding from latex presented practical challenges, such as plastic deformation and wrinkle formation when the gloves were peeled from the mold during the glove molding process, and plastic deformation and stretching of the gloves when they were stretched, such as during wearing.

[0005] Therefore, the present invention aims to provide a chloroprene-based block copolymer, a chloroprene-based block copolymer latex, a chloroprene-based block copolymer latex composition, a rubber composition, and a chloroprene-based block copolymer latex, which can be obtained that are highly flexible and less prone to plastic deformation after tensile stress is applied and released, i.e., have low tensile permanent strain. [Means for solving the problem]

[0006] 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, polyfunctional 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.

[0007] Through diligent research, the inventors have discovered that in a chloroprene-based block copolymer comprising a polymer block (A) having specific monomer units and a chloroprene-based polymer block (B), the chloroprene-based polymer block (B) contains chloroprene monomer units, polyfunctional monomer units, and unsaturated nitrile monomer units, and further, by setting the nitrogen content of the chloroprene-based block copolymer to a specific numerical range, a chloroprene-based block copolymer can be obtained that yields a highly flexible immersion molded article with low tensile permanent strain, thus completing the present invention.

[0008] 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, polyfunctional 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. [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] The chloroprene block copolymer according to any one of [1] to [3], wherein the tensile strength at break of a test molded article obtained by immersing a chloroprene block copolymer latex composition containing the chloroprene block copolymer, after heat treatment at 130°C for 30 minutes, is 17 MPa or more, as measured in accordance with JIS K 6251. [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] The chloroprene-based block copolymer according to any one of [1] to [7], wherein the polyfunctional monomer unit is a monomer unit represented by chemical formula (1) or an aromatic polyene monomer unit.

[0009] [ka] (In chemical formula (1), R1 and R2 each independently represent 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. W1 represents a saturated or unsaturated hydrocarbon group, a saturated or unsaturated cyclic hydrocarbon group, a saturated or unsaturated hydrocarbon group containing a heteroatom, or a saturated or unsaturated cyclic hydrocarbon group containing a heteroatom. Z1 represents oxygen, sulfur, or a structure represented by -NR0-. R0 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] The chloroprene-based block copolymer according to any one of [1] to [8], wherein the chloroprene-based block copolymer has a functional group having a structure represented by chemical formula (2) or chemical formula (3).

[0010] [ka] (In chemical formula (2), 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.)

[0011] [ka] A chloroprene-based block copolymer latex containing water and the chloroprene-based block copolymer described in any one of items

[10] [1] to [9]. A chloroprene-based block copolymer latex composition comprising the chloroprene-based block copolymer latex and an antioxidant as described in

[11]

[10] , 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. A rubber composition comprising a chloroprene-based block copolymer as described in any one of items

[12] [1] to [9]. A dipped molded article of the chloroprene-based block copolymer latex composition described in

[13]

[10] . [Effects of the Invention]

[0012] The chloroprene-based block copolymer according to the present invention makes it possible to obtain immersion molded articles with high flexibility and low tensile permanent strain. The obtained immersion molded articles have sufficient flexibility compared to conventional immersion molded articles using natural rubber or isoprene rubber. Furthermore, even if tensile stress is applied during the glove molding process, such as when peeling the gloves from the mold or when putting on the gloves, the elongation returns easily after the tensile stress is released, wrinkles are less likely to remain, and the deformation is restored to near the original size. [Modes for carrying out the invention]

[0013] Hereinafter, embodiments of the present invention will be exemplified and the present invention will be described in detail. The present invention is not limited in any way by these descriptions. Each feature of the embodiments of the present invention shown below can be combined with each other. Also, an invention can be established independently for each feature item.

[0014] 1. Chloroprene-based block copolymer The chloroprene-based block copolymer according to the present invention includes a polymer block (A) and a chloroprene-based polymer block (B). The polymer block (A) contains monomer units derived from monomer (A), and monomer (A) is a monomer that can obtain a polymer with a glass transition temperature of 80°C or higher during homopolymerization. The chloroprene-based polymer block (B) contains chloroprene monomer units, polyfunctional monomer units, and unsaturated nitrile monomer units. Further, the nitrogen content of the chloroprene-based block copolymer measured by the combustion method is 0.10 to 0.90% by mass.

[0015] 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 monomer of the polymer block (A). Monomer (A) is a monomer that can obtain a polymer with a glass transition temperature of 80°C or higher during homopolymerization. By using such a monomer as the polymer block, the tensile strength at break of the obtained dip-molded body is improved. Monomer (A) is preferably a monomer that can obtain a polymer with a glass transition temperature of 85°C or higher during homopolymerization. From the viewpoint of moldability, monomer (A) is preferably a monomer that can obtain a polymer with a glass transition temperature of 150°C or lower during homopolymerization, and more preferably a monomer that can obtain a polymer with a glass transition temperature of 120°C or lower. The glass transition temperature of the polymer during homopolymerization 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 here.

[0016] In this specification, the glass transition temperature is 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.

[0017] Monomer (A) is preferably a monomer such that when monomer (A) is polymerized alone 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. When the homopolymer (A) has a weight average molecular weight of 10,000 to 50,000, it is more preferable that the homopolymer has the above glass transition temperature.

[0018] Examples of the monomer unit derived from monomer (A) include an aromatic vinyl monomer unit and a methyl methacrylate monomer unit. Polymer block (A) preferably contains an aromatic vinyl monomer unit, and more preferably contains a styrene monomer unit.

[0019] Polymer block (A) can contain one or more monomer units derived from monomer (A). Also, polymer block (A) may have monomer units other than the monomer units derived from monomer (A) within a range that does not impair the object of the present invention. Polymer block (A) can be such that when polymer block (A) is 100% by mass, it contains 70% by mass or more of the monomer units derived from monomer (A). The content of the monomer units derived from 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. Polymer block (A) can also be composed of the monomer units derived from monomer (A).

[0020] 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-based block copolymer. The number-average molecular weight of the polymer block (A) may be, 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 the range of any two of the values ​​exemplified here.

[0021] 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.

[0022] 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.

[0023] 1.2 Chloroprene-based polymer block (B) The chloroprene polymer block (B) according to the present invention contains chloroprene monomer units, polyfunctional monomer units, and unsaturated nitrile monomer units derived from chloroprene monomer (2-chloro-1,3-butadiene). Furthermore, the chloroprene polymer block (B) may have a structure derived from monomer units other than chloroprene monomer units, polyfunctional monomer units, and unsaturated nitrile monomer units, to the extent that it does not impair the objectives of the present invention.

[0024] A chloroprene polymer block (B) according to one embodiment of the present invention may contain 80% 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, 80, 85, 90, 95, or 100% by mass, and may be within the range of any two of the values ​​exemplified herein.

[0025] The chloroprene polymer block (B) according to the present invention has monomer units derived from a polyfunctional monomer. The chloroprene polymer block (B) according to one embodiment of the present invention may contain 0.05 to 10.00% by mass of polyfunctional monomer units when the chloroprene polymer block (B) is considered as 100% by mass. The content of polyfunctional monomer units in the chloroprene polymer block (B) may be, for example, 0.05, 0.10, 0.50, 1.00, 2.00, 3.00, 4.00, 5.00, 6.00, 7.00, 8.00, 9.00, or 10.00% by mass, and may be within the range of any two of the values ​​exemplified herein.

[0026] The polyfunctional monomer according to one embodiment of the present invention can be a compound having two or more radical polymerization groups in its molecule. The polyfunctional monomer preferably has a plurality of polymerizable substituents that are independent of each other. The polyfunctional monomer preferably has at least one pair of non-conjugated polymerizable substituents. Of the plurality of polymerizable substituents, at least one pair of polymerizable substituents is preferably separated from each other by at least one atom, preferably by three or more atoms, and preferably by five or more atoms. The polymerizable substituents can be vinyl groups or carbon-carbon double bonds. From the viewpoint of flexibility, tensile strength at break, and moldability of the resulting chloroprene-based block copolymer, the polyfunctional monomer unit according to one embodiment of the present invention is preferably a monomer unit represented by chemical formula (1) or an aromatic polyene monomer unit.

[0027] [ka]

[0028] In chemical formula (1), R1 and R2 each independently represent 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. W1 represents a saturated or unsaturated hydrocarbon group, a saturated or unsaturated cyclic hydrocarbon group, a saturated or unsaturated hydrocarbon group containing a heteroatom, or a saturated or unsaturated cyclic hydrocarbon group containing a heteroatom. Z1 represents oxygen, sulfur, or a structure represented by -NR0-. R0 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.

[0029] Examples of monomers represented by chemical formula (1) include 1,9-nonanediol dimethacrylate, 1,9-nonanediol diacrylate, neopentyl glycol dimethacrylate, neopentyl glycol diacrylate, 1,6-hexanediol dimethacrylate, 1,6-hexanediol diacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, polyethylene glycol dimethacrylate, polyethylene glycol diacrylate, and N,N'-diacryloyl-4,7,10-trioxa-1,13-tridecanediamine. Examples of aromatic polyene monomers include aromatic polyenes having 10 to 30 carbon atoms and possessing multiple double bonds (vinyl groups) and one or more aromatic groups. Examples of aromatic polyene monomers include o-divinylbenzene, p-divinylbenzene, m-divinylbenzene, 1,4-divinylnaphthalene, 3,4-divinylnaphthalene, 2,6-divinylnaphthalene, 1,2-divinyl-3,4-dimethylbenzene, and 1,3-divinyl-4,5,8-tributylnaphthalene. One or more of orthodivinylbenzene, paradivinylbenzene, and metadivinylbenzene are preferably used.

[0030] 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 1.0 to 4.0% by mass of unsaturated nitrile monomer units when the chloroprene polymer block (B) is considered to be 100% by mass. The content of unsaturated nitrile monomer units in the chloroprene polymer block (B) is, for example, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, and 4.0% by mass, and may be within the range of any two of the values ​​exemplified here.

[0031] 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 breaking strength and elongation at break in immersion molded articles, it is preferable that the unsaturated nitrile monomer units include acrylonitrile monomer units.

[0032] According to one embodiment of the present invention, a chloroprene-based block copolymer comprising a polymer block (A) and a chloroprene-based polymer block (B) containing chloroprene monomer units, polyfunctional monomer units, and unsaturated nitrile monomer units, can be obtained by specifying the nitrogen content of the chloroprene-based block copolymer, thereby obtaining a dipping molded article with high flexibility and low tensile permanent strain. Furthermore, the chloroprene-based block copolymer according to one embodiment of the present invention can also be used to obtain a dipping molded article with excellent tensile strength at break, moderate elongation at break, and low permanent strain at break. In addition, according to one embodiment of the present invention, a dipping 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.

[0033] Other monomer units besides chloroprene monomer units, polyfunctional monomer units, and unsaturated nitrile monomer units include, for example, 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, styrene, isoprene, and butadiene. Furthermore, the polyfunctional monomers do not necessarily include 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, styrene, acrylonitrile, methacrylonitrile, isoprene, and butadiene. Also, the chloroprene polymer block (B) according to one embodiment of the present invention does not necessarily contain 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, styrene, isoprene, and butadiene. The chloroprene polymer block (B) according to one embodiment of the present invention may consist only of chloroprene monomer units, polyfunctional monomer units, and unsaturated nitrile monomer units. 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, polyfunctional 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, polyfunctional 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, and 10% by mass, and may be within the range of any two of the values ​​exemplified herein.

[0034] 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 0.10 to 0.90% by mass, as measured by combustion. The nitrogen content may be, for example, 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, or 0.90% by mass, and may be within the range of any two of the values ​​exemplified herein.

[0035] The chloroprene-based block copolymer according to one embodiment of the present invention has 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 can be 0.5 to 3.6% by mass, and more preferably 1.0 to 2.0% by mass. The content of unsaturated nitrile monomer units in the chloroprene polymer block (B) is, for example, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, and 3.6% by mass, and may be within the range of any two of the values ​​exemplified here.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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).

[0040] 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 (2) or chemical formula (3).

[0041] [ka]

[0042] In chemical formula (2), 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.

[0043] [ka]

[0044] Functional groups of the structure represented by chemical formula (2) or chemical formula (3) 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 (2) or chemical formula (3) will be described later in the section on manufacturing methods.

[0045] 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.

[0046] 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 17 MPa or more, measured in accordance with JIS K 6251, obtained by heat-treating a test molded body obtained after immersion molding of a chloroprene-based block copolymer latex composition containing the chloroprene-based block copolymer at 130°C for 30 minutes. The tensile strength at break may be, for example, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 MPa, and may be within the range of any two of the values ​​exemplified herein.

[0047] (Modulus at 500% extension) The chloroprene-based block copolymer according to one embodiment of the present invention preferably has a modulus at 500% elongation of 3.0 MPa or less, and more preferably 2.0 MPa or less, measured in accordance with JIS K 6251, obtained by heat-treating a chloroprene-based block copolymer latex composition containing the chloroprene-based block copolymer at 130°C for 30 minutes. The tensile strength at break is, for example, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0 MPa, and may be within the range of any two of the values ​​exemplified here.

[0048] (Elongation upon cutting) In one embodiment of the present invention, the chloroprene-based block copolymer preferably has an elongation at break of 850% or more, measured in accordance with JIS K 6251, obtained by heat-treating a test molded article obtained after immersion molding of a chloroprene-based block copolymer latex composition containing the chloroprene-based block copolymer at 130°C for 30 minutes. The elongation at break may be, for example, 850, 900, 950, 1000, 1050, 1100, 1150, or 1200%, and may be within the range of any two of the values ​​exemplified herein.

[0049] (Permanent distortion upon cutting) The chloroprene-based block copolymer according to one embodiment of the present invention is obtained by heat-treating a chloroprene-based block copolymer latex composition containing the chloroprene-based block copolymer at 130°C for 30 minutes, marking the test molded body with a 20 mm gauge spacing marker in accordance with JIS K 6251, measuring the length between the gauges, measuring the tensile strength and elongation at break, then letting the cut test piece stand for 10 minutes, butting the cut surfaces together and measuring the length between the gauges, and preferably the calculated permanent strain at break is 23% or less, and more preferably 20% or less. The permanent strain at break is, for example, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23%, and may be within the range of any two of the values ​​exemplified here.

[0050] (Tensile permanent strain) In one embodiment of the present invention, the chloroprene-based block copolymer preferably has a constant elongation tensile permanent strain of 5.0% or less, measured in accordance with JIS K 6273, obtained by heat-treating a test molded article obtained after immersion molding of a chloroprene-based block copolymer latex composition containing the chloroprene-based block copolymer at 130°C for 30 minutes. The constant elongation tensile permanent strain is, for example, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, and 5.0%, and may be within the range of any two of the values ​​exemplified here.

[0051] The test molded article can be obtained by immersing a chloroprene block copolymer latex composition, which is 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, so that the solid content concentration is 30% by mass. The immersed molded article obtained is then heat-treated at 130°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 modulus at 500% elongation, tensile strength at break, elongation at break, permanent strain at break, and tensile permanent strain of the test molded article can be adjusted by controlling the type and amount of raw materials used in the production of the chloroprene-based block copolymer, as well as the polymerization conditions.

[0052] 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, a polyfunctional monomer, and an 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.

[0053] 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.

[0054] <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.

[0055] 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.

[0056] 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.

[0057] (Initiator) As radical polymerization initiators, known radical polymerization initiators can be used, such as potassium persulfate, benzoyl peroxide, hydrogen peroxide, and azo compounds.

[0058] (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 (2) or chemical formula (3) can be introduced into a chloroprene-based block copolymer.

[0059] [ka]

[0060] In chemical formula (2), 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.

[0061] [ka]

[0062] The compounds used to derive the structure represented by the above chemical formula (2) 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]coha Potassium 3,5-dimethyl-1H-pyrazole-1-carbodhithioate, cyanomethyl-3,5-dimethyl-1H-pyrazole-1-carbodhithioate, cyanomethylmethyl-(phenyl)dithiocarbamate, 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.

[0063] The compound used to derive the structure represented by the above chemical formula (3) 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.

[0064] 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.

[0065] (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.

[0066] <Polymerization step 2> In polymerization step 2, a chloroprene monomer, a polyfunctional monomer, and an unsaturated nitrile are 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). The chloroprene monomer, polyfunctional monomer, and unsaturated nitrile may be added all at once or in stages. It is preferable to adjust the type and amount of each monomer added so that the content of each monomer unit in the resulting chloroprene-based polymer block (B) and chloroprene-based block copolymer falls within the numerical range described above.

[0067] 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.

[0068] 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.

[0069] <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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] <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 content 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% by mass, and may be within the range of any two of the values ​​exemplified herein.

[0074] 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.

[0075] <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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] Examples of thiram-based vulcanization accelerators include tetramethylthiram disulfide, tetraethylthiram disulfide, tetrabutylthiram disulfide, tetrakis(2-ethylhexyl)thiram disulfide, tetramethylthiram monosulfide, and dipentamethylenethiram tetrasulfide.

[0080] 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.

[0081] Examples of thiourea-based vulcanization accelerators include ethylenethiourea, N,N'-diethylthiourea, trimethylthiourea, and N,N'-diphenylthiourea.

[0082] 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.

[0083] Examples of xanthogenic acid-based vulcanization accelerators include zinc butylxanthonate and zinc isopropylxanthonate.

[0084] 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.

[0085] 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 even without vulcanization, and can exhibit excellent modulus at 500% elongation, elongation at break, permanent strain at break, and tensile permanent strain. For this reason, from the viewpoint of reducing allergies and costs, the vulcanizing agent and vulcanization accelerator can be omitted.

[0086] 5.Dip molding An immersion-molded article according to one embodiment of the present invention can be an immersion-molded article of the chloroprene-based block copolymer latex composition described above. The immersion-molded article can be suitably used for gloves, balloons, catheters, boots, and the like.

[0087] (Tensile strength at break) The immersion-molded article according to one embodiment of the present invention preferably has a tensile strength at break of 17 MPa or more, as measured in accordance with JIS K 6251. The tensile strength at break may be, for example, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 MPa, and may be within the range of any two of the values ​​exemplified herein.

[0088] (Modulus at 500% extension) The immersion-molded article according to one embodiment of the present invention preferably has a modulus of 3.0 MPa or less, and more preferably 2.0 MPa or less, at 500% elongation as measured in accordance with JIS K 6251. The tensile strength at break is, for example, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, or 3.0 MPa, and may be within the range of any two of the values ​​exemplified here.

[0089] (Elongation upon cutting) The immersion-molded article according to one embodiment of the present invention preferably has an elongation at break of 850% or more, as measured in accordance with JIS K 6251. The elongation at break may be, for example, 850, 900, 950, 1000, 1050, 1100, 1150, or 1200%, and may be within the range of any two of the values ​​exemplified herein.

[0090] (Permanent distortion upon cutting) In one embodiment of the present invention, a test molded body obtained by heat treatment at 130°C for 30 minutes is marked with a gauge marker with a gauge spacing of 20 mm in accordance with JIS K 6251, the length between the gauges is measured, the tensile strength at break and the elongation at break are measured, and then the cut test piece is left to stand for 10 minutes, the cut surfaces are butted together, and the length between the gauges is measured. The calculated permanent strain at break is preferably 23% or less, and preferably 20% or less. The permanent strain at break may be, for example, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, or 23%, and may be within the range of any two of the values ​​exemplified here.

[0091] (Tensile permanent strain) The immersion-molded article according to one embodiment of the present invention preferably has a constant elongation tensile permanent strain of 5.0% or less, as measured in accordance with JIS K 6273. The constant elongation tensile permanent strain is, for example, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, or 5.0%, and may be within the range of any two of the values ​​exemplified here.

[0092] 6. Method for manufacturing immersion molded bodies 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.

[0093] 6.1 Dip molding process Examples of immersion molding methods for one embodiment of the present invention include immersion solidification, simple immersion, heat-sensitive immersion, and electrodeposition. 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 solidification solution is immersed in a chloroprene-based block copolymer latex composition, and the chloroprene-based block copolymer latex composition is solidified. After removing water-soluble impurities by leaching, it is dried, and then heated to form an immersion molded film (rubber coating), after which the immersion molded film is released from the mold. This makes it possible to obtain a film-like immersion molded body.

[0094] 5.3 Heat treatment process A method for manufacturing a dipping molded body according to one embodiment of the present invention may include a heat treatment step of heat-treating the dipping molded body.

[0095] The heat treatment temperature can be set appropriately according to the composition of the chloroprene block copolymer, and may be between 120 and 180°C. The heating temperature is preferably between 120 and 150°C. The heating temperature can be, for example, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, or 220°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 10 and 300 minutes. The heating time can be, for example, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, or 300 minutes, 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 130°C for 30 minutes. [Examples]

[0096] 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.

[0097] (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. 3258g of pure water, 152g of disproportionated potassium rosinate (Harima Chemicals Group Co., Ltd.), 2.17g of potassium hydroxide, 17.1g of sodium salt of β-naphthalene sulfonic acid formalin condensate (Kao Corporation, product name: Demol N), 324.9g of styrene monomer, and 5.92g of butylbenzyl trithiocarbonate were charged, and the mixture was stirred at 200 rpm under a nitrogen stream at an internal temperature of 80°C. 3.73g 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.

[0098] 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 analysis results are shown in Table 1. The measurement method will be described later.

[0099] (Polymerization step 2) Synthesis of chloroprene polymer block (B-1) After polymerization step 1, once the internal temperature had dropped to 45°C, 3258g of chloroprene monomer, 54.0g of light ester EG (ethylene glycol dimethacrylate), and 288g of acrylonitrile were slowly added over 2 hours to carry out polymerization. When the polymerization rate of the chloroprene monomer reached 81%, 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 evaluation films were prepared using the remaining latex.

[0100] 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.

[0101] (Examples 2-5, 7-9, Comparative Examples 1-4, 6-8) 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.

[0102] (Example 6) (Polymerization process 1) Synthesis of polymer block (A-6) Polymerization was carried out using a 10L autoclave equipped with a stirrer and a heating / cooling jacket. 2374g of pure water, 105.2g of disproportionated potassium rosinate (Harima Chemicals Group Co., Ltd.), 1.50g of potassium hydroxide, 11.9g of sodium salt of β-naphthalene sulfonic acid formalin condensate (Kao Corporation, product name: Demol N), 227g of styrene monomer, and 4.11g of butylbenzyl trithiocarbonate were charged, and the mixture was stirred at 200 rpm under a nitrogen stream at an internal temperature of 80°C. 2.59g 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.

[0103] (Polymerization step 2) Synthesis of chloroprene polymer block (B-6) After polymerization step 1, once the internal temperature had dropped to 45°C, 4225g of chloroprene monomer, 75.0g of light ester EG, and 700g of acrylonitrile were slowly added over 3 hours to carry out polymerization. When the polymerization rate of the chloroprene monomer reached 60%, 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. The content (mass%) of polymer blocks (A-6) and chloroprene polymer blocks (B-6) of the chloroprene-based block copolymer was determined by analysis in the same manner as in Example 1. The analysis results are shown in Table 1.

[0104] (Comparative Example 5) (Polymerization process 1) Synthesis of polymer block (A-14) Polymerization was carried out using a 10L autoclave equipped with a stirrer and a heating / cooling jacket. 2374g of pure water, 105g of disproportionated potassium rosinate (Harima Chemicals Group Co., Ltd.), 1.50g of potassium hydroxide, 11.9g of sodium salt of β-naphthalene sulfonic acid formalin condensate (Kao Corporation, product name: Demol N), 222g of styrene monomer, and 8.22g of butylbenzyl trithiocarbonate were charged, and the mixture was heated to an internal temperature of 80°C and stirred at 200 rpm under a nitrogen stream. 2.59g 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.

[0105] (Polymerization step 2) Synthesis of chloroprene polymer block (B-14) After polymerization step 1, once the internal temperature had dropped to 45°C, 4900g of chloroprene monomer and 100g of 1,9-nonanediol dimethacrylate were slowly added over 3 hours to carry out polymerization. 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. From the obtained sample, the content (mass%) of chloroprene-based block copolymer polymer block (A-14) and chloroprene-based polymer block (B-14), the nitrogen content measured by combustion, and the content of acrylonitrile monomer units were determined by analysis. The analysis results are shown in Table 2.

[0106] [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).

[0107] (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.

[0108] (Measurement of the content of polymer block (A) and chloroprene polymer block (B) in the chloroprene-based block copolymer) The measurements were performed using pyrolysis gas chromatograms and 1H-NMR, according to the following methods. 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 1H-NMR spectrometer name: JNM-ECX-400 (manufactured by JEOL Ltd.) Procedure: Chloroprene-based block copolymers, consisting of polymer block (A) and chloroprene-based polymer block (B) that do not contain polyfunctional monomer units or unsaturated nitrile monomer units, were measured using a pyrolysis gas chromatogram. A calibration curve was created from the area ratio of the peak derived from polymer block (A) to the peak derived from chloroprene-based polymer block (B), and the content of polymer block (A) and chloroprene-based polymer block (B) in the chloroprene-based block copolymer obtained by measuring 1H-NMR. Samples of chloroprene-based block copolymer precipitated by mixing sampled latex with methanol were measured using a pyrolysis gas chromatogram. The content of polymer block (A) and chloroprene-based polymer block (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) to the peak derived from chloroprene-based polymer block (B).

[0109] (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.

[0110] 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.

[0111] [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.

[0112] (Film production) A ceramic cylinder with an outer diameter of 50 mm was immersed for 1 second in a coagulation solution prepared by mixing 62 parts by mass of water, 35 parts by mass of potassium nitrate tetrahydrate, and 3 parts by mass of calcium carbonate, and then removed. After drying for 4 minutes, it was immersed for 2 minutes in the chloroprene-based block copolymer latex composition prepared above. Subsequently, it was washed with running water at 45°C for 1 minute, and then heat-treated at 130°C for 30 minutes to remove moisture, thereby preparing a film (140 × 150 mm, thickness: 0.2 mm) for tensile testing.

[0113] [Evaluation of tensile properties] (Modulus at 500% elongation (tensile stress at 500% elongation), tensile strength at break, elongation at break) The prepared films were measured according to JIS K 6251:2017 for modulus at 500% elongation (tensile stress at 500% elongation), tensile strength at break, and elongation at break.

[0114] (Permanent distortion upon cutting) The prepared film was marked with a 20mm gauge marker in accordance with JIS K 6251, the length between the gauges was measured, and the tensile strength and elongation at break were measured. After the cut specimens were left to stand for 10 minutes, the cut surfaces were butted together, the length between the gauges was measured, and the permanent strain at break was calculated.

[0115] (Tensile permanent strain) The fabricated films were subjected to constant elongation tensile permanent strain measurements in accordance with JIS K 6273:2018.

[0116] [Table 1]

[0117] [Table 2]

[0118] [Table 3]

[0119] Table 4

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, polyfunctional monomer units, and unsaturated nitrile monomer units. The chloroprene-based block copolymer is a chloroprene-based block copolymer having a nitrogen content of 0.10 to 0.90% 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 claim 2, wherein the tensile strength at break of a test molded article obtained after heat-treating a chloroprene block copolymer latex composition containing the chloroprene block copolymer at 130°C for 30 minutes is 17 MPa or more, as measured in accordance with JIS K 6251.

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. The chloroprene-based block copolymer according to claim 1 or claim 2, wherein the polyfunctional monomer unit is a monomer unit represented by chemical formula (1) or an aromatic polyene monomer unit. 【Chemistry 1】 (In chemical formula (1), R １ and R ２ Each of these independently 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. １ Z represents either a saturated or unsaturated hydrocarbon group, a saturated or unsaturated cyclic hydrocarbon group, a saturated or unsaturated hydrocarbon group containing a heteroatom, or a saturated or unsaturated cyclic hydrocarbon group containing a heteroatom. １ is oxygen, sulfur, or -NR ０ Represents a structure represented by -. R ０ (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. The chloroprene-based block copolymer according to claim 1 or claim 2, wherein the chloroprene-based block copolymer has a functional group having a structure represented by chemical formula (2) or chemical formula (3). 【Chemistry 2】 (In chemical formula (2), R ３ (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.) 【Transformation 3】

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

11. A chloroprene-based block copolymer latex composition comprising the chloroprene-based block copolymer latex and an antioxidant according to claim 10, 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.

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

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

Images