Latex composition for dip molding

Abstract

The present invention relates to a latex composition for dip molding, the composition containing: a surfactant (A) which contains at least one of an anionic surfactant (A1) that contains a hydroxyalkanesulfonic acid salt, an internal olefin sulfonate, and an internal olefin, and an anionic surfactant (A2) that is composed of a linear or branched alkyl diphenyl ether disulfonate; and a polymer (B) which contains a structural unit (B1) that is derived from a conjugated diene monomer, a structural unit (B2) that is derived from an ethylenically unsaturated carboxylic acid monomer, and a structural unit (B3) that is derived from an ethylenically unsaturated nitrile monomer. The content of the surfactant (A) with respect to 100 parts by mass of the polymer (B) is 0.05 part by mass to 10 parts by mass inclusive. The present invention also relates to a method for producing a dip molded article that causes a latex added composition for dip molding including the latex composition for dip molding to be molded.

Description

Latex composition for dip molding

[0001] The present invention relates to a latex composition for dip molding, a latex-blended composition for dip molding containing the latex composition, a dip-molded product using the latex-blended composition for dip molding, and a method for producing the same.

[0002] Conventionally, dip-molded products that are used in contact with the human body, such as artificial nipples, balloons, gloves, balloons, and sacks, are known, which are obtained by dip-molding latex compositions containing natural latex, such as natural rubber latex. However, natural latex contains proteins that can cause allergic reactions in the human body, and therefore, there have been some problems with dip-molded products that come into direct contact with biological mucous membranes or organs. Therefore, the use of latex compositions obtained by emulsion polymerization of vinyl monomers such as vinyl acetate, (meth)acrylic acid esters, styrene, and derivatives thereof has been investigated.

[0003] In emulsion polymerization of vinyl monomers, anionic surfactants such as linear alkyl sulfates, linear alkylbenzene sulfonates, alkyl diphenyl ether disulfonates, polyoxyethylene alkyl ether sulfates, and polyoxyethylene alkyl phenyl ether sulfates, as well as nonionic surfactants such as polyoxyethylene linear alkyl ethers and polyoxyethylene alkyl phenyl ethers, have been used. The emulsifier in emulsion polymerization not only affects the initiation and propagation of polymerization, but also significantly influences the stability of the polymer emulsion during polymerization (hereinafter also referred to as "polymerization stability"), as well as the mechanical and chemical stability of the resulting polymer emulsion. Therefore, the performance required of a surfactant for emulsion polymerization is good polymerization stability and chemical stability, small particle size of the polymer emulsion, and low environmental impact. Conventionally, polyoxyethylene alkyl ether sulfates, which have low environmental impact and excellent polymerization stability and chemical stability, have been widely used as surfactants for emulsion polymerization. However, in the production of polyvinyl chloride and SB latex, large amounts of linear alkylbenzene sulfonates and alkyldiphenyl ether disulfonates derived from petrochemical raw materials are still used.

[0004] As such surfactants, for example, Japanese Patent Laid-Open No. 2006-273882 (Patent Document 1) discloses an emulsifier for emulsion polymerization containing an anionic surfactant derived from a polyoxyalkylene alkyl ether made from a branched alcohol derived from a petrochemical raw material. Also, Japanese Patent Laid-Open No. 2001-72702 (Patent Document 2) discloses an ether-type nonionic or anionic emulsifier for emulsion polymerization, which is obtained by adding an alkylene oxide to an alcohol having 13 carbon atoms synthesized by the oxo method, and in which the hydrophobic group is an aliphatic alcohol residue.

[0005] The present invention relates to a dip-molding latex composition, which includes a surfactant (A) containing at least one of an anionic surfactant (A1) containing a hydroxyalkanesulfonate, an internal olefinsulfonate, and an anionic surfactant (A2) consisting of a linear or branched alkyldiphenylether disulfonate, and a polymer (B) containing a structural unit (B1) derived from a conjugated diene monomer, a structural unit (B2) derived from an ethylenically unsaturated carboxylic acid monomer, and a structural unit (B3) derived from an ethylenically unsaturated nitrile monomer, wherein the content of the surfactant (A) is 0.05 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the polymer (B), and a method for producing a dip-molded product by molding the dip-molded latex-blended composition containing the dip-molding latex composition.

[0006] However, molded articles of latex compositions using the emulsifiers for emulsion polymerization described in Patent Documents 1 and 2 as surfactants in emulsion polymerization of vinyl monomers have a problem in that it is difficult to achieve both flexibility and tensile strength.

[0007] The present inventors have found that molded articles (hereinafter also referred to as "dip-molded articles") of a latex compounded composition for dip molding containing a specific surfactant (A) and a polymer (B) containing structural units (B1) derived from a conjugated diene monomer, structural units (B2) derived from an ethylenically unsaturated carboxylic acid monomer, and structural units (B3) derived from an ethylenically unsaturated nitrile monomer, wherein the content of the surfactant (A) per 100 parts by mass of the solid content of the polymer (B) is 0.05 parts by mass or more and 10.0 parts by mass or less (hereinafter also referred to as "dip-molded articles") are excellent in flexibility and tensile strength. That is, the present invention relates to the following [1] to

[19] . [1] A dip-molding latex composition comprising: a surfactant (A) containing at least one of: component (a1) being a hydroxyalkanesulfonate salt having an average carbon number of from 16 to 18; component (a2) being an internal olefin sulfonate salt having an average carbon number of from 16 to 18; and component (a3) ​​being an anionic surfactant (A1) containing an internal olefin having an average carbon number of from 16 to 18; and an anionic surfactant (A2) being a linear or branched alkyldiphenylether disulfonate salt having an average carbon number of from 16 to 18; and a polymer (B) containing structural units (B1) derived from a conjugated diene monomer, structural units (B2) derived from an ethylenically unsaturated carboxylic acid monomer, and structural units (B3) derived from an ethylenically unsaturated nitrile monomer, wherein the content of the surfactant (A) per 100 parts by mass of the polymer (B) is from 0.05 to 10 parts by mass. [2] The latex composition for dip-forming according to [1], wherein a mass ratio of the component (a1) to the component (a2) in the surfactant (A1) [component (a1) / component (a2)] is 0.25 or more and 20 or less.[3] The dip-forming latex composition according to [1] or [2], wherein the content of the structural unit (B1) derived from the conjugated diene monomer is from 50% to 78% by mass, the content of the structural unit (B2) derived from the ethylenically unsaturated carboxylic acid monomer is from 2% to 10% by mass, and the content of the structural unit (B3) derived from the ethylenically unsaturated nitrile monomer is from 20% to 40% by mass, based on the total content of the structural unit (B1) derived from the conjugated diene monomer, the structural unit (B2) derived from the ethylenically unsaturated carboxylic acid monomer, and the structural unit (B3) derived from the ethylenically unsaturated nitrile monomer in the polymer (B). [4] The dip-forming latex composition according to any one of [1] to [3], further comprising an alkylbenzenesulfonic acid or a salt thereof, the alkyl group of which has an average carbon number of from 8 to 18. [5] The latex composition for dip molding according to any one of [1] to [4], wherein the content of (A) is 0.05% by mass or more and 10% by mass or less, the content of (B) is 80% by mass or more and 99.9% by mass or less, and the content of the alkylbenzenesulfonic acid or its salt is 0.05% by mass or more and 10% by mass or less, based on the total content of the surfactant (A), the polymer (B), and the alkylbenzenesulfonic acid or its salt. [6] The latex composition for dip molding according to any one of [1] to [5], which is obtained by mixing the surfactant (A) and the polymer (B). [7] A latex blend composition for dip molding, which contains the latex composition for dip molding according to any one of [1] to [6], and at least one selected from the group consisting of a metal oxide, a sulfur-based crosslinking agent, and a vulcanization accelerator. [8] The latex-blended composition for dip molding according to [7], containing 35 parts by mass or less of a metal oxide, 2 parts by mass or less of a sulfur-based crosslinking agent, and 2 parts by mass or less of a vulcanization accelerator, relative to 100 parts by mass of the polymer (B). [9] A dip-molded product of the latex-blended composition for dip molding according to [7] or [8].

[10] The dip-molded product according to [9], wherein the dip-molded product is a glove.

[11] A method for producing a dip-molded product, comprising molding the latex-blended composition for dip molding according to [7] or [8].

[12] The production method according to

[11] , wherein the dip-molded product is a glove.

[13] A method for producing a dip-molding latex composition, the method comprising: emulsion polymerizing monomers containing a conjugated diene monomer (b1), an ethylenically unsaturated carboxylic acid monomer (b2), and an ethylenically unsaturated nitrile monomer (b3) using a surfactant (A) containing at least one of an anionic surfactant (A1) containing: component (a1): a hydroxyalkanesulfonate salt having an average carbon number of 16 to 18; component (a2): an internal olefin sulfonate salt having an average carbon number of 16 to 18; and component (a3): an internal olefin having an average carbon number of 16 to 18; and an anionic surfactant (A2) consisting of a linear or branched alkyldiphenyl ether disulfonate salt having an average carbon number of 16 to 18 in the alkyl group.

[14] A method for producing a dip-forming latex composition, the method comprising: emulsion polymerizing monomers containing a conjugated diene monomer (b1), an ethylenically unsaturated carboxylic acid monomer (b2), and an ethylenically unsaturated nitrile monomer (b3) using a surfactant (A) containing at least one of an anionic surfactant (A1) containing: a component (a1): a hydroxyalkanesulfonate salt having an average carbon number of 16 to 18; a component (a2): an internal olefin sulfonate salt having an average carbon number of 16 to 18; and a component (a3): an internal olefin having an average carbon number of 16 to 18; and an anionic surfactant (A2) consisting of a linear or branched alkyldiphenyl ether disulfonate salt having an average alkyl group number of 16 to 18; and an alkylbenzenesulfonic acid or a salt thereof having an alkyl group number of 8 to 18 on average.

[15] Use of a surfactant (A) containing at least one of an anionic surfactant (A1) containing: a component (a1): a hydroxyalkanesulfonate salt having an average carbon number of 16 to 18; a component (a2): an internal olefin sulfonate salt having an average carbon number of 16 to 18; and a component (a3): an internal olefin having an average carbon number of 16 to 18; and an anionic surfactant (A2) consisting of a linear or branched alkyldiphenylether disulfonate salt having an average carbon number of 16 to 18 in the alkyl group, for emulsion polymerization of monomers including a conjugated diene monomer (b1), an ethylenically unsaturated carboxylic acid monomer (b2), and an ethylenically unsaturated nitrile monomer (b3).

[16] An emulsion polymerization agent for monomers including a conjugated diene monomer (b1), an ethylenically unsaturated carboxylic acid monomer (b2), and an ethylenically unsaturated nitrile monomer (b3), containing a surfactant (A) including at least one of an anionic surfactant (A1) containing: a component (a1): a hydroxyalkanesulfonate salt having an average carbon number of 16 to 18; a component (a2): an internal olefin sulfonate salt having an average carbon number of 16 to 18; and a component (a3): an internal olefin having an average carbon number of 16 to 18; and an anionic surfactant (A2) consisting of a linear or branched alkyldiphenyl ether disulfonate salt having an average carbon number of 16 to 18 in the alkyl group.

[17] Use of a surfactant (A) containing at least one of an anionic surfactant (A1) containing: component (a1): hydroxyalkanesulfonate salt having an average carbon number of 16 to 18; component (a2): internal olefinsulfonate salt having an average carbon number of 16 to 18; and component (a3): internal olefin having an average carbon number of 16 to 18; and an anionic surfactant (A2) consisting of a linear or branched alkyldiphenyletherdisulfonate salt having an average alkyl group carbon number of 16 to 18, for stabilizing a dip-molding latex composition containing a polymer (B) containing structural units (B1) derived from a conjugated diene monomer, structural units (B2) derived from an ethylenically unsaturated carboxylic acid monomer, and structural units (B3) derived from an ethylenically unsaturated nitrile monomer.

[18] A stabilizer for a dip-molding latex composition, comprising a surfactant (A) containing at least one of an anionic surfactant (A1) containing: a component (a1): a hydroxyalkanesulfonate salt having an average carbon number of 16 to 18; a component (a2): an internal olefin sulfonate salt having an average carbon number of 16 to 18; and a component (a3): an internal olefin having an average carbon number of 16 to 18; and an anionic surfactant (A2) consisting of a linear or branched alkyl diphenyl ether disulfonate salt having an average carbon number of 16 to 18 in the alkyl group; and the stabilizer includes a polymer (B) containing structural units (B1) derived from a conjugated diene monomer, structural units (B2) derived from an ethylenically unsaturated carboxylic acid monomer, and structural units (B3) derived from an ethylenically unsaturated nitrile monomer. Surfactant (A1)

[19] A method for producing a latex blend composition for dip molding, comprising a step of mixing a latex composition containing a polymer (B) including structural units (B1) derived from a conjugated diene monomer, structural units (B2) derived from an ethylenically unsaturated carboxylic acid monomer, and structural units (B3) derived from an ethylenically unsaturated nitrile monomer, with a surfactant (A) containing at least one of: component (a1): a hydroxyalkanesulfonate salt having an average carbon number of 16 to 18; component (a2): an internal olefin sulfonate salt having an average carbon number of 16 to 18; and component (a3): an anionic surfactant (A1) containing an internal olefin having an average carbon number of 16 to 18; and an anionic surfactant (A2) consisting of a linear or branched alkyldiphenylether disulfonate salt having an average carbon number of 16 to 18 in the alkyl group.

[0008] The dip-molding latex composition of the present invention can produce dip-molded articles with excellent flexibility and tensile strength. The reason for this is unclear, but is thought to be as follows: Because the dip-molding latex composition and / or the dip-molding latex composition contain a specific surfactant (A) and polymer (B), it is thought that the surfactant (A) enhances the mechanical and chemical stability of the polymer (B) in the composition. Therefore, it is thought that the dip-molded article obtained by curing the dip-molding latex composition has excellent tensile strength. Furthermore, it is thought that the surfactant (A) contained in the dip-molding latex composition and / or the dip-molding latex composition is not removed by dip molding, and a portion of it remains in the dip-molded article, thereby providing a plasticizing effect on the polymer containing polymer (B) and an anchoring effect that prevents the surfactant (A) itself from bleeding. The anionic surfactant (A1) contained in the surfactant (A) contains a hydroxyalkanesulfonate (component (a1)) having an average carbon number of 16 to 18, both of which have both a nonpolar moiety and a polar moiety in the same molecule, and an internal olefinsulfonate (component (a2)) having an average carbon number of 16 to 18. Therefore, the polar moieties, such as the hydroxy group and sulfonate, contribute to an anchoring effect that prevents the anionic surfactant (A1) itself from bleeding, and remain in the dip-molded product. Furthermore, the nonpolar moieties, such as the alkane and internal olefin, of component (a1) exhibit a plasticizing effect on the polymer containing polymer (B), and therefore the dip-molded product is thought to have excellent flexibility. Furthermore, the anionic surfactant (A2) contained in the surfactant (A) is a linear or branched alkyl diphenyl ether disulfonate having an average carbon number of 16 or more and 18 or less and having both a nonpolar portion and a polar portion in the same molecule. Therefore, the polar portion, the sulfonate, contributes to an anchoring effect that prevents the anionic surfactant (A2) itself from bleeding, and remains in the dip-molded product. Furthermore, the nonpolar portions, such as the alkyl group and diphenyl ether of the anionic surfactant (A2), exhibit a plasticizing effect on the polymer containing the polymer (B), and therefore the dip-molded product is thought to have excellent flexibility.Furthermore, the internal olefin sulfonate (component (a2)) and the internal olefin (component (a3)) having an average carbon number of 16 to 18, both contained in the anionic surfactant (A1), and the diphenyl ether contained in the anionic surfactant (A2), each have an unsaturated bond. Therefore, when the surfactant (A) is used for emulsion polymerization of the polymer (B), they are incorporated into the polymer (B). Furthermore, they are incorporated into the cured product during dip molding, exhibiting a plasticizing effect, which is also thought to contribute to the excellent flexibility of the dip-molded product.

[0009] [Latex Composition for Dip Molding] The latex composition for dip molding of the present invention contains a surfactant (A) and a polymer (B) as shown below. In the latex composition for dip molding, the content of the surfactant (A) relative to 100 parts by mass of the solid content of the polymer (B) is 0.05 parts by mass or more, preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, even more preferably 2 parts by mass or more, and 10 parts by mass or less, preferably 7 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 4 parts by mass or less, from the viewpoint of providing a dip-molded product with excellent flexibility and tensile strength. The content of the surfactant (A) relative to 100 parts by mass of the solid content of the polymer (B) is 0.05 parts by mass or more and 10 parts by mass or less, preferably 0.1 parts by mass or more and 7 parts by mass or less, more preferably 1 part by mass or more and 5 parts by mass or less, and even more preferably 2 parts by mass or less.

[0010] <Surfactant (A)> The surfactant (A) contained in the dip-forming latex composition of the present invention is a composition containing at least one of an anionic surfactant (A1) containing component (a1): a hydroxyalkanesulfonate having an average carbon number of from 16 to 18 (hereinafter simply referred to as "component (a1)"), component (a2): an internal olefin sulfonate having an average carbon number of from 16 to 18 (hereinafter simply referred to as "component (a2)"), and component (a3): an internal olefin having an average carbon number of from 16 to 18 (hereinafter simply referred to as "component (a3)"), and an anionic surfactant (A2) consisting of a linear or branched alkyldiphenyl ether disulfonate having an alkyl group with an average carbon number of from 16 to 18. In this specification, the term "internal olefin" refers to an olefin having a double bond within the olefin chain, and includes a case where the olefin contains a trace amount of so-called α-olefin, in which the double bond is located at position 1 of the carbon chain.

[0011] <Anionic Surfactant (A1)> The anionic surfactant (A1) contains a component (a1): a hydroxyalkanesulfonate having an average carbon number of from 16 to 18, a component (a2): an internal olefinsulfonate having an average carbon number of from 16 to 18, and a component (a3): an internal olefin having an average carbon number of from 16 to 18.

[0012] [Component (a1): Hydroxyalkanesulfonate having an average carbon number of 16 to 18] Component (a1) may be a hydroxyalkanesulfonate having a single carbon number of 16 to 18, a mixture of two or more hydroxyalkanesulfonates having 16 to 18 carbon atoms, or a mixture of two or more hydroxyalkanesulfonates having an average carbon number of 16 to 18. Note that hydroxyalkanesulfonates having an average carbon number of 16 to 18 are hydroxyalkanesulfonates having a weighted average of the carbon atoms contained in the hydroxyalkanesulfonate of 16 to 18, and the content of hydroxyalkanesulfonates having 16 to 18 carbon atoms in component (a1) is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 16 to 18 carbon atoms.

[0013] The hydroxyalkanesulfonate salt, which is component (a1), can be obtained by sulfonating, neutralizing, and then hydrolyzing an internal olefin having from 16 to 18 carbon atoms or a mixture of internal olefins having an average carbon number of from 16 to 18. The conditions for sulfonation, neutralization, and hydrolysis are not particularly limited, and reference can be made to the conditions described in, for example, JP-B No. 49-41179 and JP-A No. 2-73051.

[0014] In the hydroxyalkanesulfonate salt of component (a1), examples of the counter cation of the sulfonic acid include hydrogen ions, alkali metal cations, and ammonium. Of these, alkali metal cations are preferred.

[0015] [Component (a2): Internal olefin sulfonate having an average carbon number of 16 to 18] The component (a2) may be an internal olefin sulfonate having a single carbon number of 16 to 18, or a mixture of two or more types of internal olefin sulfonates having 16 to 18 carbon atoms, or a mixture of two or more types of internal olefin sulfonates having an average carbon number of 16 to 18. Note that the internal olefin sulfonate having an average carbon number of 16 to 18 is an internal olefin sulfonate having a weighted average of the number of carbon atoms contained in the internal olefin sulfonate of 16 to 18, and the content of the internal olefin sulfonate having 16 to 18 carbon atoms in the component (a2) is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and still more preferably consists of an internal olefin sulfonate having 16 to 18 carbon atoms.

[0016] The internal olefin sulfonate salt of component (a2) can be obtained by sulfonating, neutralizing, and then hydrolyzing an internal olefin having from 16 to 18 carbon atoms or a mixture of internal olefins having an average carbon number of from 16 to 18. There are no particular restrictions on the conditions for sulfonation, neutralization, and hydrolysis, and similarly to component (a1), reference can be made to the conditions described in JP-B No. 49-41179, JP-A No. 2-73051, etc.

[0017] In the internal olefin sulfonate salt of component (a2), examples of the counter cation of the sulfonic acid include hydrogen ions, alkali metal cations, and ammonium. Of these, alkali metal cations are preferred.

[0018] [Component (a3): Internal Olefin with an Average Carbon Number of 16 to 18] Component (a3) ​​may be a single internal olefin with an average carbon number of 16 to 18, a mixture of two or more internal olefin sulfones each having 16 to 18 carbon atoms, or a mixture of two or more internal olefins each having an average carbon number of 16 to 18. Note that an internal olefin with an average carbon number of 16 to 18 is an internal olefin having a weighted average of the number of carbon atoms contained in the internal olefin of 16 to 18, and the content of internal olefins with a carbon number of 16 to 18 in component (a3) ​​is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and still more preferably consists of internal olefins with a carbon number of 16 to 18.

[0019] [Content of Each Component] From the viewpoint of providing a dip-molded product with excellent flexibility and tensile strength, the content of the component (a3) ​​in the anionic surfactant (A1) is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, even more preferably 1.0 parts by mass or more, still more preferably 1.2 parts by mass or more, and is preferably 3 parts by mass or less, more preferably 2.5 parts by mass or less, even more preferably 2.0 parts by mass or less, and still more preferably 1.6 parts by mass or less, relative to 100 parts by mass of the total of the components (a1), (a2), and (a3). The content of the component (a3) ​​in the surfactant composition of the present invention is preferably 0.1 parts by mass or more and 3 parts by mass or less, more preferably 0.3 parts by mass or more and 2.5 parts by mass or less, even more preferably 1.0 parts by mass or more and 2.0 parts by mass or less, and still more preferably 1.2 parts by mass or more and 1.6 parts by mass or less, relative to 100 parts by mass of the total of the components (a1), (a2), and (a3).

[0020] From the viewpoint of providing a dip-molded product with excellent flexibility and tensile strength, the content of the component (a1) in the anionic surfactant (A1) is preferably 40 parts by mass or more, more preferably 50 parts by mass or more, even more preferably 60 parts by mass or more, and even more preferably 70 parts by mass or more, and is preferably 95 parts by mass or less, more preferably 90 parts by mass or less, and even more preferably 85 parts by mass or less, based on 100 parts by mass of the total of the components (a1), (a2), and (a3). The content of the component (a1) is preferably 40 parts by mass or more and 95 parts by mass or less, more preferably 50 parts by mass or more and 90 parts by mass or less, even more preferably 60 parts by mass or more and 85 parts by mass or less, based on 100 parts by mass of the total of the components (a1), (a2), and (a3).

[0021] From the viewpoint of providing a dip-molded product with excellent flexibility and tensile strength, the content of the component (a2) in the anionic surfactant (A1) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and preferably 60 parts by mass or less, more preferably 40 parts by mass or less, even more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less, per 100 parts by mass of the total of the components (a1), (a2), and (a3). The content of the component (a2) is preferably 5 parts by mass or more and 60 parts by mass or less, more preferably 5 parts by mass or more and 40 parts by mass or less, even more preferably 10 parts by mass or more and 30 parts by mass or less, and even more preferably 10 parts by mass or more and 20 parts by mass or less, per 100 parts by mass of the total of the components (a1), (a2), and (a3).

[0022] From the viewpoint of providing a dip-molded product with excellent flexibility and tensile strength, the mass ratio of the component (a1) to the component (a2) in the anionic surfactant (A1) (component (a1) / component (a2)) is preferably 0.25 or more, more preferably 0.8 or more, even more preferably 2 or more, and is preferably 20 or less, more preferably 14 or less, even more preferably 9 or less. The mass ratio (component (a1) / component (a2)) is preferably 0.25 or more and 20 or less, more preferably 0.8 or more and 14 or less, even more preferably 2 or more and 9 or less.

[0023] The total content of the components (a1), (a2), and (a3) ​​in the anionic surfactant (A1) is preferably 95% by mass or more, more preferably 97% by mass or more, even more preferably 99% by mass or more, and preferably 100% by mass or less, from the viewpoint of providing a dip-molded product with excellent flexibility and tensile strength.

[0024] <Method for producing anionic surfactant (A1)> The anionic surfactant (A1) can be produced efficiently by a production method including the steps of obtaining an internal olefin having an average carbon number of from 16 to 18 by a dehydration reaction of an aliphatic alcohol derived from a natural fat or oil and having an average carbon number of from 16 to 18, sulfonating the internal olefin having an average carbon number of from 16 to 18, and neutralizing and then hydrolyzing the sulfonated product to obtain components (a1) to (a3). The anionic surfactant (A1) may also be produced by mixing components (a1) to (a3).

[0025] The aliphatic alcohol having an average carbon number of 16 to 18 is preferably a primary aliphatic alcohol having an average carbon number of 16 to 18. The aliphatic alcohol having an average carbon number of 16 to 18 may be an aliphatic alcohol having a single carbon number of 16 to 18, a mixture of two or more aliphatic alcohols having 16 to 18 carbon atoms, or two or more aliphatic alcohols having an average carbon number of 16 to 18. Note that an aliphatic alcohol having an average carbon number distribution of 16 to 18 is an aliphatic alcohol in which the weighted average of the carbon numbers contained in the aliphatic alcohol is 16 to 18, and the content of aliphatic alcohols having 16 to 18 carbon atoms in the aliphatic alcohol is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and still more preferably 16 to 18 carbon atoms.

[0026] Examples of primary aliphatic alcohols derived from natural fats and oils include those derived from natural fats and oils such as coconut oil, palm oil, palm kernel oil, soybean oil, rapeseed oil, beef tallow, lard, tall oil, and fish oil. From the viewpoint of providing a dip-molded product with excellent flexibility and tensile strength, primary aliphatic alcohols derived from one or more natural fats and oils selected from palm kernel oil and coconut oil are preferred, with palm kernel oil-derived primary aliphatic alcohols being more preferred. Examples of primary aliphatic alcohols derived from natural fats and oils include 1-hexadecanol and 1-octadecanol, with 1-octadecanol being preferred.

[0027] The dehydration reaction of aliphatic alcohols can be carried out by reference to, for example, the liquid-phase dehydration reaction of aliphatic alcohols described in Japanese Patent No. 5221773. The reaction is preferably carried out in the presence of a solid acid catalyst such as alumina or aluminum phosphate, at a reaction temperature of 160°C or higher and 290°C or lower, under reduced pressure of 0.03 MPa or higher and 0.09 MPa or lower or at normal pressure, while introducing nitrogen into the reaction system and removing the generated water from the system.

[0028] The conditions for sulfonating the internal olefin having an average carbon number of 16 to 18 and for neutralizing and hydrolyzing the obtained sulfonated product are not particularly limited, and as mentioned above, reference can be made to the conditions described in JP-B-49-41179 and JP-A-2-73051. The sulfonating agent used in the production method of the present invention is SO ３ Gases include SO ３ In the case of sulfonation with a gas, it is preferable to neutralize with ammonia, an alkali metal hydroxide, etc. The sulfonation reaction is carried out, for example, at a ratio of SO 2 to 1 mole of internal olefin. ３ The reaction can be carried out by reacting 1.0 to 1.2 moles of the gas. The reaction temperature is preferably 20°C to 40°C.

[0029] Neutralization is carried out by reacting with an aqueous alkali solution such as sodium hydroxide, ammonia, or 2-aminoethanol in an amount of 1.0 to 1.5 molar times the theoretical amount of sulfonic acid groups. The hydrolysis reaction is preferably carried out in the presence of water at 90 to 200°C for 30 minutes to 3 hours. These reactions can be carried out continuously. After the reaction is complete, the product can be purified by extraction, washing, or the like.

[0030] The contents of the components (a1) to (a3) ​​in the anionic surfactant (A1) produced by the above production method can be adjusted by adjusting the aging time after the sulfonation reaction and before neutralization. The shorter the aging time before neutralization, the higher the content of the component (a1) and the lower the content of the component (a2). In addition, the ratio of SO to 1 mole of internal olefin is ３ The content of component (a3) ​​can be adjusted by adjusting the amount of gas used. The content of component (a3) ​​may also be adjusted by post-addition so that the content of component (a3) ​​falls within a desired range. In this case, component (a3) ​​may be added to a composition obtained by sulfonating an internal olefin having an average carbon number of 16 to 18 and neutralizing and then hydrolyzing the resulting sulfonated product, in an amount of 0.1 to 3 parts by mass per 100 parts by mass of the total of components (a1), (a2), and (a3) ​​in the composition.

[0031] <<Surfactant (A2)>> The surfactant (A2) comprises a linear or branched alkyl diphenyl ether disulfonate having an average carbon number of 16 or more and 18 or less in the alkyl group. The surfactant (A2) may be a single linear or branched alkyl diphenyl ether disulfonate having an alkyl group carbon number of 16 or more and 18 or less, a mixture of linear or branched alkyl diphenyl ether disulfonates having two or more alkyl groups carbon numbers of 16 or more and 18 or less, or a mixture of two or more linear or branched alkyl diphenyl ether disulfonates having an alkyl group carbon number of 16 or more and 18 or less. The linear or branched alkyl diphenyl ether disulfonate having an average alkyl group carbon number of 16 to 18 refers to a linear or branched alkyl diphenyl ether disulfonate having a weighted average of the carbon numbers in the alkyl group of 16 to 18, and the linear or branched alkyl diphenyl ether disulfonate preferably contains linear or branched alkyl diphenyl ether disulfonates having an alkyl group carbon number of 16 to 18 in an amount of 80 mass% or more, more preferably 90 mass% or more, even more preferably 95 mass% or more, and even more preferably contains linear or branched alkyl diphenyl ether disulfonates having an alkyl group carbon number of 16 to 18. The surfactant (A2) may have two sulfonate groups substituted on either one of the two phenyl groups constituting the diphenyl ether, or one sulfonate group substituted on each of the phenyl groups, but it is preferred that one sulfonate group substituted on each of the phenyl groups.

[0032] In the sulfonate salt of the surfactant (A2), examples of the counter cation of the sulfonic acid include alkali metal cations and ammonium. Among these, alkali metal cations are preferred, and one selected from the group consisting of lithium ion, sodium ion, and potassium ion is more preferred, with sodium ion being even more preferred.

[0033] The surfactant (A2) may be a commercially available product. Examples of commercially available surfactants (A2) include "DOWFAX (trademark) 8390" (manufactured by Dow Corporation).

[0034] The surfactant (A) contains at least one of anionic surfactant (A1) and anionic surfactant (A2), and may contain both anionic surfactant (A1) and anionic surfactant (A2). When the surfactant (A) contains both anionic surfactant (A1) and anionic surfactant (A2), the mass ratio of the anionic surfactant (A1) to the anionic surfactant (A2) in the surfactant (A) ((A1) / (A2)) is preferably 0.1 or more, more preferably 0.4 or more, even more preferably 0.8 or more, and preferably 10 or less, more preferably 2.5 or less, even more preferably 1.25 or less, from the viewpoint of providing a dip-molded product with excellent flexibility and tensile strength. The mass ratio ((A1) / (A2)) is preferably 0.1 or more and 10 or less, more preferably 0.4 or more and 2.5 or less, even more preferably 0.8 or more and 1.25 or less.

[0035] <Polymer (B)> The polymer (B) contained in the latex composition for dip molding of the present invention is a copolymer containing a structural unit (B1) derived from a conjugated diene monomer, a structural unit (B2) derived from an ethylenically unsaturated carboxylic acid monomer, and a structural unit (B3) derived from an ethylenically unsaturated nitrile monomer.

[0036] [Structural Unit (B1) Derived from Conjugated Diene Monomer] The polymer (B) contains a structural unit (B1) derived from a conjugated diene monomer. Examples of the conjugated diene monomer include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 1,3-pentadiene, and chloroprene, with 1,3-butadiene being preferred. The conjugated diene monomer can be used alone or in combination of two or more.

[0037] In order to ensure that the dip-molded product exhibits excellent flexibility and tensile strength, the content of the structural unit (B1) derived from a conjugated diene monomer in the polymer (B) is preferably 50% by mass or more, more preferably 53% by mass or more, even more preferably 55% by mass or more, and preferably 78% by mass or less, more preferably 73% by mass or less, even more preferably 70% by mass or less, based on 100% by mass of the total content of the structural unit (B1) derived from a conjugated diene monomer, the structural unit (B2) derived from an ethylenically unsaturated carboxylic acid monomer, and the structural unit (B3) derived from an ethylenically unsaturated nitrile monomer. The content of the structural unit (B1) derived from a conjugated diene monomer in the polymer (B) is preferably 50% by mass or more and 78% by mass or less, more preferably 53% by mass or more and 73% by mass or less, even more preferably 55% by mass or less, based on 100% by mass of the total content.

[0038] [Structural Unit (B2) Derived from an Ethylenically Unsaturated Carboxylic Acid Monomer] The polymer (B) contains a structural unit (B2) derived from an ethylenically unsaturated carboxylic acid monomer. Examples of the ethylenically unsaturated carboxylic acid monomer include ethylenically unsaturated monocarboxylic acid monomers such as acrylic acid and methacrylic acid; ethylenically unsaturated polycarboxylic acid monomers such as itaconic acid, maleic acid, and fumaric acid; ethylenically unsaturated polycarboxylic acid partial ester monomers such as monobutyl fumarate, monobutyl maleate, and mono-2-hydroxypropyl maleate; and monomers that generate a carboxyl group upon hydrolysis, such as ethylenically unsaturated polycarboxylic acid anhydrides such as maleic anhydride and citraconic anhydride. Ethylenically unsaturated monocarboxylic acid monomers are preferred, with acrylic acid and methacrylic acid being more preferred, and methacrylic acid being particularly preferred. The ethylenically unsaturated carboxylic acid monomers can be used alone or in combination of two or more.

[0039] In order to ensure that the dip-molded product exhibits excellent flexibility and tensile strength, the content of the structural unit (B2) derived from an ethylenically unsaturated carboxylic acid monomer in the polymer (B) is preferably 2% by mass or more, more preferably 3% by mass or more, even more preferably 4% by mass or more, and preferably 10% by mass or less, more preferably 8% by mass or less, even more preferably 7% by mass or less, based on 100% by mass of the total content of the structural unit (B1) derived from a conjugated diene monomer, the structural unit (B2) derived from an ethylenically unsaturated carboxylic acid monomer, and the structural unit (B3) derived from an ethylenically unsaturated nitrile monomer. The content of the structural unit (B2) derived from an ethylenically unsaturated carboxylic acid monomer in the polymer (B) is preferably 2% by mass or more and 10% by mass or less, more preferably 3% by mass or more and 8% by mass or less, even more preferably 4% by mass or more, based on 100% by mass of the total content.

[0040] [Structural Unit (B3) Derived from Ethylenically Unsaturated Nitrile Monomer] The polymer (B) contains a structural unit (B3) derived from an ethylenically unsaturated nitrile monomer. Examples of the ethylenically unsaturated nitrile monomer include acrylonitrile, methacrylonitrile, fumaronitrile, α-chloroacrylonitrile, and α-cyanoethylacrylonitrile. Acrylonitrile and methacrylonitrile are preferred, and acrylonitrile is more preferred. The ethylenically unsaturated nitrile monomer can be used alone or in combination of two or more.

[0041] In order to ensure that the dip-molded product exhibits excellent flexibility and tensile strength, the content of the structural unit (B3) derived from an ethylenically unsaturated nitrile monomer in the polymer (B) is preferably 20% by mass or more, more preferably 23% by mass or more, even more preferably 25% by mass or more, and preferably 40% by mass or less, more preferably 38% by mass or less, even more preferably 36% by mass or less, based on 100% by mass of the total content of the structural unit (B1) derived from a conjugated diene monomer, the structural unit (B2) derived from an ethylenically unsaturated carboxylic acid monomer, and the structural unit (B3) derived from an ethylenically unsaturated nitrile monomer. The content of the structural unit (b3) derived from an ethylenically unsaturated nitrile monomer in the polymer (B) is preferably 20% by mass or more and 40% by mass or less, more preferably 23% by mass or more and 38% by mass or less, even more preferably 25% by mass or less, based on 100% by mass of the total content.

[0042] <Method for Producing Polymer (B)> The polymer (B) can be produced by a production method including a step of emulsion polymerizing raw material monomers including the conjugated diene monomer, the ethylenically unsaturated carboxylic acid monomer, and the ethylenically unsaturated nitrile monomer in a dispersion medium in the presence of a surfactant, preferably the surfactant (A).

[0043] In the production of polymer (B), the polymerization conversion rate of the raw material monomers is nearly 100%, and therefore the contents of the conjugated diene monomer, ethylenically unsaturated carboxylic acid monomer, and ethylenically unsaturated nitrile monomer used in the polymerization are nearly equal to the contents of the conjugated diene monomer-derived structural units, ethylenically unsaturated carboxylic acid monomer-derived structural units, and ethylenically unsaturated nitrile monomer-derived structural units in polymer (B). Therefore, with respect to the contents of the conjugated diene monomer, the ethylenically unsaturated carboxylic acid monomer, and the ethylenically unsaturated nitrile monomer in the raw material monomers, it is preferable that the content of the conjugated diene monomer is 50% by mass or more and 78% by mass or less, the content of the ethylenically unsaturated carboxylic acid monomer is 2% by mass or more and 10% by mass or less, and the content of the ethylenically unsaturated nitrile monomer is 20% by mass or more and 40% by mass or less, relative to the total content of these, because this will result in the contents of the conjugated diene monomer-derived structural unit, the ethylenically unsaturated carboxylic acid monomer-derived structural unit, and the ethylenically unsaturated nitrile monomer-derived structural unit in the polymer (B) being within the above ranges.

[0044] The amount of surfactant (A) used in the production of polymer (B) is, from the viewpoint of reducing the average particle size of polymer (B), preferably 0.05 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 1 part by mass or more, and preferably 10 parts by mass or less, more preferably 7 parts by mass or less, and even more preferably 5 parts by mass or less, relative to 100 parts by mass of raw material monomers. The amount of surfactant (A) used is preferably 0.05 parts by mass or more and 10 parts by mass or less, more preferably 0.5 parts by mass or more and 7 parts by mass or less, and even more preferably 1 part by mass or more and 5 parts by mass or less, relative to 100 parts by mass of raw material monomers. The surfactant (A) can be used alone or in combination of two or more types.

[0045] In producing the polymer (B), a surfactant other than the surfactant (A) can be used in addition to or instead of the surfactant (A). Examples of other components include anionic surfactants such as alkylbenzenesulfonic acid or a salt thereof, alkyl sulfate or a salt thereof, alkyl ether sulfate or a salt thereof, fatty acid soap, and alkyl ether carboxylic acid or a salt thereof; and nonionic surfactants such as alcohol ethoxylate, alkyl polyglycoside, and alkanolamide. Among these, alkylbenzenesulfonic acid or a salt thereof is preferred, alkylbenzenesulfonic acid or a salt thereof having an average alkyl group carbon number of 8 to 18 is more preferred, and laurylbenzenesulfonic acid or a salt thereof is even more preferred.

[0046] Any radical polymerization initiator used in the production of polymer (B) can be used as long as it is one used in conventional emulsion polymerization. Examples of radical polymerization initiators include persulfates such as potassium persulfate and ammonium persulfate; organic peroxides such as hydrogen peroxide, t-butyl hydroperoxide, benzoyl peroxide, and cumene hydroperoxide; and azo initiators such as azobisdiisobutyronitrile and 2,2-azobis(2-amidinopropane) dihydrochloride. From the viewpoints of polymerization reactivity, workability, and economy, persulfates are preferred. Furthermore, redox initiators in which a peroxide compound is combined with a reducing agent such as sodium sulfite, Rongalite, or ascorbic acid can also be used as the polymerization initiator.

[0047] In the production of the polymer (B), further polymerization auxiliary materials such as a chain transfer agent, a dispersant, an oxygen scavenger, a chelating agent, a particle size modifier, a surfactant, a molecular weight modifier, an inorganic salt, a pH adjuster, etc. may be used, if necessary. There are no particular restrictions on the type and amount of these.

[0048] The dispersion medium in the method for producing the polymer (B) is an aqueous solvent, preferably water, such as soft water, distilled water, or deionized water.

[0049] In the method for producing polymer (B), the amount of raw material monomer charged is preferably 20% by mass or more, more preferably 30% by mass or more, and preferably 60% by mass or less, more preferably 50% by mass or less, based on the total mass of the raw material monomer and the dispersion medium, from the viewpoint of production efficiency. The amount of raw material monomer charged is preferably 20% by mass or more and 60% by mass or less, more preferably 30% by mass or more and 50% by mass or less, based on the total mass of the raw material monomer and the dispersion medium. The emulsion polymerization conditions in the method for producing polymer (B) are not particularly limited, but the polymerization temperature is adjusted depending on the decomposition temperature of the polymerization initiator, and is preferably 20°C or more and 80°C or less. The polymerization time is preferably 8 hours or more and 24 hours or less.

[0050] The emulsion polymerization may be terminated by adding a pH adjuster and a polymerization terminator. The pH of the reaction system after termination of the emulsion polymerization is preferably 7.0 or more and 10.5 or less, more preferably 7.5 or more and 9.0 or less. After termination of the polymerization, a pH adjuster, a surfactant, an antioxidant, a preservative, an antifungal agent, an inorganic salt, a plasticizer, a wax, or the like may be added. The type and amount of these additives are also not particularly limited.

[0051] [Method for Producing a Dip-Forming Latex Composition] When emulsion polymerization of polymer (B) is carried out using surfactant (A), the reaction system may be used as a dip-forming latex composition. That is, emulsion polymerization of a conjugated diene monomer, an ethylenically unsaturated carboxylic acid monomer, and an ethylenically unsaturated nitrile monomer using surfactant (A) is a method for producing a dip-forming latex composition. When emulsion polymerization of polymer (B) is carried out without using surfactant (A), the dip-forming latex composition may be produced by mixing surfactant (A) and polymer (B).

[0052] As described above, the surfactant (A) can be used for emulsion polymerization of a conjugated diene monomer, an ethylenically unsaturated carboxylic acid monomer, and an ethylenically unsaturated nitrile monomer. In the method for producing the polymer (B), the surfactant (A) or a composition containing the surfactant (A) is an emulsion polymerization agent for the conjugated diene monomer, the ethylenically unsaturated carboxylic acid monomer, and the ethylenically unsaturated nitrile monomer. Components other than the surfactant (A) in the composition containing the surfactant (A) as an emulsion polymerization agent include other surfactants than the surfactant (A) and polymerization secondary materials.

[0053] The surfactant (A) is used not only as a surfactant during emulsion polymerization of the polymer (B) but also as a stabilizer for stabilizing the dip-molding latex composition or dip-molding latex-blended composition containing the polymer (B) after emulsion polymerization. When the surfactant (A) contains an anionic surfactant (A2), the dispersion state of the dip-molding latex composition or dip-molding latex-blended composition containing the polymer (B) after emulsion polymerization can be stabilized. As a result, the dip-molding latex composition or dip-molding latex-blended composition exhibits an effect of reducing aggregates, and further, the number of pinholes in gloves made using the dip-molding latex-blended composition can be reduced, which is preferable. Furthermore, the surfactant (A) or a composition containing the surfactant (A) is a stabilizer for the dip-molding latex composition or dip-molding latex-blended composition containing the polymer (B). In the composition containing the surfactant (A) as a stabilizer, components other than the surfactant (A) include other surfactants than the surfactant (A), dispersants, chelating agents, pH adjusters, particle size adjusters, etc.

[0054] The average particle size of the polymer (B) is preferably 100 nm or more, more preferably 105 nm or more, and even more preferably 110 nm or more from the viewpoint of polymerization stability, and is preferably 300 nm or less, more preferably 200 nm or less, even more preferably 150 nm or less, and still more preferably 130 nm or less from the viewpoint of excellent flexibility and tensile strength of the dip-molded product. The average particle size of the polymer (B) is preferably 100 nm or more and 300 nm or less, more preferably 105 nm or more and 200 nm or less, even more preferably 110 nm or more and 150 nm or less, and still more preferably 110 nm or more and 130 nm or less.

[0055] (Other Components) The dip-molding latex composition of the present invention may further contain other components to the extent that the effects of the present invention are not impaired. Examples of such other components include sultones, which are by-products in the production of the anionic surfactant (A1); nonionic surfactants such as raw material monomers for the polymer (B), alcohol ethoxylates, alkyl polyglycosides, and alkanolamides; anionic surfactants such as alkylbenzenesulfonic acid or its salts, alkyl sulfates or its salts, alkyl ether sulfates or its salts, fatty acid soaps, and alkyl ether carboxylic acids or their salts; and water-soluble protective colloids. Alkylbenzenesulfonic acid or its salts are preferred, and alkylbenzenesulfonic acid or its salts having an average alkyl group carbon number of 8 to 18 are more preferred. The dip-molding latex composition of the present invention may also contain secondary polymerization materials, such as chain transfer agents, dispersants, oxygen scavengers, chelating agents, and particle size modifiers, which may be used in the production method of the polymer (B).

[0056] The solid content of the dip-molding latex composition of the present invention is preferably 20% by mass or more, more preferably 30% by mass or more, and preferably 60% by mass or less, more preferably 50% by mass or less, from the viewpoint of providing a dip-molded product with excellent flexibility and tensile strength. The solid content is preferably 20% by mass or more and 60% by mass or less, more preferably 30% by mass or more and 50% by mass or less. Furthermore, the content of polymer (B) in the solid content of the dip-molding latex composition is preferably 90% by mass or more, more preferably 93% by mass or more, and even more preferably 95% by mass or more.

[0057] The content of the surfactant (A) in the dip-molding latex composition of the present invention is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, even more preferably 0.3 parts by mass or more, and preferably 10 parts by mass or less, more preferably 7 parts by mass or less, and even more preferably 5 parts by mass or less, relative to 100 parts by mass of the polymer (B). The content of the surfactant (A) is preferably 0.05 parts by mass or more and 10 parts by mass or less, more preferably 0.1 parts by mass or more and 7 parts by mass or less, and even more preferably 0.3 parts by mass or more and 5 parts by mass or less, relative to 100 parts by mass of the polymer (B).

[0058] When the dip-molding latex composition of the present invention contains an alkylbenzenesulfonic acid or a salt thereof having an alkyl group having from 8 to 18 carbon atoms, the content of the alkylbenzenesulfonic acid or a salt thereof in the dip-molding latex composition is preferably at least 0.05% by mass, more preferably at least 0.1% by mass, even more preferably at least 0.3% by mass, and preferably at most 10% by mass, more preferably at most 7% by mass, and even more preferably at most 5% by mass, based on the total content of the surfactant (A), the polymer (B), and the alkylbenzenesulfonic acid or a salt thereof, from the viewpoint of providing a dip-molded product with excellent flexibility and tensile strength. The content of the alkylbenzenesulfonic acid or a salt thereof is preferably at least 0.05% by mass and at most 10% by mass, more preferably at least 0.1% by mass and at most 7% by mass, even more preferably at most 0.3% by mass, based on 100% by mass of the total content. In this case, from the viewpoint of the dip-molded product exhibiting excellent flexibility and tensile strength, the content of surfactant (A) is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.3% by mass or more, and preferably 10% by mass or less, more preferably 7% by mass or less, and even more preferably 5% by mass or less, based on the total content. The content of surfactant (A) is preferably 0.05% by mass or more and 10% by mass or less, more preferably 0.1% by mass or more and 7% by mass or less, and even more preferably 0.3% by mass or more and 5% by mass or less, based on the total content. Furthermore, from the viewpoint of the dip-molded product exhibiting excellent flexibility and tensile strength, the content of polymer (B) is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, and preferably 99.9% by mass or less, more preferably 98% by mass or less, and even more preferably 97% by mass or less, based on the total content. The content of polymer (B) is preferably 80% by mass or more and 97% by mass or less, more preferably 85% by mass or more and 98% by mass or less, and even more preferably 90% by mass or more and 99.9% by mass or less, based on the total content.

[0059] <Latex Blended Composition for Dip Molding> The latex blended composition for dip molding of the present invention is a blended composition obtained by blending the above-mentioned latex composition for dip molding. The latex blended composition for dip molding of the present invention also includes a latex blended composition for dip molding obtained by blending a surfactant (A) with a latex composition containing a polymer (B) but not containing a surfactant (A). The latex blended composition for dip molding contains, in addition to the latex composition for dip molding, a surfactant, a crosslinking agent, a metal oxide, a lubricant, etc.

[0060] Examples of the surfactant contained in the latex blend composition for dip molding of the present invention include the above-mentioned surfactant (A); anionic surfactants such as alkylbenzenesulfonic acid or a salt thereof, alkyl sulfuric acid or a salt thereof, alkyl ether sulfuric acid or a salt thereof, fatty acid soap, and alkyl ether carboxylic acid or a salt thereof; and nonionic surfactants such as alcohol ethoxylate, alkyl polyglycoside, and alkanolamide.

[0061] The content of the surfactant in the latex blend composition for dip molding is preferably 10 parts by mass or less, more preferably 7 parts by mass or less, and even more preferably 5 parts by mass or less, based on 100 parts by mass of the polymer (B) in the latex blend composition for dip molding, from the viewpoint of the dip-molded product exhibiting excellent flexibility and tensile strength.

[0062] The content of the surfactant (A) in the latex blend composition for dip molding of the present invention is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, even more preferably 2 parts by mass or more, and preferably 10 parts by mass or less, more preferably 7 parts by mass or less, and even more preferably 5 parts by mass or less, relative to 100 parts by mass of the polymer (B), from the viewpoint of providing a dip-molded product with excellent flexibility and tensile strength. The content of the surfactant (A) is preferably 0.5 parts by mass or more and 10 parts by mass or less, more preferably 1 part by mass or more and 7 parts by mass or less, and even more preferably 2 parts by mass or less, relative to 100 parts by mass of the polymer (B).

[0063] Examples of the crosslinking agent contained in the dip-molding latex compounded composition of the present invention include sulfur-based crosslinking agents and epoxy-based crosslinking agents.

[0064] Examples of sulfur-based crosslinking agents include sulfur such as powdered sulfur, sulfur flowers, precipitated sulfur, colloidal sulfur, surface-treated sulfur, and insoluble sulfur; sulfur-containing compounds such as sulfur chloride, sulfur dichloride, morpholine disulfide, alkylphenol disulfide, dibenzothiazyl disulfide, caprolactam disulfide, phosphorus-containing polysulfide, and polymeric polysulfides; and sulfur-donating compounds such as tetramethylthiuram disulfide, dimethyldithiocarbamate, and 2-(4'-morpholinodithio)benzothiazole. These sulfur-based crosslinking agents may be used alone or in combination of two or more.

[0065] The content of the sulfur-based crosslinking agent in the latex blend composition for dip molding is preferably 2 parts by mass or less, more preferably 1.7 parts by mass or less, and even more preferably 1.5 parts by mass or less, based on 100 parts by mass of the polymer (B) in the latex blend composition for dip molding, from the viewpoint of the dip-molded product exhibiting excellent flexibility and tensile strength.

[0066] When the dip molding latex compounding composition contains a sulfur-based crosslinking agent as a crosslinking agent, the dip molding latex compounding composition preferably further contains a crosslinking accelerator (vulcanization accelerator) and zinc oxide in addition to the sulfur-based crosslinking agent. The crosslinking accelerator (vulcanization accelerator) is not particularly limited, but examples thereof include dithiocarbamic acids such as diethyldithiocarbamic acid, dibutyldithiocarbamic acid, di-2-ethylhexyldithiocarbamic acid, dicyclohexyldithiocarbamic acid, diphenyldithiocarbamic acid, and dibenzyldithiocarbamic acid, and zinc salts thereof; 2-mercaptobenzothiazole, 2-mercaptobenzothiazole zinc, 2-mercaptothiazoline, dibenzothiazyl disulfide, 2-(2,4-dinitrophenylthio)benzoate, and the like. Examples of crosslinking accelerators include zinc diethyldithiocarbamate, zinc dibutyldithiocarbamate, 2-mercaptobenzothiazole, and zinc 2-mercaptobenzothiazole. These crosslinking accelerators may be used alone or in combination of two or more.

[0067] The content of the crosslinking accelerator in the latex blend composition for dip molding is preferably 2 parts by mass or less, more preferably 1.5 parts by mass or less, and even more preferably 1.0 part by mass or less, per 100 parts by mass of the polymer (B) in the latex blend composition for dip molding, from the viewpoint of the dip-molded product exhibiting excellent flexibility and tensile strength.

[0068] Examples of epoxy-based crosslinking agents include bifunctional epoxy-based crosslinking agents such as ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, resorcinol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, 1,4-butanediol diglycidyl ether, and hydrogenated bisphenol A diglycidyl ether; and polyfunctional epoxy-based crosslinking agents such as sorbitol polyglycidyl ether, glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, diglycerol polyglycidyl ether, and polyglycerol polyglycidyl ether. These epoxy-based crosslinking agents may be used alone or in combination of two or more.

[0069] The content of the epoxy crosslinking agent in the latex blend composition for dip molding is preferably 2 parts by mass or less, more preferably 1.5 parts by mass or less, and even more preferably 1.2 parts by mass or less, per 100 parts by mass of the polymer (B) in the latex blend composition for dip molding, from the viewpoint of the dip-molded product exhibiting excellent flexibility and tensile strength.

[0070] The metal oxide is not particularly limited, but examples thereof include zinc oxide, magnesium oxide, titanium oxide, calcium oxide, lead oxide, iron oxide, copper oxide, tin oxide, nickel oxide, chromium oxide, cobalt oxide, and aluminum oxide. Among these, zinc oxide is preferred from the viewpoint of further improving the tensile strength of the resulting dip-molded product. Titanium oxide is also preferably contained as a pigment and / or color adjuster. These metal oxides may be used alone or in combination.

[0071] The content of the metal oxide in the latex compounded composition for dip molding is preferably 5 parts by mass or less, more preferably 4 parts by mass or less, and even more preferably 3 parts by mass or less, per 100 parts by mass of the polymer (B) in the latex compounded composition for dip molding, from the viewpoint of providing a dip-molded product with excellent flexibility and tensile strength. Among these, the content of zinc oxide in the latex compounded composition for dip molding is preferably 3 parts by mass or less, more preferably 2 parts by mass or less, and even more preferably 1.5 parts by mass or less, per 100 parts by mass of the polymer (B) in the latex compounded composition for dip molding, from the viewpoint of providing a dip-molded product with even better flexibility and tensile strength.

[0072] Examples of the lubricant contained in the latex blend composition for dip molding of the present invention include silicone, liquid paraffin, paraffin wax, fatty acid metal salts such as metal stearates and metal laurates, fatty acid amides, fatty acid waxes, and higher fatty acid waxes.

[0073] When the latex compounding composition for dip molding contains a lubricant, the content thereof is preferably 2 parts by mass or less, more preferably 1 part by mass or less, even more preferably 0.5 parts by mass or less, and still more preferably 0 part by mass, per 100 parts by mass of the polymer (B) in the latex compounding composition for dip molding, from the viewpoint of preventing bleeding from the dip-molded product.

[0074] <Method for Producing a Latex-Blended Composition for Dip Molding> The latex-blended composition for dip molding can be produced by a production method including a step of mixing the above-mentioned surfactant, the above-mentioned crosslinking agent, and the like, with the latex composition for dip molding, as needed. Alternatively, the latex-blended composition for dip molding can be produced by a production method including a step of mixing a latex composition containing polymer (B) but not surfactant (A), surfactant (A), and, as needed, the above-mentioned surfactant other than surfactant (A), the above-mentioned crosslinking agent, and the like. The order of mixing the dip-molding latex composition or the composition containing polymer (B) with the surfactant, crosslinking agent, and the like is not particularly limited. However, it is preferable to stabilize the system by adding the surfactant, and then add the remaining components, such as the crosslinking agent. Mixing is preferably performed under stirring, and can be performed using, for example, a mixer, a ball mill, a kneader, a disperser, or the like.

[0075] Furthermore, before mixing the dip-molding latex composition with the surfactant, crosslinking agent, etc., the pH of the dip-molding latex composition or the composition containing polymer (B) may be adjusted. The pH can be adjusted using an aqueous solution of an alkali metal hydroxide, such as sodium hydroxide, lithium hydroxide, or potassium hydroxide, or aqueous ammonia. The pH of the dip-molding latex composition after the pH adjustment is preferably 7.0 or higher, more preferably 7.5 or higher, and preferably 9.5 or lower, more preferably 9.0 or lower. The pH of the dip-molding latex composition after the pH adjustment is preferably 8.5 to 11.0, more preferably 9.0 to 10.5.

[0076] The surface tension of the latex compounded composition for dip molding is preferably 20 mN / m or more, more preferably 25 mN / m or more, even more preferably 28 mN / m or more, and is preferably 40 mN / m or less, more preferably 36 mN / m or less, even more preferably 34 mN / m or less, from the viewpoints of moldability during dip molding and suppressing the occurrence of pinholes in the dip-molded product. The surface tension of the latex compounded composition for dip molding is preferably 20 mN / m or more and 40 mN / m or less, more preferably 25 mN / m or more and 36 mN / m or less, even more preferably 28 mN / m or less.

[0077] <Dip-molded product> The dip-molded product of the present invention is a cured product of the latex compounded composition for dip molding, obtained by dip-molding the above-mentioned latex compounded composition for dip molding. Examples of dip-molded products include medical products such as baby bottle nipples, droppers, conduits, water pillows, and condoms; toys and sports equipment such as balloons, dolls, and balls; industrial products such as pressure-molding bags and gas storage bags; medical, household, agricultural, fishing, and industrial gloves; and finger cots. The dip-molded product of the present invention is preferably a glove, more preferably a medical glove, and even more preferably a surgical glove, because it has excellent flexibility and tensile strength.

[0078] The film thickness of the dip-molded product of the present invention is not particularly limited, but is preferably 0.001 mm or more, more preferably 0.005 mm or more, even more preferably 0.01 mm or more, and is preferably 1.0 mm or less, more preferably 0.5 mm or less, even more preferably 0.1 mm or less. The film thickness of the dip-molded product of the present invention is preferably 0.001 mm or more and 1.0 mm or less, more preferably 0.005 mm or more and 0.5 mm or less, even more preferably 0.01 mm or more and even more preferably 0.1 mm or less.

[0079] <Method for producing dip-molded product> As a method for producing a dip-molded product, a usual method for molding the above-mentioned latex blend composition for dip-molding may be adopted, and examples thereof include a direct dipping method, an anodic adhesion dipping method, a Teague adhesion dipping method, etc. Among these, the anodic adhesion dipping method is preferred in that a dip-molded product having a uniform thickness can be easily obtained.

[0080] In the case of the anodic coagulation dipping method, for example, a dip-forming mold can be immersed in a coagulant solution to adhere the coagulant to the surface of the dip-forming mold, and then the mold can be immersed in a latex compounded composition for dip-forming to form a dip-forming layer on the surface of the dip-forming mold. The immersion time of the dip-forming mold in the latex compounded composition for dip-forming is preferably 5 seconds or more, more preferably 10 seconds or more, from the viewpoint of obtaining a molded product with a sufficient film thickness, and is preferably 1 minute or less, more preferably 30 seconds or less, from the viewpoint of productivity.

[0081] The dip-forming mold is not particularly limited, and various materials such as ceramic, glass, metal, and plastic can be used. The mold may have a desired shape according to the shape of the dip-formed product. For example, when the dip-formed product is a glove, it is preferable to use various types of molds for gloves, such as a mold having a shape from the wrist to the fingertips, as the mold for covering the substrate.

[0082] Examples of coagulants include metal halides such as barium chloride, calcium chloride, magnesium chloride, zinc chloride, and aluminum chloride; nitrates such as barium nitrate, calcium nitrate, and zinc nitrate; acetates such as barium acetate, calcium acetate, and zinc acetate; and sulfates such as calcium sulfate, magnesium sulfate, and aluminum sulfate. Of these, calcium nitrate is preferred. These coagulants are typically used as solutions in water, alcohol, or a mixture thereof. The concentration of the coagulant in the coagulant solution is preferably 5% by mass or more and 50% by mass or less, more preferably 10% by mass or more and 30% by mass or less. The coagulant solution may contain an anionic and / or nonionic surfactant to improve wettability, and may contain a lubricant component to improve demoldability. Examples of lubricant components include talc, calcium carbonate, corn starch, calcium stearate, ammonium stearate, magnesium stearate, zinc stearate, and other metal soaps, as well as inorganic fillers such as calcium carbonate and talc. The concentration of the lubricant in the coagulant solution is preferably 1% by mass or more and 5% by mass or less, and more preferably 1% by mass or more and 3% by mass or less.

[0083] The dip-molded layer thus obtained is usually subjected to a heat treatment to crosslink it. Before the heat treatment, the layer may be immersed in water, preferably warm water at 30°C or higher and 70°C or lower, for 1 minute to 60 minutes to remove water-soluble impurities (e.g., excess emulsifier, coagulant, etc.). This operation may be performed after the heat treatment of the dip-molded layer, but is preferably performed before the heat treatment in order to more efficiently remove water-soluble impurities.

[0084] The dip-molded layer thus obtained is then crosslinked by heat treatment at a temperature of 80°C to 150°C for 10 to 120 minutes. The heating method can be external heating using infrared rays or hot air, or internal heating using high frequency waves. Of these, heating using hot air is preferred.

[0085] After heating, the dip-molded layer is washed with water, dried, and then demolded from the dip-molding mold to obtain a dip-molded product. Before demolding the dip-molded layer from the dip-molding mold, the dip-molded product may be immersed in a chlorinated bath containing sodium hypochlorite and hydrochloric acid to adjust the active chlorine concentration, in order to reduce the stickiness of the dip-molded product. The active chlorine concentration is preferably 500 ppm or more and 2000 ppm or less, more preferably 700 ppm or more and 1500 ppm or less. The immersion time is preferably 30 seconds or more and 2 minutes or less.

[0086] After removal from the dip-forming mold, the dip-formed layer may be further subjected to a heat treatment at a temperature of 60° C. to 120° C. for 10 minutes to 120 minutes. The dip-formed product may further have a surface treatment layer formed on its inner and / or outer surface.

[0087] According to the present invention, there are provided a latex composition for dip molding, a latex-blended composition for dip molding prepared by blending the latex composition for dip molding, a method for producing a dip-molded product prepared by molding the latex composition for dip molding or the latex-blended composition for dip molding, a method for producing a latex composition for dip molding, and a dip-molded product excellent in flexibility and tensile strength.

[0088] The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples in any way.

[0089] [Production of dip-molding latex composition] Example 1 After the inside of a pressure-resistant autoclave equipped with a stirrer was purged with nitrogen, 68.0 parts by mass of 1,3-butadiene, 27.0 parts by mass of acrylonitrile, 5.0 parts by mass of methacrylic acid, 3.0 parts by mass of surfactant A1-1 as surfactant (A), 0.5 parts by mass of t-dodecyl mercaptan as a chain transfer agent, 1.0 part by mass of β-naphthalenesulfonic acid formalin condensate sodium salt (manufactured by Kao Corporation: Demol T-45A) as a dispersant, 0.01 part by mass of sodium dithionite as an oxygen scavenger, 0.1 part by mass of ethylenediaminetetraacetic acid (EDTA) (manufactured by Chelest Co., Ltd.: Chelest 400G) as a chelating agent, 0.1 part by mass of potassium pyrophosphate as a particle size modifier, 0.2 part by mass of potassium persulfate as a polymerization initiator, and 150 parts by mass of soft water were added, and emulsion polymerization was carried out for 17 hours while maintaining the temperature at 40°C with stirring. After confirming that the polymerization conversion rate was 95% or higher, 10% aqueous ammonia was added as a pH adjuster and sodium nitrite as a polymerization terminator to terminate the polymerization reaction. Unreacted 1,3-butadiene, acrylonitrile, and methacrylic acid were removed from the reaction system under reduced pressure, and the solids concentration was adjusted to 45% by mass and the pH to 8.3 using aqueous ammonia. Subsequently, 0.5 parts by mass of an antioxidant (Bostex 362, manufactured by AKRON DISPERSIONS) was added to 100 parts by mass of the resulting polymer (B), yielding a dip-molding latex composition 1. The surfactant A1-1 used above was an anionic surfactant (A1) containing 82.7% by mass of hydroxyoctadecylsulfonic acid as the (a1) component, 15.8% by mass of octadecenylsulfonic acid as the (a2) component, and 1.5% by mass of octadecene as the (a3) ​​component. The polymerization conversion rate was determined by the following method. About 2 g of the solid content of dip-molding latex composition 1 was accurately weighed on an aluminum dish, and 3 g of a 5% aqueous solution of hydroquinone and 10 g of ethanol were added thereto. The mixture was heated at 130°C for 30 minutes to evaporate to dryness, and then cooled, and the weight of the evaporated dryness was accurately weighed. The weight of the evaporated dryness was subtracted from the weight of the added hydroquinone and divided by the weight of the collected latex to calculate the solid content concentration of the latex in percent.The polymerization conversion rate (%) was calculated by subtracting the total amount (%) of non-volatile components other than polymer components in the latex from the solid content concentration (%) of the obtained latex, dividing the obtained value by the total amount (%) of monomers in the latex, and multiplying this value by 100. The polymerization conversion rate (%) was 95.4%. The weight average particle size of polymer (B) in the obtained dip molding latex composition 1 was measured with a laser diffraction particle size analyzer Mastersizer 3000 manufactured by Maruban Co., Ltd., and was found to be 120 nm.

[0090] Example 2 A latex composition 2 for dip molding was obtained in the same manner as in Example 1, except that A1-2 was used instead of A1-1 as the surfactant (A). The weight average particle diameter of the polymer (B) in the latex composition 2 for dip molding is shown in Table 1. The surfactant A1-2 used above is an anionic surfactant (A1) containing 82.7% by mass of hydroxyhexadecylsulfonic acid as the component (a1), 15.8% by mass of hexadecenylsulfonic acid as the component (a2), and 1.5% by mass of hexadecene as the component (a3).

[0091] Example 3: Except for using 1.5 parts by mass of A1-1 as the surfactant (A) and 1.5 parts by mass of sodium dodecylbenzenesulfonate (Neopelex G-15, manufactured by Kao Corporation) as another surfactant, a dip-molding latex composition 3 was obtained in the same manner as in Example 1. The weight-average particle diameter of the polymer (B) in dip-molding latex composition 3 is shown in Table 1.

[0092] Example 4 A dip-molding latex composition 4 was obtained in the same manner as in Example 1, except that 3.0 parts by mass of DOWFAX 8390 (manufactured by Dow Corporation) was used as the surfactant (A). The weight-average particle diameter of polymer (B) in dip-molding latex composition 4 is shown in Table 1. DOWFAX 8390 used above is a 35% by mass aqueous solution of an anionic surfactant (A2), which is sodium alkyldiphenyl ether disulfonate having a linear alkyl group with 16 carbon atoms, each phenyl group substituted with one sodium sulfonate group, and the above parts by mass are the parts by mass of the active ingredient.

[0093] Example 5 A latex composition for dip molding 5 was obtained in the same manner as in Example 1, except that 59.0 parts by mass of 1,3-butadiene, 35.0 parts by mass of acrylonitrile, and 6.0 parts by mass of methacrylic acid were used. The weight average particle diameter of polymer (B) in latex composition for dip molding 5 is shown in Table 1.

[0094] Example 6 A latex composition for dip molding 6 was obtained in the same manner as in Example 5, except that 2.0 parts by mass of A1-1 and 1.5 parts by mass of A1-2 were used as the surfactants (A). The weight average particle diameter of the polymer (B) in the latex composition for dip molding 6 is shown in Table 1.

[0095] Example 7 A dip-molding latex composition 7 was obtained in the same manner as in Example 5, except that DOWFAX8390 (manufactured by Dow Corporation) was used as the surfactant (A) instead of A1-1. The weight-average particle size of the polymer (B) in dip-molding latex composition 7 is shown in Table 1. In the table, the parts by mass of DOWFAX8390 are the parts by mass of the active ingredient.

[0096] Example 8 A dip-molding latex composition 8 was obtained in the same manner as in Example 5, except that 1.5 parts by mass of A1-1 and 1.5 parts by mass of DOWFAX 8390 (manufactured by Dow Corporation) were used as the surfactant (A). The weight-average particle diameter of the polymer (B) in dip-molding latex composition 8 is shown in Table 1. In the table, the parts by mass of DOWFAX 8390 are the parts by mass of the active ingredient.

[0097] Example 9 A dip-molding latex composition 9 was obtained in the same manner as in Example 5, except that C18 disulfonated diphenyl oxide was used instead of A1-1 as the surfactant (A). The weight-average particle size of polymer (B) in dip-molding latex composition 9 is shown in Table 1. Note that the parts by mass of C18 disulfonated diphenyl oxide in the table refer to the parts by mass of the active ingredient. The C18 disulfonated diphenyl oxide used above is an anionic surfactant (A2) that is sodium alkyl diphenyl ether disulfonate having alkyl groups with an average carbon number of 18, each phenyl group substituted with one sodium sulfonate group, produced by the following production method.

[0098] 800 g of dichloromethane was placed in a 2 L four-neck flask and cooled to a liquid temperature of -5°C. At this temperature, 200 g of alkyl diphenyl ether having an average carbon chain number of 18 in the alkyl group and SO ３ 95 g of (liquid) was simultaneously added dropwise. After completion of the dropwise addition, cooling was stopped and the reaction system was stirred for 1 hour. Thereafter, the reaction system was distilled at 50°C, and then a 15% aqueous NaOH solution was added until the pH reached 10. Further, the system was heated at 100°C for 15 minutes to remove dichloromethane, thereby obtaining a 35% by mass aqueous solution of C18 disulfonated diphenyloxide.

[0099] Example 10: A dip-molding latex composition 10 was obtained in the same manner as in Example 1, except that 63.3 parts by mass of 1,3-butadiene, 35.0 parts by mass of acrylonitrile, and 1.7 parts by mass of methacrylic acid were used. The weight-average particle diameter of polymer (B) in dip-molding latex composition 10 is shown in Table 1.

[0100] Reference Example 1 A dip-molding latex composition 11 was obtained in the same manner as in Example 1, except that sodium dodecylbenzenesulfonate (Neopelex G-15, manufactured by Kao Corporation) was used instead of the surfactant (A). The weight-average particle diameter of the polymer (B) in the dip-molding latex composition 11 is shown in Table 1.

[0101] Reference Example 2 A dip-molding latex composition 12 was obtained in the same manner as in Example 5, except that sodium dodecylbenzenesulfonate (Neopelex G-15, manufactured by Kao Corporation) was used instead of the surfactant (A). The weight-average particle diameter of the polymer (B) in the dip-molding latex composition 12 is shown in Table 1.

[0102] Reference Example 3: A dip-molding latex composition 13 was obtained in the same manner as in Example 1, except that DOWFAX2A1 (manufactured by Dow Corporation) was used instead of surfactant (A). The weight-average particle diameter of polymer (B) in dip-molding latex composition 13 is shown in Table 1. DOWFAX2A1 used above is a 45% by mass aqueous solution (pH 10) of sodium alkyldiphenyl ether disulfonate having a branched alkyl group with 12 carbon atoms, each phenyl group substituted with one sodium sulfonate group, and the parts by mass above are the parts by mass of the active ingredient.

[0103] Reference Example 4 A dip-molding latex composition 14 was obtained in the same manner as in Example 5, except that DOWFAX2A1 (manufactured by Dow Corporation) was used instead of the surfactant (A). The weight-average particle size of polymer (B) in dip-molding latex composition 14 is shown in Table 1. In the table, the parts by mass of DOWFAX2A1 refer to the parts by mass of the active ingredient.

[0104]

[0105] [Production of latex blend composition for dip molding] Example 11 The latex composition for dip molding 1 produced in Example 1 (100.0 parts by mass of polymer (B)) was diluted with a 3% aqueous potassium hydroxide solution (1.2 parts by mass of potassium hydroxide) and stirred thoroughly, and then 0.5 parts by mass of A1-1 was added as a surfactant (A) with stirring to stabilize the reaction system. Thereafter, a sulfur dispersion (manufactured by Aquapersions) (1.1 parts by mass as sulfur), a zinc dibutyldithiocarbamate dispersion (manufactured by Aquapersions) (0.7 parts by mass as zinc dibutyldithiocarbamate) as a vulcanization accelerator, a zinc oxide dispersion (manufactured by Aquapersions) (1.1 parts by mass as zinc oxide), a titanium oxide dispersion (manufactured by Aquapersions) (1.5 parts by mass as titanium oxide), and 0.3 parts by mass of Bostex 362 (manufactured by AKRON DISPERSIONS) as an antioxidant were successively added under stirring to the mixture of dip molding latex composition 1 and surfactant (A). The mixture was then aged under stirring at room temperature for 1 day to produce dip molding latex blend composition 1. The resulting dip molding latex blend composition 1 was evaluated by the method described below.

[0106] <Evaluation of latex-blended compositions for dip molding> [Surface tension of latex-blended compositions for dip molding] The surface tension of a portion of latex-blended composition 1 for dip molding was measured by the ring method using a high-performance surface tensiometer (DY-500, manufactured by Kyowa Interface Science Co., Ltd.) at room temperature of 25° C. The average value of three measurements using a platinum ring is shown in Table 2.

[0107] [Amount of Aggregates in Dip-molding Latex Composition] The entire amount of dip-molding latex composition 1 was filtered through a 200-mesh wire screen, and the residue on the screen was taken as aggregates generated during production. The amount of aggregates was calculated as a percentage (mass%) of the mass of polymer (B) contained in the dip-molding latex composition, and the results are shown in Table 2. A small amount of aggregates is an indicator of the effectiveness of the stabilizer.

[0108] Example 12 A latex-blended composition 2 for dip molding was obtained in the same manner as in Example 11, except that sodium dodecylbenzenesulfonate (Neopelex G-15, manufactured by Kao Corporation) was used instead of the surfactant (A). The surface tension of the latex-blended composition 2 for dip molding and the amount of aggregates in the latex-blended composition 2 for dip molding are shown in Table 2.

[0109] Example 13: Except for using dip molding latex composition 2 instead of dip molding latex composition 1 and using A1-2 instead of A1-1 as surfactant (A), the same procedure as in Example 11 was carried out to obtain a dip molding latex-blended composition 3. The surface tension of dip molding latex-blended composition 3 and the amount of aggregates in dip molding latex-blended composition 3 are shown in Table 2.

[0110] Example 14 A latex-blended composition for dip molding 4 was obtained in the same manner as in Example 11, except that the latex composition for dip molding 1 was replaced with the latex composition for dip molding 11. The surface tension of the latex-blended composition for dip molding 4 and the amount of aggregates in the latex-blended composition for dip molding 4 are shown in Table 2.

[0111] Example 15 A latex-blended composition for dip molding 5 was obtained in the same manner as in Example 12, except that the latex composition for dip molding 3 was used instead of the latex composition for dip molding 1. The surface tension of the latex-blended composition for dip molding 5 and the amount of aggregates in the latex-blended composition for dip molding 5 are shown in Table 2.

[0112] Example 16: A latex-blended composition for dip molding 6 was obtained in the same manner as in Example 11, except that latex composition for dip molding 4 was used instead of latex composition for dip molding 1 and DOWFAX8390 (manufactured by Dow Corporation) was used instead of A1-1 as the surfactant (A). The surface tension of latex-blended composition for dip molding 6 and the amount of aggregates in latex-blended composition for dip molding 6 are shown in Table 2. In the table, the parts by mass of DOWFAX8390 refer to the parts by mass of the active ingredient.

[0113] Example 17: A latex-blended composition for dip molding 7 was obtained in the same manner as in Example 11, except that dip-blending latex composition 10 was used instead of dip-blending latex composition 1, and 0.5 parts by mass of A1-1 was used as the surfactant (A) and 0.5 parts by mass of sodium dodecylbenzenesulfonate (Neopelex G-15, manufactured by Kao Corporation) was used as another surfactant. The surface tension of dip-blending composition 7 and the amount of aggregates in dip-blending composition 7 are shown in Table 2.

[0114] Comparative Example 1 A latex-blended composition for dip molding 21 was obtained in the same manner as in Example 11, except that the latex composition for dip molding 11 was used instead of the latex composition for dip molding 1. The surface tension of the latex-blended composition for dip molding 21 and the amount of aggregates in the latex-blended composition for dip molding 21 are shown in Table 2.

[0115] Comparative Example 2 A latex-blended composition for dip molding 22 was obtained in the same manner as in Example 11, except that dip-blending latex composition 13 was used instead of dip-blending latex composition 1 and DOWFAX 2A1 (manufactured by Dow Corporation) was used instead of surfactant (A). The surface tension of dip-blending latex composition 22 and the amount of aggregates in dip-blending latex composition 22 are shown in Table 2. In the table, the parts by mass of DOWFAX 2A1 refer to the parts by mass of the active ingredient.

[0116]

[0117] The amount of aggregates in the dip-molding latex blended composition 6 of Example 16, which used an anionic surfactant (A2) as the surfactant (A), was smaller than the amount of aggregates in the dip-molding latex blended compositions 1 to 5 of Examples 11 to 15, which used an anionic surfactant (A1) as the surfactant (A), indicating that the anionic surfactant (A2) further stabilizes the dip-molding latex blended composition. The dip-molding latex blended composition 7 produced in Example 17 had a larger amount of aggregates than the dip-molding latex blended compositions 21 and 22 of Comparative Examples 1 and 2, but this did not pose a problem in the processability in producing dip-molded products, as described below.

[0118] [Preparation of Dip-Molded Product] Example 18: A ceramic dip-molded glove mold (manufactured by Shinko Co., Ltd.) was washed and heated. The mold was then immersed in a coagulant solution consisting of a mixed aqueous solution containing 14% by weight of calcium nitrate, 1.5% by weight of calcium stearate, and 0.05% by weight of a wetting agent (TERIC 320 manufactured by HUNTSMAN). The coagulant was then adhered to the surface of the mold by drying at 70°C for 3 minutes. The glove mold with the coagulant adhered thereto was then immersed in dip-molding latex blend composition 1 for 15 seconds or less, and the removed glove mold was heated at 80°C for 1 minute to produce a dip-molded layer on the mold, in which the dip-molded latex blend composition had gelled. The glove mold with the layer laminated thereon was then immersed in warm water at 60°C to 70°C for 3 minutes for leaching treatment. The mold was then heated in an oven at 70°C for 5 minutes, and further heated to 130°C for 20 minutes. After the heat treatment, the glove mold was cooled until its surface temperature reached 40°C. The glove mold on which the dip-molded layer was laminated was then immersed for 40 seconds in a chlorinated bath containing sodium hypochlorite and hydrochloric acid, the active chlorine concentration of which was adjusted to 900 ppm to 1000 ppm. The glove mold on which the dip-molded layer was laminated was then washed with water, washed with a 0.4% aqueous sodium sulfate solution, and washed again with water, and then dried at 100°C for 5 minutes. After the glove mold was sufficiently cooled at room temperature, the dip-molded layer was removed from the glove mold, and a glove was produced as a dip-molded product. The glove thus prepared was conditioned for 24 hours at 25°C and 55% RH, and then evaluated for the following properties.

[0119] <Evaluation of dip molding processability> [Measurement of number of pinholes] Air was blown into the sleeve of 10 pairs of gloves manufactured by the manufacturing method described in Example 18 to inflate them, and the number of pinholes was counted. The total number of pinholes found in the 10 gloves is shown in Table 3.

[0120] [Evaluation of Dripping] Ten pairs of gloves manufactured by the manufacturing method described in Example 18 were inflated by blowing air into the sleeves, and the presence or absence of dripping was visually confirmed. In Table 3, if dripping was confirmed in two or less of the ten gloves, the evaluation of the item "Dripping" was indicated as "No", and if dripping was confirmed in three or more gloves, the evaluation of the item "Dripping" was indicated as "Yes".

[0121] [Evaluation of film thickness] The film thickness of 10 gloves manufactured by the manufacturing method described in Example 18 was measured using a digital film thickness meter (Mitutoyo Corporation: Thickness gauge Code No. 547-401A) in accordance with ASTM-D412. Table 3 shows the average film thickness of 10 gloves.

[0122] [Evaluation of thickness unevenness] Ten gloves manufactured by the manufacturing method described in Example 18 were inflated by blowing air, and thickness unevenness was visually confirmed. In Table 3, when thickness unevenness was confirmed in two or less of the ten gloves, the evaluation of the item "thickness unevenness" was indicated as "absent", and when thickness unevenness was confirmed in three or more gloves, the evaluation of the item "thickness unevenness" was indicated as "present".

[0123] <Evaluation of dip-molded products> [Evaluation of presence or absence of surface bleeding] Ten gloves manufactured by the manufacturing method described in Example 18 were observed for the presence or absence of surface bleeding. The observation was carried out before and after the following aging treatment. In Table 3, if bleeding was confirmed in two or less of the ten gloves, the evaluation of the item "surface bleeding" was indicated as "absent", and if bleeding was confirmed in three or more gloves, the evaluation of the item "surface bleeding" was indicated as "present".

[0124] [Aging Treatment] The aging treatment of the gloves was carried out by adopting the method of heat treatment at 100°C ± 2°C for 22 hours ± 0.3 hours as described in ASTM D6319-19.

[0125] [Measurement of Tensile Strength, Modulus, and Elongation] Measurement of the tensile strength, modulus, and elongation of gloves was carried out according to the method described in ASTM D412. Test specimens were prepared by punching out gloves using a Die C manufactured by Dumbbell. Test specimens were measured using an AllroundLine universal testing machine Z-100 manufactured by Zwick Roell at a test speed of 500 mm / min, a chuck distance of 75 mm, and a gauge length of 25 mm. The tensile strength, modulus, and elongation obtained in this manner are shown in Table 3 as evaluation results before aging treatment. The modulus was calculated as the stress at 300% elongation of the test specimen and is shown in Table 3. The gloves that had been subjected to the above aging treatment were also evaluated in the same manner, and the evaluation results after aging treatment are shown in Table 3.

[0126] Examples 19 to 24 and Comparative Examples 3 and 4 Gloves were obtained as dip-molded products in the same manner as in Example 18, except that the latex-blended compositions for dip-molding shown in Table 3 were used instead of the dip-molding latex composition 1. Evaluation of dip-molding processability of the dip-molding latex-blended compositions and evaluation of the dip-molded products of gloves were carried out in the same manner as in Example 18, and the results are shown in Table 3.

[0127]

[0128] From Tables 2 and 3, it can be seen that the surface tensions of dip-molding latex blended compositions 1 to 7 containing surfactant (A) are lower than those of dip-molding latex blended compositions 21 and 22 not containing surfactant (A). It can be seen that the gloves of Examples 18 to 24 produced from dip-molding latex blended compositions 1 to 7 have fewer pinholes and are superior in processability compared to the gloves of Comparative Examples 3 and 4 produced from dip-molding latex blended compositions 21 and 22. Furthermore, it can be seen that the gloves of Examples 18 to 24 have lower modulus and higher elongation compared to the gloves of Comparative Examples 3 and 4, indicating that they exhibit more flexible physical properties. These effects of the gloves of Examples 18 to 24 are maintained superior to those of the gloves of Comparative Examples 3 and 4 even after aging treatment. Furthermore, it can be seen that the gloves of Examples 18 to 23 have the same tensile strength as the glove of Comparative Example 2. On the other hand, the glove of Example 24 had relatively low tensile strength, probably because the content of the structural unit (B2) derived from ethylenically unsaturated carboxylic acid monomer in the polymer (B) was 1.7 mass%.

[0129] Example 25: A latex-blended composition for dip molding 8 was obtained in the same manner as in Example 11, except that latex composition for dip molding 5 was used instead of latex composition for dip molding 1 and 1.3 parts by mass of 3% aqueous potassium hydroxide solution was used. The surface tension of latex-blended composition for dip molding 8 and the amount of aggregates in latex-blended composition for dip molding 8 are shown in Table 4.

[0130] Example 26: A latex-blended composition for dip molding 9 was obtained in the same manner as in Example 25, except that the surfactant (A) was not used, and 1.0 part by mass of an epoxy crosslinking agent (Denacol EX-321, manufactured by Nagase ChemteX Corporation) and 1.2 parts by mass of zinc oxide were used instead of the sulfur dispersion and the vulcanization accelerator. The surface tension of the latex-blended composition for dip molding 9 and the amount of aggregates in the latex-blended composition for dip molding 9 are shown in Table 4.

[0131] Example 27 A latex-blended composition for dip molding 10 was obtained in the same manner as in Example 26, except that the latex composition for dip molding 6 was used instead of the latex composition for dip molding 5. The surface tension of the latex-blended composition for dip molding 10 and the amount of aggregates in the latex-blended composition for dip molding 10 are shown in Table 4.

[0132] Example 28: A dip-molding latex-blended composition 11 was obtained in the same manner as in Example 25, except that a wax emulsion (Aquawax 48 manufactured by GOVI Chemicals) (2.0 parts by mass as the amount of wax) was used. The surface tension of dip-molding latex-blended composition 11 and the amount of aggregates in dip-molding latex-blended composition 11 are shown in Table 4.

[0133] Example 29: A latex-blended composition for dip molding 12 was obtained in the same manner as in Example 25, except that latex composition for dip molding 7 was used instead of latex composition for dip molding 5, and DOWFAX8390 (manufactured by Dow Corporation) was used instead of A1-1 as the surfactant (A). The surface tension of latex-blended composition for dip molding 12 and the amount of aggregates in latex-blended composition for dip molding 12 are shown in Table 4. In the table, the parts by mass of DOWFAX8390 refer to the parts by mass of the active ingredient.

[0134] Example 30: Dip-molding latex composition 7 was obtained in the same manner as in Example 25, except that dip-molding latex composition 8 was used instead of dip-molding latex composition 5, and 0.25 parts by mass of A1-1 and 0.25 parts by mass of DOWFAX 8390 (manufactured by Dow Corporation) were used as surfactants (A). The surface tension of dip-molding latex composition 7 and the amount of aggregates in dip-molding latex composition 13 are shown in Table 2. In the table, the parts by mass of DOWFAX 8390 refer to the parts by mass of the active ingredient.

[0135] Example 31 A latex-blended composition for dip molding 14 was obtained in the same manner as in Example 25, except that dip-blending latex composition 9 was used instead of dip-blending latex composition 5, and the above-mentioned C18 disulfonated diphenyl oxide was used instead of A1-1 as the surfactant (A). The surface tension of dip-blending latex composition 14 and the amount of aggregates in dip-blending latex composition 14 are shown in Table 4. In the table, the parts by mass of C18 disulfonated diphenyl oxide refer to the parts by mass of the active ingredient.

[0136] Comparative Example 5 The procedure of Example 25 was repeated except that dip molding latex composition 12 was used instead of dip molding latex composition 5, and sodium dodecylbenzenesulfonate (Neopelex G-15, manufactured by Kao Corporation) was used instead of surfactant (A), to obtain dip molding latex blended composition 23. The surface tension of dip molding latex blended composition 23 and the amount of aggregates in dip molding latex blended composition 23 are shown in Table 4.

[0137] Comparative Example 6: A dip-molding latex-blended composition 24 was obtained in the same manner as in Comparative Example 5, except that a wax emulsion (Aquawax 48 manufactured by GOVI Chemicals) (2.0 parts by mass as the amount of wax) was used. The surface tension of dip-molding latex-blended composition 24 and the amount of aggregates in dip-molding latex-blended composition 24 are shown in Table 4.

[0138] Comparative Example 7 Dip-molding latex composition 25 was obtained in the same manner as in Example 25, except that dip-molding latex composition 14 was used instead of dip-molding latex composition 8 and DOWFAX 2A1 (manufactured by Dow Corporation) was used instead of surfactant (A). The surface tension of dip-molding latex composition 25 and the amount of aggregates in dip-molding latex composition 25 are shown in Table 4. In the table, the parts by mass of DOWFAX 2A1 refer to the parts by mass of the active ingredient.

[0139]

[0140] The amounts of aggregates in the dip-molding latex blend compositions 12 to 14 of Examples 29 to 31, which used the anionic surfactant (A2) as the surfactant (A), were equal to or smaller than the amounts of aggregates in the dip-molding latex blend compositions 8 and 11 of Examples 25 and 28, which used the anionic surfactant (A1) as the surfactant (A). This shows that the anionic surfactant (A2) further stabilizes the dip-molding latex blend composition.

[0141] Examples 32 to 38 and Comparative Examples 8 to 10 Gloves were obtained as dip molded products in the same manner as in Example 18, except that the latex blended compositions for dip molding shown in Table 5 were used instead of the latex blended composition for dip molding 1. Evaluation of dip molding processability of the latex blended compositions for dip molding and evaluation of the gloves as dip molded products were carried out in the same manner as in Example 18, and the results are shown in Table 5.

[0142]

[0143] As shown in Tables 4 and 5, the surface tensions of dip molding latex blended compositions 8 to 14 containing surfactant (A) are lower than those of dip molding latex blended compositions 23 to 26 not containing surfactant (A). The gloves of Examples 32 to 38 produced using dip molding latex blended compositions 8 to 14 had fewer pinholes and less unevenness in film thickness, except for the glove of Example 35, compared to the gloves of Comparative Examples 8 to 10 produced using dip molding latex blended compositions 23 to 26. This confirms their superior processability. Furthermore, the gloves of Examples 32 to 38 had lower modulus and higher elongation than the gloves of Comparative Examples 8 to 10, confirming that they exhibited more flexible physical properties. These effects of the gloves of Examples 32 to 38 were maintained superior to those of the gloves of Comparative Examples 8 to 10 even after aging treatment. Furthermore, it was confirmed that the gloves of Examples 32 to 38 had the same tensile strength as the gloves of Comparative Examples 8 to 10.

[0144] A common method for improving the stiffness of nitrile rubber gloves is to incorporate a wax emulsion or the like into a latex-blended composition to enhance the flexibility of the gloves through the plasticizing effect of the wax. However, as shown in Comparative Example 9, the wax bleeds even immediately after production, resulting in problems such as a decrease in the flexibility of the gloves and contamination during use. On the other hand, as shown in Example 35, the gloves containing surfactant (A) showed no wax bleeding immediately after production, and although wax bleeding was observed after aging, they maintained a low modulus and a high elongation. Furthermore, the gloves of Examples 18 to 24, 32 to 34, and 36 to 38, which do not contain wax, had lower modulus and higher elongation than the gloves of Example 35 and Comparative Example 9, which contain wax. This indicates that surfactant (A) exhibits a more excellent plasticizing effect than wax.

[0145] It has been shown that the dip-molded latex composition of the present invention can produce dip-molded products with significantly improved flexibility while maintaining physical strength. Also, it has been shown that the produced gloves can maintain the modulus and elongation for a long period of time, unchanged from those immediately after production. Conventionally, surfactants have mostly been used for the purpose of maintaining the stability of polymer emulsions, and to the best of the present inventors' knowledge, there has been no example of using surfactants to impart functionality to the surfactant remaining in the dip-molded layer after dip-molding.

[0146] The latex blended composition for dip molding containing the latex composition for dip molding of the present invention can provide a dip-molded product excellent in flexibility and tensile strength, and is therefore useful in the fields of medical supplies such as nipples for baby bottles, droppers, conduits, water pillows, condoms, etc.; toys and sports equipment such as balloons, dolls, balls, etc.; industrial supplies such as pressure molding bags, gas storage bags, etc.; and medical, household, agricultural, fishery, and industrial gloves, and is particularly useful for medical gloves, and more particularly for surgical gloves.

Claims

1. A dip molding latex composition comprising: a surfactant (A) containing at least one of: component (a1) - hydroxyalkanesulfonate having an average carbon number of 16 to 18; component (a2) - internal olefin sulfonate having an average carbon number of 16 to 18; and component (a3) ​​- an anionic surfactant (A1) containing an internal olefin having an average carbon number of 16 to 18; and an anionic surfactant (A2) consisting of a linear or branched alkyl diphenyl ether disulfonate having an average carbon number of 16 to 18 in the alkyl group; and a polymer (B) containing structural units (B1) derived from a conjugated diene monomer, structural units (B2) derived from an ethylenically unsaturated carboxylic acid monomer, and structural units (B3) derived from an ethylenically unsaturated nitrile monomer, wherein the content of the surfactant (A) per 100 parts by mass of the polymer (B) is 0.05 parts by mass or more and 10 parts by mass or less.

2. The dip-molding latex composition according to claim 1, wherein the mass ratio of the component (a1) to the component (a2) in the surfactant (A1) [component (a1) / component (a2)] is 0.25 or more and 20 or less.

3. The dip molding latex composition according to claim 1 or 2, wherein the content of the structural unit (B1) derived from the conjugated diene monomer is 50% by mass or more and 78% by mass or less, the content of the structural unit (B2) derived from the ethylenically unsaturated carboxylic acid monomer is 2% by mass or more and 10% by mass or less, and the content of the structural unit (B3) derived from the ethylenically unsaturated nitrile monomer is 20% by mass or more and 40% by mass or less, based on the total content of the structural unit (B1) derived from the conjugated diene monomer, the structural unit (B2) derived from the ethylenically unsaturated carboxylic acid monomer, and the structural unit (B3) derived from the ethylenically unsaturated nitrile monomer in the polymer (B).

4. The dip-molding latex composition according to any one of claims 1 to 3, further comprising an alkylbenzenesulfonic acid or a salt thereof, the alkyl group of which has an average carbon number of 8 to 18.

5. The dip molding latex composition according to claim 4, wherein the content of (A) is 0.05% by mass or more and 10% by mass or less, the content of (B) is 80% by mass or more and 99.9% by mass or less, and the content of the alkylbenzenesulfonic acid or its salt is 0.05% by mass or more and 10% by mass or less, based on the total content of the surfactant (A), the polymer (B), and the alkylbenzenesulfonic acid or its salt.

6. The dip-molding latex composition according to any one of claims 1 to 5, which is obtained by mixing the surfactant (A) and the polymer (B).

7. A latex compounded composition for dip molding, comprising the latex composition for dip molding according to any one of claims 1 to 6, and at least one selected from the group consisting of metal oxides, sulfur-based crosslinking agents, and vulcanization accelerators.

8. The dip molding latex blend composition according to claim 7, which contains 35 parts by mass or less of a metal oxide, 2 parts by mass or less of a sulfur-based crosslinking agent, and 2 parts by mass or less of a vulcanization accelerator, per 100 parts by mass of the polymer (B).

9. A dip-molded product of the dip-molding latex compounding composition according to claim 7 or 8.

10. The dip-molded product according to claim 9, which is a glove.

11. A method for producing a dip-molded product, comprising molding the dip-molding latex blend composition according to claim 7 or 8.

12. The method for producing a dip-molded product according to claim 11, wherein the dip-molded product is a glove.

13. A method for producing a dip molding latex composition, comprising a step of emulsion polymerizing monomers containing a conjugated diene monomer (b1), an ethylenically unsaturated carboxylic acid monomer (b2), and an ethylenically unsaturated nitrile monomer (b3) in the presence of a surfactant (A) containing at least one of an anionic surfactant (A1) containing: component (a1): hydroxyalkanesulfonate having an average carbon number of 16 or more and 18 or less; component (a2): internal olefin sulfonate having an average carbon number of 16 or more and 18 or less; and component (a3): internal olefin having an average carbon number of 16 or more and 18 or less; and an anionic surfactant (A2) consisting of a linear or branched alkyl diphenyl ether disulfonate having an average carbon number of 16 or more and 18 or less in the alkyl group.

14. A method for producing a latex composition for dip molding, comprising a step of emulsion polymerizing monomers containing a conjugated diene monomer (b1), an ethylenically unsaturated carboxylic acid monomer (b2), and an ethylenically unsaturated nitrile monomer (b3) in the presence of a surfactant (A) containing at least one of an anionic surfactant (A1) comprising: component (a1): a hydroxyalkanesulfonate having an average carbon number of 16 to 18; component (a2): an internal olefin sulfonate having an average carbon number of 16 to 18; and component (a3): an internal olefin having an average carbon number of 16 to 18; and an anionic surfactant (A2) consisting of a linear or branched alkyldiphenyl ether disulfonate having an average carbon number of 16 to 18 in the alkyl group; and alkylbenzenesulfonic acid or a salt thereof having an average carbon number of 8 to 18 in the alkyl group.

15. Use of a surfactant (A) comprising at least one of an anionic surfactant (A1) containing: component (a1): hydroxyalkanesulfonate having an average carbon number of 16 to 18; component (a2): internal olefin sulfonate having an average carbon number of 16 to 18; and component (a3): internal olefin having an average carbon number of 16 to 18; and an anionic surfactant (A2) consisting of a linear or branched alkyl diphenyl ether disulfonate having an average carbon number of 16 to 18 in the alkyl group, for emulsion polymerization of monomers including a conjugated diene monomer (b1), an ethylenically unsaturated carboxylic acid monomer (b2), and an ethylenically unsaturated nitrile monomer (b3).

16. An emulsion polymerization agent for monomers containing a conjugated diene monomer (b1), an ethylenically unsaturated carboxylic acid monomer (b2), and an ethylenically unsaturated nitrile monomer (b3), containing a surfactant (A) containing at least one of the following: an anionic surfactant (A1) containing: component (a1): hydroxyalkanesulfonate having an average carbon number of 16 or more and 18 or less; component (a2): internal olefin sulfonate having an average carbon number of 16 or more and 18 or less; and component (a3): internal olefin having an average carbon number of 16 or more and 18 or less; and an anionic surfactant (A2) consisting of a linear or branched alkyl diphenyl ether disulfonate having an average carbon number of 16 or more and 18 or less in the alkyl group.

17. Use of a surfactant (A) comprising at least one of an anionic surfactant (A1) containing: component (a1): hydroxyalkanesulfonate having an average carbon number of 16 to 18; component (a2): internal olefin sulfonate having an average carbon number of 16 to 18; and component (a3): internal olefin having an average carbon number of 16 to 18; and an anionic surfactant (A2) consisting of a linear or branched alkyl diphenyl ether disulfonate having an average carbon number of 16 to 18 in the alkyl group, for stabilizing a dip molding latex composition containing a polymer (B) containing a structural unit (B1) derived from a conjugated diene monomer, a structural unit (B2) derived from an ethylenically unsaturated carboxylic acid monomer, and a structural unit (B3) derived from an ethylenically unsaturated nitrile monomer.

18. A stabilizer for a dip molding latex composition comprising a surfactant (A) containing at least one of an anionic surfactant (A1) containing: component (a1): hydroxyalkanesulfonate having an average carbon number of 16 to 18; component (a2): internal olefin sulfonate having an average carbon number of 16 to 18; and component (a3): internal olefin having an average carbon number of 16 to 18; and an anionic surfactant (A2) consisting of a linear or branched alkyl diphenyl ether disulfonate having an average carbon number of 16 to 18 in the alkyl group, and comprising a polymer (B) containing a structural unit (B1) derived from a conjugated diene monomer, a structural unit (B2) derived from an ethylenically unsaturated carboxylic acid monomer, and a structural unit (B3) derived from an ethylenically unsaturated nitrile monomer.

19. A method for producing a latex blend composition for dip molding, comprising the step of mixing a latex composition containing a polymer (B) containing structural units (B1) derived from a conjugated diene monomer, structural units (B2) derived from an ethylenically unsaturated carboxylic acid monomer, and structural units (B3) derived from an ethylenically unsaturated nitrile monomer, with a surfactant (A) containing at least one of: component (a1): hydroxyalkanesulfonate having an average carbon number of 16 to 18; component (a2): internal olefin sulfonate having an average carbon number of 16 to 18; and component (a3): an anionic surfactant (A1) containing an internal olefin having an average carbon number of 16 to 18; and an anionic surfactant (A2) consisting of a linear or branched alkyl diphenyl ether disulfonate having an average carbon number of 16 to 18 in the alkyl group.

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