Latex composition for dip molding and dip-molded article

Abstract

Provided is a latex composition which is for dip molding and from which it is possible to provide a dip-molded article that has excellent drug solution permeation resistance and that has an excellent balance between flexibility and wet-grip ability. Provided is a latex composition for dip molding, containing an anionic surfactant and a latex which is a polymer. The anionic surfactant contains: a compound (a) having an aromatic ring and one anionic group; and a compound (b1) having a benzene ring and having at least two anionic groups or a compound (b2) not having an aromatic ring but having one anionic group.

Description

Latex composition for dip molding and dip-molded article

[0001] The present invention relates to a latex composition for dip molding, and more particularly to a latex composition for dip molding which has excellent resistance to chemical permeation and can give a dip-molded product having a well-balanced excellent wet grip property and flexibility.

[0002] Conventionally, protective gloves that have improved solvent resistance, gripping properties, abrasion resistance, etc. by covering fiber gloves with rubber, resin, etc. have been used for various purposes such as manufacturing work in factories, light work, construction work, agricultural work, etc.

[0003] Such protective gloves are required to have excellent mechanical strength such as abrasion resistance and durability, as well as excellent flexibility. Furthermore, since protective gloves are often used in a wet state with chemicals such as oil, they are also required to have excellent wet grip properties when chemicals are attached and excellent resistance to chemical permeation.

[0004] For example, Patent Document 1 describes a copolymer latex for dip molding obtained by emulsion polymerization of monomers consisting of 50 to 80% by weight of 1,3-butadiene, 15 to 50% by weight of acrylonitrile, 0 to 10% by weight of an ethylenically unsaturated carboxylic acid monomer, and 0 to 35% by weight of an ethylenically unsaturated monomer copolymerizable therewith, wherein the difference in surface tension between pH=9 and pH=3 at a solids content of 30% by weight of the copolymer latex is 6 mN / m or more, and the methyl ethyl ketone (MEK) insoluble content is 50% or more.

[0005] Japanese Patent Application Laid-Open No. 2005-336273

[0006] The technique of Patent Document 1 does not provide sufficient wet grip properties of the obtained dip-molded article. There has been a demand for a latex composition for dip-molding which has excellent resistance to chemical liquid permeation and can provide a dip-molded article having a good balance of wet grip properties and flexibility.

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a latex composition for dip-molding which can give a dip-molded article having excellent resistance to chemical permeation and a well-balanced wet grip property and flexibility. Another object of the present invention is to provide a dip-molded article having excellent resistance to chemical permeation and a well-balanced wet grip property and flexibility.

[0008] As a result of intensive research into solving the above problems, the present inventors have found that the above problems can be solved by using a combination of specific anionic surfactants, and have thus completed the present invention.

[0009] That is, according to the present invention, there is provided a latex composition for dip molding containing a polymer latex and an anionic surfactant, wherein the anionic surfactant contains a compound (a) having one anionic group and an aromatic ring, and a compound (b1) having two or more anionic groups and a benzene ring, or a compound (b2) having one anionic group and no aromatic ring.

[0010] In the dip-forming latex composition of the present invention, the compound (b1) is preferably a compound having two anionic groups and a benzene ring, and more preferably an alkyl diphenyl ether disulfonate. In the dip-forming latex composition of the present invention, the compound (b2) is preferably an alkyl sulfate ester salt. In the dip-forming latex composition of the present invention, the compound (a) is preferably a sulfonate or a sulfate ester salt, and at least one of the compound (b1) and the compound (b2) is preferably a sulfonate or a sulfate ester salt. In the dip-forming latex composition of the present invention, the content of the compound (a) is preferably 0.1 to 5.0 parts by weight based on 100 parts by weight of the polymer components contained in the dip-forming latex composition. In the dip-forming latex composition of the present invention, the total content of the compound (b1) and the compound (b2) is preferably 0.1 to 10.0 parts by weight based on 100 parts by weight of the polymer components contained in the dip-forming latex composition. In the dip-molding latex composition of the present invention, the weight ratio of the content of compound (a) to the total content of compound (b1) and compound (b2) [weight of compound (a) : total weight of compound (b1) and compound (b2)] is preferably 5:95 to 95:5. In the dip-molding latex composition of the present invention, the compound (a) is preferably an alkylbenzenesulfonate. In the dip-molding latex composition of the present invention, the polymer latex is preferably a nitrile group-containing conjugated diene polymer latex.

[0011] According to the present invention, there is also provided a dip-molded article obtained by using the above-mentioned latex composition for dip molding. The dip-molded article of the present invention is preferably a glove.

[0012] According to the present invention, there is provided a latex composition for dip-molding which can give a dip-molded article having excellent resistance to chemical permeation and a well-balanced wet grip property and flexibility. Furthermore, according to the present invention, there is provided a dip-molded article having excellent resistance to chemical permeation and a well-balanced wet grip property and flexibility.

[0013] The dip-forming latex composition of the present invention is a dip-forming latex composition containing a polymer latex and an anionic surfactant, wherein the anionic surfactant contains a compound (a) having one anionic group and an aromatic ring, and a compound (b1) having two or more anionic groups and a benzene ring, or a compound (b2) having one anionic group and no aromatic ring.

[0014] <Polymer Latex> The dip-molding latex composition of the present invention contains a polymer latex.

[0015] The polymer constituting the polymer latex is not particularly limited, but examples include conjugated diene polymers such as nitrile rubber (NBR), natural rubber (NR), styrene-butadiene rubber (SBR), synthetic polyisoprene rubber (IR), polybutadiene rubber (BR), styrene-isoprene copolymer rubber, and styrene-isoprene-styrene copolymer rubber, polybutyl acrylate, and butyl rubber (IIR). Among these, from the viewpoint of more pronounced effects of the present invention, synthetic rubber is preferred, with nitrile rubber (NBR), styrene-butadiene rubber (SBR), synthetic polyisoprene rubber (IR), and polybutyl acrylate being more preferred, and conjugated diene polymers containing nitrile groups such as NBR (hereinafter referred to as "nitrile group-containing conjugated diene polymers") being even more preferred. Note that these conjugated diene polymers may also be conjugated diene polymers containing carboxyl groups (hereinafter referred to as "carboxyl group-containing conjugated diene polymers").

[0016] The nitrile group-containing conjugated diene polymer is not particularly limited, but for example, a polymer obtained by copolymerizing an α,β-ethylenically unsaturated nitrile monomer, a conjugated diene monomer, and, if necessary, other copolymerizable ethylenically unsaturated acid monomers can be used.

[0017] The α,β-ethylenically unsaturated nitrile monomer is not particularly limited, but an ethylenically unsaturated compound having a nitrile group and preferably having 3 to 18 carbon atoms can be used. Examples of such α,β-ethylenically unsaturated nitrile monomers include acrylonitrile, methacrylonitrile, and halogen-substituted acrylonitrile, and among these, acrylonitrile is particularly preferred. These α,β-ethylenically unsaturated nitrile monomers may be used alone or in combination of two or more.

[0018] The content of the α,β-ethylenically unsaturated nitrile monomer units in the nitrile group-containing conjugated diene polymer is preferably 10 to 45% by weight, more preferably 15 to 40% by weight, and even more preferably 20 to 40% by weight, based on the total monomer units, from the viewpoint of the flexibility and solvent resistance of the resulting dip-molded article.

[0019] As the conjugated diene monomer, conjugated diene monomers having 4 to 6 carbon atoms such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and chloroprene are preferred, 1,3-butadiene and isoprene are more preferred, and 1,3-butadiene is particularly preferred. These conjugated diene monomers may be used alone or in combination of two or more.

[0020] The content of the conjugated diene monomer units in the nitrile group-containing conjugated diene polymer is preferably 40 to 89.9% by weight, more preferably 50 to 84% by weight, even more preferably 52 to 78% by weight, and particularly preferably 55 to 75% by weight, based on the total monomer units, from the viewpoint of flexibility of the resulting dip-molded article.

[0021] The nitrile group-containing conjugated diene polymer may be a copolymer of a monomer forming an α,β-ethylenically unsaturated nitrile monomer unit and a monomer forming a conjugated diene monomer unit with another copolymerizable ethylenically unsaturated acid monomer.

[0022] The copolymerizable other ethylenically unsaturated acid monomer is not particularly limited, and examples thereof include vinyl aromatic monomers such as styrene, alkylstyrene, and vinylnaphthalene, carboxyl group-containing ethylenically unsaturated monomers, monocarboxylic acid ester group-containing ethylenically unsaturated monomers, dicarboxylic acid diester group-containing ethylenically unsaturated monomers, sulfonic acid group-containing ethylenically unsaturated monomers, and phosphoric acid group-containing ethylenically unsaturated monomers. Among these, carboxyl group-containing ethylenically unsaturated monomers are preferred because they enable the nitrile group-containing conjugated diene polymer to contain carboxyl groups, thereby enabling the resulting dip-molded article to have excellent mechanical properties. The polymer constituting the polymer latex may be, for example, a polymer consisting only of α,β-ethylenically unsaturated nitrile monomer units, conjugated diene monomer units in the nitrile group-containing conjugated diene polymer, and carboxyl group-containing ethylenically unsaturated monomers.

[0023] The carboxyl group-containing ethylenically unsaturated monomer is not particularly limited, and examples thereof include ethylenically unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, etc.; ethylenically unsaturated polycarboxylic acids and anhydrides thereof such as fumaric acid, maleic acid, itaconic acid, maleic anhydride, itaconic anhydride, etc.; and partially esterified products of ethylenically unsaturated polycarboxylic acids such as methyl maleate and methyl itaconate. When the nitrile group-containing conjugated diene polymer contains units of a carboxyl group-containing ethylenically unsaturated monomer, the content of the units of the carboxyl group-containing ethylenically unsaturated monomer is preferably 0.1 to 15% by weight, more preferably 1 to 10% by weight, and even more preferably 2 to 8% by weight, based on the total monomer units.

[0024] The monocarboxylic acid ester group-containing ethylenically unsaturated monomer is not particularly limited, but examples thereof include acrylic acid esters such as methyl acrylate, ethyl acrylate, and n-butyl acrylate; methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, and n-butyl methacrylate; and crotonate esters such as methyl crotonate. Of these, acrylic acid esters and methacrylic acid esters are preferred, and methyl acrylate and methyl methacrylate are more preferred.

[0025] The dicarboxylic acid diester group-containing ethylenically unsaturated monomer is not particularly limited, but examples thereof include maleic acid diesters such as dimethyl maleate; itaconic acid diesters such as methyl itaconate; and the like.

[0026] The sulfonic acid group-containing ethylenically unsaturated monomer is not particularly limited, but examples thereof include vinyl sulfonic acid, methyl vinyl sulfonic acid, styrene sulfonic acid, (meth)allyl sulfonic acid, (meth)acrylic acid-2-ethyl sulfonate, and 2-acrylamido-2-hydroxypropane sulfonic acid.

[0027] The phosphoric acid group-containing ethylenically unsaturated monomer is not particularly limited, but examples thereof include (meth)acrylic acid-3-chloro-2-propyl phosphate, (meth)acrylic acid-2-ethyl phosphate, and 3-allyloxy-2-hydroxypropane phosphate.

[0028] These other copolymerizable ethylenically unsaturated acid monomers can be used as alkali metal salts or ammonium salts, and may be used alone or in combination of two or more. Among the above-mentioned other copolymerizable ethylenically unsaturated acid monomers, carboxyl group-containing ethylenically unsaturated monomers are preferred, ethylenically unsaturated monocarboxylic acids are more preferred, acrylic acid and methacrylic acid are further preferred, and methacrylic acid is particularly preferred.

[0029] In the case where the nitrile group-containing conjugated diene polymer contains units of other copolymerizable ethylenically unsaturated acid monomers, the content of the units of the other copolymerizable ethylenically unsaturated acid monomers (when two or more kinds of ethylenically unsaturated acid monomers are used, the total content) is preferably 0.1 to 45% by weight, more preferably 1 to 40% by weight, and even more preferably 2 to 38% by weight, based on the total monomer units.

[0030] The polymer latex can be obtained, for example, by emulsion polymerization of a monomer mixture containing the above-mentioned monomers. During emulsion polymerization, polymerization auxiliary materials such as an emulsifier, a polymerization initiator, and a molecular weight modifier can be used.

[0031] The emulsifier used in emulsion polymerization is not particularly limited, but examples thereof include anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants, with anionic surfactants being preferred.

[0032] Specific examples of the anionic surfactant used in emulsion polymerization include the compound (a) having one anionic group and an aromatic ring, the compound (b1) having two or more anionic groups and a benzene ring, and the compound (b2) having one anionic group and no aromatic ring, which will be described later. By using these compounds as emulsifiers for emulsion polymerization, a polymer latex containing these compounds can be obtained.

[0033] The amount of the emulsifier used in emulsion polymerization is preferably 0.5 to 10 parts by weight, more preferably 1 to 8 parts by weight, based on 100 parts by weight of the total monomers used.

[0034] The polymerization initiator is not particularly limited, but a radical initiator is preferred. The radical initiator is not particularly limited, but examples thereof include inorganic peroxides such as sodium persulfate, potassium persulfate, ammonium persulfate, potassium perphosphate, and hydrogen peroxide; organic peroxides such as t-butyl peroxide, cumene hydroperoxide, p-menthane hydroperoxide, di-t-butyl peroxide, t-butylcumyl peroxide, acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, dibenzoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, and t-butylperoxyisobutyrate; and azo compounds such as azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, azobiscyclohexanecarbonitrile, and methyl azobisisobutyrate. Among these, inorganic peroxides or organic peroxides are preferred, inorganic peroxides are more preferred, and persulfates are particularly preferred. These polymerization initiators may be used alone or in combination of two or more. The amount of the polymerization initiator used is preferably 0.01 to 2 parts by weight, more preferably 0.05 to 1.5 parts by weight, based on 100 parts by weight of the total monomers used.

[0035] The molecular weight modifier is not particularly limited, but examples thereof include α-methylstyrene dimer; mercaptans such as t-dodecyl mercaptan, n-dodecyl mercaptan, and octyl mercaptan; halogenated hydrocarbons such as carbon tetrachloride, methylene chloride, and methylene bromide; and sulfur-containing compounds such as tetraethylthiuram disulfide, dipentamethylenethiuram disulfide, and diisopropylxanthogen disulfide. Among these, mercaptans are preferred, and t-dodecyl mercaptan is more preferred. These molecular weight modifiers may be used alone or in combination of two or more. The amount of molecular weight modifier used varies depending on the type, but is preferably 0.1 to 1.5 parts by weight, more preferably 0.2 to 1.0 part by weight, per 100 parts by weight of all monomers used.

[0036] The emulsion polymerization is usually carried out in water, and the amount of water used is preferably 80 to 500 parts by weight, more preferably 100 to 200 parts by weight, per 100 parts by weight of the total monomers used.

[0037] In emulsion polymerization, if necessary, other polymerization secondary materials may be used, such as a chelating agent, a dispersant, a pH adjuster, an oxygen scavenger, a particle size adjuster, etc., and the type and amount of these materials are not particularly limited.

[0038] Examples of methods for adding the monomers include adding the monomers to be used all at once to the reaction vessel, adding them continuously or intermittently as the polymerization progresses, and adding a portion of the monomers and reacting them to a specific conversion rate, followed by adding the remaining monomers continuously or intermittently to polymerize them. Any of these methods may be used. When the monomers are mixed and added continuously or intermittently, the composition of the mixture may be constant or may be varied. Furthermore, the various monomers to be used may be mixed in advance and then added to the reaction vessel, or each may be added separately to the reaction vessel.

[0039] The polymerization temperature during emulsion polymerization is not particularly limited, but is usually 0 to 95° C., and preferably 5 to 70° C. The polymerization time is not particularly limited, but is usually about 5 to 40 hours.

[0040] After the polymerization reaction is terminated, if desired, the unreacted monomer may be removed and the solid content concentration and pH may be adjusted.

[0041] From the viewpoint of making the effects of the present invention more pronounced, the glass transition temperature of the polymer constituting the polymer latex is preferably 10° C. or lower, more preferably −55° C. to 5° C., even more preferably −45° C. to 0° C., and particularly preferably −40° C. to −10° C. The method for adjusting the glass transition temperature of the polymer to the above range is not particularly limited, but examples thereof include a method in which the content ratio of each monomer unit constituting the polymer is adjusted to the above range.

[0042] The volume average particle diameter of the polymer particles constituting the polymer latex is preferably 30 to 1000 nm, more preferably 50 to 500 nm, and even more preferably 70 to 200 nm, from the viewpoint of making the effects of the present invention more pronounced. The volume average particle diameter of the polymer particles constituting the polymer latex can be measured, for example, using a light scattering diffraction particle measuring device.

[0043] The surface tension of the polymer latex at 25° C. is preferably 20 to 70 mN / m, more preferably 25 to 60 mN / m, and even more preferably 30 to 50 mN / m, from the viewpoint of making the effects of the present invention more pronounced.

[0044] The difference between the surface tension of the polymer latex at 25°C and the surface tension of the anionic surfactant at 25°C is preferably -10 to 15 mN / m, more preferably -5 to 10 mN / m, and even more preferably 0 to 8 mN / m, from the viewpoint of making the effects of the present invention more pronounced.

[0045] The surface tension of the polymer latex at 25°C and the difference between the surface tension of the polymer latex at 25°C and the surface tension of the anionic surfactant at 25°C are specifically measured by the method described in the examples.

[0046] <Anionic Surfactant> The dip-molding latex composition of the present invention contains an anionic surfactant in addition to the polymer latex.

[0047] The anionic surfactant used in the present invention contains a compound (a) having one anionic group and an aromatic ring, and a compound (b1) having two or more anionic groups and a benzene ring and / or a compound (b2) having one anionic group and no aromatic ring.

[0048] The compound (a) having one anionic group and an aromatic ring (hereinafter referred to as "compound (a)" where appropriate) is a compound having only one anionic group and an aromatic ring.

[0049] The anionic group contained in the compound (a) may be a carboxylic acid group (—COOH), a carboxylic acid salt group (—COOX), a sulfonic acid group (—SO ３ H), sulfonate group (-SO ３ X), sulfate ester group (-OSO ３ H), sulfate ester group (-OSO ３ X), phosphate group (-OP(=O)(OH) ２ ), phosphate group (-OP(=O)(OH)(OX) or -OP(=O)(OX) ２ ) and the like. In the formula, X is an atom or molecule constituting a cation. Examples of X include metal atoms such as lithium, sodium, potassium, calcium, magnesium, and aluminum, and ammonium, with sodium, potassium, and ammonium being preferred, and sodium being more preferred. The anionic group possessed by compound (a) is preferably a sulfonate group or a sulfate ester group, more preferably a sulfonate group, and a sodium sulfonate group (—SO ３ That is, compound (a) is preferably a sulfonate or a sulfate salt, more preferably a sulfonate salt, and even more preferably a sodium sulfonate salt.

[0050] The aromatic ring contained in compound (a) may be any ring having aromaticity, and is not particularly limited, but examples thereof include non-condensed aromatic rings such as benzene rings and condensed aromatic rings such as naphthalene rings. Compound (a) preferably has a non-condensed aromatic ring, and the number of non-condensed aromatic rings in compound (a) is not particularly limited, but is preferably 1. The non-condensed aromatic ring contained in compound (a) is preferably a benzene ring, and the number of benzene rings in compound (a) is not particularly limited, but is preferably 1.

[0051] The compound (a) preferably has an alkyl group. When the compound (a) has an alkyl group, the alkyl group in the compound (a) preferably has 8 to 16 carbon atoms, and more preferably has 10 to 14 carbon atoms.

[0052] Examples of the compound (a) include alkylbenzene sulfonates such as sodium decylbenzene sulfonate, potassium decylbenzene sulfonate, sodium undecylbenzene sulfonate, potassium undecylbenzene sulfonate, sodium dodecylbenzene sulfonate, potassium dodecylbenzene sulfonate, sodium tridecylbenzene sulfonate, potassium tridecylbenzene sulfonate, sodium tetradecylbenzene sulfonate, and potassium tetradecylbenzene sulfonate. Among these, from the viewpoint of making the effects of the present invention more pronounced, alkylbenzene sulfonates are preferred, sodium alkylbenzene sulfonate is preferred, and sodium dodecylbenzene sulfonate is preferred. Compound (a) may be used alone or in combination of two or more types.

[0053] The molecular weight of the compound (a) is preferably 100 to 600, more preferably 200 to 500, and even more preferably 300 to 400, from the viewpoint of making the effects of the present invention more pronounced.

[0054] The dip-forming latex composition of the present invention contains, in addition to compound (a), a compound (b1) having two or more anionic groups and a benzene ring and / or a compound (b2) having one anionic group and no aromatic ring. That is, the latex composition used in the present invention contains, in addition to compound (a), at least one of compound (b1) or compound (b2), and may contain, in addition to compound (a), both compound (b1) and compound (b2). From the viewpoint of more pronounced effects of the present invention, it is more preferable that the dip-forming latex composition of the present invention contains, in addition to compound (a), at least compound (b1).

[0055] The number of anionic groups in compound (b1) having two or more anionic groups and a benzene ring (hereinafter referred to as "compound (b1)" as appropriate) is not particularly limited as long as it is two or more, but it is preferably two.

[0056] The anionic group contained in the compound (b1) is a carboxylic acid group (—COOH), a carboxylic acid salt group (—COOX), a sulfonic acid group (—SO３ H), sulfonate group (-SO ３ X), sulfate ester group (-OSO ３ H), sulfate ester group (-OSO ３ X), phosphate group (-OP(=O)(OH) ２ ), phosphate group (-OP(=O)(OH)(OX) or -OP(=O)(OX) ２ ) and the like. In the formula, X is an atom or molecule constituting a cation. Examples of X include metal atoms such as lithium, sodium, potassium, calcium, magnesium, and aluminum, and ammonium, among which sodium, potassium, and ammonium are preferred, and sodium is more preferred. The anionic group possessed by compound (b1) is preferably a sulfonate group or a sulfate ester group, more preferably a sulfonate group, and a sodium sulfonate group (—SO ３ Na) is more preferred. That is, compound (b1) is preferably a sulfonate or a sulfate ester salt, more preferably a sulfonate, and even more preferably a sodium sulfonate salt. The two or more anionic groups contained in compound (b1) may be the same or different, but are preferably the same.

[0057] Compound (b1) has a benzene ring. The number of benzene rings in compound (b1) is not particularly limited, but is preferably two or more, and more preferably two. Compound (b1) may have an aromatic ring other than a benzene ring. Examples of aromatic rings other than a benzene ring include non-fused aromatic rings containing heteroatoms and fused aromatic rings such as naphthalene rings. The number of aromatic rings other than a benzene ring in compound (b1) is preferably two or less, more preferably one or less, and even more preferably zero. That is, compound (b1) preferably does not have any aromatic rings other than a benzene ring.

[0058] The compound (b1) preferably has an ether bond, and more preferably has a diphenyl ether structure.

[0059] The compound (b1) preferably has an alkyl group. When the compound (b1) has an alkyl group, the alkyl group in the compound (b1) preferably has 8 to 16 carbon atoms, and more preferably has 10 to 14 carbon atoms.

[0060] Examples of the compound (b1) include alkyl diphenyl ether disulfonates such as disodium alkyl diphenyl ether disulfonate, dipotassium alkyl diphenyl ether disulfonate, and diammonium alkyl diphenyl ether disulfonate, and among these, from the viewpoint of making the effects of the present invention more pronounced, disodium alkyl diphenyl ether disulfonate is preferred, more preferably disodium alkyl diphenyl ether disulfonate having an alkyl group with 8 to 16 carbon atoms, and even more preferably disodium alkyl diphenyl ether disulfonate having an alkyl group with 10 to 14 carbon atoms. Compound (b1) may be used alone or in combination of two or more types.

[0061] The molecular weight of the compound (b1) is preferably from 100 to 1,000, more preferably from 200 to 850, even more preferably from 300 to 750, and particularly preferably from 400 to 650, from the viewpoint of making the effects of the present invention more pronounced.

[0062] The compound (b2) having one anionic group and no aromatic ring (hereinafter referred to as "compound (b2)" where appropriate) is a compound having only one anionic group and no aromatic ring.

[0063] The anionic group contained in the compound (b2) may be a carboxylic acid group (—COOH), a carboxylic acid salt group (—COOX), a sulfonic acid group (—SO ３ H), sulfonate group (-SO ３ X), sulfate ester group (-OSO ３ H), sulfate ester group (-OSO ３ X), phosphate group (-OP(=O)(OH) ２ ), phosphate group (-OP(=O)(OH)(OX) or -OP(=O)(OX) ２) and the like. In the formula, X is an atom or molecule constituting a cation. Examples of X include metal atoms such as lithium, sodium, potassium, calcium, magnesium, and aluminum, and ammonium, among which sodium, potassium, and ammonium are preferred, and sodium is more preferred. The anionic group possessed by compound (b2) is preferably a sulfonate group or a sulfate ester group, more preferably a sulfate ester group, and a sodium sulfate group (-OSO ３ That is, the compound (b2) is preferably a sulfonate or a sulfate ester salt, more preferably a sulfate ester salt, and further preferably a sodium sulfate ester salt.

[0064] The compound (b2) preferably has an alkyl group. When the compound (b2) has an alkyl group, the alkyl group in the compound (b2) preferably has 8 to 16 carbon atoms, and more preferably has 10 to 14 carbon atoms.

[0065] Examples of the compound (b2) include fatty acid salts such as sodium laurate, potassium myristate, sodium palmitate, potassium oleate, sodium linolenate, and sodium rosinate; alkyl sulfosuccinates such as sodium di(2-ethylhexyl)sulfosuccinate, potassium di(2-ethylhexyl)sulfosuccinate, and sodium dioctyl sulfosuccinate; sodium octyl sulfate, potassium octyl sulfate, sodium decyl sulfate, potassium decyl sulfate, sodium undecyl sulfate, potassium undecyl sulfate, sodium dodecyl sulfate (sodium lauryl sulfate), and potassium dodecyl sulfate (lauryl sulfate).

[0043] Examples of the alkyl ester salt include alkyl sulfates such as sodium tetradecyl sulfate, potassium tetradecyl sulfate, sodium hexadecyl sulfate, and potassium hexadecyl sulfate; polyoxyethylene alkyl ether sulfates such as sodium polyoxyethylene lauryl ether sulfate and potassium polyoxyethylene lauryl ether sulfate; and monoalkyl phosphates such as sodium lauryl phosphate and potassium lauryl phosphate. Among these, from the viewpoint of making the effects of the present invention more pronounced, alkyl sulfates are preferred, sodium alkyl sulfate is preferred, and sodium lauryl sulfate is more preferred.

[0066] The molecular weight of the compound (b2) is preferably from 100 to 600, more preferably from 200 to 450, and even more preferably from 250 to 350, from the viewpoint of making the effects of the present invention more pronounced.

[0067] In the anionic surfactant used in the present invention, from the viewpoint of making the effects of the present invention more pronounced, it is preferred that compound (a) is a sulfonate or a sulfate ester salt, and at least one of compound (b1) and compound (b2) is a sulfonate or a sulfate ester salt.

[0068] The content of the compound (a) in the latex composition for dip molding of the present invention is preferably 0.1 to 5.0 parts by weight, more preferably 0.5 to 3.0 parts by weight, still more preferably 0.8 to 2.4 parts by weight, and particularly preferably 1.0 to 2.0 parts by weight, relative to 100 parts by weight of the polymer component contained in the latex composition for dip molding, from the viewpoint that the effects of the present invention become more remarkable.

[0069] When the latex composition for dip molding of the present invention contains the compound (b1), the content of the compound (b1) in the latex composition for dip molding of the present invention is preferably 0.1 to 10.0 parts by weight, more preferably 0.5 to 7.0 parts by weight, still more preferably 1.0 to 5.0 parts by weight, and particularly preferably 1.2 to 4.5 parts by weight, relative to 100 parts by weight of the polymer component contained in the latex composition for dip molding, from the viewpoint that the effects of the present invention become more remarkable.

[0070] When the latex composition for dip molding of the present invention contains the compound (b2), the content of the compound (b2) in the latex composition for dip molding of the present invention is preferably 0.1 to 10.0 parts by weight, more preferably 0.5 to 7.0 parts by weight, still more preferably 1.0 to 5.0 parts by weight, and particularly preferably 1.2 to 4.5 parts by weight, relative to 100 parts by weight of the polymer component contained in the latex composition for dip molding, from the viewpoint that the effects of the present invention become more remarkable.

[0071] In the latex composition for dip molding of the present invention, the total content of the compound (b1) and the compound (b2) is preferably 0.1 to 10.0 parts by weight, more preferably 0.5 to 7.0 parts by weight, still more preferably 1.0 to 5.0 parts by weight, and particularly preferably 1.2 to 4.5 parts by weight, relative to 100 parts by weight of the polymer component contained in the latex composition for dip molding, from the viewpoint that the effects of the present invention become more remarkable.

[0072] In the latex composition for dip molding of the present invention, the weight ratio of the content of compound (a) to the total content of compound (b1) and compound (b2) (weight of compound (a):total weight of compound (b1) and compound (b2)) is preferably 5:95 to 95:5, more preferably 10:90 to 90:10, even more preferably 15:85 to 80:20, and particularly preferably 20:80 to 70:30, from the viewpoint of making the effects of the present invention more remarkable.

[0073] The latex composition for dip molding of the present invention preferably contains a latex of polymer (A) having a glass transition temperature of 10°C or lower, and more preferably contains a latex of polymer (B) having a glass transition temperature of higher than 10°C in addition to the latex of polymer (A) having a glass transition temperature of 10°C or lower.

[0074] The polymer (A) having a glass transition temperature of 10°C or lower (hereinafter referred to as "polymer (A)") constituting the latex of polymer (A) having a glass transition temperature of 10°C or lower (hereinafter referred to as "latex of polymer (A)") is not particularly limited, and examples thereof include conjugated diene-based polymers such as nitrile rubber (NBR), natural rubber (NR), styrene-butadiene rubber (SBR), synthetic polyisoprene rubber (IR), polybutadiene rubber (BR), styrene-isoprene copolymer rubber, and styrene-isoprene-styrene copolymer rubber, polybutyl acrylate, and butyl rubber (IIR). Among these, from the viewpoint of more pronounced effects of the present invention, synthetic rubber is preferred, with nitrile rubber (NBR), styrene-butadiene rubber (SBR), synthetic polyisoprene rubber (IR), and polybutyl acrylate being more preferred, and nitrile group-containing conjugated diene polymers being even more preferred. Note that these conjugated diene-based polymers may also be carboxyl group-containing conjugated diene-based polymers. As the polymer (A) having a glass transition temperature of 10° C. or less, among the polymers described above as constituting the latex of the polymer used in the present invention, those having a glass transition temperature of 10° C. or less are suitable. Furthermore, as the polymer (A) having a glass transition temperature of 10° C. or less, those described above as the nitrile group-containing conjugated diene polymers capable of constituting the latex of the polymer used in the present invention are suitable.

[0075] The volume average particle diameter of the polymer particles constituting the latex of polymer (A) is preferably 30 to 1,000 nm, more preferably 50 to 500 nm, and even more preferably 70 to 200 nm. By setting the volume average particle diameter of the polymer (A) particles within the above range, polymer (B) can be more satisfactorily finely dispersed in polymer (A) in the obtained dip-molded article, thereby making the effects of the present invention more pronounced and improving the mechanical properties of the obtained dip-molded article.

[0076] The polymer (B) having a glass transition temperature of above 10°C (hereinafter referred to as "polymer (B)") constituting the latex of polymer (B) having a glass transition temperature of above 10°C (hereinafter referred to as "latex of polymer (B)") is not particularly limited, and examples thereof include acrylic resin, PTFE resin, acrylonitrile-styrene (AS) resin, polyurethane, vinyl chloride resin, polystyrene resin, etc., and among these, acrylic resin is preferred. These polymers may be used alone or in combination of two or more.

[0077] Examples of acrylic resins include homopolymers of acrylic acid esters, methacrylic acid esters, acrylic acid, or methacrylic acid; copolymers of acrylic acid esters and acrylic acid; copolymers of acrylic acid esters and methacrylic acid; copolymers of methacrylic acid esters and acrylic acid; copolymers of methacrylic acid esters and methacrylic acid; copolymers of acrylic acid esters, methacrylic acid esters, and acrylic acid; and copolymers of acrylic acid esters, methacrylic acid esters, acrylic acid, and methacrylic acid. Among these, from the viewpoint of more pronounced effects of the present invention, homopolymers of acrylic acid esters, methacrylic acid esters, acrylic acid, or methacrylic acid are preferred, and homopolymers of methacrylic acid esters are more preferred. Homopolymers of acrylic acid esters include not only homopolymers of the same acrylic acid ester, but also copolymers of two or more acrylic acid esters (e.g., ethyl acrylate and butyl acrylate). Similarly, the homopolymer of a methacrylic acid ester includes not only a homopolymer of the same methacrylic acid ester but also a copolymer of two or more methacrylic acid esters. The total content of the acrylic acid ester, methacrylic acid ester, acrylic acid, and methacrylic acid units in the acrylic resin is preferably 40 to 100% by weight, more preferably 70 to 100% by weight, based on the total monomer units.

[0078] Examples of acrylic acid esters used to form the acrylic resin include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, n-pentyl acrylate, sec-pentyl acrylate, isopentyl acrylate, neopentyl acrylate, n-hexyl acrylate, isohexyl acrylate, neohexyl acrylate, sec-hexyl acrylate, and tert-hexyl acrylate. Of these, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, and n-butyl acrylate are preferred, and methyl acrylate is more preferred.

[0079] Examples of methacrylic acid esters used to form the acrylic resin include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, n-pentyl methacrylate, sec-pentyl methacrylate, isopentyl methacrylate, neopentyl methacrylate, n-hexyl methacrylate, isohexyl methacrylate, neohexyl methacrylate, sec-hexyl methacrylate, and tert-hexyl methacrylate, among which methyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, and n-butyl methacrylate are preferred, with methyl methacrylate being more preferred. As the acrylic resin, a homopolymer of methyl methacrylate (polymethyl methacrylate) is particularly preferred.

[0080] The acrylic resin may be a copolymer of an acrylic acid ester monomer, a methacrylic acid ester monomer, an acrylic acid monomer, or a methacrylic acid monomer with other monomers copolymerizable therewith.

[0081] Other copolymerizable monomers include α-olefin monomers such as ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, and 1-octene; aromatic monomers such as styrene, α-methylstyrene, and vinylpyridine; α,β-ethylenically unsaturated polycarboxylic acids such as maleic acid, fumaric acid, and itaconic acid; α,β-ethylenically unsaturated polycarboxylic acid monoesters such as monomethyl maleate, monoethyl maleate, and monoethyl itaconate; dimethyl maleate, fumaric acid, and the like. Examples of suitable copolymerizable monomers include α,β-ethylenically unsaturated polycarboxylic acid polyesters such as di-n-butyl itaconate, dimethyl itaconate, and di-2-ethylhexyl itaconate; vinyl ester monomers such as vinyl acetate and vinyl propionate; α,β-ethylenically unsaturated monocarboxylic acid amides such as acrylamide and methacrylamide; N-substituted maleimides; vinyl ether monomers such as vinyl methyl ether, vinyl ethyl ether, and vinyl cetyl ether; and vinylidene compounds such as vinylidene chloride. Among these, aromatic monomers are preferred, and styrene is more preferred. The content of units of other copolymerizable monomers is preferably 0 to 60% by weight, more preferably 0 to 30% by weight, based on the total monomer units.

[0082] The method for producing the acrylic resin latex as the polymer (B) is not particularly limited as long as it is a method capable of polymerizing the above-mentioned monomers, and examples thereof include known methods such as emulsion polymerization by radical polymerization, seed emulsion polymerization, and fine suspension polymerization.

[0083] The polymer (B) is preferably one obtained by using a persulfate such as sodium persulfate, potassium persulfate, or ammonium persulfate as a polymerization initiator. By using a persulfate as a polymerization initiator, the polymer (B) can have a sulfate group at the polymer chain end as a residue of the polymerization initiator, and thus the latex of the polymer (B) can be made to have more excellent chemical stability.

[0084] The weight average molecular weight (Mw) of the acrylic resin as the polymer (B) is not particularly limited, but is preferably 10,000 to 10,000,000, and more preferably 10,000 to 5,000,000.

[0085] The glass transition temperature of polymer (B) is more than 10° C., and from the viewpoint of making the effects of the present invention more pronounced, it is preferably 30° C. or higher, more preferably 70° C. or higher, even more preferably 95° C. or higher, and particularly preferably 105° C. or higher. The upper limit of the glass transition temperature of polymer (B) is not particularly limited, but is preferably 200° C. or lower, more preferably 150° C. or lower. The method for adjusting the glass transition temperature of polymer (B) to the above range is not particularly limited, but examples include a method of adjusting the content ratio of units of each monomer constituting the polymer.

[0086] From the viewpoint of making the effects of the present invention more remarkable, the latex composition for dip molding of the present invention is preferably a latex composition for dip molding obtained by mixing, in a latex state, a latex of a polymer (A) having a glass transition temperature of 10°C or lower and a latex of a polymer (B) having a glass transition temperature of more than 10°C.

[0087] In particular, by mixing the latex of polymer (A) and the latex of polymer (B) in a latex state, particles of polymer (A) and particles of polymer (B) can be uniformly and finely dispersed in the latex composition for dip molding. When a dip-molded article is obtained by dip molding, the polymer (B) can be co-precipitated in a finely dispersed state in the matrix of polymer (A) in the obtained dip-molded article. Therefore, the finely dispersed polymer (B) acts to impart even better wet grip properties to the obtained dip-molded article.

[0088] From the viewpoint of further improving the wet grip property of the obtained dip-molded article, it is preferable that the volume average particle diameter of the particles of polymer (B) constituting the latex of polymer (B) is smaller than the volume average particle diameter of the particles of polymer (A) constituting the latex of polymer (A).

[0089] The volume average particle diameter of the particles of polymer (B) constituting the latex of polymer (B) is preferably 1 to 200 nm, more preferably 5 to 160 nm, even more preferably 5 to 120 nm, still more preferably 10 to 100 nm, and particularly preferably 20 to 80 nm. By setting the volume average particle diameter of the particles of polymer (B) within the above range, polymer (B) can be more satisfactorily finely dispersed in polymer (A) in the obtained dip-molded article, thereby making the effects of the present invention more pronounced and improving the mechanical properties of the obtained dip-molded article.

[0090] When the dip-forming latex composition of the present invention contains a latex of polymer (A) and a latex of polymer (B), the contents of polymer (A) and polymer (B) in the dip-forming latex composition of the present invention are not particularly limited, but the content of polymer (A) relative to 100% by weight of the polymer components contained in the dip-forming latex composition is preferably 75 to 100% by weight, more preferably 80 to 99% by weight, and even more preferably 85 to 95% by weight. Furthermore, the content of polymer (B) relative to 100% by weight of the polymer components contained in the dip-forming latex composition is preferably 0 to 25% by weight, more preferably 1 to 20% by weight, and even more preferably 5 to 15% by weight. Furthermore, in the latex composition for dip molding of the present invention, the weight ratio of the polymer (A) to the polymer (B) (weight of the polymer (A):weight of the polymer (B)) is preferably 75:25 to 100:0, more preferably 80:20 to 99:1, and even more preferably 85:15 to 95:5, since the effects of the present invention become more remarkable.

[0091] The dip-molding latex composition of the present invention preferably further contains a sulfur-based crosslinking agent in addition to the polymer latex and the anionic surfactant.

[0092] The sulfur-based crosslinking agent is not particularly limited, but examples thereof 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 selenium, and 2-(4'-morpholinodithio)benzothiazole. These sulfur-based crosslinking agents may be used alone or in combination of two or more.

[0093] The content of the sulfur-based crosslinking agent is preferably 0.01 to 5 parts by weight, more preferably 0.05 to 3 parts by weight, and even more preferably 0.1 to 2 parts by weight, based on 100 parts by weight of the polymer component contained in the latex composition for dip molding.

[0094] Furthermore, the dip-molding latex composition of the present invention preferably further contains a crosslinking accelerator (vulcanization accelerator) and zinc oxide in addition to the sulfur-based crosslinking agent.

[0095] 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, and 2-(2,4-dinitrophenylthio)benzo Examples of crosslinking accelerators include thiazole, 2-(N,N-diethylthiocarbamoylthio)benzothiazole, 2-(2,6-dimethyl-4-morpholinothio)benzothiazole, 2-(4'-morpholinodithio)benzothiazole, 4-morpholinyl-2-benzothiazyl disulfide, and 1,3-bis(2-benzothiazylmercaptomethyl)urea. Of these, zinc diethyldithiocarbamate, zinc dibutyldithiocarbamate, 2-mercaptobenzothiazole, and zinc 2-mercaptobenzothiazole are preferred. These crosslinking accelerators may be used alone or in combination of two or more.

[0096] The content of the crosslinking accelerator is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the polymer components contained in the latex composition for dip molding. The content of zinc oxide is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the polymer components contained in the latex composition for dip molding.

[0097] The dip-molding latex composition of the present invention may further contain a water-soluble polymer.

[0098] Examples of water-soluble polymers include vinyl compounds such as polyvinyl alcohol and polyvinylpyrrolidone; cellulose derivatives and salts thereof such as hydroxyethyl cellulose, hydroxypropyl cellulose, and carboxymethyl cellulose; polycarboxylic acid compounds such as polyacrylic acid and sodium salts thereof; and polyoxyethylene derivatives such as polyethylene glycol ether. Preferred water-soluble polymers are cellulose derivatives and salts thereof, with carboxymethyl cellulose and sodium salts thereof being more preferred. The content of the water-soluble polymer is preferably 0.01 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, per 100 parts by weight of the polymer component contained in the dip-molding latex composition.

[0099] The viscosity of a 4 wt % aqueous solution of the water-soluble polymer is not particularly limited, but is preferably 1 mPa s or more, more preferably 10 mPa s or more, and preferably 20,000 mPa s or less, and more preferably 10,000 mPa s or less. The viscosity of a 1 wt % aqueous solution of the water-soluble polymer is not particularly limited, but is preferably 1 mPa s or more, more preferably 10 mPa s or more, and preferably 20,000 mPa s or less, and more preferably 10,000 mPa s or less. The viscosity of the aqueous water-soluble polymer solution can be measured, for example, using a Brookfield viscometer at 25°C and a rotation speed of 6 rpm.

[0100] The water-soluble polymer may be any polymer as long as it is soluble in water, and the solubility of the water-soluble polymer in water is not particularly limited, but is preferably 1 g or more, more preferably 7 g or more, and particularly preferably 10 g or more per 100 g of water at a temperature of 25° C. The upper limit of the solubility of the water-soluble polymer in water is not particularly limited, but is usually 1,000,000 g or less.

[0101] The weight average molecular weight (Mw) of the water-soluble polymer is not particularly limited, but is preferably 100 or more, more preferably 1,000 or more, and is preferably 5,000,000 or less, more preferably 3,000,000 or less.

[0102] The amount of the water-soluble polymer to be blended is preferably 0.01 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, and even more preferably 0.15 to 4.5 parts by weight, based on 100 parts by weight of the polymer component contained in the dip-forming latex composition of the present invention. When the amount of the water-soluble polymer to be blended is within the above range, the obtained dip-formed article has even better wet grip properties.

[0103] The dip-forming latex composition of the present invention may also contain fillers such as carbon black, silica, calcium carbonate, aluminum silicate, magnesium silicate, calcium silicate, magnesium oxide, zinc (meth)acrylate, magnesium (meth)acrylate, and titanium oxide. The amount of filler is preferably 0.5 to 30 parts by weight, more preferably 1 to 10 parts by weight, and even more preferably 2 to 5 parts by weight, per 100 parts by weight of the polymer components contained in the dip-forming latex composition of the present invention. When the amount of filler is within the above range, the resulting dip-molded article exhibits even better wet grip properties. Furthermore, the dip-molding latex composition of the present invention may also contain, if necessary, predetermined amounts of various additives other than the water-soluble salts and fillers, such as antioxidants, antioxidants, preservatives, antibacterial agents, wetting agents, dispersants, pigments, dyes, reinforcing agents, and pH adjusters.

[0104] The volume average particle diameter of the polymer particles in the dip-molding latex composition of the present invention is preferably 30 to 250 nm, more preferably 30 to 200 nm, and even more preferably 50 to 180 nm. By setting the volume average particle diameter of the polymer particles in the dip-molding latex composition within the above range, the resulting dip-molding latex composition can be made to have excellent storage stability, and the resulting dip-molded article can be made to have even better wet grip properties. The volume average particle diameter of the polymer particles in the dip-molding latex composition of the present invention can be measured, for example, using a light scattering / diffraction particle analyzer.

[0105] The solids concentration of the dip molding latex composition of the present invention is preferably 20 to 65% by weight, more preferably 30 to 60% by weight, and even more preferably 35 to 55% by weight. By adjusting the solids concentration of the dip molding latex composition within the above range, the transport efficiency of the dip molding latex composition can be improved, and the viscosity of the dip molding latex composition becomes appropriate, thereby improving the handleability of the dip molding latex composition.

[0106] The solid content of the dip-molding latex composition of the present invention can be adjusted to the above range by, for example, adjusting the solid content of each component such as a polymer latex, or by a concentration treatment or dilution treatment, which will be described later. Among these, the concentration treatment is preferred from the viewpoint of productivity.

[0107] The pH of the latex composition for dip molding of the present invention is preferably 5 to 13, more preferably 7 to 10, and even more preferably 7.5 to 9. By adjusting the pH of the latex composition for dip molding within the above range, the mechanical stability is improved, making it possible to suppress the generation of coarse aggregates during the transfer of the latex composition for dip molding, and the viscosity of the latex composition for dip molding becomes appropriate, improving the handleability of the latex composition for dip molding.

[0108] <Method for Producing Latex Composition for Dip Molding> The method for producing the latex composition for dip molding of the present invention is not particularly limited as long as it is a method that can produce a latex composition for dip molding containing a polymer latex, compound (a), and compound (b1) and / or compound (b2). A preferred method for producing the latex composition for dip molding of the present invention is a method in which two or more types of polymer latex are prepared and mixed in a latex state. Below, an example of a method for producing the latex composition for dip molding of the present invention is shown, in which two or more types of polymer latex are prepared and mixed in a latex state.

[0109] The dip-molding latex composition of the present invention may, for example, comprise a first polymer (A１ ) and a compound (a) １ -a), and a second polymer (A) having a glass transition temperature of 10°C or less ２ ) and the compound (b1) and / or the compound (b2). ２ The polymer (A) can be obtained by a production method in which the polymer (A) and the polymer (B) are mixed in a latex state. １ ) "Latex (A １ -a) "Polymer (A ２ ) "Latex (A ２ The abbreviation "-b)" is used.

[0110] The method for producing the dip-molding latex composition of the present invention includes the steps of: １ -a) and latex (A ２ The dip-molding latex composition of the present invention obtained by this method can realize excellent resistance to chemical permeation in the dip-molded article, while further improving the balance between flexibility and wet grip property. １ -a) and latex (A ２ It is presumed that this is because, by mixing the latex with -b), aggregates of an appropriate size are generated, and an appropriate uneven structure is formed on the surface of the obtained dip-molded article.

[0111] Polymer (A １ ) and the composition of the polymer (A ２ The compositions of the polymers (A) may be the same or different. １ When the polymer (A) is a nitrile group-containing conjugated diene polymer, ２ ) is a polymer (A １ The polymer (A) may be a nitrile group-containing conjugated diene polymer having the same or different composition as the polymer (A), or may be a polymer other than the nitrile group-containing conjugated diene polymer (for example, polybutyl acrylate). ２ When the polymer (A) is a nitrile group-containing conjugated diene polymer, １ ) is a polymer (A ２The polymer may be a nitrile group-containing conjugated diene polymer having the same or different composition as the nitrile group-containing conjugated diene polymer, or a polymer other than the nitrile group-containing conjugated diene polymer (for example, polybutyl acrylate).

[0112] Polymer (A １ ) and the glass transition temperature of the polymer (A ２ ) is preferably 30°C or less, more preferably 20°C or less, even more preferably 15°C or less, particularly preferably 10°C or less, and most preferably 5°C or less.

[0113] The dip-molding latex composition of the present invention may be obtained by a production method in which, for example, latex (A-a) containing polymer (A) and compound (a), each having a glass transition temperature of 10° C. or lower, and latex (B-b) containing polymer (B) and compound (b1) and / or compound (b2), are mixed in a latex state. Hereinafter, the abbreviations "latex (A-a)" and "latex (B-b)" will be used where appropriate.

[0114] The dip-molding latex composition of the present invention may be obtained by a production method in which, for example, latex (A-b) containing polymer (A) having a glass transition temperature of 10° C. or lower and compound (b1) and / or compound (b2), and latex (B-a) containing polymer (B) having a glass transition temperature of more than 10° C. and compound (a), are mixed in a latex state. Hereinafter, the abbreviations "latex (A-b)" and "latex (B-a)" will be used as appropriate.

[0115] In each of the above-mentioned production methods, a latex containing a polymer and a compound (a) (latex (A １The method for incorporating compound (a) into latex (A-a), latex (A-a), or latex (B-a)) is not particularly limited, and examples thereof include a method of performing polymerization in the presence of compound (a) to obtain a latex containing a polymer and compound (a), or a method of preparing a latex containing a polymer and then adding compound (a). Among these, the method of performing polymerization in the presence of compound (a) is preferred. Furthermore, the latex containing a polymer and compound (a) may further contain compound (b1) and / or compound (b2). In this case, the method for incorporating compound (b1) and / or compound (b2) is not particularly limited, and examples thereof include a method of performing polymerization in the presence of compound (b1) and / or compound (b2) to obtain a latex containing a polymer and compound (b1) and / or compound (b2), or a method of preparing a latex containing a polymer and then adding compound (b1) and / or compound (b2). Among these, the method of carrying out the polymerization in the presence of the compound (b1) and / or the compound (b2) is preferred.

[0116] In each of the production methods exemplified above, a latex (latex (A)) containing a polymer and the compound (b1) and / or the compound (b2) is prepared. ２The method for incorporating compound (b1) and / or compound (b2) into latex (B-b), latex (B-b), or latex (A-b) is not particularly limited, and examples thereof include a method of performing polymerization in the presence of compound (b1) and / or compound (b2) to obtain a latex containing a polymer and compound (b1) and / or compound (b2), and a method of preparing a latex containing a polymer and then adding compound (b1) and / or compound (b2). Among these, the method of performing polymerization in the presence of compound (b1) and / or compound (b2) is preferred. Furthermore, the latex containing a polymer and compound (b1) and / or compound (b2) may further contain compound (a). In this case, the method for incorporating compound (a) is not particularly limited, and examples thereof include a method of performing polymerization in the presence of compound (a) to obtain a latex containing a polymer and compound (a), and a method of preparing a latex containing a polymer and then adding compound (a). Among these, the method of carrying out the polymerization in the presence of the compound (a) is preferred.

[0117] By appropriately combining the above-mentioned methods of mixing two types of latex in a latex state, three or more types of latex may be mixed in a latex state. １ -a) and latex (A ２ The latex (Ba) and / or the latex (Bb) may be mixed in the latex state.

[0118] The dip-molding latex composition of the present invention may be obtained through a concentration treatment or a dilution treatment. Preferably, the dip-molding latex composition of the present invention is obtained through a concentration treatment. The concentration treatment method is not particularly limited, but examples thereof include vacuum distillation, atmospheric distillation, centrifugation, membrane concentration, etc. Among these, a concentration method involving heating is preferred, and vacuum distillation involving heating is more preferred. By employing a concentration method involving heating, it is possible to reduce bacteria that cause odor or to inhibit the growth of bacteria that cause odor, thereby making the dip-molding latex composition excellent in low odor properties.

[0119] In the concentration method involving heating, the heating temperature is preferably 50° C. to 100° C. In the distillation under reduced pressure, the pressure is preferably 20 kPa to 90 kPa.

[0120] The concentration treatment may be performed on a mixture containing some of the components to be blended into the dip-molding latex composition, or on a mixture containing all of the components to be blended into the dip-molding latex composition.

[0121] Each component to be blended as necessary may be added to the composition containing the polymer latex, the compound (a), and the compound (b1) and / or the compound (b2) obtained by the above-mentioned production method.

[0122] <Dip-molded article> The dip-molded article of the present invention is an article obtained using the latex composition for dip molding of the present invention described above, and is usually obtained by dip molding using the latex composition for dip molding of the present invention described above. Since the dip-molded article of the present invention is obtained using the latex composition for dip molding of the present invention described above, it has excellent resistance to chemical liquid permeation and is excellent in a well-balanced manner in wet grip property and flexibility.

[0123] When a latex composition for dip molding containing two or more polymers is used, the dip-molded product of the present invention contains the two or more polymers, and the content ratio of each polymer in the dip-molded product is usually equal to the content ratio of each polymer in the latex composition for dip molding.

[0124] The dip-molded article of the present invention is preferably a laminate having a substrate and a polymer layer formed on the substrate using the dip-molding latex composition of the present invention. The laminate may be, for example, a laminate of a substrate and a polymer layer comprising the dip-molding latex composition, obtained by immersing the substrate in the dip-molding latex composition of the present invention. The dip-molded article of the present invention may also be a film-molded article comprising the dip-molding latex composition, obtained by immersing a dip-molding mold in the above-described dip-molding latex composition of the present invention. Hereinafter, a case where the dip-molded article of the present invention is a laminate of a substrate and a polymer layer comprising the dip-molding latex composition of the present invention will be described as an example, but the present invention is not limited to such an embodiment.

[0125] The substrate is not particularly limited, but when the dip-molded article of the present invention is used as a protective glove, a fibrous substrate can be suitably used. The fibrous substrate is not particularly limited, but for example, a glove made by weaving a twisted monofilament yarn can be used. The average thickness of the fibrous substrate is preferably 50 to 3,000 μm, more preferably 100 to 2,000 μm.

[0126] The dip-molded article of the present invention can be produced, for example, by immersing a substrate in the latex composition for dip molding to form a polymer layer made of the latex composition for dip molding on the substrate. In this case, it is preferable to immerse the substrate in the latex composition for dip molding in a state in which the substrate is previously placed on a molding die having a desired shape.

[0127] The mold for covering the substrate is not particularly limited, and various materials such as porcelain, glass, metal, and plastic can be used. The shape of the mold may be a desired shape according to the shape of the final product. For example, when the dip-molded article of the present invention is used as a protective glove, it is preferable to use various types of molds for gloves, such as molds having a shape from the wrist to the fingertips, as the mold for covering the substrate.

[0128] Furthermore, before immersing the substrate in the dip-molding latex composition, it is preferable to first immerse the substrate in a coagulant solution to adhere the coagulant solution to the substrate. In this case, it is preferable to immerse the substrate in the coagulant solution while the substrate is first placed over a mold of the desired shape. Examples of molds of the desired shape include those described above. Furthermore, after adhering the coagulant solution to the substrate, it is preferable to remove the solvent contained in the coagulant solution by drying. The drying temperature is not particularly limited and may be selected depending on the solvent used, but is preferably 10 to 80°C, more preferably 15 to 70°C. The drying time is not particularly limited, but is preferably 600 to 1 second, more preferably 300 to 5 seconds.

[0129] Next, the substrate with the coagulant solution attached thereto is placed over a molding die of a desired shape, and is immersed in the latex composition for dip molding while it is still in this state, thereby coagulating the latex composition for dip molding and adhering a polymer layer made of the latex composition for dip molding onto the substrate.

[0130] After immersing the substrate in the dip-molding latex composition, it is preferable to dry the substrate. The drying temperature is not particularly limited, but is preferably 10 to 80° C., more preferably 15 to 80° C. The drying time is not particularly limited, but is preferably 120 minutes to 5 seconds, more preferably 60 minutes to 10 seconds.

[0131] When a latex composition for dip molding containing a sulfur-based crosslinking agent is used, the latex composition for dip molding may be aged in advance (also referred to as pre-vulcanized).

[0132] The temperature conditions for aging are not particularly limited, but are preferably 20 to 50° C. Furthermore, the aging time is preferably 4 hours or more and 120 hours or less, more preferably 24 hours or more and 72 hours or less, from the viewpoint of preventing peeling between the substrate and the polymer layer and improving the mechanical properties of the polymer layer.

[0133] Next, it is preferable to heat the dip-molding latex composition attached to the substrate to crosslink the polymer components contained in the dip-molding latex composition.

[0134] The heating temperature for crosslinking is preferably 60 to 160°C, more preferably 80 to 150°C. By setting the heating temperature within the above range, the time required for the crosslinking reaction can be shortened, thereby improving the productivity of dip-molded articles, and oxidative degradation of the polymer component due to excessive heating can be suppressed, thereby improving the physical properties of the obtained dip-molded articles. The heating time for crosslinking can be appropriately selected depending on the heating temperature, but is usually 5 to 120 minutes.

[0135] It is preferable to remove water-soluble impurities (such as emulsifiers, water-soluble polymers, and coagulants) from the polymer layer of the dip-molded article obtained in this manner, by immersing the polymer layer formed on the substrate in warm water at 20 to 80°C for about 0.5 to 60 minutes, as necessary.

[0136] After immersion in warm water, drying may be further performed. The drying temperature and drying time at this time are not particularly limited, but can be the same as the drying temperature and drying time in the drying step after immersion in the latex composition for dip molding described above.

[0137] Then, after forming a polymer layer on the substrate while the substrate is placed over the mold as described above, the dip-molded article can be obtained by removing the substrate from the mold (or demolding). Methods for removing the substrate from the mold include peeling it off by hand, or by using water pressure or compressed air.

[0138] Before or after detaching the dip-molded article from the mold, it may be subjected to a further heat treatment (post-crosslinking step) at a temperature of 60 to 120° C. for 10 to 120 minutes. After detaching the dip-molded article from the mold, a surface treatment layer may be formed on the inner and / or outer surfaces of the dip-molded article by a chlorination treatment, a coating treatment, or the like.

[0139] As a method for obtaining a dip-molded article, a method of foaming a latex composition for dip-molding other than the latex composition for dip-molding of the present invention and dip-molding the foamed article can be considered. However, such a method tends to result in an excessively small arithmetic mean roughness Ra of the surface of the polymer layer of the obtained dip-molded article, which may result in poor wet grip properties and poor flexibility.

[0140] Another possible method for obtaining a dip-formed article is to form a dip layer using a dip-forming latex composition other than the dip-forming latex composition of the present invention, then adhere a water-soluble metal salt to the surface of the dip layer, and optionally dry, crosslink, or otherwise perform the process, after which the water-soluble metal salt adhered to the surface is washed away. However, such a method tends to result in the maximum height roughness Rz and arithmetic mean roughness Ra of the surface of the polymer layer of the obtained dip-formed article being too large, which may result in poor flexibility or poor resistance to chemical permeation. Furthermore, there is a risk that components derived from the water-soluble metal salt (e.g., metal components) may remain on the surface of the dip-formed article.

[0141] In addition, these methods require a foaming step, a step of adhering a water-soluble metal salt, and a step of washing away the water-soluble metal salt, which may reduce the production efficiency of dip-molded articles.

[0142] By using the dip-forming latex composition of the present invention, it is possible to obtain the dip-formed article of the present invention, which has excellent resistance to chemical permeation and a well-balanced excellent wet grip property and flexibility, without undergoing a foaming step, a step of adhering a water-soluble metal salt, and a step of washing away the water-soluble metal salt. Therefore, by using the dip-forming latex composition of the present invention, it is possible to produce the dip-formed article of the present invention with high production efficiency while reducing components derived from the water-soluble metal salt (e.g., metal components) on the surface of the dip-formed article of the present invention.

[0143] In the dip-molded article of the present invention, the polymer layer made of the latex composition for dip molding of the present invention has a thickness of preferably 0.05 to 1.0 mm, more preferably 0.06 to 0.8 mm, and even more preferably 0.07 to 0.7 mm.

[0144] Furthermore, when the dip-formed article of the present invention includes a substrate and a polymer layer, the thickness of the laminate including the substrate and the polymer layer is preferably 0.1 to 10 mm, more preferably 0.4 to 2.0 mm, and even more preferably 0.5 to 1.1 mm.

[0145] In the dip-molded article of the present invention, the 100% tensile stress of the polymer layer composed of the dip-molding latex composition of the present invention is preferably 1.1 MPa or less, more preferably 0.1 to 0.9 MPa, even more preferably 0.2 to 0.75 MPa, and particularly preferably 0.3 to 0.7 MPa. By using the dip-molding latex composition of the present invention, a dip-molded article having a 100% tensile stress within the above range, which exhibits a well-balanced combination of wet grip performance and flexibility, as well as excellent resistance to chemical permeation, can be easily obtained. The 100% tensile stress of the polymer layer can be controlled, for example, by adjusting the type of polymer latex used, the type and amount of surfactant, such as anionic surfactant, used, etc. When two or more polymer latexes are used, the 100% tensile stress of the polymer layer can be controlled by adjusting the type and ratio of each polymer latex.

[0146] The 100% tensile stress of the polymer layer made of the dip-forming latex composition of the present invention in the dip-molded article of the present invention is measured by the following method. First, a measurement latex is prepared containing the latex of the polymer constituting the dip-molding latex composition, compound (a), and compound (b1) and / or compound (b2) in the same proportions as those contained in the dip-molding latex composition. The prepared measurement latex is applied to a glass substrate and dried to obtain a film-molded article. The 100% tensile stress of the obtained film-molded article is measured, and the obtained value is the 100% tensile stress value of the polymer layer. For example, when the dip-molding latex composition is obtained by adding additives such as a sulfur-based crosslinking agent, a crosslinking accelerator, zinc oxide, a water-soluble polymer, and a filler to a latex mixture containing a polymer latex, compound (a), and compound (b1) and / or compound (b2), which are used as needed, the latex mixture (the latex mixture before adding the additives) is used as the latex to be measured. The 100% tensile stress of the polymer layer is specifically measured by the method described in the Examples.

[0147] In the dip-molded article of the present invention, the surface roughness in maximum height Rz of the polymer layer made of the latex composition for dip-molding of the present invention is preferably 135 to 350 μm, more preferably 155 to 320 μm, still more preferably 180 to 310 μm, particularly preferably 230 to 300 μm, and most preferably 260 to 295 μm.

[0148] In the dip-molded article of the present invention, the arithmetic mean roughness Ra of the surface of the polymer layer made of the latex composition for dip-molding of the present invention is preferably 20 to 72 μm, more preferably 25 to 65 μm, still more preferably 30 to 60 μm, and particularly preferably 35 to 55 μm.

[0149] In the dip-molded article of the present invention, the surface area ratio at 50% height of the polymer layer made of the latex composition for dip molding of the present invention is preferably 20 to 80%, more preferably 30 to 70%, still more preferably 35 to 60%, and particularly preferably 40 to 52%. Here, the 50% height is the average height of the maximum height (100% height) and the minimum height (0% height) in the measurement area, and the area ratio at 50% height is the projected area ratio of the part of the measurement area whose height is higher than the 50% height.

[0150] The surface roughness of the polymer layer (maximum height roughness Rz, arithmetic mean roughness Ra, and areal surface area ratio at 50% height) is determined from height data of the polymer layer surface obtained using a laser microscope. The maximum height roughness Rz and arithmetic mean roughness Ra are determined in accordance with JIS B 0601:2013. The areal surface area ratio at 50% height is determined by calculating the 50% height (the average height of the maximum height (100% height) and the minimum height (0% height)) from the obtained height data, and then calculating the projected area ratio of the portion of the measurement area whose height is higher than the 50% height. Specifically, it is determined by the method described in the examples.

[0151] The dip-molded article of the present invention has excellent resistance to chemical permeation and a well-balanced excellent wet grip property and flexibility, and can be suitably used, for example, for gloves, particularly for protective gloves. While the above description has been given by way of example of a case in which the dip-molded article of the present invention is a laminate of a substrate and a polymer layer comprising the latex composition for dip molding of the present invention, as mentioned above, the present invention is not limited to such an embodiment, and it is of course also possible to form a film-molded article comprising the latex composition for dip molding by immersing a dip-molding mold in the latex composition for dip molding.

[0152]

[0013] Incidentally, gloves consisting of only a polymer layer without a substrate are thin and therefore rarely have a problem with wet grip property. On the other hand, gloves which are a laminate of a substrate and a polymer layer consisting of a latex composition for dip molding tend to have a thick glove (total thickness of the laminate of the substrate and the polymer layer) and therefore have a specific problem that wet grip property is insufficient. By using the latex composition for dip molding of the present invention, gloves which are a laminate of a substrate and a polymer layer consisting of the latex composition for dip molding of the present invention can be made to have excellent resistance to chemical permeation and a well-balanced excellent wet grip property and flexibility.

[0153] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. Note that "parts" and "%" are by weight unless otherwise specified. Various measurements were carried out according to the following methods.

[0154] <Solid content concentration> 2 g of sample (weight: X2) was weighed out onto an aluminum dish (weight: X1) and dried in a hot air dryer at 105°C for 2 hours. After cooling in a desiccator, the sample was weighed together with the aluminum dish (weight: X3) and the solid content concentration was calculated according to the following formula: Solid content concentration (wt%) = (X3 - X1) x 100 / X2

[0155] <Volume Average Particle Diameter> The volume average particle diameter of the polymer particles constituting the polymer latex was measured using a light scattering diffraction particle analyzer (manufactured by Coulter, product name "LS-230").

[0156] <Surface tension of polymer latex> The surface tension of the polymer latex was measured using a surface tensiometer (DY-300, manufactured by Kyowa Interface Science Co., Ltd.). The measured value is expressed in mN / m. The measurement was carried out at 25°C.

[0157] <Difference between Surface Tension of Polymer Latex and Surface Tension of Anionic Surfactant> The surface tension of the polymer latex was measured by the above method. A 5.0 wt % aqueous solution of the anionic surfactant (compound (a), compound (b1), compound (b2)) used in each Production Example was prepared, and the surface tension (surface tension of the surfactant) was measured using a surface tensiometer (DY-300, manufactured by Kyowa Interface Science Co., Ltd.). The measurement was carried out at 25°C. When two or more types of anionic surfactants were used, the surfactants were mixed according to the ratio of the amounts used of each surfactant, and then the amount of water was adjusted to prepare an aqueous solution with a total surfactant concentration of 5.0 wt %. The difference between the surface tension of the polymer latex and the surface tension of the surfactant was then calculated using the following formula: Difference between Surface Tension of Polymer Latex and Surface Tension of Surfactant = Surface Tension of Polymer Latex - Surface Tension of Surfactant

[0158] <Content of surfactant in latex composition for dip molding> The content of surfactant in the latex composition for dip molding was calculated from the amount of surfactant used in each production example, the polymerization conversion rate in each production example, and the blending ratio in each example.

[0159] <100% Tensile Stress of Film Molded Article (100% Tensile Stress of Polymer Layer)> The measurement latex obtained in each Example and Comparative Example was applied to a glass substrate and dried at 25°C for 120 hours to obtain a film molded article having a thickness of 0.4 mm. The obtained film molded article was punched out with a dumbbell (product name "Super Dumbbell (Model: SDMK-100C)" manufactured by Dumbbell Co., Ltd.) to obtain a test piece. The 100% tensile stress of the test piece was measured at a pulling rate of 500 mm / min using a Tensilon universal testing machine (product name "RTG-1210" manufactured by Orientec Co., Ltd.), and the obtained value was defined as the 100% tensile stress of the film molded article (100% tensile stress of the polymer layer).

[0160] <Surface Roughness of Polymer Layer of Protective Glove> The surface roughness (maximum height roughness Rz, arithmetic mean roughness Ra, and area load ratio at 50% height) of the polymer layer of the protective glove was measured using a laser microscope (VK-X100 manufactured by Keyence Corporation) under the following measurement conditions to obtain height data of the polymer layer of the protective glove. Then, using analysis software (the "surface roughness" measurement function of VK shape analysis application VK-H1XJ manufactured by Keyence Corporation), the maximum height roughness Rz and the arithmetic mean roughness Ra were determined from the obtained height data in accordance with JIS B 0601:2013. Furthermore, from the obtained height data, the 50% height (the average height of the maximum height (100% height) and the minimum height (0% height)) was calculated, and then the area load ratio at 50% height (the projected area ratio of the part higher than the 50% height) was determined. <Measurement conditions> Measurement mode: Surface profile Measurement quality: High precision Measurement magnification: 200x Measurement area: 1000 μm x 1000 μm

[0161] <Wet Grip Property of Protective Gloves> Metal molds with different weights ranging from 0.5 kg to 15.0 kg in 0.5 kg increments were prepared. Three workers were asked to wear protective gloves and lift the dry metal molds in order of weight, starting with the lightest, and the maximum weight (W1 (kg)) that they could lift was determined for each of the three workers. Next, test oil IRM903 was applied to the metal molds. The three workers were then asked to wear protective gloves and lift the metal molds with test oil IRM903 applied in order of weight, starting with the lightest, and the maximum weight (W2 (kg)) that they could lift was determined for each of the three workers. The scores calculated for each of the three workers using the following formula were then arithmetically averaged to calculate an average score for evaluation. The higher the score, the greater the maximum weight that could be lifted, and the better the wet grip property. (Score) = 100 × W2 (kg) / W1 (kg)

[0162] <Resistance to Chemical Liquid Permeation of Protective Gloves> The amount of oil permeation through protective gloves was measured by the following procedure. (1) The index finger portion of a protective glove (laminate) was cut out to obtain a finger-shaped test piece. (2) Test oil IRM903 was placed in an aluminum cup. (3) Filter paper (weight: W１ ) and place the part of the test piece that corresponds to the pad of the finger (area: approximately 2-5 cm ２ (4) The test piece containing the filter paper was placed in an aluminum cup containing test oil IRM903, and the outer surface of the part corresponding to the pad of the finger (the part where the filter paper was in close contact in (3)) was brought into contact with the test oil IRM903. (5) After leaving it for 24 hours, the filter paper was removed from the test piece, and the weight of the filter paper after the test (W ２ (6) The amount of test oil IRM903 that permeated the test piece (W ２ -W ２ ) was calculated. (7) The middle finger portion, ring finger portion, and little finger portion of the protective glove (laminate) were cut out, respectively, to obtain three more test pieces. For each of the obtained test pieces, the amount of test oil IRM903 that had permeated through the test piece was determined in the same manner as above. (8) The average amount of test oil IRM903 that had permeated through the test piece for a total of four test pieces was determined and this was taken as the amount of oil permeation of the protective glove. It can be determined that the smaller the amount of oil permeation, the better the oil permeation resistance and chemical liquid permeation resistance.

[0163] <Flexibility of Protective Gloves> The flexibility of the protective gloves was evaluated by a sensory test. Specifically, the following commercially available protective gloves A and B were prepared as control samples and evaluated according to the following procedure. Protective glove A: A dip-molded product (laminate) having a substrate and a polymer layer, which was obtained without undergoing a step of foaming the polymer layer or a surface treatment step after forming the dip layer. Protective glove A has very excellent flexibility but no wet grip property. Protective glove B: A dip-molded product (laminate) having a substrate and a polymer layer, which was obtained through a surface treatment step after forming the dip layer. Protective glove B has relatively high wet grip property. The same subject used the protective gloves obtained in the Examples and Comparative Examples, protective glove A, and protective glove B, and judged whether the flexibility of the protective gloves obtained in the Examples and Comparative Examples was better, equal to, or worse than that of protective glove A and protective glove B. The flexibility was evaluated according to the following criteria. 5 Has better flexibility than protective glove A 4 Has flexibility equivalent to protective glove A 3 Has flexibility intermediate between the flexibility of protective glove A and protective glove B 2 Has flexibility equivalent to protective glove B 1 Has flexibility inferior to protective glove B The higher the value, the better the flexibility is judged to be.

[0164] <Production Example 1> (Production of a latex of polybutyl acrylate (A-1)) 100 parts of n-butyl acrylate as the α,β-ethylenically unsaturated monocarboxylic acid ester monomer, 6.7 parts of alkyl diphenyl ether disulfonate sodium (mainly composed of dodecyl diphenyl ether disulfonate sodium) as the compound (b1), 0.4 parts of t-dodecyl mercaptan, 150 parts of ion-exchanged water as a solvent, and 1.33 parts of potassium persulfate as a polymerization initiator were charged into a 5 MPa pressure vessel equipped with a stirrer, and after thorough stirring, the mixture was heated to a temperature of 80°C to initiate polymerization. When the monomer consumption reached 96.0%, the mixture was cooled to terminate the reaction. A 5% aqueous solution of sodium hydroxide was added to the obtained aqueous dispersion containing polybutyl acrylate, and the pH was adjusted to 7. Thereafter, unreacted monomers were removed by heating and distillation under reduced pressure, and the mixture was cooled to a temperature of 30°C or below to obtain a latex of polybutyl acrylate (A-1). The glass transition temperature (Tg) of the polybutyl acrylate (A-1) contained in the obtained latex of polybutyl acrylate (A-1) was -50°C. Using the latex of polybutyl acrylate (A-1), the volume average particle size, the content of surfactant in the polymer latex, the surface tension of the polymer latex, and the difference between the surface tension of the polymer latex and the surface tension of the surfactant were measured according to the methods described above. The results are shown in Table 1.

[0165] <Production Example 2> (Production of latex of carboxyl group-containing nitrile rubber (A-2)) A polymerization reactor was charged with 67.5 parts of 1,3-butadiene as a conjugated diene monomer, 27 parts of acrylonitrile as an α,β-ethylenically unsaturated nitrile monomer, 5.5 parts of methacrylic acid as an ethylenically unsaturated monocarboxylic acid monomer, 0.7 parts of t-dodecyl mercaptan, 132 parts of ion-exchanged water, 6.7 parts of alkyldiphenylether disulfonate sodium as compound (b1), 0.5 parts of β-naphthalenesulfonic acid formalin condensate sodium salt, 0.3 parts of potassium persulfate, and 0.05 parts of ethylenediaminetetraacetic acid sodium salt, and polymerization was carried out while maintaining the polymerization temperature at 30 to 40°C. The reaction was continued until the polymerization conversion reached 94%, thereby obtaining a latex of a copolymer. Then, unreacted monomers were removed from the obtained copolymer latex, and then the pH and solid content of the copolymer latex were adjusted to obtain a latex of carboxyl group-containing nitrile rubber (A-2) having a solid content of 40% by weight and a pH of 8. The glass transition temperature (Tg) of the carboxyl group-containing nitrile rubber (A-2) contained in the obtained latex of carboxyl group-containing nitrile rubber (A-2) was −24° C., and the monomer composition of the carboxyl group-containing nitrile rubber (A-2) was approximately the same as the charged ratio. Using the latex of carboxyl group-containing nitrile rubber (A-2), measurements were carried out in the same manner as in Production Example 1. The results are shown in Table 1.

[0166] <Production Example 3> (Production of latex of carboxyl group-containing nitrile rubber (A-3) containing methyl methacrylate units) A latex of carboxyl group-containing nitrile rubber (A-3) containing methyl methacrylate units having a solid content concentration of 40% by weight and a pH of 8 was obtained in the same manner as in Production Example 2, except that the amounts of 1,3-butadiene, acrylonitrile, and methacrylic acid were changed to 47.3 parts, 18.8 parts, and 3.9 parts, respectively, and further, 30 parts of methyl methacrylate was charged into the polymerization reactor together with these monomers. The glass transition temperature (Tg) of the carboxyl group-containing nitrile rubber (A-3) containing methyl methacrylate units contained in the obtained latex of the carboxyl group-containing nitrile rubber (A-3) containing methyl methacrylate units was -14°C, and the monomer composition of the carboxyl group-containing nitrile rubber (A-3) containing methyl methacrylate units was almost the same as the charged ratio. Measurements were carried out in the same manner as in Production Example 1 using the latex of the carboxyl group-containing nitrile rubber (A-3) containing methyl methacrylate units. The results are shown in Table 1.

[0167] <Production Example 4> (Production of Latex of Carboxyl Group-Containing Nitrile Rubber (A-4)) A latex of carboxyl group-containing nitrile rubber (A-4) having a solids concentration of 40% by weight and a pH of 8 was obtained in the same manner as in Production Example 2, except that 6.7 parts of sodium lauryl sulfate was used as compound (b1) instead of 6.7 parts of sodium alkyldiphenyletherdisulfonate. The glass transition temperature (Tg) of the carboxyl group-containing nitrile rubber (A-4) contained in the obtained latex of carboxyl group-containing nitrile rubber (A-4) was −24° C., and the monomer composition of the carboxyl group-containing nitrile rubber (A-4) was almost the same as the charged ratio. Measurements were carried out in the same manner as in Production Example 1 using the latex of carboxyl group-containing nitrile rubber (A-4). The results are shown in Table 1.

[0168] <Production Example 5> (Production of Latex of Carboxyl Group-Containing Nitrile Rubber (A-5)) A latex of carboxyl group-containing nitrile rubber (A-5) having a solids concentration of 40% by weight and a pH of 8 was obtained in the same manner as in Production Example 2, except that the amount of sodium alkyldiphenyletherdisulfonate used was changed from 6.7 parts to 3.0 parts. The glass transition temperature (Tg) of the carboxyl group-containing nitrile rubber (A-5) contained in the obtained latex of carboxyl group-containing nitrile rubber (A-5) was −24° C., and the monomer composition of the carboxyl group-containing nitrile rubber (A-5) was almost the same as the charged ratio. Measurements were carried out in the same manner as in Production Example 1 using the latex of carboxyl group-containing nitrile rubber (A-5). The results are shown in Table 1.

[0169] <Production Example 6> (Production of Latex of Carboxyl Group-Containing Nitrile Rubber (A-6)) A latex of carboxyl group-containing nitrile rubber (A-6) having a solids concentration of 40% by weight and a pH of 8 was obtained in the same manner as in Production Example 2, except that 3.0 parts of sodium dodecylbenzenesulfonate was used as compound (a) instead of 6.7 parts of sodium alkyldiphenyletherdisulfonate. The glass transition temperature (Tg) of the carboxyl group-containing nitrile rubber (A-6) contained in the obtained latex of carboxyl group-containing nitrile rubber (A-6) was −24° C., and the monomer composition of the carboxyl group-containing nitrile rubber (A-6) was approximately the same as the charged ratio. Measurements were carried out in the same manner as in Production Example 1 using the latex of carboxyl group-containing nitrile rubber (A-6). The results are shown in Table 1.

[0170] <Production Example 7> (Production of latex of carboxyl group-containing nitrile rubber (A-7)) To the latex of carboxyl group-containing nitrile rubber (A-6) obtained in Production Example 6, sodium alkyldiphenyl ether disulfonate was added in an amount of 3.0 parts per 100 parts of the carboxyl group-containing nitrile rubber (A-6) contained in the latex of carboxyl group-containing nitrile rubber (A-6), thereby obtaining a latex of carboxyl group-containing nitrile rubber (A-7). Using the latex of carboxyl group-containing nitrile rubber (A-7), measurements were carried out in the same manner as in Production Example 1. The results are shown in Table 1.

[0171] Production Example 8 (Production of polymethyl methacrylate resin (B) latex) A polymerization reactor was charged with 100 parts of methyl methacrylate, 6.7 parts of alkyldiphenyl ether disulfonate sodium as compound (b1), 0.4 parts of t-dodecyl mercaptan, 200 parts of ion-exchanged water, 0.3 parts of potassium persulfate, and 0.1 parts of ethylenediaminetetraacetic acid sodium salt. The polymerization temperature was maintained at 30 to 70°C to carry out polymerization until the polymerization conversion reached 95%, thereby obtaining a polymer latex. The pH and solids concentration of the polymer latex were then adjusted to obtain a polymethyl methacrylate resin (B) latex with a solids concentration of 30 wt% and a pH of 8.5. The glass transition temperature (Tg) of the polymethyl methacrylate resin (B) contained in the obtained polymethyl methacrylate resin (B) latex was 120°C. Using the latex of polymethyl methacrylate resin (B), measurements were carried out in the same manner as in Production Example 1. The results are shown in Table 1.

[0172]

[0173] Examples 1 to 8 and Comparative Example 1 (Preparation of Aqueous Dispersion of Colloidal Sulfur) 1.0 part of colloidal sulfur (manufactured by Hosoi Chemical Industry Co., Ltd.), 0.5 part of a dispersant (manufactured by Kao Corporation, trade name "Demol N"), 0.0015 parts of a 5 wt % aqueous potassium hydroxide solution (manufactured by Wako Pure Chemical Industries, Ltd.), and 1.0 part of water were pulverized and stirred in a ball mill for 48 hours to prepare an aqueous dispersion of colloidal sulfur with a solids concentration of 50 wt %.

[0174] (Preparation of aqueous dispersion of zinc dibutyldithiocarbamate, aqueous dispersion of zinc oxide, and aqueous dispersion of titanium oxide) An aqueous dispersion of zinc dibutyldithiocarbamate having a solids concentration of 50 wt %, an aqueous dispersion of zinc oxide having a solids concentration of 50 wt %, and an aqueous dispersion of titanium oxide having a solids concentration of 50 wt % were prepared in the same manner as above, except that zinc dibutyldithiocarbamate (manufactured by Ouchi Shinko Chemical Industry Co., Ltd.), zinc oxide (manufactured by Seido Chemical Industry Co., Ltd.), and titanium oxide, respectively, were used instead of colloidal sulfur.

[0175] (Preparation of latex composition for dip molding) The latexes of the polymers obtained in each production example were mixed so that the ratio of the polymer components in the latex of each polymer was the ratio shown in Table 2 to obtain a latex mixture. A part of the obtained latex mixture was used as a measurement latex to measure and evaluate the 100% tensile stress of the film molded product (100% tensile stress of the polymer layer). The results are shown in Table 2.

[0176] The aqueous dispersions of each compounding ingredient prepared above were added to the latex mixture so that, based on solids content, they would be 1.0 part colloidal sulfur, 1.0 part zinc dibutyldithiocarbamate, 1.5 parts zinc oxide, and 3.0 parts titanium oxide per 100 parts of the polymer component in the resulting latex mixture. The aqueous dispersions of each compounding ingredient were added slowly in predetermined amounts while the latex mixture was being stirred. After the compounding ingredients were uniformly mixed, a water-soluble polymer, carboxymethyl cellulose (manufactured by Daicel Corporation, trade name "Daicel 2200", weight average molecular weight: 550,000), was added until the viscosity reached 3,000 cps, yielding a dip molding latex composition with a solids concentration of 40% by weight. The resulting dip molding latex composition was used to determine the surfactant content. The results are shown in Table 2.

[0177] (Preparation of Coagulant Solution) A coagulant solution was prepared by dissolving calcium nitrate as a coagulant in methanol at a ratio of 2.0 wt %.

[0178] (Production of Protective Gloves) First, the dip-molding latex composition obtained above was aged (also referred to as pre-vulcanization) at 30°C for 48 hours. Next, a ceramic glove mold covered with a glove-shaped fiber substrate (material: nylon, linear density: 300 denier, gauge: 13 gauge, thickness: 0.8 mm) was immersed in the coagulant solution prepared above for 5 seconds, removed from the coagulant solution, and dried at 30°C for 1 minute. The ceramic glove mold was then immersed in the aged dip-molding latex composition for 5 seconds, removed from the aged dip-molding latex composition, and dried at 25°C for 20 minutes to form a dip layer on the fiber substrate. The ceramic glove mold with the dip layer formed thereon was then heat-treated at 110°C for 30 minutes to crosslink the polymer in the dip layer, forming a polymer layer. Next, the fiber substrate with the polymer layer formed thereon was peeled off from the ceramic glove mold to obtain a protective glove (dip-molded article). The thickness of the polymer layer in the obtained protective glove was 0.15 mm, and the thickness of the protective glove (the total thickness of the laminate including the substrate and polymer layer) was 1.0 mm. Using the obtained protective glove, the surface roughness of the polymer layer (maximum height roughness Rz, arithmetic mean roughness Ra, and area load ratio at 50% height), wet grip performance of the protective glove, chemical permeation resistance of the protective glove, and flexibility of the protective glove were evaluated. The results are shown in Table 2. In Examples 1 to 8, dip-molded articles with excellent chemical permeation resistance and a good balance of wet grip performance and flexibility were obtained without undergoing a foaming process of the latex composition or a surface treatment process after forming the dip layer (e.g., a process of adhering a water-soluble metal salt to the surface of the dip layer, further drying, crosslinking, etc. as necessary, and then rinsing off the water-soluble metal salt adhered to the surface).

[0179]

[0180] As shown in Table 2, when a dip-molding latex composition containing a polymer latex and an anionic surfactant is used, the anionic surfactant containing a compound (a) having one anionic group and an aromatic ring, and a compound (b1) having two or more anionic groups and a benzene ring, or a compound (b2) having one anionic group and no aromatic ring, the dip-molded article obtained has excellent resistance to chemical permeation and a well-balanced excellent wet grip property and flexibility (Examples 1 to 8).

[0181] On the other hand, when the anionic surfactant contained only compound (a) having one anionic group and an aromatic ring, the obtained dip-molded article had poor wet grip properties (Comparative Example 1).

Claims

1. A latex composition for dip molding, containing a polymer latex and an anionic surfactant, wherein the anionic surfactant contains a compound (a) having one anionic group and an aromatic ring, and a compound (b1) having two or more anionic groups and a benzene ring or a compound (b2) having one anionic group and no aromatic ring, the latex composition for dip molding.

2. The latex composition for dip molding according to Claim 1, wherein the compound (b1) is a compound having two anionic groups and a benzene ring.

3. The latex composition for dip molding according to Claim 1 or 2, wherein the compound (b1) is an alkyl diphenyl ether disulfonate.

4. The latex composition for dip molding according to Claim 1 or 2, wherein the compound (b2) is an alkyl sulfate ester salt.

5. The latex composition for dip molding according to Claim 1 or 2, wherein the compound (a) is a sulfonate or a sulfate ester salt, and at least one of the compound (b1) or the compound (b2) is a sulfonate or a sulfate ester salt.

6. The latex composition for dip molding according to Claim 1 or 2, wherein the compound (a) is an alkylbenzene sulfonate.

7. The latex composition for dip molding according to Claim 1 or 2, wherein the content of the compound (a) is 0.1 to 5.0 parts by weight with respect to 100 parts by weight of the polymer component contained in the latex composition for dip molding.

8. The latex composition for dip molding according to Claim 1 or 2, wherein the total content of the compound (b1) and the compound (b2) is 0.1 to 10.0 parts by weight with respect to 100 parts by weight of the polymer component contained in the latex composition for dip molding.

9. The latex composition for dip molding according to Claim 1 or 2, wherein the weight ratio of the content of the compound (a) to the total content of the compound (b1) and the compound (b2) [weight of the compound (a): total weight of the compound (b1) and the compound (b2)] is 5:95 to 95:

5.

10. The latex composition for dip molding according to Claim 1 or 2, wherein the polymer latex is a latex of a nitrile group-containing conjugated diene polymer.

11. A dip molded article obtained by using the latex composition for dip molding according to Claim 1 or 2.

12. The dip-molded article according to claim 11, which is a glove.