JP2020164690A - Latex composition for dip molding - Google Patents

Abstract

To provide a latex composition for dip molding capable of providing a dip-molded article having excellent storage stability, flexibility, abrasion resistance and wet grip performance.SOLUTION: There is provided a latex composition for dip molding obtained by mixing a latex of a conjugated diene-based polymer (A) in which, when adjusting the solid content concentration to 35 wt.%, the specific gravity is 0.950 to 1.050 g/cm3, water-insoluble fine particles (B) in which, when preparing an aqueous dispersion having a solid content concentration of 35 wt.%, the specific gravity is 1.100 to 2.200 g/cm3 and a water-soluble salt (C) composed of a monovalent cation and a metal compound anion.SELECTED DRAWING: None

Description

The present invention relates to a latex composition for dip molding, and more particularly, a latex composition for dip molding capable of providing a dip molded body having excellent storage stability and excellent flexibility, abrasion resistance, and wet grip. Regarding things.

Conventionally, solvent resistance, grip resistance, abrasion resistance, etc. have been improved by covering fiber gloves with rubber, resin, etc. in various applications such as factory manufacturing work, light work, construction work, and agricultural work. Protective gloves are used.

Since such protective gloves are usually used in contact with the human body, they are required to have excellent mechanical strength such as abrasion resistance and durability, as well as excellent flexibility. Has been done.

For example, Patent Document 1 describes a coagulant solution adhering step of adhering a coagulant solution to a fiber base material, and a polymer latex is brought into contact with the fiber base material to which the coagulant solution is attached to coagulate the polymer. A coagulation step of forming a polymer layer on the fiber base material is provided, and as the coagulant solution, 0.2 to 7.0% by weight of a metal salt as a coagulant in a solvent, and A method for producing a laminate using a product obtained by dissolving or dispersing 0.1 to 7.0% by weight of an organic acid is disclosed.

International Publication No. 2018/061868

According to the technique of Patent Document 1, although a laminate having excellent flexibility and abrasion resistance and suitable for use in protective gloves can be obtained, it has excellent grip performance (that is, wet grip property) when it gets wet with water. There is room for improvement, and further improvement is required from the viewpoint that it can be suitably used even in applications where it is used wet with water.

The present invention has been made in view of such an actual situation, and is a latex for dip molding capable of providing a dip molded body having excellent storage stability and excellent flexibility, abrasion resistance, and wet grip. It is an object of the present invention to provide a composition. It is also an object of the present invention to provide a dip molded product obtained by using such a latex composition for dip molding.

As a result of diligent research to solve the above problems, the present inventor has applied the latex of the conjugated diene polymer (A) having a specific specific gravity in a specific range, fine particles having a specific specific gravity in a specific range, and a specific water-soluble salt. According to the latex composition obtained by mixing with, the dip molded product obtained by dip molding the dip molded product having excellent storage stability is excellent in flexibility, abrasion resistance, and wet grip. We have found that it can be used as a polymer, and have completed the present invention.

That is, according to the present invention, the latex of the conjugated diene polymer (A) having a specific gravity of 0.950 to 1.050 g / cm ³ when the solid content concentration is 35% by weight, and the solid content concentration of 35% by weight. Water-insoluble fine particles (B) having a specific gravity of 1.100 to 2.200 g / cm ³ when made into an aqueous dispersion of%, and a water-soluble salt (C) composed of a monovalent cation and a metal compound anion. To provide a latex composition for dip molding, which is a mixture of and.

In the latex composition for dip molding of the present invention, it is preferable that the conjugated diene polymer (A) is a nitrile group-containing conjugated diene polymer.
In the latex composition for dip molding of the present invention, the weight average particle size of the fine particles (B) is preferably 0.05 to 50 μm.
In the latex composition for dip molding of the present invention, the content ratio of the conjugated diene polymer (A) and the fine particles (B) is the weight of the "conjugated diene polymer (A): fine particles (B)". The ratio is preferably 95: 5 to 50:50.
In the dip-molded latex composition of the present invention, the fine particles (B) are polymer particles having a specific gravity of 1.100 to 1.500 g / cm ³ when made into an aqueous dispersion having a solid content concentration of 35% by weight. It is preferable to have.
In the latex composition for dip molding of the present invention, the polymer particles are preferably vinyl chloride resin particles.
In the latex composition for dip molding of the present invention, it is preferable that the particles of the vinyl chloride resin do not contain a plasticizer.
The latex composition for dip molding of the present invention preferably further contains a sulfur-based cross-linking agent.
In the latex composition for dip molding of the present invention, the water-soluble salt (C) preferably has a specific gravity of 1.15 g / cm ³ or more when made into a 20% by weight aqueous solution.
In the latex composition for dip molding of the present invention, it is preferable that the monovalent cation is a sodium ion and the metal compound anion is a metal acid ion.
In the latex composition for dip molding of the present invention, it is preferable that the water-soluble salt (C) is at least one selected from sodium aluminate, sodium titanate, sodium molybdate, and sodium tungstate.

Further, according to the present invention, there is provided a dip molded body using the above-mentioned latex composition for dip molding.
Further, according to the present invention, there is provided a dip molded body obtained by immersing the above-mentioned latex composition for dip molding in a base material.

According to the present invention, a dip molding latex composition capable of providing a dip molded product having excellent storage stability, flexibility, abrasion resistance, and wet grip, and such a dip molding latex. A dip molded article obtained by using the composition can be provided.

FIG. 1 is a diagram showing an indentation test apparatus 20 used for measuring the flexibility of an embodiment.

<Latex composition for dip molding>
The latex composition for dip molding of the present invention contains the latex of the conjugated diene polymer (A) having a specific gravity of 0.950 to 1.050 g / cm ³ when the solid content concentration is 35% by weight, and the solid content. A water-soluble salt composed of water-insoluble fine particles (B) having a specific gravity of 1.100 to 2.200 g / cm ³ when prepared as an aqueous dispersion having a concentration of 35% by weight, and a monovalent cation and a metal compound anion. (C) is a latex composition obtained by mixing.

The conjugated diene polymer (A) constituting the latex of the conjugated diene polymer (A) and having a specific gravity of 0.950 to 1.050 g / cm ³ when the solid content concentration is 35% by weight (hereinafter, The "conjugated diene polymer (A)" is appropriately used as long as it is a polymer having a unit derived from the conjugated diene monomer, and is not particularly limited, but for example, nitrile rubber (NBR). , Natural rubber (NR), styrene-butadiene rubber (SBR), synthetic polyisoprene rubber (IR), polybutadiene rubber (BR), styrene-isoprene copolymer rubber, styrene-isoprene-styrene copolymer rubber and the like. Among these, from the viewpoint that the effect of the present invention becomes more remarkable, a conjugated diene-based polymer containing a nitrile group such as NBR (hereinafter, appropriately referred to as "nitrile group-containing conjugated diene-based polymer"). Is preferable.

The nitrile group-containing conjugated diene polymer is not particularly limited, but is an α, β-ethylenically unsaturated nitrile monomer, a conjugated diene monomer, and other copolymerizable copolymers used as needed. A copolymer of an ethylenically unsaturated acid monomer can be used.

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 monomer include acrylonitrile, methacrylonitrile, halogen-substituted acrylonitrile, and the like, and among these, acrylonitrile is particularly preferable. It should be noted that these α, β-ethylenically unsaturated nitrile monomers may be used alone or in combination of two or more.

The content ratio of the α, β-ethylenically unsaturated nitrile monomer unit in the nitrile group-containing conjugated diene polymer is preferably 10 to 45% by weight, more preferably 20 to 40% by weight, based on the total monomer units. It is% by weight, more preferably 25 to 40% by weight. By setting the content ratio of the α, β-ethylenically unsaturated nitrile monomer unit in the above range, the obtained dip molded product can be made excellent in solvent resistance.

As the conjugated diene monomer, a conjugated diene monomer having 4 to 6 carbon atoms such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and chloroprene is preferable. , 1,3-butadiene and isoprene are more preferred, and 1,3-butadiene is particularly preferred. In addition, these conjugated diene monomers may be used individually by 1 type, and may be used in combination of 2 or more type.

The content ratio of the conjugated diene monomer unit in the nitrile group-containing conjugated diene polymer is preferably 40 to 80% by weight, more preferably 52 to 78% by weight, still more preferably 55, based on all the monomer units. ~ 75% by weight. By setting the content ratio of the conjugated diene monomer unit in the above range, the obtained dip molded product can be made more flexible.

Further, the nitrile group-containing conjugated diene polymer can be copolymerized with a monomer forming an α, β-ethylenic unsaturated nitrile monomer unit and a monomer forming a conjugated diene monomer unit. It may be copolymerized with other ethylenically unsaturated acid monomers.

The other copolymerizable ethylenically unsaturated acid monomer is not particularly limited, and for example, a carboxyl group-containing ethylenically unsaturated monomer, a sulfonic acid group-containing ethylenically unsaturated monomer, and the like. Examples thereof include ethylenically unsaturated monomers containing a phosphate group.

The carboxyl group-containing ethylenically unsaturated monomer is not particularly limited, but is an ethylenically unsaturated monocarboxylic acid such as acrylic acid, methacrylic acid, and crotonic acid; fumaric acid, maleic acid, itaconic acid, maleic anhydride, and anhydrous. Examples thereof include ethylenically unsaturated polyvalent carboxylic acid such as itaconic acid and its anhydride; a partial esterified product of ethylenically unsaturated polyvalent carboxylic acid such as methyl maleate and methyl itaconic acid.

The sulfonic acid group-containing ethylenically unsaturated monomer is not particularly limited, but is limited to vinyl sulfonic acid, methyl vinyl sulfonic acid, styrene sulfonic acid, (meth) allyl sulfonic acid, and (meth) acrylic acid-2-sulfonic acid ethyl. , 2-acrylamide-2-hydroxypropanesulfonic acid and the like.

The phosphoric acid group-containing ethylenically unsaturated monomer is not particularly limited, but is limited to propyl (meth) acrylic acid-3-chloro-2-phosphate, ethyl (meth) -2-phosphate, and 3-allyloxy. -2-Hydroxypropane phosphoric acid and the like can be mentioned.

These other copolymerizable ethylenically unsaturated acid monomers can also be used as alkali metal salts or ammonium salts, or may be used alone or in combination of two or more. Good. Among the other copolymerizable ethylenically unsaturated acid monomers, the carboxyl group-containing ethylenically unsaturated monomer is preferable, the ethylenically unsaturated monocarboxylic acid is more preferable, and acrylic acid and methacrylic acid are preferable. More preferably, methacrylic acid is particularly preferable.

When the nitrile group-containing conjugated diene polymer contains a unit of another copolymerizable ethylenically unsaturated acid monomer, the content of the other copolymerizable ethylenically unsaturated acid monomer unit The ratio is preferably 0.1 to 15% by weight, more preferably 1 to 10% by weight, still more preferably 2 to 8% by weight, based on the total monomer units.

The latex of the nitrile group-containing conjugated diene polymer can be obtained, for example, by emulsion polymerization of a monomer mixture containing the above-mentioned monomer. In emulsion polymerization, commonly used polymerization auxiliary materials such as emulsifiers, polymerization initiators, and molecular weight modifiers can be used.

The emulsifier used for emulsion polymerization is not particularly limited, and examples thereof include anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants, and anionic surfactants are used. preferable. Specific examples of anionic surfactants include fatty acid salts such as sodium laurate, potassium myristate, sodium palmitate, potassium oleate, sodium linolenate, and sodium loginate; sodium dodecylbenzene sulfonate, potassium dodecylbenzene sulfonate. Alkylbenzene sulfonates such as sodium decylbenzene sulfonate, potassium decylbenzene sulfonate, sodium cetylbenzenesulfonate, potassium cetylbenzenesulfonate; sodium di (2-ethylhexyl) sulfosuccinate, potassium di (2-ethylhexyl) sulfosuccinate. Alkyl sulfosuccinates such as sodium dioctyl sulfosuccinate; alkyl sulfates such as sodium lauryl sulfate and potassium lauryl sulfate; polyoxyethylene alkyl ether sulfates such as sodium polyoxyethylene lauryl ether sulfate and potassium polyoxyethylene lauryl ether sulfate. Salts; monoalkyl phosphates such as sodium lauryl phosphate and potassium lauryl phosphate; and the like.
The amount of the emulsifier used in the 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 all the monomers used.

The polymerization initiator is not particularly limited, but a radical initiator is preferable. The radical initiator is not particularly limited, and is, for example, an inorganic peroxide such as sodium persulfate, potassium persulfate, ammonium persulfate, potassium perphosphate, hydrogen peroxide; t-butyl peroxide, cumene hydroperoxide, etc. p-menthane hydroperoxide, di-t-butyl peroxide, t-butylcumyl peroxide, acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, dibenzoyl peroxide, 3,5,5-trimethylhexanoyl Organic peroxides such as peroxide and t-butylperoxyisobutyrate; azo compounds such as azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, azobiscyclohexanecarbonitrile, methyl azobisisobutyrate; etc. Among these, inorganic peroxides or organic peroxides are preferable, inorganic peroxides are more preferable, and persulfates are particularly preferable. 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 all the monomers used.

The molecular weight modifier is not particularly limited, and is, for example, α-methylstyrene dimer; mercaptans such as t-dodecyl mercaptan, n-dodecyl mercaptan, and octyl mercaptan; halogenation of carbon tetrachloride, methylene chloride, methylene bromide, and the like. Hydrocarbons; sulfur-containing compounds such as tetraethylthiuram diesulfide, dipentamethylene thiol sulfide, diisopropylxanthogen diesulfide; and the like; among these, mercaptans are preferable, and t-dodecyl mercaptan is more preferable. These molecular weight adjusting agents may be used alone or in combination of two or more.
The amount of the molecular weight adjusting agent used varies depending on the type, but is preferably 0.1 to 1.5 parts by weight, more preferably 0.2 to 1.0 parts by weight, based on 100 parts by weight of all the monomers used. It is a department.

Emulsion polymerization is usually carried out in water. The amount of water used is preferably 80 to 500 parts by weight, more preferably 100 to 200 parts by weight, based on 100 parts by weight of all the monomers used.

In the emulsion polymerization, if necessary, a polymerization auxiliary material other than the above may be further used. Examples of the polymerization auxiliary material include a chelating agent, a dispersant, a pH adjusting agent, an oxygen scavenger, a particle size adjusting agent, and the like, and the type and amount of these are not particularly limited.

Examples of the method for adding the monomer include a method of collectively adding the monomers used in the reaction vessel, a method of continuously or intermittently adding the monomers as the polymerization progresses, and a method of adding a part of the monomers. Then, the reaction is carried out to a specific conversion rate, and then the remaining monomer is continuously or intermittently added to polymerize, and any of these methods may be adopted. When the monomers are mixed and added continuously or intermittently, the composition of the mixture may be constant or varied.
In addition, each monomer may be added to the reaction vessel after mixing various monomers to be used in advance, or may be added to the reaction vessel separately.

The polymerization temperature at the time of emulsion polymerization is not particularly limited, but is usually 0 to 95 ° C, preferably 5 to 70 ° C. The polymerization time is not particularly limited, but is usually about 5 to 40 hours.

After terminating the polymerization reaction, if desired, the unreacted monomer may be removed to adjust the solid content concentration and pH.

The latex of the conjugated diene polymer (A) used in the present invention has a specific gravity when the solid content concentration is 35% by weight (that is, the specific gravity of the latex itself when the solid content concentration is adjusted to 35% by weight). It is 0.950 to 1.050 g / cm ³ , preferably 0.960 to 1.030 g / cm ³ . The latex of the conjugated diene polymer (A) having a specific gravity in the above range when the solid content concentration is 35% by weight and the specific gravity when an aqueous dispersion having a solid content concentration of 35% by weight, which will be described later, are 1. The latex composition is preserved by using a combination of water-insoluble fine particles (B) of 100 to 2.200 g / cm ³ and a water-soluble salt (C) composed of a monovalent cation and a metal compound anion. The resulting dip-molded product can be made excellent in flexibility, abrasion resistance, and wet grip while being excellent in stability. The method for setting the specific gravity of the conjugated diene polymer (A) constituting the latex of the conjugated diene polymer (A) at a solid content concentration of 35% by weight within the above range is not particularly limited. For example, a method in which the content ratio of the unit of each monomer constituting the conjugated diene polymer (A) is within the above-mentioned range can be mentioned. When the solid content concentration is 35% by weight, when the solid content concentration of the latex of the conjugated diene polymer (A) is higher than 35% by weight, water is added to obtain the solid content. The concentration may be adjusted to 35% by weight for measurement, and if the solid content concentration of the latex of the conjugated diene polymer (A) is lower than 35% by weight, concentration is performed and the solid content concentration is 35% by weight. It may be adjusted to% and measured.

The glass transition temperature of the conjugated diene polymer (A) constituting the latex of the conjugated diene polymer (A) is preferably 10 ° C. or lower, more preferably 45 to -10 ° C., still more preferably. Is -40 to -10 ° C. By setting the glass transition temperature of the conjugated diene polymer (A) in the above range, the wet grip property of the obtained dip molded product can be further enhanced. The method for setting the glass transition temperature of the conjugated diene polymer (A) in the above range is not particularly limited, but for example, the content ratio of the unit of each monomer constituting the conjugated diene polymer (A). Is included in the above-mentioned range.

The weight average particle size of the particles of the conjugated diene polymer (A) constituting the latex of the conjugated diene polymer (A) is preferably 30 to 1000 nm, more preferably 50 to 500 nm, and further preferably 70 to 70. It is 200 nm. By setting the weight average particle diameter of the particles of the conjugated diene polymer (A) in the above range, the solid content concentration of 35% by weight, which will be described later, is contained in the conjugated diene polymer (A) in the obtained dip molded product. Water-insoluble fine particles (B) having a specific gravity of 1.100 to 2.200 g / cm ³ can be better finely dispersed as an aqueous dispersion, thereby further enhancing wear resistance. be able to.

The water-insoluble fine particles (B) to be mixed with the latex of the conjugated diene polymer (A) have a specific gravity of 1.100 to 2.200 g / when made into an aqueous dispersion having a solid content concentration of 35% by weight. It may be cm ³ , but from the viewpoint of making the obtained dip polymer more excellent in flexibility, abrasion resistance, and wet grip, it is mixed with an aqueous dispersion having a solid content concentration of 35% by weight. specific gravity when the preferably those in the range of 1.150~1.500g / cm ^3, it is more preferably in the range of 1.200~1.400g / cm ^3. The water-insoluble fine particles (B) are not particularly limited as long as they are water-insoluble and have a specific gravity within the above range when prepared as an aqueous dispersion having a solid content concentration of 35% by weight. However, from the viewpoint that the wet grip property of the obtained dip molded product can be further improved, a polymer having a specific gravity of 1.100 to 2.200 g / cm ³ when prepared as an aqueous dispersion having a solid content concentration of 35% by weight. It is preferably particles, and more preferably polymer particles having a specific gravity of 1.100 to 1.500 g / cm ³ when prepared as an aqueous dispersion having a solid content concentration of 35% by weight. When water-insoluble fine particles (B) in the state of an aqueous dispersion are used as the water-insoluble fine particles (B), the solid content concentration is 35% by weight by a method of adding water or a method of concentration. The specific gravity of the aqueous dispersion itself, which is measured in a state where the solid content concentration is 35% by weight, may be within the above range.

As the polymer constituting the polymer particles, the polymer (b) having a specific gravity of 1.100 to 2.200 g / cm ³ when made into an aqueous dispersion having a solid content concentration of 35% by weight (hereinafter, appropriately "heavy"). The vinyl chloride resin is not particularly limited as long as it is "combined (b)"), but from the viewpoint that the obtained dip-molded product can be made more excellent in flexibility, abrasion resistance, and wet grip property. , PTFE resin, polyurethane resin (PU resin), PET resin, polycarbonate resin (PC resin) are preferable, and vinyl chloride resin is preferable from the viewpoint of high effect of improving wet grip property.

The vinyl chloride resin as the polymer (b) may be any of a vinyl chloride homopolymer and a copolymer of vinyl chloride and a monomer copolymerizable with vinyl chloride. When the vinyl chloride resin is a copolymer, the content of the vinyl chloride monomer unit in the vinyl chloride resin is preferably 50% by weight or more, more preferably 75% by weight or more, still more preferably 80% by weight. % Or more.

Examples of the monomer copolymerizable with vinyl chloride include α-olefin monomers such as ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene and 1-octene; styrene and α-methyl. Aromatic monomers such as styrene and vinylpyridine; α, β-ethylene unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid and silicic acid; ethyl (meth) acrylic acid, (meth) acrylic Esters of α, β-ethylenic unsaturated monocarboxylic acids such as butyl acid, 2-ethylhexyl (meth) acrylate; α, β-ethylenic unsaturated polycarboxylic acids such as maleic acid, fumaric acid and itaconic acid; Α, β-ethylenic unsaturated polycarboxylic acid monoesters such as monomethyl maleate, monoethyl maleate, monoethyl itaconate; dimethyl maleate, di-n-butyl fumarate, dimethyl itaconate, di-2-itaconate Α, β-ethylenic unsaturated polycarboxylic acid polyvalent ester such as ethylhexyl; vinyl ester monomer such as vinyl acetate and vinyl propionate; α, β-ethylenic unsaturated monocarboxylic acid such as acrylamide and methacrylic acid Amid; N-substituted maleimides; vinyl ether monomers such as vinyl methyl ether, vinyl ethyl ether, vinyl cetyl ether; vinylidene compounds such as vinylidene chloride; and the like, among these, vinyl ester monomers, α, The ester of β-ethylenic unsaturated monocarboxylic acid is preferable, and vinyl acetate and acrylic acid ester are more preferable.

The method for producing the latex of the vinyl chloride resin as the polymer (b) may be any method as long as the above-mentioned monomer can be polymerized, and is not particularly limited, but is known by radical polymerization, known emulsion polymerization, seed emulsion polymerization, and fine particles. Examples thereof include a method using suspension polymerization.

The K value of the vinyl chloride resin as the polymer (b) measured according to JIS K 7376-2 is preferably 50 to 95, more preferably 60 to 80.

Further, as the vinyl chloride resin as the polymer (b), it is preferable to use one that does not contain a plasticizer, whereby the wet grip property of the obtained dip molded product can be further enhanced. In this case, "does not contain a plasticizer" may be any aspect as long as the plasticizer is not substantially contained in the vinyl chloride resin particles. For example, the content of the plasticizer is 10 parts by weight. Anything may be suppressed as long as it is suppressed to ppm or less.

The glass transition temperature of the polymer (b) is preferably more than 10 ° C., more preferably 30 ° C. or higher, still more preferably 50 ° C. or higher, and particularly preferably 70 ° C. or higher. The upper limit of the glass transition temperature of the polymer (b) is not particularly limited, but is preferably 200 ° C. or lower, and more preferably 150 ° C. or lower. By setting the glass transition temperature of the polymer (b) in the above range, the flexibility, abrasion resistance, and wet grip property of the obtained dip molded product can be further improved. The method for setting the glass transition temperature of the polymer (b) in the above range is not particularly limited. For example, when a vinyl chloride resin is used as the polymer, vinyl chloride alone in the vinyl chloride resin is used. Examples thereof include a method in which the content of the polymer unit is preferably 50% by weight or more, more preferably 75% by weight or more.

Further, as the water-insoluble fine particles (B), if the particles have a specific gravity in the range of 1.100 to 2.200 g / cm ³ when prepared as an aqueous dispersion having a solid content concentration of 35% by weight, it is a polymer. The particles may be particles other than the particles, and examples of the particles other than the polymer particles include metal particles, mineral particles, and water-insoluble salts.

The weight average particle size of the water-insoluble fine particles (B) is preferably 0.05 to 50 μm, more preferably 0.05 to 10 μm, and further preferably 0.05 to 5 μm. By setting the weight average particle size of the water-insoluble fine particles (B) in the above range, the water-insoluble fine particles (B) can be added to the conjugated diene polymer (A) in the obtained dip molded product. It can be finely dispersed well, which can further enhance the wear resistance.

The content ratio of the conjugated diene polymer (A) and the water-insoluble fine particles (B) in the latex composition for dip molding of the present invention is "conjugated diene polymer (A): water-insoluble. The weight ratio of "fine particles (B)" is preferably 99: 1 to 10:90, more preferably 95: 5 to 50:50, still more preferably 90: 10 to 55:45, and particularly preferably 75:25. ~ 60:40. By setting the contents of the conjugated diene polymer (A) and the water-insoluble fine particles (B) in the above range, the abrasion resistance and wet grip property of the obtained dip molded product can be further enhanced.

Further, the latex composition for dip molding of the present invention is a water-soluble salt composed of a monovalent cation and a metal compound anion in addition to the latex of the conjugated diene polymer (A) and the water-insoluble fine particles (B). It further contains (C). According to the present invention, by incorporating such a water-soluble salt (C) in addition to the latex of the conjugated diene polymer (A) and the water-insoluble fine particles (B), the latex composition can be used for a long time. Even when stored, the components in the latex composition (for example, particles of the conjugated diene polymer (A), water-insoluble fine particles (B), etc.) can be suppressed from settling, and excellent storage stability can be achieved. Can have.

Examples of the monovalent cation constituting the water-soluble salt (C) include metal ions such as lithium ion, sodium ion, potassium ion, copper (I) ion and silver ion, and molecular ion such as ammonium ion. .. Among them, metal ions are preferable and sodium ions are more preferable from the viewpoint of further improving the water solubility of the water-soluble salt (C).

The anion constituting the water-soluble salt (C) may be a metal compound anion and is not particularly limited, but such an anion is preferably a metal acid ion which is an anion having at least a metal atom and an oxygen atom. .. Examples of the metal acid ion include aluminate ion, titanate ion, molybdate ion, tungstate ion, and polyacid ion such as polytungstate ion. Among the metal acid ions, aluminate ion, tungstate ion, and polytungstate ion are preferable, and aluminate ion and polytungstate ion are more preferable.

The water-soluble salt (C) may be any water-soluble salt composed of the above-mentioned cation and anion, and is not particularly limited. Among them, the monovalent cation is a sodium ion and the metal compound anion is a metal acid ion. Water-soluble salts are preferred. Examples of such water-soluble salts include sodium aluminate, sodium titanate, sodium molybdate, sodium tungstate, sodium polytungstate, and the like, among which sodium aluminate, sodium tungstate, and polytungstate. Sodium is preferable, sodium aluminate and sodium polytungstate are more preferable. In addition, these water-soluble salts may be used individually by 1 type, and may be used in combination of 2 or more types.

The water-soluble salt (C) has a specific gravity of 1.15 g / cm ³ or more, more preferably 1.20 to 1.80 g / cm ³ , and even more preferably 1.15 g / cm ³ or more when it is made into a 20% by weight aqueous solution. It is 1.25 to 1.70 g / cm ³ . By using a water-soluble salt (C) having a specific gravity in the above range when it is made into a 20% by weight aqueous solution, the effect of improving the storage stability of the latex composition for dip molding can be further enhanced. When the water-soluble salt (C) in an aqueous solution is used as the water-soluble salt (C), the solid content concentration is set to 20% by weight by a method of adding water or a method of concentration, and the solid content concentration is 20. The specific gravity of the aqueous solution itself, which is measured in the state of% by weight, may be within the above range.

The content of the water-soluble salt (C) in the latex composition for dip molding of the present invention is not particularly limited, but is preferably 0.5 to 15.0 parts by weight with respect to 100 parts by weight of the polymer component. , More preferably in the range of 1.0 to 10.0 parts by weight. Further, the range may be 1.0 to 10.0 parts by weight with respect to 100 parts by weight of the aqueous medium contained in the latex composition for dip molding. By setting the content of the water-soluble salt (C) in the above range, the storage stability of the latex composition for dip molding is further improved.

Further, in the latex composition for dip molding of the present invention, in addition to the latex of the conjugated diene polymer (A), the water-insoluble fine particles (B), and the water-soluble salt (C), a sulfur-based cross-linking agent is further added. It is preferable to contain it.

The sulfur-based cross-linking agent is not particularly limited, but sulfur such as powdered sulfur, sulfur flower, precipitated sulfur, colloidal sulfur, surface-treated sulfur, and insoluble sulfur; sulfur chloride, sulfur dichloride, morpholini disulfide, alkylphenol disulfide, and dibenzothia. Sulfur-containing compounds such as zirdisulfide, caprolactam disulfide, phosphorus-containing polysulfide, and high molecular weight polysulfides; sulfur-donating compounds such as tetramethylthium disulfide, selenium dimethyldithiocarbamate, 2- (4'-morpholinodithio) benzothiazole; Can be mentioned. These sulfur-based cross-linking agents may be used alone or in combination of two or more.

The content of the sulfur-based cross-linking agent is preferably 0.01 to 5 parts by weight, more preferably 0.05 to 3 parts by weight, and further, with respect to 100 parts by weight of the polymer component contained in the latex composition for dip molding. It is preferably 0.1 to 2 parts by weight.

Further, the latex composition for dip molding of the present invention preferably further contains a cross-linking accelerator (vulcanization accelerator) and zinc oxide in addition to the sulfur-based cross-linking agent.
The cross-linking accelerator (vulcanization accelerator) is not particularly limited, but for example, dithiocarbamines such as diethyldithiocarbamic acid, dibutyldithiocarbamic acid, di-2-ethylhexyldithiocarbamic acid, dicyclohexyldithiocarbamic acid, diphenyldithiocarbamic acid, and dibenzyldithiocarbamic acid. Acids and their zinc salts; 2-mercaptobenzothiazole, 2-mercaptobenzothiazole zinc, 2-mercaptothiazolin, dibenzothiazyl disulfide, 2- (2,4-dinitrophenylthio) benzothiazole, 2- (N, N-diethylthiocarbamoylthio) benzothiazole, 2- (2,6-dimethyl-4-morpholinothio) benzothiazole, 2- (4'-morpholinodithio) benzothiazole, 4-morpholinyl-2-benzothiadyl disulfide, Examples thereof include 1,3-bis (2-benzothiadyl mercaptomethyl) urea, and among these, zinc diethyldithiocarbamate, zinc dibutyldithiocarbamate, 2-mercaptobenzothiazole, and 2-mercaptobenzothiazole zinc are preferable. These cross-linking accelerators may be used alone or in combination of two or more.

The content of the cross-linking 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 component contained in the latex composition for dip molding. The zinc oxide content 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 component contained in the latex composition for dip molding. ..

Further, the latex composition for dip molding of the present invention may further contain a thickener. Examples of the thickener include vinyl compounds such as polyvinyl alcohol and polyvinylpyrrolidone; cellulose derivatives such as hydroxyethyl cellulose, hydroxypropyl cellulose and carboxymethyl cellulose and salts thereof; polycarboxylic acid compounds and sodium salts thereof; polyethylene glycol ether and the like. Polyoxyethylene derivatives; etc. Among these, cellulose derivatives and salts thereof are preferable, and carboxymethyl cellulose and sodium salts thereof are more preferable.
The content of the thickener is preferably 0.01 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the polymer component contained in the latex composition for dip molding.

The solid content concentration of the latex composition for dip molding of the present invention is preferably 20 to 65% by weight, more preferably 30 to 60% by weight, and further preferably 35 to 55% by weight. By setting the solid content concentration of the latex composition for dip molding within the above range, the transport efficiency of the latex composition for dip molding can be improved, and the viscosity of the latex composition for dip molding becomes appropriate. The handleability of the latex composition for dip molding is improved.

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 setting the pH of the latex composition for dip molding within the above range, mechanical stability can be improved, the generation of coarse agglomerates during transfer of the latex composition for dip molding can be suppressed, and dip molding can be performed. The viscosity of the latex composition for dip molding becomes appropriate, and the handleability of the latex composition for dip molding is improved.

The viscosity of the latex composition for dip molding of the present invention at 25 ° C. is preferably 2,000 to 100,000 mPa · s, more preferably 2,500 to 50,000 mPa · s, still more preferably 3,000 to 3,000 to s. It is 20,000 mPa · s. The viscosity of the latex composition for dip molding at 25 ° C. can be measured using, for example, a B-type viscometer under the conditions of 25 ° C. and a rotation speed of 6 rpm. Further, the viscosity of the latex composition for dip molding at 25 ° C. has, for example, a method for adjusting the concentration of the polymer component in the latex composition for dip molding and a thickening effect on the latex composition for dip molding. It can be adjusted by a method of adding a compound or the like.

Further, in the latex composition for dip molding of the present invention, a filler other than the water-insoluble fine particles (B), for example, a water-soluble filler or an aqueous dispersion having a solid content concentration of 35% by weight was used. A water-insoluble filler having an hourly specific gravity of less than 1.100 g / cm ³ or more than 2.200 g / cm ³ may be added, and examples of such a filler include polystyrene resin (PS resin) particles. Can be mentioned. Further, the latex composition for dip molding of the present invention includes, if necessary, an antiaging agent, an antioxidant, a preservative, an antibacterial agent, a wetting agent, a dispersant, a pigment, a dye, a reinforcing agent, a pH adjuster, etc. It is also possible to add a predetermined amount of various additives of.

The latex composition of the present invention can be prepared, for example, by mixing the above-mentioned components. The mixing order of each component is not particularly limited, but from the viewpoint of further enhancing the dispersibility of each component, after the latex of the conjugated diene polymer (A) and the water-insoluble fine particles (B) are mixed in advance, A method of adding and mixing the water-soluble salt (C) and each component to be blended as needed is preferable. The method for mixing the latex of the conjugated diene polymer (A) and the water-insoluble fine particles (B) is not particularly limited, but when the water-insoluble fine particles (B) are polymer particles, the method is not particularly limited. Prepare the latex of the polymer particles as the water-insoluble fine particles (B), and prepare the latex of the polymer particles as the water-insoluble fine particles (B) and the latex of the conjugated diene polymer (A). Examples thereof include a method of mixing in a latex state (latex blend) and a method of adding polymer particles as water-insoluble fine particles (B) as they are to the latex of a conjugated diene-based polymer (A) and mixing them. From the viewpoint of further enhancing dispersibility, a method of mixing the latex of the polymer particles as the water-insoluble fine particles (B) and the latex of the conjugated diene polymer (A) in a latex state is available. preferable. The water-soluble salt (C) is preferably mixed in the state of an aqueous solution.

<Dip molded body>
The dip molded product of the present invention is a molded product obtained by using the above-mentioned latex composition for dip molding of the present invention, and is usually dip-molded using the above-mentioned latex composition for dip molding of the present invention. Obtained by

The dip molded product of the present invention may be a film molded product made of the latex composition for dip molding obtained by immersing the dip molding mold in the latex composition for dip molding, or a base material. May be a laminate of a base material and a polymer layer composed of the latex composition for dip molding, which is obtained by immersing the above in the latex composition for dip molding. In the following, a case where the dip molded product of the present invention is a laminate of a base material and a polymer layer composed of a latex composition for dip molding will be described as an example, but the present invention has such an embodiment. It is not limited.

The base material is not particularly limited, but when the dip molded product of the present invention is used as a protective glove, a fiber base material can be preferably used. The fiber base material is not particularly limited, but for example, a single-fiber twisted yarn is used as the fiber, and a glove-shaped twisted yarn can be used by weaving the twisted yarn. The average thickness of the fiber substrate is preferably 50 to 3,000 μm, more preferably 100 to 2,000 μm.

The dip molded product of the present invention is produced, for example, by immersing a base material in a latex composition for dip molding to form a polymer layer composed of the latex composition for dip molding on the base material. Can be done. In this case, it is preferable to immerse the base material in the latex composition for dip molding with the base material covered with a molding mold having a desired shape in advance.

The molding mold for covering the base material is not particularly limited, but various materials such as porcelain, glass, metal, and plastic can be used. The shape of the molding mold may be a desired shape according to the shape of the final product. For example, when the dip molded product of the present invention is used as a protective glove, a molding mold for various gloves such as a molding mold having a shape from a wrist to a fingertip is used as a molding mold for covering a base material. Is preferable.

Further, before immersing the base material in the latex composition for dip molding, it is preferable to immerse the base material in the coagulant solution in advance and attach the coagulant solution to the base material. In this case, it is preferable to immerse the base material in the coagulant solution in a state where the base material is previously covered with a molding mold having a desired shape. Examples of the molding mold having a desired shape include those described above. Further, it is preferable to remove the solvent contained in the coagulant solution by adhering the coagulant solution to the base material, adhering the coagulant solution to the base material, and then drying. The drying temperature at this time 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.

Next, the base material to which the coagulant solution is attached is dipped in the latex composition for dip molding while being covered with the molding mold having a desired shape to coagulate the latex composition for dip molding. A polymer layer made of a latex composition for dip molding is attached onto the base material.

Then, after immersing the base material in the latex composition for dip molding, it is preferable to perform drying. The drying temperature at this time 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.

When a latex composition for dip molding containing a sulfur-based cross-linking agent is used, a latex composition for dip molding that has been aged in advance (also referred to as pre-vulcanization) may be used. ..

The temperature conditions for aging are not particularly limited, but are preferably 20 to 50 ° C. In addition, the time required for aging improves the wear resistance when the obtained dip molded product is used as protective gloves from the viewpoint of preventing peeling between the base material and the polymer layer made of the latex composition for dip molding. From the viewpoint of making the mixture, it is preferably 4 hours or more and 120 hours or less, and more preferably 24 hours or more and 72 hours or less.

Next, it is preferable to crosslink the polymer component contained in the latex composition for dip molding by heating the latex composition for dip molding adhered to the substrate.

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 to improve the productivity of the dip molded product, and the oxidative deterioration of the polymer component due to excessive heating can be suppressed. The physical properties of the dip molded product can be improved. The heating time for crosslinking may be appropriately selected according to the heating temperature, but is usually 5 to 120 minutes.

The polymer layer formed on the substrate is dipped in warm water at 20 to 80 ° C. for about 0.5 to 60 minutes to add weight to the dip molded product thus obtained. It is preferable to remove water-soluble impurities (emulsifier, water-soluble polymer, coagulant, etc.) from the coalesced layer. Such a treatment of immersing the polymer layer in warm water may be performed after the polymer components in the polymer layer are crosslinked, but the polymer layer can be used to remove water-soluble impurities more efficiently. It is preferable to carry out before cross-linking the polymer component of.

After being immersed in warm water, further drying may be 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 being immersed in the latex composition for dip molding described above.

Then, after forming a polymer layer on the base material with the base material covered with the molding mold as described above, the dip molded product is obtained by desorbing (or removing) from the molding mold. Can be done. As a desorption method, a method of manually peeling from the molding mold or a method of peeling by water pressure or compressed air pressure can be adopted.

Before or after the dip molded body is detached from the molding die, a heat treatment (post-crosslinking step) may be further performed at a temperature of 60 to 120 ° C. for 10 to 120 minutes. Further, after the dip molded product is detached from the molding mold, a surface treatment layer may be formed on the inner and / or outer surfaces of the dip molded product by chlorination treatment, coating treatment, or the like.

Since the molded product of the present invention is obtained by using the latex composition for dip molding of the present invention described above, it is excellent in flexibility, abrasion resistance, and wet grip, and is, for example, used for gloves. In particular, it can be suitably used for protective gloves. In the above description, the case where the dip molded product of the present invention is a laminate of a base material and a polymer layer composed of a latex composition for dip molding has been described as an example. However, as described above, the present invention has been described. The invention is not limited to such an embodiment, and a film molded product made of a dip molding latex composition obtained by immersing a dip molding mold in a dip molding latex composition can also be used. Of course it is possible.

Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited to these examples. Unless otherwise specified, the following "parts" are based on weight. Various physical properties were measured as follows.

<Specific gravity>
The specific gravity of the conjugated diene polymer (A) when the solid content concentration of the latex is 35% by weight and the specific gravity of the water-insoluble fine particles (B) when the solid content concentration is 35% by weight are , Calculated from the Baume degree of each latex and aqueous dispersion having a solid content concentration of 35% by weight measured by a Baume hydrometer.

<Storage stability>
A part of the dip molding composition is transferred to another container, left at room temperature (25 ° C.) for 1 week, and visually confirmed, so that the components contained in the dip molding latex composition are precipitated. The presence or absence of was confirmed, and the storage stability was evaluated. If there is no sedimentation of the components contained in the latex composition for dip molding, it can be said that the storage stability is excellent.

<Abrasion resistance>
The wear test was carried out using a Martindale type wear tester (product name "STM633", manufactured by SATRA) according to the method described in EN388. Specifically, the protective gloves (dip molded body) were repeatedly rubbed while applying a predetermined load to obtain the number of times of friction until breakage. It is divided into levels from LEVEL 0 to LEVEL 4 according to the number of frictions leading up to breakage, and the higher the level, the better the wear resistance.
LEVEL 4: 8,000 rotations or more LEVEL 3: 2,000 rotations or more and less than 8,000 rotations LEVEL 2: 500 rotations or more and less than 2,000 rotations LEVEL 1: 100 rotations or more and 500 rotations Less than rotation LEVEL 0: Rotation speed less than 100 rotations

<Flexibility>
A sample for measurement was obtained by cutting the palm portion of the protective glove (dip molded body) into a shape of 60 mm × 60 mm. Then, for the measurement sample, the indentation test apparatus 20 shown in FIG. 1 disclosed in International Publication No. 2018/174068 (the product name “HG1003-SL”, manufactured by Horiuchi Electric Co., Ltd. was used as the measurement unit) was used. Using, Young's modulus was measured according to the method disclosed in WO 2018/174068. The specific conditions are as shown below. At the time of measurement, a resin tape was attached to a portion of the surface opposite to the surface (measurement surface) on which the polymer layer of the measurement sample was formed, which corresponds to a plurality of suction holes of the suction table 30. The measurement was performed by pushing the spherical indenter from the rubber layer side while sucking by the suction table 30. Further, the measurement was performed on three points of the measurement sample of 60 mm × 60 mm, and the average value of the measurement results of the Young's modulus at the three points was obtained and used as the Young's modulus of each example. It can be judged that the higher the Young's modulus, the better the flexibility.
Spherical indenter: SUS spherical indenter with a diameter of 10 mm Pushing speed: 0.5 mm / s
Maximum load: 0.5N
Initial position of spherical indenter: -6 mm (height position from suction table 30 to 6 mm)

<Wet grip>
Conical metal molds weighing 1.0 kg, 2.0 kg, 3.0 kg, 4.0 kg, and 5.0 kg were prepared, and water was attached to these metal molds. Then, the worker was asked to wear protective gloves (dip molded body), and the metal mold to which water was attached was lifted in order from the lightest weight, and the maximum weight that could be lifted was calculated. .. The measurement was performed by the same operator. It can be judged that the larger the maximum weight that can be lifted, the better the wet grip property.

<Appearance>
The appearance including the presence or absence of cracks was evaluated by visually observing the polymer layer of the protective glove (dip molded product).

<Example 1>
(Preparation of aqueous dispersion of colloidal sulfur)
Colloidal sulfur (manufactured by Hosoi Chemical Industries, Ltd.) 1.0 part, dispersant (manufactured by Kao, trade name "Demor N") 0.5 parts, 5 wt% potassium hydroxide aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd.) 0. An aqueous dispersion of colloidal sulfur having a solid content concentration of 50% by weight was prepared by pulverizing and stirring 0015 parts and 1.0 part of water in a ball mill for 48 hours.

(Preparation of aqueous dispersion of zinc dibutyldithiocarbamate, aqueous dispersion of zinc oxide, and aqueous dispersion of titanium oxide)
Dibutyldithiocarbamic acid in the same manner as above, except that zinc dibutyldithiocarbamate (manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.), zinc oxide (manufactured by Shodo Kagaku Kogyo Co., Ltd.), and titanium oxide were used instead of colloidal sulfur. An aqueous dispersion of zinc, an aqueous dispersion of zinc oxide, and an aqueous dispersion of titanium oxide were prepared.

(Preparation of Latex of Nitrile Group-Containing Conjugated Diene Polymer (A-1))
In the polymerization reactor, 65 parts of 1,3-butadiene as a conjugated diene monomer, 30 parts of acrylonitrile as an α, β-ethylenic unsaturated nitrile monomer, and 5 methacrylic acid as an ethylenically unsaturated monocarboxylic acid monomer. , T-dodecyl mercaptan 0.4 parts, ion exchange water 132 parts, sodium dodecylbenzene sulfonate 3 parts, β-naphthalinsulfonic acid formarin condensate sodium salt 0.5 parts, potassium persulfate 0.3 parts and ethylenediamine tetra 0.05 part of sodium acetate was charged, the polymerization temperature was maintained at 30 to 40 ° C., polymerization was carried out, and the reaction was carried out until the polymerization conversion rate reached 94% to obtain a latex of a copolymer.
Then, after removing the unreacted monomer from the obtained latex of the copolymer, the pH and solid content of the latex of the copolymer are adjusted to obtain a nitrile having a solid content of 40% by weight and a pH of 8. A latex of a group-containing conjugated diene-based polymer (A-1) was obtained. The glass transition temperature (Tg) of the nitrile group-containing conjugated diene polymer (A-1) contained in the latex of the obtained nitrile group-containing conjugated diene polymer (A-1) was measured. It was 27 ° C. The weight average particle size of the particles of the nitrile group-containing conjugated diene polymer (A-1) constituting the latex of the nitrile group-containing conjugated diene polymer (A-1) is 110 nm, and the nitrile group-containing conjugated diene polymer (A-1) has a nitrile group-containing conjugate. The monomer composition of the diene polymer (A-1) was almost the same as the charging ratio. The specific gravity of the nitrile group-containing conjugated diene polymer (A-1) constituting the latex of the nitrile group-containing conjugated diene polymer (A-1) at a solid content concentration of 35% by weight is 0.990 g / cm. It was ³ .

(Preparation of latex composition for dip molding)
The latex of the nitrile group-containing conjugated diene polymer (A-1) obtained above and the latex of the vinyl chloride resin (B-1) are referred to as "nitrile group-containing conjugated diene polymer (A-1). : Vinyl chloride resin (B-1) ”was mixed so that the weight ratio was 70:30, and by adding 5% by weight of potassium hydroxide, the solid content concentration was 45% by weight and pH = 9.0. Latex composition was prepared. As the latex of the vinyl chloride resin (B-1), the glass transition temperature (Tg) of the vinyl chloride resin (B-1) is 82 ° C., the K value of the vinyl chloride resin (B-1) is 65, and vinyl chloride. The specific gravity of the resin (B-1) in an aqueous dispersion having a solid content concentration of 35% by weight is 1.20 g / cm ³ , and the weight average particle diameter of the particles of the vinyl chloride resin (B-1) is 1. The one having a thickness of 3 μm was used.

Then, with respect to 100 parts of the polymer component of the latex composition obtained above, 1.0 part of colloidal sulfur, 1.0 part of zinc dibutyldithiocarbamate, and 1.5 parts of zinc oxide in terms of solid content, respectively. And the aqueous dispersion of each compounding agent prepared above was added so as to have 3.0 parts of titanium oxide. When the aqueous dispersion of each compounding agent was added, a predetermined amount was slowly added while the latex composition was agitated. Then, after each compounding agent is uniformly mixed, a 30% by weight aqueous solution of sodium polytungstate (manufactured by MEASURE WORKS, specific gravity when made into a 20% by weight aqueous solution: 1.200 g / cm ³ ) is added to the polytungstate. Add in an amount of 3.0 parts in terms of sodium, and further add 0.5 parts of carboxymethyl cellulose (manufactured by Daicel Co., Ltd., trade name "Daicel2200") as a viscosity modifier to adjust the solid content concentration. A latex composition for dip molding having a solid content concentration of 38% by weight and a viscosity at 25 ° C. of 3,300 mPa · s was obtained. A part of the obtained latex composition for dip molding was transferred to another container and used for evaluation of storage stability. The results are shown in Table 1.

(Preparation of coagulant solution)
A coagulant solution was prepared by dissolving calcium nitrate as a coagulant in methanol at a ratio of 3.0% by weight.

(Manufacturing of protective gloves (dip molded body))
First, the latex composition for dip molding obtained above was aged (also referred to as pre-vulcanization) at a temperature of 30 ° C. for 48 hours. Next, a ceramic glove mold covered with a glove-shaped fiber base material (material: nylon, linear density: 300 denier, gauge number: 13 gauge, thickness: 0.8 mm) was added to the coagulant solution prepared above in 5 It was soaked for seconds, pulled out of the coagulant solution, and then dried at a temperature of 30 ° C. for 1 minute. Then, the ceramic glove mold is immersed in the above-mentioned latex composition for dip molding for 5 seconds, pulled up from the latex composition for dip molding, dried at a temperature of 30 ° C. for 30 minutes, and then dried at a temperature of 70 ° C., A polymer layer was formed on the fiber substrate by heating and cross-linking under the condition of 10 minutes. Then, the ceramic glove mold on which the polymer layer was formed was immersed in warm water at 60 ° C. for 90 seconds to elute water-soluble impurities from the polymer layer, and then dried at a temperature of 30 ° C. for 10 minutes. Further, the polymer in the polymer layer was crosslinked by performing a heat treatment at a temperature of 125 ° C. for 30 minutes. Next, the fiber base material on which the polymer layer was formed was peeled off from the ceramic glove mold to obtain a protective glove (dip molded product).
Then, using the obtained protective gloves (dip molded body), wear resistance, flexibility and wet grip were measured, and the appearance was evaluated. The results are shown in Table 1.

<Example 2>
Similar to Example 1, the solid content concentration was 36% by weight and the viscosity at 25 ° C. was 3,600 mPa, except that the amount of the sodium polytungstate aqueous solution used was changed to 5.0 parts in terms of sodium polytungstate. A latex composition for dip molding, which is s, was obtained. Then, using the obtained latex composition for dip molding, protective gloves (dip molded body) were obtained in the same manner as in Example 1, and evaluation was carried out in the same manner. The results are shown in Table 1.

<Example 3>
Instead of the sodium polytungstate aqueous solution, a 33 wt% aqueous solution of sodium aluminate (manufactured by Asada Chemical Industry Co., Ltd., specific gravity when made into a 20 wt% aqueous solution: 1.300 g / cm ³ ) was used in terms of sodium aluminate. A latex composition for dip molding having a solid content concentration of 38% by weight and a viscosity at 25 ° C. of 3,500 mPa · s was obtained in the same manner as in Example 1 except that the addition amount was 0 parts. Then, using the obtained latex composition for dip molding, protective gloves (dip molded body) were obtained in the same manner as in Example 1, and evaluation was carried out in the same manner. The results are shown in Table 1.

<Example 4>
The mixing ratio of the latex of the nitrile group-containing conjugated diene polymer (A-1) and the latex of the vinyl chloride resin (B-1) is described as "nitrile group-containing conjugated diene polymer (A-1): vinyl chloride. Dip molding having a solid content concentration of 37% by weight and a viscosity at 25 ° C. of 3,200 mPa · s in the same manner as in Example 1 except that the weight ratio of "resin (B-1)" was changed to 50:50. Latex composition for use was obtained. Then, using the obtained latex composition for dip molding, protective gloves (dip molded body) were obtained in the same manner as in Example 1, and evaluation was carried out in the same manner. The results are shown in Table 1.

<Comparative example 1>
A solid content concentration of 40% by weight and a viscosity of 3,000 mPa · s at 25 ° C. were obtained in the same manner as in Example 1 except that an aqueous sodium polytungstate solution was not added when obtaining the latex composition for dip molding. A latex composition for dip molding was obtained. Then, using the obtained latex composition for dip molding, protective gloves (dip molded body) were obtained in the same manner as in Example 1, and evaluation was carried out in the same manner. The results are shown in Table 1.

<Comparative example 2>
The mixing ratio of the latex of the nitrile group-containing conjugated diene polymer (A-1) and the latex of the vinyl chloride resin (B-1) is described as "nitrile group-containing conjugated diene polymer (A-1): vinyl chloride. Solid in the same manner as in Comparative Example 1, except that the weight ratio of "resin (B-1)" was changed to 50:50 and the amount of carboxymethyl cellulose used as a viscosity modifier was changed to 1.00 parts. A latex composition for dip molding having a partial concentration of 37% by weight and a viscosity at 25 ° C. of 3,000 mPa · s was obtained. Then, using the obtained latex composition for dip molding, protective gloves (dip molded body) were obtained in the same manner as in Example 1, and evaluation was carried out in the same manner. The results are shown in Table 1.

As shown in Table 1, the latex of the conjugated diene polymer (A) having a specific gravity of 0.950 to 1.050 g / cm ³ at a solid content concentration of 35% by weight and an aqueous dispersion having a solid content concentration of 35% by weight. Dip molding formed by mixing water-insoluble fine particles (B) having a specific gravity of 1.100 to 2.200 g / cm ³ and a water-soluble salt (C) composed of a monovalent cation and a metal compound anion. The latex composition for use was excellent in storage stability, and the dip molded product obtained by using the same was excellent in flexibility, abrasion resistance, and wet grip (Example). 1-4).
On the other hand, when a water-soluble salt composed of a monovalent cation and an anion of a metal compound was not contained, precipitation of the components contained in the latex composition for dip molding was observed when left at room temperature for one week. Yes, it was inferior in storage stability (Comparative Examples 1 and 2).

10 ... Measurement sample 20 ... Push-in test device 21 ... Measuring table 22 ... Support arm 23 ... Horizontal arm 24 ... Vertical movable mechanism for coarse movement 25 ... Vertical movable mechanism for fine movement 26 ... Stage 27 ... Load cell 28 ... Load shaft 29 ... Spherical indenter 30 … Suction stand

Claims (13)

When the latex of the conjugated diene polymer (A) having a specific gravity of 0.950 to 1.050 g / cm ³ when the solid content concentration is 35% by weight and an aqueous dispersion having a solid content concentration of 35% by weight are used. Dip molding formed by mixing water-insoluble fine particles (B) having a specific gravity of 1.100 to 2.200 g / cm ³ and a water-soluble salt (C) composed of a monovalent cation and a metal compound anion. For latex composition. The latex composition for dip molding according to claim 1, wherein the conjugated diene polymer (A) is a nitrile group-containing conjugated diene polymer. The latex composition for dip molding according to claim 1 or 2, wherein the fine particles (B) have a weight average particle diameter of 0.05 to 50 μm. The content ratio of the conjugated diene polymer (A) and the fine particles (B) is 95: 5 to 50:50 in terms of the weight ratio of "conjugated diene polymer (A): fine particles (B)". The latex composition for dip molding according to any one of claims 1 to 3. The invention according to any one of claims 1 to 4, wherein the fine particles (B) are polymer particles having a specific gravity of 1.100 to 1.500 g / cm ³ when made into an aqueous dispersion having a solid content concentration of 35% by weight. Latex composition for dip molding. The latex composition for dip molding according to claim 5, wherein the polymer particles are particles of a vinyl chloride resin. The latex composition for dip molding according to claim 6, wherein the particles of the vinyl chloride resin do not contain a plasticizer. The latex composition for dip molding according to any one of claims 1 to 7, further containing a sulfur-based cross-linking agent. The latex composition for dip molding according to any one of claims 1 to 8, wherein the water-soluble salt (C) has a specific gravity of 1.15 g / cm ³ or more when made into a 20% by weight aqueous solution. The latex composition for dip molding according to any one of claims 1 to 9, wherein the monovalent cation is a sodium ion and the metal compound anion is a metal acid ion. The latex composition for dip molding according to any one of claims 1 to 10, wherein the water-soluble salt (C) is at least one selected from sodium aluminate, sodium titanate, sodium molybdate, and sodium tungstate. .. A dip molded product using the latex composition for dip molding according to any one of claims 1 to 11. A dip molded product obtained by immersing the latex composition for dip molding according to any one of claims 1 to 11 in a base material.

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