JP6028362B2 - DIP MOLDING COMPOSITION AND DIP MOLDED ARTICLE - Google Patents

Description

  The present invention relates to a dip-molding composition and a dip-molded product. More specifically, the present invention relates to a dip-molded product that is suitable for applications such as gloves, is excellent in bending fatigue resistance and mechanical strength, hardly discolors, and has little odor, and a dip-molding composition for obtaining the dip-molded product.

  Rubber gloves are widely used for housework, various industrial purposes such as food industry and electronic component manufacturing industry, and medical use. However, these various types of rubber gloves are torn during work (does not have sufficient tensile strength), and if they are worn and moved while the work is continued, microcracks are generated in the crotch part of the finger. (Which is inferior in bending fatigue resistance) may occur.

  Therefore, Patent Document 1 discloses dip molding from a dip molding composition containing a specific amount of an acrylonitrile-butadiene copolymer latex containing a carboxyl group, a small amount of zinc oxide, a relatively large amount of sulfur and a vulcanization accelerator. A rubber glove is disclosed. However, when such a glove is worn and the operation is continued, the glove itself may be colored to significantly reduce its commercial value, and the odor due to residual sulfur may be a problem.

Japanese translation of PCT publication No. 2002-527632

  An object of the present invention is to provide a dip-molding composition that is suitable for applications such as gloves, is excellent in bending fatigue resistance and mechanical strength, hardly discolors, and can give a dip-molded product with little odor. To do. Another object of the present invention is to provide a dip-molded product obtained by dip-molding such a dip-molding composition.

  As a result of diligent research to solve the above problems, the present inventors have found that a latex of a carboxyl group-containing conjugated diene rubber having a specific insoluble content of methyl ethyl ketone, and a monomer unit having a carbon-nitrogen double bond in the molecule It has been found that the above object can be achieved by a dip-molding composition containing a polymer containing, and the present invention has been completed.

That is, according to the present invention,
A latex of carboxyl group-containing conjugated diene rubber (A) having a methyl ethyl ketone insoluble content of 10 to 70% by weight, and a polymer (B) containing a monomer unit having a carbon-nitrogen double bond in the molecule; A dip-forming composition is provided.
The monomer unit having a carbon-nitrogen double bond in the molecule is preferably a monomer unit having an oxazoline group.
The monomer unit having a carbon-nitrogen double bond in the molecule is preferably a monomer unit having a carbodiimide structure.

The latex of the carboxyl group-containing conjugated diene rubber (A) comprises 30 to 89.5% by weight of a conjugated diene monomer, 10 to 50% by weight of an ethylenically unsaturated nitrile monomer, and an ethylenically unsaturated acid monomer. Copolymers obtained by polymerizing a monomer mixture containing 0.5 to 20% by weight and other ethylenically unsaturated monomers copolymerizable with these monomers and 0 to 20% by weight. A polymer latex is preferred.
Moreover, according to the present invention, a dip-molded product obtained by dip-molding the dip-molding composition described above is provided, and the dip-molded product is preferably a glove.

  According to the present invention, it is possible to provide a dip-molding composition that is suitable for applications such as gloves, has excellent bending fatigue resistance and mechanical strength, is resistant to discoloration, and can give a dip-molded product with little odor. it can. Moreover, according to the present invention, a dip-molded product obtained by dip-molding such a dip-molding composition can be provided.

  The dip molding composition of the present invention comprises a latex of carboxyl group-containing conjugated diene rubber (A) having a methylethylketone insoluble content of 10 to 70% by weight, and a monomer having a carbon-nitrogen double bond in the molecule. The polymer (B) containing a unit is included.

Latex of carboxyl group-containing conjugated diene rubber (A) The latex of carboxyl group-containing conjugated diene rubber (A) used in the dip molding composition of the present invention is obtained by copolymerizing a conjugated diene monomer and an ethylenically unsaturated acid monomer. The latex of the copolymer obtained in this way has a methylethylketone insoluble content of the carboxyl group-containing conjugated diene rubber (A) of 10 to 70% by weight.
In addition, the methyl ethyl ketone insoluble matter of the carboxyl group-containing conjugated diene rubber (A) is preferably 40 to 70% by weight.

  Examples of the conjugated diene monomer include 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. 1,3-butadiene and isoprene are more preferable, and 1,3-butadiene is particularly preferable. The conjugated diene monomer may be used alone or in combination of two or more.

  The amount of the conjugated diene monomer used is preferably 30 to 89.5 parts by weight (30 to 89.5% by weight), more preferably 40 to 84% by weight based on 100 parts by weight of the total monomers used for the polymerization. Parts (40 to 84% by weight), more preferably 50 to 78 parts by weight (50 to 78% by weight). If this amount is too small, the resulting dip-molded product is inferior in texture, whereas if it is too much, the tensile strength tends to be inferior.

  The ethylenically unsaturated acid monomer is not particularly limited, and examples thereof include an ethylenically unsaturated monomer containing an acidic group such as a carboxyl group, a sulfonic acid group, and an acid anhydride group.

Specific examples of the ethylenically unsaturated acid monomer having a carboxyl group include ethylenically unsaturated monocarboxylic acid monomers such as acrylic acid and methacrylic acid; ethylenically unsaturated monomers such as itaconic acid, maleic acid, and fumaric acid. A polyvalent carboxylic acid monomer; an ethylenically unsaturated polyvalent carboxylic acid partial ester monomer such as monobutyl fumarate, monobutyl maleate, mono-2-hydroxypropyl maleate;
Specific examples of the ethylenically unsaturated acid monomer containing a sulfonic acid group include styrene sulfonic acid.
Specific examples of the ethylenically unsaturated acid monomer containing an acid anhydride group include ethylenically unsaturated polyvalent carboxylic acid anhydrides such as maleic anhydride and citraconic anhydride.

  Among these ethylenically unsaturated acid monomers, the ethylenically unsaturated monocarboxylic acid monomer is preferable, acrylic acid and methacrylic acid are more preferable, and methacrylic acid because the effects of the present invention become more remarkable. Is particularly preferred.

  These ethylenically unsaturated acid monomers can also be used as alkali metal salts or ammonium salts. In addition, these ethylenically unsaturated acid monomers may be used alone or in combination of two or more.

  The amount of the ethylenically unsaturated acid monomer used is preferably 0.5 to 20 parts by weight (0.5 to 20% by weight), preferably 1 to 15 parts by weight, based on 100 parts by weight of all monomers used for polymerization. Part (1 to 15% by weight) is more preferred, and 2 to 10 parts by weight (2 to 10% by weight) is particularly preferred. When this amount is too small, the resulting dip-molded product is inferior in tensile strength, and conversely, when it is too large, the texture and the durability of the adhesive state are inferior.

  The latex of the carboxyl group-containing conjugated diene rubber (A) used in the dip molding composition of the present invention is preferably one obtained by further copolymerizing an ethylenically unsaturated nitrile monomer from the viewpoint of improving the tensile strength.

  Specific examples of the ethylenically unsaturated nitrile monomer include acrylonitrile, methacrylonitrile, fumaronitrile, α-chloroacrylonitrile, α-cyanoethylacrylonitrile and the like. Acrylonitrile and methacrylonitrile are preferable, and acrylonitrile is particularly preferable. These ethylenically unsaturated nitrile monomers may be used alone or in combination of two or more.

  The amount of the ethylenically unsaturated nitrile monomer used is preferably 10 to 50 parts by weight (10 to 50% by weight), more preferably 15 to 45 parts by weight, based on 100 parts by weight of all monomers used for the polymerization. (15 to 45% by weight), particularly preferably 20 to 40 parts by weight (20 to 40% by weight). If this amount is too small, the resulting dip-molded product may be inferior in tensile strength, and conversely if too large, the texture may be inferior.

In addition, the carboxyl group-containing conjugated diene rubber (A) latex used in the dip-molding composition of the present invention is not limited to other ethylenic copolymers that can be copolymerized with the above-mentioned monomers as long as the effects of the present invention are not impaired. Saturated monomers may be copolymerized.
Examples of such other copolymerizable ethylenically unsaturated monomers include aromatic vinyl monomers, α, β-ethylenically unsaturated monocarboxylic acid ester monomers, and α, β-ethylenic monomers. Unsaturated monocarboxylic amide, vinyl acetate, vinyl pyrrolidone, vinyl pyridine and the like can be mentioned. The amount of such other copolymerizable monomers used is preferably 0 to 20 parts by weight (0 to 20% by weight), more preferably 0 with respect to 100 parts by weight of the total monomers used for the polymerization. -10 parts by weight (0-10% by weight), particularly preferably 0 parts by weight (0% by weight).

Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, monochlorostyrene, vinyltoluene and the like.
Examples of the α, β-ethylenically unsaturated monocarboxylic acid ester monomer include methyl acrylate, methyl methacrylate, ethyl acrylate, butyl acrylate, β-hydroxyethyl acrylate, β-hydroxypropyl acrylate, Examples include β-hydroxyethyl methacrylate, glycidyl acrylate, glycidyl methacrylate, N, N-dimethylaminoethyl (meth) acrylate, and the like.
Examples of the α, β-ethylenically unsaturated monocarboxylic acid amide monomer include (meth) acrylamide, N-methylol (meth) acrylamide and the like.
These monomers may be used alone or in combination of two or more.

  The latex of the carboxyl group-containing conjugated diene rubber (A) used in the present invention is a copolymer latex obtained by polymerizing a monomer mixture containing the above-mentioned monomers. What is obtained is preferred. A conventionally well-known method can be employ | adopted as an emulsion polymerization method.

  In order to emulsion-polymerize the mixture of the above monomers, commonly used polymerization auxiliary materials such as an emulsifier, a polymerization initiator, and a molecular weight modifier can be used. The method for adding these polymerization auxiliary materials is not particularly limited, and any method such as an initial batch addition method, a divided addition method, or a continuous addition method may be used.

  The emulsifier is not particularly limited, and an anionic emulsifier, a nonionic emulsifier, a cationic emulsifier, and the like can be used.

Specific examples of anionic emulsifiers include fatty acid salts such as myristic acid, palmitic acid, oleic acid, and linolenic acid; alkylbenzene sulfonates such as sodium dodecylbenzenesulfonate; higher alcohol sulfate salts; alkylsulfosuccinates; etc. Can be mentioned. Examples of the salt in these anionic emulsifiers include alkali metal salts and ammonium salts.
Specific examples of the nonionic emulsifier include polyoxyethylene alkyl ether, polyoxyethylene alkylphenol ether, polyoxyethylene alkyl ester, polyoxyethylene sorbitan alkyl ester and the like.
Specific examples of the cationic emulsifier include alkyltrimethylammonium chloride, dialkylammonium chloride, benzylammonium chloride and the like.
The usage-amount of an emulsifier is 0.5-10 weight part normally with respect to 100 weight part of all the monomers to be used, Preferably it is 1-8 weight part, More preferably, it is 2-5 weight part.

The polymerization initiator is not particularly limited, and examples thereof include inorganic peroxides such as sodium persulfate, potassium persulfate, ammonium persulfate, potassium perphosphate, and hydrogen peroxide; 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 Organic peroxides such as peroxide and t-butylperoxyisobutyrate; azo compounds such as azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, azobiscyclohexanecarbonitrile, methyl azobisisobutyrate; etc. Cite It is possible. These polymerization initiators can be used alone or in combination of two or more. In addition, the peroxide can be used as a redox polymerization initiator in combination with a reducing agent such as sodium bisulfite. As the polymerization initiator, an inorganic or organic peroxide is preferable, an inorganic peroxide is more preferable, and a persulfate can be particularly preferably used.
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 with respect to 100 parts by weight of the total monomers used.

In carrying out the emulsion polymerization, it is preferable to use a molecular weight adjusting agent in order to adjust the methyl ethyl ketone insoluble matter of the carboxyl group-containing conjugated diene rubber (A). Examples of the molecular weight modifier include mercaptans such as n-butyl mercaptan and t-dodecyl mercaptan, sulfides such as tetraethylthiuram sulfide and dibentamethylenethiuram hexasulfide, α-methylstyrene dimer, carbon tetrachloride and the like. Can be mentioned. Among these, mercaptans are preferable, and t-dodecyl mercaptan is more preferable. These can be used alone or in combination of two or more.
The amount of the molecular weight modifier used may be appropriately determined so that the methylethylketone insoluble content of the carboxyl group-containing conjugated diene rubber (A) is within a desired range, but is preferably based on 100 parts by weight of the total monomers used. 0.3 to 0.8 part by weight.

  The amount of water used for emulsion polymerization is preferably 80 to 600 parts by weight, particularly preferably 100 to 200 parts by weight, based on 100 parts by weight of all monomers used.

Examples of the monomer addition method include a method of adding the monomers used in the reaction vessel all at once, a method of adding continuously or intermittently as the polymerization proceeds, and a part of the monomer is added. And a method in which the remaining monomer is continuously or intermittently added and polymerized, and any method may be employed. When the monomers are mixed and added continuously or intermittently, the composition of the mixture may be constant or may be changed.
Each monomer may be added to the reaction vessel after previously mixing various monomers to be used, or may be added separately to the reaction vessel.

  Furthermore, polymerization auxiliary materials such as a chelating agent, a dispersant, a pH adjuster, a deoxidizing agent, and a particle size adjuster can be used as necessary, and these are not particularly limited in terms of type and amount used.

  The polymerization temperature for emulsion polymerization is usually 0 to 95 ° C. In particular, the polymerization reaction is preferably performed at a temperature of 30 to 50 ° C., the polymerization conversion rate is preferably 90% by weight or more, and the methyl ethyl ketone insoluble content of the carboxyl group-containing conjugated diene rubber (A) is preferably adjusted to a predetermined amount. The polymerization time is about 5 to 40 hours.

As described above, the monomer is emulsion-polymerized, and when the predetermined polymerization conversion rate is reached, the polymerization reaction is stopped by cooling the polymerization system or adding a polymerization terminator.
The polymerization conversion rate when stopping the polymerization reaction is preferably 90% by weight or more, more preferably 93% by weight or more.

The polymerization terminator is not particularly limited as long as it is usually used in emulsion polymerization. Specific examples thereof include hydroxylamine, hydroxyamine sulfate, diethylhydroxyamine, hydroxyaminesulfonic acid and alkali metals thereof. Hydroxyamine compounds such as salts; sodium dimethyldithiocarbamate; hydroquinone derivatives; catechol derivatives; aromatic hydroxydithiocarboxylic acids such as hydroxydimethylbenzenethiocarboxylic acid, hydroxydiethylbenzenedithiocarboxylic acid, hydroxydibutylbenzenedithiocarboxylic acid, and alkali metal salts thereof Aromatic hydroxydithiocarboxylic acid compounds such as;
Although the usage-amount of a polymerization terminator is not specifically limited, Usually, it is 0.05-2 weight part with respect to 100 weight part of all the monomers to be used.

  After stopping the polymerization reaction, the unreacted monomer is removed if desired, and the latex of the carboxyl group-containing conjugated diene rubber (A) is obtained by adjusting the solid content concentration and pH.

  The latex of the carboxyl group-containing conjugated diene rubber (A) used in the present invention may be appropriately added with an anti-aging agent, an antiseptic, an antibacterial agent, a dispersant, an ultraviolet absorber, a pH adjuster, and the like as necessary. .

  The number average particle diameter of the latex of the carboxyl group-containing conjugated diene rubber (A) used in the present invention is preferably 60 to 300 nm, more preferably 80 to 150 nm. In addition, this particle diameter can be adjusted to a desired value by a method of adjusting the usage-amount of an emulsifier and a polymerization initiator.

Polymer (B) containing a monomer unit having a carbon-nitrogen double bond in the molecule
The dip molding composition of the present invention includes a polymer (B) containing a monomer unit having a carbon-nitrogen double bond in the molecule. In addition, as a monomer which forms the monomer unit which has a carbon-nitrogen double bond in a molecule | numerator, a C5-C20 compound is preferable.

  The monomer that forms a monomer unit having a carbon-nitrogen double bond in the molecule is preferably a monomer having an oxazoline group or a monomer having a carbodiimide structure. A compound having a heavy bond and a compound having a carbodiimide structure and a carbon-carbon double bond are more preferable, a compound having 5 to 20 carbon atoms having an oxazoline group and a carbon-carbon double bond, and a carbodiimide structure and a carbon-carbon double bond. A compound having 5 to 20 carbon atoms having a carbon number of 5 to 20 is more preferable, and a compound having 5 to 20 carbon atoms having an oxazoline group and a carbon-carbon double bond is particularly preferable.

  Specific examples of the compound having an oxazoline group and a carbon-carbon double bond include 2-vinyl-2-oxazoline, 4-methyl-2-vinyl-2-oxazoline, and 4,4-dimethyl-2-vinyl-2- Oxazolines having 5 to 20 carbon atoms such as oxazoline, 4-ethyl-2-vinyl-2-oxazoline, 4-propyl-2-vinyl-2-oxazoline, 4-methoxy-2-vinyl-2-oxazoline 2-propenyl-2-oxazoline, 4-methyl-2-propenyl-2-oxazoline, 4,4-dimethyl-2-propenyl-2-oxazoline, 4-ethyl-2-propenyl-2-oxazoline, 4-propyl Propene having 5 to 20 carbon atoms such as 2-propenyl-2-oxazoline and 4-methoxy-2-propenyl-2-oxazoline Oxazoline having Le group; and the like.

  Specific examples of the compound having a carbodiimide structure and a carbon-carbon double bond include 1-vinyl-3-ethyl-carbodiimide, 1-vinyl-3-propyl-carbodiimide, 1-vinyl-3-methoxypropyl-carbodiimide, 1 A carbodiimide having a vinyl group having 5 to 20 carbon atoms such as vinyl-3-isobutyl-carbodiimide; 1-propenyl-3-ethyl-carbodiimide, 1-propenyl-3-propyl-carbodiimide, 1-propenyl-3-methoxypropyl -Carbodiimide having a propenyl group having 5 to 20 carbon atoms such as carbodiimide, 1-propenyl-3-isobutyl-carbodiimide; and the like.

  The polymer (B) containing a monomer unit having a carbon-nitrogen double bond in the molecule is composed of a monomer having a carbon-nitrogen double bond in the molecule and other monomers capable of copolymerization. It preferably contains a unit of a monomer.

  Other monomers that form units of monomers include aromatic vinyl monomers such as styrene, α-methylstyrene, monochlorostyrene, vinyltoluene; methyl acrylate, methyl methacrylate, ethyl acrylate, acrylic Α, β-ethylenically unsaturated monocarboxylic acid ester monomers such as butyl acid, β-hydroxyethyl acrylate, β-hydroxypropyl acrylate, β-hydroxyethyl methacrylate, glycidyl acrylate and glycidyl methacrylate; Styrene, butyl acrylate and methyl methacrylate are particularly preferred.

The content of the monomer unit having a carbon-nitrogen double bond in the molecule in the polymer (B) is preferable with respect to all the monomer units since the effect of the present invention becomes more remarkable. Is from 5 to 80 mol%, more preferably from 10 to 70 mol%, particularly preferably from 15 to 60 mol%.
Further, the content of the other monomer units in the polymer (B) is preferably 20 to 95 mol%, more preferably 30 to 90 mol%, particularly preferably based on all monomer units. 40 to 85 mol%.

  The weight average molecular weight of the polymer (B) is preferably 500 to 1,000,000, more preferably 1,000 to 500,000.

The polymer (B) may be produced by radical polymerization of the above monomers by a conventionally known emulsion polymerization method or the like, or a commercially available product may be purchased and used.
The conditions and methods for emulsion polymerization are the same as in the case of the latex of the carboxyl group-containing conjugated diene rubber (A). From the latex of the polymer (B) thus obtained, coagulation, Filtration and drying can be performed to obtain the polymer (B).

Dip-molding composition The dip-molding composition of the present invention comprises a carboxyl group-containing conjugated diene rubber (A) latex having a methylethylketone insoluble content of 10 to 70% by weight, and a carbon-nitrogen double bond in the molecule. A polymer (B) containing a monomer unit having a bond.

The amount of the polymer (B) used in the dip molding composition of the present invention is such that the effects of the present invention become more prominent, so that the carboxyl group-containing conjugated diene rubber (A) in the dip molding composition is 100 parts by weight. The amount is preferably 0.01 to 20 parts by weight, more preferably 0.1 to 10 parts by weight.
The polymer (B) undergoes a crosslinking reaction with the carboxyl group-containing conjugated diene rubber (A) to form a crosslinked structure.

  The dip molding composition of the present invention may contain a vulcanizing agent, a vulcanization accelerator and zinc oxide. From the viewpoint of improving odor due to residual sulfur, the vulcanizing agent, the vulcanization accelerator and the oxidation It is preferable not to mix zinc.

In the dip molding composition of the present invention, a pH adjuster, which is usually blended if desired,
You may mix | blend a thickener, anti-aging agent, a dispersing agent, a pigment, a filler, a softening agent, etc.
Further, other latexes such as natural rubber latex and isoprene rubber latex can be used in combination as long as the object of the present invention is not impaired.

The solid content concentration of the dip molding composition of the present invention is preferably 10 to 40% by weight, more preferably 15 to 35% by weight.
The pH of the dip molding composition of the present invention is usually 8.5 to 12, preferably 9 to 11.

Dip-molded product The dip-molded product of the present invention is formed by dip-molding the dip-molding composition of the present invention.
As the dip molding method, a normal method may be employed, and examples thereof include a direct dipping method, an anode adhesion dipping method, and a teag adhesion dipping method. Of these, the anode coagulation dipping method is preferred because a dip-molded product having a uniform thickness is easily obtained.

  In the case of the anode adhesion dipping method, for example, a dip-molding mold is immersed in a coagulant solution, the coagulant is attached to the surface of the mold, and then the dip-molding composition is immersed in the dip-molding composition, A dip-formed layer is formed on the substrate.

Examples of the coagulant include metal halides such as barium chloride, calcium chloride, magnesium chloride, zinc chloride, and aluminum chloride; nitrates such as barium nitrate, calcium nitrate, and zinc nitrate; acetic acid such as barium acetate, calcium acetate, and zinc acetate. Salts; sulfates such as calcium sulfate, magnesium sulfate, and aluminum sulfate; and the like. Of these, calcium chloride and calcium nitrate are preferable.
The coagulant is usually used as a solution of water, alcohol, or a mixture thereof. The coagulant concentration is usually 5 to 50% by weight, preferably 10 to 30% by weight.

  The obtained dip-formed layer is usually subjected to heat treatment and vulcanized. Before performing the heat treatment, it may be immersed in water, preferably 30 to 70 ° C. for about 1 to 60 minutes, to remove water-soluble impurities (for example, excess emulsifier and coagulant). This operation may be performed after heat-treating the dip-molded layer, but is preferably performed before the heat treatment from the viewpoint that water-soluble impurities can be more efficiently removed.

  The dip-molded layer thus obtained is subjected to a heat treatment at a temperature of 100 to 150 ° C. for 10 to 120 minutes for crosslinking. As a heating method, an external heating method using infrared rays or hot air or an internal heating method using high frequency can be employed. Of these, heating with hot air is preferred.

  A dip-molded product is obtained by detaching the crosslinked dip-molding layer from the dip-molding die. As the desorption method, it is possible to adopt a method of peeling from the mold by hand, or peeling by water pressure or compressed air pressure.

  In addition, after desorption, you may heat-process for 10 to 120 minutes at the temperature of 60-120 degreeC.

  The dip-molded product may further have a surface treatment layer formed on the inner and / or outer surface thereof.

  The dip-formed product of the present invention can have a thickness of about 0.03 to about 3 mm, and can be suitably used for a thin product having a thickness of 0.05 to 0.3 mm. Specifically, medical supplies such as nipples for baby bottles, syringes, conduits, and water pillows; toys and exercise equipment such as balloons, dolls, and balls; industrial articles such as pressure forming bags and gas storage bags; Examples include household, agricultural, fishery and industrial gloves; finger sack. It is particularly suitable for thin surgical gloves.

  The present invention will be described more specifically with reference to the following examples. Unless otherwise specified, “part” and “%” are based on weight.

40 g of carboxyl group-containing conjugated diene rubber latex adjusted to pH 8 with aqueous methylethylketone insoluble ammonia solution and adjusted to a solid content concentration of 30% with ion-exchanged water is applied to a framed glass plate (16 cm long, 23 cm wide). Then, the film was allowed to stand at 23 ° C. and a relative humidity of 50% for 5 days to obtain a film having a thickness of 0.2 to 0.3 mm. This film is subdivided into a size of 5 mm in length and 5 mm in width to prepare a sample. After weighing approximately 0.2 g of the sample (P), it is immersed in a beaker containing 80 ml of methyl ethyl ketone in a 80 mesh stainless steel wire cage, placed at 23 ° C. for 24 hours, and then taken out. Next, the insoluble matter swollen with methyl ethyl ketone was placed in a room at 23 ° C. for 1 hour and then heated at 105 ° C. for 1 hour, and the weight (Q) of the insoluble matter in the dry state was measured. Then, the methyl ethyl ketone insoluble content (sometimes referred to as “MEK insoluble content”) was determined by the following formula.
MEK insoluble content = (Q / P) × 100 (% by weight)

300% tensile stress, tensile strength, and elongation (preparation of test pieces for evaluating physical properties of dip-formed products)
According to ASTM D-412, a rubber glove-shaped dip-molded product was punched with a dumbbell (Die-C) to obtain a test piece.
Subsequently, this test piece was pulled at a tensile speed of 500 mm / min using a Tensilon universal testing machine, the tensile stress (MPa) when the elongation was 300%, the tensile strength (MPa) at break, and the Elongation (%) was measured.
The smaller the 300% tensile stress, the better the texture.

Ten test subjects wore rubber gloves (dip-molded articles) obtained with bending fatigue resistance, and performed a light operation of keyboard input operation. Every time 10 minutes have passed since the work was started, the crotch portion of the finger of the rubber glove was observed to confirm the presence or absence of microcracks. In each test, the time until a microcrack occurs in a rubber glove is measured, and 8 data (data of 8 persons) excluding the shortest and longest time are shown as arithmetic average values. This wearing test was conducted up to 180 minutes. It shows that it is excellent in bending fatigue resistance, so that this time is long.

Copper ion discoloration The obtained rubber glove (dip-molded product) was immersed in a 3% aqueous copper sulfate solution for 30 seconds, and the degree of discoloration of the rubber glove after 1 hour was visually determined, and is shown as follows.
Rubber gloves are not discolored: ○
Discoloration of rubber gloves can be seen: ×
In addition, the rubber glove which discoloration is recognized by the said test shows that a rubber glove itself is easy to color when it wears and works for a long time.

Production Example 1 ( Production of latex of carboxyl group-containing conjugated diene rubber (a1))
In a polymerization reactor, 30 parts of acrylonitrile, 65 parts of 1,3-butadiene, 5 parts of methacrylic acid, 0.5 part of t-dodecyl mercaptan, 132 parts of ion-exchanged water, 3 parts of sodium dodecylbenzenesulfonate, β-naphthalenesulfonic acid Formalin condensate sodium salt 0.5 part, potassium persulfate 0.3 part and ethylenediaminetetraacetic acid sodium salt 0.05 part were charged, and the polymerization temperature was maintained at 37 ° C. to initiate the polymerization. When the polymerization conversion rate reached 60%, 0.2 part of t-dodecyl mercaptan was added, the polymerization temperature was raised to 40 ° C., and the reaction was continued until the polymerization conversion rate reached 94%. Thereafter, 0.1 part of sodium dimethyldithiocarbamate was added as a polymerization terminator to terminate the polymerization reaction. After removing unreacted monomers from the obtained copolymer latex, the pH and solid content concentration of the copolymer latex were adjusted, and the carboxyl group-containing conjugated diene rubber (a1) having a solid content concentration of 40% and pH 8 was adjusted. Latex (MEK insoluble content is 63% by weight) was obtained.

Production Example 2 ( Production of latex of carboxyl group-containing conjugated diene rubber (c1))
The t-dodecyl mercaptan at the start of the polymerization was changed from 0.5 part to 0.1 part, and the t-dodecyl mercaptan added when the polymerization conversion reached 60% was changed from 0.2 part to 0.1 part. Except for the change, polymerization was carried out in the same manner as in Production Example 1 to obtain a latex of carboxyl group-containing conjugated diene rubber (c1) having a solid content concentration of 40% and pH 8 (MEK insoluble content was 78% by weight). .

Example 1
To the latex of the carboxyl group-containing conjugated diene rubber (a1) obtained in Production Example 1, a polymer having an oxazoline group (trade name “Epocross WS-700”, manufactured by Nippon Shokubai Co., Ltd., theoretical oxazoline number 220, and theoretical oxazoline number and Means the weight (g) of a polymer containing 1 mol of an oxazoline group.), And then an aqueous ammonia solution and ion-exchanged water are further added to adjust the pH to 10.0 and the solid content concentration to 30%. After that, the mixture was stirred and dispersed uniformly at a temperature of 20 ° C. for 24 hours to obtain a dip molding composition.
In this example, the polymer having an oxazoline group was added to 0.2 part with respect to 100 parts of the carboxyl group-containing conjugated diene rubber (a1) in the latex of the carboxyl group-containing conjugated diene rubber (a1). did.

Next, using the dip molding composition obtained above, a rubber glove (dip molded product) was produced by the following method.
A coagulant aqueous solution was prepared by mixing 20 parts of calcium nitrate, 0.05 part of polyethylene glycol octylphenyl ether and 80 parts of water.
Next, the glove mold was immersed in this coagulant aqueous solution for 5 seconds, pulled up, and then dried under conditions of a temperature of 50 ° C. for 10 minutes to attach the coagulant to the glove mold. And after immersing the glove mold to which the coagulant is adhered in the dip molding composition obtained above for 8 seconds and then immersing in warm water at 40 ° C. for 3 minutes to elute water-soluble impurities, The film was dried at a temperature of 50 ° C. for 10 minutes to form a dip-formed layer in a glove mold.
Then, the glove mold on which the dip-molded layer was formed was dried at a temperature of 70 ° C. for 10 minutes, and subsequently the dip-molded layer was crosslinked by heat treatment at a temperature of 125 ° C. for 20 minutes. The dip-molded layer was peeled from the glove mold to obtain a rubber glove (dip-molded product) having a thickness of 0.08 mm. About the obtained rubber glove (dip molded article), each evaluation of 300% tensile stress, tensile strength, elongation, bending fatigue resistance, copper ion discoloration, and odor was performed by the above methods.
The results are shown in Table 1.

Example 2
Except having changed the addition amount of the polymer which has an oxazoline group (Brand name "Epocross WS-700", Nippon Shokubai Co., Ltd., theoretical oxazoline number 220) from 0.2 part to 1 part, it carries out similarly to Example 1 A composition for dip molding and a rubber glove (dip molded article) were obtained.
About the obtained rubber glove (dip molded article), each evaluation of 300% tensile stress, tensile strength, elongation, bending fatigue resistance, copper ion discoloration, and odor was performed by the above methods.
The results are shown in Table 1.

Example 3
Except having changed the addition amount of the polymer which has an oxazoline group (Brand name "Epocross WS-700", Nippon Shokubai Co., Ltd., theoretical oxazoline number 220) from 0.2 part to 5 parts, it carries out similarly to Example 1. A composition for dip molding and a rubber glove (dip molded article) were obtained.
About the obtained rubber glove (dip molded article), each evaluation of 300% tensile stress, tensile strength, elongation, bending fatigue resistance, copper ion discoloration, and odor was performed by the above methods.
The results are shown in Table 1.

Example 4
0.2 part of a polymer having an oxazoline group (trade name “Epocross WS-700”, theoretical oxazoline number 220, manufactured by Nippon Shokubai Co., Ltd.) and a polymer having an oxazoline group (trade name “Epocross K-2020E”, Nippon Catalyst A dip-molding composition and a rubber glove (dip-molded product) were obtained in the same manner as in Example 1 except that the product was changed to 0.2 part by theoretical oxazoline number 550).
About the obtained rubber glove (dip molded article), each evaluation of 300% tensile stress, tensile strength, elongation, bending fatigue resistance, copper ion discoloration, and odor was performed by the above methods.
The results are shown in Table 1.

Example 5
A polymer having a carbodiimide structure (trade name “Carbodilite V-02”) instead of 0.2 part of a polymer having an oxazoline group (trade name “Epocross WS-700”, manufactured by Nippon Shokubai Co., Ltd., theoretical oxazoline number 220), Made by Nisshinbo Chemical Co., Ltd., theoretical carbodiimide value 600, and the theoretical carbodiimide value means the weight (g) of a polymer containing 1 mol of carbodiimide structure.) The same as in Example 1 except that 0.5 part was added. Thus, a dip-molding composition and rubber gloves (dip-molded product) were obtained.
About the obtained rubber glove (dip molded article), each evaluation of 300% tensile stress, tensile strength, elongation, bending fatigue resistance, copper ion discoloration, and odor was performed by the above methods.
The results are shown in Table 1.

Comparative Example 1
Composition for dip molding in the same manner as in Example 1 except that 0.2 part of a polymer having an oxazoline group (trade name “Epocross WS-700”, theoretical oxazoline number 220, manufactured by Nippon Shokubai Co., Ltd.) was not added. And rubber gloves (dip-molded product) were obtained.
About the obtained rubber glove (dip molded article), each evaluation of 300% tensile stress, tensile strength, elongation, bending fatigue resistance, copper ion discoloration, and odor was performed by the above methods.
The results are shown in Table 1.

Comparative Example 2
1 part of sulfur, 0.5 part of zinc dibutylcarbamate, 0.1 part of β-naphthalene sulfonic acid formalin condensate sodium salt, 0.03 part of potassium hydroxide, and 1.63 parts of water were mixed to give a vulcanizing agent Dispersion liquid (z) was adjusted.
A vulcanizing agent dispersion (z) is added to the carboxyl group-containing conjugated diene rubber (a1) latex obtained in Production Example 1, followed by further adding an aqueous ammonia solution and ion-exchanged water to pH 10.0, solid content. After adjusting the concentration to 30%, the mixture was stirred and dispersed uniformly at a temperature of 20 ° C. for 24 hours to obtain a dip-molding composition (r).
In Comparative Example 2, the vulcanizing agent dispersion (z) is 3.26 parts with respect to 100 parts of the carboxyl group-containing conjugated diene rubber (a1) in the latex of the carboxyl group-containing conjugated diene rubber (a1). Was added as follows.
A dip molding composition and rubber gloves (dip molded product) were obtained in the same manner as in Example 1 except that the dip molding composition (r) was used as the dip molding composition.
About the obtained rubber glove (dip molded article), each evaluation of 300% tensile stress, tensile strength, elongation, bending fatigue resistance, copper ion discoloration, and odor was performed by the above methods.
The results are shown in Table 1.

Comparative Example 3
Instead of the carboxyl group-containing conjugated diene rubber (a1) latex obtained in Production Example 1, the same procedure as in Example 1 was used except that the carboxyl group-containing conjugated diene rubber (c1) latex obtained in Production Example 2 was used. Thus, a dip molding composition was obtained, and an attempt was made to obtain a rubber glove (dip molding product) using the dip molding composition. However, cracks and minute holes were generated during dip molding, and 300% tensile stress, etc. It was not possible to obtain a dip-molded product capable of measuring
The results are shown in Table 1.

Table 1 shows the following.
In Comparative Example 1 which does not satisfy the requirements of the present invention because the polymer (B) containing a monomer unit having a carbon-nitrogen double bond in the molecule was not used, the obtained dip-molded product was Bending fatigue resistance was greatly inferior.
Further, in Comparative Example 2 using sulfur and a vulcanization accelerator instead of the polymer (B) containing a monomer unit having a carbon-nitrogen double bond in the molecule, the obtained dip molding The product (gloves) was colored, and an odor due to sulfur was also felt.
Furthermore, in the comparative example 3 that does not satisfy the requirements of the present invention, cracks and minute holes occur during dip molding because the methyl ethyl ketone insoluble matter of the carboxyl group-containing conjugated diene rubber used in the dip molding composition is too high. A good dip-molded product could not be obtained.
On the other hand, in the case of Examples 1 to 5 using the dip molding composition satisfying the requirements of the present invention, the obtained dip molded product has 300% tensile stress, tensile strength, elongation, and bending fatigue resistance. Excellent properties, no discoloration or odor, and no cracks or minute holes occurred during dip molding.

Claims (6)

A latex of carboxyl group-containing conjugated diene rubber (A) having a methyl ethyl ketone insoluble content of 10 to 70% by weight, and a polymer (B) containing a monomer unit having a carbon-nitrogen double bond in the molecule; The monomer unit having a carbon-nitrogen double bond in the molecule is a monomer unit having an oxazoline group or a monomer unit having a carbodiimide structure,
The composition for dip molding whose content of the said polymer (B) is 0.01-20 weight part with respect to 100 weight part of said carboxyl group-containing conjugated diene rubbers (A).   The dip-forming composition according to claim 1, which does not contain zinc oxide.   The carboxyl group-containing conjugated diene rubber contains 20 to 40% by weight of α, β-ethylenically unsaturated nitrile monomer unit and 50 to 78% by weight of conjugated diene monomer unit. The composition for dip molding according to claim 1 or 2, wherein the diene rubber has an insoluble content in methyl ethyl ketone of 40 to 70% by weight. It is a manufacturing method of the composition for dip forming in any one of Claims 1-3,
The latex of the carboxyl group-containing conjugated diene rubber (A) comprises 30 to 89.5% by weight of a conjugated diene monomer, 10 to 50% by weight of an ethylenically unsaturated nitrile monomer, and 0. A copolymer obtained by polymerizing a monomer mixture containing 5 to 20% by weight and other ethylenically unsaturated monomers copolymerizable with these monomers and 0 to 20% by weight The manufacturing method of the composition for dip molding which is latex of this. A method for producing a dip-molded product comprising a step of dip-molding the dip-molding composition according to any one of claims 1 to 3 or the dip-molding composition obtained by the production method according to claim 4. . It is a glove, The manufacturing method of the dip molded product of Claim 5.