WO2021010334A1 - Composition for dip molding, method for producing glove, and glove - Google Patents

Abstract

The present invention provides a composition for dip molding, said composition containing at least: an elastomer which contains, in the polymer main chain, a structural unit derived from (meth)acrylonitrile, a structural unit derived from an unsaturated carboxylic acid, and a structural unit derived from butadiene; a polycarbodiimide; an epoxy crosslinking agent; water; and a pH adjuster. With respect to this composition for dip molding, the elastomer contains from 12% by weight to 36% by weight of the structural unit derived from (meth)acrylonitrile, from 2% by weight to 10% by weight of the structural unit derived from an unsaturated carboxylic acid, and from 50% by weight to 75% by weight of the structural unit derived from butadiene; the epoxy crosslinking agent includes an epoxy crosslinking agent containing an epoxy compound that has three or more epoxy groups in each molecule; and the polycarbodiimide includes at least one polycarbodiimide that contains a hydrophilic segment in the molecular structure.

Description

Dip molding composition, glove manufacturing method and gloves

The present invention relates to a composition for dip molding, a method for manufacturing a glove, and a glove.

Conventionally, gloves manufactured by dip molding using a latex composition crosslinked with a sulfur-based sulfur-based vulcanization accelerator have been widely used in various industrial fields and medical fields. However, since sulfur cross-linking agents and sulfur-based vulcanization accelerators cause type IV allergies, vulcanization accelerator-free gloves that do not use them have been proposed. These include a self-crosslinking type in which an organic crosslinkable compound is included in latex polymerization, and an external crosslinking agent type in which crosslinks are made with a polycarbodiimide or an epoxy crosslinker. Patent Document 1 describes a method for producing a self-crosslinking glove. Patent Document 2 describes a method for producing gloves using polycarbodiimide as the external cross-linking type, and Patent Document 3 describes a method for producing gloves using an epoxy cross-linking agent as the external cross-linking type.

JP-A-2010-144163 International Publication No. 2018/117109 International Publication No. 2019/102985

The elastomer contained in the composition for dip molding has a carboxyl group derived from unsaturated carboxylic acid, which is a constituent unit thereof, and the carboxyl group is oriented inside and outside the particles of the elastomer. Further, it is considered that the inside of the elastomer particles is lipophilic, while the outside of the particles is hydrophilic. At the time of molding a dip molded product obtained by using the dip molding composition, a crosslinked structure is formed by the above-mentioned cross-linking reaction via the carboxyl group. The type of bond when forming the crosslinked structure, specifically, the difference between a covalent bond and an ionic bond, and the number of crosslinked structures have a great influence on the physical properties of the dip molded product. That is, the control of the crosslinked structure of the carboxyl group of the elastomer and the crosslinking agent has a great influence on the physical properties of the dip molded product, for example, tensile strength, fatigue durability, and stress retention rate.

The polycarbodiimide described in Patent Document 2 is a hydrophilic substance because it has a hydrophilic segment in the molecular structure. On the other hand, it can be said that the epoxy cross-linking agent described in Patent Document 3 is mainly lipophilic based on the value of the MIBK / water distribution ratio.
As described above, the inside of the elastomer particles is lipophilic, while the outside of the particles is considered to be hydrophilic. Therefore, the carboxyl group oriented inside the elastomer particles and the carboxyl oriented outside the elastomer particles. It is considered that the properties of the cross-linking agent that can participate in cross-linking are different from those of the group. Specifically, since the lipophilic cross-linking agent can penetrate into the elastomer particles, a cross-linked structure can be formed by a cross-linking reaction with the carboxyl group oriented in the elastomer particles, whereas the hydrophilic cross-linking agent is the elastomer particles. It is considered that a crosslinked structure can be formed by a crosslinking reaction with a carboxyl group oriented outward.
In the prior art, focusing on the difference in hydrophilicity between the inside of the elastomer particles and the outside of the elastomer particles, it has not been studied to use cross-linking agents having different properties, specifically, hydrophilic ones and lipophilic ones in combination. It was.
Therefore, in the present invention, by using a cross-linking agent having different properties in combination, a dip-molded product having good physical properties, for example, tensile strength, fatigue durability, and stress retention rate, which cannot be obtained by the prior art, is specified. It is an object of the present invention to obtain gloves and to provide a dip molding composition or the like used for producing the dip molded product.

An embodiment of the present invention relates to the following dip molding composition, a method for producing a glove, and a glove obtained by the method for producing the glove. Hereinafter, gloves obtained by using a dip molding composition containing an epoxy cross-linking agent and polycarbodiimide may be abbreviated as "cross-linked gloves of the present invention". Further, gloves obtained by using a dip molding composition containing a sulfur cross-linking agent and a sulfur-based vulcanization accelerator may be abbreviated as "sulfur cross-linking gloves".
[1] Elastomers containing (meth) acrylonitrile-derived structural units, unsaturated carboxylic acid-derived structural units, and butadiene-derived structural units in the polymer main chain, polycarbodiimides, epoxy crosslinkers, water, and pH. A composition for dip molding containing at least a regulator.
In the elastomer, the structural unit derived from (meth) acrylonitrile is 12 to 36% by weight, the structural unit derived from unsaturated carboxylic acid is 2 to 10% by weight, and the structural unit derived from butadiene is 50 to 75% by weight.
The epoxy cross-linking agent contains an epoxy cross-linking agent containing an epoxy compound having three or more epoxy groups in one molecule.
The polycarbodiimide is a composition for dip molding, which comprises at least one polycarbodiimide containing a hydrophilic segment in the molecular structure.
[2] The composition for dip molding according to [1], wherein the MIBK / water distribution ratio according to the following measuring method of the epoxy cross-linking agent is 27% or more.
MIBK / water distribution rate measurement method: 5.0 g of water, 5.0 g of methyl isobutyl ketone (MIBK) and 0.5 g of epoxy cross-linking agent are precisely weighed in a test tube, stirred at 23 ° C ± 2 ° C for 3 minutes, and mixed. Centrifuge at 1.0 × 10 ³ G for 10 minutes to separate into an aqueous layer and a MIBK layer. Next, the MIBK layer is separated and weighed, and the MIBK / water distribution ratio is calculated by the following formula.
MIBK / water distribution rate (%) = (MIBK layer weight after distribution (g) -MIBK weight before distribution (g)) / crosslinker addition weight (g) x 100
The above measurement is performed three times, and the average value is taken as MIBK / water distribution ratio.
[3] The composition for dip molding according to [1] or [2], wherein the pH adjuster is an alkali metal hydroxide.
[4] The composition for dip molding according to any one of [1] to [3], which further contains a dispersant for an epoxy cross-linking agent.

[5] The dispersant of the epoxy cross-linking agent is a monohydric lower alcohol, a glycol represented by the following formula (1), an ether represented by the following formula (2), and a table represented by the following formula (3). The composition for dip molding according to [4], which is one or more selected from the group consisting of the esters to be formed.
HO- (CH ₂ CHR ^1- O) _n1- H (1)
[In formula (1), R ¹ represents a hydrogen or methyl group, and n1 represents an integer of 1 to 3. ]
R ² O- (CH ₂ CHR ^1- O) _n2- R ³ (2)
[In formula (2), R ¹ represents a hydrogen or methyl group, R ² represents an aliphatic hydrocarbon group having 1 to 5 carbon atoms, and R ³ represents hydrogen or an aliphatic hydrocarbon group having 1 to 3 carbon atoms. It represents a hydrocarbon group, and n2 represents an integer of 0 to 3. ]
R ² O- (CH ₂ CHR ^1- O) _n3- (C = O) -CH ₃ (3)
[In formula (3), R ¹ represents a hydrogen or methyl group, R ² represents an aliphatic hydrocarbon group having 1 to 5 carbon atoms, and n 3 represents an integer of 0 to 3. ]
[6] The amount of the epoxy cross-linking agent added to the dip molding composition is 0.2 parts by weight or more and 5.0 parts by weight or less with respect to 100 parts by weight of the elastomer contained in the dip molding composition. The amount of polycarbodiimide added to the dip molding composition is 0.2 parts by weight or more and 5.0 parts by weight or less with respect to 100 parts by weight of the elastomer contained in the dip molding composition [1] to The composition for dip molding according to any one of [5].
[7] The dip molding according to any one of [1] to [6], wherein the zinc oxide content in the dip molding composition is 0.5 parts by weight or less with respect to 100 parts by weight of the elastomer. Composition for.
[8] (1) A step of immersing a glove molding die in a coagulant solution containing calcium ions to attach the coagulant to the glove molding die.
(2) A step of stirring the dip molding composition according to any one of [1] to [7], wherein the pH is adjusted to 9.5 to 12.0 with a pH adjuster.
(3) The glove molding mold to which the coagulant of (1) is attached is immersed in the dip molding composition that has undergone the step (2), and the dip molding composition is coagulated in the glove molding mold to form a film. Dipping process to form,
(4) A gelling step of gelling a film formed on a glove molding mold to prepare a cured film precursor.
(5) A leaching step of removing impurities from the cured film precursor formed on the glove molding mold,
(6) A beading step of making a roll around the cuffs of a glove after the leaching step.
(7) A curing step of heating and drying the cured film precursor to obtain a cured film.
A method for manufacturing gloves, which comprises the above steps (3) to (7) in the above order.
[9] The method for manufacturing gloves according to [8], wherein the steps (3) and (4) above are repeated twice in that order.
[10] The precuring step of heating and drying the cured film precursor at a temperature lower than the temperature of the step (7) is further included between the steps (6) and (7), [8] or [ 9] The method for manufacturing gloves.
[11] Gloves produced by the production method according to any one of [8] to [10].

Provided is a dip molding composition or the like used for producing a dip molded product having good tensile strength, fatigue durability, and stress retention rate.

It is sectional drawing which shows typically an example of the fatigue durability test apparatus.

Hereinafter, preferred embodiments of the present invention will be described, but it goes without saying that the present invention is not limited to these embodiments, and various modifications and changes may be made. Since "weight" and "mass" are used interchangeably in the present specification, they will be collectively referred to as "weight" below.
As used herein, the term "fatigue durability" means resistance to a glove being broken due to deterioration in performance due to sweat of a user (worker). The specific evaluation method will be described later.
Regarding fatigue durability, since the finger crotch part of a glove is usually easily torn, it is a practical pass line that the finger crotch part exceeds 90 minutes, but in the present invention, a film is produced on a ceramic plate. However, since we are looking at fatigue durability, we will look at fatigue durability equivalent to the palm part. The fatigue durability of the palm and finger crotch can be converted by the following formula.
Formula (palm fatigue durability (minutes) + 21.43) ÷ 2.7928 = finger crotch fatigue durability (minutes)
Therefore, the passing line of the fatigue durability test in the present invention is set to 240 minutes.
Further, in the present invention, the tensile strength is expressed in MPa, which is a value obtained by dividing the load at break (N) by the cross-sectional area of the test piece, and is a value excluding the influence of the thickness. For thin gloves (over 3.2 g to 4.5 g: film thickness over 60 μm to 90 μm), the value is 20 MPa. On the other hand, the EN standard (EN 455) is based on a load of 6 N at break, and thinner gloves (2.7 to 3.2 g: film thickness 50 to 60 μm) are required to have a performance exceeding 35 MPa. To.

1. 1. Dip Molding Composition (1) Outline of Dip Molding Composition The dip molding composition of the present embodiment contains a specific elastomer, a specific epoxy cross-linking agent, a specific polycarbodiimide, water, and a pH adjuster. And, if necessary, a metal cross-linking agent or the like.
This dip molding composition is an emulsion which is adjusted to have a pH of about 9.5 to 12.0 as a dipping liquid for gloves, and each solid content is agitated by maturation and dispersed almost uniformly.
The composition for dip molding is a latex containing XNBR (carboxylated (meth) acrylonitrile butadiene elastomer), and XNBR forms particles having a particle diameter of about 50 to 250 nm as an aqueous emulsion. The environment inside and outside the particle is significantly different, and the inside of the particle is lipophilic because it is mainly composed of hydrocarbons composed of butadiene residue, (meth) acrylonitrile residue, (meth) acrylic acid and the like. On the other hand, since the outside of the particles is composed of water and a water-soluble component (for example, a pH adjuster, etc.), the outside of the particles is hydrophilic.
The carboxyl group oriented outside the particles of the elastomer reacts with the polycarbodiimide contained in the dip molding composition to form a crosslinked structure.
On the other hand, when the epoxy cross-linking agent stays in the hydrophilic region outside the particles, it will be inactivated by hydrolysis, so more of it will enter the lipophilic region inside the particles where contact with water can be avoided. It is thought that the epoxy cross-linking agent that can be used avoids inactivation, and as a result, contributes to the formation of many cross-linked structures.

The dip molding composition according to the embodiment of the present invention includes, for example, medical supplies such as a nipple for a baby bottle, a dropper, a conduit, and a water pillow, and toys such as balloons, dolls, and balls, in addition to the composition for molding gloves. It can be used for molding industrial supplies such as exercise equipment, pressure molding bags, gas storage bags, and dip molded products such as surgical, household, agricultural, fishing and industrial gloves, and finger cots. Next, the solid content of the dip molding composition will be described.

(2) Elastomer The elastomer contains at least a structural unit derived from (meth) acrylonitrile, a structural unit derived from an unsaturated carboxylic acid, and a structural unit derived from butadiene in the polymer main chain. This elastomer is also referred to as a carboxylated (meth) acrylonitrile butadiene elastomer or simply "XNBR". Further, gloves obtained by using XNBR as an elastomer are also simply referred to as "XNBR gloves".

The ratio of each structural unit is that the structural unit derived from (meth) acrylonitrile, that is, the structural unit derived from unsaturated carboxylic acid, that is, 12 to 36% by weight of the (meth) acrylonitrile residue, in the elastomer for producing gloves. That is, the unsaturated carboxylic acid residue is in the range of 2 to 10% by weight, and the structural unit derived from butadiene, that is, the butadiene residue is in the range of 50 to 75% by weight. The ratio of these structural units can be easily obtained from the weight ratio of the raw materials used for producing the elastomer.

The structural unit derived from (meth) acrylonitrile is an element that mainly gives strength to gloves. If it is too small, the strength will be insufficient, and if it is too large, the chemical resistance will increase but it will be too hard. The ratio of structural units derived from (meth) acrylonitrile in the elastomer is more preferably 12 to 36% by weight. In conventional XNBR gloves, the ratio of structural units derived from (meth) acrylonitrile is usually 25 to 30% by weight, but in recent years, XNBR of less than 25% by weight has also been developed. The amount of the structural unit derived from (meth) acrylonitrile can be obtained by converting the amount of nitrile groups from the amount of nitrogen atoms obtained by elemental analysis.

Butadiene-derived structural units are elements that give gloves flexibility, and usually lose flexibility below 50% by weight. The ratio of the structural unit derived from butadiene in the elastomer is more preferably 55 to 70% by weight, and particularly preferably about 60% by weight.

The amount of the structural unit derived from the unsaturated carboxylic acid is preferably 2 to 10% by weight, preferably 2 to 9% by weight, in order to maintain the physical properties of the final product, the glove, which has an appropriate crosslinked structure. It is more preferably 2 to 6% by weight in this order. The amount of the structural unit derived from the unsaturated carboxylic acid can be determined by the back titration method of the carboxyl group and the quantification of the carbonyl group derived from the carboxyl group by infrared spectroscopy (IR) or the like.

The unsaturated carboxylic acid that forms the structural unit derived from the unsaturated carboxylic acid is not particularly limited, and may be a monocarboxylic acid or a polycarboxylic acid. More specifically, acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid and the like can be mentioned. Among them, acrylic acid and / or methacrylic acid (hereinafter referred to as "(meth) acrylic acid") is preferably used, and more preferably methacrylic acid is used. Unsaturated carboxylic acids not illustrated here may be used, or two or more unsaturated carboxylic acids may be used.
The structural unit derived from butadiene is preferably a structural unit derived from 1,3-butadiene.

The polymer backbone is preferably composed of structural units derived from (meth) acrylonitrile, unsaturated carboxylic acids, and butadiene, but other structural units derived from polymerizable monomers. It may be included. On the other hand, the polymer main chain includes unsaturated monomers having a crosslinkable functional group as described in Patent Document 1, and self-crosslinkable compounds described in International Publication No. 2016/0136666. It is preferable that the constituent unit from which it is derived is not included.
The structural unit derived from the other polymerizable monomer is preferably 30% by weight or less, more preferably 20% by weight or less, and further preferably 15% by weight or less in the elastomer.

Preferred polymerizable monomers include aromatic vinyl monomers such as styrene, α-methylstyrene and dimethylstyrene; ethylenically unsaturated carboxylic acid amides such as (meth) acrylamide and N, N-dimethylacrylamide; (meth). ) Ethylene unsaturated carboxylic acid alkyl ester monomers such as methyl acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate; and vinyl acetate. These can be arbitrarily used by any one type or a combination of a plurality of types.

As the elastomer, unsaturated carboxylic acids such as (meth) acrylonitrile and (meth) acrylic acid, butadiene such as 1,3-butadiene, and other polymerizable monomers as necessary are used, and emulsifiers usually used according to a conventional method. It can be prepared by emulsion polymerization using a polymerization initiator, a molecular weight modifier, or the like.
The water at the time of emulsion polymerization is preferably contained in an amount having a solid content of 30 to 60% by weight, and more preferably contained in an amount having a solid content of 35 to 55% by weight.
The emulsion polymerization solution after the elastomer synthesis can be used as it is as an elastomer component of the composition for dip molding.

Examples of the emulsifier include anionic surfactants such as dodecylbenzene sulfonates and aliphatic sulfonates; nonionic surfactants such as polyethylene glycol alkyl ethers and polyethylene glycol alkyl esters, and preferred anions. Sexual surfactants are used.

The polymerization initiator is not particularly limited as long as it is a radical initiator, but is an inorganic peroxide such as ammonium persulfate and potassium perphosphate; t-butyl peroxide, cumene hydroperoxide, p-menthan hydroperoxide, t. -Organic peroxides such as butyl cumyl peroxide, benzoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, t-butylperoxyisobutyrate; azobisisobutyronitrile, azobis-2,4- Examples thereof include azo compounds such as dimethylvaleronitrile, azobiscyclohexanecarbonitrile, and methyl azobisisobutyrate.

Examples of the molecular weight adjusting agent include mercaptans such as t-dodecyl mercaptan and n-dodecyl mercaptan, halogenated hydrocarbons such as carbon tetrachloride, methylene chloride and methylene bromide, and t-dodecyl mercaptan; n-dodecyl mercaptan and the like. Mercaptans are preferred.

The characteristics of the suitable elastomer used for the gloves according to the embodiment of the present invention will be described below.
<Selection of elastomer by Mooney viscosity (ML _{(1 + 4)} (100 ° C))>
In gloves, a considerable part excluding the cross-linked portion by various cross-linking agents is cross-linked with calcium which is a coagulant (when a glove containing calcium ions is used as the coagulant). When no metal cross-linking agent is used in the present invention, the tensile strength is maintained by calcium cross-linking.
It is known that the tensile strength due to calcium cross-linking is almost proportional to the height of the Mooney viscosity of the elastomer. When cross-linking with an organic cross-linking agent is not performed and an elastomer having a Mooney viscosity of 80 is used, the tensile strength is about 15 MPa, and when the Mooney viscosity is 100, the tensile strength is about 20 MPa. Therefore, it is preferable to select an elastomer having a Mooney viscosity of about 100 to 150.
The upper limit of the Mooney viscosity is about 220 because the measurement limit of the Mooney viscosity itself is 220, and if the Mooney viscosity is too high, a problem of molding processability occurs. On the other hand, when an elastomer having a Mooney viscosity too low is used, tensile strength is not obtained.

<The elastomer chain has few branches and is linear>
In order to facilitate the penetration of the epoxy cross-linking agent into the inside of the elastomer chain (inside the particles), an elastomer having few branches of the elastomer chain and being linear is preferable. Elastomers with few branches have been devised at the time of manufacture by each latex manufacturer, but generally speaking, cold rubber (polymerization temperature 5 to 25 ° C) with a lower polymerization temperature is hot rubber (polymerization temperature 25 to 25 to 25 ° C.). 50 ° C.) is considered to be more preferable.

<Gel fraction of elastomer (MEK insoluble matter)>
In the elastomer used in the embodiment of the present invention, it is preferable that the gel fraction is small.
In the measurement of the insoluble matter of methyl ethyl ketone (MEK), it is preferably 40% by weight or less, and more preferably 10% by weight or less. However, the MEK insoluble matter has no correlation with the tensile strength such as Mooney viscosity.
It can be said that an elastomer having a large amount of acetone-soluble components of the elastomer is preferable, and the epoxy cross-linking agent penetrates into the elastomer particles in a lipophilic environment to protect the elastomer. Therefore, the fatigue durability of the elastomer Is also expected to be higher.

<Elastomer water release>
The elastomer used in the embodiment of the present invention forms particles having a particle diameter of about 50 to 250 nm as an aqueous emulsion. There are two types of elastomers, one with a relatively high affinity for water and the other with a low affinity for water. The lower the affinity for water, the easier it is for water to escape between particles (water separation), and the higher the water separation, the higher the elastomer. Cross-linking between particles is performed smoothly.
Therefore, if XNBR having high water separation is used, the cross-linking temperature can be lowered.

<Content of sulfur element in elastomer>
In the elastomer used in the embodiment of the present invention, the content of the sulfur element detected by the neutralization titration method of the combustion gas is preferably 1% by weight or less based on the weight of the elastomer.
To quantify the sulfur element, 0.01 g of an elastomer sample is burned in air at 1350 ° C. for 10 to 12 minutes, and the combustion gas generated is absorbed by a hydrogen peroxide solution containing a mixing indicator, and a 0.01 N NaOH aqueous solution is used. It can be carried out by the method of neutralization titration with.

The composition for dip molding may contain a combination of a plurality of types of elastomers. The content of the elastomer in the dip molding composition is not particularly limited, but is preferably about 15 to 35% by weight, more preferably 18 to 30% by weight, based on the total amount of the dip molding composition. preferable.

(3) Epoxy cross-linking agent (a) Epoxy cross-linking agent according to the embodiment of the present invention The epoxy cross-linking agent according to the embodiment of the present invention contains an epoxy compound having three or more epoxy groups in one molecule. It is an epoxy cross-linking agent having a MIBK / water partition ratio of 27% or more, more preferably 50% or more.
The following will be described step by step.

(B) An epoxy cross-linking agent containing an epoxy compound having three or more epoxy groups in one molecule i. Epoxy compounds having 3 or more epoxy groups in one molecule Epoxy compounds having 3 or more epoxy groups in one molecule are usually a plurality of glycidyl ether groups and alicyclic, aliphatic or aromatic hydrocarbons. It has a mother skeleton having (hereinafter, also referred to as "trivalent or higher valent epoxy compound"). As the epoxy compound having a valence of 3 or more, an epoxy compound having 3 or more glycidyl ether groups can be preferably mentioned. An epoxy compound having 3 or more glycidyl ether groups can usually be produced by reacting epihalohydrin with an alcohol having 3 or more hydroxyl groups in one molecule.
Examples of the epoxy cross-linking agent containing an epoxy compound having three or more epoxy groups in one molecule include polyglycidylamine, polyglycidyl ester, epoxidized polybutadiene, and epoxidized soybean oil.

Alcohols having three or more hydroxyl groups that form the matrix of a trivalent or higher epoxy compound include aliphatic glycerol, diglycerol, triglycerol, polyglycerol, sorbitol, sorbitan, xylitol, erythritol, trimethylolpropane, and tri. Examples include methylolethane, pentaerythritol, aromatic cresol novolac, and trishydroxyphenylmethane.
Among the epoxy compounds having a valence of 3 or more, it is preferable to use polyglycidyl ether.
Specifically, glycerol triglycidyl ether, trimethylolpropane triglycidyl ether, trimethylolethane triglycidyl ether, sorbitol triglycidyl ether, sorbitol tetraglycidyl ether, pentaerythritol triglycidyl ether, pentaerythritol tetraglycidyl ether, diglycerol triglycidyl ether. It is preferable to use an epoxy cross-linking agent containing at least one selected from ethers, among which among trimethylolpropane triglycidyl ether, pentaerythritol triglycidyl ether, glycerol triglycidyl ether, diglycerol triglycidyl ether and pentaerythritol tetraglycidyl ether. It is more preferable to use an epoxy cross-linking agent containing at least one selected from. Further, it is preferable to use an epoxy cross-linking agent containing an epoxy compound having no sorbitol skeleton.

ii. Epoxy cross-linking agent containing an epoxy compound having 3 or more epoxy groups in one molecule (hereinafter, also referred to as a trivalent or higher-valent epoxy cross-linking agent) Among epoxy cross-linking agents, those containing an epoxy compound having a glycidyl ether group In general, the hydroxyl group of an alcohol and epihalohydrin can be reacted as follows to produce the product. In (I) below, a monohydric alcohol is used as the alcohol and epichlorohydrin is used as the epichlorohydrin in order to simplify the explanation.

The epoxy compound contained in the epoxy cross-linking agent ranges from divalent to approximately octavalent depending on the number of hydroxyl groups of the raw material alcohol. However, even when a trivalent epoxy compound is synthesized as a target substance by a side reaction in the process of the reaction, several kinds of compounds are produced, and usually, a divalent epoxy compound is also included in the compound.
Therefore, for example, the trivalent epoxy cross-linking agent is generally a mixture of divalent and trivalent epoxy compounds. Usually, even what is called a trivalent epoxy cross-linking agent is said to have a content of about 50% of the trivalent epoxy compound which is the main component.
In addition, some epoxy cross-linking agents are difficult to dissolve in water, and this is greatly affected by chlorine and the like contained in the structure of the epoxy compound.
When the epoxy cross-linking agent used in the present invention contains an epoxy compound having a glycidyl ether group, it usually contains a trivalent or higher valent epoxy compound obtained by reacting epihalohydrin with an alcohol having three or more hydroxyl groups. It is an epoxy cross-linking agent.
More specifically, from the viewpoint of good tensile strength, fatigue durability, and stress retention of the dip molded product, Denacol Ex-313, Ex-314, Ex-321, Ex-321B, Ex, manufactured by Nagase ChemteX Corporation. Examples thereof include products such as -411, Ex-421, Ex-612, and Ex-622.
As the epihalohydrin, one or more selected from epichlorohydrin, epibromohydrin, and epiiaiodite hydrin can be used. Among these, it is preferable to use epichlorohydrin. Further, a trivalent or higher valent epoxy cross-linking agent and a divalent epoxy cross-linking agent can be mixed and used. Alternatively, when producing a trivalent or higher valent epoxy cross-linking agent, an alcohol having three or more hydroxyl groups and an alcohol having two hydroxyl groups can be mixed and reacted.

iii. Comparison of conventional divalent epoxy crosslinkers and trivalent or higher valent epoxy crosslinkers The conventional divalent epoxy crosslinkers are two-point crosslinks that crosslink between two carboxyl groups with one molecule of the epoxy compound. On the other hand, the epoxy compound contained in the epoxy cross-linking agent used in the embodiment of the present invention is characterized in that one molecule can carry out multi-point cross-linking for cross-linking between three or more carboxyl groups. It is considered that this results in more cross-linking between elastomer molecules, resulting in overwhelming fatigue durability as compared with conventional two-point cross-linked gloves. In order to obtain better fatigue durability, the upper limit of the number of epoxy groups contained in one molecule of the epoxy compound contained in the epoxy cross-linking agent is not particularly limited, and examples thereof include 8. Further, in the case of a divalent epoxy compound conventionally used as a main component, the epoxy compound loses its cross-linking function even if only one epoxy group is deactivated.
On the other hand, in the epoxy cross-linking agent containing a trivalent or higher valent epoxy compound used in the present invention, even if one of the epoxy groups of the epoxy compound is deactivated, two or more epoxy groups remain, so that the cross-linking function is provided. It will remain. As a result, the present invention can perform cross-linking more efficiently than when a conventional divalent epoxy compound is used.
As a result, gloves having the same performance can be obtained with a smaller amount of epoxy cross-linking agent added than in the past.

iv. Crosslinking reaction between an epoxy compound and the carboxyl group of XNBR As shown by the following formula (II), the epoxy crosslinking occurs by the following reaction. The epoxy compound shown in (II) below is a monovalent epoxy compound from the viewpoint of simplifying the explanation.

It is the carboxyl group in the XNBR that the epoxy compound forms a crosslink, and in order to form a crosslink with the epoxy compound, the optimum condition is to heat the epoxy compound at 90 ° C. or higher in the curing step to open the epoxy group. Can be mentioned.
The epoxy cross-linking agent contained in the dip molding composition, which had escaped deactivation in the lipophilic environment in the particles of XNBR, became a cured film precursor and was heated as a whole in the curing process as a lipophilic environment. At that time, it reacts with the carboxyl group of XNBR protruding outside the particle. At this time, by selecting XNBR having good water separation, the crosslinking efficiency can be increased and the crosslinking temperature can be lowered.

v. Properties of suitable epoxy cross-linking agent <Average number of epoxy groups>
As described above, even if the epoxy cross-linking agent has a trivalent value or higher, a divalent epoxy compound may be contained as a side reaction. Therefore, when evaluating each product, the average number of epoxy groups is grasped and the trivalent epoxy compound is used. It is important to know the proportion of compounds that have epoxy groups.
The average number of epoxy groups is obtained by specifying each epoxy compound contained in the epoxy cross-linking agent by GPC and multiplying the number of epoxy groups in one molecule of each epoxy compound by the number of moles of the epoxy compound. It is obtained for each epoxy compound, and the total value thereof is divided by the total number of moles of all the epoxy compounds contained in all the epoxy compounds contained in the epoxy cross-linking agent.
The average number of epoxy groups of the epoxy cross-linking agent used in the embodiment of the present invention is more than 2.0, and from the viewpoint of obtaining good fatigue durability of gloves, the average number of epoxy groups is preferably 2.3 or more. 2.5 or more is more preferable. On the other hand, the upper limit of the average number of epoxy groups is not particularly limited, and for example, 10.0 or less can be mentioned.

<Equivalent>
From the viewpoint of obtaining suitable fatigue durability, the epoxy equivalent of the epoxy cross-linking agent is 100 g / eq. 230 g / eq. The following is preferable. Even if the epoxy equivalents are similar, the trivalent epoxy cross-linking agent tends to have better fatigue durability than the divalent epoxy cross-linking agent.
The epoxy equivalent of the epoxy cross-linking agent is a value obtained by dividing the average molecular weight of the epoxy cross-linking agent by the average number of epoxy groups, and indicates the average weight per epoxy group. This value can be measured by the perchloric acid method.

<Molecular weight>
From the viewpoint of dispersibility in water, the molecular weight of the epoxy compound contained in the epoxy cross-linking agent is preferably 150 to 1500, more preferably 175 to 1400, and even more preferably 200 to 1300.

vi. Amount of Epoxy Crosslinker Added The amount of epoxy crosslinker added depends on the number and purity of epoxy groups in one molecule of the epoxy compound from the viewpoint of introducing a sufficient crosslinked structure between the elastomers to ensure fatigue durability. However, 0.2 parts by weight or more can be mentioned with respect to 100 parts by weight of the elastomer. Practically, even if it is extremely thin (2.7 g glove, film thickness is about 50 μm), it is possible to manufacture a glove having sufficient performance with 0.4 parts by weight or more with respect to 100 parts by weight of the elastomer. On the other hand, if the amount added is excessive, the properties of the elastomer may be deteriorated. Therefore, the upper limit of the amount of the epoxy cross-linking agent added to the dip molding composition is 5 parts by weight with respect to 100 parts by weight of the elastomer. Is considered to be preferable.
On the other hand, in the present invention, in the case of thin gloves, the amount of the epoxy cross-linking agent added is preferably 0.4 to 1.0 parts by weight, more preferably 0.5 to 0.7 parts by weight, based on 100 parts by weight of the elastomer. ..
However, as in the case of thick gloves (thickness of more than 200 to 300 μm), when reducing zinc, it is conceivable to further increase the amount of the epoxy cross-linking agent added.

vii. Epoxy cross-linking agent having a MIBK / water partition ratio of 27% or more In the present invention, an epoxy cross-linking agent having a MIBK / water partition ratio of 27% or more, preferably 50% or more, more preferably 70% or more by the following measurement method is used. Therefore, it is considered that a dip molding composition for obtaining a dip molded product having a high stress retention rate can be obtained.

The MIBK / water distribution ratio can be measured as follows.
First, about 5.0 g of water, about 5.0 g of MIBK, and about 0.5 g of an epoxy cross-linking agent are precisely weighed and added to a test tube. Let the weight of MIBK be M (g) and the weight of the epoxy crosslinker be E (g).
This mixture is well stirred and mixed at a temperature of 23 ° C. ± 2 ° C. for 3 minutes, and then centrifuged under the condition of 1.0 × 10 ³ G for 10 minutes to separate an aqueous layer and a MIBK layer. Next, the weight of the MIBK layer is measured, and this is designated as ML (g).
MIBK / water distribution rate (%) = (ML (g) -M (g)) / E (g) x 100
The MIBK / water measurement method in this specification was measured based on the weight of water and MIBK, but since MIBK dissolves water slightly, minus% is obtained as an experimental value, but the measurement is performed using the same standard. Therefore, I thought that it could be adopted as a standard.

(4) Dispersant of Epoxy Crosslinker The above-mentioned epoxy crosslinker needs to be kept in a uniform dispersed state in the composition for dip molding. On the other hand, in the epoxy cross-linking agent having a MIBK / water partition ratio of 27% or more in the embodiment of the present invention, it is said that the higher the MIBK / water partition ratio, the more difficult it is to add the cross-linking agent to the latex solution and the more difficult it is to disperse. It turns out that there is a problem.
In particular, an epoxy cross-linking agent having a MIBK / water distribution ratio of 50% or more is cloudy when dissolved in water, so it is preferable to disperse with a dispersant.

The dispersant of the epoxy cross-linking agent is a monohydric lower alcohol, a glycol represented by the following formula (1), an ether represented by the following formula (2), and an ester represented by the following formula (3). It is preferable that the amount is one or more selected from the group consisting of.
HO- (CH ₂ CHR ^1- O) _n1- H (1)
(In formula (1), R ¹ represents a hydrogen or methyl group, and n 1 represents an integer of 1 to 3.)
R ² O- (CH ₂ CHR ^1- O) _n2- R ³ (2)
[In formula (2), R ¹ represents a hydrogen or methyl group, R ² represents an aliphatic hydrocarbon group having 1 to 5 carbon atoms, and R ³ represents hydrogen or an aliphatic hydrocarbon group having 1 to 3 carbon atoms. It represents a hydrocarbon group, and n2 represents an integer of 0 to 3. ]
R ² O- (CH ₂ CHR ^1- O) _n3- (C = O) -CH ₃ (3)
[In formula (3), R ¹ represents a hydrogen or methyl group, R ² represents an aliphatic hydrocarbon group having 1 to 5 carbon atoms, and n 3 represents an integer of 0 to 3. ]

Examples of the monohydric lower alcohol include methanol and ethanol.
Examples of the glycol represented by the formula (1) include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, and tripropylene glycol.
Among the ethers represented by the formula (2), the glycol ethers include diethylene glycol monomethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monoisobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monobutyl ether, and tripropylene glycol. Examples thereof include monomethyl ether and triethylene glycol dimethyl ether. Further, as the ether represented by the formula (2), an ether having n2 = 0 can also be used.
Examples of the ester represented by the formula (3) include diethylene glycol monoethyl ether acetate and diethylene glycol monobutyl ether acetate.
When the above-mentioned dispersant of the epoxy cross-linking agent is used, only one kind may be used, or two or more kinds may be used in combination. The dispersant is preferably used without being mixed with water in advance.

The present inventor examined the use of an organic solvent as a dispersant, and as a result of first selecting a solvent that is not harmful to the human body, it was found that alcohol is preferable.
Among the above, it is preferable to use methanol, ethanol and diethylene glycol, and it is particularly preferable to use diethylene glycol from the viewpoint of volatility and flammability.
It is presumed that diethylene glycol is suitable because it has a highly hydrophilic glycol group and an ether structure, and at the same time contains a lipophilic hydrocarbon structure, and is easily dissolved in water and an elastomer.

The weight ratio of the epoxy cross-linking agent to the dispersant in the dip molding composition is preferably 1: 4 to 1: 1.
When an epoxy cross-linking agent having a low water content is used when preparing the composition for dip molding, the epoxy cross-linking agent is dissolved in the dispersant of the epoxy cross-linking agent in advance, and then the composition for dip molding is added. It is preferable to mix with the constituents of.

(5) Polycarbodiimide The dip molding composition according to the embodiment of the present invention contains polycarbodiimide as a cross-linking agent. The polycarbodiimide used in the embodiment of the present invention comprises a central portion that undergoes a cross-linking reaction with a carboxyl group and a hydrophilic segment added to the end portion thereof. Further, a part of the end portion may be sealed with a sealant.
Hereinafter, each portion of polycarbodiimide will be described.

<Central part of polycarbodiimide>
First, the chemical formula of the central portion of the polycarbodiimide used in the embodiment of the present invention is shown below in the form of diisocyanate as a raw material.
(1) OCN- (R ^1- (N = C = N)-) _m- R ^1- NCO
-N = C = N- in the above formula (1) is a carbodiimide group and reacts with the carboxyl group of XNBR.
In the formula, R ¹ is exemplified by diisocyanate described later.
m is an integer of 4 to 20 and indicates the degree of polymerization (the number of carbodiimide functional groups per molecule of polycarbodiimide). By setting m to 4 or more, the carboxyl groups of the elastomer (XNBR) used in the embodiment of the present invention can be crosslinked at multiple points, and thus the elastomer (XNBR) used in the embodiment of the present invention can be largely summarized. Therefore, it is considered that this is a factor for obtaining very good fatigue durability as compared with the conventional two-point cross-linking agent.
The central portion of the polycarbodiimide is usually formed by decarboxylation of diisocyanate and has isocyanate residues at both ends.
Examples of the diisocyanate include aromatic diisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, and mixtures thereof. Specifically, 1,5-naphthylene diisocyanate, 4,4-diphenylmethane diisocyanate, 4,4-diphenyldimethylmethane diisocyanate, 1,3-phenylenediocyanate, 1,4-phenylenediocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, hexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4 , 4'-Diisocyanate, methylcyclohexanediisocyanate, tetramethylxylylene diisocyanate and the like can be exemplified. From the viewpoint of weather resistance, it is preferable to add polycarbodiimide produced by a condensation reaction of an aliphatic or alicyclic diisocyanate accompanied by decarbonization. That is, since the diisocyanates do not have double bonds, the polycarbodiimides produced from them are less likely to be deteriorated by ultraviolet rays or the like.
A typical type of diisocyanate is dicyclohexylmethane-4,4'-diisocyanate.

<Hydrophilic segment>
Since the carbodiimide group easily reacts with water, the purpose of the dip molding composition according to the embodiment of the present invention is to protect the carbodiimide group from water so as not to lose the reactivity with the elastomer (XNBR) used in the embodiment of the present invention. , It is essential to add a hydrophilic segment to the terminal (isocyanate group) of a part of polycarbodiimide.
The structure of the hydrophilic segment is shown in the following equation (2).
(2) R ^2- O- (CH _2- CHR ^3- O-) _n- H
In the above formula (2), R ² is an alkyl group having 1 to 4 carbon atoms, R ³ is a hydrogen atom or a methyl group, and n is an integer of 5 to 30.
The hydrophilic segment has a function of protecting the carbodiimide group by surrounding the central portion of polycarbodiimide which easily reacts with water in the dip molding composition (dip liquid) (in water) (shell / core structure).
On the other hand, when dried, the hydrophilic segment opens and a carbodiimide group appears, and the reaction is ready. Therefore, in the production of gloves by dip molding of the present invention, it is important to reduce the water content for the first time in the curing step described later, open the hydrophilic segment, and crosslink the carbodiimide group with the carboxyl group of XNBR. For this purpose, it is also effective to add a moisturizer, which will be described later, to the dip molding composition in the gelling step so as not to dry the highly syneretic XNBR.
The hydrophilic segments may be located at both ends of the central portion or may be located at one side. It may also be a mixture of those having a hydrophilic segment and those having no hydrophilic segment.
The end to which the hydrophilic segment is not added is sealed with a sealant.

<Sealant>
The formula of the sealant is represented by the following formula (3).
(3) (R ⁴ ) ₂ N-R ^5- OH
In the above formula (3), R ⁴ is an alkyl group having 6 or less carbon atoms, and is preferably an alkyl group having 4 or less carbon atoms from the viewpoint of availability. R ⁵ is an alkylene having 1 to 10 carbon atoms or a polyoxyalkylene.

<Number of carbodiimide functional groups per molecule, degree of polymerization, molecular weight, equivalent>
The number of carbodiimide functional groups in the polycarbodiimide used in the embodiment of the present invention is preferably 4 or more. When the number of carbodiimide functional groups is 4 or more, multipoint cross-linking is surely performed and the fatigue characteristics required for implementation are satisfied.
The numerical value of the number of carbodiimide functional groups can be obtained from the values of the polycarbodiimide equivalent and the number average molecular weight, which will be described later.
The number of carbodiimide functional groups per molecule = the average degree of polymerization of polycarbodiimide (number average molecular weight / carbodiimide equivalent) is 3.8 or more, more preferably 9 or more. This is necessary in order to appropriately form the multi-point crosslinked structure, which is a feature of the glove according to the embodiment of the present invention, and to give the glove high fatigue durability.
The molecular weight of the polycarbodiimide is preferably 500 to 5000 in terms of number average molecular weight, and even more preferably 1000 to 4000.
The number average molecular weight can be measured by the GPC method (calculated by polystyrene conversion) as follows.
Measuring device: HLC-8220GPC manufactured by Tosoh Corporation
Column: Shodex KF-G + KF-805Lx 2 + KF-800D
Eluent: THF
Measurement temperature: Column constant temperature bath 40 ° C
Flow velocity: 1.0 mL / min
Concentration: 0.1% by weight / volume
Solubility: Complete dissolution Pretreatment After air-drying the sample with nitrogen, vacuum-dry it at 70 ° C. for 16 hours to adjust.
Filter with a 0.2 μm filter before measurement Detector: Differential refractometer (RI)
The number average molecular weight is converted using a monodisperse polystyrene standard sample.

The carbodiimide equivalent is preferably in the range of 260 to 600 from the viewpoint of fatigue durability, and more preferably 260 to 440 from the viewpoint of improving fatigue durability.
The carbodiimide equivalent is a value calculated by the following formula (I) from the carbodiimide group concentration quantified by the back titration method using oxalic acid.
Carbodiimide equivalent = number of carbodiimide groups (40) x 100 / carbodiimide group concentration (%) (I)
The amount of the polycarbodiimide added to the dip molding composition according to the embodiment of the present invention is 0.2 parts by weight or more and 5.0 parts by weight with respect to 100 parts by weight of the elastomer contained in the dip molding composition. The number of parts is preferably 0.3 parts by weight or more and 2.5 parts by weight or less, and more preferably 0.3 parts by weight or more and 2.0 parts by weight or less. Regarding the range of content, while profitability deteriorates when it exceeds 5.0 parts by weight, even a small amount of 0.2 parts by weight or more should have a high stress retention rate that exceeds that of other sulfur-based gloves. We are verifying that we can do it.

The weight ratio of the amount of the above-mentioned epoxy cross-linking agent added to the composition for dip molding and the amount of the polycarbodiimide added is, for example, 0.1 to 10.0 when the epoxy cross-linking agent is 1. It is preferably 0.3 to 5.0, and more preferably 0.3 to 5.0.

(6) pH adjuster The dip molding composition needs to be adjusted to be alkaline at the stage of the maturation step described later. One reason that the alkaline, in order to perform the crosslinking sufficiently, the -COOH of particles of elastomeric -COO ^- as oriented to the outside of the particles, in order to sufficiently perform the inter-particle crosslinking.
The preferable pH value is 9.5 to 12.0. When the pH is low, the orientation of −COOH to the outside of the particles is small and the cross-linking is insufficient, and when the pH is too high, the stability of the latex is deteriorated.
As the pH adjuster, one or more obtained from ammonia, ammonium compounds, amine compounds and alkali metal hydroxides can be used. Among these, alkali metal hydroxides are preferably used because the production conditions such as pH adjustment and gelling conditions are easy, and among them, potassium hydroxide (hereinafter, also referred to as KOH) is the easiest to use. Hereinafter, in the examples, KOH will be mainly used as the pH adjuster.
The amount of the pH adjuster added can be about 0.1 to 4.0 parts by weight with respect to 100 parts by weight of the elastomer in the dip molding composition, but is usually 1.8 to 2 in industry. Use about 0.0 parts by weight. The temperature at the time of pH measurement is 30 ° C.

(7) Metal Crosslinking Agent The elastomer constituting the gloves according to the embodiment of the present invention has a crosslinked structure combined with calcium ion bonding when an elastomer containing calcium ions is used as the coagulant.
Calcium tends to elute immediately in an artificial sweat solution that imitates human sweat, so the tensile strength tends to decrease. In addition, calcium ions have a larger ionic radius than other metal cross-linking agents such as zinc oxide or aluminum complexes, and the impermeableness of organic solvents is insufficient. Therefore, it is considered effective to replace some calcium crosslinks with zinc crosslinks or aluminum crosslinks. Further, the tensile strength and chemical resistance can be controlled by increasing the amount of zinc oxide or aluminum complex. In particular, the crosslinked aluminum has an advantage that it is very difficult to elute into a sweat-like solution such as artificial sweat liquid.

The polyvalent metal compound used as a metal cross-linking agent crosslinks by ionic bonding between functional groups such as unreacted carboxyl groups in the elastomer. As the multivalent metal compound, zinc oxide, which is a divalent metal oxide, is usually used. Further, aluminum, which is a trivalent metal, can be used as a cross-linking agent by forming a complex thereof.
It is difficult to obtain a high stress retention rate for gloves by cross-linking by ionic bonding using zinc oxide.
Aluminum has the smallest ionic radius among the above and is most suitable for obtaining chemical resistance and tensile strength, but it is difficult to handle because the glove becomes too hard if too much is added.
The amount of the divalent metal oxide, for example zinc oxide, and / or the aluminum complex added is usually 2.0 parts by weight or less, preferably 2.0 parts by weight or less, based on 100 parts by weight of the elastomer in the composition for dip molding. It is preferably 0 parts by weight or less, and is substantially not added from the viewpoint of improving the stress retention rate. Substantially no addition means that their content in the dip molding composition is below the detection limit.

In order to use aluminum as a cross-linking agent, it is necessary to add it to the XNBR latex in a neutral to weakly basic solution when compounding.
However, when the aqueous solution of the aluminum salt is neutral to weakly basic, it becomes a gel of aluminum hydroxide and cannot be used as a cross-linking agent. In order to solve this problem, a method using a polybasic hydroxycarboxylic acid as a ligand can be considered. As the polybasic hydroxycarboxylic acid here, aqueous solutions of citric acid, malic acid, tartaric acid, lactic acid and the like can be used.
Among these, malic acid is preferably used as a ligand from the viewpoint of tensile strength and fatigue durability of gloves, and citric acid is preferably used as a ligand from the viewpoint of stability of an aqueous aluminum solution.

(8) Other components The composition for dip molding contains the above-mentioned components and water, and usually contains other optional components. The content of water in the composition for dip molding can usually be 78 to 92% by weight.

The composition for dip molding may further contain a dispersant. As the dispersant, an anionic surfactant is preferable, and for example, a carboxylate, a sulfonate, a phosphate, a polyphosphoric acid ester, a polymerized alkylarylsulfonate, a polymerized sulfonated naphthalene, and a polymerized naphthalene / formaldehyde Condensation polymers and the like are mentioned, and sulfonates are preferably used.

Commercially available products can be used as the dispersant. For example, "Tamol NN9104" manufactured by BASF may be used. The amount used is preferably about 0.5 to 2.0 parts by weight with respect to 100 parts by weight of the elastomer in the dip molding composition.

The composition for dip molding can further contain various other additives. Examples of the additive include antioxidants, pigments, chelating agents and the like. As the antioxidant, a hindered phenol type antioxidant, for example, WingstayL can be used. Further, as the pigment, for example, titanium dioxide is used. As the chelating agent, sodium ethylenediaminetetraacetate or the like can be used.

The dip molding composition of the present embodiment is a conventional mixture of elastomers, epoxy crosslinkers, polycarbodiimides, pH adjusters, and water, and if necessary, additives such as moisturizers, dispersants, and antioxidants. It can be made by mixing by means, for example, a mixer or the like.

2. 2. Glove Manufacturing Method The glove of the present embodiment can be preferably manufactured by the following manufacturing method.
That is,
(1) Coagulant adhesion step (step of adhering coagulant to glove molding mold),
(2) Maturation step (step of adjusting and stirring the composition for dip molding),
(3) Dip molding step (step of immersing the glove molding die in the dip molding composition),
(4) Gelling step (step of gelling the film formed on the glove molding to make a cured film precursor),
(5) Reaching step (step of removing impurities from the cured film precursor formed on the glove molding die),
(6) Beading process (process of making a roll around the cuffs of gloves),
(7) Precure ring step (step of heating and drying the cured film precursor at a lower temperature than the curing step) However, this step is an optional step.
(8) Curing step (step of heating and drying at the temperature required for the cross-linking reaction)
This is a method for manufacturing gloves, which comprises the above steps (3) to (8) in the above order.
The above-mentioned manufacturing method also includes a method of manufacturing gloves by so-called double dipping, in which the steps (3) and (4) are repeated twice.

In the present specification, the cured film precursor is a film composed of an elastomer aggregated on a glove molding by a coagulant in a dipping step, and calcium is dispersed in the film in a subsequent gelling step. A film that has been gelled to some extent and has not been finally cured.

Details will be described below for each step.
(1) Coagulant Adhesion Step (a) A mold or former (glove molding type) is contained in a coagulant solution containing 5 to 40% by weight, preferably 8 to 35% by weight of Ca ²⁺ ions as a coagulant and a gelling agent. Soak in. Here, the time for adhering the coagulant or the like to the surface of the mold or former is appropriately determined, and is usually about 10 to 20 seconds. As the coagulant, calcium nitrate or chloride is used. Other inorganic salts having the effect of precipitating the elastomer may be used. Above all, it is preferable to use calcium nitrate. This coagulant is usually used as an aqueous solution containing 5 to 40% by weight.
The solution containing the coagulant preferably contains potassium stearate, calcium stearate, mineral oil, ester-based oil, or the like as a release agent in an amount of about 0.5 to 2% by weight, for example, about 1% by weight.
(B) The mold or former to which the coagulant solution is attached is placed in an oven having a furnace temperature of about 110 ° C. to 140 ° C. for 1 to 3 minutes and dried to allow the coagulant to adhere to the entire surface or a part of the glove molding mold. At this time, it should be noted that the surface temperature of the hand mold after drying is about 60 ° C., which affects the subsequent reaction.
(C) Calcium contributes not only to the coagulant function for forming a film on the surface of the glove molding mold, but also to the cross-linking function of a considerable part of the finally completed glove. The metal cross-linking agent added later can be said to reinforce the weakness of the cross-linking function of calcium.

(2) Maturation Step (a) As described in the section of pH adjuster for dip molding composition, the dip molding composition according to the embodiment of the present invention is adjusted to pH 9.5 to 12.0. This is the step of stirring. It is considered that the components in the dip molding composition are dispersed and homogenized by this step.
(B) In the actual manufacturing process of gloves, since this process is usually performed in a large-scale tank, maturation may take about 24 hours. This is poured into a dip tank and dipping is performed, but it is added as the water level in the dip tank drops.

(3) Diping Step In the maturation step, the dip molding composition (dip liquid) according to the embodiment of the present invention that has been stirred is poured into a dip tank, and the coagulant is adhered into the dip tank in the coagulant adhering step. This is a step of immersing the dried mold or former for 1 to 60 seconds under a temperature condition of 25 to 35 ° C.
In this step, the calcium ions contained in the coagulant agglomerate the elastomer contained in the dip molding composition on the surface of the mold or former to form a film.

(4) Gelling step (a) In the conventional sulfur cross-linked gloves, it was common sense to heat to nearly 100 ° C. in a gelling oven. This was because the cross-linking of the latex was slightly advanced and the film gelled to a certain extent so as not to be deformed during the subsequent leaching. At the same time, it also had the purpose of dispersing calcium in the membrane and later sufficient for calcium cross-linking.
On the other hand, as the gelling condition when the polycarbodiimide and the epoxy cross-linking agent are used as in the present invention, the condition for preventing the polycarbodiimide from drying and opening the ring is used.
Usually, it takes 20 seconds or more in a temperature range of about 20 ° C. to 70 ° C.
This condition is a condition when KOH is used as the pH adjuster, and when an ammonia compound or an amine compound is used as the pH adjuster, a condition different from this may be adopted.
(B) The gelling conditions when using an epoxy cross-linking agent in general mass production include that the mold or former already has a certain temperature, and that the ambient temperature in the factory is often about 50 ° C. It is determined from. Furthermore, regarding the upper limit of the temperature of the gelling process, in order to improve the quality, it is assumed that the temperature is intentionally heated.
In addition, the time of the gelling step can usually be 1 minute 30 seconds to 4 minutes.

(5) Reaching Step (a) The leaching step is a step of washing and removing calcium precipitated on the surface of the cured film precursor and impurities that interfere with subsequent curing such as excess water-soluble substances. Usually, the former is brought into contact with warm water at 40 to 60 ° C. for about 1.5 to 4 minutes. As a specific contact method, immersion in water can be mentioned.
(B) When the composition for dip molding contains zinc oxide and / or an aluminum complex as a metal cross-linking agent, another role of the leaching step is to wash the cured film precursor which has been adjusted to be alkaline with water. The purpose is to bring the zinc oxide or aluminum complex ions contained in the cured film precursor into Zn ²⁺ and Al ³⁺ so that metal crosslinks can be formed in the subsequent curing step.

(6) Beading step This is a step of winding up the cuff end of the glove of the cured film precursor for which the leaching step has been completed to make a ring having an appropriate thickness and reinforcing it. When performed in a wet state after the leaching step, the adhesiveness of the roll portion is good.

(7) Precure ring step (a) After the beading step, the cured film precursor is heated and dried at a lower temperature than the subsequent curing step. Usually, in this step, heating and drying are performed at 60 to 90 ° C. for about 30 seconds to 5 minutes. If the high-temperature curing process is performed without going through the pre-curing process, the water will evaporate rapidly and convex parts like swelling may be formed on the gloves, which may impair the quality, but without going through this process. You may move to the curing process.
(B) The temperature may be raised to the final temperature of the curing step without going through this step, but if curing is performed in multiple drying furnaces and the temperature of the first-stage drying furnace is slightly lowered, this first step Dry eyes correspond to the precuring process.

(8) Curing step (a) The curing step is a step of heating and drying at a high temperature to finally complete cross-linking and form a cured film as a glove. Gloves using polycarbodiimide and an epoxy cross-linking agent are insufficiently cross-linked unless they are at a high temperature. Therefore, they are heated and dried at 90 to 150 ° C. for 10 to 30 minutes, preferably about 15 to 30 minutes. A preferable temperature in the curing step is 100 to 140 ° C.
(A) In this curing step, the cross-linking of the glove is completed, and the glove is formed by cross-linking the carboxyl group of XNBR with calcium, cross-linking with polycarbodiimide, and cross-linking with an epoxy cross-linking agent.

(9) Regarding the method for manufacturing double dipping gloves, so-called single dipping has been described above. On the other hand, the dipping step and the gelling step may be performed twice or more, and this is usually called double dipping.
Double dipping is performed for the purpose of preventing the formation of pinholes when manufacturing thick gloves (thickness of more than 200 to 300 μm) and also in the manufacturing method of thin gloves.

3. 3. Gloves (1) Structure of gloves in the present embodiment The gloves in the first embodiment are of an elastomer containing (meth) acrylonitrile-derived structural units, unsaturated carboxylic acid-derived structural units, and butadiene-derived structural units in the polymer main chain. The elastomer is a glove made of a cured film, and the elastomer has a crosslinked structure of a carboxyl group of a structural unit derived from an unsaturated carboxylic acid, a polycarbodiimide, and an epoxy compound.
In addition to this, this glove also has a crosslinked structure of calcium derived from a coagulant and a carboxyl group.
This glove can preferably be produced using the above-mentioned dip molding composition of the present embodiment. The elastomer preferably contains 12 to 36% by weight of structural units derived from (meth) acrylonitrile, 2 to 10% by weight of structural units derived from unsaturated carboxylic acid, and 50 to 75% by weight of structural units derived from butadiene. ..
The glove in the second embodiment has a crosslinked structure of a carboxyl group of an elastomer and zinc and / or aluminum in addition to the crosslinked structure of the first embodiment.

In the present invention, in the above embodiment, by curing the dip molding composition containing both the polycarbodiimide and the epoxy cross-linking agent, gloves having good tensile strength, fatigue durability and stress retention can be produced. ..
The film thickness of the glove according to the embodiment of the present invention may be, but is not limited to, 0.04 to 0.2 mm. Within this film thickness range, more than 0.09 to 0.2 mm (more than 90 to 200 μm) is the range of normal thickness of commercially available gloves.
On the other hand, the gloves according to the first embodiment are particularly effective in producing thick gloves (thickness over 200 to 300 μm). This is because if the film thickness is thick, tensile strength, fatigue durability, and the like can be obtained.
On the other hand, as the glove in the second embodiment, the weak point of calcium cross-linking may be supplemented with zinc and / or aluminum cross-linking. Although the strength as the initial performance can be maintained by the calcium cross-linking, the drawback of easily causing a decrease in strength due to the elution of calcium in salt water and easily permeating chemicals can be compensated by the zinc and / or aluminum cross-linking.
The gloves according to the second embodiment are particularly preferable when producing ultra-thin to thin gloves (thickness 40 to 90 μm).
As described above, the glove according to the second embodiment can change the performance of the glove by changing the ratio of epoxy cross-linking, calcium cross-linking, zinc and / or aluminum cross-linking.

(2) Features of gloves according to the embodiment of the present invention (a) Gloves according to the embodiment of the present invention, like other vulcanization accelerator-free gloves, have sulfur and vulcanization promotion like conventional XNBR gloves. Since it contains virtually no agent, it is characterized by not causing type IV allergy. However, since sulfur is contained in the surfactant and the like during the production of the elastomer, a very small amount of sulfur may be detected.

(B) Generally, as the physical properties of gloves, tensile strength, elongation, and fatigue durability are usually observed. In the present invention, the tensile strength is measured by a tensile test described later and is currently on the market. The lower limit of 20 MPa of the actual product is set as the acceptance standard. As a passing standard for the tensile strength of gloves, the European standard (EN 455) states that the load at break is 6 N or more.
Regarding the elongation of gloves, the elongation at break during the tensile test described later is within the range of 500 to 750%, the 100% modulus (tensile stress at 100% elongation) is within the range of 3 to 10 MPa, and the fatigue durability is the finger crotch. The acceptance criteria are 90 minutes or more for the part (equivalent to 240 minutes or more for the palm).
The gloves according to the embodiment of the present invention satisfy the above physical characteristics.

(C) A metal cross-linking agent such as zinc and / or aluminum is further added to the dip molding composition used for producing the glove according to the second embodiment of the present invention, whereby a person at the time of wearing is added. It is possible to obtain gloves with enhanced chemical impermeableness by preventing the decrease in strength due to sweat.

1. 1. Implementation Method Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to these Examples. Unless otherwise specified, "%" is "% by weight" and "part" is "part by weight".
Further, in the following description, "parts by weight" indicates, in principle, the number of parts by weight with respect to 100 parts by weight of the elastomer.
The number of parts by weight of each additive is based on the solid content, and the number of parts by weight of the epoxy cross-linking agent is based on the total weight of the cross-linking agent.
The types of XNBR and epoxy cross-linking agent used in the dip molding composition are described in each table.

(1) XNBR used
The characteristics of XNBR used in this experimental example are shown in Table 1.

The characteristics of XNBR used in this experimental example were measured as follows.
<Acrylonitrile (AN) residue amount and unsaturated carboxylic acid (MMA) residue amount>
Each of the above elastomers was dried to prepare a film. The film was measured by FT-IR, absorbance at absorption wave 1699Cm ^-1 derived from absorption wave 2237 cm-1 and carboxylic acid groups derived from acrylonitrile based seeking (Abs), acrylonitrile (AN) residues weight and unsaturated The amount of carboxylic acid (MMA) residue was determined.
The amount of acrylonitrile residue (%) was determined from a calibration curve prepared in advance. The calibration curve was prepared from a sample in which polyacrylic acid was added as an internal standard substance to each elastomer and the amount of acrylonitrile groups was known. The amount of unsaturated carboxylic acid residue was calculated from the following formula.
Unsaturated carboxylic acid residue amount (wt%) = [Abs (1699 cm ^-1 ) / Abs (2237 cm ^-1 )] /0.2661
In the above formula, the coefficient 0.2661 is a converted value obtained by preparing a calibration curve from a plurality of samples in which the ratio of the unsaturated carboxylic acid group amount and the acrylonitrile group amount is known.

<Moony viscosity (ML _{(1 + 4)} 100 ° C)>
With 200 ml of a saturated aqueous solution of a 4: 1 mixture of calcium nitrate and calcium carbonate stirred at room temperature, each elastomer latex was added dropwise with a pipette to precipitate solid rubber. The obtained solid rubber is taken out, and after repeating stirring and washing with about 1 L of ion-exchanged water 10 times, the solid rubber is squeezed and dehydrated, and vacuum dried (60 ° C., 72 hours) to prepare a rubber sample for measurement. did. The obtained rubber for measurement was passed through a 6-inch roll having a roll temperature of 50 ° C. and a roll gap of about 0.5 mm several times until the rubber was collected, and JIS K6300-1: 2001 "Unvulcanized rubber-physical". Measurement was performed using a large-diameter rotating body at 100 ° C. in accordance with "Characteristics, Part 1 How to determine viscosity and vulcanization time by Mooney viscometer".

<MEK insoluble amount>
The MEK (methyl ethyl ketone) insoluble (gel) component was measured as follows. A 0.2 g XNBR latex dried product sample was placed in a weighed mesh basket (80 mesh), immersed in 80 mL of MEK solvent in a 100 mL beaker together with the basket, and the beaker was covered with Parafilm. Allowed for hours in the draft. Then, the mesh basket was taken out from the beaker, suspended in the air in the draft, and dried for 1 hour. This was dried under reduced pressure at 105 ° C. for 1 hour, then weighed, and the weight of the basket was subtracted to obtain the weight after immersion of the XNBR latex dried product.
The content (insoluble amount) of the MEK insoluble component was calculated from the following formula.
Insoluble component content (% by weight) = (weight g after immersion / weight g before immersion) × 100
The XNBR latex dried product sample was prepared as follows. That is, after stirring the XNBR latex at a rotation speed of 500 rpm for 30 minutes in a 500 mL bottle, 14 g of the latex was weighed in a 180 × 115 mm stainless steel vat, and the latex was 23 ° C. ± 2 ° C. and humidity 50 ± 10 RH% for 5 days. It was dried to obtain a cast film, and the film was cut into 5 mm squares to prepare an XNBR latex dried product sample.

(2) Epoxy cross-linking agent used Table 2 shows the epoxy cross-linking agent used in this experimental example.

The epoxy equivalent is based on the catalog value of each company, and the average number of epoxy groups is an analytical value.

<MIBK / water distribution rate>
Methyl isobutyl ketone (MIBK) / water partition rate (%) is a value measured to confirm how much the epoxy cross-linking agent moves to the MIBK layer in an environment similar to that in a latex solution.
The reason why MIBK was used as the organic layer is that the physical properties of latex are similar to those of methyl ethyl ketone (MEK), so it is thought that the properties are similar to MEK, the solubility in water is lower than MEK, and the layer can be clearly separated. Because it was done.

The MIBK / water distribution ratio was measured by the following procedure.
1. 1. Accurately weigh 5.0 g of pure water and 5.0 g of methyl isobutyl ketone (MIBK) in a hole screw cap test tube (φ16.5 × 105 × φ10.0 12 mL NR-10H manufactured by Maruem), and crosslinker sample 0. Add 5 g and stir (3 minutes) at room temperature (23 ± 2 ° C.) to mix well.
2. 2. Centrifuge (manufactured by Kokusan Co., Ltd., desktop centrifuge H-103N) is subjected to a condition of 3000 rpm for 10 minutes (1.0 × 10 ³ G) to separate the aqueous layer and the MIBK layer.
3. 3. Separate and weigh the separated MIBK layer into a disposable cup with a Pasteur pipette.
4. The MIBK / water distribution ratio is calculated by the following formula.
MIBK / water distribution rate (%) = (MIBK layer weight after distribution (g) -MIBK weight before distribution (g)) / (crosslinking agent addition weight (g)) × 100
5. This measurement was performed three times, the average value was calculated, and the value was used as the value of MIBK / water distribution rate.
In addition, procedure 2. A vortex mixer (manufactured by Scientific Industries, Inc., standard model, VORTEX-GENIE 2 Mixer) was used for stirring.

(3) Polycarbodiimide used The polycarbodiimide used in this example is mainly V-02-L2 manufactured by Nisshinbo Chemical Co., Ltd. Its physical characteristics are as follows.
Average particle size: 11.3 nm
Number average molecular weight: 3600
Number of carbodiimide functional groups per molecule: 9.4

(4) Preparation and Evaluation of Cured Film (a) Preparation of Dip Molding Composition To 250 g of the XNBR solution shown in Table 1, 100 g of water was added to dilute and stirring was started.
Then, the pH was preliminarily adjusted to 9.2 to 9.3 using a 5 wt% potassium hydroxide aqueous solution.
A mixture of 1.0 part by weight of the epoxy cross-linking agent shown in Table 2 and 1.0 part by weight of diethylene glycol, and 0.5 part by weight of the polycarbodiimide of (3) above were added to the above solution.
Further, 0.2 parts by weight of the antioxidant (“CVOX-50” (solid content 53%) manufactured by Farben Technique (M)), 1.0 part by weight of zinc oxide (manufactured by Farben Technique (M)), trade name “ CZnO-50 ”) and 1.5 parts by weight of titanium oxide (“PW-601” (solid content 71%) manufactured by Farben Technique (M)) were added, and the mixture was stirred and mixed overnight (16 hours). Then, after adjusting the pH to 10 to 10.5 using a 5 wt% potassium hydroxide aqueous solution, the solid content concentration of the dip molding composition was adjusted to 22% by adding water, and the beaker was used until it was used. Stirring was continued in the inside to obtain a composition for dip molding.
The solid content concentration is for adjusting the film thickness by combining with the calcium concentration of the coagulation liquid. In this case, the solid content concentration of 22% is the film thickness of the coagulation liquid of 20%. It can be adjusted to 80 μm.

(B) Preparation of coagulating liquid CRESTAGE INDUSTRY "S-9" (S-9) as a release agent in a liquid prepared by dissolving 0.56 g of a surfactant "Teric 320" manufactured by Huntsman Corporation in 42.0 g of water. 19.6 g (solid content concentration 25.46%) was diluted about 2-fold with a portion of 30 g of pre-weighed water and then slowly added. Rinse the S-9 remaining in the container with the remaining water, add the whole amount, and stir for 3 to 4 hours to prepare an S-9 dispersion.
143.9 g of calcium nitrate tetrahydrate dissolved in 153.0 g of water was prepared in another beaker, and the S-9 dispersion prepared above was added to the aqueous calcium nitrate solution with stirring.
Adjust the pH to 8.5 to 9.5 with 5% aqueous ammonia, and finally add water so that calcium nitrate has a solid content concentration of 20% as an anhydride and S-9 has a solid content concentration of 1.2%. 500 g of coagulant was obtained. The obtained coagulant was continuously stirred in a 1 L beaker until it was used.

(C) Adhesion of coagulant to porcelain plate The coagulant is heated to about 50 ° C. with stirring, filtered through a 200 mesh nylon filter, placed in a dipping container, washed, and then warmed to 70 ° C. (200 x 80 x 3 mm, hereinafter referred to as "porcelain plate") was immersed. Specifically, after the tip of the porcelain plate came into contact with the liquid surface of the coagulating liquid, the porcelain plate was immersed at a position 18 cm from the tip of the porcelain plate for 4 seconds, held for 4 seconds while being immersed, and withdrawn over 3 seconds. .. The coagulant adhering to the surface of the ceramic plate was quickly shaken off to dry the surface of the ceramic plate. The dried porcelain plate was warmed again to 70 ° C. in preparation for dipping in the dip molding composition (latex).

(D) Production of Cured Film The dip molding composition was filtered through a 200 mesh nylon filter at room temperature, placed in a dipping container, and immersed in a porcelain plate at 60 ° C. to which the coagulating liquid was attached. Specifically, the porcelain plate was immersed for 6 seconds, held for 4 seconds, and withdrawn over 3 seconds. The dip molding composition was held in the air until it did not drip, and the latex droplets adhering to the tip were gently shaken off.
A porcelain plate immersed in the dip molding composition was left at 50 ° C. for 2 minutes to prepare a cured film precursor. (Gering).
The cured film precursor was then leached with deionized water at 50 ° C. for 2 minutes.
The film was dried at 70 ° C. for 5 minutes (precuring) and mainly thermoset at 140 ° C. for 30 minutes (curing).
The obtained cured film was peeled off cleanly from the ceramic plate and stored in an environment of 23 ° C. ± 2 ° C. and a humidity of 50% ± 10% until it was subjected to a physical characteristic test.

(E) Evaluation of cured film <tensile strength, modulus and elongation>
The tensile strength, modulus and elongation of the dip molded article were measured according to the method described in ASTM D412. The dip molded product was punched out using DieC manufactured by Dumbbell Co., Ltd. to prepare a test piece. The test piece is measured using a TENSILON universal tensile tester RTC-1310A manufactured by A & D Co., Ltd. at a test speed of 500 mm / min, a distance between chucks of 75 mm, and a distance between marked lines of 25 mm.
As for the physical characteristics of gloves, the tensile strength is considered to be 14 MPa or more, and the elongation rate is considered to be 500% or more.
Regarding the modulus, especially from the viewpoint of satisfying the flexibility that does not hinder the movement of the finger when wearing gloves, the modulus at the time of 100% elongation (100% modulus) and the modulus at the time of 300% elongation (300%). We focused on the modulus (500% modulus) at the time of 500% elongation.

<Fatigue durability>
A JIS K6251 No. 1 dumbbell test piece was cut out from the cured film, and this was mixed with an artificial sweat solution (20 g of sodium chloride, 17.5 g of ammonium chloride, 17.05 g of lactic acid, 5.01 g of acetic acid in 1 liter, and an aqueous sodium hydroxide solution. The pH was adjusted to 4.7), and the fatigue durability was evaluated using the above-mentioned durability test apparatus.
That is, 15 mm from each of the two ends of the 120 mm long dumbbell test piece was sandwiched between the fixed chuck and the movable chuck, and 60 mm from the bottom of the test piece on the fixed chuck side was immersed in the artificial sweat solution. After moving the movable chuck to the minimum position (relaxed state) of 147 mm (123%) and holding it for 11 seconds, the test piece reaches the maximum position (extended state) of 195 mm (163%) and the minimum again. It was moved to the position (relaxed state) over 1.8 seconds, and a cycle test was conducted with this as one cycle. The time of one cycle was 12.8 seconds, and the time (minutes) of fatigue durability was obtained by multiplying by the number of cycles until the test piece broke.
The fatigue durability is preferably 240 minutes or more from the viewpoint of practical use as gloves.

<Stress retention rate>
A test piece is prepared from the cured film using a punching cutter (Super Straight Cutter SK-1000-D manufactured by Dumbbell) according to the strip No. 2 specified in JIS K 6263, and the speed is 100 mm at both ends of the test piece. Tensile stress was applied at / min or 500 mm / min, and when the test piece stretched twice (100%), stretching was stopped and tensile stress M100 (0) was measured, and 6 minutes passed as it was. The subsequent tensile stress M100 (6) was measured. Then, the percentage of M100 (6) with respect to M100 (0) was defined as the stress retention rate.
The higher the stress retention rate, the higher the stress is maintained after stretching, and the higher the elastic deformation force that tries to return to the original shape when the external force is removed, the fit of the glove and the hem. The tightening of the part is improved and wrinkles are reduced.
As for the stress retention rate measured by the above method, since the stress retention rate of the conventional sulfur-crosslinked XNBR glove is in the 30% range, if the molded product of the present embodiment is 50% or more, it is good as an XNBR glove. More preferably, it is 60% or more.

From the results of Experimental Examples 1 and 2, it was possible to obtain a dip molded product having good tensile strength, elongation, fatigue durability, and stress retention even when the cross-linking agent did not contain a metal cross-linking agent (zinc). .. The commercially available sulfur-crosslinked gloves have a stress retention rate of about 40% and a 500% modulus of about 30 MPa, and the dip molded product of the present invention has a clearly higher stress retention rate and a lower 500% modulus. A low 500% modulus means a low tensile stress at 500% elongation and a high flexibility.

Claims (11)

1. Elastomers containing structural units derived from (meth) acrylonitrile, structural units derived from unsaturated carboxylic acids, and structural units derived from butadiene in the polymer main chain, polycarbodiimides, epoxy crosslinkers, water, and pH adjusters. A composition for dip molding containing at least
   In the elastomer, the structural unit derived from (meth) acrylonitrile is 12 to 36% by weight, the structural unit derived from unsaturated carboxylic acid is 2 to 10% by weight, and the structural unit derived from butadiene is 50 to 75% by weight.
   The epoxy cross-linking agent contains an epoxy cross-linking agent containing an epoxy compound having three or more epoxy groups in one molecule.
   The polycarbodiimide is a composition for dip molding, which comprises at least one polycarbodiimide containing a hydrophilic segment in the molecular structure.
2. The composition for dip molding according to claim 1, wherein the MIBK / water distribution ratio according to the following measuring method of the epoxy cross-linking agent is 27% or more.
   MIBK / water distribution rate measurement method: 5.0 g of water, 5.0 g of methyl isobutyl ketone (MIBK) and 0.5 g of epoxy cross-linking agent are precisely weighed in a test tube, stirred at 23 ° C ± 2 ° C for 3 minutes, and mixed. Centrifuge at 1.0 × 10 ³ G for 10 minutes to separate into an aqueous layer and a MIBK layer. Next, the MIBK layer is separated and weighed, and the MIBK / water distribution ratio is calculated by the following formula.
   MIBK / water distribution rate (%) = (MIBK layer weight after distribution (g) -MIBK weight before distribution (g)) / crosslinker addition weight (g) x 100
   The above measurement is performed three times, and the average value is taken as MIBK / water distribution ratio.
3. The dip molding composition according to claim 1 or 2, wherein the pH adjuster is an alkali metal hydroxide.
4. The composition for dip molding according to any one of claims 1 to 3, further comprising a dispersant for an epoxy cross-linking agent.
5. The dispersant of the epoxy cross-linking agent is a monohydric lower alcohol, a glycol represented by the following formula (1), an ether represented by the following formula (2), and an ester represented by the following formula (3). The composition for dip molding according to claim 4, which is one or more selected from the group consisting of.
   HO- (CH ₂ CHR ^1- O) _n1- H (1)
   [In formula (1), R ¹ represents a hydrogen or methyl group, and n1 represents an integer of 1 to 3. ]
   R ² O- (CH ₂ CHR ^1- O) _n2- R ³ (2)
   [In formula (2), R ¹ represents a hydrogen or methyl group, R ² represents an aliphatic hydrocarbon group having 1 to 5 carbon atoms, and R ³ represents hydrogen or an aliphatic hydrocarbon group having 1 to 3 carbon atoms. It represents a hydrocarbon group, and n2 represents an integer of 0 to 3. ]
   R ² O- (CH ₂ CHR ^1- O) _n3- (C = O) -CH ₃ (3)
   [In formula (3), R ¹ represents a hydrogen or methyl group, R ² represents an aliphatic hydrocarbon group having 1 to 5 carbon atoms, and n 3 represents an integer of 0 to 3. ]
   
6. The amount of the epoxy cross-linking agent added to the dip molding composition is 0.2 parts by weight or more and 5.0 parts by weight or less with respect to 100 parts by weight of the elastomer contained in the dip molding composition, and is used for dip molding. Any of claims 1 to 5, wherein the amount of polycarbodiimide added to the composition is 0.2 parts by weight or more and 5.0 parts by weight or less with respect to 100 parts by weight of the elastomer contained in the composition for dip molding. The composition for dip molding according to item 1.
7. The dip molding composition according to any one of claims 1 to 6, wherein the zinc oxide content in the dip molding composition is 0.5 parts by weight or less with respect to 100 parts by weight of the elastomer. ..
8. (1) A step of immersing a glove mold in a coagulant solution containing calcium ions to attach the coagulant to the glove mold.
   (2) The step of stirring the dip molding composition according to any one of claims 1 to 7, wherein the pH is adjusted to 9.5 to 12.0 with a pH adjuster.
   (3) The glove molding mold to which the coagulant of (1) is attached is immersed in the dip molding composition that has undergone the step (2), and the dip molding composition is coagulated in the glove molding mold to form a film. Dipping process to form,
   (4) A gelling step of gelling a film formed on a glove molding mold to prepare a cured film precursor.
   (5) A leaching step of removing impurities from the cured film precursor formed on the glove molding mold,
   (6) A beading step of making a roll around the cuffs of a glove after the leaching step.
   (7) A curing step of heating and drying the cured film precursor to obtain a cured film.
   A method for manufacturing gloves, which comprises the above steps (3) to (7) in the above order.
9. The glove manufacturing method according to claim 8, wherein the steps (3) and (4) above are repeated twice in that order.
10. 8. The method according to claim 8 or 9, further comprising a precuring step of heating and drying the cured film precursor at a temperature lower than the temperature of the step (7) between the steps (6) and (7). How to make gloves.
11. Gloves manufactured by the manufacturing method according to any one of claims 8 to 10.

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