WO2021010343A1

WO2021010343A1 - Crosslinking agent for dip molding, composition for dip molding and glove

Info

Publication number: WO2021010343A1
Application number: PCT/JP2020/027114
Authority: WO
Inventors: 憲秀榎本; 充志森永
Original assignee: ミドリ安全株式会社
Priority date: 2019-07-12
Filing date: 2020-07-10
Publication date: 2021-01-21
Also published as: JPWO2021010343A1

Abstract

The first problem addressed by the present invention is to produce a glove having excellent tensile strength, elongation and fatigue endurance with use of a halohydrin crosslinking agent, which has not been used in the field of conventional external crosslinking agent-type gloves, while using no vulcanization accelerator. The second problem addressed by the present invention is to produce a glove having excellent stress retention ratio and good elongation at the same time, while ameliorating weaknesses of conventional sulfur-vulcanized XNBR gloves. A crosslinking agent for dip molding, which contains a halohydrin compound having at least two halohydrin groups D represented by formula (I) in each molecule. In formula (I), R¹ represents a hydrogen atom or an alkyl group; and X represents a halogen group.

Description

Dip molding cross-linking agent, dip molding composition, and gloves

The present invention is a dip molding cross-linking agent (hereinafter, also referred to as "halohydrin cross-linking agent") which is a compound having two or more halohydrin groups for a carboxylic acid-modified NBR latex, and a dip containing at least the dip molding cross-linking agent. The present invention relates to a molding composition, a method for producing a glove using the dip molding composition, and a glove.

A water-based emulsion containing a carboxylic acid-modified acrylonitrile butadiene rubber (XNBR) as an elastomer is produced in large quantities as a material for dip molding, and synthetic rubber gloves are particularly used.
When acrylonitrile butadiene rubber is used, it lacks practical strength and properties. Therefore, these elastomers are further copolymerized with an unsaturated carboxylic acid monomer and used as XNBR. The X indicates that an unsaturated carboxylic acid is added as a component of the copolymerization.

Generally, a dip molded product produced from an aqueous emulsion containing XNBR as an elastomer is formed from a crosslinked structure of covalent bonds of butadiene, sulfur and a vulcanization accelerator, and a crosslinked structure of ionic bonds of a carboxyl group and zinc. Consists of film.
This glove has excellent heat resistance and chemical resistance, but has a shorter molecular chain than natural rubber and isoprene / chloroprene synthetic rubber gloves, has fewer double bonds that represent the original properties of rubber, and has weak bonding strength. Since it also contains bonds and acrylonitrile to increase strength, the stress retention rate is as low as about 40%, and if the crosslink density is increased to increase this, the elongation rate will decrease. It was.
In addition, the vulcanization accelerator used in the production of the above dip molded products is included in the "Japanese standard allergen" defined by the Japan Society for Skin Allergy and Contact Dermatitis, and allergies develop in applications such as gloves. Multiple cases have been reported. From these case reports, it is considered that the vulcanization accelerator is an allergen for delayed-type allergy (Type IV) in XNBR gloves.

A vulcanization accelerator is indispensable for the cross-linking reaction (vulcanization) with sulfur from the viewpoint of economy and performance, but since it is considered to be the main cause of delayed allergy, sulfur and sulfurization are widely used. Cross-linking technology that does not use a sulfur accelerator is being studied and put into practical use.
Sulfur and vulcanization accelerator-free gloves include, for example, self-crosslinking gloves in which an organic crosslinkable compound is contained during latex polymerization, or an external crosslinking agent type that crosslinks with polycarbodiimide or an epoxy crosslinking agent having an epoxy group. Gloves etc. have been developed. In each of these, the unsaturated carboxylic acid was covalently bonded with the above-mentioned organic cross-linking agent or the organic cross-linking compound, and the metal cross-linking agent was used for ionic bonding.
As a self-crosslinking type glove, Patent Document 1 contains a polymer having a specific structural unit and a specific reactive group as a latex, so that it can be covalently bonded to a carboxyl group without adding a cross-linking agent. Gloves made with an elastomeric composition are disclosed.
As an external cross-linking agent type glove, Patent Document 2 discloses a glove manufactured by using an elastomer having a specific structural unit as a latex and an emulsion composition for a glove containing polycarbodiimide as a cross-linking agent. Patent Document 3 discloses a glove manufactured by using an elastomer having a specific structural unit as a latex and a dip molding composition containing a trivalent or higher valent epoxy compound as a cross-linking agent.

International Publication No. 2012/043894 International Publication No. 2018/117109 International Publication No. 2019/102985

In the present invention, a halohydrin cross-linking agent, which has not been used in the field of conventional gloves of the external cross-linking agent type, is used and is excellent in tensile strength, elongation, and fatigue durability without using a vulcanization accelerator. The first task was to make gloves, and the second task was to improve the weaknesses of conventional sulfur-vulcanized XNBR gloves and to make gloves with excellent stress retention and at the same time good elongation. Regarding the first problem and the second problem, the first problem is set as a problem to be solved at least, and the second problem is set as a problem that is desired to be further solved. It is an issue.

By using a copolymer having an unsaturated carboxylic acid as a constituent unit as the elastomer and halohydrin as a cross-linking agent, the present inventors react the halohydrin with the carboxyl group present in the elastomer. It was thought that crosslinks could be formed within and / or between the elastomeric particles. Furthermore, by using halohydrin, which has a higher affinity for water than the elastomer, the halohydrin can be reacted with the carboxyl group existing on the surface of the elastomer particles to form a crosslink between the elastomer particles. It was considered that by using halohydrin, which has a higher oiliness than the elastomer, the halohydrin can be reacted with the carboxyl group existing in the elastomer particles to form a crosslink in the elastomer particles. As a result of diligent studies based on this idea, it was found that the above-mentioned problems can be solved by using halohydrin as a cross-linking agent for dip molding, and the present invention has been completed.
In addition, we tried to solve the above problems by using it in combination with other organic cross-linking agents and metal cross-linking agents.

That is, the gist of the present invention is as follows.
[1] A cross-linking agent for dip molding, which contains a halohydrin compound having at least two halohydrin groups D represented by the following formula (I) in one molecule.

In the above formula (I), R ¹ is a hydrogen or alkyl group, and X is a halogen group.
[2] The cross-linking agent for dip molding according to the above [1], wherein the halohydrin compound is a halohydrin compound having at least one halohydrin group Da represented by the following formula (Ia) in the molecule as the halohydrin group D. ..

In the above formula (Ia), R ¹ is a hydrogen or alkyl group, and X is a halogen group.
[3] The cross-linking agent for dip molding according to the above [2], wherein the halohydrin compound is a halohydrin compound represented by the following formula (II).

In the above formula (II), R ² is a (k + m) -valent aliphatic hydrocarbon group having 2 to 10 carbon atoms, X is a halogen group, and k and m are 2 ≦ k ≦ 6,0. It is an integer that satisfies ≦ m ≦ 4 and 2 ≦ k + m ≦ 6.
[4] An elastomer containing a (meth) acrylonitrile-derived structural unit, an unsaturated carboxylic acid-derived structural unit, and a butadiene-derived structural unit in the polymer main chain, and the dip according to any one of the above [1] to [3]. A composition for dip molding, which comprises a cross-linking agent for molding.
[5] The composition for dip molding according to the above [4], wherein the structural unit derived from (meth) acrylonitrile is 12 to 35% by weight and the structural unit derived from unsaturated carboxylic acid is 2 to 10% by weight in the elastomer. Stuff.
[6] The composition for dip molding according to the above [4] or [5], which further contains an epoxy cross-linking agent containing an epoxy compound having at least three epoxy groups in one molecule.
[7] A glove which is a cured product of the dip molding composition according to any one of the above [4] to [6].
[8] (1) Coagulation and adhesion step of adhering a coagulant to a glove molding mold,
(2) A stirring step of adjusting and stirring the dip molding composition according to any one of the above [1] to [6].
(3) A dipping step of immersing the glove molding mold in the dip molding composition,
(4) Gelling step of gelling the film formed on the glove molding to make a cured film precursor.
(5) A leaching step of removing impurities from the cured film precursor formed on the glove molding mold,
(6) Beading process to make a roll around the cuffs of gloves,
(7) Step of heating and drying at a temperature required for a cross-linking reaction A method for manufacturing a glove, which comprises a curing step and performs the above steps (3) to (7) in the above order.

According to the present invention, a halohydrin cross-linking agent for a carboxylic acid-modified NBR latex, which is not used in the field of conventional gloves, a dip molding composition containing at least the cross-linking agent, and a glove using the dip molding composition. By providing a manufacturing method and gloves, gloves having excellent tensile strength, elongation, and fatigue durability can be produced without using a vulcanization accelerator. Further, depending on the specific embodiment, it is possible to produce XNBR gloves characterized by having an excellent stress retention rate and at the same time a good elongation rate as compared with the conventional sulfur vulcanized XNBR gloves.

It is a conceptual diagram of the bridge structure of the glove which concerns on embodiment of this invention. It is sectional drawing which shows typically an example of the fatigue durability test apparatus.

The embodiments of the present invention will be described in detail below, but these descriptions are examples (representative examples) of the embodiments of the present invention, and the present invention is not limited to these contents as long as the gist thereof is not exceeded.
In addition, since "weight" and "mass" are used interchangeably in the present specification, they are collectively referred to as "weight" below.
Unless otherwise specified, "%" is "% by weight" and "part" is "part by weight".
Unless otherwise specified, "parts by weight" indicates, in principle, the number of parts by weight with respect to 100 parts by weight of the elastomer.
Further, in the present specification, when a numerical value or a physical property value is sandwiched before and after using "-", it is used as including the values before and after that.
Further, in the second object of the present invention, the theme is to improve the "stress retention rate" and maintain the "elongation rate" in the XNBR gloves. The compatibility of these two physical properties is an improvement of the conventional sulfur vulcanized XNBR gloves, and aims to bring the NBR synthetic rubber gloves closer to the physical properties of natural rubber and isoprene / chloroprene synthetic rubber.
The "stress retention rate" in this case indicates how much the stress when the glove is stretched at a predetermined elongation rate is retained after a lapse of a predetermined time, and a high stress retention rate means that the stress retention rate is high. This means that when the user (worker) wears gloves and performs work, the occurrence of loosening and slack with the passage of time is suppressed, and a good usability can be obtained. The specific evaluation method will be described later.
Further, in the present specification, "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.

The first embodiment of the present invention is a glove having a crosslinked structure in which XNBR is crosslinked with a halohydrin crosslinking agent.
A second embodiment of the present invention is a glove having a structure in which XNBR is crosslinked with a halohydrin cross-linking agent and an epoxy cross-linking agent. In the first and second embodiments, a metal cross-linking agent such as zinc is not an essential element, but it may be used in combination as a cross-linking agent.
A common feature of the above two embodiments is the use of a halohydrin crosslinker for dip molding of XNBR.
Halohydrin cross-linking agents with high hydrophilicity are relatively less inactivated than epoxy cross-linking agents and have a pot life of about 6 days in the dip solution, so they are mainly oriented to the outside of the XNBR particles. It is characterized by being able to crosslink between particles with a salt of a carboxyl group or carboxylate.
Such a highly hydrophilic halohydrin cross-linking agent, like the polycarbodiimide cross-linking agent (hereinafter referred to as “CDI cross-linking agent”), cross-links between particles by a covalent bond with a carboxyl group, but unlike the CDI cross-linking agent, Ca and K Since it is easy to crosslink by replacing metal elements such as, it is possible to reduce the portion of ion crosslinks in gloves. In addition, since it can provide tensile strength, it may be used as a substitute for a metal cross-linking agent such as zinc.

The present inventors believe that in XNBR gloves, performing interparticle cross-linking by covalent bonds and reducing ionic bonds leads to an increase in the stress retention rate of XNBR gloves. In addition, reducing the amount of metal cross-linking agents such as zinc is considered to be suitable for clean room gloves that dislike metal elution.
The second embodiment is characterized in that an epoxy cross-linking agent is used in combination with the halohydrin cross-linking agent, which is intended to increase the cross-linking density by cross-linking in the elastomer particles, but has particularly high hydrophilicity. When a cross-linking agent is used, the highly hydrophilic halohydrin cross-linking agent is mainly a covalent bond between the elastomer particles, whereas the epoxy cross-linking agent is mainly a covalent bond within the elastomer particles, so that the XNBR is shared both within the particles and between the particles. It is characterized by binding by binding. As a result, gloves that are harder to break than ionic bonds can be made, and if the crosslink density is increased, gloves with a good stress retention rate can be made. In this case as well, a metal cross-linking agent such as zinc is not essential, and ionic bonds due to Ca derived from the coagulant, K derived from the pH adjuster, etc. can also be reduced by the halohydrin cross-linking agent. In addition, when a highly oil-rich halohydrin is used, the halohydrin cross-linking agent also easily enters the inside of the particles. Therefore, the intra-particle cross-linking by the epoxy cross-linking agent alone is not sufficient to further strengthen the intra-particle cross-linking. Can be done.
The conceptual diagram of the cross-linked structure of the glove cross-linked with the halohydrin cross-linking agent, which is a common feature of the first embodiment and the second embodiment, is shown in FIG. 1, and the cross-linking and the prior art in the embodiment are shown below. A comparison table of the characteristics of cross-linking is shown in Table 1 below. Note that Zn ²⁺ , Ca ²⁺ , and K ⁺ in Table 1 are described assuming that a metal cross-linking agent, a coagulant, and a pH adjuster containing them are added, respectively, and are essential requirements. is not. Further, in the second embodiment of the present invention, Zn ²⁺ is shown in parentheses because in this embodiment, gloves having desired characteristics can be easily obtained without using Zn ^2+. It shows that no particular addition is required in comparison with.

Hereinafter, each component of the dip molding composition in the above embodiment, a glove manufacturing method, and a glove will be described.

<1. Dip molding composition>
The dip molding composition of the first embodiment of the present invention is a dip molding composition containing at least an elastomer of XNBR and a halohydrin cross-linking agent. The dip molding composition of the second embodiment of the present invention is a dip molding composition containing an epoxy cross-linking agent in combination with the above materials. The dip molding composition according to the first and second embodiments may contain a metal cross-linking agent such as zinc as an optional component. Further, the dip molding composition according to the first and second embodiments may contain a pH adjuster, an antioxidant, a pigment, a chelating agent and the like as other components.

XNBR is a polymer of structural units derived from (meth) acrylonitrile ((meth) acrylonitrile residues), structural units derived from unsaturated carboxylic acids (unsaturated carboxylic acid residues), and structural units derived from butadiene (butadiene residues). It is an elastomer contained in the main chain.
The XNBR elastomer usually forms particles having a particle size of about 50 to 250 nm as an aqueous emulsion in the composition. The environment inside and outside the particle is significantly different, and the inside of the particle is lipophilic because the main component is a hydrocarbon composed of butadiene residue, (meth) acrylonitrile residue, and (meth) acrylic acid. 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 has hydrophilicity.
The pH of the composition for dip molding is usually adjusted to 9.5 to 12.0 by a pH adjuster, and the carboxyl groups around the surface of the XNBR particles (elastomer particles) are oriented outward of the particles and carboxy. It is a rat. On the other hand, a buried carboxyl group is present in the particles.
Halohydrin cross-linking agents with high lipophilicity easily enter the elastomer particles, and most of them are present in the particles.
On the other hand, the highly hydrophilic halohydrin cross-linking agent is difficult to enter into the highly lipophilic elastomer particles, and most of them are present between the elastomer particles.
Since the epoxy cross-linking agent of the second embodiment is selected so as to easily enter the lipophilic region in the particles, most of them are present in the elastomer particles.
Metal cross-linking agents such as zinc exist between particles in the form of complex ions.
The state inside the particles and between the particles is the state when the composition for dip molding is formed, but when the XNBR particles (XNBR elastomer particles) are finally laminated to form a film, the inside of the particles is formed. And the situation between the particles is almost maintained. In-particle cross-linking and inter-particle cross-linking are used in this sense in this sense. Hereinafter, each component of the dip molding composition will be described in detail.

<1-1. Elastomer>
<1-1-1. Elastomer structure>
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 backbone. This elastomer is also referred to as "carboxylated (meth) acrylonitrile butadiene elastomer" or "XNBR". Further, gloves obtained by using XNBR as an elastomer are also referred to as "XNBR gloves".

Regarding the ratio of each structural unit in the elastomer, conventionally, the structural unit derived from (meth) acrylonitrile, that is, 25 to 30% by weight of the (meth) acrylonitrile residue, and the structural unit derived from unsaturated carboxylic acid, that is, unsaturated carboxylic acid It was common practice for the residues to be 4-10% by weight and the rest to be butadiene-derived structural units and other structural units.
On the other hand, in order to increase the stress retention rate of XNBR gloves, it is necessary to further reduce the structural unit derived from (meth) acrylonitrile to less than 25% by weight and increase the structural unit derived from butadiene without impairing other physical properties. We believe it is necessary.
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 becomes insufficient, and if it is too large, the chemical resistance increases but it becomes too hard.
In conventional XNBR gloves, the ratio of structural units derived from (meth) acrylonitrile in the elastomer is usually 25 to 30% by weight. On the other hand, considering only the problem of increasing the stress retention rate of the XNBR gloves according to the present embodiment, the ratio of the structural units derived from (meth) acrylonitrile is reduced, and the ratio of the structural units derived from butadiene is increased to increase the rubber elasticity. It is preferable to increase the number of butadiene-derived double bonds produced.
In consideration of the above, the ratio of the structural unit derived from (meth) acrylonitrile in the elastomer is preferably 12 to 35% by weight, more preferably 17 to 30% by weight.
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.

The amount of the unsaturated carboxylic acid-derived structural unit in the elastomer 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%, and further preferably 2 to 6% by weight. 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 type of unsaturated carboxylic acid that forms a structural unit derived from unsaturated carboxylic acid is not particularly limited, and may be monocarboxylic acid or polycarboxylic acid. More specifically, acrylic acid, methacrylic acid, crotonic acid and the like can be mentioned. Among them, acrylic acid and / or methacrylic acid (hereinafter, also referred to as "(meth) acrylic acid") is preferably used, and methacrylic acid is more preferably used.

Butadiene-derived structural units are elements that impart flexibility to gloves, and the amount of butadiene-derived structural units in an elastomer usually loses flexibility below 50% by weight. The ratio of butadiene-derived structural units in the elastomer is typically 50-75% by weight.
The amount of structural units derived from butadiene can be determined by a known method.
Considering only the problem of increasing the stress retention rate of the XNBR gloves of the present invention, it is preferable to increase the ratio of the structural units derived from butadiene to increase the double bond of butadiene that gives rubber elasticity. However, it is important not to impair other physical properties such as tensile strength.

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.
The structural unit derived from other polymerizable monomers is preferably 30% by weight or less, more preferably 20% by weight or less, particularly preferably 15% by weight or less, and particularly sets a lower limit in the elastomer. It is not necessary to do so, and it may be 0.1% by weight or more or 1% by weight or more.

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.

<1-1-2. Elastomer preparation>
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 are usually used according to a general method. It can be prepared by emulsion polymerization using the above-mentioned elastomer, polymerization initiator, molecular weight modifier and 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 sulfonate and aliphatic sulfonate; and nonionic surfactants such as polyethylene glycol alkyl ether and polyethylene glycol alkyl ester, preferably anionic surfactants. Surfactants are used.

The type of the polymerization initiator is not particularly limited as long as it is a radical initiator, but it is an inorganic peroxide such as ammonium persulfate and potassium perphosphate; t-butyl peroxide, cumene hydroperoxide, p-menthan hydroperoxide, etc. Organic peroxides such as t-butylcumyl peroxide, benzoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, t-butylperoxyisobutyrate; azobisisobutyronitrile, azobis-2,4 -Azo compounds such as dimethylvaleronitrile, azobiscyclohexanecarbonitrile, and methyl azobisisobutyrate can be mentioned.

Examples of the molecular weight modifier include mercaptans such as t-dodecyl mercaptan and n-dodecyl mercaptan, and halogenated hydrocarbons such as carbon tetrachloride, methylene chloride and methylene bromide, and t-dodecyl mercaptan; n-dodecyl mercaptan. Such as mercaptans are preferable.

<1-1-3. Features of Elastomer>
[Elastomer particle size]
The particle size of the elastomer in the composition for dip molding is not particularly limited, but it is preferable that particles having a particle size of 50 nm or more and 250 nm or less are formed as an aqueous emulsion.

[Elastomer chain aspect]
In order for a halohydrin cross-linking agent containing a halohydrin compound having a larger molecular weight than zinc or sulfur or an epoxy cross-linking agent containing an epoxy compound to easily penetrate into the elastomer chain, the elastomer chain has few branches and is linear. Elastomers are preferred. 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.

[Elastomer gel fraction (MEK insoluble matter)]
The gel fraction (MEK insoluble matter) of the elastomer is an index of branching of the elastomer chain, and the gel fraction is high in the elastomer having many branches. Usually, the gel fraction of XNBR used for manufacturing gloves is in the range of 0% by weight or more and 70% by weight or less in the measurement of the insoluble content of methyl ethyl ketone (MEK).
From the viewpoint of increasing the number of buried carboxyl groups in the XNBR particles, enhancing the cross-linking in the particles, increasing the cross-linking density, and increasing the stress retention rate, it is conceivable to increase the gel fraction.

[Content of sulfur element in elastomer]
In the elastomer, the content of the sulfur element detected by the neutralization titration method of the combustion gas is preferably 0% by weight, but a trace amount of sulfur is contained in the raw material manufacturing process even without any addition of sulfur. There is a risk of From this viewpoint, the sulfur content 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.

[Selection of elastomer by Mooney viscosity (ML _{(1 + 4)} (100 ° C.))]
An elastomer having a Mooney viscosity (ML _{(1 + 4)} (100 ° C.)) of XNBR as a normal glove material of 80 or more and 160 or less is used.
From the viewpoint of increasing the stress retention rate, it is considered that the Mooney viscosity of XNBR should be relatively high.

[Elastomer content relative to the total amount of the dip molding composition]
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 15% by weight or more and 35% by weight or less, preferably 18% by weight or more and 30% by weight or less, based on the total amount of the dip molding composition. More preferably, it is by weight% or less.

<1-2. Halohydrin crosslinker>
The characteristics when the halohydrin cross-linking agent is used in the dip molding composition for producing XNBR gloves are as described in the description of the dip molding composition.
Halohydrin cross-linking agents are precursors in the production of epoxy cross-linking agents, but epoxy cross-linking agents with particularly high hydrophilicity have a short pot life (pot life), whereas they have high hydrophilicity. The present inventors have focused on the fact that the pot life is long, interparticle cross-linking is possible, and a covalent bond is used.
Further, the halohydrin cross-linking agent is attractive in that it can crosslink instead of metal cross-linking by Ca or K and reduce ionic bonds in terms of increasing the stress retention rate. We also focused on the possibility of making zinc-free clean room gloves if the halohydrin cross-linking agent replaces metal cross-linking agents such as zinc.
The details of the halohydrin cross-linking agent will be described below.

The halohydrin compound is considered to react with the carboxyl group or carboxylate based on the following formula (W1) or (W2). The reactivity of carboxylate is higher than that of carboxyl group.

The content of the halohydrin compound in the composition for dip molding is not particularly limited, but from the viewpoint of introducing a sufficient crosslinked structure between the elastomers to ensure tensile strength and fatigue durability, the epoxy in one molecule of the epoxy compound Although it depends on the number and purity of the groups, it is usually 0.1 parts by weight or more and 10 parts by weight or less, 0.3 parts by weight or more, and 5.0 parts by weight or less with respect to 100 parts by weight of the elastomer. It is preferably 0.5 parts by weight or more and more preferably 3.0 parts by weight or less.
The content of the halohydrin compound in the halohydrin cross-linking agent is usually 20% by weight or more, preferably 30% by weight or more, more preferably 40% by weight or more, and further preferably 50% by weight or more. It is preferably 80% by weight or more, particularly preferably 90% by weight or more, and may be 100% by weight or less.
The content of the halohydrin compound may be evaluated from the amount of the raw material charged, but can be measured by a known method such as GPC.

The dip molding cross-linking agent (hereinafter, also referred to as “dip molding cross-linking agent” or “halohydrin cross-linking agent”), which is an embodiment of the present invention, has one molecule of halohydrin group D represented by the following formula (I). A cross-linking agent for dip molding containing at least two halohydrin compounds therein. For ^{R 1} and X in the following formula (I), the later. The wavy line in the structure of the following formula (I) represents the coupling to another structure.

According to the present embodiment, when the elastomer particles for dip molding are crosslinked with the cross-linking agent for dip molding to obtain a dip molded product, the elastomer particles and the like are elastomer particles having a carboxyl group and / or carboxylate. If the above is true, the elastomer is not limited to the above-mentioned elastomer, and any conventionally known elastomer can be used.

<1-2-1. Structure of halohydrin compound>
The halohydrin cross-linking agent is a halohydrin cross-linking agent containing a compound having at least two halohydrin groups D represented by the following formula (I) in one molecule (hereinafter, also referred to as “halohydrin compound (I))).

In the above formula (I), R ¹ is a hydrogen or alkyl group, and X is a halogen group.
R ¹ is not particularly limited, but from the viewpoint of steric hindrance, it is preferably hydrogen or an alkyl group having 1 to 2 carbon atoms, more preferably hydrogen or an alkyl group having 1 carbon atom, and it is hydrogen. Is preferable.
Although X is not particularly limited, it is preferably Cl or Br, and particularly preferably Cl, from the viewpoint of reactivity.
The above conditions of R ¹ and X are the same in the following aspects.

The halohydrin compound may be a halohydrin compound having at least one halohydrin group Da represented by the following formula (Ia) in one molecule as the halohydrin group D (hereinafter, also referred to as “halohydrin compound (Ia)”). preferable. The wavy line in the structure of the following formula (Ia) represents the coupling to another structure.

In the above formula (Ia), R ¹ is a hydrogen or alkyl group, and X is a halogen group.

Further, it is preferable that the halohydrin compound (I) is a halohydrin compound represented by the following formula (II) (hereinafter, also referred to as "halohydrin compound (II)").

In the above formula (II), R ² is a (k + m) -valent aliphatic hydrocarbon group having 2 to 10 carbon atoms, X is a halogen group, and k and m are 2 ≦ k ≦ 6,0. It is an integer that satisfies ≦ m ≦ 4 and 2 ≦ k + m ≦ 6.

Further, it is preferable that the halohydrin compound (I) is a halohydrin compound represented by the following formula (III) (hereinafter, also referred to as "halohydrin compound (III)").

In the above formula (III), R ³ represents a hydrogen atom or an alkyl group, X is a halogen group, and n is an integer satisfying 1 ≦ n ≦ 50.

Further, it is preferable that the halohydrin compound (I) is a halohydrin compound represented by the following formula (IV) (hereinafter, also referred to as "halohydrin compound (IV)").

In the above formula (IV), R ⁴ is an independent hydrogen atom or a halohydrin group Da, and at least two of R ⁴ are halohydrin groups Da, and p is an integer satisfying 1 ≦ p ≦ 10. is there.

The halohydrin compound (I) is a compound having at least two halohydrin groups Da in one molecule, which is obtained by reacting a sugar alcohol from a oligosaccharide with epihalohydrin (hereinafter, also referred to as “halohydrin compound (V)”). Can be.

<1-2-2. Method for manufacturing halohydrin cross-linking agent>
The halohydrin compound (I) is generally a compound having at least two hydroxyl groups in the molecule (hereinafter, also referred to as “polyhydrin alcohol”) corresponding to the halohydrin compounds (II) to (V). It can be obtained by reacting epihalohydrin.

That is, the above-mentioned halohydrin compound (II) can be obtained by using the above-mentioned polyhydrin alcohol represented by the following formula (II-2) and reacting it with epihalohydrin.

In the formula ^{(II-2), R 2} , k and m are the same as the conditions described above.
The aliphatic hydrocarbon R ^2, as is clear from the specific examples of the polyhydric alcohol to be described later, an aliphatic polyvalent alcohol residue.

The above-mentioned halohydrin compound (III) can be obtained by using the above-mentioned polyhydrin alcohol represented by the following formula (III-2) and reacting it with epihalohydrin.

In the formula (III-2), ^{R 3} and n are the same as the conditions described above.
R ³ is not particularly limited, but is preferably a hydrogen atom or a methyl group, and n is preferably 1 or 2, and more preferably 2.

The above-mentioned halohydrin compound (IV) can be obtained by using the above-mentioned polyhydrin alcohol represented by the following formula (IV-2) and reacting it with epihalohydrin.

In the above formula (IV-2), p is the same as the above-mentioned conditions.
p is not particularly limited, but is preferably 1.

The above-mentioned halohydrin compound (V) can be obtained by reacting epihalohydrin with a sugar alcohol obtained from a oligosaccharide.

The polyhydric alcohol represented by the above general formula (II-2) shall contain a sugar alcohol obtained by reducing monosaccharides, and specific examples of such polyhydric alcohols are not particularly limited. However, for example, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,4-butanediol, 1,6-hexanediol, ethylene glycol, glycerin, trimethylol ethane, trimethylol. Examples thereof include propane, erythritol, pentaerythritol, sorbitol, mannitol, xylitol and the like. Among these, ethylene glycol, glycerin, trimethylolethane, trimethylolpropane, sorbitol, mannitol and the like are preferable, and ethylene glycol, glycerin and trimethylolpropane are preferable.

The polyhydric alcohol represented by the general formula (III-2) is not particularly limited, but for example, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol and the like can be used. Can be mentioned. Of these, diethylene glycol or dipropylene glycol is particularly preferable.

Further, the polyhydric alcohol represented by the above general formula (IV-2) is not particularly limited, and examples thereof include diglycerin and polyglycerin. Of these, diglycerin is particularly preferred.

The sugar alcohol from the oligosaccharide used for producing the halohydrin compound (V-2) described above is not particularly limited, but is, for example, maltose, cellobiose, sucrose (sucrose), and lactose. ) And the like, sugar alcohols obtained by reducing trisaccharides such as raffinose and meletitose, and reduced maltose obtained by reducing maltose. Sugar alcohols from such oligosaccharides can be used alone or as a mixture of two or more (with, if desired, sugar alcohols from monosaccharides).

Among the sugar alcohols from these oligosaccharides, for example, maltitol (sugar alcohol from maltose), which is easily available as a commercial product, is preferably used.

On the other hand, as the epichlorohydrin that reacts with such a polyhydric alcohol, epichlorohydrin or epibromhydrin is particularly preferably used.

The reaction of various polyhydric alcohols with epihalohydrin as described above is, if necessary, in a reaction solvent in the presence of a Lewis acid catalyst, preferably under heating (eg, a temperature in the range of 30-95 ° C.). ), Epihalohydrin can be added dropwise to a polyhydric alcohol and mixed. Examples of the Lewis acid catalyst include, but are limited to, boron trifluoride ether complex, tin tetrafluoride, zinc borofluoride, titanium tetrachloride, zinc chloride, silica alumina, antimony trichloride, and the like. It's not a thing.

The reaction solvent is used as necessary for controlling the reaction, adjusting the viscosity, etc., and can be any as long as it is inactive in the reaction between the polyhydric alcohol and epihalohydrin. Good. Therefore, examples of such a reaction solvent include aromatic hydrocarbons such as toluene and xylene, aliphatic hydrocarbons such as hexane and heptane, diethyl ether, diisopropyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether and dioxane. Examples include ethers.

In such a reaction between a polyhydric alcohol and epihalohydrin, epihalohydrin is usually used in the range of 30 to 200 mol%, preferably 50 to 150 mol%, based on the amount of hydroxyl groups of the polyhydric alcohol. When the amount of epihalohydrin used is less than 30 mol% with respect to the amount of hydroxyl groups of the polyhydrin alcohol, the amount of halohydrin groups in the obtained polyhalohydrin compound is too low, and it is sufficient to use this as a cross-linking agent. I can't get the physical characteristics. However, when the amount of epihalohydrin used exceeds 200 mol%, unreacted epihalohydrin remains in the obtained halohydrin compound, which is not only uneconomical but also from the viewpoint of safety when used as a cross-linking agent. It is also not preferable.

As the epichlorohydrin, epichlorohydrin or epichlorohydrin is preferably used. In addition, examples of 1,3-dihalo-2-propanol include 1,3-dichloro-2-propanol, 1,3-dibromo-2-propanol and the like.

An example of production of the halohydrin compound contained in the halohydrin cross-linking agent is shown below. A commercially available product may be used as the halohydrin cross-linking agent.
Sorbitol, toluene, and a boron trifluoride ether complex as a catalyst are charged in a separable flask, heated and stirred, and epichlorohydrin is added dropwise thereto. After completion of the dropping, the mixture is further stirred for a certain period of time at the same temperature as in the case of heating and stirring, and then the disappearance of epichlorohydrin is confirmed based on the quantification of epoxy groups by titration, and the reaction is terminated. After completion of the reaction, toluene was distilled off under reduced pressure, and as a reaction product, in the above formula (II), R ² was a sorbitol residue, X was a chlorine atom, k = 3, m = 3. A cross-linking agent can be obtained.

The MIBK / water distribution ratio of the halohydrin cross-linking agent is not particularly limited, and the effect of the present invention can be obtained regardless of whether it is hydrophilic or lipophilic, but it is usually 100% or less. Specifically, in the case of hydrophilicity, cross-linking between elastomer particles is promoted, in the case of lipophilicity, cross-linking within elastomer particles is promoted, and in the case between these, cross-linking between elastomer particles and within elastomer particles Although the ratio changes, in any case, the formation of crosslinks by halohydrin occurs, so that desired mechanical properties can be obtained. The higher the value of the MIBK / water distribution ratio, the higher the lipophilicity, and the lower the value, the higher the hydrophilicity. In the specification of the present application, the hydrophilic halohydrin has a MIBK / water partition ratio of usually -30 to 50%, preferably -30 to 30%, and more preferably -30 to 0%. Further, the lipophilic halohydrin has a MIBK / water distribution ratio of usually 50 to 100%, preferably 60 to 90%, and more preferably 70 to 90%.

The MIBK / water distribution ratio can be measured by the following method.
First, about 5.0 g of water, about 5.0 g of MIBK, and about 0.5 g of a halogen 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 halogen cross-linking agent be E (g).
The mixture is sufficiently 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, the present inventors considered that it can be adopted as a standard.

<1-3. Epoxy crosslinker>
In the second embodiment of the present invention, an epoxy cross-linking agent is used in addition to the halohydrin cross-linking agent. Since the epoxy cross-linking agent used in the present embodiment has a relatively high lipophilicity, it easily penetrates into the elastomer particles and easily reacts with the carboxyl group in the particles. Further, in the case of a halohydrin cross-linking agent having a high lipophilicity, since the halohydrin cross-linking agent also easily enters the inside of the particles, it is possible to further strengthen the intra-particle cross-linking, which was not sufficient only by the intra-particle cross-linking with the epoxy cross-linking agent.
It is considered that the cross-linking by the reaction between the epoxy cross-linking agent and the carboxyl group of XNBR tends to be an intra-particle cross-linking.
Therefore, cross-linking is possible with halohydrin alone, but by using it in combination with an epoxy cross-linking agent that enables intra-particle cross-linking, in combination with highly hydrophilic halohydrin, it should be combined with the halohydrin cross-linking agent for interparticle cross-linking. By covalently cross-linking the particles within and between the particles, and by further strengthening the inter-particle cross-linking by covalent bond in combination with halohydrin having high lipophilicity, physical properties such as stress retention rate It is thought that it will be possible to manufacture excellent gloves.
The epoxy cross-linking agent contains an epoxy compound having at least three epoxy groups in one molecule.

<1-3-1. Epoxy cross-linking agent structure>
Epoxide compounds having three or more epoxy groups in one molecule usually have a matrix having a plurality of glycidyl ether groups and alicyclic, aliphatic or aromatic hydrocarbons (hereinafter, "trivalent or higher"). It is also called an "epoxide compound"). As the epoxy compound having a trivalent or higher valence, an epoxy compound having three or more glycidyl ether groups can be preferably mentioned. An epoxy compound having three or more glycidyl ether groups can usually be produced by reacting epihalohydrin with an alcohol having three 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, at least one selected from glycerol triglycidyl ether, trimethylolpropane triglycidyl ether, sorbitol triglycidyl ether, sorbitol tetraglycidyl ether, pentaerythritol triglycidyl ether, pentaerythritol tetraglycidyl ether, and diglycerol triglycidyl ether. It is preferable to use an epoxy cross-linking agent containing trimethylolpropane, among which at least one selected from trimethylolpropane triglycidyl ether, pentaerythritol triglycidyl ether, glycerol triglycidyl ether, diglycerol triglycidyl ether and pentaerythritol tetraglycidyl ether. It is more preferred to use an containing epoxy cross-linking agent. Further, it is preferable to use an epoxy cross-linking agent containing an epoxy compound having no sorbitol skeleton.

<1-3-2. Crosslinking reaction between epoxy compound and carboxyl group of XNBR>
As shown by the following formula (Y), epoxy cross-linking occurs by the following reaction. The epoxy compound represented by the following formula (Y) is monovalent from the viewpoint of simplifying the explanation.

It is the carboxyl group in XNBR that the epoxy compound forms a crosslink, and in order to form a crosslink with the epoxy compound, it is necessary to heat at 90 ° C. or higher in the curing step to cause a ring-opening reaction of the epoxy group. Can be mentioned.
In addition, the epoxy compound contained in the dip molding composition, which has escaped deactivation in the lipophilic environment in the XNBR particles, becomes a cured film precursor and is 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 particles. At this time, by selecting XNBR having excellent water separation, the crosslinking efficiency can be increased and the crosslinking temperature can be lowered.

The content of the epoxy cross-linking agent in the composition for dip molding is not particularly limited, but from the viewpoint of introducing a sufficient cross-linking structure between the elastomers to ensure stress retention and fatigue durability, it is contained in one molecule of the epoxy compound. Although it depends on the number and purity of the epoxy groups, it is usually 0.2 parts by weight or more and 5 parts by weight or less 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 content is excessive, the characteristics of the elastomer may be deteriorated. Therefore, the content of the epoxy compound in the dip molding composition is 5 parts by weight or less with respect to 100 parts by weight of the elastomer. It is preferably 3 parts by weight or less, more preferably 2 parts by weight or less, more preferably 0.3 parts by weight or more, and 0.5 parts by weight or more. Is more preferable, and it is considered that 0.7 parts by weight or more is further preferable.
The ratio of the content of the halohydrin cross-linking agent to the epoxy cross-linking agent is preferably 10: 1 to 1: 5, preferably halohydrin cross-linking agent: epoxy cross-linking agent = 100: 1 to 1:50 on a weight basis. More preferably.
The content of the epoxy compound in the epoxy cross-linking agent is usually 20% by weight or more, preferably 30% by weight or more, more preferably 40% by weight or more, and further preferably 50% by weight or more. It is preferably 80% by weight or more, particularly preferably 90% by weight or more, and may be 100% by weight or less.
The content of the epoxy compound may be evaluated from the amount of the raw material charged, but can be measured by a known method such as GPC.

<1-3-3. Characteristics of 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 is not particularly limited, but is preferably more than 2.0, more preferably 2.3 or more, from the viewpoint of obtaining a good stress retention rate and fatigue durability of the glove. 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.

<Epoxy equivalent>
From the viewpoint of obtaining good stress retention and fatigue durability of gloves, 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 a better stress retention rate 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.

<MIBK / water distribution rate>
By using an epoxy cross-linking agent having a MIBK / water distribution ratio of 27% or more according to the following measuring method, it becomes easy to obtain a dip molding composition having a pot life of 3 days or more.
The pot life is a period from the preparation of the dip molding composition to the preparation of the cured film, and if the dip molding composition is used within that period, the obtained cured film meets a specific standard. Indicates the period during which it can be done.
If the MIBK / water distribution ratio is less than 27%, the pot life tends to be less than 3 days. The MIBK / water partition ratio of the epoxy cross-linking agent is preferably 30% or more in order to obtain the desired pot life of the dip molding composition. There is a correlation between the MIBK / water distribution rate and the pot life, and the higher the MIBK / water distribution rate, the longer the pot life without exception.
An epoxy cross-linking agent having a MIBK / water distribution ratio of 50% or more tends to have a pot life of 5 days or more.
Further, an epoxy cross-linking agent having a MIBK / water distribution ratio of 70% or more is preferable because a pot life of 7 days or more can be easily obtained.
The upper limit of the MIBK / water distribution ratio of the epoxy cross-linking agent does not need to be set in particular, but is usually 95% or less, for example.

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).
The mixture is sufficiently 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.

<1-3-4. Dispersant for epoxy cross-linking agent>
The epoxy cross-linking agent described above needs to be kept in a uniformly 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, there is a problem that the higher the MIBK / water partition ratio is, the more difficult it is to add the cross-linking agent to the latex solution and the more difficult it is to disperse.
If it is a highly hydrophilic epoxy cross-linking agent, there is no problem in water dispersibility, but for the epoxy cross-linking agent used for solvent-based paints, after dissolving the epoxy cross-linking agent with the dispersant, I thought about blending it with an elastomer.
In particular, when the MIBK / water distribution ratio is 50% or more, white turbidity tends to be seen when dissolved in water, so it was considered necessary to disperse with a dispersant.

The dispersant of the epoxy cross-linking agent comprises 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 preferably one or more selected from the group.
HO- (CH ₂ CHR ^1- O) _n1- H (1)
[In the above formula (1), R ¹ represents a hydrogen or a 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. ]

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.

Among the above dispersants, alcohol is preferable, methanol, ethanol and diethylene glycol are particularly preferable, and diethylene glycol is particularly preferable 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.

<1-4. Metal cross-linking agent>
The dip molding composition of the first and second embodiments may contain a metal cross-linking agent such as zinc as an optional component. However, in order to increase the stress retention rate of the XNBR gloves, it is preferable that there is no ionic bond due to the metal cross-linking agent.
When a metal cross-linking agent such as zinc is used in combination, it may be added to the minimum necessary to secure the tensile strength required for the glove.
However, the XNBR gloves contain a considerable amount of ionic bonds due to Ca derived from the coagulant and K derived from the pH adjuster, and a halohydrin cross-linking agent capable of reducing these ionic cross-links is also effective in that respect. it is conceivable that.

The polyvalent metal compound used as a metal cross-linking agent is one that ion-crosslinks between functional groups such as unreacted carboxyl groups in an 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. Aluminum has the smallest ionic radius among the above and is optimal for obtaining chemical resistance and tensile strength, but if too much is added, the glove becomes too hard. The amount of the divalent metal oxide, for example zinc oxide, and / or the aluminum complex added can be 0.0 to 2.0 parts by weight with respect to 100 parts by weight of the elastomer in the dip molding composition.

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.

As described above, physical properties such as tensile strength can be ensured by including a metal component in the dip molding composition, but since the ionic bond has a weaker bonding force than the covalent bond, when the gloves are stretched. In addition, the bond is displaced, which causes a decrease in the stress retention rate.

<1-5. Other ingredients>
The composition for dip molding usually contains the following components as components other than the above-mentioned elastomer, cross-linking agent and the like (hereinafter, also referred to as "other components").
Examples of other components are shown below.

(1) pH adjuster The dip molding composition needs to be adjusted to be alkaline at the stage of the stirring step (maturation step) described later. One of the reasons for making it alkaline is that -COOH is oriented outward as -COO- from the elastomer particles, and interparticle cross-linking with a halohydrin cross-linking agent is sufficiently performed. Since the metal cross-linking that can occur when a metal cross-linking agent such as zinc oxide or a coagulant containing calcium ions or the like is used is also inter-particle cross-linking, it is necessary to make it alkaline for the same reason as described above.
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.
The amount of the pH adjuster added can be 1.5 to 10.0 parts by weight with respect to 100 parts by weight of the elastomer in the composition for dip molding, but it is usually industrially 1.8 to 2. Use 0 parts by weight.

(2) Others As other components, the following components are usually contained in addition to the above materials.
The composition for dip molding contains water, and the content of water in the composition for dip molding is set to a predetermined concentration because the latex concentration, which is a factor for adjusting the thickness of gloves, is set to this concentration. It can be changed as appropriate, but it is usually 78 to 92 parts by weight.
As the water, pure water or industrial water can be used, but it is preferable to use pure water.

The composition for dip molding also usually contains a dispersant for dispersing each component. 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 usually further contains 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.

In the dip molding composition of the present embodiment, each additive such as an elastomer, a halohydrin cross-linking agent, and if necessary, an epoxy cross-linking agent, a pH adjuster, and water is mixed by a conventional mixing means, for example, a mixer or the like. Can be made.

<2. How to make gloves>
A glove manufacturing method (hereinafter, also simply referred to as “glove manufacturing method”), which is another embodiment of the present invention, is the following manufacturing method.
That is,
(1) Coagulant adhesion step (step of adhering coagulant to glove molding mold),
(2) Stirring step (step of preparing a composition for dip molding and stirring),
(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) 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 (7) in the above order.

The following step (6') may be optionally provided between the steps (6) and (7) above.
(6') Precure ring step, (step of heating and drying the cured film precursor at a lower temperature than the curing step)
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 to gel to some extent. It is a modified film that has not been finally cured.

Details will be described below for each step.
(1) Coagulant Adhesion Step (a) Mold or former (glove molding type) is ^{placed 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. 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) Stirring step (a) As described in the section of pH adjuster of the dip molding composition, in the step of adjusting the pH of the dip molding composition according to the above-described embodiment to 9.5 or higher and stirring. is there. 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, it may take about 24 hours for dispersion and homogenization. Pour this into a dip tank and dip it, but add more as the water level in the dip tank drops. Therefore, it is necessary that the cross-linking agent used is not inactivated for preferably about 5 days, at least about 3 days after the preparation of the dip molding composition.
When using a hydrophilic halohydrin cross-linking agent or an epoxy cross-linking agent with a trivalent MIBK / water distribution ratio of 27% or more, it is necessary to secure a minimum of 3 days as a mass production condition (leave it uninactivated). it can. It has been confirmed that the halohydrin cross-linking agent has a pot life of about 6 days.

(3) Diping Step In the stirring step (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 adhering step is carried out in the dip tank. This is a step of immersing the mold or former after the coagulant is attached and dried, usually 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 gelling step, the cross-linking of the latex is slightly advanced to gel to a certain extent so that the film is not deformed during the subsequent leaching, and at the same time, calcium is dispersed in the film, and then calcium cross-linking is performed. The purpose is to make it sufficient. As a gelling condition, it is generally performed for about 1 to 4 minutes within a temperature range of 30 to 140 ° C.

(5) Reaching Step (a) The leaching step is a step of washing and removing excess chemicals and impurities that interfere with subsequent curing such as calcium precipitated on the surface of the cured film precursor. Normally, the former is dipped in warm water at 40 to 60 ° C. for about 1.5 to 4 minutes. (B) leaching, removing the emulsifier is a film of XNBR particles in order to proceed smoothly crosslinked by curing process, -COO oriented outwardly ^- to return to -COOH, complex ion of metal cross-linking agent This is an important step in that it is retained in the film instead of the hydroxide that is insoluble in water, and Ca derived from the excess coagulant and K derived from the pH adjuster are removed.

(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 excellent.

(6') 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.

(7) Curing Step The curing step is a step of heating and drying at a high temperature to finally complete the cross-linking and to make a cured film as a glove. It is usually heated and dried at 90 to 140 ° C. for 10 to 30 minutes, preferably about 15 to 30 minutes.

(8) Double dipping As for the method of manufacturing 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.
As a precaution for double dipping, in order to aggregate XNBR in the second dipping step, it is necessary to have a sufficient time in the gelling step for sufficiently precipitating calcium to the film surface in the first gelling step. Is mentioned.

<3. Gloves ＞
The glove according to the above-described embodiment of the present invention is a glove manufactured by using the above-mentioned dip molding composition, and in the first embodiment, it has a cross-linked structure of a carboxyl group of XNBR and a halohydrin cross-linking agent. It is a glove, and in the second embodiment, it is a glove having a cross-linked structure of a carboxyl group and an epoxy cross-linking agent.
In the first embodiment, it was confirmed that the XNBR glove having the necessary physical characteristics of the glove can be produced by using the halohydrin cross-linking agent.
In particular, it was found that when crosslinked with a small amount of zinc, the tensile strength was as strong as 7N or more.
In the absence of zinc, fatigue durability tended to be low, but it was found that increasing the amount of halohydrin cross-linking agent added can provide sufficient fatigue durability.
In the second embodiment, in the case where the halohydrin cross-linking agent and the epoxy cross-linking agent are used in combination and zinc is not added, the characteristics of the conventional XNBR gloves having a high stress retention rate of 66% and an elongation rate of 500% or more are not found. I found that I could make gloves.
This is because, in the case of a highly hydrophilic halohydrin crosslinker, the intra-particle cross-linking is cross-linked with an epoxy cross-linking agent and the inter-particle cross-linking is cross-linked with a halohydrin cross-linking agent to eliminate zinc, which is an ionic cross-link, and halohydrin with high oiliness In the case of the cross-linking agent, it is considered that this was achieved by further strengthening the inter-particle cross-linking by covalent bond.
Further, the glove can be a glove which is a cured product of the above-mentioned dip molding composition.

The elastomer forming the glove has a (meth) acrylonitrile-derived structural unit of 12 to 35% by weight, an unsaturated carboxylic acid-derived structural unit of 2 to 10% by weight, and the rest of which is a butadiene-derived structural unit. And other components are preferred. Further, the structural unit derived from butadiene is preferably 50 to 75% by weight.

Like other vulcanization accelerator-free gloves, the above gloves do not substantially contain sulfur and vulcanization accelerators unlike conventional XNBR gloves, and therefore, the greatest feature is that they do not cause type IV allergies. .. 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.
Further, it is considered that the stress retention rate of the gloves according to the present embodiment is increased in that the cross-linking is not a sulfur cross-linking that causes a cross-linking reaction near the double bond of butadiene but a covalent bond with a carboxyl group.

As a result of looking at the physical properties of the gloves according to the first embodiment and the second embodiment in terms of tensile strength, tensile elongation, fatigue durability and stress retention, all the gloves have the physical characteristics required as gloves. The present inventors have confirmed that they have.
Further, it was confirmed that the glove according to the second embodiment has a high stress retention rate which has never been seen in the XNBR glove.
These physical properties were measured by the test method described later.

For the tensile strength and elongation, a JIS K6251 No. 5 dumbbell test piece was cut out from the cured film, and a TENSILON universal tensile tester RTC-1310A manufactured by A & D was used to test the test speed at 500 mm / min, the distance between chucks at 75 mm, and between the marked lines. Measured at a distance of 25 mm.
As for the physical characteristics of gloves, the tensile strength is considered to be 20 MPa or more, and the elongation rate is considered to be 500% or more.

The stress retention rate was measured as follows.
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 is applied in minutes, and when the test piece is stretched twice (100%), the stretching is stopped and the tensile stress M100 (0) is measured, and the tensile stress M100 (6 minutes) after elapsed as it is. 6) was measured. Then, the percentage of M100 (6) with respect to M100 (0) was defined as the stress retention rate.
Since the stress retention rate of the conventional sulfur-crosslinked XNBR gloves is in the 40% range, it is considered that 50% or more is good for XNBR gloves.

For fatigue durability, a 120 mm long JIS K6251 No. 1 dumbbell test piece is made from a cured film, the lower part is fixed and the upper part of the test piece is pulled to a length of 60 mm while being immersed in an artificial sweat solution. It is indicated by the time required for the test piece to break by repeating stretching and relaxation between a maximum of 195 mm and a minimum of 147 mm in the direction. Elongation (195 mm) and relaxation (147 mm) are performed by repeating a cycle (1 cycle 12.8 seconds) of holding in a relaxed state for 11 seconds, then extending to 195 mm in 1.8 seconds and returning to 147 mm. Can be done.

More specifically, a fatigue durability test can be performed using a device as shown in FIG. 2 using a dumbbell-shaped test piece as in the case of performing a tensile test of a rubber product. As shown in FIG. 2A, the lower end of the test piece is fixed with a clamp, and up to 60 mm is immersed in artificial sweat liquid. The upper end of the test piece is sandwiched and expanded and contracted up and down using a pneumatic piston so as to be in the relaxed state of FIG. 2 (b) → the extended state of FIG. 2 (c) → the relaxed state of FIG. 2 (b). Evaluation is made by measuring the number of cycles and the time until the bicycle breaks, with the expansion and contraction of 2 (b) → FIG. 2 (c) → FIG. 2 (b) as one cycle. When the test piece is torn, the photoelectric sensor reacts and the device stops.

1. 1. Implementation Method Hereinafter, the present invention will be described in more detail based on Examples. However, the present invention is not construed as being limited to the following examples.
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 halohydrin cross-linking agent and the epoxy cross-linking agent is based on the total weight of each cross-linking agent.

1-1. XNBR
The XNBR used in this experimental example is shown in Table 2 below.

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 numbers 2237 cm ^-1 and a carboxylic acid group 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 (% by weight) = [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.

1-2. Halohydrin cross-linking agent Table 3 below shows the characteristics of the halohydrin cross-linking agent used in this experimental example, such as the mother skeleton. The solid content in Table 3 indicates the content of the halohydrin compound in the halogen cross-linking agent in this example.

In the experimental example, a chlorohydrin cross-linking agent was used as the halohydrin cross-linking agent. The chlorohydrin cross-linking agent was produced as follows.

A. Chlorohydrin cross-linking agent A (sorbitol skeleton)
182 g (1.0 mol) of sorbitol, 500 g of toluene, and 1.8 g of boron trifluoride ether complex as a catalyst are charged in a 1 L volume separable flask, and the mixture is heated and stirred to maintain the internal temperature at 70 to 90 ° C., and epichlorohydrin. 277.5 g (3.0 mol) was added dropwise.
At the end of the dropping, the reaction system was a uniform solution. After completion of the dropping, the mixture was further stirred at the same temperature for 2 hours, and then the disappearance of epichlorohydrin was confirmed based on the determination of epoxy groups by titration, and the reaction was terminated. After completion of the reaction, toluene was evaporated under reduced pressure, as a reaction product, in the general formula ^{(II), R 2 - (} OH) m is a sorbitol residue, X is a chlorine atom, k = 3. A cross-linking agent having m = 3 was obtained.

As a result of quantitative analysis of the amount of chlorine (the amount of chlorine in the chlorohydrin group) in the above reaction product, it was 21.9% (theoretical amount 23.0%), and the yield was 95%.

I. Chlorohydrin cross-linking agent B (ethylene glycol skeleton)
166 g (2.7 mol) of ethylene glycol, 70 g of toluene, and 0.6 g of boron trifluoride ether complex as a catalyst were charged in a 2 L volume separable flask, and the mixture was heated and stirred to keep the internal temperature at 50 ° C. 557 g (6.0 mol) of epichlorohydrin was added dropwise. At the end of the dropping, the reaction system was a uniform solution. After completion of the dropping, the mixture was further stirred at the same temperature for 2 hours, and then the disappearance of epichlorohydrin was confirmed based on the determination of epoxy groups by titration, and the reaction was terminated. After completion of the reaction, toluene was distilled off under reduced pressure to obtain a cross-linking agent. In the cross-linking agent, in the general formula (II), R ^2- (OH) _m is an ethylene glycol residue, X is a chlorine atom, and k = 2 and m = 0.

C. Chlorohydrin cross-linking agent C (glycerin skeleton)
300 g (3.3 mol) of glycerin, 150 g of toluene, and 0.6 g of boron trifluoride ether complex as a catalyst were charged in a 2 L volume separable flask, and the mixture was heated and stirred to maintain the internal temperature at 50 ° C., and 999 g of epichlorohydrin (999 g). 10.8 mol) was added dropwise. At the end of the dropping, the reaction system was a uniform solution. After completion of the dropping, the mixture was further stirred at the same temperature for 2 hours, and then the disappearance of epichlorohydrin was confirmed based on the determination of epoxy groups by titration, and the reaction was terminated. After completion of the reaction, toluene was distilled off under reduced pressure to obtain a cross-linking agent. In the above general formula (II), in this cross-linking agent, R ^2- (OH) _m is a glycerin residue, X is a chlorine atom, and k = 2 and m = 1.

D. Chlorohydrin cross-linking agent D (trimethylolpropane skeleton)
425 g (3.2 mol) of trimethylolpropane, 300 g of toluene, and 2.4 g of boron trifluoride ether complex as a catalyst are charged in a 2 L volume separable flask, and the mixture is heated and stirred to maintain the internal temperature at 50 ° C., and epichlorohydrin. 894 g (9.7 mol) was added dropwise. At the end of the dropping, the reaction system was a uniform solution. After completion of the dropping, the mixture was further stirred at the same temperature for 2 hours, and then the disappearance of epichlorohydrin was confirmed based on the determination of epoxy groups by titration, and the reaction was terminated. After completion of the reaction, toluene was distilled off under reduced pressure to obtain a cross-linking agent. In the cross-linking agent, in the general formula (II), R ^2- (OH) _m is a trimethylolpropane residue, X is a chlorine atom, and k = 2 and m = 1.

1-3. Epoxy cross-linking agent The epoxy cross-linking agent used in the examples is "Denacol Ex-321" manufactured by Nagase ChemteX Corporation, and its physical characteristics are as follows.
Epoxy equivalent: 140 g / eq.
Average number of epoxy groups: 2.7
MIBK / water distribution rate: 87%
The content of the epoxy compound in the epoxy cross-linking agent in this example is approximately 100% by weight, although impurities such as reaction by-products are contained.

The epoxy equivalent is a catalog value, and the average epoxy group number is an analytical value.
The method for measuring the MIBK / water distribution ratio is the method described in the embodiment for carrying out the invention.
In the example using the epoxy cross-linking agent, when adding, it is added after mixing with the same amount of diethylene glycol.

2. 2. Manufacture and evaluation of cured film [Manufacturing of cured film]
(A) Preparation of Dip Molding Composition To 250 g of a solution of XNBR, 100 g of water was added to dilute and stirring was started.
Then, after preliminarily adjusting the pH to 9.2 to 9.3 using a 5 wt% potassium hydroxide aqueous solution, a halohydrin cross-linking agent (so that the content of the halohydrin compound is 1.0 part by weight) is added. It was. 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 is adjusted to 22% by adding water, and then used. Continued stirring in the beaker until.
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.
The film in this example is a film that has been dipped 24 hours after the addition of the halohydrin cross-linking agent.
In addition, when a part of the above conditions is changed by an Example, the condition is described for each Example.

(B) Preparation of coagulating solution 0.56 g of surfactant "Teric 320" manufactured by Huntsman Corporation was dissolved in 42.0 g of water, and "S-9" manufactured by CRESTAGE INDUSTRY as a release agent ( 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%. About 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 Using the above XNBR and the above halohydrin cross-linking agent, a cured film is prepared every 24 hours (1 day) elapsed time from the addition of the epoxy cross-linking agent to the dip molding composition (latex). did.
Specifically, the dip molding composition was filtered through a 200-mesh nylon filter at room temperature, then placed in a dipping container, and a porcelain plate at 70 ° C. to which the above coagulating liquid was attached was immersed.
Specifically, the porcelain plate was immersed for 6 seconds, held for 4 seconds, and withdrawn over 3 seconds. The latex was held in the air until it did not drip, and the latex droplets adhering to the tip were gently shaken off.
The cured film precursor that aggregated and formed a film on a ceramic plate was dried at 80 ° C. for 2 minutes (gelling step) and leached with warm water at 50 ° C. for 2 minutes.
Then, it was dried at 70 ° C. for 5 minutes and thermoset at 130 ° C. for 30 minutes.
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.
In addition, when a part of the above conditions is changed by an Example, the condition is described for each Example.

[Evaluation of cured film]
<Tensile strength, tensile elongation>
A JIS K6251 No. 5 dumbbell test piece was cut out from the cured film, and using A &D's TENSILON universal tensile tester RTC-1310A, the test speed was 500 mm / min, the distance between chucks was 75 mm, and the distance between marked lines was 25 mm. MPa) was measured.
The tensile elongation was calculated based on the following formula.
Tensile elongation rate (%) = 100 × (distance between marked lines at break in tensile test-distance between marked lines) / distance between marked lines

<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.
<Stress retention rate>
The stress retention rate was determined according to the above method.

2. 2. Experimental example (1) Experiment 1
During this experiment, Experimental Example 1 is a physical property of a film crosslinked only with zinc oxide as a reference example.
Experimental Examples 2 to 5 show the physical characteristics of the film when zinc oxide is fixed at 1.0 part by weight and chlorohydrin is changed to 0.25 to 3.0 parts by weight (chlorohydrin compound amount).
Experimental Examples 6 and 7 are films prepared using 1.0 part by weight of chlorohydrin and 0.5 part by weight of zinc oxide. As the pH adjuster, 6 is ammonia and 7 is the physical characteristics of the film when KOH is used. is there.
The results of the experiments conducted using each film are shown in Table 4 below.

Experimental Examples 2 to 7 correspond to the first embodiment of the present invention, but if the amount of chlorohydrin added is 1.0 part by weight or more, the film prepared by using chlorohydrin as a cross-linking agent has the normal physical characteristics of gloves. You can see that you are satisfied.
Looking at Experimental Examples 1 to 5, when zinc oxide is fixed at 1.0 part by weight and the amount of chlorohydrin is increased, the fatigue durability increases accordingly, so that chlorohydrin is surely crosslinked. It can be seen that it is contributing. Further, looking at Experimental Examples 2 to 5, it can be seen that the cross-linking reaction is proceeding even if the tensile elongation decreases as the amount of chlorohydrin increases.
From these results, it was found that the film using chlorohydrin can make gloves having excellent fatigue durability, tensile strength, and tensile elongation.

3. 3. Experiment 2
During this experiment, Experimental Examples 8 to 11 are films prepared by using the chlorohydrin cross-linking agent and the epoxy cross-linking agent of the second embodiment in combination without using zinc oxide, and Experimental Examples 12 to 15 are reference examples. This is a conventional film to which an epoxy cross-linking agent and zinc oxide are added, and the physical characteristics of each film are measured.
The results of experiments conducted using each film are shown in Table 5 below. The amount of chlorohydrin in Table 5 below is the amount of the chlorohydrin compound, and the amount of epoxy is the amount of the epoxy compound.

Experimental Examples 8 and 12, 9 and 13, 10 and 14, 11 and 15 use the same latex, one is cross-linking with chlorohydrin and epoxy, and the other is cross-linking with epoxy and zinc oxide. .. It can be seen that the stress retention rate is higher when chlorohydrin is used instead of zinc oxide.
Further, it can be seen that the stress retention rate of the epoxy cross-linking agent itself is further increased by adding chlorohydrin based on the fact that the stress retention rate is originally superior to that of the sulfur-crosslinked XNBR gloves.
In Experimental Example 11, the stress retention rate is 67.8%, which is incredibly high as the stress retention rate of the XNBR gloves.
Also, looking at the tensile elongation, the value is 500% or more, and when the sulfur vulcanized XNBR gloves increase the amount of sulfur added to increase the crosslink density and increase the stress retention, the elongation increases. It's amazing considering that it's going down to the extreme.
Further, in the first embodiment, fatigue durability was not obtained unless chlorohydrin was 1.0 part by weight, but when chlorohydrin and epoxy, which are the second embodiment, were used in combination, chlorohydrin was 0. It was also found that even 5 parts by weight can satisfy all the physical characteristics of gloves.

4. Experiment 3
In Experimental Examples 16 to 20 in this experiment, when 1.0 part by weight of chlorohydrin (amount of chlorohydrin compound) and 1.0 part by weight of zinc oxide were added to prepare a film, the pot of the dip molding composition was used. Life) is seen. The results of experiments conducted using each film are shown in Table 6 below. The fatigue durability in Table 6 below indicates the fatigue durability of the film obtained from the dip molding composition in which stirring was continued for the number of days shown as the pot life after preparation.

Looking at the above experimental results, the fatigue durability is at a very high level of 279 minutes even when the stirring time is 6 days, and the pot life of the chlorohydrin cross-linking agent is 6 days or more even if it is water-soluble. This is a sufficient number of days even when considering actual production.

5. Experiment 4
In Experimental Examples 21 to 24 in this experiment, when making a film to which 1.0 part by weight of chlorohydrin (amount of chlorohydrin compound) and 1.0 part by weight of zinc oxide was added, which is the first embodiment, Experimental Example 4 The cross-linking agents B, C, and D are used in place of the cross-linking agent A.
The results are shown in Table 7. Fatigue durability was significantly improved from 72 minutes in Experimental Example 1 in which only zinc oxide was added, and both tensile strength and tensile elongation were good. Further, the stress retention rate was higher than that of the cross-linking agent A and exceeded 50%. This is because the cross-linking agents B, C, and D have a high MIBK / water distribution ratio and are poorly soluble in water, and have strong lipophilicity, and enter the XNBR particles to form an intra-particle cross-link. Conceivable.

Claims

A cross-linking agent for dip molding containing a halohydrin compound having at least two halohydrin groups D represented by the following formula (I) in one molecule.

In the above formula (I), R 1 is a hydrogen or alkyl group, and X is a halogen group.
The cross-linking agent for dip molding according to claim 1, wherein the halohydrin compound is a halohydrin compound having at least one halohydrin group Da represented by the following formula (Ia) in the molecule as the halohydrin group D.

In the above formula (Ia), R 1 is a hydrogen or alkyl group, and X is a halogen group.
The cross-linking agent for dip molding according to claim 2, wherein the halohydrin compound is a halohydrin compound represented by the following formula (II).

In the above formula (II), R 2 is a (k + m) -valent aliphatic hydrocarbon group having 2 to 10 carbon atoms, X is a halogen group, and k and m are 2 ≦ k ≦ 6,0. It is an integer that satisfies ≦ m ≦ 4 and 2 ≦ k + m ≦ 6.
The crosslink for dip molding according to any one of claims 1 to 3 with an elastomer containing a structural unit derived from (meth) acrylonitrile, a structural unit derived from unsaturated carboxylic acid, and a structural unit derived from butadiene in the polymer main chain. A composition for dip molding, which comprises an agent.
The dip molding composition according to claim 4, wherein the structural unit derived from (meth) acrylonitrile is 12 to 35% by weight and the structural unit derived from unsaturated carboxylic acid is 2 to 10% by weight in the elastomer.
The composition for dip molding according to claim 4 or 5, further containing an epoxy cross-linking agent containing an epoxy compound having at least three epoxy groups in one molecule.
A glove that is a cured product of the dip molding composition according to any one of claims 4 to 6.
(1) Coagulation and adhesion step of adhering a coagulant to a glove molding mold,
(2) A stirring step of adjusting and stirring the dip molding composition according to any one of claims 1 to 6.
(3) A dipping step of immersing the glove molding mold in the dip molding composition,
(4) Gelling step of gelling the film formed on the glove molding to make a cured film precursor.
(5) A leaching step of removing impurities from the cured film precursor formed on the glove molding mold,
(6) Beading process to make a roll around the cuffs of gloves,
(7) Step of heating and drying at a temperature required for a cross-linking reaction A method for manufacturing a glove, which comprises a curing step and performs the above steps (3) to (7) in the above order.