JP7190214B2 - Glove manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing gloves.

As a glove with improved anti-slip properties, there is known a glove that includes a fiber glove body covering the wearer's hand and a coating layer that covers the outer surface of the palm area of the glove body. Among them, as a glove that can be suitably used for oil work etc., a glove having a coating layer with nitrile-butadiene rubber as the main component has been proposed (see Japanese Patent Laid-Open No. 2015-129362).

This glove is manufactured by forming a covering layer, for example, in the following procedure. First, after the glove body is immersed in a coagulant, the glove body is immersed in a raw material containing nitrile-butadiene rubber latex. Next, the film formed on the outer surface of the glove body by this immersion is dried to form a coating layer on the outer surface of the glove body.

Since 50% by mass or more of the latex raw material is water, the undried film immediately after immersion contains a large amount of water. For this reason, the coating is likely to shrink during the drying process, and cracks are likely to occur in the coating layer of the produced glove. These cracks not only deteriorate the appearance of the gloves, but also tend to cause cracks in the coating layer starting from the cracks.

JP 2015-129362 A

SUMMARY OF THE INVENTION The present invention has been made in view of these circumstances, and an object of the present invention is to provide a glove in which cracks in a covering layer containing nitrile-butadiene rubber as a main component are reduced.

The present inventors have found that cracks are dramatically reduced in a coating layer formed by simultaneously blending polycarbodiimide and zinc oxide into a nitrile-butadiene rubber latex raw material, and have completed the present invention. Although the detailed mechanism by which cracks are reduced is not clear, the polarity of zinc oxide fixes the positions of the polar groups in the nitrile-butadiene rubber and the carbodiimide groups of the polycarbodiimide. It is believed that this is because the carbodiimide groups of polycarbodiimide are readily reacted with each other, promoting cross-linking. In other words, it is considered that the effect of accelerating the cross-linking prevented cracks by resisting shrinkage of the coating when the coating layer was formed.

That is, the invention made to solve the above-mentioned problems comprises a fiber glove body that covers the wearer's hand, and a glove body that covers at least a part of the outer surface of the palm area of the glove body and contains nitrile-butadiene rubber as a main component. wherein the coating layer contains a crosslinked product of the nitrile-butadiene rubber and polycarbodiimide and zinc oxide, and the mass ratio of the polycarbodiimide to the nitrile-butadiene rubber is 0.002 or more. be.

In the glove, the coating layer contains zinc oxide and a crosslinked product of nitrile-butadiene rubber and polycarbodiimide, and the mass ratio of polycarbodiimide to nitrile-butadiene rubber is at least the above lower limit. Therefore, the glove is less prone to cracks in the covering layer due to cross-linking of nitrile-butadiene rubber and polycarbodiimide. Therefore, the glove has an excellent appearance, the coating layer is less likely to crack, and the glove has excellent durability, oil resistance, and chemical resistance.

The mass ratio of the polycarbodiimide to the nitrile-butadiene rubber is preferably 0.09 or less. By setting the mass ratio of the polycarbodiimide to the upper limit or less, the flexibility of the glove is improved.

The content of the zinc oxide with respect to 100 parts by mass of the nitrile-butadiene rubber is preferably 0.3 parts by mass or more and 5 parts by mass or less. By setting the zinc oxide content within the above range, the strength of the coating layer can be improved while ensuring the flexibility of the glove.

The crosslinked product of nitrile-butadiene rubber and polycarbodiimide preferably has a carboxyl group, a carbodiimide group, and a group formed by reaction between the carboxyl group and the carbodiimide group. The positions of the carboxyl group and the carbodiimide group are easily fixed by zinc oxide, and the carboxyl group and the carbodiimide group are easily brought close to each other. Therefore, reaction-generated groups between carboxyl groups and carbodiimide groups are likely to be generated during production of the glove, and cross-linking is likely to be promoted. Therefore, the occurrence of cracks can be further suppressed.

The molar ratio of the sum of the carbodiimide groups and the reaction product groups to the sum of the carboxyl groups and the reaction product groups is preferably 0.008 or more and 1 or less. By setting the molar ratio within the above range, it is possible to further suppress the occurrence of cracks while ensuring the flexibility of the glove, and to improve the tensile strength.

Here, the "main component" is the component with the highest content, for example, a component with a content of 50% by mass or more.

As explained above, the glove of the present invention can reduce cracks in the covering layer containing nitrile-butadiene rubber as a main component. Therefore, the glove of the present invention has an excellent appearance, the coating layer is less susceptible to cracking, and excellent durability, oil resistance, and chemical resistance.

1 is a schematic view of a glove according to one embodiment of the present invention, viewed from the palm side; FIG. 2 is a partial cross-sectional view of the glove of FIG. 1; FIG. 4 is a graph showing measurement results of tensile strength in Examples.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.

The glove of FIG. 1 comprises a fiber glove body 1 that covers a wearer's hand, and a covering layer 2 that covers the outer surface of the palm area of the glove body 1 .

<Glove body>
The glove body 1 is made by knitting fibers into a glove shape. The glove body 1 includes a bag-shaped main body to cover the hands of the wearer, extensions extending from the main body to cover the fingers of the wearer, and wrists of the wearer. and a cylindrical bottom portion extending from the body portion in a direction opposite to the extension portion. The extension part is the first finger part covering the wearer's first finger (thumb), second finger (index finger), third finger (middle finger), fourth finger (ring finger) and fifth finger (little finger). , a second finger, a third finger, a fourth finger and a fifth finger. The first to fifth fingers are formed in a cylindrical shape with closed fingertips. Further, the skirt portion has an opening into which the wearer's hand can be inserted.

The fibers constituting the glove body 1 are not particularly limited, and natural fibers, synthetic fibers, inorganic fibers, and the like can be used. Examples of the natural fibers include cotton, silk, wool, hemp, and the like. Examples of the synthetic fibers include polyethylene fibers, polyester fibers, nylon fibers, aramid fibers, ultra-strong polyethylene fibers, polyurethane fibers, polyamide fibers, rayon fibers, acrylic fibers, and polyparaphenylene terephthalamide fibers. Examples of the inorganic fibers include stainless fibers, tungsten fibers, and glass fibers.

The glove body 1 is formed using yarns made of the fibers described above. Examples of these yarns include spun yarns, filament yarns, crimped yarns, and the like. Moreover, the fibers used for these yarns may be of one type or may be a mixture of two or more types. For example, yarns using a mixture of two types of fibers include spun yarns obtained by blending cotton and polyester short fibers, and composite yarns obtained by covering stainless steel fibers with nylon or the like.

The glove body 1 may be formed by cutting a woven fabric, knitted fabric or non-woven fabric using the above fiber into the shape of a glove and sewing it, but it is preferably formed by seamlessly knitting with a seamless knitting machine. . By using the glove body 1 formed by knitting with a seamless knitting machine, the glove is excellent in manufacturing cost, flexibility, and wearing feeling. When the glove body 1 is knitted by a seamless knitting machine, the knitting gauge number of the glove body 1 is desirably 10 gauge or more and 26 gauge or less.

The lower limit of the average thickness of the glove body 1 is preferably 0.1 mm, more preferably 0.2 mm. On the other hand, the upper limit of the average thickness of the glove body 1 is preferably 1.3 mm, more preferably 1.0 mm. If the average thickness of the glove body 1 is less than the above lower limit, the glove itself may lack strength and be less durable. Conversely, if the average thickness of the glove body 1 exceeds the upper limit, the thickness of the glove increases, which may reduce flexibility and reduce workability when worn. The average thickness is the average value obtained by measuring five arbitrary points using a JIS-L1086/L1096-compliant constant-pressure thickness measuring device (for example, Teclock's "PG-15"). .

In addition, the glove body 1 may be subjected to various treatments using, for example, a softening agent, a water and oil repellent, an antibacterial agent, etc., or may be coated or impregnated with an ultraviolet absorber or the like to provide an ultraviolet prevention function. may be given. In addition, the fiber itself used for the glove body 1 may be kneaded with a chemical agent exhibiting such a function.

<Coating layer>
The coating layer 2 is mainly composed of nitrile-butadiene rubber. Moreover, the coating layer 2 contains a crosslinked product of nitrile-butadiene rubber and polycarbodiimide and zinc oxide.

The coating layer 2 is preferably impregnated into the glove body 1 as shown in FIG. On the other hand, it is preferable that the coating layer 2 does not permeate the inner surface of the glove body 1 . By impregnating the glove body 1 with the coating layer 2 and not penetrating to the inner surface of the glove body 1, peeling of the coating layer 2 can be suppressed while suppressing deterioration of the tactile sensation of the inner surface of the glove.

(Nitrile butadiene rubber)
Nitrile-butadiene rubber is formed by copolymerizing acrylonitrile and butadiene as monomers.

The lower limit of the amount of acrylonitrile compounded with respect to 100 parts by mass of nitrile-butadiene rubber is preferably 20 parts by mass, more preferably 25 parts by mass. On the other hand, the upper limit of the acrylonitrile content is preferably 40 parts by mass, more preferably 35 parts by mass, and even more preferably 30 parts by mass. If the amount of acrylonitrile blended is less than the above lower limit, the glove may have reduced oil resistance and durability. Conversely, if the blending amount of acrylonitrile exceeds the above upper limit, the flexibility of the glove may decrease.

The lower limit of the amount of butadiene compounded with respect to 100 parts by mass of the nitrile-butadiene rubber is preferably 55 parts by mass, more preferably 57 parts by mass, and even more preferably 62 parts by mass. On the other hand, the upper limit of the amount of butadiene compounded is preferably 78 parts by mass, more preferably 72 parts by mass, and even more preferably 70 parts by mass. If the amount of butadiene blended is less than the above lower limit, the flexibility of the glove may decrease. Conversely, if the blending amount of butadiene exceeds the upper limit, the oil resistance and durability of the glove may deteriorate.

The nitrile-butadiene rubber may be copolymerized with known monomers as long as the strength and flexibility of the glove can be ensured. Examples of such monomers include monomers having polar groups such as carboxyl groups, sulfonic acid groups, acid anhydride groups, and amide groups. Examples of the monomer having a carboxyl group include ethylenically unsaturated monocarboxylic acid monomers such as acrylic acid, methacrylic acid, crotonic acid and cinnamic acid. Examples of the monomer having sulfonic acid include ethylenically unsaturated acid monomers such as styrenesulfonic acid. Examples of the monomer having an acid anhydride group include ethylenically unsaturated acid monomers such as maleic anhydride and citraconic anhydride. Examples of the amide group-containing monomer include ethylenically unsaturated carboxylic acid amide monomers such as (meth)acrylamide, N,N-dimethylacrylamide and N-methylolacrylamide. After copolymerization, these polar groups can enhance the stability of the latex from which the coating layer 2 is made. Specifically, some of these form pairs with monovalent cations such as potassium ions, sodium ions and ammonium ions in the latex raw material and stabilize the nitrile-butadiene rubber latex particles in aqueous solvents. Part or all of the polar groups (including ionized products) react with polycarbodiimide and zinc oxide contained in the coating layer 2 to form covalent bonds with carbodiimide groups and metal bonds with zinc ions. Thereby, the cross-linking of the coating layer 2 can be promoted. Among them, it is preferable to use methacrylic acid or acrylic acid as a monomer from the viewpoint of stability and physical properties.

The lower limit of the amount of methacrylic acid or acrylic acid compounded with respect to 100 parts by mass of nitrile-butadiene rubber is preferably 2 parts by mass, more preferably 3 parts by mass. On the other hand, the upper limit of the amount of methacrylic acid or acrylic acid is preferably 10 parts by mass, more preferably 8 parts by mass. If the amount of methacrylic acid or acrylic acid is less than the above lower limit, the effect of improving the stability of the latex raw material may be insufficient, and the effect of promoting cross-linking of the coating layer 2 may be insufficient. Conversely, if the blending amount of methacrylic acid or acrylic acid exceeds the above upper limit, the coating layer 2 tends to shrink when dried, and cracks may easily occur and the flexibility of the glove may decrease.

In addition, the nitrile-butadiene rubber generally contains an emulsifier, a pH adjuster, a cross-linking agent, a vulcanizing agent, a vulcanization accelerator, a thickener, a heat-sensitive agent, an antioxidant, a surfactant, and a plasticizer. It may contain agents and the like. Among these, from the viewpoint of improving the film formability, strength and solvent resistance of the coating layer 2, it is preferable to include a vulcanizing agent or a vulcanization accelerator.

Examples of the vulcanizing agent include powdered sulfur, sulfur flowers, precipitated sulfur, colloidal sulfur, surface-treated sulfur, and insoluble sulfur. These may be used alone or in combination of two or more. Among these, colloidal sulfur is preferred.

The amount of the vulcanizing agent compounded with respect to 100 parts by mass of nitrile-butadiene rubber is preferably 0.1 parts by mass or more and 3.0 parts by mass or less. If the amount of the vulcanizing agent to be blended is less than the above lower limit, the effect of improving the strength may be insufficient. Conversely, if the content of the vulcanizing agent exceeds the upper limit, the glove may feel stiff to the touch.

Examples of the vulcanization accelerator include dithiocarbamate-based vulcanization accelerators such as zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, and zinc dibutyldithiocarbamate; thiazole-based vulcanization accelerators such as zinc 2-mercaptobenzothiazole; , thiourea-based, and guanidine-based vulcanization accelerators. These may be used alone or in combination of two or more. Among these, dithiocarbamic acid-based ones are preferred.

The amount of the vulcanization accelerator compounded with respect to 100 parts by mass of nitrile-butadiene rubber is preferably 0.5 parts by mass or more and 5.0 parts by mass or less. If the amount of the vulcanization accelerator is less than the above lower limit, the effect of accelerating vulcanization may be insufficient. Conversely, if the content of the vulcanization accelerator exceeds the above upper limit, the glove may have a hard feel, or the initial vulcanization may proceed to cause a scorch phenomenon.

(Polycarbodiimide)
Polycarbodiimide is a compound having multiple carbodiimide groups in one molecule. As such a polycarbodiimide, a polymer synthesized by a condensation reaction accompanied by decarbonization of an organic diisocyanate compound can be used. Examples of the organic diisocyanate compounds include aromatic diisocyanate compounds, aliphatic diisocyanate compounds, alicyclic diisocyanate compounds, and mixtures thereof. Specifically, toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, a mixture of toluene-2,4-diisocyanate and toluene-2,6-diisocyanate, diphenylmethane-4,4-diisocyanate, 1, 4-phenylene diisocyanate, dicyclohexyl-methane-4,4'-diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 1,6-hexyl diisocyanate, 1,4-cyclohexyl diisocyanate, norbornyl diisocyanate etc. Among them, dicyclohexyl-methane-4,4'-diisocyanate and 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate are preferred.

Specific examples of the polycarbodiimide include V-02 (590), V-02-L2 (385), SV-02 (430), V-04 (335), V-10 (410) manufactured by Nisshinbo Chemical Co., Ltd. ), SW-12G (465), E-02 (445), E-03A (365), E-05 (310) and the like. In addition, the numerical value in () means a carbodiimide equivalent. Moreover, XR-5508, XR-5577, XR-5580, XR-13-554, etc. manufactured by Stahl Japan Co., Ltd. can also be used. Among them, E-02, E-03A, E-05, and XR-5508, which are aqueous solvent-based and have excellent pot life performance of the blended raw materials, are preferred.

A carbodiimide group reacts with a polar group in the nitrile-butadiene rubber to form a crosslinked product. Therefore, in the formation of the coating layer 2, the film-forming property after drying is improved, and cracks can be reduced. As will be described later, the coating layer 2 is formed by immersing the glove body 1 in a latex raw material containing nitrile-butadiene rubber, polycarbodiimide and zinc oxide. It is considered that a cross-linking reaction occurs and enhances the effect of improving the film formation of zinc oxide.

As a minimum of the carbodiimide equivalent of the said polycarbodiimide, 200 are preferable and 250 are more preferable. On the other hand, the upper limit of the carbodiimide equivalent is preferably 1,000, more preferably 650. If the carbodiimide equivalent is less than the lower limit, the glove may have reduced flexibility. Conversely, if the carbodiimide equivalent exceeds the upper limit, the carbodiimide group may not sufficiently promote cross-linking. Here, the carbodiimide equivalent represents the mass [g] of the carbodiimide compound required to give 1 mol of carbodiimide groups, and is a numerical value obtained by dividing the molecular weight of the carbodiimide compound by the number of carbodiimide groups possessed by the carbodiimide compound. is.

The lower limit of the mass ratio of the polycarbodiimide to the nitrile-butadiene rubber is 0.002, more preferably 0.004. On the other hand, the upper limit of the mass ratio of polycarbodiimide is preferably 0.09, more preferably 0.06. If the mass ratio of the polycarbodiimide is less than the above lower limit, the effect of reducing cracks in the coating layer 2 may be insufficient, and the tensile strength of the coating layer 2 may decrease. Conversely, when the mass ratio of the polycarbodiimide exceeds the upper limit, the flexibility of the glove may decrease.

The crosslinked product of nitrile-butadiene rubber and polycarbodiimide preferably has a carboxyl group, a carbodiimide group, and a group formed by reaction between the carboxyl group and the carbodiimide group. The carboxyl groups are easily fixed in position by zinc oxide, and tend to be close to each other. Therefore, reaction-generated groups between carboxyl groups and carbodiimide groups are likely to be generated during production of the glove, and cross-linking is likely to be promoted. Therefore, the occurrence of cracks can be further suppressed.

When the above-mentioned crosslinked product of nitrile-butadiene rubber and polycarbodiimide has carboxyl groups and reaction-generated groups of carboxyl groups and carbodiimide groups, the sum of the carbodiimide groups and the reaction-generated groups with respect to the total of the carboxyl groups and the reaction-generated groups is preferably 0.008, more preferably 0.01, still more preferably 0.015, and particularly preferably 0.02. On the other hand, the upper limit of the molar ratio is preferably 1, more preferably 0.5, and even more preferably 0.3. If the molar ratio is less than the lower limit, the effect of reducing cracks in the coating layer 2 may become insufficient, and the tensile strength of the coating layer 2 may decrease. Conversely, if the molar ratio exceeds the upper limit, the flexibility of the glove may decrease.

(zinc oxide)
Zinc oxide interacts with the polar groups of the nitrile-butadiene rubber and improves the film-forming properties of the coating layer 2 after being immersed in the latex raw material. However, the film-forming effect of zinc oxide alone is relatively low. Cracks may occur in the coating layer 2 due to unbearable resistance. On the other hand, in the glove, since polycarbodiimide and zinc oxide are included to enhance the effect of improving the film formation, cracks are less likely to occur in the coating layer 2 .

The lower limit of the zinc oxide content relative to 100 parts by mass of nitrile-butadiene rubber is preferably 0.3 parts by mass, more preferably 1 part by mass. On the other hand, the upper limit of the zinc oxide content is preferably 5 parts by mass, more preferably 4 parts by mass, and even more preferably 3.5 parts by mass. If the zinc oxide content is less than the above lower limit, the strength of the coating layer 2 may be insufficient. Conversely, if the content of zinc oxide exceeds the upper limit, the flexibility of the glove may decrease, the strength of the coating layer 2 may decrease due to excessive zinc oxide, and the latex raw material may become unstable. There is a risk of

When the nitrile-butadiene rubber has carboxyl groups, the lower limit of the molar ratio of zinc oxide to carboxyl groups is preferably 0.1, more preferably 0.2. On the other hand, the upper limit of the molar ratio of zinc oxide to carboxyl groups is not particularly limited, but is preferably 1, more preferably 0.5. If the molar ratio of zinc oxide is less than the lower limit, the effect of reducing cracks in the coating layer 2 may be insufficient. Conversely, if the molar ratio of zinc oxide exceeds the upper limit, the excess zinc oxide may deteriorate the coating layer 2 .

The lower limit of the molar ratio of zinc oxide to carbodiimide groups is preferably 1, more preferably 5. On the other hand, the upper limit of the molar ratio of zinc oxide to carbodiimide groups is preferably 50, more preferably 40, and even more preferably 35. If the molar ratio of zinc oxide to the carbodiimide group is less than the above lower limit, the amount of zinc oxide is relatively small, and the effect of reducing cracks in the coating layer 2 may be insufficient. Conversely, if the molar ratio of zinc oxide to the carbodiimide groups exceeds the upper limit, the amount of carbodiimide groups becomes relatively small, and the effect of reducing cracks in the coating layer 2 may be insufficient.

<Glove manufacturing method>
The glove can be manufactured by forming the coating layer 2 on the outer surface of the glove body 1 by dipping. Specifically, the glove can be manufactured by a glove manufacturing method including, for example, a step of dipping in a coagulant solution, a step of dipping in a latex raw material, and a drying step. Each step will be described below.

(Step of immersion in coagulant solution)
In the step of dipping in the coagulant solution, the prepared glove body 1 is put on the hand mold for forming the glove, the hand mold is dipped in the coagulant solution, and after being lifted up, the solvent is volatilized.

As the coagulant solution, a known solution such as a methanol solution or an aqueous solution containing a polyvalent metal salt or an organic acid can be used. Among them, it is preferable to contain a polyvalent metal salt. By including the polyvalent metal salt in the coagulant solution, excessive permeation of the latex raw material into the glove body 1 can be easily suppressed.

Examples of polyvalent metal salts include barium chloride, calcium chloride, magnesium chloride, zinc chloride, aluminum chloride, barium nitrate, calcium nitrate, zinc nitrate, barium acetate, calcium acetate, zinc acetate, calcium sulfate, magnesium sulfate, aluminum sulfate, and the like. can be mentioned. Although these may be used individually, they can also be used in combination of 2 or more types.

The lower limit of the polyvalent metal salt content in the coagulant solution is preferably 0.3% by mass, more preferably 0.8% by mass. On the other hand, the upper limit of the polyvalent metal salt content is not particularly limited as long as peeling of the coating layer 2 from the glove body 1 can be suppressed, but is preferably 5% by mass, more preferably 3% by mass. If the content of the polyvalent metal salt is less than the lower limit, it is not possible to sufficiently prevent the nitrile-butadiene rubber from penetrating into the inner surface of the glove body 1 in the later-described immersion step in the latex raw material, and the inner surface of the glove is damaged. The tactile sensation may deteriorate. Conversely, if the content of the polyvalent metal salt exceeds the upper limit, cracks may easily occur in the coating layer 2 due to abrupt aggregation of the coating formed after immersion in the latex raw material. Since penetration into the glove body 1 is insufficient, the coating layer 2 may easily peel off from the glove body 1 .

Moreover, acetic acid, citric acid, etc. can be mentioned as said organic acid. The content of the organic acid in the coagulant solution is preferably 5% by mass or more and 35% by mass or less. This organic acid can be used alone, but is preferably used in combination with a polyvalent metal salt. By mixing with a polyvalent metal salt and using it, it is possible to prevent the thickness of the coating layer 2 from becoming thin. In addition, it becomes easier to control the film-forming ability of the coagulant solution than when each of them is used alone.

The temperature of the hand mold when the hand mold is immersed in the coagulant solution is preferably 40° C. or higher and 70° C. or lower from the viewpoint of permeation of the coagulant into the glove body 1 .

The temperature for volatilizing the solvent after immersion in the coagulant solution and pulling out is preferably 25° C. or higher and 70° C. or lower, and the time for volatilizing the solvent is preferably 10 seconds or longer and 600 seconds or shorter. This volatilization of the solvent makes it possible to control the permeation of the latex raw material in the next step. It is possible to prevent peeling of the coating layer 2 . From the viewpoint of controlling permeation of the latex raw material, when the solvent is methanol, it is more preferably 10 seconds or more and 60 seconds or less, and when the solvent is water, it is more preferably 30 seconds or more and 600 seconds or less.

(Step of immersion in latex raw material)
In the step of dipping into the latex raw material, the hand model covered with the glove main body 1 after the step of dipping into the coagulant solution is dipped into the latex raw material and pulled up.

The latex raw material is a mixture of nitrile-butadiene rubber latex and polycarbodiimide and zinc oxide. The amounts of polycarbodiimide and zinc oxide to be blended are adjusted so that the content of the crosslinked product of nitrile-butadiene rubber and polycarbodiimide after formation of the coating layer and the content of zinc oxide are desired values. Additives such as a vulcanizing agent, a vulcanization accelerator, and a surfactant may be added as necessary.

(Drying process)
In the drying step, the hand pattern covered with the glove body 1 after the dipping step in the latex raw material is dried. Specifically, the coating layer 2 is formed by promoting the cross-linking reaction after evaporating water in the coating formed by immersion in the latex raw material. This drying step can be performed, for example, using a known oven.

This drying step may be performed in a high temperature environment immediately after the hand mold is immersed in the latex raw material, but it is performed in a high temperature environment after the hand mold is held at room temperature (20° C. or higher and 40° C. or lower) for a certain period of time. is preferred. The inventors of the present invention are aware that the effect of preventing the occurrence of cracks is enhanced by providing the time for holding the hand mold at room temperature.

The retention time at room temperature is preferably 20 seconds or more and 200 seconds or less. If the holding time at room temperature is less than the lower limit, uneven drying tends to occur, and cracks may easily occur in the coating layer 2 . Conversely, if the holding time at room temperature exceeds the upper limit, there is a risk that the production efficiency will be reduced, or that the undried coating will sag.

The temperature for evaporating water in a high-temperature environment is preferably 50° C. or higher and 100° C. or lower. If the temperature is lower than the lower limit, the undried film may sag and the coating layer 2 may become non-uniform. Conversely, if the temperature exceeds the upper limit, uneven drying tends to occur due to rapid drying, and strong tension is likely to be applied to the film in some areas. As a result, the film tends to shrink, and cracks tend to occur in the coating layer 2 . Moreover, the time for evaporating water after the temperature rise is preferably 10 minutes or more and 30 minutes or less from the viewpoint of production efficiency.

The temperature for promoting the cross-linking reaction is preferably 100° C. or higher and 150° C. or lower. If the temperature at which the cross-linking reaction is promoted is below the above lower limit, the cross-linking reaction may not be sufficiently promoted. Conversely, if the temperature for promoting the cross-linking reaction exceeds the above upper limit, the cross-linking reaction may be uneven, and the glove body 1 and the coating layer 2 may be deteriorated by heat.

After evaporating water and accelerating the cross-linking reaction, the glove body 1 with the coating layer 2 formed thereon is removed from the hand mold to obtain the glove.

In this glove manufacturing method, both polycarbodiimide and zinc oxide are mixed in the latex raw material, so that moderate cross-linking is formed when the hand mold is immersed in the latex raw material after being immersed in the coagulant and when the water evaporates. and the obtained gloves are less prone to cracks.

In addition, coagulants, surfactants, etc. may bloom or bleed from the film. In this case, after the moisture has evaporated, the hand mold may be immersed in a water tank, or the glove removed from the hand mold may be washed. etc. can be removed. The removal of the coagulant, surfactant, etc. can be performed after evaporation of water in the drying step or after the cross-linking reaction.

<Advantages>
In the glove, the coating layer 2 contains zinc oxide and a crosslinked product of nitrile-butadiene rubber and polycarbodiimide, and the mass ratio of the polycarbodiimide to the nitrile-butadiene rubber is set to 0.002 or more, so nitrile-butadiene rubber and polycarbodiimide Due to the cross-linking of the glove, cracks in the coating layer 2 are less likely to occur. Therefore, the glove is excellent in appearance, cracks are less likely to occur in the coating layer 2, and is excellent in durability, oil resistance, and chemical resistance.

[Other embodiments]
The present invention is not limited to the above-described embodiments, and can be implemented in various modified and improved modes in addition to the above-described modes.

In the above embodiment, the covering layer covers the palm area of the glove body, but may also cover the back side area of the glove body. By forming a coating layer also on the area on the back side of the hand, the protection function of the area on the back side of the hand of the glove can be improved.

In addition, the covering range of the covering layer does not have to be the entire palm area of the glove body, and may be a part of the palm area.

Concavities and convexities may be formed on the coating layer. By forming unevenness in this way, the anti-slip effect of the glove is enhanced. Examples of the shape of the protrusions forming the unevenness include a structure (honeycomb shape) in which a plurality of approximately hexagonal protrusions are arranged in the same direction at regular intervals.

Also, the coating layer may be a foam layer. By using a foam layer as the covering layer in this manner, the anti-slip effect and breathability of the glove are enhanced. Examples of the method for forming the foam layer include a method of coating a mechanically foamed latex raw material, a method of heating a latex raw material containing a chemical foaming agent to foam it, and the like.

EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples, but the invention is not limited to the following examples.

[Example 1]
Using a 13-gauge glove knitting machine ("N-SFG" manufactured by Shima Seiki Seisakusho Co., Ltd.), a seamless knitted glove body was prepared using 280 d woolly nylon (two 70 d two-ply yarns). In addition, a coagulant solution having a calcium nitrate concentration shown in Table 1, and polycarbodiimide (“CARBODILITE E-02” manufactured by Nisshinbo Chemical Co., Ltd., carbodiimide equivalent 445) and zinc oxide (positive A latex raw material containing, as a main component, nitrile-butadiene rubber (NBR) latex (“Nipol LX550L” manufactured by Nippon Zeon Co., Ltd.) mixed with “zinc oxide type 2” manufactured by Nippon Zeon Co., Ltd.) was prepared. The latex raw material was diluted with ion-exchanged water so that the solid content in the latex raw material was 36%.

The prepared glove body was put on a hand mold at a temperature of 55° C., the hand mold was immersed in the above coagulant solution, and after pulling it out, part of the solvent was volatilized. Next, the hand mold was immersed in the latex raw material and pulled out. After that, this glove was subjected to moisture evaporation at 70° C. for 30 minutes, and then accelerated cross-linking at 120° C. for 30 minutes to obtain the glove of Example 1.

[Examples 2 to 11, Comparative Examples 1 and 2]
Performed in the same manner as the gloves of Example 1, except that a coagulant solution having a calcium nitrate concentration shown in Table 1 and a latex raw material containing polycarbodiimide and zinc oxide having a solid content shown in Table 1 were used. Gloves of Examples 2 to 11 and Comparative Examples 1 and 2 were obtained. The solid content in the latex raw material was adjusted by diluting with ion-exchanged water so that the solid content was 36%, the same as in Example 1.

(Visual evaluation)
The stability of the prepared latex raw material, the coating state of the glove after water evaporation and after accelerated cross-linking, the flexibility of the glove, and the permeation and peeling of the coating layer into the glove body were visually evaluated. Each evaluation criterion is shown below. In addition, Table 1 shows the evaluation results.

[Raw material stability evaluation criteria]
A: After storage at 35°C for 1 week, aggregates do not occur even if the liquid surface is stirred to such an extent that the liquid surface does not undulate. After storing at 35°C for 1 week, fine aggregates are generated when the liquid surface is stirred to the extent that it does not undulate. C: Aggregates are generated after being stored at 20°C for 1 week at rest. Agglomeration occurs when blending raw materials

[Evaluation Criteria for Coating State after Moisture Evaporation]
A: Almost no cracks B: Although cracks are slightly generated, they are virtually non-existent C: Cracks are generated, but there is no practical problem D: Many cracks are generated This evaluation criterion is based on the increased number of cracks compared to the state before moisture evaporation.

[Evaluation Criteria for Coating State after Acceleration of Crosslinking]
A: The number of cracks has hardly increased B: The number of cracks has increased slightly, but it is almost the same as not increasing C: The number of cracks has increased D: The number of cracks has increased significantly and is practical This evaluation criterion is based on the number of cracks increased compared to the state after water evaporation.

[Evaluation criteria for flexibility]
A: Excellent in flexibility B: Relatively excellent in flexibility, no practical problem C: Slightly inferior in flexibility, impeding practical use D: Inferior in flexibility

[Evaluation Criteria for Penetration]
A: The coating layer does not penetrate to the inner surface of the glove body D: The coating layer penetrates to the inner surface of the glove body

[Evaluation Criteria for Peeling]
A: Almost no peeling is observed in the coating layer B: Although slight peeling is partially observed when the coating layer is strongly pulled, the range of peeling does not spread and there is no practical problem C: When the coating layer is pulled strongly Partial peeling is observed and the peeling spreads a little, but there is no practical problem.
D: Significant peeling of the coating layer is observed even before the coating layer is pulled, impeding practical use.

From the results in Table 1, the gloves of Examples 1 to 12, in which the coating layer contains a crosslinked product of nitrile-butadiene rubber and polycarbodiimide and zinc oxide, and the mass ratio of polycarbodiimide to nitrile-butadiene rubber is 0.002 or more, There are few cracks both after evaporation of water and after accelerated cross-linking. On the other hand, the glove of Comparative Example 1, which does not contain zinc oxide, cracked during water evaporation, and the glove of Comparative Example 2, which had a polycarbodiimide mass ratio of less than 0.002, cracked during accelerated cross-linking. ing. From this, it can be seen that cracks can be reduced by including a crosslinked product of nitrile-butadiene rubber and polycarbodiimide and zinc oxide in the coating layer and setting the mass ratio of polycarbodiimide to nitrile-butadiene rubber to 0.002 or more.

Further, when comparing Examples 1 to 6 with different mass ratios of polycarbodiimide, in Example 6 where the mass ratio of polycarbodiimide exceeds 0.09, the glove has low flexibility. From this, it can be seen that the flexibility of the glove can be ensured by setting the mass ratio of polycarbodiimide to 0.09 or less.

Further, when comparing Example 3 and Examples 9 to 12 with different zinc oxide contents, cracks were observed in Example 9 with a zinc oxide content of 0.3 parts by mass, although there was no practical problem. In Example 12, in which the content of zinc oxide is 5 parts by weight, the stability of the latex raw material and the flexibility of the glove are reduced. From this, it can be seen that cracks can be reduced while ensuring the stability of the latex raw material and the flexibility of the glove by setting the content of zinc oxide to 0.3 parts by mass or more and 5 parts by mass or less.

Furthermore, when comparing Examples 3, 7, and 8, which have different contents of calcium nitrate, which is a polyvalent metal salt, the glove of Example 7, which has a calcium nitrate content of less than 0.3% by mass, has a glove body Penetration of the coating layer to the inner surface cannot be suppressed. Further, in the glove of Example 8, in which the content of calcium nitrate is more than 5% by mass, the coating layer is easily peeled off from the glove body. Therefore, by setting the content of calcium nitrate, which is a polyvalent metal salt, to 0.3% by mass or more and 5% by mass or less, the coating layer can be prevented from peeling and the coating layer can penetrate into the inner surface of the glove body. It turns out that this can be prevented.

<Crack evaluation of coating layer>
In order to confirm that cracks can be prevented and strength is improved by including a crosslinked product of nitrile-butadiene rubber and polycarbodiimide and zinc oxide in the coating layer, a film of the same components as the coating layer was applied to the bar-shaped unglazed pottery surface. was prepared, and the strength of the coating layer alone was evaluated.

[No. 1]
Three stick-shaped unglazed pottery were prepared. These three pieces of pottery were immersed in a coagulant solution consisting of a methanol solution containing 30% by mass of calcium nitrate, and after being pulled out, the pottery was heated at 60° C. for 1 minute to volatilize the solvent. Next, each of these three pieces of pottery was immersed in a latex raw material containing nitrile-butadiene rubber (NBR) latex as a main component shown in Table 2, and after being pulled out, each of the three pieces of pottery was allowed to evaporate at 40°C for 40 minutes, The cross-linking reaction was accelerated at temperatures of 40° C., 80° C. and 120° C. for 40 minutes. In this way, three film Nos. having different cross-linking reaction temperatures were obtained. got 1. In addition, in the latex raw material of Table 2, water (64% by mass) is included other than the solid content.

[No. 2-4]
Except for using the latex raw materials shown in Table 2, No. No. 1 in the same manner as No. Films 2-4 were obtained in triplicate each.

(Measurement of tensile strength)
Tensile strength was measured for each film produced. The tensile strength was measured using an autograph universal testing machine ("AGS-J" manufactured by Shimadzu Corporation). For the measurement, a test piece was taken from the film using a JIS No. 3 dumbbell, and the sampled test piece was measured under the conditions of a tensile speed of 500 mm/min, a chuck distance of 60 mm, and a marked line interval of 20 mm. The results are shown in FIG.

From the results of FIG. 3, No. 1 using the latex raw material containing only polycarbodiimide. No. 2 film, which does not contain both polycarbodiimide and zinc oxide, regardless of the temperature at which the cross-linking reaction was accelerated. No improvement in tensile strength compared to the film of No. 1 is observed.

No. 3, which uses a latex raw material containing only zinc oxide. In film No. 3, improvement in tensile strength was observed when the cross-linking reaction was promoted at a temperature of 80°C or higher, but no improvement in tensile strength was observed at a temperature of 40°C. That is, No. It can be seen that the film No. 3 requires a temperature of 80° C. or higher to promote the cross-linking reaction.

On the other hand, No. 1, which uses a latex raw material containing polycarbodiimide and zinc oxide. The film of No. 4 shows improvement in tensile strength at all temperatures. That is, No. With the film No. 4, it can be seen that the cross-linking reaction can be promoted even at a low temperature of 40°C.

From the above, the use of polycarbodiimide or zinc oxide alone requires a temperature of at least 80°C to promote the cross-linking reaction. can be promoted. In other words, it is considered that the addition of polycarbodiimide and zinc oxide facilitated the progress of the cross-linking reaction and reduced cracks.

As described above, the glove of the present invention can reduce cracks in the covering layer containing nitrile-butadiene rubber as a main component. Therefore, the glove of the present invention has an excellent appearance, the coating layer is less susceptible to cracking, and excellent durability, oil resistance, and chemical resistance.

1 glove body 2 coating layer

Claims (7)

By forming a coating layer on the outer surface of the glove body by dipping, the fiber glove body covering the wearer's hand and at least a part of the outer surface of the palm area of the glove body are covered, and nitrile-butadiene rubber is mainly used. A method of manufacturing a glove comprising a coating layer comprising:
A first immersion step of immersing the glove body in a coagulant solution, a second immersion step of immersing the glove body after the first immersion step in a latex raw material, and a step of drying the glove body after the second immersion step. and
The glove body is knitted by a glove knitting machine with a gauge number of 10 or more and 26 or less,
The coagulant solution contains 5% by mass or less of a polyvalent metal salt,
The nitrile-butadiene rubber is obtained by copolymerizing only acrylonitrile, butadiene and a monomer having a polar group as a monomer, and the monomer having a polar group is an ethylenically unsaturated monocarboxylic acid monomer, styrene At least one selected from the group consisting of sulfonic acid, maleic anhydride and citraconic anhydride,
The coating layer is impregnated into the glove body and does not penetrate to the inner surface of the glove body,
The coating layer comprises a crosslinked product of nitrile-butadiene rubber and polycarbodiimide and zinc oxide,
The mass ratio of the polycarbodiimide to the nitrile-butadiene rubber is 0.002 or more ,
A method for producing gloves, wherein the zinc oxide content is 0.3 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the nitrile-butadiene rubber . 2. The method for producing gloves according to claim 1, wherein the mass ratio of said polycarbodiimide to said nitrile-butadiene rubber is 0.09 or less. 3. The method for manufacturing gloves according to claim 2, wherein the mass ratio of said polycarbodiimide to said nitrile-butadiene rubber is 0.004 or more. 4. The method for manufacturing a glove according to claim 1, claim 2, or claim 3, wherein the zinc oxide content is 1 part by mass or more and 3.5 parts by mass or less with respect to 100 parts by mass of the nitrile-butadiene rubber. 5. The method for producing gloves according to any one of claims 1 to 4, wherein the crosslinked product of nitrile-butadiene rubber and polycarbodiimide has a carboxyl group, a carbodiimide group, and a group formed by reaction between the carboxyl group and the carbodiimide group. . 6. The method for manufacturing gloves according to claim 5, wherein the molar ratio of the sum of the carbodiimide groups and the reaction product groups to the sum of the carboxyl groups and the reaction product groups is 0.008 or more and 1 or less. The drying step includes a step of holding the glove body after the second immersion step at 20° C. or higher and 40° C. or lower for 20 seconds or longer and 200 seconds or shorter, and then drying the glove body at 50° C. or higher and 100° C. or lower. 7. The method for manufacturing the glove according to any one of 6.

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