Gloves and their manufacturing method

Abstract

The present invention relates to a dip-molded article, and more specifically, provides a dip-molded article comprising an outer molded layer having a repeating unit content derived from an ethylenically unsaturated nitrile monomer of 35% by weight to 60% by weight, and an inner molded layer having a repeating unit content derived from an ethylenically unsaturated nitrile monomer of 10% by weight to 28% by weight.

Description

[Technical field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2019-0123605 filed on October 7, 2019, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a dip-molded article, and more particularly to the dip-molded article, a dip-molding latex composition for producing the dip-molded article, and a method for producing the dip-molded article. [Background technology]

[0003] The use of nitrile rubber gloves is rapidly spreading in various industrial fields including medical, food, chemical, electronics, and industrial fields, as well as in daily life. Glove manufacturers are making efforts to develop a wide variety of quality gloves for various purposes in response to changes in customers and the market.

[0004] Natural rubber gloves have excellent wearing comfort due to their low modulus and high elasticity. Based on these advantages, natural rubber gloves have been used for a long time in medical and surgical applications, but they have the disadvantage of very low resistance to oils and other chemicals. In addition, proteins contained in natural rubber can cause certain allergies and skin rashes, limiting the scope of their use.

[0005] Nitrile rubber gloves have the advantage of being resistant to chemicals and oils and protecting the skin in various working environments. However, the high modulus of nitrile rubber gloves makes them feel stiff when worn, and hands tend to feel tired when worn for long periods of time. In addition, the low elasticity of the gloves makes them difficult to fit tightly to the hands, making them unsuitable for delicate work.

[0006] Thus, rubber gloves are required to have excellent wearing comfort and chemical resistance, but it is extremely difficult to develop and manufacture gloves that simultaneously satisfy both of these physical properties. Summary of the Invention [Problem to be solved by the invention]

[0007] The problem to be solved by the present invention is to simultaneously improve the wearing comfort and chemical resistance of a dip-molded article in order to solve the problems mentioned in the background of the invention above.

[0008] That is, the present invention aims to provide a dip-molded product having improved wearing comfort and chemical resistance at the same time by forming a plurality of layers using dip-molding latex compositions each having a different content of an ethylenically unsaturated nitrile monomer when manufacturing the dip-molded product, and a manufacturing method thereof. [Means for solving the problem]

[0009] According to one embodiment of the present invention for solving the above problems, the present invention provides a dip-molded product including an outer molded layer having a repeating unit content derived from an ethylenically unsaturated nitrile monomer of 35% by weight to 60% by weight, and an inner molded layer having a repeating unit content derived from an ethylenically unsaturated nitrile monomer of 10% by weight to 28% by weight.

[0010] The present invention also provides a method for producing a latex mold comprising the steps of: attaching a coagulant to a dip molding mold (S10); immersing the dip molding mold to which the coagulant has been attached in a first dip molding latex composition to form a layer derived from the first dip molding latex composition (S20); immersing the dip molding mold on which the layer derived from the first dip molding latex composition has been formed in a second dip molding latex composition to form a layer derived from the second dip molding latex composition (S30); and heating the layer derived from the first molding latex composition and the layer derived from the second dip molding latex composition, and a step (S40) of crosslinking the first dip molding latex composition and the second dip molding latex composition, wherein the first dip molding latex composition contains a carboxylic acid-modified nitrile-based copolymer latex having a content of repeating units derived from an ethylenically unsaturated nitrile-based monomer of 35% by weight to 60% by weight, and the second dip molding latex composition contains a carboxylic acid-modified nitrile-based copolymer latex having a content of repeating units derived from an ethylenically unsaturated nitrile-based monomer of 10% by weight to 28% by weight. Effect of the Invention

[0011] The dip-molded article according to the present invention includes an outer molded layer having a high content of repeating units derived from ethylenically unsaturated nitrile monomers and an inner molded layer having a low content of repeating units derived from ethylenically unsaturated nitrile monomers, thereby realizing excellent wearing comfort and chemical resistance at the same time. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The terms and words used in the description and claims of the present invention should not be interpreted in a limited manner to their ordinary or dictionary meanings, but should be interpreted in a manner that is consistent with the technical idea of ​​the present invention, based on the principle that the inventors can appropriately define the concepts of terms in order to best describe their invention.

[0013] In the following, the present invention will be described in more detail in order to facilitate understanding of the present invention.

[0014] In the present invention, the term "monomer-derived repeating unit" may refer to a component, structure, or substance itself derived from a monomer, and may mean a repeating unit formed in a polymer when an input monomer participates in the polymerization reaction during polymerization of the polymer.

[0015] In the present invention, the term "latex" may mean a polymer or copolymer polymerized by polymerization that exists in a form dispersed in water, and as a specific example, may mean a rubber-like polymer or rubber-like copolymer polymerized by emulsion polymerization that exists in a form dispersed in water in a colloidal state.

[0016] In the present invention, the term "derived layer" may refer to a layer formed from a polymer or copolymer, and as a specific example, may mean a layer formed from a polymer or copolymer that is attached, fixed, and / or polymerized on a dip-molding mold during the production of a dip-molded article.

[0017] According to the present invention, there is provided a dip-molded product, which may include an outer molded layer having a repeating unit content derived from an ethylenically unsaturated nitrile monomer of 35% by weight to 60% by weight, and an inner molded layer having a repeating unit content derived from an ethylenically unsaturated nitrile monomer of 10% by weight to 28% by weight.

[0018] According to one embodiment of the present invention, in the dip molded product, the outer molded layer may refer to a layer that directly contacts the external environment and external substances. The outer molded layer that directly contacts the external environment and external substances is required to have excellent chemical resistance as well as modulus and tensile properties related to wearing comfort. When a dip molded product that does not have such excellent chemical resistance is used to handle an organic solvent for a long period of time, the molded product may become mushy and break. In contrast, the present invention manufactures the outer molded layer to contain 35% to 60% by weight of repeating units derived from ethylenically unsaturated nitrile monomers, i.e., to contain a high content of repeating units derived from ethylenically unsaturated nitrile monomers, thereby simultaneously realizing excellent tensile properties and chemical resistance.

[0019] The ethylenically unsaturated nitrile monomer forming the repeating unit derived from the ethylenically unsaturated nitrile monomer may include one or more selected from the group consisting of acrylonitrile, methacrylonitrile, fumaronitrile, α-chloronitrile, and α-cyanoethylacrylonitrile. Specific examples thereof may include acrylonitrile and methacrylonitrile, and a more specific example thereof may be acrylonitrile.

[0020] According to an embodiment of the present invention, the content of the repeating unit derived from the ethylenically unsaturated nitrile monomer may be 35% to 55% by weight, 35% to 50% by weight, or 35% to 45% by weight based on the total content of the outer molded layer. By including the repeating unit derived from the ethylenically unsaturated nitrile monomer within the above range, the outer molded layer can realize an excellent wearing comfort and improve chemical resistance.

[0021] According to one embodiment of the present invention, the outer molding layer may further include a repeating unit derived from a conjugated diene monomer and a repeating unit derived from an ethylenically unsaturated acid monomer in addition to the repeating unit derived from an ethylenically unsaturated nitrile monomer.

[0022] The conjugated diene monomer forming the repeating unit derived from the conjugated diene monomer may include one or more selected from the group consisting of 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 1,3-pentadiene, and isoprene. A specific example may be 1,3-butadiene or isoprene, and a more specific example may be 1,3-butadiene.

[0023] The content of the repeating units derived from the conjugated diene monomer may be 30% by weight to 65% by weight, 35% by weight to 65% by weight, or 40% by weight to 60% by weight based on the total content of the outer molding layer. Within this range, the dip-molded product has the effects of being flexible, excellent in touch and wearing comfort, as well as excellent in oil resistance and tensile strength.

[0024] According to an embodiment of the present invention, the ethylenically unsaturated acid monomer forming the repeating unit derived from the ethylenically unsaturated acid monomer may be an ethylenically unsaturated monomer containing an acidic group such as a carboxyl group, a sulfonic acid group, or an acid anhydride group, and may be one or more selected from the group consisting of ethylenically unsaturated acid monomers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, and fumaric acid; polycarboxylic acid anhydrides such as maleic anhydride and citraconic anhydride; ethylenically unsaturated sulfonic acid monomers such as styrenesulfonic acid; ethylenically unsaturated polycarboxylic acid partial ester monomers such as monobutyl fumarate, monobutyl maleate, and mono-2-hydroxypropyl maleate, and may be one or more selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, maleic acid, and fumaric acid, and may be methacrylic acid. The ethylenically unsaturated acid monomer may be used in the form of a salt such as an alkali metal salt or an ammonium salt during polymerization.

[0025] The content of the repeating units derived from the ethylenically unsaturated acid monomer may be 0.1 to 10% by weight, 0.5 to 9% by weight, or 2 to 8% by weight, based on the total content of the outer molding layer. Within this range, the dip-molded product is flexible, has excellent wearing comfort, and has excellent polymerization stability and tensile strength.

[0026] According to an embodiment of the present invention, the outer molding layer may further include a repeating unit derived from an ethylenically unsaturated monomer formed from another ethylenically unsaturated monomer copolymerizable with the ethylenically unsaturated nitrile monomer and the ethylenically unsaturated acid monomer.

[0027] The ethylenically unsaturated monomer forming the repeating unit derived from the ethylenically unsaturated monomer is a vinyl aromatic monomer selected from the group consisting of styrene, arylstyrene, and vinylnaphthalene; a fluoroalkyl vinyl ether such as fluoroethyl vinyl ether; an ethylenically unsaturated amide monomer selected from the group consisting of (meth)acrylamide, N-methylol (meth)acrylamide, N,N-dimethylol (meth)acrylamide, N-methoxymethyl (meth)acrylamide, and N-propoxymethyl (meth)acrylamide; a non-conjugated diene monomer such as vinylpyridine, vinylnorbornene, dicyclopentadiene, and 1,4-hexadiene; a methyl (meth)acrylate, an ethyl (meth)acrylate, a butyl (meth)acrylate, a 2-ethyl (meth)acrylate, or a 2-ethyl (meth)acrylate. and the like. The monomer may be one or more selected from the group consisting of ethylenically unsaturated carboxylic acid ester monomers ...

[0028] The content of the repeating units derived from the ethylenically unsaturated monomer may be within 20% by weight, 0.01% to 20% by weight, or 0.01% to 15% by weight, based on the total content of the outer molding layer. Within this range, the dip-molded article has excellent feel and wearing comfort as well as excellent tensile strength.

[0029] According to one embodiment of the present invention, in the dip-molded product, the inner molded layer may refer to a layer that comes into contact with a part of the body of a user wearing the dip-molded product. Thus, the inner molded layer that comes into contact with a part of the user's body is required to have an excellent wearing comfort. In contrast, the present invention manufactures the inner molded layer so as to contain 10% to 28% by weight of repeating units derived from ethylenically unsaturated nitrile monomers, i.e., a low content of repeating units derived from ethylenically unsaturated nitrile monomers, and to increase the content of repeating units derived from conjugated diene monomers that improve wearing comfort, thereby providing the dip-molded product with flexibility, excellent touch and wearing comfort, as well as excellent oil resistance and tensile strength.

[0030] The specific description of the ethylenically unsaturated nitrile-based monomer forming the repeating unit derived from the ethylenically unsaturated nitrile-based monomer contained in the inner molded layer is the same as the description of the ethylenically unsaturated nitrile-based monomer forming the repeating unit derived from the ethylenically unsaturated nitrile-based monomer contained in the outer molded layer. In this case, the ethylenically unsaturated nitrile-based monomer forming the repeating unit derived from the ethylenically unsaturated nitrile-based monomer of the outer molded layer and the inner molded layer may be the same or different. As a specific example, the ethylenically unsaturated nitrile-based monomer contained in the inner molded layer may be acrylonitrile.

[0031] According to an embodiment of the present invention, the content of the repeating unit derived from the ethylenically unsaturated nitrile monomer may be 13% to 28% by weight, 15% to 28% by weight, or 20% to 28% by weight based on the total content of the inner molded layer. By including the repeating unit derived from the ethylenically unsaturated nitrile monomer within the above range, the inner molded layer can realize an excellent wearing comfort and maintain chemical resistance.

[0032] According to one embodiment of the present invention, the inner molding layer may further include a repeating unit derived from a conjugated diene monomer and a repeating unit derived from an ethylenically unsaturated acid monomer in addition to the repeating unit derived from an ethylenically unsaturated nitrile monomer.

[0033] The specific description of the conjugated diene monomer forming the repeating unit derived from the conjugated diene monomer contained in the inner molded layer is the same as the description of the conjugated diene monomer forming the repeating unit derived from the conjugated diene monomer contained in the outer molded layer. In this case, the conjugated diene monomers forming the repeating units derived from the conjugated diene monomers of the outer molded layer and the inner molded layer may be the same or different. As a specific example, the conjugated diene monomer contained in the inner molded layer may be 1,3-butadiene.

[0034] The content of the repeating unit derived from the conjugated diene monomer is based on the total content of the inner molding layer. 62% by weight Within this range, the dip-molded article has the effects of being flexible, having excellent touch and wearing comfort, as well as excellent chemical resistance and tensile strength.

[0035] According to one embodiment of the present invention, the specific description of the ethylenically unsaturated acid monomer forming the repeating unit derived from the ethylenically unsaturated acid monomer contained in the inner molding layer is the same as the description of the ethylenically unsaturated acid monomer forming the repeating unit derived from the ethylenically unsaturated acid monomer contained in the outer molding layer. In this case, the ethylenically unsaturated acid monomers forming the repeating units derived from the ethylenically unsaturated acid monomers of the outer molding layer and the inner molding layer may be the same or different. As a specific example, the ethylenically unsaturated acid monomer contained in the inner molding layer may be methacrylic acid.

[0036] The content of the repeating units derived from the ethylenically unsaturated acid monomer may be 0.1% by weight to 10% by weight, 0.5% by weight to 9% by weight, or 2% by weight to 8% by weight, based on the total content of the inner molding layer. Within this range, the dip-molded product is flexible, has excellent wearing comfort, and has excellent polymerization stability and tensile strength.

[0037] According to an embodiment of the present invention, the inner molding layer may further include a repeating unit derived from an ethylenically unsaturated monomer formed from another ethylenically unsaturated monomer copolymerizable with the ethylenically unsaturated nitrile monomer and the ethylenically unsaturated acid monomer.

[0038] The explanation regarding the ethylenically unsaturated monomer forming the repeating unit derived from the ethylenically unsaturated monomer contained in the inner molding layer is the same as the explanation regarding the ethylenically unsaturated monomer forming the repeating unit derived from the ethylenically unsaturated monomer contained in the outer molding layer described above. In this case, the ethylenically unsaturated monomers forming the repeating units derived from the ethylenically unsaturated monomer of the outer molding layer and the inner molding layer may be the same or different.

[0039] The content of the repeating units derived from the ethylenically unsaturated monomer may be within 20% by weight, 0.01% to 20% by weight, or 0.01% to 15% by weight, relative to the total content of the inner molding layer. Within this range, the dip-molded article has excellent feel and wearing comfort as well as excellent tensile strength.

[0040] According to one embodiment of the present invention, the thickness ratio of the outer molded layer to the inner molded layer may be 1:9 to 9:1. For example, the thickness ratio of the outer molded layer to the inner molded layer may be 1:4 to 4:1, or 1.5:1 to 2.5:1. By adjusting the thicknesses of the outer molded layer and the inner molded layer within the above range, it is possible to simultaneously improve the wearing comfort and chemical resistance of the dip-molded product consisting of the outer molded layer and the inner molded layer.

[0041] According to the present invention, there is also provided a method for producing a dip-molded product, which includes the steps of: attaching a coagulant to a dip-molding mold (S10); immersing the dip-molding mold to which the coagulant has been attached in a first dip-molding latex composition to form a layer derived from the first dip-molding latex composition (S20); immersing the dip-molding mold on which the layer derived from the first dip-molding latex composition has been formed in a second dip-molding latex composition to form a layer derived from the second dip-molding latex composition (S30); and forming a layer derived from the first molding latex composition and the second dip-molding latex composition. and heating the product-derived layer to crosslink the first dip molding latex composition and the second dip molding latex composition (S40). The first dip molding latex composition comprises a carboxylic acid-modified nitrile-based copolymer latex having a repeating unit content of 35% by weight to 60% by weight derived from an ethylenically unsaturated nitrile-based monomer, and the second dip molding latex composition comprises a carboxylic acid-modified nitrile-based copolymer latex having a repeating unit content of 10% by weight to 28% by weight derived from an ethylenically unsaturated nitrile-based monomer.

[0042] A method for producing the molded article for forming the molded article may include a step of immersing the latex composition for dip molding by a direct immersion method, an anode adhesion immersion method, a Teague adhesion immersion method, etc., and as a specific example, the method may be performed by an anode adhesion immersion method, which has an advantage that a dip-molded article having a uniform thickness can be obtained.

[0043] The (S10) step is a step of immersing the dip molding mold in a coagulant solution to adhere the coagulant to the surface of the dip molding mold in order to form a coagulant in the dip molding mold. The coagulant solution is a solution in which a coagulant is dissolved in water, alcohol or a mixture thereof. The content of the coagulant in the coagulant solution may be 5% by weight to 75% by weight, 7% by weight to 60% by weight, or 15% by weight to 55% by weight based on the total content of the coagulant solution.

[0044] The coagulant may be, for example, one or more selected from the group consisting of metal halides such as barium chloride, calcium chloride, magnesium chloride, zinc chloride, and aluminum chloride; nitrates such as barium nitrate, calcium nitrate, and zinc nitrate; acetates such as barium acetate, calcium acetate, and zinc acetate; and sulfates such as calcium sulfate, magnesium sulfate, and aluminum sulfate. A specific example of the coagulant may be calcium chloride or calcium nitrate.

[0045] According to one embodiment of the present invention, the step (S20) may be a step of immersing a dip molding mold having a coagulant attached thereto in the first dip molding latex composition to form an outer molding layer, and then removing the dip molding mold to form a layer derived from the first dip molding latex composition, i.e., the outer molding layer, on the dip molding mold.

[0046] In the step (S20), the first dip molding latex composition may contain a first carboxylic acid modified nitrile copolymer latex containing a repeating unit derived from an ethylenically unsaturated nitrile monomer, a repeating unit derived from a conjugated diene monomer, and a repeating unit derived from an ethylenically unsaturated acid monomer. In this case, the detailed explanation of the repeating unit derived from the ethylenically unsaturated nitrile monomer, the repeating unit derived from the conjugated diene monomer, and the repeating unit derived from the ethylenically unsaturated acid monomer is the same as the explanation of the repeating unit derived from the ethylenically unsaturated nitrile monomer, the repeating unit derived from the conjugated diene monomer, and the repeating unit derived from the ethylenically unsaturated acid monomer contained in the outer molding layer of the dip molding product described above.

[0047] The first carboxylic acid modified nitrile-based copolymer latex may further include a repeating unit derived from an ethylenically unsaturated monomer. In this case, the detailed description of the ethylenically unsaturated monomer forming the repeating unit derived from the ethylenically unsaturated monomer is the same as the description of the ethylenically unsaturated monomer contained in the outer molding layer of the above-mentioned dip molding.

[0048] The first carboxylic acid-modified nitrile-based copolymer latex can be prepared by emulsion polymerization of a monomer mixture constituting the first carboxylic acid-modified nitrile-based copolymer by adding an emulsifier, a polymerization initiator, an activator, a molecular weight regulator, a polymerization terminator, etc. In this case, the type and content of the monomer mixture in the polymerization can be the same as the type and content of the monomer contained in the outer molding layer of the dip molding, and the method of addition can be selected from a method of all-at-once addition, continuous addition, or divided addition.

[0049] In preparing the first carboxylic acid modified nitrile copolymer latex, an emulsifier is added to provide stability to the latex during and after the polymerization reaction, and various anionic emulsifiers and nonionic emulsifiers can be used. For example, anionic emulsifiers include alkylbenzene sulfonates such as sodium alkylbenzene sulfonate, alcohol sulfates, alcohol ether sulfonates, alkylphenol ether sulfonates, alpha olefin sulfonates, paraffin sulfonates, ester sulfoxinates, and phosphate esters, and nonionic emulsifiers include alkylphenol ethoxylates, petiamine ethoxylates, fatty acid ethoxylates, and alkanoamides. Such emulsifiers can be used alone or in combination of two or more. In addition, the emulsifier may be added in an amount of 0.3 to 10 parts by weight, 0.8 to 8 parts by weight, or 1.5 to 6 parts by weight, based on 100 parts by weight of the total content of the monomer mixture. Within this range, there are effects such as excellent polymerization stability, little foam generation, and easy production of molded products.

[0050] In addition, in preparing the first carboxylic acid modified nitrile copolymer latex, a radical initiator can be used as the polymerization initiator. For example, the radical initiator can include inorganic peroxides such as sodium persulfate, potassium persulfate, ammonium persulfate, potassium perphosphate, and hydrogen peroxide; organic peroxides such as t-butyl peroxide, cumene hydroperoxide, p-menthane hydroperoxide, di-t-butyl peroxide, t-butyl cumyl peroxide, acetyl peroxide, isobutyl peroxide, octanoyl peroxide, dibenzoyl peroxide, 3,5,5-trimethylhexanol peroxide, and t-butyl peroxyisobutyrate; and nitrogen compounds such as azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, azobiscyclohexanecarbonitrile, and methyl azobisisobutyrate. The polymerization initiator can be used alone or in combination of two or more kinds. As a specific example, the radical initiator can be an inorganic peroxide, and as a more specific example, the radical initiator can be a persulfate. The polymerization initiator may be added in an amount of 0.01 to 2 parts by weight or 0.02 to 1.5 parts by weight based on 100 parts by weight of the total content of the monomer mixture, and within this range, it is possible to maintain the polymerization rate at an appropriate level.

[0051] In the preparation of the first carboxylic acid-modified nitrile copolymer latex, the activator is sodium formaldehyde. Aldehyde Sulfate The activator may be one or more selected from the group consisting of ferrous sulfate, dextrose, sodium pyrophosphate, and sodium sulfite. The activator may be added in an amount of 0.01 to 2.0 parts by weight, 0.02 to 1.5 parts by weight, or 0.05 to 1.0 parts by weight based on 100 parts by weight of the total content of the monomer mixture, and within this range, the polymerization rate can be maintained at an appropriate level.

[0052] In addition, in preparing the first carboxylic acid modified nitrile copolymer latex, the molecular weight regulator may include, for example, mercaptans such as α-methylstyrene dimer, t-dodecyl mercaptan, n-dodecyl mercaptan, octyl mercaptan, etc.; halogenated hydrocarbons such as carbon tetrachloride, methylene chloride, methylene bromide, etc.; sulfur-containing compounds such as tetraethyl thiuram disulfide, dipentamethylene thiuram disulfide, diisopropyl xanthogen disulfide, etc. Such molecular weight regulators may be used alone or in combination of two or more kinds. As a specific example, the molecular weight regulator may be a mercaptan, and as a more specific example, the molecular weight regulator may be t-dodecyl mercaptan. The molecular weight modifier may be added in an amount of 0.1 to 2 parts by weight, 0.2 to 1.5 parts by weight, or 0.3 to 1 part by weight, based on 100 parts by weight of the total content of the monomer mixture. Within this range, the polymerization stability is excellent, and the physical properties of the molded product are excellent when the molded product is produced after polymerization.

[0053] In addition, according to one embodiment of the present invention, in the method for preparing the first carboxylic acid modified nitrile-based copolymer latex, the polymerization may be carried out using water as a medium, specifically deionized water, and may further include additives such as a chelating agent, a dispersant, a pH regulator, an oxygen scavenger, a particle size regulator, an antiaging agent, and an oxygen scavenger, if necessary, in order to ensure ease of polymerization.

[0054] According to an embodiment of the present invention, the emulsifier, polymerization initiator, molecular weight regulator, additives, etc. may be added to the polymerization reactor all at once or in portions, like the monomer mixture, or may be added continuously at each addition.

[0055] According to one embodiment of the present invention, during polymerization of the first carboxylic acid modified nitrile copolymer latex, auxiliary materials such as a chelating agent, a dispersing agent, a pH regulator, an oxygen scavenger, a particle size regulator, an antiaging agent, and an oxygen scavenger may be added as necessary.

[0056] The emulsion polymerization can be carried out at a polymerization temperature of, for example, 10° C. to 90° C., 20° C. to 80° C., or 25° C. to 75° C. Within this range, there is an effect of excellent latex stability.

[0057] Meanwhile, according to one embodiment of the present invention, the first dip molding latex composition may be prepared by adding at least one additive selected from the group consisting of a vulcanizing agent, an ionic crosslinking agent, a pigment, a filler, a thickener, and a pH adjuster to the first carboxylic acid-modified nitrile copolymer latex. In this case, the vulcanizing agent, the ionic crosslinking agent, the pigment, the filler, the thickener, and the pH adjuster may be any one that is commonly used in preparing a dip molding latex composition, and are not particularly limited.

[0058] The content of the first carboxylic acid-modified nitrile-based copolymer latex in the first dip molding latex composition may be 80% by weight to 99% by weight, 85% by weight to 98% by weight, or 88% by weight to 97% by weight. By forming a layer derived from the first dip molding latex composition using the first dip molding latex composition containing the first carboxylic acid-modified nitrile-based copolymer latex in the above range, the physical properties of the dip molded product can be improved.

[0059] According to one embodiment of the present invention, the solid content (concentration) of the first dip molding latex composition may be 10% by weight to 20% by weight, 12% by weight to 20% by weight, or 15% by weight to 20% by weight. Within this range, there are effects of excellent latex transport efficiency, prevention of latex viscosity increase, and excellent storage stability.

[0060] According to one embodiment of the present invention, the first dip molding latex composition may have a pH of 8 to 12, 9 to 11, or 9.3 to 10.5, and within this range, there is an effect of excellent processability and productivity during the production of a dip molded product. The pH of the dip molding latex composition may be adjusted by adding the above-mentioned pH adjuster. The pH adjuster may be, for example, a potassium hydroxide aqueous solution having a concentration of 1% by weight to 5% by weight, or an ammonia aqueous solution having a concentration of 1% by weight to 5% by weight.

[0061] According to one embodiment of the present invention, the immersion time in step (S20) may be 5 to 20 seconds, 5 to 15 seconds, or 6 to 12 seconds. By controlling the immersion time in step (S20) within the above range, the thickness of the layer derived from the first dip molding latex composition can be adjusted.

[0062] According to an embodiment of the present invention, after the step (S20), a step of evaporating water by performing a heat treatment at a predetermined temperature or higher may be further included.

[0063] According to an embodiment of the present invention, the step (S30) may be a step of immersing the dip molding mold on which the layer derived from the first dip molding latex composition is formed into a second dip molding latex composition and removing it to form a layer derived from the second dip molding latex composition, i.e., the inner molding layer.

[0064] In the step (S30), the second dip molding latex composition may contain a second carboxylic acid modified nitrile copolymer latex containing a repeating unit derived from an ethylenically unsaturated nitrile monomer, a repeating unit derived from a conjugated diene monomer, and a repeating unit derived from an ethylenically unsaturated acid monomer. In this case, the detailed explanation of the repeating unit derived from the ethylenically unsaturated nitrile monomer, the repeating unit derived from the conjugated diene monomer, and the repeating unit derived from the ethylenically unsaturated acid monomer is the same as the explanation of the repeating unit derived from the ethylenically unsaturated nitrile monomer, the repeating unit derived from the conjugated diene monomer, and the repeating unit derived from the ethylenically unsaturated acid monomer contained in the inner molding layer of the dip molding product described above.

[0065] The second carboxylic acid modified nitrile-based copolymer latex may further include a repeating unit derived from an ethylenically unsaturated monomer. In this case, the detailed description of the ethylenically unsaturated monomer forming the repeating unit derived from the ethylenically unsaturated monomer is the same as the description of the ethylenically unsaturated monomer contained in the inner molding layer of the above-mentioned dip molding.

[0066] The second carboxylic acid-modified nitrile-based copolymer latex can be produced by emulsion polymerization of a monomer mixture constituting the first carboxylic acid-modified nitrile-based copolymer by adding an emulsifier, a polymerization initiator, an activator, a molecular weight regulator, a polymerization terminator, etc. In this case, the detailed description of the polymerization conditions and additives in emulsion polymerization of the second carboxylic acid-modified nitrile-based copolymer latex is the same as the description of the polymerization conditions and additives for the first carboxylic acid-modified nitrile-based copolymer latex described above.

[0067] According to one embodiment of the present invention, the second dip molding latex composition may be prepared by adding one or more additives selected from the group consisting of vulcanizing agents, ionic crosslinking agents, pigments, fillers, thickeners, and pH adjusters to the second carboxylic acid-modified nitrile copolymer latex. In this case, the vulcanizing agents, ionic crosslinking agents, pigments, fillers, thickeners, and pH adjusters may be those that are commonly used in preparing dip molding latex compositions, and are not particularly limited.

[0068] The content of the second carboxylic acid-modified nitrile-based copolymer latex in the second dip molding latex composition may be 80% by weight to 99% by weight, 85% by weight to 98% by weight, or 88% by weight to 97% by weight. By forming a layer derived from the second dip molding latex composition using the second dip molding latex composition containing the second carboxylic acid-modified nitrile-based copolymer latex in the above range, the physical properties of the dip molded product can be improved.

[0069] According to one embodiment of the present invention, the solid content (concentration) of the second dip molding latex composition may be 21% by weight to 35% by weight, 21% by weight to 32% by weight, or 21% by weight to 30% by weight. Within this range, there are effects of excellent latex transport efficiency, prevention of latex viscosity increase, and excellent storage stability.

[0070] According to one embodiment of the present invention, Second The dip molding latex composition may have a pH of 8 to 12, 9 to 11, or 9.3 to 10.5, and within this range, there is an effect of excellent processability and productivity during the production of dip molded products. The pH of the dip molding latex composition may be adjusted by adding the above-mentioned pH adjuster. As an example, the pH adjuster may be a potassium hydroxide aqueous solution having a concentration of 1% by weight to 5% by weight, or an ammonia aqueous solution having a concentration of 1% by weight to 5% by weight.

[0071] According to one embodiment of the present invention, in the step (S30), the immersion time may be 5 to 20 seconds, 5 to 18 seconds, or 6 to 14 seconds. By controlling the immersion time within the above range in the step (S30), Second The thickness of the layer derived from the dip-molding latex composition can be adjusted.

[0072] According to an embodiment of the present invention, after the step (S30), a step of evaporating water by performing a heat treatment at a predetermined temperature or higher may be further included.

[0073] According to one embodiment of the present invention, the step (S40) may be a step of first evaporating water by heating a layer derived from the first dip molding latex composition and a layer derived from the second dip molding latex composition formed in a dip molding mold, and crosslinking and curing the first dip molding latex composition and the second dip molding latex composition to obtain a dip molded product.

[0074] In this manner, by forming a first layer derived from a latex composition for dip molding and a second layer derived from a latex composition for dip molding, each of which has a different content of repeating units derived from an ethylenically unsaturated nitrile monomer, and producing a dip-molded product by crosslinking, it is possible to simultaneously improve the wearing comfort and chemical resistance.

[0075] According to one embodiment of the present invention, after step (S40), the layer derived from the first dip molding latex composition and the layer derived from the second dip molding latex composition crosslinked by the heat treatment in step (S40) can be removed from the dip molding mold to obtain a dip-molded product.

[0076] According to one embodiment of the present invention, the molded article may be a glove, such as a surgical glove, an examination glove, an industrial glove, or a household glove, a condom, a catheter, or a healthcare product.

[0077] The present invention will be described in more detail below with reference to examples. However, the following examples are merely for the purpose of illustrating the present invention, and it is obvious to those skilled in the art that various changes and modifications are possible within the scope of the scope and technical idea of ​​the present invention, and the scope of the present invention is not limited to these examples.

[0078] Manufacturing Example [Production Example 1] <Production of first carboxylic acid modified nitrile copolymer latex> A 10L high-pressure reactor equipped with a stirrer, a thermometer, a cooler, a nitrogen gas inlet, and a monomer, an emulsifier, and a polymerization initiator were purged with nitrogen, and then 2.4 parts by weight of sodium alkylbenzenesulfonate, 0.6 parts by weight of t-dodecyl mercaptan, and 140 parts by weight of ion-exchanged water were added to 100 parts by weight of a monomer mixture of 39% by weight of acrylonitrile, 57% by weight of 1,3-butadiene, and 4% by weight of methacrylic acid, and the temperature was raised to 40°C.

[0079] After heating, 0.3 parts by weight of potassium persulfate, a polymerization initiator, was added, and when the conversion rate reached 95%, 0.1 parts by weight of sodium dimethyldithiocarbamate was added to terminate the polymerization. Unreacted monomers were removed by a deodorization process, and ammonia water, antioxidants, antifoaming agents, etc. were added to obtain a first-dip carboxylic acid-modified nitrile copolymer latex (Latex-A) with a solid concentration of 45% and a pH of 8.5.

[0080] <Preparation of first dip molding latex composition> 1% by weight of sulfur, 1% by weight of zinc dibutyldithiocarbamate (ZDBC), 1.3% by weight of zinc oxide, 1.0% by weight of titanium oxide, 1.6% by weight of potassium hydroxide solution and secondary distilled water were added to 100% by weight (based on solid content) of the prepared latex-A to obtain latex compositions (composition-A) for first dip molding with pH 10 and solid content concentrations of 18% and 25% by weight.

[0081] [Production Example 2] <Production of second carboxylic acid modified nitrile copolymer latex> A 10L high-pressure reactor equipped with a stirrer, a thermometer, a cooler, a nitrogen gas inlet, and a monomer, an emulsifier, and a polymerization initiator were replaced with nitrogen, and then 100 parts by weight of a monomer mixture of 24% by weight of acrylonitrile, 72% by weight of 1,3-butadiene, and 4% by weight of methacrylic acid were charged with 3 parts by weight of sodium alkylbenzenesulfonate, 0.7 parts by weight of t-dodecyl mercaptan, and 140 parts by weight of ion-exchanged water, and the temperature was raised to 40°C.

[0082] After heating, 0.3 parts by weight of potassium persulfate, a polymerization initiator, was added, and when the conversion rate reached 95%, 0.1 parts by weight of sodium dimethyldithiocarbamate was added to terminate the polymerization. Unreacted monomers were removed by a deodorization process, and ammonia water, antioxidants, antifoaming agents, etc. were added to obtain a second-dip carboxylic acid-modified nitrile copolymer latex (Latex-B) with a solid concentration of 45% and a pH of 8.5.

[0083] <Production of latex composition for second dip molding> 1% by weight of sulfur, 1% by weight of zinc dibutyldithiocarbamate (ZDBC), 1.3% by weight of zinc oxide, 1.0% by weight of titanium oxide, 1.6% by weight of potassium hydroxide solution and secondary distilled water were added to 100% by weight (based on solid content) of the prepared latex-B to obtain latex compositions (composition-B) for second dip molding with pH 10 and solid content concentrations of 18% and 25% by weight.

[0084] [Production Example 3] <Production of third carboxylic acid modified nitrile copolymer latex> A 10L high-pressure reactor equipped with a stirrer, a thermometer, a cooler, a nitrogen gas inlet, and a monomer, an emulsifier, and a polymerization initiator were replaced with nitrogen, and then 100 parts by weight of a monomer mixture of 31% by weight of acrylonitrile, 63% by weight of 1,3-butadiene, and 6% by weight of methacrylic acid, 3 parts by weight of sodium alkylbenzenesulfonate, 0.7 parts by weight of t-dodecyl mercaptan, and 140 parts by weight of ion-exchanged water were added, and the temperature was raised to 40°C.

[0085] After heating, 0.3 parts by weight of potassium persulfate, a polymerization initiator, was added, and when the conversion rate reached 95%, 0.1 parts by weight of sodium dimethyldithiocarbamate was added to terminate the polymerization. Unreacted monomers were removed by a deodorization process, and ammonia water, antioxidants, antifoaming agents, etc. were added to obtain a 3rd dip carboxylic acid modified nitrile copolymer latex (Latex-C) with a solid concentration of 45% and a pH of 8.5.

[0086] <Production of latex composition for second dip molding> 1% by weight of sulfur, 1% by weight of zinc dibutyldithiocarbamate (ZDBC), 1.3% by weight of zinc oxide, 1.0% by weight of titanium oxide, 1.6% by weight of potassium hydroxide solution and secondary distilled water were added to 100% by weight (based on solid content) of the prepared latex-C to obtain latex compositions (composition-C) for second dip molding with pH 10 and solid content concentrations of 18% and 25% by weight.

[0087] [Example] Example 1 <Manufacturing of dip-molded products> A coagulant solution was prepared by mixing 15 parts by weight of calcium nitrate, 84.5 parts by weight of distilled water, and 0.5 parts by weight of a wetting agent (Teric 320 produced by Huntsman Corporation, Australia). A hand-shaped ceramic dip mold was immersed in this solution for 8 seconds, removed, and then dried at 120°C for 2 minutes and 30 seconds to apply the coagulant to the hand-shaped mold (S10).

[0088] Next, the dip-molding mold coated with the coagulant was immersed in the above-prepared composition-A with a solid content concentration of 18% by weight for 8 seconds, pulled out, and dried at 120°C for 30 seconds (S20). Then, it was immersed in the above-prepared composition-B with a solid content concentration of 25% by weight for 12 seconds, pulled out, dried at 80°C for 30 seconds, and then immersed in water or warm water for 30 seconds (S30). Next, it was crosslinked at 120°C for 20 minutes (S40). The crosslinked dip-molded layer was removed from the hand-shaped mold to obtain a glove-shaped dip-molded product.

[0089] [Example 2] A glove-shaped dip-molded product was obtained in the same manner as in Example 1, except that in step (S20), the sample was immersed in composition-A having a solid content of 18% by weight for 10 seconds instead of 8 seconds, and in step (S30), the sample was immersed in composition-B having a solid content of 25% by weight for 8 seconds instead of 12 seconds.

[0090] Comparative Example [Comparative Example 1] A glove-shaped dip-molded product was obtained in the same manner as in Example 1, except that in step (S30), instead of composition-B having a solid content of 25% by weight, composition-A having a solid content of 25% by weight was immersed.

[0091] [Comparative Example 2] A glove-shaped dip-molded product was obtained in the same manner as in Example 1, except that in step (S20), instead of composition-A having a solid content of 18 wt%, composition-B having a solid content of 18 wt% was immersed.

[0092] [Comparative Example 3] A glove-shaped dip-molded product was obtained in the same manner as in Example 2, except that in step (S30), instead of composition-B having a solid content of 25% by weight, composition-A having a solid content of 25% by weight was immersed.

[0093] [Comparative Example 4] A glove-shaped dip-molded product was obtained in the same manner as in Example 2, except that in step (S20), instead of composition-A having a solid content of 18 wt%, composition-B having a solid content of 18 wt% was immersed.

[0094] [Comparative Example 5] A glove-shaped dip-molded product was obtained in the same manner as in Example 1, except that in step (S20), instead of composition-A having a solid content of 18% by weight, composition-B having a solid content of 18% by weight was immersed, and in step (S30), instead of composition-B having a solid content of 25% by weight, composition-A having a solid content of 25% by weight was immersed.

[0095] [Comparative Example 6] A glove-shaped dip-molded product was obtained in the same manner as in Example 2, except that in step (S20), instead of composition-A having a solid content of 18 wt%, composition-B having a solid content of 18 wt% was immersed, and in step (S30), instead of composition-B having a solid content of 25 wt%, composition-A having a solid content of 25 wt% was immersed.

[0096] [Comparative Example 7] A glove-shaped dip-molded product was obtained in the same manner as in Example 1, except that in step (S20), instead of composition-A having a solid content of 18% by weight, composition-C having a solid content of 18% by weight was immersed, and in step (S30), instead of composition-B having a solid content of 25% by weight, composition-C having a solid content of 25% by weight was immersed.

[0097] Experimental Example [Experimental Example 1] For the dip-molded products produced in Examples 1 and 2 and Comparative Examples 1 to 7, the type of composition used in steps (S20) and (S30), the solid content concentration, the thickness of the molding layer, the stress (modulus) at 300% elongation of the dip-molded products, the stress retention rate, the chemical resistance and the durability were measured under the following conditions, and are shown in Table 1 below.

[0098] *Stress at 300% elongation (300% Modulus, MPa): A dumbbell-shaped test piece was prepared according to EN 455-2 from the dip-molded products obtained in each Example and Comparative Example. The test piece was then pulled at an elongation rate of 500 mm / min using a Universal Testing Machine (UTM) to measure the tensile strength and elongation at break, and the feel was measured at the stress when the elongation was 300%. The higher the tensile strength and elongation, the better the quality of the dip-molded product, and the lower the stress value when the elongation is 300%, the better the wearing comfort of the dip-molded product and the better its quality.

[0099] *Stress retention rate (%): For the dip-molded products obtained in each Example and Comparative Example, dumbbell-shaped test pieces were prepared according to EN 455-2, and both ends of the test piece were stretched 100% from the standard section of 20 mm to 40 mm at a speed of 500 mm / min, at which point the stretching was stopped, and the stress M100(0) at this time was measured, and the stress M100(5) was measured after 5 minutes had passed. The value of M100(5) relative to M100(0) was calculated as a percentage, and this value was defined as the stress retention rate. In this case, it is determined that the larger the value, the better the wearing comfort.

[0100] *Chemical resistance (min): Test pieces were prepared from the dip-molded products obtained in each Example and Comparative Example in accordance with EN374-3:2003. Then, isopropyl alcohol was passed through the test pieces using GC-FID, and the isopropyl alcohol penetrated the test pieces at a concentration of 1 μg / cm 2 The time required for permeation at a rate of 100 / min was measured in minutes (min). A longer time indicates better chemical resistance.

[0101] *Durability (times): After preparing a solution for measuring the durability of dip-molded products at 25°C, which is composed of 16 parts by weight of sodium chloride, 16 parts by weight of lactic acid, 3.2 parts by weight of urea, and 64.8 parts by weight of water, the dip-molded product test pieces obtained in each Example and Comparative Example were clamped in a durability measuring device, and the number of times that the test pieces were stretched to twice their original length (maximum 2.6 times when stretched, minimum 1 time when contracted) until they broke was measured. At this time, a high number of times is judged to be excellent in durability.

[0102] [Table 1]

[0103] Referring to Table 1, in the case of Examples 1 and 2 prepared by sequentially immersing Composition-A having a high content of repeating units derived from an ethylenically unsaturated nitrile monomer and Composition-B having a low content, the 300% modulus and stress retention rate were superior to those of Comparative Examples 1 and 3 prepared by immersing only Composition-A having a high content of an ethylenically unsaturated nitrile monomer, and it was confirmed that the fibers exhibited excellent wearing comfort.

[0104] In addition, in the case of Comparative Example 2 and Comparative Example 4, which were prepared by immersing only Composition-B having a low content of ethylenically unsaturated nitrile monomer, it was confirmed that the chemical resistance was decreased compared to Examples 1 and 2.

[0105] In addition, in the case of Comparative Examples 5 and 6, which were prepared by successively immersing in Composition-B having a low content of repeating units derived from ethylenically unsaturated nitrile monomers and Composition-A having a high content, it was confirmed that the chemical resistance was significantly reduced compared to Examples 1 and 2. This was because the outer molding layer, which accounts for about 2 / 3 of the total thickness of the molded product, was prepared from Composition-B having a low content of repeating units derived from ethylenically unsaturated nitrile monomers.

[0106] In addition, in the case of Comparative Example 7, which was prepared by immersing only Composition-C, the content of repeating units derived from ethylenically unsaturated nitrile monomers being between Composition-A and Composition-B, it was confirmed that the 300% modulus, stress retention rate, and chemical resistance were generally decreased compared to Examples 1 and 2.

Claims

1. an outer molding layer having a repeating unit content of 39% by weight to 60% by weight derived from an ethylenically unsaturated nitrile monomer, a repeating unit content of 30% by weight to 60% by weight derived from a conjugated diene monomer, and a repeating unit content of 0.1% by weight to 10% by weight derived from an ethylenically unsaturated acid monomer; and an inner molded layer having a content of repeating units derived from an ethylenically unsaturated nitrile monomer of 10% by weight to 28% by weight, a content of repeating units derived from a conjugated diene monomer of 62% by weight to 85% by weight, and a content of repeating units derived from an ethylenically unsaturated acid monomer of 0.1% by weight to 10% by weight.

2. 2. The glove of claim 1, wherein the thickness ratio of the outer molded layer to the inner molded layer is from 1:9 to 9:

1.

3. 3. The glove according to claim 1, wherein the thickness ratio of the outer molded layer to the inner molded layer is from 1.5:1 to 2.5:

1.

4. A step (S10) of applying a coagulant to the dip casting mold; (S20) immersing the dip molding mold to which the coagulant has been attached into a first dip molding latex composition to form a layer derived from the first dip molding latex composition; A step (S30) of immersing the dip molding mold on which the layer derived from the first dip molding latex composition has been formed, into a second dip molding latex composition to form a layer derived from the second dip molding latex composition; and (S40) heating the layer derived from the first molding latex composition and the layer derived from the second dip molding latex composition to crosslink the first dip molding latex composition and the second dip molding latex composition, The first dip molding latex composition includes a carboxylic acid-modified nitrile-based copolymer latex having a repeating unit derived from an ethylenically unsaturated nitrile-based monomer of 39% by weight to 60% by weight, a repeating unit derived from a conjugated diene-based monomer of 30% by weight to 60% by weight, and a repeating unit derived from an ethylenically unsaturated acid monomer of 0.1% by weight to 10% by weight, The second dip molding latex composition contains a carboxylic acid modified nitrile copolymer latex having a repeating unit derived from an ethylenically unsaturated nitrile monomer of 10% by weight to 28% by weight, a repeating unit derived from a conjugated diene monomer of 62% by weight to 85% by weight, and a repeating unit derived from an ethylenically unsaturated acid monomer of 0.1% by weight to 10% by weight.

5. The method for manufacturing a glove according to claim 4, wherein in the steps (S20) and (S30), the immersion time is 5 seconds to 20 seconds.

6. The solid content concentration of the first dip molding latex composition is 10% by weight to 20% by weight, The method for manufacturing a glove according to claim 4 or 5, wherein the second dip molding latex composition has a solid content of 21% by weight to 35% by weight.

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