KR102168347B1 - Latex composition for dip-forming and the product prepared thereby - Google Patents

Abstract

The present invention relates to a latex composition for dip molding and a molded article prepared therefrom, and more specifically, the composition does not use sulfur and a vulcanization accelerator, but a zinc peroxide-based crosslinking agent as the crosslinking proceeds, resulting in tensile strength, elongation, and stress. And it is possible to manufacture a dip molded article excellent in durability against sweat.

Description

Latex composition for dip molding and molded article manufactured therefrom {LATEX COMPOSITION FOR DIP-FORMING AND THE PRODUCT PREPARED THEREBY}

The present invention relates to a latex composition for dip molding capable of producing a dip-molded product having excellent tensile strength, elongation, stress and durability against sweat, and a molded product produced therefrom.

Rubber gloves used in various fields such as housework, food industry, electronics industry, medical field, etc. have been made by molding natural rubber. However, the use thereof has been limited recently due to allergic problems and unstable supply and demand problems due to natural proteins contained in natural rubber.

Therefore, rubber gloves made by dip molding a latex composition containing sulfur and a vulcanization accelerator in a carboxylic acid-modified nitrile-based copolymer latex such as a synthetic rubber latex that does not cause allergic reactions, such as acrylic acid-acrylonitrile-butadiene copolymer latex, are widely used. Is being used.

Rubber gloves made by mixing these sulfur and vulcanization accelerators have improved durability so that sulfur forms crosslinks between polymer chains so that they are not easily damaged even if the rubber gloves are used for a long time, and the strength of the rubber gloves may be improved.

However, in the case of manufacturing a rubber glove using sulfur and a vulcanization accelerator, a long stirring and aging process of 24 hours or more must be carried out, thereby reducing productivity. In addition, rubber gloves formulated with sulfur and vulcanization accelerators as essential ingredients cause an unpleasant odor due to sulfur or discoloration of the rubber gloves, resulting in an allergic reaction to some users. There is a problem that causes skin abnormalities such as tingling.

Therefore, research is being conducted to manufacture rubber gloves with good durability without causing discomfort, discoloration, allergic reactions, etc. due to the use of sulfur and vulcanization accelerators. water

As an example, when using a latex composition for dip molding containing a conjugated diene rubber latex and an organic peroxide, studies related to the manufacture of rubber gloves that do not require a long stirring aging process and do not cause discoloration have been conducted. However, the organic peroxide solution is very harmful to the human body and fires and explosions may occur when heat or shock is applied, so the safety of the process is very poor.

In Japanese Patent Laid-Open No. 2006-321955, as a method of obtaining a dip molded product without using sulfur and a vulcanization accelerator, a latex composition for dip molding containing conjugated diene rubber latex and organic peroxide is used to eliminate a long stirring and aging process. Although it was possible to make gloves that do not discolor even when used for a long time, there is a disadvantage that the organic peroxide solution is very harmful to the human body and is not safe because of the risk of fire and explosion when heat or shock is applied.

U.S. Patent No. 7,345,111 uses a crosslinkable monomer in acrylic emulsion latex to make a glove that does not have a long stirring and aging process and does not cause allergic reactions due to sulfur and vulcanization accelerators, but there is a disadvantage that acrylic gloves are too sensitive to temperature. .

Moreover, in the case of gloves made without the use of sulfur and vulcanization accelerators, there is a problem in that the gloves are torn in a short time due to sweat and tensile force generated when worn on the hand.

Japanese Laid-Open Patent No. 2006-321955 (2006.11.30), Dip molding latex composition and dip molding product US Patent No. 7,345,111 (2008.03.18), Acrylic polymer emulsion and glove formed from the same

The present inventors conducted various studies to solve the above problems, and as a result of curing latex containing a carboxylic acid-modified nitrile-based copolymer, crosslinking was possible by using a zinc peroxide-based crosslinking agent that does not cause allergies instead of sulfur or a vulcanization accelerator. And, by confirming that the physical properties of the dip-molded product can be improved, the present invention was completed.

Accordingly, an object of the present invention is to provide a latex composition for dip molding comprising a carboxylic acid-modified nitrile-based copolymer latex.

In addition, another object of the present invention is to provide a dip-molded article having excellent tensile strength, elongation, stress, and durability against sweat by being prepared from the latex composition for dip molding.

In order to achieve the above object, the present invention comprises a carboxylic acid-modified nitrile-based copolymer latex in which a conjugated diene-based monomer, an ethylenically unsaturated nitrile-based monomer, and an ethylenically unsaturated acid monomer are copolymerized, and a zinc peroxide-based crosslinking agent. It provides a latex composition for dip molding.

At this time, the dip molding latex composition is characterized in that it contains 1 to 20 parts by weight of a zinc peroxide-based crosslinking agent based on 100 parts by weight of the carboxylic acid-modified nitrile-based copolymer.

The zinc peroxide-based crosslinking agent is characterized in that it is a mixture of zinc peroxide (ZnO ₂ ) and zinc oxide (ZnO).

In addition, the present invention provides a dip molded article, characterized in that produced by dip molding with the latex composition for dip molding.

The latex composition for dip molding according to the present invention can be crosslinked without the use of sulfur and vulcanization accelerators that cause allergies, so it does not require a stirring and aging process for a long time, and has superior physical properties equal to or higher than that of existing products.

Specifically, the dip-molded product made of the dip-molding latex composition has high durability against sweat, has a soft touch and excellent fit, and has excellent mechanical properties such as tensile strength and elongation.

Such a dip-molded product can be easily applied to industries requiring it, such as inspection gloves, condoms, catheters, industrial gloves, household gloves, and health care products.

Hereinafter, the present invention will be described in more detail to aid understanding of the present invention.

The terms or words used in the specification and claims should not be construed as being limited to their usual or dictionary meanings, and the inventor may appropriately define the concept of terms in order to describe his own invention in the best way. It should be interpreted as a meaning and concept consistent with the technical idea of the present invention based on the principle that there is.

Latex composition for dip molding

The present invention proposes a latex composition for dip molding comprising a carboxylic acid-modified nitrile-based copolymer latex, but crosslinking is possible without the use of sulfur and vulcanization accelerators that cause allergies in the related art, so that tensile strength, elongation, stress, and We present a latex composition for dip molding that can increase the durability against sweat.

As a crosslinking agent for crosslinking rubber, sulfur/vulcanization accelerators are mainly used, and various candidate groups such as metal oxides, organic peroxides, and amine compounds exist to replace them, but durability and chemical resistance decrease due to non-use of sulfur. Accordingly, in order to replace the sulfur/vulcanization accelerator, it should be considered first to consider the properties of the composition used for crosslinking or the physical properties of the finally obtained crosslinked molded article. In addition, since the crosslinking agent has different induction time and curing time at a certain temperature and a certain composition, the process time (scorch time, curing time) and the like related thereto must also be considered.

The dip-molded product presented in the present invention is a carboxylic acid-modified nitrile-based copolymer in which a conjugated diene-based monomer, an ethylenically unsaturated nitrile-based monomer, and an ethylenically unsaturated acid monomer are copolymerized. In consideration of the properties of the monomers constituting the copolymer, the state of latex, and the physical properties of the dip molded product, there are various candidate groups of crosslinking agents that can replace sulfur and vulcanization accelerators, but the physical properties of the dip molded product to be obtained in the present invention (sweat Considering durability, tensile strength, elongation, stress, etc.), it is possible to manufacture a dip-molded product having the best physical properties when a zinc peroxide-based crosslinking agent is used.

Zinc peroxide-based crosslinking agent can achieve crosslinking through ionic bonding with carboxylic acid in the carboxylic acid-modified nitrile-based copolymer, and prevents the decrease in durability and chemical resistance caused by the absence of sulfur and vulcanization accelerators. Even when used as a substitute, a sufficient level of crosslinking can be achieved. As a result, it is possible to manufacture a dip-molded product excellent in tensile strength, elongation, stress and durability against sweat.

In addition, in the process, long stirring maturation for 24 hours or more, which is normally performed when using sulfur and a vulcanization accelerator, is unnecessary, so that the overall process time is shortened and productivity is improved. In addition, it is possible to further improve the product value of the dip-molded product by reducing the conventional unpleasant odor and discoloration of the molded product due to sulfur.

The zinc peroxide-based crosslinking agent presented in the present invention may be a mixture of zinc peroxide (ZnO ₂ ) and zinc oxide (ZnO). Although crosslinking by zinc oxide has been previously suggested, it is difficult to manufacture a dip molded article having desired physical properties by using it alone. At this time, the mixing ratio of zinc peroxide and zinc oxide is not particularly limited in the present invention, and any one containing the two may be used. For example, in consideration of crosslinking efficiency, speed, etc., it is preferable to use zinc peroxide in which zinc peroxide is equal to or in excess of 5 to 10% compared to zinc oxide on a commercial basis.

The zinc peroxide-based crosslinking agent is used in an amount of 0.1 to 20.0 parts by weight, preferably 1 to 10 parts by weight, and most preferably 3 to 7 parts by weight, based on 100 parts by weight of the carboxylic acid-modified nitrile-based copolymer latex. If the content of the zinc peroxide-based crosslinking agent is out of the above range, the stability of the latex composition for dip molding decreases, thereby lowering process workability and securing the desired level of physical properties (tensile strength, elongation, stress, durability against sweat, etc.) Can not.

The carboxylic acid-modified nitrile-based copolymer using the zinc peroxide-based crosslinking agent is a copolymer of a conjugated diene-based monomer, an ethylenically unsaturated nitrile-based monomer, and an ethylenically unsaturated acid monomer, and each composition will be described in detail below. .

First, the conjugated diene-based monomer is a monomer constituting the carboxylic acid-modified nitrile-based copolymer according to the present invention, and specific examples thereof include 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, and 2-ethyl -1,3-butadiene, 1,3-pentadiene, and one or more selected from the group consisting of isoprene, of which 1,3-butadiene and isoprene are preferred, and 1,3-butadiene is most preferably used. do.

The conjugated diene-based monomer is 40 to 89% by weight, preferably 45 to 80% by weight, more preferably 50 to 78% by weight, within 100% by weight of the total content of all monomers constituting the carboxylic acid-modified nitrile-based copolymer Included as. If the content is less than the above range, the dip-molded product becomes hard and the fit is deteriorated. On the contrary, if the content exceeds the above range, the oil resistance of the dip-molded product is deteriorated and the tensile strength is lowered.

As another monomer constituting the carboxylic acid-modified nitrile-based copolymer according to the present invention, the ethylenically unsaturated nitrile-based monomer is acrylonitrile, methacrylonitrile, fumaronitrile, α-chloronitrile and α-cyano ethyl acryl. Among them, acrylonitrile and methacrylonitrile are preferable, and among them, acrylonitrile is most preferably used.

The ethylenically unsaturated nitrile-based monomer is 10 to 50% by weight, preferably 15 to 45% by weight, more preferably 20 to 40% by weight within 100% by weight of the total content of the total monomers constituting the carboxylic acid-modified nitrile-based copolymer. Included in %. If the content is less than the above range, the oil resistance of the dip molded article deteriorates and the tensile strength decreases. Conversely, if the content exceeds the above range, the dip molded article becomes stiff and wearability deteriorates.

In addition, as another monomer constituting the carboxylic acid-modified nitrile-based copolymer according to the present invention, the ethylenically unsaturated acid monomer is an ethylenically unsaturated acid monomer containing at least one acidic group selected from the group consisting of a carboxyl group, a sulfonic acid group, and an acid anhydride group. to be. Examples of the ethylenically unsaturated acid monomer include ethylenically unsaturated carboxylic acid monomers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid and fumaric acid; Polycarboxylic anhydrides such as maleic anhydride and citraconic anhydride; Ethylenically unsaturated sulfonic acid monomers such as styrene sulfonic acid; And ethylenically unsaturated polycarboxylic acid partial ester monomers such as monobutyl fumarate, monobutyl maleate, and mono-2-hydroxypropyl maleate. Among these, methacrylic acid is particularly preferred. These ethylenically unsaturated acid monomers may be used in the form of an alkali metal salt or an ammonium salt.

The ethylenically unsaturated acid monomer is 0.1 to 10% by weight, preferably 0.5 to 9% by weight, more preferably 1 to 8, within 100% by weight of the total content of the total monomers constituting the carboxylic acid-modified nitrile-based copolymer. It is included in weight percent. If the content is less than the above range, the tensile strength of the dip-molded article is lowered. Conversely, when the content exceeds the above range, the dip-molded article becomes hard and the fit is deteriorated.

The carboxylic acid-modified nitrile-based copolymer according to the present invention may optionally further include the ethylenically unsaturated nitrile monomer and another ethylenically unsaturated monomer copolymerizable with the ethylenically unsaturated acid monomer.

Examples of copolymerizable ethylenically unsaturated monomers include vinyl aromatic monomers including styrene, alkyl styrene and vinyl naphthalene; Fluoroalkylvinyl ethers including fluoro ethyl vinyl ethers; (Meth)acrylamide, N-methylol (meth)acrylamide, N,N -dimethylol (meth)acrylamide, N-methoxy methyl (meth)acrylamide and N -propoxy methyl (meth)acrylamide Ethylenically unsaturated amide monomer containing; Non-conjugated diene monomers including vinyl pyridine, vinyl norbornene, dicyclopentadiene and 1,4-hexadiene; Methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, ethyl trifluoroethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, dibutyl maleate, di-fumarate Butyl, diethyl maleate, methoxymethyl (meth)acrylate, ethoxyethyl (meth)acrylate, methoxyethoxyethyl (meth)acrylate, cyanomethyl (meth)acrylate, 2-cyanoethyl (meth)acrylate, 1-cyanopropyl (meth)acrylate, 2-ethyl-6-cyanohexyl (meth)acrylate, 3-cyanopropyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, At least one selected from the group consisting of ethylenically unsaturated carboxylic acid ester monomers including glycidyl (meth)acrylate and dimethylamino ethyl (meth)acrylate is used.

The amount of the ethylenically unsaturated nitrile-based monomer and other ethylenically unsaturated monomer copolymerizable therewith may be used within 0.001 to 20% by weight within 100% by weight of the total content of all monomers constituting the carboxylic acid-modified nitrile-based copolymer. If the content exceeds 20% by weight, the balance between the soft fit and tensile strength is not well matched, so it is appropriately used within the above range.

As already mentioned, the carboxylic acid-modified nitrile-based copolymer latex of the present invention can be prepared by emulsion polymerization by adding an emulsifier, a polymerization initiator, and a molecular weight modifier to the monomer constituting the carboxylic acid-modified nitrile-based copolymer.

Specifically, the carboxylic acid-modified nitrile-based copolymer latex

(Step a) adding a conjugated diene-based monomer, an ethylenically unsaturated nitrile-based monomer and an ethylenically unsaturated acid monomer, an emulsifier, a polymerization initiator, and deionized water to the polymerization reactor;

(Step b) performing emulsion polymerization,

(Step c) It is produced through the step of stopping polymerization.

In step a, the conjugated diene-based monomer, the ethylenically unsaturated nitrile-based monomer, the ethylenically unsaturated acid monomer, the emulsifier, and the polymerization initiator may be introduced into the polymerization reactor at once or may be continuously introduced. In addition, they may add all of each used content to the polymerization reactor at once, or add a part of the content to the polymerization reactor and then continuously supply the remaining content to the polymerization reactor again.

Although it does not specifically limit as an emulsifier, For example, anionic surfactant, nonionic surfactant, cationic surfactant, amphoteric surfactant, etc. can be used. Among them, an anionic surfactant selected from the group consisting of alkylbenzene sulfonates, aliphatic sulfonates, higher alcohol sulfates, α-olefin sulfonates and alkyl ether sulfates may be particularly preferably used.

At this time, the amount of the emulsifier used is 0.3 to 10 parts by weight, preferably 0.8 to 8 parts by weight, more preferably 1.5 to 6 parts by weight, based on 100 parts by weight of the monomer constituting the carboxylic acid-modified nitrile-based copolymer. If the content is less than the above range, stability during polymerization is deteriorated. Conversely, if the content exceeds the above range, foaming increases, making it difficult to manufacture a dip molded article.

The polymerization initiator is not particularly limited, but a radical initiator may be specifically used. Examples of the radical initiator include inorganic peroxides such as sodium persulfate, potassium persulfate, ammonium persulfate, potassium perphosphate, and hydrogen peroxide; t-butyl peroxide, cumene hydroperoxide, p-mentane hydroperoxide, di-t-butyl peroxide, t-butylcumyl peroxide, acetyl peroxide, isobutyl peroxide, octanoyl peroxide, dibenzoyl peroxide Organic peroxides such as oxide, 3,5,5-trimethylhexanol peroxide, and t-butyl peroxy isobutylate; Azobis isobutyronitrile, azobis-2,4-dimethylvaleronitrile, azobiscyclohexane carbonitrile, and azobis isobutyric acid (butyric acid) methyl. Among these radical initiators, inorganic Peroxide is more preferable, and among them, persulfate may be particularly preferably used.

The amount of the polymerization initiator is included in an amount of 0.01 to 2 parts by weight, preferably 0.02 to 1.5 parts by weight, based on 100 parts by weight of all monomers constituting the carboxylic acid-modified nitrile-based copolymer. If the content is less than the above range, the polymerization rate is lowered and it is difficult to manufacture a final product. On the contrary, if the content exceeds the above range, the polymerization rate becomes too fast and polymerization cannot be controlled.

The activator is not particularly limited and may be used commonly known in the art, for example, sodium formaldehyde sulfoxylate, sodium ethylenediamine tetraacetate, ferrous sulfate, dextrose, sodium pyrrolate, and sodium sulfite. One or more selected from the group may be used.

Although it does not specifically limit as a molecular weight modifier, For example, Mercaptans, such as α-methylstyrene dimer, t-dodecyl mercaptan, n-dodecyl mercaptan, and octyl mercaptan; Halogenated hydrocarbons such as carbon tetrachloride, methylene chloride and methylene bromide; Sulfur-containing compounds, such as tetraethyl thiuram disulfide, dipentamethylene thiuram disulfide, and diisopropylxanthogen disulfide, etc. are mentioned. These molecular weight modifiers may be used alone or in combination of two or more. Among these, mercaptans are preferable, and t-dodecyl mercaptan may be more preferably used.

The amount of the molecular weight modifier to be used varies depending on the type, but is 0.1 to 2.0 parts by weight, preferably 0.2 to 1.5 parts by weight, more preferably, based on 100 parts by weight of all monomers constituting the carboxylic acid-modified nitrile-based copolymer. It is used in an amount of 0.3 to 1.0 parts by weight. If the content is less than the above range, the physical properties of the dip-molded product are markedly deteriorated. Conversely, if the content exceeds the above range, polymerization stability is deteriorated.

In addition, when the latex of the present invention is polymerized, subsidiary materials such as a chelating agent, a dispersing agent, a pH adjusting agent, a deoxygenating agent, a particle size adjusting agent, an anti-aging agent, and an oxygen scavenger may be added as needed.

The method of introducing the monomer mixture constituting the carboxylic acid-modified nitrile-based copolymer is not particularly limited, and a method of putting the monomer mixture into a polymerization reactor at once, a method of continuously introducing a monomer mixture into a polymerization reactor, and a part of the monomer mixture You may use any method of the method of putting into the polymerization reactor and continuously supplying the remaining monomers to the polymerization reactor.

In step b, the polymerization temperature during emulsion polymerization may be usually 10 to 90°C, and preferably 20 to 80°C. More preferably, it may be 25 to 75 ℃, but is not particularly limited.

In step c, the conversion rate at the time of stopping the polymerization reaction may be 85% or more, preferably 88 to 99.9%, more preferably 90 to 99%, and the unreacted monomer is removed after stopping the polymerization reaction. Then, by adjusting the solid content concentration and pH, a carboxylic acid-modified nitrile-based copolymer latex for dip molding can be obtained.

The carboxylic acid-modified nitrile-based copolymer latex has a glass transition temperature of -50 to -15°C. When the glass transition temperature of the latex is less than the above range, the tensile strength is significantly lowered or the fit is deteriorated due to the stickiness of the glove. Conversely, when it is higher than the above range, the dip molded product cracks, which is not preferable. The glass transition temperature can be adjusted by adjusting the content of the conjugated diene monomer, and can be measured by differential scanning calorimetry.

The average particle diameter of the carboxylic acid-modified nitrile-based copolymer latex may be 50 nm to 500 nm. If the average particle diameter of the dip molding latex falls within the above range, the tensile strength of the manufactured dip molded article may be improved. At this time, the average particle diameter of the dip molding latex can be adjusted by adjusting the type or content of the emulsifier, and the average particle diameter can be measured by a laser scattering analyzer (Nicomp).

The carboxylic acid-modified nitrile-based copolymer latex prepared through the above steps is mixed with a zinc peroxide-based crosslinking agent to prepare a latex composition for dip molding.

The zinc peroxide-based crosslinking agent may be added to the latex as it is in a powder state, or prepared in an aqueous dispersion for uniform mixing and then added to the latex.

The aqueous dispersion is prepared by putting a dispersant in water and then adding a zinc peroxide-based crosslinking agent. After making the particles uniform through a ball mill process, etc., the dispersion stability is increased to be prepared before use. At this time, the dispersant is not particularly limited in the present invention, and any known dispersant may be used. For example, alkyl (C8-12) benzenesulfonate, alkyl (C3-6) naphthalene sulfonate, dialkyl (C3-6) naphthalene sulfonate, dialkyl (C8-12) sulfosuccinate, lignin sulfonate, Naphthalene sulfosuccinate formalin condensate, alkyl (C8-12) naphthalene sulfonate formalin condensate, polyoxyethylene alkyl (C8-12) sodium or calcium salt of sulfonate such as phenylsulfonate, alkyl (C8-12) ) Sodium or calcium salts of sulfates such as sulfate, polyoxyethylene alkyl (C8-12) sulfate, polyoxyethylenealkyl (C8-12) phenyl sulfate, sodium salt or calcium of succinate such as polyoxyalkylene succinate Salt, polyoxyethylene alkyl (C8-12) ether, polyoxyethylene alkyl (C8-12) phenyl ether, polyoxyethylene alkyl (C8-12) phenyl polymer, etc. may be used alone or in combination of two or more, Preferably, beta-naphthalin sulfonic acid formalin condensate sodium salt is used.

If necessary, the latex composition for dip molding may include various additives such as anti-aging agents, antioxidants, preservatives, antibacterial agents, wetting agents, thickeners, dispersants, pigments, dyes, fillers, reinforcing materials, and pH adjusters.

The latex composition for dip molding according to the present invention has a solid content concentration of 10 to 43% by weight, preferably 13 to 40% by weight, and more preferably 10 to 33% by weight. If the concentration is too low, the efficiency of transport of the latex composition decreases, and if the concentration is too high, the solid content concentration may cause problems such as storage stability due to an increase in viscosity, and therefore, it is appropriately adjusted within the above range.

The pH of the latex composition for dip molding may be 8.5 to 12, preferably 9 to 11, more preferably 9.3 to 10.5, and if the pH concentration is out of the above range, the stability of the latex composition for dip molding may decrease. have.

At this time, the pH of the latex composition for dip molding can be adjusted by adding a certain amount of a pH adjusting agent when manufacturing the latex for dip molding, and as the pH adjusting agent, mainly 1 to 5% potassium hydroxide aqueous solution or 1 to 5% ammonia water can be used. have.

Dip molding

In addition, the present invention provides a dip molded article manufactured from the latex composition for dip molding.

The dip-molded article according to an embodiment of the present invention is not particularly limited and may be manufactured through a method commonly known in the art, for example, a direct immersion method, an anode adhesion immersion method, a Teague adhesion needle It can be manufactured using a method such as a paper method. Preferably, an anode adhesion immersion method may be used, and when a dip molded article is manufactured using the positive electrode adhesion immersion method, there is an advantage that a dip molded article having a uniform thickness can be manufactured.

As a specific example, the dip molded article

Immersing a hand-shaped dip molding mold in a coagulant solution to attach a coagulant to the surface of the dip molding mold (step a);

Forming a dip molding layer by immersing the dip molding mold attached to the surface of the coagulant in the latex composition for dip molding (step b); And

It can be prepared through the step of crosslinking the latex resin by heating the dip molding layer.

The step a is a step for attaching a coagulant to the surface of the hand-shaped dip molding mold, and although not particularly limited, the dip molding mold may be immersed in a coagulant solution for at least 1 minute and then taken out and dried at 70 to 150°C. .

The coagulant solution is a solution obtained by dissolving a coagulant in water, alcohol, or a mixture thereof, and may generally contain 5 to 50% by weight of a coagulant, and preferably 10 to 40% by weight of a coagulant.

The coagulant is not particularly limited, for example, 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; Sulfates such as calcium sulfate, magnesium sulfate and aluminum sulfate, and the like can be used. Preferably it may be calcium chloride, calcium nitrate or a combination thereof.

The step b is a step for forming a dip molding layer from the latex composition for dip molding according to the present invention on the dip molding die to which the coagulant is attached, and the dip molding mold to which the coagulant is attached to the dip molding latex composition The dip molding layer can be formed by taking out after being immersed in for 1 minute or more.

The step c is a step for obtaining a dip molded article by crosslinking a latex resin on the dip molding layer, and may be performed by heat treatment of the dip molding layer.

The heat treatment is not particularly limited, for example, after a first heat treatment at 70 to 150° C. for 1 minute to 10 minutes, and then a secondary heat treatment at 100 to 180° C. for 5 to 30 minutes may be performed.

During the heat treatment, the water component is first evaporated from the dip molding layer, and curing of the latex resin of the dip molding layer occurs through crosslinking, thereby obtaining a dip molded article.

The dip molded product is not particularly limited and can be applied to various latex industries, but, for example, one selected from the group consisting of inspection gloves, condoms, catheters, industrial gloves, surgical gloves, household gloves, industrial gloves and health care products. It can be applied to the above molded products.

Hereinafter, preferred embodiments are presented to aid the understanding of the present invention, but the following examples are only illustrative of the present invention, and it is obvious to those skilled in the art that various changes and modifications are possible within the scope and spirit of the present invention. It is natural that changes and modifications fall within the scope of the appended claims.

[Example]

Example 1: Dip molding latex composition and dip molding product manufacturing

(Manufacture of carboxylic acid-modified nitrile-based copolymer latex)

In the reaction vessel, 28 parts by weight of acrylonitrile, 66 parts by weight of 1,3-butadiene, 6 parts by weight of methacrylic acid, 0.7 parts by weight of tert-dodecyl mercaptan, 2.3 parts by weight of sodium dodecylbenzenesulfonate, 140 parts by weight of water After the addition, the temperature was raised to 40°C to initiate polymerization.

When the conversion rate reached 65%, the temperature was raised to 60°C to proceed with polymerization. When the conversion rate reached 94%, 0.3 parts by weight of ammonium hydroxide was added to stop the polymerization.

Unreacted monomer was removed through a deodorization process, and ammonia water, antioxidant, and antifoaming agent were added to obtain a carboxylic acid-modified nitrile-based copolymer latex having a solid content of 45.0% and pH 8.0.

(Preparation of zinc peroxide-based crosslinking agent dispersion)

Zinc peroxide-based crosslinking agent by putting 40% by weight of zinc peroxide, 2% by weight of the sodium salt of the formalin condensate of beta-naphthalin sulfonic acid, and 58% by weight of water into a barrel containing glass beads and dispersing for 24 hours by a ball-mill method. A dispersion was prepared.

(Preparation of latex composition for dip molding)

A dispersion of a zinc peroxide-based crosslinking agent was added so that zinc peroxide was 5% by weight to 100% by weight of the carboxylic acid-modified nitrile-based copolymer latex (in terms of solid content). Then, a potassium hydroxide solution, 1.5 parts by weight of titanium oxide, an appropriate amount of a dispersant and secondary distilled water were added to obtain a latex composition for dip molding having a solid content concentration of 20% and a pH of 9.7.

(Deep molded product manufacturing)

A coagulant solution was prepared by mixing 12 parts by weight of calcium nitrate, 79.5 parts by weight of water, 8 parts by weight of calcium carbonate, and 0.5 parts by weight of a wetting agent (Teric 320 produced by Huntsman Corporation, Australia). The hand-shaped ceramic mold was immersed in this solution for 10 seconds, pulled out, and dried at 70° C. for 5 minutes to apply a coagulant to the hand-shaped mold.

Next, the mold to which the coagulant was applied was immersed in the above dip molding composition for 10 seconds, pulled up, dried at 70° C. for 2 minutes, and leached by immersing in water or hot water for 3 minutes. Again, the mold was dried at 70° C. for 3 minutes and then crosslinked at 120° C. for 20 minutes. The crosslinked dip molded layer was peeled off from the hand-shaped mold to obtain a glove-shaped dip molded article.

Example 2: Dip molding latex composition and dip molding

A latex composition for dip molding was prepared in the same manner as in Example 1, except that 3 parts by weight of the zinc peroxide-based crosslinking agent was used, and a dip molded article in the form of a glove was prepared using this.

Example 3: Dip molding latex composition and dip molding

A latex composition for dip molding was prepared in the same manner as in Example 1, except that the zinc peroxide-based crosslinking agent was used in an amount of 7 parts by weight, and a dip molded article in the form of a glove was prepared using this.

Comparative Example 1: Dip molding latex composition and dip molding

In the same manner as in Example 1, except that 1.0 parts by weight of sulfur, 0.5 parts by weight of zinc dibutyldithiocarbamate, and 1.5 parts by weight of zinc oxide were used instead of the zinc peroxide-based crosslinking agent, a dip molding latex composition and , Using this, a glove-shaped dip molded article was manufactured.

Experimental Example 1: Evaluation of physical properties of a dip molded article

The physical properties of the dip-molded products prepared in Examples and Comparative Examples were measured, and the obtained results are shown in Table 2 below.

(1) Tensile strength, elongation and stress at 300%

Each of the above dip molded products was manufactured as a dumbbell-shaped specimen according to ASTM D-412, and a cross head speed was set to 500 using a Universal Testing Machine (UTM) device (model name: 4466, Instron) according to ASTM D638. After pulling at mm/min, the point at which each specimen was cut was measured.

Max load (N) represents the external force applied to the specimen at the time the specimen is cut, and the tensile strength was calculated by Equation 1 below.

In addition, the elongation (%) was calculated by the following equation (2), and the stress (MPa) at 300% was measured for tensile strength when the specimen was elongated to three times the initial length.

[Equation 1]

[Equation 2]

(2) sweat resistance

After preparing a solution for durability measurement of a dip-molded product at 25° C. consisting 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 test piece was then inserted into a durability measuring device with nitrile rubber gloves. The number of times until the break was measured by increasing it to twice the initial length (maximum 2 times when stretching, and at least 1 times when reducing). At this time, the high number of times means excellent durability.

Tensile strength (MPa) Elongation(%) Stress (MPa, at 300%) Durability (times) Example 1 34.3 652 3.6 731 Example 2 32.1 694 3.0 534 Example 3 33.6 598 4.0 826 Comparative Example 1 29.2 623 3.7 692

As shown in Table 2, in Examples 1 to 3, in which a zinc peroxide-based cross-linking agent was added as a cross-linking agent to the carboxylic acid-modified nitrile-based copolymer latex, even without a long stirring and aging process, superior physical properties equal to or higher than Comparative Example 1. It was confirmed that it was possible to manufacture a glove having.

Therefore, the latex composition for dip molding according to the present invention can secure physical properties equal to or higher than that of sulfur crosslinking by using a zinc peroxide crosslinking agent when crosslinking the carboxylic acid-modified nitrile copolymer latex, so it is used as a substitute for existing sulfur crosslinked products. It is possible.

The latex composition for dip molding according to the present invention can be used for manufacturing latex articles such as health care products such as various industrial and household gloves.

Claims (13)

Carboxylic acid-modified nitrile-based copolymer latex in which a conjugated diene-based monomer, an ethylenically unsaturated nitrile-based monomer, and an ethylenically unsaturated acid monomer are copolymerized; And
As a latex composition for dip molding comprising 5 to 20 parts by weight of a zinc peroxide-based crosslinking agent based on 100 parts by weight of the carboxylic acid-modified nitrile-based copolymer latex,
The dip molding latex composition does not contain a polyvalent salt of an organic acid and an organic peroxide curing agent
Examination gloves, condoms, catheters, surgical gloves, household gloves, or latex composition for dip molding for manufacturing industrial gloves. delete delete The method of claim 1,
The carboxylic acid-modified nitrile-based copolymer is based on 100% by weight of the total monomer,
40 to 89% by weight of a conjugated diene monomer, 10 to 50% by weight of an ethylenically unsaturated nitrile monomer, and 0.1 to 10% by weight of an ethylenically unsaturated acid monomer are copolymerized. The method of claim 1,
The conjugated diene monomer is at least one 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. Dip molding latex composition, characterized in that. The method of claim 1,
The ethylenically unsaturated nitrile-based monomer is a latex for dip molding, characterized in that at least one selected from the group consisting of acrylonitrile, methacrylonitrile, fumaronitrile, α-chloronitrile and α-cyano ethyl acrylonitrile Composition. The method of claim 1,
The ethylenically unsaturated acid monomer is composed of acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, maleic anhydride, citraconic anhydride, styrene sulfonic acid, monobutyl fumarate, monobutyl maleate and mono-2-hydroxypropyl maleic acid. Dip molding latex composition, characterized in that at least one selected from the group. The method of claim 1,
The carboxylic acid-modified nitrile-based copolymer is a latex composition for dip molding, characterized in that it is copolymerized by further comprising an ethylenically unsaturated monomer as a comonomer. The method of claim 8,
The ethylenically unsaturated monomers are styrene, alkyl styrene, vinyl naphthalene, fluoroethyl vinyl ether, (meth)acrylamide, N-methylol (meth)acrylamide, N,N-dimethylol (meth)acrylamide, N- Methoxy methyl (meth) acrylamide, N-propoxy methyl (meth) acrylamide, vinyl pyridine, vinyl norbornene, dicyclopentadiene, 1,4-hexadiene, (meth) methyl acrylate, (meth) ethyl acrylate , (Meth)butyl acrylate, (meth)acrylate-2-ethylhexyl, (meth)acrylate trifluoroethyl, (meth)acrylate tetrafluoropropyl, dibutyl maleate, dibutyl fumarate, diethyl maleate, (meth)acrylate meth Toxymethyl, (meth)acrylate ethoxyethyl, (meth)acrylate methoxyethoxyethyl, (meth)acrylate cyanomethyl, (meth)acrylate 2-cyanoethyl, (meth)acrylate 1-cyanopropyl, ( Meth)acrylic acid 2-ethyl-6-cyanohexyl, (meth)acrylic acid 3-cyanopropyl, (meth)acrylate hydroxyethyl, (meth)acrylate hydroxyethyl, (meth)acrylate hydroxypropyl, glycidyl Latex composition for dip molding, characterized in that at least one selected from the group consisting of (meth)acrylate and dimethylamino ethyl (meth)acrylate. The method of claim 1,
The carboxylic acid-modified nitrile-based copolymer latex has a glass transition temperature of -50 to -15°C, and an average particle diameter of 50 to 500 nm. The method of claim 1,
The latex composition for dip molding is a latex composition for dip molding, characterized in that the solid content concentration is 10% by weight to 40% by weight, and the pH is 8 to 12. A dip-molded article, characterized in that it is manufactured by dip molding with the latex composition for dip molding of any one of claims 1 and 4 to 11. delete