WO2021071078A1 - Method for preparing carboxylic acid-modified nitrile-based copolymer latex - Google Patents

Abstract

The present invention relates to a method for preparing carboxylic acid-modified nitrile-based copolymer latex, and provides a method for preparing carboxylic acid-modified nitrile-based copolymer latex, the method comprising a step for, in the presence of a crosslinking agent comprising glyoxal, emulsion polymerizing a monomer mixture comprising a conjugated diene-based monomer, an ethylenically unsaturated nitrile-based monomer and an ethylenically unsaturated acid monomer.

Description

Method for producing carboxylic acid-modified nitrile-based copolymer latex

Mutual citation with related applications

This application claims the benefit of priority based on Korean Patent Application No. 10-2019-0123894 filed on October 07, 2019 and Korean Patent Application No. 10-2020-0070902 filed on June 11, 2020, and All contents disclosed in the literature are included as part of this specification.

Technical field

The present invention relates to a method for preparing a carboxylic acid-modified nitrile-based copolymer latex, and more particularly, a method for preparing a carboxylic acid-modified nitrile-based copolymer latex, a copolymer latex prepared thereby, a latex composition for dip molding comprising the same And it relates to a molded article prepared from the latex composition for dip molding.

Disposable rubber gloves, which are widely used in everyday life such as housework, food industry, electronics industry, medical field, etc., are made by dip molding of natural rubber or carboxylic acid-modified nitrile-based copolymer latex. Recently, carboxylic acid-modified nitrile-based gloves are in the spotlight in the disposable gloves market due to allergies and unstable supply and demand problems caused by natural proteins of natural rubber.

On the other hand, there are various attempts to increase glove productivity in accordance with the increasing glove demand. The most commonly used of these attempts is to maintain strength while thinning the glove. In the past, disposable nitrile gloves weighing about 4g were generally used, but now, gloves with a tensile strength of 6N or more are required by making them as thin as 3.2g. In order to make such a thin glove, a glove molded article is manufactured with a low concentration of a coagulant and a latex composition. In this case, workability such as syneresis is deteriorated.

Another attempt to increase glove productivity is to increase the line speed, and even in this case, high workability is required.

Latex having such high strength and excellent workability at the same time is required, but in reality, the strength and workability of gloves are in a trade-off relationship. It is the film formation speed of latex that determines the strength and workability of the gloves. If the film formation speed is fast, it has high strength, but the workability is poor, and if the film formation speed is slow, the workability is excellent, but low strength gloves are made. . Accordingly, it is required to develop a carboxylic acid-modified nitrile-based copolymer latex that can secure high tensile strength even if it is made thin in a high-speed production line and has excellent workability.

In order to solve the problems mentioned in the technology behind the background of the present invention, the present invention is capable of producing a molded article having high tensile strength and elongation even at a thin thickness, and a latex composition for dip molding excellent in workability, modified with carboxylic acid. It is to provide a nitrile-based copolymer latex.

That is, in the present invention, when preparing a carboxylic acid-modified nitrile-based copolymer latex, it is emulsion-polymerized in the presence of a crosslinking agent containing glyoxal to form a uniform cross-linking site in the copolymer, thereby obtaining a carboxylic acid-modified nitrile-based copolymer with improved crosslinking density. I wanted to.

In the present invention, in the presence of a crosslinking agent containing glyoxal and a specific polymerization initiator and an initiator when preparing a carboxylic acid-modified nitrile-based copolymer latex, a water-soluble monomer and an ethylenically unsaturated acid monomer are partially polymerized in water at the beginning of polymerization. By preparing a water-soluble oligomer, a carboxylic acid-modified nitrile-based copolymer latex having a carboxylic acid pKa in a specific range was prepared, and the prepared latex composition for dip molding comprising the carboxylic acid-modified nitrile-based copolymer latex has excellent workability. And, the molded article manufactured from the dip molding latex composition has achieved excellent tensile strength.

In order to solve the above problems, the present invention comprises the step of emulsion polymerization of a monomer mixture containing a conjugated diene monomer, an ethylenically unsaturated nitrile monomer, and an ethylenically unsaturated acid monomer in the presence of a crosslinking agent containing glyoxal. It provides a method for producing a carboxylic acid-modified nitrile-based copolymer latex.

In addition, the present invention includes a carboxylic acid-modified nitrile-based copolymer latex copolymer comprising a repeating unit derived from a conjugated diene-based monomer, a repeating unit derived from an ethylenically unsaturated nitrile-based monomer, a repeating unit derived from an ethylenically unsaturated acid monomer, and a glyoxal-derived moiety. It provides a carboxylic acid-modified nitrile-based copolymer latex.

In addition, the present invention is a carboxylic acid-modified nitrile-based copolymer comprising a repeating unit derived from a conjugated diene-based monomer, a repeating unit derived from an ethylenically unsaturated nitrile-based monomer, a repeating unit derived from an ethylenically unsaturated acid monomer, a repeating unit derived from a water-soluble monomer, and a glyoxal-derived moiety. A carboxylic acid-modified nitrile-based copolymer latex containing a coalescence and having a pKa of 8.5 to 9.5 is provided.

In addition, the present invention provides a latex composition for dip molding comprising the carboxylic acid-modified nitrile-based copolymer latex according to the present invention.

In addition, the present invention provides a dip molded article comprising a layer derived from the latex composition for dip molding according to the present invention.

In the present invention, when preparing a carboxylic acid-modified nitrile-based copolymer latex, it is subjected to emulsion polymerization in the presence of a crosslinking agent containing glyoxal to form a uniform crosslinking site in the polymer, thereby obtaining a carboxylic acid-modified nitrile-based copolymer having improved crosslinking density. .

In addition, in the present invention, in the presence of a crosslinking agent containing glyoxal and a specific polymerization initiator and an initiator when preparing a carboxylic acid-modified nitrile-based copolymer latex, a water-soluble monomer and an ethylenically unsaturated monomer are partially polymerized in water to be water-soluble at the beginning of polymerization. By preparing an oligomer, a carboxylic acid-modified nitrile-based copolymer latex having a low pKa of carboxylic acid was prepared, and the dip molding latex composition comprising the prepared carboxylic acid-modified nitrile-based copolymer latex is excellent in workability, and the dip Molded articles made from the latex composition for molding can implement excellent tensile strength.

1 is a graph showing a change in pH according to the amount of KOH input in Example 1 of the present invention.

FIG. 2 is a differential curve of the input amount of KOH according to the pH shown in FIG. 1.

The terms or words used in the description and claims of the present invention should not be construed as being limited to a conventional or dictionary meaning, and the inventors appropriately explain the concept of terms in order to explain their own invention in the best way. Based on the principle that it can be defined, it should be interpreted as a meaning and concept consistent with the technical idea of the present invention.

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

In the present invention, the terms'derived repeating unit' and'derived part' may refer to a component, structure, or the substance itself originated from a substance, and as a specific example, the'derived repeating unit' is a monomer that is introduced during polymerization of a polymer. It may mean a repeating unit formed in the polymer by participating in the polymerization reaction, and the'derived part' may refer to a chain transfer agent introduced during polymerization of the polymer to participate in the polymerization reaction to induce a chain transfer reaction of the polymer.

In the present invention, the term'latex' may mean that a polymer or copolymer polymerized by polymerization is dispersed in water, and as a specific example, fine particles of a rubber polymer or rubber copolymer polymerized by emulsion polymerization It may mean that is present in a colloidal state and dispersed in water.

In the present invention, the term'derived layer' may refer to a layer formed from a polymer or a copolymer, and as a specific example, when manufacturing a dip molded article, the polymer or copolymer is attached, fixed, and/or polymerized on a dip mold to form a polymer or It may mean a layer formed from a copolymer.

According to the present invention, a method for producing a carboxylic acid-modified nitrile-based copolymer latex is provided. The manufacturing method of the carboxylic acid-modified nitrile-based copolymer latex is the step of emulsion polymerization of a monomer mixture containing a conjugated diene-based monomer, an ethylenically unsaturated nitrile-based monomer, and an ethylenically unsaturated acid monomer in the presence of a crosslinking agent containing glyoxal. It may be to include.

According to an embodiment of the present invention, the conjugated diene-based monomer is 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 1,3-pentadiene, and It may include at least one selected from the group consisting of isoprene, and a specific example may be 1,3-butadiene or isoprene, and a more specific example may be 1,3-butadiene.

The content of the conjugated diene-based monomer may be 35% to 75% by weight, 40% to 75% by weight, or 45% to 70% by weight based on the total content of the monomer mixture, and within this range, the dip molded product is flexible. And, while having excellent touch and wearing feeling, there is an effect of excellent oil resistance and tensile strength.

According to an embodiment of the present invention, the ethylenically unsaturated nitrile-based monomer is one selected from the group consisting of acrylonitrile, methacrylonitrile, fumaronitrile, α-chloronitrile and α-cyano ethyl acrylonitrile. The above may be included, and specific examples may be acrylonitrile and methacrylonitrile, and more specific examples may be acrylonitrile.

The content of the ethylenically unsaturated nitrile-based monomer may be 20 wt% to 50 wt%, 25 wt% to 45 wt%, or 25 wt% to 40 wt% based on the total content of the monomer mixture. Within this range, the dip-molded product is flexible, has excellent touch and fit, and has excellent oil resistance and tensile strength.

According to an embodiment of the present invention, the ethylenically unsaturated acid monomer may be an ethylenically unsaturated monomer containing an acidic group such as a carboxyl group, a sulfonic acid group, and an acid anhydride group, and specific examples thereof include acrylic acid, methacrylic acid, itaconic acid, maleic acid, and Ethylenically unsaturated acid monomers such as fumaric acid; Polycarboxylic anhydrides such as maleic anhydride and citraconic anhydride; Ethylenically unsaturated sulfonic acid monomers such as styrene sulfonic acid; It may be one or more selected from the group consisting of ethylenically unsaturated polycarboxylic acid partial ester monomers such as monobutyl fumarate, monobutyl maleate and mono-2-hydroxypropyl maleic acid, and more specific examples of acrylic acid and methacrylic acid , Itaconic acid, maleic acid, and may be one or more selected from the group consisting of fumaric acid, and a more specific example 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.

The content of the ethylenically unsaturated acid monomer may be 2% to 15% by weight, 3% to 9% by weight, or 4% to 7% by weight based on the total content of the monomer mixture, and within this range, the dip The molded article is flexible, has excellent fit, and has excellent polymerization stability and tensile strength.

According to an embodiment of the present invention, the monomer mixture may include a water-soluble monomer. The water-soluble monomer may react with the ethylenically unsaturated acid monomer to form a water-soluble oligomer in the presence of a crosslinking agent including glyoxal and a persulfate polymerization initiator and an initiator to be described later during polymerization of the carboxylic acid-modified nitrile-based copolymer. have.

The water-soluble monomer may include at least one selected from the group consisting of hydroxy ethyl acrylate, hydroxy ethyl methacrylate, hydroxy propyl methacrylate, dimethylaminoethyl acrylate, and diethylaminoethyl methacrylate. have.

The content of the water-soluble monomer may be 0.1% to 10% by weight, 0.1% to 8% by weight, or 0.3% to 5% by weight based on the total content of the monomer mixture. Within this range, there is an effect of improving workability and polymerization stability.

According to an embodiment of the present invention, by emulsion polymerization of a monomer mixture comprising the conjugated diene monomer, an ethylenically unsaturated nitrile monomer, and an ethylenically unsaturated acid monomer, the conjugated diene monomer, the ethylenically unsaturated nitrile monomer, and The ethylenically unsaturated acid monomer is copolymerized, and through this, a carboxylic acid-modified nitrile-based copolymer can be prepared.

According to an embodiment of the present invention, the conjugated diene-based monomer, ethylenically unsaturated nitrile, by emulsion polymerization of a monomer mixture containing the conjugated diene-based monomer, ethylenically unsaturated nitrile-based monomer, ethylenically unsaturated acid monomer, and water-soluble monomer. A system monomer, an ethylenically unsaturated acid monomer, and a water-soluble monomer are copolymerized, and through this, a carboxylic acid-modified nitrile-based copolymer can be prepared.

According to an embodiment of the present invention, the monomer mixture may further include an ethylenically unsaturated monomer formed of the ethylenically unsaturated nitrile-based monomer and another ethylenically unsaturated monomer copolymerizable with the ethylenically unsaturated acid monomer.

The ethylenically unsaturated monomer is a vinyl aromatic monomer selected from the group consisting of styrene, aryl styrene, and vinyl naphthalene; Fluoroalkyl vinyl ethers such as fluoro ethyl vinyl ether; (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 monomers selected from the group consisting of; Non-conjugated diene monomers such as vinyl pyridine, vinyl norbornene, dicyclopentadiene, and 1,4-hexadiene; Methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, trifluoroethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, dibutyl maleate, Dibutyl fumarate, diethyl maleate, methoxymethyl (meth)acrylate, ethoxyethyl (meth)acrylate, methoxyethyl (meth)acrylate, cyanomethyl (meth)acrylate, 2-cyano (meth)acrylate Ethyl, (meth)acrylic acid 1-cyanopropyl, (meth)acrylic acid 2-ethyl-6-cyanohexyl, (meth)acrylic acid 3-cyanopropyl, (meth)acrylic acid hydroxyethyl, (meth)acrylic acid hydroxy It may be one or more selected from the group consisting of ethylenically unsaturated carboxylic acid ester monomers selected from the group consisting of propyl, glycidyl (meth)acrylate, and dimethylamino ethyl (meth)acrylate.

The content of the ethylenically unsaturated monomer may be within 20% by weight, 0.01% by weight to 20% by weight, or 0.01% by weight to 15% by weight based on the total content of the monomer mixture, and within this range, the touch of the dip-molded product And excellent wearability, and excellent tensile strength.

According to an embodiment of the present invention, the step of emulsion polymerization of a monomer mixture including the conjugated diene monomer, an ethylenically unsaturated nitrile monomer, and an ethylenically unsaturated acid monomer is performed in the presence of a crosslinking agent containing glyoxal, By forming a uniform crosslinking site in the carboxylic acid-modified nitrile-based copolymer, it is possible to improve the crosslinking density of the copolymer.

In the case of rubber polymers, when the crosslinking density is increased, the tensile strength increases, but when the crosslinking density is too high, there is a disadvantage of lowering the elongation. As described above, when emulsion polymerization is carried out in the presence of a crosslinking agent containing glyoxal, by appropriately controlling the crosslinking density, the crosslinking density in the copolymer is improved, so that the tensile strength of the molded article made from the copolymer is improved and the elongation is also increased. It has an excellent effect.

According to an embodiment of the present invention, in the emulsion polymerization step, the content of a crosslinking agent including glyoxal as a crosslinking agent may be added in an amount of 0.1 parts by weight to 1 part by weight based on 100 parts by weight of the total monomer mixture. In the polymerization step, by adding a crosslinking agent containing glyoxal within the above range, the degree of crosslinking between particles of the latex is improved, thereby further improving the strength of the molded article including the latex.

According to an embodiment of the present invention, the step of emulsion polymerization of a monomer mixture including the conjugated diene-based monomer, ethylenically unsaturated nitrile-based monomer, ethylenically unsaturated acid monomer, and water-soluble monomer may include sodium persulfate, potassium persulfate, And a persulfate-based polymerization initiator comprising at least one selected from the group consisting of ammonium persulfate; It may be carried out in the presence of an initiator including at least one selected from the group consisting of hydroperoxide, ferrous sulfate, and sodium metabisulfite, and a crosslinking agent including glyoxal.

In the case of emulsion polymerization in the presence of the persulfate polymerization initiator, sulfate ion radicals are converted into hydroxy radicals in the presence of water. Since the hydroxy radical is hydrophobic compared to the sulfate ion radical, polymerization proceeds in the particles, and in this case, the formation of oligomers of the ethylenic unsaturated acid monomer and the water-soluble monomer is suppressed.

On the other hand, in the present invention, by adding a persulfate initiator together with an initiator including at least one selected from the group consisting of hydroperoxide, ferrous sulfate and sodium metabisulfite, and a crosslinking agent including glyoxal, hydrophilicity The generation of phosphorus sulfate ion radicals can be maximized, and the conversion of sulfate ion radicals into hydroxy radicals can be suppressed to promote the formation of water-soluble oligomers, which are polymers of water-soluble monomers and ethylenically unsaturated acid monomers.

As described above, when the ethylenically unsaturated acid monomer forms an oligomer with a water-soluble monomer at the beginning of polymerization, it is easily ionized in the final carboxylic acid-modified nitrile-based copolymer latex to have a low pKa. Latex having a low pKa has excellent workability and high strength.

According to an embodiment of the present invention, in the polymerization step, the content of the persulfate-based polymerization initiator including at least one selected from the group consisting of sodium persulfate, potassium persulfate, and ammonium persulfate is 100 weight of the total monomer mixture It may be added in an amount of 0.1 parts by weight to 5 parts by weight, 0.1 parts by weight to 3 parts by weight, or 0.1 parts by weight to 2 parts by weight based on parts. Within this range, the polymerization rate can be appropriately adjusted, the polymerization can be controlled, and the productivity of the carboxylic acid-modified nitrile-based copolymer is excellent.

According to an embodiment of the present invention, in the polymerization step, the content of the initiator comprising at least one selected from the group consisting of hydroperoxide, ferrous sulfate, and sodium metabisulfite is a persulfate-based polymerization initiator It may be added in an amount of 1 to 100 parts by weight, 25 parts by weight to 100 parts by weight, or 30 parts by weight to 100 parts by weight based on 100 parts by weight of the total content. Within this range, there is an effect of facilitating the formation of a water-soluble oligomer by further promoting the reaction of the ethylenically unsaturated acid monomer and the water-soluble monomer.

According to an embodiment of the present invention, the carboxylic acid-modified nitrile-based copolymer latex may be prepared by emulsion polymerization by further adding an emulsifier and a molecular weight control agent to a monomer mixture constituting the carboxylic acid-modified nitrile-based copolymer. In this case, in the polymerization, the type and content of the monomer mixture may be introduced in the monomer type and content described above, and the injection method may be selected from batch injection, continuous injection, or divided injection method.

In preparing the carboxylic acid-modified nitrile-based copolymer latex, an emulsifier is added to impart stability to the latex during and after the polymerization reaction, and various types of anionic emulsifiers and nonionic emulsifiers may be used. For example, as anionic emulsifiers, alkyl benzene sulfonates such as sodium alkyl benzene sulfonate, alcohol sulfate, alcohol ether sulfonate, alkyl phenol ether sulfonate, alpha olefin sulfonate, paraffin sulfonate, ester sulfosuccinate, phosphate Esters, and the like, and nonionic emulsifiers may include alkyl phenol ethoxylate, fethiamine ethoxylate, fatty acid ethoxylate, alkanoamide, and the like. These emulsifiers may be used alone or in combination of two or more. In addition, the emulsifier may be added in an amount of 0.3 parts by weight to 10 parts by weight, 0.8 parts by weight to 8 parts by weight, or 1.5 parts by weight to 6 parts by weight based on 100 parts by weight of the total monomer mixture, and polymerization stability within this range It is excellent, and there is an effect that it is easy to manufacture a molded product due to a small amount of foaming.

In addition, in preparing the carboxylic acid-modified nitrile-based copolymer latex, the molecular weight modifier is, for example, a mercap such as α-methylstyrene dimer, t-dodecyl mercaptan, n-dodecyl mercaptan, and octyl mercaptan. Coal flow; Halogenated hydrocarbons such as carbon tetrachloride, methylene chloride, and methylene bromide; And sulfur-containing compounds such as tetraethylthiuram disulfide, dipentamethylthiuram disulfide, and diisopropylxanthogen disulfide. These molecular weight modifiers may be used alone or in combination of two or more. As a specific example, the molecular weight control agent may use mercaptans, and as a more specific example, the molecular weight control agent may use t-dodecyl mercaptan. The molecular weight modifier may be added in an amount of 0.1 parts by weight to 2 parts by weight, 0.2 parts by weight to 1.5 parts by weight, or 0.3 parts by weight to 1 part by weight based on 100 parts by weight of the total content of the monomer mixture, and has excellent polymerization stability within this range. , When manufacturing a molded product after polymerization, it has an excellent effect on the physical properties of the molded product.

In addition, according to an embodiment of the present invention, in preparing the carboxylic acid-modified nitrile-based copolymer latex, polymerization may be carried out in water as a medium, for example, deionized water. Additives 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 further included.

According to an embodiment of the present invention, the emulsifier, polymerization initiator, molecular weight modifier, additive, and the like may be added collectively or dividedly into a polymerization reactor like the monomer mixture, and may be continuously added at each input.

According to an embodiment of the present invention, when the carboxylic acid-modified nitrile-based copolymer latex is polymerized, a chelating agent, a dispersant, a pH adjuster, a deoxidant, a particle size adjuster, an anti-aging agent, an oxygen scavenger, if necessary. Subsidiary materials such as may be added.

According to an embodiment of the present invention, the polymerization temperature during the emulsion polymerization may 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, and within this range. The latex stability has an excellent effect.

According to an embodiment of the present invention, the polymerization reaction may be terminated after the polymerization conversion rate is 90% or more, preferably 93% or more. The polymerization reaction may be terminated by addition of a polymerization inhibitor, a pH adjuster, and an antioxidant. After completion of the reaction, the final obtained copolymer latex is used after removing the unreacted monomer through a conventional deodorization and concentration process.

According to an embodiment of the present invention, the carboxylic acid-modified nitrile-based copolymer latex may have a glass transition temperature of -40°C to -15°C, -40°C to -20°C, or -35°C to -20°C. When the glass transition temperature of the latex satisfies the above range, the tensile strength is excellent, the stickiness of the molded article is prevented, so that the feeling of wearing is excellent, and the durability is excellent by preventing cracks. The glass transition temperature can be adjusted by adjusting the content of the conjugated diene-based monomer, and can be measured by differential scanning calorimetry.

The average particle diameter of the carboxylic acid-modified nitrile-based copolymer may be 80 nm to 300 nm, 80 nm to 280 nm, or 100 nm to 230 nm. By adjusting the average particle diameter of the carboxylic acid-modified nitrile-based copolymer within the above range, it is possible to improve the tensile strength of the manufactured dip-molded product. The average particle diameter of the carboxylic acid-modified nitrile-based copolymer 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).

Further, according to the present invention, there is provided a carboxylic acid-modified nitrile-based copolymer latex prepared according to the production method of the present invention.

According to an embodiment of the present invention, the carboxylic acid-modified nitrile-based copolymer latex is a repeating unit derived from a conjugated diene-based monomer, a repeating unit derived from an ethylenically unsaturated nitrile-based monomer, a repeating unit derived from an ethylenically unsaturated acid monomer, and a glyoxal-derived portion. It may include a carboxylic acid-modified nitrile-based copolymer containing.

As described above, when the glyoxal-derived portion is included, the crosslinking density in the copolymer is improved by appropriately controlling the crosslinking density of the copolymer, so that the tensile strength of the molded article made from the copolymer is improved and the elongation is also excellent. have.

According to an embodiment of the present invention, the carboxylic acid-modified nitrile-based copolymer latex is a repeating unit derived from a conjugated diene-based monomer, a repeating unit derived from an ethylenically unsaturated nitrile-based monomer, a repeating unit derived from an ethylenically unsaturated acid monomer, and a repeating derived from a water-soluble monomer. A carboxylic acid-modified nitrile-based copolymer including a unit and a glyoxal-derived portion may be included, and the carboxylic acid-modified nitrile-based copolymer latex may have a pKa of 8.5 to 9.5.

As described above, since the carboxylic acid-modified nitrile-based copolymer latex according to the present invention has a low pKa, the workability of the latex composition for dip molding including the same is excellent, and the strength of the dip-molded article manufactured therefrom is improved. I can.

In addition, according to the present invention, there is provided a latex composition for dip molding comprising the carboxylic acid-modified nitrile-based copolymer latex according to the present invention. According to an embodiment of the present invention, the dip molding latex composition is at least one selected from the group consisting of a vulcanizing agent, an ionic crosslinking agent, a pigment, a filler, a thickener, and a pH adjusting agent in the above-described carboxylic acid-modified nitrile-based copolymer latex. It can be prepared including additives.

According to an embodiment of the present invention, the vulcanizing agent is for vulcanizing the latex composition for dip molding, and may be sulfur, and as a specific example, sulfur such as powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur and insoluble sulfur, etc. Can be The content of the vulcanizing agent may be 0.1 parts by weight to 10 parts by weight, or 1 part by weight to 5 parts by weight based on 100 parts by weight of the total content of the carboxylic acid-modified nitrile-based copolymer latex in the dip molding latex composition (based on solid content). And there is an effect excellent in crosslinking ability by vulcanization within this range.

In addition, according to an embodiment of the present invention, the vulcanization accelerator is 2-mercaptobenzothiazole (MBT, 2-mercaptobenzothiazole), 2,2-dithiobisbenzothiazole-2-sulfenamide (MBTS, 2,2 -dithiobisbenzothiazole-2-sulfenamide), N-cyclohexylbenzothiazole-2-sulfenamide (CBS, N-cyclohexylbenzothiasole-2-sulfenamide), 2-morpholinothiobenzothiazole (MBS, 2-morpholinothiobenzothiazole), tetra Methylthiuram monosulfide (TMTM), tetramethylthiuram disulfide (TMTD), zinc diethyldithiocarbamate (ZDEC), zinc di-n-butyldithiocarbamate (ZDBC, zinc di-n-butyldithiocarbamate), diphenylguanidine (DPG, diphenylguanidine), and di-o-tolylguanidine (di-o-tolylguanidine) may be one or more selected from the group consisting of. The content of the vulcanization accelerator may be 0.1 parts by weight to 10 parts by weight, or 0.5 parts by weight to 5 parts by weight based on 100 parts by weight of the total content of the carboxylic acid-modified nitrile-based copolymer latex in the dip molding latex composition (based on solid content). In addition, there is an effect excellent in crosslinking ability by vulcanization within this range.

In addition, according to an embodiment of the present invention, the zinc oxide performs ionic bonding with the carboxy group of the carboxylic acid-modified nitrile-based copolymer in the dip molding latex composition, and thus the carboxylic acid-modified nitrile-based copolymer or carboxylic acid It may be a crosslinking agent for forming a crosslinking portion through ionic bonds between the modified nitrile-based copolymers. The content of zinc oxide may be 0.1 parts by weight to 5 parts by weight, or 0.5 parts by weight to 4 parts by weight based on 100 parts by weight (based on solids) of the total content of the carboxylic acid-modified nitrile-based copolymer latex in the dip molding latex composition. And, within this range, the crosslinking ability is excellent, the latex stability is excellent, and the tensile strength and flexibility of the manufactured dip molded article are excellent.

In addition, according to an embodiment of the present invention, the latex composition for dip molding may have a solid content (concentration) of 5% to 40% by weight, 8% to 35% by weight, or 10% to 30% by weight. And, within this range, the efficiency of the latex transport is excellent, and there is an effect of excellent storage stability by preventing an increase in the viscosity of the latex.

As another example, the dip molding latex composition may have a pH of 9 to 12, 9 to 11.5, or 9.5 to 11, and has excellent processability and productivity when manufacturing a dip molded article within this range. The pH of the latex composition for dip molding may be adjusted by the introduction of the aforementioned pH adjusting agent. The pH adjusting agent may be, for example, an aqueous potassium hydroxide solution having a concentration of 1% to 5% by weight, or aqueous ammonia having a concentration of 1% to 5% by weight.

In addition, according to an embodiment of the present invention, the latex composition for dip molding may further include additives such as pigments such as titanium dioxide, fillers such as silica, thickeners, and pH adjusters, if necessary.

Further, according to the present invention, a dip molded article is provided. The dip-molded product may be a dip-molded product manufactured by dip-molding the latex composition for dip molding, and may be a molded product including a dip-molding latex composition-derived layer formed from the dip-molding latex composition by dip molding.

The molded article manufacturing method for molding the molded article may include immersing the latex composition for dip molding by a direct immersion method, an anode adhesion immersion method, a Teague adhesion immersion method, etc. It can be carried out by an adhesion immersion method, and in this case, there is an advantage in that a dip-molded article having a uniform thickness can be obtained.

As a specific example, the method of manufacturing a molded article may include the steps of attaching a coagulant to a dip mold (S100); Forming a layer derived from the latex composition for dip molding, that is, a dip molding layer by immersing the dip molding mold to which the coagulant is attached to the latex composition for dip molding (S200); And heating the dip molding layer to crosslink the latex composition for dip molding (S300).

According to an embodiment of the present invention, the step (S100) is a step of attaching a coagulant to the surface of the dip molding mold by immersing the dip molding mold in a coagulant solution to form a coagulant in the dip molding mold, and the coagulant solution is a coagulant Is dissolved in water, alcohol, or a mixture thereof, and the content of the coagulant in the coagulant solution is 5% to 75% by weight, 10% to 65% by weight, or 15% to 55% by weight based on the total content of the coagulant solution. It can be %. The coagulant may be, for example, a metal halide 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 it may be one or more selected from the group consisting of sulfates such as calcium sulfate, magnesium sulfate, and aluminum sulfate, and a specific example may be calcium chloride or calcium nitrate.

In addition, according to an embodiment of the present invention, the step (S100) is a step of immersing the dip molding mold in a coagulant solution for at least 1 minute and then drying it at 70°C to 150°C in order to attach the coagulant to the dip molding mold. It may further include.

According to an embodiment of the present invention, in the step (S200), a dip molding mold to which a coagulant is attached to form a dip molding layer is immersed in the latex composition for dip molding according to the present invention, taken out, and dip molded in the dip molding mold. It may be a step of forming a layer. In addition, according to an embodiment of the present invention, in the step (S200), in order to form a dip molding layer on the dip molding mold, during the immersion, immersion may be performed for 1 minute or more.

According to an embodiment of the present invention, in the step (S300), a liquid component is evaporated by heating a dip molding layer formed on a dip molding mold to obtain a dip molding product, and curing is performed by crosslinking the latex composition for dip molding. It may be a step to do. At this time, when using the latex composition for dip molding according to the present invention, vulcanization of the crosslinking agent composition included in the latex composition for dip molding and/or crosslinking by ionic bonding may be performed. In addition, according to an embodiment of the present invention, the heating is carried out by first heating at 70° C. to 150° C. for 1 minute to 10 minutes, and then secondary heating at 100° C. to 180° C. for 5 to 30 minutes. I can.

According to an embodiment of the present invention, the molded article may be a glove such as a surgical glove, an examination glove, an industrial glove and a household glove, a condom, a catheter, or a health care product.

Hereinafter, the present invention will be described in more detail by examples. However, the following examples are intended to illustrate the present invention, and that various changes and modifications can be made within the scope of the present invention and the scope of the technical idea are obvious to those skilled in the art, and the scope of the present invention is not limited thereto.

Example

Example One

<Production of carboxylic acid-modified nitrile-based copolymer latex>

In the polymerization reactor, a monomer mixture consisting of 28% by weight of acrylonitrile, 64.2% by weight of 1,3-butadiene, 5.8% by weight of methacrylic acid, and 2% by weight of hydroxyethyl methacrylate and 100 parts by weight of the monomer mixture t -Dodecylmercaptan 0.6 parts by weight, sodium dodecyl benzenesulfonate 2 parts by weight, potassium persulfate 0.3 parts by weight, hydroperoxide 0.1 parts by weight, glyoxal 0.5 parts by weight, water 140 parts by weight and then polymerization at a temperature of 37 ℃ Was initiated.

When the polymerization conversion rate reached 94%, 0.3 parts by weight of ammonium hydroxide was added to stop the polymerization. Thereafter, unreacted substances were removed through a deodorization process, and aqueous ammonia, an antioxidant, and an antifoaming agent were added to obtain a carboxylic acid-modified nitrile-based copolymer latex having a solid content of 45% and a pH of 8.5.

<Preparation of latex composition for dip molding>

To 100 parts by weight of the obtained carboxylic acid-modified nitrile-based copolymer latex (based on solid content), 1 part by weight of sulfur, 0.7 parts by weight of zinc di-n-butyldithiocarbamate (ZDBC), oxidation 1.5 parts by weight of zinc and 1 part by weight of titanium oxide, a potassium hydroxide solution, and secondary distilled water were added to obtain a latex composition for dip molding having a solid content of 16% by weight and a pH of 10.

<Manufacture of dip molded products>

A coagulant solution was prepared by mixing 13% by weight of calcium nitrate, 86.5% by weight of water, and 0.5% by weight of a wetting agent (manufactured by Huntsman Corporation, Australia, product name Teric 320), and a hand-shaped ceramic mold was added to the solution for 1 minute. After soaking and taking out, it was dried at 80° C. for 3 minutes to apply a coagulant to a hand-shaped mold.

Then, the hand-shaped mold coated with the coagulant was immersed in the obtained latex composition for dip molding for 1 minute and taken out, dried at 80° C. for 1 minute, and immersed in water for 3 minutes. Again, the mold was dried at 80° C. for 3 minutes and then crosslinked at 125° C. for 20 minutes. Thereafter, the crosslinked dip molded layer was peeled off from the hand-shaped mold to obtain a glove-shaped dip molded article.

Example 2

The preparation of the carboxylic acid-modified nitrile-based copolymer latex of Example 1 was carried out in the same manner as in Example 1, except that 0.1 parts by weight of glyoxal was added instead of 0.5 parts by weight.

Example 3

The preparation of the carboxylic acid-modified nitrile-based copolymer latex of Example 1 was carried out in the same manner as in Example 1, except that 1 part by weight of glyoxal was added instead of 0.5 part by weight.

Example 4

The preparation of the carboxylic acid-modified nitrile-based copolymer latex of Example 1 was carried out in the same manner as in Example 1, except that 0.05 parts by weight of glyoxal was added instead of 0.5 parts by weight.

Example 5

The preparation of the carboxylic acid-modified nitrile-based copolymer latex of Example 1 was carried out in the same manner as in Example 1, except that 1.5 parts by weight of glyoxal was added instead of 0.5 parts by weight.

Comparative example

Comparative example One

The preparation of the carboxylic acid-modified nitrile-based copolymer latex of Example 1 was carried out in the same manner as in Example 1, except that 0.5 parts by weight of glyoxal was not added.

Comparative example 2

The preparation of the carboxylic acid-modified nitrile-based copolymer latex of Example 1 was carried out in the same manner as in Example 1, except that 0.1 part by weight of hydroperoxide as an initiator was not added.

Experimental example

Experimental example One

The physical properties of the copolymer latex prepared in Examples and Comparative Examples were measured under the following conditions, and the results are shown in Tables 1 to 2 and FIGS. 1 to 2 below.

* Measurement of pKa of copolymer latex: It is pKa that determines the degree of ionization of the unsaturated acid monomer present in the copolymer latex. When the pKa is low, the amount of unsaturated acid monomer saponified at the pH at the time of manufacturing the glove increases, so that the glove having excellent workability and high strength can be manufactured. The pKa of the latex was measured by the following method. After the latex obtained by polymerization was diluted to 10%, the pH was raised to 12 using a 3% aqueous potassium hydroxide solution, and then stirred at 90° C. for 2 hours. Then, ammonia in the aqueous solution was removed, the obtained diluted solution was cooled to room temperature, and the pH was dropped to 2 or less using an aqueous hydrochloric acid solution diluted to 2%, followed by stirring at a temperature of 90° C. for 2 hours. Next, carbon dioxide in the aqueous solution was removed, the obtained diluted solution was cooled to room temperature, and an acid base titration graph was obtained using a 3% potassium hydroxide aqueous solution having an accurate concentration. The results are shown in FIGS. 1 and 2.

1 is a graph showing the pH change according to the amount of KOH input in Example 1 of the present invention. The amount of carboxylic acid calculated as the amount of KOH input between the first and second inflection points of FIG. 1 is an acid present on the surface. Is the amount of FIG. 2 is a differential curve of the input amount of KOH according to the pH shown in FIG. 1. The vertex of this quadratic function is the pKa of latex. Through this, it can be seen that the pKa of the copolymer latex prepared from Example 1 has a range of 8.5 to 9.5.

Experimental example 2

The properties of the latex composition for dip molding and the dip-molded article prepared in Examples and Comparative Examples were measured under the following conditions, and the results are shown in Tables 1 and 2 below.

* Tensile strength, elongation, stress at 300% elongation (modulus): A dumbbell-shaped test piece was prepared from a dip-molded product according to ASTM D-412. Subsequently, this test piece was pulled at an elongation speed of 500 mm/min, and the stress at the elongation rate of 300%, the tensile strength at break, and the elongation at break were measured.

* Syneresis measurement: The hand-shaped ceramic mold was immersed in the coagulant solution used in the manufacture of the dip molded product for 1 minute, taken out, and dried at 80° C. for 3 minutes, and the coagulant was applied to the hand-shaped mold. Thereafter, the hand-shaped mold to which the coagulant was applied was immersed in the latex composition for dip molding of each of Examples and Comparative Examples for 1 minute and taken out, and then the time required for droplets to fall from the hand-shaped mold was measured. If the droplet does not fall within 5 minutes, it is marked with an X.

* Appearance: If the workability of the dip molded product is poor, there will be flow marks on the glove. The appearance of the glove was observed, and when there were flow marks, X was indicated, and when workability was excellent without flow marks, ○ was indicated.

division			Example
			One	2	3	4	5
Glyoxal content		Parts by weight	0.5	0.1	One	0.05	1.5
Potassium persulfate content		Parts by weight	0.3	0.3	0.3	0.3	0.3
Hydro peroxide content		Parts by weight	0.1	0.1	0.1	0.1	0.1
Latex properties		pKa	9.2	9.1	9.1	9.0	9.1
Tensile properties	The tensile strength	MPa	34.3	38	35	29	30
	Elongation	%	620	650	580	641	576
	300% modulus	MPa	6.9	6.3	8.6	6.0	9.2
Workability	Syneresis	Min	X	X	X	X	X
	Appearance properties	-	○	○	○	○	○

division			Comparative example
			One	2
Glyoxal content		Parts by weight	0	0.5
Potassium persulfate content		Parts by weight	0.3	0.3
Hydro peroxide content		Parts by weight	0.1	0
Latex properties		pKa	9.6	9.7
Tensile properties	The tensile strength	MPa	29	30
	Elongation	%	650	598
	300% modulus	MPa	5.2	6.9
Workability	Syneresis		Min	2	One
	Appearance properties	-	X	X

Referring to Tables 1 and 2, in the preparation of the carboxylic acid-modified nitrile-based copolymer latex, Examples 1 to 5 in which all of glyoxal, potassium persulfate as a polymerization initiator, and hydroperoxide as an initiator are added, Compared to the case where no input (Comparative Example 1) or no starting activator is added (Comparative Example 2), the pKa of the latex is low, the workability of the composition for dip molding is excellent, and the tensile properties of the dip molded product are excellent. can confirm.

Claims (14)

1. A monomer mixture comprising a conjugated diene monomer, an ethylenically unsaturated nitrile monomer, and an ethylenically unsaturated acid monomer,

   A method for producing a carboxylic acid-modified nitrile-based copolymer latex comprising the step of emulsion polymerization in the presence of a crosslinking agent containing glyoxal.
2. The method of claim 1,

   The monomer mixture is a method for producing a carboxylic acid-modified nitrile-based copolymer latex containing a water-soluble monomer.
3. The method of claim 2,

   The emulsion polymerization is a persulfate-based polymerization initiator containing at least one selected from the group consisting of sodium persulfate, potassium persulfate and ammonium persulfate; And

   A method for producing a carboxylic acid-modified nitrile-based copolymer latex which is carried out in the presence of an initiator containing at least one selected from the group consisting of hydroperoxide, ferrous sulfate and sodium metabisulfite.
4. The method of claim 1,

   The conjugated diene-based 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 A method for producing a carboxylic acid-modified nitrile-based copolymer latex comprising a.
5. The method of claim 1,

   The ethylenically unsaturated nitrile-based monomer includes at least one selected from the group consisting of acrylonitrile, methacrylonitrile, hummaronitrile, α-chloronitrile and α-cyano ethyl acrylonitrile. Method for producing a nitrile-based copolymer latex.
6. 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. A method for producing a carboxylic acid-modified nitrile-based copolymer latex comprising at least one selected from the group.
7. The method of claim 2,

   The water-soluble monomer includes at least one selected from the group consisting of hydroxy ethyl acrylate, hydroxy ethyl methacrylate, hydroxy propyl methacrylate, dimethylaminoethyl acrylate, and diethylaminoethyl methacrylate. A method for producing a phosphorus carboxylic acid-modified nitrile-based copolymer latex.
8. The method of claim 3,

   The content of the persulfate-based polymerization initiator is 0.1 to 2 parts by weight based on 100 parts by weight of the total monomer mixture.
9. The method of claim 3,

   The amount of the initiator activator is 1 to 100 parts by weight based on 100 parts by weight of the persulfate-based polymerization initiator.
10. The method of claim 1,

    The content of the crosslinking agent is 0.1 to 1 part by weight based on the total 100 parts by weight of the monomer mixture.
11. Carboxylic acid-modified nitrile-based copolymer comprising a repeating unit derived from a conjugated diene-based monomer, a repeating unit derived from an ethylenically unsaturated nitrile-based monomer, a repeating unit derived from an ethylenically unsaturated acid monomer, and a glyoxal-derived moiety Latex.
12. A carboxylic acid-modified nitrile-based copolymer comprising a repeating unit derived from a conjugated diene-based monomer, a repeating unit derived from an ethylenically unsaturated nitrile-based monomer, a repeating unit derived from an ethylenically unsaturated acid monomer, a repeating unit derived from a water-soluble monomer, and a portion derived from glyoxal,

    A carboxylic acid-modified nitrile-based copolymer latex having a pKa of 8.5 to 9.5.
13. A latex composition for dip molding comprising the carboxylic acid-modified nitrile-based copolymer latex according to claim 11 or 12.
14. A dip molded article comprising a layer derived from the latex composition for dip molding according to claim 13.

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