KR102601327B1 - Latex composition for dip-forming, method for preparing the composition and article formed by the composition - Google Patents

Abstract

The present invention relates to a latex composition for dip molding, and more specifically, to a latex composition for dip molding comprising a carboxylic acid-modified nitrile-based copolymer latex and a polyvalent metal cation compound, wherein the carboxylic acid-modified nitrile-based copolymer latex , a carboxylic acid-modified nitrile-based copolymer containing 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 unit derived from an alkyl methacrylate-based monomer; , the alkyl group of the alkyl methacrylate-based monomer is an alkyl group having 12 carbon atoms or less, and the content of repeating units derived from the alkyl methacrylate-based monomer is 0.8% by weight to 6.5% by weight based on the total content of the carboxylic acid-modified nitrile-based copolymer. A latex composition for in-dip molding, a manufacturing method thereof, and a molded article manufactured therefrom are provided.

Description

Latex composition for dip molding, method for manufacturing the same, and molded article formed therefrom

The present invention relates to a latex composition for dip molding, and more specifically, to the latex composition for dip molding, a method of manufacturing the same, and a molded article manufactured therefrom.

As interest in the environment and safety has increased significantly in various technological fields such as the food industry, electronics industry, and medical field, as well as in everyday life such as housework, the demand for gloves to protect hands has increased, and the market for rubber gloves has also increased significantly. increased.

In the glove market, as natural rubber gloves are known to contain allergy-causing factors such as proteins contained in natural rubber, the demand for sulfur cross-linked gloves made by dip molding latex has increased as an alternative to natural rubber gloves. , As a result, changes appeared in the glove market. However, even in the case of sulfur cross-linked gloves made by dip molding latex, the vulcanization accelerators used during the sulfur cross-linking process, such as thiuram and carbamate, are known to cause allergies. , interest in and demand for gloves that do not contain sulfur and non-vulcanization accelerators is increasing.

Accordingly, in order to prevent side effects caused by sulfur and vulcanization accelerators, various attempts have been made to make rubber gloves without using sulfur and vulcanization accelerators. Among them, a representative attempt was to increase strength by using an aluminum-based crosslinking agent to form an ionic bond with the carboxylic acid of synthetic latex. However, when manufacturing latex gloves using an aluminum-based crosslinking agent as described above, the metal bond between carboxylic acid and zinc ions is weakened by ammonia, urea, and citric acid, which are major components of human sweat, and this reduces the durability of the gloves. There is a problem of significant degradation. Additionally, in the case of latex gloves manufactured using the aluminum-based crosslinking agent, the stickiness between the gloves increases and there is a problem of the gloves sticking together when the gloves are recovered from the packaging material. Therefore, there is an urgent need to develop gloves that have excellent durability and low stickiness while manufacturing non-vulcanized and non-vulcanized accelerator gloves.

KR 2014-0053859 A

The problem to be solved by the present invention is to solve the problems mentioned in the background technology of the above invention, to provide gloves, etc. manufactured by dip molding a latex composition for dip molding containing a carboxylic acid-modified nitrile-based copolymer latex. While preventing allergies caused by dip molded products, the durability of dip molded products is improved and stickiness is improved.

In other words, the present invention was developed to solve the problems of the prior art, and by introducing a hydrophobic monomer with a low glass transition temperature when producing carboxylic acid-modified nitrile-based copolymer latex, without sulfur crosslinking by sulfur and vulcanization accelerator, While maintaining the physical properties such as tensile properties of dip molded products at the same or higher level, the durability of dip molded products is improved due to the low glass transition temperature, and the stickiness of dip molded products is reduced due to the increased hydrophobicity of the surface of the copolymer particles in latex. The purpose is to provide a latex composition for molding, a manufacturing method thereof, and a dip molded article formed therefrom.

According to one embodiment of the present invention to solve the above problem, the present invention is a latex composition for dip molding comprising a carboxylic acid-modified nitrile-based copolymer latex and a polyvalent metal cation compound, wherein the carboxylic acid-modified nitrile-based copolymer The polymer latex is a carboxylic acid-modified nitrile-based copolymer containing 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 unit derived from an alkyl methacrylate-based monomer. It includes, the alkyl group of the alkyl methacrylate-based monomer is an alkyl group having 12 carbon atoms or less, and the content of repeating units derived from the alkyl methacrylate-based monomer is 0.8% by weight to 0.8% by weight based on the total content of the carboxylic acid-modified nitrile-based copolymer. A latex composition for dip molding of 6.5% by weight is provided.

In addition, the present invention provides a carboxylic acid-modified copolymer comprising a carboxylic acid-modified nitrile-based copolymer by polymerizing a monomer mixture containing a conjugated diene-based monomer, an ethylenically unsaturated nitrile-based monomer, an ethylenically unsaturated acid monomer, and an alkyl methacrylate-based monomer. Preparing nitrile-based copolymer latex; And adding a polyvalent metal cation compound to the prepared carboxylic acid-modified nitrile-based copolymer latex, wherein the alkyl group of the alkyl methacrylate monomer is an alkyl group having 12 carbon atoms or less, and the alkyl methacrylate monomer A method for producing a latex composition for dip molding is provided wherein the content is 0.8% by weight to 6.5% by weight based on the total content of the monomer mixture.

Additionally, the present invention provides a molded article including a layer derived from a latex composition for dip molding.

When manufacturing dip molded products such as gloves using the latex composition for dip molding according to the present invention, physical properties such as tensile properties are maintained at the same or higher level, but it does not contain sulfur or vulcanization accelerators, preventing allergy to the user. Durability is improved due to the introduction of hydrophobic monomers with a low glass transition temperature, and the increased hydrophobicity of the particle surface in latex reduces stickiness, which has the effect of preventing dip molded products from sticking together when recovered from packaging materials.

Terms or words used in the description and claims of the present invention should not be construed as limited to their ordinary or dictionary meanings, and the inventor should appropriately use the concept of the term to explain his or her invention in the best way. Based on the principle of definability, it must be interpreted with meaning and concept consistent with the technical idea of the present invention.

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

The latex composition for dip molding according to the present invention may include a carboxylic acid-modified nitrile-based copolymer latex and a polyvalent metal cation compound.

According to one embodiment of the present invention, the carboxylic acid-modified nitrile-based copolymer latex includes 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 an alkyl methacrylate. A carboxylic acid-modified nitrile-based copolymer comprising a repeating unit derived from a monomer-based monomer, wherein the alkyl group of the alkyl methacrylate-based monomer is an alkyl group having 12 carbon atoms or less, and the content of the repeating unit derived from the alkyl methacrylate-based monomer is as described above. It may be 0.8% by weight to 6.5% by weight based on the total content of the carboxylic acid-modified nitrile-based copolymer. The carboxylic acid-modified nitrile-based copolymer latex includes a repeating unit derived from an alkyl methacrylate-based monomer, and thus includes the carboxylic acid-modified nitrile-based copolymer latex due to the low glass transition temperature of the alkyl methacrylate-based monomer. It has the effect of improving the durability of molded products dip molded from the latex composition for dip molding and reducing the stickiness of the molded products due to the increase in hydrophobicity of the surface of the copolymer particles within the latex particles.

In the present invention, the term 'monomer-derived repeating unit' may refer to a component, structure, or the substance itself derived from a monomer. As a specific example, during polymerization of a polymer, the input monomer participates in the polymerization reaction and repeats within the polymer. It may mean a unit.

In the present invention, the term 'latex' may mean that a polymer or copolymer polymerized by polymerization exists in a dispersed form in water, and specific examples include fine particles of a polymer on rubber or a copolymer on rubber polymerized by emulsion polymerization. This may mean that it exists in a colloidal state dispersed in water.

According to one embodiment of the present invention, the carboxylic acid-modified nitrile-based copolymer contains 35% to 80% by weight of repeating units derived from conjugated diene monomers and 10% to 50% by weight of repeating units derived from ethylenically unsaturated nitrile monomers. , it may contain 2% to 10% by weight of repeating units derived from ethylenically unsaturated acid monomers and 0.8% to 6.5% by weight of repeating units derived from alkyl methacrylate monomers.

According to one embodiment of the present invention, the conjugated diene monomer forming the repeating unit derived from the conjugated diene monomer is 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3 -It may be one or more selected from the group consisting of butadiene, 1,3-pentadiene, and isoprene, and as a specific example, it may be 1,3-butadiene or isoprene, and as a more specific example, it may be 1,3-butadiene. The content of the repeating unit derived from the conjugated diene-based monomer may be 35% to 80% by weight, 40% to 75% by weight, or 45% to 70% by weight, based on the total content of the carboxylic acid-modified nitrile-based copolymer, Within this range, dip molded products molded from the latex composition for dip molding containing the carboxylic acid-modified nitrile-based copolymer are flexible, have excellent wearing comfort, and have excellent oil resistance and tensile strength.

In addition, according to one embodiment of the present invention, the ethylenically unsaturated nitrile-based monomers forming the repeating units derived from the ethylenically unsaturated nitrile-based monomers include acrylonitrile, methacrylonitrile, humaronitrile, α-chloronitrile, and α-chloronitrile. -It may be one or more types selected from the group consisting of cyano ethyl acrylonitrile, and as a specific example, it may be acrylonitrile and methacrylonitrile, and as a more specific example, it may be acrylonitrile. The content of the repeating unit derived from the ethylenically unsaturated nitrile-based monomer may be 10% to 50% by weight, 15% to 40% by weight, or 20% to 40% by weight based on the total content of the carboxylic acid-modified nitrile-based copolymer. Within this range, dip molded products molded from the latex composition for dip molding containing the carboxylic acid-modified nitrile-based copolymer are flexible, have excellent wearing comfort, and have excellent oil resistance and tensile strength.

In addition, according to one embodiment of the present invention, the ethylenically unsaturated acid monomer forming the repeating unit derived from the ethylenically unsaturated acid monomer may be an ethylenically unsaturated monomer containing an acidic group such as a carboxyl group, a sulfonic acid group, and an acid anhydride group, Specific examples 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; 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 maleate, and more specific examples include acrylic acid and methacrylic acid. , itaconic acid, maleic acid, and fumaric acid. A more specific example may be methacrylic acid. During polymerization, the ethylenically unsaturated acid monomer may be used in the form of a salt such as an alkali metal salt or ammonium salt. In addition, the content of the repeating unit derived from the ethylenically unsaturated acid monomer is 2% by weight to 10% by weight, 2% by weight to 9% by weight, or 2% by weight to 8% by weight based on the total content of the carboxylic acid-modified nitrile-based copolymer. Within this range, a dip molded product molded from a latex composition for dip molding containing the carboxylic acid-modified nitrile-based copolymer is flexible, has excellent wearing comfort, and has excellent tensile strength.

In addition, according to one embodiment of the present invention, the alkyl methacrylate monomer forming the repeating unit derived from the alkyl methacrylate monomer has an alkyl group of the alkyl methacrylate monomer having 12 or less carbon atoms, 5 to 12 carbon atoms, Or it may have 8 to 12 carbon atoms. Within this range, it is possible to secure a low glass transition temperature of the carboxylic acid-modified nitrile-based copolymer and at the same time ensure the hydrophobicity of the surface of the copolymer particles in the latex within an appropriate range. Accordingly, the use of a polyvalent metal cation compound as a crosslinking agent can be achieved. In this case, compared to dip molded products made by sulfur crosslinking using sulfur and a vulcanization accelerator, it has excellent durability and has the effect of reducing stickiness.

As a specific example, the alkyl methacrylate-based monomer may be one or more selected from the group consisting of dodecyl methacrylate, octyl methacrylate, decyl methacrylate, and isodecyl methacrylate, and a specific example is dodecyl methacrylate. and octyl methacrylate. A more specific example may be dodecyl methacrylate. In addition, the content of the repeating unit derived from the alkyl methacrylate monomer is 0.8% by weight to 6.5% by weight, 1% by weight to 5% by weight, or 3% by weight to 5% by weight based on the total content of the carboxylic acid-modified nitrile-based copolymer. , or it may be 4% to 5% by weight, and within this range, due to the low glass transition temperature of the alkyl methacrylate monomer, a latex composition for dip molding containing the carboxylic acid-modified nitrile-based copolymer latex, especially It has the effect of improving the durability of molded products dip molded from a latex composition for dip molding using a polyvalent metal cation compound as a crosslinking agent and reducing the stickiness of the molded product due to the increase in hydrophobicity of the surface of the copolymer particles in the latex particles.

According to one embodiment of the present invention, the carboxylic acid-modified nitrile-based copolymer latex may have a glass transition temperature of -40 ℃ to -15 ℃, or -35 ℃ to -20 ℃, and within this range, the carboxylic acid It prevents the deterioration of tensile properties such as tensile strength and the occurrence of cracks in molded products dip-molded from a latex composition for dip molding containing a modified nitrile-based copolymer latex, while providing excellent wearing comfort due to low stickiness. The glass transition temperature may be measured using differential scanning calorimetry.

In addition, according to one embodiment of the present invention, the average particle diameter of the carboxylic acid-modified nitrile-based copolymer particles in the carboxylic acid-modified nitrile-based copolymer latex may be 80 nm to 300 nm, and within this range, the carboxylic acid-modified nitrile-based copolymer latex may have an average particle diameter of 80 nm to 300 nm. The tensile properties, such as tensile strength, of molded products dip molded from a latex composition for dip molding containing copolymer latex are excellent. The average particle diameter may be measured using a laser scattering analyzer (Nicomp).

In addition, according to one embodiment of the present invention, the solid concentration of the carboxylic acid-modified nitrile-based copolymer latex may be 10% by weight to 30% by weight, and within this range, the efficiency of latex transportation is excellent, and the viscosity of the latex is excellent. It has excellent storage stability by preventing rise. The solid content concentration of the carboxylic acid-modified nitrile-based copolymer latex may be the solid content concentration of the carboxylic acid-modified nitrile-based copolymer latex after polymerization is completed. As a specific example, the solid content before removing moisture and unreacted monomers through a deodorization process, etc. It could be concentration.

According to one embodiment of the present invention, the polyvalent metal cation compound is applied to the surface of the copolymer particles in the carboxylic acid-modified nitrile-based copolymer latex to enable crosslinking without using a crosslinking agent such as sulfur, a vulcanization accelerator, or zinc oxide. It may be a crosslinking agent for crosslinking through ionic bonding with carboxyl groups present in large quantities.

According to one embodiment of the present invention, the polyvalent metal cation compound may be at least one selected from the group consisting of aluminum hydroxide, aluminum sulfate, aluminum chloride, aluminum lactate, and aluminum acetylacetonate, and as described above, the aluminum cation When the compound is used as an ionic bond crosslinking agent, weakening of the bond in an acidic solution can be prevented, thereby preventing a decrease in the strength of the dip molded product.

In addition, according to one embodiment of the present invention, the content of the polyvalent metal cation compound is 0.1 part by weight to 5 parts by weight, 0.1 part by weight to 100 parts by weight (based on solid content) of the carboxylic acid-modified nitrile-based copolymer latex. It may be 3 parts by weight, or 0.5 parts by weight to 3 parts by weight, and within this range, it is possible to prevent weakening of bonds in acidic solutions, thereby preventing a decrease in the strength of dip molded products.

In addition, according to one 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.

In addition, according to one embodiment of the present invention, the latex composition for dip molding has a solid content (concentration) of 5% by weight to 40% by weight, 8% by weight to 35% by weight, or 10% by weight to 33% by weight. Within this range, the efficiency of latex transportation is excellent, and an increase in latex viscosity is prevented, resulting in excellent storage stability.

As another example, the latex composition for dip molding may have a pH of 9 to 12, 9 to 11, or 9.5 to 10.5, and within this range, it has excellent processability and productivity when manufacturing dip molded products. The pH of the latex composition for dip molding can be adjusted by adding the pH adjuster described above. For example, the pH adjuster may be an aqueous solution of potassium hydroxide at a concentration of 1% to 5% by weight, or aqueous ammonia at a concentration of 1% to 5% by weight.

On the other hand, the latex composition for dip molding according to the present invention is a carboxylic acid-modified nitrile-based polymerization of a monomer mixture containing a conjugated diene-based monomer, an ethylenically unsaturated nitrile-based monomer, an ethylenically unsaturated acid monomer, and an alkyl methacrylate-based monomer. Preparing a carboxylic acid-modified nitrile-based copolymer latex containing a copolymer; and adding a multivalent metal cationic compound to the prepared carboxylic acid-modified nitrile-based copolymer latex.

That is, the method for producing a latex composition for dip molding according to the present invention polymerizes a monomer mixture containing a conjugated diene monomer, an ethylenically unsaturated nitrile monomer, an ethylenically unsaturated acid monomer, and an alkyl methacrylate monomer to produce carboxylic acid-modified nitrile. Preparing a carboxylic acid-modified nitrile-based copolymer latex containing a copolymer; And adding a polyvalent metal cation compound to the prepared carboxylic acid-modified nitrile-based copolymer latex, wherein the alkyl group of the alkyl methacrylate monomer is an alkyl group having 12 carbon atoms or less, and the alkyl methacrylate monomer The content may be 0.8% by weight to 6.5% by weight based on the total content of the monomer mixture.

According to one embodiment of the present invention, polymerization of the carboxylic acid-modified nitrile-based copolymer may be carried out by emulsion polymerization. The polymerization may be carried out by polymerizing the monomer mixture, and each monomer included in the monomer mixture may be added in the type and amount of the monomer mentioned above, and may be added all at once or continuously.

Meanwhile, during the polymerization, the monomer mixture may be simultaneously introduced into the polymerization reactor prior to polymerization, or it may be carried out by first introducing a part of the monomer mixture into the polymerization reactor and then adding the remaining monomer mixture after the start of polymerization. As a specific example, the polymerization includes adding a portion of the monomer mixture to a polymerization reactor and initiating polymerization; And after the start of polymerization, when the polymerization conversion rate is 50% or less, the step of adding the remaining monomer mixture may be performed. As a more specific example, when a portion of the monomer mixture is added before the start of polymerization and the remaining amount is added after the start of polymerization, the monomer mixture partially added before the start of polymerization is 70% by weight or more based on the total content of the monomer mixture, and after the start of polymerization, The remaining monomer mixture may be added in an amount of 30% by weight or less based on the total content of the monomer mixture. In this case, the monomer mixture may be added all at once or continuously. In addition, when the monomer mixture is divided and added, the time of introduction may be when the polymerization conversion rate is 50% or less, or 10% to 50%. As described above, when the monomer mixture is divided and added, when monomer-derived repeating units derived from each monomer in the carboxylic acid-modified nitrile-based copolymer are formed, the distribution of monomers due to the difference in reaction rate for each monomer can be equalized. Accordingly, there is an effect of improving the balance between the physical properties of dip molded products manufactured using the carboxylic acid-modified nitrile-based copolymer.

Meanwhile, according to one embodiment of the present invention, the polymerization conversion rate is calculated by collecting a certain amount of sample from the reacting composition at regular time intervals, measuring the content of solids in the sample, and using Equation 1 below: You can.

[Equation 1]

Polymerization conversion (%) = (Ms - Mo) / (Mp - M'o)

In Equation 1, Ms is the weight of the dried copolymer, Mo is the sum of the weights of the emulsifier and polymerization initiator, Mp is the weight of the 100% polymerized copolymer, and M'o is the sum of the weights of the emulsifier and polymerization initiator. am.

Additionally, according to one embodiment of the present invention, polymerization of the carboxylic acid-modified nitrile-based copolymer may be carried out in the presence of an emulsifier, a polymerization initiator, a molecular weight regulator, etc.

When the polymerization of the carboxylic acid-modified nitrile-based copolymer is carried out including an emulsifier, the emulsifier may be, for example, at least one selected from the group consisting of anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants. Specific examples may include one or more anionic surfactants selected from the group consisting of alkylbenzene sulfonates, aliphatic sulfonates, higher alcohol sulfuric acid ester salts, α-olefin sulfonate salts, and alkyl ether sulfuric acid ester salts. 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 content of the monomer mixture, and polymerization is limited within this range. This is excellent and the amount of foam generated is small, which makes it easy to manufacture molded products.

In addition, when the polymerization of the carboxylic acid-modified nitrile-based copolymer is carried out including a polymerization initiator, the polymerization initiator may be, for example, a radical initiator, and specific examples include sodium persulfate, potassium persulfate, ammonium persulfate, potassium perphosphate, and Inorganic peroxides such as hydrogen peroxide; t-butyl peroxide, cumene hydroperoxide, p-menthane hydroperoxide, di-t-butyl peroxide, t-butylcumyl peroxide, acetyl peroxide, isobutyl peroxide, octanoyl peroxide, dibenzoyl peroxide oxide, organic peroxides such as 3,5,5-trimethylhexanol peroxide and t-butyl peroxy isobutyrate; It may be one or more selected from the group consisting of nitrogen compounds such as azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, azobiscyclohexanecarbonitrile, and methyl azobisisobutyric acid (butyric acid), A specific example may be an inorganic peroxide, and a more specific example may be persulfate. In addition, the polymerization initiator may be added in an amount of 0.01 to 2 parts by weight, or 0.02 to 1.5 parts by weight, based on 100 parts by weight of the total monomer mixture content, and has the effect of maintaining the polymerization rate at an appropriate level within this range. There is.

In addition, when the polymerization of the carboxylic acid-modified nitrile-based copolymer is carried out including a molecular weight regulator, the molecular weight regulator may include, for example, α-methylstyrene dimer; mercaptans such as t-dodecyl mercaptan, n-dodecyl mercaptan, and octyl mercaptan; halogenated hydrocarbons such as carbon tetrachloride, methylene chloride, and methylene bromide; It may be one or more selected from the group consisting of sulfur-containing compounds such as tetraethyl thiuram disulfide, dipentamethylene thiuram disulfide, and diisopropylxanthogen disulfide, and a specific example may be t-dodecyl mercaptan. In addition, the molecular weight regulator 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 1.0 parts by weight based on 100 parts by weight of the total content of the monomer mixture, and polymerization stability is within this range. This is excellent, and when manufacturing molded products after polymerization, the physical properties of the molded products are excellent.

In addition, according to one embodiment of the present invention, the polymerization of the carboxylic acid-modified nitrile-based copolymer may be carried out in water as a medium, specifically deionized water, and to ensure ease of polymerization, chelating agents, dispersants, and It may be carried out by further including additives such as pH adjusters, deoxidizers, particle size adjusters, anti-aging agents, and oxygen scavengers. According to one embodiment of the present invention, the emulsifier, polymerization initiator, molecular weight regulator, additives, etc. may be added to the polymerization reactor as a bulk or divided portion, like the monomer mixture, or may be added continuously at each injection.

In addition, according to one embodiment of the present invention, the polymerization of the carboxylic acid-modified nitrile-based copolymer may be carried out at a polymerization temperature of 10 ℃ to 90 ℃, 20 ℃ to 80 ℃, or 25 ℃ to 75 ℃, Latex stability is excellent within the range.

Meanwhile, according to one embodiment of the present invention, the method for producing the carboxylic acid-modified nitrile-based copolymer latex may include completing the polymerization reaction to obtain the carboxylic acid-modified nitrile-based copolymer latex. Termination of the polymerization reaction of the carboxylic acid-modified nitrile-based copolymer may be performed when the polymerization conversion rate is 90% or more, or 93% or more, and may be performed by adding a polymerization terminator, a pH adjuster, and an antioxidant. In addition, the method for producing the carboxylic acid-modified nitrile-based copolymer latex may further include a step of removing unreacted monomers by a deodorizing concentration process after completion of the reaction.

In addition, according to one embodiment of the present invention, the step of adding a polyvalent metal cation compound to the prepared carboxylic acid-modified nitrile-based copolymer latex is to prepare a polyvalent metal cationic compound for dip molding from the carboxylic acid-modified nitrile-based copolymer latex. This may be a step for manufacturing a latex composition. At this time, the type and content of the multivalent metal cation compound may be the same as described above.

In addition, according to one embodiment of the present invention, at the same time as the addition of the polyvalent metal cation compound, additives such as pigments such as titanium dioxide, fillers such as silica, thickeners, and pH adjusters may be added as necessary.

According to the present invention, a molded article including a layer derived from the latex composition for dip molding is provided. The molded article may be a dip molded article manufactured by dip molding the latex composition for dip molding, or may be a molded article including a layer derived from the latex composition for dip molding formed from the latex composition for dip molding. The molded product manufacturing method for molding the molded product may include the step of immersing the latex composition for dip molding by a direct immersion method, an anode adhesion immersion method, a Teague adhesion immersion method, etc., and specific examples include anode adhesion immersion method. It can be carried out by the adhesion dipping method, and in this case, there is an advantage in obtaining dip molded products of uniform thickness.

As a specific example, the molded product manufacturing method includes 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 latex composition for dip molding in the dip mold to which the coagulant is attached (S200); And it may include a step (S300) of crosslinking the latex composition for dip molding by heating the dip molding layer.

The step (S100) is a step of attaching the coagulant to the surface of the dip mold by immersing the dip mold in a coagulant solution to form a coagulant in the dip mold. The coagulant solution adds the coagulant to water, alcohol, or a mixture thereof. As a dissolved solution, the content of the coagulant in the coagulant solution may be 5% by weight to 50% by weight, or 10% by weight to 40% by weight based on the total content of the coagulant solution. The coagulant may include, 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; Acetate salts such as barium acetate, calcium acetate and zinc acetate; and sulfate such as calcium sulfate, magnesium sulfate, and aluminum sulfate. Specific examples may include calcium chloride or calcium nitrate.

In addition, the step (S200) may be a step of immersing a dip molding mold to which a coagulant is attached in order to form a dip molding layer in the latex composition for dip molding according to the present invention, taking it out, and forming a dip molding layer on the dip molding mold. there is.

In addition, the step (S300) may be a step in which liquid components are evaporated by heating the dip molding layer formed in the dip molding mold to obtain a dip molding product, and curing is performed by crosslinking the latex composition for dip molding. At this time, when using the latex composition for dip molding according to the present invention, crosslinking can be performed by ionic bonding with the polyvalent metal cation compound contained in the latex composition for dip molding, thereby reducing allergies caused by sulfur and vulcanization accelerators. It has the effect of preventing problems such as reactions from occurring.

According to one embodiment of the present invention, the molded article may be a glove such as surgical gloves, examination gloves, industrial gloves, and household gloves, condoms, catheters, or health care products.

Hereinafter, the present invention will be described in more detail through examples. However, the following examples are intended to illustrate 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, and the scope of the present invention is not limited to these alone.

Example

Example 1

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

In a polymerization reactor, 99 parts by weight of a monomer mixture consisting of 30.5% by weight of acrylonitrile, 52.7% by weight of 1,3-butadiene, 5.8% by weight of methacrylic acid, and 5.0% by weight of dodecyl methacrylate, and 0.55% by weight of t-dodecyl mercaptan. parts, 2.1 parts by weight of sodium dodecyl benzenesulfonate, 0.5 parts by weight of potassium persulfate, and 140 parts by weight of water were added, and polymerization was initiated at a temperature of 37°C. Then, when the polymerization conversion rate was 75%, 6.0% by weight of 1,3-butadiene, 0.055 part by weight of t-dodecyl mercaptan, and 0.4 part by weight of sodium dodecyl benzenesulfonate were added. Afterwards, when the polymerization conversion rate reached 94%, 0.3 parts by weight of ammonium hydroxide was added to stop the polymerization. Subsequently, a certain amount of moisture and unreacted monomers were removed through a deodorization process, and ammonia water, antioxidants, and antifoaming agents were added to obtain carboxylic acid-modified nitrile-based copolymer latex with a solid content of 45% by weight and pH of 8.5.

<Manufacture of latex composition for dip molding>

2.5 parts by weight of potassium hydroxide solution, 2.0 parts by weight of aluminum acetylacetonate, 1.2 parts by weight of titanium oxide, and double distilled water were added to 100 parts by weight (based on solid content) of the carboxylic acid-modified nitrile-based copolymer latex obtained above to obtain a solid content concentration of 20 weight. %, a latex composition for dip molding with pH 10 was obtained.

<Manufacture of deep molded products>

A coagulant solution was prepared by mixing 18 parts by weight of calcium nitrate, 81.9 parts by weight of water, and 0.1 parts by weight of a wetting agent (Teric 320, Huntsman Corporation, Australia). The hand-shaped ceramic mold was immersed in the prepared coagulant solution for 10 seconds, taken out, and dried at 80° C. for 4 minutes to apply the coagulant to the hand-shaped mold.

Afterwards, the mold to which the coagulant was applied was dipped into the obtained latex composition for dip molding for 10 seconds, taken out, dried at 80°C for 2 minutes, then dipped in water for 30 seconds for leaching, and then the mold was again heated at 110°C. Crosslinked for 20 minutes. The crosslinked dip molded layer was peeled off from the hand-shaped mold to obtain a glove-shaped dip molded product.

Example 2

In Example 1, when producing the carboxylic acid-modified nitrile-based copolymer latex, the same method as Example 1 was used, except that 5.0% by weight of octyl methacrylate was added instead of 5.0% by weight of dodecyl methacrylate in the monomer mixture. It was carried out as follows. At this time, the solid concentration of the prepared carboxylic acid-modified nitrile-based copolymer latex was 45% by weight and the pH was 8.5.

Example 3

In Example 1, when producing the carboxylic acid-modified nitrile-based copolymer latex, the same method as Example 1 was used, except that 5.0% by weight of decyl methacrylate was added instead of 5.0% by weight of dodecyl methacrylate in the monomer mixture. It was carried out as follows. At this time, the solid concentration of the prepared carboxylic acid-modified nitrile-based copolymer latex was 45% by weight and the pH was 8.5.

Example 4

In Example 1, when preparing the carboxylic acid-modified nitrile-based copolymer latex, 5.0% by weight of isodecyl methacrylate was added instead of 5.0% by weight of dodecyl methacrylate in the monomer mixture. The same method as Example 1 was used. It was carried out using this method. At this time, the solid concentration of the prepared carboxylic acid-modified nitrile-based copolymer latex was 45% by weight and the pH was 8.5.

Example 5

In Example 1, when preparing the carboxylic acid-modified nitrile-based copolymer latex, 56.7% by weight of 1,3-butadiene and dodecyl methacrylate were used instead of 52.7% by weight of 1,3-butadiene and 5.0% by weight of dodecyl methacrylate in the monomer mixture. It was carried out in the same manner as Example 1, except that 1.0% by weight of crylate was added. At this time, the solid concentration of the prepared carboxylic acid-modified nitrile-based copolymer latex was 45% by weight and the pH was 8.5.

Example 6

In Example 1, when preparing the carboxylic acid-modified nitrile-based copolymer latex, 54.7% by weight of 1,3-butadiene and dodecyl methacrylate were used instead of 52.7% by weight of 1,3-butadiene and 5.0% by weight of dodecyl methacrylate in the monomer mixture. It was carried out in the same manner as Example 1, except that 3.0% by weight of crylate was added. At this time, the solid concentration of the prepared carboxylic acid-modified nitrile-based copolymer latex was 45% by weight and the pH was 8.5.

Comparative Example 1

In Example 1, when preparing the carboxylic acid-modified nitrile-based copolymer latex, the monomer mixture contained 30.5% by weight of acrylonitrile, 52.7% by weight of 1,3-butadiene, 5.8% by weight of methacrylic acid, and 5.0% by weight of dodecyl methacrylate. Instead of %, 30.0% by weight of acrylonitrile, 57.7% by weight of 1,3-butadiene, and 6.3% by weight of methacrylic acid were added to prepare carboxylic acid-modified nitrile-based copolymer latex, and when preparing the latex composition for dip molding, carboxylic acid was used. Instead of 2.5 parts by weight of potassium hydroxide solution, 2.0 parts by weight of aluminum acetylacetonate, and 1.2 parts by weight of titanium oxide to 100 parts by weight of modified nitrile-based copolymer latex (based on solid content), 100 parts by weight of carboxylic acid-modified nitrile-based copolymer latex (based on solid content) ) in the above example, except that 1 part by weight of sulfur, 1.25 parts by weight of zinc oxide, 0.7 parts by weight of zinc dibutyl dibutyl dithiocarbamate (ZDBC), a vulcanization accelerator, and 1.2 parts by weight of titanium oxide were added. It was carried out in the same manner as in 1. At this time, the solid concentration of the prepared carboxylic acid-modified nitrile-based copolymer latex was 45% by weight and the pH was 8.5.

Comparative Example 2

In Example 1, when preparing the carboxylic acid-modified nitrile-based copolymer latex, the monomer mixture contained 30.5% by weight of acrylonitrile, 52.7% by weight of 1,3-butadiene, 5.8% by weight of methacrylic acid, and 5.0% by weight of dodecyl methacrylate. It was carried out in the same manner as Example 1, except that 30.0% by weight of acrylonitrile, 57.7% by weight of 1,3-butadiene, and 6.3% by weight of methacrylic acid were added instead of %. At this time, the solid concentration of the prepared carboxylic acid-modified nitrile-based copolymer latex was 45% by weight and the pH was 8.5.

Comparative Example 3

In Example 1, when preparing the carboxylic acid-modified nitrile-based copolymer latex, 5.0% by weight of tetradecyl methacrylate was added instead of 5.0% by weight of dodecyl methacrylate in the monomer mixture. The same method as Example 1 was used. It was carried out using this method. At this time, the solid concentration of the prepared carboxylic acid-modified nitrile-based copolymer latex was 45% by weight and the pH was 8.5.

Comparative Example 4

In Example 1, when preparing the carboxylic acid-modified nitrile-based copolymer latex, 5.0% by weight of octadecyl methacrylate was added instead of 5.0% by weight of dodecyl methacrylate in the monomer mixture. The same method as Example 1 was used. It was carried out using this method. At this time, the solid concentration of the prepared carboxylic acid-modified nitrile-based copolymer latex was 45% by weight and the pH was 8.5.

Comparative Example 5

In Example 1, when preparing the carboxylic acid-modified nitrile-based copolymer latex, 57.2% by weight of 1,3-butadiene and dodecyl methacrylate were used instead of 52.7% by weight of 1,3-butadiene and 5.0% by weight of dodecyl methacrylate in the monomer mixture. It was carried out in the same manner as Example 1, except that 0.5% by weight of crylate was added. At this time, the solid concentration of the prepared carboxylic acid-modified nitrile-based copolymer latex was 45% by weight and the pH was 8.5.

Comparative Example 6

In Example 1, when preparing the carboxylic acid-modified nitrile-based copolymer latex, 50.7% by weight of 1,3-butadiene and dodecyl methacrylate were used instead of 52.7% by weight of 1,3-butadiene and 5.0% by weight of dodecyl methacrylate in the monomer mixture. It was carried out in the same manner as Example 1, except that 7% by weight of crylate was added. At this time, the solid concentration of the prepared carboxylic acid-modified nitrile-based copolymer latex was 45% by weight and the pH was 8.5.

Experiment example

In order to compare the physical properties of each dip molded product manufactured in Examples 1 to 6 and Comparative Examples 1 to 6, tensile strength, stress at 300% and 500%, elongation, durability, and stickiness were measured and compared to Table 1 below. It is shown in 2.

* Tensile strength (kgf/mm ² ): According to the ASTM D638 method, the crosshead speed was pulled to 500 mm/min using a measuring device UTM (Instron, model 4466), and the point where the specimen was cut was measured. It was calculated according to Equation 2 below.

[Equation 2]

Tensile strength (kgf/mm ² ) = (load value (kgf)) / (thickness (mm)

* Elongation (%): According to the ASTM D638 method, the crosshead speed was pulled to 500 mm/min using a measuring device U.T.M. (Instron, 4466 model), and then the point where the specimen was cut was measured, using Equation 3 below: It was calculated according to .

[Equation 3]

Elongation (%) = (Length after stretching of specimen / Initial length of specimen)

* Stress at 300% and 500% (300% modulus and 500% modulus, MPa): According to the ASTM D638 method, the crosshead speed was pulled to 500 mm/min using a measuring device U.T.M. (Instron, model 4466). Then, the stress at 300% (300% modulus, MPa) and the stress at 500% (500% modulus, MPa) were calculated according to Equation 4 and Equation 5 below.

[Equation 4]

Stress at 300% (300% modulus, MPa) = tensile strength when the specimen is stretched to 3 times the initial length (300%) (1 MPa = 0.10197 kgf/mm ² )

[Equation 5]

Stress at 500% (300% modulus, MPa) = Tensile strength when stretched to 5 times (500%) the initial length of the specimen (1 MPa = 0.10197 kgf/mm ² )

* Durability: 200% elongation by soaking the letter-shaped specimen in an artificial sweat solution (18% by weight of sodium chloride, 3.6% by weight of urea, 18.95% by weight of lactic acid, 27.5% by weight of ammonia water, and 31.95% by weight of distilled water). This was repeated and the number of times the glove specimen broke was measured.

* Stickiness: After overlapping four glove specimens at 45°C, a load of about 700 g was placed on the gloves, and after maintaining it for 15 hours, the stickiness between the gloves was expressed on a 10-point scale. The less stickiness between the gloves, the closer to 1 point, and the more stickiness between gloves, the closer to 10 points.

division Example One 2 3 4 5 6 Tensile strength (kgf/mm ² ) 37.4 33.1 41.2 40.8 40.2 39.5 Elongation (%) 617.2 633.1 630.2 606.1 610.2 620.1 300% modulus (MPa) 6.1 6.3 6 6.5 6.4 6.3 500% modulus (MPa) 17.1 18.5 17.3 18.8 19 18.2 Durability (number of times) 381 312 349 273 276 327 Stickiness (10 point method) 2 5 4 6 6 4

division Comparative example One 2 3 4 5 6 Tensile strength (kgf/mm ² ) 45.2 42.9 38.1 43.8 42.7 35.4 Elongation (%) 580.9 627.8 592.4 557.2 631.4 594.4 300% modulus (MPa) 7.1 6.7 6.5 7.5 6.6 5.9 500% modulus (MPa) 22.0 19 20.1 27.7 18.9 16.8 Durability (number of times) 262 253 252 204 252 261 Stickiness (10 point method) 5 8 8 10 8 7

As shown in Table 2, as a dip molded product by conventional sulfur crosslinking, Comparative Example 1 in which sulfur and a vulcanization accelerator were added to a carboxylic acid-modified nitrile-based copolymer latex containing no alkyl methacrylate monomer and sulfur crosslinked. In comparison, in the case of Comparative Example 2, in which a polyvalent metal cation compound was added to crosslink the carboxylic acid-modified nitrile-based copolymer latex that does not contain an alkyl methacrylate monomer, durability was lowered, and in particular, stickiness increased. You can.

Based on this, looking at the results of the examples of the present invention, as shown in Tables 1 and 2 above, dip molded products were produced using the latex composition for dip molding containing the carboxylic acid-modified nitrile-based copolymer prepared according to the present invention. In the case of Examples 1 to 6, which did not contain an alkyl methacrylate monomer and were cross-linked with sulfur, the tensile properties were maintained at the same or higher level, while durability and stickiness were improved. It was confirmed that, in particular, compared to Comparative Example 2, which did not contain an alkyl methacrylate monomer and used a polyvalent metal cation compound as a crosslinker, tensile properties such as tensile strength, elongation, and 300% and 500% modulus were equivalent. It was confirmed that durability and stickiness were significantly improved while maintaining the level or higher. This is believed to be caused by partially replacing the 1,3-butadiene monomer with an alkyl methacrylate monomer that has a low glass transition temperature and is hydrophobic.

On the other hand, in the case of Comparative Examples 2 and 3 manufactured including methacrylate monomers containing an alkyl group with 14 or more carbon atoms outside the scope limited in the present invention, not only did the tensile properties deteriorate, but durability and stickiness also sharply decreased. It has been degraded. This is believed to be due to the fact that the hydrophobicity of the alkyl methacrylate monomer becomes very large, and the alkyl methacrylate monomer reduces the stability of the copolymer particles in the latex during polymerization, causing the copolymer particles in the latex to grow unevenly.

In addition, in the case of Comparative Example 4, which was manufactured including an alkyl methacrylate monomer in an amount less than the range limited in the present invention, tensile properties, durability, and stickiness were all at the same level as Comparative Example 1, and alkyl methacrylate It was confirmed that the effect improvement due to the addition of the monomer was minimal, and in the case of Comparative Example 5, which was manufactured by including an alkyl methacrylate monomer in excess of the range limited in the present invention, not only did the tensile properties deteriorate, but the durability also decreased. It was confirmed that the stickiness was also rapidly reduced, and as in Comparative Example 3, this was due to the fact that excessive alkyl methacrylate monomers during polymerization reduced the stability of the copolymer particles in the latex, causing the copolymer particles in the latex to grow unevenly. It is believed to be caused by

From the above results, the present inventors found that when manufacturing dip molded products such as gloves using the latex composition for dip molding containing the carboxylic acid-modified nitrile-based copolymer latex according to the present invention, the physical properties such as tensile properties are equal or While maintaining the level above that level, it does not contain sulfur or vulcanization accelerators to prevent allergies to users, durability is improved due to the introduction of hydrophobic monomers with a low glass transition temperature, and stickiness is reduced due to the increased hydrophobicity of the surface of the particles in the latex. I was able to confirm what was written.

Claims (10)

A latex composition for dip molding comprising a carboxylic acid-modified nitrile-based copolymer latex and a polyvalent metal cation compound,
The carboxylic acid-modified nitrile-based copolymer latex is,
A carboxylic acid-modified nitrile-based copolymer comprising a repeating unit derived from a conjugated diene 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 unit derived from an alkyl methacrylate-based monomer,
The alkyl methacrylate monomer is at least one selected from the group consisting of dodecyl methacrylate, decyl methacrylate, and isodecyl methacrylate,
A latex composition for dip molding wherein the content of the repeating unit derived from the alkyl methacrylate-based monomer is 1.0% by weight to 5.0% by weight based on the total content of the carboxylic acid-modified nitrile-based copolymer. According to paragraph 1,
The carboxylic acid-modified nitrile-based copolymer contains 35% to 80% by weight of repeating units derived from conjugated diene monomers, 10% to 50% by weight of repeating units derived from ethylenically unsaturated nitrile monomers, and repeating units derived from ethylenically unsaturated acid monomers. A latex composition for dip molding comprising 2% to 10% by weight and 1.0% to 5.0% by weight of repeating units derived from alkyl methacrylate monomers. delete delete delete According to paragraph 1,
The polyvalent metal cation compound is a latex composition for dip molding, wherein the polyvalent metal cation compound is at least one selected from the group consisting of aluminum hydroxide, aluminum sulfate, aluminum chloride, aluminum lactate, and aluminum acetylacetonate. According to paragraph 1,
The content of the polyvalent metal cation compound is 0.1 parts by weight to 5 parts by weight based on 100 parts by weight of the carboxylic acid-modified nitrile-based copolymer latex (based on solid content). Carboxylic acid-modified nitrile-based copolymer latex comprising a carboxylic acid-modified nitrile-based copolymer by polymerizing a monomer mixture containing a conjugated diene monomer, an ethylenically unsaturated nitrile-based monomer, an ethylenically unsaturated acid monomer, and an alkyl methacrylate-based monomer. manufacturing a; and
Comprising the step of adding a polyvalent metal cation compound to the prepared carboxylic acid-modified nitrile-based copolymer latex,
The alkyl methacrylate monomer is at least one selected from the group consisting of dodecyl methacrylate, decyl methacrylate, and isodecyl methacrylate,
The method of producing a latex composition for dip molding wherein the content of the alkyl methacrylate monomer is 1.0% by weight to 5.0% by weight based on the total content of the monomer mixture. According to clause 8,
In the step of preparing the carboxylic acid-modified nitrile-based copolymer latex, a portion of the monomer mixture is first introduced into the polymerization reactor, and the remaining monomer mixture is added after the start of polymerization. Manufacturing a latex composition for dip molding. method. A molded article comprising a layer derived from the latex composition for dip molding according to any one of claims 1, 2, 6, and 7.