Latex composition for dip molding, method for preparing same, and molded article

Abstract

The present invention relates to: a latex composition for dip molding having improved latex stability; a method for preparing same; and a molded article formed therefrom and having improved wearability and tensile properties, the latex composition comprising: a first carboxylic acid-modified nitrile-based copolymer latex including a first carboxylic acid-modified nitrile-based copolymer; and a second carboxylic acid-modified nitrile-based copolymer latex including a second carboxylic acid-modified nitrile-based copolymer and an alkali-soluble resin unit, wherein the alkali-soluble resin includes a conjugated diene-based monomer unit, an ethylenically unsaturated nitrile-based monomer unit, and an ethylenically unsaturated acid monomer unit.

Description

Latex composition for deep molding, method for producing the same, and molded product

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2024-0015242, filed January 31, 2024, the entire disclosure of which is incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a latex composition for dip molding with improved latex stability, a method for producing the same, and a molded product molded therefrom with improved fit and tensile properties.

[0005]

[0006] Traditionally, natural rubber was primarily used as a raw material for industrial, medical, and food-grade gloves, as well as products requiring flexibility such as balloons and condoms. However, due to the side effect of natural rubber causing serious protein allergies in some users, nitrile rubber is increasingly replacing natural rubber. Nitrile rubber boasts high chemical resistance and is widely used in work gloves, particularly those used by users handling organic solvents, as well as in medical and food-grade gloves.

[0007] In addition, due to the unstable supply and demand of natural rubber, many glove manufacturing companies are converting their natural rubber glove production lines to nitrile rubber glove production lines, and as awareness of safety increases, the use of disposable gloves manufactured from nitrile rubber is continuously increasing.

[0008] These nitrile rubber gloves are typically manufactured using dip molding latex. However, if the stability of the dip molding latex is low, coagulation may occur. This coagulation increases the defect rate of the final dip molded product, leading to reduced productivity. In severe cases, dip molding itself may become impossible.

[0009] In particular, when temperatures drop below freezing, such as in winter, the stability of dip molding latex deteriorates rapidly, leading to an increase in the formation of coagulation and sedimentation in stored dip molding latex. Therefore, there is a need for measures to improve the storage stability and low-temperature stability of dip molding latex.

[0010] Meanwhile, latex for dip molding is generally manufactured through emulsion polymerization, and emulsifiers are essential for polymerization stability. Consequently, a significant amount of emulsifier remains in the latex, which can cause foaming problems in the resulting dip molded product. To suppress foaming caused by emulsifier residue in the final dip molded product, the leaching process is being strengthened, but this process consumes a lot of water. However, it is difficult to reduce the amount of emulsifier to ensure the polymerization stability of dip molding latex, and even if polymerization stability is secured while reducing the amount of emulsifier, there is a problem that the workability of manufacturing molded products (reduction of syneresis time) is seriously reduced.

[0011] Therefore, a method is required that can reduce the content of emulsifier contained in latex for dip molding while also improving the stability and workability of the latex.

[0012] [Prior Art Literature]

[0013] [Patent Document]

[0014] (Patent Document 1) KR 10-1775798 B1 (August 31, 2017)

[0015]

[0016] The present invention has been devised to solve the problems of the above-mentioned prior art, and aims to provide a latex composition for dip molding that has excellent stability and molded product manufacturing workability while having a reduced emulsifier content.

[0017] In addition, the present invention aims to provide a method for producing the latex composition for dip molding.

[0018] In addition, the present invention aims to provide a molded product having excellent manufacturing workability, excellent tensile properties, and suppressed foaming, molded from the latex composition for deep molding.

[0019]

[0020] To solve the above problem, the present invention provides a latex composition for dip molding, a method for producing the same, and a molded product.

[0021] (1) The present invention provides a latex composition for dip molding, comprising: a first carboxylic acid-modified nitrile copolymer latex comprising a first conjugated diene monomer unit; a first ethylenically unsaturated nitrile monomer unit; and a first carboxylic acid-modified nitrile copolymer comprising a first ethylenically unsaturated acid monomer unit; and a second carboxylic acid-modified nitrile copolymer latex comprising a second conjugated diene monomer unit; and a second carboxylic acid-modified nitrile copolymer comprising a second ethylenically unsaturated nitrile monomer unit and an alkaline-soluble resin unit; wherein the alkaline-soluble resin comprises a third conjugated diene monomer unit, a third ethylenically unsaturated nitrile monomer unit, and a third ethylenically unsaturated acid monomer unit.

[0022] (2) The present invention provides a latex composition for dip molding, wherein the first carboxylic acid-modified nitrile copolymer latex and the second carboxylic acid-modified nitrile copolymer latex have a weight ratio of 1.00:0.20 to 1.25 in (1).

[0023] (3) The present invention provides a latex composition for dip molding, wherein the first carboxylic acid-modified nitrile copolymer according to (1) or (2) above comprises 35 to 78 wt% of a first conjugated diene monomer unit; 20 to 50 wt% of a first ethylenically unsaturated nitrile monomer unit; and 0.1 to 10 wt% of a first ethylenically unsaturated acid monomer unit.

[0024] (4) The present invention provides a latex composition for dip molding, wherein the second carboxylic acid-modified nitrile copolymer comprises 60 to 80 wt% of a second conjugated diene monomer unit; and 20 to 40 wt% of a second ethylenically unsaturated nitrile monomer unit, in any one of the above (1) to (3).

[0025] (5) The present invention provides a latex composition for dip molding, wherein the second carboxylic acid-modified nitrile-based copolymer latex according to any one of the above (1) to (4) contains 5 to 25 parts by weight of an alkaline water-soluble resin unit based on 100 parts by weight of the second carboxylic acid-modified nitrile-based copolymer.

[0026] (6) The present invention provides a latex composition for dip molding, wherein the alkaline water-soluble resin comprises 40 to 75 wt% of a third conjugated diene monomer unit; 10 to 50 wt% of a third ethylenically unsaturated nitrile monomer unit; and 10 to 50 wt% of a third ethylenically unsaturated acid monomer unit in any one of the above (1) to (5).

[0027] (7) The present invention provides a latex composition for dip molding, wherein the second carboxylic acid-modified nitrile-based copolymer latex has a micelle form in any one of the above (1) to (6), the micelle is formed from an alkaline water-soluble resin unit, and includes the second carboxylic acid-modified nitrile-based copolymer inside the micelle.

[0028] (8) The present invention provides a latex composition for dip molding, which comprises 1.5 to 2.5 parts by weight of an emulsifier based on 100 parts by weight of the total solid content in any one of (1) to (7).

[0029] (9) The present invention comprises a step of mixing a first carboxylic acid-modified nitrile-based copolymer latex and a second carboxylic acid-modified nitrile-based copolymer latex, wherein the first carboxylic acid-modified nitrile-based copolymer latex comprises a first carboxylic acid-modified nitrile-based copolymer including a first conjugated diene-based monomer unit, a first ethylenically unsaturated nitrile-based monomer unit, and a first ethylenically unsaturated acid monomer unit, and the second carboxylic acid-modified nitrile-based copolymer latex comprises a second carboxylic acid-modified nitrile-based copolymer including a second conjugated diene-based monomer unit and a second ethylenically unsaturated nitrile-based monomer unit, and an alkaline water-soluble resin unit, and the second carboxylic acid-modified nitrile-based copolymer latex is prepared by mixing and emulsion polymerizing a second conjugated diene-based monomer, a second ethylenically unsaturated nitrile-based monomer, and an alkaline water-soluble resin solution. A method for producing a latex composition for molding is provided.

[0030] (10) The present invention provides a method for producing a latex composition for dip molding, wherein, in the above (9), the first carboxylic acid-modified nitrile copolymer latex and the second carboxylic acid-modified nitrile copolymer latex are mixed in a weight ratio of 1.00:0.20 to 1.25.

[0031] (11) The present invention provides a method for producing a latex composition for dip molding, wherein, in the above (9) or (10), the alkaline water-soluble resin solution is used in an amount of 5 to 25 parts by weight based on solid content, based on 100 parts by weight of the total amount of the second conjugated diene monomer and the second ethylenically unsaturated nitrile monomer.

[0032] (12) The present invention provides a method for producing a latex composition for dip molding, wherein the alkaline water-soluble resin solution is injected in at least two portions before and after the initiation of emulsion polymerization, in any one of the above (9) to (11).

[0033] (13) The present invention provides a method for manufacturing a latex composition for dip molding, wherein, in any one of (9) to (12), the alkaline water-soluble resin solution is first introduced before the start of emulsion polymerization, second introduced after the start of emulsion polymerization, and the second introduction is continuously introduced during a polymerization conversion rate range of 30% to 70%.

[0034] (14) The present invention provides a method for manufacturing a latex composition for dip molding, wherein, in the above (13), the alkaline water-soluble resin solution at the first injection and the alkaline water-soluble resin solution at the second injection have a weight ratio of 1:0.2 to 1 based on solid content.

[0035] (15) The present invention provides a method for producing a latex composition for dip molding, wherein the alkaline water-soluble resin solution is produced by a method including a step of producing a polymer latex by emulsion polymerizing a third conjugated diene monomer, a third ethylenically unsaturated nitrile monomer, and a third ethylenically unsaturated acid monomer in a solvent; and a step of adding a pH adjuster to the polymer latex.

[0036] (16) The present invention provides a method for producing a latex composition for dip molding, wherein the alkaline water-soluble resin solution has a pH of 7.0 to 10.0 at 25°C in any one of the above (9) to (15).

[0037] (17) The present invention provides a method for producing a latex composition for dip molding, wherein the first carboxylic acid-modified nitrile copolymer latex is produced by emulsion polymerizing a first conjugated diene monomer; a first ethylenically unsaturated nitrile monomer; and a first ethylenically unsaturated acid monomer in a solvent, in any one of the above (9) to (16).

[0038] (18) The present invention provides a molded product including a layer derived from a latex composition for deep molding according to any one of (1) to (8) above.

[0039]

[0040] The latex composition for dip molding according to the present invention comprises a first carboxylic acid-modified nitrile copolymer latex and a second carboxylic acid-modified nitrile copolymer latex comprising an alkaline water-soluble resin unit, thereby having a reduced emulsifier content while exhibiting excellent latex stability and workability in manufacturing molded products.

[0041] In addition, a molded product according to the present invention can be molded from the latex composition for deep molding, and thus has low bubble generation and excellent tensile properties.

[0042]

[0043] Hereinafter, the present invention will be described in more detail to help understand the present invention.

[0044] The terms or words used in the description and claims of the present invention should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0045] Definition of terms

[0046] In the present invention, the term 'monomer unit' may indicate a component, structure, or substance itself derived from a monomer, and as a specific example, may mean a repeating unit formed within a polymer by a monomer introduced during polymerization of the polymer and participating in the polymerization reaction.

[0047] In the present invention, the term 'polymer' may mean both a homopolymer formed by polymerization from one type of monomer and a copolymer formed by copolymerization from two types of monomers.

[0048] In the present invention, the terms 'latex' and 'emulsion' may mean that a polymer or copolymer polymerized by polymerization exists in a form dispersed in water, and as a specific example, may mean that fine particles of a rubber-like polymer or a rubber-like copolymer polymerized by emulsion polymerization exist in a colloidal state dispersed in a solvent (water), and in the present invention, 'latex' and 'emulsion' may be used interchangeably.

[0049] The term 'composition' as used in the present invention includes a mixture of materials comprising the composition as well as reaction products and decomposition products formed from the materials of the composition.

[0050] In the present invention, the term 'derived layer' may refer to a layer formed from a polymer or copolymer, and as a specific example, may refer to a layer formed from a polymer or copolymer by attaching, fixing, and / or polymerizing the polymer or copolymer on a dip mold during the manufacture of a dip molded product.

[0051]

[0052] Latex composition for deep molding

[0053] The present invention provides a latex composition for dip molding that has excellent latex stability and workability in manufacturing molded products while having a reduced emulsifier content.

[0054] The latex composition for dip molding according to one embodiment of the present invention comprises a first carboxylic acid-modified nitrile copolymer latex comprising a first conjugated diene monomer unit; a first ethylenically unsaturated nitrile monomer unit; and a first carboxylic acid-modified nitrile copolymer comprising a first ethylenically unsaturated acid monomer unit; and a second carboxylic acid-modified nitrile copolymer latex comprising a second conjugated diene monomer unit; and a second carboxylic acid-modified nitrile copolymer comprising a second ethylenically unsaturated nitrile monomer unit and an alkali-soluble resin unit, wherein the alkali-soluble resin may comprise a third conjugated diene monomer unit, a third ethylenically unsaturated nitrile monomer unit, and a third ethylenically unsaturated acid monomer unit.

[0055] According to one embodiment of the present invention, the alkali-soluble resin (ASR) may be an alkali-soluble polymer composition or an alkali-soluble emulsion polymer.

[0056]

[0057] Typically, carboxylic acid-modified nitrile copolymer latexes constituting latex compositions for dip molding are manufactured by emulsion polymerization. At this time, an emulsifier is essential for polymerization stability, and a significant amount of the emulsifier remains in the latex, which remains in the dip molded product obtained from the latex composition for dip molding containing the same, causing a foaming problem. Therefore, the leaching process is being strengthened to suppress foaming due to emulsifier residues in the final dip molded product, but there is a problem that a lot of water is consumed in this process. However, it is difficult to reduce the emulsifier to ensure polymerization stability, and even if polymerization stability is secured while reducing the emulsifier, there is a problem that the workability of manufacturing molded products (reduction of syneresis time) is seriously reduced.

[0058] However, the latex composition for dip molding according to one embodiment of the present invention includes a first carboxylic acid-modified nitrile-based copolymer latex and a second carboxylic acid-modified nitrile-based copolymer latex prepared by emulsion polymerizing an alkaline water-soluble resin solution together with a conjugated diene-based monomer and an ethylenically unsaturated nitrile-based monomer, thereby having a reduced amount of emulsifier residue and excellent workability for manufacturing molded products.

[0059]

[0060] Hereinafter, a latex composition for deep molding according to one embodiment of the present invention will be specifically described by dividing it into its constituent components.

[0061]

[0062] First carboxylic acid modified nitrile copolymer latex

[0063] According to one embodiment of the present invention, the first carboxylic acid-modified nitrile copolymer latex may be a latex in which the first carboxylic acid-modified nitrile copolymer is dispersed in a solvent, and the solvent may be an aqueous solvent. As a specific example, the aqueous solvent may be water, and the water may be ion-exchanged water or distilled water.

[0064] According to one embodiment of the present invention, the first carboxylic acid-modified nitrile copolymer may include a first conjugated diene monomer unit, a first ethylenically unsaturated nitrile monomer unit, and a first ethylenically unsaturated acid monomer unit.

[0065] According to one embodiment of the present invention, the first conjugated diene monomer for forming the first conjugated diene monomer unit of the first carboxylic acid-modified nitrile copolymer may be 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, 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.

[0066] According to one embodiment of the present invention, the first carboxylic acid-modified nitrile-based copolymer may contain repeating units derived from the first conjugated diene monomer in an amount of 35 wt% to 78 wt%, 40 wt% to 75 wt%, or 45 wt% to 70 wt%, and within this range, a molded article molded from a latex composition for dip molding comprising a carboxylic acid-modified nitrile-based copolymer latex including the first carboxylic acid-modified nitrile-based copolymer has the effects of being flexible, having excellent wearability, and having excellent oil resistance and tensile strength.

[0067] According to one embodiment of the present invention, the first ethylenically unsaturated nitrile monomer forming the first ethylenically unsaturated nitrile monomer unit of the first carboxylic acid-modified nitrile copolymer may be at least one selected from the group consisting of acrylonitrile, methacrylonitrile, fumaronitrile, α-chloronitrile, and α-cyano ethyl acrylonitrile, and as a specific example, may be acrylonitrile and methacrylonitrile, and as a more specific example, may be acrylonitrile.

[0068] According to one embodiment of the present invention, the first carboxylic acid-modified nitrile-based copolymer may contain 20 wt% to 50 wt%, 20 wt% to 45 wt%, or 25 wt% to 40 wt% of the first ethylenically unsaturated nitrile-based monomer unit, and within this range, a molded article molded from a latex composition for dip molding comprising the first carboxylic acid-modified nitrile-based copolymer latex composition including the first carboxylic acid-modified nitrile-based copolymer has the effects of being flexible, having excellent wearability, and having excellent oil resistance and tensile strength.

[0069] According to one embodiment of the present invention, the first ethylenically unsaturated acid monomer forming the first ethylenically unsaturated acid monomer unit of the first carboxylic acid-modified nitrile copolymer may be an ethylenically unsaturated monomer containing an acidic group such as a carboxyl group, a sulfonic acid group, or an acid anhydride group, and specific examples thereof 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 at least one 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 specifically, it may be at least one selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, maleic acid, and fumaric acid, and a more specific example may be methacrylic acid. The first 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.

[0070] According to one embodiment of the present invention, the first carboxylic acid-modified nitrile-based copolymer may contain 0.1 wt% to 10 wt%, 0.5 wt% to 9 wt%, or 1 wt% to 8 wt% of the first ethylenically unsaturated acid monomer unit, and within this range, a molded article molded from a latex composition for dip molding comprising a first carboxylic acid-modified nitrile-based copolymer latex including the first carboxylic acid-modified nitrile-based copolymer has the effect of being flexible, having excellent wearability, and having excellent tensile strength.

[0071]

[0072] Second carboxylic acid modified nitrile copolymer latex

[0073] According to one embodiment of the present invention, the second carboxylic acid-modified nitrile copolymer latex may be a latex in which the second carboxylic acid-modified nitrile copolymer and an alkaline water-soluble resin unit are dispersed in a solvent, and the solvent may be an aqueous solvent. As a specific example, the aqueous solvent may be water, and the water may be ion-exchanged water or distilled water.

[0074] According to one embodiment of the present invention, the second carboxylic acid-modified nitrile-based copolymer latex may include a second carboxylic acid-modified nitrile-based copolymer including a second conjugated diene-based monomer unit and a second ethylenically unsaturated nitrile-based monomer unit, and an alkaline water-soluble resin unit.

[0075] According to one embodiment of the present invention, the second carboxylic acid-modified nitrile-based copolymer latex has a micelle form, and the micelle may include a second carboxylic acid-modified nitrile-based copolymer including a second conjugated diene-based monomer unit and a second ethylenically unsaturated nitrile-based monomer unit inside the micelle. Specifically, the alkaline water-soluble resin included in the second carboxylic acid-modified nitrile-based copolymer latex is a polymerization product of a hydrophilic ethylenically unsaturated acid monomer, a hydrophobic conjugated diene-based monomer, and an ethylenically unsaturated nitrile-based monomer, and is dissolved in an alkaline aqueous solution at a pH of 7 or higher by ionization of the ethylenically unsaturated acid. Accordingly, when producing the second carboxylic acid-modified nitrile copolymer, a hydrophobic conjugated diene monomer and an ethylenically unsaturated nitrile monomer are mixed with the above-mentioned alkaline-soluble resin solution, and the hydrophobic portion of the alkaline-soluble resin is distributed in the hydrophobic monomer, and the hydrophilic portion, the ionized ethylenically unsaturated acid, is distributed in the water phase, thereby forming a micelle form similar to a general emulsifier.

[0076] Due to the properties of the alkaline water-soluble resin, the second carboxylic acid-modified nitrile copolymer according to one embodiment of the present invention can easily undergo a polymerization reaction without a general emulsifier or with a very small amount of the emulsifier, as the alkaline water-soluble resin acts as an emulsifier.

[0077] In addition, according to one embodiment of the present invention, the 'alkali-soluble resin unit' may represent a component, structure, or substance itself derived from the alkali-soluble resin, and as an example, may be an alkali-soluble resin dispersed together with the second carboxylic acid-modified nitrile-based copolymer in the second carboxylic acid-modified nitrile-based copolymer latex. As another example, the alkali-soluble resin may function as a reactive polymer emulsifier, and may participate in a polymerization reaction together with the second conjugated diene-based monomer and the second ethylenically unsaturated nitrile-based monomer constituting the second carboxylic acid-modified nitrile-based copolymer to form a chemical bond and / or a strong physical bond with the polymer chain, and in this case, the alkali-soluble resin unit may include a unit (part) including a component, structure derived from the alkali-soluble resin that forms a chemical bond and / or a physical bond with the polymer chain.

[0078] According to one embodiment of the present invention, the second conjugated diene monomer for forming the second conjugated diene monomer unit of the second carboxylic acid-modified nitrile copolymer may be the same as described in the first conjugated diene monomer for forming the first conjugated diene monomer unit in the first carboxylic acid-modified nitrile copolymer, and specifically, the second conjugated diene monomer may be 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, 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. At this time, the second conjugated diene monomer for forming the second conjugated diene monomer unit of the second carboxylic acid-modified nitrile copolymer may be the same as or different from the first conjugated diene monomer for forming the first conjugated diene monomer unit of the first carboxylic acid-modified nitrile copolymer.

[0079] According to one embodiment of the present invention, the second carboxylic acid-modified nitrile-based copolymer may contain repeating units derived from the second conjugated diene-based monomer in an amount of 65 wt% to 80 wt%, 65 wt% to 75 wt%, or 65 wt% to 70 wt%, and within this range, a molded article molded from a latex composition for dip molding comprising a second carboxylic acid-modified nitrile-based copolymer latex including the second carboxylic acid-modified nitrile-based copolymer has the effects of being flexible and having excellent wearability, as well as excellent oil resistance and tensile strength.

[0080] According to one embodiment of the present invention, the second ethylenically unsaturated nitrile monomer forming the second ethylenically unsaturated nitrile monomer unit of the second carboxylic acid-modified nitrile copolymer may be the same as described in the first ethylenically unsaturated nitrile monomer for forming the first ethylenically unsaturated nitrile monomer unit in the first carboxylic acid-modified nitrile copolymer latex, and specifically, the second ethylenically unsaturated nitrile monomer may be at least one selected from the group consisting of acrylonitrile, methacrylonitrile, fumaronitrile, α-chloronitrile, and α-cyano ethyl acrylonitrile, and as a specific example, may be acrylonitrile and methacrylonitrile, and as a more specific example, may be acrylonitrile. At this time, the second ethylenically unsaturated nitrile monomer for forming the second ethylenically unsaturated nitrile monomer unit of the second carboxylic acid-modified nitrile copolymer latex may be the same as or different from the first ethylenically unsaturated nitrile monomer for forming the first ethylenically unsaturated nitrile monomer unit of the first carboxylic acid-modified nitrile copolymer.

[0081] According to one embodiment of the present invention, the second carboxylic acid-modified nitrile-based copolymer may contain 20 wt% to 40 wt%, 25 wt% to 35 wt%, or 25 wt% to 30 wt% of the second ethylenically unsaturated nitrile-based monomer unit, and a molded product molded from a latex composition for dip molding including the second carboxylic acid-modified nitrile-based copolymer latex containing the second ethylenically unsaturated nitrile-based monomer unit within this range is flexible and has excellent wearability, and at the same time has excellent oil resistance and tensile strength.

[0082] According to one embodiment of the present invention, the alkaline water-soluble resin forming the alkaline water-soluble resin unit of the second carboxylic acid-modified nitrile-based copolymer may include a third conjugated diene-based monomer unit, a third ethylenically unsaturated nitrile-based monomer unit, and a third ethylenically unsaturated acid monomer unit.

[0083] According to one embodiment of the present invention, the alkaline water-soluble resin is characterized by including a monomer unit derived from the same monomer or the same series of monomers as the carboxylic acid-modified nitrile-based copolymer, and thus can act as a stabilizer such as an emulsifier during latex polymerization, thereby replacing the emulsifier or reducing the amount used while having excellent polymerization stability, and can simultaneously improve the workability of manufacturing a molded product of a latex composition for dip molding including a second carboxylic acid-modified nitrile-based copolymer latex including the same as well as the mechanical properties such as the fit and tensile properties of the molded product.

[0084] According to one embodiment of the present invention, the third conjugated diene monomer for forming the third conjugated diene monomer unit of the alkaline water-soluble resin may be 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, 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.

[0085] According to one embodiment of the present invention, the third ethylenically unsaturated nitrile monomer forming the third ethylenically unsaturated nitrile monomer unit of the alkaline water-soluble resin may be at least one selected from the group consisting of acrylonitrile, methacrylonitrile, fumaronitrile, α-chloronitrile, and α-cyano ethyl acrylonitrile, and as a specific example, may be acrylonitrile and methacrylonitrile, and as a more specific example, may be acrylonitrile.

[0086] According to one embodiment of the present invention, the third ethylenically unsaturated acid monomer forming the third ethylenically unsaturated acid monomer unit of the alkaline water-soluble resin may be an ethylenically unsaturated monomer containing an acidic group such as a carboxyl group, a sulfonic acid group, or an acid anhydride group, and specific examples thereof 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 at least one 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 specifically, it may be at least one selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, maleic acid, and fumaric acid, and a more specific example may be methacrylic acid. The third 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.

[0087] According to one embodiment of the present invention, the Alari water-soluble resin may include 40 wt% or more and 75 wt% or less of a third conjugated diene monomer unit, 10 wt% or more and 50 wt% or less of a third ethylenically unsaturated nitrile monomer unit, and 10 wt% to 50 wt% of a third ethylenically unsaturated acid monomer unit, and within this range, the glass transition temperature targeted in the present invention can be satisfied, thereby maintaining a balance between wearability and tensile properties.

[0088] According to one embodiment of the present invention, the alkaline water-soluble resin may contain a third conjugated diene monomer unit in an amount of 40 wt% or more, 45 wt% or more, 50 wt% or more, 55 wt% or more, or 60 wt% or more, and may also contain a third conjugated diene monomer unit in an amount of 75 wt% or less, 70 wt% or less, 65 wt% or less, or 60 wt% or less, and within this range, the glass transition temperature may be controlled, and the mechanical properties, such as tensile properties, of a molded article molded from a latex composition for dip molding containing the same may be improved.

[0089] According to one embodiment of the present invention, the alkaline water-soluble resin may contain a third ethylenically unsaturated nitrile monomer unit in an amount of 10 wt% or more, 11 wt% or more, 12 wt% or more, 13 wt% or more, 14 wt% or more, 15 wt% or more, 16 wt% or more, 17 wt% or more, 18 wt% or more, 19 wt% or more, or 20 wt% or more, and further may contain a third ethylenically unsaturated nitrile monomer unit in an amount of 50 wt% or less, 45 wt% or less, 40 wt% or less, 35 wt% or less, 30 wt% or less, 25 wt% or less, 24 wt% or less, 23 wt% or less, 22 wt% or less, 21 wt% or less, or 20 wt% or less, and within this range, the glass transition temperature can be controlled, and the polymerization stability of the latex composition for dip molding containing the same can be improved, and the mechanical properties such as the fit and tensile characteristics of the molded article can be improved at the same time. It can be improved.

[0090] According to one embodiment of the present invention, the alkaline water-soluble resin may contain a third ethylenically unsaturated acid monomer unit in an amount of 10 wt% or more, 11 wt% or more, 12 wt% or more, 13 wt% or more, 14 wt% or more, 15 wt% or more, 16 wt% or more, 17 wt% or more, 18 wt% or more, 19 wt% or more, or 20 wt% or more, and further may contain a third ethylenically unsaturated acid monomer unit in an amount of 50 wt% or less, 45 wt% or less, 40 wt% or less, 35 wt% or less, 30 wt% or less, 25 wt% or less, 24 wt% or less, 23 wt% or less, 22 wt% or less, 21 wt% or less, or 20 wt% or less, and within this range, the glass transition temperature can be controlled, and the mechanical properties, such as the fit and tensile characteristics, of a molded article molded from a latex composition for dip molding containing the same can be improved at the same time.

[0091] According to one embodiment of the present invention, the alkaline water-soluble resin may have a weight average molecular weight of 5,000 g / mol or more and 50,000 g / mol or less. As a specific example, the polymer may have a weight average molecular weight of 5,000 g / mol or more, 5,500 g / mol or more, 6,000 g / mol or more, 6,500 g / mol or more, 7,000 g / mol or more, 7,500 g / mol or more, 8,000 g / mol or more, 8,500 g / mol or more, 9,000 g / mol or more, 9,500 g / mol or more, 10,000 g / mol or more, 10,500 g / mol or more, 11,000 g / mol or more, 11,500 g / mol or more, or 12,000 g / mol or more, and further, 50,000 g / mol or less, 49,000 g / mol or less, 48,000 g / mol or less, 47,000 g / mol or less, 46,000 g / mol or less, 45,000 g / mol or less, 40,000 g / mol or less, 35,000 g / mol or less, 30,000 g / mol or less, 25,000 g / mol or less, 20,000 g / mol or less, 15,000 g / mol or less, 14,000 g / mol or less, 13,000 g / mol or less, or 12,000 g / mol or less.

[0092] According to one embodiment of the present invention, the alkaline water-soluble resin may have a glass transition temperature of -34°C or higher and 33°C or lower. As a specific example, the polymer may have a glass transition temperature of -34°C or higher, -33°C or higher, -32°C or higher, -30°C or higher, -29°C or higher, -28°C or higher, -27°C or higher, -26°C or higher, -25°C or higher, -20°C or higher, -15°C or higher, -14°C or higher, -13°C or higher, or -12°C or higher, and may also have a glass transition temperature of 33°C or lower, 32°C or lower, 31°C or lower, 30°C or lower, 29°C or lower, 28°C or lower, 27°C or lower, 26°C or lower, 25°C or lower, 24°C or lower, 23°C or lower, 22°C or lower, 21°C or lower, 20°C or lower, 15°C or lower, 10°C or lower, 5°C or lower, 0°C or lower, -5°C or lower, -10°C or lower, -11°C or lower, or -12°C or lower. At this time, the glass transition temperature can be controlled from the content of each monomer unit of the polymer, particularly, the content of the conjugated diene monomer unit, and can be measured using a differential scanning calorimeter (DSC).

[0093]

[0094] Latex composition for deep molding

[0095] According to one embodiment of the present invention, the latex composition for dip molding is for performing dip molding, and may contain 1.5 to 2.5 parts by weight of an emulsifier based on 100 parts by weight of the total solid content.

[0096] According to one embodiment of the present invention, the latex composition for dip molding includes the first carboxylic acid-modified nitrile-based copolymer latex and the second carboxylic acid-modified nitrile-based copolymer latex, wherein the first carboxylic acid-modified nitrile-based copolymer latex and the second carboxylic acid-modified nitrile-based copolymer latex may have a weight ratio of 1.00:0.20 to 1.25, 1.00:0.25 to 1.00, 1.0:0.3 to 1.0, or 1.0:0.6 to 1.0. When the weight ratio is within the above range, the emulsifier content of the latex composition for dip molding is controlled as described above, so that the molded product can be manufactured with excellent workability and excellent tensile properties while having a reduced emulsifier content.

[0097]

[0098] According to one embodiment of the present invention, the latex composition for dip molding may include a crosslinking agent composition for controlling pH and inducing crosslinking during dip molding.

[0099] According to one embodiment of the present invention, the crosslinking agent composition may be for forming a crosslinking agent-derived crosslinking portion through a crosslinking reaction for a carboxylic acid-modified nitrile-based copolymer.

[0100] According to one embodiment of the present invention, the crosslinking composition may include a vulcanizing agent and a vulcanizing accelerator, and more specifically, may include a vulcanizing agent, a vulcanizing accelerator, and zinc oxide.

[0101] According to one embodiment of the present invention, the vulcanizing agent is for vulcanizing the latex composition for dip molding, and may be sulfur, and specific examples thereof include sulfur such as powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur, and insoluble sulfur. The content of the vulcanizing agent may be 0.1 to 10 parts by weight, or 1 to 5 parts by weight, based on 100 parts by weight (based on solid content) of the total content of the first and second carboxylic acid-modified nitrile-based copolymer latexes in the latex composition for dip molding, and within this range, excellent crosslinking ability by vulcanization is effective.

[0102] According to one 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-cyclohexylbenzothiasole-2-sulfenamide (CBS, N-cyclohexylbenzothiasole-2-sulfenamide), 2-morpholinothiobenzothiazole (MBS, 2-morpholinothiobenzothiazole), tetramethylthiuram monosulfide (TMTM, tetramethylthiuram monosulfide), tetramethylthiuram disulfide (TMTD, tetramethylthiuram disulfide), zinc diethyldithiocarbamate (ZDEC, zinc diethyldithiocarbamate), zinc di-n-butyldithiocarbamate (ZDBC, zinc The vulcanization accelerator may be at least one selected from the group consisting of di-n-butyldithiocarbamate, diphenylguanidine (DPG), and di-o-tolylguanidine. The content of the vulcanization accelerator may be 0.1 to 10 parts by weight, or 0.5 to 5 parts by weight, based on 100 parts by weight (based on solid content) of the total content of the first and second carboxylic acid-modified nitrile-based copolymer latexes in the latex composition for dip molding, and within this range, excellent crosslinking ability by vulcanization is effective.

[0103] According to one embodiment of the present invention, the zinc oxide may be a crosslinking agent for forming a crosslinked portion through an ionic bond within the carboxylic acid-modified nitrile-based copolymer or between carboxylic acid-modified nitrile-based copolymers by performing an ionic bond with a carboxyl group of the carboxylic acid-modified nitrile-based copolymer in the latex composition for dip molding. The content of the zinc oxide may be 0.1 to 5 parts by weight, or 0.5 to 4 parts by weight, based on 100 parts by weight (based on solid content) of the total content of the first and second carboxylic acid-modified nitrile-based copolymer latexes in the latex composition for dip molding, and within this range, the crosslinking ability is excellent, the latex stability is excellent, and the tensile strength and flexibility of the manufactured product are excellent.

[0104] According to one embodiment of the present invention, the latex composition for dip molding may have a solid content (concentration) of 5 wt% to 40 wt%, 8 wt% to 35 wt%, or 10 wt% to 33 wt%, and within this range, the latex transport efficiency is excellent, and the latex viscosity is prevented from increasing, resulting in excellent storage stability.

[0105] According to one embodiment of the present invention, the latex composition for dip molding may have a pH of 8 to 12, 9 to 11, or 9.5 to 10.5 at 25°C, and within this range, excellent processability and productivity are achieved when manufacturing a dip molded product. The pH of the latex composition for dip molding may be adjusted by adding the pH adjusting agent described above.

[0106] 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, pH regulators, etc., as needed.

[0107]

[0108] Method for producing a latex composition for deep molding

[0109] The present invention provides a method for producing the latex composition for dip molding.

[0110] The method for manufacturing the latex for dip molding according to one embodiment of the present invention includes a step of mixing a first carboxylic acid-modified nitrile copolymer latex including a first conjugated diene monomer unit, a first ethylenically unsaturated nitrile monomer unit, and a first ethylenically unsaturated acid monomer unit, a second carboxylic acid-modified nitrile copolymer including a second conjugated diene monomer unit and a second ethylenically unsaturated nitrile monomer unit, and a second carboxylic acid-modified nitrile copolymer latex including an alkaline water-soluble resin unit, and the second carboxylic acid-modified nitrile copolymer latex may be manufactured by mixing the second conjugated diene monomer, the second ethylenically unsaturated nitrile monomer, and the alkaline water-soluble resin solution and emulsion polymerizing the mixture.

[0111] According to one embodiment of the present invention, the first carboxylic acid-modified nitrile copolymer latex and the second carboxylic acid-modified nitrile copolymer latex may be mixed in a weight ratio of 1.00:0.20 to 1.25, 1.00:0.25 to 1.00, 1.0:0.3 to 1.0, or 1.0:0.6 to 1.0, and within this range, a latex composition for dip molding having excellent workability for manufacturing molded products while reducing the emulsifier content can be obtained.

[0112]

[0113] Meanwhile, the first carboxylic acid-modified nitrile copolymer latex and the second carboxylic acid-modified nitrile copolymer latex may each be manufactured through conventional emulsion polymerization, and are described in more detail below.

[0114] Method for producing a first carboxylic acid-modified nitrile copolymer latex

[0115] According to one embodiment of the present invention, the first carboxylic acid-modified nitrile-based copolymer latex may be manufactured by emulsion polymerizing a first conjugated diene-based monomer, a first ethylenically unsaturated nitrile-based monomer, and a first ethylenically unsaturated acid monomer in a solvent, wherein the amount of each monomer used may be appropriately adjusted to an amount that allows each monomer unit to satisfy the above-described range in the first carboxylic acid-modified nitrile-based copolymer latex.

[0116] According to one embodiment of the present invention, the solvent, the first conjugated diene monomer, the first ethylenically unsaturated nitrile monomer, and the first ethylenically unsaturated acid monomer may be the same as those described above.

[0117] Specifically, the first carboxylic acid-modified nitrile copolymer latex can be produced by emulsion polymerizing 35 to 78 wt% of the first conjugated diene monomer; 20 to 50 wt% of the first ethylenically unsaturated nitrile monomer; and 0.1 to 10 wt% of the first ethylenically unsaturated acid monomer in a solvent.

[0118] According to one embodiment of the present invention, the emulsion polymerization may be carried out in the presence of at least one additive selected from an emulsifier, a molecular weight regulator, and a polymerization initiator, and the emulsifier may be at least one selected from the group consisting of anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants, and as a specific example, may be at least one anionic surfactant selected from the group consisting of alkylbenzene sulfonates, aliphatic sulfonates, higher alcohol sulfate ester salts, α-olefin sulfonates, and alkyl ether sulfate ester salts.

[0119] According to one embodiment of the present invention, in the emulsion polymerization for producing the first carboxylic acid-modified nitrile copolymer latex, the emulsifier can be used in an amount of 1.0 to 5.0 parts by weight based on 100 parts by weight of the total monomer content, and as a specific example, the emulsifier can be introduced in an amount of 1.0 parts by weight or more, 1.5 parts by weight or more, 2.0 parts by weight or more, or 2.5 parts by weight or more, and further, the emulsifier can be introduced in an amount of 5.0 parts by weight or less, 4.5 parts by weight or less, 4.0 parts by weight or less, 3.5 parts by weight or less, 3.0 parts by weight or less, or 2.5 parts by weight or less, and within this range, the polymerization stability can be further improved.

[0120] According to one embodiment of the present invention, the emulsion polymerization for producing the first carboxylic acid-modified nitrile copolymer latex can be carried out in the presence of a molecular weight regulator, and the molecular weight regulator can be at least one selected from the group consisting of 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; and sulfur-containing compounds such as tetraethyl thiuram disulfide, dipentamethylene thiuram disulfide, and diisopropylxanthogen disulfide, and a specific example thereof can be t-dodecyl mercaptan.

[0121] According to one embodiment of the present invention, the emulsion polymerization for producing the first carboxylic acid-modified nitrile copolymer latex can be carried out by adding a molecular weight modifier in an amount of 0.8 parts by weight or more and 8.0 parts by weight or less based on 100 parts by weight of the total monomer content, and for specific examples, the emulsion polymerization can be carried out by adding a content of 0.8 parts by weight or more, 0.9 parts by weight or more, 1.0 parts by weight or more, 1.5 parts by weight or more, 2.0 parts by weight or more, 2.5 parts by weight or more, 3.0 parts by weight or more, or 3.5 parts by weight or more, and further, the emulsion polymerization can be carried out by adding a content of 8.0 parts by weight or less, 7.5 parts by weight or less, 7.0 parts by weight or less, 6.5 parts by weight or less, 6.0 parts by weight or less, 5.5 parts by weight or less, 5.0 parts by weight or less, 4.5 parts by weight or less, 4.0 parts by weight or less, or 3.5 parts by weight or less, and within this range, the molecular weight of the polymer can be adjusted. By appropriately controlling the latex composition, it is possible to prevent the latex stability from deteriorating due to an increase in viscosity, and at the same time, to improve the entanglement between the polymer and the carboxylic acid-modified nitrile copolymer, thereby further improving the mechanical properties, such as tensile properties, of a molded product molded from the latex composition for dip molding.

[0122] According to one embodiment of the present invention, the emulsion polymerization for producing the first carboxylic acid-modified nitrile copolymer latex may be initiated by introducing a polymerization initiator, and the polymerization initiator may be a radical initiator, and specific examples thereof include inorganic peroxides such as sodium persulfate, potassium persulfate, ammonium persulfate, potassium perphosphate, and hydrogen peroxide; organic peroxides such as t-butyl peroxide, cumene hydroperoxide, p-menthane hydroperoxide, di-t-butyl peroxide, t-butylcumyl peroxide, acetyl peroxide, isobutyl peroxide, octanoyl peroxide, dibenzoyl peroxide, 3,5,5-trimethylhexanol peroxide, and t-butyl peroxy isobutyrate; It may be at least one selected from the group consisting of nitrogen compounds such as azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, azobiscyclohexanecarbonitrile, and azobisisobutyric acid methyl, and a specific example thereof may be an inorganic peroxide, and a more specific example thereof may be a persulfate.

[0123] According to one embodiment of the present invention, the emulsion polymerization for producing the first carboxylic acid-modified nitrile copolymer latex can be carried out by adding a polymerization initiator in an amount of 0.01 to 2.0 parts by weight based on 100 parts by weight of the total monomer content, and for specific examples, the polymerization initiator can be added in an amount of 0.01 to 2.0 parts by weight based on 100 parts by weight of the total monomer content, and for specific examples, the polymerization initiator can be added in an amount of 0.01 to 2.0 parts by weight, 0.05 to 2.0 parts by weight, 0.1 to 2.0 parts by weight, 0.2 to 2.0 parts by weight, 0.3 to 2.0 parts by weight, 0.4 to 2.0 parts by weight, 0.5 to 2.0 parts by weight, 0.6 to 2.0 parts by weight, 0.7 to 2.0 parts by weight, 0.8 to 2.0 parts by weight, 0.7 to 2.0 parts by weight, 0.8 to 2.0 parts by weight, 0.9 to 2.0 parts by weight, 0.7 to 2.0 parts by weight, 0.6 ... It can be carried out by adding the amount of less than 1 part by weight, less than 1.2 parts by weight, less than 1.1 parts by weight, or less than 1.0 parts by weight, and the polymerization speed can be maintained at an appropriate level within this range.

[0124] Additionally, according to one embodiment of the present invention, a deodorizing step may be performed to remove unreacted monomers and residual components as needed after the emulsion polymerization.

[0125]

[0126] Method for producing a second carboxylic acid-modified nitrile copolymer latex

[0127] According to one embodiment of the present invention, the second carboxylic acid-modified nitrile-based copolymer latex may be manufactured by emulsion polymerizing a second conjugated diene-based monomer, a second ethylenically unsaturated nitrile-based monomer, and an alkaline-soluble resin solution in a solvent, wherein the amounts of each monomer and the alkaline-soluble resin solution used may be appropriately adjusted to an amount that allows each unit in the second carboxylic acid-modified nitrile-based copolymer latex to satisfy the aforementioned range.

[0128] According to one embodiment of the present invention, the solvent, the second conjugated diene monomer, and the second ethylenically unsaturated nitrile monomer may be the same as those described above.

[0129] Specifically, the second carboxylic acid-modified nitrile copolymer latex can be produced by emulsion polymerizing a second conjugated diene monomer; a second ethylenically unsaturated nitrile monomer; and an alkaline water-soluble resin solution in a solvent, wherein the alkaline water-soluble resin solution can be used in an amount of 5 to 25 parts by weight based on solid content, based on 100 parts by weight of the total amount of the second conjugated diene monomer and the second ethylenically unsaturated nitrile monomer.

[0130] According to one embodiment of the present invention, the alkaline water-soluble resin solution may be introduced in batches together with the second conjugated diene monomer and the second ethylenically unsaturated nitrile monomer before initiation of emulsion polymerization.

[0131] In addition, according to one embodiment of the present invention, the alkaline water-soluble resin solution may be injected at least twice during polymerization before and after the initiation of emulsion polymerization, and as another example, the alkaline water-soluble resin solution may be injected once before the initiation of emulsion polymerization, and twice after the initiation of emulsion polymerization, and the second injection may be continuously injected during a polymerization conversion rate range of 30% to 70%. At this time, when the alkaline water-soluble resin solution is injected in installments, the total injected alkaline water-soluble resin solution may be 5 to 25 parts by weight based on the solid content, based on 100 parts by weight of the total amount of the conjugated diene monomer and the ethylenically unsaturated nitrile monomer.

[0132] According to one embodiment of the present invention, the alkaline water-soluble resin solution is first introduced before the start of emulsion polymerization, and second introduced after the start of emulsion polymerization. The second introduction may be continuously introduced during a polymerization conversion rate range of 30% to 70%, and the alkaline water-soluble resin solution at the first introduction and the alkaline water-soluble resin solution at the second introduction may have a weight ratio of 1:0.2 to 1 based on solid content. Meanwhile, when the alkaline water-soluble resin solution is introduced in portions to perform emulsion polymerization, there is an effect that polymerization stability can be further improved.

[0133] According to one embodiment of the present invention, the polymerization conversion rate may be calculated by collecting a certain amount of sample from a reacting composition at certain time intervals, measuring the content of solids in the sample, and then using the following mathematical formula 1.

[0134] [Mathematical Formula 1]

[0135] Polymerization conversion rate (%) = [(Ms - Mo) / (Mp - M'o)] × 100

[0136] In the above mathematical expression 1, Ms is the weight of the dried copolymer, Mo is the sum of the weights of the emulsifier and the polymerization initiator, Mp is the weight of the 100% polymerized copolymer, and M'o is the sum of the weights of the emulsifier and the polymerization initiator.

[0137] According to one embodiment of the present invention, the alkaline water-soluble resin solution may have a pH of 7.0 to 10.0 at 25°C. As a specific example, the alkaline water-soluble resin solution may have a pH of 7.0 or more, 7.1 or more, 7.2 or more, 7.3 or more, 7.4 or more, 7.5 or more, 7.6 or more, 7.7 or more, 7.8 or more, 7.9 or more, or 8.0 or more, and may also have a pH of 10.0 or less, 9.9 or less, 9.8 or less, 9.7 or less, 9.6 or less, 9.5 or less, 9.4 or less, 9.3 or less, 9.2 or less, 9.1 or less, or 9.0 or less, and within this range, the second carboxylic acid-modified nitrile copolymer latex may function more effectively as a polymerization stabilizer when producing the latex, thereby improving the latex stability.

[0138]

[0139] According to one embodiment of the present invention, the emulsion polymerization may be carried out in the absence of an emulsifier, and, if necessary, may be carried out in the presence of one or more additives selected from an emulsifier, a molecular weight regulator, and a polymerization initiator. The second carboxylic acid-modified nitrile copolymer latex can stably polymerize even in the absence of an emulsifier or in the presence of a reduced emulsifier, since the alkaline water-soluble resin solution can act as a polymerization stabilizer such as an emulsifier.

[0140] According to one embodiment of the present invention, the emulsifier, molecular weight regulator and polymerization initiator may be the same as those described above.

[0141] According to one embodiment of the present invention, when an emulsifier is used in the emulsion polymerization for producing the second carboxylic acid-modified nitrile-based copolymer latex, the emulsifier may be used in an amount of 0.3 to 2.0 parts by weight based on 100 parts by weight of the total solid content of the monomers constituting the second carboxylic acid-modified nitrile-based copolymer, for example, the second conjugated diene-based monomer and the second ethylenically unsaturated nitrile-based monomer or the second carboxylic acid-modified nitrile-based copolymer, and as a specific example, the emulsifier may be introduced in an amount of 0.3 parts by weight or more, 0.4 parts by weight or more, 0.5 parts by weight or more, or 0.6 parts by weight or more, and further, the emulsifier may be introduced in an amount of 2.0 parts by weight or less, 1.8 parts by weight or less, 1.6 parts by weight or less, 1.4 parts by weight or less, 1.2 parts by weight or less, or 1.0 parts by weight or less, and within this range, the polymerization stability is further improved. It can be excellent.

[0142] According to one embodiment of the present invention, the emulsion polymerization for producing the second carboxylic acid-modified nitrile copolymer latex can be carried out by adding a molecular weight modifier in an amount of 0.8 parts by weight or more and 8.0 parts by weight or less based on 100 parts by weight of the total monomer content, and for specific examples, the emulsion polymerization can be carried out by adding a content of 0.8 parts by weight or more, 0.9 parts by weight or more, 1.0 parts by weight or more, 1.5 parts by weight or more, 2.0 parts by weight or more, 2.5 parts by weight or more, 3.0 parts by weight or more, or 3.5 parts by weight or more, and further, the emulsion polymerization can be carried out by adding a content of 8.5 parts by weight or less, 8.0 parts by weight or less, 7.5 parts by weight or less, 7.0 parts by weight or less, 6.5 parts by weight or less, 6.0 parts by weight or less, 5.5 parts by weight or less, 5.0 parts by weight or less, 4.5 parts by weight or less, or 4.0 parts by weight or less, and within this range, the molecular weight of the polymer can be adjusted. By properly adjusting, the latex stability can be prevented from deteriorating due to increased viscosity.

[0143] According to one embodiment of the present invention, the emulsion polymerization for producing the second carboxylic acid-modified nitrile copolymer latex can be carried out by adding a polymerization initiator in an amount of 0.01 to 2.0 parts by weight based on 100 parts by weight of the total monomer content, and for specific examples, it can be carried out by adding a polymerization initiator in an amount of 0.01 to 2.0 parts by weight based on 100 parts by weight of the total monomer content, and for specific examples, it can be carried out by adding a polymerization initiator in an amount of 0.01 to 2.0 parts by weight, 0.05 to 0.1 parts by weight, 0.2 to 0.3 parts by weight, 0.4 to 0.5 parts by weight, 0.6 to 0.7 parts by weight, 0.8 to 0.9 parts by weight, or 1.0 to 1.0 parts by weight, and also, it can be carried out by adding a polymerization initiator in an amount of 2.0 to 1.9 parts by weight, 1.8 to 1.7 parts by weight, 1.6 to 1.5 parts by weight, 1.4 to 1.3 parts by weight or less. It can be carried out by adding the amount of less than 1 part by weight, less than 1.2 parts by weight, less than 1.1 parts by weight, or less than 1.0 parts by weight, and the polymerization speed can be maintained at an appropriate level within this range.

[0144] Additionally, according to one embodiment of the present invention, a deodorizing step may be performed to remove unreacted monomers and residual components as needed after the emulsion polymerization.

[0145]

[0146] Meanwhile, according to one embodiment of the present invention, the alkaline water-soluble resin solution may be manufactured by a manufacturing method including a step (S10) of manufacturing a polymer latex by emulsion polymerizing a third conjugated diene monomer, a third ethylenically unsaturated nitrile monomer, and a third ethylenically unsaturated acid monomer in a solvent; and a step (S20) of adding a pH adjuster to the polymer latex.

[0147] According to one embodiment of the present invention, the solvent, the third conjugated diene monomer, the third ethylenically unsaturated nitrile monomer, and the third ethylenically unsaturated acid monomer may be the same as those described above.

[0148] According to one embodiment of the present invention, the step (S10) is a step for producing a polymer latex, which may be performed by emulsion polymerization, wherein the emulsion polymerization may be performed in the presence of an emulsifier and a molecular weight regulator. In addition, the emulsifier and the molecular weight regulator may be as described above.

[0149] According to one embodiment of the present invention, the emulsion polymerization in step (S10) can be performed by adding an emulsifier in an amount of 1.0 parts by weight or more and 5.0 parts by weight or less based on 100 parts by weight of the total monomer content, and as a specific example, the emulsifier can be added in an amount of 1.0 parts by weight or more, 1.5 parts by weight or more, 2.0 parts by weight or more, or 2.5 parts by weight or more, and further, the emulsifier can be added in an amount of 5.0 parts by weight or less, 4.5 parts by weight or less, 4.0 parts by weight or less, 3.5 parts by weight or less, 3.0 parts by weight or less, or 2.5 parts by weight or less, and within this range, the polymerization stability can be further improved.

[0150] According to one embodiment of the present invention, the emulsion polymerization of the step (S10) can be carried out by adding a molecular weight regulator in an amount of 0.8 parts by weight or more and 8.0 parts by weight or less based on 100 parts by weight of the total monomer content, and for specific examples, it can be carried out by adding a content of 0.8 parts by weight or more, 0.9 parts by weight or more, 1.0 parts by weight or more, 1.5 parts by weight or more, 2.0 parts by weight or more, 2.5 parts by weight or more, 3.0 parts by weight or more, or 3.5 parts by weight or more, and further, it can be carried out by adding a content of 8.0 parts by weight or less, 7.5 parts by weight or less, 7.0 parts by weight or less, 6.5 parts by weight or less, 6.0 parts by weight or less, 5.5 parts by weight or less, 5.0 parts by weight or less, 4.5 parts by weight or less, 4.0 parts by weight or less, or 3.5 parts by weight or less, and by appropriately adjusting the molecular weight of the polymer within this range, the latex stability is improved due to an increase in viscosity. It can prevent degradation.

[0151] According to one embodiment of the present invention, the emulsion polymerization in step (S10) may be initiated by introducing a polymerization initiator, and the polymerization initiator may be a radical initiator. In this case, the polymerization initiator may be as described above.

[0152] According to one embodiment of the present invention, the emulsion polymerization of the step (S10) may be carried out by adding a polymerization initiator in an amount of 0.01 parts by weight or more and 2.0 parts by weight or less based on 100 parts by weight of the total monomer content, and as a specific example, the polymerization initiator may be added in an amount of 0.01 parts by weight or more, 0.05 parts by weight or more, 0.1 parts by weight or more, 0.2 parts by weight or more, 0.3 parts by weight or more, 0.4 parts by weight or more, 0.5 parts by weight or more, 0.6 parts by weight or more, 0.7 parts by weight or more, 0.8 parts by weight or more, 0.9 parts by weight or more, or 1.0 parts by weight or more, and further, 2.0 parts by weight or less, 1.9 parts by weight or less, 1.8 parts by weight or less, 1.7 parts by weight or less, 1.6 parts by weight or less, 1.5 parts by weight or less, 1.4 parts by weight or less, 1.3 parts by weight or less, 1.2 parts by weight or less, It can be carried out by adding a content of 1.1 parts by weight or less, or 1.0 parts by weight or less, and the polymerization speed can be maintained at an appropriate level within this range.

[0153] According to one embodiment of the present invention, the step (S20) is a step for adjusting the pH of the polymer latex manufactured in the step (S10), whereby the pH of the alkaline water-soluble resin solution finally obtained at 25°C can be adjusted to 7.0 to 10.0. At this time, the pH adjusting agent may be a basic compound, and a specific example may be an alkaline hydroxide salt and / or an aqueous ammonia solution, and a more specific example may be sodium hydroxide or potassium hydroxide.

[0154] In addition, according to one embodiment of the present invention, a deodorizing step for removing unreacted monomers and residual components may be included as needed after the step (S20).

[0155]

[0156] molded products

[0157] The present invention provides a dip-molded product manufactured by dip-molding the latex composition for dip-molding.

[0158] According to one embodiment of the present invention, the molded article may include a layer derived from a latex composition for dip molding. The molded article may be a dip molded article manufactured by dip molding the latex composition for dip molding, and may be a molded article including a layer derived from a latex composition for dip molding formed from the latex composition for dip molding by dip molding. A molded article manufacturing method for molding the molded article may include a step of immersing the latex composition for dip molding by a direct immersion method, an anodic adhesion immersion method, a Teague adhesion immersion method, or the like, and as a specific example, it may be performed by an anodic adhesion immersion method, in which case there is an advantage of being able to obtain a dip molded article having a uniform thickness.

[0159] According to one embodiment of the present invention, the method for manufacturing a molded product may include a step of attaching a coagulant to a dip mold (S100); a step of immersing the dip mold with the coagulant attached into a latex composition for dip molding to form a layer derived from the latex composition for dip molding, i.e., a dip molding layer (S200); and a step of heating the dip molding layer to crosslink the latex composition for dip molding (S300).

[0160] According to one embodiment of the present invention, the step (S100) is a step of immersing the dip mold in a coagulant solution to attach the coagulant to the surface of the dip mold in order to form a coagulant in the dip mold, wherein the coagulant solution is a solution in which the coagulant is dissolved in water, alcohol, or a mixture thereof, and the content of the coagulant in the coagulant solution may be 5 wt% to 75 wt%, 5 wt% to 50 wt%, or 10 wt% to 40 wt% based on the total content of the coagulant solution. The coagulant may be at least one selected from the group consisting of metal halides such as barium chloride, calcium chloride, magnesium chloride, zinc chloride, and aluminum chloride; nitrates such as barium nitrate, calcium nitrate, and zinc nitrate; acetates such as barium acetate, calcium acetate, and zinc acetate; and sulfates such as calcium sulfate, magnesium sulfate, and aluminum sulfate, and a specific example thereof may be calcium chloride or calcium nitrate. In addition, according to one embodiment of the present invention, the step (S100) may further include a step of immersing the dip mold in a coagulant solution for 5 seconds or more, taking it out, and drying it at 50°C to 150°C to attach a coagulant to the dip mold.

[0161] According to one embodiment of the present invention, the step (S200) may be a step of immersing a dip mold having a coagulant attached thereto in a latex composition for dip molding according to the present invention to form a dip molding layer, and taking it out to form a dip molding layer in the dip molding mold. In addition, according to one embodiment of the present invention, in the step (S200), in order to form a dip molding layer in the dip molding mold, the immersion may be performed for 5 seconds or longer.

[0162] According to one embodiment of the present invention, the step (S300) may be a step of heating a dip molding layer formed in a dip mold to evaporate a liquid component and crosslinking and hardening the latex composition for dip molding in order to obtain a dip molded product. At this time, when the latex composition for dip molding according to the present invention is used, crosslinking by vulcanization and / or ionic bonding of the crosslinking agent composition included in the latex composition for dip molding may be performed. In addition, according to one embodiment of the present invention, the heating may be performed by first heating at 70°C to 150°C for 1 minute to 10 minutes, and then second heating at 100°C to 180°C for 5 minutes to 30 minutes. At this time, after the first heating and before performing the second heating, a leaching process by soaking in water or warm water for 10 seconds to 10 minutes may be further included.

[0163] According to one embodiment of the present invention, the molded product may be a glove, such as a surgical glove, an examination glove, an industrial glove, or a household glove, a condom, a catheter, or a health care product.

[0164]

[0165] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0166] Examples and Comparative Examples

[0167] Example 1

[0168] <Preparation of the first carboxylic acid-modified nitrile copolymer latex>

[0169] A 10 L high-pressure reactor equipped with a thermometer, a cooler, a nitrogen gas inlet, and an inlet for continuously introducing monomers, emulsifiers, and polymerization initiators was used. After the 10 L high-pressure reactor was replaced with nitrogen, 27 wt% of acrylonitrile, 67 wt% of 1,3-butadiene, and 6 wt% of methacrylic acid, and 100 wt% of a monomer mixture composed of the acrylonitrile, 1,3-butadiene, and methacrylic acid were introduced, 2.8 wt% of sodium alkylbenzene sulfonate as an emulsifier, 0.7 wt% of t-dodecyl mercaptan as a molecular weight regulator, and 150 wt% of ion-exchanged water were introduced, and the internal temperature of the reactor was raised to 40°C. After the temperature rise was completed, 1.0 part by weight of potassium persulfate as a polymerization initiator was added to initiate polymerization, and when the polymerization conversion rate reached 95%, 1.0 part by weight of sodium dimethyldithiocarbamate was added to terminate the polymerization, thereby producing a polymer latex including a polymer. Subsequently, potassium hydroxide was added to the polymer latex to adjust the pH at 25°C to 8.5, and a deodorization process was performed to remove unreacted monomers, thereby obtaining a first carboxylic acid-modified nitrile-based copolymer latex.

[0170]

[0171] <Manufacture of a second carboxylic acid-modified nitrile copolymer latex>

[0172] 1) Preparation of alkaline water-soluble resin solution

[0173] A 10 L high-pressure reactor equipped with a thermometer, a cooler, a nitrogen gas inlet, and an inlet for continuously introducing monomers, emulsifiers, and polymerization initiators was used. After the 10 L high-pressure reactor was replaced with nitrogen, 20 wt % of acrylonitrile, 60 wt % of 1,3-butadiene, and 20 wt % of methacrylic acid and 100 wt % of a monomer mixture composed of the acrylonitrile, 1,3-butadiene, and methacrylic acid were introduced, 2.5 wt parts of sodium alkylbenzene sulfonate as an emulsifier, 4.0 wt parts of t-dodecyl mercaptan as a molecular weight regulator, and 250 wt parts of ion-exchanged water were introduced, and the internal temperature of the reactor was raised to 40°C. After the temperature rise was completed, 1.0 part by weight of potassium persulfate was added as a polymerization initiator to initiate polymerization, and when the polymerization conversion rate was 95%, potassium hydroxide was added to adjust the pH at 25°C to 9.5, and a deodorization process was performed to remove unreacted monomers, thereby obtaining an alkaline water-soluble resin solution.

[0174]

[0175] 2) Preparation of second carboxylic acid modified nitrile copolymer latex

[0176] A 10 L high-pressure reactor equipped with a thermometer, a cooler, a nitrogen gas inlet, and an inlet for continuously introducing monomers, emulsifiers, and polymerization initiators was used. After the 10 L high-pressure reactor was replaced with nitrogen, 15 parts by weight (based on solid content) of the alkaline water-soluble resin solution prepared above based on 30 wt% of acrylonitrile, 70 wt% of 1,3-butadiene, and 100 parts by weight of the monomer mixture composed of the acrylonitrile and 1,3-butadiene, 0.7 parts by weight of t-dodecyl mercaptan as a molecular weight regulator, and 150 parts by weight of ion-exchanged water were introduced, and the internal temperature of the reactor was raised to 40°C. After the temperature was completed, 1.0 part by weight of potassium peroxide was added as a polymerization initiator to initiate polymerization, and 5 parts by weight (based on solid content) of the alkaline water-soluble resin solution was continuously added during the polymerization conversion range of 30% to 70%. When the polymerization conversion reached 95%, 1.0 part by weight of sodium dimethyldithiocarbamate was added to stop the polymerization, thereby producing a polymer latex including the polymer. Subsequently, a deodorization process was performed to remove unreacted monomers, thereby obtaining a second carboxylic acid-modified nitrile-based copolymer latex.

[0177]

[0178] <Manufacture of latex composition for deep molding>

[0179] 1.2 parts by weight of a 3 wt% potassium hydroxide aqueous solution, 1.2 parts by weight of a vulcanizing agent (Akron dispersions, BOSTEX 378), 0.7 parts by weight of a vulcanizing accelerator (Akron dispersions, BOSTEX 497B), 1.0 parts by weight of zinc oxide (Akron dispersions, BOSTEX 422), 1.0 parts by weight of titanium dioxide (Akron dispersions, BOSTEX 497D), and double-distilled water were added to 100 parts by weight (based on solid content) of the first carboxylic acid-modified nitrile copolymer latex and the second carboxylic acid-modified nitrile copolymer latex manufactured above, thereby preparing a latex composition for dip molding having a solid content of 25 wt%, and ammonia was added to prepare a latex composition for dip molding having a pH of 10 at 25°C. At this time, the first carboxylic acid-modified nitrile copolymer latex and the second carboxylic acid-modified nitrile copolymer latex were mixed at a weight ratio of 80:20 (4:1).

[0180]

[0181] <Manufacturing of deep molded products>

[0182] A coagulant solution was prepared by mixing 18 wt% calcium nitrate, 81.9 wt% water, and 0.1 wt% wetting agent (Huntsman Corporation, Australia, product name Teric 320). A hand-shaped ceramic mold was immersed in the coagulant solution for 10 seconds, removed, and dried at 80°C for 4 minutes to apply the coagulant to the hand-shaped mold.

[0183] Next, a hand-shaped mold coated with a coagulant was immersed in the obtained dip-molding latex composition for 10 seconds, taken out, dried at 80°C for 2 minutes, and leached by immersing in water for 30 seconds. Again, the mold was crosslinked at 110°C for 20 minutes, and the crosslinked dip-molding layer was peeled off from the hand-shaped mold to obtain a glove-shaped dip-molded product.

[0184]

[0185] Example 2

[0186] In the above Example 1, except that the first carboxylic acid-modified nitrile copolymer latex and the second carboxylic acid-modified nitrile copolymer latex were mixed in a weight ratio of 70:30 (about 2.3:1) when preparing the latex composition for dip molding, the same procedure as Example 1 was performed to prepare a latex composition for dip molding, and a dip molded product was obtained using the same.

[0187]

[0188] Example 3

[0189] In the above Example 1, except that the first carboxylic acid-modified nitrile copolymer latex and the second carboxylic acid-modified nitrile copolymer latex were mixed in a weight ratio of 60:40 (1.5:1) when preparing the latex composition for dip molding, the same procedure as Example 1 was performed to prepare a latex composition for dip molding, and a dip molded product was obtained using the same.

[0190]

[0191] Example 4

[0192] In the above Example 1, except that the first carboxylic acid-modified nitrile copolymer latex and the second carboxylic acid-modified nitrile copolymer latex were mixed in a weight ratio of 50:50 (1:1) when preparing the latex composition for dip molding, the same procedure as Example 1 was performed to prepare a latex composition for dip molding, and a dip molded product was obtained using the same.

[0193]

[0194] Example 5

[0195] In the above Example 1, a latex composition for dip molding was manufactured in the same manner as Example 1, except that the first carboxylic acid-modified nitrile copolymer latex and the second carboxylic acid-modified nitrile copolymer latex were mixed in a weight ratio of 90:10 (9:1) when manufacturing a latex composition for dip molding, and a dip molded product was obtained using the same.

[0196]

[0197] Example 6

[0198] In the above Example 1, except that the first carboxylic acid-modified nitrile copolymer latex and the second carboxylic acid-modified nitrile copolymer latex were mixed in a weight ratio of 40:60 (1:1.5) when preparing the latex composition for dip molding, the same procedure as Example 1 was performed to prepare a latex composition for dip molding, and a dip molded product was obtained using the same.

[0199]

[0200] Comparative Example 1

[0201] In the above Example 1, except that 100 parts by weight of the first carboxylic acid-modified nitrile copolymer latex was used instead of mixing the second carboxylic acid-modified nitrile copolymer latex when preparing the latex composition for dip molding, a latex composition for dip molding was prepared in the same manner as Example 1, and a dip molded product was obtained using the same.

[0202]

[0203] Comparative Example 2

[0204] In the above Example 1, when preparing a latex composition for dip molding, 100 parts by weight of the first carboxylic acid-modified nitrile-based copolymer latex was used without mixing the second carboxylic acid-modified nitrile-based copolymer latex, and when preparing the first carboxylic acid-modified nitrile-based copolymer latex, 2.2 parts by weight of an emulsifier was used, and a latex composition for dip molding was prepared in the same manner as in Example 1, and a dip molded product was obtained using the same.

[0205]

[0206] Comparative Example 3

[0207] <Manufacture of carboxylic acid-modified nitrile copolymer latex>

[0208] A 10 L high-pressure reactor equipped with a thermometer, a cooler, a nitrogen gas inlet, and an inlet for continuously introducing monomers, emulsifiers, and polymerization initiators was used. After the 10 L high-pressure reactor was replaced with nitrogen, 27 wt% of acrylonitrile, 67 wt% of 1,3-butadiene, and 6 wt% of methacrylic acid, and 100 wt% of a monomer mixture composed of the acrylonitrile, 1,3-butadiene, and methacrylic acid were introduced, 2.8 wt% of sodium alkylbenzene sulfonate as an emulsifier, 0.7 wt% of t-dodecyl mercaptan as a molecular weight regulator, and 150 wt% of ion-exchanged water were introduced, and the internal temperature of the reactor was raised to 40°C. After the temperature rise was completed, 1.0 part by weight of potassium persulfate as a polymerization initiator was added to initiate polymerization, and when the polymerization conversion rate reached 95%, 1.0 part by weight of sodium dimethyldithiocarbamate was added to terminate the polymerization, thereby producing a polymer latex containing the polymer. Subsequently, potassium hydroxide was added to the polymer latex to adjust the pH at 25°C to 8.5, and a deodorization process was performed to remove unreacted monomers, thereby obtaining a carboxylic acid-modified nitrile-based copolymer latex.

[0209]

[0210] <Preparation of alkaline water-soluble resin solution>

[0211] A 10 L high-pressure reactor equipped with a thermometer, a cooler, a nitrogen gas inlet, and an inlet for continuously introducing monomers, emulsifiers, and polymerization initiators was used. After the 10 L high-pressure reactor was replaced with nitrogen, 20 wt % of acrylonitrile, 60 wt % of 1,3-butadiene, and 20 wt % of methacrylic acid and 100 wt % of a monomer mixture composed of the acrylonitrile, 1,3-butadiene, and methacrylic acid were introduced, 2.5 wt parts of sodium alkylbenzene sulfonate as an emulsifier, 4.0 wt parts of t-dodecyl mercaptan as a molecular weight regulator, and 250 wt parts of ion-exchanged water were introduced, and the internal temperature of the reactor was raised to 40°C. After the temperature rise was completed, 1.0 part by weight of potassium persulfate was added as a polymerization initiator to initiate polymerization, and when the polymerization conversion rate was 95%, potassium hydroxide was added to adjust the pH at 25°C to 9.5, and a deodorization process was performed to remove unreacted monomers, thereby obtaining an alkaline water-soluble resin solution.

[0212]

[0213] <Manufacture of latex composition for deep molding>

[0214] 100 parts by weight (based on solid content) of the carboxylic acid-modified nitrile copolymer latex prepared above was added with 5 parts by weight of an alkaline water-soluble resin solution, 1.2 parts by weight of a 3 wt% concentrated potassium hydroxide aqueous solution, 1.2 parts by weight of a vulcanizing agent (Akron dispersions, BOSTEX 378), 0.7 parts by weight of a vulcanizing accelerator (Akron dispersions, BOSTEX 497B), 1.0 parts by weight of zinc oxide (Akron dispersions, BOSTEX 422), 1.0 parts by weight of titanium dioxide (Akron dispersions, BOSTEX 497D), and double-distilled water to prepare a latex composition for dip molding having a solid content of 25 wt%, and ammonia was added to prepare a latex composition for dip molding having a pH of 10 at 25°C. In addition, a dip molded product was obtained by performing the same procedure as in Example 1 using the same.

[0215]

[0216] Comparative Example 4

[0217] In the above Comparative Example 3, a latex composition for dip molding was prepared in the same manner as in Comparative Example 3, except that 20 parts by weight of an alkaline water-soluble resin was mixed with 100 parts by weight of a carboxylic acid-modified nitrile copolymer latex when preparing a latex composition for dip molding, and a dip molded product was obtained using the latex composition.

[0218]

[0219] Experimental example

[0220] Experimental Example 1

[0221] The latex stability and total emulsifier content of the latex compositions for dip molding prepared in Examples 1 to 6 and Comparative Examples 1 to 4 were measured, and the results are shown in Table 1 below.

[0222] (1) Latex stability

[0223] Latex stability was confirmed through total coagulant content and reactor scale generation.

[0224] The total coagulum content was determined by passing each composition through a #200 mesh sieve and measuring the weight of the filtered coagulum. A lower weight indicates better latex stability.

[0225] The amount of reactor scale was evaluated by scoring the amount of scale generated in the reactor after polymerization was completed using a 10-point scale system, with a higher score indicating better results. A completely clean reaction was given 10 points, a fine band at the reaction interface was given 9 points, scale throughout the impeller was given 5 points, scale that was severe enough to make subsequent polymerization difficult was given 2 points, and a complete breakdown of latex stability was given 0 points.

[0226]

[0227] (2) Total emulsifier content

[0228] The total emulsifier content is expressed as the sum of the total emulsifier content added until the latex composition for dip molding is manufactured.

[0229]

[0230] As shown in Table 1 above, it can be confirmed that Examples 1 to 6 have a total coagulant content and a reactor scale amount that are lower or similar to those of the Comparative Examples even though they have a reduced emulsifier content. Specifically, Examples 1 to 6 have an emulsifier content that is reduced by about 50% to 90% compared to Comparative Example 1, which is a latex composition for dip molding containing only the first carboxylic acid-modified nitrile-based copolymer latex, while showing an equivalent or higher level of latex stability. In addition, it was confirmed that the latex stability was significantly improved with a reduced or similar emulsifier content compared to Comparative Example 2, which is a latex composition for dip molding containing only the carboxylic acid-modified nitrile-based copolymer latex prepared with a reduced amount of emulsifier.

[0231] In addition, Comparative Examples 3 and 4, which are latex compositions for dip molding prepared by mixing an alkaline water-soluble resin solution with a carboxylic acid-modified nitrile copolymer latex, had an increased emulsifier content of about 10% to 200% compared to the examples, but the latex stability was the same or only slightly improved.

[0232]

[0233] Experimental Example 2

[0234] The dip molding workability of the latex compositions for dip molding manufactured in Examples 1 to 6 and Comparative Examples 1 to 4 and the tensile strength, elongation, 500% modulus, and degree of foaming of the dip molded products were measured, and the results are shown in Table 2 below.

[0235] (1) Deep forming workability

[0236] Deep forming workability was evaluated by syneresis and webbing.

[0237] The dripping phenomenon was measured by the time (in seconds) for water droplets to drip when the film was dried in an 80°C oven after applying a CaNO3 solution to a cylindrical ceramic mold and then drying it, and dipping it in each latex composition for dip molding. The longer the time (the longer the elapsed time), the better.

[0238] Webbing was measured by inserting a triangular ring into each latex composition for deep molding and then removing it, and the time (in seconds) for the bubble film formed on the ring to burst was measured. The shorter the time (the shorter the elapsed time), the better.

[0239]

[0240] (2) Tensile strength (MPa), elongation (%) and 500% modulus (MPa)

[0241] Tensile strength was measured by manufacturing dumbbell-shaped test specimens using each deep-molded product in accordance with ASTM D-412. Using these test specimens, a UTM (Universal Testing Machine) device (Instron, Model: 4466) was used in accordance with ASTM D638 to pull the specimen at a crosshead speed of 500 mm / min, and the point where the specimen breaks was measured. The tensile strength was calculated according to the following mathematical equation 2, and then converted to MPa (1 MPa = 0.10197 kgf / mm). 2 ) was performed. At this time, the higher the calculated tensile strength, the better the tensile properties.

[0242] [Equation 2]

[0243] Tensile strength (kgf / mm) 2 ) = load value (kgf) / (thickness (mm) × width (mm))

[0244] The elongation was calculated according to ASTM D638 using a test piece manufactured for the measurement of the above tensile strength, using a UTM (Universal Testing Machine) device (manufactured by Instron, model number: 4466) at a crosshead speed of 500 mm / min, and the point where the test piece breaks was measured, and the elongation was calculated according to the following mathematical equation 3. At this time, the higher the calculated elongation, the better the tensile properties.

[0245] [Equation 3]

[0246] Elongation (%) = (length of specimen after elongation / length of specimen before elongation) × 100

[0247] The 500% modulus was measured using a test piece manufactured for the above tensile strength measurement in accordance with ASTM D638, using a Universal Testing Machine (UTM) (Instron, Model: 4466) at a crosshead speed of 500 mm / min, and the 500% modulus, which is the tensile strength when the test piece is stretched 5 times its original length before being pulled, was measured. At this time, the lower the measured 500% modulus, the softer and more comfortable it is to wear.

[0248]

[0249] (3) Degree of foaming (%)

[0250] After dropping water droplets on each deep-molded product eight times, they were rubbed together for 10 seconds to generate foam, and immediately after, a photograph was taken to obtain an image. Then, the foam area and the total area of ​​the molded product were obtained using the Image J program and calculated using the following mathematical formula 4. A smaller value indicates better performance.

[0251] [Equation 4]

[0252] Foaming rate (%) = [Foam area / Total molded product area] × 100

[0253]

[0254] As shown in Table 2 above, it was confirmed that the deep-molded products of Examples 1 to 6 had tensile properties that were at least as good as those of Comparative Examples 1 to 4, while workability was significantly improved and bubble generation was greatly reduced.

Claims

1. A first carboxylic acid-modified nitrile copolymer latex comprising a first conjugated diene monomer unit; a first ethylenically unsaturated nitrile monomer unit; and a first carboxylic acid-modified nitrile copolymer comprising a first ethylenically unsaturated acid monomer unit; and A second carboxylic acid-modified nitrile copolymer comprising a second conjugated diene monomer unit; and a second ethylenically unsaturated nitrile monomer unit; and a second carboxylic acid-modified nitrile copolymer latex comprising an alkaline water-soluble resin unit; A latex composition for dip molding, wherein the alkaline water-soluble resin comprises a third conjugated diene monomer unit, a third ethylenically unsaturated nitrile monomer unit, and a third ethylenically unsaturated acid monomer unit.

2. In paragraph 1, A latex composition for dip molding, wherein the first carboxylic acid-modified nitrile copolymer latex and the second carboxylic acid-modified nitrile copolymer latex have a weight ratio of 1.00:0.20 to 1.

25.

3. In paragraph 1, A latex composition for dip molding, wherein the first carboxylic acid-modified nitrile copolymer comprises 35 to 78 wt% of a first conjugated diene monomer unit; 20 to 50 wt% of a first ethylenically unsaturated nitrile monomer unit; and 0.1 to 10 wt% of a first ethylenically unsaturated acid monomer unit.

4. In paragraph 1, A latex composition for dip molding, wherein the second carboxylic acid-modified nitrile copolymer comprises 60 to 80 wt% of a second conjugated diene monomer unit; and 20 to 40 wt% of a second ethylenically unsaturated nitrile monomer unit.

5. In paragraph 1, A latex composition for dip molding, wherein the second carboxylic acid-modified nitrile copolymer latex contains 5 to 25 parts by weight of an alkaline water-soluble resin unit based on 100 parts by weight of the second carboxylic acid-modified nitrile copolymer.

6. In paragraph 1, A latex composition for dip molding, wherein the alkaline water-soluble resin comprises 40 to 75 wt% of a third conjugated diene monomer unit; 10 to 50 wt% of a third ethylenically unsaturated nitrile monomer unit; and 10 to 50 wt% of a third ethylenically unsaturated acid monomer unit.

7. In paragraph 1, The above second carboxylic acid modified nitrile copolymer latex has a micelle form, The above micelles are formed from alkaline water-soluble resin units, A latex composition for dip molding comprising a second carboxylic acid-modified nitrile copolymer inside the micelle.

8. In paragraph 1, A latex composition for dip molding, comprising 1.5 to 2.5 parts by weight of an emulsifier per 100 parts by weight of the total solid content.

9. A step of mixing a first carboxylic acid-modified nitrile copolymer latex and a second carboxylic acid-modified nitrile copolymer latex, The above first carboxylic acid modified nitrile copolymer latex includes a first carboxylic acid modified nitrile copolymer including a first conjugated diene monomer unit, a first ethylenically unsaturated nitrile monomer unit, and a first ethylenically unsaturated acid monomer unit, The above second carboxylic acid modified nitrile copolymer latex includes a second carboxylic acid modified nitrile copolymer including a second conjugated diene monomer unit and a second ethylenically unsaturated nitrile monomer unit, and an alkaline water-soluble resin unit. A method for producing a latex composition for dip molding, wherein the second carboxylic acid-modified nitrile copolymer latex is produced by mixing a second conjugated diene monomer, a second ethylenically unsaturated nitrile monomer, and an alkaline water-soluble resin solution and subjecting the mixture to emulsion polymerization.

10. In paragraph 9 A method for producing a latex composition for dip molding, wherein the first carboxylic acid-modified nitrile copolymer latex and the second carboxylic acid-modified nitrile copolymer latex are mixed in a weight ratio of 1.00:0.20 to 1.

25.

11. In paragraph 9, A method for producing a latex composition for dip molding, wherein the alkaline water-soluble resin solution is used in an amount of 5 to 25 parts by weight based on solid content, based on 100 parts by weight of the total amount of the second conjugated diene monomer and the second ethylenically unsaturated nitrile monomer.

12. In paragraph 9, A method for producing a latex composition for dip molding, wherein the above alkaline water-soluble resin solution is injected in at least two portions before and after the initiation of emulsion polymerization.

13. In paragraph 9, The above alkaline water-soluble resin solution is first injected before the start of emulsion polymerization, and second injected after the start of emulsion polymerization. A method for manufacturing a latex composition for deep molding, wherein the above secondary injection is continuously injected during a polymerization conversion rate range of 30% to 70%.

14. In paragraph 13, A method for manufacturing a latex composition for dip molding, wherein the alkaline water-soluble resin solution in the first injection and the alkaline water-soluble resin solution in the second injection have a weight ratio of 1:0.2 to 1 based on solid content.

15. In paragraph 9, The above alkaline water-soluble resin solution comprises a step of producing a polymer latex by emulsifying a third conjugated diene monomer, a third ethylenically unsaturated nitrile monomer, and a third ethylenically unsaturated acid monomer in a solvent; and A method for producing a latex composition for dip molding, the method comprising a step of adding a pH regulator to the polymer latex.

16. In paragraph 9, A method for producing a latex composition for dip molding, wherein the alkaline water-soluble resin solution has a pH of 7.0 to 10.0 at 25°C.

17. In paragraph 9, A method for producing a latex composition for dip molding, wherein the first carboxylic acid-modified nitrile copolymer latex is produced by emulsion polymerizing a first conjugated diene monomer; a first ethylenically unsaturated nitrile monomer; and a first ethylenically unsaturated acid monomer in a solvent.

18. A molded product comprising a layer derived from a latex composition for deep molding according to Article 1.

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