Latex composition for dip molding, preparation method therefor, and molded article

Abstract

The present invention relates to a latex composition for dip molding having excellent latex stability and reduced foaming, a preparation method therefor, and a molded article molded therefrom with improved wearing comfort. The present disclosure provides a latex composition for dip molding, a preparation method therefor, and a molded article molded therefrom, the latex composition for dip molding 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, wherein the first carboxylic acid-modified nitrile-based copolymer latex and the second carboxylic acid-modified nitrile-based copolymer latex have a weight ratio of 1: 0.6 to 1.5, based on the solid content of each latex.

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. 10-2024-0050163, filed April 15, 2024, the entire disclosure of which is incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a latex composition for deep molding having excellent latex stability and reduced foaming, a method for producing the same, and a molded product molded therefrom having improved wearing comfort.

[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 can provide a molded product having latex stability and improved surface properties 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 and surface properties and suppressed foaming by being 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 the first ethylenically unsaturated acid monomer unit; and a second carboxylic acid-modified nitrile copolymer latex comprising a second conjugated diene monomer unit; a second ethylenically unsaturated nitrile monomer unit; a second carboxylic acid-modified nitrile copolymer comprising the second ethylenically unsaturated acid monomer unit and a reactive emulsifier unit; wherein the first carboxylic acid-modified nitrile copolymer latex and the second carboxylic acid-modified nitrile copolymer latex have a weight ratio of 1:0.6 to 1.5 based on the solid content of each latex.

[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 1:0.6 to 1 based on the solid content of each latex in (1).

[0023] (3) The present invention provides a latex composition for dip molding, wherein in (1) or (2), the first carboxylic acid-modified nitrile copolymer comprises 40 to 75 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 3 to 5 wt% of a reactive emulsifier 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 copolymer comprises 35 to 75 wt% of a second conjugated diene monomer unit; 20 to 50 wt% of a second ethylenically unsaturated nitrile monomer unit; 0.1 to 10 wt% of a second ethylenically unsaturated acid monomer unit; and 3 to 5 wt% of a reactive emulsifier unit in any one of the above (1) to (4).

[0026] (6) The present invention provides a latex composition for dip molding, wherein in any one of the above (1) to (5), the reactive emulsifier is at least one selected from the group consisting of sodium 2-methyl-2-propene-1-sulfonate, sodium allyloxy hydroxypropyl sulfonate, sodium 2-hydroxy-3-(methacryloyloxy)propane-1 sulfonate, sodium 11-methacryloyl undecan-1-yl sulfate, and sodium 11-crodonoyl undetan-1-yl sulfate.

[0027] (7) The present invention provides a method for producing a latex composition for dip molding according to any one of (1) to (6), comprising the step of mixing 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; a second ethylenically unsaturated nitrile monomer unit; a second ethylenically unsaturated acid monomer unit and a reactive emulsifier unit, in a weight ratio of 1:0.6 to 1.5 based on the solid content of each latex.

[0028] (8) The present invention provides a method for producing a latex composition for dip molding, wherein, in the above (7), the first carboxylic acid-modified nitrile copolymer latex and the second carboxylic acid-modified nitrile copolymer latex are mixed in a weight ratio of 1:0.6 to 1.0 based on the solid content of each latex.

[0029] (9) The present invention provides a method for producing a latex composition for dip molding, wherein the first carboxylic acid-modified nitrile copolymer latex according to (7) or (8) 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.

[0030] (10) The present invention provides a method for producing a latex composition for dip molding, wherein the second carboxylic acid-modified nitrile copolymer latex is produced by including a step (S1) of introducing a reactive emulsifier and a second ethylenically unsaturated acid monomer into a reactor and initiating polymerization to produce a first polymer latex including a first polymer; and a step (S2) of introducing a second conjugated diene monomer, a second ethylenically unsaturated nitrile monomer, and a second ethylenically unsaturated acid monomer into the first polymer latex and polymerizing the second carboxylic acid-modified nitrile copolymer latex in any one of the above (7) to (9).

[0031] (11) The present invention provides a method for producing a latex composition for dip molding, wherein, in the above (10), the reactive emulsifier is added in an amount of 3 to 5 wt% based on 100 wt% of the total polymerization reactant, and the polymerization reactant includes a second conjugated diene monomer, a second ethylenically unsaturated nitrile monomer, a second ethylenically unsaturated acid monomer, and a reactive emulsifier.

[0032] (12) The present invention provides a method for producing a latex composition for dip molding, wherein in any one of the above (7) to (11), the reactive emulsifier is at least one selected from the group consisting of sodium 2-methyl-2-propene-1-sulfonate, sodium allyloxy hydroxypropyl sulfonate, sodium 2-hydroxy-3-(methacryloyloxy)propane-1 sulfonate, sodium 11-methacryloyl undecan-1-yl sulfate, and sodium 11-crodonoyl undetan-1-yl sulfate.

[0033] (13) 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 (6) above.

[0034]

[0035] 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 a second carboxylic acid-modified nitrile copolymer comprising a reactive emulsifier unit, thereby having a reduced emulsifier content while exhibiting excellent latex stability and workability in manufacturing molded products.

[0036] In addition, a molded product according to the present invention can be molded from the latex composition for deep molding, and thus can have less foaming and excellent surface properties and tensile properties.

[0037]

[0038] Hereinafter, the present invention will be described in more detail to help understand the present invention.

[0039] 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.

[0040] Definition of Terms

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046]

[0047] Latex composition for deep molding

[0048] 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.

[0049] According to one embodiment of the present invention, the latex composition for dip molding includes 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 the first ethylenically unsaturated acid monomer unit; and a second carboxylic acid-modified nitrile copolymer latex comprising a second conjugated diene monomer unit; a second ethylenically unsaturated nitrile monomer unit; a second carboxylic acid-modified nitrile copolymer comprising the second ethylenically unsaturated acid monomer unit and a reactive emulsifier unit, wherein the first carboxylic acid-modified nitrile copolymer latex and the second carboxylic acid-modified nitrile copolymer latex may have a weight ratio of 1:0.6 to 1.5 based on the solid content of each latex.

[0050]

[0051] In general, the carboxylic acid-modified nitrile copolymer latex that constitutes the latex composition for dip molding is manufactured by emulsion polymerization, and in emulsion polymerization, an emulsifier is essential to lower the interfacial tension between the monomer and the liquid phase to create a stable dispersion, dissolution, and emulsification state between the reaction phase and the continuous phase, provide micelle reaction sites necessary for polymerization through micelle formation, and stabilize the polymer latex emulsion.

[0052] These emulsifiers are typically ionic, low molecular weight emulsifiers such as nonionic, anionic, and cationic. However, these ionic, low molecular weight emulsifiers do not chemically bond with polymers, which adversely affect the properties of the molded product. Specifically, when manufacturing a molded product, the emulsifier moves from the coagulated latex phase to the surface or adhesive interface, easily causing phase separation. In addition, since the emulsifier is highly soluble in water, when the phase-separated emulsifier comes into contact with water, it desorbs, creating flow marks on the surface of the molded product or generating bubbles, which causes quality problems.

[0053] However, a latex composition for dip molding according to one embodiment of the present invention comprises a first carboxylic acid-modified nitrile-based copolymer latex and a second carboxylic acid-modified nitrile-based copolymer latex manufactured using a reactive emulsifier without using the above-described ionic, low-molecular-weight emulsifier and including a reactive emulsifier unit in a controlled ratio, thereby enabling excellent latex stability while having a reduced residual amount of ionic, low-molecular-weight emulsifier, and at the same time providing a dip molded product having excellent surface properties and tensile properties and suppressed foaming.

[0054]

[0055] 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.

[0056]

[0057] First carboxylic acid modified nitrile copolymer latex

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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 40 wt% to 75 wt%, 45 wt% to 70 wt%, or 50 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 excellent flexibility and wearability, and has excellent oil resistance and tensile strength.

[0062] 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.

[0063] According to one embodiment of the present invention, the 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 a first carboxylic acid-modified nitrile-based copolymer latex composition including the first 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.

[0064] 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.

[0065] 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.

[0066]

[0067] Second carboxylic acid modified nitrile copolymer latex

[0068] 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 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.

[0069] According to one embodiment of the present invention, the second carboxylic acid-modified nitrile copolymer latex may include a second conjugated diene monomer unit, a second ethylenically unsaturated nitrile monomer unit, a second ethylenically unsaturated acid monomer unit, and a reactive emulsifier unit.

[0070] According to one embodiment of the present invention, the second carboxylic acid-modified nitrile-based copolymer latex is prepared by emulsion polymerization in the presence of a reactive emulsifier without using an ionic, low-molecular-weight emulsifier, and the reactive emulsifier may form a chemical bond with a polymer chain formed by a monomer. Accordingly, a latex composition for dip molding according to one embodiment of the present invention, which includes a predetermined ratio of the second carboxylic acid-modified nitrile-based copolymer latex together with the first carboxylic acid-modified nitrile-based copolymer latex, may have excellent latex stability while containing a reduced amount of ionic, low-molecular-weight emulsifier, and a molded article prepared therefrom may have excellent surface properties.

[0071] Meanwhile, in the present invention, the term 'reactive emulsifier unit' may indicate a component, structure, or substance itself derived from a reactive emulsifier, and as a specific example, may mean a unit (part) formed by a reactive emulsifier introduced during polymerization participating in a polymerization reaction and chemically bonding with a polymer chain.

[0072] In addition, according to one embodiment of the present invention, the second carboxylic acid-modified nitrile-based copolymer may include 3 wt% to 5 wt% of a reactive emulsifier unit, in which case the latex stability of the second carboxylic acid-modified nitrile-based copolymer latex including the same may be excellent.

[0073] The above reactive emulsifier may be at least one selected from the group consisting of sodium 2-methyl-2-propene-1-sulfonate, sodium allyloxy hydroxypropyl sulfonate, sodium 2-hydroxy-3-(methacryloyloxy)propane-1 sulfonate, sodium 11-methacryloyl undecan-1-yl sulfate, and sodium 11-crodonoylundetan-1-yl sulfate, and specifically, may be sodium 2-methyl-2-propene-1-sulfonate.

[0074]

[0075] 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.

[0076] According to one embodiment of the present invention, the second carboxylic acid-modified nitrile-based copolymer may contain 35 wt% to 75 wt%, 40 wt% to 70 wt%, or 45 wt% to 70 wt% of the second conjugated diene-based monomer unit, 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, having excellent wearability, and having excellent oil resistance and tensile strength.

[0077] 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.

[0078] According to one embodiment of the present invention, the second carboxylic acid-modified nitrile-based copolymer may contain 20 wt% to 50 wt%, 20 wt% to 45 wt%, or 20 wt% to 40 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 has excellent oil resistance and tensile strength.

[0079] According to one embodiment of the present invention, the second ethylenically unsaturated acid monomer forming the second ethylenically unsaturated acid monomer unit of the second carboxylic acid-modified nitrile-based copolymer may be the same as described in the first ethylenically unsaturated acid monomer for forming the first ethylenically unsaturated acid monomer unit in the first carboxylic acid-modified nitrile-based copolymer latex, and specifically, the second ethylenically unsaturated acid monomer may be an ethylenically unsaturated carboxylic acid monomer such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, and fumaric acid; a polycarboxylic anhydride such as maleic anhydride and citraconic anhydride; an ethylenically unsaturated sulfonic acid monomer 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 more specifically, it may be methacrylic acid. In addition, the second 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. At this time, the second ethylenically unsaturated acid monomer for forming the second ethylenically unsaturated acid monomer unit of the second carboxylic acid-modified nitrile-based copolymer latex may be the same as or different from the first ethylenically unsaturated acid monomer for forming the first ethylenically unsaturated acid monomer unit of the first carboxylic acid-modified nitrile-based copolymer.

[0080] According to one embodiment of the present invention, the second 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 second 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.

[0081]

[0082] Latex composition for deep molding

[0083] According to one embodiment of the present invention, the latex composition for dip molding is for performing dip molding, and 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 1:0.6 to 1.5 and a weight ratio of 1:0.6 to 1.0. When the weight ratio is within the above range, the residual amount of an ionic, low-molecular-weight emulsifier in the latex composition for dip molding is reduced, while the latex stability is excellent, resulting in excellent workability in manufacturing a molded product, and the surface properties and tensile properties of the manufactured molded product are excellent while suppressing foaming.

[0084]

[0085] 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.

[0086] According to one embodiment of the present invention, the crosslinking agent composition may be for forming a crosslinking unit derived from the crosslinking agent through a crosslinking reaction for a carboxylic acid-modified nitrile-based copolymer.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094]

[0095] Method for producing a latex composition for deep molding

[0096] The present invention provides a method for producing the latex composition for dip molding.

[0097] A 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 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; a second ethylenically unsaturated nitrile monomer unit; a second ethylenically unsaturated acid monomer unit and a reactive emulsifier unit, in a weight ratio of 1:0.6 to 1.5 based on the solid content of each latex.

[0098]

[0099] 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.

[0100] Method for producing a first carboxylic acid-modified nitrile copolymer latex

[0101] 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.

[0102] 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.

[0103] Specifically, the first carboxylic acid-modified nitrile copolymer latex can be produced by emulsion polymerizing 40 to 75 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.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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.

[0111]

[0112] Method for producing a second carboxylic acid-modified nitrile copolymer latex

[0113] According to one embodiment of the present invention, the second carboxylic acid-modified nitrile copolymer latex may be manufactured by emulsion polymerizing a second conjugated diene monomer, a second ethylenically unsaturated nitrile monomer, and a second ethylenically unsaturated acid monomer in the presence of a reactive emulsifier in a solvent.

[0114]

[0115] According to one embodiment of the present invention, the solvent, the second conjugated diene monomer, the second ethylenically unsaturated nitrile monomer, the second ethylenically unsaturated acid monomer, and the reactive emulsifier may be the same as those described above.

[0116] Specifically, the second carboxylic acid-modified nitrile copolymer latex may be manufactured by including a step (S1) of introducing a reactive emulsifier and a second ethylenically unsaturated acid monomer into a reactor and initiating polymerization to manufacture a first polymer latex including a first polymer; and a step (S2) of introducing a second conjugated diene monomer, a second ethylenically unsaturated nitrile monomer, and a second ethylenically unsaturated acid monomer into the first polymer latex and polymerizing the second conjugated diene monomer, the second ethylenically unsaturated nitrile monomer, and the second ethylenically unsaturated acid monomer.

[0117] The manufacturing method according to one embodiment of the present invention is such that when manufacturing a second carboxylic acid-modified nitrile copolymer latex, a reactive emulsifier and a second ethylenically unsaturated acid monomer are pre-polymerized, so that the reactive emulsifier and the second ethylenically unsaturated acid monomer react, and the hydrophobic portion of the reactive emulsifier and the hydrophilic portion of the ionized second ethylenically unsaturated acid monomer form a micelle form similar to that of a general emulsifier, thereby allowing the polymerization reaction to proceed stably and easily.

[0118] The above reactive emulsifier is added in an amount of 3% to 5% by weight based on 100% by weight of the total polymerization reactant, and the polymerization reactant may include a second conjugated diene monomer, a second ethylenically unsaturated nitrile monomer, a second ethylenically unsaturated acid monomer, and a reactive emulsifier.

[0119] According to one embodiment of the present invention, the polymerization may be carried out without using any emulsifier other than a reactive emulsifier, and, if necessary, may be carried out in the presence of one or more additives selected from a molecular weight modifier and a polymerization initiator.

[0120] According to one embodiment of the present invention, the molecular weight regulator and polymerization initiator may be the same as those described above.

[0121] According to one embodiment of the present invention, the 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, 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 8.5 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 appropriately adjusted. By controlling, it is possible to prevent the latex stability from being reduced due to an increase in viscosity.

[0122] According to one embodiment of the present invention, the 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 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 for specific examples, the polymerization initiator can 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, the polymerization initiator can be added in an amount of 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, or 1.3 parts by weight. The polymerization can be carried out by adding the amount of 1.2 parts by weight or less, 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.

[0123] 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 polymerization.

[0124]

[0125] molded products

[0126] The present invention provides a dip-molded product manufactured by dip-molding the latex composition for dip-molding.

[0127] 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.

[0128] 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).

[0129] 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.

[0130] 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.

[0131] 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.

[0132] 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.

[0133]

[0134] 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.

[0135]

[0136] Examples and Comparative Examples

[0137] Manufacturing Example 1: Manufacturing of the first carboxylic acid-modified nitrile copolymer latex

[0138] 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, 3.0 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 (solid content 45 wt%, average particle diameter 120 nm).

[0139]

[0140] Manufacturing Example 2: Manufacturing of a second carboxylic acid-modified nitrile copolymer latex A

[0141] 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, 3 wt% of sodium 2-methyl-2-propene-1-sulfonate as a reactive emulsifier, 1.5 wt% of methacrylic acid, and 150 wt% of ion-exchanged water were introduced, and the internal temperature of the reactor was increased to 65°C. 1.2 wt% of potassium persulfate as a polymerization initiator was added thereto to initiate polymerization. After polymerization for 2 hours, 26 wt% of acrylonitrile, 3.5 wt% of methacrylic acid, 66 wt% of 1,3-butadiene, 0.55 wt% of t-dodecyl mercaptan as a molecular weight regulator, and 0.25 wt% of potassium persulfate were additionally added to continue the polymerization. Here, the weight parts of the emulsifier, polymerization initiator, and molecular weight regulator were based on 100 weight parts of the polymerization reactant containing acrylonitrile, 1,3-butadiene, methacrylic acid, and a reactive emulsifier. When the polymerization conversion rate reached 95%, potassium hydroxide was added to adjust the pH at 25°C to 5.5, and a deodorization process was performed to remove unreacted monomers, thereby obtaining a second carboxylic acid-modified nitrile copolymer latex A (solid content 35 wt%, average particle diameter 280.2 nm).

[0142]

[0143] Manufacturing Example 3: Manufacturing of second carboxylic acid-modified nitrile copolymer latex B

[0144] 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, 5 wt% of sodium 2-methyl-2-propene-1-sulfonate as a reactive emulsifier, 3.0 wt% of methacrylic acid, and 150 wt% of ion-exchanged water were introduced, and the internal temperature of the reactor was increased to 65°C. 1.2 wt% of potassium persulfate as a polymerization initiator was added thereto to initiate polymerization. After polymerization for 2 hours, 26 wt% of acrylonitrile, 2.0 wt% of methacrylic acid, 64 wt% of 1,3-butadiene, 0.55 wt% of t-dodecyl mercaptan as a molecular weight regulator, and 0.25 wt% of potassium persulfate were further added to continue the polymerization. Here, the weight parts of the emulsifier, polymerization initiator, and molecular weight regulator were based on 100 weight parts of the polymerization reactant containing acrylonitrile, 1,3-butadiene, methacrylic acid, and a reactive emulsifier. When the polymerization conversion rate reached 85%, potassium hydroxide was added to adjust the pH at 25°C to 5.4, and a deodorization process was performed to remove unreacted monomers, thereby obtaining a second carboxylic acid-modified nitrile copolymer latex B (solid content 35 wt%, average particle diameter 239.4 nm).

[0145]

[0146] Manufacturing Example 4: Manufacturing of a second carboxylic acid-modified nitrile copolymer latex C

[0147] 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, 3 wt% of sodium allyloxy hydroxy propyl sulfonate as a reactive emulsifier, 1.5 wt% of methacrylic acid, and 150 wt% of ion-exchanged water were introduced, and the internal temperature of the reactor was raised to 65°C. 1.2 wt% of potassium persulfate as a polymerization initiator was added thereto to initiate polymerization. After polymerization for 2 hours, 26 wt% of acrylonitrile, 3.5 wt% of methacrylic acid, 66 wt% of 1,3-butadiene, 0.55 wt% of t-dodecyl mercaptan as a molecular weight regulator, and 0.25 wt% of potassium persulfate were additionally added to continue the polymerization. Here, the weight parts of the emulsifier, polymerization initiator, and molecular weight regulator were based on 100 weight parts of the polymerization reactant containing acrylonitrile, 1,3-butadiene, methacrylic acid, and a reactive emulsifier. When the polymerization conversion rate reached 95%, potassium hydroxide was added to adjust the pH at 25°C to 5.5, and a deodorization process was performed to remove unreacted monomers, thereby obtaining a second carboxylic acid-modified nitrile copolymer latex C (solid content 35 wt%, average particle diameter 290.3 nm).

[0148]

[0149] Manufacturing Example 5: Manufacturing of a second carboxylic acid-modified nitrile copolymer latex D

[0150] 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, 3 wt% of sodium 2-hydroxy-3-(methacryloyloxy)propane-1 sulfonate as a reactive emulsifier, 1.5 wt% of methacrylic acid, and 150 wt% of ion-exchanged water were introduced, and the internal temperature of the reactor was raised to 65°C. 1.2 wt% of potassium persulfate as a polymerization initiator was added thereto to initiate polymerization. After 2 hours of polymerization, 26 wt% of acrylonitrile, 3.5 wt% of methacrylic acid, 66 wt% of 1,3-butadiene, 0.55 wt% of t-dodecyl mercaptan as a molecular weight regulator, and 0.25 wt% of potassium persulfate were added to continue the polymerization. Here, the weight parts of the emulsifier, polymerization initiator, and molecular weight regulator were based on 100 weight parts of the polymerization reactant including acrylonitrile, 1,3-butadiene, methacrylic acid, and a reactive emulsifier. When the polymerization conversion rate was 95%, potassium hydroxide was added to adjust the pH at 25°C to 5.5, and a deodorization process was performed to remove unreacted monomers, thereby obtaining a second carboxylic acid-modified nitrile-based copolymer latex D (solid content 35 wt%, average particle diameter 271.6 nm).

[0151]

[0152] Example 1

[0153] <Manufacture of latex composition for deep molding>

[0154] In the above, 100 parts by weight (based on solid content) of the first carboxylic acid-modified nitrile copolymer latex manufactured in Manufacturing Example 1 and the second carboxylic acid-modified nitrile copolymer latex A manufactured in Manufacturing Example 2 were added with 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 to manufacture a latex composition for dip molding having a solid content of 25 wt%, and ammonia was added to manufacture a latex composition for dip molding having a pH of 10 at 25°C. It was manufactured. 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 60:40 (1.5:1) based on the solid content of each latex.

[0155]

[0156] <Manufacturing of deep molded products>

[0157] 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.

[0158] 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.

[0159]

[0160] Example 2

[0161] In the above Example 1, when preparing a latex composition for dip molding, the first carboxylic acid-modified nitrile copolymer latex and the second carboxylic acid-modified nitrile copolymer latex A were mixed in a weight ratio of 50:50 (1:1) based on the solid content of the latex, and 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.

[0162]

[0163] Example 3

[0164] In the above Example 1, when preparing a latex composition for dip molding, the second carboxylic acid-modified nitrile copolymer latex B prepared in Preparation Example 2 was mixed in a weight ratio of 60:40 (1.5:1) instead of the second carboxylic acid-modified nitrile copolymer latex A, 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.

[0165]

[0166] Example 4

[0167] In the above Example 3, a latex composition for dip molding was manufactured in the same manner as Example 3, except that the first carboxylic acid-modified nitrile copolymer latex and the second carboxylic acid-modified nitrile copolymer latex B were mixed in a weight ratio of 50:50 (1:1) when manufacturing a latex composition for dip molding, and a dip molded product was obtained using the same.

[0168]

[0169] Example 5

[0170] In the above Example 1, except that the first carboxylic acid-modified nitrile copolymer latex and the second carboxylic acid-modified nitrile copolymer latex A were mixed in a weight ratio of 40:60 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.

[0171]

[0172] Example 6

[0173] In the above Example 1, except that the first carboxylic acid-modified nitrile copolymer latex and the second carboxylic acid-modified nitrile copolymer latex C were mixed in a weight ratio of 60:40 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.

[0174]

[0175] Example 7

[0176] In the above Example 1, except that the first carboxylic acid-modified nitrile copolymer latex and the second carboxylic acid-modified nitrile copolymer latex D were mixed in a weight ratio of 60:40 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.

[0177]

[0178] Comparative Example 1

[0179] 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.

[0180]

[0181] Comparative Example 2

[0182] In the above Example 1, when preparing a latex composition for dip molding, the first carboxylic acid-modified nitrile copolymer and the second carboxylic acid-modified nitrile copolymer latex A were mixed in a weight ratio of 70:30 based on the solid content of each latex, and 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.

[0183]

[0184] Comparative Example 3

[0185] In the above Example 1, when preparing a latex composition for dip molding, the first carboxylic acid-modified nitrile copolymer and the second carboxylic acid-modified nitrile copolymer latex A were mixed in a weight ratio of 30:70 based on the solid content of each latex, and 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.

[0186]

[0187] Comparative Example 4

[0188] In the above Example 3, a latex composition for dip molding was manufactured in the same manner as Example 3, except that the first carboxylic acid-modified nitrile copolymer and the second carboxylic acid-modified nitrile copolymer latex B were mixed in a weight ratio of 70:30 based on the solid content of each latex when manufacturing a latex composition for dip molding, and a dip molded product was obtained using the same.

[0189]

[0190] Comparative Example 5

[0191] In the above Example 3, a latex composition for dip molding was manufactured in the same manner as Example 3, except that the first carboxylic acid-modified nitrile copolymer and the second carboxylic acid-modified nitrile copolymer latex B were mixed in a weight ratio of 30:70 based on the solid content of each latex when manufacturing a latex composition for dip molding, and a dip molded product was obtained using the same.

[0192]

[0193] Experimental Example 1

[0194] The latex stability of the latex compositions for deep molding manufactured in Examples 1 to 7 and Comparative Examples 1 to 5 was measured, and the results are shown in Table 1 below.

[0195] Latex stability was confirmed through total coagulant content and reactor scale generation.

[0196] 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.

[0197] The amount of scale generated was evaluated by scoring the amount of scale generated inside the container after manufacturing the dip-molded product using a 10-point scale system, with a higher score indicating better results. A completely clean container was given 10 points, a fine band at the interface was given 9 points, scale throughout the impeller was given 5 points, scale that made manufacturing the dip-molded product difficult was given 2 points, and a complete breakdown of latex stability was given 0 points.

[0198]

[0199] As shown in Table 1 above, it was confirmed that the dip molding latex of Examples 1 to 7 had a significantly reduced total coagulant content of about 13% to 38% while maintaining a similar reactor scale amount compared to Comparative Examples 1 to 5. Here, Comparative Example 1 does not include the second carboxylic acid-modified nitrile-based copolymer latex suggested in the present invention, and Comparative Examples 2 to 5 include the first and second carboxylic acid-modified nitrile-based copolymer latexes, but include them in a ratio that deviates from the ratio suggested in the present invention. From the above results, it was confirmed that the dip molding latex composition according to the present invention has an excellent effect of latex stability by including the first and second carboxylic acid-modified copolymer latexes while controlling the ratio of the first and second carboxylic acid-modified copolymer latexes.

[0200]

[0201] Experimental Example 2

[0202] The dip molding workability of the latex compositions for dip molding manufactured in Examples 1 to 7 and Comparative Examples 1 to 5 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.

[0203] (1) Deep forming workability

[0204] Deep forming workability was evaluated by flow marks.

[0205] The degree of flow mark occurrence of each of the 10 deep-molded products was visually observed and evaluated using a 10-point scale. The evaluation was as follows: 0 flow marks visually visible within a 2 cm × 2 cm area was 10 points, 1 was 9 points, 2 were 8 points, 3 were 7 points, 4 to 5 were 6 points, 6 to 7 were 5 points, 8 to 10 were 4 points, 11 to 12 were 3 points, 13 to 14 were 2 points, and 15 or more were 1 point.

[0206]

[0207] (2) Tensile strength (MPa), elongation (%), 300% modulus (MPa) and 500% modulus (MPa)

[0208] 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. In addition, the force at break (FAB) at the time the test piece was cut was also indicated.

[0209] [Equation 2]

[0210] Tensile strength (kgf / mm) 2 ) = load value (kgf) / (thickness (mm) × width (mm))

[0211] 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.

[0212] [Equation 3]

[0213] Elongation (%) = (length of specimen after elongation / length of specimen before elongation) × 100

[0214] 300% modulus and 500% modulus were measured using a UTM (Universal Testing Machine) device (Instron, Model: 4466) manufactured for the above tensile strength measurement in accordance with ASTM D638, at a crosshead speed of 500 mm / min, and when the specimen was stretched 3 times and 5 times its pre-tension length, the tensile strength of 300% modulus and 500% modulus were measured. At this time, the lower the measured 300% modulus and 500% modulus, the softer and more comfortable it is to wear.

[0215]

[0216] (3) Degree of foaming (10-point method)

[0217] For each dip-molded product, the leaching process was performed 50 times, water droplets were dropped on the dip-molded product 8 times, the dip-molded product was folded in half and rubbed for 10 seconds to generate foam, and the degree of foam generation was calculated using the following mathematical formula 4 and evaluated as follows: less than 1% was given 10 points, 1% or more but less than 5% was given 9 points, 5% or more but less than 10% was given 8 points, 10% or more but less than 20% was given 7 points, 20% or more but less than 30% was given 6 points, 30% or more but less than 40% was given 5 points, 40% or more but less than 50% was given 4 points, 50% or more but less than 70% was given 3 points, 70% or more but less than 90% was given 2 points, and 90% or more was given 1 point. A larger number indicates better performance. At this time, the area of ​​the foam and the total area of ​​the molded product were obtained by taking a surface photograph immediately after mixing and using the Image J program.

[0218] [Equation 4]

[0219] Foaming rate (%) = [Foam area / Total molded product area] × 100

[0220]

[0221] As shown in Table 2 above, it was confirmed that the deep-molded products of Examples 1 to 7 had significantly improved workability while having tensile properties that were at least as good as those of Comparative Examples 1 to 5.

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 latex comprising a second conjugated diene monomer unit; a second ethylenically unsaturated nitrile monomer unit; a second carboxylic acid-modified nitrile copolymer comprising a second ethylenically unsaturated acid monomer unit and a reactive emulsifier unit, 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 1:0.6 to 1.5 based on the solid content of each latex.

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 1:0.6 to 1 based on the solid content of each latex.

3. In paragraph 1, A latex composition for dip molding, wherein the first carboxylic acid-modified nitrile copolymer comprises 40 to 75 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 3 to 5 wt% of a reactive emulsifier unit.

5. In paragraph 1, A latex composition for dip molding, wherein the second carboxylic acid-modified nitrile copolymer comprises 35 to 75 wt% of a second conjugated diene monomer unit; 20 to 50 wt% of a second ethylenically unsaturated nitrile monomer unit; 0.1 to 10 wt% of a second ethylenically unsaturated acid monomer unit; and 3 to 5 wt% of a reactive emulsifier unit.

6. In paragraph 1, A latex composition for dip molding, wherein the reactive emulsifier is at least one selected from the group consisting of sodium 2-methyl-2-propene-1-sulfonate, sodium allyloxy hydroxypropyl sulfonate, sodium 2-hydroxy-3-(methacryloyloxy)propane-1 sulfonate, sodium 11-methacryloyl undecan-1-yl sulfate, and sodium 11-crodonoyl undetan-1-yl sulfate.

7. A method for producing a latex composition for dip molding, comprising the step of mixing 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; a second ethylenically unsaturated nitrile monomer unit; a second ethylenically unsaturated acid monomer unit and a reactive emulsifier unit, in a weight ratio of 1:0.6 to 1.5 based on the solid content of each latex.

8. In paragraph 7 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 1:0.6 to 1.0 based on the solid content of each latex.

9. In paragraph 7, 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.

10. In paragraph 7, The above second carboxylic acid modified nitrile copolymer latex is, Step (S1) of introducing a reactive emulsifier and a second ethylenically unsaturated acid monomer into a reactor and initiating polymerization to produce a first polymer latex including a first polymer; and A method for producing a latex composition for dip molding, comprising the step (S2) of adding a second conjugated diene monomer, a second ethylenically unsaturated nitrile monomer, and a second ethylenically unsaturated acid monomer to the first polymer latex and polymerizing the same.

11. In paragraph 10, The above reactive emulsifier is added in an amount of 3 to 5 wt% based on 100 wt% of the total polymerization reactant. A method for producing a latex composition for dip molding, wherein the polymerization reactant comprises a second conjugated diene monomer, a second ethylenically unsaturated nitrile monomer, a second ethylenically unsaturated acid monomer, and a reactive emulsifier.

12. In paragraph 7, A method for producing a latex composition for dip molding, wherein the reactive emulsifier is at least one selected from the group consisting of sodium 2-methyl-2-propene-1-sulfonate, sodium allyloxy hydroxypropyl sulfonate, sodium 2-hydroxy-3-(methacryloyloxy)propane-1 sulfonate, sodium 11-methacryloyl undecan-1-yl sulfate, and sodium 11-crodonoyl undetan-1-yl sulfate.

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

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