Polymer composition, method for producing the same, latex composition for dip molding containing the same, and molded article

Abstract

The present invention relates to a polymer composition applicable as a latex stabilizer for a dip molding latex composition, a production method thereof, a dip molding latex composition containing the same and having improved latex stability, and a molded article molded therefrom and having improved wearing comfort and tensile properties.

Description

[Technical Field]

[0001] The present invention claims the benefit of priority based on Korean Patent Application No. 10-2021-0125033, filed on September 17, 2021, and all contents disclosed in the documents of this Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a polymer composition applicable as a latex stabilizer for a dip-molding latex composition, a method for producing the same, a dip-molding latex composition containing the same and having improved latex stability, and a molded article molded from the same and having improved wear comfort and tensile properties. [Background technology]

[0003] Traditionally, natural rubber has been the primary raw material for products requiring elasticity, such as industrial, medical, and food-safe gloves, as well as balloons and condoms. However, in recent years, natural rubber has been replaced by nitrile rubber due to side effects that can cause serious protein allergies in some users. Nitrile rubber has high chemical resistance and is widely used in work gloves, particularly those used by users who handle organic solvents, as well as medical and food-safe gloves.

[0004] In addition, in recent years, due to the unstable supply and demand of natural rubber, many glove manufacturers have switched from natural rubber glove production lines to nitrile rubber glove production lines, and as awareness of safety increases, the use of disposable gloves made from nitrile rubber is on a continuous upward trend.

[0005] Such nitrile rubber gloves are generally manufactured by dip molding using latex for dip molding. In this case, if the stability of the latex for dip molding is low, coagulation occurs, which increases the defective rate of the final dip molded product, causing a decrease in productivity, and in serious cases, making dip molding itself impossible.

[0006] In particular, when the temperature drops below zero as in winter, the stability of the dip molding latex drops sharply, and as a result, the occurrence of coagulation and sediment increases in the dip molding latex during storage. Therefore, there is a need for a method for improving the low-temperature stability as well as the storage stability of the dip molding latex.

[0007] On the other hand, nitrile rubber gloves, which are dip-molded products made from dip-molding latex, have the drawback of being less soft than gloves made from natural rubber. This causes a decrease in comfort when wearing the gloves, and they are not a satisfactory substitute for natural rubber gloves, particularly when used as surgical gloves. Therefore, measures to improve the softness of gloves are needed. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] KR10-2014-0053859A Summary of the Invention [Problem to be solved by the invention]

[0009] The problem to be solved by the present invention is to improve the storage stability and low-temperature stability of a dip-molding latex composition in order to solve the problems described in the background art, and also to improve the softness of a molded article molded therefrom to improve wearing comfort.

[0010] That is, the present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a polymer composition applicable as a latex stabilizer for a latex composition for dip molding in order to improve the storage stability and low-temperature stability of the latex composition for dip molding, and a method for producing the same.

[0011] Another object of the present invention is to provide a latex composition for dip molding which contains the polymer composition and thereby has improved latex stability, particularly improved storage stability and low-temperature stability.

[0012] Another object of the present invention is to provide a molded article which is molded from the dip molding latex composition and which has improved softness, excellent wearing comfort, and excellent tensile properties. [Means for solving the problem]

[0013] In order to solve the above problems, the present invention provides a polymer composition, a method for producing a polymer composition, a latex composition for dip molding, and a molded article. (1) The present invention provides a polymer composition comprising a polymer dispersed in a solvent, the polymer comprising conjugated diene-based monomer units, ethylenically unsaturated nitrile-based monomer units, and ethylenically unsaturated acid monomer units, the polymer having a weight-average molecular weight of 5,000 g / mol or more and 50,000 g / mol or less and a glass transition temperature of −34° C. or more and 33° C. or less.

[0014] (2) The present invention provides the polymer composition according to (1) above, wherein the solvent is an aqueous solvent.

[0015] (3) In the present invention, there is provided the polymer composition according to (1) or (2) above, wherein the polymer contains 40% by weight or more and 75% by weight or less of conjugated diene-based monomer units, 10% by weight or more and 50% by weight or less of ethylenically unsaturated nitrile-based monomer units, and 10% by weight or more and 50% by weight or less of ethylenically unsaturated acid monomer units.

[0016] (4) The present invention provides the polymer composition according to any one of (1) to (3) above, wherein the polymer has a weight-average molecular weight of 7,000 g / mol or more and 46,000 g / mol or less.

[0017] (5) The present invention provides the polymer composition according to any one of (1) to (4) above, wherein the polymer has a glass transition temperature of −28° C. or higher and 24° C. or lower.

[0018] (6) The present invention provides the polymer composition according to any one of (1) to (5) above, wherein the polymer composition has a pH at 25° C. of 7.0 or more and 10.0 or less.

[0019] (7) The present invention provides a method for producing a polymer composition, comprising a step (S10) of emulsion-polymerizing a conjugated diene monomer, an ethylenically unsaturated nitrile monomer, and an ethylenically unsaturated acid monomer in a solvent to produce a polymer latex containing a polymer, wherein the polymer polymerized in the step (S10) has a weight-average molecular weight of 5,000 g / mol or more and 50,000 g / mol or less and a glass transition temperature of −34° C. or more and 33° C. or less.

[0020] (8) The present invention provides the method for producing a polymer composition according to (7) above, wherein the emulsion polymerization in step (S10) is 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 per 100 parts by weight of the total amount of monomers.

[0021] (9) The present invention provides a method for producing the polymer composition according to (7) or (8), comprising: a step (S20) of adding a pH adjuster to the polymer latex produced in the step (S10); and a step (S30) of obtaining the polymer latex, the pH of which has been adjusted in the step (S20), in an emulsion phase.

[0022] (10) The present invention provides a latex composition for dip molding, comprising a carboxylic acid-modified nitrile-based copolymer latex and the polymer composition according to any one of (1) to (6), wherein the carboxylic acid-modified nitrile-based copolymer latex comprises a carboxylic acid-modified nitrile-based copolymer, and the carboxylic acid-modified nitrile-based copolymer comprises a conjugated diene-based monomer unit, an ethylenically unsaturated nitrile-based monomer unit, and an ethylenically unsaturated acid monomer unit.

[0023] (11) The present invention provides the latex composition for dip-molding according to the above (10), comprising 1 part by weight or more and 15 parts by weight or less of the polymer composition based on the solid content per 100 parts by weight based on the solid content of the carboxylic acid-modified nitrile-based copolymer latex.

[0024] (12) The present invention provides a molded article comprising a layer derived from the dip-molding latex composition according to (10) or (11). [Effects of the Invention]

[0025] The polymer composition according to the present invention is applicable as a latex stabilizer for a dip-molding latex composition, and can improve the latex stability, particularly the storage stability and low-temperature stability, of the dip-molding latex composition containing the polymer composition. Furthermore, the molded article according to the present invention is molded from the latex composition for dip molding, and has improved softness, excellent wearing comfort, and excellent tensile properties. DETAILED DESCRIPTION OF THE INVENTION

[0026] The present invention will now be described in more detail to aid in understanding the invention. The terms and words used in the description of the present invention and the claims should not be interpreted in a limited way to their ordinary or dictionary meanings, but should be interpreted in a way that is consistent with the technical idea of ​​the present invention, based on the principle that the inventors can appropriately define the concepts of terms in order to best describe their inventions.

[0027] The term "monomer unit" used in the present invention may refer to a component, structure, or substance itself resulting from a monomer, and as a specific example, may refer to a repeating unit formed in a polymer when an input monomer participates in the polymerization reaction during polymerization of the polymer.

[0028] The term "polymer" as used in the present invention may be intended to include both a homopolymer formed by polymerization of one type of monomer and a copolymer formed by copolymerization of two types of monomers.

[0029] The terms "latex" and "emulsion" used in the present invention mean that a polymer or copolymer polymerized by polymerization exists in a form dispersed in water, and as a specific example, they can mean that fine particles of a rubbery polymer or rubbery copolymer polymerized by emulsion polymerization exist in a form dispersed in water in a colloidal state, and in the present invention, "latex" and "emulsion" may be used interchangeably.

[0030] As used herein, the term "composition" includes mixtures of materials comprising the composition as well as reaction products and decomposition products formed from the materials of the composition.

[0031] The term "derived layer" as used in the present invention may refer to a layer formed from a polymer or copolymer, and as a specific example, it may refer to a layer formed from a polymer or copolymer that is adhered, fixed, and / or polymerized on a dip-molding mold during the production of a dip-molded article.

[0032] The present invention provides a polymer composition that can be used as a latex stabilizer for dip-molding latex compositions. According to one embodiment of the present invention, the polymer composition may be an alkali-soluble polymer composition, specifically an alkali-soluble emulsion polymer, i.e., an alkali-soluble resin (ASR). Therefore, the polymer composition may exist in a latex state.

[0033] According to one embodiment of the present invention, the polymer composition includes a polymer dispersed in a solvent, the polymer including a conjugated diene-based monomer unit, an ethylenically unsaturated nitrile-based monomer unit, and an ethylenically unsaturated acid monomer unit, and the polymer may have a weight-average molecular weight of 5,000 g / mol to 50,000 g / mol and a glass transition temperature of -34°C to 33°C.

[0034] According to one embodiment of the present invention, the polymer composition may be in a latex state, whereby the polymer is dispersed in a solvent. The polymer composition may be prepared by emulsion polymerization, as described below, whereby the solvent may be an aqueous solvent that can be used in emulsion polymerization. As a specific example, the aqueous solvent may be water, which may be ion-exchanged water or distilled water.

[0035] According to one embodiment of the present invention, the polymer may contain conjugated diene-based monomer units, ethylenically unsaturated nitrile-based monomer units, and ethylenically unsaturated acid monomer units. Known alkali-soluble resins generally contain acrylate-based monomers as the main monomer. However, alkali-soluble resins containing such acrylate-based monomers are not suitable for use as latex stabilizers in dip-molding latex compositions due to their low compatibility with the carboxylic acid-modified nitrile-based copolymers contained in the dip-molding latex compositions. To address this issue, the polymer of the present invention is characterized by containing monomer units derived from the same monomer or monomers as the carboxylic acid-modified nitrile-based copolymer. This not only makes the polymer suitable for use as a latex stabilizer in dip-molding latex compositions, but also improves the wear comfort and mechanical properties, such as tensile strength, of molded articles.

[0036] According to one embodiment of the present invention, the conjugated diene monomer for forming the conjugated diene monomer unit 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 a specific example thereof may be 1,3-butadiene or isoprene, and a more specific example thereof may be 1,3-butadiene.

[0037] According to one embodiment of the present invention, the ethylenically unsaturated nitrile-based monomer forming the ethylenically unsaturated nitrile-based monomer unit may be at least one selected from the group consisting of acrylonitrile, methacrylonitrile, fumaronitrile, α-chloronitrile, and α-cyanoethylacrylonitrile, and specific examples thereof may include acrylonitrile and methacrylonitrile, and a more specific example thereof may be acrylonitrile.

[0038] According to one embodiment of the present invention, the ethylenically unsaturated acid monomer forming the ethylenically unsaturated acid monomer unit may be an ethylenically unsaturated monomer containing an acidic group such as a carboxyl group, a sulfonic acid group, or an acid anhydride group, specifically at least one selected from the group consisting of ethylenically unsaturated carboxylic acid monomers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, and fumaric acid; polycarboxylic acid anhydrides such as maleic anhydride and citraconic anhydride; ethylenically unsaturated sulfonic acid monomers such as styrenesulfonic acid; and ethylenically unsaturated polycarboxylic acid partial ester monomers such as monobutyl fumarate, monobutyl maleate, and mono-2-hydroxypropyl maleate, more specifically at least one selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, maleic acid, and fumaric acid, and even more specifically methacrylic acid. The ethylenically unsaturated acid monomer may be used in the form of a salt, such as an alkali metal salt or ammonium salt, during polymerization.

[0039] According to one embodiment of the present invention, the polymer may contain 40 to 75% by weight of conjugated diene monomer units, 10 to 50% by weight of ethylenically unsaturated nitrile monomer units, and 10 to 50% by weight of ethylenically unsaturated acid monomer units. Within these ranges, the target glass transition temperature of the present invention can be satisfied and a balance between wearing comfort and tensile properties can be maintained.

[0040] According to one embodiment of the present invention, the polymer may contain 40% by weight or more, 45% by weight or more, 50% by weight or more, 55% by weight or more, or 60% by weight or less of conjugated diene monomer units. Within this range, the glass transition temperature can be adjusted and mechanical properties such as tensile properties of a molded article molded from a dip molding latex composition containing the polymer composition can be improved.

[0041] According to one embodiment of the present invention, the polymer may contain 10% by weight or more, 11% by weight or more, 12% by weight or more, 13% by weight or more, 14% by weight or more, 15% by weight or more, 16% by weight or more, 17% by weight or more, 18% by weight or more, 19% by weight or more, or 50% by weight or less, 45% by weight or less, 40% by weight or less, 35% by weight or less, 30% by weight or less, 25% by weight or less, 24% by weight or less, 23% by weight or less, 22% by weight or less, 21% by weight or less, or 20% by weight or less. Within this range, the glass transition temperature can be adjusted and the wear comfort and mechanical properties, such as tensile strength, of a molded article molded from a dip molding latex composition containing the polymer composition can be improved.

[0042] According to one embodiment of the present invention, the polymer may contain 10% by weight or more, 11% by weight or more, 12% by weight or more, 13% by weight or more, 14% by weight or more, 15% by weight or more, 16% by weight or more, 17% by weight or more, 18% by weight or more, 19% by weight or more, or 50% by weight or less, 45% by weight or less, 40% by weight or less, 35% by weight or less, 30% by weight or less, 25% by weight or less, 24% by weight or less, 23% by weight or less, 22% by weight or less, 21% by weight or less, or 20% by weight or less. Within this range, the glass transition temperature can be adjusted and the wear comfort and mechanical properties, such as tensile strength, of a molded article molded from a dip molding latex composition containing the polymer composition can be improved.

[0043] According to one embodiment of the present invention, the polymer may have a weight-average molecular weight of 5,000 g / mol or more and 50,000 g / mol or less. Specific examples of the polymer include weight-average molecular weights 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. or may be 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. If the weight-average molecular weight of the polymer is lower than the above-mentioned range, the entanglement between the polymer and the carboxylic acid-modified nitrile copolymer in the dip-molding latex composition is reduced, resulting in a problem that the mechanical properties, such as tensile properties, of a molded article molded from the dip-molding latex composition are deteriorated. In addition, if the weight average molecular weight of the polymer is higher than the above range, the viscosity increases during the preparation of the polymer composition, which reduces the stability of the latex, making it difficult to substantially complete the polymerization, resulting in a problem that the preparation of the polymer composition becomes impossible.

[0044] According to one embodiment of the present invention, the polymer may have a glass transition temperature of -34°C or higher and 33°C or lower. Specific examples of 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, or may 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. If the glass transition temperature of the polymer is lower than the above-mentioned range, the molded article molded from the dip-molding latex composition will have a problem of reduced tensile strength. If the glass transition temperature of the polymer is higher than the above-mentioned range, the molded article molded from the dip-molding latex composition will have a problem of hardness and poor comfort. Therefore, by adjusting the glass transition temperature of the polymer within the above-mentioned range, the wear comfort and mechanical properties such as tensile strength of the molded article molded from the dip-molding latex composition can be improved simultaneously. The glass transition temperature can be adjusted by adjusting the content of each monomer unit, particularly the content of conjugated diene-based monomer units, of the polymer, and can be measured using a differential scanning calorimetry (DSC).

[0045] According to one embodiment of the present invention, the polymer composition may have a pH at 25° C. of 7.0 or more and 10.0 or less. Specific examples of the polymer composition may have a pH at 25° C. 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 have a pH at 25° C. 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. Within this range, the latex stability, particularly storage stability and low-temperature stability, of the dip-molding latex composition can be further improved.

[0046] The present invention provides a method for producing the polymer composition. According to one embodiment of the present invention, the method for preparing the polymer composition includes a step (S10) of emulsion-polymerizing a conjugated diene-based monomer, an ethylenically unsaturated nitrile-based monomer, and an ethylenically unsaturated acid monomer in a solvent to prepare a polymer latex containing a polymer. The polymer polymerized in the step (S10) may have a weight-average molecular weight of 5,000 g / mol to 50,000 g / mol and a glass transition temperature of -34°C to 33°C.

[0047] According to one embodiment of the present invention, the solvent, the conjugated diene monomer, the ethylenically unsaturated nitrile monomer, and the ethylenically unsaturated acid monomer are as described above.

[0048] According to one embodiment of the present invention, step (S10) is a step for preparing the polymer composition in a latex state, and may be performed by emulsion polymerization. Here, the emulsion polymerization in step (S10) may be performed in the presence of an emulsifier and a molecular weight modifier.

[0049] According to one embodiment of the present invention, the emulsion polymerization in step (S10) may be carried out in the presence of an emulsifier. The emulsifier may be one or more selected from the group consisting of anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants. Specific examples of the emulsifier include one or more anionic surfactants selected from the group consisting of alkylbenzene sulfonates, aliphatic sulfonates, higher alcohol sulfates, α-olefin sulfonates, and alkyl ether sulfates.

[0050] According to one embodiment of the present invention, the emulsion polymerization in step (S10) may be carried out by adding 1.0 to 5.0 parts by weight of the emulsifier relative to 100 parts by weight of the total monomer content. Specific examples include 1.0 to 1.5 parts by weight, 2.0 to 2.5 parts by weight or more of the emulsifier, or 5.0 to 4.5 parts by weight, 4.0 to 3.5 parts by weight, 3.0 to 2.5 parts by weight or less. Within these ranges, the polymerization stability may be improved.

[0051] According to one embodiment of the present invention, the emulsion polymerization in step (S10) may be carried out in the presence of a molecular weight regulator. The molecular weight regulator may 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 tetraethylthiuram disulfide, dipentamethylenethiuram disulfide, and diisopropylxanthogen disulfide. A specific example of the molecular weight regulator is t-dodecyl mercaptan.

[0052] According to one embodiment of the present invention, the emulsion polymerization in step (S10) may be carried out by adding the molecular weight modifier in an amount of 0.8 to 8.0 parts by weight, based on 100 parts by weight of the total monomers. Specific examples include 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. Also, the amount may be 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. Within this range, the molecular weight of the polymer can be appropriately controlled to prevent a decrease in stability due to an increase in viscosity, and the entanglement between the polymer and the carboxylic acid-modified nitrile copolymer can be improved, thereby further improving mechanical properties such as tensile properties of a molded product molded from the dip molding latex composition.

[0053] According to one embodiment of the present invention, the emulsion polymerization in step (S10) may be initiated by adding a polymerization initiator. The polymerization initiator may be a radical initiator, and specific examples thereof may be one or more selected from the group consisting of 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-butylperoxyisobutyrate; and nitrogen compounds such as azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, azobiscyclohexanecarbonitrile, and azobismethylisobutyrate. Specific examples thereof may include inorganic peroxides, and more specific examples thereof may include persulfates.

[0054] According to one embodiment of the present invention, the emulsion polymerization in step (S10) may be carried out by adding the polymerization initiator in an amount of 0.01 to 2.0 parts by weight based on 100 parts by weight of the total monomers. Specific examples include 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 part by weight or more. Alternatively, the emulsion polymerization may be carried out 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, 1.3 parts by weight or less, 1.2 parts by weight or less, 1.1 parts by weight or less, or 1.0 part by weight or less. Within this range, the polymerization rate can be maintained at a suitable level.

[0055] According to one embodiment of the present invention, during the emulsion polymerization in step (S10), a certain amount of sample is collected from the composition during the reaction at a certain time interval, and the solid content in the sample is measured, and then the polymerization conversion can be calculated using the following Equation 1:

[0056] [Formula 1] Polymerization conversion rate (%) = [(Ms - Mo) / (Mp - M'o)] x 100

[0057] In the above formula 1, Ms is the weight of the dried copolymer, Mo is the total weight of the emulsifier and the polymerization initiator, Mp is the weight of the 100% polymerized copolymer, and M'o is the total weight of the emulsifier and the polymerization initiator.

[0058] According to an embodiment of the present invention, the method for preparing the polymer composition may include a step (S20) of adding a pH adjuster to the polymer latex prepared in the step (S10), and a step (S30) of obtaining the polymer latex, the pH of which has been adjusted in the step (S20), in an emulsion state.

[0059] According to one embodiment of the present invention, step (S20) is a step for adjusting the pH of the polymer latex prepared in step (S10), and step (S20) can adjust the pH of the polymer composition obtained in step (S30) to 7.0 or more and 10.0 or less at 25° C. In this case, the pH adjuster may be a basic compound, and specific examples thereof may include an alkali hydroxide salt and / or an aqueous ammonia solution, and more specific examples thereof may include sodium hydroxide or potassium hydroxide.

[0060] According to one embodiment of the present invention, step (S30) is a step of obtaining a polymer latex in an emulsion state, and may optionally include a deodorizing step for removing unreacted monomers and residual components. The polymer composition obtained from step (S30) may be an alkali-soluble polymer composition, and a specific example thereof may be an alkali-soluble emulsion polymer, i.e., an alkali-soluble resin (ASR). Thus, the polymer composition can exist in a latex state.

[0061] The present invention provides a dip-molding latex composition for producing a molded article by dip molding. According to one embodiment of the present invention, the latex composition for dip molding includes a carboxylic acid-modified nitrile-based copolymer latex and the polymer composition, the carboxylic acid-modified nitrile-based copolymer latex includes a carboxylic acid-modified nitrile-based copolymer, and the carboxylic acid-modified nitrile-based copolymer may include a conjugated diene-based monomer unit, an ethylenically unsaturated nitrile-based monomer unit, and an ethylenically unsaturated acid monomer unit.

[0062] According to one embodiment of the present invention, the carboxylic acid-modified nitrile-based copolymer latex may be in a latex state in which the carboxylic acid-modified nitrile-based 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.

[0063] According to one embodiment of the present invention, the carboxylic acid-modified nitrile-based copolymer may include monomer units derived from the same monomer or the same type of monomer as the polymer, as described above. Specific examples thereof include conjugated diene-based monomer units, ethylenically unsaturated nitrile-based monomer units, and ethylenically unsaturated acid monomer units.

[0064] According to one embodiment of the present invention, the conjugated diene monomer forming the conjugated diene monomer unit of the carboxylic acid-modified nitrile-based 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 a specific example thereof may be 1,3-butadiene or isoprene, and a more specific example thereof may be 1,3-butadiene. In this case, the conjugated diene monomer forming the conjugated diene monomer unit of the polymer and the conjugated diene monomer forming the conjugated diene monomer unit of the carboxylic acid-modified nitrile-based copolymer may be the same or different.

[0065] According to one embodiment of the present invention, the carboxylic acid-modified nitrile-based copolymer may contain 35 to 80% by weight, 40 to 75% by weight, or 45 to 70% by weight of repeating units derived from the conjugated diene-based monomer. Within this range, a molded article molded from a dip-molding latex composition containing the carboxylic acid-modified nitrile-based copolymer latex is flexible, has excellent wearing comfort, and exhibits excellent oil resistance and tensile strength.

[0066] According to one embodiment of the present invention, the ethylenically unsaturated nitrile-based monomer forming the ethylenically unsaturated nitrile-based monomer unit of the carboxylic acid-modified nitrile-based copolymer may be at least one selected from the group consisting of acrylonitrile, methacrylonitrile, fumaronitrile, α-chloronitrile, and α-cyanoethylacrylonitrile, and specific examples thereof include acrylonitrile and methacrylonitrile, and more specific example thereof may be acrylonitrile. In this case, the ethylenically unsaturated nitrile-based monomer forming the ethylenically unsaturated nitrile-based monomer unit of the polymer and the ethylenically unsaturated nitrile-based monomer forming the ethylenically unsaturated nitrile-based monomer unit of the carboxylic acid-modified nitrile-based copolymer may be the same or different.

[0067] According to one embodiment of the present invention, the carboxylic acid-modified nitrile-based copolymer may contain the ethylenically unsaturated nitrile-based monomer units in an amount of 20 to 50% by weight, 20 to 45% by weight, or 25 to 40% by weight. Within this range, a molded article molded from a dip-molding latex composition containing the carboxylic acid-modified nitrile-based copolymer latex composition is flexible and has excellent wearability, oil resistance, and tensile strength.

[0068] According to one embodiment of the present invention, the ethylenically unsaturated acid monomer forming the ethylenically unsaturated acid monomer unit of the carboxylic acid-modified nitrile-based 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. Specific examples include at least one selected from the group consisting of ethylenically unsaturated carboxylic acid monomers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, and fumaric acid; polycarboxylic acid anhydrides such as maleic anhydride and citraconic anhydride; ethylenically unsaturated sulfonic acid monomers such as styrenesulfonic acid; and ethylenically unsaturated polycarboxylic acid partial ester monomers such as monobutyl fumarate, monobutyl maleate, and mono-2-hydroxypropyl maleate. More specifically, the ethylenically unsaturated acid monomer may be at least one selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, maleic acid, and fumaric acid, and even more specifically, methacrylic acid. The ethylenically unsaturated acid monomer may be used in the form of a salt, such as an alkali metal salt or ammonium salt, during polymerization. In this case, the ethylenically unsaturated acid monomer forming the ethylenically unsaturated acid monomer unit of the polymer and the ethylenically unsaturated acid monomer forming the ethylenically unsaturated acid monomer unit of the carboxylic acid-modified nitrile-based copolymer may be the same or different.

[0069] According to one embodiment of the present invention, the carboxylic acid-modified nitrile-based copolymer may contain 0.1 to 10% by weight, 0.5 to 9% by weight, or 1 to 8% by weight of repeating units derived from the ethylenically unsaturated acid monomer. Within this range, a molded article molded from a dip-molding latex composition containing the carboxylic acid-modified nitrile-based copolymer has excellent flexibility, comfort when worn, and tensile strength.

[0070] According to one embodiment of the present invention, the latex composition for dip molding is for dip molding using the carboxylic acid-modified nitrile-based copolymer latex, and may include a crosslinker composition for adjusting the pH of the carboxylic acid-modified nitrile-based copolymer latex and inducing crosslinking during dip molding. In this regard, the latex composition for dip molding according to the present invention includes the polymer composition, thereby improving the latex stability, particularly storage stability and low-temperature stability, of the latex composition for dip molding.

[0071] According to one embodiment of the present invention, the dip molding latex composition may contain 1 to 15 parts by weight of the polymer composition based on the solids content, relative to 100 parts by weight of the carboxylic acid-modified nitrile-based copolymer latex. Specifically, the polymer composition may be contained in an amount of 1 to 15 parts by weight, based on the solids content, relative to 100 parts by weight of the carboxylic acid-modified nitrile-based copolymer latex. The polymer composition may be contained in an amount of 1 to 15 parts by weight, 14 to 13 parts by weight, 12 to 11 parts by weight, 10 to 9 parts by weight, 8 to 7 parts by weight, 6 to 5 parts by weight, based on the solids content, relative to 100 parts by weight of the carboxylic acid-modified nitrile-based copolymer latex. Within this range, the wearing comfort and mechanical properties, such as tensile strength, of a molded article molded from the dip molding latex composition can be further improved.

[0072] According to one embodiment of the present invention, the crosslinking agent composition may be used to form crosslinked portions derived from the crosslinking agent in the carboxylic acid-modified nitrile-based copolymer through a crosslinking reaction.

[0073] According to one embodiment of the present invention, the crosslinker composition may include a vulcanizing agent and a vulcanization accelerator, and more specifically, may include a vulcanizing agent, a vulcanization accelerator, and zinc oxide.

[0074] According to one embodiment of the present invention, the vulcanizing agent is used to vulcanize the dip molding latex composition and may be sulfur, and specific examples thereof include 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 solids) of the total content of the carboxylic acid-modified nitrile-based copolymer in the dip molding latex composition. Within this range, excellent crosslinking ability upon vulcanization is achieved.

[0075] According to one embodiment of the present invention, the vulcanization accelerator is 2-mercaptobenzothiazole (MBT), 2,2-dithiobisbenzothiazole-2-sulfenamide (MBTS), N-cyclohexylbenzothiasole-2-sulfenamide (CBS), 2-morpholinothiobenzothiazole (MBS), tetramethylthiuram monosulfide (TMTM), tetramethylthiuram disulfide (TMTD), zinc diethyldithiocarbamate (ZDEC), zinc di-n-butyldithiocarbamate (ZDBC), or the like. 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 carboxylic acid-modified nitrile copolymer in the dip-molding latex composition. Within this range, excellent crosslinking ability by vulcanization is achieved.

[0076] According to one embodiment of the present invention, the zinc oxide may be a crosslinking agent that forms an ionic bond with a carboxy group of the carboxylic acid-modified nitrile copolymer in the dip-molding latex composition to form crosslinked moieties through ionic bonds within the carboxylic acid-modified nitrile copolymer or between carboxylic acid-modified nitrile copolymers. 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 solids) of the total content of the carboxylic acid-modified nitrile copolymer in the dip-molding latex composition. Within this range, excellent crosslinking ability, excellent latex stability, and excellent tensile strength and flexibility of the molded product produced can be achieved.

[0077] According to one embodiment of the present invention, the dip-molding latex composition may have a solids content (concentration) of 5 to 40% by weight, 8 to 35% by weight, or 10 to 33% by weight, which has the effects of providing excellent latex transport efficiency, preventing an increase in the viscosity of the latex, and providing excellent storage stability.

[0078] According to one embodiment of the present invention, the dip-molding latex composition may have a pH at 25°C of 9 to 12, 9 to 11, or 9.5 to 10.5. Within this range, excellent processability and productivity can be achieved during the production of dip-molded products. The pH of the dip-molding latex composition may be adjusted by adding the above-mentioned pH adjuster.

[0079] According to one embodiment of the present invention, the dip-molding latex composition may further contain additives such as a pigment such as titanium dioxide, a filler such as silica, a thickener, and a pH adjuster, if necessary.

[0080] The present invention provides a molded article. According to one embodiment of the present invention, the molded article may include a layer derived from the dip-molding latex composition. The molded article may be a dip-molded article produced by dip-molding the dip-molding latex composition, or may be a molded article including a layer derived from the dip-molding latex composition formed by dip-molding. A method for producing the molded article may include immersing the dip-molding latex composition by a direct immersion method, an anodic adhesion immersion method, a Teague adhesion immersion method, or the like. A specific example is the anodic adhesion immersion method, which has the advantage of producing a dip-molded article with a uniform thickness.

[0081] According to one embodiment of the present invention, the method for producing the molded product may include the steps of: attaching a coagulant to a dip-molding mold (S100); immersing the dip-molding mold with the coagulant attached thereto in a latex composition for dip-molding to form a layer derived from the latex composition for dip-molding, i.e., a dip-molded layer (S200); and heating the dip-molded layer to crosslink the latex composition for dip-molding (S300).

[0082] According to one embodiment of the present invention, step (S100) is a step of immersing the dip-forming mold in a coagulant solution to deposit the coagulant on the surface of the dip-forming mold. The coagulant solution may be a solution in which the coagulant is dissolved in water, alcohol, or a mixture thereof. The content of the coagulant in the coagulant solution may be 5% to 75%, 5% to 50%, or 10% to 40% by weight of the total content of the coagulant solution. The coagulant may be one or more 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. Specific examples include calcium chloride and calcium nitrate. According to one embodiment of the present invention, the step (S100) may further include a step of immersing the dip-forming mold in a coagulant solution for 5 seconds or more, removing the dip-forming mold, and then drying the dip-forming mold at 50°C to 150°C to adhere the coagulant to the dip-forming mold.

[0083] According to one embodiment of the present invention, the step (S200) may be a step of immersing a dip-forming mold having a coagulant attached thereto in the latex composition for dip-forming according to the present invention and then removing the dip-forming mold to form a dip-forming layer on the dip-forming mold. Also, according to one embodiment of the present invention, the immersion may be performed for 5 seconds or more to form a dip-forming layer on the dip-forming mold.

[0084] According to one embodiment of the present invention, step (S300) may be a step of heating a dip-molded layer formed in a dip mold to evaporate liquid components and crosslink and harden the dip-molded latex composition to obtain a dip-molded product. When the dip-molded latex composition according to the present invention is used, vulcanization of the crosslinker composition contained in the dip-molded latex composition and / or crosslinking via ionic bonds may be performed. 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, followed by second heating at 100°C to 180°C for 5 minutes to 30 minutes. After the first heating, the method may further include a step of leaching the dip-molded product by immersing the dip-molded product in water or warm water for 10 seconds to 10 minutes before the second heating.

[0085] According to one embodiment of the present invention, the molded article 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 healthcare product.

[0086] The present invention may be embodied in various different forms and should not be construed as limited to the embodiments set forth herein, although the present invention may be embodied in various different forms and should not be construed as limited to the embodiments set forth herein.

[0087] Examples and Comparative Examples Example 1 <Production of polymer composition> A 10 L high-pressure reactor equipped with a thermometer, a condenser, a nitrogen gas inlet, and inlets for continuous addition of monomers, emulsifiers, and polymerization initiators was used. After the 10 L high-pressure reactor was purged with nitrogen, 100 parts by weight of a monomer mixture consisting of 20 parts by weight of acrylonitrile, 60 parts by weight of 1,3-butadiene, and 20 parts by weight of methacrylic acid (based on a total content of 100 parts by weight of acrylonitrile, 1,3-butadiene, and methacrylic acid), 2.5 parts by weight of sodium dodecylbenzenesulfonate as an emulsifier, 3.5 parts by weight of t-dodecyl mercaptan as a molecular weight modifier, and 250 parts by weight of ion-exchanged water were added, and the internal temperature of the reactor was raised to 40°C. After the temperature increase 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 reached 95%, 1.0 part by weight of sodium dimethyldithiocarbamate was added to terminate the polymerization, producing a polymer latex containing a polymer. Next, potassium hydroxide was added to the polymer latex to adjust the pH to 8.5 at 25°C, and a deodorization process was performed to remove unreacted monomers, yielding a polymer composition.

[0088] <Production of latex composition for dip molding> To 100 parts by weight (solids basis) of a carboxylic acid-modified nitrile copolymer latex (LG Chem, NL105), 5 parts by weight (solids basis) of the polymer composition obtained above, 2 parts by weight of a 3 wt% potassium hydroxide aqueous solution, 1.5 parts by weight of a vulcanizing agent (Akron Dispersions, BOSTEX 378), 0.7 parts by weight of a vulcanization accelerator (Akron Dispersions, BOSTEX 497B), 1.5 parts by weight of zinc oxide (Akron Dispersions, BOSTEX 422), 1.0 part by weight of titanium dioxide (Akron Dispersions, BOSTEX 497D), and double-distilled water were added to prepare a dip molding latex composition having a solids content of 25 wt% and a pH of 10 at 25°C.

[0089] <Manufacturing of dip-molded products> 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 then dried at 80°C for 4 minutes to coat the coagulant on the hand-shaped mold.

[0090] Next, the hand-shaped mold coated with the coagulant was immersed in the dip-molding latex composition obtained above for 10 seconds, removed, dried at 80°C for 2 minutes, and immersed in water for 30 seconds for leaching. The mold was again crosslinked at 110°C for 20 minutes, and the crosslinked dip-molded layer was peeled off from the hand-shaped mold to obtain a glove-shaped dip-molded product.

[0091] Example 2 A polymer composition was obtained in the same manner as in Example 1, except that 15 parts by weight of acrylonitrile instead of 20 parts by weight, 70 parts by weight of 1,3-butadiene instead of 60 parts by weight, and 15 parts by weight of methacrylic acid instead of 20 parts by weight in preparing the polymer composition. A latex composition for dip molding and a dip-molded product were obtained using the polymer composition.

[0092] Example 3 A polymer composition was obtained in the same manner as in Example 1, except that 35 parts by weight of acrylonitrile instead of 20 parts by weight, 40 parts by weight of 1,3-butadiene instead of 60 parts by weight, and 25 parts by weight of methacrylic acid instead of 20 parts by weight in preparing the polymer composition. A latex composition for dip molding and a dip-molded product were obtained using the polymer composition.

[0093] Example 4 A polymer composition was obtained in the same manner as in Example 1, except that 6.0 parts by weight of t-dodecyl mercaptan was added instead of 3.5 parts by weight in preparing the polymer composition. A dip-molding latex composition and a dip-molded product were obtained using the polymer composition.

[0094] Example 5 A polymer composition was obtained in the same manner as in Example 1, except that 1.0 part by weight of t-dodecyl mercaptan was added instead of 3.5 parts by weight in preparing the polymer composition. A dip-molding latex composition and a dip-molded product were obtained using the polymer composition.

[0095] Example 6 A dip-molded product was obtained in the same manner as in Example 1, except that 10 parts by weight of the polymer composition was added instead of 5 parts by weight (based on solid content) when preparing the dip-molding latex composition.

[0096] Example 7 A dip-molded product was obtained in the same manner as in Example 1, except that 20 parts by weight of the polymer composition was added instead of 5 parts by weight (based on solid content) when preparing the dip-molding latex composition.

[0097] Example 8 A polymer composition was obtained in the same manner as in Example 1, except that 7.5 parts by weight of t-dodecyl mercaptan was added as a molecular weight modifier instead of 3.5 parts by weight in preparing the polymer composition. A latex composition for dip molding and a dip-molded product were obtained using the polymer composition.

[0098] Example 9 A polymer composition was obtained in the same manner as in Example 1, except that 0.85 parts by weight of t-dodecyl mercaptan was added as a molecular weight modifier instead of 3.5 parts by weight in preparing the polymer composition. A latex composition for dip molding and a dip-molded product were obtained using the polymer composition.

[0099] Example 10 A polymer composition was obtained in the same manner as in Example 1, except that 13 parts by weight of acrylonitrile instead of 20 parts by weight, 74 parts by weight of 1,3-butadiene instead of 60 parts by weight, and 13 parts by weight of methacrylic acid instead of 20 parts by weight in preparing the polymer composition. A latex composition for dip molding and a dip-molded product were obtained using the polymer composition.

[0100] Example 11 A polymer composition was obtained in the same manner as in Example 1, except that 33 parts by weight of acrylonitrile instead of 20 parts by weight, 37 parts by weight of 1,3-butadiene instead of 60 parts by weight, and 30 parts by weight of methacrylic acid instead of 20 parts by weight in preparing the polymer composition. A latex composition for dip molding and a dip-molded product were obtained using the polymer composition.

[0101] Comparative Example 1 A polymer composition was obtained in the same manner as in Example 1, except that 35 parts by weight of acrylonitrile instead of 20 parts by weight, 35 parts by weight of 1,3-butadiene instead of 60 parts by weight, and 30 parts by weight of methacrylic acid instead of 20 parts by weight in preparing the polymer composition. A latex composition for dip molding and a dip-molded product were obtained using the polymer composition.

[0102] Comparative Example 2 A polymer composition was obtained in the same manner as in Example 1, except that 10 parts by weight of acrylonitrile instead of 20 parts by weight, 80 parts by weight of 1,3-butadiene instead of 60 parts by weight, and 10 parts by weight of methacrylic acid instead of 20 parts by weight in preparing the polymer composition. A latex composition for dip molding and a dip-molded product were obtained using the polymer composition.

[0103] Comparative Example 3 The same procedure as in Example 1 was carried out, except that 0.5 parts by weight of t-dodecyl mercaptan was added instead of 3.5 parts by weight in preparing the polymer composition. However, the latex stability was reduced due to an increase in viscosity during polymerization, and the polymer composition could not be prepared.

[0104] Comparative Example 4 A polymer composition was obtained in the same manner as in Example 1, except that 10.0 parts by weight of t-dodecyl mercaptan was added instead of 3.5 parts by weight in preparing the polymer composition. A dip-molding latex composition and a dip-molded product were obtained using the polymer composition.

[0105] Comparative Example 5 A dip-molded product was obtained in the same manner as in Example 1, except that the polymer composition was not added during the preparation of the dip-molding latex composition.

[0106] Experimental example Experimental Example 1 For the polymer compositions prepared in Examples 1 to 11 and Comparative Examples 1 to 4, the glass transition temperatures and weight average molecular weights of the polymers were measured by the following methods, and the results are shown in Tables 1 to 3 below, together with the composition of each monomer added during the preparation of the polymer compositions, the amount of molecular weight modifier added, and the amount of polymer composition added during the preparation of the latex composition for dip molding.

[0107] *Glass transition temperature (Tg, °C): The polymer compositions prepared in Examples 1 to 11 and Comparative Examples 1 to 4 were dried in an oven at 130°C for 1 hour to prepare film-like samples. The glass transition temperature of approximately 1 mg of the prepared sample was measured by increasing the temperature from -70°C to 70°C at a heating rate of 20°C / min using a differential scanning calorimeter, DSC 2920, manufactured by TA Instruments.

[0108] *Weight average molecular weight (Mw, g / mol): The polymer compositions prepared in Examples 1 to 11 and Comparative Examples 1 to 4 were dried in a constant temperature and humidity chamber (25°C, relative humidity 50%) for 24 hours to obtain films, which were then dissolved in tetrahydrofuran (THF). Only the sol portion dissolved in tetrahydrofuran was obtained, and the weight average molecular weight was measured using gel permeation chromatography (GPC, Waters 2414 Refractive Index Detector with external column heater; Waters 1515 Isocractic pump, Waters 717 plus Autosampler) under the following conditions.

[0109] -Column: Agilent PL gel Mixed-B Solvent: THF -Flow rate: 1mL / min -Sample concentration: 1mg / mL -Injection volume: 10μL -Column temperature: 40℃ -Detector: Waters 2414 Refractive Index Detector with external column heater -Standard: Polystyrene

[0110] [Table 1]

[0111] [Table 2]

[0112] [Table 3]

[0113] As shown in Tables 1 to 3, it was confirmed that the polymers of the polymer compositions of Examples 1 to 11 according to the present invention exhibited the weight average molecular weights and glass transition temperatures defined in the present invention.

[0114] In contrast, it was confirmed that the polymer of the polymer composition of Comparative Example 1 had a glass transition temperature higher than the range defined by the present invention, and the polymer of the polymer composition of Comparative Example 2 had a glass transition temperature lower than the range defined by the present invention.

[0115] In Comparative Example 3, an attempt was made to prepare a polymer composition containing a polymer having a weight average molecular weight higher than the range defined in the present invention, but it was confirmed that the latex stability was reduced due to an increase in viscosity during polymerization, making it impossible to prepare the polymer composition. It was also confirmed that the polymer of the polymer composition of Comparative Example 4 had a weight average molecular weight lower than the range limited by the present invention.

[0116] Experimental Example 2 The low temperature stability of the dip-molding latex compositions prepared in Examples 1 to 11 and Comparative Examples 1 to 5, and the tensile strength, elongation, and modulus of the dip-molded products were measured by the following methods, and the results are shown in Tables 4 to 6 below.

[0117] *Low temperature stability (ppm): 2 parts by weight (based on solids) of the polymer compositions prepared in Examples 1 to 11 and Comparative Examples 1 to 5 were added to 100 parts by weight (based on solids) of a carboxylic acid-modified nitrile copolymer latex (LG Chem, NL105) and mixed at room temperature for 2 hours. After storing the mixture at -5°C for 24 hours, the amount of coagulated material produced was measured. The lower the measured coagulated material content, the better the low temperature stability.

[0118] *Tensile strength (MPa): Using the dip-molded products obtained in each Example and Comparative Example, dumbbell-shaped test pieces were prepared in accordance with ASTM D-412. Using the test pieces, a UTM (Universal Testing Machine) (manufactured by Instron, model name: 4466) was used to pull the test pieces at a crosshead speed of 500 mm / min in accordance with ASTM D638, and the point at which the test pieces broke was measured. The tensile strength was calculated using the following formula 2, and then converted into MPa units (1 MPa = 0.10197 kgf / mm 2 In this case, the higher the calculated tensile strength, the better the tensile properties.

[0119] [Formula 2] Tensile strength (kgf / mm2) = Load value (kgf) / (Thickness (mm) x Width (mm))

[0120] *Elongation (%): The test specimen prepared for measuring the tensile strength was stretched at a crosshead speed of 500 mm / min using a Universal Testing Machine (UTM) (Instron, Model 4466) in accordance with ASTM D638, and the location where the test specimen broke was measured, and the elongation was calculated using the following Equation 3. In this case, a higher calculated elongation indicates better tensile properties.

[0121] [Formula 3] Elongation rate (%) = (length of test piece after elongation / length of test piece before elongation) x 100

[0122] *500% modulus (MPa): Using a test piece manufactured for measuring the tensile strength, the test piece was stretched at a crosshead speed of 500 mm / min using a Universal Testing Machine (UTM) (Instron, model 4466) in accordance with ASTM D638, and the 500% modulus, which is the tensile strength when the test piece is stretched to 5 times its original length, was measured. The lower the measured 500% modulus, the softer the material and the better the wearing comfort.

[0123] [Table 4]

[0124] [Table 5]

[0125] [Table 6]

[0126] As shown in Tables 3 and 4, it was confirmed that the dip-molding latex compositions containing the polymer compositions of Examples 1 to 11 of the present invention have excellent low-temperature stability compared to the dip-molding latex composition of Comparative Example 5 which does not contain any polymer composition.

[0127] Moreover, it was confirmed that the dip-molded articles formed from the dip-molding latex compositions of Examples 1 to 11 of the present invention exhibited tensile strength, elongation and 500% modulus at levels equal to or higher than those of the dip-molded article formed from the dip-molding latex composition of Comparative Example 5.

[0128] In particular, it was confirmed that the latex compositions for dip molding of Examples 1 to 5 and Example 8 of the present invention and the dip-molded articles molded therefrom have excellent low-temperature stability and the tensile properties of the dip-molded articles are significantly improved because the latex compositions for dip molding contain the polymer composition in an appropriate amount.

[0129] On the other hand, it was confirmed that the dip-molded article molded from the dip-molding latex composition of Comparative Example 1 containing a polymer composition having a glass transition temperature higher than the range defined in the present invention was inferior in tensile properties and had a worse wearing comfort than Comparative Example 5.

[0130] In addition, it was confirmed that the dip-molded product molded from the dip-molding latex composition of Comparative Example 2 containing a polymer composition having a glass transition temperature lower than the range defined in the present invention had a significantly reduced tensile strength.

[0131] In addition, it was confirmed that the dip-molded product molded from the dip-molding latex composition of Comparative Example 4, which contains a polymer composition having a weight-average molecular weight lower than the range defined in the present invention, had poor tensile properties and wearing comfort.

[0132] From these results, it was confirmed that the polymer composition according to the present invention can be applied as a latex stabilizer for a dip molding latex composition, and that the latex stability, especially storage stability and low temperature stability, of a dip molding latex composition containing the polymer composition can be improved. In addition, it was confirmed that a molded product obtained therefrom has improved softness, excellent wearing comfort, and excellent tensile properties.

Claims

1. a polymer dispersed in a solvent; the polymer contains 40% by weight or more and 75% by weight or less of conjugated diene-based monomer units, 10% by weight or more and 45% by weight or less of ethylenically unsaturated nitrile-based monomer units, and 11% by weight or more and 50% by weight or less of ethylenically unsaturated acid monomer units, The polymer has a weight average molecular weight of 5,000 g / mol or more and 50,000 g / mol or less, and a glass transition temperature of -34°C or more and 33°C or less.

2. The polymer composition according to claim 1 , wherein the solvent is an aqueous solvent.

3. The polymer composition according to claim 1 , wherein the polymer has a weight average molecular weight of 7,000 g / mol or more and 46,000 g / mol or less.

4. 2. The polymer composition according to claim 1, wherein the polymer has a glass transition temperature of −28° C. or higher and 24° C. or lower.

5. The polymer composition according to claim 1, wherein the polymer composition has a pH at 25°C of 7.0 or more and 10.0 or less.

6. The method includes a step (S10) of emulsion-polymerizing a conjugated diene monomer, an ethylenically unsaturated nitrile monomer, and an ethylenically unsaturated acid monomer in a solvent to produce a polymer latex containing the polymer; The method for producing a polymer composition according to any one of claims 1 to 5, wherein the polymer polymerized in step (S10) has a weight average molecular weight of 5,000 g / mol or more and 50,000 g / mol or less and a glass transition temperature of -34°C or more and 33°C or less.

7. 7. The method for producing a polymer composition according to claim 6, wherein the emulsion polymerization in step (S10) is carried out by adding a molecular weight modifier in an amount of 0.8 parts by weight to 8.0 parts by weight based on 100 parts by weight of the total amount of monomers.

8. (S20) adding a pH adjuster to the polymer latex prepared in the (S10) step; and (S30) obtaining the polymer latex, the pH of which has been adjusted in the (S20) step, in an emulsion phase.

9. A polymer composition comprising a carboxylic acid-modified nitrile copolymer latex and the polymer composition according to any one of claims 1 to 5, The carboxylic acid-modified nitrile copolymer latex contains a carboxylic acid-modified nitrile copolymer, The carboxylic acid-modified nitrile copolymer is a latex composition for dip molding, which contains a conjugated diene monomer unit, an ethylenically unsaturated nitrile monomer unit, and an ethylenically unsaturated acid monomer unit.

10. 10. The latex composition for dip molding according to claim 9, wherein the polymer composition is contained in an amount of 1 part by weight to 15 parts by weight based on the solid content per 100 parts by weight based on the solid content of the carboxylic acid-modified nitrile-based copolymer latex.

11. A molded article comprising a layer derived from the dip molding latex composition described in claim 9.

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