KR102579024B1 - Method for preparing carboxylic acid modified-nitrile based copolymer latex - Google Patents

Abstract

In the present invention, in a reactor, a monomer mixture containing a conjugated diene monomer, an ethylenically unsaturated nitrile monomer, an ethylenically unsaturated acid monomer, and a water-soluble monomer is mixed with an oil-soluble initiator of 0.01 to 0.1 parts by weight based on a total of 100 parts by weight of the monomer mixture, and Initiating emulsion polymerization in the presence of water under conditions where the weight ratio (M/W) of the monomer mixture to water is 1.1 to 1.4 (S10); Controlling the weight ratio (M/W) to 0.8 to 1.0 by adding water when the polymerization conversion rate of the polymerization is 30 to 40% (S20); And a step (S30) of controlling the weight ratio (M/W) to 0.6 to 0.7 by adding water when the polymerization conversion rate of the polymerization is 60 to 70%, and the polymerization conversion rate of the polymerization is 10% or more and Provides a method for producing a carboxylic acid-modified nitrile-based copolymer latex in which 0.1 to 2.0 parts by weight of sodium naphthalene sulfonate formaldehyde condensate is added relative to the total 100 parts by weight of the monomer mixture when the content is less than 60%. do.

Description

Method for producing carboxylic acid-modified nitrile-based copolymer latex {METHOD FOR PREPARING CARBOXYLIC ACID MODIFIED-NITRILE BASED COPOLYMER LATEX}

The present invention relates to a method for producing carboxylic acid-modified nitrile-based copolymer latex, which uses an ethylenically unsaturated acid monomer and a water-soluble monomer, and improves the polymerization stability of the copolymer latex even under polymerization reaction conditions with a Reynolds number of 10,000 or more, thereby improving the working performance. The present invention relates to a technology for providing a latex composition for dip molding with excellent properties and manufacturing it therefrom and applying it to dip molded products with excellent tensile properties.

Disposable rubber gloves, which are used in a variety of ways in daily life such as housework, food industry, electronics industry, and medical field, are made through dip molding of natural rubber or carboxylic acid-modified nitrile-based copolymer latex. Recently, carboxylic acid-modified nitrile-based gloves have been in the spotlight in the disposable glove market due to allergic problems caused by the natural proteins of natural rubber and unstable supply and demand.

Meanwhile, there are various attempts to increase glove productivity to meet the increasing demand for gloves. The most common of these attempts is to maintain strength while making gloves thinner. In the past, disposable nitrile-based gloves weighing about 4 g were commonly used, but currently, gloves that are made as thin as 3 g and have a tensile strength of 6 N or more are required. In order to make such thin gloves, molded gloves are manufactured with low concentrations of coagulant and latex composition, in which case workability such as syneresis deteriorates.

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

Latex that has both high strength and excellent workability is required, but in reality, the strength and workability of gloves are in a trade-off relationship. What determines the strength and workability of gloves is the film formation speed of latex. If the film formation speed is fast, gloves have high strength but poor workability, and if the film formation speed is slow, gloves with excellent workability but low strength are produced. . Accordingly, there was a need for the development of carboxylic acid-modified nitrile-based copolymer latex that can secure high tensile strength even when made thin in a high-speed production line and has excellent workability.

In the prior art, this problem was attempted to be solved by preparing carboxylic acid-modified nitrile-based copolymer latex by adding some water-soluble monomers. However, in turbulent flow conditions where the polymerization reactor is large and the Reynolds number is 10,000 or more, water-soluble monomers and unsaturated carboxylic acid monomers cannot be used together. In this case, a large amount of water-soluble oligomers were formed, resulting in a decrease in polymerization stability, and a large amount of aggregates due to water-soluble oligomers were generated in the produced latex, making it unsuitable for use in the production of dip molded products. In other words, carboxylic acid-modified nitrile-based copolymer latex manufactured in industrial sites under conditions where the Reynolds number in the reactor exceeds 10,000 or more is practically impossible to apply to dip molded products.

KR 2016-0127008 A

The problem to be solved by the present invention is to solve the problems mentioned in the background technology of the above invention, by using ethylenically unsaturated acid monomers and water-soluble monomers, and by producing copolymer latex even under polymerization reaction conditions where the Reynolds number is 10,000 or more. The purpose is to manufacture a latex composition for dip molding with improved polymerization stability and excellent workability, and to apply it to dip molded products with excellent tensile properties.

According to one embodiment of the present invention for solving the above problem, in a reactor, a monomer mixture including a conjugated diene monomer, an ethylenically unsaturated nitrile monomer, an ethylenically unsaturated acid monomer, and a water-soluble monomer is added to the monomer mixture. Initiating emulsion polymerization in the presence of 0.01 to 0.1 parts by weight of an oil-soluble initiator and water based on a total of 100 parts by weight, under the condition that the weight ratio (M/W) of the monomer mixture to water is 1.1 to 1.4 (S10); Controlling the weight ratio (M/W) to 0.8 to 1.0 by adding water when the polymerization conversion rate of the polymerization is 30 to 40% (S20); And a step (S30) of controlling the weight ratio (M/W) to 0.6 to 0.7 by adding water when the polymerization conversion rate of the polymerization is 60 to 70%, and the polymerization conversion rate of the polymerization is 10% or more and Provides a method for producing a carboxylic acid-modified nitrile-based copolymer latex in which 0.1 to 2.0 parts by weight of sodium naphthalene sulfonate formaldehyde condensate is added relative to the total 100 parts by weight of the monomer mixture when the content is less than 60%. do.

The method for producing carboxylic acid-modified nitrile-based copolymer latex according to the present invention uses ethylenically unsaturated acid monomers and water-soluble monomers, and the polymerization stability of the copolymer latex is improved even under polymerization reaction conditions with a Reynolds number of 10,000 or more, improving workability. This latex composition for dip molding can be manufactured, and a dip molded product with excellent tensile properties can be provided.

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

In the present invention, the term 'copolymer' may include all copolymers formed by copolymerizing comonomers, and as specific examples, may include both random copolymers and block copolymers.

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

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

In the present invention, the term 'alkyl' refers to a linear or branched saturated monovalent hydrocarbon of carbon atoms, such as methyl, ethyl, propyl, 2-propyl, n-butyl, iso-butyl, tert-butyl, pentyl, hexyl, dodecyl, etc. It may mean that it includes not only unsubstituted ones but also those substituted by substituents.

In the present invention, the term '(meth)acrylate' may mean that both acrylate and methacrylate are possible.

In the present invention, the term 'Reynolds number' is a dimensionless number used to predict the flow of fluid in a pipe, and is expressed as the ratio of the force due to inertia and the force due to viscosity according to Equation 1 below. You can.

[Equation 1]

Re=Vs(d/ν)

* Vs is the average flow velocity in the pipe (m/s), d is the inner diameter of the pipe (m), and ν is the dynamic viscosity coefficient of the fluid (m ² /s).

* Re ≤ 2,320 means laminar flow, and Re > 2,320 means turbulent flow.

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

According to the present invention, a method for producing carboxylic acid-modified nitrile-based copolymer latex is provided. The production method includes, in a reactor, a monomer mixture containing a conjugated diene monomer, an ethylenically unsaturated nitrile monomer, an ethylenically unsaturated acid monomer, and a water-soluble monomer, and a fat-soluble monomer mixture of 0.01 to 0.1 parts by weight based on a total of 100 parts by weight of the monomer mixture. Initiating emulsion polymerization in the presence of an initiator and water under the condition that the weight ratio (M/W) of the monomer mixture to water is 1.1 to 1.4 (S10); Controlling the weight ratio (M/W) to 0.8 to 1.0 by adding water when the polymerization conversion rate of the polymerization is 30 to 40% (S20); And a step (S30) of controlling the weight ratio (M/W) to 0.6 to 0.7 by adding water when the polymerization conversion rate of the polymerization is 60 to 70%, and the polymerization conversion rate of the polymerization is 10% or more and When the content is less than 60%, 0.1 to 2.0 parts by weight of sodium naphthalene sulfonate formaldehyde condensate may be added based on 100 parts by weight of the monomer mixture.

Generally, as the volume of the batch reactor used in industrial sites and the size of the impeller of the stirrer are increased to improve productivity, the reaction system within the reactor is placed in an unsteady state beyond the steady state. As a result, the Reynolds number (Re) for the flow of fluid in the reactor has a high value ranging from more than 10,000 to hundreds of thousands, forming a turbulent flow.

On the other hand, in emulsion polymerization, when an emulsifier exceeding the critical micelle concentration (CMC) is added, polymerization of monomers proceeds within micelles formed by the emulsifier. As in the past, it is manufactured using carboxylic acid-modified nitrile-based copolymer latex. When water-soluble monomers are included in the copolymer to improve the strength and workability of the molded product, the proportion of monomers with high water solubility increases, so that polymerization occurs to a certain extent not only inside the micelle but also in the water phase.

As described above, when the diffusion rate of monomers increases due to the formation of turbulent flow in a reactor with a Reynolds number of 10,000 or more, the formation of water-soluble oligomers is promoted due to rapid polymerization of ethylenically unsaturated acid monomers and water-soluble monomers within micelles. In addition, the polymerization reaction rate of the monomers dissolved in the water phase increases. When the water-soluble monomers reach a size that they can no longer dissolve in water due to the rapid polymerization reaction, they clump together to form a large amount of water-soluble oligomers in the water phase. It is adsorbed to the formed polymer particles and polymerization proceeds. In particular, in a situation where the fluidity of the polymer chain is high because the conjugated diene monomer does not crosslink at the beginning of the polymerization reaction, the water-soluble oligomers have a strong tendency to exist on the surface of the polymer particles in order to maintain a thermodynamically stable state. As a result, the hydrophilicity of the polymer particles increases, the adsorption capacity for the hydrophobic part of the emulsifier decreases, and polymer particles having the hydrophilic surface agglomerate with each other. However, in this case, the final copolymer latex contains a large amount of aggregates, making it unsuitable for use in the production of dip molded products.

As described above, in order to solve the problems that occur when water-soluble monomers are used together during the polymerization of a copolymer containing an ethylenically unsaturated acid monomer in a reactor with a Reynolds number of 10,000 or more, in the present invention, as described above, At the start of polymerization, an oil-soluble initiator is used, and sodium naphthalene sulfonate formaldehyde condensation polymer (hereinafter referred to as condensation polymer) is added when the polymerization conversion rate is 10% or more and less than 60%, and the polymerization conversion rate is 30 to 30% before the start of polymerization. By adding water at 40% and 60 to 70%, the polymerization stability is improved by lowering the aggregate content in the copolymer latex, and the workability of the dip molding composition containing the copolymer latex and the strength of the dip molded product are improved. Everything can be improved.

Meanwhile, for example, the oil-soluble initiator is not added at the start of polymerization, the condensation polymer is not added when the polymerization conversion rate is 10% or more and less than 60%, or even if the condensation polymer is added, the time of addition is when the polymerization conversion rate is 60%. or more, or the weight ratio (M/W) (weight ratio of the monomer mixture to the total weight of water) before the start of polymerization and when the polymerization conversion rate is 30 to 40% and 60 to 70% is outside the appropriate range. In this case, the polymerization stability of the copolymer latex may decrease, the workability of the composition for dip molding containing the copolymer latex may decrease, or the tensile properties of the dip molded product may decrease.

According to one embodiment of the present invention, in the step (S10), a monomer mixture including a conjugated diene monomer, an ethylenically unsaturated nitrile monomer, an ethylenically unsaturated acid monomer, and a water-soluble monomer is added in a total of 100 parts by weight of the monomer mixture. Initiating emulsion polymerization in the presence of 0.01 to 0.1 parts by weight of an oil-soluble initiator and water, but controlling the weight ratio (M/W) of the monomer mixture to water to 1.1 to 1.4, controlling the content of monomers in the monomer mixture. By doing so, the physical properties of the carboxylic acid-modified nitrile-based copolymer can be adjusted.

The conjugated diene monomers include 1,3-butadiene, 1,4-butadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 1,3-pentadiene, piperylene, It may include one or more selected from the group consisting of 3-butyl-1,3-octadiene, 2-phenyl-1,3-butadiene, and isoprene. As a specific example, the conjugated diene monomer is 1,3-butadiene. It can be.

The content of the conjugated diene-based monomer may be 40 to 70% by weight, 50 to 68% by weight, or 60 to 65% by weight based on the total content of the monomer mixture, and within this range, it is prepared from a carboxylic acid-modified nitrile-based copolymer. Not only is the oil resistance and tensile strength of the molded product excellent, but it also improves flexibility and comfort.

The ethylenically unsaturated nitrile-based monomer may include one or more selected from the group consisting of acrylonitrile, methacrylonitrile, α-chloronitrile, and α-cyanoethylacrylonitrile. Specific examples include the ethylene The sexually unsaturated nitrile-based monomer may be acrylonitrile.

The content of the ethylenically unsaturated nitrile-based monomer may be 20 to 40% by weight, 25 to 35% by weight, or 28 to 30% by weight based on the total content of the monomer mixture, and within this range, the carboxylic acid-modified nitrile-based copolymer Molded products manufactured from it not only have excellent oil resistance and tensile strength, but also improve flexibility and wearing comfort.

The ethylenically unsaturated acid monomer 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 ethylenically unsaturated acid monomers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, and fumaric acid; polyanhydrides such as maleic anhydride and citraconic anhydride; ethylenically unsaturated sulfonic acid monomers such as styrene sulfonic acid; It may include one or more selected from the group consisting of ethylenically unsaturated polycarboxylic acid partial ester monomers such as monobutyl fumarate, monobutyl maleate, and mono-2-hydroxypropyl maleate, and more specific examples include acrylic acid, It may include one or more selected from the group consisting of methacrylic acid, itaconic acid, maleic acid, and fumaric acid, and a more specific example may be methacrylic acid. During polymerization, the ethylenically unsaturated acid monomer may be used in the form of a salt such as an alkali metal salt or ammonium salt.

The content of the ethylenically unsaturated acid monomer may be 4 to 10% by weight, 5 to 9% by weight, or 6 to 8% by weight based on the total content of the monomer mixture, and within this range, from the carboxylic acid-modified nitrile-based copolymer Not only does the manufactured molded product have excellent tensile strength, but it also improves flexibility and comfort.

The water-soluble monomers include 2-hydroxy ethyl methacrylate, 2-hydroxy propyl methacrylate, 3-hydroxy propyl methacrylate, 2-hydroxy ethyl acrylate, 2-hydroxy propyl acrylate and 3-hydroxy propyl acrylate. hydroxy alkyl (meth)acrylates, including oxypropyl acrylate; and acrylamide. As a specific example, the water-soluble monomer may be 2-hydroxy ethyl methacrylate.

The content of the water-soluble monomer may be 0.5 to 10% by weight, 1.0 to 5% by weight, or 1.5 to 2.0% by weight based on the total content of the monomer mixture, and within this range, the polymerization stability of the copolymer latex is improved, and Not only is the workability of the dip molding composition containing the carbonic acid-modified nitrile-based copolymer latex improved, but the tensile strength of the molded article manufactured from the carboxylic acid-modified nitrile-based copolymer is excellent.

The fat-soluble initiator may include one or more selected from the group consisting of cumene hydroperoxide, benzoyl peroxide, dibutyl peroxide, dicumyl peroxide, and lauroyl peroxide. As a specific example, the fat-soluble initiator is cumene hydroperoxide. It may be roperoxide.

In the method for producing a carboxylic acid-modified nitrile-based copolymer according to the present invention, the addition of the oil-soluble initiator has the effect of imparting hydrophobicity to the polymer particles formed during the polymerization process to facilitate adsorption of the emulsifier.

The content of the oil-soluble initiator may be 0.01 to 0.1 parts by weight, 0.03 to 0.08 parts by weight, or 0.05 to 0.06 parts by weight, based on a total of 100 parts by weight of the monomer mixture. Specifically, when the content of the oil-soluble initiator is 0.01 parts by weight or more based on a total of 100 parts by weight of the monomer mixture, it has the effect of improving stability without significantly affecting the polymerization rate, and when it is 0.1 part by weight or less, it has the effect of improving stability within the particles. Polymerization progresses significantly and stability is improved.

Additionally, the oil-soluble initiator may be added together with an initiation activator, and in this case, the adsorption effect of the emulsifier on the polymer particles due to the oil-soluble initiator can be further improved.

In addition, the oil-soluble initiator can be used together with a water-soluble initiator to control the speed of the polymerization reaction. In this case, the total content of the oil-soluble initiator and the water-soluble initiator is 0.5 parts by weight or less, 0.4 parts by weight based on 100 parts by weight of the monomer mixture. It may be less than or equal to 0.3 parts by weight, and by appropriately controlling the speed of the polymerization reaction within this range, there is an effect of improving polymerization stability by controlling the production of water-soluble oligomers in the copolymer latex.

The water-soluble initiator may include one or more selected from the group consisting of sodium persulfate, potassium persulfate, and ammonium persulfate, and a specific example may be potassium persulfate.

Polymerization in the (S10) step may be initiated under the condition that the weight ratio (M/W) of the monomer mixture to water is 1.1 to 1.4. Typically, in the case of a reactor with a Reynolds number of 10,000 or more, there is an induction period that temporarily induces polymerization in the micelle at the beginning of the reaction by introducing oxygen along with the reactants. As described above, at the start of polymerization By operating under conditions where the weight ratio (M/W) is 1.1 to 1.4, it has the effect of reducing the formation of water-soluble oligomers occurring in the aqueous phase by controlling the polymerization that proceeds rapidly in the aqueous phase rather than the polymerization reaction in the micelle. . Through this, polymerization stability at the beginning of polymerization can be improved.

According to one embodiment of the present invention, the (S20) step is a step of controlling the weight ratio (M/W) to 0.8 to 1.0 by adding water when the polymerization conversion rate of the polymerization is 30 to 40%. The means for controlling the weight ratio (M/W) is adding water, as specified above. That is, control of the weight ratio (M/W) in the (S20) step and the subsequent (S30) step may be controlled by adding water.

Specifically, as described above, there is an induction period at the beginning of the reaction, but when the polymerization conversion rate reaches 30 to 40%, the production rate of water-soluble oligomer and the heat of polymerization reach their highest points. At this time, the weight ratio By reducing the (M/W) to 0.8 to 1.0, which is relatively lower than the (S10) step, the effective concentration of the emulsifier (the concentration of the emulsifier that can cause the formation of micelles) is reduced, thereby forming micelles that generate water-soluble oligomers. It can deteriorate. As a result, the production of water-soluble oligomers is reduced, thereby improving polymerization stability.

The sodium naphthalene sulfonate formaldehyde condensate is prepared by sulfonation of naphthalene with sulfuric acid (step a) through Scheme 1 below, and then polycondensation in the presence of formaldehyde (b). Step) It may be a condensation polymer formed, and the repeating unit (n) of the condensation polymer may be 2 to 30, 2 to 20, or 2 to 10.

[Scheme 1]

In the method for producing a carboxylic acid-modified nitrile-based copolymer according to the present invention, adding the sodium naphthalene sulfonate formaldehyde condensation polymer has the effect of lowering the viscosity in the section where the viscosity increases rapidly.

The amount of the condensation polymer added may be 0.1 to 2.0 parts by weight, 0.3 to 0.7 parts by weight, or 0.5 to 0.6 parts by weight based on a total of 100 parts by weight of the monomer mixture, and within this range, the viscosity of the carboxylic acid-modified nitrile-based copolymer latex is It can be easily controlled in the manufacture of dip molded products, and prevents the color of the molded product from darkening, resulting in an excellent appearance. Specifically, when the amount of the condensation polymer added is 0.1 parts by weight or more based on a total of 100 parts by weight of the monomer mixture, latex coagulum is reduced, and when the amount is 2.0 parts by weight or less, the viscosity is reduced.

In addition, the condensation polymer may be added in batches, divided doses, or continuously when the polymerization conversion rate is 10% or more and less than 60%.

The time point when the polymerization conversion rate is 30 to 40%, the time point when it is 10% or more and less than 60%, respectively, is the time point when the polymerization conversion rate is 30 to 40% for 100 parts by weight of the monomer mixture prepared in the step (S10), and 10%. It may mean a point in time of % or more and less than 60%.

Meanwhile, according to one embodiment of the present invention, the polymerization conversion rate is determined by collecting a certain amount of sample from the reactant at regular time intervals, calculating the TSC (Total Solid Content) of the sample, and substituting this into Equation 2 below: It may have been calculated.

[Equation 2]

Polymerization conversion rate (%)= {(TSC ⅹ W _t,t - W _t,s )/ W _t,m } ⅹ 100

* TSC: Weight of dried sample solids/Weight of sample before drying

* W _t,t : Sum of weight of monomer, water and auxiliary materials added during polymerization

* W _t,s : Sum of weight of additives other than monomer and water during polymerization

* W _t,m : Sum of the weight of monomers added during polymerization

* Auxiliary materials: Additives such as emulsifiers, initiators, and molecular weight regulators, excluding monomers and water added during polymerization.

According to one embodiment of the present invention, the (S30) step is a step of controlling the weight ratio (M/W) to 0.6 to 0.7 by adding water when the polymerization conversion rate of the polymerization is 60 to 70%.

Specifically, the point in time when the polymerization conversion rate is 60 to 70% is the time when the conjugated diene monomer swells within the polymer particles and the particle surface area becomes very large. At this time, the weight ratio (M/W) is relatively low compared to the (S20) step. By controlling it to a low level of 0.6 to 0.7, polymerization stability is improved.

In addition, by gradually lowering the weight ratio (M/W) according to the polymerization conversion rate, polymerization stability is improved and water-soluble oligomers containing carboxylic acid monomers can be easily formed on the surface of the final copolymer particles. In this case, the carboxylic acid on the surface of the copolymer particle and the ionic crosslinking component contained in the latex composition for dip molding can effectively form an ionic bond to improve the strength of the molded article, and at the same time, provide an appropriate adhesive to the surface of the copolymer particle. By forming a hydration layer in the latex composition for dip molding by water-soluble oligomers present in proportion, excellent syneresis properties are achieved.

According to one embodiment of the present invention, when the polymerization conversion rate of the polymerization is 10% or more and less than 60%, 0.1 to 2.0 parts by weight of the condensation polymer may be added based on a total of 100 parts by weight of the monomer mixture. Specifically, when the polymerization conversion rate is 60% or more, the number of monomer droplets gradually decreases, and a decrease in polymerization stability can be prevented by adding the condensation polymer before that. That is, when the condensation polymer is added at a time when the polymerization conversion rate is less than 60%, polymerization stability can be improved by adding the condensation polymer before the monomer droplets are reduced. In addition, when the condensation polymer is added at a time when the polymerization conversion rate is 10% or more, the diffusion rate of the monomer is less affected.

According to one embodiment of the present invention, the emulsion polymerization may be carried out in the presence of ion exchange water, an emulsifier, a polymerization initiator, a molecular weight regulator, etc.

According to one embodiment of the present invention, during the polymerization, water may be used as ion exchange water, and the amount added may be the same as the amount mentioned above.

According to one embodiment of the present invention, the emulsifier may be at least one selected from the group consisting of anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants, and specific examples include alkylbenzene sulfonate, It may be one or more anionic surfactants selected from the group consisting of aliphatic sulfonates, higher alcohol sulfuric acid ester salts, α-olefin sulfonate salts, and alkyl ether sulfuric acid ester salts. In addition, the emulsifier may be added in an amount of 0.3 to 10 parts by weight, 0.8 to 8 parts by weight, or 1.5 to 6 parts by weight based on 100 parts by weight of the monomer mixture, and polymerization is limited within this range. This is excellent and the amount of foam generated is small, which makes it easy to manufacture molded products.

According to one embodiment of the present invention, when the polymerization is carried out including a molecular weight regulator, specific examples of the molecular weight regulator include α-methylstyrenedimer, t-dodecyl mercaptan, n-dodecyl mercaptan, and octyl. Mercaptans such as mercaptan; Halogenated hydrocarbons such as carbon tetrachloride, methylene chloride, and methylene bromide; It may include sulfur-containing compounds such as tetraethylthiuram disulfide, dipentamethylenethiuram disulfide, and diisopropylxanthogen disulfide. These molecular weight regulators can be used individually or in combination of two or more types. As a specific example, the above mercaptans can be used, and as a more specific example, the t-dodecyl mercaptan can be used. In addition, the molecular weight regulator may be added in an amount of 0.1 to 2 parts by weight, 0.2 to 1.5 parts by weight, or 0.3 to 1 part by weight based on 100 parts by weight of the monomer mixture, and polymerization stability is within this range. It is excellent, and when manufacturing molded products after polymerization, the physical properties of the molded products are excellent.

According to one embodiment of the present invention, the type and amount of the polymerization initiator may be the same as the type and amount of the oil-soluble initiator and the water-soluble initiator mentioned above.

According to one embodiment of the present invention, in addition to the above composition, if necessary, an activator, chelating agent, dispersant, pH adjuster, deoxidizer, particle size adjuster, anti-aging agent, antioxidant, and anti-foaming agent within the range that does not deteriorate the physical properties of the copolymer. and additives such as oxygen scavengers can be additionally added.

According to one embodiment of the present invention, the emulsion polymerization may be performed at a polymerization temperature of 10 to 90 °C, more specifically 20 to 75 °C.

According to one embodiment of the present invention, the emulsion polymerization reaction may be terminated when the polymerization conversion rate is 90% or more, or 93% or more. Termination of the polymerization reaction can be performed by adding a polymerization inhibitor, pH adjuster, and antioxidant. In addition, the copolymer latex finally obtained after the reaction can be used after removing unreacted monomers through a normal deodorizing concentration process.

According to the present invention, a latex composition for dip molding comprising the carboxylic acid-modified nitrile-based copolymer latex according to the present invention is provided. The latex composition for dip molding according to the present invention may include the carboxylic acid-modified nitrile-based copolymer latex and a crosslinking agent composition.

According to one embodiment of the present invention, the crosslinking agent composition may include a vulcanizing agent, a vulcanization accelerator, and a metal oxide, and as a specific example, it may include a vulcanizing agent, a vulcanization accelerator, and zinc oxide.

The vulcanizing agent is used to vulcanize the latex composition for dip molding, and may be sulfur. Specific examples may 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 parts by weight to 10 parts by weight, or 1 part by weight to 5 parts by weight, based on 100 parts by weight (based on solid content) of the carboxylic acid-modified nitrile-based copolymer latex in the latex composition for dip molding. , Within this range, the crosslinking ability by vulcanization is excellent.

In addition, the vulcanization accelerator is 2-mercaptobenzothiazole (MBT, 2-mercaptobenzothiazole), 2,2-dithiobisbenzothiazole-2-sulfenamide (MBTS, 2,2-dithiobisbenzothiazole-2-sulfenamide), N -Cyclohexylbenzothiazole-2-sulfenamide (CBS, N-cyclohexylbenzothiasole-2-sulfenamide), 2-morpholinothiobenzothiazole (MBS, 2-morpholinothiobenzothiazole), tetramethylthiuram monosulfide (TMTM, tetramethylthiuram monosulfide), tetramethylthiuram disulfide (TMTD), zinc diethyldithiocarbamate (ZDEC), zinc di-n-butyldithiocarbamate (ZDBC) ), diphenylguanidine (DPG), and di-o-tolylguanidine (di-o-tolylguanidine). The content of the vulcanization accelerator may be 0.1 parts by weight to 10 parts by weight or 0.5 parts by weight to 5 parts by weight based on 100 parts by weight (based on solid content) of the carboxylic acid-modified nitrile-based copolymer latex in the latex composition for dip molding, Within this range, the crosslinking ability by vulcanization is excellent.

In addition, the metal oxide may include zinc oxide, magnesium oxide, aluminum oxide, etc., and forms an ionic bond with the functional group of the ethylenically unsaturated acid monomer of the carboxylic acid-modified nitrile-based copolymer in the latex composition for dip molding, It may be a crosslinking agent for forming a crosslinking portion through ionic bonding within the carboxylic acid-modified nitrile-based copolymer or between carboxylic acid-modified nitrile-based copolymers. The content of the metal 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 carboxylic acid-modified nitrile-based copolymer latex in the latex composition for dip molding. , Within this range, the crosslinking ability is excellent, latex stability is excellent, and the tensile strength and flexibility of the manufactured dip molded product are excellent.

According to one embodiment of the present invention, the latex composition for dip molding may have a solid content (concentration) of 5% by weight to 40% by weight, 8% by weight to 35% by weight, or 10% by weight to 30% by weight. Within this range, the efficiency of latex transportation is excellent, and an increase in latex viscosity is prevented, resulting in excellent storage stability.

As another example, the latex composition for dip molding may have a pH of 9 to 12, 9 to 11.5, or 9.5 to 11, and within this range, it has excellent processability and productivity when manufacturing dip molded products. The pH of the latex composition for dip molding can be adjusted by adding the pH adjuster described above. For example, the pH adjuster may be an aqueous solution of potassium hydroxide at a concentration of 1% to 5% by weight, or aqueous ammonia at a concentration of 1% to 5% by weight.

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

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

The molded product manufacturing method for molding the molded product may include the step of immersing the latex composition for dip molding by a direct immersion method, an anode adhesion immersion method, a Teague adhesion immersion method, etc., and specific examples include anode adhesion immersion method. It can be carried out by the adhesion dipping method, and in this case, there is an advantage in obtaining dip molded products of uniform thickness.

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

The step (S100) is a step of attaching the coagulant to the surface of the dip mold by immersing the dip mold in a coagulant solution to form a coagulant in the dip mold. The coagulant solution adds the coagulant to water, alcohol, or a mixture thereof. As a dissolved solution, the content of the coagulant in the coagulant solution may be 5% to 75% by weight, 10% to 65% by weight, or 13% to 55% by weight based on the total content of the coagulant solution.

The coagulant may include, for example, metal halides such as barium chloride, calcium chloride, magnesium chloride, zinc chloride, and aluminum chloride; nitrates such as barium nitrate, calcium nitrate and zinc nitrate; Acetate salts such as barium acetate, calcium acetate and zinc acetate; and sulfate such as calcium sulfate, magnesium sulfate, and aluminum sulfate. Specific examples may include calcium chloride or calcium nitrate.

In addition, the step (S100) may further include immersing the dip molding mold in a coagulant solution for more than 1 minute, taking it out, and drying it at 70 to 150° C. in order to attach the coagulant to the dip molding mold.

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

In addition, in the step (S200), immersion may be performed for 1 minute or more in order to form a dip molding layer in the dip molding mold.

In addition, the step (S300) may be a step in which liquid components are evaporated by heating the dip molding layer formed in the dip molding mold to obtain a dip molding product, and curing is performed by crosslinking the latex composition for dip molding. At this time, when using the latex composition for dip molding according to the present invention, vulcanization and/or crosslinking by ionic bonding of the vulcanizing agent and/or crosslinking agent contained in the latex composition for dip molding may be performed. In addition, according to one embodiment of the present invention, the heating is performed by first heating at 70 ℃ to 150 ℃ for 1 to 10 minutes, and then secondary heating at 100 ℃ to 180 ℃ for 5 to 30 minutes. You can.

Thereafter, the dip molded layer crosslinked by heat treatment can be peeled off from the dip mold to obtain a dip molded product.

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

Hereinafter, the present invention will be described in more detail through examples. However, the following examples are intended to illustrate the present invention, and it is obvious to those skilled in the art that various changes and modifications are possible within the scope and spirit of the present invention, and the scope of the present invention is not limited to these alone.

<Example>

When preparing the carboxylic acid-modified nitrile-based copolymer latex composition, the stirring speed was adjusted so that the diameter of the stirrer in the polymerization reactor was 150 mm and the tip speed of the stirrer was 4 m/s, and the Reynolds number (Re) at this time was approximately It was 20,000. Hereinafter, all polymerization reactions in Examples and Comparative Examples were conducted under the same conditions.

Example 1

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

(1) Polymerization initiation step (S10)

In a polymerization reactor, a monomer mixture consisting of 29.5% by weight of acrylonitrile, 63% by weight of 1,3-butadiene, 6.0% by weight of methacrylic acid, and 1.5% by weight of 2-hydroxy ethyl acrylate, with respect to 100 parts by weight of the monomer mixture. After adding 0.5 parts by weight of t-dodecyl mercaptan, 2.5 parts by weight of sodium dodecyl benzenesulfonate, 0.25 parts by weight of potassium persulfate, 0.05 parts by weight of cumene hydroperoxide, 0.01 parts by weight of initiation activator, and 90 parts by weight of water, the mixture was heated at 37°C. Polymerization was initiated at a temperature of .

(2) First addition of water and input of condensation polymer (S20)

When the polymerization conversion rate reached 10%, 0.5 parts by weight of sodium naphthalene sulfonate formaldehyde condensation polymer (hereinafter referred to as condensation polymer) was added, and when the polymerization conversion rate reached 35%, 30 parts by weight of water were added, and then polymerized. was carried out subsequently.

(3) Secondary addition of water (S30)

When the polymerization conversion rate reached 63%, 40 parts by weight of water was added, and when the polymerization conversion rate reached 95%, 0.3 parts by weight of ammonium hydroxide was added to stop the polymerization. Afterwards, unreacted substances were removed through a deodorization process, and ammonia water, antioxidants, and antifoaming agents were added to obtain carboxylic acid-modified nitrile-based copolymer latex with a solid content of 45% and pH 8.5.

<Manufacture of latex composition for dip molding>

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

<Manufacture of dip molded products>

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

Next, the hand-shaped ceramic mold coated with the coagulant was dipped into the obtained dip molding latex composition for 1 minute, pulled up, dried at 80° C. for 1 minute, and then immersed in water for 3 minutes. The mold was dried again at 80°C for 1 minute and then crosslinked at 125°C for 20 minutes. Afterwards, the crosslinked dip molded layer was peeled off from the hand-shaped mold to produce a glove-shaped dip molded product.

Example 2

In preparing the carboxylic acid-modified nitrile-based copolymer latex of Example 1, except that 72 parts by weight of water was added instead of 90 parts by weight in step (S10), and 45 parts by weight of water was added instead of 40 parts by weight in step (S30). Then, it was carried out in the same manner as Example 1.

Example 3

When preparing the carboxylic acid-modified nitrile-based copolymer latex of Example 1, except that 0.5 parts by weight of the condensation polymer in step (S20) was added when the polymerization conversion rate reached 50%, rather than 10%. It was carried out in the same manner as Example 1.

Example 4

When preparing the carboxylic acid-modified nitrile-based copolymer latex of Example 1, 0.3 parts by weight of the condensation polymer in step (S20) was added when the polymerization conversion rate reached 20%, not 10%, and added at 50%. It was carried out in the same manner as Example 1, except that 0.2 parts by weight was added when it was reached.

Example 5

When preparing the carboxylic acid-modified nitrile-based copolymer latex of Example 1, the point of introduction of the condensation polymer in step (S20) was not 10%, but 0.5 weight from when the polymerization conversion rate reached 10% to when it reached 40%. It was carried out in the same manner as Example 1, except that a certain amount of water was continuously added.

<Comparative example>

Comparative Example 1

When preparing the carboxylic acid-modified nitrile-based copolymer latex of Example 1, in step (S10), water-soluble monomers were not included in the monomer mixture, and 30% by weight of acrylonitrile, 64% by weight of 1,3-butadiene, and methacryl The same method as Example 1 was carried out, except that a monomer mixture consisting of 6% by weight of acid was used.

Comparative Example 2

When preparing the carboxylic acid-modified nitrile-based copolymer latex of Example 1, it was carried out in the same manner as Example 1, except that 0.05 parts by weight of cumene hydroperoxide was not added in step (S10).

Comparative Example 3

When preparing the carboxylic acid-modified nitrile-based copolymer latex of Example 1, the same method as Example 1 was performed, except that 0.5 parts by weight of the condensation polymer was not added in step (S20).

Comparative Example 4

When preparing the carboxylic acid-modified nitrile-based copolymer latex of Example 1, except that 0.5 parts by weight of the condensation polymer in step (S20) was added when the polymerization conversion rate reached 65%, not 10%. was carried out in the same manner as Example 1.

Comparative Example 5

When preparing the carboxylic acid-modified nitrile-based copolymer latex of Example 1, 140 parts by weight of water was added instead of 90 parts by weight in step (S10), except that water was not added in steps (S20) to (S30). Then, it was carried out in the same manner as Example 1.

Comparative Example 6

When preparing the carboxylic acid-modified nitrile-based copolymer latex of Example 1, 70 parts by weight of water was added instead of 30 parts by weight in step (S20), except that water was not added in step (S30). It was carried out in the same manner as in 1.

Comparative Example 7

In Example 1, the stirring speed was adjusted so that the diameter of the stirrer impeller of the polymerization reactor was 75 mm, the tip speed of the stirrer was 2 m/s, and the Reynolds number (Re) at this time was about 5,000. In addition, the oil-soluble initiator cumene hydroperoxide and the condensation polymer were not added. The same method as Example 1 was performed except for the stirring conditions and whether or not the oil-soluble initiator and condensation polymer were added.

< Experimental example>

Experimental Example 1

Polymerization stability of the carboxylic acid-modified nitrile-based copolymer latex prepared from the above examples and comparative examples, workability of the latex composition for dip molding, and tensile properties (tensile strength, elongation, 300% modulus) of the dip molded product (glove) It was measured as follows and is shown in Tables 1 and 2 below.

(1) Polymerization stability: After filtering the obtained carboxylic acid-modified nitrile-based copolymer latex using a 200 mesh screen, the amount of aggregates caught on the screen was calculated in ppm using the solid content and the amount of filtered latex. It was determined that the smaller the amount of aggregates, the better the polymerization stability of the copolymer latex.

(2) Tensile strength (MPa): According to the ASTM D-412 method, pull the crosshead speed to 500 mm/min using a measuring device U.T.M. (Instron, 4466 model) and measure the point where the specimen is cut. It was calculated according to Equation 3 below.

[Equation 3]

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

(3) Elongation (%): According to the ASTM D-412 method, the crosshead speed was pulled to 500 mm/min using a measuring device U.T.M. (Instron, 4466 model), and then the point where the specimen was cut was measured, It was calculated according to Equation 4 below.

[Equation 4]

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

(4) 300% modulus (MPa): According to the ASTM D-412 method, the crosshead speed is pulled to 500 mm/min using a measuring device U.T.M. (Instron, 4466 model), and then the elongation is 300%. Stress was measured.

(5) Syneresis: The hand-shaped ceramic mold was immersed in the coagulant solution used in the manufacture of dip molded products for 1 minute, taken out, dried at 80°C for 3 minutes, and the coagulant was applied to the hand-shaped ceramic mold. Thereafter, the hand-shaped ceramic mold coated with the coagulant was immersed in the latex composition for dip molding of each example and comparative example for 1 minute and taken out, and the time taken for a droplet to fall from the hand-shaped mold was measured. If the droplet did not fall within 5 minutes, it was marked with an X, and in this case, syneresis was judged to be excellent.

Example 1 Example 2 Example 3 Example 4 Example 5 Reynolds number 20,000 20,000 20,000 20,000 20,000 Whether water-soluble monomer is added or not ○ ○ ○ ○ ○ Whether fat-soluble initiator is added or not ○ ○ ○ ○ ○ Condensation polymer input time and amount (parts by weight) 10% (0.5) 10% (0.5) 50% (0.5) 20% (0.3), 50% (0.2) 10~40% (0.5) continuous input M/W weight ratio (S10) step 1.11 1.39 1.11 1.11 1.11 (S20) step 0.83 0.98 0.83 0.83 0.83 (S30) step 0.63 0.68 0.63 0.63 0.63 Polymerized aggregate (ppm) 30 23 18 45 26 Syneresis (min) ⅹ ⅹ ⅹ ⅹ ⅹ glove properties Tensile strength (MPa) 35 34.7 36 33 35 Elongation (%) 520 532 525 535 529 300% modulus (MPa) 6.8 6.5 7.0 6.7 6.0

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Reynolds number 20,000 20,000 20,000 20,000 20,000 20,000 5 thousand Whether water-soluble monomer is added or not ⅹ ○ ○ ○ ○ ○ ○ Whether fat-soluble initiator is added or not ○ ⅹ ○ ○ ○ ○ ⅹ Condensation polymer input time and amount (parts by weight) 10% (0.5) 10% (0.5) ⅹ 65% (0.5) 10% (0.5) 10% (0.5) ⅹ M/W weight ratio (S10) step 1.11 1.11 1.11 1.11 0.71 1.11 1.11 (S20) step 0.83 0.83 0.83 0.83 - 0.63 0.83 (S30) step 0.63 0.63 0.63 0.63 - - 0.63 Polymerized aggregate (ppm) 20 2000 2600 1900 860 900 54 Syneresis (min) 1 min 3min 2min 3min 3min 3min 2min glove properties Tensile strength (MPa) 28 31 31 29 28 30 31 Elongation (%) 505 510 505 500 500 502 510 300% modulus (MPa) 7.0 6.8 7.0 7.0 6.9 7.1 6.7

* In Tables 1 and 2 above, M/W is the weight ratio of the monomer mixture to the total water introduced, and this value is rounded to two decimal places.

Referring to Tables 1 and 2 above, according to the production method of the present invention, an oil-soluble initiator is added before the start of polymerization, the condensation polymer is added when the polymerization conversion rate is 10% or more and less than 60%, and before the start of polymerization, the polymerization conversion rate is Examples 1 to 5, where the weight ratio (M/W) at 30 to 40% and 60 to 70% are within the appropriate range, have excellent polymerization stability because the content of aggregates in the copolymer latex after polymerization is small. It can be confirmed that the syneresis properties of the dip molding composition containing the polymerized copolymer latex and the tensile properties of the dip molded product (gloves) are also excellent.

Meanwhile, in the case of Comparative Example 1, which does not contain water-soluble monomers in the monomer mixture, it can be seen that the content of aggregates in the latex is small after polymerization. This is believed to be because water-soluble oligomers are not formed during the polymerization process because it does not contain water-soluble monomers. do. However, in this case, it can be seen that the syneresis and glove properties of the dip molding composition are significantly reduced compared to the case containing a water-soluble monomer. In addition, in the case of Comparative Example 7, where the Reynolds number for the fluid flow in the reactor is less than 10,000, it can be confirmed that the amount of aggregates in the latex after polymerization is small even if water-soluble monomers are included in the monomer mixture, but in this case, the productivity of the copolymer latex is improved. There is a problem that prevents this from happening.

In addition, if the oil-soluble initiator is not added (Comparative Example 2), the condensation polymer is not added (Comparative Example 3), or even if the condensation polymer is added, the timing of addition is outside the appropriate range (Comparative Example 4), or before the start of the polymerization reaction. If the weight ratio (M/W) value is outside the appropriate range (Comparative Example 5) or the weight ratio (M/W) value at the point when the polymerization conversion rate is 30 to 40% is outside the appropriate range (Comparative Example 6), It can be seen that the polymerization stability of the polymer latex, the syneresis properties of the dip molding composition, and the tensile properties of the dip molded product were significantly reduced compared to the Examples.

Accordingly, according to the production method of the present invention, an oil-soluble initiator is added before the start of polymerization, the condensation polymer is added when the polymerization conversion rate is 10% or more and less than 60%, and before the start of polymerization, the polymerization conversion rate is 30 to 40%. When the conditions that the weight ratio (M/W) at the time point and the time point of 60 to 70% are all within the appropriate range are satisfied, the polymerization stability of the copolymer latex and the cineri of the composition for dip molding containing the polymerized copolymer latex It can be seen that both sheath properties and tensile properties of dip molded products (gloves) can be improved.

Claims (11)

In the reactor, a monomer mixture containing a conjugated diene monomer, an ethylenically unsaturated nitrile monomer, an ethylenically unsaturated acid monomer, and a water-soluble monomer is prepared in the presence of 0.01 to 0.1 parts by weight of an oil-soluble initiator and water based on a total of 100 parts by weight of the monomer mixture. , starting emulsion polymerization under the condition that the weight ratio (M/W) of the monomer mixture to water is 1.1 to 1.4 (S10);
Controlling the weight ratio (M/W) to 0.8 to 1.0 by adding water when the polymerization conversion rate of the polymerization is 30 to 40% (S20); and
A step (S30) of controlling the weight ratio (M/W) to 0.6 to 0.7 by adding water when the polymerization conversion rate of the polymerization is 60 to 70%,
When the polymerization conversion rate of the polymerization is 10% or more and less than 60%, 0.1 to 2.0 parts by weight of sodium naphthalene sulfonate formaldehyde condensate is added based on 100 parts by weight of the monomer mixture,
In the step (S10), a water-soluble initiator is further added, but the total content of the oil-soluble initiator and the water-soluble initiator is added in an amount of 0.5 parts by weight or less based on 100 parts by weight of the monomer mixture,
The water-soluble monomers include 2-hydroxy ethyl methacrylate, 2-hydroxy propyl methacrylate, 3-hydroxy propyl methacrylate, 2-hydroxy ethyl acrylate, 2-hydroxy propyl acrylate and 3-hydroxy propyl acrylate. At least one member selected from the group consisting of hydroxyalkyl (meth)acrylates, including oxypropyl acrylate, and acrylamide,
The fat-soluble initiator is at least one selected from the group consisting of cumene hydroperoxide, benzoyl peroxide, dibutyl peroxide, dicumyl peroxide, and lauroyl peroxide,
A method of producing a carboxylic acid-modified nitrile-based copolymer latex wherein the water-soluble initiator is at least one selected from the group consisting of sodium persulfate, potassium persulfate, and ammonium persulfate. According to paragraph 1,
In the steps (S10) to (S30), the Reynolds number (Re) of the entire fluid flow including the reactants introduced into the reactor is 10,000 or more. According to paragraph 1,
A method for producing a carboxylic acid-modified nitrile-based copolymer latex, wherein the sodium naphthalene sulfonate formaldehyde condensation polymer is added in batches, divided doses, or continuously when the polymerization conversion rate is 10% or more and less than 60%. delete delete delete delete According to paragraph 1,
The monomer mixture contains 40 to 70% by weight of a conjugated diene monomer, 20 to 40% by weight of an ethylenically unsaturated nitrile monomer, 4 to 10% by weight of an unsaturated ethylenically unsaturated acid monomer, and 0.5 to 10% by weight of a water-soluble monomer. Method for producing this acid-modified nitrile-based copolymer latex. According to paragraph 1,
The conjugated diene monomers include 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 1,3-pentadiene, piperylene, 3-butyl-1, A method for producing a carboxylic acid-modified nitrile-based copolymer latex containing at least one member selected from the group consisting of 3-octadiene, 2-phenyl-1,3-butadiene, and isoprene. According to paragraph 1,
The ethylenically unsaturated nitrile-based monomer is a carboxylic acid-modified nitrile-based monomer comprising at least one selected from the group consisting of acrylonitrile, methacrylonitrile, fumaronitrile, α-chloronitrile, and α-cyano ethyl acrylonitrile. Method for producing copolymer latex. According to paragraph 1,
The ethylenically unsaturated acid monomer consists of acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, maleic anhydride, citraconic anhydride, styrene sulfonic acid, monobutyl fumarate, monobutyl maleate, and mono-2-hydroxypropyl maleate. A method for producing a carboxylic acid-modified nitrile-based copolymer latex comprising at least one member selected from the group.