KR20210156991A - Method for preparing carboxylic acid modified-nitrile based copolymer latex - Google Patents

Abstract

The present invention relates to a method for preparing a carboxylic acid-modified nitrile-based copolymer. Particularly, the method for preparing a carboxylic acid-modified nitrile-based copolymer includes the steps of: (S10) initiating polymerization of a monomer mixture containing a conjugated diene-based monomer, ethylenically unsaturated nitrile-based monomer, ethylenically unsaturated acid monomer and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) in the presence of a mercaptan-based compound; and (S20) further introducing a (meth)acrylate-based compound and mercaptan-based compound, when the polymerization conversion reaches 70-90%, wherein the ratio (Y) of the amount of the mercaptan-based compound further introduced in step (S20) based on the total amount of the mercaptan-based compound introduced in step (S10) and step (S20) satisfies formula 1 of Y(%) = [{(-0.59)*X} + 0.94] *100, and the amount (X) of the (meth)acrylate-based compound is 0.7-1.5 parts by weight based on 100 parts by weight of the total monomer mixture. According to the present invention, it is possible to obtain a carboxylic acid-modified nitrile-based copolymer having a controlled viscosity average molecular weight (Mv).

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 a carboxylic acid-modified nitrile-based copolymer latex, wherein a carboxylic acid-modified nitrile-based copolymer latex having a controlled viscosity average molecular weight (Mv) is prepared, and a composition for dip molding excellent in workability including the same And it relates to a technology to be applied as a dip-molded article having excellent tensile properties.

As interest in the environment and safety in various fields and daily life has greatly increased, the demand for gloves has increased, and the rubber glove market has also greatly increased accordingly. In the past, disposable gloves were made by deep molding natural rubber latex, but some users had problems with protein allergy, such as pain or rash. Due to these problems, disposable gloves manufactured by dip molding of nitrile-based latex with excellent chemical resistance and no allergy risk are in the spotlight in recent years to replace natural rubber.

On the other hand, workability and strength of gloves in the industrial and safety management market among the glove markets have been identified as major factors of physical properties, and various attempts have been made to improve them. Among them, a representative attempt is to increase the strength of the glove by increasing the carboxylic acid content in the carboxylic acid-modified nitrile-based copolymer latex to increase the ionic bond between zinc oxide and carboxylic acid in the synthetic latex.

However, when the content of carboxylic acid is increased as described above, the polymerization stability of the synthetic latex is seriously deteriorated in the polymerization process of the synthetic latex, and the workability of the polymerized nitrile-based copolymer latex and the tensile properties of the molded article manufactured therefrom are deteriorated. do.

Therefore, there is a need for the recurrence of the nitrile-based latex itself in order to simultaneously improve the workability of the nitrile-based copolymer latex and the tensile properties of a molded article manufactured therefrom.

KR 2016-0127008 A

The problem to be solved in the present invention is to polymerize a monomer mixture containing 2-acrylamido-2-methylpropanesulfonic acid in order to solve the problems mentioned in the technology that is the background of the invention, but a crosslinking agent ( By controlling the divided input ratio of the molecular weight modifier (mercaptan-based compound) according to the (meth)acrylate-based compound) content to satisfy General Formula 1 according to the present invention, the viscosity average molecular weight (Mv) is in an appropriate range (60,000 to 120,000). ) to prepare a carboxylic acid-modified nitrile-based copolymer latex contained within, and to apply it as a composition for dip molding with excellent workability and dip-molded products (gloves) with excellent tensile properties, including this.

According to an embodiment of the present invention for solving the above problems, a conjugated diene-based monomer, an ethylenically unsaturated nitrile-based monomer, an ethylenically unsaturated acid monomer, and 2-acrylamido-2-methylpropanesulfonic acid (2-Acrylamido- Initiating polymerization of a monomer mixture containing 2-methylpropanesulfonic acid, AMPS) in the presence of a mercaptan-based compound (S10); and a step (S20) of additionally adding a (meth)acrylate-based compound and a mercaptan-based compound at a time when the polymerization conversion rate of the polymerization is 70 to 90%, and the mercap introduced in the steps (S10) and (S20) The ratio (Y) of the mercaptan-based compound input added in step (S20) to the total input amount of the tan-based compound satisfies the following general formula 1, and the input amount (X) of the (meth)acrylate-based compound is It provides a method for preparing a carboxylic acid-modified nitrile-based copolymer in an amount of 0.7 to 1.5 parts by weight based on 100 parts by weight of the total monomer mixture.

[General formula 1]

Y(%) = [{(-0.59)*X} + 0.94] *100

In General Formula 1, X represents the amount of the (meth)acrylate-based compound added, and Y is the total amount of the mercaptan-based compound added in steps (S10) and (S20), added in step (S20) Indicates the ratio of the input amount of the mercaptan-based compound to be input,

The input amount represents parts by weight added based on 100 parts by weight of the total monomer mixture,

In General Formula 1, when the value of Y is 0 or less, the input amount of the mercaptan-based compound additionally added in the step (S20) is 0.

In addition, the present invention provides a repeating unit derived from a conjugated diene-based monomer, a repeating unit derived from an ethylenically unsaturated nitrile-based monomer, a repeating unit derived from an ethylenically unsaturated acid monomer, and 2-acrylamido-2-methylpropanesulfonic acid (2-Acrylamido-2- Provides a carboxylic acid-modified nitrile-based copolymer latex comprising a carboxylic acid-modified nitrile-based copolymer comprising a repeating unit derived from methylpropanesulfonic acid and a (meth)acrylate-based compound-derived portion, and having a viscosity average molecular weight (Mv) of 60,000 to 120,000 do.

In the method for producing a carboxylic acid-modified nitrile-based copolymer latex according to the present invention, a monomer mixture containing 2-acrylamido-2-methylpropanesulfonic acid is polymerized, but a crosslinking agent within an appropriate range ((meth)acrylate-based compound) By controlling the divided input ratio of the molecular weight modifier (mercaptan-based compound) according to the content to satisfy General Formula 1 according to the present invention, the viscosity average molecular weight (Mv) is contained within an appropriate range (60,000 to 120,000) of carboxylic acid-modified nitrile It is possible to provide a composition for dip molding excellent in workability and a dip molded article (gloves) excellent in tensile properties by preparing a copolymer-based latex and including it.

The terms or words used in the description and claims of the present invention should not be construed as being limited to their ordinary or dictionary meanings, and the inventor must properly understand the concept of the term in order to best describe his invention. Based on the principle that can be defined, it should be interpreted as meaning and concept consistent with the technical idea of the present invention.

In the present invention, the term 'copolymer' may mean including all copolymers formed by copolymerizing comonomers, and as a specific example, may mean including both random copolymers and block copolymers.

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

In the present invention, the terms 'derived repeating unit' and 'derived part' may refer to a component, structure, or material itself derived from a certain material. It may refer to a repeating unit formed in the polymer by participating in the polymerization reaction, and the 'derived part' may be one that induces a chain transfer reaction of the polymer by participating in the polymerization reaction of the chain transfer agent input during polymerization of the polymer.

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 article through dip molding, the polymer or copolymer is attached, fixed, and/or polymerized on the dip molding die. and may mean a layer formed from a polymer or copolymer.

As used herein, 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, and the like. may mean, and may mean including those substituted by substituents as well as unsubstituted ones.

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

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

According to the present invention, there is provided a method for producing a carboxylic acid-modified nitrile-based copolymer latex. The manufacturing method is a monomer comprising a conjugated diene-based monomer, an ethylenically unsaturated nitrile-based monomer, an ethylenically unsaturated acid monomer and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) Initiating polymerization of the mixture in the presence of a mercaptan compound (S10); and a step (S20) of additionally adding a (meth)acrylate-based compound and a mercaptan-based compound at a time when the polymerization conversion rate of the polymerization is 70 to 90%, and the mercap introduced in the steps (S10) and (S20) The ratio (Y) of the mercaptan-based compound input added in step (S20) to the total input amount of the tan-based compound satisfies the following general formula 1, and the input amount (X) of the (meth)acrylate-based compound is It may be 0.7 to 1.5 parts by weight based on 100 parts by weight of the total monomer mixture.

[General formula 1]

Y(%) = [{(-0.59)*X} + 0.94] *100

In General Formula 1, X represents the amount of the (meth)acrylate-based compound added, and Y is the total amount of the mercaptan-based compound added in steps (S10) and (S20), added in step (S20) Indicates the ratio of the input amount of the mercaptan-based compound to be input,

The input amount represents parts by weight added based on 100 parts by weight of the total monomer mixture,

In General Formula 1, when the value of Y is 0 or less, the input amount of the mercaptan-based compound additionally added in the step (S20) is 0.

According to the present invention, as described above, a molecular weight regulator ( By controlling the divided input ratio of the mercaptan compound) to satisfy General Formula 1, a carboxylic acid-modified nitrile-based copolymer latex having a viscosity average molecular weight (Mv) within an appropriate range (60,000 to 120,000) can be prepared, It is possible to improve both the workability of the latex composition for dip molding including the same and the tensile properties of the dip molded article (gloves).

On the other hand, for example, even if the above general formula 1 is satisfied, when the input amount of the crosslinking agent is out of the appropriate range, the viscosity average molecular weight (Mv) is out of the appropriate range (60,000 to 120,000), and the operation of the latex composition for dip molding Both the cast properties and the tensile properties of the dip molded article may be reduced, and, in the case where 2-acrylamido-2-methylpropanesulfonic acid (AMPS) is not included in the monomer mixture, the viscosity average molecular weight (Mv) is within an appropriate range ( 60,000 to 120,000), the workability of the latex composition for dip molding may be reduced, and, in addition, when the additional input time of the crosslinking agent and the molecular weight regulator is outside the appropriate polymerization conversion range (70 to 80%), or as a crosslinking agent ( When the meth) acrylate-based compound is not used or a mercaptan-based compound is not used as a molecular weight regulator, the viscosity average molecular weight (Mv) is out of the appropriate range (60,000 to 120,000), so that the workability of the latex composition for dip molding Alternatively, the tensile properties of the dip molded product may be deteriorated.

According to an embodiment of the present invention, in step (S10), a monomer mixture comprising a conjugated diene-based monomer, an ethylenically unsaturated nitrile-based monomer, an ethylenically unsaturated acid monomer, and 2-acrylamido-2-methylpropanesulfonic acid Initiating polymerization in the presence of a mercaptan-based compound as a molecular weight control agent, by controlling the content of monomers in the monomer mixture, the physical properties of the carboxylic acid-modified nitrile-based copolymer can be controlled, and the content of the mercaptan-based compound is controlled By doing so, the polymerization rate can be appropriately controlled.

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

The content of the conjugated diene-based monomer may be 45 to 80% by weight, 50 to 75% by weight, or 60 to 70% by weight based on the total content of the monomer mixture, and within this range, prepared from a carboxylic acid-modified nitrile-based copolymer The molded article is not only excellent in oil resistance and tensile strength, but also has the effect of improving flexibility and wearing comfort.

The ethylenically unsaturated nitrile-based monomer may include at least one selected from the group consisting of acrylonitrile, methacrylonitrile, α-chloronitrile and α-cyanoethylacrylonitrile, and specifically, the ethylenic The unsaturated nitrile-based monomer may be acrylonitrile.

The content of the ethylenically unsaturated nitrile-based monomer may be 15 to 40% by weight, 20 to 35% by weight, or 25 to 30% by weight based on the total content of the monomer mixture, and within this range, the carboxylic acid-modified nitrile-based copolymer Not only the oil resistance and tensile strength of molded articles manufactured from

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

The content of the ethylenically unsaturated acid monomer may be 0.1 to 10% by weight, 0.5 to 9% by weight, or 1 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 the tensile strength of the manufactured molded article is excellent, but there is an effect of improving flexibility and wearing comfort.

The 2-acrylamido-2-methylpropanesulfonic acid may be a compound represented by the following Chemical Formula 1, and when 2-acrylamido-2-methylpropanesulfonic acid is included in the monomer mixture, polymerization stability of the copolymer latex particles By improving the workability of the composition for dip molding containing the copolymer latex is improved, there is an excellent effect in the tensile strength of the molded article prepared from the carboxylic acid-modified nitrile-based copolymer.

[Formula 1]

The content of the 2-acrylamido-2-methylpropanesulfonic acid may be 3 to 5% by weight, 3.5 to 4.5% by weight, or 3.8 to 4.3% by weight based on the total content of the monomer mixture, and within this range, There is an effect that it is easy to control the range of the viscosity average molecular weight (Mv) of the latex targeted in the present invention.

According to an embodiment of the present invention, the monomer mixture may optionally further include another ethylenically unsaturated monomer copolymerizable with the ethylenically unsaturated nitrile monomer and the ethylenically unsaturated acid monomer.

Examples of the copolymerizable ethylenically unsaturated monomer include a hydroxyalkyl (meth)acrylate monomer having 1 to 4 carbon atoms; a vinyl aromatic monomer selected from the group consisting of styrene, aryl styrene, and vinyl naphthalene; fluoroalkylvinyl ether monomers such as fluoroethyl vinyl ether; (meth)acrylamide, N-methylol (meth)acrylamide, N,N-dimethylol (meth)acrylamide, N-methoxymethyl (meth)acrylamide, and N-propoxymethyl (meth)acrylamide an ethylenically unsaturated amide monomer selected from the group consisting of; non-conjugated diene monomers such as vinyl pyridine, vinyl norbornene, dicyclopentadiene, and 1,4-hexadiene; (meth) methyl acrylate, (meth) ethyl acrylate, (meth) acrylate, (meth) acrylic acid-2-ethylhexyl, (meth) acrylate trifluoroethyl, (meth) acrylic acid tetrafluoropropyl, dibutyl maleate, Dibutyl fumarate, diethyl maleate, methoxymethyl (meth)acrylate, ethoxyethyl (meth)acrylate, methoxyethoxyethyl (meth)acrylate, cyanomethyl (meth)acrylate, 2-cyano acrylate (meth)acrylate Ethyl, (meth)acrylic acid 1-cyanopropyl, (meth)acrylic acid 2-ethyl-6-cyanohexyl, (meth)acrylic acid 3-cyanopropyl, (meth)acrylic acid hydroxyethyl, (meth)acrylic acid hydroxy It may include at least one selected from the group consisting of ethylenically unsaturated carboxylic acid ester monomers selected from the group consisting of propyl, glycidyl (meth) acrylate, and dimethylamino ethyl (meth) acrylate. As a specific example, the ethylenically unsaturated monomer may be a hydroxyalkyl (meth)acrylate monomer having 1 to 4 carbon atoms, and more specifically, it may be a hydroxyethyl (meth)acrylate monomer.

The content of the ethylenically unsaturated monomer may be within 20 wt%, 0.001 wt% to 10 wt%, or 0.5 wt% to 5 wt%, based on the total content of the monomer mixture, within this range the carboxylic acid-modified nitrile-based monomer There is an effect of improving the balance between the wearing comfort and tensile strength of a molded article molded from the latex composition for dip molding including the copolymer.

The mercaptan-based compound may include at least one selected from the group consisting of t-dodecyl mercaptan, n-dodecyl mercaptan, allyl mercaptan, amyl mercaptan, methyl mercaptan, ethyl mercaptan and octyl mercaptan. And, as a specific example, the mercaptan-based compound may be t-dodecyl mercaptan. In this case, the polymerization stability is excellent, and when the molded article is manufactured after polymerization, there is an effect of excellent physical properties of the molded article.

According to an embodiment of the present invention, in the step (S20), when the polymerization conversion rate is 70 to 90%, a (meth)acrylate-based compound as a crosslinking agent and a mercaptan-based compound as a molecular weight regulator are additionally added. , by controlling the ratio (Y) of the mercaptan-based compound input amount additionally added in the (S20) step to the total input amount of the mercaptan-based compound inputted in the steps (S10) and (S20) to satisfy the general formula 1, It is a step of adjusting the viscosity average molecular weight (Mv) of the prepared latex to 60,000 to 120,000.

That is, in the step (S20), the input amount (X) of the (meth)acrylate-based compound is adjusted within the range of 0.7 to 1.5 parts by weight relative to 100 parts by weight of the total monomer mixture, and the (meth)acrylate-based compound According to the input amount (X), the ratio (Y) of the input amount of the mercaptan-based compound satisfying the above general formula (1) may be determined. In this way, the amount of the mercaptan-based compound added in step (S20) may be determined according to the determined ratio (Y) of the mercaptan-based compound input amount.

As described above, the added amount of the mercaptan compound, which is determined according to the amount of the crosslinking agent added within the appropriate range (0.7 to 1.5 parts by weight), is dividedly added at a specific time point (polymerization conversion rate of 70 to 90%), and the viscosity average of the produced latex The molecular weight (Mv) can be adjusted from 60,000 to 120,000, and the copolymer latex having the above-described viscosity average molecular weight (Mv) is prepared according to the above steps, and the workability of the latex composition for dip molding including the same, and the dip It shows the result of improving the tensile properties (tensile strength, stress retention) of the molded article.

The viscosity average molecular weight (Mv), unlike the weight average molecular weight (Mw), refers to a viscosity in a state in which intermolecular attraction is minimized, which is a value calculated through an intrinsic viscosity value in a dilute solution state of the latex composition. If the viscosity average molecular weight (Mv) is too large or too small, the diffusion motion of molecules alone is too large or small, which may reduce workability or strength in the manufacturing process of a molded article. The viscosity average molecular weight (Mv) of the copolymer latex containing 2-acrylamido-2-methylpropanesulfonic acid, prepared according to the production method of the present invention, is in the range of 60,000 to 120,000, so that the workability of the latex composition is improved and , there is an effect of excellent tensile properties of dip-molded products.

According to an embodiment of the present invention, the (meth)acrylate-based compound may serve to improve the crosslinking density in the copolymer to improve physical properties of a molded article including the copolymer. In addition, the input amount (X) of the (meth) acrylate-based compound may be 0.7 to 1.5 parts by weight, or 0.8 to 1.4, based on 100 parts by weight of the entire monomer mixture, and within this range, polymerization stability is excellent, and after polymerization When manufacturing a molded article, there is an effect of excellent tensile strength of the molded article.

The (meth) acrylate-based compound is allyl (meth) acrylate, 1,3-butanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, di Ethylene glycol di(meth)acrylate, triethyleneglycol di(meth)acrylate, 1,6-hexanediol (meth)acrylate, trimethylolpropane tri(meth)acrylate and tetraethylene glycol di(meth)acrylate It may include at least one selected from the group consisting of, as a specific example, the (meth)acrylate-based compound may be allyl (meth)acrylate. In this case, it is possible to form a uniform cross-linking site in the copolymer, and there is an effect of increasing the distribution of a linear nitrile-based copolymer having a high cross-linking density.

According to an embodiment of the present invention, the type of the mercaptan-based compound additionally added in step (S20) may be the same as the type of the mercaptan-based compound described above.

According to an embodiment of the present invention, the total amount of the mercaptan-based compound added in the steps (S10) and (S20) may be 0.5 to 0.6 parts by weight, or 0.55 to 0.58 parts by weight based on 100 parts by weight of the total monomer mixture. There is an effect of excellent polymerization stability by appropriately controlling the polymerization rate within this range, and excellent physical properties of the molded article when manufacturing a molded article after polymerization.

According to an embodiment of the present invention, in the general formula 1, when the value of Y is 0 or less, the input amount of the mercaptan-based compound additionally added in the step (S20) may be 0. That is, when the value of Y is 0 or less (0 or a negative number), the mercaptan-based compound may not be separately added, but may be added at once in the step (S10).

According to an embodiment of the present invention, the time point at which the polymerization conversion rate is 70 to 90% may mean a time point at which the polymerization conversion rate is 70 to 90% with respect to 100 parts by weight of the entire monomer mixture prepared in step (S10). .

On the other hand, according to an embodiment of the present invention, the polymerization conversion rate is obtained by taking a predetermined amount of a sample from the reactant being reacted at a predetermined time interval, calculating the total solid content (TSC) of the sample, and substituting it in Equation 1 below. may have been calculated.

[Equation 1]

Polymerization conversion (%) = {(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 the weight of monomers, water and auxiliary materials added during polymerization

* W _t,s : Sum of the weight of the added ingredients other than the monomer and water

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

* Supplementary materials: Molecular weight regulators such as emulsifiers, initiators, and molecular weight regulators excluding monomers and water added during polymerization

According to an embodiment of the present invention, the carboxylic acid-modified nitrile-based copolymer latex may be prepared by emulsion polymerization by further adding an emulsifier and a polymerization initiator to the monomer mixture constituting the carboxylic acid-modified nitrile-based copolymer.

In preparing the carboxylic acid-modified nitrile-based copolymer latex, the emulsifier is added to impart stability to the latex during and after the polymerization reaction, and when the polymerization of the carboxylic acid-modified nitrile-based copolymer is carried out including an emulsifier, The emulsifier may include, for example, at least one selected from the group consisting of anionic surfactants, nonionic surfactants, cationic surfactants and amphoteric surfactants, and specific examples thereof include alkylbenzenesulfonate, aliphatic sulfonate, higher alcohol It may include at least one anionic surfactant selected from the group consisting of sulfuric acid ester salts, α-olefin sulfonates, and alkyl ether sulfate ester salts. In addition, the emulsifier may be added in an amount of 0.3 parts by weight to 10 parts by weight, 0.8 parts by weight to 8 parts by weight, or 1.0 parts by weight to 6 parts by weight, based on 100 parts by weight of the total content of the monomer mixture, and polymerization is limited within this range. It has excellent properties and has a small amount of foam, which makes it easy to manufacture molded products.

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

In addition, according to an embodiment of the present invention, in preparing the carboxylic acid-modified nitrile-based copolymer latex, polymerization may be carried out in water as a medium, specifically deionized water as a medium, and to ensure polymerization easiness, if necessary It may be carried out by further including additives such as an activator, a chelating agent, a dispersing agent, a pH adjusting agent, an oxygen scavenger, a particle size adjusting agent, an anti-aging agent, and an oxygen scavenger.

According to an embodiment of the present invention, the emulsifier, the polymerization initiator, the additive, etc. may be added to the polymerization reactor as a whole, or may be separately added, or may be continuously added at each input.

According to an embodiment of the present invention, the polymerization temperature during the emulsion polymerization may be carried out at a polymerization temperature of, for example, 10 °C to 90 °C, 20 °C to 80 °C, or 25 °C to 75 °C, within this range In the latex stability has an excellent effect.

According to an embodiment of the present invention, the polymerization reaction termination may be performed at a polymerization conversion rate of 90% or more, preferably 92% to 99.9%. The polymerization reaction may be terminated by adding a polymerization inhibitor, a pH adjuster, and an antioxidant. After completion of the reaction, the finally obtained copolymer latex is used after removing unreacted monomers through a conventional deodorization and concentration process.

In addition, according to the present invention, there is provided a carboxylic acid-modified nitrile-based copolymer latex prepared by the method for producing a carboxylic acid-modified nitrile-based copolymer latex according to the present invention.

The carboxylic acid-modified nitrile-based copolymer latex prepared by the production method according to the present invention is a repeating unit derived from a conjugated diene-based monomer, a repeating unit derived from an ethylenically unsaturated nitrile-based monomer, a repeating unit derived from an ethylenically unsaturated acid monomer, 2-acrylamide Do-2-methylpropanesulfonic acid (2-Acrylamido-2-methylpropanesulfonic acid) containing a carboxylic acid-modified nitrile-based copolymer including a repeating unit and a (meth) acrylate-based compound-derived portion, the viscosity average molecular weight (Mv) is It may be between 60,000 and 120,000. As described above, including the repeating unit derived from 2-acrylamido-2-methylpropanesulfonic acid and the (meth)acrylate compound-derived portion, the viscosity average molecular weight (Mv) is In the case of 60,000 to 120,000, the workability of the latex composition for dip molding including the same, and the physical properties of the dip molded article are improved.

According to an embodiment of the present invention, the carboxylic acid-modified nitrile-based copolymer latex may have a glass transition temperature of -40 ℃ to -15 ℃, or -35 ℃ to -25 ℃, within this range, the While preventing the deterioration of tensile properties such as tensile strength and cracking of a molded article dip-molded from a latex composition for dip molding containing a main acid-modified nitrile-based copolymer latex, both elasticity and fit are excellent. The glass transition temperature may be adjusted by adjusting the content of the conjugated diene monomer, and the glass transition temperature may be measured using a differential scanning calorimetry.

In addition, according to an embodiment of the present invention, the average particle diameter of the carboxylic acid-modified nitrile-based copolymer particles in the carboxylic acid-modified nitrile-based copolymer latex is 80 nm to 300 nm, 95 nm to 195 nm, or 105 nm to 150 nm nm, and within this range, there is an effect of excellent tensile properties such as tensile strength of a molded article dip-molded from a latex composition for dip molding containing the same, and the film formation rate is excellent within the above range, resulting in synergy properties It has an excellent effect. The average particle diameter may be measured using a laser scattering analyzer (Nicomp).

In addition, according to the present invention, the carboxylic acid-modified nitrile-based copolymer latex according to the present invention is used as a latex composition for dip molding as it is, or through the addition of a composition (or additive) commonly used in the manufacture of dip molded products for dip molding It may be prepared from a latex composition. Specifically, a latex composition for dip molding including the carboxylic acid-modified nitrile-based copolymer latex and additives may be provided.

The latex composition for dip molding may be prepared by including one or more additives selected from the group consisting of a vulcanizing agent, an ionic crosslinking agent, a pigment, a filler, a thickener and a pH adjuster in the carboxylic acid-modified nitrile-based copolymer latex.

According to an embodiment of the present invention, the vulcanizing agent is for vulcanizing the latex composition for dip molding, and may be sulfur, and specific examples thereof include sulfur such as powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur and insoluble sulfur. can be 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 total content of the carboxylic acid-modified nitrile-based copolymer latex in the latex composition for dip molding. , there is an effect excellent in crosslinking ability by vulcanization within this range.

In addition, according to an embodiment of the present invention, the vulcanization accelerator is 2-mercaptobenzothiazole (MBT, 2-mercaptobenzothiazole), 2,2-dithiobisbenzothiazole-2-sulfenamide (MBTS, 2,2) -dithiobisbenzothiazole-2-sulfenamide), N-cyclohexylbenzothiazole-2-sulfenamide (CBS, N-cyclohexylbenzothiasole-2-sulfenamide), 2-morpholinothiobenzothiazole (MBS, 2-morpholinothiobenzothiazole), tetra Methylthiuram monosulfide (TMTM, tetramethylthiuram monosulfide), tetramethylthiuram disulfide (TMTD, tetramethylthiuram disulfide), zinc diethyldithiocarbamate (ZDEC, zinc diethyldithiocarbamate), zinc dibutyldithiocarbamate (ZDBC, It may be at least one selected from the group consisting of zinc di-n-butyldithiocarbamate), diphenylguanidine (DPG, diphenylguanidine), and 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 total content of the carboxylic acid-modified nitrile-based copolymer latex in the latex composition for dip molding. , there is an effect excellent in crosslinking ability by vulcanization within this range.

In addition, according to an embodiment of the present invention, zinc oxide may be used as the ionic crosslinking agent. The zinc oxide performs ionic bonding with the carboxyl group of the carboxylic acid-modified nitrile-based copolymer in the latex composition for dip molding, and cross-linking through ionic bonding within the carboxylic acid-modified nitrile-based copolymer or between the carboxylic acid-modified nitrile-based copolymer It may be a crosslinking agent to form a part. The content of the zinc oxide may be 0.1 parts by weight to 5 parts by weight, or 0.5 parts by weight to 4 parts by weight, based on 100 parts by weight (based on solid content) of the total content of the carboxylic acid-modified nitrile-based copolymer latex in the latex composition for dip molding. , it has excellent crosslinking ability, excellent latex stability, and excellent tensile strength and flexibility of the manufactured dip-molded product within this range.

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

As another example, the latex composition for dip molding may have a pH of 8 to 12, 9 to 11, or 9.5 to 10.5, and has excellent processability and productivity when manufacturing a dip molded article within this range. The pH of the latex composition for dip molding may be adjusted by adding the above-described pH adjuster. The pH adjusting agent may be, for example, an aqueous solution of potassium hydroxide at a concentration of 1 wt% to 5 wt%, or aqueous ammonia at a concentration of 1 wt% to 5 wt%.

In addition, according to the present invention, there is provided a molded article comprising a layer derived from the latex composition for dip molding according to the present invention. The molded article may be a dip molded article prepared by dip molding the latex composition for dip molding, and may be a molded article including a latex composition derived layer for dip molding formed from the latex composition for dip molding by dip molding.

The molded article manufacturing method for molding the molded article may include a step of immersing the latex composition for dip molding by a direct immersion method, an anode adhesion immersion method, a Teague adhesion immersion method, etc. It can be carried out by an adhesive dipping method, in which case there is an advantage in that a dip molded article having a uniform thickness can be obtained.

As a specific example, the method for manufacturing the molded article includes the steps of attaching a coagulant to a dip molding die (S100); The step of immersing the dip molding die to which the coagulant is attached in the latex composition for dip molding to form a latex composition-derived layer for dip molding, that is, a dip molding layer (S200); and heating the dip molding layer to crosslink the latex composition for dip molding (S300).

According to an embodiment of the present invention, the step (S100) is a step of attaching the coagulant to the surface of the dip forming die by immersing the dip forming die in a coagulant solution to form a coagulant in the dip forming die, wherein the coagulant solution is a coagulant is a solution in which water, alcohol, or a mixture thereof is dissolved, and the content of the coagulant in the coagulant solution may be 5 wt% to 50 wt% or 10 wt% to 40 wt% 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; acetates such as barium acetate, calcium acetate and zinc acetate; And it may be at least one selected from the group consisting of sulfates such as calcium sulfate, magnesium sulfate and aluminum sulfate, and specific examples thereof may be calcium chloride or calcium nitrate.

In addition, according to an embodiment of the present invention, the step (S100) is a step of immersing the dip molding die in a coagulant solution for 10 seconds or more in order to attach the coagulant to the dip molding die, and drying it at 70 ° C. to 150 ° C. after taking it out. may further include.

According to an embodiment of the present invention, in the step (S200), a dip molding mold to which a coagulant is attached to form a dip molding layer is immersed in the latex composition for dip molding according to the present invention, taken out and dip molding in the dip molding mold It may be a step of forming a layer. In addition, according to an embodiment of the present invention, in the step (S200), the immersion may be performed for 10 seconds or more during the immersion in order to form a dip molding layer on the dip molding die.

According to an embodiment of the present invention, in the step (S300), the liquid component is evaporated by heating the dip molding layer formed on the dip molding die to obtain a dip molded article, and the latex composition for dip molding is crosslinked to proceed with curing. It may be a step to At this time, when using the latex composition for dip molding according to the present invention, the crosslinking agent composition included in the latex composition for dip molding may be crosslinked by vulcanization and/or ionic bonding. In addition, according to an embodiment of the present invention, the heating is performed by primary heating at 70 ° C. to 150 ° C. for 1 minute to 10 minutes, and then secondary heating at 100 ° C. to 180 ° C. for 5 minutes to 30 minutes. can

Thereafter, the dip molding layer crosslinked by heat treatment can be peeled off from the dip molding die to obtain a dip molded article.

The method for manufacturing a molded article according to the present invention can be used for any latex article that can be produced by a known dip molding method. Specifically, the molded article may be gloves, condoms, catheters, or health care products such as surgical gloves, examination gloves, industrial gloves and household gloves.

Hereinafter, the present invention will be described in more detail by way of Examples. However, the following examples are intended to illustrate the present invention, and it is apparent to those skilled in the art that various changes and modifications can be made within the scope and spirit of the present invention, and the scope of the present invention is not limited thereto.

< Example >

Example One

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

A monomer mixture comprising 25 wt% of acrylonitrile, 66 wt% of 1,3-butadiene, 5 wt% of methacrylic acid and 4 wt% of 2-acrylamido-2-methylpropanesulfonic acid (AMPS) in a polymerization reactor; Based on 100 parts by weight of the monomer mixture, 0.51 parts by weight of t-dodecyl mercaptan (TDDM), 1.0 parts by weight of sodium dodecyl benzenesulfonate, and 125 parts by weight of water were added, and then the temperature was raised to 40°C. After the temperature was raised, 0.3 parts by weight of potassium persulfate as a polymerization initiator was added to initiate polymerization. Then, when the polymerization conversion reached 80%, 0.07 parts by weight of t-dodecyl mercaptan (TDDM), 1.38 parts by weight of allyl methacrylate (AMA), 0.3 parts by weight of sodium dodecyl benzene sulfonate, and 5 parts by weight of water were additionally added. .

At this time, the ratio (Y) of the amount of t-dodecyl mercaptan added to the total amount of t-dodecyl mercaptan added during polymerization (0.58 parts by weight) to the amount of t-dodecyl mercaptan added when the polymerization conversion rate is 80% (Y) is was determined, and the additional input amount of t-dodecyl mercaptan calculated according to the ratio (Y) was rounded off to the third decimal place.

Then, when the polymerization conversion reached 95%, 0.1 parts by weight of sodium dimethyldithio carbamate was added to stop the polymerization. Thereafter, unreacted substances were removed through a deodorizing process, and aqueous ammonia, an antioxidant, and an antifoaming agent were added to obtain a carboxylic acid-modified nitrile-based copolymer latex having a solids concentration of 45% and pH 8.5.

[General formula 1]

Y(%) = [{(-0.59)*X} + 0.94] *100

In Formula 1, X represents the amount of the allyl methacrylate input, and Y represents the total amount of t-dodecyl mercaptan added during the polymerization. t-dode added when the polymerization conversion rate is 80%. Represents the ratio of the actual mercaptan input,

The input amount represents parts by weight added based on 100 parts by weight of the total monomer mixture,

In Formula 1, when the value of Y is 0 or less, the amount of t-dodecyl mercaptan added is 0 when the polymerization conversion rate is 80%.

<Production of latex composition for dip molding>

2.0 parts by weight of potassium hydroxide solution, 1.2 parts by weight of sulfur, 1.4 parts by weight of zinc oxide, zinc di-n-butyldithiocarbamate (ZDBC, Zinc di-n-butyldithiocarbamate) 0.9 parts by weight, 1.2 parts by weight of titanium oxide, and secondary distilled water were added to prepare a latex composition for dip molding having a solids concentration of 20% by weight and a pH of 10.

<Production of deep molded products>

18% by weight of calcium nitrate, 81.9% by weight of water, and 0.1% by weight of a wetting agent (manufactured by Huntsman Corporation, Australia, product name: Teric 320) were mixed to prepare a coagulant solution, and a hand-shaped ceramic mold was placed in the solution for 10 seconds. After soaking, taking out, and drying at 80° C. for 4 minutes, the coagulant was applied to a hand-shaped ceramic mold.

Then, the hand-shaped ceramic mold coated with the coagulant was immersed in the prepared latex composition for dip molding for 10 seconds, pulled up, dried at 80 ° C. for 2 minutes, and then soaked in water or warm water for 30 seconds to perform leaching. Again the mold was crosslinked at 110° C. for 20 minutes. Thereafter, the cross-linked dip-molding layer was peeled off from the hand-shaped mold to obtain a glove-shaped dip-molded article.

Example 2

When preparing the carboxylic acid-modified nitrile-based copolymer latex of Example 1, 1.15 parts by weight instead of 1.38 parts by weight of allyl methacrylate, and 0.43 parts by weight instead of 0.51 parts by weight of t-dodecyl mercaptan at the start of polymerization, It was carried out in the same manner as in Example 1, except that 0.15 parts by weight was added instead of 0.07 parts by weight of t-dodecyl mercaptan when the polymerization conversion rate was 80%.

Example 3

When preparing the carboxylic acid-modified nitrile-based copolymer latex of Example 1, 0.80 parts by weight instead of 1.38 parts by weight of allyl methacrylate, and 0.31 parts by weight instead of 0.51 parts by weight of t-dodecyl mercaptan at the start of polymerization, It was carried out in the same manner as in Example 1, except that 0.27 parts by weight was added instead of 0.07 parts by weight of t-dodecyl mercaptan when the polymerization conversion rate was 80%.

Example 4

When preparing the carboxylic acid-modified nitrile-based copolymer latex of Example 2, as a monomer mixture, 25 wt% of acrylonitrile, 68 wt% of 1,3-butadiene, 5 wt% of methacrylic acid and 2-acrylamido- It was carried out in the same manner as in Example 2, except that a monomer mixture consisting of 2 wt% of 2-methylpropanesulfonic acid was used.

Example 5

When preparing the carboxylic acid-modified nitrile-based copolymer latex of Example 2, as a monomer mixture, 25 wt% of acrylonitrile, 64 wt% of 1,3-butadiene, 5 wt% of methacrylic acid and 2-acrylamido- It was carried out in the same manner as in Example 2, except that a monomer mixture consisting of 6 wt% of 2-methylpropanesulfonic acid was used.

comparative example One

When preparing the carboxylic acid-modified nitrile-based copolymer latex of Example 1, 0.65 parts by weight is added instead of 1.38 parts by weight of allyl methacrylate, and 0.26 parts by weight is added instead of 0.51 parts by weight of t-dodecyl mercaptan when polymerization is started, It was carried out in the same manner as in Example 1, except that 0.32 parts by weight was added instead of 0.07 parts by weight of t-dodecyl mercaptan when the polymerization conversion rate was 80%.

comparative example 2

When preparing the carboxylic acid-modified nitrile-based copolymer latex of Example 1, 1.60 parts by weight is added instead of 1.38 parts by weight of allyl methacrylate, and 0.58 parts by weight is added instead of 0.51 parts by weight of t-dodecyl mercaptan when polymerization is started, It was carried out in the same manner as in Example 1, except that t-dodecyl mercaptan was not additionally added when the polymerization conversion rate was 80%.

comparative example 3

When preparing the carboxylic acid-modified nitrile-based copolymer latex of Example 2, as a monomer mixture, a monomer mixture consisting of 25% by weight of acrylonitrile, 70% by weight of 1,3-butadiene, and 5% by weight of methacrylic acid was used. Except it was carried out in the same manner as in Example 2.

comparative example 4

In the preparation of the carboxylic acid-modified nitrile-based copolymer latex of Example 1, additional input of allyl methacrylate and t-dodecyl mercaptan was performed at a time when the polymerization conversion rate was 60% instead of 80%. It was carried out in the same manner as in Example 1.

comparative example 5

In the preparation of the carboxylic acid-modified nitrile-based copolymer latex of Example 1, diallyl phthalate (DAP), not allyl methacrylate, was used as a crosslinking agent. It was carried out in the same manner as in Example 1. .

comparative example 6

In the preparation of the carboxylic acid-modified nitrile-based copolymer latex of Example 1, not t-dodecyl mercaptan, but dibutyl sulfide (DBS) was used as a molecular weight control agent. The same method as in Example 1 was carried out with

< Experimental example >

Experimental example One

The physical properties of the carboxylic acid-modified nitrile-based copolymer latex, the workability of the latex composition for dip molding, and the tensile properties (tensile strength, 300% and 500% modulus) of the dip molded article (glove) prepared from the Examples and Comparative Examples was measured as follows and shown in Tables 1 and 2 below.

(1) Intrinsic Viscosity and Viscosity Average Molecular Weight (Mv): The latex obtained by polymerization was dissolved in acetone for each concentration to be well dispersed (0.28, 0.52, 0.73, 0.96 g/dl). 10 ml of this solution was put into a Canon-Fenske type capillary viscometer, and the time (t) required to fall at 25 °C was measured. In addition, the fall time (t0) of acetone alone without latex was also measured. Relative Viscosity, Specific Viscosity, Reduced Viscosity, and Intrinsic Viscosity (IV) were obtained for each concentration using t and t0 to obtain the intrinsic viscosity value. Each viscosity value is shown in Tables 1 and 2 below. Next, the Mark-Houwink equation shown below was used to obtain the viscosity average molecular weight (Mv) through the intrinsic viscosity value. The viscosity average molecular weight obtained through this is shown in Tables 1 and 2 below.

[Mark-Houwink equation]

[n]=KMva ([n]: intrinsic viscosity, Mv: viscosity average molecular weight, K,a are Mark-Houwink parameters, using the values from the Polymer Handbook, K=0.0005 dl/g, a=0.64)

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

[Equation 2]

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

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

[Equation 3]

Elongation (%) = (length after extension of specimen / initial length of specimen) X 100

(4) 300%, 500% modulus (MPa): According to ASTM D-412 method, after pulling the crosshead speed to 500 mm/min using a measuring device UTM (Instron, 4466 model), the elongation is 300% , the stress at 500% was measured.

(5) Syneresis (sec): In order to check the syneresis time, the mold coated with the coagulant solution is immersed in the latex composition for dip molding prepared in Examples and Comparative Examples for 1 minute and then pulled up at 120 ° C. After drying at temperature for 4 minutes, re-immersed in water for 3 minutes. Then, the time it takes for the droplet to fall from the hand-shaped mold when drying at a temperature of 120° C. for 4 minutes was measured. As the syneresis time increased, it was judged that the synergy characteristics were excellent.

Example 1 Example 2 Example 3 Example 4 Example 5 AMPS content (wt%) 4 4 4 2 6 Crosslinking agent (parts by weight, X) Kinds Allyl Methacrylate (AMA) input 1.38 1.15 0.80 1.15 1.15 Molecular weight modifier (parts by weight) Kinds t-Dodecyl mercaptan (TDDM) input 0.58 Additional input molecular weight regulator
Post-addition ratio (%, Y) / Post-addition amount (parts by weight) 12.6%
/0.07 26.2%
/0.15 46.8%
/0.27 26.2%
/0.15 26.2%
/0.15 Intrinsic Viscosity (dl/g) 0.5885 0.7094 0.8841 0.7276 0.7324 Viscosity Average Molecular Weight (Mv) 62,800 84,100 118,600 87,500 88,400 Tensile strength (MPa) 32.8 32.6 33.2 31.0 27.9 300% modulus (MPa) 5.19 5.05 5.23 5.02 4.58 500% modulus (MPa) 10.75 10.56 10.82 10.21 9.35 Syneresis (min) 252 245 233 193 184

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 AMPS content (wt%) 4 4 0 4 4 4 Crosslinking agent (parts by weight, X) Kinds AMA AMA AMA AMA DAP AMA input 0.65 1.60 1.15 1.38 1.38 1.38 Molecular weight modifier (parts by weight) Kinds TDDM TDDM TDDM TDDM TDDM DBS input 0.58 Additional input molecular weight regulator
Post-addition ratio (%, Y) / Post-addition amount (parts by weight) 55.7%
/0.32 0%/0 26.2%
/0.15 12.6%
/0.07 12.6%
/0.07 12.6%
/0.07 Intrinsic Viscosity (dl/g) 0.9315 0.5311 0.7207 0.5456 0.9466 0.5368 Viscosity Average Molecular Weight (Mv) 128,700 53,500 86,200 55,800 132,000 54,400 Tensile strength (MPa) 27.6 23.8 30.5 24.4 25.7 24.2 300% modulus (MPa) 4.49 3.88 4.95 4.02 4.24 3.94 500% modulus (MPa) 9.17 7.94 10.16 8.16 8.84 7.98 Syneresis (min) 125 176 120 178 114 178

Referring to Tables 1 and 2 above, according to the manufacturing method of the present invention, a monomer mixture containing 2-acrylamido-2-methylpropanesulfonic acid is polymerized, but the content of the crosslinking agent (allyl methacrylate) within an appropriate range is The carboxylic acid-modified nitrile-based copolymer latex of Examples 1 to 5 in which the divided input ratio of the molecular weight modifier (t-dodecyl mercaptan) according to the above was controlled to satisfy General Formula 1 has a viscosity average molecular weight (Mv) in an appropriate range (60,000 to 120,000) was confirmed to be included, and as a result, it can be confirmed that the workability of the latex composition for dip molding and the tensile properties of the dip molded article are excellent.

On the other hand, even if the general formula 1 is satisfied, when the crosslinking agent input amount is out of the appropriate range (Comparative Examples 1 and 2), the viscosity average molecular weight (Mv) is out of the appropriate range (60,000 to 120,000), and latex for dip molding It can be seen that the workability of the composition and the tensile properties of the dip molded article are lowered compared to those of Examples.

In addition, when 2-acrylamido-2-methylpropanesulfonic acid (AMPS) is not included (comparison 3), even if the viscosity average molecular weight (Mv) is within an appropriate range (60,000 to 120,000), the synergistic properties are was lowered, and when the addition time of the crosslinking agent and the molecular weight regulator was outside the appropriate range (Comparative Example 4), the viscosity average molecular weight (Mv) was less than the lower limit of the appropriate range (60,000 to 120,000), and the tensile strength properties were lowered, When the (meth)acrylate-based compound was not used as the crosslinking agent (Comparative Example 5), the synergy was significantly lowered compared to Example 1 in which the same amount of the (meth)acrylate-based compound was added, and mercap as a molecular weight regulator When the tan-based compound was not used (Comparative Example 6), it can be seen that the tensile strength was significantly lowered compared to that of Example 1, in which the same amount of the mercaptan-based compound was added at the same post-addition ratio.

Accordingly, according to the production method of the present invention, a monomer mixture containing 2-acrylamido-2-methylpropanesulfonic acid is polymerized, but a molecular weight regulator according to the content of a crosslinking agent ((meth)acrylate-based compound) within an appropriate range When the divided input ratio of (mercaptan-based compound) is controlled to satisfy General Formula 1, the viscosity average molecular weight (Mv) of the carboxylic acid-modified nitrile-based copolymer latex prepared through this is within an appropriate range (60,000 to 120,000). It was confirmed that it was included, and as a result, it was confirmed that both the synergy properties of the composition for dip molding including the copolymer latex and the tensile properties of the dip molded article (gloves) could be improved.

Claims (10)

A monomer mixture including a conjugated diene-based monomer, an ethylenically unsaturated nitrile-based monomer, an ethylenically unsaturated acid monomer, and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) is mixed with a mercaptan-based compound Initiating polymerization in the presence (S10); and
A step (S20) of additionally adding a (meth)acrylate-based compound and a mercaptan-based compound at a time when the polymerization conversion rate of the polymerization is 70 to 90%;
The ratio (Y) of the amount of the mercaptan-based compound added in step (S20) to the total amount of the mercaptan-based compound added in the steps (S10) and (S20) satisfies the following general formula 1,
The amount (X) of the (meth) acrylate-based compound is 0.7 to 1.5 parts by weight based on 100 parts by weight of the entire monomer mixture. Method for producing a carboxylic acid-modified nitrile copolymer:
[General formula 1]
Y(%) = [{(-0.59)*X} + 0.94] *100
In the general formula 1, X represents the input amount of the (meth)acrylate-based compound, and Y is the total input amount of the mercaptan-based compound input in the steps (S10) and (S20), added in step (S20) Indicates the ratio of the input amount of the mercaptan-based compound to be input,
The input amount represents parts by weight added based on 100 parts by weight of the total monomer mixture,
In Formula 1, when the value of Y is 0 or less, the input amount of the mercaptan-based compound additionally added in step (S20) is 0. According to claim 1,
The method for producing a carboxylic acid-modified nitrile-based copolymer latex wherein the 2-acrylamido-2-methylpropanesulfonic acid is included in an amount of 3 to 5% by weight based on the total content of the monomer mixture. According to claim 1,
The total amount of the mercaptan compound added in the steps (S10) and (S20) is 0.5 to 0.6 parts by weight based on 100 parts by weight of the total monomer mixture. According to claim 1,
The (meth) acrylate-based compound is added in an amount (X) of 0.8 to 1.4 parts by weight based on 100 parts by weight of the entire monomer mixture. According to claim 1,
The viscosity average molecular weight (Mv) of the carboxylic acid-modified nitrile-based copolymer latex is 60,000 to 120,000, a method for producing a carboxylic acid-modified nitrile-based copolymer latex. According to claim 1,
The monomer mixture comprises 45 to 80% by weight of a conjugated diene-based monomer, 15 to 40% by weight of an ethylenically unsaturated nitrile-based monomer, 0.1 to 10% by weight of an unsaturated ethylenically unsaturated acid monomer, and 2-acrylamido-2-methylpropanesulfonic acid Method for producing a carboxylic acid-modified nitrile-based copolymer latex containing 3 to 5% by weight. According to claim 1,
The mercaptan-based compound includes at least one selected from the group consisting of t-dodecyl mercaptan, n-dodecyl mercaptan, allyl mercaptan, amyl mercaptan, methyl mercaptan, ethyl mercaptan and octyl mercaptan. A method for producing acid-modified nitrile-based copolymer latex. According to claim 1,
The (meth) acrylate-based compound is allyl (meth) acrylate, 1,3-butanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, di Ethylene glycol di(meth)acrylate, triethyleneglycol di(meth)acrylate, 1,6-hexanediol (meth)acrylate, trimethylolpropane tri(meth)acrylate and tetraethylene glycol di(meth)acrylate A method for producing a carboxylic acid-modified nitrile-based copolymer latex comprising at least one selected from the group consisting of. According to claim 1,
The mercaptan-based compound is t-dodecyl mercaptan,
The (meth) acrylate-based compound is an allyl methacrylate method for producing a carboxylic acid-modified nitrile-based copolymer latex. A repeating unit derived from a conjugated diene-based monomer, a repeating unit derived from an ethylenically unsaturated nitrile monomer, a repeating unit derived from an ethylenically unsaturated acid monomer, a repeating unit derived from 2-acrylamido-2-methylpropanesulfonic acid A carboxylic acid-modified nitrile-based copolymer comprising a unit and a (meth)acrylate-based compound-derived portion,
A carboxylic acid-modified nitrile-based copolymer latex having a viscosity average molecular weight (Mv) of 60,000 to 120,000.