KR102229443B1 - Latex composition for dip-forming and the product prepared thereby - Google Patents

Abstract

The present invention relates to a latex composition for dip molding and a molded article prepared therefrom, and more specifically, the composition is a carboxylic acid-modified nitrile-based copolymer latex using a C1 to C12 alkyl (meth)acrylic monomer as a comonomer. Thus, it is possible to manufacture dip-molded products with excellent tensile strength, elongation, stress and durability against sweat.

Description

Latex composition for dip molding and molded article manufactured therefrom {LATEX COMPOSITION FOR DIP-FORMING AND THE PRODUCT PREPARED THEREBY}

The present invention relates to a latex composition for dip molding capable of manufacturing a dip-molded product having excellent tensile strength, elongation, stress and durability against sweat, and a molded product manufactured therefrom.

Rubber gloves used in various fields such as housework, food industry, electronics industry, medical field, etc. have been made by molding natural rubber. However, its use has been limited recently due to allergies and unstable supply and demand problems caused by natural proteins contained in natural rubber.

Therefore, rubber gloves made by dip molding a latex composition containing sulfur and a vulcanization accelerator in a carboxylic acid-modified nitrile-based copolymer latex such as a synthetic rubber latex that does not cause allergic reactions, such as acrylic acid-acrylonitrile-butadiene copolymer latex, are widely used. Is being used.

Rubber gloves made by mixing these sulfur and vulcanization accelerators have improved durability so that sulfur forms crosslinks between polymer chains, so that even if the rubber gloves are used for a long time, durability is improved, and the strength of the rubber gloves may be improved.

However, in the case of manufacturing rubber gloves using sulfur and a vulcanization accelerator, a long stirring and aging process for 24 hours or more must be carried out, thereby reducing productivity. In addition, rubber gloves formulated with sulfur and vulcanization accelerators as essential ingredients cause an unpleasant odor due to sulfur or discoloration of the rubber gloves, resulting in an allergic reaction to some users. There is a problem that causes skin abnormalities such as tingling.

Therefore, research is being conducted to manufacture durable rubber gloves without using sulfur or a vulcanization accelerator, which does not cause problems such as discomfort, discoloration, and allergic reactions.

For example, when using a latex composition for dip molding containing a conjugated diene rubber latex and an organic peroxide, a long stirring and aging process is not required, and studies related to the manufacture of rubber gloves that do not cause discoloration have been conducted. However, the organic peroxide solution is very harmful to the human body, and when heat or shock is applied, fire and explosion may occur, and thus the safety of the process is very poor.

In addition, rubber gloves that do not cause allergic reactions by sulfur and vulcanization accelerators have been developed using crosslinkable monomers in acrylic emulsion latex, but the rubber gloves are made from acrylic, which is very vulnerable to heat, so they are very sensitive to heat. there is a problem.

However, in the case of gloves made without the use of sulfur and vulcanization accelerators, there is a problem in that the glove is torn in a short time due to sweat and tensile force generated when worn on the hand.

Republic of Korea Patent Publication No. 2014-0053859 (2014.05.08), highly saturated nitrile rubber composition and rubber crosslinked product

As a result of conducting various studies to solve the above problems, the present inventors have conducted a dip molded product by increasing the glass transition temperature of the copolymer by using an alkyl (meth)acrylic monomer as a copolymer when preparing a carboxylic acid-modified nitrile-based copolymer. The present invention was completed by confirming that the physical properties of can be improved.

Accordingly, an object of the present invention is to provide a latex composition for dip molding comprising a carboxylic acid-modified nitrile-based copolymer latex.

In addition, another object of the present invention is to provide a dip-molded article having excellent tensile strength, elongation, stress and durability against sweat by being prepared from the latex composition for dip molding.

In order to achieve the above object, the present invention provides a carboxylic acid-modified nitrile-based copolymer latex in which a conjugated diene-based monomer, an ethylenically unsaturated nitrile-based monomer, an ethylenically unsaturated acid monomer, and a C1 to C12 alkyl (meth)acrylic monomer are copolymerized. It provides a latex composition for dip molding, characterized in that it comprises.

At this time, the C1 to C12 alkyl (meth)acrylic monomers are methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, hexyl ( It is characterized in that at least one selected from the group consisting of meth)acrylate, 2-ethylbutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and heptyl (meth)acrylate.

The carboxylic acid-modified nitrile-based copolymer latex has a glass transition temperature of -20 to -5°C, and an average particle diameter of 100 to 200 nm.

In addition, the present invention provides a dip molded article, characterized in that produced by dip molding with the latex composition for dip molding.

The latex for dip molding according to the present invention may have excellent durability compared to existing products through simple ionic bonding without sulfur crosslinking.

Therefore, the dip molded product prepared from the dip molding latex composition may have excellent durability against sweat, and the carboxylic acid-modified nitrile-based copolymer latex and the dip molded product using the same may be used in industries that require it, such as the rubber glove industry. It can be easily applied to the etc.

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

The terms or words used in the specification and claims should not be construed as being limited to their usual or dictionary meanings, and the inventor may appropriately define the concept of terms in order to describe his own invention in the best way. It should be interpreted as a meaning and concept consistent with the technical idea of the present invention based on the principle that there is.

Latex composition for dip molding

The present invention proposes a latex composition for dip molding comprising a carboxylic acid-modified nitrile-based copolymer latex, but by increasing the molecular weight of the copolymer to adjust the glass transition temperature, the tensile strength, elongation, stress, and durability against sweat It proposes a latex composition for dip molding that can increase.

The term "Glass transition temperature (Transition Temperature, ℃, hereinafter referred to as Tg)" used in the present invention refers to the point at which molecules in the latex become active and begin to move by temperature, that is, the elasticity before the latex changes from the solid phase to the liquid phase. It means the time point at which the state has changed.

Tg depends on the chemical structure of the carboxylic acid-modified nitrile-based copolymer, the composition of the monomer, and the molecular weight, and in the present invention, an alkyl (meth)acrylic monomer is used as a comonomer when preparing a carboxylic acid-modified nitrile-based copolymer by increasing the Tg. And copolymerize.

Typically, the carboxylic acid-modified nitrile-based copolymer is prepared by copolymerization of a conjugated diene-based monomer, an ethylenically unsaturated nitrile-based monomer, and an ethylenically unsaturated acid monomer, and in the present invention, C1 to C12 alkyl (meta) as a comonomer during the copolymerization. By using an acrylic monomer, it plays a role in increasing the Tg of the entire copolymer by increasing the molecular weight and flexibility of the molecular structure.

At this time, the C1 to C12 alkyl (meth)acrylic monomers are methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate. ) At least one type from the group consisting of acrylate, 2-ethylbutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and heptyl (meth)acrylate, preferably 2-ethylhexyl acrylate do.

Unless otherwise specified in the specification, “(meth)acrylic” means that both “acrylic” and “methacrylic” are possible.

The C1 to C12 alkyl (meth)acrylic monomer is used in an amount of 0.1 to 10% by weight, preferably 0.5 to 3% by weight, based on the total 100% by weight of the monomers. If the content is less than the above range, the synergistic effect of Tg cannot be obtained, and if the content exceeds the above range, since the content of other monomers is relatively reduced, it is difficult to control the tensile strength, elongation, stress, and durability against sweat of the dip molded article. , It is appropriately used within the above range.

Other monomers constituting the carboxylic acid-modified nitrile-based copolymer, that is, a conjugated diene-based monomer, an ethylenically unsaturated nitrile-based monomer, and an ethylenically unsaturated acid monomer will be described in detail below.

First, the conjugated diene-based monomer is a monomer constituting the carboxylic acid-modified nitrile-based copolymer according to the present invention, and specific examples include 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, and 2-ethyl -1,3-butadiene, 1,3-pentadiene, and one or more selected from the group consisting of isoprene, of which 1,3-butadiene and isoprene are preferred, and among them, 1,3-butadiene is most preferably used. do.

The conjugated diene-based monomer is 40 to 89% by weight, preferably 45 to 80% by weight, more preferably 50 to 78% by weight, within 100% by weight of the total content of all monomers constituting the carboxylic acid-modified nitrile-based copolymer Included as. If the content is less than the above range, the dip molded article becomes hard and the fit is deteriorated. On the contrary, if the content exceeds the above range, the oil resistance of the dip molded article is deteriorated and the tensile strength is lowered.

As another monomer constituting the carboxylic acid-modified nitrile-based copolymer according to the present invention, the ethylenically unsaturated nitrile-based monomer is acrylonitrile, methacrylonitrile, fumaronitrile, α-chloronitrile and α-cyano ethyl acryl. Among them, acrylonitrile and methacrylonitrile are preferable, and among them, acrylonitrile is most preferably used.

The ethylenically unsaturated nitrile-based monomer is 10 to 50% by weight, preferably 15 to 45% by weight, more preferably 20 to 40% by weight within 100% by weight of the total content of all monomers constituting the carboxylic acid-modified nitrile-based copolymer. Included in %. If the content is less than the above range, the oil resistance of the dip molded article deteriorates and the tensile strength is lowered. Conversely, if the content exceeds the above range, the dip molded article becomes stiff and wearability deteriorates.

In addition, as another monomer constituting the carboxylic acid-modified nitrile-based copolymer according to the present invention, the ethylenically unsaturated acid monomer is an ethylenically unsaturated acid monomer containing at least one acidic group selected from the group consisting of a carboxyl group, a sulfonic acid group, and an acid anhydride group. to be. Examples of the ethylenically unsaturated acid monomer include ethylenically unsaturated carboxylic acid monomers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, and fumaric acid; Polycarboxylic anhydrides such as maleic anhydride and citraconic anhydride; Ethylenically unsaturated sulfonic acid monomers such as styrene sulfonic acid; And ethylenically unsaturated polycarboxylic acid partial ester monomers such as monobutyl fumarate, monobutyl maleate, and mono-2-hydroxypropyl maleate. Among these, methacrylic acid is particularly preferred. These ethylenically unsaturated acid monomers may be used in the form of an alkali metal salt or an ammonium salt.

The ethylenically unsaturated acid monomer is 0.1 to 10% by weight, preferably 0.5 to 9% by weight, more preferably 1 to 8, within 100% by weight of the total content of the total monomers constituting the carboxylic acid-modified nitrile-based copolymer. It is included in weight percent. If the content is less than the above range, the tensile strength of the dip molded article is lowered, and if the content exceeds the above range, the dip molded article becomes hard and the fit is deteriorated.

The carboxylic acid-modified nitrile-based copolymer according to the present invention may optionally further include the ethylenically unsaturated nitrile monomer and another ethylenically unsaturated monomer copolymerizable with the ethylenically unsaturated acid monomer.

The copolymerizable ethylenically unsaturated monomers include vinyl aromatic monomers including styrene, alkyl styrene, and vinyl naphthalene; Fluoroalkylvinyl ethers including fluoro ethyl vinyl ethers; (Meth)acrylamide, N-methylol (meth)acrylamide, N,N -dimethylol (meth)acrylamide, N-methoxy methyl (meth)acrylamide and N -propoxy methyl (meth)acrylamide Ethylenically unsaturated amide monomer containing; Non-conjugated diene monomers including vinyl pyridine, vinyl norbornene, dicyclopentadiene and 1,4-hexadiene; Trifluoroethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, dibutyl maleate, dibutyl fumarate, diethyl maleate, methoxymethyl (meth)acrylate, ethoxyethyl (meth)acrylate, (meth)acrylic acid Methoxyethoxyethyl, (meth) acrylate cyanomethyl, (meth) acrylate 2-cyanoethyl, (meth) acrylate 1-cyanopropyl, (meth) acrylate 2-ethyl-6-cyanohexyl, (meth) ) Ethylenically unsaturated carboxylic acid esters including 3-cyanopropyl acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, glycidyl (meth) acrylate and dimethylamino ethyl (meth) acrylate At least one selected from the group consisting of monomers is used.

The amount of the ethylenically unsaturated nitrile-based monomer and other ethylenically unsaturated monomer copolymerizable therewith may be used within 0.001 to 20% by weight within 100% by weight of the total content of all monomers constituting the carboxylic acid-modified nitrile-based copolymer. If the content exceeds 20% by weight, the balance between the soft fit and the tensile strength is not well matched, so it is appropriately used within the above range.

As already mentioned, the carboxylic acid-modified nitrile-based copolymer latex of the present invention can be prepared by emulsion polymerization by adding an emulsifier, a polymerization initiator, and a molecular weight modifier to a monomer constituting the carboxylic acid-modified nitrile-based copolymer.

Specifically, the carboxylic acid-modified nitrile-based copolymer latex

(Step a) adding a conjugated diene monomer, an ethylenically unsaturated nitrile monomer, an ethylenically unsaturated acid monomer, a C1 to C12 alkyl (meth)acrylic monomer, an emulsifier, a polymerization initiator, and deionized water to the polymerization reactor;

(Step b) performing emulsion polymerization; And

(Step c) It is produced through the step of stopping polymerization.

In step a, the conjugated diene-based monomer, ethylenically unsaturated nitrile-based monomer, ethylenically unsaturated acid monomer, C1 to C12 alkyl (meth)acrylic, monomer, emulsifier and polymerization initiator are added to the polymerization reactor at one time or continuously Can be put into. In addition, they may add all of each used content to the polymerization reactor at once, or add a part of the content to the polymerization reactor, and then continuously supply the remaining content to the polymerization reactor again.

Hereinafter, the composition used for the copolymerization will be described in more detail.

Although it does not specifically limit as an emulsifier, For example, anionic surfactant, nonionic surfactant, cationic surfactant, amphoteric surfactant, etc. can be used. Among them, an anionic surfactant selected from the group consisting of alkylbenzene sulfonates, aliphatic sulfonates, higher alcohol sulfates, α-olefin sulfonates and alkyl ether sulfates may be particularly preferably used.

At this time, the emulsifier is used in an amount of 0.3 to 10 parts by weight, preferably 0.8 to 8 parts by weight, more preferably 1.5 to 6 parts by weight, based on 100 parts by weight of the monomer constituting the carboxylic acid-modified nitrile-based copolymer. If the content is less than the above range, stability during polymerization is deteriorated. On the contrary, if the content exceeds the above range, foaming increases, making it difficult to manufacture a dip molded article.

Although it does not specifically limit as a polymerization initiator, A radical initiator can be specifically used. Examples of the radical initiator include inorganic peroxides such as sodium persulfate, potassium persulfate, ammonium persulfate, potassium perphosphate, and hydrogen peroxide; 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; Azobis isobutyronitrile, azobis-2,4-dimethylvaleronitrile, azobiscyclohexane carbonitrile, and azobis isobutyric acid (butyric acid) methyl. Among these radical initiators, inorganic Peroxide is more preferable, and among them, persulfate may be particularly preferably used.

The amount of the polymerization initiator is included in an amount of 0.01 to 2 parts by weight, preferably 0.02 to 1.5 parts by weight, based on 100 parts by weight of all monomers constituting the carboxylic acid-modified nitrile-based copolymer. If the content is less than the above range, the polymerization rate is lowered and it is difficult to manufacture a final product. On the contrary, if the content exceeds the above range, the polymerization rate becomes too fast and polymerization cannot be controlled.

The activator is not particularly limited and may be used commonly known in the art, for example, sodium formaldehyde sulfoxylate, sodium ethylenediamine tetraacetate, ferrous sulfate, dextrose, sodium pyrrolate and sodium sulfite. One or more selected from the group may be used.

Although it does not specifically limit as a molecular weight modifier, For example, Mercaptans, such as α-methylstyrene dimer, t-dodecyl mercaptan, n-dodecyl mercaptan, and octyl mercaptan; Halogenated hydrocarbons such as carbon tetrachloride, methylene chloride, and methylene bromide; And sulfur-containing compounds such as tetraethyl thiuram disulfide, dipentamethylene thiuram disulfide, and diisopropylxanthogen disulfide. These molecular weight modifiers may be used alone or in combination of two or more. Among these, mercaptans are preferable, and t-dodecyl mercaptan may be more preferably used.

The amount of the molecular weight modifier to be used varies depending on the type, but is 0.1 to 2.0 parts by weight, preferably 0.2 to 1.5 parts by weight, more preferably, based on 100 parts by weight of all monomers constituting the carboxylic acid-modified nitrile-based copolymer. It is used in an amount of 0.3 to 1.0 parts by weight. If the content is less than the above range, the physical properties of the dip-molded article are markedly deteriorated, whereas if the content exceeds the above range, polymerization stability is deteriorated.

In addition, when the latex of the present invention is polymerized, subsidiary materials such as a chelating agent, a dispersing agent, a pH adjusting agent, a deoxygenating agent, a particle size adjusting agent, an anti-aging agent, and an oxygen scavenger may be added as needed.

The method of introducing the monomer mixture constituting the carboxylic acid-modified nitrile-based copolymer is not particularly limited, and a method of introducing the monomer mixture into the polymerization reactor at once, a method of continuously introducing the monomer mixture into the polymerization reactor, and a part of the monomer mixture You may use any method of the method of putting into the polymerization reactor and continuously supplying the remaining monomers to the polymerization reactor.

In step b, the polymerization temperature during emulsion polymerization may be usually 10 to 90°C, preferably 20 to 80°C. It may be more preferably 25 to 75 ℃, but is not particularly limited.

In step c, the conversion rate when stopping the polymerization reaction may be 85% or more, preferably 88 to 99.9%, more preferably 90 to 99%, and the unreacted monomer is removed after stopping the polymerization reaction. Then, by adjusting the solid content concentration and pH, a carboxylic acid-modified nitrile-based copolymer latex for dip molding can be obtained.

The carboxylic acid-modified nitrile-based copolymer latex has a glass transition temperature of -20 to -5°C, preferably -15 to -10°C. When the glass transition temperature of the latex is less than the above range, the tensile strength is significantly lowered or the wearing feeling is deteriorated due to the stickiness of the glove. On the contrary, when the glass transition temperature is higher than the above range, the dip molded product cracks, which is not preferable. The glass transition temperature can be adjusted by adjusting the content of the conjugated diene monomer, and can be measured by differential scanning calorimetry.

The average particle diameter of the dip molding latex may be 100 to 200 nm, preferably 110 to 180 nm, more preferably 120 to 160 nm. If the average particle diameter of the dip molding latex falls within the above range, the tensile strength of the manufactured dip molded article may be improved.

The average particle diameter of the dip molding latex can be adjusted by adjusting the type or content of the emulsifier, and the average particle diameter can be measured by a laser scattering analyzer (Nicomp).

In addition, the solid content concentration of the dip molding latex composition may be 10 to 40% by weight, preferably 15 to 35% by weight, more preferably 15 to 30% by weight. The pH of the dip molding latex composition may be 8 to 12, preferably 9 to 11, more preferably 9.3 to 10.5. At this time, Tg can be adjusted according to the composition of the monomer to be used, and the average particle diameter can be adjusted according to the type or content of the emulsifier.

According to another embodiment of the present invention, the carboxylic acid-modified nitrile-based copolymer latex prepared through the above steps is used as it is as a latex composition for dip molding, or the addition of a composition (or additive) commonly used in manufacturing a dip molded article Through the dip to prepare a latex composition for molding.

Specifically, additives commonly used during dip molding, such as a sulfur crosslinking agent for dip molding, a vulcanization accelerator, a metal oxide such as zinc oxide, a pigment such as titanium dioxide, a filler such as silica, a thickener, a pH adjuster such as ammonia or alkali hydroxide, etc. It can be added to prepare a composition for dip molding.

As such a latex composition for dip molding contains a triblock copolymer with a carboxylic acid-modified nitrile-based copolymer, the stability of the latex is increased to reduce the occurrence of coagulation in the dip molding process, and the tensile strength and elongation of the manufactured dip molded product Raises.

The latex composition for dip molding comprising the various additives and the triblock copolymer contains 80 to 99% by weight, preferably 85 to 98% by weight, more preferably 88 to 97% by weight of the carboxylic acid-modified nitrile-based copolymer. It includes, and within this range, the physical properties of the dip-molded product can be secured.

In addition, the latex composition for dip molding according to the present invention has a solid content concentration of 5 to 40% by weight, preferably 8 to 35% by weight, and more preferably 10 to 33% by weight. If the concentration is too low, the efficiency of transport of the latex composition decreases, and if the concentration is too high, the solid content concentration may cause problems such as storage stability due to an increase in viscosity, and therefore, it is appropriately adjusted within the above range.

The pH of the latex composition for dip molding may be 8 to 12, preferably 9 to 11, more preferably 9.3 to 10.5, and if the pH concentration is out of the above range, the stability of the latex composition for dip molding may decrease. have.

At this time, the pH of the dip molding latex composition can be adjusted by adding a certain amount of a pH adjusting agent during the production of the dip molding latex, and as the pH adjusting agent, mainly 1 to 5% potassium hydroxide aqueous solution or 1 to 5% aqueous ammonia can be used. have.

Dip molded product

In addition, the present invention provides a dip molded article prepared from the latex composition for dip molding.

The dip-molded article according to an embodiment of the present invention is characterized in that the nitrogen content is 6.69% by weight to 8.94% by weight based on the total weight of the dip-molded article.

The dip molded article according to an embodiment of the present invention is not particularly limited and may be manufactured through a method commonly known in the art, for example, a direct immersion method, an anode adhesion immersion method, a Teague adhesion needle It can be manufactured using a method such as a paper method. Preferably, an anode adhesion immersion method may be used, and in the case of manufacturing a dip molded article by using the anode adhesion immersion method, there is an advantage of manufacturing a dip molded article having a uniform thickness.

As a specific example, the dip-molded product includes a step of immersing a hand-shaped dip molding mold in a coagulant solution and attaching a coagulant to the surface of the dip molding mold (step a); Forming a dip molding layer by immersing the dip molding mold attached to the surface of the coagulant in the latex composition for dip molding (step b); And heating the dip molding layer to crosslink the latex resin.

The step a is a step for attaching a coagulant to the surface of the hand-shaped dip molding mold, and although not particularly limited, the dip molding mold is immersed in a coagulant solution for at least 1 minute, and dried at 70°C to 150°C after removal. I can.

The coagulant solution is a solution obtained by dissolving a coagulant in water, alcohol, or a mixture thereof, and may generally contain 5 to 50% by weight of a coagulant, and preferably 10 to 40% by weight of a coagulant.

The coagulant is not particularly limited, 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; Sulfates such as calcium sulfate, magnesium sulfate and aluminum sulfate, and the like can be used. Preferably, it may be calcium chloride, calcium nitrate or a combination thereof.

The step b is a step for forming a dip molding layer from the latex composition for dip molding according to the present invention on the dip molding mold to which the coagulant is attached, and the dip molding mold to which the coagulant is attached to the dip molding latex composition The dip molding layer can be formed by taking out after being immersed in for 1 minute or more.

The step c is a step for obtaining a dip molded product by crosslinking a latex resin on the dip molding layer, and may be performed by heat treatment of the dip molding layer.

The heat treatment is not particularly limited, for example, after a first heat treatment at 70 to 150° C. for 1 minute to 10 minutes, and then a secondary heat treatment at 100 to 180° C. for 5 to 30 minutes may be performed.

During the heat treatment, the water component is first evaporated from the dip molding layer, and curing of the latex resin of the dip molding layer occurs through crosslinking, thereby obtaining a dip molded article.

The dip molded article is not particularly limited and can be applied to various latex industries, but may be applied to one or more molded articles selected from the group consisting of, for example, inspection gloves, condoms, catheters, industrial gloves, household gloves, and health care products. .

Hereinafter, preferred embodiments are presented to aid in the understanding of the present invention, but the following examples are only illustrative of 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. It is natural that changes and modifications fall within the scope of the appended claims.

[Example]

Example 1: Dip molding latex composition and dip molded article manufacturing

(Manufacture of carboxylic acid-modified nitrile-based copolymer latex)

Agitator, thermometer, cooler, nitrogen gas inlet and a 10L high-pressure reactor equipped to continuously input monomers, emulsifiers, and polymerization initiators were substituted with nitrogen, and then acrylonitrile 37.0% by weight, 1,3-butadiene 56.5 2.5 parts by weight of sodium alkylbenzene sulfonate, 0.6 parts by weight of t-dodecyl mercaptan and 140 parts by weight of ion-exchanged water based on 100 parts by weight of the monomer mixture of 5.5% by weight, 5.5% by weight of methacrylic acid and 1.0% by weight of 2-ethylhexyl acrylate Part was added and the temperature was raised to 40°C.

After the temperature was raised, 0.25 parts by weight of potassium persulfate, which is a polymerization initiator, was added to initiate polymerization, and when the conversion rate reached 95%, 0.1 parts by weight of sodium dimethyl dithiocarbamate was added to stop the polymerization.

Unreacted material was removed through a deodorization process, and ammonia water, antioxidant, and antifoaming agent were added to prepare a carboxylic acid-modified nitrile-based copolymer latex having a solid content of 45% and a pH of 8.3.

(Preparation of latex composition for dip molding)

To prepare a carboxylic acid-modified nitrile-based copolymer latex containing the reactive compound prepared in Preparation Example 1, and add 2.0 parts by weight of a 1.25% potassium hydroxide solution, an appropriate amount of distilled water, 1 part by weight of titanium oxide, and 1.2 parts by weight of zinc oxide And mixed to prepare a latex composition for dip molding having a solid content concentration of 15% and a pH of 9.3. At this time, the parts by weight are shown based on 100 parts by weight of the latex composition for dip molding.

(Deep molded product manufacturing)

A coagulant solution was prepared by mixing 12 parts by weight of calcium nitrate, 87.9 parts by weight of neutral water, and 0.1 parts by weight of a wetting agent (Teric 320, Huntsman Corporation, Australia). At this time, parts by weight are shown based on 100 parts by weight of the coagulant solution.

The hand-shaped ceramic mold was immersed in the coagulant solution for 10 seconds, pulled out, and dried at 80° C. for 4 minutes to apply the coagulant to the hand-shaped ceramic mold.

Thereafter, the mold coated with the coagulant was immersed in the latex composition for dip molding for 10 seconds, pulled out, dried at 80° C. for 2 minutes, and then immersed in water for 1 minute. After drying the mold again at 80 for 3 minutes, it was crosslinked at 120°C for 20 minutes. The crosslinked dip molded layer was peeled off from the hand-shaped mold to obtain a glove-shaped dip molded article.

Next, the mold coated with the coagulant was immersed in the latex composition for dip molding for 1 minute, pulled up, dried at 120° C. for 4 minutes, and then immersed in water or hot water for 3 minutes. Again, the mold was dried at 120° C. for 3 minutes and then crosslinked at 130° C. for 20 minutes. The crosslinked dip molded layer was peeled off from the hand-shaped mold to obtain a glove-shaped dip molded article.

Example 2: Dip molding latex composition and dip molding product manufacturing

A latex composition for dip molding was prepared in the same manner as in Example 1, except that 2-ethylhexyl acrylate was used in an amount of 0.1% by weight, and a dip molded article in the form of a glove was prepared using this.

Example 3: Manufacturing of latex composition for dip molding and dip molded product

A latex composition for dip molding was prepared in the same manner as in Example 1, except that 2-ethylhexyl acrylate was used in an amount of 10% by weight, and a dip molded article in the form of a glove was prepared using this.

Example 4: Dip molding latex composition and dip molding product manufacturing

Except that butyl acrylate was used instead of 2-ethylhexyl acrylate, a latex composition for dip molding was prepared in the same manner as in Example 1, and a dip molded article in the form of a glove was prepared using this.

Comparative example 1: Dip molding latex composition and dip molding product manufacturing

2-ethylhexyl acrylate was not used and 1,3-butadiene was used in the same manner as in Example 1, except that 57.5% by weight of 1,3-butadiene was used. A molded article was prepared.

Comparative example 2: Dip molding latex composition and dip molding product manufacturing

A latex composition for dip molding using the same method as in Example 1, except that 1.0 part by weight of sulfur and 0.5 part by weight of zinc dibutyldithiocarbamate were used in the manufacture of the dip molded product, and a glove form using the same. A dip molded article was prepared.

Comparative example 3: Manufacturing of latex composition for dip molding and dip molded product

A latex composition for dip molding using the same method as in Comparative Example 1, except that 1.0 part by weight of sulfur and 0.5 part by weight of zinc dibutyldithiocarbamate were used in the manufacture of the dip molded product, and a glove form using the same. A dip molded article was prepared.

Comparative example 4: Dip molding latex composition and dip molding product manufacturing

A latex composition for dip molding was prepared in the same manner as in Example 1, except that 2-ethylhexyl acrylate was used in an amount of 0.05% by weight, and a dip molded article in the form of a glove was prepared using this.

Comparative example 5: Dip molding latex composition and dip molding product manufacturing

A latex composition for dip molding was prepared in the same manner as in Example 1, except that 2-ethylhexyl acrylate was used in an amount of 15% by weight, and a dip molded article in the form of a glove was prepared using this.

Experimental example 1: Evaluation of properties of latex composition for dip molding

The average particle diameter of the carboxylic acid-modified nitrile-based copolymer latex prepared in Example 1 and Comparative Example 1, gel content (%) at 130°C, glass transition temperature (Tg), surface tension (mN/m), and molecular weight ( kDa) was measured respectively. The results are shown in Table 1 below.

(1) Glass transition temperature (℃)

The glass transition temperature was measured according to a conventional method using Differential Scanning Calotimetry, and the average particle diameter was measured according to a conventional method using a laser scattering analyzer (Nicomp).

(2) gel content

The gel content was determined by drying each latex at 25℃ and 60% humidity for 48 hours or more to prepare a polymer film, cut into pieces, measure the weight (W0), and put it in a bucket of #200 mesh, then 200 ml of methyl ethyl kecon. The (MEK) solution was immersed in the solution for 48 hours, taken out, dried in an oven at 130° C., and the weight (W1) was measured. The ratio of the weight of the polymer film (W0) and the weight (W1) of the polymer film after drying in the oven was calculated as a percentage to obtain the measured #200 mesh in a bucket.

(3) Surface tension

The surface tension was obtained by measuring the force required to remove the platinum summons from the sample solution when the platinum summons were suspended horizontally using a surface tension meter to contact each sample solution (latex) and pulled.

(4) molecular weight

Molecular weight (kDa) is obtained by drying each latex at 130°C. Each polymer film is finely cut, immersed in a tetrahydrofuran (THF) solution, and the dissolved liquid is filtered and compared with a standard sample using GPC (gel permeation chromatography). It was obtained by measuring the relative molecular weight.

Average particle diameter
(nm) Gel content (% at 130℃) Glass transition temperature
(Tg, ℃) Surface tension
(mN/m) Molecular Weight
(kDa) Example 1 130.6 56.9 -12.29 31.62 12.1 Example 2 131.3 56.8 -12.30 31.20 13.0 Example 3 135.2 55.2 -12.31 31.10 13.2 Example 4 133.0 57.5 -12.30 32.05 10.5 Comparative Example 1 121.4 61.2 -12.30 32.08 8.6

Experimental example 2: Evaluation of properties of dip molded products

The physical properties of the dip-molded products prepared in Examples and Comparative Examples were measured, and the obtained results are shown in Table 2 below.

(1) Max load (N), tensile strength, elongation, stress at 300% and stress at 500%

Each of the dip-molded products was prepared as a dumbbell-shaped specimen according to ASTM D-412, and a cross head speed was set to 500 using a Universal Testing Machine (UTM) device (model name: 4466, Instron) according to ASTM D638. After pulling at mm/min, the point at which each specimen was cut was measured.

Max load (N) represents the external force applied to the specimen at the time the specimen is cut, and the tensile strength was calculated by Equation 1 below.

In addition, the elongation (%) was calculated by the following equation (2), the stress (MPa) at 300% is the tensile strength when the specimen is elongated to three times the initial length, and the stress (MPa) at 500% is the specimen Tensile strength when elongated to 5 times the initial length was measured.

[Equation 1]

[Equation 2]

(2) sweat resistance

After each dip-molded product was cut into an S-shaped specimen and manufactured, each specimen was immersed in an artificially created sweat solution, increased to 200% of the initial length at a rate of once every 2 seconds, and then decreased repeatedly to cut the specimen. The number of times up to the time point was measured.

Max
load(N) The tensile strength
(MPa) Elongation
(%) Stress
(MPa, at 300%) Stress
(MPa, at 500%) Durability (times) Example 1 6.0 39.0 606.4 6.8 19.3 241 Example 2 6.0 38.4 607.2 6.8 19.2 250 Example 3 6.0 40.1 607.5 6.8 19.1 260 Example 4 6.1 38.5 607.2 6.7 19.0 280 Comparative Example 1 6.0 38.4 608.1 6.8 18.9 213 Comparative Example 2 6.7 41.5 606.0 6.0 16.7 384 Comparative Example 3 6.4 39.7 599.9 6.1 17.3 258 Comparative Example 4 6.5 40.2 600.2 6.2 16.5 230 Comparative Example 5 6.4 40.2 602.2 6.1 16.8 250

As shown in Table 2, in the case of the dip-molded article of Example 1 using 2-ethylhexyl acrylate as a comonomer according to the present invention, compared to the dip-molded article of Comparative Example 1, tensile strength and stress were excellent, and in particular, Excellent durability against sweat.

The dip-molded products of Comparative Examples 2 and 3 were dip-molded products prepared by performing sulfur crosslinking, and were more durable than the dip-molded products of Example 1, but the allergic problem caused by sulfur could not be solved.

Therefore, the latex composition for dip molding according to the present invention uses an alkyl (meth)acrylic monomer as a comonomer to prepare a carboxylic acid-modified nitrile-based copolymer latex, and the dip-molded product prepared using this is equivalent to or more than sulfur crosslinking physical properties. Can be secured, so it can be used as a substitute for existing sulfur crosslinked products.

The latex composition for dip molding according to the present invention can be used to manufacture latex articles such as health care products such as various industrial and household gloves.

Claims (12)

A conjugated diene-based monomer, an ethylenically unsaturated nitrile-based monomer, an ethylenically unsaturated acid monomer, and a C1 to C12 alkyl (meth)acrylic monomer are copolymerized with a carboxylic acid-modified nitrile-based copolymer latex,
The carboxylic acid-modified nitrile-based copolymer is based on 100% by weight of the total monomer,
Conjugated diene monomer 40 to 89 wt%, ethylenically unsaturated nitrile monomer 10 to 50 wt%, ethylenically unsaturated acid monomer 0.1 to 10 wt%, and C1 to C12 alkyl (meth)acrylic monomer 0.1 to 10 wt% are copolymerized Dip molding latex composition, characterized in that the. delete The method of claim 1,
The conjugated diene-based monomer is at least one selected from the group consisting of 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 1,3-pentadiene, and isoprene. Dip molding latex composition, characterized in that. The method of claim 1,
The ethylenically unsaturated nitrile-based monomer is a latex for dip molding, characterized in that at least one selected from the group consisting of acrylonitrile, methacrylonitrile, fumaronitrile, α-chloronitrile and α-cyano ethyl acrylonitrile Composition. The method of claim 1,
The ethylenically unsaturated acid monomer is composed 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 maleic acid. Dip molding latex composition, characterized in that at least one selected from the group. The method of claim 1,
The C1 to C12 alkyl (meth)acrylic monomers are methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate. ) Acrylate, 2-ethylbutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and a latex composition for dip molding, characterized in that at least one type from the group consisting of heptyl (meth) acrylate. The method of claim 1,
The carboxylic acid-modified nitrile-based copolymer is a latex composition for dip molding, characterized in that it is copolymerized by further comprising an ethylenically unsaturated monomer as a comonomer. The method of claim 7,
The ethylenically unsaturated monomers are styrene, alkyl styrene, vinyl naphthalene, fluoroethyl vinyl ether, (meth)acrylamide, N-methylol (meth)acrylamide, N,N-dimethylol (meth)acrylamide, N- Methoxy methyl (meth)acrylamide, N-propoxy methyl (meth)acrylamide, vinyl pyridine, vinyl norbornene, dicyclopentadiene, 1,4-hexadiene, trifluoroethyl (meth)acrylate, (meth) )Tetrafluoropropyl acrylate, dibutyl maleate, dibutyl fumarate, diethyl maleate, methoxymethyl (meth)acrylate, ethoxyethyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, cyanic (meth)acrylate Nomethyl, (meth)acrylic acid 2-cyanoethyl, (meth)acrylic acid 1-cyanopropyl, (meth)acrylic acid 2-ethyl-6-cyanohexyl, (meth)acrylic acid 3-cyanopropyl, (meth) It is characterized in that it is at least one selected from the group consisting of hydroxyethyl acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, glycidyl (meth)acrylate, and dimethylamino ethyl (meth)acrylate. The latex composition for dip molding. The method of claim 1,
The carboxylic acid-modified nitrile-based copolymer latex has a glass transition temperature of -20 to -5°C, and an average particle diameter of 100 to 200 nm. The method of claim 1,
The latex composition for dip molding is a latex composition for dip molding, characterized in that the solid content concentration is 10 to 40% by weight, and the pH is 8 to 12. A dip-molded article, characterized in that it is manufactured by dip molding with the latex composition for dip molding of any one of claims 1 and 3 to 10. The method of claim 11,
The dip molded article is a dip molded article, characterized in that at least one molded article selected from the group consisting of inspection gloves, condoms, catheters, industrial gloves, household gloves, and health care products.