KR20170062730A - Latex composition for dip-forming and the product prepared thereby - Google Patents

Abstract

The present invention relates to a latex composition for deep molding and a molded article produced therefrom. More specifically, the present invention relates to a latex composition for deep- Which is excellent in workability and durability. Thus, it is possible to produce a molded article having an antimicrobial effect as well as showing a smooth feeling of tear without being torn even at a thin thickness.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a latex composition for deep-

The present invention relates to a latex composition for deep molding which is excellent in durability and capable of producing a dip molded article having an antibacterial effect and soft touch, and a molded article produced therefrom.

Disposable rubber gloves used variously in everyday life such as housework, food industry, electronics industry, and medical field are made by dip molding of natural rubber or carboxylic acid modified nitrile copolymer latex. In recent years, carbonic acid denatured nitrile gloves have been attracting attention in the disposable glove market due to allergies and unstable supply and demand due to the natural protein of natural rubber.

A latex composition in which sulfur and a vulcanization accelerator are mixed with a carboxylic acid-modified nitrile-based copolymer latex such as an acrylic acid-acrylonitrile-butadiene copolymer latex, which does not cause an allergic reaction, Many molded gloves were used.

In the process for producing such gloves, since the sulfur and the vulcanization accelerator are mixed in the latex and then subjected to a long-time stirring aging process for more than 24 hours, there is a problem that the productivity is lowered. Rubber gloves are worn for a long period of time, and when the work is continued, the smell due to sulfur is generated to give an uncomfortable feeling, the color of the glove is discolored, the product value is lowered, and some users are allergic to cause a tingling.

In the Republic of Korea Patent Publication No. 2010-0066005 call has been proposed a technique of adding a collagen peptide (collagen peptide) and aloe vera extract (aloe vera extracts) the natural rubber latex. Skin irritation could be reduced to some extent by the addition of the above composition, but no fundamental problem was solved by using sulfur and vulcanization accelerators.

When sulfur and vulcanization accelerators are not used, the durability of the gloves is poor, and when the gloves are worn for a long period of time, the glove tears, and the chemical resistance of the gloves may be deteriorated. In the case of gloves without sulfur and vulcanization accelerators, the durability and chemical resistance of the gloves are important factors in determining the quality of the gloves. Therefore, it is necessary to develop a technique that does not deteriorate the quality of thin gloves, such as durability and chemical resistance, of the glove, even if the sulfur and vulcanization accelerator is not used or its use is minimized.

On the other hand, the carboxylic acid-modified nitrile-based copolymer latex for producing rubber gloves has a structure in which a certain proportion of acrylic acid, acrylonitrile and butadiene is present, that is, in the form of organic acid segments. Recently, There has been an attempt to secure physical properties such as tensile strength and durability required as gloves.

For example, WO 2006/068394 proposes a method of carboxylating acrylonitrile, adding a metal oxide such as zinc oxide or another metal salt thereto, and crosslinking by ionic bonds therebetween . However, such crosslinking alone does not satisfy a sufficient level of tensile strength and durability, and some metals have remained in the final molded product, resulting in a new problem in which physical properties are deteriorated and skin irritation is caused.

Furthermore, in the rubber glove market, which has recently replaced natural rubber gloves, the goal is to manufacture thin, yet tear-resistant gloves by raising the production line to increase productivity.

In the past, if disposable nitrile gloves weighing 4 grams were generally used, a glove with a tensile strength of 6 N or more is required even if it is thinner to 3.2 g at present. However, it is not easy to obtain 6N tensile strength in thin gloves of 3.2g even when aging process is performed.

However, when the concentration of the latex composition is simply lowered to make the glove thinner, there is a problem in workability in manufacturing the glove. Therefore, the workability in the production of the glove is good and the tensile strength is high so that a technique of making a glove that does not tear easily .

In addition to these workings, wearing comfort when using gloves is also becoming an important part. The fit of the glove is related to the modulus value, and the higher the value, the stiffer fit. Therefore, a technique of lowering the modulus value so as to have a soft touch is required.

Korean Patent Publication No. 2010-0066005, "Rubber composition and rubber gloves made therefrom" WO < RTI ID = 0.0 > 2011/068394 < / RTI > "vulcanization accelerators and sulfur-

As a result of various studies to solve the above problems, the present inventors have found that chitosan, which is a water-soluble polymer as a crosslinkable material through hydrogen bonding, is selected, and when it is mixed with latex, it is improved in workability, And that the physical properties of the produced molded article are improved, thereby completing the present invention.

Accordingly, it is an object of the present invention to provide a latex composition for deep molding, which increases the syneresis time during the deep molding step and reduces the occurrence of tearing even at a thin thickness due to excellent durability, especially tensile strength, even when the use of sulfur / vulcanization accelerator is minimized .

Another object of the present invention is to provide a molded article produced from the latex composition for deep molding and having excellent tensile strength, soft feeling, and antibacterial effect.

It is still another object of the present invention to provide a method for producing a molded article improved in workability using the latex composition for dip molding.

In order to achieve the above object, the present invention provides a latex composition for deep molding comprising a carboxylic acid-modified nitrile-based copolymer latex and chitosan.

The present invention also provides a dip-formed article produced by dip-molding the latex composition for dip molding.

The present invention also provides a process for preparing a coagulant solution comprising: a) applying a coagulant solution to a mold and drying; b) applying a latex composition for dip molding to a mold to which the coagulant is applied to form a dip molding layer; c) crosslinking said dip molding layer; And d) peeling the cross-linked dip-formed layer from the mold to obtain a dip-molded article,

Wherein the latex composition for dip molding is the latex composition for dip molding as described above.

The carboxylic acid-modified nitrile-based copolymer latex according to the present invention is obtained by mixing chitosan, which is a water-soluble polymer capable of crosslinking by hydrogen bonding with a carboxylic acid-modified nitrile-based copolymer, into a latex, Is excellent.

In addition, the manufactured gloves have a higher tensile strength than the conventional gloves and have an advantage in that they are not torn even when they are made thin, and the modulus of the gloves is lower than that of the existing gloves.

In addition, it is possible to manufacture gloves having antimicrobial properties exhibited by chitosan itself, and it is possible to prevent skin diseases caused by allergic reactions due to the antibacterial properties, thereby enhancing the satisfaction of consumers.

In addition, since the use of sulfur and vulcanization accelerator can be minimized, it is possible to produce a dip-molded article, so that the unpleasant smell caused by sulfur and the discoloration of the molded article caused by the use of sulfur and vulcanization accelerator is reduced, .

When manufacturing a molded article such as a rubber glove through a deep molding process, a specific composition is added or a process parameter is changed to improve the physical properties and the deep molding process of the resulting molded article. In the present invention, chitosan which is well mixed with latex and has a functional group capable of hydrogen bonding with carboxylic acid functional group is mixed with latex for dip molding.

Latex composition for deep molding

The latex composition for dip molding according to the present invention comprises a carboxylic acid-modified nitrile-based copolymer latex and chitosan.

The carboxylic acid-modified nitrile-based copolymer latex is prepared by adding an emulsifier, a reactive compound, a polymerization initiator, a molecular weight modifier, and other additives to a monomer, followed by emulsion polymerization.

The monomer is composed of a conjugated diene-based monomer, an ethylenically unsaturated nitrile-based monomer, an ethylenically unsaturated acid monomer, and an unsaturated ethylenic monomer copolymerizable therewith.

Specific examples of the conjugated diene monomer as the monomer constituting the carboxylic acid-modified nitrile-based copolymer according to the present invention include 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, , 3-butadiene, 1,3-pentadiene and isoprene. Of these, 1,3-butadiene and isoprene are preferable, and 1,3-butadiene is most preferably used among them.

The conjugated diene monomer is contained in an amount of 40 to 89% by weight, preferably 45 to 80% by weight, more preferably 50 to 78% by weight, in the total amount of 100% by weight of the total monomers constituting the carboxylic acid modified nitrile- . If the content is less than the above range, the dip molded article becomes hard and the feeling of wearing becomes worse. On the other hand, if the content exceeds the above range, the oil resistance of the dip molded article is deteriorated and the tensile strength is lowered.

As the other monomers constituting the carboxylic acid-modified nitrile-based copolymer according to the present invention, the ethylenically unsaturated nitrile-based monomer may be at least one selected from the group consisting of acrylonitrile, methacrylonitrile, fumaronitrile,? -Cyanonetyl acrylate Acrylonitrile and ronitrile. Of these, acrylonitrile and methacrylonitrile are preferable, and acrylonitrile is most preferably used among them.

The ethylenically unsaturated nitrile monomer is contained in an amount of 10 to 50% by weight, preferably 15 to 45% by weight, more preferably 20 to 40% by weight, based on 100% by weight of the total monomers constituting the carboxylic acid-modified nitrile- %. If the content is less than the above range, the oil resistance of the dip molded article deteriorates and the tensile strength lowers. On the other hand, if the content exceeds the above range, the dip molded article becomes hard and the feeling of wearing becomes poor.

As the other monomers constituting the carboxylic acid-modified nitrile-based copolymer according to the present invention, the ethylenic unsaturated acid monomer is an ethylenically unsaturated acid monomer having 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 ethylenic 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 styrenesulfonic acid; Ethylenically unsaturated polycarboxylic acid partial ester monomers such as monobutyl fumarate, monobutyl maleate, mono-2-hydroxypropyl maleate, and the like. Of these, methacrylic acid is particularly preferable. Such ethylenically unsaturated acid monomers can be used in the form of alkali metal salts or ammonium salts.

The ethylenic unsaturated acid monomer is contained in an amount of 0.1 to 10% by weight, preferably 0.5 to 9% by weight, more preferably 1 to 8% by weight, in 100% by weight of the total monomer constituting the carboxylic acid- modified nitrile- By weight. If the content is less than the above range, the tensile strength of the dip-formed article is lowered. On the other hand, if the content is in excess of the above-mentioned range, the deep-molded article becomes hard and the wearing feeling becomes poor.

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

Copolymerizable ethylenically unsaturated monomers include vinyl aromatic monomers selected from the group consisting of styrene, alkyl styrene, and vinyl naphthalene; Fluoroalkyl vinyl ethers such as fluoro ethyl vinyl ether; (Meth) acrylamide, N- methylol (meth) acrylamide, N, N - dimethylol (meth) acrylamide, N- methoxymethyl (meth) acrylamide, and N - propoxy, methyl (meth) acrylamide An ethylenically unsaturated amide monomer selected from the group consisting of: Nonconjugated diene monomers such as vinylpyridine, vinylnorbornene, dicyclopentadiene and 1,4-hexadiene; (Meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, trifluoroethyl (Meth) acrylate, dibutyl fumarate, diethyl maleate, methoxymethyl (meth) acrylate, ethoxyethyl (meth) acrylate, methoxyethoxyethyl (meth) acrylate, cyanomethyl Ethyl (meth) acrylate, 2-ethyl-6-cyanohexyl (meth) acrylate, 3-cyanopropyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxy Ethylenically unsaturated carboxylic acid ester monomer selected from the group consisting of glycidyl (meth) acrylate, glycidyl (meth) acrylate, and dimethylaminoethyl (meth) .

The amount of the ethylenically unsaturated nitrile monomer and the other ethylenic unsaturated monomer copolymerizable with the ethylenic unsaturated acid monomer is preferably from 0.001 to 20% by weight within 100% by weight of the total monomer constituting the carboxylic acid-modified nitrile-based copolymer Can be used. If the content exceeds 20% by weight, the balance between the soft feeling and the tensile strength does not fit well. Therefore, it is suitably used within the above range.

The carboxylic acid-modified nitrile-based copolymer latex of the present invention can be prepared by adding an emulsifier, a polymerization initiator, a molecular weight modifier, and the like to the monomers constituting the carboxylic acid-modified nitrile-based copolymer and emulsifying them.

The emulsifier is not particularly limited, and for example, an anionic surfactant, a nonionic surfactant, a cationic surfactant, a positive surfactant and the like can be used. Of these, anionic surfactants selected from the group consisting of alkylbenzenesulfonic acid salts, aliphatic sulfonic acid salts, sulfuric acid ester salts of higher alcohols,? -Olefin sulfonic acid salts, and alkyl ether sulfuric acid ester salts are particularly preferably used.

The amount of the emulsifier used is 0.3-10 parts by weight, preferably 0.8-8 parts by weight, more preferably 1.5-6 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-mentioned range, the stability at the time of polymerization is deteriorated. On the other hand, when the content exceeds the above range, foaming becomes more frequent and dip molded articles are difficult to produce.

The polymerization initiator is not particularly limited, but a radical initiator can be specifically used. Examples of the radical initiator include inorganic peroxides such as sodium persulfate, potassium persulfate, ammonium persulfate, potassium persulfate, and hydrogen peroxide; t-butyl peroxide, cumene hydroperoxide, p-menthol hydroperoxide, di-t-butyl peroxide, t-butyl cumyl peroxide, acetyl peroxide, isobutyl peroxide, octanoyl peroxide, dibenzoyl peroxide Organic peroxides such as oxides, 3,5,5-trimethylhexanol peroxide, t-butyl peroxyisobutyrate; At least one member selected from the group consisting of azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, azobiscyclohexanecarbonitrile, and azobisisobutyric acid (butyl acid) methyl, Inorganic peroxides are more preferable, and persulfates are particularly preferable.

The amount of the polymerization initiator to be used is 0.01 to 2 parts by weight, preferably 0.02 to 1.5 parts by weight, based on 100 parts by weight of the total monomers constituting the carboxylic acid-modified nitrile-based copolymer. If the content is less than the above range, the polymerization rate is lowered and the final product is difficult to produce. On the contrary, if the content exceeds the above range, the polymerization rate becomes too fast and the polymerization can not be controlled.

The activating agent may be selected from the group consisting of sodium formaldehyde sulfoxylate, sodium ethylenediaminetetraacetate, ferrous sulfate, dextrose, sodium pyrophosphate, and sodium sulfite.

Examples of the molecular weight regulator include, but are not limited to, mercaptans such as? -Methylstyrene dimer, t-dodecyl mercaptan, n-dodecyl mercaptan, and octyl mercaptan; Halogenated hydrocarbons such as carbon tetrachloride, methylene chloride, and methylene bromide; Containing sulfur compounds such as tetraethylthiuram disulfide, dipentamethylenethiuramdisulfide, diisopropylkisantigen disulfide, and the like.

These molecular weight modifiers can be used alone or in combination of two or more. Of these, mercaptans are preferable, and t-dodecyl mercaptan can be more preferably used. The amount of the molecular weight modifier to be used varies depending on the kind thereof, but is preferably from 0.1 to 2.0 parts by weight, preferably from 0.2 to 1.5 parts by weight, more preferably from 0.3 to 100 parts by weight, To 1.0 part by weight. If the content is less than the above range, the physical properties of the dip molded article are significantly lowered. On the other hand, if the content exceeds the above range, the polymerization stability is deteriorated.

In addition, it is of course possible to add a chelating agent, a dispersant, a pH adjuster, an oxygen scavenger, a particle size regulator, an anti-aging agent, and an oxygen scavenger in the polymerization of the latex of the present invention.

The method of introducing the monomer mixture constituting the carboxylic acid-modified nitrile-based copolymer is not particularly limited, and a method of charging the monomer mixture into the polymerization reactor at one time, a method of continuously introducing the monomer mixture into the polymerization reactor, A method in which the monomer is introduced into a polymerization reactor and the remaining monomer is continuously supplied to the polymerization reactor.

The polymerization temperature in the emulsion polymerization may be generally from 10 to 90 캜, preferably from 20 to 80 캜. More preferably 25 to 75 ° C, but is not particularly limited.

When the polymerization reaction is stopped, the conversion may be 90% or more, preferably 92 to 99.9%. After the polymerization reaction is stopped, unreacted monomers are removed, and the solid content concentration and the pH are controlled to adjust the carboxylic acid- Based copolymer latex can be obtained.

Such a carboxylic acid-modified nitrile-based copolymer latex has a glass transition temperature of -50 to -15 占 폚, preferably -45 to -20 占 폚. When the glass transition temperature of the latex is less than the above range, the tensile strength is remarkably lowered or the wearing feeling is deteriorated due to the stickiness of gloves. On the other hand, when the latex is higher than the above range, cracking of the dip- The content of the diene monomer can be adjusted and can be measured by Differential Scanning Calorimetry.

The average particle size of the latex for deep-forming may be 90 nm to 500 nm. Preferably from 100 nm to 200 nm, and more preferably from 110 nm to 180 nm. When the average particle diameter of the late molding latex falls within the above range, the tensile strength of the produced dip molded article can be improved.

The average particle size of the latex for deep-forming can be adjusted by adjusting the type and content of the emulsifier, and the average particle size can be measured by a laser scattering analyzer (Nicomp).

The solid concentration of the carboxylic acid-modified nitrile-based copolymer latex for dip-molding may be 10 to 30% by weight. If the amount is less than 10% by weight, the efficiency of transporting the latex may be deteriorated. If the amount is more than 30% by weight, the viscosity may increase, which may cause problems such as storage stability.

At this time, the glass transition temperature can be adjusted according to the content of the conjugated diene monomer, and the average particle diameter can be adjusted according to the type and content of the emulsifier.

Particularly, in the present invention, a specific crosslinking system is used for producing a dip-molded article of a carboxylic acid-modified nitrile-based copolymer latex.

The crosslinking system uses a polymer capable of crosslinking with a carboxylic acid-modified nitrile-based copolymer latex through hydrogen bonding. Preferably, a water-soluble polymer such as chitosan is used so as to be well mixed with the latex.

Specifically, the chitosan presented in the present invention is represented by the following Formula 1:

[Chemical Formula 1]

Chitosan represented by the structure of the above formula (1) is a condensation polymerized basic polysaccharide, which is a water-soluble polymer compound made from chitin as a raw material. Since it has a large number of polar groups, its hydration ability is high and it has a property of forming a film and has excellent properties of strength and flexibility . Since it has an amino group, it has positive ion in aqueous solution and it binds with anion and coagulates and is also used as coagulant. In addition, it has high affinity to the skin, so it is effective in preventing skin diseases.

The chitosan has OH and NH ₂ which are capable of hydrogen bonding within the molecular structure, and these are functional groups (for example, carboxylic acid (C (═O) OH) present in the carboxylic acid-modified nitrile-based copolymer latex copolymer) Oxygen (O) and hydrogen bonds (O ... H) are formed to show the crosslinking behavior. As a result, the stability of latex can be increased to increase the screening time in the deep molding step to improve the workability and productivity, and the tensile strength of the finally obtained molded article can be increased to secure an advantage of not being torn even when the thickness is thin.

The chitosan proposed in the present invention is one having a limited molecular weight in consideration of syneresis, workability, and physical properties of the final molded article. Preferably, the chitosan has a weight average molecular weight (MW) of 1,000 to 2,000 g / mol, but is not limited thereto.

The preparation of the latex composition for deep molding is carried out by mixing the carboxylic acid-modified nitrile-based copolymer latex with chitosan.

In this case, the carboxylic acid-modified nitrile-based copolymer latex is used in an amount of 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, more preferably 0.5 to 2 parts by weight, based on 100 parts by weight of solid matter of chitosan. If the content of the chitosan is less than the above range, the above-mentioned effect can not be ensured. On the other hand, if the content is above the above range, the stability of the latex composition for deep- Tensile strength, etc.) can not be ensured.

At this time, chitosan can be directly added to the carboxylic acid-modified nitrile-based copolymer latex, but is preferably mixed in an aqueous solution. Preferably, the chitosan is used in an aqueous solution of 0.5 to 15% by weight, more preferably 1 to 10% by weight, and most preferably 2 to 5% by weight, so that the syneresis in the deep molding process is gentle, The molded product has low stickiness and excellent tensile strength.

The latex composition for deep molding according to the present invention containing such a chitosan may further contain conventional additives used in a dip molding process.

As additives, additives such as a vulcanizing agent, a vulcanizing accelerator, an ionic crosslinking agent for dip molding, a metal oxide such as zinc oxide, a pigment such as titanium dioxide, a filler such as silica, a thickener, a pH adjusting agent such as ammonia or alkali hydroxide, The additives used are possible.

At this time, the content of the vulcanizing agent and the vulcanization accelerator as additives is minimized. Accordingly, it is possible to effectively reduce unpleasant odor due to sulfur and discoloration of the molded article, thereby further improving the product value of the dip molded article.

The solid concentration of the latex composition for dip molding according to the present invention containing the additive may be 10 to 40% by weight. Concentration of the solid content that is too low may lower the efficiency of transporting the latex, and an excessively high concentration of the solid content may cause an increase in viscosity, which may cause problems such as storage stability. Preferably 15 to 35% by weight, and more preferably 18 to 33% by weight.

The pH of the latex composition for deep-forming may be 8 to 12, preferably 9 to 11, more preferably 9.3 to 10.5. When the pH concentration is out of the above range, the stability of the latex composition for deep- have. At this time, the pH of the latex composition for deep-forming can be adjusted by adding a certain amount of a pH adjusting agent during the preparation of the latex for dip molding. As the pH adjusting agent, 1 to 5% aqueous solution of potassium hydroxide or 1 to 5% have.

Deep-formed product

The above-described latex composition for dip molding is capable of producing a dip product through a dip molding process. In particular, the latex composition for dip molding according to the present invention has a uniform thickness and excellent physical properties even when a molded article is manufactured to a thickness of tens to hundreds of microns.

For example, when a glove is manufactured using the latex composition for dip molding of the present invention, a high level of tensile strength is secured in a thin glove of 3.2 g, which is advantageous in that it is not torn easily. In addition, the syneresis is smooth and the workability is improved, and when the work is performed at the low concentration, the problem of the workability due to the short syneresis and the high defect rate in the manufacture of the product are solved.

In addition, the manufactured dip-shaped article has a soft touch, an excellent wearing feeling, an antibacterial effect, and suppresses or reduces the odor and discoloration of the molded article due to the exclusion of sulfur.

As a dip molding method for obtaining the dip-shaped article of the present invention, a usual method can be used, and examples thereof include a direct dipping method, an anode adhesion dipping method, and a Teague adhesion dipping method. Of these, the positive electrode deposition dipping method is preferable because a dip-shaped article having a uniform thickness can be easily obtained.

A method of producing a dip-molded article using the composition of the present invention

(a) coating a coagulant solution on the mold surface;

(b) coating a coagulant-coated mold with a latex composition for dip molding to form a dip-formed layer;

(c) crosslinking the dip molding layer; And

(d) peeling the cross-linked dip-formed layer from the mold to obtain a dipped molded article.

Hereinafter, a method for producing a dip-molded article using the latex composition of the present invention will be described in detail.

(a) Mold  Coating the surface with a coagulant

In this step (a), a hand shaped dip forming mold is used as a mold, the mold is coated on the coagulant solution and dried, and a step of applying a coagulant to the surface of the mold is performed.

Coagulants include metal halides such as barium chloride, calcium chloride, magnesium chloride, zinc chloride and aluminum chloride, and the like; Nitrates such as barium nitrate, calcium nitrate and zinc nitrate; Acetic acid salts such as barium acetate, calcium acetate and zinc acetate; Calcium sulfate, magnesium sulfate, and sulfate such as aluminum sulfate. Of these, calcium chloride and calcium nitrate are preferred. The coagulant solution is a solution in which the above coagulant is dissolved in water, alcohol or a mixture thereof. The concentration of the coagulant in the coagulant solution is usually from 5 to 50% by weight, preferably from 10 to 40% by weight.

(b) Mold  Deep within The shaping layer  Forming step

In the step (b), following the step (a), the step of immersing the mold with the coagulant into the latex composition for deep-forming of the present invention to form a dip-formed layer is performed.

The mold with the coagulant is immersed in the latex composition for late molding made from the latex resin composition of the present invention, and then the mold is taken out to form a dip molding layer in the mold.

(c) Dip The shaping layer Bridged  step

Next, in this step (c), the step of crosslinking the latex resin by heat-treating the dip molding layer formed on the mold is performed.

The crosslinking is carried out through a heat treatment, in which the water component first evaporates and is cured by crosslinking.

(d) measuring the yield and physical properties of the dip-molded article

Subsequently, in this step (d), a dip-molded article is obtained from the mold, and the physical properties of the obtained dip-molded article are measured.

A dumbbell-shaped specimen was produced from the obtained dip-molded article in accordance with ASTM D-412. Subsequently, the test piece is pulled at a stretching speed of 500 mm / min using a universal testing machine (UTM), the tensile strength and elongation at break are measured, and the touch is measured by the stress when the elongation is 300% and 500%.

The process according to the invention can also be used for any latex article which can be produced by known dip molding methods. Specifically, it can be applied to deep-formed latex articles selected from health care products such as surgical gloves, test gloves, condoms, catheters or various kinds of industrial and household gloves.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope and spirit of the invention as disclosed in the accompanying claims. Changes and modifications may fall within the scope of the appended claims.

[Example]

Example  1: Production of latex composition for dip molding and dip molding

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

A 10 L high-pressure reactor equipped with a stirrer, a thermometer, a condenser, an inlet of nitrogen gas, and a monomer, emulsifier and polymerization initiator was continuously replaced with nitrogen. To 100 parts by weight of a monomer mixture comprising 25% by weight of acrylonitrile, 70% by weight of 1,4-butadiene and 5% by weight of methacrylic acid, 2.5 parts by weight of sodium alkylbenzenesulfonate, 0.5 parts by weight of t- And 140 parts by weight of ion-exchanged water were charged and the temperature was raised to 40 캜.

After the temperature was elevated, 0.25 parts by weight of potassium persulfate as a polymerization initiator was added. When the conversion was 95%, 0.1 part by weight of sodium dimethyldithiocarbamate was added to terminate the polymerization.

Then, unreacted monomers were removed through a deodorization process, and ammonia water, an antioxidant, a defoaming agent and the like were added to obtain a carboxylated acrylonitrile-butadiene copolymer latex having a solid concentration of 45% and a pH of 8.5.

The average particle size and glass transition temperature of the prepared latex were measured. The average particle size was measured with a Laser Scattering Analyzer (Nicomp), and the glass transition temperature was measured with Differential Scanning Calorimetry.

As a result of the analysis, the glass transition temperature of the prepared latex was -40 ° C and the average particle size was 130 nm. The latex prepared above is referred to as 'latex-A'.

(Production of latex composition for deep molding)

Next, chitosan having a weight-average molecular weight of 2000 g / mol, diluted to 5% with 100 parts by weight of the latex-A, 0.5 part by weight to prepare a mixture. A 3% potassium hydroxide solution and an appropriate amount of secondary distilled water were added together with 0.5 part by weight of sulfur (BOSTEX 378, Akron dispersions) and 0.2 part by weight of a vulcanization accelerator (BOSTEX 497B) to prepare a latex for deep- A composition was obtained.

(Production of Dip molded article)

12 parts by weight of calcium nitrate, 87.5 parts by weight of distilled water and 0.5 part by weight of a wetting agent (Teric 320 produced by Huntsman Corporation, Australia) were mixed to prepare a coagulant solution. A hand-shaped ceramic mold was immersed in this solution for 1 minute, pulled out, dried at 80 ° C for 3 minutes, and the coagulant was applied to the hand mold.

Next, the mold to which the coagulant was applied was immersed in the latex composition for deep molding for 1 minute, pulled up, dried at 80 DEG C for 1 minute, and then immersed in hot water for 3 minutes.

The mold was again dried at 80 DEG C for 3 minutes and then crosslinked at 120 DEG C for 20 minutes. The crosslinked dip molding layer was peeled off from the hand mold to obtain a glove-shaped dip molded article.

Example  2: Production of latex composition for dip molding and dip molding

The solid content of chitosan 1.0 part by weight was used in place of the above-mentioned prepolymer.

Example  3: Production of latex composition for dip molding and dip molding

The solid content of chitosan Except that 2.0 parts by weight of polyvinyl alcohol was used as a solvent.

Comparative Example  1: Production of latex composition for dip molding and dip molding

In the same manner as in Example 1 except that latex-A was used alone in Example 1, a glove-shaped deep-molded product was prepared

Experimental Example  1: Measurement of physical properties of dip-molded parts

The physical properties of the dip-molded articles produced in the above Examples and Comparative Examples were measured, and the results are shown in Table 1 below.

(1) Measurement of synergy (sec)

In order to confirm the screening time, a mold coated with a coagulant was immersed in the latex composition for deep molding for 1 minute, dried, and dried at 120 ° C for 4 minutes.

(2) Measurement of tensile strength

A cross head speed was pulled at 500 mm / min using a test instrument U.TM (manufactured by Instron, model name: 4466) according to the ASTM D638 method, and the point at which the specimen was cut was measured. The tensile strength was calculated as follows:

[Equation 1]

(3) Stress at 300% (MPa) and Stress at 500% (MPa)

After pulling the cross head speed at 500 mm / min using a UTM (Instron, model name: 4466, manufactured by the manufacturer) according to the ASTM D638 method, the stress at 300% and the stress at 500% Were measured as follows:

Stress at 300% (MPa) = tensile strength (1 MPa = 0.10197 kgf / mm 2) when stretched to three times the original length of the specimen.

Stress at 500% (MPa) = tensile strength (1 MPa = 0.10197 kgf / mm 2) when stretched at 5 times the original length of the specimen.

(4) Measurement of elongation rate

After pulling the crosshead speed at 500 mm / min using the U.TM according to the ASTM D638 method, the point at which the specimen was cut was measured and the elongation was calculated as follows:

&Quot; (2) "

Scenicism
(sec) The tensile strength
(MPa) Stress at 300% elongation (Mpa) Stress at 500% elongation (Mpa) Elongation (%) Example 1 148 32.0 5.6 16.2 579 Example 2 166 32.3 5.2 15.3 623 Example 3 220 33.0 5.0 14.6 610 Comparative Example 1 146 31.7 5.7 16.5 546

As shown in Table 1, the dip-molded articles of Examples 1 to 3 using the carboxylic acid-modified nitrile latex according to the present invention and chitosan as a water-soluble polymer capable of crosslinking were compared with the dip-molded articles prepared in Comparative Example 1 It was confirmed that the syneresis was smooth and the tensile strength was excellent.

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

Claims (12)

A carboxylic acid-modified nitrile-based copolymer latex, and chitosan. The method according to claim 1,
Wherein the carboxylic acid-modified nitrile-based copolymer latex has a glass transition temperature of -50 to -15 占 폚 and an average particle size of 90 to 500 nm. The method according to claim 1,
Wherein the chitosan has a weight average molecular weight of 1,000 to 2,000 g / mol. The method according to claim 1,
Wherein the latex composition for deep-forming comprises 0.1 to 10 parts by weight of chitosan relative to 100 parts by weight of the carboxylic acid-modified nitrile-based copolymer latex. The method according to claim 1,
Wherein the chitosan is mixed with an aqueous solution having a concentration of 0.5 to 15% by weight. The method according to claim 1,
The carboxylic acid-modified nitrile-based copolymer is characterized in that a monomer mixture comprising 40 to 89% by weight of a conjugated diene monomer, 10 to 50% by weight of an ethylenically unsaturated nitrile monomer and 0.1 to 10% by weight of an ethylenically unsaturated acid monomer By weight based on the total weight of the latex composition. The method according to claim 6,
Wherein the conjugated diene monomer is at least one member selected from the group consisting of 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 1,3-pentadiene, isoprene, Wherein the latex composition further comprises at least one member selected from the group consisting of polyvinylpyrrolidone and polyvinylpyrrolidone. The method according to claim 6,
The ethylenically unsaturated nitrile-based monomer is preferably one selected from the group consisting of acrylonitrile, methacrylonitrile, fumaronitrile,? -Chloronitrile,? -Cyanoethyl acrylonitrile, and combinations thereof By weight based on the total weight of the latex composition. The method according to claim 6,
Wherein said ethylenically unsaturated acid monomer is selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, maleic anhydride, citraconic anhydride, styrenesulfonic acid, monobutyl fumarate, monobutyl maleate, mono-2- And a combination thereof. ≪ RTI ID = 0.0 > 21. < / RTI > The method according to claim 1,
Wherein the composition further comprises one additive selected from the group consisting of a vulcanizing agent, a vulcanization catalyst, a filler, a crosslinking agent, a pigment, a thickener, a pH adjusting agent and a combination thereof. 10. A dip-formed article produced by dip-molding a latex composition for dip molding according to any one of claims 1 to 10. a) applying a coagulant solution to the mold and drying; b) applying a latex composition for dip molding to a mold to which the coagulant is applied to form a dip molding layer; c) crosslinking said dip molding layer; And d) peeling the cross-linked dip-formed layer from the mold to obtain a dip-molded article,
Wherein the latex composition for dip molding is a latex composition for dip molding according to any one of claims 1 to 10.