KR20220058184A - A latex composition with a good storage stability for dip-forming, a method for preparing thereof, and a dip-formed article prepared therefrom - Google Patents

Abstract

Disclosed are a latex composition for dip molding including a carboxylic acid-modified nitrile-based copolymer latex, a polyvinylpyrrolidone-based resin, a negative ionic dispersant, and a filler, a method for preparing the same, and a dip molded article prepared therefrom. According to the present invention, the productivity of dip molded articles can be improved by preventing reduction in the chemical stability of the latex composition.

Description

Latex composition for dip molding with excellent storage stability, manufacturing method thereof, and deep molded article manufactured therefrom

It relates to a latex composition for dip molding, a method for manufacturing the same, and a dip molded article prepared therefrom.

The main raw material of gloves used for conventional medical, agricultural and livestock processing, and industrial use was natural rubber latex. However, when gloves made from natural rubber latex are used, the problem that the glove user suffers from a contact allergic disease has frequently occurred due to the protein contained in the natural rubber latex.

Accordingly, attempts have been made to manufacture raw materials for gloves that can replace natural rubber latex. For example, attempts have been made to manufacture gloves by applying a synthetic rubber latex that does not contain a protein, such as a nitrile-based copolymer latex. As compared to natural rubber latex gloves, nitrile-based copolymer latex gloves have a higher puncture strength, and thus demand is increasing in the medical and food fields where contact with sharp objects frequently occurs. However, there are clearly limitations in the puncture strength, tensile strength, elongation, etc. implemented in the nitrile-based copolymer latex gloves to date.

On the other hand, Korean Patent Publication No. 10-1964278 discloses an invention with the name of "a latex composition for dip molding and a dip molded article prepared therefrom". The latex composition for dip molding includes an alkenyl succinic acid-based emulsifier, and the dip molded article prepared therefrom has improved tensile strength.

Laid-Open Patent Publication No. 10-2017-0081839 discloses an invention with the name of "a latex composition for dip molding and a molded article prepared therefrom". The latex composition for dip molding includes an emulsifier composed of a triblock copolymer, and the dip molded article prepared therefrom has improved tensile strength or elongation.

Laid-Open Patent Publication No. 10-2018-0051147 discloses an invention with the name of "a latex composition for dip molding and a molded article prepared therefrom". The latex composition for dip molding includes polyethylene glycol, and the dip molded article prepared therefrom has improved tensile strength or elongation.

Although the above inventions improve the physical properties of a dip molded article by adding a special emulsifier or using a modified monomer, there is a limit in that mechanical properties cannot be improved in a balanced way.

And, in the manufacturing process of the nitrile-based copolymer glove, in the dip molding process, the nitrile-based copolymer latex is a halide-based calcium chloride (CaCl ₂ ), magnesium chloride (MgCl ₂ ) ), barium chloride (barium chloride, BaCl ₂ ), or nitrate-based calcium nitrate (calcium nitrate, Ca(NO ₃ ) ₂ ), magnesium nitrate (magnesium nitrate, Mg(NO ₃ ) ₂ ), etc. There is a problem in that the chemical stability of the latex is sharply deteriorated as it is exposed to a cationic coagulant for a long time. This reduces the productivity as well as mechanical properties of the nitrile-based copolymer glove. In addition, if the particulate additive added after polymerization is not introduced with a high degree of dispersibility, there is a problem in that the quality of physical properties of the manufactured glove deteriorates due to the deterioration of the storage stability of the latex over time.

Description of the present specification is to solve the problems of the prior art described above, one purpose is to prevent the chemical stability of the nitrile-based latex composition for dip molding from being lowered to improve the productivity of the dip molded article, and the nitrile for dip molding To provide a dip molded article having excellent mechanical properties such as tensile strength and elongation when a dip molded article is manufactured using the latex-based composition.

Another object is to improve the dispersion stability of the latex due to the particulate additive to significantly reduce the film formation in the latex reservoir to improve the performance and quality of the final product.

According to one aspect, there is provided a latex composition for dip molding comprising a carboxylic acid-modified nitrile-based copolymer latex, a polyvinylpyrrolidone-based resin, an anionic dispersant and a filler.

In one embodiment, the carboxylic acid-modified nitrile-based copolymer latex, based on the total weight of the carboxylic acid-modified nitrile-based copolymer latex, 45 to 80% by weight of a conjugated diene-based monomer; 15 to 45% by weight of an ethylenically unsaturated nitrile monomer; and 1 to 10% by weight of an ethylenically unsaturated acid monomer.

In one embodiment, the conjugated diene-based monomer is 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 1,3-pentadiene, isoprene, and these It may be one selected from the group consisting of a combination of two or more of them.

In one embodiment, the ethylenically unsaturated nitrile monomer is selected from the group consisting of acrylonitrile, methacrylonitrile, humaronitrile, α-chloronitrile, α-cyano ethyl acrylonitrile, and combinations of two or more thereof. can be one

In one embodiment, the ethylenically unsaturated acid monomer is acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, maleic anhydride, citraconic acid anhydride, styrene sulfonic acid, monobutyl fumarate, monobutyl maleate, mono-2 maleic acid It may be one selected from the group consisting of -hydroxy propyl and a combination of two or more thereof.

In one embodiment, the content of the polyvinylpyrrolidone-based resin may be 0.1 to 3 parts by weight based on 100 parts by weight of the carboxylic acid-modified nitrile-based copolymer latex.

In one embodiment, the polyvinylpyrrolidone-based resin comprises one monomer selected from the group consisting of vinyl acetate, vinyl propionate, vinyl butyrate, vinyl methoxyacetate, vinyl benzoate, and combinations of two or more thereof. It may contain 20 to 80% by weight based on the total weight of the polyvinylpyrrolidone-based resin.

In one embodiment, the polyvinylpyrrolidone-based resin may have a weight average molecular weight of 5,000 to 50,000 g/mol.

In one embodiment, the content of the anionic dispersant may be 0.1 to 1 part by weight based on 100 parts by weight of the carboxylic acid-modified nitrile-based copolymer latex.

In one embodiment, the anionic dispersant is one selected from the group consisting of sodium laureth sulfate, ammonium laureth sulfate, sodium laureth sulfonate, sodium lauryl sulfate, ammonium lauryl sulfate, and combinations of two or more thereof. can be

In one embodiment, the content of the filler may be 0.1 to 5 parts by weight based on 100 parts by weight of the carboxylic acid-modified nitrile-based copolymer latex.

In one embodiment, the average particle diameter of the filler may be 10-200 nm.

In one embodiment, the filler may be one selected from the group consisting of silica, fumed silica, precipitated silica, silica sol, and a combination of two or more thereof.

In one embodiment, the latex composition for dip molding may further include one selected from the group consisting of a pigment, a vulcanizing agent, a vulcanization accelerator, a crosslinking agent, and a combination of two or more thereof.

In one embodiment, the carboxylic acid-modified nitrile-based copolymer latex is selected from the group consisting of an emulsifier, a polymerization initiator and a molecular weight regulator, a polymerization terminator, a pH regulator, an antioxidant, an oxygen scavenger, and a combination of two or more thereof. may include more.

According to another aspect, (a) emulsion polymerization of a mixture of a conjugated diene-based monomer, an ethylenically unsaturated nitrile-based monomer and an ethylenically unsaturated acid monomer to obtain a carboxylic acid-modified nitrile-based copolymer latex; And (b) mixing the polyvinylpyrrolidone-based resin aqueous solution, anionic dispersant and filler aqueous solution with the product of step (a); comprising, a method for producing a latex composition for dip molding is provided.

According to another aspect, a dip molded article obtained by dip molding the above-described latex composition for dip molding is provided.

In one embodiment, the dip molded article may be one selected from the group consisting of medical gloves, agricultural and livestock processing gloves, industrial gloves.

According to one aspect, the chemical stability of the nitrile-based latex composition for dip molding is prevented from lowering to improve the productivity of the dip-molded article, and when a dip-molded article is manufactured using the nitrile-based latex composition for dip molding, excellent tensile strength , and mechanical properties such as elongation can be implemented.

According to another aspect, it is possible to significantly reduce the phenomenon of film formation in the latex storage tank by improving the storage stability of the latex due to the particulate additive, thereby improving the performance and quality of the dip molded product.

The effect of one aspect of the present specification is not limited to the above-described effect, but it should be understood to include all effects that can be inferred from the configuration described in the detailed description or claims of the present specification.

The description of the present specification may be embodied in several different forms, and thus is not limited to the embodiments described herein.

Throughout the specification, when a part is "connected" with another part, this includes not only the case where it is "directly connected" but also the case where it is "indirectly connected" with another member interposed therebetween. . In addition, when a part "includes" a certain component, this means that other components may be further provided without excluding other components unless otherwise stated.

When a range of numerical values is recited herein, the values have the precision of the significant figures provided in accordance with the standard rules in chemistry for significant figures, unless the specific range is otherwise stated. For example, 10 includes the range of 5.0 to 14.9 and the number 10.0 includes the range of 9.50 to 10.49.

As used herein, the term “primary particle” refers to one-dimensional or more particles having an average particle size of 1 to 100 nm. In this regard, "secondary particle" means a particle formed by agglomeration of the primary particle. In this case, the secondary particles may be formed by physical or chemical bonds such as van der Waals bonds and covalent bonds.

Latex composition for dip molding

The latex composition for dip molding according to one aspect may include a carboxylic acid-modified nitrile-based copolymer latex, a polyvinylpyrrolidone-based resin, an anionic dispersant, and a filler.

The carboxylic acid-modified nitrile-based copolymer latex is, based on the total weight of the carboxylic acid-modified nitrile-based copolymer latex, 45 to 80% by weight of a conjugated diene-based monomer; 15 to 45% by weight of an ethylenically unsaturated nitrile monomer; and 1 to 10% by weight of an ethylenically unsaturated acid monomer.

As a non-limiting example of the present specification, the content of the conjugated diene-based monomer is 45% by weight or more, 50% by weight or more, or 55% by weight or more, based on the total weight of the carboxylic acid-modified nitrile-based copolymer latex, 80 weight percent or less, 75 weight percent or less, or 70 weight percent or less. If the content of the conjugated diene-based monomer is less than 45% by weight, the deep-molded article is excessively hardened, and the user of the dip-molded article can reduce the wearing feeling. This may be lowered and the tensile strength may be lowered.

As a non-limiting example of the present specification, the content of the ethylenically unsaturated nitrile monomer is 15% by weight or more, 20% by weight or more, or 25% by weight or more, based on the total weight of the carboxylic acid-modified nitrile-based copolymer latex, 45 wt% or less, 40 wt% or less, or 35 wt% or less. If the content of the ethylenically unsaturated nitrile monomer is less than 15% by weight, the oil resistance of the dip molded article may be lowered and the tensile strength may be lowered. If the content of the ethylenically unsaturated nitrile monomer exceeds 45% by weight, the dip molded article may be excessively hardened, and thus the user of the dip molded article may reduce the wearing comfort.

As a non-limiting example of the present specification, the content of the ethylenically unsaturated acid monomer is 1% by weight or more, 2% by weight or more, or 3% by weight or more, based on the total weight of the carboxylic acid-modified nitrile-based copolymer latex, 10 wt% or less, 9 wt% or less, or 8 wt% or less. If the content of the ethylenically unsaturated acid monomer is less than 1% by weight, the tensile strength of the dip molding may decrease. If the content of the ethylenically unsaturated nitrile monomer exceeds 10% by weight, the dip molded article may be excessively hardened, and thus the user of the dip molded article may reduce the wearing comfort.

As a non-limiting example of the present specification, the carboxylic acid-modified nitrile-based copolymer latex may be a copolymer represented by Formula 1 below.

[Formula 1]

Formula 1 represents a general example of a conjugated diene-based monomer unit, an ethylenically unsaturated nitrile monomer unit, and an ethylenically unsaturated acid monomer unit, which are three structural units of the carboxylic acid-modified nitrile-based copolymer latex, and the copolymer is It is not limited. In addition, Formula 1 shows each unit in order for convenience, and the copolymer is randomly distributed by mixing each unit irrespective of the order of Formula 1, or at least some of them are block units according to the user's needs. may be distributed.

The ratios of a, b and c may be adjusted according to the ratio of each monomer unit constituting the copolymer.

The conjugated diene-based monomer is 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 1,3-pentadiene, isoprene, and a combination of two or more thereof. It may be one selected from the group, for example, may be 1,3-butadiene (buta-1,3-diene), but is not limited thereto.

The ethylenically unsaturated nitrile monomer may be one selected from the group consisting of acrylonitrile, methacrylonitrile, humaronitrile, α-chloronitrile, α-cyano ethyl acrylonitrile, and combinations of two or more thereof, For example, it may be acrylonitrile (prop-2-enenitrile), but is not limited thereto.

The ethylenically unsaturated acid monomer is acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, maleic anhydride, citraconic acid anhydride, styrene sulfonic acid, monobutyl fumarate, monobutyl maleate, mono-2-hydroxypropyl maleate and these It may be one selected from the group consisting of a combination of two or more of, for example, methacrylic acid (2-methylprop-2-enoic acid), but is not limited thereto.

The content of the polyvinylpyrrolidone-based resin may be 0.1 to 3 parts by weight based on 100 parts by weight of the carboxylic acid-modified nitrile-based copolymer latex. At this time, the content of the polyvinylpyrrolidone-based resin is 0.1 parts by weight or more, 0.2 parts by weight or more, 0.3 parts by weight or more, 0.4 parts by weight or more, or 0.5 parts by weight based on 100 parts by weight of the carboxylic acid-modified nitrile-based copolymer latex. part or more, and may be 3 parts by weight or less, 2.8 parts by weight or less, or 2.6 parts by weight or less.

The polyvinylpyrrolidone-based resin is a polyvinylpyrrolidone-based resin comprising one monomer selected from the group consisting of vinyl acetate, vinyl propionate, vinyl butyrate, vinyl methoxyacetate, vinyl benzoate, and combinations of two or more thereof. It may contain 20 to 80% by weight based on the total weight, for example, may be vinyl acetate, but is not limited thereto. Polyvinylpyrrolidone-based resin has excellent compatibility with carboxylic acid-modified nitrile-based copolymer latex, and exhibits acid resistance to improve chemical stability of latex particles as well as excellent dispersibility with nano-particle oxides, resulting in chemical stability of latex particles Along with the improvement, mechanical properties such as tensile strength of dip-molded products can be improved at the same time.

As a non-limiting example of the present specification, the content of the first monomer is 20% by weight or more, 30% by weight or more, 40% by weight or more, 80% by weight or less, based on the total weight of the polyvinylpyrrolidone-based resin; 70% by weight or less, or 60% by weight or less.

The polyvinylpyrrolidone-based resin may have a weight average molecular weight of 5,000 to 50,000 g/mol. The weight average molecular weight of the polyvinylpyrrolidone-based resin is 5,000 g/mol or more, 6,000 g/mol or more, or 7,000 g/mol or more, and 50,000 g/mol or less, 49,000 g/mol or less, or 48,000 g/mol or less. can

As a non-limiting example of the present specification, the polyvinylpyrrolidone-based resin may be a block copolymer represented by Formula 2 below.

[Formula 2]

In Formula 2, the ratio of m:n may be 1:1 to 1.5.

When the polyvinylpyrrolidone-based resin and the anionic dispersant are included in the latex composition for dip molding, it is possible to improve the problem of long-term storage stability degradation due to the particulate additive.

The anionic dispersant has excellent compatibility with carboxylic acid-modified nitrile-based copolymer latex, can improve chemical stability of latex particles, and has dispersion compatibility with fillers, for example, nanoparticle oxides such as silica Because it is excellent, long-term storage stability of latex for dip molding can be improved, and mechanical properties such as tensile strength of dip molded products can be improved.

The content of the anionic dispersant may be 0.1 to 1 part by weight based on 100 parts by weight of the carboxylic acid-modified nitrile-based copolymer latex. At this time, the content of the anionic dispersant is 0.1 parts by weight or more, 0.15 parts by weight or more, or 0.2 parts by weight or more, 1 part by weight or less, 0.9 parts by weight or less with respect to 100 parts by weight of the carboxylic acid-modified nitrile-based copolymer latex , or 0.8 parts by weight or less.

The anionic dispersant may be one selected from the group consisting of sodium laureth sulfate, ammonium laureth sulfate, sodium laureth sulfonate, sodium lauryl sulfate, ammonium lauryl sulfate, and combinations of two or more thereof.

As a non-limiting example of the present specification, the anionic dispersant may be a polymer compound represented by Formula 3 below.

[Formula 3]

In Chemical Formula 3, the ratio of n: m may be 1-5: 1-50, respectively.

The polymer compound of Formula 3 according to an example may have a structure including alpha sulfo-megadodecyl oxy polyosyl ethane and sodium salt. The compound is composed of polyosylethane and a hydrophobic alkyl chain, but the anionic dispersant of the present specification is not limited thereto.

The content of the filler may be 0.1 to 5 parts by weight based on 100 parts by weight of the carboxylic acid-modified nitrile-based copolymer latex. At this time, the content of the filler is 0.1 parts by weight or more, 0.3 parts by weight or more, or 0.5 parts by weight or more, 5 parts by weight or less, 4.8 parts by weight or less, or It may be 4.6 parts by weight or less.

The average particle diameter of the filler may be 10-200 nm. Such filler particles may include primary particles to secondary particles. At this time, the average particle diameter of the filler may be 10 nm or more, 15 nm or more, or 20 nm or more, and may be 200 nm or less, 195 nm or less, or 190 nm or less. The average particle diameter of the filler may mean the particle diameter of the primary particles, but is not limited thereto.

The filler may be one selected from the group consisting of silica, fumed silica, precipitated silica, silica sol, and a combination of two or more thereof, for example, fumed silica, but is not limited thereto.

When the latex composition contains particulate additives such as the filler, long-term storage stability may be lowered and a film may be formed during long-term storage of the composition, but like the latex composition for dip molding, polyvinylpyrrolidone-based resin and anions When the system dispersant is included at the same time, storage stability can be significantly improved.

The latex composition for dip molding may further include one selected from the group consisting of a pigment such as titanium dioxide, a vulcanizing agent, a vulcanization accelerator, a crosslinking agent such as zinc oxide, and combinations of two or more thereof.

As a non-limiting example of the present specification, the vulcanizing agent may include sulfur such as powdered sulfur, precipitated sulfur, colloidal sulfur, surface treated sulfur, insoluble sulfur. Such a vulcanizing agent crosslinks between polymer chains by attacking the pi bonds in the conjugated double bond of butadiene, thereby imparting elasticity to the copolymer as well as improving the chemical resistance of the dip molded product.

As a non-limiting example of the present specification, the vulcanization accelerator is 2-mercaptobenzothiazole, 2,2-dithiobisbenzothioazole-2-sulfenamide, N-cyclohexylbenzothiazole-2-sulfenamide, 2-morpholinothiobenzothiazole, tetramethylthiuram monosulfide, tetramethylthiuram disulfide, zinc diethyldithiocarbamate, zinc dibutyldithiocarbamate, diphenylguanidine, di-o-tolyl It may be one selected from guanidine and a combination of two or more thereof, for example, zinc dibutylthiocarbamate (ZDBC), but is not limited thereto.

The carboxylic acid-modified nitrile-based copolymer latex may further include one selected from the group consisting of an emulsifier, a polymerization initiator and a molecular weight control agent, a polymerization terminator, a pH control agent, an antioxidant, an oxygen scavenger, and a combination of two or more thereof.

As a non-limiting example of the present specification, the emulsifier may be one of anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants, for example, an anionic surfactant alkylbenzene sulfonate. , aliphatic sulfonates, sulfate ester salts of higher alcohols, α-olefin sulfonates, and alkyl ether sulfate ester salts, for example, sodium alkylbenzene sulfonate, but is not limited thereto. it is not These emulsifiers may be used in an amount of 0.8 to 8 parts by weight based on 100 parts by weight of the monomer mixture.

As a non-limiting example of the present specification, the polymerization initiator is an inorganic peroxide selected from the group consisting of sodium persulfate, potassium persulfate, ammonium persulfate, potassium perphosphate, and hydrogen peroxide; t-butyl peroxide, cumene hydroperoxide, p-tanhydroperoxide, di-t-butyl peroxide, t-butylcumyl peroxide, acetyl peroxide, isobutyl peroxide, octanoyl peroxide, dibenzoyl peroxide an organic peroxide selected from the group consisting of oxide, 3,5,5-trimethylhexanol peroxide, and t-butylperoxy isobutylate; azobis isobutyronitrile, azobis-2,4-dimethyl valeronitrile, azobiscyclohexanecarbonitrile, and azobisisobutyronitrile (butyric acid)methyl, for example, potassium persulfate (potassium persulfate) persulfate), but is not limited thereto. These polymerization initiators may be used in an amount of 0.02 to 1.5 parts by weight based on 100 parts by weight of the monomer mixture.

As a non-limiting example of the present specification, the molecular weight modifier may include 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; sulfur-containing compounds such as tetraethyl thiuram disulfide, dipentamethylene thiuram disulfide, and diisopropyl xanthogen disulfide; It may be one of, for example, t-dodecyl mercaptan (t-dodecyl mercaptan), but may be, but is not limited thereto. 0.2 to 0.7 parts by weight of the molecular weight regulator may be used based on 100 parts by weight of the monomer mixture.

In one non-limiting example of the present specification, the polymerization terminator is hydroxylamine, hydroxylamine sulfate, diethylhydroxyamine, hydroxylamine sulfonic acid and alkali metal ions thereof, sodium dimethyldithiocarbamate, hydroquinone derivatives , hydroxy diethyl benzene dithio carboxylic acid, hydroxy dibutyl benzene dithio carboxylic acid, may be one of aromatic hydroxy dithio carboxylic acid such as dithio carboxylic acid, for example, sodium dimethyl dithio carbamate (sodium dimethyl dithiocarbamate) However, the present invention is not limited thereto.

As a non-limiting example of the present specification, it may be preferable to adjust the hydrogen ion concentration index of the latex composition for dip molding to pH 9-11 by adding the pH adjusting agent. As such a pH adjusting agent, 1 to 5% by weight of potassium hydroxide aqueous solution or 1 to 5% by weight of aqueous ammonia may be used. At this time, the solid content of the pH adjusting agent may be 40 to 50% by weight, for example, 40% by weight or more, 42% by weight or more, or 44% by weight or more, 50% by weight or less, 48% by weight or less, or 46% by weight or less.

Method for producing latex composition for dip molding

The method for producing a latex composition for dip molding according to another aspect includes (a) emulsion polymerization of a mixture of a conjugated diene-based monomer, an ethylenically unsaturated nitrile-based monomer and an ethylenically unsaturated acid monomer to obtain a carboxylic acid-modified nitrile-based copolymer latex obtaining; and (b) mixing the polyvinylpyrrolidone-based resin aqueous solution, anionic dispersant and filler aqueous solution with the product of step (a).

As a non-limiting example of the present specification, the polyvinylpyrrolidone-based resin may be prepared by spray drying. In addition, when only the polyvinylidene-based resin is added and the aqueous filler solution is not added, the tensile strength of the dip-molded product may be deteriorated.

As a non-limiting example of the present specification, the filler aqueous solution may have a filler content of 3 to 40% by weight based on the total weight of the aqueous solution. At this time, the content of the filler may be 3% by weight or more, 40% by weight or less, 35% by weight or less, or 30% by weight or less. In addition, the aqueous filler solution may include a silica sol in which the content of silica is 10 to 50% by weight based on the total weight of the silica sol. In this case, the content of silica may be 10 wt% or more, 15 wt% or more, or 20 wt% or more, and may be 50 wt% or less, 45 wt% or less, or 40 wt% or less.

As a non-limiting example of the present specification, the mixing reaction of step (b) may be performed at 25 to 75° C., and it may be preferable to stop the polymerization reaction when the conversion rate of the reactants is 93% or more.

As a non-limiting example of the present specification, the solids concentration of the polyvinylpyrrolidone-based resin aqueous solution added in step (b) may be 10 to 40% by weight based on the total weight of the aqueous solution. In this case, the solid content concentration of the polyvinylpyrrolidone-based resin may be 10% by weight or more, 15% by weight or more, or 20% by weight or more, and 40% by weight or less, 35% by weight or less, or 30% by weight or less.

As a non-limiting example of the present specification, the anionic dispersant introduced in step (b) may be added as a solution having a concentration of 20 to 40% by weight. The concentration may be, for example, 20% by weight or more, 25% by weight or more, or 30% by weight or more, 40% by weight or less, or 37.5% by weight or less.

The anionic dispersant may interact with the polyvinylpyrrolidone-based resin to improve dispersibility of the filler and improve stability over time.

In the method for producing the latex composition for dip molding, each component may be calculated and added to suit the content of the latex composition for dip molding described above based on the solid content.

dip molding

A dip-molded article according to another aspect may be obtained by dip-molding the aforementioned latex composition for dip-molding.

The dip-molded article may be prepared from a latex composition for dip molding including a polyvinylpyrrolidone-based resin and an anionic dispersant at the same time, and thus may have excellent mechanical properties such as tensile strength.

The dip molded article may be one selected from the group consisting of medical gloves, agricultural and livestock processing gloves, and industrial gloves.

Hereinafter, embodiments of the present specification will be described in more detail. However, the following experimental results describe only representative experimental results among the above examples, and the scope and content of the present specification may not be construed as reduced or limited by the examples. Each effect of the various embodiments of the present specification not explicitly presented below will be specifically described in the corresponding section.

Preparation Example 1

A 10 L high-pressure reactor equipped with a stirrer, a thermometer, a cooler, and an inlet for nitrogen gas and capable of continuously introducing each component was prepared. Under a nitrogen atmosphere, a monomer mixture containing 61.5 wt% of 1,3-butadiene, 32 wt% of acrylonitrile, and 6.5 wt% of methacrylic acid was added to the reactor based on the total weight of the mixture. Thereafter, 2 parts by weight of sodium alkylbenzene sulfonate, 0.5 parts by weight of t-dodecyl mercaptan, and 140 parts by weight of ion-exchanged water were added to the reactor with respect to 100 parts by weight of the monomer mixture. A weight part was added. And after raising the temperature of the reactor to about 40 ℃, potassium persulfate (potassium persulfate) was added 0.3 parts by weight.

When the conversion rate of 1,3-butadiene reached about 95%, 0.1 parts by weight of sodium dimethyldithiocarbamate was added to stop the polymerization reaction. Thereafter, by removing the unreacted monomer through a deodorizing process, and adding ammonia water, an antioxidant, an antifoaming agent, etc., a carboxylic acid-modified nitrile-based copolymer latex was prepared.

The solid content concentration of the carboxylic acid-modified nitrile-based copolymer latex was measured to be 45% by weight based on the total weight of the carboxylic acid-modified nitrile-based copolymer latex, and the hydrogen ion concentration index was measured as pH 8.0.

Preparation 2

Polyvinylpyrrolidone polymer having a weight average molecular weight of 7,000 to 11,000 g/mol was added to a 1 L container and stirred with secondary distilled water at 2,000 RPM for 1 hour to prepare a polyvinylpyrrolidone aqueous solution. At this time, the input amount of polyvinylpyrrolidone was calculated so that the solid content concentration was 20% by weight based on the total weight of the aqueous solution.

In addition, by adding a polyvinylpyrrolidone-vinyl acetate copolymer having a vinyl acetate content of 40% by weight based on the total weight of the copolymer in a 1 L container and stirring with secondary distilled water at 2,000 RPM for 1 hour, A polyvinylpyrrolidone-vinyl acetate copolymer aqueous solution was prepared. At this time, the input amount of the polyvinylpyrrolidone-vinyl acetate copolymer was calculated so that the solid content concentration was 20% by weight based on the total weight of the aqueous solution.

Preparation 3

An aqueous solution of fumed silica was prepared by putting fumed silica particles in a 1 L container and stirring at 1,500 RPM with secondary distilled water for 6 hours using a bead mill. In this case, as the fumed silica, a particle diameter of 20 to 30 nm was used, and the amount of the fumed silica was calculated so that the solid content concentration was 30% by weight based on the total weight of the aqueous solution.

Comparative Example 1

After putting the carboxylic acid-modified nitrile-based copolymer latex according to Preparation Example 1 into the reactor, it was stirred for 10 minutes at 4,000 RPM using a high-speed stirrer.

Then, in a 2 L plastic container, the carboxylic acid-modified nitrile-based copolymer latex, 40 wt% sulfur aqueous solution, 40 wt% zinc dibutyldithiocarbamate (ZDBC) hydrate, 40 wt% zinc oxide aqueous solution, 40 wt% % titanium dioxide aqueous solution, 4 wt% potassium hydroxide aqueous solution and secondary distilled water were added to obtain a latex composition for dip molding.

At this time, 400 g of carboxylic acid-modified nitrile-based copolymer latex mixed with the above additives, 11.25 g of sulfur aqueous solution, 6.75 g of ZDBC hydrate, 11.25 g of zinc oxide aqueous solution, 11.25 g of titanium dioxide aqueous solution, 1,350 g of potassium hydroxide aqueous solution, 2nd distilled water 474.8 g was added.

The solid content concentration of the latex composition for dip molding was measured to be 20% by weight based on the total weight of the latex composition for dip molding, and the hydrogen ion concentration index was measured to be pH 10.

Comparative Example 2

In the reactor, the carboxylic acid-modified nitrile-based copolymer latex according to Preparation Example 1, the polyvinylpyrrolidone aqueous solution according to Preparation Example 2 and the fumed silica aqueous solution according to Preparation Example 3 were added, and then 4,000 using a high-speed stirrer. By stirring at RPM for 10 minutes, a latex composition for dip molding was prepared in the same manner as in Comparative Example 1, except that a carboxylic acid-modified nitrile-based copolymer latex mixed with an additive was prepared.

At this time, the amount of the polyvinylpyrrolidone aqueous solution was calculated so that 0.25 parts by weight of the polyvinylpyrrolidone (PVP) solid content was added with respect to 100 parts by weight of the carboxylic acid-modified nitrile-based copolymer latex.

In addition, the amount of the fumed silica aqueous solution was calculated so that 0.7 parts by weight of the solid content of the fumed silica was added based on 100 parts by weight of the carboxylic acid-modified nitrile-based copolymer latex.

Comparative Example 3

After the carboxylic acid-modified nitrile-based copolymer latex according to Preparation Example 1, the polyvinylpyrrolidone-vinyl acetate copolymer aqueous solution according to Preparation Example 2 and the fumed silica aqueous solution according to Preparation Example 3 were put into the reactor, high-speed A latex composition for dip molding was prepared in the same manner as in Comparative Example 1, except that a carboxylic acid-modified nitrile-based copolymer latex mixed with an additive was prepared by stirring at 4,000 RPM using a stirrer for 10 minutes.

At this time, the input amount of the polyvinylpyrrolidone-vinylacetate copolymer aqueous solution is 0.25 parts by weight of the polyvinylpyrrolidone-vinylacetate copolymer (PVA) solid content based on 100 parts by weight of the carboxylic acid-modified nitrile-based copolymer latex. Calculated.

In addition, the amount of the fumed silica aqueous solution was calculated so that 0.7 parts by weight of the solid content of the fumed silica was added based on 100 parts by weight of the carboxylic acid-modified nitrile-based copolymer latex.

Example 1

The carboxylic acid-modified nitrile-based copolymer latex according to Preparation Example 1, the polyvinylpyrrolidone-acetate copolymer aqueous solution according to Preparation Example 2 and the fumed silica aqueous solution according to Preparation Example 3 were put into a reactor, and then sodium la After adding the less sulfate anionic dispersant, by stirring at 4,000 RPM for 10 minutes using a high-speed stirrer, dip in the same manner as in Comparative Example 1, except that the carboxylic acid-modified nitrile-based copolymer latex mixed with the additive was prepared. A latex composition for molding was prepared.

At this time, the input amount of the polyvinylpyrrolidone-vinylacetate copolymer aqueous solution was calculated so that 0.1 parts by weight of the polyvinylidone-vinylacetate copolymer (PVA) solid content was added with respect to 100 parts by weight of the carboxylic acid-modified nitrile-based copolymer latex. .

In addition, the amount of sodium laureth sulfate anionic dispersant added was calculated to be 0.1 parts by weight based on 100 parts by weight of carboxylic acid-modified nitrile-based copolymer latex.

In addition, the amount of the fumed silica aqueous solution was calculated so that 0.7 parts by weight of the solid content of the fumed silica was added based on 100 parts by weight of the carboxylic acid-modified nitrile-based copolymer latex.

Example 2

The carboxylic acid-modified nitrile-based copolymer latex according to Preparation Example 1, the polyvinylpyrrolidone-acetate copolymer aqueous solution according to Preparation Example 2 and the fumed silica aqueous solution according to Preparation Example 3 were put into a reactor, and then sodium la After adding the less sulfate anionic dispersant, by stirring at 4,000 RPM for 10 minutes using a high-speed stirrer, dip in the same manner as in Comparative Example 1, except that the carboxylic acid-modified nitrile-based copolymer latex mixed with the additive was prepared. A latex composition for molding was prepared.

At this time, the input amount of the polyvinylpyrrolidone-vinylacetate copolymer aqueous solution was calculated so that 0.1 parts by weight of the polyvinylidone-vinylacetate copolymer (PVA) solid content was added with respect to 100 parts by weight of the carboxylic acid-modified nitrile-based copolymer latex. .

In addition, the amount of sodium laureth sulfate anionic dispersant added was calculated to be added in 0.2 parts by weight based on 100 parts by weight of carboxylic acid-modified nitrile-based copolymer latex.

In addition, the amount of the fumed silica aqueous solution was calculated so that 0.7 parts by weight of the solid content of the fumed silica was added based on 100 parts by weight of the carboxylic acid-modified nitrile-based copolymer latex.

The content of each component of the latex prepared in Comparative Examples and Examples is summarized in Table 1 below.

division latex PVP PVA anion dispersant Fumed Silica Comparative Example 1 100 0 0 0 0 Comparative Example 2 100 0.25 0 0 0.7 Comparative Example 3 100 0 0.25 0 0.7 Example 1 100 0 0.1 0.1 0.7 Example 2 100 0 0.1 0.2 0.7

(Unit: parts by weight)

Experimental Example 1

The chemical stability of the latex composition for dip molding was analyzed by measuring the agglomeration time of the latex composition for dip molding according to the Comparative Examples and Examples. At this time, the agglomeration time refers to the time from the point of dropwise addition of the calcium chloride aqueous solution to the time at which the latex composition for dip molding starts to aggregate.

Specifically, 2 g of the latex composition for dip molding was added to a 300 mL beaker, 200 g of secondary distilled water was added, and the mixture was stirred at 200 RPM for 1 hour. Thereafter, an aqueous calcium chloride solution having a calcium chloride content of 0.3% by weight based on the total weight of the aqueous solution was added dropwise at a rate of 3 mL/min, and stirring was stopped when the latex composition for dip molding started to aggregate.

In order to quantitatively analyze the chemical stability of the latex composition for dip molding of the Comparative Examples and Examples, a Chemical Stability Index (CSI) expressed as in Equation 1 was calculated and shown in Table 2 below.

The higher the CSI value, the better the chemical stability.

[Equation 1]

CSI (%) = Aggregation time (minutes) of the latex composition for dip molding to be measured / Agglomeration time (minutes) of the latex composition for dip molding according to Comparative Example 1 * 100

division CSI (%) Comparative Example 1 100.0 Comparative Example 2 117.0 Comparative Example 3 120.4 Example 1 121.7 Example 2 125.2

Referring to Table 2, it can be confirmed that when PVP or PVA is used as an additive, stability is increased by 15% or more compared to latex without a separate additive even when fumed silica is added. In addition, it can be confirmed that when sodium laureth sulfate is added, excellent chemical stability can be achieved even when the amount of PVA is reduced.

Experimental Example 2

When liquid latex is stored for a long period of time, creaming occurs in the upper layer (upper mode) of the solution over time, and agglomeration and coagulation occur in the lower layer (lower mode). Therefore, in order to maintain a continuous dipping operation during the manufacture of gloves, the storage stability of the latex is important, and in the prior art, continuous stirring was performed to maintain the properties of the latex composition for dip molding.

The storage stability over time of the latex composition for dip molding of the Comparative Examples and Examples was comparatively measured. The measurement mode was compared in the zone mode using a Turbiscan power model measuring device, and the chemical stability of the latex composition for dip molding was analyzed by measuring the agglomeration time through accelerated agglomeration. At this time, the agglomeration time refers to the time from the point of dropwise addition of the calcium chloride aqueous solution to the time at which the latex composition for dip molding starts to aggregate.

In order to quantitatively analyze the storage stability of the latex composition for dip molding, a Storage Stability Index (SSI) expressed as Equation 2 below was calculated.

The smaller the SSI value, the better the storage stability.

[Equation 2]

Storage stability index (%) = measured intensity of the zone (upper or lower) mode of the latex composition for dip molding to be measured/measured intensity of the corresponding zone mode of the latex composition for dip molding according to Comparative Example 1 * 100

Table 3 below shows the results of comparing the zone mode state through the acceleration measurement for 3 days.

division Upper SSI (%) Lower SSI (%) Comparative Example 1 100 100 Comparative Example 2 96 94 Comparative Example 3 94 95 Example 1 87 84 Example 2 84 80

Referring to Table 3, it can be confirmed that when PVA and anionic dispersant are mixed and used, the storage stability of the latex composition for dip molding can be significantly improved even when a smaller amount is added.

Experimental Example 3

6 L of an aqueous solution of calcium nitrate having a calcium nitrate content of 18% by weight based on the total weight of the aqueous solution was put into an oven at 60° C., and then heated for about 3 hours to bring it to a medium temperature state.

After immersing a plate-shaped ceramic mold with a width*length*thickness of 17 cm*17 cm*0.5 cm in the medium-temperature solution for 1 minute, it was dried at 80° C. for 3 minutes, and the coagulant was applied to the plate-shaped ceramic mold. It was applied to the mold. Then, the flat ceramic mold coated with the coagulant was immersed in the latex composition for dip molding for 1 minute, dried at 70° C. for 10 minutes, and washed with water for 3 minutes.

The washed ceramic mold was dried again at 70° C. for 10 minutes, and then crosslinked at 120° C. for 25 minutes. After that, by winding the cross-linked flat latex film for dip molding from a ceramic mold, a sheet-shaped latex molded article for dip molding was obtained.

The physical properties of the latex molded article for dip molding were measured and shown in Table 3 below. At this time, the latex film test piece for dip molding was manufactured in a dumbbell shape according to ASTM D412.

division The tensile strength 100% modulus 300% modulus 500% modulus elongation Comparative Example 1 42.4 2.7 5.9 22.7 570 Comparative Example 2 46.9 2.5 4.8 16.2 615 Comparative Example 3 54.7 2.4 4.7 17.2 622 Example 1 54.5 2.5 4.7 16.9 617 Example 2 55.1 2.6 4.4 15.8 620 * Unit: Tensile strength (MPa), Elongation (%) Modulus (MPa)
* Measurement method: Using UTM (Universal Testing Machine), a specimen of latex film for dip molding was pulled at an elongation rate of 500 mm/min, and tensile strength, modulus and elongation at break were measured.

In general, the higher the tensile strength and elongation of the latex molded article, the better the dip quality.

Referring to Table 4, it can be confirmed that tensile strength and elongation are improved when a latex molded article for dip molding is manufactured using PVP or PVA and fumed silica at the same time. When an anionic dispersant is further added, a molded article having excellent tensile strength and elongation and excellent tactile properties can be manufactured even when a small amount of PVA is added.

The description of the present specification described above is for illustration, and those of ordinary skill in the art to which one aspect of the present specification belongs can easily transform it into other specific forms without changing the technical idea or essential features described in this specification. you will be able to understand Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. For example, each component described as a single type may be implemented in a dispersed form, and likewise components described as distributed may be implemented in a combined form.

The scope of the present specification is indicated by the following claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present specification.

Claims (18)

A latex composition for dip molding, comprising a carboxylic acid-modified nitrile-based copolymer latex, a polyvinylpyrrolidone-based resin, an anionic dispersant and a filler. According to claim 1,
The carboxylic acid-modified nitrile-based copolymer latex,
Based on the total weight of the carboxylic acid-modified nitrile-based copolymer latex,
45-80 wt% of a conjugated diene-based monomer;
15 to 45% by weight of an ethylenically unsaturated nitrile monomer; and
A latex composition for dip molding, including; 1 to 10% by weight of an ethylenically unsaturated acid monomer. 3. The method of claim 2,
The conjugated diene monomer is 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 1,3-pentadiene, isoprene, and a combination of two or more thereof. One selected from the group, a latex composition for dip molding. 3. The method of claim 2,
The ethylenically unsaturated nitrile monomer is one selected from the group consisting of acrylonitrile, methacrylonitrile, humaronitrile, α-chloronitrile, α-cyano ethyl acrylonitrile, and combinations of two or more thereof, dip molding latex composition for 3. The method of claim 2,
The ethylenically unsaturated acid monomer is acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, maleic anhydride, citraconic anhydride, styrene sulfonic acid, monobutyl fumarate, monobutyl maleate, mono-2-hydroxypropyl maleate and these One selected from the group consisting of a combination of two or more of, a latex composition for dip molding. According to claim 1,
The content of the polyvinylpyrrolidone-based resin is 0.1 to 3 parts by weight based on 100 parts by weight of the carboxylic acid-modified nitrile-based copolymer latex, a latex composition for dip molding. According to claim 1,
The polyvinylpyrrolidone-based resin,
20 to 80 weights of one monomer selected from the group consisting of vinyl acetate, vinyl propionate, vinyl butyrate, vinyl methoxy acetate, vinyl benzoate, and combinations of two or more thereof, based on the total weight of the polyvinylpyrrolidone-based resin % containing, a latex composition for dip molding. According to claim 1,
The polyvinylpyrrolidone-based resin has a weight average molecular weight of 5,000 to 50,000 g/mol, a latex composition for dip molding. According to claim 1,
The content of the anionic dispersant is 0.1 to 1 part by weight based on 100 parts by weight of the carboxylic acid-modified nitrile-based copolymer latex, a latex composition for dip molding. According to claim 1,
The anionic dispersant is one selected from the group consisting of sodium laureth sulfate, ammonium laureth sulfate, sodium laureth sulfonate, sodium lauryl sulfate, ammonium lauryl sulfate, and combinations of two or more thereof, latex for dip molding composition. According to claim 1,
The content of the filler is 0.1 to 5 parts by weight based on 100 parts by weight of the carboxylic acid-modified nitrile-based copolymer latex, a latex composition for dip molding. According to claim 1,
The average particle diameter of the filler is 10-200 nm, a latex composition for dip molding. According to claim 1,
The filler is one selected from the group consisting of silica, fumed silica, precipitated silica, silica sol, and combinations of two or more thereof, a latex composition for dip molding. According to claim 1,
The latex composition for dip molding further comprises one selected from the group consisting of a pigment, a vulcanizing agent, a vulcanization accelerator, a crosslinking agent, and a combination of two or more thereof. According to claim 1,
The carboxylic acid-modified nitrile-based copolymer latex further comprises one selected from the group consisting of an emulsifier, a polymerization initiator and a molecular weight regulator, a polymerization terminator, a pH regulator, an antioxidant, an oxygen scavenger, and a combination of two or more thereof, dip molding latex composition for (a) emulsion polymerization of a mixture of a conjugated diene-based monomer, an ethylenically unsaturated nitrile-based monomer and an ethylenically unsaturated acid monomer to obtain a carboxylic acid-modified nitrile-based copolymer latex; and
(b) mixing the polyvinylpyrrolidone-based resin aqueous solution, anionic dispersant, and filler aqueous solution with the product of step (a); comprising, a method for producing a latex composition for dip molding. A dip molded article obtained by dip molding the latex composition for dip molding according to claim 1 . 17. The method of claim 16,
The dip molded article is one selected from the group consisting of medical gloves, agricultural and livestock processing gloves, and industrial gloves.