Latex polymerization composition, latex for dip molding, and dip molded product produced therefrom

Abstract

Disclosed are a composition for latex polymerization, which contains a conjugated diene monomer, an ethylenically unsaturated nitrile monomer, an ethylenically unsaturated acid monomer, and an ionic compound and has an ionic conductivity of 275 μs / cm or more, a dip molding latex polymerized from the composition, and a dip molded product using the composition.

Description

[Technical field]

[0001] The present specification relates to a composition for latex polymerization, a dip molding latex obtained by polymerizing the composition, and a dip molded article produced therefrom. [Background technology]

[0002] Conventionally, dip-molded products such as gloves and condoms used for medical, food, inspection and experimental purposes have been manufactured mainly from natural rubber latex. However, such natural rubber latex molded products have the problem that they contain proteins inside, which can cause contact allergic reactions in users, such as rashes, itchiness, and colds. As a result, there is a tendency for the use of dip-molded products manufactured mainly from synthetic rubber latex, which does not contain any proteins, to increase.

[0003] As the amount of dip molding latex used increases, there is a need to improve its quality, and in recent years, attempts have been made to improve the durability of dip molded products made from dip molding latex, such as tensile strength and elongation. However, despite such attempts to improve mechanical properties, there continue to be cases where the dip molded products are damaged, resulting in fatal accidents, or where the desired purpose cannot be achieved.

[0004] This is because the physical properties of molded products deteriorate when they come into contact with human skin and body fluids such as sweat, which are weakly acidic, during actual use. Conventional mechanical properties such as tensile strength and elongation are measured in air at room temperature, and if these properties are excellent, the durability of the dip-molded product before use can be guaranteed, but there are cases where the durability under actual use conditions is poor. Therefore, the reality is that there is a demand for technological development to manufacture dip-molded products with excellent durability under actual use conditions.

[0005] As a result, there is an increasing demand for high-solids dip molding latexes that have excellent quality even in small quantities. However, conventional dip molding latexes have a problem that when the solid content is increased by concentration or the like, the viscosity increases rapidly above a certain content due to a decrease in particle stability.

[0006] In addition, dip molding latex generally contains particulate polymers with an average particle size of about 800 Å. There have been proposals to produce latex containing high-quality large-sized polymer particles by concentrating the polymers or enlarging them through chemical treatment, but there is a problem that the stability of the latex is rapidly reduced during the process. Summary of the Invention [Problem to be solved by the invention]

[0007] The present specification provides a polymerization composition for producing a dip molding latex having excellent stability, large particle size, high solid content and low viscosity, and provides a dip molded product having excellent quality by using the dip molding latex. [Means for solving the problem]

[0008] According to one embodiment, there is provided a composition for latex polymerization, comprising a conjugated diene monomer, an ethylenically unsaturated nitrile monomer, an ethylenically unsaturated acid monomer, and an ionic compound, and having an ionic conductivity of 275 μs / cm or more.

[0009] In one embodiment, the conjugated diene monomer may be at least one selected from the group consisting of 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, 2-phenyl-1,3-butadiene, 3-methyl-1,3-pentadiene, 2-chloro-1,3-butadiene, 3-butyl-1,3-octadiene, and octadiene.

[0010] In one embodiment, the ethylenically unsaturated nitrile monomer may be at least one selected from the group consisting of acrylonitrile, methacrylonitrile, fumaronitrile, α-chloronitrile, and α-cyanoethyl acrylonitrile.

[0011] In one embodiment, the ethylenically unsaturated acid monomer may be at least one selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, maleic anhydride, citraconic anhydride, styrene sulfonic acid, monobutyl fumarate, monobutyl maleate, and mono-2-hydroxypropyl maleate.

[0012] In one embodiment, the ionic compound may be at least one selected from the group consisting of sodium chloride, potassium chloride, calcium chloride, magnesium chloride, sodium nitrate, potassium nitrate, calcium nitrate, magnesium nitrate, sodium sulfate, potassium sulfate, calcium sulfate, magnesium sulfate, sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, sodium bicarbonate, potassium bicarbonate, sodium carbonate, potassium carbonate, sodium hydrogen sulfite, potassium bisulfite, sodium pyrophosphate, potassium pyrophosphate, trisodium phosphate, tripotassium phosphate, sodium monohydrogen phosphate, potassium monohydrogen phosphate, ethylenediaminetetraacetic acid or a sodium salt thereof, ethylene glycol tetraacetic acid or a sodium salt thereof, nitrilotriacetic acid or a sodium salt thereof, iminodiacetic acid or a sodium salt thereof, and quinolinic acid or a sodium salt thereof.

[0013] In one embodiment, the composition may include 30 to 90 parts by weight of a conjugated diene monomer, 1 to 55 parts by weight of an ethylenically unsaturated nitrile monomer, and 0.001 to 20 parts by weight of an ethylenically unsaturated acid monomer.

[0014] In one embodiment, the composition may further include water, an emulsifier, a polymerization initiator, and a molecular weight regulator.

[0015] According to another embodiment, there is provided a dip molding latex containing a copolymer derived from the above-mentioned composition for latex polymerization, the copolymer having an average particle size of 1,000 to 3,000 Å.

[0016] In one embodiment, the viscosity of the latex at 25° C. may be 50 to 2,500 cps.

[0017] In one embodiment, the solids content of the latex may be 50-65% by weight.

[0018] According to another aspect, there is provided a dip-molded article made from the dip-molding latex described above.

[0019] In one embodiment, the dip-molded product may be a surgical glove, a medical glove, an agricultural and livestock processing glove, an industrial glove, a condom, a cosmetic material, a catheter, or a healthcare product. Effect of the Invention

[0020] According to one embodiment, during polymerization of the latex, the stability of the polymer is significantly improved, and the trade-off between high solids, large particle size, and low viscosity can be simultaneously satisfied.

[0021] The effects of one embodiment of this specification should not be limited to the effects described above, but should be understood to include all effects that can be inferred from the configurations described in the detailed description and claims of this specification. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, an embodiment of the present specification will be described based on a specific example. However, the description of the present specification may be embodied in various different forms, and therefore, is not limited to the embodiment described herein.

[0023] Throughout the specification, when a part is described as being "connected" to another part, this includes not only the case where the part is "directly connected" to another part, but also the case where the part is "indirectly connected" to another part via another member in between. Furthermore, when a part is described as "comprising" a certain component, this does not mean that the part excludes other components, but means that the part can further include other components, unless otherwise specified.

[0024] When a range of numerical values ​​is given herein, unless a specific range is specifically stated, the values ​​have the precision of the significant figures provided in accordance with standard rules in chemistry for significant figures, for example, 10 includes a range of 5.0 to 14.9, and the number 10.0 includes a range of 9.50 to 10.49.

[0025] Composition for latex polymerization The composition for latex polymerization according to one embodiment includes a conjugated diene monomer, an ethylenically unsaturated nitrile monomer, an ethylenically unsaturated acid monomer, and an ionic compound, and may have an ionic conductivity of 275 μs / cm or more.

[0026] The composition for latex polymerization may have an ionic compound content adjusted to achieve a desired ionic conductivity. For example, the ionic conductivity of the composition may be 275 μs / cm or more, for example, 275 μs / cm, 277.5 μs / cm, 280 μs / cm, 282.5 μs / cm, 285 μs / cm, 287.5 μs / cm, 290 μs / cm, 292.5 μs / cm, 295 μs / cm, 297.5 μs / cm, 300 μs / cm, 302 μs / cm, 304 μs / cm, 306 μs / cm, 308 μs / cm, 309 μs / cm, 310 μs / cm, 311 μs / cm, 312 μs / cm, 313 μs / cm, 314 μs / cm, 315 μs / cm, 316 μs / cm, 317 μs / cm, 318 μs / cm, 319 μs / cm, 320 μs / cm, 321 μs / cm, 322 μs / cm, 323 μs / cm, 324 μs / cm, 325 μs / cm, 326 μs / cm, 327 μs / cm, 328 μs / cm, 329 μs / cm, 330 μs / cm, 335 μs / cm, 336 μs / cm, 337 μs / cm, 338 μs / cm, 339 μs / cm, 340 μs / cm, 341 μs / cm, 342 μs / cm, 343 μs / cm, 344 μs / cm, 345 μs / cm, 346 μs / cm, 347 μs / cm, 34 .5μs / cm, 305μs / cm, 307.5μs / cm, 310μs / cm, 312.5μs / cm, 315μs / cm, 317.5μs / cm, 320μ s / cm, 322.5μs / cm, 325μs / cm, 327.5μs / cm, 330μs / cm, 332.5μs / cm, 335μs / cm, 337.5μs / cm, 340 μs / cm, 342.5 μs / cm, 345 μs / cm, 347.5 μs / cm, 350 μs / cm, 352.5 μs / cm, 355 μs / cm, 357.5 μs / cm, 360 μs / cm, 362.5 μs / cm, 365 μs / cm, 367.5 μs / cm, 370 μs / cm, 372.5 μs / cm, 375 μs / cm, 377.5 μs / cm, 380 μs / cm, 382.5 μs / cm, 385 μs / cm, 387.5 μs / cm, 390 μs / cm, 392.5 μs / cm, 395 μs / cm, 397.5 μs / cm, 400 μs / cm, a range between any two of these values, or one or more of these values. If the ionic conductivity of the composition for latex polymerization is less than the above range, the stability of the polymerized latex is reduced, and especially when the solid content is concentrated by half or more, the viscosity may increase rapidly.

[0027] The ionic conductivity of the composition may be, but is not limited to, 10ms / cm or less, 5ms / cm or less, or 1ms / cm or less. If the ionic conductivity of the composition is too high, components unnecessary for polymerization may increase, and the stability of the latex may decrease.

[0028] The stability of latexes containing copolymers derived from conjugated diene monomers, ethylenically unsaturated nitrile monomers, and ethylenically unsaturated acid monomers can be improved by controlling the ionic conductivity during polymerization. This can be used to maintain low viscosity even at high solids contents of 50% by weight or more. Also, large particle size copolymers of 1,000 Å or more can be formed while maintaining stability.

[0029] The conjugated diene monomer may be at least one selected from the group consisting of 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, 2-phenyl-1,3-butadiene, 3-methyl-1,3-pentadiene, 2-chloro-1,3-butadiene, 3-butyl-1,3-octadiene, and octadiene. The structure derived from the conjugated diene monomer in the copolymer of the dip molding latex can impart flexibility to the dip molded product.

[0030] The ethylenically unsaturated nitrile monomer may be at least one selected from the group consisting of acrylonitrile, methacrylonitrile, fumaronitrile, α-chloronitrile, and α-cyanoethylacrylonitrile. The structure derived from the ethylenically unsaturated nitrile monomer in the copolymer of the dip molding latex can improve the strength and chemical resistance of the dip molding product.

[0031] The ethylenically unsaturated acid monomer may be at least one 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, and mono-2-hydroxypropyl maleate. In the copolymer of the dip molding latex, the structure derived from the ethylenically unsaturated acid monomer forms a crosslinked structure, which can improve the mechanical properties of the dip molding product.

[0032] The ionic compounds are sodium chloride (NaCl), potassium chloride (KCl), calcium chloride (CaCl 2), magnesium chloride (MgCl 2 ), sodium nitrate (NaNO 3 ), potassium nitrate (KNO 3 ), calcium nitrate (Ca(NO 3 ) 2 ), magnesium nitrate (Mg(NO 3 ) 2 ), sodium sulfate (Na 2 SO 4 ), potassium sulfate (K 2 SO 4 ), calcium sulfate (CaSO 4 ), magnesium sulfate (MgSO 4 ), sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca(OH) 2 ), magnesium hydroxide (Mg(OH) 2 ), sodium bicarbonate (NaHCO 3 ), potassium bicarbonate (KHCO 3 ), Sodium Carbonate (Na 2 CO 3 ), potassium carbonate (K 2 CO 3 ), sodium hydrogen sulfite (NaHSO 4 ), potassium bisulfite (KHSO 4 ), Sodium pyrophosphate (Na 4 P 2 O 7 ), potassium pyrophosphate (K 4 P 2 O 7 ), Trisodium Phosphate (Na 3 PO 4 ), tripotassium phosphate (K 3 PO 4 ), Sodium monohydrogen phosphate (Na 2 HPO 4 ), potassium monohydrogen phosphate (K 2 HPO 4The ionic compound may be at least one selected from the group consisting of ethylenediaminetetraacetic acid (EDTA) or its sodium salt, ethylene glycol tetraacetic acid (EGTA) or its sodium salt, nitrilotriacetic acid (NTA) or its sodium salt, iminodiacetic acid (IDA) or its sodium salt, and quinolinic acid (QNA) or its sodium salt. The ionic compound can improve the stability of the copolymer during the copolymerization reaction of the dip molding latex and can suppress the aggregation of the latex even after polymerization.

[0033] The composition may contain 30 to 90 parts by weight of a conjugated diene monomer, 1 to 55 parts by weight of an ethylenically unsaturated nitrile monomer, and 0.001 to 20 parts by weight of an ethylenically unsaturated acid monomer.

[0034] For example, the content of the conjugated diene monomer in the composition may be 30 parts by weight, 32.5 parts by weight, 35 parts by weight, 37.5 parts by weight, 40 parts by weight, 42.5 parts by weight, 45 parts by weight, 47.5 parts by weight, 50 parts by weight, 52.5 parts by weight, 55 parts by weight, 57.5 parts by weight, 60 parts by weight, 62.5 parts by weight, 65 parts by weight, 67.5 parts by weight, 70 parts by weight, 72.5 parts by weight, 75 parts by weight, 77.5 parts by weight, 80 parts by weight, 82.5 parts by weight, 85 parts by weight, 87.5 parts by weight, 90 parts by weight, or a range between two of these values. If the content of the conjugated diene monomer is less than 30 parts by weight, the dip molded product may be excessively hardened and have poor wearing comfort, and if it exceeds 90 parts by weight, the durability or chemical resistance of the dip molded product may be reduced.

[0035] The ethylenically unsaturated nitrile monomer content of the composition may be 1 part by weight, 2.5 parts by weight, 5 parts by weight, 7.5 parts by weight, 10 parts by weight, 12.5 parts by weight, 15 parts by weight, 17.5 parts by weight, 20 parts by weight, 22.5 parts by weight, 25 parts by weight, 27.5 parts by weight, 30 parts by weight, 32.5 parts by weight, 35 parts by weight, 37.5 parts by weight, 40 parts by weight, 42.5 parts by weight, 45 parts by weight, 47.5 parts by weight, 50 parts by weight, 52.5 parts by weight, 55 parts by weight, or a range between two of these values. If the ethylenically unsaturated nitrile monomer is less than 1 part by weight, the chemical resistance or mechanical strength of the dip molded article may be reduced, and if it exceeds 55 parts by weight, the elongation rate of the dip molded article may be reduced, and the usability may be reduced.

[0036] The ethylenically unsaturated acid monomer content of the composition may be 0.001 parts by weight, 0.5 parts by weight, 1 part by weight, 1.5 parts by weight, 2 parts by weight, 2.5 parts by weight, 3 parts by weight, 3.5 parts by weight, 4 parts by weight, 4.5 parts by weight, 5 parts by weight, 5.5 parts by weight, 6 parts by weight, 6.5 parts by weight, 7 parts by weight, 7.5 parts by weight, 8 parts by weight, 8.5 parts by weight, 9 parts by weight, 9.5 parts by weight, 10 parts by weight, 10.5 parts by weight 0.001 parts by weight, 11 parts by weight, 11.5 parts by weight, 12 parts by weight, 12.5 parts by weight, 13 parts by weight, 13.5 parts by weight, 14 parts by weight, 14.5 parts by weight, 15 parts by weight, 15.5 parts by weight, 16 parts by weight, 16.5 parts by weight, 17 parts by weight, 17.5 parts by weight, 18 parts by weight, 18.5 parts by weight, 19 parts by weight, 19.5 parts by weight, 20 parts by weight, or a range between two of these values. If the ethylenically unsaturated acid monomer is less than 0.001 parts by weight, the tensile strength of the dip-molded article may decrease, and if it exceeds 20 parts by weight, the dip-molded article may be excessively hardened, resulting in poor wearing comfort.

[0037] In the present specification, the term "total monomers" means a combination of the conjugated diene monomer, the ethylenically unsaturated nitrile monomer, and the ethylenically unsaturated acid monomer, but the composition for latex polymerization may further include polymerizable monomers other than the conjugated diene monomer, the ethylenically unsaturated nitrile monomer, and the ethylenically unsaturated acid monomer as long as the result of a durability test does not deviate from the above range, and in this case, the "total monomers" further includes the polymerizable monomers.

[0038] In a non-limiting example, the monomers contained in the composition may be the conjugated diene monomer, the ethylenically unsaturated nitrile monomer, and the ethylenically unsaturated acid monomer. By controlling the ionic conductivity through the ionic compound when copolymerizing the three kinds of monomers, the stability of the latex can be improved and the average particle size can be increased, but when adding separate monomers, it may be difficult to realize such an effect.

[0039] The content of the ionic compound may vary depending on the monomer composition ratio and the type of ionic compound. The content of the ionic compound may be 0.1 to 5 parts by weight based on 100 parts by weight of the total monomers under the condition of satisfying the above-mentioned ionic conductivity, for example, 0.1 parts by weight, 0.5 parts by weight, 1 parts by weight, 1.5 parts by weight, 2 parts by weight, 2.5 parts by weight, 3 parts by weight, 3.5 parts by weight, 4 parts by weight, 4.5 parts by weight, 5 parts by weight, or a range between two of these values. If it is out of the above range, it may be difficult to satisfy the condition of ionic conductivity, or even if the ionic conductivity is satisfied, the stability improvement effect may not be realized.

[0040] The composition for latex polymerization may further include water, an emulsifier, a polymerization initiator, and a molecular weight regulator.

[0041] The water may be 75 to 150 parts by weight based on 100 parts by weight of the total monomers, for example, 75 parts by weight, 77.5 parts by weight, 80 parts by weight, 82.5 parts by weight, 85 parts by weight, 87.5 parts by weight, 90 parts by weight, 92.5 parts by weight, 95 parts by weight, 97.5 parts by weight, 100 parts by weight, 102.5 parts by weight, 105 parts by weight, 107.5 parts by weight, 110 parts by weight, 112.5 parts by weight, 115 parts by weight, 117.5 parts by weight, 120 parts by weight, 122.5 parts by weight, 125 parts by weight, 127.5 parts by weight, 130 parts by weight, 132.5 parts by weight, 135 parts by weight, 137.5 parts by weight, 140 parts by weight, 142.5 parts by weight, 145 parts by weight, 147.5 parts by weight, 150 parts by weight, or a range between two of these values. If the water content is less than 75 parts by weight, the viscosity during polymerization may increase excessively, making it difficult to manufacture a molded product, and if it exceeds 150 parts by weight, the solid content may be excessively low. The water may have an ion conductivity of 5 μs / cm or less, 2.5 μs / cm or less, or 1 μs / cm or less. For example, the water may be ion-exchanged water, ultrapure water, or purified water. When water with high ion conductivity is used, it may contain impurities that adversely affect polymerization stability or latex stability.

[0042] The emulsifier may be an anionic surfactant, a nonionic surfactant, a cationic surfactant, or an amphoteric surfactant. For example, the anionic surfactant may be at least one selected from the group consisting of alkylbenzene sulfonate, aliphatic sulfonate, sulfate salt of higher alcohol, α-olefin sulfonate, and alkyl ether sulfate salt, but is not limited thereto. The emulsifier may be used in an amount of 0.8 to 8 parts by weight based on 100 parts by weight of the total monomers. The content of the ionic compound may be changed depending on the content of the emulsifier to achieve the above-mentioned ionic conductivity.

[0043] The polymerization initiator may be a radical initiator. The radical initiator may be, for example, The polymerization initiator may be at least one of inorganic peroxides selected from the group consisting of sodium persulfate, potassium persulfate, ammonium persulfate, potassium perphosphate, and hydrogen peroxide, organic peroxides selected from the group consisting of t-butyl peroxide, cumene hydroperoxide, p-menthane hydroperoxide, di-t-butyl peroxide, t-butylcumyl peroxide, acetyl peroxide, isobutyl peroxide, octanoyl peroxide, dibenzoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, and t-butylperoxyisobutyrate, and azo-based initiators selected from the group consisting of azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, azobiscyclohexanecarbonitrile, and methyl azobisisobutyrate (butyrate), but is not limited thereto. The polymerization initiator may be used in an amount of 0.01 to 1.5 parts by weight based on 100 parts by weight of the total monomers.

[0044] The molecular weight regulator may be, but is not limited to, mercaptans such as α-methylstyrene dimer, t-dodecyl mercaptan, n-dodecyl mercaptan, octyl mercaptan, etc., halogenated hydrocarbons such as carbon tetrachloride, methylene chloride, methylene bromide, etc., and sulfur-containing compounds such as tetraethylthiuram disulfide, dipentamethylenethiuram disulfide, diisopropylxanthogen disulfide, etc. The content of the molecular weight regulator may be 0.1 to 1 part by weight based on 100 parts by weight of the total monomers of the copolymer latex. For example, the molecular weight modifier may be 0.1 parts by weight, 0.15 parts by weight, 0.2 parts by weight, 0.25 parts by weight, 0.3 parts by weight, 0.35 parts by weight, 0.4 parts by weight, 0.45 parts by weight, 0.5 parts by weight, 0.55 parts by weight, 0.6 parts by weight, 0.65 parts by weight, 0.7 parts by weight, 0.75 parts by weight, 0.8 parts by weight, 0.85 parts by weight, 0.9 parts by weight, 0.95 parts by weight, 1 part by weight, or a range between two of these values. If the molecular weight modifier is less than 0.1 parts by weight, gel may be generated and the latex stability may be reduced, and if it exceeds 1 part by weight, the tensile strength may be poor or the stress retention rate may be reduced, and in addition, the durability in actual use may be reduced.

[0045] Dip molding latex A dip molding latex according to another embodiment is a dip molding latex containing a copolymer derived from the above-mentioned latex polymerization composition, and the average particle size of the copolymer is 1,000 to 3,000 Å, for example, 1,000 Å, 1,050 Å, 1,100 Å, 1,150 Å, 1,200 Å, 1,250 Å, 1,300 Å, 1,350 Å, 1,400 Å, 1,450 Å, 1,500 Å, 1,550 Å, 1,600 Å, 1,650 Å, 1,700 Å, 1,750 Å, 1,800 Å, 1,900 Å, 2,100 Å, 2,100 Å, 2,200 Å, 2,300 Å, 2,400 Å, 2,500 Å, 2,600 Å, 2,750 Å, 2,800 Å, 2,900 Å, 3,100 Å, 3,200 Å, 3,300 Å, 3,400 Å, 3,500 Å, 3,600 Å, 3,750 Å, 3,8 ...900 Å, 4,000 Å, 4,000 Å, 4,000 Å, 5,000 Å, 5,000 Å, 6 50 Å, 1,800 Å, 1,850 Å, 1,900 Å, 1,950 Å, 2,000 Å, 2,050 Å, 2,100 Å, 2,150 Å, 2,200 Å, 2,250 Å, 2,300 Å, 2,350 Å, 2,400 Å, 2,450 Å, 2,500 Å, 2,550 Å, 2,600 Å, 2,650 Å, 2,700 Å, 2,750 Å, 2,800 Å, 2,850 Å, 2,900 Å, 2,950 Å, 3,000 Å, or a range between two of these values. The dip molding latex can be polymerized by controlling the ion conductivity to minimize the decrease in stability and enlarge the particle size of the copolymer. In addition, the latex has a low oligomer content and is more stable.

[0046] The dip molding latex may have a zeta potential (absolute value) of 60 mV or more, 62.5 mV or more, 65 mV or more, 67.5 mV or more, or 70 mV or more. A latex that satisfies such conditions is excellent in stability, and can suppress an increase in viscosity even when concentrated with a high solid content of 50% by weight or more.

[0047] The viscosity of the dip molding latex at 25°C is 50 to 2,500 cps, for example, 50 cps, 75 cps, 100 cps, 125 cps, 150 cps, 175 cps, 200 cps, 225 cps, 250 cps, 275 cps, 300 cps, 325 cps, 350 cps, 375 cps, 400 cps, 425 cps, 450 cps, 475 cps, 500 cps, 525 cps, 550 cps, 575 cps, 600 cps, 625 cps, 650 cps, 675 cps, 700 cps, 725 cps, 750 cps, cps, 775 cps, 800 cps, 825 cps, 850 cps, 875 cps, 900 cps, 925 cps, 950 cps, 975 cps, 1,000 cps, 1,100 cps, 1,200 cps, 1,300 cps, 1,400 cps, 1,500 cps, 1,600 cps, 1,700 cps, 1,800 cps, 1,900 cps, 2,000 cps, 2,100 cps, 2,200 cps, 2,300 cps, 2,400 cps, 2,500 cps, or a range between any two of these values. If the viscosity is outside the above range, the latex may be substantially impossible to manufacture or difficult to dip mold.

[0048] The solid content of the dip molding latex may be 50 to 65% by weight, for example, 50%, 52.5%, 55%, 57.5%, 60%, 62.5%, 65% by weight, or a range between any two of these values. If the solid content is outside the above range, the effect of improving the stability described above may be unnecessary or the latex may aggregate.

[0049] The characteristics of the dip molding latex may be measured at pH 8.0 to 10.0, for example, pH 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, and 10.0. When adjusting the pH of the latex using an additive, the solid content and average particle size may change, but the dip molding latex can simultaneously satisfy the requirements of the average particle size, solid content, and viscosity described above in the above pH range.

[0050] The dip molding latex may further contain at least one additive selected from the group consisting of a chelating agent, a dispersant, a pH adjuster, an oxygen scavenger, a particle size adjuster, an antiaging agent, and an oxygen scavenger. These additives may be those known in the art, and as long as they satisfy the above-mentioned range of ion conductivity, the description of the type, function, and amount of addition will be omitted. Such additives may be added before or after polymerization of the copolymer.

[0051] The dip molding latex can simultaneously satisfy the requirements of low viscosity, solid content, and large particle size, and has excellent stability of the latex itself, so that the quality of the dip molding product can be prevented from being deteriorated even when subjected to external impact or during long-term storage.

[0052] Manufacturing method of latex for dip molding The method for preparing the latex for dip molding includes: (a) adding an emulsifier and water to a monomer mixture including a conjugated diene monomer, an ethylenically unsaturated nitrile monomer, and an ethylenically unsaturated acid monomer; (b) adding an ionic compound to adjust ionic conductivity; and (c) adding a polymerization initiator to prepare the latex for dip molding. In the step (b), the ionic compound may be added so that the ionic conductivity is 275 μs / cm or more.

[0053] The step (a) is a step of preparing a monomer mixture including a conjugated diene monomer, an ethylenically unsaturated nitrile monomer, and an ethylenically unsaturated acid monomer, which are monomers constituting a carboxylic acid-modified nitrile copolymer, and adding the monomer mixture to emulsified water, and may be carried out under a nitrogen atmosphere.

[0054] In step (a) or (b), a molecular weight regulator and an emulsifier may be further added, as described above.

[0055] The step (b) is a step of preparing the composition for latex polymerization by adding an ionic compound, and after adding all the components required for polymerization, the ionic conductivity is controlled, thereby achieving the above-mentioned stability improvement effect.

[0056] The polymerization in step (c) may be carried out at a temperature of 10 to 90°C, for example, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, or a temperature between any two of these temperatures.

[0057] When the conversion rate of the polymerization reaction is 90% or more, a polymerization terminator may be added to terminate the polymerization. For example, the polymerization terminator may be added when the conversion rate of the polymerization reaction is 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, or a value between two of these values.

[0058] The polymerization terminator may be one selected from the group consisting of hydroxylamine, hydroxylamine sulfate, diethylhydroxyamine, hydroxylamine sulfonic acid and its alkali metal ion, sodium dimethyldithiocarbamate, hydroquinone derivatives, aromatic hydroxydithiocarboxylic acids such as hydroxydiethylbenzenedithiocarboxylic acid and hydroxydibutylbenzenedithiocarboxylic acid, and combinations of two or more of these. The content of the polymerization terminator may be 0.02 to 1.5 parts by weight based on 100 parts by weight of the monomer mixture.

[0059] Other raw materials used in the above production method, their contents, etc. are as described above.

[0060] Dip Molding A dip-molded article according to another embodiment may be produced from the above-mentioned dip-molding latex.

[0061] A dip-molded product may be produced by adding 0.1 to 1 part by weight of zinc oxide, 1 to 2 parts by weight of sulfur, and 0.3 to 1.5 parts by weight of a vulcanization accelerator based on 100 parts by weight of the copolymer to the above-mentioned latex for dip molding, and then dip molding the mixture.

[0062] The zinc oxide may form an ionic bond with the structure derived from the ethylenically unsaturated acid to form a crosslinked structure. In addition, if the above-mentioned range of ionic conductivity is satisfied using an ionic compound, the ionic bond strength may be improved to improve durability. The zinc oxide may be, for example, 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight, or 1 part by weight. If the amount of zinc oxide is too small, the durability in practical use may decrease, and if the amount is too large, the tensile strength may decrease.

[0063] The sulfur may react with the structure derived from the conjugated diene monomer to form a crosslinked structure. If the ionic conductivity range is satisfied using an ionic compound, shrinkage of a molded product due to syneresis during vulcanization may be suppressed. The sulfur may be, for example, 1 part by weight, 1.1 parts by weight, 1.2 parts by weight, 1.3 parts by weight, 1.4 parts by weight, 1.5 parts by weight, 1.6 parts by weight, 1.7 parts by weight, 1.8 parts by weight, 1.9 parts by weight, or 2.0 parts by weight. If the sulfur is less than 1 part by weight, mechanical properties such as tensile strength and practical durability may be reduced, and if it exceeds 2 parts by weight, it may cause an allergic reaction in the user.

[0064] The dip-molded product may be obtained by adjusting the solid content of the dip-molding latex by adding an aqueous potassium hydroxide solution thereto, and then dip-molding the resulting product, but is not limited thereto.

[0065] The tensile strength of the dip-molded product may be, but is not limited to, 3 MPa or more, 5 MPa or more, 7 MPa or more, 9 MPa or more, 11 MPa or more, 13 MPa or more, 15 MPa or more, 20 MPa or more, 25 MPa or more, 30 MPa or more, or 35 MPa or more. As the tensile strength is higher, the durability during storage is improved, but other mechanical properties such as elongation may decrease.

[0066] The elongation of the dip-molded article may be, but is not limited to, 600% or more, 650% or more, 700% or more, 750% or more, 800% or more, 850% or more, or 900% or more. The higher the elongation, the better the wearing comfort, but there may be a trade-off with other mechanical properties.

[0067] The dip-molded article may have a durability test result of 60 minutes or more, a tensile strength of 10 MPa or more, and an elongation of 600% or more. By controlling the ionic conductivity during polymerization, it is possible to produce a high-quality dip-molded article that maintains minimum tensile strength and elongation and has excellent durability in practical use as confirmed by a durability test.

[0068] [Durability test method] A dip-molded product with a width of 30 mm, length of 135 mm, and thickness of 0.06 to 0.08 mm was stretched by 20% in the longitudinal direction and immersed in a pH 4.0 to 4.3 solution at 35°C. The molded product was stretched so that the longitudinal elongation rate was 50% for 10 seconds, fixed for 2 seconds, and then relaxed so that the longitudinal elongation rate was 20% for 10 seconds. This process was repeated, and the time until the molded product broke was measured.

[0069] The durability test method involves repeatedly stretching and relaxing a specimen in a solution at 35°C and pH 4.0 to 4.3, which are conditions similar to those of the skin and body fluids that the dip-molded article is likely to come into contact with during actual use, and checking for damage to the specimen. For example, if the molded article is a glove, the durability of the dip-molded article under actual use conditions can be measured by replicating the condition in which the molded article repeatedly stretches and relaxes in response to finger movements.

[0070] The dip-molded article may be a surgical glove, a medical glove, a glove for processing livestock products, an industrial glove, a condom, a cosmetic material, a catheter or a healthcare molded article.

[0071] For example, the dip-molded product may be a surgical glove or other medical glove, an industrial glove such as a glove for handling chemicals, or a cosmetic material such as a puff, but is not limited thereto.

[0072] The examples of the present specification will be described in more detail below. However, the following experimental results are only representative experimental results among the above examples, and the scope and content of the present specification should not be construed as being narrowed or limited by the examples. The effects of various embodiments of the present specification that are not explicitly presented below will be specifically described in the relevant section. Unless otherwise specified, each test may be performed under conditions of 20°C and 1 atm.

[0073] Examples and Comparative Examples A 1L high-pressure reactor was prepared, which was equipped with a stirrer, a thermometer, a cooler, and a nitrogen gas inlet, and was equipped so that each component such as a monomer, an emulsifier, and a polymerization initiator could be continuously added. Ion-exchanged water with a conductivity of 1 μs / cm or less was prepared. After the reactor was purged with nitrogen, a monomer mixture of 74 parts by weight of isoprene (IPM), 24 parts by weight of acrylonitrile (AN), and 2 parts by weight of methacrylic acid (MAA) was added. Then, an ionic compound (IC), 0.5 parts by weight of t-dodecyl mercaptan as a molecular weight regulator, 2 parts by weight of sodium alkylbenzene sulfonate as an emulsifier, and 120 parts by weight of ion-exchanged water were added to the reactor, relative to 100 parts by weight of the monomer mixture. The ionic conductivity of the reactants was measured, and the ionic compound was added until the desired ionic conductivity was reached, to prepare a composition for latex polymerization. The temperature of the reactor was raised to about 25° C., and 0.3 parts by weight of potassium persulfate was added. The types of ionic compounds used in each of the Examples and Comparative Examples and the ionic conductivity of the compositions for latex polymerization are shown in Table 1 below.

[0074] When the conversion rate reached about 95%, 0.9 parts by weight of sodium hydroxide was added to terminate the polymerization reaction. Thereafter, unreacted monomers were removed through a deodorizing process, and ammonia water, an antioxidant, an antifoaming agent, etc. were added to obtain a carboxylic acid modified nitrile copolymer latex with a pH of 8.5 (except for Example 6 and Comparative Example 6, which had a pH of 9.6). The zeta potential, average particle size, solid content, and viscosity of the latex were measured and are shown in Table 1 below.

[0075] In Comparative Example 7, no ionic compound was added to achieve the desired ion conductivity, and 0.05 parts by weight of a molecular weight regulator and 0.1 parts by weight of an emulsifier were added, but polymerization was not possible.

[0076] [Table 1]

[0077] -Ionic conductivity (μs / cm): Ionic conductivity was determined by the Nyquist diagram method after measuring the resistance with an electrochemical impedance spectroscopy (EIS) using a two-electrode method. The resistance was measured under conditions of a frequency of 60Hz to 1kHz, a current of 10.0mV, and a voltage range of ±10V. Ionic conductivity was measured after correction with a standard solution in the expected range. A graphite electrode was used as the electrode. The ionic conductivity was used as a value corrected to the standard temperature of 25°C.

[0078] - Zeta potential (mV): Zeta potential was measured at 25°C using a Malvern Zetasizer instrument.

[0079] - Average particle size (Å): measured by dynamic laser light scattering using Nanotrac 150.

[0080] Viscosity at -25°C (cps): Measured using a Brookfield viscometer at a spindle of 62 and 100 rpm.

[0081] Referring to Table 1, in the case of the examples in which the ion conductivity of the latex polymerization composition is relatively high, the zeta potential, which means the electrical stability of the latex particles, was measured to be relatively large. As a result, it is judged that it is possible to achieve a large particle size of 1,000 Å or more and a high solid content of 50 wt % or more while having low viscosity. Meanwhile, the zeta potential of the comparative latex polymerized under the condition of low ion conductivity was measured to be relatively small. Therefore, it was difficult to simultaneously achieve a large particle size, high solid content, and low viscosity due to lack of stability. In particular, the comparative latex with a small particle size had a problem that the viscosity rapidly increased when the solid content was increased through concentration. In addition, it is expected that when polymerization is performed while controlling the ion conductivity, the generation of low molecular weight oligomers is reduced and the stability of the latex is increased.

[0082] Experimental Example To 100 parts by weight of the latex of each of the examples and comparative examples, 1.8 parts by weight of sulfur (S), 0.7 parts by weight of zinc oxide (ZnO), and 1.2 parts by weight of zinc dibutyldithiocarbamate (ZDBC) as a vulcanization accelerator were added. Then, 4% aqueous potassium hydroxide solution and doubly distilled water were added to prepare a dip molding composition with a solid content concentration of 20% and a pH of 10.0. A rectangular specimen of the dip molding composition with a width of 30 mm, a length of 135 mm, and a thickness of 0.06 to 0.08 mm was prepared, and each physical property was measured and shown in Table 2 below.

[0083] [Table 2]

[0084] -Tensile strength and elongation: Using a Universal Testing Machine (UTM), a dumbbell-shaped specimen was elongated at a speed of 500 mm / min, and the tensile load and elongation at which the specimen broke were measured.

[0085] - Stress retention (S / R): Using a universal testing machine, the specimen was stretched to 100% elongation at a speed of 500 mm / min, and the initial tensile load (σ0) and the tensile load after 6 minutes (σ6) were measured. The stress retention was calculated using the following formula.

[0086]

number

[0087] - Durability: A pH 4 solution was prepared using citric acid and kept at 35°C. A rectangular specimen was immersed in the solution while being stretched by 20% in the vertical direction. The specimen was stretched to 50% elongation for 10 seconds, fixed for 2 seconds, and then relaxed to 20% elongation for 10 seconds, and this cycle was repeated to measure the time it took for the specimen to break.

[0088] Referring to Table 2, the specimens prepared using the latexes of the Examples were superior to the Comparative Examples in both mechanical strength and durability. In particular, comparing Example 4 and Comparative Example 4, which have similar solid content, the specimen of Example 4, which has a relatively large average particle size, was superior in mechanical strength and durability. This is believed to be because film shrinkage occurred in Comparative Example 4, which has a small average particle size, during the preparation of the specimen by dip molding.

[0089] The above description of the present specification is for illustrative purposes only, and a person having ordinary skill in the art to which one embodiment of the present specification belongs can easily understand that the present specification can be easily modified into other specific forms without changing the technical ideas and essential features described in the present specification. Therefore, it should be understood that the above-described embodiments are illustrative in all respects and are not limiting. For example, each component described in a single form may be implemented in a distributed form, and similarly, each component described as being distributed may be implemented in a combined form.

[0090] The scope of this specification is defined by the claims set forth below, and all modifications and variations derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of this specification.

Claims

1. Conjugated diene monomers, ethylenically unsaturated nitrile monomers, ethylenically unsaturated acid monomers, and Contains an ionic compound, A composition for latex polymerization having an ionic conductivity of 275 μs / cm or more.

2. The latex polymerization composition according to claim 1, wherein the conjugated diene monomer is at least one selected from the group consisting of 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, 2-phenyl-1,3-butadiene, 3-methyl-1,3-pentadiene, 2-chloro-1,3-butadiene, 3-butyl-1,3-octadiene, and octadiene.

3. 2. The latex polymerization composition according to claim 1, wherein the ethylenically unsaturated nitrile monomer is at least one selected from the group consisting of acrylonitrile, methacrylonitrile, fumaronitrile, α-chloronitrile, and α-cyanoethylacrylonitrile.

4. The latex polymerization composition according to claim 1, wherein the ethylenically unsaturated acid monomer is at least one 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, and mono-2-hydroxypropyl maleate.

5. 2. The composition for latex polymerization according to claim 1, wherein the ionic compound is at least one selected from the group consisting of sodium chloride, potassium chloride, calcium chloride, magnesium chloride, sodium nitrate, potassium nitrate, calcium nitrate, magnesium nitrate, sodium sulfate, potassium sulfate, calcium sulfate, magnesium sulfate, sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate, sodium carbonate, potassium carbonate, sodium hydrogen sulfite, potassium bisulfite, sodium pyrophosphate, potassium pyrophosphate, trisodium phosphate, tripotassium phosphate, sodium monohydrogen phosphate, potassium monohydrogen phosphate, ethylenediaminetetraacetic acid or a sodium salt thereof, ethylene glycol tetraacetic acid or a sodium salt thereof, nitrilotriacetic acid or a sodium salt thereof, iminodiacetic acid or a sodium salt thereof, and quinolinic acid or a sodium salt thereof.

6. The composition for latex polymerization according to claim 1, comprising 30 to 90 parts by weight of a conjugated diene monomer, 1 to 55 parts by weight of an ethylenically unsaturated nitrile monomer, and 0.001 to 20 parts by weight of an ethylenically unsaturated acid monomer.

7. 2. The latex polymerization composition of claim 1, further comprising water, an emulsifier, a polymerization initiator, and a molecular weight regulator.

8. A dip molding latex comprising a copolymer derived from the composition for latex polymerization according to claim 1, The average particle size of the copolymer is 1,000 to 3,000 Å.

9. The latex for dip molding according to claim 8, wherein the viscosity of the latex at 25° C. is 50 to 2,500 cps.

10. 9. The dip molding latex according to claim 8, wherein the solids content of the latex is 50 to 65% by weight.

11. A dip-molded product produced from the dip-molding latex according to any one of claims 8 to 10.

12. The dip-molded article according to claim 11, which is a surgical glove, a medical glove, an agricultural and livestock product processing glove, an industrial glove, a condom, a cosmetic material, a catheter, or a health care molded article.

Images