JP2006321881A - Method for producing copolymer latex used for dip-molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a copolymer latex used for dip-molding, having a high whiteness and excellent in touch feeling, tensile strength and stretch, and a dip-molded article. <P>SOLUTION: This method for producing the copolymer for dip-molding is characterized by performing the emulsion polymerization of monomers (total of the monomers is 100 pts.wt.) consisting of 50-80 wt.% 1,3-butadiene, 15-50 wt.% acrylonitrile, 0-10 wt.% ethylenically unsaturated carboxylic acid-based monomer and 0-35 wt.% ethylenically unsaturated monomer copolymerizable with the above monomers in the presence of 2-30 pts.wt. cyclic hydrocarbon having one double bond in its ring. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a method for producing a copolymer latex for dip molding. More specifically, the present invention relates to a method for producing a copolymer latex for dip molding that is excellent in whiteness, odor, texture, and tensile strength.

In recent years, rubber gloves have been widely used in various fields such as medical treatment, food processing field and electronic component manufacturing field due to increasing interest in safety and health. One method for producing these rubber gloves is the dip molding method. As the dip molding method, anode coagulation dipping is performed in which a mold made of wood, glass, ceramics, metal or plastic is dipped in a coagulant solution in advance and then dipped in a natural rubber latex composition or a synthetic rubber latex composition. There are known methods such as the Teg adhesion dipping method in which a mold is dipped in a latex composition and then dipped in a coagulating liquid, and a molded product obtained by these dip molding methods is a dip molded product. In these dip-molded products, the influence on the texture, tensile strength, elongation, and oil resistance is largely due to factors of the latex composition and the coagulation liquid composition. Conventionally, latex used in the dip molding method is typically natural rubber latex or synthetic rubber latex of acrylonitrile butadiene rubber (NBR rubber) having resistance to organic solvents and oils and fats. Recently, the former natural rubber latex may cause an allergic reaction depending on the amount of protein contained in some users. Synthetic rubber latex (NBR rubber) that does not contain the latter protein has attracted attention, and the amount used is also large. It has become to.
NBR rubber gloves are required to have high whiteness when used in the medical / food field where cleanliness is particularly required. However, if the whiteness of the copolymer latex, which is the raw material, is low, the product will be yellowish in the case of white non-colored gloves, and its commercial value will be impaired, and even in the case of colored gloves, color adjustment is difficult. It may become. For this reason, whiteness is required for the copolymer latex, but its investigation is not sufficient and no drastic solution has been proposed yet.
In addition, when used in the medical / food field, the NBR rubber gloves are required to have a low odor. However, if the odor of the copolymer latex as a raw material is strong, the odor when made into NBR rubber gloves tends to be strong, but examination of a copolymer latex with little odor is not sufficient.
In addition, as a basic physical property of gloves, improvement in texture (softness when wearing gloves) is required. For this purpose, for example, a method for defining the molecular weight of copolymer latex and insoluble part of methyl ethyl ketone (Japanese Patent Laid-Open No. 5-247266: Patent) Document 1, Japanese Patent Laid-Open No. 6-182788: Patent Document 2) has been proposed, and Japanese Patent Laid-Open No. 2003-165814 (Patent Document 3) describes the glass transition temperature by adjusting the composition of the copolymer. It has been proposed to use a latex composed of two different copolymers.
However, texture and other characteristics tend to conflict with each other, and it has been very difficult to satisfy all the characteristic balances at the same time. For example, when the amount of a conjugated diene compound such as butadiene having a low glass transition temperature is increased for the purpose of improving the texture, the texture is improved but the oil resistance and chemical resistance are poor.
JP-A-5-247266 JP-A-6-182788 JP 2003-165814 A

An object of the present invention is to provide a method for producing a copolymer latex for dip molding that is excellent in whiteness, odor, texture, and tensile strength.

As a result of intensive studies in view of the above-mentioned circumstances, the present inventors have carried out emulsion polymerization in the presence of a cyclic hydrocarbon having one double bond in the ring, thereby obtaining whiteness, odor, texture, and tensile strength. It was found that a copolymer latex for dip molding excellent in the above can be obtained, and the present invention has been completed.

That is, the present invention relates to 50 to 80% by weight of 1,3-butadiene, 15 to 50% by weight of acrylonitrile, 0 to 10% by weight of ethylenically unsaturated carboxylic acid monomer, and ethylenically unsaturated monomers copolymerizable therewith. Emulsion polymerization of monomers consisting of 0 to 35% by weight of monomer (total 100 parts by weight of monomer) in the presence of 2 to 30 parts by weight of cyclic hydrocarbon having one double bond in the ring. A method for producing a dip-molding copolymer latex is provided.

By using the dip molding latex obtained by the production method of the present invention, a dip molded product having excellent whiteness, odor, texture, and tensile strength can be obtained, and it is widely used in the medical and food processing fields. Rubber gloves can be obtained, which is extremely useful.

The present invention is described in detail below.
The monomer composition of the copolymer latex in the present invention is 1,3-butadiene 50 to 80% by weight, acrylonitrile 15 to 50% by weight, ethylenically unsaturated carboxylic acid monomer 0 to 10% by weight, and It is constituted by 0 to 35% by weight of a copolymerizable ethylenically unsaturated monomer.

1,3-butadiene needs to be used in the range of 50 to 80% by weight in the total monomers. If the amount of 1,3-butadiene is less than 50% by weight, the latex polymer after drying does not exhibit properties as an NBR rubber, which is not preferable. When 1,3-butadiene exceeds 80% by weight, the oil resistance decreases. Preferably it is 55 to 75% by weight.

Acrylonitrile needs to be used in the range of 15 to 50% by weight in all monomers. If acrylonitrile is less than 15% by weight, the oil resistance decreases, and if it exceeds 50% by weight, the latex polymer after drying does not exhibit properties as an NBR rubber, which is not preferable. Preferably it is 25 to 45% by weight.

Examples of the ethylenically unsaturated carboxylic acid monomer used in the present invention include acrylic acid, methacrylic acid, crotonic acid, fumaric acid, itaconic acid, maleic acid and the like. Can do. In particular, methacrylic acid is preferred.
The ethylenically unsaturated carboxylic acid-based monomer needs to be used in the range of 0 to 10% by weight in all monomers. If the ethylenically unsaturated carboxylic acid monomer exceeds 10% by weight, the viscosity of the copolymer latex becomes too high, and there is a high possibility that handling problems will occur in all applications.

  Examples of the ethylenically unsaturated monomer copolymerizable with these include 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene, Aliphatic conjugated diene compounds such as substituted linear conjugated pentadienes, substituted and side chain conjugated hexadienes, for example, vinyl cyanide compounds such as methacrylonitrile, α-chloroacrylonitrile, α-ethylacrylonitrile, such as styrene, α-methyl Aromatic vinyl compounds such as styrene, for example, unsaturated carboxylic acid alkyl such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-hydroxyethyl acrylate, methyl methacrylate, 2-hydroxyethyl methacrylate, glycidyl methacrylate Ester compounds such as acrylamide, Ethylenically unsaturated carboxylic acid amide compounds such as rhoamide, N, N-dimethylacrylamide and N-methylolacrylamide, for example, carboxylic acid vinyl esters such as vinyl acetate, such as methylaminoethyl (meth) acrylate, dimethylaminoethyl ( Examples thereof include ethylenically unsaturated amine compounds such as (meth) acrylate and 2-vinylpyridine, and one or more of them can be used.

Further, in the present invention, the presence of 2 to 30 parts by weight of a cyclic hydrocarbon having one double bond in the ring of the monomer having the above monomer composition (monomer total 100 parts by weight) It is necessary to emulsion polymerize under. When the hydrocarbon is less than 2 parts by weight, the elongation at break for dip molding is lowered, the tensile strength is lowered, and the effect of reducing odor is also lowered. On the other hand, when the amount of the hydrocarbon exceeds 30 parts by weight, the amount of aggregates generated in the emulsion polymerization increases, resulting in a decrease in yield. Examples of the cyclic hydrocarbon having one double bond in the ring include cyclopentene, cyclohexene, cycloheptene, 4-methylcyclohexene, 1-methylcyclohexene and the like. Cyclohexene and cyclopentene are particularly preferable.

In addition, there is no restriction | limiting in particular about superposition | polymerization temperature, However, It is 40-100 degreeC, Preferably it is 45-90 degreeC, Most preferably, it is 50-85 degreeC.

Although there is no restriction | limiting in particular about the gel content of the copolymer latex in this invention, A preferable gel content is 20 to 80 weight% especially from viewpoints, such as balance of texture and tensile strength.

The particle diameter of the copolymer latex is not particularly limited, but the preferable particle diameter of the copolymer latex is 200 nm or less. More preferably, it is 180 nm or less, and the most preferable particle diameter of the copolymer latex is 50 to 150 nm.

In the emulsion polymerization of the copolymer latex of the present invention, conventional emulsifiers, polymerization initiators, reducing agents, chain transfer agents, redox catalysts, electrolytes, polymerization accelerators, chelating agents, and the like can be used.

Examples of emulsifiers that can be used in the production of the copolymer latex of the present invention include sulfate esters of higher alcohols, alkylbenzene sulfonates, alkyl diphenyl ether sulfonates, aliphatic sulfonates, aliphatic carboxylates, and nonionic surfactants. Nonionic surfactants such as anionic surfactants such as sulfuric acid ester salts of polyethylene or alkyl ester type, alkyl phenyl ether type, alkyl ether type of polyethylene glycol, and the like, and one or more of these should be used Can do. In particular, alkylbenzene sulfonate and alkyl diphenyl ether sulfonate are preferable.

As the polymerization initiator, water-soluble polymerization initiators such as potassium persulfate, sodium persulfate, ammonium persulfate, cumene hydroperoxide, benzoyl peroxide, t-butyl hydroperoxide, acetyl peroxide, diisopropylbenzene hydroperoxide, An oil-soluble polymerization initiator such as 1,1,3,3-tetramethylbutyl hydroperoxide can be appropriately used. In particular, it is preferable to use a water-soluble polymerization initiator of potassium persulfate, sodium persulfate, or ammonium persulfate.

Specific examples of the reducing agent preferably used in the present invention include sulfite, bisulfite, pyrosulfite, nitrite, nithionate, thiosulfate, formaldehyde sulfonate, benzaldehyde sulfonate, Examples thereof include carboxylic acids such as L-ascorbic acid, tartaric acid and citric acid, further reducing sugars such as dextrose and saccharose, and amines such as dimethylaniline and triethanolamine.

Examples of the chain transfer agent that can be used for the production of the copolymer latex of the present invention include alkyls such as n-hexyl mercaptan, n-octyl mercaptan, t-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, and n-stearyl mercaptan. Xanthogen compounds such as mercaptan, dimethylxanthogen disulfide, diisopropylxanthogen disulfide, terpinolene, thiuram compounds such as tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetramethylthiuram monosulfide, 2,6-di-t-butyl-4 -Halogenation of phenolic compounds such as methylphenol and styrenated phenol, allyl compounds such as allyl alcohol, dichloromethane, dibromomethane, carbon tetrabromide, etc. Hydrogenated compounds, vinyl ethers such as α-benzyloxystyrene, α-benzyloxyacrylonitrile, α-benzyloxyacrylamide, triphenylethane, pentaphenylethane, acrolein, methacrolein, thioglycolic acid, thiomalic acid, 2-ethylhexylthioglyco A rate etc. are mentioned, These can be used 1 type or 2 or more types. In particular, n-octyl mercaptan and t-dodecyl mercaptan are preferable. The amount of these chain transfer agents is not particularly limited, but is usually 0 to 5 parts by weight with respect to 100 parts by weight of the monomer.

In the present invention, α-methylstyrene dimer can also be used as a chain transfer agent. α-Methylstyrene dimer includes 2,4-diphenyl-4-methyl-1-pentene, 2,4-diphenyl-4-methyl-2-pentene and 1,1,3-trimethyl-3-phenyl as isomers. Although there is indane, the α-methylstyrene dimer used in the present invention has a content of 2,4-diphenyl-4-methyl-1-pentene of 60% by weight or more, particularly 80% by weight or more. preferable. Since α-methylstyrene dimer has a high boiling point and remains in the latex particles even after the production of the copolymer latex, the amount used is 100 parts by weight of the monomer due to environmental problems different from the object of the present invention. The amount is preferably less than 2 parts by weight.

  Furthermore, anti-aging agents, preservatives, dispersants, thickeners and the like can be appropriately added to the copolymer latex as necessary.

As the polymerization method in the present invention, any one of single-stage polymerization, two-stage polymerization, multi-stage polymerization, seed polymerization, power feed polymerization method, etc. may be adopted. preferable. Further, the addition method of various components in the polymerization method of the present invention is not particularly limited, and any of a batch addition method, a divided addition method, and a continuous addition method can be employed.

  The copolymer latex in the present invention is used as a copolymer latex for dip molding. In order to obtain a dip-molded product, for example, a conventionally known dip-molding method such as a direct dipping method, an anode adhesion dipping method, or a teag dipping method is applied.

  Hereinafter, the anode adhesion dipping method will be briefly described. First, the mold is dipped in a coagulating liquid, and then pulled up and dried to make the coagulant adhere to the mold surface. The coagulation liquid is obtained by dissolving a calcium salt such as calcium chloride, calcium nitrate, or calcium acetate in water or a hydrophilic organic solvent such as alcohol or ketone. The calcium concentration in the coagulation liquid is usually 5 to 50% by weight, preferably 10 to 30% by weight. If necessary, the coagulation liquid may contain a surfactant such as nonionic or anionic surfactant, and a filler such as calcium carbonate, talc, or silica gel. Next, the mold to which the coagulant is attached is dipped in the copolymer latex composition for dip molding and pulled up. At this time, the coagulant and the copolymer latex react to form a rubbery film on the mold. The obtained film is washed with water, dried, and then peeled off from the mold to form a dip-molded product.

The latex composition for dip molding of the present invention includes, as necessary, rubber latex such as natural rubber latex and isoprene rubber latex, vulcanizing agents such as colloidal sulfur and thiuram disulfide, dialkyldithiocarbamate and xanthate. Vulcanization accelerators, zinc oxide, risurge (PbO), red lead (Pb ₃ O ₄ ), vulcanization accelerators such as magnesium oxide, fillers such as phthalic anhydride, benzoic acid, salicylic acid, magnesium carbonate, styrenation You may mix | blend suitably coloring agents, such as anti-aging agents, such as phenol, imidazoles, and paraphenylenediamine, and fast yellow, phthalocyanine blue, and ultramarine blue.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited to these Examples, unless the summary is exceeded. In the examples, parts and percentages indicating percentages are based on weight unless otherwise specified. In addition, various physical properties in the examples were evaluated by the following methods.

The particle size number measured average particle size of the copolymer latex was measured by dynamic light scattering method. In the measurement, LPA-3000 / 3100 manufactured by Otsuka Electronics was used.

Measurement of the gel content of the copolymer latex The film is dried at room temperature for 24 hours to prepare a film of the copolymer latex. About 1 g of the film is weighed and placed in 400 cc of methyl ethyl ketone and expanded and dissolved for 48 hours. Thereafter, this was filtered through a 300-mesh wire mesh, the methyl ethyl ketone insoluble part captured by the wire mesh was dried and weighed, and the ratio of this weight to the initial film weight was calculated as a gel content in wt%.

Each physical property of the dip-formed product was evaluated as follows, and the results are shown in Tables 1 and 2.
Evaluation of Whiteness of Dip Molded Product The whiteness of the dip molded product sample was determined with the naked eye as follows.
○: Yellow is not felt and white.
Δ: Slightly yellowish.
X: Obviously yellowish.
Evaluation of the texture of the dip-molded product The evaluation of the texture was performed by measuring the tensile stress when the glove-shaped dip-molded product reached a 300% elongation at a tensile rate of 300 mm / min. A smaller value indicates a better texture.
Evaluation of Tensile Strength and Elongation of Dip Molded Article For tensile strength evaluation, a glove-shaped dip molded article was pulled at a pulling speed of 300 mm / min, and the tensile strength and elongation immediately before breaking were measured.
Evaluation of odor of dip-molded product Evaluation of odor was made by leaving 5 parts of the obtained dip-molded product in a desiccator (sealed container) for 1 hour, then opening the lid, checking the odor, and evaluating in the following three stages. .
○: Almost no odor △: Slight odor ×: Strong odor

Example 1
Preparation of copolymer latex 1 (example of the present invention)
In a pressure resistant polymerization reactor, under a nitrogen atmosphere, 0.6 part of sodium bicarbonate, each monomer shown in addition 1 of Table 1, t-dodecyl mercaptan, cyclohexene, potassium persulfate, sodium dodecylbenzenesulfonate, pure water After the temperature was raised to 60 ° C., each monomer shown in addition 2 in Table 1, t-dodecyl mercaptan, sodium dodecylbenzenesulfonate, and pure water were continuously added over 10 hours. Thereafter, aging was performed until the polymerization conversion rate exceeded 95%. The pH is adjusted to 8 with an aqueous caustic potash solution, and diethylhydroxylamine shown in Table 1 is added as a polymerization terminator. Thereafter, steam distillation was performed at 90 ° C. for 15 hours to remove unreacted monomers and other low-boiling compounds. Further, the pH was adjusted to about 9 with an aqueous caustic potash solution to obtain a copolymer latex 1 having a particle size and a gel content shown in Table 1.

Example 2
Preparation of copolymer latex 2 (example of the present invention)
In a pressure resistant polymerization reactor, under a nitrogen atmosphere, 0.6 part of sodium bicarbonate, each monomer shown in addition 1 of Table 1, t-dodecyl mercaptan, cyclohexene, potassium persulfate, sodium dodecylbenzenesulfonate, pure water Then, the temperature was raised to 56 ° C., and then each monomer, t-dodecyl mercaptan, sodium dodecylbenzenesulfonate, and pure water shown in addition 2 in Table 1 were continuously added in 10 hours. Thereafter, aging was carried out until the polymerization conversion rate exceeded 97%. The pH is adjusted to 8 with an aqueous caustic potash solution, and diethylhydroxylamine shown in Table 1 is added as a polymerization terminator. Thereafter, steam distillation was performed at 90 ° C. for 15 hours to remove unreacted monomers and other low-boiling compounds. Further, the pH was adjusted to about 9 with an aqueous caustic potash solution to obtain a copolymer latex 2 having a particle size and a gel content shown in Table 1.

Example 3
Preparation of copolymer latex 3 (example of the present invention)
In a pressure resistant polymerization reactor, under a nitrogen atmosphere, 0.6 part of sodium bicarbonate, each monomer shown in addition 1 of Table 1, t-dodecyl mercaptan, cyclohexene, potassium persulfate, sodium dodecylbenzenesulfonate, pure water After the temperature was raised to 60 ° C., the respective monomers shown in addition 2 in Table 1, t-dodecyl mercaptan, cyclohexene, sodium dodecylbenzenesulfonate, and pure water were continuously added over 10 hours. Thereafter, aging was carried out until the polymerization conversion rate exceeded 97%. The pH is adjusted to 8 with an aqueous caustic potash solution, and diethylhydroxylamine shown in Table 1 is added as a polymerization terminator. Thereafter, steam distillation was performed at 90 ° C. for 15 hours to remove unreacted monomers and other low-boiling compounds. Further, the pH was adjusted to about 9 with a caustic potash aqueous solution to obtain a copolymer latex 3 having a particle size and a gel content shown in Table 1.

Example 4
Preparation of copolymer latex 4 (example of the present invention)
In a pressure-resistant polymerization reactor, under a nitrogen atmosphere, 0.3 part of sodium bicarbonate, each monomer shown in addition 1 of Table 1, n-octyl mercaptan, cyclopentene, potassium persulfate, sodium dodecylbenzenesulfonate, pure water Then, the temperature was raised to 55 ° C., and then each monomer, n-octyl mercaptan, sodium dodecylbenzenesulfonate, and pure water shown in addition 2 in Table 1 were continuously added in 10 hours. Thereafter, aging was carried out until the polymerization conversion rate exceeded 96%. The pH was adjusted to 8 with an aqueous caustic potash solution. Thereafter, steam distillation was performed at 90 ° C. for 15 hours to remove unreacted monomers and other low-boiling compounds. Further, the pH was adjusted to about 9 with a caustic potash aqueous solution to obtain a copolymer latex 4 having a particle size and a gel content shown in Table 1.

Example 5
Preparation of copolymer latex 5 (example of the present invention)
In a pressure resistant polymerization reactor, in a nitrogen atmosphere, 0.4 part of sodium bicarbonate, each monomer shown in addition 1 of Table 1, t-dodecyl mercaptan, cyclohexene, potassium persulfate, sodium dodecylbenzenesulfonate, pure water Then, the temperature was raised to 58 ° C., and then each monomer, t-dodecyl mercaptan, sodium dodecylbenzenesulfonate, and pure water shown in addition 2 in Table 1 were continuously added in 10 hours. Thereafter, aging was carried out until the polymerization conversion rate exceeded 97%. The pH is adjusted to 8 with an aqueous caustic potash solution, and diethylhydroxylamine shown in Table 1 is added as a polymerization terminator. Thereafter, steam distillation was performed at 90 ° C. for 15 hours to remove unreacted monomers and other low-boiling compounds. Further, the pH was adjusted to about 9 with an aqueous caustic potash solution to obtain a copolymer latex 5 having the particle size and gel content shown in Table 1.

Example 6
Preparation of copolymer latex 6 (example of the present invention)
In a pressure-resistant polymerization reactor, under a nitrogen atmosphere, 0.3 part of sodium bicarbonate, each monomer shown in addition 1 of Table 1, t-dodecyl mercaptan, cyclohexene, potassium persulfate, sodium dodecylbenzenesulfonate, pure water Then, the temperature was raised to 55 ° C., and then each monomer, t-dodecyl mercaptan, cyclohexene and pure water shown in addition 2 in Table 1 were continuously added in 5 hours. Subsequently, each monomer shown in Addition 3 of Table 1, t-dodecyl mercaptan, cyclohexene, and sodium dodecylbenzenesulfonate were continuously added in 5 hours. Thereafter, aging was carried out until the polymerization conversion rate exceeded 97%. The pH is adjusted to 8 with an aqueous caustic potash solution, and diethylhydroxylamine shown in Table 1 is added as a polymerization terminator. Thereafter, steam distillation was performed at 90 ° C. for 15 hours to remove unreacted monomers and other low-boiling compounds. Further, the pH was adjusted to about 9 with an aqueous caustic potash solution to obtain a copolymer latex 6 having a particle size and a gel content shown in Table 1.

Example 7
Preparation of copolymer latex 7 (example of the present invention)
In a pressure resistant polymerization reactor, under a nitrogen atmosphere, 0.6 part of sodium bicarbonate, each monomer shown in addition 1 of Table 1, t-dodecyl mercaptan, cyclohexene, potassium persulfate, sodium dodecylbenzenesulfonate, pure water Then, the temperature was raised to 55 ° C., and then each monomer, t-dodecyl mercaptan, sodium dodecylbenzenesulfonate, and pure water shown in addition 2 in Table 1 were continuously added in 10 hours. Thereafter, aging was performed until the polymerization conversion rate exceeded 95%. The pH is adjusted to 8 with an aqueous caustic potash solution, and diethylhydroxylamine shown in Table 1 is added as a polymerization terminator. Thereafter, steam distillation was performed at 90 ° C. for 15 hours to remove unreacted monomers and other low-boiling compounds. Further, the pH was adjusted to about 9 with an aqueous caustic potash solution to obtain a copolymer latex 7 having a particle size and gel content shown in Table 1.

Example 8
Preparation of copolymer latex 8 (example of the present invention)
In a pressure resistant polymerization reactor, under a nitrogen atmosphere, 0.2 part of sodium bicarbonate, each monomer shown in addition 1 in Table 1, t-dodecyl mercaptan, cyclohexene, potassium persulfate, sodium dodecylbenzenesulfonate, pure water Then, the temperature was raised to 55 ° C., and after 2 hours, the respective monomers shown in addition 2 in Table 1, t-dodecyl mercaptan, cyclohexene, sodium dodecylbenzenesulfonate, and pure water were continuously added in 6 hours. Thereafter, aging was performed until the polymerization conversion rate exceeded 97%. The pH is adjusted to 8 with an aqueous caustic potash solution, and diethylhydroxylamine shown in Table 1 is added as a polymerization terminator. Thereafter, steam distillation was performed at 90 ° C. for 15 hours to remove unreacted monomers and other low-boiling compounds. Further, the pH was adjusted to about 9 with an aqueous caustic potash solution to obtain a copolymer latex 8 having a particle size and gel content shown in Table 1.

Comparative Example 9
Preparation of copolymer latex 9 (comparative example)
To a pressure-resistant polymerization reactor, 0.6 parts of sodium bicarbonate, each monomer shown in addition 1 of Table 2, t-dodecyl mercaptan, potassium persulfate, sodium dodecylbenzenesulfonate, and pure water were added under a nitrogen atmosphere. Then, each monomer, t-dodecyl mercaptan, sodium dodecylbenzenesulfonate, and pure water shown in addition 2 in Table 2 were continuously added over 10 hours. Thereafter, aging was carried out until the polymerization conversion rate exceeded 97%. The pH is adjusted to 8 with an aqueous caustic potash solution, and diethylhydroxylamine shown in Table 2 is added as a polymerization terminator. Thereafter, steam distillation was performed at 90 ° C. for 15 hours to remove unreacted monomers and other low-boiling compounds. Further, the pH was adjusted to about 9 with an aqueous caustic potash solution to obtain a copolymer latex 9 having a particle size and gel content shown in Table 2.

Comparative Example 10
Preparation of copolymer latex 10 (comparative example)
To a pressure-resistant polymerization reactor, 0.6 parts of sodium bicarbonate, each monomer shown in addition 1 of Table 2, t-dodecyl mercaptan, potassium persulfate, sodium dodecylbenzenesulfonate, and pure water were added under a nitrogen atmosphere. Then, each monomer, t-dodecyl mercaptan, sodium dodecylbenzenesulfonate, and pure water shown in addition 2 in Table 2 were continuously added over 10 hours. Thereafter, aging was carried out until the polymerization conversion rate exceeded 97%. The pH is adjusted to 8 with an aqueous caustic potash solution, and diethylhydroxylamine shown in Table 2 is added as a polymerization terminator. Thereafter, steam distillation was performed at 90 ° C. for 15 hours to remove unreacted monomers and other low-boiling compounds. Further, the pH was adjusted to about 9 with an aqueous caustic potash solution to obtain a copolymer latex 10 having a particle size and gel content shown in Table 2.

Comparative Example 11
Preparation of copolymer latex 11 (comparative example)
In a pressure resistant polymerization reactor, under a nitrogen atmosphere, 0.6 parts of sodium bicarbonate, each monomer shown in addition 1 of Table 2, t-dodecyl mercaptan, cyclohexene, potassium persulfate, sodium dodecylbenzenesulfonate, pure water Then, the temperature was raised to 57 ° C., and then each monomer, t-dodecyl mercaptan, sodium dodecylbenzenesulfonate, and pure water shown in addition 2 in Table 2 were continuously added in 10 hours. Thereafter, aging was carried out until the polymerization conversion rate exceeded 97%. The pH is adjusted to 8 with an aqueous caustic potash solution, and diethylhydroxylamine shown in Table 2 is added as a polymerization terminator. Thereafter, steam distillation was performed at 90 ° C. for 15 hours to remove unreacted monomers and other low-boiling compounds. Further, the pH was adjusted to about 9 with an aqueous caustic potash solution to obtain a copolymer latex 11 having a particle size and a gel content shown in Table 2.

Comparative Example 12
Preparation of copolymer latex 12 (comparative example)
In a pressure resistant polymerization reactor, under a nitrogen atmosphere, 0.2 part of sodium bicarbonate, each monomer shown in addition 1 of Table 2, n-dodecyl mercaptan, potassium persulfate, sodium dodecylbenzenesulfonate, and pure water were added. The temperature was raised to 50 ° C., and after 3 hours, each monomer, n-dodecyl mercaptan, sodium dodecylbenzenesulfonate, and pure water shown in addition 2 in Table 2 were continuously added over 5 hours. Thereafter, aging was carried out until the polymerization conversion rate exceeded 97%. The pH was adjusted to 8 with an aqueous caustic potash solution. Thereafter, steam distillation was performed at 90 ° C. for 15 hours to remove unreacted monomers and other low-boiling compounds. Further, the pH was adjusted to about 9 with an aqueous caustic potash solution to obtain a copolymer latex 12 having a particle size and gel content shown in Table 2.

Preparation of latex composition for dip molding For the dip molding, the following compounding agents were added to the copolymer latexes 1 to 12 obtained in Examples 1 to 8 and Comparative Examples 9 to 12 above. A composition was obtained.
<Dip molding latex composition>
Latex for dip molding (solid content) 100.0 parts Zinc oxide 1.5 parts Colloidal sulfur 1.0 parts Zinc di-n-butyldithiocarbamate 0.5 parts Titanium dioxide 1.5 parts (solid content concentration 33%)

Manufacture of dip-molded product Separately, a 15% strength aqueous solution of calcium nitrate was prepared as a coagulation solution, dipped in a glove mold pre-dried at 80 ° C for 2 seconds, pulled up, leveled and rotated And dried (80 ° C. × 2 minutes). Subsequently, the mold for gloves was immersed in the dip molding composition for 2 seconds, pulled up, and then leveled and dried under rotation (80 ° C. × 2 minutes). Next, the mold for gloves was immersed in warm water at 40 ° C. for 3 minutes, washed, and then heated at 120 ° C. for 20 minutes to obtain a solid film on the surface of the mold for gloves. Finally, the solid coating was removed from the glove mold to obtain a glove-shaped dip molding.

Tables 1 and 2 summarize the evaluation results of the particle diameter, gel content, whiteness, texture, tensile strength, elongation, and odor of each copolymer latex.

As described above, by using the dip molding latex of the present invention, a dip molded product having high whiteness and excellent texture, tensile strength, elongation, and oil resistance can be obtained. Rubber gloves and the like widely used in various fields such as the processing field and the electronic component manufacturing field can be obtained.

Claims (2)

1,3-butadiene 50 to 80% by weight, acrylonitrile 15 to 50% by weight, ethylenically unsaturated carboxylic acid monomer 0 to 10% by weight, and ethylenically unsaturated monomer 0 to 35 copolymerizable therewith A dip characterized in that a monomer comprising 100% by weight (monomer total 100 parts by weight) is emulsion polymerized in the presence of 2 to 30 parts by weight of a cyclic hydrocarbon having one double bond in the ring. A method for producing a molding copolymer latex. 2. The dip-forming co-polymer according to claim 1, wherein the cyclic hydrocarbon having one double bond in the ring is at least one selected from cyclopentene, cyclohexene, cycloheptene, 4-methylcyclohexene, and 1-methylcyclohexene. A method for producing a combined latex.