JP2016132761A - Method for producing dip molding and dip molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a dip molding which makes it possible to obtain a dip molding having high tear strength with a small number of steps.SOLUTION: The present invention employs a synthetic polyisoprene in which a ratio of the amount of polymerization accelerator to the amount of active catalyst is 0.001-0.400(mol/mol), a weight average molecular weight is 600,000 or more, and a 1,4-cis content is 78% or more.SELECTED DRAWING: None

Description

  The present invention relates to a method for manufacturing a dip-molded body and a dip-molded body. More specifically, the present invention relates to a method for manufacturing a dip-molded body having high tear strength, and a dip-molded body manufactured by this manufacturing method.

  Conventionally, it is known that a dip molding composition containing a latex of natural rubber is dip-molded to obtain a dip-molded body used in contact with a human body such as a nipple, a balloon, a glove, a balloon, and a sack. Yes. However, since natural rubber latex contains a protein that causes allergic symptoms in the human body, there are cases in which there is a problem as a dip-molded product that is in direct contact with a living mucous membrane or an organ. Therefore, studies have been made to use synthetic polyisoprene latex instead of natural rubber latex.

  However, when a dip molded body obtained from synthetic polyisoprene latex is used as a glove, the tear strength is inferior to that when a dip molded body obtained from natural rubber latex is used as a glove. There was a risk of tearing inside. For this reason, development of the glove using the synthetic polyisoprene latex which has high tear strength was calculated | required.

  Moreover, when obtaining synthetic polyisoprene latex, synthetic polyisoprene was dissolved in a hydrocarbon solvent, a surfactant was added and mixed, and the hydrocarbon solvent was removed (see, for example, Patent Documents 1 to 3). . However, from the viewpoint of simplifying the process in which the step of dissolving the synthetic polyisoprene in the hydrocarbon solvent can be omitted, it is preferable to obtain the synthetic polyisoprene in a state dissolved in the solvent.

Japanese Patent No. 5031821 Japanese Patent No. 5155295 Japanese Patent No. 5260737

  An object of this invention is to provide the manufacturing method of a dip molded object and the dip molded object which can obtain the dip molded object which has high tear strength with few processes.

  As a result of intensive studies to solve the above problems, the present inventors have found that the amount of active catalyst and the amount of polymerization accelerator are in a specific range, the weight average molecular weight is in a specific range, and 1,4-cis is contained. It has been found that the above object can be achieved by using synthetic polyisoprene having a specific ratio, and the present invention has been completed.

That is, according to the present invention,
(1) The ratio of the amount of polymerization accelerator to the amount of active catalyst is in the range of 0.001 to 0.400 (mol / mol), the weight average molecular weight is 600,000 or more, and 1,4- a method for producing a dip-molded body using a synthetic polyisoprene having a cis content of 78% or more,
(2) The method for producing a dip-molded article according to (1), wherein the amount of the polymerization accelerator is in the range of 0.005 to 0.300 (mol / mol) with respect to the amount of the active catalyst.
(3) The method for producing a dip-molded article according to (1) or (2), wherein the 1,4-cis content of the synthetic polyisoprene is 80% or more,
(4) The method for producing a dip-molded product according to any one of (1) to (3), wherein the synthetic polyisoprene has a weight average molecular weight of 800,000 or more,
(5) The method for producing a dip-molded article according to any one of (1) to (4), wherein the polymerization initiation temperature in producing the synthetic polyisoprene is in the range of 20 to 70 ° C.
(6) A dip-molded body obtained by the method for producing a dip-molded body according to any one of (1) to (5) is provided.

  According to the method for producing a dip-formed body of the present invention, a dip-formed body having a high tear strength can be obtained with a small number of steps. Moreover, according to this invention, the dip molded object obtained by the manufacturing method of this dip molded object can be provided.

Hereinafter, the manufacturing method of the dip molding of this invention is demonstrated. In the method for producing a dip-molded article of the present invention, the amount of the polymerization accelerator relative to the amount of the active catalyst (hereinafter sometimes referred to as “I ^* ”) is in the range of 0.001 to 0.400 (mol / mol). In addition, a synthetic polyisoprene having a weight average molecular weight of 600,000 or more and a 1,4-cis content of 78% or more is used.

(Synthetic polyisoprene)
The synthetic polyisoprene used in the present invention is obtained by polymerizing isoprene. Further, the synthetic polyisoprene used in the present invention may be a copolymer of other ethylenically unsaturated monomers copolymerizable with isoprene. The content of the isoprene unit in the synthetic polyisoprene is flexible and it is easy to obtain a dip-molded article excellent in tensile strength. Therefore, the content is preferably 70% by weight or more, more preferably 90% by weight based on the total monomer units. % Or more, more preferably 95% by weight or more, and particularly preferably 100% by weight (isoprene homopolymer).

  Examples of other ethylenically unsaturated monomers copolymerizable with isoprene include conjugated diene monomers other than isoprene such as butadiene, chloroprene and 1,3-pentadiene; acrylonitrile, methacrylonitrile, fumaronitrile, α- Ethylenically unsaturated nitrile monomers such as chloroacrylonitrile; vinyl aromatic monomers such as styrene and alkylstyrene; methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, (meth) And ethylenically unsaturated carboxylic acid ester monomers such as acrylic acid-2-ethylhexyl; and crosslinkable monomers such as divinylbenzene, diethylene glycol di (meth) acrylate, and pentaerythritol (meth) acrylate. In addition, the other ethylenically unsaturated monomer copolymerizable with these isoprenes may be used individually by 1 type, and may use multiple types together.

  As the isoprene unit in the synthetic polyisoprene, there are four types of 1,4-cis bond unit, 1,4-trans bond unit, 1,2-vinyl bond unit, and 3,4-vinyl bond unit depending on the bond state of isoprene. Exists.

  The content of 1,4-cis bond units (1,4-cis content) in the isoprene units contained in the synthetic polyisoprene is 78% by weight or more, preferably 80% by weight, based on all isoprene units. That's it. When the 1,4-cis content is in the above range, the tensile strength of the resulting dip-molded product can be improved.

  The weight average molecular weight of the synthetic polyisoprene is 600,000 or more, preferably 800,000 or more in terms of standard polystyrene by gel permeation chromatography analysis. The weight average molecular weight of the synthetic polyisoprene is preferably 5 million or less, more preferably 3 million or less in terms of standard polystyrene by gel permeation chromatography analysis. If the weight average molecular weight of the synthetic polyisoprene is too small, the tensile strength of the dip-molded product tends to decrease. Conversely, if it is too large, the synthetic polyisoprene latex tends to be difficult to produce.

The polymer Mooney viscosity [ML _{1 + 4} , 100 ° C.] of the synthetic polyisoprene is preferably 50 to 80, more preferably 60 to 80, and still more preferably 70 to 80.

  Synthetic polyisoprene can be obtained, for example, by solution polymerization of isoprene in an inert polymerization solvent using a polymerization catalyst. In the present invention, it is preferable to use an alkyllithium polymerization catalyst such as n-butyllithium or sec-butyllithium as the polymerization catalyst from the viewpoint of performing a polymerization reaction at a high polymerization conversion rate. It is more preferable to use

The amount (I ^* ) of the active catalyst in the synthetic polyisoprene used in the present invention is preferably 0.020 to 0.220 mmol, more preferably 0.040 to 0.170 mmol, based on 100 parts by weight of the synthetic polyisoprene. . Here, the active catalyst is not a catalyst component that has lost its function as a catalyst due to a reaction with an impurity such as oxygen, water or acetylene, or a polymerization terminator, but a catalyst that can exhibit its function as a catalyst. is there.

  In the present invention, a polymerization accelerator is used in addition to the polymerization catalyst in the polymerization of the synthetic polyisoprene. As the polymerization accelerator, tetramethylethylenediamine (TMEDA), hexamethylphosphoramide (HMPA), N, N′-dimethylpropyleneurea (DMPU), dimethylsulfoxide (DMSO), or the like can be used. Among these, it is preferable to use TMEDA.

  The amount of the polymerization accelerator in the synthetic polyisoprene used in the present invention is preferably 0.00003 to 0.088 mmol, more preferably 0.00013 to 0.066 mmol, with respect to 100 parts by weight of the synthetic polyisoprene.

  In the present invention, from the viewpoint of simplifying the process, it is preferable to produce a synthetic polyisoprene latex, which will be described later, using the obtained polymer solution of synthetic polyisoprene as it is. In the production of synthetic polyisoprene latex, solid synthetic polyisoprene (which may be commercially available) is dissolved in an organic solvent after taking out the solid synthetic polyisoprene from the polymer solution of synthetic polyisoprene. However, in the present invention, it is not preferable from the viewpoint of simplifying the process.

The ratio of the amount of polymerization accelerator to the amount of active catalyst (I ^* ) in the synthetic polyisoprene used in the present invention is 0.001 to 0.400 (mol / mol), preferably 0.005 to 0.300 (mol). / Mol).

  Moreover, the polymerization start temperature at the time of polymerizing the synthetic polyisoprene is preferably 20 to 70 ° C.

  The molecular weight distribution of the synthetic polyisoprene used in the present invention is the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) measured as a polystyrene equivalent value by gel permeation chromatography. ) Is preferably 1.1 to 2.2.

  In addition, after synthesizing polyisoprene, impurities such as a residue of the polymerization catalyst remaining in the polymer solution may be removed. Moreover, you may add the anti-aging agent mentioned later to the solution after superposition | polymerization.

(Synthetic polyisoprene latex)
The dip-molded product obtained by the method for producing a dip-molded product of the present invention is obtained by dip-molding a dip-molding composition containing a synthetic polyisoprene latex. The synthetic polyisoprene latex comprises the synthetic polyisoprene.

  As a method for producing a synthetic polyisoprene latex, for example, (1) a solution or fine suspension of a synthetic polyisoprene dissolved or finely dispersed in an organic solvent is emulsified in water in the presence of a surfactant, and if necessary, A method for producing a synthetic polyisoprene latex by removing an organic solvent, (2) emulsion polymerization or suspension polymerization of isoprene alone or a mixture of ethylenically unsaturated monomers copolymerizable with isoprene, Although a method for directly producing a synthetic polyisoprene latex is mentioned, synthetic polyisoprene having a high proportion of 1,4-cis bond units in the isoprene unit can be used, and a dip molded article having excellent tensile strength is obtained. Therefore, the production method (1) is preferable.

Examples of the organic solvent used in the production method (1) include aromatic hydrocarbon solvents such as benzene, toluene and xylene; alicyclic hydrocarbon solvents such as cyclopentane, cyclopentene, cyclohexane and cyclohexene; pentane, hexane, And aliphatic hydrocarbon solvents such as heptane; halogenated hydrocarbon solvents such as methylene chloride, chloroform and ethylene dichloride; Of these, aromatic hydrocarbon solvents and alicyclic hydrocarbon solvents are preferred, with cyclohexane and toluene being particularly preferred.
In addition, the usage-amount of an organic solvent becomes like this. Preferably it is 2,000 weight part or less with respect to 100 weight part of synthetic polyisoprenes, More preferably, it is 20-1,500 weight part.

  Examples of the surfactant used in the production method of (1) above include nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenol ether, polyoxyethylene alkyl ester, polyoxyethylene sorbitan alkyl ester; Sodium or potassium salts of fatty acids such as lauric acid, myristic acid, palmitic acid, oleic acid, linolenic acid, rosin acid, alkylbenzene sulfonates such as sodium dodecylbenzene sulfonate, higher alcohol sulfates, alkyl sulfosuccinates, etc. Anionic surfactants; cationic surfactants such as alkyltrimethylammonium chloride, dialkyldimethylammonium chloride, alkylbenzyldimethylammonium chloride; , Β-unsaturated carboxylic acid sulfoesters, α, β-unsaturated carboxylic acid sulfate esters, sulfoalkylaryl ethers and the like, and the like, and anionic surfactants are preferred. Particularly preferred are sodium rosinate and sodium dodecylbenzene sulfonate. In addition, these surfactants may be used individually by 1 type, and may use 2 or more types together.

  The amount of the surfactant used is preferably 0.5 to 50 parts by weight, more preferably 0.5 to 30 parts by weight with respect to 100 parts by weight of the synthetic polyisoprene. If the amount is too small, the stability of the latex tends to be inferior. On the other hand, if the amount is too large, foaming tends to occur and problems may occur during dip molding.

  The amount of water used in the production method (1) is preferably 50 to 5,000 parts by weight, more preferably 100 to 3,000 parts by weight, based on 100 parts by weight of the synthetic polyisoprene.

  Examples of the water used include hard water, soft water, ion exchange water, distilled water, and zeolite water. Moreover, you may use together the polar solvent represented by alcohol, such as methanol, with water.

  An apparatus for emulsifying an organic solvent solution or fine suspension of synthetic polyisoprene in water in the presence of a surfactant is not particularly limited as long as it is generally commercially available as an emulsifier or a disperser. The addition method of the surfactant is not particularly limited, and the emulsified liquid may be added during the emulsification operation even if it is added to the organic solvent solution or fine suspension of water and / or synthetic polyisoprene in advance. It may be added in a batch, or may be added all at once or dividedly.

  Examples of the emulsifier include a batch type emulsifier such as trade name: homogenizer (manufactured by IKA), trade name: polytron (manufactured by Kinematica), trade name: TK auto homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), etc. Name: TK Pipeline Homomixer (manufactured by Koki Kogyo Kogyo Co., Ltd.), Product Name: Colloid Mill (made by Shinko Pantech Co., Ltd.), Product Name: Thrasher (manufactured by Nihon Coke Kogyo Co., Ltd.), Product Name: Trigonal Wet Fine Crusher ( Product name: Cavitron (manufactured by Eurotech), product name: Milder (manufactured by Taiheiyo Kiko Co., Ltd.), product name: Fine Flow Mill (manufactured by Taiheiyo Kiko Co., Ltd.), etc. Name: Microfluidizer (manufactured by Mizuho Kogyo Co., Ltd.), Product name: Nanomizer (manufactured by Nanomizer Co., Ltd.), Product name: APV Gaurin (manufactured by Gaulin Co., Ltd.), etc .; Membrane emulsifiers such as chemical generators (manufactured by Chilling Industries Co., Ltd.); Product name: Vibrating emulsifiers such as Vibro mixers (manufactured by Chilling Industries Co., Ltd.); Machine; and the like. In addition, the conditions of the emulsification operation by the emulsification apparatus are not particularly limited, and the treatment temperature, the treatment time, and the like may be appropriately selected so as to obtain a desired dispersion state.

  In the method (1), it is preferable to obtain a synthetic polyisoprene latex by removing the organic solvent from the emulsion obtained through the emulsification operation. The method for removing the organic solvent from the emulsion is not particularly limited, and methods such as vacuum distillation, atmospheric distillation, steam distillation, and centrifugation can be employed.

  Further, after removing the organic solvent, if necessary, in order to increase the solid content concentration of the synthetic polyisoprene latex, a concentration operation may be performed by a method such as vacuum distillation, atmospheric distillation, centrifugal separation or membrane concentration.

The solid content concentration of the synthetic polyisoprene latex is preferably 30 to 70% by weight, more preferably 40 to 70% by weight. If the solid content concentration is too low, there is a concern that the synthetic polyisoprene particles are separated when the synthetic polyisoprene latex is stored. Conversely, if the solid content concentration is too high, the synthetic polyisoprene particles are aggregated to generate coarse aggregates. There is a case.
It may be added.

  The volume average particle diameter of latex particles (synthetic polyisoprene particles) in the synthetic polyisoprene latex is preferably 0.5 to 10 μm, more preferably 0.5 to 3 μm, and particularly preferably 0.5 to 2 μm. . If the volume average particle size is too small, the latex viscosity may become too high and difficult to handle. Conversely, if the volume average particle size is too large, a film may be formed on the latex surface when the synthetic polyisoprene latex is stored. .

The conductivity of the synthetic polyisoprene latex is preferably 1.0 mS / cm to 2.0 mS / cm. When the conductivity is less than 1.0 mS / cm, a large amount of aggregates may be generated during emulsification or concentration. Further, when the electrical conductivity exceeds 2.0 mS / cm, foaming becomes severe at the time of solvent removal, foaming is severe at the time of transferring the composition for dip molding or at the time of blending, and defects such as pinholes are left in the glove. There is a case.
The conductivity is a value measured at a measurement temperature of 25 ° C. using a conductivity meter (trade name: SG78-FK2) manufactured by METLER TOLEDO.

  Synthetic polyisoprene latex is usually added in the latex field, and includes additives such as pH adjusters, antifoaming agents, preservatives, crosslinking agents, chelating agents, oxygen scavengers, dispersants, and anti-aging agents. May be blended.

  Examples of the pH adjuster include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide; alkali metal carbonates such as sodium carbonate and potassium carbonate; alkali metal hydrogen carbonates such as sodium bicarbonate; ammonia An organic amine compound such as trimethylamine or triethanolamine; an alkali metal hydroxide or ammonia is preferred.

(Dip molding composition)
The composition for dip molding used in the method for producing a dip molded article of the present invention comprises the synthetic polyisoprene latex, a vulcanizing agent, a vulcanization accelerator, and other components used as necessary.

(Vulcanizing agent)
Examples of the vulcanizing agent used in the dip molding composition include sulfur such as powdered sulfur, sulfur white, precipitated sulfur, colloidal sulfur, surface-treated sulfur and insoluble sulfur; sulfur chloride, sulfur dichloride, morpholine disulfide, alkylphenol, Use sulfur-containing compounds such as disulfide, N, N′-dithio-bis (hexahydro-2H-azepinone-2), phosphorus-containing polysulfide, polymer polysulfide, 2- (4′-morpholinodithio) benzothiazole, and the like. Can do. Of these, sulfur is preferably used. These vulcanizing agents may be used alone or in combination of two or more.

  Although the usage-amount of a vulcanizing agent is not specifically limited, Preferably it is 0.1-10 weight part with respect to 100 weight part of synthetic polyisoprenes, More preferably, it is 0.2-3 weight part. If the amount is too small or too large, the tensile strength of the dip-molded product tends to decrease.

(Vulcanization accelerator)
As the vulcanization accelerator, those usually used in dip molding can be used, for example, diethyldithiocarbamic acid, dibutyldithiocarbamic acid, di-2-ethylhexyldithiocarbamic acid, dicyclohexyldithiocarbamic acid, diphenyldithiocarbamic acid, dibenzyldithiocarbamic acid and the like. Dithiocarbamic acids and their zinc salts; 2-mercaptobenzothiazole, 2-mercaptobenzothiazole zinc, 2-mercaptothiazoline, dibenzothiazyl disulfide, 2- (2,4-dinitrophenylthio) benzothiazole, 2- (N , N-diethylthio-carbylthio) benzothiazole, 2- (2,6-dimethyl-4-morpholinothio) benzothiazole, 2- (4'-morpholino-dithio) benzothiazo And 4-morpholinyl-2-benzothiazyl disulfide, 1,3-bis (2-benzothiazyl mercaptomethyl) urea, etc., but zinc diethyldithiocarbamate, 2-mercaptobenzothiazole, and 2-mercaptobenzothiazole zinc preferable. These vulcanization accelerators may be used alone or in combination of two or more.

  The amount of the vulcanization accelerator used is preferably 0.05 to 5 parts by weight, more preferably 0.1 to 2 parts by weight with respect to 100 parts by weight of the synthetic polyisoprene. If this amount is small, the tensile strength of the dip-molded product may decrease. On the other hand, if this amount is excessive, the elongation just before breakage of the dip-molded product and the tensile strength may decrease.

(Other ingredients)
(Zinc oxide)
The dip molding composition used in the present invention preferably further contains zinc oxide. Although content of zinc oxide is not specifically limited, Preferably it is 0.1-5 weight part with respect to 100 weight part of synthetic polyisoprenes, More preferably, it is 0.2-2 weight part. If this amount is too small, the tensile strength of the dip-molded product tends to decrease. On the other hand, if the amount is too large, the stability of the synthetic polyisoprene particles in the dip-molding composition decreases and coarse aggregates are generated. There is a case.

(Dispersant)
The dip molding composition used in the present invention may contain a dispersant as necessary. Examples of the dispersant include lauric acid, myristic acid, palmitic acid, oleic acid, linolenic acid, and rosin acid. Examples include sodium or potassium salts of fatty acids, alkylbenzene sulfonates such as sodium dodecylbenzenesulfonate, anionic surfactants such as higher alcohol sulfate esters, alkylsulfosuccinates, etc., but sodium dodecylbenzenesulfonate is particularly preferable. . In addition, these surfactants may be used individually by 1 type, and may use 2 or more types together.

  The amount of the dispersant used is preferably 0.01 to 5 parts by weight, more preferably 0.05 to 3 parts by weight with respect to 100 parts by weight of the synthetic polyisoprene. If this amount is small, the blending stability of the dip-forming composition may be reduced, or aggregates may increase during pre-vulcanization. On the other hand, if this amount is excessive, the dip-forming composition tends to foam and pinholes are likely to occur.

(Combination agent)
The dip molding composition used in the present invention further includes an anti-aging agent; a reinforcing agent such as carbon black, silica, and talc; a filler such as calcium carbonate and clay; an ultraviolet absorber; a plasticizer; It can mix | blend as needed.

  Anti-aging agents include 2,6-di-4-methylphenol, 2,6-di-t-butylphenol, butylhydroxyanisole, 2,6-di-t-butyl-α-dimethylamino-p-cresol, Octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, styrenated phenol, 2,2′-methylene-bis (6-α-methyl-benzyl-p-cresol), 4, Butylation of 4'-methylenebis (2,6-di-tert-butylphenol), 2,2'-methylene-bis (4-methyl-6-tert-butylphenol), alkylated bisphenol, p-cresol and dicyclopentadiene Phenol-based antioxidants containing no sulfur atom, such as reaction products; 2,2′-thiobis- (4-methyl-6-tert-butylphenol) ), 4,4′-thiobis- (6-tert-butyl-o-cresol), 2,6-di-tert-butyl-4- (4,6-bis (octylthio) -1,3,5-triazine Thiobisphenol-based antioxidants such as 2-ylamino) phenol; phosphite-based antioxidants such as tris (nonylphenyl) phosphite, diphenylisodecyl phosphite, tetraphenyldipropylene glycol diphosphite; thiodipropionic acid Sulfur ester type antioxidants such as dilauryl; phenyl-α-naphthylamine, phenyl-β-naphthylamine, p- (p-toluenesulfonylamido) -diphenylamine, 4,4 ′-(α, α-dimethylbenzyl) diphenylamine, N , N-Diphenyl-p-phenylenediamine, N-isopropyl-N′-F Amine-based antioxidants such as nyl-p-phenylenediamine and butyraldehyde-aniline condensates; quinoline antioxidants such as 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline; -Hydroquinone anti-aging agents such as di- (t-amyl) hydroquinone; These anti-aging agents may be used alone or in combination of two or more.

  The amount of the anti-aging agent used is preferably 0.05 to 10 parts by weight, more preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the synthetic polyisoprene. If this amount is too small, the synthetic polyisoprene may deteriorate. Moreover, when there is too much this quantity, the tensile strength of a dip molded object may fall.

The method for preparing the dip molding composition is not particularly limited. As the adjustment method, using a dispersing machine such as a ball mill, a kneader, a disper, etc., the latex of synthetic polyisoprene is blended with a vulcanizing agent, a vulcanization accelerator, zinc oxide, the above-mentioned dispersing agent, and if necessary. After preparing an aqueous dispersion of desired compounding ingredients other than latex of synthetic polyisoprene using a method of mixing other compounding agents such as anti-aging agents and the above-mentioned disperser in advance, the aqueous dispersion is synthesized. The method of mixing with the latex of polyisoprene is mentioned. In addition, after the above-mentioned dispersant is mixed in advance with the latex of synthetic polyisoprene, other compounding agents such as a vulcanizing agent, a vulcanization accelerator, and an anti-aging agent can be added.
The pH of the dip molding composition is preferably 7 or more, more preferably in the range of pH 8-12.

  The solid content concentration of the dip molding composition is, for example, in the range of 15 to 65% by weight. The dip molding composition of the present invention is preferably aged (also referred to as pre-vulcanization) before being subjected to dip molding.

  The time for pre-vulcanization is not particularly limited and depends on the pre-vulcanization temperature, but is preferably 1 to 14 days, more preferably from the viewpoint of obtaining a dip-molded body having suitable tensile strength. 1-7 days. The pre-vulcanization temperature is preferably 20 to 40 ° C.

  From the viewpoint of obtaining a dip-molded body having a suitable tensile strength, it is preferably stored at 10 to 25 ° C. until it is subjected to dip molding after pre-vulcanization.

(Dip molded body)
The dip-formed body of the present invention is obtained by dip-molding the above dip-forming composition.

  Dip molding is a method in which a mold is immersed in a dip molding composition, the composition is deposited on the surface of the mold, the mold is then lifted from the composition, and the composition deposited on the mold surface is dried. is there. The mold before dipping in the dip molding composition may be preheated. A coagulant can be used as necessary before the mold is immersed in the dip molding composition or after the mold is pulled up from the dip molding composition. Specific examples of the method of using the coagulant include a method in which a mold before dipping in a dip molding composition is immersed in a coagulant solution to attach the coagulant to the mold (anode coagulation dipping method), a dip molding composition This is a method of immersing the mold in which the material is deposited in a coagulant solution (Teag adhesion dipping method). Among these, the anode coagulation dipping method is preferable in that a dip-formed body with little thickness unevenness can be obtained.

  Specific examples of coagulants include metal halides such as barium chloride, calcium chloride, magnesium chloride, zinc chloride, and aluminum chloride; nitrates such as barium nitrate, calcium nitrate, and zinc nitrate; acetates such as barium acetate, calcium acetate, and zinc acetate Water-soluble polyvalent metal salts such as calcium sulfate, magnesium sulfate, and sulfates such as aluminum sulfate; Of these, calcium salts are preferable, and calcium nitrate is more preferable. These water-soluble polyvalent metal salts can be used alone or in combination of two or more, and are preferably used in the form of an aqueous solution. This aqueous solution may further contain a water-soluble organic solvent such as methyl alcohol and ethyl alcohol, and a nonionic surfactant. The concentration of the coagulant varies depending on the type of the water-soluble polyvalent metal salt, but is preferably 5 to 50% by weight, more preferably 8 to 30% by weight.

  After the mold is lifted from the dip molding composition, for example, the deposit formed on the mold is dried by heating. Drying conditions can be selected as appropriate.

  Subsequently, the deposit formed on the mold is vulcanized by heating. The heating conditions at the time of vulcanization are not particularly limited, but are preferably 60 to 150 ° C, more preferably 100 to 130 ° C, and preferably 10 to 120 minutes. The heating method is not particularly limited, and examples thereof include a method of heating with warm air in an oven and a method of heating by irradiating infrared rays.

  Preferably, the mold is washed with water or warm water to remove water-soluble impurities (eg, excess surfactant, coagulant) before or after heating the mold on which the dip molding composition has been deposited. .

  The dip-formed body after vulcanization is desorbed from the mold. Specific examples of the desorption method include a method of peeling from a mold by hand, a method of peeling by water pressure or compressed air pressure. If the dip-molded product being formed has sufficient strength against desorption, it may be desorbed in the middle step and then the subsequent processing may be continued.

  When the dip-molded body is a glove, in order to prevent the dip-molded bodies from sticking to the contact surface and improve slipping during attachment and detachment, organic fine particles such as talc and calcium carbonate or starch particles are used as gloves. It may be dispersed on the surface, an elastomer layer containing fine particles may be formed on the surface of the glove, or the surface layer of the glove may be chlorinated.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples. The following “%” and “part” are based on weight unless otherwise specified.
In Examples and Comparative Examples, physical properties were measured and evaluated as follows.

Weight average molecular weight of synthetic polyisoprene Synthetic polyisoprene was dissolved in tetrahydrofuran so that the solid concentration would be 0.1% by weight. This solution was subjected to gel permeation chromatography analysis and calculated as a weight average molecular weight in terms of standard polystyrene.

The amount of cis-bond units of the synthetic polyisoprene The synthetic polyisoprene is analyzed by ¹³ C-NMR and expressed as a ratio of cis-bond units to all isoprene units in the synthetic polyisoprene.

Combined volume average polyisoprene latex particle diameter light scattering diffraction particle analyzer (Coulter: LS-230) was used to determined the volume average particle diameter.

Tensile strength and elongation at break of the dip-formed product The tensile strength and elongation at break of the dip-formed product were measured based on ASTM D412. Specifically, the dip-molded film was punched with a dumbbell (Die-C: manufactured by Dumbbell) to prepare a test piece for measuring tensile strength. The test piece was pulled at a tensile speed of 500 mm / min with a Tensilon universal testing machine (RTC-1225A manufactured by Orientec Co., Ltd.), and the tensile strength (unit: MPa) immediately before breaking and the elongation (unit:%) immediately before breaking were measured. The tensile strength and the elongation at break were used, respectively.

Tear Strength of Dip Molded Body The tear strength of the dip molded body was measured based on ASTM D624-00. Specifically, a film-shaped dip-molded body having a film thickness of about 0.2 mm is conditioned for 24 hours or more in a constant temperature and humidity chamber at 23 ° C. and 50% relative humidity, and then dumbbell (Die-C: manufactured by Dumbbell Co. ) To produce a punched specimen. The test piece was pulled with a Tensilon universal testing machine (trade name “RTG-1210”, manufactured by A & D Co., Ltd.) at a pulling speed of 500 mm / min, and the tear strength (unit: N / mm) was measured.

Ratio of amount of polymerization accelerator to amount of active catalyst (I ^* ) (TMEDA / I ^* )
TMEDA / I ^* was determined from I ^* (mmol) obtained by the formula consisting of M / I ^* = Mw / 1000 and the amount of TMEDA added (mmol). Here, M is the amount (g) of isoprene added, and Mw is the weight average molecular weight.

Example 1
(Production of synthetic polyisoprene)
1150 parts of cyclohexane, 100 parts of isoprene, and 0.0022 part of tetramethylethylenediamine (hereinafter sometimes referred to as “TMEDA”) were charged into a dried and nitrogen-substituted autoclave with stirring. The temperature in the autoclave was adjusted to 60 ° C., and while stirring, 0.028 part of a normal butyl lithium 15 wt% hexane catalyst solution was added and reacted for 1 hour. The polymerization reaction rate was 99%. To the obtained polymer solution, 0.0050 part of methanol was added as a polymerization terminator to stop the reaction.

  The 1,4-cis content of the obtained synthetic polyisoprene was 82%, and the weight average molecular weight (Mw) was 1,530,000.

(Production of synthetic polyisoprene latex)
A solution of 1150 parts (b1) of the synthetic polyisoprene obtained by the method for producing synthetic polyisoprene was prepared. Next, 1140 parts of a surfactant aqueous solution (a1) containing 10 parts of sodium rosinate (trade name “Longis N-18”, manufactured by Arakawa Chemical Co., Ltd.) and containing no synthetic polyisoprene was prepared. .

  Then, the total amount of the synthetic polyisoprene solution (b1) and the total amount of the surfactant aqueous solution (a1) are placed in a SUS304 container with stirring and mixed, and then a homogenizer (trade name “Milder MDN-303V”). The product was subjected to an emulsification dispersion treatment by Taiheiyo Kiko Co., Ltd. to obtain an emulsified mixed solution (c1).

  Next, an antifoaming agent (trade name “SM5515” manufactured by Toray Dow Corning Co., Ltd.) is added to 400 ppm with respect to 100 parts of the synthetic polyisoprene, and the emulsified mixed liquid (c1) is added in the solvent removal tank. Then, cyclohexane was distilled off to obtain a synthetic polyisoprene latex (e1). And the aggregate in synthetic polyisoprene latex (e1) was removed using the 200 mesh stainless steel metal-mesh.

  Next, the synthetic polyisoprene latex (e1) after removal of the aggregates was centrifuged at 9000 G and a flow rate of 1200 L / hr by a closed disk type continuous centrifuge (SGR509 manufactured by Alfa Laval). As a result, the synthetic polyisoprene latex of Example 1 having a solid content concentration of 56% by weight was obtained. When the bowl of the centrifuge was opened and the disc was opened, almost no agglomerates were seen.

(Preparation of dip molding composition)
While stirring the synthetic polyisoprene latex, sodium dodecylbenzenesulfonate having a concentration of 10% by weight was added to 100 parts of the synthetic polyisoprene so as to be 1 part in terms of solid content. And while stirring the obtained mixture, 1.5 parts of zinc oxide, 1.5 parts of sulfur and an antioxidant (trade name: Wingstay L) in terms of solid content with respect to 100 parts of synthetic polyisoprene in the mixture. , Goodyear Co.) 3 parts, zinc diethyldithiocarbamate 0.3 part, zinc dibutyldithiocarbamate 0.5 part, mercaptobenzothiazole zinc salt 0.7 parts were added water dispersion of each compounding agent Thereafter, an aqueous potassium hydroxide solution was added to obtain a dip molding composition having a pH adjusted to 10.5.
Thereafter, the obtained dip molding composition was aged in a constant temperature water bath adjusted to 30 ° C. for 48 hours.

(Manufacture of dip-molded bodies)
A commercially available ceramic hand mold (manufactured by Shinko Co., Ltd.) was washed and preheated in an oven at 70 ° C., and then 18 wt% calcium nitrate and 0.05 wt% polyoxyethylene lauryl ether (trade name: Emulgen 109P) The product was immersed in a coagulant solution made of Kao Corporation for 5 seconds and taken out. Next, the hand mold coated with the coagulant was dried in an oven at 70 ° C. for 30 minutes or more.

  Thereafter, the hand mold coated with the coagulant was taken out of the oven and immersed in the dip molding composition for 10 seconds. Then, after air-drying for 10 minutes at room temperature, this hand mold was immersed in 60 degreeC warm water for 5 minutes. Thereafter, the hand mold covered with the film-like synthetic polyisoprene was placed in an oven at 130 ° C. and vulcanized for 30 minutes.

  The hand mold covered with the vulcanized film was cooled to room temperature, then talc was sprayed and then peeled off from the hand mold. Table 1 shows the measurement results of the tensile strength, elongation at break, and tear strength of the obtained dip-molded body.

(Example 2)
In the production of the synthetic polyisoprene, a dip-molded body was produced in the same manner as in Example 1 except that the amount of the normal butyl lithium 15 wt% hexane catalyst solution was changed to 0.030 parts, and evaluation was performed in the same manner. The results are shown in Table 1. In addition, the 1, 4-cis content rate of the obtained synthetic polyisoprene was 81%, and the weight average molecular weight (Mw) was 14,110,000.

Example 3
In the production of synthetic polyisoprene, the amount of TMEDA used was changed to 0.00003 parts, the amount of normal butyllithium 15 wt% hexane catalyst solution was changed to 0.025 parts, methanol was changed to 0.004 parts, and the polymerization initiation temperature was 30. A dip-molded body was produced in the same manner as in Example 1 except that the temperature was changed to ° C., and evaluated in the same manner. The results are shown in Table 1. The obtained synthetic polyisoprene had a 1,4-cis content of 84% and a weight average molecular weight (Mw) of 1,740,000.

(Comparative Example 1)
Example 1 except that the amount of TMEDA used in the production of synthetic polyisoprene was changed to 0.0042 parts, the amount of normal butyl lithium 15 wt% hexane catalyst solution to 0.032 parts, and methanol to 0.006 parts. A dip-molded body was produced in the same manner as described above and evaluated in the same manner. The results are shown in Table 1. The obtained synthetic polyisoprene had a 1,4-cis content of 76% and a weight average molecular weight (Mw) of 13,320,000.

(Comparative Example 2)
Example 1 except that the amount of TMEDA used in the production of synthetic polyisoprene was changed to 0.0077 parts, the amount of normal butyl lithium 15 wt% hexane catalyst solution to 0.025 parts, and methanol to 0.004 parts. A dip-molded body was produced in the same manner as described above and evaluated in the same manner. The results are shown in Table 1. The obtained synthetic polyisoprene had a 1,4-cis content of 72% and a weight average molecular weight (Mw) of 1,740,000.

(Comparative Example 3)
Example 1 except that the amount of TMEDA used in the production of synthetic polyisoprene was changed to 0.0083 parts, the amount of normal butyl lithium 15 wt% hexane catalyst solution to 0.087 parts, and methanol to 0.016 parts. A dip-molded body was produced in the same manner as described above and evaluated in the same manner. The results are shown in Table 1. In addition, the 1, 4-cis content rate of the obtained synthetic polyisoprene was 76%, and the weight average molecular weight (Mw) was 490,000.

(Comparative Example 4)
Example 1 except that the amount of TMEDA used in the production of synthetic polyisoprene was changed to 0.0050 parts, the amount of normal butyllithium 15 wt% hexane catalyst solution to 0.122 parts, and methanol to 0.022 parts. A dip-molded body was produced in the same manner as described above and evaluated in the same manner. The results are shown in Table 1. In addition, the 1, 4-cis content rate of the obtained synthetic polyisoprene was 75%, and the weight average molecular weight (Mw) was 350,000.

(Comparative Example 5)
In the production of synthetic polyisoprene, the amount of TMEDA used was changed to 0.0014 parts, the amount of normal butyllithium 15 wt% hexane catalyst solution was changed to 0.079 parts, methanol was changed to 0.014 parts, and the polymerization initiation temperature was 30. A dip-molded body was produced in the same manner as in Example 1 except that the temperature was changed to ° C., and evaluated in the same manner. The results are shown in Table 1. In addition, 1,4-cis content rate of the obtained synthetic polyisoprene was 79%, and the weight average molecular weight (Mw) was 540,000.

(Comparative Example 6)
Example 1 except that the amount of TMEDA used in the production of synthetic polyisoprene was changed to 0.0030 parts, the amount of normal butyl lithium 15 wt% hexane catalyst solution to 0.068 parts, and methanol to 0.012 parts. A dip-molded body was produced in the same manner as described above and evaluated in the same manner. The results are shown in Table 1. In addition, the 1, 4-cis content rate of the obtained synthetic polyisoprene was 74%, and the weight average molecular weight (Mw) was 630,000.

(Comparative Example 7)
In the production of synthetic polyisoprene, polymerization was carried out without using TMEDA. However, it was difficult to control the polymerization, the molecular weight distribution had two peaks, and the desired synthetic polyisoprene could not be obtained. .

  As shown in Table 1, the ratio of the amount of polymerization accelerator to the amount of active catalyst is in the range of 0.001 to 0.400 (mol / mol), the weight average molecular weight is 600,000 or more, and The tensile strength, tear strength and elongation at break of the glove produced using the method for producing a dip-molded body using a synthetic polyisoprene having a 1,4-cis content of 78% or more showed good values. (Examples 1-3).

  On the other hand, if the ratio of the amount of the polymerization accelerator to the amount of the active catalyst in the synthetic polyisoprene is too high, and if the 1,4-cis content is too low, the obtained gloves are inferior in tensile strength and tear strength (comparison) Examples 1 and 2).

Further, if the weight average molecular weight of the synthetic polyisoprene is too low and the 1,4-cis content is too low, the obtained gloves are inferior in tensile strength and tear strength (Comparative Examples 3 and 4).
Moreover, when the weight average molecular weight of synthetic polyisoprene is too low, it is inferior to the tensile strength and tear strength of the obtained glove (comparative example 5).
Moreover, when the 1, 4-cis content rate of synthetic polyisoprene is too low, it is inferior to the tensile strength and tear strength of the obtained glove (comparative example 6).
In addition, when a synthetic polyisoprene is synthesized, if a polymerization accelerator is not used, it is difficult to control the polymerization and synthetic polyisoprene having a single molecular weight distribution cannot be obtained (Comparative Example 7).

Claims (6)

  The ratio of the amount of polymerization accelerator to the amount of active catalyst is in the range of 0.001 to 0.400 (mol / mol), the weight average molecular weight is 600,000 or more, and the 1,4-cis content is The manufacturing method of the dip molded object using the synthetic polyisoprene whose is 78% or more.   The method for producing a dip-molded product according to claim 1, wherein the amount of the polymerization accelerator is in the range of 0.005 to 0.300 (mol / mol) with respect to the amount of the active catalyst.   The method for producing a dip-formed body according to claim 1 or 2, wherein the 1,4-cis content of the synthetic polyisoprene is 80% or more.   The method for producing a dip-molded article according to any one of claims 1 to 3, wherein the synthetic polyisoprene has a weight average molecular weight of 800,000 or more.   The method for producing a dip-molded article according to any one of claims 1 to 4, wherein a polymerization initiation temperature in producing the synthetic polyisoprene is in a range of 20 to 70 ° C.   A dip-molded product obtained by the method for producing a dip-molded product according to any one of claims 1 to 5.