WO2018088327A1

WO2018088327A1 - Synthetic polyisoprene latex

Info

Publication number: WO2018088327A1
Application number: PCT/JP2017/039738
Authority: WO
Inventors: 小出村　順司; 俊仁相原; 吉隆佐藤
Original assignee: 日本ゼオン株式会社
Priority date: 2016-11-10
Filing date: 2017-11-02
Publication date: 2018-05-17
Also published as: JP7156030B2; JPWO2018088327A1

Abstract

Provided is a synthetic polyisoprene latex containing a tall-rosin surfactant in an amount of 0.3-1.5 parts by weight per 100 parts by weight of the synthetic polyisoprene.

Description

Synthetic polyisoprene latex

The present invention provides a synthetic polyisoprene latex capable of providing a film molded article such as a dip molded article having an odor effectively suppressed, excellent tensile strength and elongation, and having a soft texture, and such The present invention relates to a latex composition using a synthetic polyisoprene latex, a film molded body, and a packaging structure.

Conventionally, a film molded body obtained by molding a latex composition containing natural rubber latex into a film shape is known. For example, as a film molded body, a dip molded body obtained by dip molding a latex composition containing natural rubber latex and used in contact with a human body such as a nipple, a balloon, a glove, a balloon, and a sac is known. It has been. 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 on using synthetic rubber latex instead of natural rubber latex.

For example, Patent Document 1 discloses a synthetic polyisoprene latex obtained using rosinate as a surfactant as a latex used for dip molding. However, the dip-molded article obtained by using the synthetic polyisoprene latex disclosed in Patent Document 1 has a problem that the odor is strong, so that a film-molded article such as a dip-molded article in which the odor is suppressed is given. Synthetic rubber latex is desired.

Special table 2009-531497 gazette

The present invention has been made in view of such a situation, and provides a film molded body such as a dip molded body that is effectively suppressed in odor, has excellent tensile strength and elongation, and has a soft texture. It is an object to provide a synthetic polyisoprene latex that can be used.

As a result of intensive studies to achieve the above object, the present inventors have determined that the amount of tall rosin-based surfactant contained in the synthetic polyisoprene latex is within a specific range, whereby such a synthetic polyisoprene is obtained. It has been found that a film molded body such as a dip molded body obtained by using a latex has an odor effectively suppressed, has excellent tensile strength and elongation, and also has a flexible texture. It came to complete.

That is, according to the present invention, there is provided a synthetic polyisoprene latex containing a tall rosin surfactant in a proportion of 0.3 to 1.5 parts by weight with respect to 100 parts by weight of the synthetic polyisoprene.
In the synthetic polyisoprene latex of the present invention, the synthetic polyisoprene is preferably polymerized by anionic polymerization.
In the synthetic polyisoprene latex of the present invention, the content of the tall rosin surfactant is preferably 0.3 to 1.3 parts by weight with respect to 100 parts by weight of the synthetic polyisoprene.

According to the present invention, there is also provided a method for producing the above synthetic polyisoprene latex, wherein a polymer solution of synthetic polyisoprene polymerized by anionic polymerization is emulsified in water in the presence of a tall rosin surfactant. A method for producing a synthetic polyisoprene latex comprising the steps is provided.
In the method for producing a synthetic polyisoprene latex of the present invention, the polymer solution preferably contains an organic solvent.
The method for producing a synthetic polyisoprene latex of the present invention preferably further includes a step of removing the organic solvent from the emulsion obtained by the step of emulsifying in water.

According to the present invention, there is provided a latex composition containing the above synthetic polyisoprene latex and a vulcanizing agent and / or a vulcanization accelerator.

Moreover, according to this invention, the film forming body which consists of said latex composition is provided.
Further, according to the present invention, at least a part of the first sheet base material and at least a part of the second sheet base material are bonded and laminated by the coating film made of the synthetic polyisoprene latex, There is provided a packaging structure capable of accommodating an object to be packaged between a first sheet substrate and the second sheet substrate.

According to the present invention, it is possible to provide a synthetic polyisoprene latex capable of providing a film molded body such as a dip molded body having a odor effectively suppressed, excellent tensile strength and elongation, and having a soft texture. Can do.

Synthetic polyisoprene latex The synthetic polyisoprene latex of the present invention is a latex of synthetic polyisoprene, and 0.3 to 1.5 parts by weight of a toll rosin surfactant per 100 parts by weight of the synthetic polyisoprene contained in the latex. It contains in the ratio.

The synthetic polyisoprene latex of the present invention contains a tall rosin surfactant in a ratio of 0.3 to 1.5 parts by weight with respect to 100 parts by weight of the synthetic polyisoprene. When the film molded body is obtained, the obtained molded body such as a dip molded body can be effectively suppressed in odor, excellent in tensile strength and elongation, and having a soft texture. Is. The content of the tall rosin surfactant is preferably 0.3 to 1.3 parts by weight, more preferably 0.3 to 1.1 parts by weight. If the content of the tall rosin surfactant is too small, a synthetic polyisoprene aggregate (coagulum) is likely to be generated, resulting in poor mechanical stability as a latex. On the other hand, if the content of the tall rosin surfactant is too large, the odor of the film molded body such as a dip molded body obtained is deteriorated.

The synthetic polyisoprene contained in the synthetic polyisoprene latex of the present invention may be a homopolymer of isoprene or a copolymer of other ethylenically unsaturated monomers copolymerizable with isoprene. There may be. The content of isoprene units in the synthetic polyisoprene is flexible, and it is easy to obtain a film molded body such as a dip molded body having excellent tensile strength. More preferred is 90% by weight or more, still more preferred is 95% by weight or more, and particularly preferred is 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 (meaning “methyl acrylate and / or methyl methacrylate”; The same applies to ethyl (meth) acrylate, etc.), ethylenically unsaturated carboxylic acid ester monomers such as ethyl (meth) acrylate, butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate; Is mentioned. These other ethylenically unsaturated monomers copolymerizable with isoprene may be used singly or in combination.

Synthetic polyisoprene may be polymerized in any manner such as a conventionally known method, coordination polymerization or anionic polymerization. For example, when polymerizing by coordination polymerization, a Ziegler polymerization catalyst is used. A preferred method is to obtain a polymer solution of synthetic polyisoprene by solution polymerization of isoprene and other copolymerizable ethylenically unsaturated monomers used as necessary in an inert polymerization solvent. is there. The Ziegler-based polymerization catalyst is not particularly limited and may be a known one. For example, it can be obtained by reducing titanium tetrachloride with an organoaluminum compound and further treating with various electron donors and electron acceptors. In addition, a catalyst system in which a titanium trichloride composition and an organoaluminum compound are combined, a supported catalyst system in which titanium tetrachloride and various electron donors are brought into contact with magnesium halide, and among these, titanium tetrachloride and A catalyst system using an organoaluminum compound is preferred, and a catalyst system using titanium tetrachloride and trialkylaluminum is particularly preferred.

In the case of polymerization by anionic polymerization, an isoprene and another copolymerizable ethylenically unsaturated monomer used as necessary are used in an inert polymerization solvent using an organic alkali metal catalyst. A method of obtaining a polymer solution of synthetic polyisoprene by solution polymerization is suitable. By using an organic alkali metal catalyst as a polymerization catalyst for anionic polymerization, anionic polymerization can proceed with a high living property, so a synthetic polyisoprene having a high weight average molecular weight can be obtained in a high yield. Therefore, it is preferable. The organic alkali metal catalyst is not particularly limited and known ones can be used. For example, an organic material such as n-butyllithium, sec-butyllithium, t-butyllithium, hexyllithium, phenyllithium, stilbenelithium, etc. Monolithium compounds; organic polylithium such as dilithiomethane, 1,4-dilithiobutane, 1,4-dilithio-2-ethylcyclohexane, 1,3,5-trilithiobenzene, 1,3,5-tris (lithiomethyl) benzene Compounds; organic sodium compounds such as sodium naphthalene; organic power lium compounds such as potassium naphthalene; and the like. Among these, it is preferable to use an organic monolithium compound, and it is more preferable to use n-butyllithium. These organic alkali metal catalysts can be used alone or in combination of two or more.

Examples of the polymerization solvent used for the polymerization include organic solvents such as aromatic hydrocarbon solvents such as benzene, toluene and xylene; alicyclic hydrocarbon solvents such as cyclopentane, cyclopentene, cyclohexane and cyclohexene; And aliphatic hydrocarbon solvents such as butane, pentane, hexane and heptane; halogenated hydrocarbon solvents such as methylene chloride, chloroform and ethylene dichloride; and the like. Of these, aliphatic hydrocarbon solvents are preferred, butane, hexane and pentane are more preferred, hexane is further preferred, and normal hexane is particularly preferred.

There are four types of isoprene units in the synthetic polyisoprene, which are cis bond units, trans bond units, 1,2-vinyl bond units, and 3,4-vinyl bond units, depending on the bond state of isoprene. From the viewpoint of improving the tensile strength of the resulting dip-molded product, the content of cis-bond units in the isoprene units contained in the synthetic polyisoprene is preferably 70% by weight or more, more preferably 90% by weight based on the total isoprene units. % Or more, more preferably 95% by weight or more.

The weight average molecular weight of the synthetic polyisoprene is preferably 10,000 to 5,000,000, more preferably 500,000 to 5,000,000, and still more preferably, in terms of standard polystyrene by gel permeation chromatography analysis. Is 800,000 to 3,000,000. By setting the weight average molecular weight of the synthetic polyisoprene in the above range, the tensile strength of the obtained film molded body in the case of a film molded body such as a dip molded body is improved, and the synthetic polyisoprene latex is easy to produce. Tend.

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.

The synthetic polyisoprene latex of the present invention can be obtained, for example, by the following method using a polymer solution of synthetic polyisoprene obtained by the above coordination polymerization or anionic polymerization. That is, (1) a synthetic polyisoprene polymer solution obtained by coordinating polymerization or anionic polymerization is dissolved or finely dispersed in an organic solvent from a synthetic polyisoprene polymer solution once solidified. A method of producing a synthetic polyisoprene latex by emulsifying a polymer solution of a synthetic polyisoprene in water in the presence of a tall rosin surfactant as an emulsifier, 2) Synthetic polyisoprene latex obtained by directly emulsifying a polymer solution of synthetic polyisoprene obtained by coordination polymerization or anionic polymerization in water in the presence of a tall rosin surfactant as an emulsifier without coagulation. The method of manufacturing is mentioned. Either of the above methods (1) and (2) may be adopted. However, when a synthetic polyisoprene obtained by anionic polymerization is used, the heat history due to coagulation and the like can be reduced. The method (2) is preferred from the viewpoint that a film molded body such as a body can be made more excellent in tensile strength and elongation.

Examples of the organic solvent used in the production method (1) above 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, aliphatic hydrocarbon solvents are preferred, hexane is more preferred, and normal hexane is particularly preferred.

The amount of the organic solvent used is preferably 2,000 parts by weight or less, more preferably 20 to 1,500 parts by weight, still more preferably 500 to 1,500 parts by weight based on 100 parts by weight of the synthetic polyisoprene. is there.

In the present invention, in any of the above methods (1) and (2), a tall rosin surfactant is used as an emulsifier for emulsifying synthetic polyisoprene. By using a tall rosin surfactant, it is possible to suppress foaming when the organic solvent is removed in a later step, and further suppress the generation of aggregates (coagulum) of the resulting synthetic polyisoprene. This can also improve the mechanical stability of the latex. Further, a tall rosin surfactant is used, and the content in the finally obtained synthetic polyisoprene latex is 0.3 to 1.5 parts by weight with respect to 100 parts by weight of the synthetic polyisoprene. By controlling the thickness of the film, it is possible to make the film molded body such as a dip molded body, which has an odor effectively suppressed, and excellent in tensile strength and elongation.

The tall rosin surfactant may be tall rosin obtained by rectification of crude tall oil or a derivative using such tall rosin as a raw material. As a derivative using tall rosin as a raw material, the resin acid constituting tall rosin is a metal. Chlorinated metal salts of tall rosin such as sodium tolrosinate, disproportionated tall rosin disproportionated by using a disproportionation catalyst such as iodine-based catalyst, and resin acid that constitutes disproportionated tall rosin. Examples of the metal salt include metal salts of disproportionated tall rosin such as sodium disproportionated tall rosin acid. Tall rosin includes 33 to 48% by weight of abietic acid, 2 to 8% by weight of neoabietic acid, 10 to 20% by weight of parastolic acid, 3 to 8% by weight of pimaric acid, 4 to 10% by weight of isopimaric acid, and Those containing 15 to 25% by weight of abietic acid are preferred. Further, the disproportionated tall rosin is one in which at least a part of abietic acid, neoabietic acid, and parastrinic acid is converted to dehydroabietic acid by a disproportionation reaction.

The amount of the tall rosin surfactant used as an emulsifier when emulsifying the synthetic polyisoprene is preferably 1 to 15 parts by weight, more preferably 3 to 12 parts by weight, based on 100 parts by weight of the synthetic polyisoprene. More preferably, it is 5 to 10 parts by weight. If the amount of tall rosin surfactant used is too small, emulsification becomes insufficient. On the other hand, if the amount of tall rosin surfactant used is too large, the tall rosin system in the final synthetic polyisoprene latex is obtained. The surfactant content is excessively increased and the odor is deteriorated.

The amount of water used for emulsifying the synthetic polyisoprene is preferably 10 to 200 parts by weight, more preferably 30 to 100 parts by weight, and most preferably 50 parts by weight based on 100 parts by weight of the polymer solution of the synthetic polyisoprene. ~ 70 parts by weight. Examples of the water to be used include hard water, soft water, ion exchange water, distilled water, zeolite water and the like, and soft water, ion exchange water and distilled water are preferable. If the amount of water used is too small, emulsification will be insufficient, while if too much, productivity will decrease.

When emulsifying a polymer solution of synthetic polyisoprene in water in the presence of a tall rosin surfactant as an emulsifier, an emulsifying apparatus that is generally commercially available as an emulsifier or a disperser can be used without any particular limitation. The method for adding the tall rosin surfactant to the synthetic polyisoprene polymer solution is not particularly limited, and may be added in advance to either or both of water and the synthetic polyisoprene polymer solution. During the emulsification operation, the emulsion may be added to the emulsion, or may be added all at once or in divided portions.

Examples of the emulsifier include batch type emulsification 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. Machine: Trade name “TK Pipeline Homomixer” (made by Tokushu Kika Kogyo Co., Ltd.), trade name “Colloid Mill” (made by Shinko Pantech Co., Ltd.), trade name “Slasher” (made by Nippon Coke Industries, Ltd.), trade name “ "Trigonal wet milling machine" (Mitsui Miike Chemical Co., Ltd.), trade name "Cabitron" (Eurotech Co., Ltd.), trade name "Milder" (Pacific Kiko Co., Ltd.), trade name "Fine Flow Mill" (Pacific Kiko Co., Ltd.) Product name “Microfluidizer” (manufactured by Mizuho Kogyo Co., Ltd.), product name “Nanomizer” (manufactured by Nanomizer), product name “APV Gaurin” (Ga High-pressure emulsifiers such as the product name “Membrane Emulsifier” (manufactured by Chilling Industries Co., Ltd.); vibratory emulsifiers such as the product name “Vibro mixer” (manufactured by Chilling Industries Co., Ltd.); An ultrasonic emulsifier such as a trade name “ultrasonic homogenizer” (manufactured by Branson) or the like can be used. The conditions for the emulsification operation by the emulsification apparatus are not particularly limited, and the treatment temperature, treatment time, etc. may be appropriately selected so as to obtain a desired dispersion state.

It is also desirable to remove the organic solvent from the emulsion obtained by emulsifying the polymer solution of synthetic polyisoprene in water in the presence of a tall rosin surfactant as an emulsifier. As a method for removing the organic solvent from the emulsion, a method capable of setting the content of the organic solvent (preferably an aliphatic hydrocarbon solvent) in the emulsion to 500 ppm by weight or less is preferable. Although methods such as atmospheric distillation, steam distillation, and centrifugal separation can be employed, vacuum distillation is preferred from these viewpoints because the organic solvent can be removed appropriately and efficiently.

Additives usually added in the latex field, such as pH adjusters, antifoaming agents, preservatives, chelating agents, oxygen scavengers, dispersants, anti-aging agents, etc. May be. 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.

In addition, after removing the organic solvent, it is desirable to perform a concentration operation by a method such as vacuum distillation, atmospheric distillation, centrifugation, membrane concentration, etc. in order to increase the solid content concentration in the synthetic polyisoprene latex as necessary. In particular, it is preferable to perform centrifugation from the viewpoint that the solid content concentration in the synthetic polyisoprene latex can be increased and the content of the tall rosin surfactant in the synthetic polyisoprene latex can be adjusted.

Centrifugation can be carried out using, for example, a continuous centrifuge or a batch centrifuge, but is preferably carried out using a continuous centrifuge from the viewpoint of excellent productivity of synthetic polyisoprene latex. When the emulsion is concentrated by centrifugation, a synthetic polyisoprene latex can be obtained as a light liquid that is a part of the dispersion after centrifugation. Therefore, according to the centrifugal separation, it is finally obtained by making the residual liquid after removing the synthetic polyisoprene latex as the light liquid contain the desired amount of tall rosin surfactant to be removed. The content of the tall rosin surfactant in the synthetic polyisoprene latex can be appropriately adjusted.

The conditions for the centrifugation are not particularly limited, and the content of the tall rosin surfactant in the finally obtained synthetic polyisoprene latex is 0 with respect to 100 parts by weight of the synthetic polyisoprene contained in the latex. The conditions may be in the range of 3 to 1.5 parts by weight. For example, the solid content concentration of the emulsion used for centrifugation (emulsion before centrifugation) is preferably 5 to 11% by weight, more preferably 7 to 10.7% by weight, and still more preferably 9 to 10.5% by weight. %. By setting the solid content concentration of the emulsion before centrifugation to the above range, aggregation of synthetic polyisoprene, etc. can be prevented during centrifugation, thereby improving the mechanical stability of the emulsion. The amount of the tall rosin surfactant in the finally obtained synthetic polyisoprene latex can be appropriately adjusted to a desired amount, which is preferable. In addition, when performing centrifugation, you may use the emulsion from which the organic solvent was removed as it is, or after adjusting solid content concentration.

Further, as a condition for performing the centrifugation, when a continuous centrifuge is used, the centrifugal acceleration is preferably 5,000 to 11,000 G, more preferably 6,000 to 10,000 G, and still more preferably. Is 7,000 to 9,500 G, and the feed amount of the emulsion to the continuous centrifuge is preferably 0.5 to 1.5 m ³ / hour, more preferably 0.7 to 1.45 m ³ / hour. More preferably, it is 0.9 to 1.4 m ³ / hour, and the residence time in the continuous centrifuge is preferably 2.0 to 4.0 minutes, more preferably 2.5 to 3.0 minutes, The back pressure (gauge pressure) of the centrifuge is preferably 0.03 to 1.6 MPa. By setting the centrifugation conditions as described above, aggregation of synthetic polyisoprene and the like during centrifugation can be prevented, thereby improving the mechanical stability of the emulsion and finally obtaining it. The amount of the tall rosin surfactant in the synthetic polyisoprene latex to be obtained can be appropriately adjusted to a desired amount, which is preferable.

In the above, an example of the conditions for obtaining the synthetic polyisoprene latex of the present invention containing the tall rosin surfactant in a proportion of 0.3 to 1.5 parts by weight with respect to 100 parts by weight of the synthetic polyisoprene. However, it is not particularly limited to such conditions. In particular, the amount of the tall rosin surfactant in the synthetic polyisoprene latex of the present invention is mainly used when the polymer solution of the synthetic polyisoprene is emulsified in water. The tall rosin system in the synthetic polyisoprene latex finally obtained can be adjusted by appropriately combining the solid content concentration of the previous emulsion and the conditions for centrifugation, etc. Each condition may be adjusted as appropriate so that the amount of the surfactant is within the predetermined range of the present invention. For example, when the amount of tall rosin surfactant used when emulsifying a polymer solution of synthetic polyisoprene in water is relatively small, the amount of tall rosin surfactant removed by centrifugation is relatively low. Therefore, it is considered that it may be possible to increase the centrifugal acceleration in the continuous centrifuge beyond the above range, or to increase the feed amount of the emulsion to the continuous centrifuge.

Latex Composition The latex composition of the present invention is obtained by blending the above-described synthetic polyisoprene latex of the present invention with a vulcanizing agent and / or a vulcanization accelerator.

Examples of the vulcanizing agent include sulfur such as powdered sulfur, sulfur white, precipitated sulfur, colloidal sulfur, surface-treated sulfur, insoluble sulfur, etc .; sulfur chloride, sulfur dichloride, morpholine disulfide, alkylphenol disulfide, N, N'- Examples thereof include sulfur-containing compounds such as dithio-bis (hexahydro-2H-azepinone-2), phosphorus-containing polysulfides, polymer polysulfides, and 2- (4′-morpholinodithio) benzothiazole. Among these, sulfur can be preferably used. Vulcanizing agents can be used alone or in combination of two or more.

The content of the vulcanizing agent is not particularly limited, but is preferably 0.1 to 10 parts by weight, more preferably 0.2 to 3 parts by weight with respect to 100 parts by weight of the synthetic polyisoprene contained in the latex. . By setting the content of the vulcanizing agent in the above range, the tensile strength of a film molded body such as a dip molded body obtained can be further increased.

As the vulcanization accelerator, those usually used in a method for obtaining a film molded product such as dip molding can be used. For example, diethyldithiocarbamic acid, dibutyldithiocarbamic acid, di-2-ethylhexyldithiocarbamic acid, dicyclohexyldithiocarbamic acid, diphenyldithiocarbamine Acids, dithiocarbamic acids such as dibenzyldithiocarbamic acid and zinc salts thereof; 2-mercaptobenzothiazole, 2-mercaptobenzothiazole zinc, 2-mercaptothiazoline, dibenzothiazyl disulfide, 2- (2,4-dinitrophenylthio) ) Benzothiazole, 2- (N, N-diethylthiocarbaylthio) benzothiazole, 2- (2,6-dimethyl-4-morpholinothio) benzothiazole, 2- (4′-mol) Rino-dithio) benzothiazole, 4-morpholinyl-2-benzothiazyl disulfide, 1,3-bis (2-benzothiazyl-mercaptomethyl) urea, and the like, but include zinc diethyldithiocarbamate, zinc dibutyldithiocarbamate, 2- Mercaptobenzothiazole zinc is preferred. A vulcanization accelerator can be used individually by 1 type or in combination of 2 or more types.

The content of the vulcanization accelerator 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 contained in the latex. By making content of a vulcanization accelerator into the said range, the tensile strength of film molded objects, such as a dip molded object obtained, can be raised more.

Further, the latex composition of the present invention preferably further contains an anti-aging agent. Antiaging 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-t-butylphenol), 2,2'-methylene-bis (4-methyl-6-t-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- Thiobisphenol-based antioxidants such as triazin-2-ylamino) phenol; Phosphite-based antioxidants such as tris (nonylphenyl) phosphite, diphenylisodecyl phosphite, tetraphenyldipropylene glycol diphosphite; thiodipropion Sulfur ester type antioxidants such as dilauryl acid; phenyl-α-naphthylamine, phenyl-β-naphthylamine, p- (p-toluenesulfonylamido) -diphenylamine, 4,4 ′-(α, α-dimethylbenzyl) diphenylamine, N, N-diphenyl-p-phenylenediamine, N-isopropyl-N'- Amine-based antioxidants such as phenyl-p-phenylenediamine and butyraldehyde-aniline condensates; quinoline antioxidants such as 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline; 2,5 And hydroquinone anti-aging agents such as di- (t-amyl) hydroquinone. These anti-aging agents can be used alone or in combination of two or more. Among these, a phenolic anti-aging agent is preferable and a phenolic anti-aging agent containing no sulfur atom is more preferable because it has a small effect of inhibiting the vulcanization reaction and a large antioxidant effect.

The content of the antioxidant is preferably 0.1 to 10 parts by weight, more preferably 1 to 7 parts by weight, still more preferably 3 to 6 parts by weight with respect to 100 parts by weight of the synthetic polyisoprene contained in the latex. It is. By setting the content of the antioxidant to be in this range, it is preferable because a sufficient antioxidant effect can be obtained without inhibiting the vulcanization reaction during vulcanization.

Moreover, it is preferable that the latex composition of this invention contains a zinc oxide further.
The content of zinc oxide is not particularly limited, but is preferably 0.1 to 5 parts by weight, more preferably 0.2 to 2 parts by weight with respect to 100 parts by weight of the synthetic polyisoprene contained in the latex. By setting the content of zinc oxide in the above range, the tensile strength of a film molded body such as a dip molded body can be further increased while improving the emulsion stability.

The latex composition of the present invention further contains a compounding agent such as a dispersant; a reinforcing agent such as carbon black, silica, or talc; a filler such as calcium carbonate or clay; an ultraviolet absorber; a plasticizer; Can be blended.

The method for preparing the latex composition of the present invention is not particularly limited. For example, using a dispersing machine such as a ball mill, a kneader, or a disper, the synthetic polyisoprene latex is added to a vulcanizing agent and / or a vulcanization accelerator, and After preparing an aqueous dispersion of compounding ingredients other than synthetic polyisoprene latex using a method of mixing various kinds of compounding agents such as anti-aging agents blended as necessary and such a disperser, the aqueous dispersion Examples thereof include a method of mixing the liquid with a synthetic polyisoprene latex.

The latex composition of the present invention preferably has a pH of 7 or more, more preferably in the range of 7 to 13, and still more preferably in the range of 8 to 12. The solid content concentration of the latex composition is preferably in the range of 15 to 65% by weight.

The latex composition of the present invention is preferably aged (pre-crosslinked) before being subjected to molding such as dip molding from the viewpoint of further improving the mechanical properties of a film molded body such as a dip molding obtained. The pre-crosslinking time is not particularly limited and depends on the pre-crosslinking temperature, but is preferably 1 to 14 days, and more preferably 1 to 7 days. The pre-crosslinking temperature is preferably 20 to 40 ° C.
After pre-crosslinking, it is preferably stored at a temperature of 10 to 30 ° C. until it is subjected to molding such as dip molding. When stored at a high temperature, the tensile strength of the obtained film molded body such as a dip molded body may be lowered.

Film molded body The film molded body of the present invention is a film-shaped molded body made of the latex composition of the present invention. The film thickness of the film molded body of the present invention is preferably 0.03 to 0.50 mm, more preferably 0.05 to 0.40 mm, and particularly preferably 0.08 to 0.30 mm.

The film molded body of the present invention is not particularly limited, but is preferably a dip molded body obtained by dip molding the latex composition of the present invention. Dip molding is a method in which a mold is immersed in a latex composition, the composition is deposited on the surface of the mold, the mold is then lifted from the composition, and then the composition deposited on the mold surface is dried. is there. The mold before being immersed in the latex composition may be preheated. Further, a coagulant can be used as necessary before the mold is immersed in the latex composition or after the mold is pulled up from the latex composition.

Specific examples of the method of using the coagulant include a method in which the mold before dipping in the latex composition is immersed in a solution of the coagulant to attach the coagulant to the mold (anode coagulation dipping method), and the latex composition is deposited. There is a method of immersing the formed mold in a coagulant solution (Teag adhesion dipping method), etc., but the anode adhesion dipping method is preferable in that a dip-formed product 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; acetic acid such as barium acetate, calcium acetate, and zinc acetate. Salts; 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.

The coagulant is preferably used in the form of an aqueous solution. This aqueous solution may further contain a water-soluble organic solvent such as methanol or ethanol, or 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 10 to 30% by weight.

After lifting the mold from the latex composition, the deposit formed on the mold is usually dried by heating. What is necessary is just to select drying conditions suitably.

It is then heated to crosslink the deposit formed on the mold.
The heating conditions at the time of crosslinking 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 there are a method of heating with warm air in an oven, a method of heating by irradiating infrared rays, and the like.

Alternatively, the mold may be washed with water or warm water to remove water-soluble impurities (for example, excess surfactant or coagulant) before or after heating the mold on which the latex composition is deposited. preferable. The hot water used is preferably 40 ° C. to 80 ° C., more preferably 50 ° C. to 70 ° C.

The dip-formed body after crosslinking is detached 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, and the like. If the dip-formed product in the middle of crosslinking has sufficient strength against desorption, it may be desorbed in the middle of crosslinking, and then the subsequent crosslinking may be continued.

Since the film molded body of the present invention and the dip molded body which is one embodiment thereof are obtained using the latex of the present invention described above, they have excellent tensile strength and elongation, and are particularly suitable as, for example, gloves. Can be used. When the film molded body is a glove, in order to prevent adhesion between the contact surfaces of the film molded bodies and improve slippage during attachment and detachment, organic fine particles such as inorganic fine particles such as talc and calcium carbonate or starch particles are gloved. 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.

In addition to the above gloves, the membrane molded article of the present invention and the dip molded article as one aspect thereof are medical supplies such as nipples for baby bottles, syringes, tubes, water pillows, balloon sacks, catheters, condoms, etc. It can also be used for toys such as dolls and balls; industrial articles such as pressure forming bags and gas storage bags; finger sack and the like.

Packaging structure The packaging structure of the present invention is formed by adhering and laminating the first sheet base material and the second sheet base material coated with the above-described synthetic polyisoprene latex of the present invention, and can accommodate an object to be packaged. The structure is shown. Specifically, in the packaging structure of the present invention, the first sheet base material and the second sheet base material face each other so that the surfaces to which the synthetic polyisoprene latex is applied (latex application surface) are opposed to each other. The first sheet base material and the second sheet base material and the second sheet base material are pressed together with the latex coated surfaces of the first sheet base material and the second sheet base material in contact with each other as necessary. The sheet base material adheres to each other, and thus has a structure capable of packaging an object to be packaged. Although it does not specifically limit as a to-be-packaged object, For example, the various to-be-packaged goods which it is desired to sterilize like medical goods, such as a bandage, are mentioned. Although it does not specifically limit as a 1st sheet base material and a 2nd sheet base material, For example, paper materials, such as glassine paper, a high density polyethylene nonwoven fabric, a polyolefin film, a polyester film, etc. are mentioned, Among these, Paper materials are preferred, and glassine paper is particularly preferred from the viewpoints of excellent handleability (a point of moderate bending ease) and low cost.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples. In the following, “part” is based on weight unless otherwise specified. Tests or evaluation methods for physical properties and characteristics are as follows.

Weight average molecular weight (Mw)
Diluted with tetrahydrofuran so that the solid content concentration of the synthetic polyisoprene contained in the polymer solution is 0.1% by weight, this solution was subjected to gel permeation chromatography analysis, and the weight in terms of standard polystyrene Average molecular weight (Mw) was calculated.

A 2 g sample was precisely weighed (weight: X2) in a solid content aluminum dish (weight: X1) and dried in a hot air drier at 105 ° C. for 2 hours. Subsequently, after cooling in a desiccator, the weight of the aluminum pan was measured (weight: X3), and the solid content concentration was calculated according to the following formula.
Solid content concentration (% by weight) = (X3−X1) × 100 / X2

Content ratio of sodium disproportionated tall rosinate and sodium disproportionated gum rosinate 2 ml of water was added to 0.1 g of polyisoprene latex and diluted to 10 ml with acetonitrile. The obtained liquid was shaken well to solidify the rubber component. Thereafter, the aqueous layer was filtered through a 0.2 μm disk filter. This liquid was analyzed by high performance liquid chromatography, and the content ratio (unit: parts by weight) of disproportionated sodium sodium disproportionate and disproportionate sodium sodium disproportionate to 100 parts of synthetic polyisoprene was calculated.

About the film-shaped dip molded object whose odor film thickness is about 0.2 mm, the odor determination was performed on the following references | standards.
A: There is no odor at all.
B: Although it feels a slight odor, it is not uncomfortable.
C: The odor is clearly felt.
D: Feels a strong odor and is uncomfortable.

Measurement of carbon disulfide content and carbonyl sulfide content by measuring with a triple quadrupole gas chromatograph mass spectrometer on a dip-molded film with a carbon disulfide content and carbonyl sulfide content of about 0.2 mm. Went. Specifically, the peak area corresponding to carbon disulfide (Area) detected by triple quadrupole gas chromatography mass spectrometry and the peak area corresponding to carbonyl sulfide (Area) are converted per 1 g of sample. The obtained values were determined as the amount of carbon disulfide and the amount of carbonyl sulfide (unit: Area / g). Since carbon disulfide and carbonyl sulfide cause odor, it can be judged that the odor is stronger as the amount of carbon disulfide and the amount of carbonyl sulfide (unit: Area / g) are larger.

Based on the tensile strength, elongation at break (tensile elongation), and 500% tensile stress ASTM D412 of the dip-molded product, a film-shaped dip-molded product having a film thickness of about 0.2 mm was converted into a dumbbell (trade name “Super Dumbbell” : SDMK-100C) ”(manufactured by Dumbbell) to produce a test piece for measuring tensile strength. The test piece was pulled with a Tensilon universal tester (trade name “RTG-1210”, manufactured by Orientec Co., Ltd.) at a tensile speed of 500 mm / min, tensile strength immediately before break (unit: MPa), elongation just before break (unit:%) ) And the tensile stress (unit: MPa) when the elongation is 500%. The higher the tensile strength and the elongation at break, the better. Moreover, the smaller the tensile stress at 500%, the better the dip-formed body becomes excellent in flexibility.

Example 1
(Production of polymer solution of synthetic polyisoprene (a-1))
1150 parts of normal hexane and 100 parts of isoprene were charged into an autoclave with stirring which was dried and purged with nitrogen. Next, the temperature inside the autoclave was set to 60 ° C., 0.006 part of normal butyl lithium was added and reacted for 2 hours while stirring, 0.05 part of methanol was added as a polymerization terminator, the reaction was stopped, A normal hexane solution of synthetic polyisoprene (a-1) was obtained. The weight average molecular weight of the synthetic polyisoprene (a-1) in the normal hexane solution was 3,520,000.

(Production of synthetic polyisoprene latex (A-1))
Next, 1250 parts of a normal hexane solution of the resulting synthetic polyisoprene (a-1) was heated to 60 ° C., and 1250 parts of an aqueous solution of disproportionated sodium sodium disproportionate having a concentration of 1.0 wt% heated to 60 ° C., The flow rate was adjusted to 1: 1 by weight and mixed using a line mixer. Subsequently, an emulsion was obtained using a homogenizer.

Further, the emulsion obtained above was heated to 80 ° C. under reduced pressure to distill off normal hexane, whereby an aqueous dispersion of synthetic polyisoprene (a-1) was obtained. After adjusting the obtained aqueous dispersion to a solid content concentration of 10.3% by weight, the aqueous dispersion with the adjusted solid content concentration was subjected to a sealed disk type continuous centrifuge (product name “SGR509”, manufactured by Alfa Laval). ) Is continuously fed at a flow rate of 1.0 m ³ / hour (converted to a residence time of 3.0 minutes), centrifuged at a centrifugal acceleration of 9,000 G, and a synthetic polyisoprene latex ( A-1) was obtained. The content of disproportionated sodium tolrosinate in the obtained synthetic polyisoprene latex (A-1) was measured and found to be 0.8 parts with respect to 100 parts of synthetic polyisoprene.

(Preparation of latex composition)
While stirring the synthetic polyisoprene latex (A-1) obtained above, the blending amount in terms of solid content is 1 part with respect to 100 parts of the synthetic polyisoprene latex (A-1). So that 10% by weight of sodium dodecylbenzenesulfonate was added. Then, while stirring the obtained mixture, 1.5 parts of zinc oxide, 1.5 parts of sulfur, an anti-aging agent (trade name “Wingstay”) in terms of solid content with respect to 100 parts of synthetic polyisoprene in the mixture. L ", manufactured by Goodyear) 2 parts, zinc diethyldithiocarbamate 0.3 part, zinc dibutyldithiocarbamate 0.5 part, and mercaptobenzothiazole zinc salt 0.7 parts. After the addition, an aqueous potassium hydroxide solution was added to obtain a latex composition having a pH adjusted to 10.5. Thereafter, the obtained latex composition was aged in a constant temperature water bath adjusted to 30 ° C. for 48 hours.

(Manufacture of dip-molded bodies)
A glass mold (diameter of about 5 cm, crumb length of about 15 cm) with a ground surface was washed, preheated in an oven at 70 ° C., and then 18 wt% calcium nitrate and 0.05 wt% polyoxyethylene. It was immersed in a coagulant aqueous solution containing lauryl ether (trade name “Emulgen 109P”, manufactured by Kao Corporation) for 5 seconds and taken out. Next, the glass mold coated with the coagulant was dried in an oven at 70 ° C. for 30 minutes or more.

Thereafter, the glass mold coated with the coagulant is taken out of the oven, the latex composition obtained above is adjusted to 25 ° C., immersed in this latex composition for 10 seconds and then taken out, and then at room temperature for 60 minutes. By air drying, a glass mold covered with a film was obtained. The glass mold covered with the film was immersed in warm water at 60 ° C. for 2 minutes, and then air-dried at room temperature for 30 minutes. Thereafter, the glass mold covered with the film is placed in an oven at 120 ° C., vulcanized for 20 minutes, cooled to room temperature, sprayed with talc, and then peeled off from the glass mold to dip-molded body. Got. And according to the said method, each measurement of an odor, the amount of carbon disulfide, the amount of carbonyl sulfide, tensile strength, elongation at break, and 500% tensile stress was performed using the obtained dip molding. The results are shown in Table 1.

Example 2
(Production of synthetic polyisoprene latex (A-2))
The flow rate when the aqueous dispersion adjusted in solid content is continuously fed to a continuous centrifuge is changed from 1.0 m ³ / hour to 1.3 m ³ / hour (2.3 minutes when converted to residence time) Synthetic polyisoprene latex (A-2) was obtained in the same manner as in Example 1 except that the conditions were changed. The content of disproportionated sodium tolrosinate in the obtained synthetic polyisoprene latex (A-2) was measured and found to be 1.3 parts with respect to 100 parts of synthetic polyisoprene.

(Preparation of latex composition, production of dip-molded body)
Then, except that the synthetic polyisoprene latex (A-2) obtained above was used, a latex composition was prepared and a dip-formed product was produced in the same manner as in Example 1, and evaluated in the same manner. went. The results are shown in Table 1.

Example 3
(Production of synthetic polyisoprene latex (A-3))
A normal hexane solution of synthetic polyisoprene (a-1) obtained in the same manner as in Production Example 1 was coagulated in methanol, and then the obtained coagulated product was vacuum-dried at 70 ° C. for 12 hours to obtain a solid state. The synthetic polyisoprene (a-1) was obtained. Next, the obtained solid synthetic polyisoprene (a-1) was redissolved in normal hexane to obtain a normal hexane solution of synthetic polyisoprene (a-1) having a solid content concentration of 8% by weight. A synthetic polyisoprene (a-1) was prepared in the same manner as in Example 2 except that a normal hexane solution was used, and an emulsion was prepared, normal hexane was distilled off and centrifuged. Latex (A-3) was obtained. When the content of disproportionated sodium tolrosinate in the obtained synthetic polyisoprene latex (A-3) was measured, it was 1.3 parts with respect to 100 parts of synthetic polyisoprene.

(Preparation of latex composition, production of dip-molded body)
Then, except that the synthetic polyisoprene latex (A-3) obtained above was used, a latex composition was prepared and a dip-formed product was produced in the same manner as in Example 1, and evaluated in the same manner. went. The results are shown in Table 1.

Example 4
(Production of polymer solution of synthetic polyisoprene (a-2))
1150 parts of normal hexane and 100 parts of isoprene were charged into an autoclave with stirring which was dried and purged with nitrogen. Next, the temperature in the autoclave was adjusted to 30 ° C., 0.03 part of titanium tetrachloride, 0.03 part of triisobutylaluminum, and 0.005 part of normal butyl ether were added with stirring and reacted for 2 hours. As a result, 0.05 part of methanol was added to stop the reaction to obtain a normal hexane solution of synthetic polyisoprene (a-2). The weight average molecular weight of the synthetic polyisoprene (a-2) in the normal hexane solution was 1,860,000.

(Production of synthetic polyisoprene latex (A-4))
The normal hexane solution of the synthetic polyisoprene (a-2) obtained above was coagulated in methanol, and then the obtained coagulated product was vacuum dried at 70 ° C. for 12 hours to obtain a solid synthetic polyisoprene. (A-2) was obtained. Next, the obtained solid synthetic polyisoprene (a-2) was redissolved in normal hexane to obtain a normal hexane solution of synthetic polyisoprene (a-2) having a solid concentration of 8% by weight. Then, preparation of the emulsion, distillation of normal hexane, and centrifugation are performed in the same manner as in Example 2, except that the normal hexane solution of synthetic polyisoprene (a-2) obtained by re-dissolution is used. Thus, a synthetic polyisoprene latex (A-4) was obtained. The content of sodium disproportionated tolrosinate in the obtained synthetic polyisoprene latex (A-4) was measured and found to be 1.3 parts with respect to 100 parts of synthetic polyisoprene.

(Preparation of latex composition, production of dip-molded body)
Then, except that the synthetic polyisoprene latex (A-4) obtained above was used, the latex composition was prepared and the dip-formed product was produced in the same manner as in Example 1, and the evaluation was made in the same manner. went. The results are shown in Table 1.

Comparative Example 1
(Production of synthetic polyisoprene latex (A-5))
The solid content concentration of the aqueous dispersion of synthetic polyisoprene (a-1) used for centrifugation is changed to 11.5% by weight, and the flow rate when continuously fed to a continuous centrifuge is 1.0 m. Synthetic polyisoprene latex (A-5) was obtained in the same manner as in Example 1 except that it was changed from ³ / hour to 1.6 m ³ / hour (conditions of 1.9 minutes in terms of residence time). The content of disproportionated sodium sodium toluronate in the obtained synthetic polyisoprene latex (A-5) was measured and found to be 1.7 parts with respect to 100 parts of synthetic polyisoprene.

(Preparation of latex composition, production of dip-molded body)
Then, except that the synthetic polyisoprene latex (A-5) obtained above was used, a latex composition was prepared and a dip-formed product was produced in the same manner as in Example 1, and evaluation was performed in the same manner. went. The results are shown in Table 1.

Comparative Example 2
(Production of synthetic polyisoprene latex (A-6))
The solid content concentration of the aqueous dispersion of synthetic polyisoprene (a-1) used for centrifugation is changed to 11.5% by weight, and the flow rate when continuously fed to a continuous centrifuge is 1.0 m. Synthetic polyisoprene latex (A-6) was obtained in the same manner as in Example 1 except that ³ / hour to 1.3 m ³ / hour and the centrifugal acceleration was set to 12,000 G. The content of disproportionated sodium sodium toluronate in the obtained synthetic polyisoprene latex (A-6) was measured and found to be 0.2 parts with respect to 100 parts of synthetic polyisoprene.

A latex composition was prepared in the same manner as in Example 1 except that the synthetic polyisoprene latex (A-6) obtained above was used. As a result, the synthetic polyisoprene latex (A-6) was prepared. The agglomeration was remarkable and coagulated, so that a latex composition could not be prepared, and furthermore, a dip-formed product could not be produced.

Comparative Example 3
(Production of synthetic polyisoprene latex (A-7))
As an emulsifier, a synthetic polysiloxane was prepared in the same manner as in Example 2 except that an aqueous solution of disproportionated sodium sodium rosinate (trade name “Longis K-25”, manufactured by Arakawa Chemical Industries, Ltd.) having a concentration of 1.0% by weight was used. An isoprene latex (A-7) was obtained. The content of disproportionated sodium sodium rosinate in the obtained synthetic polyisoprene latex (A-7) was measured and found to be 1.3 parts with respect to 100 parts of synthetic polyisoprene.

(Preparation of latex composition, production of dip-molded body)
Then, except that the synthetic polyisoprene latex (A-7) obtained above was used, a latex composition was prepared and a dip-formed product was produced in the same manner as in Example 1, and evaluated in the same manner. went. The results are shown in Table 1.

(* 1) Content based on 100 parts of synthetic polyisoprene

As shown in Table 1, a dip as an embodiment of a film molded body obtained by using a synthetic polyisoprene latex containing a tall rosin surfactant in a ratio of 0.3 to 1.5 parts with respect to 100 parts of the synthetic polyisoprene. The molded body was effectively suppressed in odor, had excellent tensile strength and elongation, and had a soft texture (500% tensile stress was low) (Examples 1 to 4).

On the other hand, if the amount of the tall rosin surfactant in the synthetic polyisoprene latex is too large, the resulting dip-molded product has a strong odor and inferior tensile strength (Comparative Example 1).
Further, when the amount of the tall rosin surfactant in the synthetic polyisoprene latex is too small, the aggregation of the synthetic polyisoprene becomes remarkable and the stability as a latex is extremely poor (Comparative Example 2).
Furthermore, when disproportionated sodium sodium rosin was used as an emulsifier, the resulting dip-molded product resulted in a strong odor (Comparative Example 3).

Claims

Synthetic polyisoprene latex containing tall rosin surfactant in a proportion of 0.3 to 1.5 parts by weight with respect to 100 parts by weight of synthetic polyisoprene.
The synthetic polyisoprene latex according to claim 1, wherein the synthetic polyisoprene is polymerized by anionic polymerization.
The synthetic polyisoprene latex according to claim 1 or 2, wherein the content of the tall rosin surfactant is 0.3 to 1.3 parts by weight with respect to 100 parts by weight of the synthetic polyisoprene.
A method for producing the synthetic polyisoprene latex according to any one of claims 1 to 3,
A method for producing a synthetic polyisoprene latex comprising a step of emulsifying a polymer solution of synthetic polyisoprene polymerized by anionic polymerization in water in the presence of a tall rosin surfactant.
The method for producing a synthetic polyisoprene latex according to claim 4, wherein the polymer solution contains an organic solvent.
The method for producing a synthetic polyisoprene latex according to claim 5, further comprising a step of removing the organic solvent from an emulsion obtained by the step of emulsifying in water.
A latex composition comprising the synthetic polyisoprene latex according to any one of claims 1 to 3, and a vulcanizing agent and / or a vulcanization accelerator.
A film molded body comprising the latex composition according to claim 7.
At least a part of the first sheet base material and at least a part of the second sheet base material are adhesively laminated by a coating film made of the synthetic polyisoprene latex according to any one of claims 1 to 3, A packaging structure capable of accommodating an object to be packaged between the first sheet base material and the second sheet base material.