Halogenated butyl rubber dispersion and production method for halogenated butyl rubber molded body using said dispersion

Abstract

Provided is a method that makes it possible to prepare a higher strength butyl rubber molded body when preparing a butyl rubber molded body (specifically, a butyl rubber glove) by means of dip molding. More specifically, the following method is provided. This production method for a halogenated butyl rubber molded body involves (γ) immersing, in an aqueous dispersion for immersion containing halogenated butyl rubber, water, a stabilizer, sulfur, zinc oxide, and a vulcanization accelerator, a mold having a coagulant adhered to a surface thereof, and removing the mold from said dispersion, and (δ) obtaining a halogenated butyl rubber molded body by drying and vulcanizing the aqueous dispersion for immersion adhered to the surface of the mold.

Description

Halogenated butyl rubber dispersion and method for producing halogenated butyl rubber molded article using the dispersion

[0001] The present disclosure relates to a halogenated butyl rubber dispersion, a method for producing a halogenated butyl rubber molded article using the dispersion, and the like.

[0002] Butyl rubber is a copolymer composed of isobutylene and a small amount of isoprene, and can be prepared by polymerizing isobutylene and isoprene (for example, addition polymerization). Butyl rubber is classified as a rubber having an unsaturated hydrocarbon in its main chain, like natural rubber (NR), isoprene rubber (IR), styrene-butadiene rubber (SBR), and butadiene rubber (BR). The abbreviation for butyl rubber is IIR.

[0003] Butyl rubber is widely used, for example, as a raw material rubber for automobile tires. In addition, it is also used as a material for rubber gloves, for example. Butyl rubber is excellent in heat resistance, chemical resistance and the like, and is excellent as a material for protective gloves. Demand for butyl rubber gloves is high in work sites where people handle chemicals harmful to the human body.

[0004] When preparing a butyl rubber molded article such as a butyl rubber glove, a method of preparing a butyl rubber dispersion and performing dip molding using the dispersion is known. Studies have been repeatedly conducted on the preparation of the dispersion for dip molding and dip molding of gloves using the dispersion (for example, Patent Documents 1 to 3).

[0005] Japanese Unexamined Patent Application Publication No. 2006-219609 Chinese Patent Application Publication No. 115975219 Specification Chinese Patent Application Publication No. 109503963 Specification

[0006] Generally, butyl rubber gloves have low strength, and higher strength is required.

[0007] Accordingly, the present inventors have conducted studies to provide a method capable of preparing a butyl rubber molded article with higher strength when preparing a butyl rubber molded article (particularly a butyl rubber glove) by dip molding.

[0008] This disclosure includes, for example, the following subjects: 1. A method for producing a halogenated butyl rubber molded article, comprising: (γ) immersing a mold with a coagulant attached to its surface in an aqueous dispersion for immersion containing halogenated butyl rubber, water, a stabilizer, sulfur, zinc oxide, and a vulcanization accelerator, and then removing it; and (δ) drying and vulcanizing the aqueous dispersion for immersion attached to the surface of the mold to obtain a halogenated butyl rubber molded article. 1a. The method according to 1, further comprising immersing the mold with the aqueous dispersion for immersion attached to it in water (preferably after standing as necessary) between (γ) and (δ). 2. The method according to 1 or 1a, further comprising (β) immersing the mold in an aqueous solution of a coagulant and then drying it to obtain a mold with a coagulant attached to its surface. 3. (α): The method according to item 1, 1a, or 2, further comprising mixing an aqueous dispersion of halogenated butyl rubber, a stabilizer, sulfur, zinc oxide, and a vulcanization accelerator to obtain an aqueous dispersion for immersion. Item 3a. The method according to any one of the above items (items 1 to 3), wherein the solid content concentration of the aqueous dispersion for immersion (preferably the total concentration of halogenated butyl rubber, stabilizer, sulfur, zinc oxide, and vulcanization accelerator) is 30 to 50% by mass. Item 3b. The method according to any one of the above items (items 1 to 3a), wherein the stabilizer comprises an alkali (preferably an alkali metal hydroxide) and a thickener (preferably at least one selected from the group consisting of casein or a salt thereof, carboxymethylcellulose or a salt thereof, polyacrylic acid or a salt thereof, polyvinyl alcohol, and polyvinyl methyl ether), and the vulcanization accelerator comprises a dithiocarbamate and a 2-mercaptobenzothiazole salt. Item 3c. The method according to item 3b, wherein, with respect to 100 parts by mass of halogenated butyl rubber, one of the following conditions selected from the group consisting of (i) to (vi) is satisfied.Item 4 contains: (i) 0.1 to 2 parts by mass of alkali (more preferably 0.5 to 1.5 parts by mass) (ii) 0.1 to 2 parts by mass of thickener (more preferably 0.5 to 1.5 parts by mass) (iii) 0.1 to 10 parts by mass of sulfur (more preferably 0.5 to 5 parts by mass, even more preferably 1 to 5 parts by mass, and even more preferably 2 to 4 parts by mass) (iv) 0.1 to 10 parts by mass of zinc oxide (more preferably 0.5 to 5 parts by mass, even more preferably 1 to 2 parts by mass) (v) 0.1 to 10 parts by mass of dithiocarbamate (more preferably 0.5 to 5 parts by mass, even more preferably 1 to 2 parts by mass) (vi) 0.1 to 10 parts by mass of 2-mercaptobenzothiazole salt (more preferably 0.5 to 5 parts by mass, even more preferably 1 to 5 parts by mass, and even more preferably 2 to 4 parts by mass). The method according to item 3, 3a, 3b, or 3c, wherein the aqueous dispersion of halogenated butyl rubber contains halogenated butyl rubber, water, alkali metal hydroxide, and a surfactant (preferably at least one selected from the group consisting of fatty acids or their salts, alkylbenzene sulfonates, and rosinates, more preferably a fatty acid having 10 to 20 carbon atoms or a salt thereof). Item 5. The method according to item 3, 3a, 3b, 3c, or 4, further comprising preparing an organic solvent solution by dissolving halogenated butyl rubber and a surfactant (preferably at least one selected from the group consisting of fatty acids or their salts, alkylbenzene sulfonates, and rosinates, more preferably a fatty acid having 10 to 20 carbon atoms or a salt thereof) in an organic solvent, mixing the organic solvent solution with an aqueous alkali metal hydroxide solution, and then removing the organic solvent to prepare an aqueous dispersion of halogenated butyl rubber. Item 6. The method according to item 4 or 5, wherein the surfactant is oleic acid or a salt thereof. Item 7. The method according to any of the above items (items 1 to 6), wherein the halogenated butyl rubber is brominated butyl rubber. Item 8. The method according to any one of the above items (items 1 to 7), wherein the halogenated butyl rubber molded body is a halogenated butyl rubber glove. Item 9. The method according to any one of the above items (items 1 to 8), wherein the coagulant is a polyvalent metal salt. Item 10. The method according to item 9, wherein the polyvalent metal salt is a calcium salt.

[0009] This disclosure provides a butyl rubber molded article (particularly a butyl rubber glove) with increased strength (particularly fracture stress) compared to a butyl rubber molded article obtained by conventional dip molding, and a method for manufacturing the same.

[0010] Furthermore, when butyl rubber gloves are prepared by dip molding using this manufacturing method, the efficiency of molding according to the mold is improved. More specifically, the possibility of bulging occurring in the film formed on the mold due to trapped air bubbles, etc., can be reduced. Therefore, this manufacturing method can also reduce the defect rate of butyl rubber molded products and improve manufacturing efficiency.

[0011] The embodiments included in this disclosure will be described in more detail below. This disclosure preferably includes, but is not limited to, a method for producing a halogenated butyl rubber molded article, which comprises: (γ) immersing a mold with a coagulant attached to its surface in an aqueous dispersion for dipping containing halogenated butyl rubber and removing it, and (δ) drying and vulcanizing the aqueous dispersion for dipping attached to the surface of the mold to obtain a halogenated butyl rubber molded article, and halogenated butyl rubber molded articles obtained by this method. This disclosure is therefore not limited to these, and encompasses everything disclosed herein and recognizable to those skilled in the art. The method may be referred to as the manufacturing method of this disclosure. The aqueous dispersion for dipping here is an aqueous dispersion that can be used for dip molding, and can therefore also be referred to as an aqueous dispersion for dip molding. The aqueous dispersion is preferably latex.

[0012] Butyl rubber is a copolymer composed of isobutylene and a small amount of isoprene. According to the JIS K 6937 classification, it is classified in the R group (rubber with unsaturated hydrocarbons in the main chain), along with natural rubber (NR), isoprene rubber (IR), styrene-butadiene rubber (SBR), and butadiene rubber (BR). The abbreviation for butyl rubber is IIR. When IIR is reacted with halogen molecules to halogenate the main chain, halogenated butyl rubber (halogenated IIR) is produced.

[0013] Butyl rubber is composed of isobutylene and isoprene. More specifically, the main chain of butyl rubber is a copolymer obtained by copolymerizing isobutylene with a small amount of isoprene as an unsaturated moiety (usually about 3 mol% or less of the total butyl rubber, typically 0.6 to 3 mol%). Halogenated butyl rubber is obtained by halogenating the isoprene moiety in this main chain. The halogen content in halogenated butyl rubber is usually about 1 to 3% by mass relative to the halogenated butyl rubber, and halogenated butyl rubber with a halogenation rate in this range can be used in the manufacturing method of this disclosure. As halogenated butyl rubber used in the manufacturing method of this disclosure, chlorinated butyl rubber (CIIR) with introduced chloride groups and brominated butyl rubber (BIIR) with introduced bromide groups are preferred examples, with brominated butyl rubber being particularly preferred. In addition, commercially available halogenated butyl rubber can be purchased and used in the manufacturing method of this disclosure. For example, as brominated butyl rubber, "BROMOBUTYL 2222" (Br content: 2.0% by mass), "BROMOBUTYL 2244" (Br content: 2.1% by mass), and "BROMOBUTYL 2255" (all manufactured by Nippon Butyl Co., Ltd.) can be used. Also, as chlorinated butyl rubber, for example, "CHLOROBUTYL 1066" (Cl content: 1.2% by mass) (manufactured by Nippon Butyl Co., Ltd.) can be used.

[0014] As described above, the manufacturing method of the present disclosure includes immersing a mold on which a coagulant has adhered to its surface in an aqueous dispersion for immersion containing halogenated butyl rubber and then removing it.

[0015] The aqueous dispersion for immersion containing halogenated butyl rubber preferably contains, in addition to halogenated butyl rubber, water, a stabilizer, sulfur, zinc oxide, and a vulcanization accelerator. Furthermore, the manufacturing method of the present disclosure may further include, for example, (α): mixing an aqueous dispersion of halogenated butyl rubber, a stabilizer, sulfur, zinc oxide, and a vulcanization accelerator to obtain an aqueous dispersion for immersion. In addition, for example, in the mixing, known additives such as rheology modifiers, antioxidants, defoamers, pH adjusters, chelating agents, film-forming aids, plasticizers, silane coupling agents, fillers, and pigments may be further mixed in addition to these components.

[0016] As a stabilizer, known stabilizers that can be used with rubber latex can be used, such as alkalis and thickeners. Stabilizers can be used individually or in combination of two or more.

[0017] As the alkali, alkali metal hydroxide is preferred, and potassium hydroxide or sodium hydroxide is particularly preferred. The alkali can be used alone or in combination of two or more.

[0018] As a thickening agent, water-soluble polymers are preferred, more specifically, casein or its salts, carboxymethylcellulose (CMC) or its salts, polyacrylic acid or its salts, polyvinyl alcohol (PVA), polyvinyl methyl ether, etc., with casein or its salts being particularly preferred. As for the salts of each component exemplified here, alkali metal salts are preferred for all components, with potassium salts or sodium salts being preferred. Sodium caseinate is particularly preferred as a thickening agent. The thickening agents can be used individually or in combination of two or more.

[0019] Hereafter, alkali may be referred to as component (a) and thickener as component (b).

[0020] The stabilizer is preferably used in combination with an alkali and a thickener, and is particularly preferably used in combination with an alkali metal salt (especially potassium hydroxide) and casein or a salt thereof (especially sodium caseinate).

[0021] While there are no particular restrictions on the sulfur used, it is preferable to use granular sulfur (especially fine-grained sulfur), such as colloidal sulfur or precipitated sulfur. Although we do not wish to be limited to theory, in the manufacturing method of this disclosure, sulfur may act as a vulcanizing agent. Hereinafter, sulfur may be referred to as component (c).

[0022] While there are no particular restrictions on the zinc oxide used, granular zinc oxide (especially fine-grained) is preferred, and the use of one or two types of zinc oxide (JIS K1410:2006) is more preferred. Although we do not wish to be limited to theory, in the manufacturing method of this disclosure, zinc oxide may act as a vulcanization accelerator. Hereinafter, zinc oxide may be referred to as component (d).

[0023] As the vulcanization accelerator, known vulcanization accelerators used for rubber latex can be used, such as various known vulcanization accelerators including aldehydeamine-based, thiourea-based, guanidine-based, thiazole-based, thiraum-based, dithiocarbamate-based, and xanthate-based accelerators. Among these, dithiocarbamate salts (a dithiocarbamate-based accelerator) and 2-mercaptobenzothiazole salts (a thiazole-based accelerator) are preferably used. The vulcanization accelerator can be used alone or in combination of two or more types.

[0024] Examples of dithiocarbamates include dimethyldithiocarbamate, diethyldithiocarbamate, dibutyldithiocarbamate, ethylphenyldithiocarbamate, pentamethylenedithiocarbamate, and pentamethylenedithiocarbamate. Examples of the salts include zinc salts, sodium salts, and potassium salts, with zinc salts and sodium salts being more preferred. More specifically, examples of dithiocarbamates include zinc dimethyldithiocarbamate (PZ), zinc diethyldithiocarbamate (EZ), zinc dibutyldithiocarbamate (BZ), zinc ethylphenyldithiocarbamate (PX), zinc pentamethylenedithiocarbamate, sodium dimethyldithiocarbamate, sodium diethyldithiocarbamate, sodium dibutyldithiocarbamate, sodium pentamethylenedithiocarbamate, and potassium pentamethylenedithiocarbamate. Among these, zinc diethyldithiocarbamate (EZ) is preferred. Dithiocarbamates can be used individually or in combination of two or more. Hereinafter, dithiocarbamates may be referred to as component (e).

[0025] Examples of 2-mercaptobenzothiazole salts include zinc salts, sodium salts, and cyclohexylamine salts, with zinc salts being particularly preferred. 2-mercaptobenzothiazole salts can be used individually or in combination of two or more. Hereinafter, 2-mercaptobenzothiazole salts may be referred to as component (f).

[0026] It is more preferable to use a combination of a thiocarbamate and a 2-mercaptobenzothiazole salt as the vulcanization accelerator. It is particularly preferable to use a combination of zinc diethyldithiocarbamate and a 2-mercaptobenzothiazole zinc salt.

[0027] In the aqueous dispersion for immersion, it is preferable that the stabilizer be included in an amount of 0.1 to 5 parts by mass per 100 parts by mass of halogenated butyl rubber. The upper or lower limit of this range may be, for example, 0.2, 0.3, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, or 4.5 parts by mass. For example, the range is more preferably 0.2 to 4 parts by mass, even more preferably 0.2 to 2 parts by mass, and still more preferably 0.5 to 1.5 parts by mass. In addition, it is preferable that the total amount of sulfur, zinc oxide, and vulcanization accelerator be included in an amount of 0.1 to 40 parts by mass per 100 parts by mass of halogenated butyl rubber. The upper or lower limit of the range may be, for example, 0.2, 0.3, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, or 39 parts by mass. For example, the range is more preferably 0.5 to 20 parts by mass, even more preferably 2 to 20 parts by mass, even more preferably 3 to 18 parts by mass, and particularly preferably 6 to 12 parts by mass. Furthermore, it is preferable that sulfur, zinc oxide, and vulcanization accelerator are included in amounts within the following ranges per 100 parts by mass of halogenated butyl rubber. Sulfur: 0.1 to 10 parts by mass (The upper or lower limit of this range may be, for example, 0.2, 0.3, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, or 9 parts by mass. For example, the range is more preferably 0.5 to 5 parts by mass, even more preferably 1 to 5 parts by mass, and even more preferably 2 to 4 parts by mass.) Zinc oxide: 0.1 to 10 parts by mass (The upper or lower limit of this range may be, for example, 0.2, 0.3, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, or 9 parts by mass. For example, the range is more preferably 0.5 to 5 parts by mass, and even more preferably 1 to 2 parts by mass.) Vulcanization accelerator: 0.2 to 20 parts by mass (the upper or lower limit of this range may be, for example, 0.3, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or 19 parts by mass. For example, this range is more preferably 1 to 15 parts by mass, even more preferably 2 to 10 parts by mass, and even more preferably 3 to 8 parts by mass.)

[0028] Furthermore, if the aqueous dispersion for immersion contains components (a) to (f) above, it is preferable that the total amount of components (a) and (b) is 0.1 to 5 parts by mass per 100 parts by mass of halogenated butyl rubber. The upper or lower limit of this range may be, for example, 0.2, 0.3, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, or 4.5 parts by mass. For example, the range is more preferably 0.2 to 4 parts by mass, even more preferably 0.2 to 2 parts by mass, and even more preferably 0.5 to 1.5 parts by mass. Also, it is preferable that the total amount of components (c) to (f) is 0.1 to 40 parts by mass per 100 parts by mass of halogenated butyl rubber. The upper or lower limit of the range may be, for example, 0.2, 0.3, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, or 39 parts by mass. For example, the range is more preferably 0.5 to 20 parts by mass, even more preferably 2 to 20 parts by mass, even more preferably 3 to 18 parts by mass, and particularly preferably 6 to 12 parts by mass.

[0029] Furthermore, if the aqueous dispersion for immersion contains the above components (a) to (f), it is preferable that each component is included in the following amounts per 100 parts by mass of halogenated butyl rubber. (a) Component: 0.1 to 2 parts by mass (The upper or lower limit of this range may be, for example, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, or 1.9 parts by mass. For example, the range is more preferably 0.5 to 1.5 parts by mass.) (b) Component: 0.1 to 2 parts by mass (The upper or lower limit of this range may be, for example, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, or 1.9 parts by mass. For example, the range is more preferably 0.5 to 1.5 parts by mass.) (c) Component: 0.1 to 10 parts by mass (The upper or lower limit of this range may be, for example, 0.2, 0.3, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, or 9 parts by mass. For example, the range is more preferably 0.5 to 5 parts by mass, even more preferably 1 to 5 parts by mass, and even more preferably 2 to 4 parts by mass.) (d) Component: 0.1 to 10 parts by mass (The upper or lower limit of this range may be, for example, 0.2, 0.3, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, or 9 parts by mass. For example, the range is more preferably 0.5 to 5 parts by mass, and even more preferably 1 to 2 parts by mass.) (e) Component: 0.1 to 10 parts by mass (The upper or lower limit of this range may be, for example, 0.2, 0.3, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, or 9 parts by mass. For example, the range is more preferably 0.5 to 5 parts by mass, even more preferably 1 to 2 parts by mass.) (f) Component: 0.1 to 10 parts by mass (The upper or lower limit of this range may be, for example, 0.2, 0.3, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, or 9 parts by mass. For example, the range is more preferably 0.5 to 5 parts by mass, even more preferably 1 to 5 parts by mass, and even more preferably 2 to 4 parts by mass.)

[0030] Furthermore, the aqueous dispersion for immersion preferably contains 30 to 50% by mass of halogenated butyl rubber, more preferably 31 to 49% by mass, 32 to 48% by mass, 33 to 47% by mass, or 34 to 46% by mass, and even more preferably 35 to 45% by mass.

[0031] Furthermore, the solid content concentration of the aqueous dispersion for immersion is preferably 30 to 50% by mass, more preferably 31 to 49% by mass, 32 to 48% by mass, 33 to 47% by mass, or 34 to 46% by mass, and even more preferably 35 to 45% by mass. The solid content concentration is calculated by totaling the amounts of halogenated butyl rubber and other solid components used. The aqueous dispersion for immersion may also contain a surfactant (emulsifier). As such surfactants, anionic surfactants are preferred, and examples include fatty acids or their salts, alkylbenzene sulfonates, rosinates, etc. As fatty acids or their salts, fatty acids having 10 to 20 carbon atoms (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20) or their salts are preferred. Preferred fatty acids include, for example, lauric acid, myristic acid, palmitic acid, oleic acid, and stearic acid, with oleic acid being particularly preferred. Alkali metal salts are preferred as the salts of the fatty acids, with sodium salts or potassium salts being more preferred. Fatty acids having 10 to 20 carbon atoms or their salts can be used individually or in combination of two or more. As alkylbenzene sulfonates, alkylbenzene sulfonates having an alkyl group with 10 to 20 carbon atoms (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 carbon atoms) are preferred, more specifically, dodecylbenzene sulfonate, decylbenzene sulfonate, cetylbenzene sulfonate, etc. Alkali metal salts are preferred as the salts, with sodium salts or potassium salts being more preferred. Alkylbenzene sulfonates can be used individually or in combination of two or more. As for the rosinate salt, alkali metal salts of rosinic acid are preferred, and more specifically, sodium rosinate and potassium rosinate are preferred.In addition, other surfactants that can be used include, for example, alkyl sulfosuccinates such as sodium di(2-ethylhexyl)sulfosuccinate, potassium di(2-ethylhexyl)sulfosuccinate, and sodium dioctylsulfosuccinate; alkyl sulfate esters such as sodium lauryl sulfate and potassium lauryl sulfate; polyoxyethylene alkyl ether sulfate esters such as sodium polyoxyethylene lauryl ether sulfate and potassium polyoxyethylene lauryl ether sulfate; and monoalkyl phosphates such as sodium lauryl phosphate and potassium lauryl phosphate. One or more surfactants can be used in combination. Furthermore, when a surfactant is used in the aqueous dispersion for immersion, the amount of surfactant that can disperse the halogenated butyl rubber can be appropriately set. Although not particularly limited, for example, when a fatty acid having 10 to 20 carbon atoms or a salt thereof is used as the surfactant, it can be used in amounts of preferably 1 to 10 parts by mass, more preferably 2 to 8 parts by mass, and even more preferably 3 to 7 parts by mass per 100 parts by mass of halogenated butyl rubber.

[0032] The aqueous dispersion for immersion can be prepared by known methods or by methods readily conceivable from known methods, as long as it does not impair the effectiveness of the manufacturing method of this disclosure. Preferably, an aqueous dispersion of halogenated butyl rubber is first prepared (using a surfactant if necessary), and other components (e.g., stabilizers (especially alkalis and / or thickeners), sulfur, zinc oxide, vulcanization accelerators, and water and other additives as necessary) are added and mixed, and then allowed to stand and mature. When mixing other components with the aqueous dispersion of halogenated butyl rubber, it is preferable to prepare an aqueous solution or aqueous dispersion of the other components in advance and mix them. If the other components are water-soluble, an aqueous solution can be prepared by mixing them with water. If the other components are poorly water-soluble, an aqueous dispersion can be prepared by mixing them with water using a surfactant as necessary. The surfactant used here is preferably one that can be used to disperse halogenated butyl rubber in the aqueous dispersion for immersion as described above, and anionic surfactants such as alkylbenzene sulfonates (especially sodium salts) can be preferably used. Furthermore, as a mixing method when preparing the aqueous dispersion, it is preferable to use, for example, a bead mill.

[0033] Furthermore, while there are no particular limitations on the conditions for letting the mixture stand after mixing, it is preferable to let it stand at 15 to 80°C for 2 to 48 hours, and more preferably at 20 to 75°C for 4 to 36 hours.

[0034] The aqueous solutions or aqueous dispersions of the other components are preferably concentrated to about 5 to 30% by mass, and more preferably to about 10 to 20% by mass. Furthermore, the amount of each component added is preferably adjusted so that the content of each component in the resulting aqueous dispersion for immersion falls within the range described above.

[0035] For example, if the aqueous dispersion for immersion contains components (a) to (f) above, it is preferable to prepare aqueous solutions or aqueous dispersions of the following concentrations in advance and then mix them with the aqueous dispersion of halogenated butyl rubber: (a) component: 5 to 15% by mass (more preferably 8 to 12% by mass) (b) component: 5 to 15% by mass (more preferably 8 to 12% by mass) (c) component: 10 to 30% by mass (more preferably 15 to 25% by mass) (d) component: 10 to 30% by mass (more preferably 15 to 25% by mass) (e) component: 10 to 30% by mass (more preferably 15 to 25% by mass) (f) component: 10 to 30% by mass (more preferably 15 to 25% by mass)

[0036] Furthermore, aqueous dispersions of halogenated butyl rubber can be prepared by known methods or methods easily conceivable from known methods, as long as the effects of the manufacturing method of this disclosure are not impaired. For example, an aqueous dispersion of halogenated butyl rubber can be prepared by preparing an organic solvent solution by dissolving halogenated butyl rubber in an organic solvent, mixing the organic solvent solution with an alkaline aqueous solution, and then removing the organic solvent. It is preferable to dissolve a surfactant in either (or both) the organic solvent solution or the alkaline aqueous solution before use. More preferably, an aqueous dispersion of halogenated butyl rubber can be prepared by preparing an organic solvent solution by dissolving halogenated butyl rubber and a surfactant (preferably an anionic surfactant) in an organic solvent, mixing the organic solvent solution with an alkaline aqueous solution, and then removing the organic solvent. As the surfactant, for example, the surfactants mentioned above can be used, and among them, it is preferable to use a fatty acid having 10 to 20 carbon atoms or a salt thereof. An aqueous dispersion of halogenated butyl rubber can be more preferably prepared by preparing an organic solvent solution by dissolving halogenated butyl rubber and a fatty acid having 10 to 20 carbon atoms or a salt thereof in an organic solvent, mixing the organic solvent solution with an alkaline aqueous solution, and then removing the organic solvent. The manufacturing method of the present disclosure may further include, for example, preparing an aqueous dispersion of halogenated butyl rubber.

[0037] As the organic solvent, any known organic solvent capable of dissolving halogenated butyl rubber can be used, such as hexane, isohexane, pentane, cyclohexane, heptane, isooctane, xylene, toluene, and benzene. Toluene is preferred among these. Furthermore, the amount of organic solvent used should be sufficient to dissolve the halogenated butyl rubber and a fatty acid having 10 to 20 carbon atoms or a salt thereof. For example, about 500 to 1000 parts by mass, preferably about 600 to 900 parts by mass, can be used per 100 parts by mass of halogenated butyl rubber.

[0038] As described above, preferred fatty acids having 10 to 20 carbon atoms include, for example, lauric acid, myristic acid, palmitic acid, oleic acid, and stearic acid, with oleic acid being particularly preferred. Furthermore, alkali metal salts are preferred as salts of the fatty acids, with sodium salts or potassium salts being more preferred. Fatty acids having 10 to 20 carbon atoms or their salts can be used individually or in combination of two or more. The fatty acids having 10 to 20 carbon atoms or their salts can be used in amounts of preferably 1 to 10 parts by mass, more preferably 2 to 8 parts by mass, and even more preferably 3 to 7 parts by mass, per 100 parts by mass of halogenated butyl rubber.

[0039] One method for preparing an organic solvent solution in which halogenated butyl rubber and a fatty acid having 10 to 20 carbon atoms or a salt thereof are dissolved in an organic solvent is to dissolve halogenated butyl rubber in an organic solvent and then dissolve a fatty acid having 10 to 20 carbon atoms or a salt thereof in this solution.

[0040] The method for dissolving halogenated butyl rubber in an organic solvent is not particularly limited as long as the halogenated butyl rubber can be dissolved in the organic solvent, but one example is stirring at around 60-80°C for 2-12 hours. To this, a fatty acid with 10-20 carbon atoms or a salt thereof can be added and stirred until it is also dissolved.

[0041] As the alkali used in the alkaline aqueous solution, the same ones as those listed as the above component (a) can be used. That is, alkali metal hydroxides are preferable, and potassium hydroxide or sodium hydroxide is particularly preferable. The alkali can be used alone, or two or more kinds thereof can be used in combination. The alkali is preferably used in an amount of 0.1 to 5 parts by mass, more preferably 0.2 to 3 parts by mass, still more preferably 0.5 to 2 parts by mass, per 100 parts by mass of halogenated butyl rubber.

[0042] When mixing the organic solvent solution and the alkaline aqueous solution, it is preferable that the ratio of the mass of the organic solvent solution to the mass of water contained in the alkaline aqueous solution (organic solvent solution / water contained in the alkaline aqueous solution) is 1 to 2, and more preferably 1.2 to 1.8. In addition, when mixing the organic solvent solution and the alkaline aqueous solution, it is preferable that the obtained mixed liquid contains 0.1 to 5 parts by mass of the alkali, more preferably 0.2 to 3 parts by mass, and still more preferably 0.5 to 2 parts by mass, per 100 parts by mass of the halogenated butyl rubber.

[0043] In addition, the mixing of the organic solvent solution and the alkaline aqueous solution is preferably performed so that the halogenated butyl rubber is well dispersed, and it is more preferable to perform the mixing using a stirrer such as a homomixer, for example.

[0044] As a method for removing the organic solvent from the obtained mixed liquid of the organic solvent solution and the alkaline aqueous solution, a known organic solvent removal method can be used, and examples thereof include a method of distilling off the organic solvent by heating (preferably under reduced pressure). The distillation can be performed using, for example, a flask (particularly a separable flask), a rotary evaporator, or the like. Although not particularly limited, the distillation can be performed under reduced pressure (for example, 10 to 30 kPa). In addition, the distillation can also be performed while heating (for example, at 50 to 60°C).

[0045] A product obtained by removing the organic solvent from the mixed solution can be preferably used as an aqueous dispersion of halogenated butyl rubber. Further, the product obtained by removing the organic solvent from the mixed solution can be more preferably used as an aqueous dispersion of halogenated butyl rubber after further concentration. The solid content concentration can be adjusted by concentration. As the concentration method, a known concentration method can be used, and examples thereof include ultrafiltration. The molecular weight cut-off of the membrane used in ultrafiltration is preferably 100,000 to 300,000, more preferably 150,000 to 250,000.

[0046] Although not particularly limited, the solid content concentration in the aqueous dispersion of halogenated butyl rubber is preferably 40 to 60% by mass, more preferably 45 to 55% by mass.

[0047] The solid content concentration in the aqueous dispersion of halogenated butyl rubber is a value obtained by the following method. Specifically, it is a value calculated by the following formula when X g is the residue obtained after drying P g (about 2 g) of the aqueous dispersion of halogenated butyl rubber at 130°C for 2 hours to remove moisture. Solid content concentration (mass%) = (X / P) × 100

[0048] In the production method of the present disclosure, as described above, a mold having a coagulant adhered to its surface is immersed in the aqueous dipping dispersion and then taken out.

[0049] The material of the mold is not particularly limited, and a mold made of a known material can be used. For example, metal molds, ceramic molds and the like can be preferably used, and ceramic molds are more preferable.

[0050] As a coagulant, polyvalent metal salts are preferred, with examples including calcium salts, magnesium salts, barium salts, zinc salts, and aluminum salts. Among polyvalent metal salts, water-soluble polyvalent metal salts are preferred. More specifically, examples of calcium salts include calcium chloride, calcium nitrate, calcium acetate, and calcium sulfate. Examples of magnesium salts include magnesium chloride and magnesium sulfate. Examples of barium salts include barium chloride, barium nitrate, and barium acetate. Examples of zinc salts include zinc chloride, zinc nitrate, and zinc acetate. Examples of aluminum salts include aluminum chloride and aluminum sulfate. Coagulants containing calcium ions are preferred, and therefore, among polyvalent metal salts, calcium salts are particularly preferred, and calcium nitrate is particularly preferred. The coagulant can be used alone or in combination of two or more types.

[0051] A preferred method for adhering the coagulant to the surface of a mold is to prepare an aqueous solution of the coagulant (coagulation solution), immerse the mold in it (dip) and remove it, and then dry it. The above coagulation solution may contain alcohol, for example, methanol or ethanol. The manufacturing method of the present disclosure may further include, for example, (β): immersing the mold in the coagulation solution and then drying it to obtain a mold on which the coagulant has adhered to the surface.

[0052] The concentration of the coagulant in the coagulation solution is not particularly limited as long as an appropriate amount of coagulant adheres to the mold surface, but for example, 30 to 70% by mass is preferred, and 40 to 60% by mass is more preferred. The immersion time can be set as appropriate. For example, 1 to 30 seconds is preferred, 2 to 20 seconds is more preferred, and 3 to 10 seconds is even more preferred.

[0053] Furthermore, the coagulation solution may contain a release agent as needed. Known release agents can be used, and calcium carbonate is preferred, for example. The concentration of the release agent in the coagulation solution is preferably 1 to 10% by mass, and more preferably 3 to 7% by mass.

[0054] The method for drying the solidified liquid adhering to the mold surface is not particularly limited as long as it can leave the solidifying agent adhering to the mold surface, but one example is to air dry it with air at 100 to 140°C for 1 to 10 minutes.

[0055] After immersing the mold, which has a coagulant adhering to its surface, into an aqueous dispersion for immersion and removing it, the aqueous dispersion adhering to the surface of the mold is dried and vulcanized to obtain a halogenated butyl rubber molded body.

[0056] There are no particular limitations on the method for removing the mold that has been immersed in the aqueous dispersion for immersion. Examples include lifting the mold up or lowering the container containing the aqueous dispersion for immersion to bring the mold above the water surface.

[0057] The time from immersion to removal of the mold is not particularly limited as long as the aqueous dispersion for immersion adheres to the surface of the mold, but for example, 10 seconds to 10 minutes is preferred, and 30 seconds to 3 minutes is more preferred.

[0058] While we do not wish to be bound by theory, it is thought that the coagulant (especially polyvalent metal ions) combines with fatty acids having 10 to 20 carbon atoms or their salts, which can act as anionic surfactants (emulsifiers), to form insoluble salts, causing the emulsifier to lose its emulsifying ability and resulting in the aggregation of halogenated butyl rubber on the mold surface. Therefore, it is thought that the main component of the aqueous dispersion used for immersion that adheres to the mold surface is this aggregated halogenated butyl rubber.

[0059] After removing the mold, the aqueous dispersion for immersion adhering to the mold surface is dried, and then it is heated and vulcanized. Alternatively, after removing the mold, before drying, leaching (an operation to remove unwanted components, especially emulsifiers) may be performed. Leaching can be performed, for example, by removing the mold, letting it stand for a while as needed, and then immersing the mold in an unwanted component eluent. Specifically, this standing can be performed at, for example, 10 to 40°C (preferably 15 to 30°C). The standing time can be 0.5 to 30 minutes (preferably 2 to 10 minutes, more preferably 1 to 5 minutes). More specifically, it is preferable to stand at 10 to 40°C for 0.5 to 30 minutes. The unwanted component eluent can be any liquid from which unwanted components can be removed by dissolving them through immersion, and can be selected as appropriate. Specifically, water (e.g., pure water, deionized water, etc.) is preferred. Furthermore, this immersion can be carried out, for example, by immersing the mold in an eluent of unwanted components at 25 to 90°C (preferably 40 to 80°C, more preferably 40 to 70°C) for about 0.5 to 60 minutes (preferably 1 to 20 minutes).

[0060] The drying method is not particularly limited, and any method that can remove moisture can be appropriately selected. For example, this could be drying by leaving it to stand (static drying) or drying by blowing air on it (air drying). The drying is preferably carried out at a temperature of about 50 to 90°C (preferably 60 to 80°C). In the case of air drying, the temperature of the air is also preferably around this temperature. The drying time can be set as appropriate, for example, about 5 to 30 minutes (preferably 10 to 20 minutes).

[0061] Furthermore, a method of vulcanization is to heat at 100 to 180°C. The upper or lower limit of this range may be, for example, 110, 120, 130, 140, 150, 160, or 170°C. This range may be, for example, 140 to 180°C, 150 to 170°C, or 120 to 160°C. The heating time can be set as appropriate, for example, 0.5 to 4 hours. The upper or lower limit of this range may be, for example, 1, 1.5, 2, 2.5, 3, or 3.5 hours. This range may be, for example, 0.5 to 2 hours. More specifically, a method of vulcanization is to heat at 100 to 180°C (preferably 120 to 160°C) for about 0.5 to 4 hours (preferably about 0.5 to 2 hours).

[0062] By drying and vulcanizing in this manner, a film is formed on the surface of the mold. This film can be obtained as a halogenated butyl rubber molded body. The thickness of the film is not particularly limited, but is preferably 0.1 mm or more, and more preferably 0.2 mm or more. The upper limit of the film thickness is also not particularly limited, but is 5 mm. The upper limit within this range (0.1 mm to 5 mm) may be, for example, 4, 3, 2, 1, or 0.5 mm. Three locations on the film without any bulges are arbitrarily selected and their thickness is measured, and the average value is taken as the film thickness. A film thickness gauge is used for measurement. An example of a film thickness gauge is the thickness gauge SM-112 (manufactured by Teclock Co., Ltd.).

[0063] The coating of the halogenated butyl rubber molded article obtained by the manufacturing method of this disclosure is more preferably 7.5 MPa or higher, and even more preferably 7.5 to 10 MPa.

[0064] The coating of the halogenated butyl rubber molded article obtained by the manufacturing method of the present disclosure is more preferably 0.2 to 0.5 mm thick and has a breaking stress of 7.5 MPa or more, and even more preferably 7.5 to 10 MPa.

[0065] The fracture stress was measured by performing a tensile test on a test piece punched out from the coating in the shape of a JIS No. 4 dumbbell (K7139:2009) at a measurement temperature of 25°C and a tensile speed of 300 mm / min. An Autograph (product name "AGS-X" from Shimadzu Corporation) can be used for this measurement.

[0066] Furthermore, various shapes of coatings can be obtained depending on the shape of the mold. For example, if a glove mold is used, halogenated butyl rubber gloves can be obtained.

[0067] Furthermore, during drying and vulcanization (especially during vulcanization), the film formed on the mold may bulge due to the inclusion of air bubbles or other imperfections. However, the manufacturing method disclosed herein can reduce the frequency of such bulging in the film.

[0068] In this specification, the term "comprising" includes both "consisting essentially of" and "consisting of." Furthermore, this disclosure encompasses all combinations of the constituent elements described herein.

[0069] Furthermore, the various characteristics (properties, structure, function, etc.) described for each embodiment of this disclosure described above may be combined in any way to identify the subject matter covered by this disclosure. In other words, this disclosure covers all subject matter consisting of any combination of the combinable characteristics described herein.

[0070] The embodiments of this disclosure will be described in more detail below with examples, but the embodiments of this disclosure are not limited to the examples below. As stated above, the aqueous dispersion for immersion is an aqueous dispersion that can be used for dip molding, and therefore can also be called an aqueous dispersion for dip molding, and in the following examples, it may be referred to as an aqueous dispersion for dip molding.

[0071] <Manufacturing Example 1> (Preparation of Isobutylene-Isoprene Copolymer Latex) Using isobutylene-isoprene copolymer brominated (brominated butyl rubber) as the raw material rubber, an aqueous dispersion (latex) of isobutylene-isoprene copolymer brominated was prepared. Specifically, it was prepared as follows.

[0072] 120 g (100 phr) of isobutylene-isoprene copolymer brominated (brominated butyl rubber) (manufactured by Nippon Butyl Co., Ltd., trade name "BROMOBUTYL 2222") and 880 g (733 phr) of toluene were placed in a separable flask and stirred at 70°C for 6 hours to dissolve, preparing a 12% by mass brominated butyl rubber solution. To the obtained brominated butyl rubber solution, 6.00 g (5 phr) of oleic acid (manufactured by NOF Corporation, trade name: Extra Olein) was further added to prepare a solution. (This solution is also referred to as the "organic solvent solution.")

[0073] In a separate container, a potassium hydroxide solution (KOH solution) was prepared. Specifically, when the organic solvent solution and the KOH solution were mixed, the ratio of the total mass of the organic solvent solution and potassium hydroxide to the mass of water ("brominated butyl rubber + toluene + oleic acid + potassium hydroxide / water") was 1.5 in the amount of water (671.51 g), and 1.26 g (1.0 phr) of potassium hydroxide was dissolved in it to prepare an aqueous KOH solution.

[0074] An aqueous KOH solution was added to the organic solvent solution, and the mixture was stirred and mixed for 15 minutes at a rotation speed of 9,000 rpm using a stirrer (Primix Corporation, product name "TK Autohomomixer SL type") to obtain an emulsion.

[0075] The resulting emulsion was heated to 55°C under reduced pressure of 20 kPa while being stirred in a separable flask to remove toluene by distillation.

[0076] Subsequently, the mixture was concentrated using an ultrafiltration apparatus (ultrafiltration membrane: flat membrane type, molecular weight cutoff: 200,000, material: polysulfone) to a solid content concentration of 50% by mass, thereby obtaining isobutylene-isoprene copolymer brominated latex (brominated butyl rubber).

[0077] The solid content concentration was calculated by weighing Pg (approximately 2g) from the obtained latex, drying it in a forced-air dryer (AVVANTEC DRE320DB) at 130°C for 2 hours to remove moisture, and then measuring the mass of the residue (Xg). (In the latex prepared in Production Example 1, the solid content concentration essentially represents the brominated butyl rubber concentration.) Solid content concentration (mass%) = (X / P) × 100 The same procedure applies to Production Example 2 below.

[0078] <Manufacturing Example 2> An aqueous dispersion of isobutylene-isoprene copolymer (butyl rubber) was prepared using isobutylene-isoprene copolymer as the raw material rubber. Specifically, it was prepared as follows.

[0079] In Production Example 1, the same procedure as in Production Example 1 was performed except that the raw rubber was changed to isobutylene-isoprene copolymer (BUTYL 065, manufactured by Nippon Butyl Co., Ltd.), and isobutylene-isoprene copolymer (butyl rubber) latex (solid content concentration 50% by mass) was obtained.

[0080] (Preparation of raw materials to be added to aqueous dispersions for dip molding) Aqueous dispersions for dip molding for each example and comparative example were prepared using the following raw materials: A: Potassium hydroxide (manufactured by Osaka Soda Co., Ltd.) B: Sodium caseinate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) C: Colloidal sulfur (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) D: Zinc oxide (manufactured by Seido Chemical Co., Ltd., trade name: Zinc Oxide 2) E: Zinc diethyldithiocarbamate (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., trade name: Noxellar EZ) F: 2-mercaptobenzothiazole zinc salt (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., trade name: Noxellar MZ)

[0081] The raw materials A through F were used as aqueous solutions or aqueous dispersions, respectively.

[0082] For A, 10.0 parts by mass of A was dissolved in 90.0 parts by mass of pure water to prepare a 10.0% by mass aqueous solution of A.

[0083] For B, a 10.0% by mass aqueous solution was prepared in the same manner as for A.

[0084] For C, 20.0 parts by mass of C, 1.0 part by mass of sodium alkylbenzenesulfonate (manufactured by NOF Corporation, trade name: Newlex R), and 79.0 parts by mass of pure water were mixed using a wet bead mill (manufactured by AIMEX Corporation, model: RMB) to prepare a 20% by mass aqueous dispersion of C.

[0085] For D, E, and F, a 20% by mass aqueous dispersion was prepared in the same manner as for C.

[0086] <Example 1> (Preparation of aqueous dispersion for dip molding) To the aqueous dispersion of isobutylene-isoprene copolymer brominated obtained in Production Example 1 (latex of brominated butyl rubber), aqueous solutions or aqueous dispersions of each raw material were added in the following amounts based on the solid content of each raw material: 0.5 parts by mass of raw material A, 0.5 parts by mass of raw material B, 2.0 parts by mass of raw material C, 1.0 part by mass of raw material D, 1.0 part by mass of raw material E, and 2.0 parts by mass of raw material F, per 100 parts by mass of isobutylene-isoprene copolymer brominated contained in the latex. Furthermore, 27.5 parts by mass of pure water were added to 100 parts by mass of isobutylene-isoprene copolymer brominated, and the mixture was left to stand at room temperature (25°C) for 24 hours to obtain an aqueous dispersion for dipping (aqueous dispersion for dip molding) with a solid content of 40% by mass. The 40% solid content concentration of the aqueous dispersion for dip molding refers to the total concentration of solids from the raw rubber and raw materials A to F contained in the aqueous dispersion for dip molding. The same applies to the solid content concentration of the aqueous dispersion for dip molding in the following examples.

[0087] (Preparation of Dip-Molded Body) A ceramic mold (a rectangular mold measuring 20 cm x 8 cm with a thickness of 5 mm) was immersed (dipped) for 5 seconds in a solidification solution (calcium nitrate / calcium carbonate / pure water mixed in a mass ratio of 45 / 5 / 50) and dried in a 120°C forced-air dryer for 5 minutes. Then, the ceramic mold was immersed (dipped) in the aforementioned aqueous dispersion for dip molding for 2 minutes to allow the rubber component to adhere to the ceramic mold. The ceramic mold was removed from the aqueous dispersion for dip molding and allowed to stand at 25°C for 2 minutes. Then, the ceramic mold with the rubber component attached was immersed in 60°C pure water for 5 minutes (leaching process). Then, the ceramic mold with the rubber component attached was dried in a 70°C forced-air dryer for 15 minutes and further vulcanized by heating at 160°C for 1 hour. After cooling to room temperature, the film was peeled off the ceramic mold and obtained as a dip-molded body.

[0088] (Strength evaluation of dip-molded body) Test pieces punched out from the obtained coating into the shape of a JIS No. 4 dumbbell (JIS K 7139 2009) were subjected to tensile tests using an Autograph (product name "AGS-X" from Shimadzu Corporation) at a measurement temperature of 25°C and a tensile speed of 300 mm / min, and the fracture stress was measured.

[0089] In cases where the coating had bulges, the evaluation was performed using areas without bulges.

[0090] (Condition of the dip-molded body) The obtained coating was visually inspected to see if there were any bulges that appeared to be caused by trapped air bubbles.

[0091] (Thickness of the dip-molded body) The thickness of the obtained coating was measured using a film thickness gauge. If the coating had bulges, the measurement was taken using areas without bulges. More specifically, three areas without bulges were arbitrarily selected, their thickness was measured, and the average value was adopted as the thickness of the coating. A film thickness gauge (thickness gauge SM-112, manufactured by Teclock Co., Ltd.) was used for the measurement.

[0092] <Examples 2-6> In Examples 2-6, the same procedure as in Example 1 was followed, except that the amounts of raw materials C-F used in preparing the aqueous dispersion for dip molding, the standing conditions after preparation, and the dipping time into the ceramic mold composition were changed to the conditions shown in Table 1, to obtain a dip molded body. In Examples 3 and 4, the amount of pure water used in preparing the aqueous dispersion for dip molding was adjusted so that an aqueous dispersion with a solid content concentration of 40% by mass was obtained.

[0093] <Comparative Example 1> A dip-molded body was obtained by performing the same procedure as in Example 1, except that the latex obtained in Production Example 1 was replaced with the latex obtained in Production Example 2.

[0094] <Comparative Examples 2-3> In Comparative Example 1, the same procedure as in Comparative Example 1 was performed, except that the amount of raw materials C-F added for preparing the aqueous dispersion for dip molding, the standing conditions after preparation, and the dipping time into the ceramic mold composition were changed to the conditions shown in Table 1, and a dip molded body was obtained. In Comparative Example 2, when preparing the aqueous dispersion for dip molding, the amount of pure water was adjusted so that an aqueous dispersion for dip molding with a solid content concentration of 40% by mass was obtained.

[0095] The physical properties of the dip-molded bodies (coatings) obtained in each example and comparative example are summarized in Table 2.

[0096]

[0097]

[0098] This invention provides a butyl rubber molded article (particularly a butyl rubber glove) with increased strength (especially in terms of fracture stress) compared to butyl rubber molded articles obtained by conventional dip molding, and a method for manufacturing the same. Furthermore, this manufacturing method can reduce the defect rate of the butyl rubber molded article and improve manufacturing efficiency. As a result, the amount of waste liquid can be reduced, which is also preferable from the standpoint of environmental protection.

Claims

1. A method for producing a halogenated butyl rubber molded article, comprising: (γ) immersing a mold with a coagulant attached to its surface in an aqueous dispersion for immersion containing halogenated butyl rubber, water, a stabilizer, sulfur, zinc oxide, and a vulcanization accelerator, and then removing it; and (δ) drying and vulcanizing the aqueous dispersion for immersion attached to the surface of the mold to obtain a halogenated butyl rubber molded article.

2. The method according to claim 1, further comprising immersing in water a mold in which the aqueous dispersion for immersion is attached between (γ) and (δ).

3. (β): The method according to claim 1, further comprising immersing the mold in an aqueous solution of a coagulant and then drying it to obtain a mold on which the coagulant adheres to the surface.

4. (α): The method according to claim 1, further comprising mixing an aqueous dispersion of halogenated butyl rubber, a stabilizer, sulfur, zinc oxide, and a vulcanization accelerator to obtain an aqueous dispersion for immersion.

5. The method according to claim 1 or 4, wherein the stabilizer comprises an alkali and a thickener, and the vulcanization accelerator comprises a dithiocarbamate and a 2-mercaptobenzothiazole salt.

6. The method according to claim 5, wherein the aqueous dispersion for immersion contains, per 100 parts by mass of halogenated butyl rubber, 0.1 to 2 parts by mass of alkali, 0.1 to 2 parts by mass of a thickener, 0.1 to 10 parts by mass of sulfur, 0.1 to 10 parts by mass of zinc oxide, 0.1 to 10 parts by mass of dithiocarbamate, and 0.1 to 10 parts by mass of 2-mercaptobenzothiazole salt.

7. The method according to claim 4, wherein the aqueous dispersion of halogenated butyl rubber contains halogenated butyl rubber, water, alkali metal hydroxide, and a fatty acid having 10 to 20 carbon atoms or a salt thereof.

8. The method according to claim 4, further comprising preparing an organic solvent solution by dissolving halogenated butyl rubber and a fatty acid having 10 to 20 carbon atoms or a salt thereof in an organic solvent, mixing the organic solvent solution with an aqueous alkali metal hydroxide solution, and then removing the organic solvent to prepare an aqueous dispersion of halogenated butyl rubber.

9. The method according to claim 7 or 8, wherein the fatty acid having 10 to 20 carbon atoms or a salt thereof is oleic acid or a salt thereof.

10. The method according to any one of claims 1 to 4, 7 to 8, wherein the halogenated butyl rubber is brominated butyl rubber.

11. The method according to any one of claims 1 to 4, 7 to 8, wherein the halogenated butyl rubber molded body is a halogenated butyl rubber glove.

12. The method according to any one of claims 1 to 4, 7 to 8, wherein the coagulant is a polyvalent metal salt.

13. The method according to claim 12, wherein the polyvalent metal salt is a calcium salt.

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