JP2008255157A - Dip molding composition and dip molded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dip molding composition giving a dip molded article having low surface resistivity and keeping sufficiently low surface resistivity even by washing the surface of the article with pure water or ultra-pure water. <P>SOLUTION: The dip molding composition contains a rubber latex and a filler containing an organic polymerized inorganic laminar compound holding a polymer of a polymerizable monomer containing an ammonium ion and intercalated between the layers of the inorganic laminar compound, wherein the content of the organic polymerized inorganic laminar compound is 0.3-5 pts.wt. based on 100 pts.wt. of the solid content of the rubber latex. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a dip-molding composition containing rubber latex and a dip-molded product formed by molding the composition, and more particularly, to provide a dip-molded product with reduced surface electrical resistance when used as a dip-molded product. The present invention relates to a dip molding composition and a dip molding product.

  Molded products obtained by dip molding a composition for dip molding consisting of natural rubber latex or acrylonitrile-butadiene copolymer latex are flexible and have sufficient mechanical strength. Used in various fields.

  In such a dip-molded product, a coagulant such as calcium nitrate is attached to the surface of a mold shaped like a hand or a finger, and the mold is immersed in a dip-molding latex composition containing rubber latex (dip dip). Then, the film is pulled up to form a coating film (dip molding layer) on the surface of the mold, and then the dip molding layer is vulcanized (crosslinked) by heating.

  It is important that gloves for manufacturing electronic parts / semiconductor parts have sufficiently high tensile strength and elongation at break and are tightly attached to the hand so that they do not easily loosen or sag even after a long time. . Such properties are realized to some extent by dip-molded products using natural rubber latex. However, natural rubber products have poor resistance to organic solvents and contain proteins, so that there is a problem that it causes allergic reactions although there are differences among individuals, causing itching, rashes, respiratory disorders, and the like. For this reason, attempts have been made to use synthetic rubber latex in order to improve the above disadvantages of such natural rubber latex.

  On the other hand, in gloves for manufacturing precision electronic parts and semiconductor parts, these parts are electrically very fragile, so to avoid the risk of contamination due to discharge due to charging of the glove, adsorption of fine particles, etc. There is also a need for a reduction in surface electrical resistance. Furthermore, in order to remove fine particles adhering to the surface of rubber gloves and metal ions contained in rubber gloves, gloves for manufacturing precision electronic parts and semiconductor parts are generally pre-cleaned with pure water or ultrapure water. However, the surface resistivity of rubber gloves tends to be higher by washing. Therefore, also from such a viewpoint, a rubber glove with reduced surface electrical resistance is required.

In contrast, the present inventor proposed a dip-molded product formed by dip-molding a carboxyl composition-containing conjugated diene rubber latex and a latex composition containing an amphoteric surfactant composed of a weak base and a strong acid. (See Patent Document 1). According to this technique, the surface electrical resistance of the dip-molded product can be reduced to 10 ¹⁰ Ω / cm ² or less. However, on the other hand, in order to meet the recent demand for higher precision in precision electronic parts and semiconductor parts, further reduction in surface electrical resistance of dip-molded products such as rubber gloves used in such applications is desired. In particular, even when washed with pure water or ultrapure water, a material having a characteristic that a sufficiently low surface electric resistance can be maintained is required.

Japanese Patent Laid-Open No. 2004-300386

  The present invention was made in view of such a situation, and when it is a dip-molded product, the surface electrical resistance is low, and even when the surface is washed with pure water or ultrapure water, the surface is sufficiently low. It is an object of the present invention to provide a dip-molding composition that provides a dip-molded article that can maintain electrical resistance, and a dip-molded article that is obtained by dip-molding this dip-molding composition.

  As a result of diligent research to achieve the above object, the present inventor has polymerized a polymerizable ammonium ion-containing monomer as a filler between layers of an inorganic layered compound in a dip molding composition. The inventors have found that the above object can be achieved by including a filler containing an organic polymerized inorganic layered compound intercalated in the resulting polymer, and the present invention has been completed based on this finding.

  That is, according to the present invention, it contains a rubber latex and a filler containing an organic polymerized inorganic layered compound in which a polymer of a polymerizable ammonium ion-containing monomer is intercalated between layers of the inorganic layered compound. And the composition for dip-molding whose content of the said organic polymer-ized inorganic layered compound is 0.3-5 weight part with respect to 100 weight part of solid content of the said rubber latex is provided.

Preferably, the organic polymerized inorganic layered compound has R ¹ NH ₃ ⁺ , R ² R ³ NH ₂ ⁺ , R ⁴ (CH ₃ ) ₃ N ⁺ , and R ⁵ R ⁶ (CH ₃ ) between the layers. A compound in which at least one ammonium ion selected from ₂ N ⁺ is further intercalated.
(However, R ¹ is a saturated hydrocarbon having 8 to 20 carbon atoms, R ² and R ³ are saturated hydrocarbons having 6 to 12 carbon atoms, R ⁴ is a saturated hydrocarbon having 8 to 20 carbon atoms, R ⁵ and R ^6. Is a saturated hydrocarbon having 8 to 20 carbon atoms.)
Preferably, the inorganic layered compound constituting the organic polymerized inorganic layered compound is at least one selected from montmorillonite, saponite, hectorite, beidellite, stevensite, nontronite, vermiculite, halloysite, mica and bentonite. It is.
Preferably, the polymerizable ammonium ion-containing monomer constituting the organic polymerized inorganic layered compound is a compound containing a quaternary ammonium ion represented by the following formula (1).
[CH ₂ = C (R ⁷ ) CH ₂ ] ₂ (R ⁸ ) ₂ N ⁺ (1)
(In the above formula (1), R ⁷ is a hydrogen atom, —CH ₃ or —C ₂ H ₅ , and R ⁸ is —CH ₃ , —C ₂ H ₅ , —C ₃ H ₇ or —, respectively. C ₄ H ₉ )
Preferably, the latex is a carboxyl group-containing conjugated diene rubber latex. More preferably, the carboxyl group-containing conjugated diene rubber latex is a rubber latex further containing a cyano group. Particularly preferably, the carboxyl group-containing conjugated diene rubber constituting the carboxyl group-containing conjugated diene rubber latex is 30 to 99.5% by weight of the conjugated diene monomer, and 0.5% of the carboxyl group-containing ethylenically unsaturated monomer. -20% by weight, and 10-50% by weight of a cyano group-containing ethylenically unsaturated monomer.

  Further, according to the present invention, there is provided a dip-molded product obtained by dip-molding any of the above dip-forming compositions. Preferably, the dip-formed product of the present invention is a glove.

  According to the present invention, the dip-molding composition contains an organic polymerized inorganic layered compound in which a polymer of a polymerizable ammonium ion-containing monomer is intercalated between the layers of the inorganic layered compound as a filler. Therefore, due to the effect of addition of the organic polymerized inorganic layered compound, in the case of a dip-molded product, the insulation can be lowered, and a dip-molded product with low surface electrical resistance can be obtained.

  Moreover, the organic polymerized inorganic layered compound as the filler is a cationic polymer, which is a polymer of a polymerizable ammonium ion-containing monomer intercalated between the layers of the inorganic layered compound. Therefore, even when the dip molded product is used and the surface thereof is washed with pure water or ultrapure water, the polymer of the polymerizable ammonium ion-containing monomer, which is a cationic polymer, is removed from the dip molded product. It has the property of being difficult. As a result, the dip-molded product obtained by dip-molding the dip-molding composition of the present invention maintains a sufficiently low surface electric resistance even when the surface is washed with pure water or ultrapure water. It can be done.

  Hereinafter, the dip-molding composition of the present invention and the dip-molded product of the present invention obtained by dip-molding the composition will be described.

Dip Molding Composition The dip molding composition of the present invention contains at least a rubber latex and a filler containing an organic polymerized inorganic layered compound.
The organic polymerized inorganic layered compound as a filler is a compound obtained by intercalating a polymer obtained by polymerizing a polymerizable ammonium ion-containing monomer between layers of an inorganic layered compound.

Rubber latex Examples of the rubber latex constituting the dip molding composition of the present invention include natural rubber latex and synthetic rubber latex.
Among these, a synthetic rubber latex can be preferably used because various properties of a molded product after dip molding can be arbitrarily adjusted, and a carboxyl group-containing conjugated diene rubber latex can be particularly preferably used.

  A carboxyl group-containing conjugated diene rubber latex preferably used as a rubber latex is a conjugated diene monomer, a carboxyl group-containing ethylenically unsaturated monomer, and other copolymerizable with these added as necessary. It is obtained by emulsion polymerization of a monomer mixture comprising a monomer.

  Although it does not specifically limit as a conjugated diene monomer, The C4-C12 compound containing a conjugated diene is preferable. Examples of such conjugated diene monomers include 1,3-butadiene, isoprene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and chloroprene. And halogen-substituted butadienes. These conjugated diene monomers can be used alone or in combination of two or more. Of these, 1,3-butadiene can be preferably used.

  The carboxyl group-containing ethylenically unsaturated monomer is not particularly limited, but ethylenically unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, cinnamic acid; fumaric acid, maleic acid, itaconic acid, anhydrous Examples thereof include ethylenically unsaturated polyvalent carboxylic acids such as maleic acid and itaconic anhydride and anhydrides thereof; partially esterified products of ethylenically unsaturated polyvalent carboxylic acids such as methyl maleate and methyl itaconic acid; and the like. The carboxy group-containing ethylenically unsaturated monomer can be used as an alkali metal salt or an ammonium salt, or can be used alone or in combination of two or more. Among these, ethylenically unsaturated monocarboxylic acid is preferable, and methacrylic acid can be more preferably used.

  Examples of other copolymerizable monomers include, but are not limited to, for example, cyano group-containing ethylenically unsaturated monomers, aromatic vinyl monomers, ethylenically unsaturated carboxylic acid ester monomers, and ethylenic monomers. And unsaturated carboxylic acid amide monomers.

  Examples of the cyano group-containing ethylenically unsaturated monomer include, but are not limited to, acrylonitrile, methacrylonitrile, fumaronitrile, α-chloroacrylonitrile, α-cyanoethylacrylonitrile, and the like. Of these, acrylonitrile can be preferably used.

  Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, monochlorostyrene, vinyltoluene and the like.

  Examples of the ethylenically unsaturated carboxylic acid ester monomer include methyl acrylate, methyl methacrylate, ethyl acrylate, butyl acrylate, 2-hydroxyethyl acrylate, 3-hydroxypropyl acrylate, and methacrylic acid. Examples include 2-hydroxyethyl, glycidyl acrylate, glycidyl methacrylate, N, N-dimethylaminoethyl (meth) acrylate, and N, N-diethylaminoethyl (meth) acrylate acrylamide.

  Examples of the ethylenically unsaturated carboxylic acid amide monomer include (meth) acrylamide, N-methylol (meth) acrylamide and the like.

In addition to the above monomers, vinyl acetate, vinyl pyrrolidone, vinyl pyridine and the like can be used.
These monomers can be used alone or in combination of two or more.

  In the present invention, it is preferable to use a cyano group-containing ethylenically unsaturated monomer among the other monomers. That is, the rubber latex is preferably a carboxyl group / cyano group-containing conjugated diene rubber latex, whereby a dip-molded product that is flexible and excellent in oil resistance and mechanical strength can be obtained.

When the rubber latex according to the present invention is a carboxyl group / cyano group-containing conjugated diene rubber latex, the amount of each monomer used is preferably in the following range.
That is, the amount of the conjugated diene monomer used is preferably 30 to 89.5% by weight and more preferably 45 to 79% by weight with respect to 100% by weight of the total monomers. The amount of the carboxyl group-containing ethylenically unsaturated monomer used is preferably 0.5 to 20% by weight, more preferably 1 to 15% by weight, based on 100% by weight of the total monomers. The amount of the cyano group-containing ethylenically unsaturated monomer used is preferably 10 to 50% by weight, more preferably 20 to 40% by weight, based on 100% by weight of the total monomers.

Next, a method for producing a rubber latex used in the present invention will be described.
The rubber latex used in the present invention can be produced by emulsion polymerization of a mixture of the above monomers. As the emulsion polymerization method, a conventionally known emulsion polymerization method may be employed. In emulsion polymerization, commonly used polymerization auxiliary materials such as emulsifiers and polymerization initiators can be used.

  The emulsifier is not particularly limited, and examples thereof include an anionic surfactant, a nonionic surfactant, a cationic surfactant, and an amphoteric surfactant. Among these, anionic surfactants such as alkylbenzene sulfonates, aliphatic sulfonates, higher alcohol sulfates, α-olefin sulfonates, and alkyl ether sulfates can be preferably used. The amount of the emulsifier used is preferably 0.5 to 10 parts by weight, more preferably 1 to 8 parts by weight with respect to 100 parts by weight of the total monomers.

  Although it does not specifically limit as a polymerization initiator, A radical polymerization initiator can be used preferably. Examples of such radical polymerization initiators include inorganic peroxides such as sodium persulfate, potassium persulfate, ammonium persulfate, potassium perphosphate, and hydrogen peroxide; t-butyl peroxide, cumene hydroperoxide, p -Mentane hydroperoxide, di-t-butyl peroxide, t-butylcumyl peroxide, acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, dibenzoyl peroxide, 3,5,5-trimethylhexanoyl peroxide Organic peroxides such as oxide and t-butylperoxyisobutyrate; azo compounds such as azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, azobiscyclohexanecarbonitrile, methyl azobisisobutyrate; All Rukoto can. These polymerization initiators can be used alone or in combination of two or more. Among these radical initiators, inorganic peroxides or organic peroxides are preferable, inorganic peroxides are more preferable, and persulfates are particularly preferable. The amount of the polymerization initiator used is preferably 0.01 to 2 parts by weight, more preferably 0.05 to 1.5 parts by weight with respect to 100 parts by weight of the total monomers.

  In the present invention, polymerization auxiliary materials other than those described above may be used as necessary. Examples of such a polymerization auxiliary material include a molecular weight adjusting agent, a chelating agent, a dispersing agent, a pH adjusting agent, an oxygen scavenger, a particle diameter adjusting agent, and the like, and the type and amount used are not particularly limited.

  Emulsion polymerization is usually performed in an aqueous medium using each of the above monomers and each of the polymerization auxiliary materials. The polymerization temperature is not particularly limited, but is usually 0 to 95 ° C, preferably 5 to 70 ° C. After stopping the polymerization reaction, a rubber latex can be obtained by removing unreacted monomers and adjusting the solid content concentration and pH, if desired.

Organic polymerized inorganic layered compound as an organic polymerized inorganic layered compound filler is a polymer obtained by polymerizing a polymerizable ammonium ion-containing monomer between layers of an inorganic layered compound. It is the compound which becomes.

  The inorganic layered compound is not particularly limited, and examples thereof include layered silicate minerals belonging to the genus smectite, and more specifically, montmorillonite, saponite, hectorite, beidellite, stevensite, nontronite, vermiculite. , Halloysite, mica, bentonite and the like.

These inorganic layered compounds may be any of natural, synthetic and processed products. For example, natural smectites include hectorite, saponite, montmorillonite, bentonite, and the like. Synthetic smectite, the composition formula: (Na and / or _{Li) 0.1~1.0 Mg 2.4~2.9 Li 0.0~0.6 Si} 3.5~4.0 O 9.0 _˜10.6 (OH and / or F) Those represented by _1.5 to _2.5 are mentioned. Examples of the synthetic mica include swellable fluorine mica.

  Examples of such inorganic layered compounds include commercially available clay minerals, such as natural bentonite generally called sodium bennite, commercially available products Kunipia, Smecton (manufactured by Kunimine Industries), Veagam (manufactured by Vanderbilt), Laponite (manufactured by Laporte), DM Clean A, DMA-350, Na-Ts (Topy Industries), Bengel (manufactured by Toyoshun Yoko Co., Ltd.), etc. may be used.

  The inorganic layered compound used in the present invention has a large contact surface with a polymerizable ammonium ion-containing monomer and a long-chain hydrocarbon-substituted ammonium salt that is added as necessary to be described later. It is preferable that it can be done. Specifically, as the inorganic layered compound, those having a cation exchange capacity of preferably 10 to 200 milliequivalent / 100 g, more preferably 50 to 180 milliequivalent / 100 g are desirable. If the cation exchange capacity is too low, intercalation of the monomer and ammonium salt between the layers of the inorganic layered compound tends to be insufficient. On the other hand, if the cation exchange capacity is too high, the bonding force of the inorganic layered compound becomes strong, and intercalation of the monomer and ammonium salt between layers becomes difficult. In addition, the cation exchange capacity | capacitance of an inorganic layered compound can be calculated | required by measuring a methylene blue adsorption amount, for example.

  Moreover, as an inorganic layered compound, the aspect-ratio (Z) becomes like this. Preferably it is 50-5000, More preferably, it is 100-5000. The aspect ratio (Z) can be determined according to the formula: Z = L / a, where L is the length of the inorganic layered compound dispersed in the shape and a is the unit thickness. The length L and the unit thickness a can be measured from an electron micrograph.

  For example, Na montmorillonite as an example of the inorganic layered compound is a silicic acid having a sandwich type three-layer structure having a thickness of about 1 nm with two silica tetrahedral layers sandwiched between a magnesium octahedral layer or an aluminum octahedral layer. It has a salt layer, and several layers to several tens of layers are laminated. The silicate layer has a negative charge, and the layers are bonded via an alkali metal cation (Na cation in Na montmorillonite), an alkaline earth metal cation, or the like. .

  In the present invention, as a method for obtaining an organic polymerized inorganic layered compound, first, a polymerizable ammonium ion-containing monomer is intercalated into the inorganic layered compound without polymerization, and then intercalated into the inorganic layered compound. It is preferable to polymerize the polymerizable ammonium ion-containing monomer in the state of being charged.

The polymerizable ammonium ion-containing monomer is not particularly limited as long as it is a compound containing an ammonium ion having a polymerizable substituent. Preferably, a quaternary ammonium ion represented by the following formula (1) is used. The compound to contain is mentioned.
[CH ₂ = C (R ⁷ ) CH ₂ ] ₂ (R ⁸ ) ₂ N ⁺ (1)

In the above formula (1), R ⁷ is a hydrogen atom, —CH ₃ or —C ₂ H ₅ , and R ⁸ is —CH ₃ , —C ₂ H ₅ , —C ₃ H ₇ or —C, respectively. ₄ H ₉ and R ⁸ may be the same as or different from each other. Among the compounds represented by the formula (1), a compound containing diallyldimethylammonium ion [(CH ₂ ═CHCH ₂ ) ₂ (CH ₃ ) ₂ N ⁺ ] is preferable. The compound containing a quaternary ammonium ion as the polymerizable ammonium ion-containing monomer can be usually used in the form of various salts such as a chloride salt, a bromide salt, and a sulfate salt.

  The amount of the polymerizable ammonium ion-containing monomer used is not particularly limited as long as the amount can be sufficiently intercalated in the inorganic layered compound, but the amount of the polymerizable ammonium ion-containing monomer used is not particularly limited. The lower limit is preferably 0.5 equivalent, more preferably 0.7 equivalent, of the cation exchange capacity of the inorganic layered compound. Further, the upper limit of the amount of the polymerizable ammonium ion-containing monomer used is preferably 2 equivalents, more preferably 1.5 equivalents, from the viewpoint of cation exchange efficiency. If the amount of the polymerizable ammonium ion-containing monomer is too small, the exchange of cations becomes insufficient, and the production of the organic polymerized inorganic layered compound tends to be insufficient. On the other hand, if the amount is too large, the amount of polymerizable ammonium ions not involved in cation exchange increases, which tends to be economically disadvantageous.

  In the present invention, in addition to the polymerizable ammonium ion-containing monomer, other monomers that are copolymerized with the polymerizable ammonium ion-containing monomer are used as long as the antistatic effect of the resulting dip-molded product is not impaired. be able to. Such monomers include N-dimethylaminoethyl acrylate, N, N-diethylaminoethyl acrylate, N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl methacrylate, N, N-dimethylacrylamide, N, N N-dimethylaminomethylacrylamide, N, N-dimethylaminoethylacrylamide, N, N-dimethylaminopropylacrylamide, N, N-dimethylmethacrylamide, N, N-dimethylaminomethylmethacrylamide, N, N-dimethylaminoethyl Examples include methacrylamide, N, N-dimethylaminopropyl methacrylamide and the like. These can be used alone or in combination.

  In the present invention, before intercalating a polymerizable ammonium ion-containing monomer into an inorganic layered compound, a predetermined long-chain hydrocarbon-substituted ammonium ion is intercalated in advance into the inorganic layered compound, It is preferable to intercalate the polymerizable ammonium ion-containing monomer in a state where hydrogen-substituted ammonium ions are intercalated. By intercalating long-chain hydrocarbon-substituted ammonium ions into the inorganic layered compound in advance and causing the inorganic layered compound to swell with the long-chain hydrocarbon-substituted ammonium ions, the intercalation of the polymerizable ammonium ion-containing monomer is performed. Can be performed efficiently.

Examples of such a long-chain hydrocarbon-substituted ammonium ion include R ¹ NH ₃ ⁺ , R ² R ³ NH ₂ ⁺ , R ⁴ (CH ₃ ) ₃ N ⁺ , and R ⁵ R ⁶ (CH ₃ ) ₂ N ^+. There may be mentioned at least one ammonium ion selected. Here, R ¹ is a saturated hydrocarbon having 8 to 20 carbon atoms, preferably 10 to 18 carbon atoms, R ² and R ³ are saturated hydrocarbons having 6 to 12 carbon atoms, preferably 8 to 12 carbon atoms, R ⁴ Is a saturated hydrocarbon having 8 to 20 carbon atoms, preferably 10 to 18 carbon atoms, and R ⁵ and R ⁶ are saturated hydrocarbons having 8 to 20 carbon atoms, preferably 10 to 18 carbon atoms.

As the ammonium ion to be intercalated in advance with the inorganic layered compound, when a saturated hydrocarbon group (R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ ) having a small carbon number is used, Swelling becomes insufficient, and as a result, when the polymerizable ammonium ion-containing monomer is added thereafter, the intercalation of the polymerizable ammonium ion-containing monomer into the inorganic layered compound becomes insufficient. Invention It becomes difficult to obtain a predetermined organic polymerized inorganic layered compound. On the other hand, when the number of carbons is too large, the hydrophobicity of ammonium ions becomes too high, so that the solubility in a solvent is lowered, and similarly, it becomes difficult to intercalate with an inorganic layered compound. It becomes difficult to obtain a polymerized inorganic layered compound.

  In the case of using a long-chain hydrocarbon-substituted ammonium ion, at least a part of the used long-chain hydrocarbon-substituted ammonium ion is usually an organic polymer together with a polymer of a polymerizable ammonium ion-containing monomer. It remains in an intercalated state in the fluorinated inorganic layered compound. In this case, the residual amount of the long-chain hydrocarbon-substituted ammonium ions is preferably 50 parts by weight or less, more preferably 30 parts by weight or less with respect to 100 parts by weight of the polymer of the polymerizable ammonium ion-containing monomer.

Examples of ammonium ions represented by R ¹ NH ₃ ⁺ or R ² R ³ NH ₂ ⁺ include amines represented by R ¹ NH ₂ or R ² R ³ NH, and acids such as hydrochloric acid, sulfuric acid, and nitric acid. It can be used as an ammonium ion and used in the form of these salts. Examples of the amine represented by R ¹ NH ₂ or R ² R ³ NH include octylamine, 2-ethylhexylamine, dodecylamine, octadecylamine, dihexylamine, dioctylamine, didecylamine, didodecylamine and the like. In R ² R ³ NH ₂ ⁺ , R ² and R ³ may be saturated hydrocarbons having the same carbon number or may be saturated hydrocarbons having different carbon numbers.

Examples of ammonium ions represented by R ⁴ (CH ₃ ) ₃ N ⁺ or R ⁵ R ⁶ (CH ₃ ) ₂ N ⁺ include, for example, various salt forms such as chloride salts, bromide salts, and sulfate salts. Can be used. Such salts include octyl trimethyl ammonium salt, decyl trimethyl ammonium salt, dodecyl trimethyl ammonium salt, octadecyl trimethyl ammonium salt, dioctyl dimethyl ammonium salt, didecyl dimethyl ammonium salt, didodecyl dimethyl ammonium salt, dioctadecyl dimethyl ammonium salt, etc. Is mentioned. In R ⁵ R ⁶ (CH ₃ ) ₂ N ⁺ , R ⁵ and R ⁶ may be saturated hydrocarbons having the same carbon number or may be saturated hydrocarbons having different carbon numbers.

  The amount used in the case of intercalating the long-chain hydrocarbon-substituted ammonium ion in advance is not particularly limited as long as it is an amount capable of sufficiently swelling the inorganic layered compound. It may be equivalent to the amount used by the body.

  The size of the organic polymerized inorganic layered compound is not particularly limited, but it is preferable that the average thickness is 1 to 50 nm and the average diameter is 50 to 1000 nm.

  The organic polymerized inorganic layered compound according to the present invention is preferably produced by the following method using the salt of the long-chain hydrocarbon-substituted ammonium ion.

That is, first, a salt of a long-chain hydrocarbon-substituted ammonium ion is reacted with an inorganic layered compound.
As a method of reacting these, for example, (1) a method of reacting by adding an inorganic layered compound in a solvent in which a long-chain hydrocarbon-substituted ammonium salt is dissolved, and (2) a long-chain hydrocarbon-substituted ammonium salt Examples thereof include a method of softening or melting and then reacting by adding an inorganic layered compound therein.

  According to the above method (1), the long-chain hydrocarbon-substituted ammonium salt can be intercalated in the form of ions between the inorganic layered compounds at room temperature. In this method, as a solvent to be used, for example, various organic solvents can be used in addition to water. In the method (2), it is necessary to heat to a temperature higher than the softening temperature or melting temperature of the long-chain hydrocarbon-substituted ammonium salt. This heating is desirably performed at a temperature at which the long-chain hydrocarbon-substituted ammonium salt and the inorganic layered compound are not decomposed and at a temperature at which they stably exist. For example, the heating temperature is 250 ° C. or less.

  Then, by adding a polymerizable ammonium ion-containing monomer to the reaction product obtained above and stirring at a temperature of 20 to 95 ° C. for 0.5 to 24 hours, between the layers of the inorganic layered compound, The polymerizable ammonium ion-containing monomer is intercalated in the form of ions.

  Next, the polymerizable ammonium ion-containing monomer is polymerized in a state where the polymerizable ammonium ion-containing monomer is intercalated in the form of ions between the layers of the inorganic layered compound. The polymerization method of the polymerizable ammonium ion-containing monomer is not particularly limited. For example, as a polymerization initiator, ammonium persulfate, potassium persulfate, tertiary butyl hydroperoxide, or the like is used. It can superpose | polymerize by making it react in 1 to 24 hours. The addition method of the polymerization initiator may be any of a batch type, a split type, and a continuous type. In this way, an organic polymerized inorganic layered compound can be produced.

  The molecular weight (Mw) of the polymer of the polymerizable ammonium ion-containing monomer in the organic polymerized inorganic layered compound is preferably 2,000 to 1,000,000, more preferably 5,000 to 500,000. 000. In addition, the polymer obtained by polymerizing the polymerizable ammonium ion-containing monomer in the organic polymerized inorganic layered compound is usually intercalated between the layers of the inorganic layered compound in the form of ions. Become.

  The content of the organic polymerized inorganic layered compound in the dip molding composition of the present invention is 0.3 to 5 parts by weight, preferably 0.5 parts per 100 parts by weight of the solid content of the rubber latex. ~ 4 parts by weight. If the content of the organic polymerized inorganic layered compound is too small, the effect of improving the surface electrical resistance of the resulting dip-molded product becomes insufficient. On the other hand, if the amount is too large, the tensile strength and elongation at break will deteriorate.

Crosslinking agent The dip molding composition of the present invention preferably further contains a crosslinking agent in order to crosslink the rubber latex described above.
Although it does not specifically limit as a crosslinking agent, Organic peroxide; Sulfur, such as powder sulfur, sulfur white, precipitation sulfur, colloidal sulfur, surface treatment sulfur, insoluble sulfur; Hexamethylenediamine, triethylenetetramine, tetraethylenepentamine, etc. Of polyamines; and the like. Of these, organic peroxides or sulfur are preferable.

  The content of the crosslinking agent is preferably 0.01 to 10 parts by weight, more preferably 0.05 to 4 parts by weight, particularly preferably 0.1 to 100 parts by weight of the solid content in the dip molding composition. ~ 2 parts by weight. If the content of the cross-linking agent is too small, the molding tends to be insufficient, and if too much, the texture and tensile strength tend to be inferior.

  The organic peroxide exhibits solid properties at normal pressure and 30 ° C., and has a 10-hour half-life temperature of preferably 150 ° C. or less, more preferably 130 ° C. or less, particularly preferably 40 ° C. or more, 120 ° C. The following is desirable. The 10-hour half-life temperature means a temperature at which the amount of the organic peroxide that retains activity becomes half when the organic peroxide is heated at that temperature for 10 hours. That is, for example, an organic peroxide having a 10-hour half-life temperature of 100 ° C. has a property that when heated at 100 ° C. for 10 hours, the amount of the organic peroxide retaining activity is halved. Have

  Examples of such organic peroxides include dibenzoyl peroxide, benzoyl (3-methylbenzoyl) peroxide, di (4-methylbenzoyl) peroxide, dilauroyl peroxide, distearoyl peroxide, and di-α. -Cumyl peroxide, 1,1-bis (t-butylperoxy) cyclododecane, succinic acid peroxide, bis (4-t-butylcyclohexyl) peroxydicarbonate, t-butylperoxymaleic acid, etc. Can be mentioned. These can be used alone or in combination of two or more.

  Moreover, when using sulfur as a crosslinking agent, it is preferable to mix | blend a crosslinking accelerator (vulcanization accelerator) and a zinc oxide. As the crosslinking accelerator (vulcanization accelerator), those usually used in dip molding can be used. The usage-amount of a crosslinking accelerator is 0.1-10 weight part normally with respect to 100 weight part of solid content in the latex for dip molding, Preferably it is 0.2-4 weight part. The amount of zinc oxide used is usually 5 parts by weight or less, preferably 2 parts by weight or less, based on 100 parts by weight of the solid content in the dip molding latex.

Dip-molded product The dip-molded product of the present invention is obtained by dip-molding the above-described dip-molding composition of the present invention. As the dip-molding method, a conventionally known method can be adopted, and examples thereof include a direct dipping method, an anode adhesion dipping method, and a teag adhesion dipping method. Among these, the anode coagulation dipping method is preferable in that it is easy to obtain a dip-formed product having a uniform thickness. Hereinafter, a dip molding method using an anode adhesion dipping method as one embodiment will be described.

  First, the dip mold is immersed in a coagulant solution, and the coagulant is attached to the surface of the dip mold. Various materials such as porcelain, glass, metal, and plastic can be used as the dip mold. The shape of the mold may be adapted to the shape of the dip molded product that is the final product.

  The coagulant solution is a solution in which a coagulant such as a salting-out agent is dissolved in water, alcohol, or a mixture thereof. Metal halides such as barium chloride, calcium chloride, magnesium chloride, zinc chloride and aluminum chloride; nitrates such as barium nitrate, calcium nitrate and zinc nitrate; acetates such as barium acetate, calcium acetate and zinc acetate; calcium sulfate and magnesium sulfate And sulfates such as aluminum sulfate. The concentration of the coagulant in the coagulant solution is preferably 5 to 70% by weight, more preferably 15 to 50% by weight.

  Next, the dip molding die to which the coagulant is adhered is immersed in the dip molding composition of the present invention described above, and then the dip molding die is pulled up to form a dip molding layer on the dip molding die.

  Next, the dip molding layer formed on the dip molding die is heated to crosslink the rubber (coagulated product of rubber latex) constituting the dip molding layer. The heating temperature is preferably 100 to 150 ° C. If the temperature is too low, the crosslinking reaction may take a long time, which may reduce productivity. On the other hand, if it is too high, the oxidative deterioration of the rubber (coagulated product of rubber latex) constituting the dip-molded layer is promoted and the physical properties of the molded product may be lowered. The heat treatment time may be appropriately selected depending on the heat treatment temperature, but is usually 10 to 120 minutes. The heating method is not particularly limited. For example, an external heating method using infrared rays or hot air or an internal heating method using high frequency can be employed. Of these, heating with hot air is preferred.

  In the present invention, before heat-treating the dip-molded layer, the dip-molded layer is immersed in warm water at 20 to 80 ° C. for about 0.5 to 60 minutes, and water-soluble impurities (emulsifier, water-soluble polymer, It is preferable to remove a coagulant and the like.

Next, the dip-molded layer crosslinked by heat treatment is removed from the dip-molding die to obtain a dip-molded product. As a demolding method, a method of peeling from a mold by hand, a method of peeling by water pressure or compressed air pressure, and the like can be adopted.
After demolding, a heat treatment (post-crosslinking step) may be performed at a temperature of 60 to 120 ° C. for 10 to 120 minutes.

  In addition, when the dip-formed product is a glove, inorganic or organic fine particles such as talc, calcium carbonate, starch particles, etc. are used in order to prevent the dip-formed products from sticking to each other at the contact surface and to improve slippage during attachment / detachment. May be dispersed on the surface of the glove, an elastomer layer containing these fine particles may be formed on the surface of the glove, or the surface layer of the glove may be chlorinated.

  The dip-molded product of the present invention thus obtained is formed by dip-molding the dip-molding composition of the present invention, so that the surface electrical resistance is low. Even when washed with pure water, a sufficiently low surface electrical resistance can be maintained.

  Such a dip-molded product of the present invention can have a thickness of about 0.1 to about 3 mm, particularly 0.1 to 0.3 mm. It can be used suitably. Specifically, nipples for baby bottles; medical supplies such as syringes, conduits, and water pillows; toys and exercise equipment such as balloons, dolls, and balls; industrial articles such as pressure forming bags and gas storage bags; It can be suitably used for household, agricultural, fishery and industrial gloves; finger sack; and the like. In particular, the dip-molded product of the present invention can be suitably used for gloves for manufacturing precision electronic parts and semiconductor parts, taking advantage of the above characteristics. In addition, when using the dip molded product of this invention as a glove, it may be a support type or an unsupport type.

  The present invention will be specifically described below with reference to examples and comparative examples. [Part] and [%] in these examples are based on weight unless otherwise specified. However, the present invention is not limited only to these examples. Each characteristic is evaluated by the following method.

A dumbbell-shaped test piece is prepared from a 300% tensile stress, tensile strength, and stretch dip-formed product (rubber glove) using dumbbells (Die-C) according to ASTM D-412. Next, the test piece is pulled at a tensile speed of 500 mm / min, and the tensile stress (MPa) when the elongation is 300%, the tensile strength (MPa) at break, and the elongation (%) at break are measured. In this example, each characteristic was evaluated according to the following criteria. Examples that satisfy the following criteria are indicated by “◯” in Table 2, and examples that do not satisfy the following criteria are shown in Table 2. Indicated by “x”.
In other words, in this example, 300 MPa tensile stress is 3.5 MPa or less, tensile strength is 20 MPa or more, and elongation at break is 600% or more, which are the reference values.

Surface electrical resistivity (surface electrical resistivity after immersion in ultrapure water)
A 10 cm square test piece was cut out from the palm of the palm of the dip-formed product (rubber gloves), and this test piece was immersed in 500 ml of ultrapure water having a specific resistance of 18.3 MΩcm at 30 ° C. for 2 hours. The test piece is pulled up from the ultrapure water and dried at 70 ° C. Next, the dried test piece is left in a constant temperature / humidity chamber at 20 ° C. and a relative humidity of 65% for 12 hours, and then, under the same atmosphere, in accordance with ASTM D257-93, at a measurement voltage of 250 V, Measure the surface electrical resistivity. The results are shown in Table 2. In Table 2, for example, 10 ⁷ to 10 ⁸ Ω / cm ² indicates that the surface electrical resistivity falls within this range.

Example 1
Production of copolymer latex In a nitrogen-substituted polymerization reactor, 27 parts of acrylonitrile, 67.5 parts of 1,3-butadiene, 5.5 parts of methacrylic acid, 0.3 part of t-dodecyl mercaptan (TDM), 132 parts of soft water , 3.0 parts of sodium dodecylbenzenesulfonate, 0.5 parts of β-naphthalenesulfonic acid formalin condensate sodium salt, 0.3 part of potassium persulfate and 0.05 part of sodium ethylenediaminetetraacetate were added, and the polymerization temperature was 37. The polymerization is started by maintaining the temperature. When the polymerization conversion is 60%, 0.15 part of t-dodecyl mercaptan is added and the polymerization temperature is raised to 40 ° C., and then when the polymerization conversion is 80%, t-dodecyl mercaptan 0.15 is added. Part is added to continue the polymerization reaction, and the reaction is continued until the polymerization conversion rate reaches 94%. Thereafter, 0.1 part of sodium dimethyldithiocarbamate is added as a polymerization terminator to terminate the polymerization reaction to obtain a copolymer latex.
Then, after removing unreacted monomers from the copolymer latex, the pH and solid content concentration of the copolymer latex are adjusted to obtain an acrylonitrile-butadiene-methacrylic acid copolymer having a solid content concentration of 40% and a pH of 8.5. A coalesced latex is obtained.

Production of Organic Polymerized Inorganic Layered Compound First, a compound in which a long chain hydrocarbon-substituted ammonium ion is intercalated into an inorganic layered compound is prepared by the following method.
That is, Na montmorillonite (cation capacity 115 meq./100 g) as an inorganic layered compound is prepared, 160 g of Na montmorillonite is dispersed in 10 liters of water at 80 ° C., and stirred for 1 hour to obtain a montmorillonite dispersion. Next, 3 liters of an aqueous solution containing 42.20 g of dodecylamine and 83.2 g of hydrochloric acid having a concentration of 10% is added to the montmorillonite dispersion and further stirred at the same temperature (80 ° C.) for 1 hour. Then, after cooling to room temperature, the precipitate is filtered and washed, water is added again so that the solid content concentration becomes 10%, the temperature is raised to 80 ° C., and the mixture is stirred for 1 hour to sufficiently swell montmorillonite. A compound (hereinafter referred to as “ammonium swollen montmorillonite”) in which a long-chain hydrocarbon-substituted ammonium salt is intercalated in the form of ions to a layered compound is obtained. In this example, the content of dodecylammonium ions produced by the reaction of dodecylamine and hydrochloric acid is 1.24 equivalents relative to the cation exchange capacity of Na montmorillonite.

Next, an organic polymerized inorganic layered compound is prepared using the ammonium-swelled montmorillonite obtained above.
That is, 1000 g of the aqueous dispersion of ammonium-swelled montmorillonite is stirred at 80 ° C. for 1 hour. Then, 133 g of a 60% solution of diallyldimethylammonium chloride is added to the stirred solution, and further stirred at 80 ° C. for 1 hour, the temperature of the reaction solution is set to 70 ° C., and 5 g of 25% ammonium persulfate aqueous solution is added to the reaction solution. Add dropwise over time. And after completion | finish of dripping, an organic-polymerization inorganic layered compound is obtained by continuing reaction for 2 hours.

Production of Dip Molding Composition Into 250 parts of the acrylonitrile-butadiene-methacrylic acid copolymer latex obtained above (100 parts in terms of solid content), 1.0 part of sulfur and zinc diethyldithiocarbamate as a vulcanization accelerator .5 parts and 1.0 part of zinc oxide are blended. Then, 12.6 parts (2 parts in terms of solid content) of the organic polymerized inorganic layered compound obtained above are added, and then an aqueous potassium hydroxide solution is added to adjust the pH to 9.5. Further, by adding water to adjust the solid content concentration to 30%, a dip molding composition is obtained.

Manufacture of Dip Molded Product (Rubber Gloves) A glove mold heated to 60 ° C. is immersed in a 25% calcium nitrate aqueous solution (coagulant solution), and then dried at 60 ° C. for 10 minutes to attach a coagulant. Next, the glove mold to which the coagulant is adhered is dipped in the dip molding composition obtained above for 10 seconds to form a dip molding layer on the glove mold. Then, after leaching with deionized water at 40 ° C. for 5 minutes and drying at 60 ° C. for 10 minutes, the dip-formed layer is vulcanized at 120 ° C. for 20 minutes. Finally, the obtained vulcanizate is desorbed while being inverted from the hand mold to obtain a dip-formed product (rubber glove).

  And about each dip molded article obtained as mentioned above, each evaluation of the surface electrical resistivity after 300% tensile stress, tensile strength, elongation, and ultrapure water immersion is performed by the said method. The results are shown in Table 2.

Examples 2 to 6, Comparative Examples 1 and 2
When preparing the organic polymerized inorganic layered compound as the filler, each amine compound shown in Table 1 was used instead of 42.20 parts of dodecylamine as a compound constituting the long-chain hydrocarbon-substituted ammonium ion. A dip-molding composition and a dip-molded product are produced in the same manner as in Example 1 except that they are used in the addition amount shown in FIG. The results are shown in Table 2.
In Examples 2 to 6, the filler contained in the dip-molding composition and the dip-molded product was prepared by intercalating the polymer of the polymerizable ammonium ion-containing monomer of the present invention in the inorganic layered compound. Configuration. On the other hand, in Comparative Examples 1 and 2, intercalation of the polymer of the polymerizable ammonium ion-containing monomer into the inorganic layered compound hardly occurs.

Examples 7 to 11 and Comparative Examples 3 and 4
When preparing an organic polymerized inorganic layered compound as a filler, instead of 42.20 parts dodecylamine and 83.2 parts hydrochloric acid having a concentration of 10% as a compound constituting a long-chain hydrocarbon-substituted ammonium ion, A dip-molding composition and a dip-molded product are produced in the same manner as in Example 1 except that each ammonium salt shown in Table 1 is used in the addition amount shown in Table 1, and evaluated in the same manner as in Example 1. The results are shown in Table 2.
In Examples 7 to 11, the filler contained in the dip-molding composition and the dip-molded product was prepared by intercalating a polymer of the polymerizable ammonium ion-containing monomer of the present invention in the inorganic layered compound. Configuration. On the other hand, in Comparative Examples 3 and 4, the polymer intercalation of the polymerizable ammonium ion-containing monomer into the inorganic layered compound hardly occurs.

Examples 12-14, Comparative Examples 5-7
Except for changing the amount of the organic polymerized inorganic layered compound as a filler used in the preparation of the dip-molding composition from 2 parts to the amounts shown in Table 2, the same as in Example 1, A dip-molding composition and a dip-molded product are produced and evaluated in the same manner as in Example 1. The results are shown in Table 2. Comparative Example 5 is an example in which no organic polymerized inorganic layered compound is added.

  In Table 2, in the dip-molding composition and dip-molded product, the inorganic layered compound is present in a state where the polymer of the polymerizable ammonium ion-containing monomer of the present invention is intercalated between the layers. Whether or not there is an organic polymerized inorganic layered compound in the dip-molding composition and the dip-molded product is also shown. In this example, the presence of the organic polymerized inorganic layered compound is evaluated as “existing” if it can be clearly confirmed, while the presence of almost no confirmation is evaluated as “not present”. The results are shown in Table 2.

  As shown in Table 2, by containing a predetermined amount of the organic polymerized inorganic layered compound according to the present invention, while maintaining good 300% tensile stress, tensile strength and elongation (300% tensile stress is 3.5 MPa or less) Further, the tensile strength is 20 MPa or more, the breaking elongation is 600% or more), and the surface electrical resistivity after immersion in ultrapure water can be lowered (Examples 1 to 11 and Examples 12 to 14).

  On the other hand, when an inorganic layered compound and a polymerizable ammonium ion-containing monomer are used but the organic polymerized inorganic layered compound is not formed, the surface electrical resistivity after immersion in ultrapure water is increased. (Comparative Examples 1-4).

  In addition, as this reason, in these comparative examples 1-4, since the polymer of the polymerizable ammonium ion containing monomer which is a cationic polymer is not intercalated to the inorganic layered compound, It is considered that the polymer of the polymerizable ammonium ion-containing monomer, which is a cationic polymer, was removed when immersed in water. The reason why the polymer of a polymerizable ammonium ion-containing monomer that is a cationic polymer does not intercalate with the inorganic layered compound, that is, the reason why the organic polymerized inorganic layered compound is not formed is This is considered to be due to insufficient swelling of the amine or ammonium salt used before adding the ammonium ion-containing monomer into the inorganic layered compound.

  Further, when the organic polymerized inorganic layered compound is not added or when the addition amount is too small, the effect of reducing the surface electrical resistivity after immersion in ultrapure water cannot be obtained (Comparative Examples 5 and 6). Furthermore, when there is too much addition amount of an organic polymerized inorganic layered compound, 300% tensile stress, tensile strength, and elongation will deteriorate (Comparative Example 7).

Claims (9)

Rubber latex,
A filler containing an organic polymerized inorganic layered compound in which a polymer of a polymerizable ammonium ion-containing monomer is intercalated between layers of the inorganic layered compound,
The dip-molding composition, wherein the content of the organic polymerized inorganic layered compound is 0.3 to 5 parts by weight with respect to 100 parts by weight of the solid content of the rubber latex. The organic polymerized inorganic layered compound has R ¹ NH ₃ ⁺ , R ² R ³ NH ₂ ⁺ , R ⁴ (CH ₃ ) ₃ N ⁺ , and R ⁵ R ⁶ (CH ₃ ) ₂ N ⁺ between the layers. The dip molding composition according to claim 1, wherein at least one ammonium ion selected from is a compound further intercalated.
(However, R ¹ is a saturated hydrocarbon having 8 to 20 carbon atoms, R ² and R ³ are saturated hydrocarbons having 6 to 12 carbon atoms, R ⁴ is a saturated hydrocarbon having 8 to 20 carbon atoms, R ⁵ and R ^6. Is a saturated hydrocarbon having 8 to 20 carbon atoms.)   The inorganic layered compound constituting the organic polymerized inorganic layered compound is at least one selected from montmorillonite, saponite, hectorite, beidellite, stevensite, nontronite, vermiculite, halloysite, mica and bentonite. Item 3. The composition for dip molding according to Item 1 or 2. 4. The polymerizable ammonium ion-containing monomer constituting the organic polymerized inorganic layered compound is a compound containing a quaternary ammonium ion represented by the following formula (1). The composition for dip molding as described in 2.
[CH ₂ = C (R ⁷ ) CH ₂ ] ₂ (R ⁸ ) ₂ N ⁺ (1)
(In the above formula (1), R ⁷ is a hydrogen atom, —CH ₃ or —C ₂ H ₅ , and R ⁸ is —CH ₃ , —C ₂ H ₅ , —C ₃ H ₇ or —, respectively. C ₄ H ₉ )   The dip molding composition according to any one of claims 1 to 4, wherein the latex is a carboxyl group-containing conjugated diene rubber latex.   The composition for dip molding according to claim 5, wherein the carboxyl group-containing conjugated diene rubber latex is a rubber latex further containing a cyano group.   The carboxyl group-containing conjugated diene rubber latex constituting the carboxyl group-containing conjugated diene rubber latex is conjugated diene monomer 30 to 89.5% by weight, carboxyl group-containing ethylenically unsaturated monomer 0.5 to 20% by weight. And a composition for dip molding according to claim 5 or 6, which is obtained by copolymerizing 10 to 50% by weight of a cyano group-containing ethylenically unsaturated monomer.   A dip-molded product obtained by dip-molding the dip-molding composition according to claim 1.   The dip-molded product according to claim 8, which is a glove.