WO2007026704A1

WO2007026704A1 - Composition for dip molding and dip molded product

Info

Publication number: WO2007026704A1
Application number: PCT/JP2006/316996
Authority: WO
Inventors: Misao Aida; Osamu Ishizu; Hisanori Ota
Original assignee: Zeon Corporation
Priority date: 2005-08-31
Filing date: 2006-08-29
Publication date: 2007-03-08
Also published as: JPWO2007026704A1; JP5380839B2

Abstract

Disclosed is a composition for dip molding containing a copolymer latex obtained by copolymerizing 100 parts by weight of a monomer mixture containing 34-60 parts by weight of a conjugated diene monomer, 39-65 parts by weight of an aromatic vinyl monomer and 1-10 parts by weight of an ethylenically unsaturated acid monomer. This composition for dip molding is characterized in that when the copolymer constituting the copolymer latex is dipped in toluene at 20˚C for 24 hours, the toluene insoluble fraction of the copolymer is not less than 30% by weight relative to 100% by weight of the copolymer as a whole. This composition for dip molding has good releasability from molding dies while exhibiting sufficient tensile strength and elongation at break. In addition, this composition enables to obtain a dip molded product having excellent ethanol resistance.

Description

DIP MOLDING COMPOSITION AND DIP MOLDED ARTICLE

Technical field

[0001] The present invention relates to a dip-molding composition and a dip-molded article. More specifically, the present invention has a good releasability from a molding die, sufficient tensile strength and elongation at break, and Dip molding composition that can give dip molded products with excellent ethanol resistance

And a dip-molded product obtained by dip-molding this dip-molding composition.

Background art

[0002] A molded product obtained by dip molding a composition for dip molding such as natural rubber latex or synthetic rubber latex is flexible and has sufficient mechanical strength. In addition to household use, it is widely used in various industries such as the food industry and electronic component manufacturing industry, and also for medical use.

Such a rubber glove (dip-molded product) is particularly required to be not easily torn during wearing (sufficient tensile strength and elongation at break) in order to protect the hand safely. At the same time, many disposable rubber gloves are required to be resistant to ethanol (ethanol resistance) because they are used by first disinfecting ethanol after being worn on the hand.

[0004] A dip-molded product used for such rubber gloves is usually manufactured by the following method. That is, first, a coagulant such as calcium chloride is attached to the surface of a mold shaped like a hand or a finger, and the above-mentioned mold is immersed in a dip molding composition containing rubber latex (dip). To do. Next, the film is pulled up to form a coating film (dip-molded layer) on the surface of the mold, and then the dip-molded layer is vulcanized (crosslinked) by heating. However, rubber gloves (dip molded products) produced in this way tend to adhere to molds that are highly sticky, so that it is often difficult to remove them from the mold (release). was there. For this reason, it is also required that the mold force is easy to detach (that is, good releasability), that is, it is not in close contact with the mold (low adhesion). [0005] Conventionally, as such rubber gloves, those obtained by dip molding natural rubber latex have been frequently used. However, natural rubber latex gloves may cause allergies, depending on the user, due to minute amounts of protein components in the rubber component. Therefore, synthetic rubber latex gloves that do not have such concerns have been proposed.

[0006] For example, Patent Document 1 discloses a carboxy-modified conjugated gen-based rubber latex having a glass transition temperature of 50 ° C or lower, and a glove force obtained by dip molding this latex. While the glove described in this document is excellent in flexibility and elongation at break, it has a problem that it is inferior in tensile strength and easily adheres to a mold.

[0007] Further, Patent Document 2 discloses a copolymer obtained by emulsion copolymerization of an aromatic butyl monomer, a conjugation monomer and an unsaturated acid monomer, and having a gel content (indicating the level of internal crosslinking) of a specific value or less. A polymer latex and a glove obtained by dip molding this latex are disclosed. The purpose of this document is to obtain a glove with excellent tensile strength. However, the tensile strength is still insufficient, and the strength is inferior to ethanol resistance and releasability from molded molds. there were.

[0008] Furthermore, Patent Document 3 is characterized in that it is formed from a carboxyl-cleaved chain aliphatic gen-Z acrylonitrile Z (meth) acrylic acid ester terpolymer. Latex gloves with improved properties are disclosed. This document aims to improve the slipperiness between the glove surfaces, but on the other hand, there is a problem that the elongation at break is insufficient and the ethanol resistance is inferior.

Patent Document 1: U.S. Pat.No. 5,910,533

Patent Document 2: U.S. Patent 6,627,325

Patent Document 3: Japanese Patent Publication No. 6-70143

Disclosure of the invention

Problems to be solved by the invention

[0009] The present invention has been made in view of such a situation, has good releasability from a mold, has sufficient tensile strength and elongation at break, and shika is also excellent in ethanol resistance. It is an object of the present invention to provide a dip-forming composition that can provide a dip-formed product. Also, Another object of the present invention is to provide a dip-molded product obtained by dip-molding such a dip-molding composition and having the above characteristics.

Means for solving the problem

[0010] As a result of diligent studies to achieve the above object, the present inventors have found that a monomer containing a conjugation monomer, an aromatic butyl monomer, and an ethylenically unsaturated acid monomer. The mass mixture

Then, the ratio of these monomers is set within a predetermined range, and the amount of insoluble toluene in the case where the copolymer constituting the copolymer latex is immersed in toluene under predetermined conditions is also determined. The inventors have found that the above-described object can be achieved by controlling to a specific value or more, and have completed the present invention.

[0011] That is, the dip molding composition according to the present invention comprises:

Monomer mixture comprising 34-60 parts by weight of conjugation monomer, 39-65 parts by weight of aromatic vinyl monomer, and 1-: LO part by weight of ethylenically unsaturated acid monomer 100 A dip-molding composition having a copolymer latex obtained by copolymerizing parts by weight, wherein the copolymer constituting the copolymer latex is placed in toluene at a temperature of 20 ° C for 24 hours. The toluene-insoluble content of the copolymer when immersed for 30 minutes is 30% by weight or more with respect to 100% by weight of the entire copolymer.

[0012] Preferably, the conjugation monomer is 1,3-butadiene, isoprene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene. Group, consisting of 1,3-pentadiene and black-opened plane, at least one selected, more preferably 1,3-butadiene and Z or isoprene, more preferably 1,3-butadiene. .

Preferably, the aromatic bur monomer is composed of styrene, α-methyl styrene, ρ-methyl styrene, ρ-phenyl styrene, ρ-methoxy styrene, chloromethyl styrene, m-fluoro styrene, and urnaphthalene. At least one selected, and more preferably styrene.

Preferably, the ethylenically unsaturated acid monomer is an ethylenically unsaturated monocarboxylic acid monomer, an ethylenically unsaturated polyvalent carboxylic acid monomer, or an ethylenically unsaturated polyvalent carboxylic acid monomer. It is at least one selected from the group power consisting of an acid anhydride, an ethylenically unsaturated polycarboxylic acid partial ester monomer and an ethylenically unsaturated sulfonic acid monomer, more preferably an ethylenically unsaturated monocarboxylic acid More preferred is methacrylic acid.

[0013] The dip molding composition of the present invention preferably further contains a crosslinking agent. More preferably, the crosslinking agent is at least one selected from the group consisting of sulfur, organic peroxides and polyamines, and more preferably sulfur. The amount of the crosslinking agent is preferably 0.1 to 3 parts by weight with respect to 100 parts by weight of the solid content in the dip molding composition.

The dip molding composition of the present invention preferably further contains a crosslinking accelerator. The blending amount of the crosslinking accelerator is preferably 0.1 to 2 parts by weight with respect to 100 parts by weight of the solid content in the dip molding composition.

The dip molding composition of the present invention preferably further contains acid zinc. It is preferable that the amount of the zinc oxide zinc is 0.3 to 3 parts by weight with respect to 100 parts by weight of the solid content in the dip molding composition.

The dip molding composition of the present invention preferably has a pH of 8.5-12.

[0014] In the dip molding composition of the present invention, preferably, the dip molding film is formed when a metal plate is immersed in the dip molding composition to form a dip molding film on the metal plate. The value of the 180 ° peel test of the molded film is 4.9 (NZ25mm) or less.

[0015] A dip-molded product according to the present invention is a dip-molded product obtained by dip molding the above dip molding composition.

The dip-formed product of the present invention preferably has a tensile strength measured in accordance with ASTM D-412 of 2 OMPa or more and an elongation at break of 600% or more.

Further, the dip-molded product of the present invention preferably has a tensile strength of 16 MPa or more measured at a tensile speed of 500 mmZ after being immersed in ethanol at a temperature of 20 ° C. for 1 hour.

The invention's effect

[0016] According to the present invention, the copolymer latex to be contained in the dip-molding composition comprises the above conjugate monomer, aromatic vinyl monomer, and ethylenically unsaturated acid monomer. did The monomer mixture contained in the range is formed by copolymerization, and the toluene-insoluble content of the copolymer constituting the copolymer latex is set in the predetermined range. Therefore, it is possible to obtain a dip-molded product that has good releasability from the mold during production, has sufficient tensile strength and elongation at break, and is excellent in ethanol resistance. In particular, it is possible to improve productivity by making the mold release property good. Also, by improving the ethanol resistance, for example, when a dip-molded product is used for rubber gloves and sterilized with ethanol, tearing of the gloves during use can be effectively prevented.

BEST MODE FOR CARRYING OUT THE INVENTION

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

[0018] Dip Hfe ffl Hfe

The dip molding composition of the present invention is a copolymer obtained by copolymerizing a monomer mixture containing a conjugation monomer, an aromatic vinyl monomer, and an ethylenically unsaturated acid monomer. Combined latex at least.

[0019] Copolymer latex

Conjugated dye monomer

Although it does not specifically limit as a conjugation monomer, The C4-C12 compound containing a conjugation is preferable. Examples of such conjugated diene monomers include 1,3-butadiene, isoprene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene. 1, 3-pentagen, black mouth plane and the like. Of these, 1,3-butadiene and 1,3-butadiene are preferred, and 1,3-butadiene and isoprene are preferred. These conjugation monomers can be used alone or in combination of two or more.

The amount of the conjugation monomer used is 34 to 60 parts by weight, preferably 38 to 55 parts by weight, and more preferably 40 to 52 parts by weight with respect to 100 parts by weight of the total monomers. If this amount is too small, the elongation at break is poor, and conversely if too large, the releasability from the mold and the tensile strength are poor.

[0020] Houki Bure Monomer Examples of the aromatic bur monomer include styrene, (X-methyl styrene, p-methyl styrene, p-phenyl styrene, p-methoxy styrene, chloromethyl styrene, m-phenol styrene, and urnaphthalene. Of these, styrene is particularly preferred, and these aromatic vinyl monomers can be used alone or in combination of two or more.

The amount of the aromatic vinyl monomer used is 39 to 65 parts by weight, preferably 42 to 60 parts by weight, and more preferably 45 to 58 parts by weight with respect to 100 parts by weight of the total monomers. If the amount of the aromatic vinyl monomer is too small, the releasability from the mold is poor in ethanol resistance, and conversely if too large, the elongation at break is poor.

[0021] Ethylene unsaturated acid monomer

The ethylenically unsaturated acid monomer is not particularly limited as long as it is an ethylenically unsaturated monomer containing an acidic group. Examples of the acidic group include a carboxyl group, a sulfonic acid group, and an acid anhydride group.

Specifically, ethylenically unsaturated monocarboxylic acid monomers such as acrylic acid and methacrylic acid; ethylenically unsaturated polycarboxylic acid monomers such as itaconic acid, maleic acid and fumaric acid; Ethylenically unsaturated polycarboxylic acid anhydrides such as citraconic anhydride; ethylenically unsaturated polycarboxylic acid partial ester monomers such as monobutyl fumarate, monobutyl maleate, mono-2-hydroxypropyl maleate; styrene sulfone And ethylenically unsaturated sulfonic acid monomers such as acids. Of these, methacrylic acid is particularly preferred, with ethylenically unsaturated monocarboxylic acids being more preferred, with ethylenically unsaturated carboxylic acids being preferred. These ethylenically unsaturated acid monomers can also be used as alkali metal salts or ammonium salts. These ethylenically unsaturated acid monomers can be used alone or in combination of two or more.

The amount of the ethylenically unsaturated acid monomer used is 1 to 10 parts by weight, preferably 1.5 to 8 parts by weight, more preferably 2 to 7 parts by weight, based on 100 parts by weight of the total monomers. . If the amount of the ethylenically unsaturated acid monomer is too small, the tensile strength is inferior. On the other hand, if the amount is too large, the elongation at break is inferior.

[0022] Other monomers In the copolymer latex contained in the dip molding composition of the present invention, in addition to the above-mentioned monomer, if necessary, other monomers copolymerizable with these can be used. The

Other monomers include, for example, fluoralkyl butyl ether such as fluoroethyl vinyl ether; (meth) acrylamide, N-methylol (meth) acrylamide, N, N dimethylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide N-propoxymethyl ethylenically unsaturated amide monomers such as (meth) acrylamide; methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylic acid-2-ethyl Hexyl, trifluoroethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate, dibutyl maleate, dibutyl fumarate, jetyl maleate, methoxymethyl (meth) acrylate, ethoxyethyl (meth) acrylate, ( (Meth) acrylic acid Ethyl, cyanomethyl (meth) acrylate, 2-cyanoethyl (meth) acrylate, (meth) acrylic acid— 1-cyanopropyl, (meth) acrylic acid—2 ethyl-6 cyanohexyl, (meth) acrylic acid 1 3 — Ethylenically unsaturated carboxylic acid ester monomers such as cyanopropyl, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, glycidyl (meth) acrylate, dimethylaminoethyl (meth) acrylate; Ethylenically unsaturated-tolyl monomers such as (meth) acrylonitrile; dibutenebenzene, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, penta Crosslinkable simple substances such as erythritol (meth) atarylate Body; and the like. These monomers can be used alone or in combination of two or more.

When these other monomers are used, the amount used is preferably 20 parts by weight or less, more preferably 15 parts by weight or less, and even more preferably 10 parts by weight or less with respect to 100 parts by weight of the total monomers. is there. If the amount of the other monomer is too large, the effects of the present invention described above tend to be difficult to obtain.

Method for producing copolymer latex

Next, a method for producing the copolymer latex used in the present invention will be described.

The copolymer latex used in the present invention emulsion-polymerizes a mixture of the above monomers. Can be manufactured. As the emulsion polymerization method, a conventionally known emulsion polymerization method may be employed. For emulsion polymerization, commonly used polymerization auxiliary materials such as emulsifiers, polymerization initiators, chain transfer agents and the like can be used.

[0024] The emollient is not particularly limited, but nonionic such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenol ether, polyoxyethylene alkyl ester, polyoxyethylene sorbitan alkyl ester, etc. Emulsifiers: Fatty acid salts such as myristic acid, palmitic acid, oleic acid, linolenic acid, alkyl benzene sulfonates such as sodium dodecylbenzene sulfonate, higher alcohol sulfate esters, alkyl sulfosuccinates, etc. A, j8 unsaturated carboxylic acid sulfoester, _a , j8-unsaturated carboxylic acid sulfate ester, sulfoalkylaryl ether, and other copolymerizable whey agents; Of these, ionic emulsifiers are preferably used. These emulsifiers can be used alone or in combination of two or more. The amount of the emulsifier used is preferably 0.1 to 10 parts by weight, more preferably 2 to 6 parts by weight with respect to 100 parts by weight of the total monomers.

[0025] The polymerization initiator is not particularly limited, and examples thereof include inorganic peroxides such as sodium persulfate, potassium persulfate, ammonium persulfate, potassium perphosphate, and hydrogen peroxide; Benzene Hyde Peroxide, Cumene Hyde Peroxide, t-Butyl Hyde Peroxide, 1, 1, 3, 3-Tetramethylbutyl Hyde Peroxide, 2, 5 Dimethylhexane 2, 5 Dihydrate Peroxide, G Organic peroxides such as butyl peroxide, di-α-tamyl peroxide, acetyl chloride, isobutyryl peroxide, benzoyl peroxide; azobisisobutyoxy-tolyl, azobis-2,4 dimethyl valeryl-tolyl, azobisisobutyric acid Azo compounds such as methyl; and the like. In particular, when an inorganic peroxide is used, a copolymer latex can be stably produced, and a dip molded product having excellent tensile strength and elongation at break can be obtained. . These polymerization initiators can be used alone or in combination of two or more. The amount of the polymerization initiator used is usually 0.01 to 1 part by weight with respect to 100 parts by weight of all monomers.

[0026] The inorganic peroxide initiator and the organic peroxide initiator described above are combined with a reducing agent. In addition, it can be used as a redox polymerization initiator. Examples of such a reducing agent include, but are not limited to, compounds containing metal ions in a reduced state such as ferrous sulfate and cuprous naphthenate; sulfonic acid compounds such as sodium methanesulfonate; dimethyl And amine compounds such as a phosphorus.

[0027] When carrying out the emulsion polymerization, it is preferable to use a chain transfer agent. By using a chain transfer agent, it is possible to adjust the toluene-insoluble content of the copolymer constituting the copolymer latex.

Examples of chain transfer agents include mercaptans such as n-butyl mercaptan and t-dodecyl mercaptan; sulfides such as tetraethylthiuramsulfide and dipentamethylenethiuramhexasulfide; _a- methylstyrene dimer; tetrasalt匕匕; and so on. Of these, mercaptans are preferred. Tododecyl mercaptan is more preferred. These can be used alone or in combination of two or more. The amount of the chain transfer agent used is preferably 0.1 to 1 part by weight, more preferably 0.2 to 0.5 part by weight, based on 100 parts by weight of all monomers.

[0028] The amount of water used in the emulsion polymerization is usually about 80 to 600 parts by weight, preferably 100 to 300 parts by weight, with respect to 100 parts by weight of the total monomers.

[0029] The method of adding each monomer described above is not particularly limited, and a method of mixing the monomers to form a monomer mixture and charging the monomer mixture into the polymerization reactor all at once. , A method of continuously adding the monomer mixture to the polymerization reactor, charging a part of the monomer into the polymerization reactor, and adding the remaining monomer continuously or divided into the polymerization reactor Use any of these methods.

In the emulsion polymerization, polymerization auxiliary materials such as a particle size adjusting agent, a chelating agent, an oxygen scavenger, and a dispersing agent can be used as necessary.

[0031] Emulsion polymerization is usually carried out in water using the monomers and polymerization auxiliary materials.

The polymerization temperature is not particularly limited, but is preferably 5 to 60 ° C, more preferably 30 to 50 ° C. The polymerization time is about 5 to 30 hours.

[0032] Emulsion polymerization is performed under the above conditions, and when a predetermined polymerization conversion rate is reached, the polymerization reaction is stopped by a method of cooling the polymerization system or a method of adding a polymerization terminator. Polymerization reaction The polymerization conversion rate when the reaction is stopped is preferably 90% by weight or more, more preferably 94% by weight or more. Then, after stopping the polymerization reaction, a copolymer latex can be obtained by removing unreacted monomers and adjusting the solid content concentration and pH as desired.

[0033] In the present invention, each monomer constituting the copolymer latex to be contained in the dip molding composition is set to the above predetermined amount, and further a copolymer latex is constituted. The toluene insoluble content of the copolymer is set to the following specific range. By adopting such a configuration, it is possible to improve mold release properties and ethanol resistance while maintaining tensile strength and elongation at break.

That is, the insoluble content of toluene is 30% by weight or more, preferably in the range of 40 to 95% by weight, more preferably 50 to 90% by weight, based on 100% by weight of the entire copolymer constituting the copolymer latex. The range. For toluene insoluble matter, for example, a dry film made of copolymer latex is placed in a wire mesh cage and immersed in toluene at a temperature of 20 ° C for 24 hours, and then the basket is pulled up and dried, and the dried film before and after immersion The specific force can be calculated. The toluene insoluble matter depends on various factors such as polymerization temperature, reaction time, type and amount of polymerization initiator, type and amount of crosslinkable monomer, and type and amount of chain transfer agent. It can select and adjust suitably.

[0034] The number average particle size of the copolymer latex is a number average particle size measured with a transmission electron microscope, and is preferably 60 to 300 nm, more preferably 80 to 150 nm. The particle size can be adjusted to a desired value by adjusting the amounts of emulsifier and polymerization initiator used.

[0035] If desired, the copolymer latex may further contain auxiliary materials such as an anti-aging agent, an ultraviolet absorber, a preservative, and an antibacterial agent.

[0036] Cross-linking agent

The dip molding composition of the present invention preferably further contains a crosslinking agent in order to crosslink the copolymer latex.

Although it does not specifically limit as a crosslinking agent, Sulfur, an organic peroxide, a polyamine, etc. are mentioned. Of these, sulfur is preferable.

[0037] Examples of sulfur include powdered sulfur, sulfur white, precipitated sulfur, colloidal sulfur, and surface-treated sulfur. Examples include yellow and insoluble sulfur.

Organic peroxides include, for example, dibenzoyl peroxide, benzoyl (3-methylbenzoyl) peroxide, di (4 methylbenzoyl) peroxide, dilauryl peroxide, distearoyl peroxide, di-α-tamil peroxide 1, 1 bis (t-butylperoxy) cyclododecane, succinic acid peroxide, bis (4-tert-butylcyclohexyl) peroxydicarbonate, t-butylperoxymaleic acid, and the like.

Examples of the polyamine include hexamethylenediamine, triethylenetetramine, tetraethylenepentamine and the like.

[0038] The amount of the crosslinking agent is preferably 0.1 to 3 parts by weight, more preferably 0.3 to 2 parts per 100 parts by weight of the solid content (latex solid content) in the dip molding composition. 5 parts by weight, more preferably 0.5 to 2 parts by weight. If the amount of the crosslinking agent is too small, the tensile strength is inferior. On the other hand, if the amount is too large, the elongation at break is inferior.

[0039] When sulfur is used as the crosslinking agent, it is preferable to incorporate a crosslinking accelerator (vulcanization accelerator) or zinc oxide.

[0040] As the crosslinking accelerator (vulcanization accelerator), those usually used for dip molding can be used, and examples thereof include decyl dithiocarbamic acid, dibutyldithiocarbamic acid, and di-2-ethyl. Xyldithiocarbamate, dicyclohexyldithiocarbamate, diphenoldithiocarbamate, dibenzyldithiocarbamate and other dithiorubamates and their zinc salts; 2-mercaptobenzothiazole, 2-mercaptobenzo Zinc thiazole, 2-mercaptothiazoline, dibenzothiazyl'disulfide, 2- (2,4-di-trifluorothio) benzothiazole, 2- (N, N jetylthio'carbylthio) benzothiazole, 2- (2, 6 Dimethyl-4-morpholinothio) benzothiazol, 2— (4, -morpholino'dithio) benzothiazole, 4 E - Lil - 2 Ben Zochiajiru 'disulfide, 1, 3-bis (2 base Nzochiajiru' mercaptomethyl) etc. urea which can be mentioned. These can be used alone or in combination of two or more. The amount of the crosslinking accelerator (vulcanization accelerator) is preferably 0.1 to 2 parts by weight, more preferably 0.2 to 1.5 parts by weight, more preferably 100 parts by weight of the latex solid content. Preferably from 0.25 1 part by weight. If this amount is too small, the tensile strength decreases, and if it is too large, the elongation at break is inferior.

[0041] The amount of acid zinc is preferably 0.3 to 3 parts by weight, more preferably 0.5 to 2 parts by weight, and still more preferably 1 to 1. 5 parts by weight. If the amount is too small, the tensile strength is inferior. Conversely, if the amount is too large, the elongation at break is inferior.

[0042] The dip molding composition of the present invention may further contain a pH adjuster, a thickener, an anti-aging agent, a dispersant, a pigment, a filler, a softener, and the like, if necessary. .

[0043] The solid content concentration of the dip molding composition of the present invention is preferably 10 to 60% by weight, more preferably 20 to 45% by weight. The pH of the dip molding composition of the present invention is preferably 8.5 to 12, more preferably 9 to L1.

[0044] The dip-forming composition of the present invention has a 180 ° peel test value of the dip-formed film when the dip-formed film is formed on the metal plate by immersing the metal plate. 4. 9 (NZ25mm) or less, preferably 3.4 (NZ25mm) or less. When the value of the peel test is low, it is easy to release from the mold during dip molding. Therefore, the value of the peel test is preferably low. The peel test value is determined by, for example, forming a dip-molded layer made of a dip-molding composition on a metal plate, then heating to crosslink the copolymer latex, and then peeling the molded film. It can be measured by obtaining the tensile load required for this. The metal plate used in this case is not particularly limited as long as a metal plate generally used for adhesion tests is used, but stainless steel plates, aluminum and aluminum alloy plates, chrome plates, etc. can be used. . Among these, a stainless steel plate can be preferably used.

[0045] Dip molding

The dip-molded product of the present invention is obtained by dip-forming 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. Of these, the anode coagulation dipping method is preferable in that a dip-molded product having a uniform thickness is easily obtained. Hereinafter, a dip forming method by an anode adhesion dipping method as one embodiment will be described. [0046] First, the dip mold is immersed in a coagulant solution, and the coagulant is adhered 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 should be matched to the shape of the final dip-molded product.

[0047] 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. Halogenated metals such as barium chloride, calcium chloride, magnesium chloride, dumbbell, salt and aluminum; nitrates such as barium nitrate, calcium nitrate, and zinc nitrate; acetates such as barium acetate, calcium acetate, and zinc acetate; calcium sulfate, And sulfates such as magnesium sulfate and 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.

[0048] 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. To do.

[0049] Next, the dip-molded layer formed in the dip-molding die is heated to crosslink the copolymer latex. The heating temperature is preferably 100 to 150 ° C. If the temperature is too low, the cross-linking reaction takes a long time, which may reduce productivity. On the other hand, if it is too high, the deterioration of the acidity of the copolymer latex may be accelerated and the physical properties of the molded product may be lowered. The heat treatment time may be appropriately selected according to 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.

[0050] In the present invention, before the dip-molded layer is subjected to heat treatment, the dip-molded layer is immersed in warm water of 20 to 80 ° C for about 0.5 to 60 minutes to obtain water-soluble impurities. It is preferable to remove (emulsifier, water-soluble polymer, coagulant, etc.).

[0051] Next, the dip-molded layer crosslinked by heat treatment is removed from the dip-mold to obtain a dip-molded product. As the demolding method, a method of peeling from the mold by hand or a method of peeling by water pressure or compressed air pressure can be employed.

The dip-molded article of the present invention comprises the above-described dip-molding composition of the present invention (preferably It is obtained by dip molding a composition having a 180 ° peel test value of 4.9 (NZ25 mm) or less, and is excellent in releasability from the mold. Therefore, the adhesion to the mold is effectively prevented, and as a result, the mold can be removed easily and easily.

[0052] After demolding, a heat treatment (post-crosslinking step) may be performed at a temperature of 60 to 120 ° C for 10 to 120 minutes.

[0053] Further, when the dip-formed product is a glove, talc, calcium carbonate, starch particles, etc. are used in order to prevent adhesion at the contact surface between the dip-formed products and to improve slippage during attachment / detachment. Sprinkle inorganic or organic fine particles on the surface of the glove, form an elastomer layer containing these fine particles on the surface of the glove, or chlorinate the surface layer of the glove.

[0054] The dip-molded product of the present invention thus obtained has a good tensile strength of 20 MPa or more, a breaking elongation of 600% or more, and a resistance to ethanol that can sufficiently withstand normal use conditions. It has sex. That is, the tensile strength at break after immersion in ethanol is preferably 16 MPa or more, more preferably 20 MPa or more, and further preferably 25 MPa or more, and has excellent ethanol resistance. The tensile strength at break after immersion in ethanol can be measured by immersing the dip-molded product in ethanol at a temperature of 20 ° C for 1 hour, and then performing a tensile test on the immersed molded product. it can.

Conventionally, in such dip-molded products, the tensile strength at break after immersion in ethanol was insufficient, so for example, when dip-molded products are used for rubber gloves and ethanol disinfection is used, There was a problem that gloves were easily torn o

On the other hand, according to the dip-molded product of the present invention, since the dip-molding composition of the present invention is formed by dip molding, such a problem can be effectively solved.

[0055] Since such a dip-formed 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 is thin with such a thickness. It can be used suitably for things. Specifically, medical supplies such as nipples, syringes, conduits, and water pillows for baby bottles; toys and exercise equipment such as balloons, dolls, and balls; industrial products such as pressure forming bags and gas storage bags Goods: Medical, household, agricultural, fishery and industrial gloves; can be used for finger sack, etc., particularly suitable for thin medical gloves. When the molded product is a glove, it may be a sabot type or an unsupport type.

Example

[0056] 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. The copolymer latex, the dip molding composition, and the dip molded product were evaluated by the following methods.

[0057] #Toluene insoluble content of polymer latex

First, the copolymer latex was cast on a framed glass plate, and then allowed to stand for 120 hours under conditions of a temperature of 20 ° C. and a relative humidity of 65% to obtain a dry film having a thickness of 1 mm. Next, weigh out about 0.2g (weight W) from this dry film and put it in an 80 mesh wire mesh basket.

0

And immersed in 100 ml of toluene at a temperature of 20 ° C. for 24 hours. Then, the soaked force basket was pulled up, dried at a temperature of 105 ° C, toluene was removed, and the amount of film remaining in the basket without being dissolved in toluene was precisely weighed (weight W) o Finally, the obtained weight W, W force,

1 0 1 The toluene insoluble matter was determined according to the following formula (1).

Toluene insoluble matter (wt%) = (W / W) X 100 (1)

Ten

[0058] 180 ° peel test

First, in a 20% aqueous calcium nitrate solution, a stainless steel plate (SUS304) with a length of 200mm x width 25 111111 according to JIS K6854 is vertically placed vertically, and the bottom edge of the plate is immersed to a position of 175mm. Then, it pulled up and dried at 60 degreeC for 10 minutes. Next, the dried plate is dipped in the dip molding composition in the same manner as described above to the position where the bottom end force of the plate is 170 mm, and then pulled up to dip forming layer before crosslinking on both sides of the plate. Formed. Then, the plate on which the dip-formed layer was formed was washed with distilled water at 40 ° C for 5 minutes, pre-dried at 20 ° C for 5 minutes, then dried at 60 ° C for 10 minutes, and then 120 ° C. And were cross-linked for 30 minutes to obtain a dip-formed film, and a test piece for a peel test was obtained. Next, in accordance with JIS K6854, one end of the dip-formed film was peeled in advance in the vertical direction by 95 mm using one side of the test piece prepared above. And stainless steel plate Attach the upper end to the upper grip of the Tensilon universal testing machine, and then attach one end of the dip molding film previously peeled off to the lower grip of the Tensilon universal testing machine. It was. Thereafter, a 180 ° peel test was conducted from the point of pulling under the condition of a pulling speed of 200 mmZ. As a result of the peeling test, the maximum value of the bow | tension load (peeling resistance value, unit: NZ25 mm) when the dip-formed film (length 75 mm x width 25 mm) was peeled from the stainless steel plate was measured. This peel test was performed three times, and the average value was taken as the peel resistance value. If the peel resistance value is low, it is easy to release from the mold during dip molding, so a low peel resistance value is preferable!

[0059] Release from glove mold (molding mold)

The ease with which the dip-formed film after crosslinking formed on the surface of the glove mold (mold) was peeled off from the glove mold (releasability) was evaluated according to the following criteria.

A: The dip-formed film is not in close contact with the glove mold and can be easily detached.

B: The dip-molded film is partially adhered to the glove mold, and is somewhat difficult to remove. C: The dip-formed layer is in close contact with the glove mold and is difficult to remove.

[0060] Tensile strength, elongation at break

A dumbbell-shaped test piece was produced from the obtained rubber glove (dip-formed product) using a dumbbell (Die — C) according to ASTM D-412. Next, the test piece was pulled with a Tensilon universal testing machine at a tensile speed of 500 mmZ, and the tensile strength at break (MPa) and the elongation at break (%) were measured.

[0061] Tensile strength after ethanol cleaning (ethanol resistance)

First, a test piece similar to that used for measurement of tensile strength and elongation at break was immersed for 1 hour in ethanol (special grade reagent) at a temperature of 20 ° C. Then, the test piece after immersion was pulled with a Tensilon universal tester at a tensile speed of 500 mmZ, and the tensile strength at break (tensile strength after ethanol immersion) was measured.

[0062] Example 1

Production of copolymer latex

First, in a pressure-resistant polymerization reactor, 47 parts of styrene, 3 parts of methacrylic acid, 50 parts of 1,3-butadiene, 0.3 part of tododecyl mercaptan as a chain transfer agent, 150 parts of deionized water, After charging 2.5 parts of sodium benzenesulfonate, 0.3 part of potassium persulfate, and 0.1 part of sodium ethylenediamine tetraacetate, the temperature in the system was changed to 45 ° C. to initiate the polymerization reaction. Then, the polymerization reaction was continued until the polymerization conversion rate reached 95%, and then 0.1 part of jetylhydroxylamine was added to stop the polymerization reaction. Then, after removing the unreacted monomer, the solid content concentration and the pH were adjusted to obtain a copolymer latex having a solid content concentration of 45% and a pH of 8.5. A pH meter (M12: manufactured by HORIBA) was used for pH measurement.

[0063] Preparation of dip molding composition

First, 1.0 part of sulfur, 0.5 part zinc diethyldithiocarbamate, 1.0 part zinc oxide, 1.5 parts titanium oxide, 0.03 part potassium hydroxide and 5.63 parts water are mixed. Thus, a vulcanizing agent (crosslinking agent) dispersion was obtained. Then, 9.16 parts of this vulcanizing agent dispersion was added to 222.2 parts of the copolymer latex produced above (100 parts as the solid content) and mixed. Thereafter, an appropriate amount of deionized water was added to adjust the solid content concentration to 30% and pH 9.0, and further ripened for 1 day to obtain a dip molding composition.

[0064] Rubber bowl (dip molded product)

Next, a rubber glove (dip molded product) was produced by the following method using the dip molding composition obtained above.

First, an aqueous coagulant solution was prepared by mixing 20 parts of calcium nitrate, 0.05 part of polyethylene glycol octyl phenyl ether as a nonionic emulsifier and 80 parts of water. Next, a glove mold heated to 60 ° C. was immersed in this coagulant aqueous solution for 10 seconds, pulled up, and then dried under conditions of a temperature of 60 ° C. for 10 minutes to attach the coagulant to the glove mold . Next, the glove mold to which the coagulant was adhered was immersed in the dip molding composition obtained above for 15 seconds and pulled up to form a dip molding layer on the surface of the glove mold. The formed dip-formed layer is immersed in distilled water at 40 ° C for 5 minutes to remove water-soluble impurities, then pre-dried at 20 ° C for 5 minutes, further dried at 60 ° C for 10 minutes, and then 120 ° C. Vulcanization was performed for 30 minutes. Finally, the dip-formed layer after vulcanization was peeled off from the glove mold to obtain a rubber glove (date-formed product) having a thickness of 0.1 mm.

[0065] The copolymer latex obtained above was subjected to a toluene-insoluble matter, a 180 ° peel test for the dip molding composition, and a dip molded product from the mold. Each evaluation of peelability, tensile strength, elongation at break and tensile strength after immersion in ethanol was performed by the above methods. The results are shown in Table 1.

[0066] Examples 2 to 4, Comparative Examples 1 to 5

Except that the monomer composition used in the production of the copolymer latex was changed as shown in Table 1, and the toluene-insoluble content of the copolymer constituting the copolymer latex was changed. A copolymer latex, a dip-molding composition, and a dip-molded product were prepared in the same manner as in Example 1, and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0067] In Examples 2 to 4 and Comparative Examples 1 to 5, copolymer latex contained in the dip molding composition by changing the addition amount of the chain transfer agent and the conditions of the addition method. The toluene-insoluble content of the copolymer constituting was adjusted. Specifically, in Examples 2 and 4, tododecyl mercaptan in the amount shown in Table 1 was added at the start of polymerization. In Example 3, the amount of t-decyl mercaptan added at the start of polymerization was 0.2 parts, and 0.1 part of t-decyl mercaptan was added when the polymerization conversion was 60%. did. Similarly, in Comparative Examples 1 to 3, the amount of t-dodecyl mercaptan at the start of polymerization was set to the amount shown in Table 1 (in Table 1, “at the start of polymerization”), and the polymerization conversion rate was 60%. The amount of t-decyl mercaptan shown in Table 1 was added as a supplement (in Table 1, “Post-added Caro”).

[0068] [Table 1]

In the table, in the amount of t-decyl mercaptan added, “post-addition” means the amount added at a polymerization conversion rate of 60¾.

[0069] From Table 1, the following can be confirmed.

In the case of not containing styrene as the aromatic vinyl monomer, the releasability from the mold was poor, the tensile strength after ethanol immersion was low, and the ethanol resistance was insufficient (Comparative Example 1). , Five). This Comparative Example 1 corresponds to a synthetic NBR for gloves that is generally commercially available.

When the toluene insoluble content of the copolymer constituting the copolymer latex was too low, the releasability from the mold was poor and the ethanol resistance was insufficient (Comparative Example 2).

[0070] The content of 1,3-butadiene as the conjugation monomer and the content of styrene as the aromatic butyl monomer are outside the scope of the present invention. When the dissolved content was too low, the releasability from the mold was poor and the tensile strength was insufficient (Comparative Example 3).

When the content of 1,3-butadiene as the conjugation monomer and the content of styrene as the aromatic vinyl monomer are outside the scope of the present invention, the toluene-insoluble matter is reduced. Even within the scope of the invention, ethanol resistance was insufficient (Comparative Example 4).

[0071] In comparison with these comparative examples, the rubber gloves (dip-molded products) obtained using the dip-molding composition according to the present invention have good release properties from the mold. The tensile strength and elongation at break were sufficient, and the tensile strength after immersion in ethanol was high, resulting in excellent ethanol resistance (Examples 1 to 4). That is, according to these Examples 1 to 4, since the adhesion to the mold is low, it is possible to perform the detachment of the mold force well, and the force is also suitable for glove use that is used after being disinfected with ethanol. It can be used suitably.

Claims

The scope of the claims

[1] Monomer comprising 34 to 60 parts by weight of a conjugation monomer, 39 to 65 parts by weight of an aromatic vinyl monomer, and 1 to L0 part by weight of an ethylenically unsaturated acid monomer A dip-molding composition having a copolymer latex obtained by copolymerizing 100 parts by weight of a body mixture, wherein the copolymer constituting the copolymer latex is placed in toluene at a temperature of 20 ° C. The composition for dip molding, wherein the toluene-insoluble content of the copolymer when immersed for 24 hours is 30% by weight or more with respect to 100% by weight of the whole copolymer.

[2] The conjugation monomer is 1,3 butadiene, isoprene, 2-methyl-1,3 butadiene, 2,3 dimethyl-1,3 butadiene, 2 ethyl 1,3 butadiene, 1,3 2. The dip-forming composition according to claim 1, wherein the composition is at least one kind selected from a group power consisting of a mouth plane.

[3] The dip molding composition according to claim 1, wherein the conjugation monomer is 1,3 butadiene and Z or isoprene.

[4] The dip forming composition according to claim 1, wherein the conjugation monomer is 1,3 butadiene.

[5] The aromatic bur monomer may be selected from the group consisting of styrene, α-methyl styrene, p-methyl styrene, p phenylol styrene, ρ-methoxy styrene, chloromethyl styrene, m-fluoro styrene, and urnaphthalene. The composition for dip molding according to any one of claims 1 to 4, which is at least one of the above.

[6] The composition for die molding according to any one of claims 1 to 4, wherein the aromatic pill monomer is styrene.

[7] The ethylenically unsaturated acid monomer is an ethylenically unsaturated monocarboxylic acid monomer, an ethylenically unsaturated polyvalent carboxylic acid monomer, an ethylenically unsaturated polyvalent carboxylic acid anhydride, ethylene The composition for dip molding according to any one of claims 1 to 6, wherein the composition is at least one selected from the group consisting of a polymerizable unsaturated polycarboxylic acid partial ester monomer and an ethylenically unsaturated sulfonic acid monomer. .

[8] The dip molding composition according to any one of claims 1 to 6, wherein the ethylenically unsaturated acid monomer is an ethylenically unsaturated monocarboxylic acid. The composition for dip molding according to any one of claims 1 to 6, wherein the ethylenically unsaturated acid monomer is methacrylic acid.

Furthermore, the composition for dip molding in any one of Claims 1-9 containing the crosslinking agent.

11. The dip molding composition according to claim 10, wherein the crosslinking agent is at least one selected from the group power consisting of sulfur, an organic peroxide, and a polyamine.

The dip-forming composition according to claim 10, wherein the crosslinking agent is sulfur.

Compounding power of the crosslinking agent 100 parts by weight of solid content in the dip molding composition

The composition for dip molding according to any one of claims 10 to 12, which is 0.1 to 3 parts by weight, and further comprises a crosslinking accelerator. .

15. The dip molding composition according to claim 14, wherein the amount of the crosslinking accelerator is 0.1 to 2 parts by weight with respect to 100 parts by weight of the solid content in the dip molding composition.

The dip molding composition according to claim 12, further comprising acid zinc.

17. The composition for dip molding according to claim 16, which is 0.3 to 3 parts by weight based on 100 parts by weight of the solid content in the dip molding composition.

The dip-forming composition according to any one of claims 1 to 17, wherein ρΗ is 8.5 to 12. A dip-forming film is formed on the metal plate by immersing a metal plate in the dip-forming composition. The composition for dip molding according to any one of claims 1 to 18, wherein the dip-molded film has a 180 ° peel test value of 4.9 (N / 25 mm) or less.

A dip-molded product obtained by dip-molding the dip-molding composition according to any one of claims 1 to 19.

21. The dip-molded product according to claim 20, wherein the tensile strength measured in accordance with ASTM D-412 is 20 MPa or more and the elongation at break is 600% or more.

Measured at a tensile speed of 500 mmZ after being immersed in ethanol at a temperature of 20 ° C for 1 hour The dip-formed product according to claim 20 or 21, wherein the tensile strength is 16 MPa or more.