WO2003062307A2 - Composition de latex polymere, articles formes par immersion, et procede de production d'articles formes par immersion - Google Patents

Composition de latex polymere, articles formes par immersion, et procede de production d'articles formes par immersion Download PDF

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Publication number
WO2003062307A2
WO2003062307A2 PCT/JP2003/000657 JP0300657W WO03062307A2 WO 2003062307 A2 WO2003062307 A2 WO 2003062307A2 JP 0300657 W JP0300657 W JP 0300657W WO 03062307 A2 WO03062307 A2 WO 03062307A2
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Prior art keywords
dip
polymer
forming
polymer latex
polymerization
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PCT/JP2003/000657
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English (en)
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WO2003062307A3 (fr
Inventor
Xiang Liu
Misao Nakamura
Kazumi Kodama
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Zeon Corporation
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Priority claimed from JP2002015707A external-priority patent/JP2003213197A/ja
Priority claimed from JP2002188921A external-priority patent/JP2004027135A/ja
Application filed by Zeon Corporation filed Critical Zeon Corporation
Publication of WO2003062307A2 publication Critical patent/WO2003062307A2/fr
Publication of WO2003062307A3 publication Critical patent/WO2003062307A3/fr

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J3/00—Processes of treating or compounding macromolecular substances
    • C08J3/02—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques
    • C08J3/03—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques in aqueous media
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08C—TREATMENT OR CHEMICAL MODIFICATION OF RUBBERS
    • C08C1/00—Treatment of rubber latex
    • C08C1/14—Coagulation
    • C08C1/15—Coagulation characterised by the coagulants used

Definitions

  • This invention relates to a polymer latex composition which is used as a coating agent or for the preparation of a coagulating composition for dip-forming, a dip-formed article and a process for making a dip-formed article.
  • the present invention is concerned with a polymer latex composition used as a coating agent for making a dip-formed article which can be easily released from a dip-forming form in a dip-forming step, has an enhanced blocking resistance, can be easily donned and put off, and from which a fine powder is not separated or is separated only to a slight extent; and a dip-formed article having a coating formed from the polymer latex composition.
  • the present invention is concerned with a coagulating polymer latex composition which is not subject to coagulation when it is used as a coagulating composition at a dip-forming step, and which is capable of giving a dip-formed article characterized in that a fine powder is not separated or is separated only to a slight extent from the dip-formed article, and in that it has an outer surface exhibiting enhanced blocking resistance; and a dip-formed article made by using the coagulating polymer latex composition; and a process for making the dip-formed article.
  • Dip-formed articles made from natural rubber latex or synthetic rubber latex are used, for example, as rubber gloves and finger cots .
  • the skin-contacting inner surface of a dip-formed article such as a glove and the outer surface thereof have problems . That is, the inner surface of a glove is sticky and not slippery, and the rubber glove cannot be easily donned and put off.
  • the outer surface of a glove is also sticky and, when a plurality of gloves are stored in a superposed state, the outer surfaces thereof stick one another and must be stripped from each other for donning. Where the gloves are thin in thickness, they are easily broken upon stripping.
  • a method of applying a dusting powder such as talc powder onto the inner surface of a glove, and a method of subjecting the inner surface of a glove to a chlorinating treatment to form protrusions on the inner surface were proposed.
  • the former method has problems such that the applied dusting powder is easily separated upon donning and putting off the glove, and, when the glove is used in a medical field including surgery, the separated dusting powder may contaminate an operated part and cause postoperative complications .
  • the latter method has problems such that the treating process is difficult to control, facilitation of donning and putting off cannot be enhanced to the desired extent, and the use of chlorine may cause environmental pollution.
  • JP-A Japanese Unexamined Patent Publication
  • the inner lubricating elastomer layer is formed from an aqueous dispersion comprising a synthetic rubber latex and an organic filler, which rubber latex is incapable of being coagulated with a coagulant contained in a main rubber layer of the rubber glove.
  • the synthetic rubber used includes, for example, a styrene-butadiene rubber latex and an acrylonitrile-butadiene rubber latex.
  • the organic filler used includes, for example, finely divided crosslinked methyl methacrylate polymer particles and finely divided urethane resin particles .
  • JP-A H8-249430 Another rubber glove having an inner lubricating elastomer layer has been proposed in JP-A H8-249430, wherein the inner lubricating elastomer layer is formed mainly from an aqueous dispersion comprising finely divided thermoplastic resin particles, a rubber latex and blocked isocyanate.
  • the rubber latex includes, for example, a natural rubber latex and a chloroprene rubber latex.
  • the finely divided thermoplastic resin particles include, for example, finely divided ethylene-acrylic acid copolymer resin particles and finely divided ethylene-methacrylic acid copolymer resin particles .
  • the gloves having an inner lubricating elastomer layer are made by a method wherein a glove having an outer elastomer layer as-formed on a glove form is released from the form while the glove is reversed so that the outer elastomer layer becomes an inner lubricating elastomer layer.
  • This method has a problem such that, when the as-formed glove is released from the form, the outer elastomer layer is rubbed with each other and thus the release from the form cannot be easily conducted. Especially when the form is maintained at a high temperature for enhancing the productivity, the release fromthe moldbecomes more difficult.
  • the outer surface of a glove in order to enhance the anti-sticking property thereof, a method of applying a dusting powder such as talc powder onto the outer surface of a glove, and a method of subjecting the outer surface of a glove to a chlorination treatment to form protrusions on the inner surface were proposed.
  • the former method has problems such that the applied dusting powder is easily separated upon donning and putting off the glove, and, when the glove is used in a medical field including surgery, the separated dusting powder may contaminate an operated part and cause postoperative complications .
  • the latter method has problems such that the treating process is difficult to control, facilitation of donning and putting off cannot be enhanced to the desired extent , and the use of chlorine may cause environmental pollution.
  • a method of forming an elastomer layer on the outer surface of a glove was proposed in EP 640,623, A, wherein a coagulating composition for dip-forming comprising a latex and an inorganic coagulant, which latex is a polychloroprene latex or polyurethane latex stabilized with a cationic surface active agent against a salt, is used for dip-forming whereby an outer layer comprised of said latex is formed on the outer surface of a glove.
  • a copolymer latex is prepared by carrying out copolymerization of a copolymerizable silicone oligomer with a copolymerizable monomer, for example, an acrylic acid ester monomer in the presence of an anionic surface active agent and/or a nonionic surface active agent by a sequential two stage polymerization procedure to produce two kinds of copolymers having a glass transition temperature of -50 to 25°C and a glass transition temperature of 25 to 100°C, and a dip-forming coagulating composition comprising the thus-prepared copolymer latex and an inorganic coagulant is used for dip-forming whereby an outer layer comprised of said copolymer latex is formed on the outer surface of a glove.
  • a copolymer latex is prepared by carrying out copolymerization of a copolymerizable silicone oligomer with a copolymerizable monomer, for example, an acrylic acid ester monomer in the presence of an anionic surface active agent and/or a non
  • a primary object of the present invention is to provide a polymer latex used as a coating agent, giving a dip-formed article which is capable of being easily released from a dip-forming form, has an antiblocking property, and is capable of being easily donned and put off, and from which fine particles are separated only to a very slight extent; and to provide the dip-formed article having a coating formed from the polymer latex.
  • Another object of the present invention is to provide a polymer latex used as a coagulating composition for dip forming, in which an undesirable coagulation of the polymer latex can be minimized and which gives a dip-formed article from which fine particles are separated only to a very slight extent, and the outer surface of which sticks to each other only to a negligible extent; and to provide the dip-formed article made by using the polymer latex as a coagulating composition, and further to provide a process for making the dip-formed article.
  • a polymer latex composition used as a coating agent or for the preparation of a coagulating composition for dip-forming which comprises a polymer latex comprising a polymer having a glass transition temperature (Tg) in the range of -85°C to +30°C and a polymer having a glass transition temperature (Tg) in the range of +40°C to +140°C, said polymers being dispersion-stabilized with polyvinyl alcohol.
  • a polymer latex composition used as a coating agent which comprises a polymer latex comprising a first polymer having a glass transition temperature (Tgl) in the range of -20°C to +30°C and a second polymer having a glass transition temperature (Tg2) in the range of +60°C to +140°C, the first polymer and the second polymer being dispersion-stabilized with polyvinyl alcohol.
  • a dip-formed article having a coating formed thereon from the coating agent as mentioned above as the second aspect of the present invention.
  • a polymer latex composition which comprises a polymer latex and a coagulant for dip-forming and is used as a coagulating composition for dip-forming, wherein said polymer latex comprises copolymer particles each having polyvinyl alcohol bonded thereto, which are obtainable by polymerizing a monomer (M3 ) capable of forming a third polymer having a glass transition temperature (Tg3) in the range of -85°C to +10°C in a first polymerization step, and then a monomer (M4) capable of forming a fourth polymer having a glass transition temperature (Tg4) in the range of +40°C to +140°C in the sequential polymerization step, saidpolymerization steps being carried out in the presence of polyvinyl alcohol in an aqueous medium.
  • a dip-formed article made by a dip-forming method using the polymer latex composition mentioned above as the fourth aspect of the present invention.
  • a process for making a dip-formed article comprising the steps of: dipping a form in the polymer latex composition as mentioned above as the fourth aspect of the present invention to form a layer comprised of the polymer latex composition on the form, dipping the form having the polymer latex composition layer thereon in a dip-forming composition to form a coagulated layer comprised of the dip-forming composition, curing the coagulated layer comprised of the dip-forming composition to form a cured coagulated layer, and then, releasing the cured coagulated layer from the form, while the cured coagulated layer is reversed.
  • the polymer latex of the present invention comprises a polymer latex comprising a polymer having a glass transition temperature (Tg) in the range of -85°C to +30°C and a polymer having a glass transition temperature (Tg) in the range of +40°C to +140°C, wherein the two polymers having different glass transition temperatures are dispersion-stabilized with polyvinyl alcohol; and it is used as a coating agent or for the preparation of a coagulating composition for dip-forming.
  • Tg glass transition temperature
  • Tg glass transition temperature
  • the polymer latex of the present invention includes ( 1 ) a polymer latex composition used as a coating agent , which comprises a polymer latex comprising a first polymer having a glass transition temperature (Tgl) in the range of -20°C to +30°C and a second polymer having a glass transition temperature (Tg2) in the range of +60°C to +140°C, wherein the first polymer and the second polymer are dispersion-stabilized with polyvinyl alcohol; and (2) a polymer latex composition which comprises a copolymer latex and a coagulant for dip-forming and is used as a coagulating composition for dip-forming, wherein the copolymer latex comprises copolymer particles each having polyvinyl alcohol bonded thereto, wherein said copolymer latex is obtainable by polymerizing a monomer (M3) capable of forming a third polymer having a glass transition temperature (Tg3) in the range of -85°C to +10°C in
  • coating composition used as a coating agent
  • dip-forming coagulating composition used for the preparation of a coagulating composition for dip-forming
  • the polymer latex contained in the coating composition of the present invention comprises a first polymer having a glass transition temperature (Tgl) preferably in the range of -20°C to +30°C, more preferably -15°C to +25°C and especially preferably -10°C to +20°C, and a second polymer having a glass transition temperature (Tg2) preferably in the range of +60°C to +140°C, more preferably +70°C to +130°C and especially preferably +80°C to +120°C, wherein the first polymer and the second polymer are dispersion-stabilized with polyvinyl alcohol.
  • Tgl glass transition temperature
  • Tg2 glass transition temperature
  • Tgl If Tgl is too low, a dip-formed article is difficult to release from a form, the donning and putting-off are not easy, and the blocking resistance is poor. In contrast, if Tgl is too high, a dusting powder is liable to be easily separated from a dip-formed article.
  • Tg2 if Tg2 is too low, a dip-formed article is difficult to release from a form, the donning and putting-off are not easy, and the blocking resistance is poor. In contrast, if Tg2 is too high, a dusting powder is liable to be easily separated from a dip-formed article.
  • the polymer latex contained in the coating composition may be either a mixture of a latex of first polymer with Tgl and a latex of second polymer with Tg2 , or a polymer latex having a heterogeneous structure such that each polymer particle is comprised of the first polymer with Tgl and the second polymer with Tg2.
  • the latter polymer latex having a heterogeneous structure is preferable because the donning and putting-off of a dip-formed article is easier, a dusting powder is not easily separated, and the blocking resistance is better.
  • the polymer latex contained in the coating composition is prepared by polymerizing monomers in the presence of polyvinyl alcohol in an aqueous medium.
  • the aqueous medium used includes, for example, water- soluble organic solvents such as methanol, ethanol and isopropanol, water and a mixture thereof.
  • the amount of aqueous medium is preferably in the range of 100 to 500 parts by weight, more preferably 150 to 300 parts by weight, based on 100 parts by weight of the monomers .
  • the polyvinyl alcohol (hereinafter abbreviated to "PVA” when appropriate) is not particularly limited provided that it comprises vinyl alcohol units , is substantially soluble in water, and, when it is used in polymerization, it is capable of forming a stable polymer latex.
  • PVA is usually easily prepared by a method wherein a vinyl monomer charge comprised of a vinyl ester monomer alone or predominantly comprised of a vinyl ester monomer is polymerized by the conventional procedure to produce a vinyl ester polymer, which may be any of a homopolymer derived from a vinyl ester monomer, or a copolymer derived from at least two kinds of vinyl ester monomers or a mixture of a vinyl ester monomer and other ethylenically unsaturated monomer, and then, the thus-obtained vinyl ester polymer is saponified by the conventional procedure.
  • PVA having a modifying group such as a mercapto group introduced to their side chains or at terminals can also be used.
  • the vinyl ester monomers can be used provided that they are capable of being radically polymerized, and, as specific examples thereof, there can be mentioned vinyl formate, vinyl acetate, vinyl propionate, isopropenyl acetate, vinyl valerate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl versatate and vinyl pivalate . Of these, vinyl acetate is preferable because it is industrially less costly produced.
  • olefins such as ethylene, propylene, 1-butene and isobutene
  • ethylenically unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid
  • ethylenically unsaturated poly ⁇ arboxyli ⁇ acids and anhydrides thereof such as fumaric acid, maleic acid, itaconic acid, maleic anhydride, phthalic anhydride, trimellitic anhydride and itaconic anhydride
  • ethylenically unsaturated monocarboxylic acid esters such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-but
  • the degree of saponification of PVA is preferably in the range of 40% to 100% by mole, more preferably 60% to 99% by mole and especially preferably 80% to 95% by mole. If the degree of saponification is too small, the dispersion stability of polymer particles is reduced.
  • the polymerization degree of PVA is preferably in the range of 50 to 8,000, more preferably 100 to 6,000 and especially preferably 300 to 3,000.
  • the degree of polymerization is too low, the stability of polymerization is poor.
  • the degree of polymerization is too high, the polymer latex has a very high viscosity and the removal of heat upon polymerization for producing the latex becomes difficult , and the resulting polymer latex is difficult to handle.
  • the amount of PVA as a dispersion stabilizer is preferably in the range of 0.1 to 60 parts by weight, more preferably 0.5 to 20 parts by weight and especially preferably 1 to 10 parts by weight, based on 100 parts by weight of the monomers. If the amount of PVA is too small, the polymerization stability becomes poor, a large amount of aggregates are produced at a polymerization step, and mechanical properties of the resulting polymer latex are poor. In contrast, if the amount of PVA is too large, the removal of polymerization heat becomes difficult because of an increase in viscosity of a polymerization system, and the polymer latex has a too high viscosity to handle.
  • a surface active agent conventionally used in a polymerization for a polymer latex is preferably not used in a polymerization for the polymer latex used in the coating composition, or, even when it is used, the amount thereof should preferably be below 0.5 part by weight and more preferably below 0.2 part by weight , based on 100 parts by weight of the monomers .
  • the monomers used for the production of a polymer latex contained in the coating composition are not particularly limited provided that they are capable of being radically polymerized, and include, for example, conjugated diene monomers , ethylenically unsaturated carboxylic acid monomers , aromatic vinyl monomers, ethylenically unsaturated carboxylic acid ester monomers , ethylenically unsaturated carboxylic acid amide monomers and ethylenically unsaturated nitrile monomers .
  • aromatic vinyl monomers and ethylenically unsaturated carboxylic acid ester monomers are preferable.
  • Ethylenically unsaturated carboxylic acid ester monomers are especially preferable .
  • conjugated diene monomers there can be mentioned 1,3-butadiene, isoprene, 2,3- dimethyl-1,3-butadiene, 1,3-pentadiene and chloroprene. Of these, 1,3-butadiene is preferable.
  • ethylenically unsaturated carboxylic acid monomers there can be mentioned ethylenically unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid and crotonic acid; ethylenically unsaturated polycarboxylic acids such as fumaric acid, maleic acid, itaconic acid and butenetricarboxylic acid; and partial esters of ethylenically unsaturated carboxylic acids such as monoethyl maleate and monomethyl itaconate.
  • monocarboxylic acids such as acrylic acid, methacrylic acid and crotonic acid
  • polycarboxylic acids such as fumaric acid, maleic acid, itaconic acid and butenetricarboxylic acid
  • partial esters of ethylenically unsaturated carboxylic acids such as monoethyl maleate and monomethyl itaconate.
  • aromatic vinyl monomers there can be mentioned styrene, C ⁇ -methylstyrene, vinyltoluene, chlorostyrene and hydroxymethylstyrene .
  • ethylenically unsaturated carboxylic acid ester monomers there can be mentioned ethylenically unsaturated monocarboxylic acid ester monomers such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, trifluoroethyl acrylate, tetrafluropropyl acrylate, methoxymethyl acrylate, ethoxyethyl acrylate, cyanomethyl acrylate, 2-cyanoethyl acrylate, 2- hydroxyethyl acrylate, glycidyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate.
  • monocarboxylic acid ester monomers such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhex
  • ethylenically unsaturated carboxylic acid amide monomers there can be mentioned acrylamide, N-methylola ⁇ rylamide, N,N-dimethylolacrylamide, N-methoxymethylacrylamide, methacrylamide, N- methylolmethacrylamide, N,N-dimethylolmetha ⁇ rylamide and N- methoxymethylmethacrylamide .
  • ethylenically unsaturated nitrile monomers there can be mentioned acrylonirile, methacrylonitrile, fumaronitrile, a -chloroacrylonitrile and -cyanoethylacrylonitrile .
  • These monomers may be used either alone or as a combination of at least two threof.
  • monomers Ml capable of forming first polymer having Tgl and monomers M2 capable of forming second polymers having Tg2 are appropriately chosen.
  • Monomers Ml and monomers M2 may be used either alone or as a combination of at least two thereof.
  • BA n-butyl acrylate
  • MMA methyl methacrylate
  • the mixed ratio by weight of BA/MMA is preferably in the range of 70/30 to 30/70, more preferably 60/40 to 40/60 and especially preferably 55/45 to 45/55.
  • monomers M2 there can be mentioned a mixture of BA and MM , and MMA alone.
  • the mixed ratio by weight of BA/MMA is preferably in the range of 0/100 to 20/80, more preferably 0/100 to 15/85 and especially preferably 1/99 to 10/90.
  • the polymer latex contained in the coating composition is preferably made by a sequential two stage polymerization procedure wherein monomer Ml and monomer M2 are polymerized in the presence of PVA in an aqueous medium. The polymerization may be carried out either in an order of Ml and then M2 , or in an order of M2 and then Ml . The latter order of M2 and then Ml is preferable.
  • the ratio by weight of M1/M2 is preferably in the range of 20/80 to 80/20, more preferably 25/75 to 70/30 and especially preferably 30/70 to 50/50.
  • the polymerization conversion at the first stage polymerization is preferably at least 80%, more preferably at least 90% and especially preferably at least 95%.
  • the manner in which PVA is used is not particularly limited, but, there can be adopted amethod of previously adding the entire amount of PVA into a polymerization vessel, a method of adding a part of PVA prior to the commencement of polymerization and adding the remainder of PVA after the commencement thereof to a polymerization vessel, and a method of adding PVA continuously or intermittently at the commencement of and along with the progress of polymerization.
  • the manner in which the monomers are added into a polymerization vessel is not particularly limited, but, there can be adopted a method of previously adding the entire amount of monomers before the commencement of polymerization, a method of adding a part of the monomers prior to the commencement of polymerization and adding the remainder of monomers after the commencement thereof, and a method of adding the monomers continuously or intermittently at the commencement of and along with the progress of polymerization.
  • the method of adding the monomers continuously or intermittently at the commencement of and along with the progress of polymerization is preferable.
  • the procedure by which the monomers and PVA are added into a polymerization vessel is not particularly limited.
  • the monomers and PVA can be added either separately or as a monomer emulsion prepared bymixing together the monomers , PVA andwater .
  • the addition of the monomers and PVA is substantially concurrently commenced and substantially concurrently terminated.
  • a method of continuously adding the monomers and PVA in the form of a monomer emulsion prepared by mixing together the monomers, PVA and water is preferable.
  • the rate of continuously adding the monomers is not particularly limited, but, the rate of addition is preferably controlled so that a polymerization conversion of at least 10% by weight , more preferably at least 20% by weight and especially preferably at least 30% by weight is maintained during polymerization.
  • the rate of addition of the monomers is too high, the polymerization conversion tends to be decreased and coarse particles are liable to be produced.
  • a polymerization initiator used for polymerization of the monomers may be chosen from those which are conventionally used for emulsion polymerization.
  • water-soluble peroxides such as potassium persulfate, ammonium persulfate and hydrogen peroxide
  • oil-soluble peroxides such as t-butyl hydroperoxide, benzoyl peroxide and di-t-butyl peroxide
  • redox catalysts including a combination of a peroxide with a reducing agent such as , for example, sodium hydrogenbisulfite.
  • water-soluble peroxides are preferable.
  • Persulfates such as potassium persulfate and ammonium persulfate are especially preferable.
  • the amount of polymerization initiator is usually in the range of 0.05 to 3 parts by weight, preferably 0.1 to 2 parts by weight, based on 100 parts by weight of the monomers.
  • the procedure by which the polymerization initiator is added into a polymerization vessel is not particularly limited, but , there can be adopted a procedure of adding the entire amount of initiator before the commencement of polymerization, a procedure of adding a part of the initiator before the commencement of polymerization and adding the remainder of initiator in a lot at a predetermined time in the midway of polymerization, and a procedure of adding a part of the initiator before the commencement of polymerization and adding the remainder of initiator continuously or intermittently during polymerization.
  • the polymerization for production of the above-mentioned polymer latex is preferably carried out in the presence of a water-soluble alcohol.
  • the alcohol used is not particularly limited, but, monohydric and polyhydric water-soluble alcohols are preferably used.
  • monohydric and polyhydric water-soluble alcohols are preferably used.
  • methanol, ethanol, propanol, butanol, ethylene glycol, propylene glycol and glycerol Of these, methanol, ethanol and propanol are preferable.
  • the amount of alcohol is not particularly limited, but is preferably in the range of 1 to 50 parts by weight, more preferably 3 to 20 parts by weight, based on 100 parts by weight of the monomers .
  • the procedure by which the alcohol is added into a polymerization vessel is not particularly limited, but, there can be adopted a procedure of adding the entire amount of alcohol before the commencement of polymerization, a procedure of adding a part of the alcohol before the commencement of polymerization and adding the remainder of alcohol in a lot at a predetermined time in the midway of polymerization, and a procedure of adding a part of the alcohol before the commencement of polymerization and adding the remainder of alcohol continuously or intermittently during polymerization.
  • the procedure of adding the entire amount of alcohol before the commencement of polymerization is preferable.
  • a chain transfer agent may be used at polymerization, although it is not indispensable.
  • the chain transfer agent there can be mentioned mercapto group-containing compounds such as mercaptans (such as n- hexylmercaptan, n-octylmercaptan, t-octylmercaptan, n- dodecylmer ⁇ aptan, t-dodecylmercaptan and n-stearylmercaptan) , thioglycolic acid, thiomalic acid and 2-ethylhexyl thioglycolate; xanthogen compounds such as dimethylxanthogen disulfide and diisopropylxanthogen disulfide; a -methylstyrene dimer and its derivatives such as 2,4-diphenyl-4-methyl-l- pentene, 2, 4-diphenyl-4-methyl ⁇ 2-pentene and 1,1,3- trimethyl-3-pheny
  • the amount of chain transfer agent is usually in the range of 0.01 to 10 parts by weight based on 100 parts by weight of the monomers .
  • the procedure for adding the chain transfer agent is not particularly limited, and it may be added at once, or intermittently or continuously to a polymerization system.
  • the polymerization temperature is not particularly limited, but it is usually in the range of 0 to 100°C, preferably 50 to 90°C.
  • the polymerization is terminated.
  • the termination of polymerization is carried out by adding a polymerization terminator or cooling a polymerization system.
  • the value of polymerization conversion at which the polymerization is terminated is preferably at least 90% byweight, more preferably at least 93% by weight and especially preferably at least 95% byweight .
  • unreacted monomers may be removed.
  • the polymer latex contained in the coating composition mayhave incorporated therein additives such as a chelating agent, a dispersant, a pH adjuster, an antiseptic, a plasticizer and a defoaming agent . These additives can be added during or after polymerization.
  • the polymer latex preferably has a volume average particle diameter in the range of 50 to 5,000 nm, more preferably 80 to 2,000 nm and especially preferably 100 to 1,000 nm. If the volume average particle diameter is too small, the polymerization mixture becomes too viscous during polymerization, and the resulting polymer is difficult to handle. In contrast, if the volume average particle diameter is too large, a uniform coating layer is difficult to obtain from the coating composition.
  • the coating composition of the present invention comprising the above-mentioned latex preferably further comprises finely divided particles .
  • the finely divided particles are not particularly limited, and may be either inorganic particles or organic particles. Organic particles are especially preferable.
  • inorganic particles there can be mentioned finely divided particles of silica, magnesium oxide, titanium dioxide and calcium carbonate.
  • organic particles there can be mentioned finely divided particles of acrylic resin, acryl-styrene resin, urethane resin, polyamide resin, olefin resins, vinyl chloride resin, vinylidene chloride resin, nylon resin, cellulose resin, starch, and crosslinked resins thereof .
  • acrylic resin and acryl-styrene resin are preferable because the glass transition temperatures thereof can be relatively easily adjusted.
  • the finely divided particles may be used either alone or as a combination of at least two thereof.
  • the resin constituting the organic particles usually has a glass transition temperature in the range of 60 to 140°C, preferably 70 to 120°C and more preferably 80 to 110°C. If the glass transition temperature is too low, a dip-formed article is liable to have poor blocking resistance. In contrast, if the glass transition temperature is too high, a dusting powder is liable to be separated from a dip-formed article.
  • the finely divided particles usually has a volume average particle diameter in the range of 1 to 50 m, preferably 3 to 30 ⁇ m. If the volume average particle diameter is within this range, a dip-formed article can be very easily donned and put off, and is comfortable.
  • the shape of finely divided particles is not particularly limited, but is preferably of a spherical shape.
  • the finely divided particles are spherical, gloves are comfortable to wear, and, when gloves are donned and put off, an external force applied to a dusting powder becomes small leading to reduction of separation of a dusting powder.
  • the amount of finely divided particles is usually in the range of 10 to 200 parts by weight, preferably 20 to 150 parts by weight and more preferably 40 to 100 parts by weight, based on 100 parts by weight of the solid content in the polymer latex.
  • the amount of finely divided powder is in this range, a dip-formed article is easily released from a form, and anti-blocking property, donning and putting off property and reduction of dusting powder separation are satisfactory.
  • the coating composition of the present invention may have incorporated therein additives such as a thickener, a wetting agent, a defoaming agent, a pH adjuster and an antioxidant .
  • additives such as a thickener, a wetting agent, a defoaming agent, a pH adjuster and an antioxidant .
  • Hydrophili ⁇ solvents such as alcohols , Cellosolves, gly ⁇ ols and glycerin can also be added, if desired, in order to the drying property and film-forming property of the coating agent .
  • the solid content in the coating composition is usually in the range of 1 to 15% by weight, preferably 3 to 12% by weight and more preferably 5 to 10% by weight, based on the coating composition.
  • a di -formed article can be coated with the above- mentioned coating composition to enhance the releasability from a form, the anti-blocking property and the ease in donning and putting-of , and to reduce the separation of a dusting powder.
  • the amount of the coating composition used is not particularly limited, but is preferably in the range of 0.1 to 2 g/m 2 , more preferably 0.15 to 1.5 g/m 2 , as the amount of solid content applied to unit area.
  • the dip-formed article is not particularly limited, and includes, for example, gloves and finger cots, which are made usually by conventional direct dip-forming, cohesion dip- forming and heat-sensitive dip-forming.
  • the dip-formed article may be made from a natural rubber latex or a synthetic rubber latex.
  • the synthetic rubber latex includes, for example, a styrene-butadiene copolymer latex, an acrylonitrile-butadiene copolymer latex and a carboxyl-modified acrylonitrile- butadiene copolymer latex.
  • the coating composition of the present invention is especially suitable for coating gloves made by a cohesion dip-forming method from a carboxyl-modified acrylonitrile-butadiene copolymer latex.
  • the dip-forming form used includes those which are made from porcelain, ceramics, metals, glass and plastic materials .
  • the dip-forming form used is a glove form having the contour of a human hand.
  • the glove form includes various forms which are, for example, a form having the contour spanning from a wrist to finger tips, and a form having the contour spanning an elbow to finger tips .
  • the method of coating a dip-formed article with the coating agent usually includes, for example, a method of dipping a di -formed article in a bath of the coating composition, and a method of applying the coating agent to a dip-formed article.
  • the former method of dipping a dip-formed article in a bath of the coating agent is preferable because a uniform surface coating can be obtained.
  • the coating of dip-formed article can be conducted at a step following a dip-forming in the course of making a dip- formed article from raw material, or conducted on a finished and stored dip-formed article. In either case, an as-coated dip-formed article is dried to give a coated dip-formed article.
  • the coating of dip-formed article may be conducted either on one surface or both surfaces thereof, and either on the whole surface or a part of the surface thereof.
  • the polymer latex composition of the present invention comprises a polymer latex and a coagulant for dip-forming, and is used as a coagulating composition for dip-forming, wherein the polymer latex is a copolymer latex comprising copolymer particles each having polyvinyl alcohol bonded thereto, which are obtained by polymerizing a monomer (M3) capable of forming a third polymer having a glass transition temperature (Tg3) in the range of -85°C to +10°C in a first polymerization step, and then a monomer (M4) capable of forming a fourth polymer having a glass transition temperature (Tg4) in the range of +40°C to +140°C in the sequential polymerization step, said polymerization steps being carried out in the presence of polyvinyl alcohol in an aqueous medium.
  • M3 monomer
  • Tg3 glass transition temperature
  • Tg3 glass transition temperature
  • the copolymer latex contained in the coagulating dip- forming composition of the present invention comprises copolymer particles each having polyvinyl alcohol bonded thereto which are obtainedbypolymerizing amonomer (M3) capable of forming a third polymer having a glass transition temperature (Tg3) of -85°C to +10°C in a first polymerization step, and then a monomer (M4) capable of forming a fourth polymer having a glass transition temperature (Tg4) of +40°C to +140°C in the sequential polymerization step, said polymerization steps being carried out in the presence of polyvinyl alcohol in an aqueous medium.
  • M3 polymerizing amonomer
  • Tg3 glass transition temperature of -85°C to +10°C in a first polymerization step
  • M4 monomer capable of forming a fourth polymer having a glass transition temperature (Tg4) of +40°C to +140°C in the sequential polymerization step
  • the third polymer has a glass transition temperature (Tg3) in the range of of -85°C to +10°C, preferably -60°C to 0°C and more preferably -50°C to -20°C. If Tg3 is too low, gloves have poor blocking resistance and are liable to stick to each other. In contrast, if Tg3 is too high, a dusting powder is liable to be easily separated from gloves.
  • Tg3 glass transition temperature
  • the fourth polymer has a glass transition temperature (Tg4) in the range of +40°C to +140°C, preferably +40°C to +100°C and more preferably +50°C to +80°C. If Tg4 is too low, a dip-formed article has poor blocking resistance. In if Tg4 is too high, a dusting powder is liable to be easily separated from a dip-formed article.
  • Tg4 glass transition temperature
  • the monomers M3 and M4 used for the preparation of the copolymer latex are not particularly limited provided that they are capable of being radically polymerized, and they include, for example, conjugated diene monomers, aromatic vinyl monomers , ethylenically unsaturated carboxylic acid ester monomers , ethylenically unsaturated carboxylic acid amide monomers and ethylenically unsaturated nitrile monomers . Of these, aromatic vinyl monomers and ethylenically unsaturated carboxylic acid ester monomers are preferable. Ethylenically unsaturated carboxylic acid ester monomers are especially preferable. As specific examples of these monomers , there can be mentioned those which are recited above as the monomers used for the preparation of the coating composition of the present invention.
  • the monomers M3 and the monomers M4 are appropriately chosen from those which have Tg3 and Tg4, respectively.
  • the respective monomers M3 and M4 may be used either alone or as a mixture of at least two thereof.
  • BA n-butyl acrylate
  • BA amixture of n-butyl acrylate
  • MMA methyl methacrylate
  • the mixed ratio by weight of BA/MMA is preferably in the range of 100/0 to 45/55, more preferably 100/0 to 70/30 and especially preferably 100/0 to 90/10.
  • monomers M4 there can be mentioned a mixture of BA and MMA, and MMA alone .
  • the mixed ratio by weight of BA/MMA is preferably in the range of 30/70 to 0/100, more preferably 25/75 to 5/95 and especially preferably 20/80 to 15/85.
  • the ratio by weight of M3/M4 is preferably in the range of 20/80 to 80/20, more preferably 25/75 to 70/30 and especially 30/70 to 50/50.
  • the kind and amount of an aqueous medium used for the preparation of the copolymer latex may be the same as those of an aqueous medium used for the preparation of the polymer latex in the coating composition.
  • the amount of PVA is preferably in the range of 0.5 to 60 parts by weight, more preferably 1 to 30 parts by weight and especially preferably 2 to 20 parts by weight, based on 100 parts by weight of the monomers. If the amount of PVA is too small, a large amount of aggregates is liable to be produced when the resulting copolymer latex is mixed with an inorganic metal salt coagulant, and the polymerization stability becomes poor, a large amount of aggregates are also produced at a polymerization step, and mechanical properties of the resulting copolymer latex are poor. In contrast, if the amount of PVA is too large, the removal of polymerization heat becomes difficult because of an increase in viscosity of a polymerization system, and the polymer latex has a too high viscosity to handle.
  • the amount of PVA used in each of the first polymerization step and the sequential second polymerization step is preferably in the above-mentioned range.
  • a surf ce active agent having a lowmolecularweight, i. e. , below about 1,000, conventionally used in a polymerization for a polymer latex is preferably not used in a polymerization for the preparation of the copolymer latex used in the coagulating dip-forming composition, or, even when it is used, the amount thereof should preferably be below 0.5 part by weight and more preferably below 0.2 part by weight , based on 100 parts by weight of the monomers .
  • the resulting copolymer particles do not have PVA bonded thereto, with the result that a large amount of aggregates is liable to be produced in the coagulating dip-forming composition, and separation of a dusting powder from a dip-formed article becomes prominent.
  • the manner in which PVA is used is not particularly limited, but , there can be adopted amethod of previously adding the entire amount of PVA into a polymerization vessel, a method of adding a part of PVA prior to the commencement of polymerization and adding the remainder of PVA after the commencement thereof to a polymerization vessel, and a method of adding PVA continuously or intermittently at the commencement of and along with the progress of polymerization.
  • the manner in which the monomers are added into a polymerization vessel is not particularly limited, provided that the above-mentioned sequential two-stage polymerization can be effected. But , there can be adopted amethod of previously adding the entire amount of monomers before the commencement of polymerization, a method of adding a part of the monomers prior to the commencement of polymerization and adding the remainder of monomers after the commencement thereof, and a method of adding the monomers continuously or intermittently at the commencement of and along with the progress of polymerization. Of these, the method of adding the monomers continuously or intermittently at the commencement of and along with the progress of polymerization is preferable.
  • the procedure by which the monomers and PVA are added into a polymerization vessel is not particularly limited.
  • the monomers and PVA can be added either separately or as a monomer emulsion prepared bymixing together the monomers , PVA and water.
  • the addition of the monomers and PVA is substantially concurrently commenced and substantially concurrently terminated.
  • a method of continuously adding the monomers and PVA in the form of a monomer emulsion prepared by mixing together the monomers, PVA and water is preferable.
  • the rate of continuously adding the monomers is not particularly limited, but, the rate of addition is preferably controlled so that a polymerization conversion of at least 30% by weight, more preferably at least 50% by weight and especially preferably at least 70% by weight is maintained during polymerization.
  • the rate of addition of the monomers is too high, the polymerization conversion tends to be decreased and coarse particles are liable to be produced.
  • a polymerization initiator used for polymerization of the monomers may be chosen from those which are conventionally used for emulsion polymerization.
  • the kind, amount and manner of addition of the polymerization initiator can be the same as the kind, amount and manner of addition of the polymerization initiator used for the preparation of polymer latex in the coating composition.
  • the polymerization for production of the above-mentioned copolymer latex is preferably carried out in the presence of a water-soluble alcohol.
  • the kind, amount and manner of addition of the alcohol can be the same as the kind, amount and manner of addition of the alcohol used for the preparation of polymer latex in the coating composition.
  • a chain transfer agent may be used at polymerization, although it is not indispensable.
  • the kind, amount and manner of addition of the chain transfer agent can be the same as the kind, amount and manner of addition of the chain transfer agent used for the preparation of polymer latex in the coating composition.
  • the polymerization temperature is not particularly limited, but, is usually in the range of 0 to 100°C, preferably 50 to 95°C.
  • the second stage polymerization is commenced preferably when the polymerization conversion reaches at least 80%, more preferably at least 90% and especially preferably at least 95% at the first stage polymerization because a dip-formed article having good and balanced anti-blocking property and anti- separation of dusting powder can be obtained.
  • the polymerization is terminated.
  • the termination of polymerization is carried out by adding a polymerization terminator or cooling a polymerization system.
  • the value of polymerization conversion at which the polymerization is terminated is preferably at least 90% by weight, more preferably at least 93% by weight and more preferably at least 95% byweight .
  • unreacted monomers may be removed.
  • the copolymer latex used in the present invention may have incorporated therein additives such as a ⁇ helating agent, a dispersant, a pH adjuster, an antiseptic, a plasticizer and a defoaming agent . These additives can be added during or after polymerization.
  • the thus-produced copolymer latex comprises copolymer particles each having PVA bonded thereto.
  • the amount of PVA bonded to the copolymer particles is preferably in the range of 0.3 to 30 parts by weight, more preferably 0.5 to 20 parts by weight and especially preferably 1 t 10 parts by weight , based on 100 parts by weight of the copolymer particles produced by polymerization.
  • the amount of PVA bonded is too small, aggregates are liable to occur in the coagulating dip-forming composition.
  • the amount of PVA bonded is too large, balance between the anti-blocking property and the anti-separation of dusting powder tends to become deteriorated.
  • the amount of PVA bonded to the copolymer particles can appropriately be varied by controlling, for example, the kind and amount of PVA used, the kind and amount of polymerization initiator, and the polymerization temperature.
  • the copolymer particles preferably have a volume average particle diameter in the range of 50 to 5,000 nm, more preferably 80 to 2,000 nm and especially preferably 100 to 1,000 nm. If the volume average particle diameter is too small, the polymerization mixture becomes too viscous during polymerization, and the resulting polymer is difficult to handle, in contrast , if the volume average particle diameter is too large, a dip-formed article tends to have poor anti-separation of dusting powder.
  • the dip-forming coagulating composition of the present invention is prepared by mixing together the above-mentioned copolymer latex with a coagulant for dip-forming.
  • the coagulant for dip-forming can be those which are conventionally used for dip-forming, and includes, for example, water-soluble polyvalent metal salts which metals are selected from groups 2, 12 and 13 of the periodic table.
  • halides such as barium chloride, calcium chloride, magnesium chloride, zinc chloride and aluminum chloride
  • nitric acid salts such as barium nitrate, calcium nitrate and zinc nitrate
  • acetic acid salts such as barium acetate, calcium acetate and zinc acetate
  • sulfuric acid salts such as calcium sulfate, magnesium sulfate and aluminum sulfate.
  • calcium chloride and calcium nitrate are preferable.
  • These coagulants for dip-forming can be used either alone or as a combination of at least two thereof .
  • the coagulant for dip-forming is usually used in a solution form, preferably in an aqueous solution form.
  • the aqueous solution used can contain a lower alcohol such as methanol and ethanol.
  • the concentration of coagulant for dip-forming in the solution varies depending upon the particular kind of coagulant , but is usually in the range of 5 to 70% by weight, preferably 20 to 50% by weight.
  • the coagulant solution is usually used at a temperature in the range of 0 to 90°C, preferably 25 to 70°C.
  • the amount of the copolymer latex is preferably such that the concentration of copolymer latex as solid content in the dip-forming coagulating composition is in the range of 0.3 to 10% by weight , more preferably 0.5 to 10% byweight and especially preferably 1 to 4% by weight.
  • the dip-forming coagulating composition of the present invention can further contain finely divided particles provided that the effect of the invention can be obtained.
  • the kind, volume average particle diameter and shape of finely divided particles are the same as those of finely divided particles to be incorporated in the above-mentioned coating composition.
  • the amount of finely divided particles is usually not larger than 200 parts by weight, preferably not larger than 150 parts by weight and more preferably not larger than 100 parts byweight , based on 100 parts by weight of the solid content in the copolymer latex.
  • the dip-forming coagulating composition may have incorporated therein additives such as a thickener, a wetting agent, a defoaming agent, a pH adjuster, an antioxidant , an antiseptic and an anti-fungus agent.
  • additives such as a thickener, a wetting agent, a defoaming agent, a pH adjuster, an antioxidant , an antiseptic and an anti-fungus agent.
  • a dip-formed article, from which a dusting powder is separated only to a slight extent and which has an outer surface exhibiting reduced stickiness can be obtained by conducting dip-forming using the above-mentioned dip-forming coagulating composition.
  • the dip-forming procedure is not particularly limited, and includes, for example, an anode cohesion dip-forming procedure, a Teague cohesion dip-forming procedure and a combination of these procedures.
  • an anode cohesion dip-forming procedure is preferable because a dip-formed article having a uniform thickness is easily obtained.
  • the anode cohesion dip-forming procedure using the above-mentioned dip-forming coagulating composition is carried out by the following process.
  • the process comprises the steps of dipping a form in the above- mentioned dip-forming coagulating composition to form a layer comprised of the dip-forming coagulating composition on the form; dipping the form having the coagulating composition layer thereon in a dip-forming composition to form a coagulated layer comprised of the dip-forming composition; curing the coagulated layer comprised of the dip-forming composition to form a cured coagulated layer; and then; releasing the cured coagulated layer from the form, while the cured coagulated layer is reversed.
  • the dip-forming form used includes those which are made from porcelain, ceramics, metals, glass and plastic materials .
  • the dip-forming form used is a glove form having the contour of a human hand.
  • the glove form includes various forms which are, for example, a form having the contour spanning from a wrist to finger tips, and a form having the contour spanning an elbow to finger tips .
  • the dip-forming composition may be made from a natural rubber latex or a synthetic rubber latex.
  • the synthetic rubber latex includes, for example, a styrene-butadiene copolymer latex, an acrylonitrile-butadiene copolymer latex and a carboxyl-modified acrylonitrile-butadiene copolymer latex.
  • the dip-forming composition usually comprises the synthetic rubber latex and/or natural rubber latex, a sulfur vulcanizer, a vulcanization accelerator and zinc oxide.
  • the solid content in the dip-forming composition is usually in the range of 10 to 40% by weight.
  • the amounts of sulfur, vulcanization accelerator and zinc oxide can be appropriately chosen depending upon the intended properties of a dip-formed article.
  • the time for which a dip-forming form is dipped in the dip-forming coagulating composition; the temperature and time for drying the dip-forming form having the coagulating composition layer thereon; the time for which the form having the dried coagulation composition layer is dipped in a dip- forming composition to form a coagulated layer comprised of the dip-forming composition; and the temperature and time for drying the formhaving the coagulated layer comprised of the dip-forming composition are appropriately chosen.
  • the vulcanization conditions employed for vulcanizing the coagulated layer varies depending upon the particular dip- forming composition used, but, the vulcanization is usually carried out usually at a temperature of 100 to 130°C for 10 to 60 minutes.
  • the coagulated layer Before the vulcanization of the coagulated layer, the coagulated layer can be washed with water to remove excessive coagulant and water-soluble impurities, or, a coating can be formed on the coagulated layer.
  • the vulcanized coagulated layer is coated with a surface coating layer or washed with water, if desired, and then, the vulcanized coagulated layer is released from the form while the coagulated layer is reversed, whereby a dip-formed article having an outer coating layer formed from the above-mentioned dip-forming coagulation composition is obtained. If desired, the thus-obtained dip-formed article is washed with water to remove excessive coagulant and water- soluble impurities .
  • the amount of the coating layer formed from the dip-forming coagulating composition is not particularly limited, but the solid content of the coating layer per unit surface area of the dip-formed article is preferably in the range of 0.1 to 2 g/m 2 , more preferably 0.15 to 1.5 g/m 2 .
  • the amount of the coating layer can be appropriately varied depending upon the concentration of solid content of copolymer latex in the dip-forming coagulating composition, and the conditions for dipping a dip-forming form in the dip-forming coagulating composition.
  • Each of the dip-formed article (1) having a coating layer formed from the above-mentioned coating composition, and the dip-formed article (2) made by using the above-mentioned dip-forming coagulating composition can have a thickness in the range of about 0.1 mm to about 3 mm.
  • the dip-formed articles are useful as a thin dip-formed article characterized by a thickness of about 0.1 to about 0.3 mm.
  • the volume average particle diameter is measured by Coulter LS230 (particle size analyzer available from Coulter Co. )
  • a polymer latex In the case of a polymer latex, a polymer latex is cast on a glass plate having frames at the peripheral edges. The as-cast polymer latex is left to stand in a thermo-hygrostat maintained at a temperature of 20°C and a relative humidity of 65% for 48 hours to give a filmy specimen.
  • an aqueous dispersion of finely divided organic particles is cast on a glass plate, and the as-cast dispersion is left to stand in a thermo-hygrostat maintained at a temperature of 20°C and a relative humidity of 65% for 48 hours to give a dry filmy specimen.
  • the glass transition temperature is measured on each filmy specimen according to JIS K 7121 by using a differential scanning calorimeter ("SSC 5200" available from Seiko Instruments Inc.) at an initiation temperature of -100°C and a temperature elevation rate of 5°C/min.
  • SSC 5200 differential scanning calorimeter
  • the solid content of a copolymer latex is adjusted to 10% .
  • 60 g of the copolymer latex is taken as a specimen, and subjected to centrifugal separation at a temperature of 5°C and a revolution rate of 13,000 rpm for 60 minutes by using a centrifugal separator "H-2000" available from Kokusan Centrifugal Separator K.K.
  • 50 g of a supernatant liquid is removed.
  • 50 g of distilled water is added to a sediment (10 g) and uniformly mixed together. Again, the mixture is subjected to centrifugal separation, 50 g of a supernatant is removed, and then, 50 g of distilled water is added to a sediment.
  • a dip-forming coagulating composition having a copolymer latex incorporated therein 200 ml of a dip-forming coagulating composition having a copolymer latex incorporated therein is placed in a glass bottle and sealed.
  • the glass bottle is left to stand in a thermostat maintained at a temperature of 50°C for 24 hours. Then the bottle is left to stand at room temperature.
  • the dip-forming coagulating composition is cooled to room temperature, the coagulating composition is filtered by a wire mesh with a mesh size of 325 mesh and a residue on the wire mesh is thoroughly washed with distilled water, and then dried with hot air at 60°C.
  • the dried residue is weighed to determine the amount of aggregates , and the percentage of the amount of aggregates based on the solid content of copolymer latex in the dip-forming coagulating composition is calculated.
  • a form having a coagulated and cured glove-contoured polymer layer is hung down from a load cell of tensilon tensile tester "UTM-250" available from Toyo Baldwin Co. so that tip ends of fingers of the glove-contoured polymer layer are downward directed.
  • the form having the glove-contoured polymer layer is heated.
  • the temperature of palm of the glove-contoured polymer layer is measured by a laser non-contact type thermometer "THI 44ON" available from TASCO Co.
  • TTI 44ON available from TASCO Co.
  • the above test is repeated five times to measure the maximum stress in tension.
  • the minimum value and the maximum value are removed from the five values of release stress , an average release stress value is calculated on the remaining three values. The smaller the average release stress value, the easier the release of glove from the form.
  • a glove is put on and then put off in a state such that the inner, ski -contacting surface is dry. Ease of donning and putting off the dry glove is evaluated according to the following criteria.
  • a load of 9.8 KPa is imposed from outside onto a glove having an inner coating layer whereby the inner coating layer is pressed against upon another.
  • the load-imposed glove and the superposed gloves are allowed to stand for 24 hours in a thermo-hygrostat oven maintained at a temperature of 60°C and a relative humidity of 95%. Thereafter the glove is taken out and the stuck portions of coating layers are peeled from each other, and the peelability is evaluated according to the following criteria.
  • the blocking resistance is expressed by the following three ratings.
  • the amount of resin particles separated from a glove having an inner coating layer having incorporated therein fine particles is measured according to ASTM D6124-97. The smaller the amount of resin particles, the better the fine particles-separability.
  • a pressure-resistant vessel equipped with a stirrer was charged with 45 parts of deionized water, 2.5 parts of butyl acrylate, 47.5 parts of methyl methacrylate and 2.5 parts of polyvinyl alcohol ("PVA-205" available from Kuraray Co. Ltd.; average degree of polymerization: 500, degree of saponification: 88% by mole) .
  • the content was stirred to prepare a monomer emulsion I .
  • Another pressure-resistant vessel equippedwith a stirrer was charged with 45 parts of deionized water, 26.5 parts of butyl acrylate, 22.5 parts of methyl methacrylate, 1 part of 2- hydroxyethyl acrylate and 1.5 parts of polyvinyl alcohol ("PVA-224" available from Kuraray Co. Ltd.; average degree of polymerization: 2,400, degree of saponification: 88% by mole).
  • PVA-224" available from Kuraray Co. Ltd.; average degree of polymerization: 2,400, degree of saponification: 88% by mole.
  • a pressure-resistant reaction vessel equipped with a stirrer was charged with 70 parts of deionized water and 8 parts of ethanol, and the temperature of the content was elevated to 80°C. While the temperature was maintained at 80°C, the continuous addition of the above-mentioned monomer emulsion I was commenced. Then, a polymerization initiator solution comprising 0.3 part of potassium persulfate in 10 parts of deionized water was added. The addition of the monomer emulsion I was continued over a period of 2 hours. After completion of the addition of monomer emulsion I, the reaction mixture was stirred further for 40 minutes . The polymerization conversion was 99% .
  • the monomer emulsion II was continuously added to the reaction vessel over a period of 2 hours. After completion of the addition of monomer emulsion II, the reaction mixture was stirred further for 2 hours and then cooled to terminate polymerization. At the termination of polymerization, the polymerization conversion was 98%.
  • the polymer latex A had a volume average particle diameter of 350 nm and two glass transition temperatures of -2°C and +94°C.
  • the solid content of polymer latex A was adjusted to 8% to prepare a coating composition Al.
  • the coagulant-deposited glove form was dipped in the above-mentioned dip-forming latex formulation for 10 seconds, and then taken out.
  • the dip-forming latex formulation-applied glove form was then dried at 60°C for 5 minutes. Then the glove was dipped in warm water at 50°C for 5 minutes and then dried at 60°C for 5 minutes.
  • the coating agent-applied glove form was dried at 70°C for 10 minutes in a drier, and further heat-treated at 120°C for 25 minutes to give a glove form having a solid vulcanized rubber film on the outer periphery.
  • the solid vulcanized rubber film was stripped from the glove form, while the solid vulcanized rubber film was reversed to obtain a rubber glove having an inner coating layer.
  • the rubber glove had a wall thickness of 0.15 mm, and the coating layer had a weight of 1 g/m 2 .
  • the properties of the rubber glove were evaluated. The results are shown in Table 1.
  • Polymer latex B was prepared by the same procedures as described in Example 1 except that monomer emulsion I, monomer emulsion II, and the time for continuous addition of monomer emulsions I and II were varied as shown in Table 1. Volume average particle diameter and glass transition temperature of polymer latex B were evaluated. The results are shown in Table 1.
  • a dip-formed article (rubber glove) was made by the same procedures as mentioned in Example 1 except that polymer latex B was used instead of polymer latex A. The properties of rubber glove were evaluated. The results are shown in Table 1.
  • Polymer latex C was prepared by the same procedures as described in Example 1 except that monomer emulsion I andmonomer emulsion II were varies as shown in Table 1, were used. Volume average particle diameter and glass transition temperature of polymer latex C were evaluated. The results are shown in Table 1.
  • a dip-formed article (rubber glove) was made by the same procedures as mentioned in Example 1 except that polymer latex C was used instead of polymer latex A. The properties of rubber glove were evaluated. The results are shown in Table 1.
  • Polymer latex D was prepared by the same procedures as described in Example 1, except that only monomer emulsion I, shown in Table 1, was used and polymerization was carried out in a single stage. Volume average particle diameter and glass transition temperature of polymer latex D were evaluated. The results are shown in Table 1.
  • a dip-formed article (rubber glove) was made by the same procedures as mentioned in Example 1 except that polymer latex D was used instead of polymer latex A. The properties of rubber glove were evaluated. The results are shown in Table 1.
  • Coating composition CI comprising polymer latex C having Tgl higher than that stipulated in the present invention gives a dip-formed article which can be easily released from a form and exhibits good donning and putting off property and good blocking resistance, but exhibits undesirably large particles-separability (Comparative Example 1).
  • Coating composition D comprising polymer latex D having a single glass transition temperature (i.e. , not having two glass transition temperatures) gives a dip-formed article which cannot be easily released from a form and exhibits poor donning and putting off property and poor blocking resistance, and large fine particles-separability (Comparative Example 2).
  • coating composition Al or Bl comprising polymer latex A or B, which falls within the range stipulated in the present invention, gives a dip-formed article which can be easily released from a form and exhibits good donning and putting off property and good blocking resistance, and reduced fine particles-separability (Examples 1 and 2).
  • Table 1
  • An aqueous PVA solution was prepared by dissolving 2.1 parts of PVA (average degree of polymerization: 500, degree of saponification: 88% by mol) in 200 parts of deionized water.
  • a monomer solution was prepared by mixing together 92.8 parts of styrene, 7 parts of butyl acrylate,0.2 part of divinylbenzene, 0.9 part of t-dodecyl mercaptan and 5 parts of benzoyl peroxide (BPO) .
  • BPO benzoyl peroxide
  • a temperature-controllable polymerization vessel equipped with a stirrer was charged with the fine liquid dispersion .
  • the inner atmosphere was substitutedwith nitrogen, and the content was heated to 90°C to initiate polymerization.
  • the polymerization mixture was cooled to terminate polymerization.
  • the polymerization conversion was 97% at termination of polymerization. Unreacted monomers were removed to give an aqueous fine organic particle dispersion having a solid content of 30%.
  • the fine organic particles had a volume average particle diameter of 4.6 m.
  • the polymer of the particles had a glass transition temperature of 92°C.
  • a dip-formed article was made by the same procedures as described in Example 1 except that coating composition A2 was used instead of coating composition Al .
  • the properties of the dip-formed article were evaluated. The results are shown in Table 2.
  • a dip-formed article was made by the same procedures as described in Example 3 except that the recipe shown in Table 2 was employed. The properties of the dip-formed article were evaluated. The results are shown in Table 2. Table 2
  • coating composition D2 comprising polymer latex D having a single glass transition temperature, i.e., not having two glass transition temperatures, and containing fine organic particles gives a dip-formed article exhibiting good donning and putting-off property, but having poor releasability from a form and undesirably large separation of fine particles (Comparative Example 3)
  • coating composition A2 or B2 comprising polymer latex A or B, which falls within the range stipulated in the present invention, and further comprising fine organic particles gives a dip-formed article which can be easily released from a form and exhibits good donning and putting-off property and good blocking resistance, and reduced fine particles- separability (Examples 3 and 4).
  • a pressure-resistant vessel equipped with a stirrer was charged with 28 parts of deionized water, 29.2 parts of butyl acrylate, 3.3 parts of methyl methacrylate and 1.75 parts of polyvinyl alcohol ("PVA-205" available from Kuraray Co. Ltd.; average degree of polymerization: 500, degree of saponification: 88% by mole) .
  • the content was stirred to prepare a monomer emulsion I .
  • Another pressure-resistant vessel equipped with a stirrer was charged with 52 parts of deionized water, 11.7 parts of butyl acrylate, 55.8 parts of methyl methacrylate and 3.25 parts of polyvinyl alcohol ("PVA-205" available from Kuraray Co. Ltd.; average degree of polymerization: 500, degree of saponification: 88% by mole) .
  • PVA-205" available from Kuraray Co. Ltd.; average degree of polymerization: 500, degree of saponification: 88% by mole
  • a pressure-resistant reaction vessel equipped with a stirrer was charged with 70 parts of deionized water and 8 parts of ethanol, and the temperature of the content was elevated to 80°C. While the temperature was maintained at 80°C, the continuous addition of the above-mentioned monomer emulsion I was commenced. Then, a polymerization initiator solution comprising 0.3 part of potassium persulfate in 10 parts of deionized water was added. The addition of the monomer emulsion I was continued over a period of 90 minutes. After completion of the addition of monomer emulsion I , the reaction mixture was stirred further for 40 minutes. The polymerization conversion was 99%.
  • the monomer emulsion II was continuously added to the reaction vessel over a period of 180 minutes . After completion of the addition of monomer emulsion II, the reaction mixture was stirred further for 2 hours and then cooled to terminate polymerization. At the termination of polymerization, the polymerization conversion was 98%.
  • a polymer latex E having a solid content of 40%.
  • the polymer latex E had a volume average particle diameter of 450 nm and two glass transition temperatures of -48°C and +63°C.
  • the amount of PVA bonded to the copolymer was 2.6 parts based on 100 parts of the copolymer.
  • a glove form made of porcelain was dipped in the above-mentioned dip-forming coagulating composition El for 1 minute, and then taken out therefrom.
  • the coagulating composition-applied glove form was dried at 50°C for 3 minutes thereby to deposit the coagulating composition on the glove form.
  • the coagulating composition-deposited glove form was dipped in the above-mentioned dip-forming latex formulation for 10 seconds, and then taken out.
  • the dip-forming latex formulation-applied glove form was then dried at 60°C for 5 minutes. Then the glove was dipped in warm water at 50°C for 5 minutes and then dried at 60°C for 5 minutes.
  • the glove form was heat-treated at 120°C for 25 minutes to give a glove form having a solid vulcanized rubber film on the outer periphery.
  • the solid vulcanized rubber film was stripped from the glove form, while the solid vulcanized rubber film was reversed to obtain a rubber glove having an outer coating layer.
  • the rubber glove had a wall thickness of 0.15 mm, and the coating layer had a weight of 1 g/m 2 .
  • the properties of the rubber glove were as shown in Table 3.
  • Copolymer latex F was prepared by the same procedures as described in Example 5, wherein monomer emulsion I, monomer emulsion II, and the time for continuous addition of monomer emulsions I and II were varied as shown in Table 3.
  • PVA "PVA-224" available from Kuraray Co. Ltd.; average degree of polymerization: 2,400, degree of saponification: 88% by mole) was used instead of PVA-205.
  • a dip-forming coagulating composition Fl was prepared by the same procedures as described in Example 5 except that copolymer latex F was used instead of copolymer latex E.
  • a dip-formed article (rubber glove) was made by the same procedures as mentioned in Example 5 except that dip-forming coagulating composition Fl was used instead of dip-forming coagulating composition El .
  • the properties of rubber glove were as shown in Table 3.
  • Copolymer latex G was prepared by the same procedures as described in Example 5 , except that monomer emulsion I and monomer emulsion II were varied as shown in Table 3. Instead of PVA, sodium alkyl-diphenyl-ethersisulfonate (anionic surface active agent; "Pelex SS-H” available from Kao Corp.) and polyoxyethylene-lauryl-ether (nonionic surface active agent; "Emulgen 120" available from Kao Corp.) were used.
  • Copolymer latex G was prepared without use of PVA, and therefore measurement of the amount of PVA bonded thereto was not conducted.
  • an aqueous solution of 5 parts (as solid content) of PVA ( "PVA-205" available from Kuraray Co. , Ltd.) was incorporated in 100 parts by weight (as copolymer) of copolymer latex G. Measurement of the amount of PVA bonded to the copolymer was conducted, but, PVA bonded thereto was not detected. This means that free PVA is substantially removed by the above-mentioned procedures employed for the measurement of amount of PVA bonded to copolymer.
  • a dip-forming coagulating composition Gl was prepared by the same procedures as described in Example 5 except that copolymer latex G was used instead of copolymer latex E.
  • a dip-formed article (rubber glove) was made by the same procedures as mentioned in Example 5 except that dip-forming coagulating composition Gl was used instead of dip-forming coagulating composition El .
  • the properties of rubber glove were as shown in Table 3.
  • Copolymer latex H was prepared by the same procedures as described in Example 5 except that only monomer emulsion I , shown in Table 1 , was used and polymerization was carried out in a single stage.
  • a dip-forming coagulating composition HI was prepared by the same procedures as described in Example 5 except that copolymer latex H was used instead of copolymer latex E.
  • a dip-formed article (rubber glove) was made by the same procedures as mentioned in Example 5 except that dip-forming coagulating composition HI was used instead of dip-forming coagulating composition El .
  • the properties of rubber glove were as shown in Table 3.
  • a dip-formed article (1) coated with the coating composition of the present invention is easily released from a dip-forming form, has good blocking resistance and good donning and putting-off property, and finely particles are separated only in a slight amount from the dip-formed article.
  • the dip-forming coagulating composition of the present invention is characterized in that aggregates occur only to a negligible extent in the coagulating composition, and a dip-formed article ( 2 ) made by using the coagulating composition is characterized in that finely particles are separated only in a slight amount from the dip-formed article, and the outer surfaces of the dip-formed articles do not stick or stick only to a negligible extent to each other.
  • dip-formed articles (1) and (2) are useful as, for example, a nipple of nursing bottle, medical articles such as a dropper, a duct and a water pillow; toys such as a balloon, dolls and a ball, and sporting goods such as a ball; industrial articles such as a pressure molding bag and a gas storage bag; unsupported gloves and supported gloves for surgical, household, agricultural and industrial uses; and a finger cot.
  • the dip-formed articles are advantageously used as gloves , especially a thin glove such as a thin surgical glove .

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  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Dispersion Chemistry (AREA)
  • Graft Or Block Polymers (AREA)
  • Paints Or Removers (AREA)

Abstract

Une composition de latex polymère comprenant un polymère dont la température de transition vitreuse (Tg) va de 85 à +30 °C et un polymère dont la Tg va de +40 à 140 °C, les polymères étant stabilisés en dispersion par un alcool de polyvinyle (PVA). De préférence, la composition de latex polymère est (1) une composition de revêtement comprenant un polymère d'une Tg de 2 à +30 °C et un deuxième polymère d'une Tg de +60 à +140 °C, ou (2) utilisé pour la préparation d'une composition coagulante de formation par immersion comprenant un coagulant et un latex polymère comprenant des particules copolymères auxquelles adhère le PVA, qui s'obtiennent par polymérisation d'un monomère capable de former un troisième polymère d'une Tg de 85 à +10 °C dans une première étame, et ensuite un monomère capable de former un quatrième polymère d'une Tg de +40 ) +140 °C dans l'étape séquentielle. La polymérisation pour préparer le premier jusqu'au quatrième polymère s'exécute en présence de PVA dans un milieu aqueux.
PCT/JP2003/000657 2002-01-24 2003-01-24 Composition de latex polymere, articles formes par immersion, et procede de production d'articles formes par immersion WO2003062307A2 (fr)

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JP2002015707A JP2003213197A (ja) 2002-01-24 2002-01-24 コーティング剤およびディップ成形品
JP2002-015707 2002-01-24
JP2002188921A JP2004027135A (ja) 2002-06-28 2002-06-28 ディップ成形用凝固剤組成物、ディップ成形品およびその製造方法
JP2002-188921 2002-06-28

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EP1634894A1 (fr) * 2004-09-09 2006-03-15 PolymerLatex GmbH Latex polymére pour la préparation d'un produit moulé par trempage
US8158691B2 (en) 2005-04-04 2012-04-17 Polymer Latex Gmbh & Co. Kg Aqueous reinforced rubber dispersions and their use for making latex foams
US8222362B2 (en) 2006-08-10 2012-07-17 Polymerlatex Gmbh Latex with reduced odor
US8399105B2 (en) 2004-09-09 2013-03-19 Polymer Latex Gmbh & Co., Kg Polymer latex suitable for the preparation of dip-molded articles
RU2624292C1 (ru) * 2016-05-04 2017-07-03 Яков Самойлович Фрейдзон Полимерная латексная система для использования в лакокрасочных материалах
CN115515994A (zh) * 2020-05-05 2022-12-23 瓦克化学股份公司 聚乙烯醇稳定化的(甲基)丙烯酸酯聚合物

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DE19954619A1 (de) * 1999-11-12 2001-05-17 Basf Ag Wässrige Polymerdispersionen

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US4181769A (en) * 1976-06-17 1980-01-01 Rohm And Haas Company Heteropolymer acrylic latices and textiles treated therewith
US5207954A (en) * 1989-09-25 1993-05-04 Union Carbide Chemicals & Plastics Technology Corporation Method of making coreactable powdered coatings
DE19954619A1 (de) * 1999-11-12 2001-05-17 Basf Ag Wässrige Polymerdispersionen

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1634894A1 (fr) * 2004-09-09 2006-03-15 PolymerLatex GmbH Latex polymére pour la préparation d'un produit moulé par trempage
WO2006027164A1 (fr) * 2004-09-09 2006-03-16 Polymerlatex Gmbh Latex polymere adapte a la fabrication d'articles moules au trempe
CN101014628B (zh) * 2004-09-09 2010-06-30 聚合体弹性织物有限公司 适合于制备蘸塑制品的聚合物胶乳
US8399105B2 (en) 2004-09-09 2013-03-19 Polymer Latex Gmbh & Co., Kg Polymer latex suitable for the preparation of dip-molded articles
KR101259200B1 (ko) 2004-09-09 2013-04-29 폴리머라텍스 게엠베하 딥-성형된 물품의 제조에 적합한 폴리머 라텍스
US8158691B2 (en) 2005-04-04 2012-04-17 Polymer Latex Gmbh & Co. Kg Aqueous reinforced rubber dispersions and their use for making latex foams
US8222362B2 (en) 2006-08-10 2012-07-17 Polymerlatex Gmbh Latex with reduced odor
RU2624292C1 (ru) * 2016-05-04 2017-07-03 Яков Самойлович Фрейдзон Полимерная латексная система для использования в лакокрасочных материалах
CN115515994A (zh) * 2020-05-05 2022-12-23 瓦克化学股份公司 聚乙烯醇稳定化的(甲基)丙烯酸酯聚合物
CN115515994B (zh) * 2020-05-05 2024-02-13 瓦克化学股份公司 聚乙烯醇稳定化的(甲基)丙烯酸酯聚合物

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