Patent GB-796199-A (GB)
Title: Process for the production of moulded articles by a dipping process
IPC: B29C41/14
Filed: 1956-02-13
Abstract: Elastic articles are moulded by a process which comprises dipping a former, in any desired sequence, into a copolymer bath comprising a solution or emulsion of a synthetic copolymer containing reactive groups and into a coagulating bath containing agents capable of reacting with the reactive groups of said copolymer with cross-linking, and thereafter washing and drying the dip-moulded articles.  Suitable synthetic copolymers consist essentially of linear carbon chains to which are linked 0.005-0.6 mols. by weight of reactive groups per 100 parts by weight of polymers.  The polymers are obtained by copolymerizing, in aqueous emulsion, monomers which have polymerizable carbon-to-carbon double bonds and have an elasticizing action and copolymerizable ethylenically unsaturated organic compounds with one or more carbonyl, carboxyl, sulphonic acid carbonamide or basic nitrogen groups.  Among such monomers are acrylic acid esters or methacrylic acid esters of aliphatic alcohols with at least 4 carbon atoms, vinyl alkyl ethers the alkyl radical of which contains 1-8 carbon atoms, and compounds with two conjugate carbon-to-carbon double bonds, e.g. butadiene or homologues and derivatives thereof.  Other organic compounds each containing at least one polymerizable carbonto-carbon double bond may be used, such as styrene, acrylonitrile, or methacrylic acid esters of alcohols with 1-3 carbon atoms.  Also suitable are such copolymerizable compounds as have their reactive groups present in masked form and liberated by reaction with a hydrolysing agent after the polymerization, e.g. saponifiable esters, vinylsulphonic alkylesters, unsaturated nitrile or unsaturated amides.  The copolymer bath used consists of a solution or emulsion of the synthetic copolymer. Suitable solvents are aromatic hydrocarbons such as benzene and compounds thereof, ketones and compounds thereof or mixtures of such solvents.  Examples of emulsifiers are the alkali salts of paraffin sulphonates obtained by sulphochlorination of long-chain paraffins with 12-18 carbon atoms and subsequent saponification.  The monomers may be polymerized in bulk or in solution and subsequently emulsified. The coagulating bath is a solution or emulsion of a polyamine, a salt of a polyamine, a polyepoxy compound, a water-soluble salt of a polyvalent metal, a water-soluble hydroxide of a polyvalent metal, an aldehyde, a polycarboxylic acid or an organic polysulphonic acid; and the groups capable of reacting with the cross-linking agents are carbonyl, carboxyl, sulphonic acid carbonamide or basic nitrogen groups.  The choice of group depends on the nature of the reactive groups of the copolymers.  For example, copolymers containing carbonyl groups are reacted with polyamines and polyamides containing at least two NH2 groups (e.g. ethylene diamine, butylene diamine, &c.), the carbonyl group reacting with the amino or amide groups with the formation of =C=N-linkages.  Suitable for copolymers containing acid groups, e.g. carboxyl and sulphonic acid, are polyamines containing at least two <FORM:0796199/IV (a)/1> groups, R1 and R2, which may be the same or different, standing for hydrogen atoms, alkyl radicals having 1-18 carbon atoms, or aryl radicals.  For copolymers containing basic groups, oxalic acid, itaconic acid and other polybasic organic acids are suitable.  In addition to the components which cause cross-linking, the coagulating bath may contain electrolytes having a coagulating action, e.g. sodium chloride, potassium chloride, &c.  The pH-value is governed by the type of reaction, instances being given in the Specification. The activation of the polymerization may be carried out with radical forming substances, e.g. azo dinitriles, or combinations of compounds yielding oxygen and reducing components.  Stabilizers may be used, e.g. a suitable phenol for copolymers of butadienes.  When butadiene polymers are used, vulcanizing agents and accelerators may be added to the emulsion.  The reaction of the epoxy and carboxyl groups may be accelerated by after-treating with alkaline agents. The emulsion or solution of the polymer may contain thickening agents such as polyvinylalcohol, salts of polyacrylic acid, &c. The temperature of the coagulating bath is generally 20-70 DEG  C. Natural or synthetic rubber latices or plastic emulsions, fillers, plasticizers, resins, dyestuffs, pigments, solvents, &c., may be added, or other high molecular weight polymers.  The dippings may be repeated to give uniform thick-walled mouldings, e.g. pipes and tubes.  The Specification contains a large number of detailed examples.ALSO:Elastic articles are moulded by a process which comprises dipping a former, in any desired sequence, into a copolymer bath comprising a solution or emulsion of a synthetic copolymer containing reactive groups and into a coagulating bath containing agents capable of reacting with the reactive groups of said copolymer with cross-linking, and thereafter washing and drying the dip-moulded articles.  Suitable synthetic copolymers consist essentially of linear carbon chains to which are linked 0,005-0,6 mols. by weight of reactive groups per 100 parts by weight of polymers.  The polymers are obtained by copolymerizing, in aqueous emulsion, monomers which have polymerizable carbon-to-carbon double bonds and have an elasticizing action and copolymerizable ethylenically unsaturated organic compounds with one or more carbonyl, carboxyl, sulphonic acid carbonamide or basic nitrogen groups.  Among such monomers are acrylic acid esters or methacrylic acid esters of aliphatic alcohols with at least 4 carbon atoms, vinyl alkyl ethers the alkyl radical of which contains 1-8 carbon atoms, and compounds with two conjugate carbon-to-carbon double bonds, e.g., butadiene or homologues and derivatives thereof.  Other organic compounds each containing at least one polymerizable carbon-to-carbon double bond may be used, such as styrene, acrylonitrile, or methacrylic acid esters of alcohols with 1-3 carbon atoms.  Also suitable are such copolymerizable compounds as have their reactive groups present in masked form and liberated by reaction with a hydrolysing agent after the polymerization, e.g., saponifiable esters, vinylsulphonic alkyl esters, unsaturated nitrile or unsaturated amides.  The copolymer bath used consists of a solution or emulsion of the synthetic copolymer.  Suitable solvents are aromatic hydrocarbons such as benzene and compounds thereof, ketones and compounds thereof or mixtures of such solvents. Examples of emulsifiers are the alkali salts of paraffin sulphonates obtained by sulphochlorination of long-chain paraffins with 12-18 carbon atoms and subsequent saponification.  The monomers may be polymerized in bulk or in solution and subsequently emulsified.  The coagulating bath is a solution or emulsion of a polyamine, a salt of a polyamine, a polyepoxy compound, a water soluble salt of a polyvalent metal, a water soluble hydroxide of a polyvalent metal, an aldehyde, a polycarboxylic acid or an organic polysulphonic acid; and the groups capable of reacting with the cross-linking agents are carbonyl, carboxyl, sulphonic acid carbonamide or basic nitrogen groups.  The choice of group depends on the nature of the reactive groups of the copolymers.  For example, copolymers containing carbonyl groups are reacted with polyamines and polyamides containing at least two NH2 groups (e.g. ethylene diamine, butylene diamine, &c.) the carbonyl group reacting with the amino or amide groups with the formation of =C=N- linkages.  Suitable for copolymers containing acid groups, e.g., carboxyl and sulphonic acid, are polyamines containing at least two <FORM:0796199/V/1> groups, R1 and R2, which may be the same or different, standing for hydrogen atoms, alkyl radicals having 1-18 carbon atoms, or aryl radicals.  For copolymers containing basic groups, oxalic acid, itaconic acid and other polybasic organic acids are suitable.  In addition to the components which cause cross-linking, the coagulating bath may contain electrolytes having a coagulating action, e.g., sodium chloride, potassium chloride &c. The pH value is governed by the type of reaction, instances being given in the Specification.  The activation of the polymerization may be carried out with radical forming substances, e.g., azo dinitriles, or combinations of compounds yielding oxygen and reducing components. Stabilizers may be used, e.g., a suitable phenol for copolymers of butadienes.  When butadiene polymers are used, vulcanizing agents and accelerators may be added to the emulsion.  The reaction of the epoxy and carboxyl groups may be accelerated by aftertreating with alkaline agents.  The emulsion or solution of the polymer may contain thickening agents such as polyvinylalcohol, salts of polyacrylic acid &c.  The temperature of the coagulating bath is generally 20 DEG -70 DEG C.  Natural or synthetic rubber latices or plastic emulsions, fillers, plasticizers, resins, dyestuffs, pigments, solvents &c., may be added, or other high molecular weight polymers.  The dippings may be repeated to give uniform thick-walled mouldings, e.g., pipes and tubes.  The Specification contains a large number of detailed examples.