GB1075754A - Improvements in or relating to stiffening materials for footwear - Google Patents

Abstract

Moulded and stiffened articles, particularly footwear and parts of footwear, are made by incorporating in a normally flexible article a stiffening material at the location where moulding and stiffening is required, the stiffening material comprising a woven or nonwoven cloth e.g. of cotton, or sheet of fibrous material carrying a blend of a urea-formaldehyde synthetic resin and a thermoplastic synthetic resin, applying heat to the article at the location where moulding is required to render the thermoplastic component pliable and moulding the article in the desired form and finally curing the article in that form. The cloth or sheet of fibrous material may be impregnated or coated on one or both sides with the blend of synthetic resins, or may be coated on one side with the urea-formaldehyde synthetic resin and on the other side with the thermoplastic synthetic resin. The stiffening material may also carry a suitable catalyst for promoting the curing of the urea-formaldehyde resin. The catalyst may be selected from organic acids, inorganic salts which react acid in solution, and ammonium salts which produce acid by reaction with the formaldehyde present in the resin. An amount of urea may be added to the catalyst in order to retain its action to suit different production rate requirements. The stiffening material may have a coating e.g. applied by brushing, spraying or dipping, on one or both sides, of a suitable adhesive for adhesively bonding the stiffening material to the article, such as the lining or upper material, or both, of footwear. The adhesive may be a thermoplastic adhesive capable of forming a solution or emulsion in water and may be an acrylic base adhesive. The stiffening material may have a coating on one or both sides of a mixture of an adhesive and a catalyst comprising 100 parts by weight of a 50% acrylic adhesive solution and 10 parts by weight of ammonium chloride. A suitable compatible plasticiser e.g. glycerol, dibutyl-phthalate, may be incorporated in the blend of synthetic resins carried by the stiffening material to prevent hardening and/or embrittlement. The thermoplastic synthetic resin may be polyvinyl acetate resin which may have a softening point well above atmospheric temperature but below the temperature at which the stiffening material is to be moulded. The stiffening material may carry a blend of synthetic resin comprising 70 parts by weight of a 70% urea-formaldehyde solution and 30 parts by weight of a 60% polyvinyl acetate emulsion. The stiffening material is inserted between the lining and upper of a part of footwear at the location where stiffening is required.ALSO:Moulded and stiffened articles, particularly footwear and parts of footwear, are made by incorporating in a normally flexible article a stiffening material at the location where moulding and stiffening is required, the stiffening material comprising a woven or nonwoven cloth, e.g. of cotton, or sheet of fibrous material carrying a blend of a urea-formaldehyde synthetic resin and a thermoplastic synthetic resin, applying heat to the article at the location where moulding is required to render the thermoplastic component pliable and moulding the articles in the desired form and finally curing the article in that form. The cloth or sheet of fibrous material may be impregnated or coated on one or both sides with the blend of synthetic resins, or may be coated on one side with the urea-formaldehyde synthetic resin and on the other side with the thermoplastic synthetic resin. The stiffening material may also carry a suitable catalyst for promoting the curing of the urea-formaldehyde resin. The catalyst may be selected from organic acids, inorganic salts which react acid in solution, and ammonium salts which produce acid by reaction with the formaldehyde present in the resin. An amount of urea may be added to the catalyst in order to retain its action to suit different production rate requirements. The stiffening material may have a coating e.g. applied by brushing, spraying or dipping, on one or both sides, of a suitable adhesive for adhesively bonding the stiffening material to the article, such as the lining or upper material, or both, of footwear. The adhesive may be a thermoplastic adhesive capable of forming a solution or emulsion in water and may be an acrylic base adhesive. The stiffening material may have a coating on one or both sides of a mixture of an adhesive and a catalyst comprising 100 parts by weight of a 50% acrylic adhesive solution and 10 parts by weight of ammonium chloride. A suitable compatible plasticiser, e.g. glycerol, dibutylphthalate, may be incorporated in the blend of synthetic resins carried by the stiffening material to prevent hardening and/or embrittlement. The thermoplastic synthetic resin may be polyvinyl acetate resin which may have a softening point well above atmospheric temperature but below the temperature at which the stiffening material is to be moulded. The stiffening material may carry a blend of synthetic resin comprising 70 parts by weight of a 70% urea-formaldehyde solution and 30 parts by weight of a 60% polyvinyl acetate emulsion. The stiffening material is inserted between the lining and upper of a part of footwear at the location where stiffening is required.