Patent GB-848332-A (GB)
Title: Process for the manufacture of packing materials and for treating casting moulds
IPC: B22C3/00
Filed: 1956-08-22
Abstract: Unsupported films of metal alginate, usable as lining materials in packing, are made by applying to a support a solution containing an alginic acid derivative, a nitrogenous base capable of forming complexes with metal ions, and a metal salt which is soluble in the nitrogenous base and forms an insoluble metal alginate, or a solution containing an insoluble metal alginate maintained in solution by the nitrogenous base, and subsequently removing the nitrogenous base to form an insoluble metal alginate. The nitrogenous base may be ammonia, ethylamine, butylamine, propylamine or triethanolamine, and the metal salt may be a zinc, aluminium, copper, cadmium, nickel, cobalt, chromium or manganese salt.  The soluble alginic acid starting material may be sodium or ammonium alginate or an ether or ester of alginic acid.  The base may be removed from the film on the support by exposure to air or air currents with or without heating, e.g. by infra red rays or by passage through a tunnel or over heated rollers.  The solution may also contain hygroscopic substances such as glycerine, glycol or sorbitol, plasticisers such as starch in any stage of degradation, dextrine, water-soluble cellulose ethers, plant mucilages, tragacanth or protein degradation products, aluminium or other metal powder as a radiant heat reflector, and pigments or soluble dyestuffs.  The film is finally stripped from the support.ALSO:Packing materials of paper, metal or fabric, or casting moulds are rendered moistureimpermeable and non-adherent to soft or sticky materials, by impregnating or coating them with a solution containing an alginic acid derivative, a solvent nitrogenous substance capable of forming complexes with metal ions, and a metal salt which is soluble in the nitrogenous base and forms an insoluble metal alginate, or a solution containing an insoluble metal alginate maintained in solution by the above nitrogenous base, and subsequently removing the nitrogenous base to form an insoluble metal alginate.  The nitrogenous base may be ammonia, ethylamine, butylamine, propylamine or triethanolamine, and the metal salt may be a zinc, aluminium, copper, cadmium, nickel, cobalt, chromium or manganese salt.  The soluble alginic acid product may be sodium or ammonium alginate or ethers or esters of alginic acid.  The base may be removed from the impregnated or coated material by exposure to air or air currents with or without heating e.g. by infra red or in a tunnel or over heated rollers. The treating solution may also contain hygroscopic substances such as glycerine, glycol or sorbitol, plasticisers such as starch in any stage of degradation, dextrins, water soluble cellulose ethers, plant mucilages, tragacanth or protein degradation products, aluminium or other metal powder as a radiant heat reflector, and pigments or soluble dyestuffs which may be used to detect imperfectly treated areas.  Unsupported films of metal alginate, usable for example as lining materials in packing may be made by applying the above solutions to a base and subsequently stripping the film therefrom.ALSO:Packing materials of paper, metal or fabric, or casting moulds, are rendered moisture-impermeable and non-adherent to soft or sticky materials, by impregnating or coating them with a solution containing an alginic acid derivative, a solvent nitrogenous substance capable of forming complexes with metal ions, and a metal salt which is soluble in the nitrogenous base and forms an insoluble metal alginate, or a solution containing an insoluble metal alginate maintained in solution by the above nitrogenuos base, and subsequently removing the nitrogenuos base to form an insoluble metal alginate.  The nitrogenous base may be ammonia, ethylamine, butylamine, propylamine or triethanolamine, and the metal salt may be a zinc, aluminium, copper, cadmium, nickel, cobalt, chromium or manganese salt.  The soluble alginic acid product may be sodium or ammonium alginate or ethers or esters of alginic acid.  The base may be removed from the impregnated or coated material by exposure to air or air currents with or without heating, e.g. by infra red or in a tunnel or over heated rollers. The treating solution may also contain hygroscopic substances such as glycerine, glycol or sorbitol, plasticisers such as starch in any stage of degradation, dextrins, water soluble cellulose ethers, plant mucilages, tragacant or protein degradation products, aluminium or other metal powder as a radiant heat reflector, and pigments or soluble dyestuffs which may be used to detect imperfectly treated areas.  Unsupported films of metal alginate, usable for example as lining materials in packing may be made by applying the above solutions to a base and subsequently stripping the film therefrom.