Patent GB-386146-A (GB)
Title: Manufacture of urea-formaldehyde condensation products and artificial materials therefrom
IPC: C08G12/12
Filed: 1932-02-23
Abstract: Urea is condensed with formaldehyde at ordinary temperature in an aqueous solution in the presence of a metallic oxide or carbonate of the kind referred to in Specification 340,114, giving products which are polymerized only to a low degree.  The oxide or carbonate adjusts the pH value of the reaction solution to a constant value which, in the case of zinc oxide or carbonate, is about 6.  The product obtained by allowing the solution to stand comprises a greasy crystalline mass, which may be dried and subdivided to give a moulding powder capable of forming translucent or transparent materials when subjected to heat and pressure preferably in the presence of an acid condensing agent. When fillers are employed they may be added to the reaction solution or may be impregnated with the melt obtained by heating the crystalline mass on the water bath, the products in each case being dried at a low temperature and ground. The crystalline mass may also be further heated to give a more highly polymerized but still reactive product which may be used, alone or with fillers, in the preparation of varnishes and moulding powders. Fillers mentioned are cellulose, hydrocellulose, powdered horn, casein, asbestos fibre or powder, and coloured mineral filling agents. The acidic condensing agents may comprise an acid, an acid salt, or a salt or ester-salt capable of liberating acid, e.g. benzoic acid and ammonium acetate.  Examples are given of the preparation of condensation products in the presence of zinc and lead carbonates and of their use in the manufacture of moulding powders and varnishes; in one case a plasticizing agent such as ethyl alcohol, benzyl alcohol or triacetin is employed.  Specification 373,577 is referred to.ALSO:The condensation product of urea with aqueous formaldehyde at ordinary temperature in the presence of a metallic oxide or carbonate of the kind referred to in Specification 340,114, [Group IV], is employed in conjunction with fillers for the manufacture of moulding powders capable of forming shaped materials when subjected to heat and pressure, preferably in the presence of an acidic condensing agent.  Fillers specified are cellulose, hydrocellulose, powdered horn, casein, asbestos fibre or powder, and coloured minerals.  The aforementioned condensation product forms on standing a greasy crystalline mass and the fillers may be added either to the reaction solution or impregnated with the melt obtained by heating the crystalline mass on the water bath. The crystalline mass may also be further heated to give a more highly polymerized but still reactive product which may be used for impregnating fillers. The acidic condensing agent may comprise an acid, an acid salt, or a salt or ester-salt capable of liberating acid, e.g. benzoic acid and ammonium acetate. Examples are given of the preparation of condensation products in the presence of zinc and lead carbonates and of their use for impregnating cellulose, horn or hydrocellulose. Specification 373,577, [Group IV], is referred to.