Patent GB-238904-A (GB)
Title: Improved manufacture of condensation products of urea or its derivatives and formaldehyde
IPC: C08G12/12
Filed: 1925-08-24
Abstract: In the manufacture of condensation products of urea or its derivatives or substances yielding urea with formaldehyde, the water contained in the product is wholly or partly replaced by the addition of organic substances either to the starting materials or during the process of condensation, the organic substances employed being such as are capable of forming transparent solutions of or in the condensation product and have a higher boiling point than water. Benzyl alcohol is specifically mentioned as a suitable organic substance.  Preferably the bulk of the water is first removed in known manner, then an organic liquid which is volatile with steam is added to the aqueous solution of the initial condensation product and the mixture distilled, in order to expel wholly or in part the water present; such organic liquid may comprise an alcohol, hydrocarbon, ester, aldehyde or ketone.  Before or during the distillation, the organic substance is added which is to enter into the structure of the final product.  If a high-boiling liquid is employed for this purpose, it is advisable to use only a small quantity and to make up the remaining liquid necessary to keep the mass fluid with a liquid of lower boiling point.  The invention is applicable also to mixtures of urea-formaldehyde condensation products with other plastic substances or with plastifying agents, e.g. camphor and borneol.  The products can be used for the manufacture of glass substitutes, lacquers, films, plates, rods, tubes, buttons, combs, &c.  According to the examples, (1) a hydrophobe urea-formaldehyde condensation product is dissolved in ethyl alcohol and amyl acetate then added; after concentration, benzyl alcohol is admixed and the further concentrated mass then hardened to a glassy product; (2) a solution of acetyl cellulose in benzyl alcohol is mixed with a solution of a hydrophile urea-formaldehyde product in excess of methyl alcohol; (3) ethyl alcohol is mixed with a hydrophobe urea-formaldehyde condensation product, the mixture evaporated, naphthalene dissolved in benzyl alcohol then added, and the concentrated product hardened in moulds to a glassy mass.  The Specification as open to inspection under Sect. 91 (3) (a) describes (1) the use of glacial acetic acid, glycerin, concentrated formic acid and sugar as suitable organic substances for the replacement of the water, (2) the application of the invention to condensation products of aldehydes in general with urea, &c., (3) the addition of cellulose, cellulose derivatives and products of decomposition or transformation of cellulose, as well as colouring matters and filling bodies of all kinds as additive materials.  The following examples are also included: (1) benzyl alcohol and amyl acetate are mixed with a hydrophile condensation product of urea and formaldehyde, and the concentrated mass hardened in moulds to a glass-like product; (2) glacial acetic acid, collodion, amyl acetate, acetic ether and toluol are added to a urea-formaldehyde hydrosol to produce a lacquer or a solution which can be concentrated and hardened in moulds; (3) a dough formed by mixing a hydrophile urea-formaldehyde condensation product with benzyl alcohol and camphor is used for making transparent objects; (4) glycerin is mixed with a hydrophile urea-formaldehyde condensation product; the mass sets when ammonium phosphate is added; (5) an aqueous solution of acetanilide is added to a syrupy hydrophile urea-formaldehyde condensation product, then distilled, poured into moulds and hardened; (6) a solution of benzanilide in benzyl alcohol is added to a hydrophobe condensation product, and after distillation, is hardened in moulds to a glassy mass.  This subject-matter does not appear in the Specification as accepted.