GB413439A - Manufacture of condensation products from urea or thiourea or derivatives thereof - Google Patents

Abstract

Condensation products of urea or thiourea or their derivatives or mixtures and formaldehyde which are soluble in water are prepared by condensing not beyond the hydrophile stage one molecular proportion of urea or thiourea or a derivative of either of them or a mixture of them with at least two molecular proportions of formaldehyde or an agent yielding formaldehyde, and drying, and if desired comminuting, the solution thus obtained in the absence of condensation accelerators. The condensation may occur in the presence or absence of catalysts and the solution may be dried on a roller or a boric drier or by atomizing or in vacuum. The product may be dissolved in water to yield a clear hydrosol. Substances capable of condensation such as urea, thiourea, dicyandiamide, phenol and aromatic acid amides or sulphamides such as benzamide or toluenesulphamide may be added at any stage of the process. The products may be used as adhesives, stiffening agents and varnishes for surfaces such as wood, metal, leather and pottery or for impregnating porous articles such as fabrics, paper or leather, wood pulp, cotton waste, sawdust, powdered leather, corkmeal, asbestos or talc. The impregnated articles may be dried and pressed. Cellulose fibres may be added to the condensation product and after grinding the powder may be dissolved in water to yield a varnish. Moulding powders may be prepared by adding the filling materials at any stage of the condensation, drying and grinding the product. In examples: (1) thiourea is added to a clear condensation solution of urea and formaldehyde and the product dried in a vacuum to yield a product soluble in water. Glazed wall tiles may be prepared by painting a solution of the powder and lithopore in water into a porous tile. (2) A dried condensation product of urea and formaldehyde is mixed with thiourea, dissolved in water and used to impregnate paper, which may be moulded into laminated paper and tubes. (3) A dried condensation product of urea, thiourea and formaldehyde is mixed with thiourea, dissolved in water, kneaded with a - cellulose and the product dried and ground to yield a moulding powder. (4) A condensation product of urea and formaldehyde is mixed with a - cellulose, dried, ground with thiourea and ultramarine and dissolved in water to be used as an impregnating agent for paper. Other filling agents and colouring matters may be used. (5) Urea is added to a condensate of urea and formaldehyde from which some water has been removed and the product is dried, ground and dissolved in water to use as an impregnating agent for a textile web which is then moulded into a laminated product. (6) Urea is condensed with formaldehyde and the product is condensed with thiourea in the presence of formic acid and then dried. Specifications 373,184 and 386,328 are referred to.