GB266752A - Improvements in the manufacture and production of condensation products of urea and formaldehyde - Google Patents

Abstract

266,752. I. G. Farbenindustrie Akt.- Ges. Feb. 27, 1926, [Convention date]. Urea-formaldehyde condensation products are prepared by condensing dimethylolurea, or the higher molecular amorphous condensation products resulting therefrom by splitting off water by means of alkaline condensing agents, in alcohols with the aid of acid condensing agents and under mild conditions of working. Crystalline products are thereby obtained which, by treatment under stronger conditions, are transformed into lacquers and glass-like colloidal bodies. Other solvents may be added to the alcohols and pressure may be employed in both treatments. The condensation under stronger conditions may be effected in the fused state, and materials such as plasticizers, natural and artificial resins, and cellulose esters may be present. According to the examples (1) dimethylolurea is boiled for a short time in methyl or ethyl alcohol containing a little hydrochloric acid; after neutralization and filtration, a crystalline product separates out; the condensation may be ejected under pressure in a closed vessel; (2) the product of the preceding example obtained in methyl alcohol solution is dissolved in this solvent and heated in a closed vessel, preferably with the addition of sodium phosphate; a lacquer solution is obtained after neutralization with calcium oxide and filtration. Specifications 261,029 and 262,148 are referred to. The Specification as open to inspection under Sect. 91 (3) (a) states that the process is applicable to methyl compounds obtained from the homologues and derivatives of urea, such as thiourea, N-methylurea and N-methylthiourea, bv alkaline condensation with formaldehyde. It also mentions hydrocarbons, ethers and esters as other solvents that may be present: also alcoholic hydrochloric acid, formic acid, acetic acid, and sulphuric acid monomethyl ester as weaklyacid condensing agents used in the first treatment; and phenols, colophony, casein and yeast as additive materials. The following examples are also included :-(1) dimethylolurea is suspended in a mixture of methyl alcohol and benzene, and heated for a short time with a little formic or acetic acid; sufficient caustic potash is added to neutralize the acid and the solution then filtered and cooled to give a crystalline product; (2) a lacquer is obtained by heating in an autoclave a suspension in isobutyl alcohol of the product of the preceding example; phenol may be added prior to the heating: (3) a suspension of monomethylolurea in methyl alcohol is heated for a short time with sulphuric acid monomethylester, neutralized with caustic potash and filtered; a crystalline product separates out on cooling. This subject-matter does not appear in the Specification as accepted.