Patent GB-460275-A (GB)
Title: Improvements in the manufacture and production of urea-formaldehyde resins
IPC: C08G12/42
Filed: 1935-07-23
Abstract: In the production of resinous condensation products by the acid condensation of urea and/or thiourea with formaldehyde, its polymers, the corresponding methylol compounds or alkyl ethers thereof, or the compounds of high molecular weight obtainable therefrom by splitting off water, or mixtures of such substances, carried out with the addition of monohydric alcoholic solvents and with the co-employment of (a) hydroxyl-bearing esters of fatty acids containing at least 10 carbon atoms or mixtures of such esters, or (b) an aliphatic saturated or unsaturated alcohol with more than 8 carbon atoms in the molecule, or (c) a cyclic alcohol containing no phenolic hydroxyl groups; the resinous product, after neutralization and removal of the monhydric alcoholic solvent, is subjected to further heating, with stirring, while adding a non-reacting, non-alcoholic solvent insoluble or difficultly soluble in water until the resinous material becomes soluble therein.  The hydroxyl compound of high molecular weight may be added before, during or after the condensation of the urea with formaldehyde, &c., and before or after removal of the monhydric alcoholic solvent.  Suitable non-alcoholic solvents are benzene, toluene, benzine, mixtures of benzine with esters and/or ethers; esters such as butyl acetate, amyl acetate and ethyl propionate; ethers such as dibutyl ether, ethyl amyl ether, and the dimethyl ether of ethylene glycol; ketones such as cyclohexanone; and mixtures.  The presence of small amounts of substances having an acid reaction, e.g. phthalic anhydride, lactic acid or a sulphonic acid, is advantageous.  The amount of added solvent may be from 5--200 and particularly 15--20 per cent of the amount of resin and hydroxyl compound, the mixture being heated to boiling in a stirring vessel and being azeotropically dehydrated while refluxing the solvent distilled over.  The solvent should preferably be such that the temperature rises to 120--130 DEG  C. during dehydration.  In examples: (1) a resin prepared from dimethylol urea and butanol according to Specification 261,029, [Class 2 (iii)], and freed from solvent according to Specification 332,634, [Class 2 (iii)], is worked up with benzyl alcohol and toluene with a small addition of phthalic anhydride; (2) a similar urea resin is worked up with abietinol together with a glyceryl ester of the fatty acid mixture of linseed oil, and toluene; (3) a similar urea resin is worked up with an alcohol mixture derived from palm kernel oil as described in Specification 356,731 and with a solvent mixture of butyl acetate and benzine; (4) the urea resin of (3) is worked up with a glyceryl ester of (4) a wood oil acid mixture or (5) castor oil acids, and with a solvent mixture of toluene and dibutyl ether; (6) a resin is prepared by dissolving paraformaldehyde in a mixture of butyl and ethyl alcohols with a small addition of caustic soda, neutralizing and adding in turn, urea, urea nitrate and oleyl alcohol obtained from sperm oil according to Specification 396,769, the ethyl alcohol and excess of butyl alcohol being expelled from the clear resin solution by blowing in steam under reduced pressure and the product being worked up with toluene; (7) a resin is prepared from dimethylol urea, the alcohol mixture obtained by catalytic hydrogenation of palm kernel oil acids, urea nitrate, butyl and ethyl alcohols, and, after neutralization, the resin solution is worked up as in (6). Specifications 404,664, 433,536, and 459,788 also are referred to.