GB572245A - Improvements in or relating to the production of moulding powders - Google Patents

Abstract

A moulding composition is obtained by reacting a urea, an aldehyde, and at least 5 per cent (based on the weight of resin produced) of a diamine-dicarboxylic acid salt, in the presence of at least 15 per cent of water based on the weight of the mixture. Some suitable diaminedicarboxylic acid salts are described in Specification 474,999. Others are listed in the Specification. The term "urea" is defined as meaning urea, thiourea or derivatives thereof which will react with aldehydes. Mono-sesqui- or di-methylol ureas may replace the mixture of urea and formaldehyde. The preferred aldehyde is formaldehyde. A list of other suitable aldehydes is given in the Specification. The ratio of formaldehyde to urea is 1.5-1.0 : 1. The reaction temperature may vary from 0 DEG to 100 DEG C., preferably it is between 50 DEG and 100 DEG C. Reaction is usually carried on until gelation is incipient, as shown by the viscosity of the mixture. Fillers may be added to the reaction mixture or incorporated latex or clear unfilled products may be produced. Acidic or basic catalysts, e.g. ammonium sulphate, formic acid, sodium hydroxide, or trisodium phosphate may be used in the reaction. The products of the mixture can be moulded at 60-200 DEG C. and 500-20,000 lbs./ sq. in. pressure. Moulding catalysts, e.g. b -brom-hydrocinnamic acid, ammonium sulphate, ammonium chloride, benzoic acid or dibromstyrene may be added. Opacifiers, fillers, pigments, lubricants, or other resins such as phenol-formaldehyde, nylon or cellulose acetate may be incorporated either with the resin syrup before drying or with the dry resin powder. Unfilled articles are clear and water-white. The products have good shock-resistance. Examples describe: (1) and (7) the reaction of urea, formaldehyde and hexamethylene diammonium adipate under reflux until gelation occurs, and drying and powdering of the gel. Articles moulded from the gel are clear, water-white and tough; (2) as in (1) a -cellulose being added as a filler to the partially reacted mixture; (3) as in (1) with hexamethylene diammonium sebacate as the salt; (4) as in (1) with decamethylene diammonium adipate as the salt; (5) as in (1) with ethylenediammonium adipate as the salt; (6) as in (1) with ethylene diammonium sebacate as the salt. The powders are especially useful for forming unfilled, clear or translucent articles or opaque articles with fillers, such as asbestos, cellulose or lignin. A list of articles for which the powders may be used is given. Specification 562,091 also is referred to.