GB597726A - A process for the manufacture of a granular amine-aldehyde moulding composition - Google Patents

Abstract

A process for the manufacture of granulated amine-aldehyde resin moulding compositions comprises introducing into a vessel the resin-forming ingredients in an aqueous medium, adding a filler such as wood pulp, a -cellulose, paper, cotton, canvas, asbestos or other natural or synthetic fibres or mixtures thereof, p condensing the resin-forming ingredients in the vessel while stirring, continuing the stirring until the filler is impregnated with the reaction product, and stirring the mass while drying in the vessel and granulating the dried mass in the vessel. The amine-aldehyde resins are acid-curing thermosetting resins such as aminotriazinealdehyde, dicyandiamide aldehyde, melamine-modified dicyandiamide-urea-aldehyde, melamine-urea-formaldehyde, alkylated urea aldehyde and alkylated melamine-aldehyde resins or mixtures of these resins. The aldehyde is preferably formaldehyde or its polymers, but acetaldehyde, propionaldehyde, butyraldehyde, acrolein, methacrolein, crotonaldehyde and mixtures of these or mixtures of these aldehydes with formaldehyde. The temperature of the initial reaction is about 40-50 DEG C. and not exceeding 60 DEG C. The pH is maintained above 5.8, that of the final product being 5.8-7.0, preferably about 6.5, and the drying temperature is kept preferably below 60 DEG C. A latent catalyst, comprising 1-3 per cent of the weight of the resin is preferably formed in situ before or during the condensation by reacting at least a portion of the aldehyde from which the resin is prepared with a salt of an alkaline amino compound to form a complex salt which decomposes at moulding temperatures to yield an acid. The process is carried out in a vessel having a hinged cover and fitted with a pair of rotatable serrated sigma blades. The reaction temperature is regulated by a water jacket and an air intake and exhaust fan circulate air through the reaction mass, which may be dried by passing air or other gases through. In the examples: (1) a urea formaldehyde resin was prepared in the presence of a complex salt formed from ammonium hydroxide and sheeted, bleached paper pulp added as the filler; (2) the procedure of example 1 was followed, except that the final drying was carried out in an apron drier; (3) a melamine-formaldehyde resin moulding composition was prepared and (4) the procedure of example 3 was carried out with the addition of a water soluble colouring matter during the mixing. Apparatus for carrying out the process, is also described (see Group II).