GB848678A - Resinous compositions - Google Patents

Abstract

The invention comprises a process for preparing a fluid resinous composition stable in storage by heating together, in the presence of an acid catalyst which is at least as strong as phosphoric acid and which maintains an acid system in solution in a mutual solvent, an organic solvent-soluble etherified urea-formaldehyde or etherified melamine formaldehyde resinous condensation product and an epoxy resin produced from epichlorhydrin and a dihydric phenol, in proportions based on total solids weight of from 30% to 80% of the aminoplast resin and from 70% to 20% of the epoxy resin, at a temperature between 70 DEG C. and the boiling point of the solution under conditions such that there is retained sufficient of the solvent to ensure that the composition is fluid and remains fluid after it has been cooled. Suitable aminoplastic resins are urea-formaldehyde or melamine-formaldehyde resins etherified with, for example, methanol, ethanol, propanol, butanol, isobutanol or higher alcohols, in solution in the etherifying alcohol or partly or wholly replaced by, e.g. xylene or ethyl glycol acetate. Phosphoric acid and p-toluene sulphonic acid (which may be partly neutralised, e.g. with morpholine) and hydrochloric acid are suitable acid catalysts. In an example (1) an epoxy resin from epichlorhydrin and diphenylol propane, a butanol solution of butylated melamine formaldehyde resin and xylol are heated in the presence of phosphoric acid up to 100 DEG C. The fluid product obtained was cured as a film by heating at 180 DEG C. Other examples are given in some of which the epoxy resin has been previously reacted with refined soya bean oil and the aminoplast is selected from butylated melamine-formaldehyde and urea-formaldehyde resins and tri- or hexa(methoxymethyl) melamine. The Provisional Specification includes also an example employing 610 parts of epoxy resin and 107 parts of butylated melamine formaldehyde resin, the solution produced being used to bond a sheet of copper foil to a phenolic laminate.ALSO:A fluid resinous composition, suitable as a stoving lacquer, is prepared by heating together, in the presence of an acid catalyst which is at least as strong as phosphoric acid and which maintains an acid system, in solution in a mutual solvent, an organic solventsoluble etherified urea - formaldehyde or etherified melamine - formaldehyde resinous condensation product and an epoxy resin produced from epichlorhydrin and a dihydric phenol, in proportions based on total solids weight of from 30% to 80% of the aminoplast resin and from 70% to 20% of the epoxy resin at a temperature between 70 DEG C. and the boiling point of the solution under conditions such that there is retained sufficient of the solvent to ensure that the composition is fluid and remains fluid after it has been cooled. Phosphoric acid and p-toluene sulphonic acid (which may be partly neutralized e.g. with morpholine) and hydrochloric acid are suitable catalysts. In an Example (1) an epoxy resin from epichlorhydrin and diphenylolpropane, a butanol solution of butylated melamineformaldehyde resin are heated with xylol and phosphoric acid up to 100 DEG C. The fluid product is flowed on to a tin plate and cured at 180 DEG C. to give a hard film. Other examples are given in which the epoxy resin has previously been reacted with refined soya bean oil and the aminoplast is a butylated melamine-formaldehyde or urea-formaldehyde resin or a tri- or hexa - methoxymethyl melamine.