GB654351A - Improvements in and relating to synthetic resinous compositions - Google Patents

Abstract

A synthetic resinous coating composition consists of an inter-condensation product of a saturated cyclic ketone of the cyclohexane series or a mixture of such ketones with an aldehyde, a phenol and urea or melamine in butyl or octyl alcohol alone or admixed with alcohols containing 5 to 7 carbon atoms. Phenol and the ketone, e.g. cyclohexanone or methyl cyclohexanone are condensed with hexamethylenetetramine or with formaldehyde and a basic catalyst in presence of butyl or octyl alcohol or a mixture thereof with up to 50 per cent of alcohols with 5-7 carbon atoms. Up to 1 mol. of phenol is used for 2.5 mols. of formaldehyde. The condensation is arrested when the viscosity begins to rise sharply by acidification to pH of 5.5 to 6 with a mixture of 2 parts of salicylic acid and 1 of lactic acid, or with a sulphonic acid such as benzene- or p-toluene sulphonic acid or with oxalic acid. Urea in the proportion of 2-4 mols. per mol. of phenol is dissolved in neutralized formaldehyde and added to acidified condensate and condensation is continued. Water is removed by vacuum distillation, 4-8 per cent being left in the mixture. A mixture of solvents, e.g. ethylene glycol monobutyl ether and benzene is added to form a ternary solvent system with the residual water in the mixture. The pH is finally adjusted to 4.5. Using melamine in place of urea, a smaller molar percentage is employed in relation to the phenol and the final pH is adjusted to 4.2. The compositions are compatible with plasticizing resins of the non-drying alkyd types. They are particularly suitable for application to mouldings or laminates of thermosetting materials.