GB780033A - Improvements in or relating to flux compositions adapted for use in aqueous solutionfor the soldering of metals - Google Patents

Abstract

Zinc chloride complex salts of pyrazoline hydrohalides are formed (a) by reaction of zinc chloride with a pyrazoline hydrohalide, itself formed by the reaction of an aldehyde or ketone and a hydrazine hydrohalide or by the reaction of an aldehyde or ketone and hydrazine followed by reaction with a hydrogen halide; or (b) by reaction of zinc chloride, an aldehyde or ketone and a hydrazine hydrohalide; or (c) by reaction of zinc dihydrazine chloride, an aldehyde or ketone and a hydrogen halide. In the preparation of the pyrazoline hydrohalide, a substituted hydrazine or its hydrohalide may be used, e.g. dimethyl hydrazine, phenyl hydrazine or hydroxy ethyl hydrazine: the halide is preferably the chloride but bromides and fluorides may be used; of ketones, acetone, methyl-ethyl ketone, di-acetone alcohol, di-ethyl ketone, methyl isobutyl ketone, methyl vinyl ketone, mesityl oxide and methyl phenyl ketone are specified; of aldehydes, acetaldehyde, propionaldehyde, butyraldehyde, aldol, acrolein and crotonaldehyde. Preferably two or more mols. of a saturated aldehyde or ketone are reacted with one mol. of hydrazine monohydrohalide by admixture at ordinary temperatures or with application of controlled heat; with unsaturated aldehydes or ketones, equimolecular proportions are employed; an inert solvent may be used; the product is recovered by crystallization and filtration. Alternatively, after reaction of aldehyde or ketone with hydrazine in solution or anhydrous, the resulting mixture is reacted with aqueous or gaseous hydrogen halide. The complex salts are used as ingredients of soldering fluxes (Group II). Reference has been directed by the Comptroller to Specification 745,456, [Group II].ALSO:A flux comprises a zinc chloride complex salt of a pyrazoline hydrohalide and a nitrogen salt component comprising a hydrazine hydrohalide or an ammonium halide or both. The nitrogen salt component may amount to 10-50 per cent by weight of the complex salt and may itself comprise 50-90 per cent of ammonium chloride and the balance hydrizine hydrochloride; alternatively bromides may be employed. The pyrazoline hydrohalide may be hydrochloride, hydrobromide or hydrofluoride. The flux is preferably used in aqueous solution for soldering aluminium and its alloys, copper or brass; solutions in methanol, ethanol, isopropanol, ethylene glycol, propylene glycol, butylene glycol or acetone may also be used. The preparation of pyrazoline hydrohalides and their complex salts is described (Group IV(b)). Reference has been directed by the Comptroller to Specification 745,456.