GB811634A - Coated metals - Google Patents

Abstract

<PICT:0811634/III/1> Copper sheet is superficially oxidized and then coated with a thermosetting adhesive comprising a mixture of an acetal resin and an aldehyde resin. The preferred acetal resins are the polyvinyl acetals, propionals, butyrals, pentals and hexals, and the preferred aldehyde resins are condensation products that are alkali-catalyzed and initially alcohol-soluble and heat-hardening, particularly phenol, resorcinol, cresol and xylenol aldehydes, preferably formaldehyde or acetaldehyde and homologues. Mixtures given by way of example consist, by weight, of (a) 10-90 parts polyvinyl butyral, 90-10 parts phenol formaldehyde, 0.02 parts malachite green crystals, and (b) 25 parts polyvinyl butyral, 25 parts polyvinyl acetal, 50 parts phenol formaldehyde. The mixtures may be applied from solvent solutions composed of ethyl alcohol or isopropyl alcohol together with toluene, methyl ethyl ketone or n-butyl alcohol. As shown, copper foil 10 is etched by submersion in bath 11 of an alkali such as ammonia, hydrazine or an amine base, cleaned by rotary brush 13, excess alkali removed by squeegee 14, exposed to air and thus oxidized at 16, further cleaned by water 141, excess water removed by squeegees 15, last traces of water removed by heater 151 and suction device 20, coated at 18 with adhesive 17, and finally the adhesive solvent evaporated off in oven 19.ALSO:A thermosetting adhesive coating comprising a mixture of an acetal resin and an aldehyde resin is applied to superficially oxidised copper sheet. The preferred acetal resins are the polyvinyl acetals, propionals, butyrals, pentals and hexals, and the preferred aldehyde resins are condensation products that are alkali-catalysed and initially alcohol-soluble and heat-hardening, particularly phenol, resorcinol, cresol and xylenol aldehydes, preferably formaldehyde or acetaldehyde and homologues. Mixtures given by way of example consist, by weight, of (a) 10-90 parts polyvinyl butyral, 90-10 parts phenol formaldehyde, 0.02 parts malachite green crystals, and (b) 25 parts polyvinyl butyral, 25 parts polyvinyl acetal, 50 parts phenol formaldehyde. The mixtures may be applied from solvent solutions composed of ethyl alcohol or isopropyl alcohol together with toluene, methyl ethyl ketone or n-butyl alcohol.