GB1317622A - Polyamide composition - Google Patents

Abstract

1317622 Coating metal HERMANN WIEDERHOLD and DAIMLER-BENZ AG 27 Feb 1970 [1 March 1969] 39131/71 Heading B2E [Also in Division C3] A composition for use as an adhesion promoter in the filling or coating of metal substrates comprises (i) 70 to 90% (by weight) of polyamide resin (A) (ii) 5 to 15% of polyamide resin B and (iii) 5 to 15% of a pigment which changes colour at 100 to 280‹C. Resins (A) and (B) each have a M.P. of at least 200‹C, a viscosity of 20 to 60 poises at 250‹C and a softening point in the range 30 to 120‹C; resin (A) is derived from (a) a mixture of 20 to 30% of a C 6-12 aliphatic dicarboxylic acid and 80 to 70% of more than 80% dimerised C 12-22 unsaturated fatty acid and (b) ethylene diamine or a mixture thereof with trimethyl hexamethylene diamine; resin (B) is derived from (C) a mixture of 20 to 10% of sebacic acid and 80 to 90% of a 60 to 75% dimerised such fatty acid and (d) ethylene diamine. The pigment may be iron oxide yellow. Coating and filling metal substrates. The composition is stated to be particularly suitable to application to sheet metal in making vehicle bodies especially when it is to be filled or coated with the composition of Specification 1317621 (see Division C3). The composition of Specification 1317621 may be preheated to 190 to 250‹C before being applied to the metal substrate treated with the adhesion promoter. It may then be heated to the melting temperature with a flame or hot air using an electrically heated thermostatically controlled metal spatula. After cooling the applied composition may be ground e.g. using a 180mm grinding wheel having its abrasive surface coated with zinc stearate and rotating at relatively low speeds e.g. 500 to 1500 r.p.m. An initial coarse grinding with grain 40 may be followed with polishing with grain 60 or 80. Reference has been directed by the Comptroller to Specification 1055676.