Protection of steel tubes against corrosion - by coating with chromate zinc powder and polymeric layer derived from allylic ether prepolymers

摘要

Steel tubes, partic. drinking water pipes are coated with a protective layer against corrosion involves first depositing and baking on the steel surface a layer of chromate and, simultaneously, over this layer a metallic base layer of fine zinc powder using chromic acid as carrier for a spherulitic zinc dust. This base layer is then cooled. A protective layer of allylic ether conducting prepolymer is then deposited directly on the base layer. The prepolymer is based on allylether-resol of polynuclear aromatic complexes contg. methylol gps. in combination with condensates of bisphenol A-epichlorohydrin without end chain epoxide gp. The prepolymer is pigmented by means of aluminium-bronze pigment flakes (size 10-45 mu), using 1 pts. wt. pigment per 2-4 pts. wt. prepolymer. The prepolymer is converted to polymer by baking. The coating has satisfactory physiological compatibility, and has a service lifetime approx. 10 times greater than conventional coatings.