GB634477A - Improvements in enamel coatings for ferrous metals - Google Patents

Abstract

634,477. Enamelling. POOR & CO. Nov. 24, 1947, No. 31110. Convention date, June 19, 1941. Drawings to Specification. [Class 56] An enamel coating composition for coating ferrous metals consists of a mill formula including an aqueous alcohol vehicle, a bonding compound formula composed of Sb 2 O 3' TiO 2 and nickel chloride, and a blend of a raw glass batch a of relatively high maturing temperature with a eutectic frit b of relatively low maturing temperature. The aqueous alcohol vehicle consists of a mixture of 91.266 parts water, 0.454 part octyl sulphide and 8.280 parts isopropyl alcohol, butyl alcohol or diethylene glycol monobutyl ether, and serves to increase the rate of drying, and by lowering the surface tension to improve the spreading. The bonding compound is made from a colloidal suspension of 60 parts Sb 2 O 3 , 1.5 parts TiO 2 and 60 parts water, ground in a ball mill, dried, and 100 parts of the mixture mixed with 5 parts of nickel chloride. The frit a comprises the following parts by weight, feldspar 26.10, borax 39.20, silica 15.70, soda ash 4.90, sodium nitrate 0.90, fluorspar 8.40, calcium carbonate 3.90, bone ash 0.90, and is mixed and then smelted at 2200‹ F. Frit b contains at least 27 per cent BaO and 10.2 per cent NaF, and may be formed by mixing 34.5 parts barium carbonate, 22.8 parts sodium silico fluoride, 21.0 parts boric acid, 10.8 parts quartz, and 10.6 parts zinc oxide and smelting at 1900‹ F. The mill formula comprises a mixture of 60 parts of frit a, 40 parts frit b, 2.10 parts of bonding compound, 40 parts alcohol vehicle, 7 parts clay, 0.25 parts borax, 6 parts calcium titanium antimonate, and 0.25 part black iron oxide. After grinding in a ball mill the mixture may be sprayed on to the metal which has been cleaned in an alkaline cleaner, rinsed, pickled, rinsed, nickel dipped, rinsed, neutralized and dried. The single coated metal is then dried and fired at about 1350-1400‹ F. to give a rust-proof product. A decorative coating is obtained by forming a clear glass frit and mixing this in a ball mill as follows, 100 parts clear glass frit, 4 parts colour oxide, “ part magnesium carbonate, 5 parts clay, 38 parts water, spraying the product to form a second coating, drying, and firing. Since lower firing temperatures are employed the process can be applied to sheets of lighter gauge than previously.