GB579556A - Protective covering for metal articles and method of applying - Google Patents

Abstract

Metal articles are protected during shipment, handling or storage, by applying to each article a molten composition comprising ethyl cellulose (45.5 to 50 per cent ethoxyl, 7 to 200 centipoises viscosity), and for every 100 parts of ethyl cellulose, 25 to 150 parts of a solvent plasticiser, 25 to 375 parts of a non-solvent exuding-type plasticiser, and 0 to 50 parts of a thermoplastic resin, the total amount of plasticiser being between 100 and 400 parts for every 100 parts of ethyl cellulose. The amount of composition applied to each article is sufficient to provide a continuous impervious covering over the article. The composition is readily removed from the article by stripping after cutting through the covering, or by cooling and then fracturing the covering by striking it. Stripping is facilitated by inserting during application a string or strip in the covering and pulling at the time of stripping. The covering does not adhere to the metal article and leaves the surface clean when stripped. The composition may be applied to tools, machine parts, gears, or pistons, of iron, steel or other corrodible metal. The viscosity characteristic of the ethyl cellulose is taken as the viscosity of a 5 per cent solution in a solvent mixture consisting of 80 per cent toluene and 20 per cent alcohol at 25 DEG C. The solvent plasticiser may be dibutyl phthalate, methyl abietate, hydrogenated ethyl abietate, tricresyl phosphate, tributyl phosphate, butyl stearate, or methyl phthalyl methyl glycollate, or it may be a wax which is a solvent for the ethyl cellulose such as montan wax, spermaceti, stearic acid, beeswax, Japan wax, hydrogenated castor oil, or candelilla wax. The non-solvent exuding-type plasticiser may be a vegetable oil, a mineral oil, or a wax which is a non-solvent for ethyl cellulose. It may be corn oil, castor oil, acetylated castor oil, coconut oil, cottonseed oil, soya bean oil, linseed oil, or perilla oil, or it may be a light or heavy mineral oil or refined mineral oil. Paraffin wax, petroleum wax, ceresin, and Chinese insect wax, are specified non-solvent waxes. The composition may contain an addition of lanolin. The resin may be an ester of rosin with glycerol, pentaerythritol, or a higher polyhydric alcohol; hydrogenated rosin, polymerized rosin, or heat-treated rosin; an alkyd resin modified by a rosin ester; an oil-modified alkyd resin; a maleic-modified rosin-polyhydric alcohol ester; a rosin-modified phenol-formaldehyde resin, an unmodified phenolic resin, or a coumaroneindene resin. The composition may contain a small amount of a stabilizer for the cellulose ether, e.g. diphenylamine, phenyl beta naphthyl-amine, carbazole, diphenylguanidine, sym.-dibetanaphthyl paraphenylene diamine, hydroquinone benzyl ether, copper naphthenate, cupric chloride, or cupric acetate. Prior to coating with the molten ethyl cellulose composition, the metal article may be lightly coated with oil.