| 摘要 |
A lacquer suitable for electrostatic spraying comprises 40-42% of 1/2 -second nitrocellulose, 5% of dioctyl phthalate, 20% of castor oil, 10% of dammar resin and 23% of a castor oil alkyd resin containing 20 lb. of oil per 100 lb. of resin formed from equimolecular proportions of glycerin and phthalic anhydride. The solids are dissolved to give a 20% solution in a 60/40 mixture of butyl acetate and xylene.ALSO:A method of electrostatically coating an article having an electrically insulating surface including functional groups adapted for chemisorption with electrically charged ions comprises providing the article with a thin electrically continuous conductive gel surface layer containing polar liquid of high dielectric constant, said gel layer comprising an ionizable organic compound capable of ionizing to form an organic ion of one electrical sign capable of chemisorption with said functional groups in said surface, and ions of opposite electrical sign, to thereby reduce the electrical resistivity at the surface of the article, and projecting electrostatically charged coating particles toward the surface or maintaining the surface at a relatively opposite polarity with respect to the electrostatic charge of the coating particles. Examples are given of coating wood, glass and polyester film; fibre-board, hardboard, nylon and polyethylene may also be treated. The ionizable organic compound may be an organic acid, base or salt; the preferred compounds are quaternary and diquaternary ammonium halides. Other suitable compounds are the alkyl and aryl esters of the acids of phosphorus and sulphur. They may be applied in an aqueous alcoholic medium by wiping with a rag, spraying or brushing, and air- or force-dried. The coating particles used in the example were composed ofa nitro cellulose lacquer containing natural resins and alkyd resins. |
