| 摘要 |
1,145,076. Synthetic resin electrocoating compositions. RANSBURG ELECTRO-COATING CORP. 6 April, 1966 [9 April, 1965], No. 15440/66. Headings C3B, C3P and C3R. [Also in Division C7] Articles are electrocoated under a D.C. potential difference of at least 300 volts per inch of separation between the electrode and the nearest conductive surface of the article in a non-aqueous bath comprising a suspension of (a) an acrylic or curable alkyd or epoxy resin which may be modified, e.g. with isocyanates, organosilanes or organosiloxanes, in (b) an organic liquid of which a major proportion is a solvent and a minor proportion a non- solvent for (a), (c) a pigment of average particle size 0À1 to 10 microns, and optionally up to 3% of (d) a surface active agent, (a) + (c) constituting 5 to 30 wt. per cent of the whole composition; the ratio of (c) : (a) being between 1 : 2À5 and 1: 6; the dielectric constant of (b) differing from those of (a) and (c) by at least a factor of 2; and the dielectric constant of the mixture of (a) and (b) being 2 to 6. The coating may subsequently be heated. Numerous resins, modifying ingredients, solvents, pigments and other materials capable of holding an electric charge, and surface-active agents are mentioned. Example VIII using an oil modified alkyd in xylene and CCl 4 compares a process according to the invention with a conventional process differing only in the concentration and pigment : resin ratio of the bath and the deposition time. In other examples the resins are (I to IV) oil-modified alkyd, (V) epoxy, (VI) epoxy plus styrenated alkyd and (VII) polymethyl methacrylate. The solvents are 98: 2 xylene/butanol with an additional 2% trichlorethylene in Example II.
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