| 摘要 |
A metal ligature, e.g. a steel strap, having a thin flexible protective coating, is produced by applying to the ligature a thin film of a solution in an organic solvent of oily butadiene polymer having a low molecular weight and containing dispersed therein a proportion of flake aluminium in a sufficiently finely divided condition to permit it to pass through a 400 mesh screen, and heat curing the applied film, e.g. at a temperature in excess of 600 DEG F. The solution may contain between 0,5 and 4 lbs., e.g. between 1 and 2 lbs., of the flake aluminium per gallon. The polymer may contain at least 75% by weight of copolymerized butadiene-1,3, having an average molecular weight, determined by boiling point elevation in ethylene dichloride, of between 1000 and 30,000, e.g. between 5000 and 15,000, any balance of the polymer being constituted by copolymerized mono-ethylenically unsaturated monomer, e.g. vinyl toluene, styrene, or up to 2% of ethylenic monomers containing a carboxyl group and especially dicarboxylic acid anhydrides such as maleic or citraconic anhydride. The polymer may be partially oxidized to an acid number in the range 5-25. The polymer may be a copolymer of butadiene and styrene, and may contain approximately 10% by weight of copolymerized styrene. The proportion of dispersed flake aluminium may be from 0,13 to 1,0 pounds per pound of the polymer, e.g. 0,26-0,52 pounds per pound of heat-cured butadiene-styrene. The butadiene copolymer may be employed alone or in combination with other synthetic resins, e.g. solvent-soluble heat-hardenable urea-formaldehyde resin. The coating composition may be applied as a solution in an organic solvent, and the thickness of the film may be from 0,1 to 0,5 mils, e.g. from 0,2 to 0,4 mils. The coated strap may be printed or waxed. |
