| 摘要 |
1,228,761. Polyamide coated metal. B.P. CHEMICALS (U.K.) Ltd. 23 April, 1968 [18 May, 1967], No. 23093/67. Heading B2E. [Also in Division C3] Water-resistant polyamides are derived to at least 80 mol % from isophthalic and terephthalic acids, isopherone diamine (5 to 50 mol %) and hexamethylene diamine, at least 50 mol %). They may be prepared by condensing equimolar proportion of the diacid and diamine reactant, desirably in the presence of a trihydrocarbyl phosphite stabiliser, at elevated temperature in the absence of oxygen preferably at a pH of 7 to 7.5. There may be a precondensation step under reflux and the reaction mixture may be agitated continously The reaction may be effected in stages first in a stirred reactor and finally in screw reactor. Other acids, aminoacids and diamines which may provide up to 20 mol % of the polymer are mentioned. Mono-acids or amines may be used to control molecular weight. Reference is made to Specifications Nos. 1,096,908 and 977,868. The polymer may be applied as a powder to metal substrates by fluidised bed dip coating, electrostatic deposition, or flame spraying techniques, the object being heated to the temperature necessary to obtain a coherent film. Reference has been directed by the Comptroller to Specifications 967007 and 1100972. |
