| 摘要 |
<p>Coating compositions comprise (parts by weight) 100 parts of a polyvinyl acetal, 5 to 100 parts of a soluble, heat-hardenable phenolaldehyde resin and 0.05 to 3.0 parts of hexamethylenetetramine dissolved in organic solvents, the polyvinyl acetal having been neutralized after acetalization with ammonium hydroxide or an amine. Specified acetals are derived from formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde or mixtures thereof and may be prepared by simultaneous hydrolysis and acetalization of a polyvinyl ester, e.g. polyvinyl acetate, in the presence of an acid catalyst, e.g. sulphuric acid, followed by neutralization with ethanolamine, triethanolamine, morpholine, benzylamine, dimethylamine, orthotolyl biguanide or ammonium hydroxide. The phenol-aldehyde resins may be derived from phenol, cresols, xylenols, ethyl phenol or p-tertiary butyl phenol and formaldehyde, acetaldehyde, propionaldehyde or butyraldehyde, in the presence of a base, preferably triethanolamine. Specified solvents are cresols, furfural, coal tar naphthas, toluol and xylol. The compositions, which may contain fillers, plasticizers and colouring agents, may be coated on wires, e.g. of copper, nickel, tin, aluminium and cobalt, and cured by heating. Specification 531,273, [Group IV], is referred to.</p> |
