GB482206A - Improvements in or relating to varnished cambric - Google Patents

Abstract

Insulating-material of the varnished cambric type comprises a textile base having a primer coat of a varnish containing a resinous esterified reaction product of an aromatic hydroxycarboxylic acid and an aldehyde, and one or more body coats of a varnish containing an inherently oil-soluble alkyl- or aryl-substituted phenol-aldehyde resin. The outermost coat may contain a wax such as ceresin, carnauba or paraffin wax, or halogenated naphthalene. The fabric is sized and/or calendered before application of the varnish by dipping, spraying or brushing. Each coat of varnish is preferably baked on before the next is applied. Additional coat of a varnish containing an oil-modified alkyd resin may be applied or such a resin may be mixed with one of the other resins. The resin for the primer coat is made by reacting together a polyhydric alcohol such as glycerol, ethylene glycol or pentaerythritol, a natural resin or resin acid such as abietic acid, rosin, copal or sandarac, and a potentially reactive reaction product of an aromatic hydroxy carboxylic acid such as p-hydroxy benzoic acid, cresotinic acid or hydroxy naphthoic acid and a methylene-containing agent such as formaldehyde, hexamethylenetetramine and acetone. This resin is bodied with fatty oils such as linseed, tung, soya bean, perilla or fish oils, by heating, and diluted with a hydrocarbon with addition of a drier such as a mixture of lead, cobalt and manganese naphthenates. The resin for the body coat is made by reacting an aldehyde with p-phenyl-phenol, dicresol, dithymol, cresol, xylenol, or butyl-, amyl-, or benzyl-phenol, and is bodied with oil and thinned as in the case of the primer coat. Blends of the resin varnishes described may be used for the primer and intermediate coats. Specification 471,927 is referred to.