Characters material

摘要

1478474 Receptor sheets comprising crosslinked polyvinylbutyrals OCE-VAN DER GRITEN NV 4 Oct 1974 [4 Oct 1973] 43226/ 74 Heading B2E [Also in Division C3] A receptor sheet comprises a flexible support e.g. polypropylene, polyester, polyamide, polycarbonate and linen provided on at least one side with a drawing layer which contains a crosslinked thermoplastic binder and one or more toothing agents wherein the binder comprises at least 50% by weight of a polyvinylbutyral which has been crosslinked with an etherified polymethylol melamine using an acidic catalyst, the polyvinylbutyral before crosslinking containing at least 18% by weight of vinyl alcohol groups. The toothing agent may be diatomaceous earth, glasspowder, TiO 2 , ZnO, kaolin or silica. In the examples a polyethyleneterephthalate film pretreated with trichloroacetic acid is coated with a mixture of polyvinylbutyral containing vinyl butyral, vinyl alcohol and vinyl acetate groups, hexamethoxymelamine, poly(N, N dimethyl 3, 5 methylenepiperidinium chloride) as antistatic agent; p toluene sulphonic acid or a mixture of cyclohexylsulphamic acid and potassium sulphate, a mixture of two silicas of different surface area and particle size, methylene chloride and 2 methoxymethanol. The drawing layer may be covered with an ink receiving top layer as described in Specification No. 1448889.