GB1062663A - Electrostatic image recording medium - Google Patents

Abstract

An electrostatic image-recording medium comprises a sheet of paper having dispersed therein an electrolytic conductor comprising a quaternary ammonium salt in admixture with a deliquescent salt and carrying on one surface a layer of a dielectric material consisting of a synethetic resin. The deliquescent salt may be LiCl, LiBr, ZnCl2, CaCl2 or MgCl2. The quaternary ammonium salt may be a compound having the general formula <FORM:1062663/B1-B2/1> wherein R1 and R2 are C1-7 alkyl groups, R3 is a C8-18 aliphatic hydrocarbon radical, R4 is benzyl, optionally substituted with halogen, alkyl, alkylether and/or hydroxyalkyl ether alkyl groups, and X is Cl or Br; or R1, R2 and R3 are C1-7 alkyl groups, R4 is a C8-21 aliphatic hydrocarbon radical or a radical containing alternating aliphatic and aromatic groups, X being halogen or a nitrate group. Alternatively water-soluble polymeric quaternary ammonium salts may be employed which are obtained by polymerisation of compounds having the above general formula, wherein R1, R2 and R3 are C1-7 alkyl groups or C2-7 alkenyl groups, R4 is a C6-20 aliphatic hydrocarbon radical or a radical containing alternating alkyl or alkenyl and aryl groups, at least one of said R1, R2, R3 and R4 radicals containing a polymerisable -CH=CH- grouping, and X is Cl, Br, nitrate or hydroxyl. Specified quaternary ammonium salts include alkyl dimethyl benzyl ammonium chlorides, para diisobutyl phenoxy ethoxy ethyl dimethyl benzyl ammonium chloride, lauryloxy hydroxypropyl trimethyl ammonium chloride, stearamido propyl dimethyl-b -hydroxy ethyl ammonium nitrate, cety1oxy-hydroxy-propyl trimethyl ammonium chloride, poly (vinyl benzyl trimethyl ammonium chloride), poly (N,N dimethyl-N-benzylamino ethyl acrylate chloride) and poly (N-benzyl ethyl pyridyl ethyl acrylate chloride). The synthetic resin layer may comprise polyvinyl acetate. The layer may be applied to one side of a web of paper from a coating bath or by air knife, coating or doctor blading and thereafter the opposite side may be impregnated by spraying with an aqueous solution of the quaternary ammonium salt-deliquescent salt mixture. Alternatively, the base sheet may be impregnated with the above aqueous solution prior to application of the dielectric coating material.