| 摘要 |
PURPOSE:To obtain a sharp printing image having excellent image density, resolving power and no background staining, by using inorg. pigment, a thermoplastic resin and straight chain saturated fatty acid having a specific number of carbon atoms in a thermal recording layer as main components. CONSTITUTION:A planographic printing base plate is prepared by a method wherein inorg. pigment, a thermoplastic resin and, further, if necessary, a dispersing aid are mixed and dispersed to prepare a dispersion and, for example, 12-19C straight chain saturated fatty acid separately dissolved in a solvent is added to said dispersion to prepare a thermal recording layer coating solution which is, in turn, applied to a water resistant support and dried. As the inorg. pigment, zinc oxide is pref. from the aspect of use sensitivity and, as the thermoplastic resin, ones having a softening point or m.p. of about 150 deg.C or less according to a ring and ball method, for example, polystyrene and the like are designated. As the straight saturated fatty acid, lauric acid, nonadecanoic acid and the like are designated. By this method, a good printing image is obtained without generating sticking on a thermal head at the time of thermal printing.
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