| 摘要 |
PURPOSE:To obtain a vanishing soln. increasing the rate of vanishment of the unnecessary image area of a planographic printing plate and suppressing fringy stain caused at the non-image area around the vanished part owing to the sticking of the vanishing soln. and printing stain caused at the vanished part. CONSTITUTION:This vanishing soln. contains modified polyvinyl alcohol obtd. by substituting groups such as carboxyl, sulfo and phosphono or their alkali metallic salts, a silanol group or its deriv., a residue of a quat. ammonium salt, etc., for hydroxyl groups of polyvinyl alcohol, the hydrogen atoms of the groups or hydrogen atoms bonding to carbon atoms. This vanishing soln. further contains a solvent for dissolving or swelling an image area, e.g. gamma-butyrolactone or xylene. |
