| 摘要 |
<p>A desensitizing gum for lithographic printing plates is disclosed. The gum is comprised of 5 to 35 wt%, based on the total weight of the gum, of a film-forming organic high molecular compound substantially soluble in cold water. The compound is selected from the group consisting of dextrine, soluble starch, water-soluble cellulose ether, water-soluble vinyl polymers, plurune and its derivatives, sterabic, stractan and alginates. The gum further includes 0.02 to 2 wt%, based on the total weight of the gum, of an alkali metal hexametaphosphate or ammonium hexametaphosphate. The desensitizing gum is used in connection with lithographic printing plates and aids in maintaining the ink-repelling properties of the non-image areas of the plate. Furthermore, the gum does not spoil the ink receptive properties of the image areas and possesses good plate-protecting ability while providing good coating surface properties.</p> |
