Developing method for positive type photosensitive lithographic plate

Abstract

Abstract PURPOSE:To obtain constant developing results at all times by imagewise exposing a printing plate having a photosensitive layer made of o-quinone diazide compound and developing the plate while supplying a potassium-contg. alkali metal silicate soln. to compensate deterioration of a developer due to the passage of time. CONSTITUTION:When a positive type photosensitive lithographic plate having a photosensitive layer made of o-quinone diazide compound is imagewise exposed and developed with an aqueous alkali metal silicate soln. as a developer, an aqueous alkali metal silicate soln. having alkali activity higher than that of the developer (a) is supplied as a primary replenisher, and a secondary replenisher having higher alkali activity is added continuously at a fixed rate or intermittently every fixed time. At this time, potassium is added to all of the developer, the primary and secondary replenishers in an amount of at least 20% gram atom on the basis of gram atom of the total existing alkali metals.

Inventors

• 👤 Hiroshi Takahashi
• 👤 Masaru Watanabe
• 👤 Haruo Ito

Bibliographic Details