DEVELOPER FOR PHOTOSENSITIVE PLANOGRAPHIC PRINTING PLATE

PURPOSE:To solve the problem that a defoaming agent aggregates to an oily form and is uniformize at the time of preparing a developer by incorporating the defoaming agent and chelate agent into a developer for a photosensitive planographic printing plate, thereby dissolving the developer into a solvent consisting essentially of water. CONSTITUTION:This developer for the photosensitive planographic printing plate which contains an alkali silicate and has the form of granular solid is prepd. by incorporating the defoaming agent and the chelate agent into the developer for the photosensitive planographic printing plate. In such a case, the defoaming agent to be used includes the defoaming agents having a defoaming effect, i.e., a foam suppressing effect and/or foam breaking effect and more specifically, mineral oils, vegetable oils, alcohols, surfactants, silicone, etc., are exemplified. The chelating agent is preferably capable of sealing calcium ions and magnesium ions in an alkaline soln. The chelate agent which has a sealing rate thereof of 50% at pH10.0 to 13.5 is preferable in terms preventing the formation of precipitate, such as calcium salt, which affects development performance.