Automatic development method of photosensitive lithographic printing plate and automatic development device thereof

Abstract

A developer replenishing method of an automatic development device of photosensitive lithographic printing plate including developing a plurality of exposed photosensitive lithographic printing plates with a developer containing an electrolyte and keeping the developer activity constant, which includes measuring an electric conductivity of the developer in every predetermined fixed period; providing a predetermined setting value of replenishing amount due to aging in every fixed time; providing a predetermined setting value of replenishing amount due to processing in every processing of a plate having a fixed area; calculating a replenishing amount due to aging based on the replenishing amount setting value due to aging; calculating a replenishing amount due to processing based on the replenishing amount setting value due to processing; calculating an operating value of electric conductivity from the replenishing amount due to aging and the replenishing amount due to processing; and increasing or decreasing the setting value of replenishing amount due to aging and the setting value of replenishing amount due to processing based on a result obtained by comparing the calculated operating value of electric conductivity with the electric conductivity of the developer.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to an automatic development method of, for example, photosensitive lithographic printing plate and an automatic development device thereof In particular, the invention relates to a technology for controlling a fluctuation of the sensitivity of a developer against changes of the development processing condition in the minimum level. [0003] 2. Description of the Related Art [0004] In general, in an automatic development device of photosensitive lithographic printing plate, a replenishing system due to aging and due to processing in which a development replenisher is replenished in a developing tank where a developer is stored, a plate area of a lithographic printing plate to be processed is measured, and the development replenisher is replenished in an amount corresponding to the measured value (this system will be hereinafter referred to as “area-based replenishing system due to aging”) ...

AI Technical Summary

Benefits of technology

[0261] In forming the foregoing heat-sensitive layer, in addition to the foregoing components, various additives can be added as the need arises so far as the effects of the invention are not hindered.

[0262] In the photosensitive lithographic printing plate, for the purpose of enhancing that inhibition (dissolution inhibition), it is possible to contain a variety of inhibitors in the heat-sensitive layer.

[0263] The inhibitor is not particularly limited, and examples thereof include quaternary ammonium salts and polyethylene glycol based compounds.

[0264] The quaternary ammonium salt is not particularly limited, and examples thereof include tetraalkylammonium salts, trialkylarylammonium salts, dialkyldiarylammonium salts, alkyltriarylammonium salts, tetraarylammonium salts, cyclic ammonium salts, and dicyclic ammonium salts.

[0265] Specific examples include tetrabutylammonium bromide, tetrapentylammonium bromide, tetrahexylammonium bromide, tetraoctylammonium bromide, tetralaurylammonium bromide, tetraphenylammonium bromide, tetranaphthylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium iodide, tetrastearylammonium bromide, lauryltrimethylammonium bromide, stearyltrimethylammonium bromide, behenyltrimethylammonium bromide, lauryltriethylammonium bromide, phenyltrimethylammonium bromide, 3-trifluoromethylphenyltrimethylammonium bromide, benzyltrimethylammonium bromide, dibenzyldimethylammonium bromide, distearyldimethylammonium bromide, tristearylmethylammonium bromide, benzyltriethylammonium bromide, hydroxyphenyltrimethlylammonium bromide, and N-methylpyridinium bromide. Of these, quaternary ammonium salts described in Japanese Patent Application Nos. 2001-226297, 2001-370059 and 2001-398047.

[0266] The addition amount of the quaternary ammonium salt is preferably from 1 to 50% by weight, and more preferably from 1 to 30% by weight based on the amount of the whole of solids of the image recording layer from the standpoint of the matter that not only a sufficient dissolution inhibiting effect is revealed, but also the film forming properties of the binder are not adversely affected.

Problems solved by technology

However, in such an area-based replenishing system due to aging, a high-precision plate area measurement device of lithographic printing plate is required in a development processing section of the automatic development device, and therefore, there was a problem of complication of the structure and an increase of the costs.

Also, it is difficult to distinguish whether the photosensitive side of the lithographic printing plate is a single side or double sides (hereinafter referred to as “single side / double sides”) and to distinguish the plate type (such as a plate having a different coating amount of the photosensitive layer).

For these reasons, there was encountered such a problem that if a necessary replenishing amount of the development replenisher changes due to the changes of the plate area, single side / double sides and plate type of the lithographic printing plate, it becomes difficult to adequately achieve the replenishment of the development replenishing amount.

Therefore, there is encountered such a problem that an adequate electric conductivity value of the whole of the developer in a developing tank calculated from the respective adequate electric conductivities changes and a difference from the preset adequate electric conductivity value is generated, whereby it becomes impossible to adequately keep the sensitivity of the developer.

However, according to the foregoing method of controlling the electric conductivity of developer by the electric conductivity value determined from a proportion of the replenishing amount due to processing to the replenishing amount due to aging as calculated from the time interval for replenishment, in the case where the fatigue condition due to aging is different, there is encountered such a problem that a precise proportion of the replenishing amount due to processing to the replenishing amount due to aging cannot be determined.

Thus, there is fear that a wrong target electric conductivity value is calculated.

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