JPH0675192B2 - Photosensitive lithographic printing plate processing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for treating a photosensitive lithographic printing plate, and more specifically, a method for treating a photosensitive lithographic printing plate capable of stably maintaining the liquid activity of a developing solution. Regarding

(Prior Art) Generally, when a photosensitive lithographic printing plate (hereinafter, simply referred to as a PS plate) is continuously processed by an automatic developing machine, the developing solution is consumed as the processing progresses, and the development activity is The sensitivity of the PS plate may also decrease due to the decrease. Further, if the development process is continued as it is, it may even cause defective development.

Examples of the cause of the development failure as described above include fatigue of the developing solution due to elution of the photosensitive layer, that is, processing fatigue, and fatigue of the developing solution by absorbing carbon dioxide in the air, that is, fatigue over time. You can

As a method of replenishing the developing solution for recovering such a fatigue phenomenon, for example, as described in JP-A-58-95349, deterioration of the developing solution is detected by a sensor in the middle of the developing zone and the PS plate is exposed to light. A method has been proposed in which the layer elution degree is measured, and the development replenisher is replenished based on the measurement result.

Specifically, it is a method in which the deterioration of the developing solution is measured in the development process of the PS plate, and a certain amount of the developing replenisher is replenished when the deterioration reaches a predetermined level.

The deterioration of the developer in the above method is measured by measuring the elution degree of the photosensitive layer in the non-image area of the PS plate with the AC resistance meter as the electric resistance value, or the surface of the support with a light reflection sensor. It is performed by measuring as reflected light.

However, the support or photosensitive layer of the PS plate differs depending on the product type, and therefore, even if the degree of deterioration of the developing solution is the same, the measured value by the method as described above differs depending on the product type of the PS plate.

For example, when the deterioration of the developing solution is measured by the electric resistance value as the elution degree of the photosensitive layer in the non-image area of the PS plate, the electric resistance value is obviously different depending on the type of the support. Even if the type of the support is the same, it may show different values depending on the surface condition.

For example, when the support is aluminum, the electric resistance value obviously differs depending on the presence or absence of the anodized layer on the surface or the thickness thereof.

Even if the type and thickness of the photosensitive layer are different, the electric resistance value is obviously different due to the difference in the physical properties of the photosensitive layer and the difference in the amount of the photosensitive layer remaining on the support due to the difference in the elution degree.

Furthermore, when measuring the deterioration of the developing solution as the elution degree of the photosensitive layer in the non-image area of the PS plate with a light reflection sensor, the same applies.
The measured values differ depending on the difference in reflectance or reflection density on the surface of the support due to the difference in PS plate type, or the difference in reflectance or reflection density of the photosensitive layer remaining on the support.

Therefore, depending on the method of replenishing the developing replenisher as described above, appropriate replenishment cannot be performed, and the development quality of the PS plate may deteriorate and the quality may vary.

(Problems to be Solved by the Invention) The present invention improves the above-mentioned drawbacks, and when developing PS plates of different varieties, it is possible to constantly maintain the liquid activity of the developer stably. A method for processing a lithographic printing plate is provided.

(Means for Solving the Problems) As a result of intensive studies by the present inventors, the above-mentioned problems are caused by automatically exposing an exposed photosensitive lithographic printing plate using an automatic processor having a developing replenisher replenishing device. A method of processing a photosensitive lithographic printing plate, which comprises carrying, developing and measuring the elution degree of at least a part of the non-image area photosensitive layer of the photosensitive lithographic printing plate, and replenishing a developing replenisher according to the measured elution degree At
A photosensitive lithographic printing plate which detects the type of the above-mentioned photosensitive lithographic printing plate and compares it with a replenishment condition that has been input in advance according to the type of the photosensitive lithographic printing plate, and replenishes a developing replenisher according to the replenishing condition. It can be solved by the processing method of.

However, the prior application (Japanese Patent Application No. 59-5) having a relationship between the present invention and the prior application
No. 0343), the case where the means for detecting the type of the photosensitive lithographic printing plate is by measuring the impedance value is excluded.

The processing method of the photosensitive lithographic printing plate of the present invention will be described in more detail below.

The photosensitive lithographic printing plate (hereinafter simply referred to as PS plate) used in the processing method of the present invention has a photosensitive layer whose solubility is changed by light irradiation, coated on a support.

Examples of the support include paper, plastic-laminated paper, metal plates such as aluminum, zinc, and copper, plastic films such as polyethylene terephthalate, polypropylene, and cellulose triacetate, and metals such as chromium and nickel that are vapor-deposited or laminated. Included are metal plates, paper, plastic films and the like. Among these supports, an aluminum plate is preferably used as the support for the PS plate according to the present invention.

Examples of the aluminum material include pure aluminum and alloys containing aluminum as a main component, for example, aluminum alloys containing silicon, magnesium, iron, copper, zinc, manganese, bismuth, nickel and the like.

As the aluminum material, a plate-shaped (including foil-shaped) aluminum material manufactured by a rolling method or hot dip aluminum plating can be used. An aluminum material manufactured by hot dip aluminum plating is a plate having a thickness of 7 μm or more obtained by plating a metal plate such as a steel plate with a hot aluminum bath.

Further, it is desirable that the surface of the aluminum plate has a grain shape. Examples of the method of forming the grain shape include a mechanical method and an electrolytic etching method. Further, it is desirable that the aluminum plate having the grain shape is subjected to anodizing treatment. Further, it is desirable to further perform a surface treatment such as a sealing treatment and other dipping in an aqueous solution of potassium fluorozirconate.

The PS plate photosensitive composition used in the present invention contains a photosensitive substance as an essential component, and the photosensitive substance is one whose physical and chemical properties are changed by exposure or subsequent development treatment. , For example, a difference in solubility in a developing solution due to exposure, a difference in intermolecular adhesion before and after exposure, a difference in affinity for water and oil due to exposure or subsequent development, A material capable of forming an image portion by an electrophotographic method or the like can be used.

Typical examples thereof include a photosensitive diazo compound, a photosensitive azide compound, a compound having an ethylenically unsaturated double bond, an epoxy compound which undergoes polymerization with an acid catalyst, and a compound having a COC- group which decomposes with an acid. Is mentioned. Examples of the photosensitive diazo compound include an o-naphthoquinonediazide compound as a positive type compound that changes into alkali solubility upon exposure and an aromatic diazonium salt as a negative type compound whose solubility decreases upon exposure.

Additives such as dyes, plasticizers, and components for imparting printout performance can be further added to the photosensitive layer formed as described above of the PS plate to which the method of the present invention is applied. A photosensitive layer having such a composition is coated on a support using a solution of a suitable solvent.

The coating amount of the photosensitive layer provided on the support is 0.1 to 7 g / m ²
And more preferably 0.5 to 3 g / m ² .

The PS plate having the above composition is exposed through a transparent original image by a light source rich in actinic rays such as a carbon arc lamp, a mercury lamp, a metal halide lamp, and a tungsten lamp, and then developed in a development processing step by wet processing.

The developing solution used in the present invention can be variously changed depending on the kind of the photosensitive composition used for the PS plate and the like, but preferably contains at least one of an alkaline agent and an organic solvent.

As the alkaline agent, sodium silicate, potassium silicate, lithium silicate, sodium hydroxide, potassium hydroxide, lithium hydroxide, ammonium hydroxide, sodium triphosphate, dibasic sodium phosphate, potassium triphosphate, Inorganic alkali agents such as potassium dibasic phosphate, tribasic ammonium phosphate, dibasic ammonium phosphate, sodium metasilicate, sodium bicarbonate, sodium carbonate, potassium carbonate, ammonium carbonate, mono-, di-,
Or triethanolamine, mono-, di-, or trimethylamine, mono-, di-, or triethylamine, mono- or diisopropylamine, n-butylamine, mono-, di-, or triisopropanolamine, ethyleneimine, ethylenediyl Examples thereof include organic amine compounds such as min.

Especially when the photosensitive composition provided on the hydrophilic surface of the support contains a negative type diazo compound (hereinafter referred to as a negative type diazo PS plate), the developer is an alkaline aqueous solution containing an organic solvent. It is preferable that the organic solvent has a solubility in water at 20 ° C. of not more than 10% by weight from the viewpoint of the developability of the PS plate, the ink receptivity, and the improvement of water retention. Solubility in water at 20 ℃ is 10% by weight
If a part of the following organic solvent is exemplified, for example, ethyl acetate, propyl acetate, butyl acetate, amyl acetate,
Benzyl acetate, ethyl acetoacetate, ethylene glycol monobutyl acetate, ethyl malonate, butyl lactate,
Carboxylic acid esters such as butyl repurinate, ethyl butyl ketone, methyl isobutyl ketone, ketones such as cyclohexanone, ethylene glycol monobutyl ether, ethylene glycol monobutyl phenyl ether, ethylene glycol monobenzyl ether, ethylene glycol mono-n-hexyl Ether, ethylene glycol monophenyl ether, propylene glycol monophenyl ether, benzyl alcohol, ethoxyethoxyethanol, methylphenylcarbinol,
n-amyl alcohol, methyl amyl alcohol, 4-
Alcohols such as phenyl-1-butanol, β-phenethyl alcohol, 3-phenyl-1-propanol, alkyl-substituted aromatic hydrocarbons such as xylene,
There are halogenated hydrocarbons such as methylene dichloride, ethylene dichloride and monochlorobenzene.
One or more of these organic solvents may be used. Among these organic solvents, ethylene glycol monophenyl ether and benzyl alcohol are particularly effective. The content of these organic solvents in the developer is preferably 1
-20% by weight, and particularly 2-10% by weight, more preferable results are obtained.

The content of the alkaline agent contained in the developer for negative type diazo PS plate is preferably 0.005 to 4% by weight,
It is 0.5 to 2% by weight.

Further, in order to improve the developability, it is preferable to add an anionic surfactant, a water-soluble sulfite, a solubilizing agent, etc. to the developer for the negative type diazo PS plate. Examples of the anionic surfactant include higher alcohol sulfates, aliphatic alcohol phosphates, alkylaryl sulfonates, alkylamide sulfonates, and dibasic fatty acids described in JP-A-57-5045. Examples thereof include ester sulfonates, alkylnaphthalenesulfonates, formaldehyde condensates of alkylnaphthalenesulfonates, and the like. Of these, sodium butyl naphthalene sulfonate and formaldehyde condensation product of sodium butyl naphthalene sulfonate are particularly preferable because they have strong separation and solubility from the hydrophilic surface of the photosensitive composition layer during development. The content of these anionic surfactants in the developer component is preferably 0.5 to 10% by weight, more preferably 1 to 5%.
% By weight. The water-soluble sulfite has an effect of preventing sticking to a hydrophilic surface by a side reaction of the photosensitive composition, preventing residue, and improving developability, and specific examples thereof include alkali or alkaline earth metal of sulfite. , For example, sodium sulfite, potassium sulfite, lithium sulfite, magnesium sulfite and the like. The content of sulfite in the developer composition is preferably 0.05 to 4% by weight, more preferably 0.1 to 1% by weight. Since the solubilizer is for assisting the dissolution of the organic solvent having a solubility in water at 20 ° C. of 10% or less, it is preferable that the organic solvent is a water-soluble organic solvent, and low molecular weight alcohols and ketones are preferable. It is better to use lactams. Specifically, for example, methanol, ethanol, purpanol, butanol, acetone, methyl ethyl ketone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether,
Methoxybutanol, ethoxybutanol, 4-methoxy-4-methylbutanol, N-methylpyrrolidone and the like are preferable. The amount of the solubilizer used is preferably 30% by weight or less in the developer.

When a photosensitive composition containing a positive diazo compound is provided on the hydrophilic surface of the support (hereinafter referred to as positive diazo PS
Write as a version. ), The developer is preferably an alkaline aqueous solution, preferably as an alkali agent, potassium silicate, lithium silicate, sodium silicate, sodium hydroxide, potassium hydroxide, lithium hydroxide, tribasic sodium phosphate, Examples thereof include dibasic sodium phosphate, tribasic potassium phosphate, dibasic potassium phosphate, sodium carbonate, potassium carbonate and the like. Among these, a developer containing an alkali silicate such as potassium silicate, lithium silicate, and sodium silicate is most preferable because of good development gradation, and the composition of the alkali silicate is [SiO ₂ ] / [M]
= 0.5-1.5 (where [SiO ₂ ] and [M] represent the molar concentration of SiO _{2 and} the molar concentration of total alkali metal, respectively), and a developer containing 0.8-8 wt% of SiO ₂ was used. It is preferably used. Of this alkaline silicate composition, a molar ratio of [SiO ₂ ] / [M] = 0.5 to 0.75, and SiO ₂
Is preferably used because the developer is easily neutralized due to its low concentration, and the molar ratio is more than 0.75 to 1.3 and SiO ₂ is 1 to 8% by weight. The developing solution of (1) has a high buffering power and a high processing capacity, and is therefore preferably used.

In addition, in the developer of positive-working diazo PS plate, the method disclosed in JP-A-50-51324
As described in JP-A-55-95946 and JP-A-56-142528, by containing at least one of an anionic surfactant and a double-sided surfactant as described in JP-A-55-95946. By containing the polymer electrolyte, the wettability to the photosensitive composition can be enhanced and the gradation can be further enhanced, and thus it is preferably used. The amount of such a surfactant added is not particularly limited, but 0.003 to 3% by weight
Is preferable, and a concentration of 0.006 to 1% by weight is particularly preferable.
Furthermore, in all alkali metals as the alkali metal of the alkali silicate, it is preferable that the content of potassium is 20 mol% or more, since insoluble matter generation in the developing solution is small, and more preferably 90 mol% or more of potassium is contained. Most preferably, potassium is 100 mol%.

Whether the photosensitive composition is negative or positive, the developer used in the present invention may contain an antifoaming agent. Suitable defoamers include organosilane compounds.

In the present invention, as the automatic developing machine used for processing the PS plate, after the development processing step if necessary in addition to the development processing step, each processing step of the development stop processing step and the desensitization processing step, and It includes those having a development stop treatment step and a subsequent desensitization treatment step, and a treatment step in which the development stop treatment step and the desensitization treatment step are combined.

An example of such a processing step is, for example, Japanese Patent Laid-Open No. 54-800.
It is described in Publication No. 2.

In the method of replenishing the developing replenisher in the processing method of the present invention,
As a sensor used to measure the elution degree of at least a part of the non-image area photosensitive layer of the PS plate, it can be measured optically or electrically as described in JP-A-58-95349, for example. The sensor can be mentioned.

The positions of these sensors may be either in the middle of the developing zone or after passing through the developing zone in the present invention.

If a preferred embodiment when the sensor is provided at a position after passing through the development zone is described, a means for preventing development of that portion from being substantially progressed in the development zone for a certain period is taken with respect to the portion for measuring the elution degree, A method of measuring the elution degree of the part after passing through the development zone, or providing a part of the non-image area photosensitive layer of the PS plate where the protrusion speed or elution degree is different from other non-image area photosensitive layers, and elution of the part A method of measuring the degree after passing through the development zone can be mentioned.

The method of providing the sensor at a position in the middle of the developing zone is preferable to providing the sensor after the development in view of simplification of the apparatus or the necessity of erasing the PS plate after the development.

According to the present invention, when the sensor is provided at a position in the middle of the development zone, the position is from a position advanced about 1/20 of the development zone to a position advanced about 1/2 of the development zone from the insertion portion of the development zone. It is preferable to provide it within the range.

According to the present invention, in the method of replenishing the development replenisher according to the elution degree measured by the above method, one of the features is to detect the type of PS plate to be treated,
Examples of the method for obtaining the PS version type information include a method for artificially obtaining the type information and a method for automatically obtaining the type information by a sensor.

As for the artificial method, for example, the method of operating the selection buttons corresponding to each PS version product, or when the product types can be roughly divided into two, the PS version ends for one group product type. Can be processed by aligning with the right edge of the automatic processor, and for the other type of product, the edge of the PS plate can be aligned with the left edge of the automatic processor.

There is also a method of storing product type information in an intermediate medium such as a magnetic card, setting the above-mentioned intermediate medium during processing of a PS plate, and detecting and determining the product type.

On the other hand, in the automatic method, for example, a method of determining the reflection density or reflectance of the PS plate by using an optical sensor and comparing it with the reflection density or reflectance of each product type stored in advance to identify the product type, etc. Can be given. The above-mentioned automatic method is preferable because it is less troublesome and does not cause an erroneous operation as compared with the artificial method.

In addition to the above, for example, by providing a small notch at a certain position on the PS plate or at a different position for each product type,
There is also a method to detect the position by contact method, or to identify the type by checking the shape, or to optically read the code printed on a part of the PS plate in advance, or the surface of the PS plate by the contact needle method. There is also a method of identifying roughness by detecting roughness or surface irregularities given in advance.

When the sensor for identifying the product type as described above is provided separately from the sensor for measuring the degree of deterioration of the developer, the type and position of each sensor are not particularly limited and may be arbitrary. .

That is, to give an example, a sensor for measuring the degree of deterioration of the developing solution as the impedance of the non-image area photosensitive layer of the PS plate is provided at a position in the middle of the developing zone, and a light reflection type sensor for identifying the product type. Is provided at a position before the development zone.

According to the present invention, one sensor is installed at a position in the middle of the development zone or a position after passing through the development zone to measure the degree of deterioration of the developing solution due to the elution degree of the non-image area photosensitive layer and to identify the type. It is preferable to use one sensor.

More preferably, one sensor is provided at a position in the middle of the developing zone, and this one sensor measures the degree of deterioration of the developing solution and identifies the product type.

When using a sensor that electrically measures as the sensor that measures the deterioration degree of the developer as described above, the distance between one electrode of the sensor and the other electrode is 0.1 mm to 30 c.
m is preferable, and more preferably 0.1 mm to 15 cm. Further, the positional relationship between the two electrodes may be parallel to the PS plate transport direction, perpendicular to the PS plate transport direction, or vertically above and below the PS plate. The distance between the PS plate and the electrode is preferably 10 mm or less, more preferably 5 mm or less. The area of the electrode in the part where the PS plate and the electrode are parallel to each other is 1 cm ^{2 to} 20 cm.
² is preferred, more preferably 2cm ² ~10cm ^2. At this time, at least one of the electrodes needs to be positioned on the side of the PS plate having the photosensitive layer. When the remaining amount of the photosensitive layer is to be regarded as an AC impedance, it is necessary to make it possible for electricity to flow, such as by contact between the PS plate and the electrode, or through a liquid that is an electrolyte between the PS plate electrodes. is there.

Also, one electrode is in contact with the PS plate and the other electrode is PS
It may be separated from the plate through a liquid which is an electrolyte. In any case, it is necessary to make it possible for electricity to flow between the PS plate and the electrode.

In the present invention, in order to replenish the developing replenisher according to the elution degree of the non-image area photosensitive layer, the relationship between the measured value corresponding to the elution degree and the appropriate replenishment amount corresponding to the measured value is previously determined by experiments or the like. It is only necessary to determine the amount of replenishment based on the demand. The appropriate replenishment amount may be determined so that the measured value corresponding to the elution degree maintains the measured value in the new solution.

The relationship between the type identification in the method of the present invention, the measurement of the elution degree of the non-image area photosensitive layer of the PS plate and the replenishment condition of the developing replenisher is, for example, by the type identification sensor when developing the exposed PS plate. Identifies the PS version varieties, and responds to the set value of the elution degree when the preset elution degree set value for the identified variety and the PS version elution degree of the processed variety match Make sure that the specified amount of development replenisher is replenished.

The set value of the elution degree at this time may be one step or multistep. When the set value is one step, a certain amount of the developer replenisher is replenished when the elution degree becomes less than the certain value determined for the corresponding product type. On the other hand, when the set value is multi-step, if the measured value of the elution degree matches any of the preset values of each step set for the corresponding varieties, a predetermined fixed amount corresponding to the number of matched steps. Replenish the developer replenisher.

In the present invention, the series of control information as described above is input in advance for each PS version type, and the control process is performed corresponding to the identified type.

As a replenishment method other than the above, for example, when a product type is identified by a product type identification sensor and the measured value indicating the elution degree shows a constant set value regardless of the product type, a predetermined amount of the developer replenisher solution To replenish. Also at this time, the set value of the elution degree may be one step or multiple steps as in the above method.

That is, a fixed set value is provided regardless of product type in one step or multiple steps, and when the elution degree matches a predetermined set value regardless of product type, a predetermined amount of development replenisher liquid is applied to the set value for each product type. refill.

In the present invention, such control information is input in advance in the replenishing device. This input may be input by the user from the keyboard, or a previously input control plate may be incorporated in the replenishing device. When an intermediate medium such as a magnetic card is used to identify the product type, control information may be input to the intermediate medium and supplementation may be performed based on the control information.

In the present invention, the amount of the developing replenisher to be replenished depends on the activity of the developing replenisher to be replenished, but the replenishment amount per time is preferably 101 or less per 40 l of the mother liquor of the developer charged, and more preferably 40 l It is less than 4l.

Along with the replenishment method according to the present invention, a change in the degree of absorption of carbon dioxide in the air due to a change in the outside air temperature, a change in the shower flow velocity, etc. is detected, and fatigue due to the absorption of carbon dioxide in the air that changes accordingly is detected. Replenish the corresponding amount of replenisher with PS
It is desirable to always keep the developer activity constant regardless of whether the plate is processed or not.

Examples Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1 Positive PS version FPS-A and FPP (Fuji Photo Film Co., Ltd.)
A large number of 1003 mm × 800 mm size specimens were prepared and exposed through a transparent positive image from a distance of 80 cm for 70 seconds using a 2 kW metal hydrate lamp. On the other hand, prepare a developer prepared by diluting SDR-1 (Konishi Roku Photo Industry Co., Ltd.) 6 times with water and a developer replenisher prepared by diluting SDR-1R (Konishi Roku Photo Industry Co., Ltd.) 4 times with water. did.

The exposed PS plate was processed using the developing solution and the developing replenisher using the automatic developing machine shown in FIG. In FIG. 1, 1 is a developing tank, 2 is a conveying roller, 3 is a squeezing roller, 6 is a brush roller, 12 is a light reflection sensor for measuring the amount of the photosensitive layer remaining in the non-image portion of the PS plate, and 13 is a developing device. It is a liquid removal roller. The developer sent from the pump 7 is supplied onto the PS plate from the shower pipes 8, 8 ', 8 "and 8. The light receiving surface is transported to the installation position of the light reflection sensor 12.
It was decided to be at a position of 10 mm on the PS plate, and further to be at a position 1/5 of the entire development zone from the transport roller 2 at the entrance. The developing solution removing roller 13 temporarily removed the developing solution in the middle of the developing zone, and the light reflection sensor 12 could measure the amount of the photosensitive layer remaining in the non-image area of the PS plate.

The signal of the light reflection sensor 12 is converted into an output voltage by the control device 10 'and processed, the PS plate type is identified by the value, and at the same time, the replenishing device 11' is operated in accordance with the value, and a predetermined amount of The replenisher was replenished.

Regarding the relationship between the processed value of the light reflection sensor signal and the identification of the product type, when the processed value is 0.30 or less, it is determined as FPS-A, and when the processed value is greater than 0.30, it is determined as FPD-A. Further, the relationship between the identified product type, the processing value, and the developing replenisher amount was set as shown in Table 1. In Table 1, x indicates a processed value of the signal of the light reflection sensor.

In addition, while the automatic processor is operating, 35 ml of development replenisher is replenished every hour regardless of PS plate processing, and when the automatic processor is stopped, 300 ml of development replenisher is replenished every 15 hours. It was to so.

401 is charged with the developing solution in the developing solution tank 1 ', the speed of the conveying roller 2 is set so that the total developing time is 40 seconds,
Further, the developing solution temperature was set to 25 ° C. and the exposed PS plate was processed. When the first exposed PS plate FPS-A was processed, when the PS plate reached the light reflection sensor, the photosensitive layer in the measurement area was almost eluted, and the processed value of the light reflection sensor signal was It showed 0.21.

Next, when the exposed PS plate FPD-A was processed, when the PS plate reached the sensor, the photosensitive layer in the measurement portion was almost eluted, and the processed value was 0.31. Subsequently, the exposed PS plates FPS-A and FPD-A were processed to process 20 sheets in total. FP
The SA and FPD-A treatments were performed in any order. When the 21st exposed PS plate FPS-A was processed, the processed value was 0.24, and 420 ml of the development replenisher was automatically replenished. Subsequently, when the 22nd exposed PS plate FPD-A was processed, the processed value was 0.31 again. When the 45th sheet of exposed PS plate FPD-A was processed further, the processed value was 0.34, and 420 ml of the developing replenisher was automatically replenished. Then 4
When the 6th exposed PS plate FPS-A is processed, the processed value is again
It showed 0.21.

In this way, the exposed PS plates FPS-A and FPD-A total about
When 1000 sheets were processed, a lithographic printing plate which showed almost the same sensitivity as the one treated with the new solution and had stable halftone dot reproducibility was obtained.

Comparative Example 1 The exposed PS plate was processed using the PS plate, the developing solution, the developing replenisher and the automatic developing machine used in Example 1. However, the relationship between the processed value of the light reflection sensor signal and the amount of replenisher is
Only when the value was 0.34 or more, 420 ml of the developing replenisher was replenished. Except for the relationship between the processed value and the replenishment, all the PS plates FPS-A and F which have been exposed and set in the same manner as in Example 2
When a total of about 1000 PD-A's were processed, the sensitivity varied greatly. In particular, when several tens of exposed PS plates FPS-A were processed continuously, replenishment was not performed at all during that time, and the decrease in sensitivity was extremely remarkable.

Comparative Example 2 The exposed PS plate was treated with the PS plate, the developing solution and the developing replenisher used in Example 1. However, the automatic developing machine shown in FIG. 2 was used.

In FIG. 2, 1 is a developing tank, 2 is a conveying roller, 3 is a squeezing roller, 4 is a skewer roller, 5 is a receiving roller, and 6 is a brush roller. The developer sent from the pump 7 is supplied onto the PS plate from the shower pipes 8, 8 ', 8 "and 8.
9'is an electrode plate made of stainless steel, the size of which is 1 mm thick
It is 1 cm x 2 cm. The installation position is 3 mm for the PS plate being transported.
Above, at a position 5 mm from the left end in the width direction of the PS plate,
The non-image part always passes through the position. The speed of the transport roller 2 was set so that the total developing time was 40 seconds. The developer temperature was set to 25 ° C. The distance between the centers of the electrode plates 9 and 9'is 10 cm. Reference numeral 10 is an AC impedance meter and a control switch connected to the AC impedance meter. A constant current of 10 kHz was passed through the measured object to measure the impedance of the measured object.

The relationship between the impedance value measured by the AC impedance meter 10 and the amount of the replenisher solution was set so that the development replenisher solution of 420 ml was replenished only when the impedance value showed a value of 26Ω or more. In this way, when a total of about 1000 exposed PS plates were processed, the sensitivity greatly varied. Especially when dozens of exposed PS plates FPP are processed continuously,
During that time, replenishment was not performed at all, and the decrease in sensitivity was extremely severe.

(Effect of the invention) In the processing method of measuring the dissolution degree of at least a part of the non-image area photosensitive layer of the photosensitive lithographic printing plate to be developed, and replenishing the developing replenisher according to the dissolution degree, The developing replenisher is replenished according to the replenishing conditions calculated by comparing the replenishing conditions of the printing plate which are input in advance, so that the developing solution can be used even when developing printing plates of different types. The liquid activity of can be always maintained stable. After the treatment, it is possible to obtain a printing plate having good halftone dot performance without sensitivity deterioration.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an example of an automatic developing machine used in the present invention, and FIG. 2 is a schematic configuration diagram showing another embodiment of the same apparatus. 1 ... development tank, 1 '... developer tank, 9,9' ... electrode plate, 10 ... control switch, 10 '... control device, 11,11' ... replenishment device, 12 ... light reflection sensor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-60-194446 (JP, A) JP-A-58-95349 (JP, A) JP-A-58-27144 (JP, A)

Claims (1)

[Claims] 1. An exposed photosensitive lithographic printing plate is automatically conveyed and developed by using an automatic processor having a developing replenisher replenishing device, and at least a part of a non-image area photosensitive layer of the photosensitive lithographic printing plate. In the method for processing a photosensitive lithographic printing plate in which the elution degree of is measured and the developing replenisher is replenished according to the measured elution degree, the type of the photosensitive lithographic printing plate is detected, and the type of the photosensitive lithographic printing plate is detected. A method for processing a photosensitive lithographic printing plate, which comprises comparing the replenishment conditions input in advance according to the above conditions and replenishing the development replenisher according to the replenishment conditions. However, the case where the means for detecting the type of the photosensitive lithographic printing plate is by measuring the impedance value is excluded.