JPS6161167A - Processing method of photosensitive planographic printing plate - Google Patents

Abstract

PURPOSE:To always maintain the liquid activity of a developer by measuring a degree of elusion of a part of a non-image part photosensitive layer of a photosensitive planographic printing plate, after passing through a developing zone, and replenishing a development replenishing liquid in accordance with its measured degree of elusion. CONSTITUTION:A processor of a photosensitive planographic printing plate has a control switch 14. This control switch 14 makes a constant-current of 10KHz flow to an object to be measured, measures the impedance of the object to be measured, operates a replenishing device 15 in accordance with the measured impedance value, and replenishes a replenishing liquid of a prescribed quantity. In this way, a degree of elusion of a part of a non-image part photosensitive layer of the photosensitive planographic printing plate is measured after passing through a developing zone, and in accordance with the degree of elusion, a development replenishing liquid is replenished. As a result, the liquid activity of a developer can always be maintained stably.

Description

Detailed Description of the Invention (1) Object of the Invention (Field of Industrial Application) The present invention relates to a method for developing a photosensitive lithographic printing plate using an automatic developing machine having a developer replenisher replenishing device. be.

(Prior art) When processing a photosensitive planographic printing plate using an automatic processor,
Generally, the development activity of the developer decreases with processing, and the sensitivity of the photosensitive lithographic printing plate also decreases accordingly. If the processing is continued further, there is a drawback that development defects eventually occur. The causes of this development failure include fatigue of the developer due to elution of the photosensitive layer, that is, processing fatigue, and fatigue of the developer due to absorption of carbon dioxide gas in the air, that is, fatigue over time.

As a method for separately replenishing processing replenishment and time-based replenishment, a method as disclosed in Japanese Patent Application Laid-Open No. 115039/1983 has been proposed. In this method, the developer replenisher is replenished due to processing fatigue deterioration in accordance with the time the photosensitive planographic printing plate passes through the automatic processor. In this case, a fixed amount is replenished regardless of the width of the photosensitive planographic printing plate or the area of the image area. Furthermore, for replenishment due to fatigue deterioration over time, a fixed amount of replenisher fluid is replenished at a fixed time. The amount of carbon dioxide gas that the developer absorbs from the air is also affected by the surrounding outside temperature and shower flow rate. Therefore, such a method of replenishing a replenisher with a constant loss results in variations in the quality of development of the object to be developed.

In addition, as a method to improve such problems, for example, as shown in Japanese Patent Application Laid-Open No. 58-95349, a sensor placed in the middle of the development zone detects the deterioration of the developer and measures the degree of elution of the photosensitive layer of the photosensitive lithographic printing plate. A replenishment method has been proposed in which the developer replenisher is measured and the developer replenisher is replenished.

However, a specific replenishment method involves measuring the deterioration of the developer during processing of photosensitive planographic printing plates, and replenishing a certain amount of replenisher when the deterioration of the developer drops to a predetermined level. It has become. Therefore, while processing is stopped, no signal is received from the sensor, so replenishment is not performed, and the developer absorbs carbon dioxide gas in the air, causing it to become fatigued.

Therefore, if the machine is stopped for a long time, the first plate after the break will be developed with a considerably exhausted developer. Also, each replenishment only replenishes a certain amount, so if you are extremely fatigued, the developer activity will not recover with one replenishment, and several replenishments will be required before the developer activity recovers. .

Furthermore, since a sensor for measuring the degree of elution of the photosensitive layer is installed in the middle of the development zone, for example, when an optical sensor is used, the developer may splash and adhere to a part of the optical sensor.
Alternatively, the adhering solvent such as water in the developing solution evaporates, and the resin and other solid components in the developing solution dry up, resulting in problems such as poor measurement accuracy. In addition, even in the method of measuring electrically by dipping the electrode of the sensor in a developer solution, if used for a long period of time, solid components in the developer will deposit on the electrode surface, resulting in errors in the measured value. This causes a problem in that the degree of elution of the photosensitive layer cannot be accurately measured. Therefore, in this method of replenishing the development replenisher, the development quality of the object to be developed deteriorates and variations occur.

(Objective of the Invention) An object of the present invention is to provide a method for replenishing a developer replenisher, which improves the above-mentioned drawbacks and makes it possible to constantly maintain the activity of the developer in a stable manner.

(2) Structure of the Invention As a result of intensive research, the present inventors have devised a method for automatically transporting (a large number of) exposed photosensitive lithographic printing plates using an automatic developing machine connected to a developer replenisher replenisher. In the processing method of developing, the degree of elution of at least a portion of the photosensitive layer in the non-image area of the photosensitive lithographic printing plate is measured after passing through the development zone,
It has been found that the object of the present invention can be achieved by replenishing the developer replenisher according to the measured degree of elution.

The present invention will be explained in detail below.

The photosensitive lithographic printing plate to be developed in the method of the present invention has a support coated with a photosensitive layer whose solubility changes upon irradiation with light.

Supports include paper; paper laminated with plastink; metal plates such as aluminum, zinc, and copper; plastic films such as polyethylene tere-7' tallate, polypropylene, and cellulose triacetate; and vapor-deposited metals such as chromium and nickel. Or laminated metal plates, paper,
Includes plastic films, etc. Among the stiff supports, aluminum-5=nium plates are particularly preferred.

Examples of the aluminum material include pure aluminum as well as alloys containing aluminum as a main component, such as 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 metal plate such as a steel plate plated with a hot-dip aluminum bath, and has an aluminum layer having a thickness of 7 μm or more.

Further, it is desirable that the surface of the aluminum plate has a grained shape. Examples of methods for forming the grain shape include mechanical methods and electrolytic etching methods. Furthermore, it is desirable that the aluminum plate with the grained shape be anodized. Further, it is desirable to perform a sealing treatment and other surface treatments such as immersion in an aqueous solution of potassium zirconate.

The photosensitive composition of the photosensitive lithographic printing plate used in the present invention contains a photosensitive substance as an essential component, and the physical and chemical properties of the photosensitive substance change upon exposure or subsequent development treatment. For example, there is a difference in solubility in a developer due to exposure, a difference in intermolecular adhesive strength before and after exposure, and a difference in affinity for water and oil due to exposure or subsequent development processing. It is also possible to use a material that can form an image area using an electronic photographic method.

Typical examples include photosensitive diazo compounds, photosensitive azide compounds, compounds with ethylenically unsaturated double bonds, epoxy compounds that polymerize with acid catalysts, and C-0-C- groups that decompose with acids. Examples include compounds having the following. Examples of photosensitive diazo compounds include O-naphthoquinone diazide compounds as positive types that change to alkali solubility upon exposure, and aromatic diazonium salts as negative types that decrease solubility upon exposure.

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

The coating amount of the photosensitive layer provided on the support is 0°1 to 7.
9/male, more preferably 0.5 to 3 g/m.

The photosensitive lithographic printing plate is exposed through a transparent original to a light source rich in actinic rays, such as a carbon arc lamp, mercury lamp, metal halide lamp, or tungsten lamp, and then developed in a wet processing process.

The developer used in the present invention may vary depending on the type of photosensitive composition used in the photosensitive lithographic printing plate, but preferably contains at least one of an alkaline agent and an organic solvent.

Examples of alkali agents include sodium silicate, potassium silica, lithium silica, sodium hydroxide, potassium hydroxide, lithium hydroxide, ammonium hydroxide, tribasic sodium phosphate, dibasic sodium phosphate, tribasic potassium phosphate, Inorganic alkaline agents such as potassium diphosphate, tertiary ammonium phosphate, ammonium diphosphate, sodium metasilicate, sodium bicarbonate, sodium carbonate, potassium carbonate, ammonium carbonate, etc.
! 14) Liethanolamine, mono-, di-, or trimethylamine, mono-, di-, or triethylamine, mono-1- or di-isopropylamine, n-butylamine, mono-, di-, or triisopropylamine, ethyleneimine, ethylenediamine Examples include organic amine compounds such as amine.

In particular, when the photosensitive composition provided on the hydrophilic surface of the support contains a negative-working diazo compound, it is referred to as a negative-working diazo PS plate of c or more. ), the developer is preferably an alkaline aqueous solution containing an organic solvent, and the organic solvent has a solubility in water at 20°C to i i
% or less is preferable from the viewpoint of improving the developability, ink receptivity, and water retention of the 28 plate. Some examples of organic solvents having a solubility in water at elevated temperature of 10% by weight or less include, for example, ethyl acetate, propyl acetate, butyl acetate, amyl acetate, benzyl acetate, ethyl acetoacetate, ethylene glycol monobutyl acetate, Carboxylic acid esters such as ethyl malonate, butyl lactate, butyl levulinate, ketones such as ethyl butyl ketone, methyl isobutyl ketone, cyclohexanone, ethylene glycol monobutyl ether, ethylene glycol monobutylphenyl ether, ethylene glycol monobenzyl ether, Ethylene glycol mono-n-hexyl ether, ethylene glycol monobutyl ether, propylene glycol monophenyl ether, benzyl alcohol, ethoxyethoxyethanol, methylphenyl carbinol, n-amyl alcohol, methyl amyl alcohol, 4-phenyl-1-butanol, β Examples include alcohols such as -7enethyl alcohol and 3-phenyl-1-propanol, alkyl-substituted aromatic hydrocarbons such as xylene, and unahalogenated 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.

Further, the content of these organic solvents in the developer is preferably 1 to 20% by weight, and particularly preferably 2 to 10% by weight to obtain more preferable results.

Further, the preferable content of the alkaline agent contained in the developer for the negative 97798 plate is 0.005 to 4% by weight, preferably 0.5 to 2% by weight.

Further, it is preferable to contain an anionic surfactant, a water-soluble sulfite, a solubilizer, etc. in the developer of the negative 97728 plate in order to improve the developability. Examples of the anionic surfactant include higher alcohol sulfur esters, aliphatic alcohol phosphate ester salts, alkylaryl sulfonates, alkylamide sulfonate salts, and dibasic salts described in JP-A No. 57-5045. Examples include sulfonic acid salts of fatty acid esters, alkylnaphthalene sulfonates, and formaldehyde condensates of alkylnaphthalene sulfonates. Among these, sodium butylnaphthalene sulfonate and a formaldehyde condensate of sodium butylnaphthalene sulfonate are particularly preferred because of their 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 05 to 10% by weight, more preferably 1 to 5% by weight. Water-soluble sulfites have the effect of preventing the photosensitive composition from sticking or remaining on the hydrophilic surface due to side reactions and improving developability. Preferred examples include sulfite, potassium sulfite, lithium sulfite, and magnesium sulfite.

Sulfite! The preferred content of the powder in the developer composition is 0.05 to 4% by weight, more preferably 0.01 to 1% by weight. Since the solubilizing agent assists in dissolving the aforementioned organic solvent having a solubility in water of 20'C of 10% or less, it is preferably an organic solvent that is more easily soluble in water, such as low-molecular alcohols, ketones, etc. It is better to use lactams and lactams. Specifically, for example, methanol, ethanol, propatool, 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 preferred. The amount of solubilizer used is preferably (9)% by weight or less in the developer.

In addition, when a photosensitive composition containing a positive type diazo compound is provided on the hydrophilic surface of the support (hereinafter referred to as positive type 9772
Marked as 8th edition. ), the developer is preferably an alkaline aqueous solution, and the alkaline agents are preferably potassium silicate, lithium silicate, sodium silicate, sodium hydroxide, potassium hydroxide, lithium hydroxide, tribasic sodium phosphate, Examples include sodium diphosphate, potassium tertiary phosphate, potassium diphosphate, sodium carbonate, potassium carbonate, and the like. Among these, potassium silicate,
A developer containing an alkali silicate such as lithium silicate or sodium silicate is most preferable because it has good development gradation, and the composition of the alkali silicate is C510t in molar ratio.
/ CM:) = o, s ~ 1.5 (here (sto,
), CM) are each 810. (7) Indicates the mol concentration of % mol and total alkali metal. ), and 5tir,
A developer containing 0.8 to 8% by weight of is preferably used. Of this alkali silicate composition, especially in molar ratio [S
A developer solution with 0.5 to 0.75 and sio of 0.8 to 4% is preferably used because it is easy to neutralize developer waste due to its low concentration. while the molar ratio is greater than 0.75 and up to 1.3,
Kak8i0. A developer with a content of 1 to 8% by weight has a high buffering power.
It is preferably used because of its high processing capacity.

In addition, in the developing solution of the positive type 97728 plate,
By containing at least one of an anionic surfactant and a double-faced surfactant as described in Japanese Patent Application Laid-open No. 55-95946,
As described in Japanese Patent Publication No. 56-142528, the inclusion of a polymer electrolyte makes it possible to improve the wettability of the photosensitive composition and to further improve the gradation, and is therefore preferably used.

The amount of such surfactant added is not particularly limited, but 0.0
0.03 to 3% by weight is preferred, especially 0.006 to 1% by weight
A concentration of is preferred. Furthermore, it is preferable that the alkali metal of the silica alkali contains potassium in an additional mol% or more based on the total alkali metals, since the generation of insoluble matters in the developer is small, and more preferably potassium is contained in an amount of 90 mol% or more. , most preferably when the potassium content is 100 mol %.

Regardless of whether the photosensitive composition is negative or positive, the developer used in the present invention can contain an antifoaming agent. Suitable antifoaming agents include organosilane compounds.

In addition to the development process, the automatic developing machine according to the present invention can carry out individual processing steps such as after the development process, a development stop process, and a desensitization process, as well as the development stop process and the subsequent steps. It includes a desensitizing process, and further a process that combines a development stop process and a desensitizing process.

Examples of such processing steps include, for example, JP-A-54-
There is a description in Publication No. 8002.

In the present invention, the degree of elution in the non-image area may be measured visually or by using a sensor.

As a measurement method using a sensor, for example, Japanese Patent Application Laid-open No. 58
Optically, as described in Publication No. -95349,
Alternatively, there is a method of measuring electrically.

As a method for optical measurement, a light transmission type sensor can be used when the support is transparent, and a light reflection type sensor can be used when the support is opaque.

For example, in the case of an aluminum support, a method in which light is applied to the surface of the aluminum support after the photosensitive lithographic printing plate passes through the development zone and before entering the next process, and the reflected light is measured using a light reflection sensor. There is.

In addition, as for electrical measurement methods, if the support is conductive, the change in the amount of remaining film of the photosensitive layer is interpreted as a change in electrical resistance value, that is, the method of measuring impedance in alternating current, and the other method is capacitance. (Series) A method of considering it as a change in the equivalent resistance value, etc.

When measuring electrically, the distance between one electrode and the other electrode of the sensor is preferably 0.1 m to 30 m, more preferably 0.1 m to 15 m. Further, the positional relationship between the two electrodes may be parallel to or perpendicular to the direction of conveyance of the photosensitive planographic printing plate, or in any position above or below the photosensitive planographic printing plate. Further, the distance between the photosensitive lithographic printing plate and the electrode is preferably less than 5 toys, more preferably 5 or less. In addition, the area of the electrode in the part where the photosensitive planographic printing plate and the electrode are arranged in parallel is i, 1-20-
is desirable, and more preferably 2- to [Od. At this time, at least one electrode must be located on the side of the photosensitive lithographic printing plate that has the photosensitive layer. When considering the remaining amount of the photosensitive layer as impedance in alternating current, electricity can flow through contact between the photosensitive planographic printing plate and the electrodes, or through a liquid that is an electrolyte between the photosensitive planographic printing plate electrodes. need to be kept in condition.

Alternatively, one electrode may be in contact with the photosensitive lithographic printing plate, and the other electrode may be separated from the photosensitive lithographic printing plate with an electrolyte liquid interposed therebetween. In any case, it is necessary to maintain a state in which electricity can flow between the photosensitive planographic printing plate and the electrode.

In the present invention, the measurement position or timing of the elution degree is arbitrary as long as it is after passing through the development zone.

In the present invention, in order to replenish the developer replenisher according to the degree of elution of the photosensitive layer in the non-image area, the relationship between the measured value corresponding to the degree of elution and the appropriate replenishment amount corresponding to the measured value is determined by experiment in advance. etc., and then determine the replenishment amount based on it. The above-mentioned appropriate replenishment amount may be determined so that the measured value corresponding to the degree of elution maintains the measured value of the new solution.

When measuring a measured value corresponding to the degree of elution using a sensor, it is preferable that the sensor automatically measures the value and automatically replenishes an amount of replenisher corresponding to this measured value. In such a case, the following embodiment is preferred. That is, the measured value is changed from an analog signal to a digital signal, and the amount of replenisher corresponding to each digital signal is determined in advance. Therefore, a predetermined amount corresponding to each digital signal indicating the degree of elution is replenished.

In the present invention, it is preferable that the part for measuring the degree of elution be taken at the positions 1 to 2 (7) of the edge of the photosensitive planographic printing plate, that is, a part that does not interfere with printing, such as a grip part during printing.

As a preferred embodiment of the present invention, a method is adopted in which the development of the portion for which the degree of elution is to be measured is substantially prevented from proceeding for a certain period of time in the development zone. As a means to substantially stop the progress of development for a certain period of time,
Examples include, but are not limited to, blowing high-pressure air onto the surface of the photosensitive layer, or bringing a rubber belt into close contact with the surface of the photosensitive layer. The time to substantially stop the progress of development is preferably 1/4 to 9/1 of the total development time, more preferably 1/4 to 9/1 of the total development time. It is in the range of ~9/1o.

In the present invention, the amount of developer replenisher to be replenished varies depending on the activity of the developer replenisher, but the amount of replenishment at one time is 10/? The following are preferable,
More preferably, the amount of mother liquor used is 40I! The hit is less than 4E.

Further, in the present invention, it is desirable to provide one more same sensor. After passing through the development zone, a part (A) is provided in a part of the non-image area where development does not substantially proceed for a certain period of time, and a second sensor detects the non-image part other than the part (A). The degree of elution of part (A) is measured with a first sensor, and the degree of elution is determined as the difference between the fixed values on both sides.

In this method, differences due to the type of support, presence or absence of an anodized layer, or amount of anodized layer can be ignored, and differences in the degree of shedding of the photosensitive layer depending on the type of photosensitive lithographic printing plate can be ignored. Therefore, only the degree of elution of the photosensitive layer can be measured, regardless of differences in the type of photosensitive lithographic printing plate, type of support, surface treatment of the support, etc.

191 In addition to the replenishment method of the present invention, changes in the degree of absorption of carbon dioxide in the air due to changes in outside air temperature, changes in shower flow rate, etc. are detected, and fatigue due to the absorption of carbon dioxide in the air that changes accordingly. It is desirable to replenish the replenisher in an amount corresponding to the amount of replenisher to keep the developer activity constant regardless of whether the photosensitive lithographic printing plate is processed or not.

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 3 parts by weight of esterified product of naphthoquinone 1,2-diazido-5-sulfonyl chloride and resorcinol-benzaldehyde resin (described in Example 1 of JP-A-56-104.4), cresol novolak Resin, 9M
A photosensitive solution was prepared by dissolving 0.12 parts by weight of Victoria Pure Blue BOH (dye manufactured by Hodogaya Chemical Industry Co., Ltd.) in 100 parts by weight of methyl cellosolve.

A grained aluminum plate with a thickness of 0°3M is anodized in sulfuric acid to a thickness of about 2.5,! ? / m" oxide film was created, thoroughly washed and conditioned, and then dried. The above photosensitive solution was applied on top of the oxide film and dried.
．． A photosensitive lithographic printing plate with a photosensitive layer of 9/m' was obtained. A large number of positive-working photosensitive planographic printing plates obtained in this way were cut to a size of 1003 x 800 gg, and a 2 KW metal halide lamp was passed through the transparent positives from a distance of 80 mm. using 60
Exposure for seconds. On the other hand, 8i
Ratio between 0□ and O ((Si02) /CK20)
) is 1.78, and the molar concentration of K and O is 3.90 mol/
1 developer solution, and the ratio of O to 5io2 (C
5iOz ) / (K20) ) is 0688, K2
A replenisher solution with a molar O concentration of 7.79 mol/l was prepared.

Next, the photosensitive lithographic printing plate was processed using the above-mentioned exposure method using an automatic processor shown in FIG. In FIG. 1, 1 is a developing tank, and 2 is a circulating water washing tank.

3 is a conveyance roller, 4 is a squeezing roller, 5 is a skewer roller, 6 is a receiving roller, and 7 is a brush roller. The developer sent from the pump 8 is supplied onto the photosensitive lithographic printing plate from the shower pipe 10, and the circulating washing water (saline solution) sent from the pump 9 is supplied from the shower vibe 11 onto the photosensitive lithographic printing plate. 12 is a rubber belt, its width is 2crn
By bringing the photosensitive planographic printing plate into close contact with the photosensitive planographic printing plate between two sides in the width direction from the edge of the photosensitive planographic printing plate passing through an automatic developing machine, contact between the photosensitive planographic printing plate and the developer is prevented. is.

The length of the portion where the rubber belt and the photosensitive lithographic printing plate are in contact with each other in the conveying direction was set to L7 so as to be )'5 of the development zone. That is, the image time between two steps in the width direction from one end of the photosensitive planographic printing plate was set to be 115 of the total development time. 13 and 137 are stainless steel electrode plates,
Its size is 1 loaf of thickness IM x 2 (1). The installation position is above the third eyebrow of the photosensitive planographic printing plate being conveyed, and is at a position five positions from the widthwise end of the photosensitive planographic printing plate,
The position was such that the area where the rubber belt and the photosensitive planographic printing plate were in contact always passed through. Further, the speed of the conveyance roller was set so that the total development time was 40 seconds. Further, the developer temperature was set at 5°C. 13 and 13/ke The distance between their centers was set to 10□□□. 14 is an AC impedance meter and a control switch connected to it;
A constant current of OK)lz was passed through the object to be measured, the impedance of the object to be measured was measured, and the replenishing device 15 was operated according to the measured impedance value, so that a predetermined amount of replenisher was refilled.

The relationship between the impedance value and the amount of replenisher was set as shown in Table 1 below. In Table 1, X indicates the measured impedance.

Add 40/? of the developer to the developer tank 1/? Preparation, circulating water washing water tank 2/saline water 151! I prepared it. The electrical conductivity of this saline solution was 6.10 X lO' 7+Ω.

The exposed photosensitive lithographic printing plate was processed under these conditions. When the first exposed photosensitive lithographic printing plate was processed, the photosensitive layer in the measurement area was almost eluted, and the impedance value measured by the AC impedance meter was 18Ω. As the exposed photosensitive planographic printing plates were processed one after another, the impedance value showed nΩ at the 12th plate, and the replenisher of 210° was automatically replenished. When the 13th exposed photosensitive lithographic printing plate was subsequently processed, the impedance value again showed 18Ω. In this way, 1.00 exposed photosensitive planographic printing plates were processed, then rested for one day, and an additional 10,000 sheets were processed. After that, there was a break for 2 days,
Another 100 sheets were processed. When a total of 2,000 exposed photosensitive lithographic printing plates were processed in this way with a maximum of 4 days of rest, the results were as follows:
Although a slight decrease in sensitivity occurred only in the plate grain, a lithographic printing plate was obtained that exhibited almost the same sensitivity as that treated with the new solution in all other areas and had stable halftone dot reproducibility. Further, even after processing 2000 photosensitive planographic printing plates, no dirt was deposited on the sensor, and impedance could be measured accurately.

Comparative Example 1 An exposed photosensitive lithographic printing plate was processed in the same manner as in Example 1 using the same photosensitive lithographic printing plate, developer, and replenisher as used in Example 1, and the automatic developing machine shown in FIG. The automatic developing machine shown in FIG. 2 is constructed by removing the rubber bell (12) from the automatic developing machine shown in FIG. The center of the electrode plates 13 and 13/ was located at position 15 of the entire development zone from the center of the conveyance roller at the entrance. In addition, when the impedance value shows 22Ω or more, the replenishment control is performed using a constant amount of replenishment fluid, that is, 21-0 m
, /; was set to be replenished with replenisher fluid. Except for these points, when the exposed photosensitive lithographic printing plates were processed using the same settings as in Example 1, a solid substance appeared on the electrode plate sensor near the time when about 1000 photosensitive lithographic printing plates had been processed. was precipitated and adhered, causing a large error in the measured impedance value. As a result, accurate replenishment could not be performed, and the sensitivity of the finished lithographic printing plates varied widely. In addition, when the number of sheets processed was small (less than a few hundred sheets), no solid substances were deposited on the electrode plate sensor, and the impedance value could be measured accurately. After resting for 3 or 4 days, the sensitivities of the lithographic printing plates ranging from several editions to additional editions were all lower than the predetermined sensitivity, and some plates had background stains.

Example 2 An exposed photosensitive lithographic printing plate was processed in the same manner as in Example 1 using the same photosensitive lithographic printing plate used in Example 1, a developer, a replenisher, and the automatic developing machine shown in FIG. Reference numeral 16 denotes a light reflection sensor for measuring the amount of the photosensitive layer remaining in the measurement area provided on the photosensitive lithographic printing plate, that is, the area where the rubber belt and the photosensitive lithographic printing plate were in contact; The light-receiving surface was placed at a position 10 mm above the lithographic printing plate.

The signal from the light reflection sensor is converted into an output voltage and processed by the control device 14/, and the replenishing device 15' is operated according to the value. The relationship between the signal processing value at the light reflection sensor and the amount of replenisher was set as shown in Table 2 below. In Table 2, y indicates the processed value of the signal at the light reflection sensor.

Table 2 When the first exposed photosensitive lithographic printing plate was processed, the photosensitive layer in the measurement area was almost eluted, and the processed value of the signal from the light reflection sensor was 3.0. A total of 2000 photosensitive planographic printing plates □ were treated in the same manner as in Example 1, and the same results as in Example 1 were obtained for the finished planographic printing plates. Furthermore, the light reflection sensor did not get dirty at all, and the amount of remaining photosensitive layer could always be accurately measured, allowing for accurate replenishment.

Comparative Example 2 An exposed photosensitive lithographic printing plate was processed in the same manner as in Example 2 using the same photosensitive lithographic printing plate, developer, and replenisher as used in Example 2, and the automatic developing machine shown in FIG. Reference numeral 17 denotes a developer removal roller which temporarily removes the developer in the speed of the development zone so that the amount of photosensitive layer remaining in the non-image area of the photosensitive lithographic printing plate can be measured by the light reflection sensor 16. . The installation position of the light reflection sensor 16 is determined so that its light-receiving surface is at the position IQ El on the photosensitive planographic printing plate being conveyed, and at the position V5 of all development zones from the conveyance roller at the entrance. Ta. Further, the replenishment control was set so that a fixed amount of replenisher, that is, 210 mA of replenisher, was refilled when the processed value of the signal from the light reflection sensor was 3.4 or higher. All other points are the same as in Example 2.
When the exposed photosensitive planographic printing plate was processed in the same manner as above, the same results as in Comparative Example 2 were obtained for the finished planographic printing plate.

Furthermore, the light reflection sensor was dirty and the lens surface was also slightly damaged, making it impossible to accurately measure the amount of photosensitive layer remaining on the photosensitive planographic printing plate.

(3) Effects of the invention According to the present invention, compared to conventional methods, when developing a large number of photosensitive planographic printing plates using an automatic developing machine connected to a developer replenisher replenisher, the developer The maintenance quality of solution activity is improved, and stable development processing is possible. .

[Brief explanation of drawings]

1 and 3 show an example of an automatic developing machine for carrying out the present invention, and FIGS. 2 and 4 are schematic sectional views of conventional automatic developing machines used as comparative examples, respectively. 1: Developer tank II: Developer tank 2: Circulating water washing tank 2I: Circulating washing water tank 3: Conveyance roller
4: Squeezing roller 5: Skewer roller 6: Receiving roller 7: Brush roller 89: Pump to, 11: Shower pipe 12: Rubber belt 13, 13': [Pole plate 14: AC impedance meter and control switch 141
:Control device 15, 15' :Replenishment device 16:
Light reflection sensor agent Patent attorney No. 1) Interests

Claims (1)

[Claims] In a processing method in which an exposed photosensitive lithographic printing plate is automatically conveyed and developed using an automatic developing machine to which a developer replenisher replenisher is connected, at least the photosensitive layer of the non-image area of the photosensitive lithographic printing plate is A method for processing a photosensitive lithographic printing plate, characterized in that the degree of elution of a portion of the plate is measured after passing through a development zone, and a developer replenisher is replenished according to the measured degree of elution to keep the solution activity of the developer constant.