JPH0784418A - Processing method for electrophotographic planographic printing plate - Google Patents

Abstract

PURPOSE:To provide the processing method for an electrophotographic planographic printing plate which enables processing with a stable grade over a long period of time and lower frequencies in liquid exchange by suppressing the deterioration of a circulating processing liquid. CONSTITUTION:This processing method for the electrophotographic planographic printing plate executes processing in the following manner: Toner images are formed by an electrophotographic system on a planographic printing original plate provided with a photoconductive layer on a conductive substrate. The photoconductive layer of the non-image parts is wetted and solubilized by an eluting liquid and the solubilized photoconductive layer on the plate is removed by a solubilized photoconductive layer removing means. The plate is rinsed at least once each with the circulating processing liquid to be cyclically reused in a rinsing stage in succession to the above removing stage and the unused processing liquid. The unused processing liquid described above contains at least a defoaming agent.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a lithographic printing plate precursor in which a photoconductive layer is provided on a conductive support to form a toner image by an electrophotographic method, and then an eluate is supplied to the non-image area light source. Regarding the processing method of the electrophotographic lithographic printing plate for producing a printing plate by eluting and removing the conductive layer and subsequently rinsing, it is possible to perform stable quality processing for a long period without the occurrence of plate making defects, The present invention relates to a method for treating an electrophotographic lithographic printing plate that prevents and prevents foaming of a circulating treatment liquid that is reused by circulation.

[0002]

2. Description of the Related Art A non-image area alkali-eluting electrophotographic lithographic printing plate generally comprises a photoconductive layer comprising a photoconductive substance and an alkali-soluble binder resin provided on a conductive support.
A toner image is formed on the photoconductive layer by electrophotography, and in the elution step, the non-image area photoconductive layer other than the toner image area is solubilized and eluted by an eluent containing an alkaline agent, etc. After removing the photoconductive layer component solubilized in step 1 and washing, it is usually treated with a protective gum and then subjected to printing.

The elution step utilizes the difference between the alkali solubility of the toner and that of the photoconductive layer, and the photoconductive layer on which the toner image is formed does not essentially become sparingly soluble in alkali. When the elution is pressed, the elution liquid called side etching from the side surface of the photoconductive layer also corrodes the photoconductive layer in the image area, so that the image line is thin and good image reproducibility cannot be obtained. In addition, if the solubilized photoconductive layer component flows into the eluate, the elution ability may be lowered due to the recycling and reuse, which may lead to elution failure. Therefore, in the elution step, the non-image area is solubilized only, and the solubilized product is removed in the next step in consideration of suppressing the inclusion of the solubilized photoconductive layer component in the circulating eluate.

The solubilized photoconductive layer component can be removed from the plate by directly supplying a rinsing solution in the rinsing step, but if the processing solution is circulated and reused, the solubilized product is added to the solubilized photoconductive layer component. Is mixed and accumulated, and eventually the side etch is aggravated by an increase in the pH of the solution, and if the processing solution is used up, a large amount of solution is required, which is not preferable from the economical, disposal and environmental viewpoints. Therefore, a method is adopted in which this solubilized product is removed together with the eluent remaining on the plate before the rinsing step and discarded, and the solubilized material that cannot be completely removed in the rinse treatment step is washed away. .

This method also causes the solubilized photoconductive layer components to be mixed and accumulated during recycling and reuse of the rinse treatment solution. Therefore, if the plate surface is rinsed with an unused treatment solution at the end of the rinse step, for example, circulation reuse is possible. Even if the processing liquid used is contaminated with the solubilized product, the plate surface is always cleaned. Moreover, if the unused treatment liquid used for the rinse is put into the rinse circulation system and the circulation reuse treatment liquid is discarded instead, the progress of the contamination of the circulation liquid and the accompanying deterioration of the side etch are significantly delayed. However, when the photoconductive layer component is mixed in the circulating liquid even in a small amount, the water-solubilized binder resin is generally foamable, and a large amount of the circulating reuse liquid is applied to the plate surface in order to enhance the rinse effect. Since it must be supplied, foaming is induced relatively early in plate making.

Therefore, in order to defoam a conventionally foamed treatment liquid, an antifoaming agent is artificially added while observing the degree of foaming, or the treatment liquid is preliminarily contained. Was taken. This artificial addition method enables efficient defoaming, but despite the fact that the plate making process is almost automated, complete automation of the process is not achieved, and the platemaker pays attention to other than plate quality inspection. I had to. On the other hand, for defoaming, it is most effective to coat the foaming interface with a defoaming agent.Therefore, in the method in which the defoaming agent is contained in the treatment liquid in advance, the defoaming effect is exhibited at the early stage of plate making. However, it was difficult to maintain the effect until the end of the plate-making period, as the effect diminished during cyclic reuse.

[0007]

SUMMARY OF THE INVENTION According to the present invention, after a toner image is formed by an electrophotographic method on a lithographic printing plate precursor having a photoconductive layer on a conductive support, a non-image area other than the toner image area is formed. In a method for treating an electrophotographic lithographic printing plate for producing a printing plate by elution and removal of a photoconductive layer, liquid deterioration caused by mixing of a solubilized photoconductive layer due to liquid circulation reuse is suppressed. An object of the present invention is to provide a processing method capable of performing stable processing over a long period of time and thus reducing the burden of maintenance management. More specifically, it is an object of the present invention to provide a method for treating an electrophotographic lithographic printing plate which improves the foaming of the circulating reuse treatment liquid in the rinse treatment step.

[0008]

As a result of repeated studies to solve the above problems, a toner image is formed by an electrophotographic method on a lithographic printing plate precursor having a photoconductive layer provided on a conductive support, and then a toner image is formed. The eluate is supplied to the image forming surface to swell and solubilize the non-image area photoconductive layer, and the solubilized photoconductive layer removing means removes the eluent on the plate and the solubilized photoconductive layer. In the processing method of an electrophotographic lithographic printing plate, which comprises rinsing with a circulating treatment liquid that is recycled and reused in the treatment process and an unused treatment liquid at least once, by adding at least an antifoaming agent to the unused treatment liquid. Achieved

That is, the present invention provides a method for treating an electrophotographic lithographic printing plate which comprises rinsing after supplying an eluent to the toner image forming surface of the electrophotographic lithographic printing plate to remove the solubilized photoconductive layer. By supplying the unused treatment liquid onto the plate and rinsing, the treatment liquid remaining on the plate is removed by the unused treatment liquid to clean the plate surface, and the replenishment of the circulating treatment liquid and the accompanying treatment It is characterized by delaying liquid deterioration. Furthermore, by containing an antifoaming agent in the unused processing liquid, the antifoaming agent can be supplied to the surface of the circulating reuse processing liquid directly or through the plate surface, and the defoaming can be effectively achieved.

The defoaming agent according to the present invention will be described. The defoaming agent according to the present invention is composed of a reagent having a defoaming effect (foam suppressing effect, foam breaking effect), examples of which include mineral oil, spot oil, alcohol, surfactant, and silicone. To be Mineral oils are mainly paraffinic and naphthenic saturated hydrocarbons obtained from petroleum crude oils or processed products thereof, such as gasoline, kerosene, gas oil, heavy oil, machine oil and the like.

Vegetable oils include drying oils, semi-drying oils, non-drying oils, and vegetable fats. Examples of the drying oil include hemp oil, linseed oil, eno oil, tung oil, walnut oil, poppy seed oil, safflower oil, soybean oil, and sunflower oil. As semi-drying oil, mustard oil, sesame oil, corn oil, rapeseed oil, bran oil,
And cottonseed oil. Examples of the non-drying oil include olive oil, mountain tea flower oil, tea oil, camellia oil, tall oil, husk oil, castor oil, and peanut oil. Examples of vegetable fats include cocoa oil, palm oil, palm kernel oil, wood wax oil, and palm oil. Among these, a particularly preferable vegetable oil is a non-drying oil.

Examples of alcohols include sterin, methylsterin, and acyclic aliphatic alcohols. The sterins include campesterin, cholesterin, β-
Examples thereof include sitosterin, stigmasterin, brassicasterin and the like. Methylsterin includes gramisterin, cycloartanol, cyclobranol, citrostadienol, lanosterine, lophenol, and 2,
4-ethylidene rophenol and the like can be mentioned. As the acyclic aliphatic alcohol, a monovalent or divalent linear aliphatic alcohol having 7 or more carbon atoms is preferable, 1-heptanol, 1-octanol, 2-ethyl-1-hexanol,
2-nonanol, 1-decanol, 2-undecanol,
1-dodecanol, 1-tetradecanol, 1-hexadecanol, 1-octadecanol, oleyl alcohol, hexadecane-1,2-diol, octadecane-1,
Examples thereof include 2-diol, eicosane-1,2-diol, and batyl alcohol. Particularly preferred among these are 1-octanol, 1-decanol, 1-undecanol, and 1-tetradecanol.

The surfactant is preferably nonionic or weakly cationic. Preferred examples thereof include sorbitan higher fatty acid esters such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan tristearate, sorbitan monooleate, sorbitan trioleate, and sorbitan sesquioleate, N, N. -Fatty acid amides such as distearoyl ethylene diamide, polypropylene glycol, polyethylene glycol ether, polyoxyethylene alkyl ether, polyoxyethylene alkyl aryl ether, and polyol ether such as polyoxyethylene polyoxypropylene ether, 3,
6-dimethyl-4-octyne-3,6-diol, 2,4,7,
Examples thereof include 9-tetramethyl-5-decyne-4,7-diol, acetylene alcohols such as oxyethylene adducts thereof and derivatives thereof, and fluorochemical surfactants. Of these, particularly preferable are acetylene alcohol and its derivatives, and fluorochemical surfactants.

Examples of the silicone include long side chain low polymerization degree silicones such as dicetyl silicone, and short side chain high polymerization degree polysiloxanes such as polydialkyl siloxanes, polyalkylaryl siloxanes, and polydialkyl polyalkylaryl siloxanes. Is mentioned. The polysiloxane having a short side chain and a high degree of polymerization is preferably dimethylpolysiloxane, and an alkoxypoly (ethyleneoxy) polysiloxane in which a part of the methyl groups bonded to silicon is substituted with alkylenepolyoxyethylene, or these It is preferable to modify the polysiloxane by partially introducing a carboxyl group or a sulfone group.

The addition amount of the above-mentioned antifoaming agent according to the present invention is preferably 100 to 50,000 ppm, more preferably 500 to 10,000 ppm, based on the unused treatment liquid. If the amount of the defoaming agent added to the unused treatment liquid is small, the defoaming effect cannot be expected, and as a result, it becomes necessary to supply a large amount of the unused treatment liquid. Then the effect is saturated. These may be used alone or in combination. Also, these follicular agents may be added to the unused processing liquid in advance, but immediately before the unused processing liquid is supplied to the printing plate, that is, the unused processing liquid is stored in the unused processing liquid storage source. You may mix and use it, before reaching a liquid supply means. If necessary, these defoaming agents may be dissolved in a suitable solvent and used in a uniform state, or may be added together with various emulsifiers in the form of an emulsion to the unused treatment liquid according to the present invention.

Hereinafter, the unused processing liquid according to the present invention will be described in detail while explaining the processing method of the present invention in the order of processing steps. The treatment step in the treatment method of the present invention comprises at least an eluate supply step, a solubilized photoconductive layer removal step, and a plurality of rinse treatment steps, and in the rinse treatment step, a circulation treatment liquid which is reused by circulation. And rinsing with fresh treatment liquid containing defoamer at least once.

In the eluate supply step, the eluate is supplied to the photoconductive layer surface of the lithographic printing plate on which the toner image has been formed by the electrophotographic method. A known mechanism such as a shower, a slide hopper, a curtain coater, or a dip method can be used as the eluent supply method, but particularly when a shower is used, the liquid discharged from the pipe is supplied to another member, such as a straightening plate or a plate conveyer. A method of uniformly supplying to the photoconductive layer surface via an upper roll or the like is suitable. In all of these methods, in order to further shorten the elution time and prevent liquid supply failure, a flow accelerating mechanism was installed during the liquid metering process to replace the flow of the eluate supplied on the plate. It is desirable to achieve this and to supply the eluate multiple times.

The electrophotographic lithographic printing plate supplied with the eluent is preferably measured and removed by the liquid metering means in the eluent metering step, leaving at least a certain amount of excess eluent on the plate. As a liquid measuring tool in the eluate measuring step, it can be rotated by some kind of drive transmission in the plate conveying direction, and evenly contacts the plate surface in all the rotating directions in the measuring width direction. At the time of measurement, it is important to have a shape that prevents the solubilized photoconductive layer from peeling off. Examples of the liquid measuring tool include a wire bar in which a thin wire having a constant diameter is spirally wound around an axis, a grooved roll, a plain bar, and a lightweight rubber roll. Since the eluate that has flowed down before the eluate measurement step and the measurement-removed solution hardly suffer fatigue from the elution treatment, it can be recycled and used.

The electrophotographic lithographic printing plate in which the non-image area is solubilized by the eluent enters the solubilized photoconductive layer removal step,
The solubilized photoconductive layer removing means removes the solubilized photoconductive layer, and the photoconductive layer is conveyed to the next step. Since most of the liquid substance removed in the solubilized photoconductive layer removing step is the solubilized photoconductive layer and the fatigue eluate, it is desirable to discard and not reuse. In addition, it is desirable to replenish at least the amount of the eluent contained in the waste liquid with a new liquid so as to secure the circulating liquid amount and maintain the elution activity.

The solubilized photoconductive layer removing means arranges an elastic material having a smooth contact surface at least with the plate along the conveyance path of the printing plate, and slides the liquid material on the plate surface to slide the liquid material on the plate surface. It can be removed. The removal pressure of the solubilized photoconductive layer removing means can be adjusted depending on the elasticity (hardness) and the shape of the contact portion. In installing the solubilized photoconductive layer removing means, a backup roll that rotates at a peripheral speed equal to or higher than the conveying speed is provided under the solubilized photoconductive layer removing means, or pressure is applied immediately after the plate leading portion passes through the solubilized photoconductive layer removing means, It is desirable to provide some kind of mechanism for preventing the induction of conveyance failure.

The printing plate from which the removed material such as the photoconductive layer solubilized in the solubilized photoconductive layer removing step has been removed is subjected to a rinsing step provided to remove the removed material on the printing plate.
Rinse the circulating treatment liquid to be recycled and reused and the unused treatment liquid containing at least an antifoaming agent at least once. Since the circulating treatment liquid and the unused treatment liquid containing the defoaming agent need to be supplied at least once each time, the circulating treatment liquid having the same or different composition can be continuously or rinsed with the unused treatment liquid. It may be supplied a plurality of times by sandwiching it, or similarly, an unused treatment liquid having the same or different composition may be supplied a plurality of times by sandwiching a continuous or circulating treatment liquid supply. When the unused treatment liquid is supplied a plurality of times, the antifoaming agent may be included at least once. Further, the treatment liquid containing the defoaming agent rinsed by supplying it onto the plate may be discarded except for the minimum amount at which the substantial defoaming of the circulation treatment liquid is achieved, and the treatment liquid is stored in the circulation treatment liquid storage tank. Even if all are collected, or a tank different from the circulating treatment liquid storage tank is provided below the unused treatment liquid supply unit, the used treatment liquid is temporarily stored to replenish the circulating treatment liquid and clean each part. It may be used for etc.

The unused processing solution and the circulating processing solution according to the present invention are prepared so that the binder resin and the like in the electrophotographic planographic printing plate photoconductive layer to be plate-processed are not reaggregated, and at least The eluate and the solubilized photoconductive layer have the ability to be rapidly diffused and dissolved in the treatment liquid.
Usually, the rinse effect is sufficiently exhibited even in tap water, so the unused treatment liquid according to the present invention may contain at least a defoaming agent in water, but the unused treatment liquid used for rinsing is circulated. If used as a mixture with the treatment liquid, the unused treatment liquid component excluding the defoaming agent may have the same composition as the circulating treatment liquid, or the unused treatment liquid and the circulating treatment liquid may have the same composition. It doesn't matter.

In order to prevent agglomeration of the solubilized product and the deterioration of side etching to more stably rinse the many electrophotographic lithographic printing plates, at least p of the circulating treatment liquid is used.
It is desirable that H does not fluctuate during the plate making period, and specifically, it is important to maintain the liquid pH at 10.5 or less.
Therefore, it is desirable to finally contain a compound having an acid dissociation index (pKa) of at least 7 to 10 (hereinafter, a compound having an acid dissociation index (pka) of at least 7 to 10 will be simply referred to as a compound). .

When the compound has a plurality of dissociation stages, at least one of the acid dissociation indices should be in the range specified in the present invention. Examples of the compound having an acid dissociation index defined in the present invention include “Chemical Handbook. Basic Edition II”, The Chemical Society of Japan, ed., 3rd edition 1984, published by Maruzen Co., Ltd., II-33.
8 to II-342, all can be used.
Among the compounds, amino acids such as aspartic acid, glycine, glutamic acid and salts thereof are particularly preferable. Two or more kinds of these compounds may be mixed and added. Also,
These compounds may be used as a mixture with an appropriate acid or basic compound, or may be used in combination with an appropriate acid or basic compound for pH adjustment or acceleration of dissolution. Particularly when a solution containing these compounds is added later, it is desirable to adjust the pH to 6.0-9.5, more preferably 7.0-8.0 before adding.

The addition of the compound allows sufficient rinsing at the initial stage of plate making, even if the liquid does not contain the compound.
The compound may not be contained in the circulating treatment liquid, and the compound-containing solution may be supplemented to the circulating treatment liquid to finally contain it, or may be added to the circulating and / or unused treatment liquid prior to plate making. good. In the case of post-addition, the pH of the treatment liquid is preferably 8.5 to 10.5, more preferably 9.5 to 10.0 at the start of addition. In addition, especially if the plate size is constant, unless the areas of the non-image areas are significantly different,
Since the rise is related to the number of plates passed, the compound can be added at regular intervals. Even in the case of pre-addition, it can be further added according to the increase in the pH of the processing liquid during the multi-plate printing. When this compound is added prior to plate-making, the compound may be added alone or may be previously dispersed or dissolved in water. When using an aqueous solution, a small amount of an organic solvent may be used to accelerate the dissolution. The pH of the treatment liquid according to the present invention is at least in the range of 7.5 to 10.5, more preferably 8.0 to 10.0, in the treatment liquid containing the compound.
It is desirable to keep in the range of.

It is desirable to further use a preservative and / or a bactericide in the treatment liquid used in the rinsing step according to the present invention. The amount added to the treatment liquid must be adjusted depending on the type of antiseptic and / or bactericide used (sterilizing power), the species of the bacteria mixed in the treatment liquid and its amount, the treatment liquid exchange period, etc. It is used in the range of 10 to 10,000 ppm. It is desirable that the preservative and / or bactericide be added to at least the circulating treatment liquid during the plate making period, but if it is mixed with the circulating treatment liquid after supplying and treating the unused treatment liquid, at least unused It may be contained in the treatment liquid.

In addition to the above-mentioned additives, in the treatment liquid used in the rinse step according to the present invention, at least the antifoaming agent according to the present invention is added at least as long as it is added in an emulsion form to the unused treatment liquid. In order to improve the rinsing effect, a conventionally known surfactant can be used in combination within a range that does not impair the mixing stability of the defoaming agent according to the invention. Further, an appropriate amount of a pH adjusting agent, a wetting agent, a rust preventive agent, etc. may be mixed and used.

The treatment liquid supply system in the rinse treatment process is similar to that of the eluate, and a conventionally known liquid supply mechanism, for example, a shower or a dip system is used to supply the circulating treatment liquid.
Although a high-pressure spray, a shower, or the like can be used to supply the unused processing liquid, unlike the elution processing, the rinsing processing must be able to quickly remove completely the removed substances remaining on the plate with the processing liquid. Therefore, the supply liquid may be directly supplied to the plate surface as long as it has a mechanism capable of suppressing scattering, or the processing liquid may be compressed or supplied together with compressed air. Furthermore, in order to improve the rinse treatment, the elution promoting member described in Japanese Patent Publication No. 3-27038 may be used in the rinse treatment mechanism.

The unused treatment liquid according to the present invention is a rinsing effect for cleaning the plate surface by removing the circulating treatment liquid which is colored and fatigued and foamed due to many uses remaining on the plate surface, and a defoaming agent for breaking foaming. Both effects must be achieved. From the rinsing effect, unused treatment liquid can be discarded after use or mixed with circulating treatment liquid and reused, resulting in an increase in waste liquid.Therefore, it is necessary to cover the entire plate surface only while the printing plate passes. It suffices to supply an amount of unused processing liquid. Further, from the viewpoint of the defoaming effect, it is important to supply the defoaming agent contained in the unused treatment liquid to the entire foaming surface, more preferably at least the defoaming agent remains on the foaming surface. Therefore, in the present invention, the unused treatment liquid is preferably a liquid supply system by spraying. Supplying unused processing liquid and high-pressure air to the plate surface in the rinse step
It is disclosed in Japanese Patent No. 261543, and this supply system can be used for supplying the unused processing liquid according to the present invention.

When the unused treatment liquid according to the present invention is supplied by spraying, the supply amount per unit area of the printing plate is preferably 25 to 200 ml / m ² , more preferably 50 to 1
50 ml / m ² is preferred. The compressed air pressure during liquid supply is preferably in the range of ^{2 to} 10 kg / cm ² , and more preferably 3 to
It is 7 kg / cm ² . If the amount of liquid supplied is less than 25 ml / m ² , not only the cleaning effect will be significantly reduced, but also the liquid supply may be uneven due to lack of liquid.
If it exceeds / m ² , the unused treatment liquid stays on the plate and the cleaning effect is basically not improved, and the waste liquid is increased. Further, while the compressed air is reduced by half is also cleaning effect if the lower 2 kg / cm ^2, exceeds the 10 kg / cm ²吐液not only cleaning effect deteriorates again becomes mist, is close discharge hole and the plate surface Therefore, the plate is more likely to be deformed, and the load on the device is increased in terms of producing compressed air.

At least one kind of the treatment liquid used in the rinsing treatment is supplied to the solubilized photoconductive layer removing means used for removing the solubilized photoconductive layer in the solubilized photoconductive layer removing step, and is supplied to the removing means. It can be used for cleaning and removing the adhered eluate and photoconductive layer components. If the cleaning / removing liquid is a circulating treatment liquid in the rinse treatment step, it is not necessary to provide a separate storage tank, and it may be directly supplied from the circulating tank. In addition, if a cleaning / removing liquid dedicated storage tank is provided, at least one type of rinse treatment used treatment liquid and other liquids such as unused treatment liquid, diluting liquid, various cleaning agents and
Alternatively, a liquid mixture obtained by mixing the photoconductive layer component dispersant-containing liquid and the like in this storage tank may be supplied.

The cleaning / removing liquid may be supplied at any time other than during the passage of the solubilized photoconductive layer removing means, but the solubilized photoconductive layer removal step is performed immediately after the printing plate passes. It is desirable to do it in time. Further, as long as the removed matter adhered to the removing means does not adversely affect the subsequent plate-making quality and the like, cleaning may not be performed during continuous plate-making, and the next plate-making material may be washed within the set cleaning time. When the solution is carried into the step of removing the solubilized photoconductive layer, the supply of the cleaning removal solution may be interrupted during the cleaning. The cleaning removal liquid supply time and the total amount of liquid supplied at one time depend on the liquid supply system,
It may be determined according to the plate-making conditions and the degree of adherence of the removed material, and the supply (discharge) speed may be changed or intermittent supply may be performed. The cleaning / removing liquid may be supplied from a plurality of cleaning / removing liquid supplying means at different cleaning / removing liquids or at different timings.

Solubilized photoconductive layer removing step The treatment liquid used for cleaning the elastic member is preferably discarded together with the removed material removed from the printing plate by the removing means in the solubilized photoconductive layer removing step. Since the removed substance has a high viscosity and may adhere to the waste system, the cleaning and used treatment liquid also has an effect of suppressing this adherence. If there is a processing solution that was originally used as a cleaning / removing solution and is originally circulated and reused, it is desirable to replenish at least a replenishing solution corresponding to the cleaning consumption.

As described above, the function of each step of the present invention is to supply an excess eluate to the plate surface in the eluate supply step,
The eluate flows over the plate and a part of it flows down from the plate end surface to promote the elution and suppress the elution defect due to the liquid supply failure.
The step of removing the solubilized photoconductive layer is to remove the removed substance composed of the solubilized photoconductive layer component and the solubilized photoconductive layer component by the solubilized photoconductive layer removing means. The printing plate that has undergone the elution process is rinsed at least once with a circulation processing solution to wash and remove the residual removal material on the plate, and then rinsed with an unused processing solution containing an antifoaming agent to remain on the plate. The circulating treatment liquid is also removed, and the foaming of the circulating treatment liquid is defoamed by the defoaming agent contained in the unused treatment liquid. In addition, by using the treatment liquid used in the rinse treatment step for washing the solubilized photoconductive layer removing means, if desired, a method for treating an electrophotographic lithographic printing plate that reduces the platemaking stability and the waste liquid and the burden of maintenance management is provided. Can be provided.

[0035]

EXAMPLES The present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples without departing from the object thereof.

Example 1 JIS 1050 aluminum (thickness of 0.3 mm) was placed at 60 ° C.
It was immersed in a 10% sodium hydroxide aqueous solution and etched so that the amount of aluminum dissolved was 6 g / m ² . After washing with water
It was immersed in a 30% aqueous nitric acid solution for 1 minute for neutralization, and then thoroughly washed with water. Next, electrolytic surface roughening was performed in a 3.0% hydrochloric acid aqueous solution at 35 A / dm ² for 50 seconds, and the surface was washed by immersing it in a 20% sulfuric acid aqueous solution at 50 ° C. and then washed with water. Further, anodizing treatment was performed in a 20% aqueous solution of sulfuric acid to form an aluminum oxide film on the surface, and the support for printing plate was prepared by washing with water and drying. The photoconductive composition shown in Table 1 dispersed on the surface-treated surface of the support for 1 hour with a paint shaker was coated with an extrusion coater so that the solid coating amount was 4.4 g / m ^2, and then 90 It was dried at 3 ° C. for 3 minutes to prepare an electrophotographic lithographic printing plate.

[0037]

[Table 1]

The obtained electrophotographic lithographic printing plate was 400 mm
It was cut into × 550 mm, shielded from light and heated at 50 ° C. for 2 hours, and then cooled to room temperature. This printing plate was charged by a corotron in the dark so that the surface potential became about +280 V, and then scanning image exposure was performed using a semiconductor laser (780 nm), and immediately a positively charged toner (manufactured by Mitsubishi Paper Mills, LOM- ED
Liquid reversal development was carried out in III), and after drying with cold air to remove the toner dispersion medium, the toner was further heat-fixed to form a toner image on the photoconductive layer. A plate making process was carried out on the above toner-developed printing plate using a processing apparatus as shown below.

FIG. 1 shows the electrophotographic lithographic printing plate processing apparatus used in this embodiment. The basic configuration of this processing apparatus is composed of four zones: an eluate coating zone A, a solubilized photoconductive layer removal discard zone B, a rinse treatment zone C, and a protective gum coating zone D. The printing plate is a printing plate in the direction of the arrow. By being inserted into the transport line 1, it is sandwiched between a pair of rolls and automatically transported, and is used for plate making processing.

The eluate application zone A is composed of the eluate supply pipe 2
7, the rectifying plate 28, and the eluate supply unit including the liquid supply roll 11a, and the eluate measurement unit including the liquid measuring tool 47 and the guide roll 13. As the liquid measuring tool 47, a wire bar in which a stainless wire 50 having a diameter of 175 μm was spirally and densely wound around a rotating shaft 51 was used. Forced drive transmission is not carried out to the rotary shaft 51 of the wire bar, but rotation is transmitted by contact with the translation plate during liquid measurement. The eluate 16 is supplied from the eluate supply pipe 27 to the rectifying plate 28.
The effluent, which is rectified by and is supplied to the plate surface through the liquid supply roll 11a, and measured by the eluate measuring unit, flows on the liquid guide plate 75 installed above the circulating eluate storage tank 3 and the liquid is discharged. It is again collected in the circulating eluate storage tank 3 through the drop hole 78.

Further, the circulating eluate liquid storage layer 3 is replenished with the eluate replenishing liquid in an amount corresponding to the liquid measurement residual liquid amount. The eluate replenisher 19 is replenished after the circulating eluate 16 has been reduced by a certain amount, and immediately after the printing plate has passed through the liquid measuring tool 47, the replenisher pump 94, the pipe 122, and the replenisher are removed from the replenisher tank 7. It is supplied to the liquid measuring instrument 47 through the supply pipe 54, and is supplied to the eluate circulation together with the circulating eluent 16 while cleaning the liquid measuring instrument 47.

The solubilized photoconductive layer removal discard zone B is a solubilized photoconductive layer removal section composed of a scraping blade 22, a backup roll 20, and a backup roll cleaning blade 23, which is means for removing the solubilized photoconductive layer, and scraping. The cleaning / removing liquid supply unit includes a cleaning / removing liquid supply pipe 52 for supplying the circulating treatment liquid to the blade 22, and the removal waste liquid primary storage tank 4. The pressure of the scraping blade 22 was adjusted so that the contact width with the backup roll 20 was minimized in the range where the solubilized photoconductive layer was optimally removed. The liquid scraped off by the scraping blade 22 is temporarily stored in the removal waste liquid primary storage tank 4, but is released to the removal waste liquid secondary storage tank 9 via the pipe 114 by opening the valve 104. It has become like.

The rinse treatment zone C supplies the circulation treatment liquid 36 stored in the circulation treatment liquid storage tank 5 directly from the two circulation treatment liquid supply pipes 37 and 38 to a circulation treatment liquid supply section and conveys it. It is arranged in parallel with the pair of rolls 31 and 32, and is composed of an unused processing liquid supply section that supplies the unused processing liquid together with compressed air by discharging it from the spray gun 33. Four sets of spray guns 33 are installed with a 10 cm interval between the centers of the nozzles, and the liquid discharge range of one set of spray guns is set so as to be wider than 10 cm in the plate conveyance width direction with respect to the plate surface. . Further, the nozzles are all directed vertically downward with respect to the plate transport surface. Spray gun 3
3 A shade 83 opened in the plate surface direction is attached in order to prevent scattering of mist or the like that may occur during operation.

Above the spray gun 33, an unused treatment liquid storage tank 88 is arranged as shown in FIG.
The unused treatment liquid 39 is supplied to the spray gun 33 via 6. The compressed air supplied to the spray guns 33 is reduced by the pressure reducing valve 125 to 4 kg / cm ² for the air compressed by the compressor 81, and each spray gun 3
3 was supplied. The unused treatment liquid 39 is supplied by the unused treatment liquid supply control means (not shown) after the leading edge of the printing plate reaches the transport roll pair 31 and then the trailing end of the printing plate passes through the transport roll pair 32. It is set to discharge for a second, and the supply amount is about 150 ml / m ^{2 for} all spray guns.
I adjusted it so that.

The protective gum solution application zone D includes a protective gum solution supply pipe 45, a surface roughening solution measuring roll 43, and a liquid supply roll 4.
0 and a lower guide roll 41, a protective gum solution supply part, a cleaning means including a cleaning solution supply pipe 60 for cleaning the protective gum solution supply part, a protective gum solution storage tank 8 for storing the protective gum solution 46, and an excess. It comprises a protective gum liquid primary storage tank 6 for receiving the protective gum liquid. The protective gum solution supplied from the protective gum solution supply pipe 45 is metered by the surface roughening solution metering roll 43, applied to the printing plate, spread by the roll pair 40 and 41, and squeezed. The excess squeezed protective gum solution is recovered in the protective gum solution storage tank 8 through the pipe 120 and the valve 108, and is circulated and reused.

For the plate-making process, processing solutions having the compositions shown in Tables 2 to 6 were used. The elution replenisher and the unused treatment liquid A were appropriately replenished to the respective liquid storage layers according to the amount of use reduction.
The elution time was adjusted based on the relationship between the plate transport speed and the solubilization of the photoconductive layer immediately before being carried into the solubilized photoconductive layer removing section.

[0047]

[Table 2]

[0048]

[Table 3]

[0049]

[Table 4]

[0050]

[Table 5]

[0051]

[Table 6]

Using the above processing apparatus and each processing solution, the scraping blade was washed after 50 plates were continuously plate-made with the long side of the printing plate being the transport direction, and immediately after the scraping blade was washed, continuous plate making was repeated under repeated conditions. The plate was made for 500 days a day. The cleaning of the scraping blade 22 is performed by operating the liquid feeding pump 95 two seconds after the trailing edge of the last printing plate, which is the initial setting of continuous plate making, passes through the scraping blade 22, and the circulating treatment liquid storage tank 5 is activated.
Then, the circulating treatment liquid 36 was supplied to the scraped blade adhering surface of the scraping blade for substantially 10 seconds for cleaning through the cleaning and removal liquid supply pipe 55.

When the continuous plate making was carried out under the above plate making conditions, the circulating treatment liquid 36 slightly foamed due to the liquid circulation in the circulating treatment liquid supply part, but at the latest after the supply of the unused treatment liquid containing the defoaming agent. Almost all of the plates were defoamed, and the circulation treatment liquid 36 was considerably dyed after making a total of 2000 plates, but no plate surface cleaning defects occurred on all the plate-making products, and the foamed circulation treatment liquid flowed into the protective gum liquid. Could not be seen. Also, plate making start 10
Edition, 100 edition, 500 edition, 1000 edition, and 2
After examining the printability of the 000th plate,
In normal printing, of course, even when the printing plate heated at 50 ° C. was printed again after the printing was completed, scumming was not observed, and good printed matter was obtained on all printing plates.

Comparative Example 1 The same as Example 1 except that the unused treatment liquid A used in Example 1 was replaced with a treatment liquid (unused treatment liquid B) in which the antifoaming agent KS68 was omitted. Plate making was carried out under the same treatment liquid and plate making conditions. As a result, cream-like fine bubbles covered the surface of the circulating treatment liquid in a bulky manner even after the continuous plate making of 50 plates at the latest. Since the bubbles eventually reached the height of the printing plate transport line, the bubbles reattached to the back surface of the printing plate after passing through the transport roll pair 32, and the protective gum solution 46 also turned blue due to the foam component of the introduced circulating treatment liquid 36. As the liquid bubbled and the liquid pH increased and turbidity occurred at the bottom of the liquid storage tank 8, the protective gum liquid 46 had to be replaced.

Example 2 The unused treatment liquid B used in Comparative Example 1 was changed to the unused treatment liquid C shown in Table 7, and the circulation treatment liquid was foamed after completion of plate making in Comparative Example 1. The same amount of the unused circulating treatment solution was mixed with the same amount as in Example 1, and the eluate, the eluent replenisher, and the protective gum solution were the same new treatment solutions as in Example 1 for plate making. .

[0056]

[Table 7]

As a result, at the start of plate-making, the circulating treatment liquid foamed as in Comparative Example 1, but after several plate-making, the generated bubbles were almost broken, and a total of 1000 plates were prepared, but all the plate-made products had plate surfaces. No poor cleaning occurred, and no inflow of the foamed circulating treatment solution into the protective gum solution was observed. In addition, the printability was examined for the 10th plate, the 100th plate, the 500th plate, and the 1000th plate, which were the same as in Example 1, and it was found that in normal printing, printing was performed at 50 ° C. after printing. No background stain was generated even when the plate was printed again, and good printed matter was obtained in all printing plates in exactly the same manner as in Example 1.

Comparative Example 2 The same as Example 2 except that the liquid containing the fatigue circulation treatment liquid prepared in Example 2 was used as a circulation treatment liquid and tap water was used in place of the unused treatment liquid C to make a plate. When plate-making was carried out under the plate-making conditions, similar to Example 2, after the dozen-plate-making, fine creamy foam covered the surface of the circulating treatment liquid in a bulky manner. The plate making was interrupted, and the unused treatment liquid containing the defoaming agent used in Example 2 was sprayed on the circulating treatment liquid which was foamed until the foam was broken. When the plate making was further continued after the foam was broken, the circulating treatment liquid was considerably foamed after the 50th plate making at the latest, and eventually the foaming surface reached the conveying height.
After 2 passes, the protective gum solution 46 redeposited on the back surface of the printing plate due to the foam component of the circulating treatment solution 36 brought in, and the protective gum solution 46 also changed its color to blue and the solution pH increased, causing turbidity at the bottom of the storage tank 8. The protective gum solution 46 had to be replaced.

[0059]

As described above, when the electrophotographic lithographic printing plate is processed by the electrophotographic lithographic printing plate processing method of the present invention, the foaming of the circulating treatment liquid used in the rinsing step is suppressed and the long-term treatment is prevented. By enabling stable treatment over a long period of time, the replacement frequency of the treatment liquid is greatly reduced, and the burden of waste liquid treatment and maintenance management is reduced, resulting in excellent effects.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional configuration diagram of an electrophotographic lithographic printing plate processing apparatus used for carrying out a method for processing an electrophotographic lithographic printing plate of the present invention.

FIG. 2 is a cross-sectional configuration diagram showing a spray gun for discharging compressed air and an unused processing liquid in an unused processing liquid supply unit in an electrophotographic lithographic printing plate processing apparatus.

[Explanation of symbols]

 A Eluent coating zone B Solubilized photoconductive layer removal waste zone C Rinse treatment zone D Protective gum solution coating zone 1 Printing plate transport line 5 Circulating treatment liquid storage tank 22 Scraping blade 33 Spray gun 36 Circulating treatment liquid 39 Unused Treatment liquid 81 Compressor

Claims (1)

[Claims] 1. A non-image area photoconductive layer is formed by forming a toner image on a lithographic printing plate precursor having a photoconductive layer provided on a conductive support by an electrophotographic method and then supplying an eluent to the toner image forming surface. Swelling and solubilizing the solubilizing solution, removing the eluate on the plate and the solubilized photoconductive layer by means of the solubilized photoconductive layer removing means, and then circulating and reusing it in the subsequent rinse treatment step. What is claimed is: 1. A method for treating an electrophotographic lithographic printing plate which comprises rinsing with a liquid at least once, wherein the unused treatment liquid contains at least an antifoaming agent.