JPH0588417A - Electrophotographic planographic printing plate processing method - Google Patents

Abstract

(57) [Summary] [Purpose] Not only is it possible to prevent the elution failure while suppressing the thinning of the image during elution and to evenly elute the entire surface of the plate, but also to suppress the deterioration of liquid properties and to stabilize it over a long period (EN) Provided is a processing method of an electrophotographic lithographic printing plate, which enables an elution process, thereby significantly reducing the frequency of liquid exchange and reducing the burden of waste liquid and maintenance management. [Construction] A toner image is formed on a lithographic printing plate precursor having a photoconductive layer provided on a conductive support by an electrophotographic method, and then an eluate is excessively supplied to the toner image forming surface to form a non-image. After swelling and solubilizing the photoconductive layer, an electrophotographic lithographic plate that measures the amount of eluate on the plate with a rotatable liquid measuring tool and removes the solubilized photoconductive layer and the remaining eluate after the transportation. In the method of processing a printing plate, the weight applied to the plate is 0.5 with respect to the effective measuring width of the liquid measuring tool which is substantially related to the liquid measuring.
A method for treating an electrophotographic lithographic printing plate, characterized in that it is about 4.0 kg / m.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithographic printing plate precursor having a photoconductive layer provided on a conductive support, and a toner is prepared by electrophotography.
Regarding an electrophotographic lithographic printing plate processing method for producing a printing plate by performing elution removal of the non-image area photoconductive layer other than the toner image area after forming an image, suppressing image streaking due to elution In addition, the present invention relates to a method for treating an electrophotographic lithographic printing plate, which is capable of performing stable elution treatment over a long period of time without causing defective elution and reducing the frequency of liquid exchange.

[0002]

2. Description of the Related Art In recent years, mechanical image processing technology and large capacity data
By controlling data storage and establishing transmission technology, computer control of image input, correction, editing, layout of pages such as characters and figures, page layout, etc., all at once, can be instantly made into a terminal plotter at a remote location by high-speed communication network or satellite communication. An electronic editing system that can output is running. In particular, in the field of newspaper printing, which is based on the idea of immediacy, the demand for this electronic editing system is high.

By the way, the photosensitive lithographic printing plate called PS plate, which has been conventionally used also in the field of newspaper printing, generally has low sensitivity because image formation involves at least a chemical structure change due to actinic rays of the photosensitizer. That is, the silver salt photographic film original plate on which an image is recorded in advance is contact-exposed to perform plate making. Therefore, even when the electronic editing system is in operation, image output is once performed on the silver salt photographic film, and based on this, the printing plate is indirectly produced by contact exposure to the PS plate. is there. This has a high sensitivity that a printing plate can be produced within a practical time by a light source of an output plotter (eg, He-Ne laser, semiconductor laser, etc.), and it is as high as a conventional type. This is because it is difficult to develop a direct printing plate that is easy to handle.

Therefore, an electrophotographic photoreceptor is considered as a photosensitive material having a high photosensitivity which can provide a direct printing plate. Conventionally, as printing plate materials utilizing electrophotography, for example, Japanese Patent Publications No. 47-47610 and No. 48-18325,
Photoconductive zinc oxide / resin dispersion type offset printing plate materials described in JP-A-48-40002 and JP-A-51-15766, and JP-B-37-17162 and JP-A-38-7758.
No. 41-2426, No. 46-39405, JP-A No. 50-19509, No. 52-2437, and No. 54-.
No. 134632, No. 54-145538, No. 55-1
Organic photoconductive compound / binder resin printing plate materials such as those described in JP-A-53948 and JP-A-57-147656 are known.

The former photoconductive zinc oxide / resin-dispersed offset printing plate material has a zinc oxide-rich photoconductive layer based on paper having water resistance and conductivity, and is a toner image by electrophotography. After the formation, the non-image area is moistened with a desensitizing treatment liquid (for example, an acidic aqueous solution containing a hexacyanoiron salt or an inositol hexaphosphate) in order to render it non-sensitized, and then subjected to printing. The offset printing plate thus treated has a maximum number of printing sheets of about 10,000 from the viewpoint of good print image reproducibility, and when the composition with enhanced desensitization is used, the image quality deteriorates. Have.

On the other hand, in the latter organic photoconductive compound / binder resin printing plate material, since these electrophotographic photoconductors are generally provided on the aluminum substrate, the adhesion between the aluminum substrate and the photoconductive layer does not occur. If strong, essentially PS
It has printing durability equivalent to or better than that of the plate. Also, already 800
Organic photoconductive compounds having a practical sensitivity of not less than nm are known, and the printing plates using these compounds are being put to practical use.

A general plate-making method for these electrophotographic lithographic printing plates is as follows. After forming a toner image by a known electrophotographic image forming method on an electrophotographic printing plate precursor using a photoconductive compound, a toner image is formed. The non-image area other than the image area is treated with a treatment liquid containing an alkaline agent and the like, and a washing solution is further supplied to wash the plate surface, thereby dissolving (so-called elution) the non-image area photoconductive layer from the plate. Made into a plate.

Particularly, the elution step is different from the alkali development step in the PS plate and utilizes the difference between the alkali solubility of the toner and that of the photoconductive layer. ) Is prevented from elution due to the resist property of the toner, but since the photoconductive layer itself at the toner-adhered portion does not become alkali-insoluble (or hardly) -soluble, elution is excessively promoted. In this case, the permeation of the eluate called side etching from the side surface of the photoconductive layer also erodes the photoconductive layer in the image area, and good fine line reproducibility cannot be obtained. On the other hand, if the elution is performed slightly, the photoconductive pigment does not remain on the non-image area support and it seems that the photoconductive pigment is eluted. It may occur.

Therefore, the elution in the alkali elution type electrophotographic lithographic printing plate is carried out by the toner composition, its developing method, the selection of the eluent formulation, the elution treatment mechanism, the electrophotographic lithographic printing plate photoconductive layer and the eluent. It is important to pay attention to plate making processing conditions such as matching and processing time, and more rigorous processing is required than alkaline development on the PS plate. In particular, if a large number of electrophotographic lithographic printing plates are processed intermittently by an automatic plate making machine, for example, not only the eluent but also the elution characteristics can be obtained between the liquid supply system and the roll while stopped. It is also necessary to pay attention to the treatment method such as liquid sticking and the liquid physical properties related to the mechanism.

As a method of developing and eluting a PS plate and a planographic printing plate such as an alkali-eluting electrophotographic printing plate in a conventional automatic plate making machine, a circulating processing solution is directly or Is a method in which the printing plate is contacted through a roll and / or a current plate, or a printing plate is curvedly dipped in a processing liquid tank by a guide roll or the like, and the processing liquid is convected by a shower in the liquid and supplied to the plate surface. JP-A-62-238564 for preventing processing fluctuations caused by the processing liquid by the dip method (the above-mentioned processing liquid circulation reuse method) or the processing liquid.
As disclosed in Japanese Patent Publication, etc., a method in which the required supply amount is measured before supplying the processing liquid to the printing plate, a new liquid is supplied for each plate, and the processing liquid on the plate is discarded after the processing is completed (pre-measurement liquid disposable (Processing method), and a processing method combining these, such as disclosed in Japanese Patent Laid-Open No. 63-71855, is also known.

Further, as disclosed in Japanese Patent Application Laid-Open No. 62-59957, the processing solution is metered to a fixed amount within a time when the alkali development does not proceed, the excess solution is circulated and reused, and the processing on the plate after metering is carried out. The solution is discarded together with the solubilized photosensitive layer after the development is completed (post-measurement method), and as disclosed in JP-A-63-16353, in order to further improve the plate-making defect at the plate leading end, the solution is further measured after the measurement. A method is known in which the treatment liquid removed at the time of measurement is circulated and re-supplied to the plate top. Others, actual Kaihei 1
In JP-A-160443, in order to speed up the replacement of the processing liquid on the plate to shorten the processing time and prevent streak unevenness in the transport direction, the printing plate is held at an inclination and a large number of protrusions are provided on the facing surface. There is also disclosed a method in which a treatment liquid is supplied from above a pair of guide plates that the guide plates have and a conveyance is performed between the inclined guide plates.

Regarding the processing relationship of the electrophotographic lithographic printing plate, as described in Japanese Patent Publication No. 1-60824, scratches on the non-image area photoconductive layer swollen with an etching solution in the etching (elution in the present invention) step. A method of suppressing mechanical forced inflow of the composition of the photoconductive layer into at least the etching solution by supplying a rinse solution and scraping it off in the next step without a dropping part, and JP-A-2-93474. As in JP-A-63
A method applying the technique disclosed in Japanese Patent Publication No. -16353 is disclosed.

Among these methods, the liquid disposable processing method can prevent the processing variation caused by the processing solution, but requires a larger amount of processing solution than the liquid circulation reuse method.
Inevitably, a large amount of waste liquid is produced. Further, if the liquid amount is reduced to supply the required minimum amount, the treatment liquid may not be uniformly coated on the entire surface of the plate, and the tendency tends to be particularly strong at the top of the plate, resulting in treatment defects. .. Particularly in the plate-making process of electrophotographic lithographic printing plate, the electrophotographic photoconductive layer is thicker than the general PS plate photosensitive layer to be removed, and strict processing conditions are required. Disposable treatment method is not suitable.

On the other hand, in the treatment liquid circulation reuse method, since the excess liquid is circulated and reused, it is possible to apparently reduce the amount of waste liquid, but the conventional non-image area photoconductive layer is almost entirely removed during the dissolution removal process by the treatment liquid. Is removed from the plate into the processing solution, so even if the processing solution itself is filled with the solution and retains the desired processing characteristics, the processing solution containing a large amount of inflowing photoconductive layer In addition to various adverse effects such as liquid adhesion that occurs in the tank, liquid circulation system, and processing unit transport area, the liquid supply amount is reduced, and the liquid supply spray-discharging holes are clogged. In some cases, a residual film that causes print stains due to redeposition on the image support is brought about. Even if the non-image area photoconductive layer is not forcibly mechanically removed in the elution part, depending on the elution solution formulation, solution supply method, and elution time,
In some cases, the photoconductive layer was washed off from the plate together with the excess eluate, or even if it was not washed away, side etching progressed during the elution process to become an elution overcoat.

Therefore, there is the above-mentioned post-measurement method as a processing method which solves both drawbacks and has advantages. This method
Immediately after the alkaline developer is supplied to the plate and the amount necessary for development is left to be measured, the removal liquid at the time of measurement contains almost no components in the non-image area photosensitive layer, and the minimum amount required for alkali development. By supplying and consuming and replenishing the liquid in proportion to it, fatigue deterioration over time due to the decrease in alkalinity due to absorption and dissolution of carbon dioxide gas in the air over time is suppressed, and practically almost the same as the liquid disposable method. The plate can be made in this state, and it is unlikely to be affected by the passage of time like the processing liquid circulation reuse method. Further, even if there is a portion where the developing solution is not supplied onto the plate as a result, since the solution is spread by the solution measuring tool before the start of development, unevenness in processing is reduced.

However, when the above treatment method is simply applied to an alkali-eluting electrophotographic lithographic printing plate as the measurement after the liquid is supplied and before the swelling and solubilization of the photoconductive layer by the eluate is started, the plate edge portion, especially the plate top, is measured. Dissolution deficiency easily occurs due to insufficient liquid supply at the edge portion, or even if the dissolution deficiency is not apparently apparent, the degree of side etching differs between the center portion and the edge portion of the plate. Therefore, in order to completely prevent defective dissolution at the plate edge, it is necessary to measure more than the required amount of eluate in the plate, or to elongate the elution time. become longer. Further, in this case, the central portion of the plate becomes excessively eluted, which promotes side etching.

The reason for this elution failure is that the alkali-eluting electrophotographic lithographic printing plate photoconductive layer has a general PS from the viewpoints of initial charging potential, sensitivity, electrophotographic characteristics such as dark decay, and printing characteristics such as printing durability. It is 2 to 3 times thicker than the plate photosensitive layer, the binder resin has a higher molecular weight, the introduction rate of functional groups involved in solubilization is suppressed, and the alkali strength of the eluate is increased to prevent side etching. If the eluate is weighed before the swelling and solubilization of the photoconductive layer is started, the photoconductive layer represented by an alkali that promotes the swelling and solubilization can be used, depending on the remaining amount. The solubilization becomes slow because there is not enough solubilized species in the solubilized area, or the solubilization is insufficient and solubilization ends halfway, resulting in a residual film. In addition, since the photoconductive layer binding resin becomes water repellent as a result of improving ink acceptability, even if the liquid is apparently coated on the entire plate surface at the time of supply with an aqueous eluate, the liquid film thickness before measurement is uniform. If it does not exist, especially at the leading portion and the side end portion of the plate conveyance, the liquid repelling is induced after the measurement, resulting in poor elution.

For this reason, in the electrophotographic lithographic printing plate, with respect to the poor elution of the leading portion of the plate conveyance, JP-A-2-93
Japanese Patent No. 474 discloses a treatment method in which the treatment liquid is further supplied to the plate front portion after measuring the liquid. However, even in this method, the above-mentioned elution defect cannot be completely wiped out, and therefore the above-mentioned method causes the elution defect. In order to prevent this, the amount of residual liquid after measurement must be made considerably large, resulting in a problem that a large amount of waste liquid is produced as in the liquid disposable system.

[0019]

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-toner image area other than the toner image area is formed. In a method of processing an electrophotographic lithographic printing plate for producing a printing plate by removing the photoconductive layer of the image area by elution, a) preventing the failure of elution such as residual film while suppressing the thinning of image lines due to elution. Therefore, it is possible to prevent the liquid from degrading due to gas absorption and mixing of the solubilized photoconductive layer due to reuse of liquid circulation, and to ensure stable elution treatment over a long period of time. C) It is to provide a treatment method that significantly reduces the amount of residual liquid after liquid measurement and the frequency of liquid exchange, thereby reducing the burden of waste liquid and maintenance management.

[0020]

Means for Solving the Problems As a result of repeated studies for solving the above problems, the eluate was excessively supplied to the photoconductive layer surface of the electrophotographic lithographic printing plate precursor on which the toner image was formed, and the non-image area was formed. A method for treating an electrophotographic lithographic printing plate, which comprises solubilizing a photoconductive layer, measuring an excess amount of the eluent to a predetermined amount, and further removing the eluent on the plate and the solubilized photoconductive layer to make a plate. It is achieved by using a rotatable liquid measuring tool as the liquid measuring means and performing a pressurizing weight within a specific range with respect to a widthwise length (effective measuring width) that can substantially measure the liquid measuring tool. ..

That is, according to the present invention, 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 it is excessively eluted on the lithographic printing plate photoconductive layer surface. After the liquid is supplied to solubilize the non-image area photoconductive layer, the excess eluent is weighed to a fixed amount by pressing the rotatable liquid measuring tool, and the eluate and solubilization on the plate are carried after the conveyance. In the method for treating an electrophotographic lithographic printing plate which removes the photoconductive layer, the amount of the eluate is measured within a range that the weight added to the plate with respect to the effective measuring width of the liquid measuring tool is 0.5 to 4.0 kg / m. This is a method of processing an electrophotographic lithographic printing plate.

The purpose of liquid metering in the present invention is to separate the fatigue eluate on the photoconductive layer side from that which is relatively not fatigued, and more specifically, the fatigue eluent by elution and solubilization of the photoconductive layer. Is left on the plate and is then removed together with the solubilized photoconductive layer, and the eluent not involved in the solubilization is removed from the plate for reuse. In the processing method of the present invention, since the non-image area photoconductive layer is solubilized and liquid is measured in order to prevent defective dissolution, peeling of the solubilized photoconductive layer may be induced depending on the liquid measuring method. , The results are different from those intended by the processing method of the present invention. In order to suppress or prevent peeling, it is desirable to measure the liquid without contacting the solubilized photoconductive layer, but in practice, the ideal residual eluate film thickness (that is, the liquid measuring device and the solubilization light). The flexure of the plate may be greater than the gap with the surface of the conductive layer), resulting in peeling of the solubilized photoconductive layer.

Then, as a result of studying a method for measuring the liquid in a predetermined amount while suppressing the peeling of the solubilized photoconductive layer,
In order to suppress frictional separation and adjust the gap as much as possible in response to flexure of the plate, at least when the plate passes, the liquid measuring tool contacts the plate and rotates freely, and We have found that it is important to keep the applied pressure within a certain range. At this time, if the pressing weight applied to the plate of the liquid measuring tool is large, the liquid measuring accuracy is improved, but it is easy to induce the pressure destruction (friction peeling) of the solubilized and swollen photoconductive layer, and conversely the pressing weight. If the value is small, the elution liquid will slip and the weighing accuracy will drop, so the pressing weight against the effective weighing width of the liquid weighing tool is 0.5 to 4.0 kg / m 2.
The range is good.

The processing method of the present invention will be described in detail below 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 photoconductive layer swelling and solubilizing step, an eluate measuring step, and a solubilized photoconductive layer removing step.
In the eluate supply step, the eluate is excessively supplied to the photoconductive layer surface of the planographic printing plate on which the toner image is formed by the electrophotographic method. As the eluate supply system, a conventionally known mechanism such as a liquid discharge shower pipe, a slide hopper, a carter coater, and a dip system can be used, but especially when a shower pipe is used, the liquid discharged from the pipe is separated. The method of uniformly supplying to the surface of the photoconductive layer via a member such as (3), for example, a rectifying plate, a roll for conveying the plate, etc. is suitable. In addition, in all systems, in order to further shorten the elution time and prevent liquid supply failure, a flow promoting mechanism should be installed during the liquid metering process to replace the eluate supplied on the plate. Alternatively, it is desirable to supply the eluate multiple times.

It is necessary to supply the eluate in excess, and the amount of eluate must be larger than the amount of the eluate remaining on the plate after passing through the liquid measuring step, as well as the amount of the eluate from the end of the plate during conveyance in the liquid measuring step. It is important that the amount of spillage is such that it flows down. This allows
Part of the photoconductive layer in the non-image area swells and is solubilized, and the excess part flows over the plate and partially flows down from the plate edge while partially replacing the existing eluate in the part to be eluted. Therefore, liquid replacement frequently occurs at the plate edge, and the flow rate of the eluent near the interface of the photoconductive layer increases, so that the variation of the elution degree due to the plate portion is suppressed. The more specific amount of the eluate supplied depends on the amount of the eluent left on the plate after passing through the liquid measuring step (the liquid remaining amount), but is preferably 2 to 100 times, more preferably 5 to 30 times.
Double is good.

The eluate supplied in excess on the printing plate swells and solubilizes the photoconductive layer in the photoconductive layer swelling and solubilizing step. Dissolution of the photoconductive layer by the eluent in the swelling step of swelling the photoconductive layer is caused by penetration of at least the photoconductive layer-solubilizing species in the components of the eluate into the photoconductive layer, swelling of the photoconductive layer,
And the process of dissolving and diffusing the components of the photoconductive layer into the eluent in contact with the photoconductive layer, and the progress process is easily designed stepwise and competitively by controlling the selection of the prescription of the eluent. You can "Solubilization" of the photoconductive layer in the present invention
Means that at least the photoconductive layer to be removed swells with the eluent to become a viscous liquid layer, and the photoconductive layer can be easily removed from the plate by elution.

In the present invention, the photoconductive layer swelling and solubilizing step,
That is, immediately before the eluate metering process is carried in, the photoconductive layer in the non-image area is almost completely solubilized, and in the eluent metering process, at least a certain amount of excess eluent on the plate is left by the liquid metering means. And weigh out. Since the eluate that has flowed down before the eluate measuring step and the measurement-removing solution have almost no fatigue in the elution process, they can be recycled and used.

In the liquid metering according to the present invention, it is possible to prevent the mixing of the solubilized photoconductive layer during the metering of liquid and prevent the effluent which is not substantially involved in the solubilization of the photoconductive layer. It is important to remove it from the plate. Therefore, if the amount of eluent left on the plate after liquid metering (liquid metering residual amount) is large, the amount of eluent consumed inevitably increases and the elution efficiency per unit amount of eluent decreases. Since the solubilization further progresses until the post-solubilization photoconductive layer is removed and side etching is deteriorated, it is desirable that the eluate carry-out amount is small.

However, if the carry-out amount of the eluate is too small, the viscosity of the removing liquid increases significantly as a result, and accordingly, in the continuous plate making, the removing liquid accumulates and is removed in the solubilized photoconductive layer removing portion (member). This is not preferable because the effect is reduced and the photoconductive layer solubilized in the liquid metering unit is more likely to peel off. Furthermore, when the liquid material on the plate is removed to the maximum extent in the alkali treatment step as in the liquid circulation system, the fatigue eluate and the photoconductive layer component are also mixed, which is different from the intention of the treatment method of the present invention. Therefore, the amount of the eluate taken out after the liquid measurement in the present invention depends on what kind of liquid measurement means is used.
~ 120g / m ² is good, more preferably 40 ~ 100g
/ m ² is good.

The liquid measuring tool in the liquid measuring step according to the present invention can be rotated by some kind of drive transmission in the plate conveying direction, and can be rotated at least with respect to the plate surface in all the rotating directions in the measuring width direction. It is essential to have a shape that prevents uniform peeling of the solubilized photoconductive layer during liquid measurement and prevents it from peeling off. Examples of the liquid measuring tool used in the present invention include a wire bar in which a thin wire having a constant diameter is spirally wound around a shaft, a grooved roll, a plane bar, and a lightweight rubber roll. The liquid measuring tool may be rotated by forcibly rotating the rotating shaft in a forward or reverse direction at a certain peripheral speed, or at least only when the plate passes.

It is preferable that the weight of the liquid measuring device is heavy to some extent from the viewpoint of improving the measuring accuracy, but peeling of the solubilized photoconductive layer occurs depending on the liquid measuring device, so 0.2 to 6.0 kg is preferable. The pressing weight according to the present invention can be sufficiently covered by the weight of the liquid measuring device alone, but if desired, the entire liquid measuring device can be pressed with a pressure roll or the like, or the nip pressure is applied to both ends of the liquid measuring device. Alternatively, the substantial pressing weight may be increased. Also, the effective measuring width of the liquid measuring tool, for example, the length of the portion around which the wire is wound in the wire bar, is preferably longer than the plate conveying lateral width (plate width), and the effective measuring width / maximum plate width is 1.
It is preferably 05 or more, more preferably 1.2 or more. Further, it is desirable that one end is at least 20 mm or more, more preferably 50 mm or more longer than the maximum plate width. However, if the plate width is too small with respect to the effective measurement width, the liquid measuring tool is slightly bent and the residual measurement liquid amount also increases.

In the liquid metering according to the present invention, a relatively lightweight rotating shaft (bar) is used from the viewpoints of easy adjustment of the metered liquid amount and suppression of separation runoff of the solubilized photoconductive layer component. A wire bar wound with a wire is preferably used. It is desirable that the bar is a circular cylindrical or columnar object having a uniform cross-sectional shape that is hard to undergo permanent deformation and has a diameter of 5 to 40 mm.
However, 10 to 25 mm is more preferable, but since the weight per unit length is important in the present invention, a member is selected in consideration of the wall thickness and the diameter in order to adjust to the desired weight. There is a need to. Although the thickness depends on the material, it is preferably 0.4 mm or more. The wire has sufficient strength,
Various materials can be used that are not affected by the eluate and have a uniform winding, but stainless wire is preferable. The wire diameter is 0.12 to 0.70 mm, more preferably 0.15 to 0.70 mm.
53mm is good. The winding may be dense or may be wound at regular intervals as desired.

The printing plate which has undergone the liquid metering step is subjected to a solubilized photoconductive layer removing step, the solubilized photoconductive layer remaining in the non-image portion is removed by a removing means, and the printing plate is conveyed to the next step. If the liquid measurement is appropriately performed in the liquid measurement step, the progress of further solubilization is considerably suppressed.However, in order to prevent the deterioration of the side etch, the solubilized photoconductive layer removal time after the liquid measurement is further increased. It is desirable to remove the solubilized photoconductive layer in the removal step in a short time, preferably 3 seconds or less, more preferably 1 second or less. The liquid removed in the solubilized photoconductive layer removal step is
Most of them are solubilized photoelectrokinetic layer and fatigue eluate,
It is desirable to dispose of it. In addition, it is desirable to replenish at least the amount of the eluate contained in the waste liquid with a new liquid so as to secure the amount of circulating liquid and maintain the elution activity.

Examples of the removing means according to the present invention include a method using an air knife, a rubber blade, an elastic roll, a rotating and non-rotating (fixed or slidable) brush, and a Molton roll. .. The elastic roll can remove the eluate on the plate surface by the nip pressure through the printing plate between the pair of rolls, and the rubber blade uses an elastic material whose contact surface with the plate is smooth at least in the conveying path of the printing plate. It is possible to remove the effluent on the plate surface by arranging them alongside each other and making a sliding contact with the plate surface. Examples of the elastic material used in these include silicone rubber, neoprene rubber, butyl rubber, ethylene propylene rubber, nitrile butadiene rubber, and Teflon coat rubber, and the hardness thereof is 75 degrees or less, more preferably 50 degrees or less. .. When used for an elastic roll, a lower hardness is better, and when used for a blade, a higher hardness is better. When installing the rubber blade, a guide roller that rotates at a peripheral speed higher than the conveying speed is installed under the rubber blade, or pressurization is applied immediately after the plate leading edge passes through the rubber blade to prevent the conveyance failure from being induced. It is desirable to provide some mechanism for doing so. In addition, in the removal using a molton roll and a brush, a small amount of treatment liquid may be supplied at least at the time of removal in order to accelerate the peeling removal of the solubilized photoconductive layer.

In the present invention, the rubber blade is preferably used for the comprehensive reasons such as reduction of maintenance load on the mechanism, reduction of waste liquid amount, removal efficiency, and prevention of deterioration of elution quality. For rubber blade scraping (pressure) adjustment, rubber hardness,
It can be selected depending on the thickness, effective elastic length, plate contact angle, shape of contact portion, etc., the thickness is 2 mm or more, effective elastic length is 2 to 20 mm, plate contact angle is 10 to 60 °, and more preferably 25 to 45 ° is good. Further, in order to improve the pressure, a pressure assisting member such as a metal plate and means may be used on the side opposite to the plate contact surface of the rubber blade.

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, and the eluate flows on the plate in the photoconductive layer swelling and solubilization step. Furthermore, a part of it flows down from the plate end surface to promote the elution and the suppression of the elution defect due to the poor liquid supply.In the eluate measuring step, the excess eluent on the plate is measured and removed by the liquid measuring means. In the step of removing the solubilized photoconductive layer, the fatigue eluate and the solubilized photoconductive layer are removed. In addition, as for the eluate, the carry-out after liquid measurement is replenished with a new liquid and the surplus not involved in elution is circulated and reused, and the fatigue eluate is removed and discarded together with the solubilized photoconductive layer. It is possible to provide a processing method in which the frequency of liquid exchange is drastically reduced by the consumption of the eluate that is close to the minimum required, and thus the burden of waste liquid and maintenance management is reduced.

The electrophotographic lithographic printing plate processed in the present invention comprises a photoconductive layer provided on a conductive support and is capable of forming a toner image by a usual electrophotographic development system. As the electroconductive support used in the electrophotographic lithographic printing plate, a plastic sheet having an electroconductive surface, solvent-impermeable and electroconductive paper, or aluminum, zinc, copper-aluminum, copper-stainless steel, chromium -Bimetal such as copper, chrome-copper-aluminum, chrome-lead-iron, chrome-copper-stainless metal such as trimetal such as stainless steel is used as a base, and at least the surface on which the photoconductive layer is provided is hydrophilized. And a conductive support. Also,
The thickness thereof is preferably 0.07 to 2.0 mm, more preferably 0.1 to 0.5 mm. Among these substrates, aluminum plates are preferably used. The aluminum plate may contain aluminum as a main component and a slight amount of a different element, and conventionally known and officially used materials can be appropriately used.

In order to impart these desired surface textures to the surface of the support on which the photoconductive layer is provided, graining or anodic oxidation may be performed by a known method. Prior to the graining treatment, if desired, a degreasing treatment with a surfactant or an aqueous alkaline solution is carried out.
The graining treatment method includes a mechanical surface roughening method, an electrochemical surface roughening method, and a chemical surface selective dissolution method. As the mechanical surface roughening method, known methods such as a ball polishing method, a brush polishing method, a blast polishing method and a buff polishing method can be used.
The electrochemical surface roughening method includes a method of performing alternating current or direct current in a hydrochloric acid or nitric acid electrolytic solution. Further, as disclosed in Japanese Patent Laid-Open No. 54-63902, a method of combining the two can be used. The substrate thus roughened is
It is used after being subjected to alkali etching treatment and neutralization treatment as needed.

The substrate subjected to the above treatment is anodized to form an oxide film on its surface. As the electrolyte used for the anodizing treatment, sulfuric acid, phosphoric acid, oxalic acid or the like, or a mixed acid thereof or the like is used, and the concentration thereof is appropriately determined depending on the kind of the electrolyte. The anodizing condition cannot be unconditionally specified because it varies greatly depending on the electrolyte used, but the amount of anodized film is preferably 0.10 to 10 g / m ² , more preferably 1.0 to 6.0 g / m ^2. Is preferred.

If necessary, an intermediate layer may be provided between the conductive support and the photoconductive layer in order to improve adhesiveness, printability, electrophotographic characteristics and the like. A desired electrophotographic photoconductive layer can be provided on the conductive support thus obtained to obtain an electrophotographic lithographic printing plate precursor.

The photoconductive layer of the electrophotographic lithographic printing plate to be treated in the present invention contains at least a photoconductive compound, but known photoconductive compounds exemplified below can be used. a) Triazol derivatives described in U.S. Pat. No. 3,121,197, b) Oxadiazole derivatives described in U.S. Pat. No. 3,189,447, etc., and c) Imidazo described in JP-B-37-16096. -L derivative, d) U.S. Pat. Nos. 3,542,544 and 3,615,402.
No. 3820989, Japanese Patent Publication No. 45-555
No. 51-10983, JP-A-51-93224.
No. 55-108667, No. 55-156953.
Nos. 56-36656 and the like, polyarylalkane derivatives, e) U.S. Pat. Nos. 3,180,729 and 4,278,746, JP-A-55-88064, and JP-A-55-8806.
5, No. 49-105537, No. 55-51086.
No. 56-80051, No. 56-88141, No. 57-45545 and the like, and pyrazoline derivatives and pyrazolone derivatives, f) U.S. Pat. No. 3,615,404, Japanese Patent Publication No. 46-
3712, 47-28336, JP-A-54-83
No. 435, No. 54-110836, No. 54-1199.
25, etc., phenylenediamine derivatives, g) U.S. Pat. Nos. 3,567,450 and 3,180,703.
No.3, No. 340597, No. 3658520, No. 42
No. 32103, No. 41755961, No. 4012376
Description, West German Patent (DAS) 1110518, JP-B-49-35702, JP-A-39-27577, JP-A-55-144250, JP-A-56-119132, JP-A-56-22437 and the like. Arylamine derivatives, h) amino-substituted chalcone derivatives described in U.S. Pat. No. 3,526,501, i) N described in U.S. Pat. No. 3,542,546, etc.
N-bicarbazyl derivative, j) Oxazole derivative described in US Pat. No. 3,257,203, k) Styrylanthracene derivative described in JP-A-56-46234, l) JP-A-54-110837 Fluorenone derivatives described in the publications, m) US Pat. No. 3,717,462, JP-A-54-
59143 (corresponding to US Pat. No. 4,150,987),
55-52063, 55-52064, 55
-46760, 55-85495, 57-11.
No. 350, No. 57-148749, No. 57-1041
44, etc., n) US Patent Nos. 4047948 and 4047949.
No. 4265990, No. 4273846, No. 42
Benzidine derivatives described in JP-A-99897 and JP-A-4306008, o) JP-A-58-190953 and 59-95540.
No. 59-97148, 59-195658,
Stilbene derivatives described in JP-B No. 62-36674, p) polyvinylcarbazole and derivatives thereof described in JP-B-34-10966, and q) JP-B-43-18674 and 43-19192. A vinyl polymer such as the polyvinylvinylene, polyvinylanthracene, poly-2-vinyl-4- (4'-dimethylaminophenyl) -5-phenyloxazole, poly-3-vinyl-N-ethylcarbazol, etc., r) polymers such as polyacenaphthylene, polyindene, and acenaphthylene / styrene copolymers described in JP-B-43-19193, etc. s) pyrene described in JP-B-56-13940, etc.
Condensation resins such as formaldehyde resin and ethylcarbazol / formaldehyde resin, t) JP-A-56-90883 and 56-161550.
And various triphenylmethane polymers described in Japanese Patent Publication No. 397086 and U.S. Pat. No. 4,666,802.
No. 4, Japanese Patent Publication No. 49-4338, No. 49-17535,
JP-A-64-2061, JP-A-64-4389, JP-A-1-144057, JP-A 1-153757, and JP-A 1-2.
No. 17362, No. 1-2221459, No. 1-2529
No. 67, No. 1-285952, No. 1-312551.
No. 2-8256, No. 2-16570, etc., and metal-free or metal phthalocyanines and naphthalocyanines, and derivatives thereof.

The photoconductive compound used in the electrophotographic lithographic printing plate relating to the treatment of the present invention is not limited to the compounds listed in a) to u), but may be any of the known photoconductive compounds and, if desired, 2 Although more than one kind can be mixed and used, a metal-free or metal phthalocyanine pigment having photoconductivity is advantageously used in the electrophotographic lithographic printing plate photoconductive layer used in the present invention.

As the metal phthalocyanine, the central metal of the phthalocyanine ring is lysium, beryllium, sodium, magnesium, aluminum, potassium, calcium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, molybdenum, ruthenium,
Rhodium, palladium, silver, cadmium, indium,
Tin, antimony, barium, hafnium, osmium,
Platinum, mercury, lead, and the like, and complex salts in which oxygen or halogen is axially coordinated with these metals are known, and metal-free phthalocyanines are those containing hydrogen in place of those metals. Also, for the purpose of improving electrophotographic characteristics and dispersibility,
Hydrogen on the benzene ring in the phthalocyanine molecule is halogen,
Cyano group, nitro group, carboxyl group, sulfonic acid group,
Alkoxy group, alkylamino group, alkylamido group,
Derivatives substituted with a substituted or unsubstituted aliphatic or aromatic group are also known. Furthermore, the existence of various different crystal forms is known by measuring the X-ray crystal diffraction of these phthalocyanines.

In the electrophotographic lithographic printing plate photoconductive layer used in the present invention, among these, α type, β type, γ type, π type, τ type,
Metal-free phthalocyanines such as χ type and ε type, α type, β
Type, γ type, ε type, and η type copper phthalocyanine, α
Type, β-type titanyl phthalocyanine, and metal phthalocyanine such as halogenoaluminum phthalocyanine are preferable, and they have excellent photosensitivity even in a long wavelength region corresponding to a light source such as He-Ne laser and semiconductor laser. Χ type metal-free phthalocyanine and titanyl phthalocyanine are more preferable.

A binder resin is further used in combination with the photoconductive layer of the electrophotographic printing plate used in the treatment of the present invention. When used as a printing plate, it is necessary to finally remove the photoconductive layer other than the image area. This step is a relative relationship between the solubility of the photoconductive layer in the eluate and the resist property of the toner in the eluate. Although it cannot be unconditionally expressed because it is determined by the above, the binder resin is preferably a polymer compound that is soluble or dispersible in the eluent described below. Specific examples of the binder resin include a styrene / maleic anhydride copolymer, a styrene / maleic acid monoalkyl ester copolymer, a methacrylic acid / methacrylic acid ester copolymer, a styrene / methacrylic acid / methacrylic acid ester copolymer. , Acrylic acid / methacrylic acid ester copolymer, styrene / acrylic acid / methacrylic acid ester copolymer, vinyl acetate / crotonic acid copolymer,
Styrene such as vinyl acetate / crotonic acid / methacrylic acid ester copolymer, methacrylic acid ester, acrylic acid ester, vinyl acetate, vinyl benzoate, etc. and acrylic acid,
Methacrylic acid, itaconic acid, crotonic acid, maleic acid,
Copolymers with carboxylic acid-containing monomers such as maleic anhydride and fumaric acid, or copolymers with acid anhydride group-containing monomers, methacrylic acid amide, vinylpyrrolidone, phenolic hydroxyl group, sulfonic acid group, sulfonamide group, sulfonimide group A copolymer containing a monomer having a group, a phenol resin, a partially saponified vinyl acetate resin, a xylene resin, a polyvinyl butyra
Vinyl acetal resins such as vinyl alcohol.

Among these binder resins, a monomer-containing copolymer having an acid anhydride group or a carboxylic acid group and a phenol resin are used as a photoconductive layer for an electrophotographic printing plate. And therefore can be used to advantage.
As the monomer-containing copolymer having an acid anhydride group, a copolymer of styrene and maleic anhydride is preferable. Examples of the monomer-containing copolymer having a carboxylic acid group include a copolymer of styrene and maleic acid monoester, and a copolymer of acrylic acid or methacrylic acid and an alkyl ester, aryl ester or aralkyl ester of two or more thereof. Polymers are preferred. Vinyl acetate and crotonic acid are also preferable. Among the phenol resins, particularly preferable are phenol, o-cresol, m-cresol, and p-cresol.
A novolak resin obtained by condensing a resin with methanol or ethanol under acidic conditions can be mentioned. The binder resin may be used alone or in combination of two or more kinds.

The mixing ratio of the photoconductive compound and the binder resin in the photoconductive layer of the electrophotographic lithographic printing plate used in the treatment of the present invention satisfies various characteristics such as desired electrophotographic characteristics and plate-making characteristics. However, in general, when the content of the photoconductive compound is small, the sensitivity becomes low.
It is 5 parts by weight or more, more preferably 1 part by weight.
It is preferable to mix and use 5 parts by weight or more. However, the use of 40 parts by weight or more is usually not desirable because the liquid properties such as dispersibility, coating liquid stability and coating property and further improvement of electrophotographic properties cannot be expected. If the thickness of the photoconductive layer is thin, the electric charge necessary for toner development cannot be charged and induces fog due to leak. Conversely, if it is thick, not only accelerates the deterioration of the eluate but also causes side etching during elution. Since it is not possible to obtain good image reproducibility by attracting,
[mu] m is more preferably 0.50 to 10 [mu] m, and even more preferably 1.5 to 6.0 [mu] m.

The electrophotographic lithographic printing plate used in the treatment of the present invention can be obtained by coating a photoconductive layer on a conductive support according to a conventional method. In producing the photoconductive layer, a method of containing the components constituting the photoconductive layer in the same layer, or a method of separately containing two or more layers, for example, the lower layer (support side) is easy to dissolve, A method in which a strongly adhesive binder resin is arranged and a resin having good chargeability and ink acceptability is arranged in the upper layer, or the content of the organic photoconductive compound is increased, etc., and the layers are separated and used. Etc. are known and can be produced by any method. The coating liquid is prepared by dissolving and dispersing each component constituting the photoconductive layer in an appropriate solvent. When the organic photoconductive compound uses a component insoluble in the solvent such as phthalocyanine, a ball mill, An average particle size of 0.4 μm or less, more preferably 0.2 μm or less, is used by dispersing with a disperser such as Dynomill, Attritor or Paint shaker. Further, in the photoconductive layer, if necessary, in addition to the organic photoconductive compound and the binder resin, the flexibility of the photoconductive layer, a plasticizer, a surfactant, for the purpose of improving film physical properties such as coating surface state, Other additives can be added. The additives used in the photoconductive layer can be added during or after the dispersion of the organic photoconductive compound.

The coating solution thus prepared is spin coated,
A known method such as blade coating, knife coating, reverse roll coating, dip coating, rod bar coating, spray coating or extrusion coating is applied on a support and dried to obtain an electrophotographic lithographic printing plate. You can Solvents for the coating liquid include halogenated hydrocarbons such as dichloromethane and dichloroethane, alcohols such as methanol, ethanol, 2-propanol, 1-butanol, propanediol and butanediol. Ketones such as acetone, acetone, 2-butanone and cyclohexanone, 2-methoxyethanol,
2-methoxyethyl acetate, 2-ethoxyethyl acetate, glycol ethers such as 2- (2-ethoxyethoxy) ethanol, cyclic ethers such as oxolane, oxane and dioxane, formic acid Examples thereof include esters such as methyl, ethyl acetate, propyl acetate, butyl acetate and ethyl lactate. The concentration (or viscosity) of the coating liquid, the solvent to be used and the mixing ratio thereof are appropriately selected depending on the coating method and the drying conditions.

On the photoconductive layer, for the purpose of improving electrostatic characteristics, developing characteristics at toner development, or image characteristics, an overcoat layer which can be dissolved at the time of alkali elution removal may be provided. The overcoat layer may be a mechanically matted layer or a resin layer containing a matting agent. Known inorganic and organic fine particles can be used as the matting agent.

The electrophotographic lithographic printing plate used in the present invention can form a toner image by a known operation. That is, it is charged substantially uniformly in a dark place, an electrostatic latent image is formed by imagewise exposure, and then toner development is performed. As the exposure method, a reflection image exposure using a xenon lamp, a tungsten lamp, a fluorescent lamp or the like as a light source, a contact exposure through a transparent positive film, a laser light, a light emitting diode
Scanning exposure by means of scanning and the like. The light source in the scanning exposure is a He-Ne laser, an argon ion laser, a krypton ion laser, a ruby laser, a YAG laser, a nitrogen laser, a dye laser, and an excimer. Laser, GaAs
/ GaAlAs, laser sources such as semiconductor lasers such as InGaAsP can be used, or scanning exposure using a light emitting diode or liquid crystal shutter (light emitting diode array,
(A line printer type light source using a liquid crystal shutter array or the like is also included).

Next, the electrostatic latent image is developed with a toner. As a developing method, any of a dry developing method (cascade developing, magnetic brush developing, powder cloud developing) and liquid developing can be used. In particular, the liquid development method can form a toner fine image and is suitable for producing a printing plate having good reproducibility. Further, positive / positive development by positive development and negative / positive development by reversal development under application of an appropriate bias voltage are possible. However, in the present invention, the advantage of scanning exposure is utilized, and therefore image development is performed in the image exposure section. Toner development is performed by reversal development.
The formed toner image can be fixed by a known fixing method such as heat fixing, pressure fixing, solvent fixing and the like. The toner image thus formed is used as a resist to remove the non-image area photoconductive layer with an eluent to prepare a printing plate.

Toner used for developing electrophotographic lithographic printing plate
Needs to contain at least a resin component having resist properties with respect to the following eluate. Examples of the resin component include acrylic resins made of methacrylic acid and esters of methacrylic acid and the like, vinyl acetate resins, copolymers of vinyl acetate and ethylene or vinyl chloride, vinylidene chloride resins, vinyl chloride resins, polyvinyl butyra- Vinyl acetate resin such as polystyrene, polystyrene, copolymer of styrene and butadiene, methacrylic acid ester, etc., polyethylene, polypropylene and its chloride, polyester resin such as polyethylene terephthalate, polyamide resin such as polycapramide, phenol Resin, xylene resin,
Examples thereof include alkyd resin, vinyl-modified alkyd resin, and other waxes. Further, the toner may contain a dye or a charge control agent within a range that does not adversely affect development or fixing.

The electrophotographic lithographic printing plate after completion of toner development is then eluted with a non-image area photoconductive layer with an alkaline eluent, followed by washing with a washing liquid to wash the plate surface, and then usually with a protective gum treatment. To be done.

The eluent according to the present invention is preferably an aqueous solution containing an alkaline agent and having a buffering capacity near the pH of the eluate. As the alkaline agent to be contained,
General formula SiO ₂ / M ₂ O (M represents an alkali metal atom)
Inorganic alkali agents such as silicates, alkali metal hydroxides, alkali metal and ammonium salts of phosphoric acid and carbonic acid, organic amine agents such as ethanolamines, ethylenediamine, propanediamines, triethylenetetramine and morpholine , And mixtures thereof can be used, but since the above-mentioned silicates in particular exhibit a suitable alkaline strength and a strong buffering capacity at high pH, silicates are advantageously used.

The eluent according to the present invention is further described in Japanese Patent Application Laid-Open No.
Ionic compounds described in JP-A No. 5-25100, JP-A-SHO-5
5-95946, water-soluble cationic polymers, JP-A-56-142528, water-soluble amphoteric polymer electrolytes, JP-A-58-75152, neutral salts, JP-A-58-190952. Chelating agents described in JP-A No. 1-177541, liquid viscosity modifiers described in JP-A-1-177541, preservatives and bactericides described in JP-A-63-226657, various surfactants, natural and synthetic water-soluble agents. Known components such as a polymer can be contained as necessary.

The solvent in the eluate is not particularly limited as long as it can stably disperse and dissolve the above components, but soft water is more preferable, and ion-exchanged water is advantageously used. In addition, in a solution containing the eluent composition excluding the alkaline agent, in order to more stably mix and disperse the above components in an amount such that elution does not occur substantially, the minimum amount of organic solvent along with the eluent active ingredient is used. You may add and contain a solvent.

The preferred properties of the silicate used in the preparation of the eluate according to the present invention are SiO ₂ / M ₂ O = 0.5-4.0 (on a molar basis), more preferably 1.0-3.0. A range is preferred.
When preparing the eluate, it is desirable to add an appropriate amount of alkali metal hydroxide to adjust the pH of the solution appropriately. Alkali metal oxide (M ₂ ) relative to the amount of silicic acid (SiO ₂ ) in the eluate
The final molar ratio of the total amount of (O) (SiO ₂ / M ₂ O) is 1.
The range of 0 to 2.6 is preferable, and 1.3 to 2.2 is more preferable. Further, the concentration of the alkaline agent in the eluate is one of the main factors that determine the elution rate, but in the present invention, it is 1 to 20.
%, More preferably 2 to 10% by weight, further preferably 3 to 8% by weight. The pH of the eluate is 11.8-
It is preferably 13.5, more preferably 12.0 to 13.0, and it is desirable to add a desired replenisher solution in a timely manner to improve the elution activity in the case of multi-plate printing.

If the elution time, that is, the time from the contact of the eluate with the photoconductive layer to the removal thereof is short, it causes elution failure and scumming during printing, and if it is long, the image line becomes thin and elutes. This causes excessive inflow of the photoconductive layer into the liquid. The elution time is specified by the eluate formulation, etc., but is in the range of 2 to 15 seconds,
More preferably, it is carried out for 3 to 10 seconds.

The washing process must be able to quickly completely remove the solubilized photoconductive layer remaining on the plate and the eluate with the washing solution. The liquid may be directly supplied to the solubilized photoconductive layer as long as it has a mechanism capable of suppressing scattering.
The elution promoting member described in JP-A-27038 may be applied to a water washing mechanism. In the water washing treatment, the solubilized photoconductive layer can be scraped off by directly contacting a rotating brush with the photoconductive layer, but the solubilized photoconductive layer is usually removed without mechanical scraping. Its use is not desirable because it can be easily removed and it may accelerate the deterioration of side etching. The washing liquid used in the treatment method of the present invention may be a disposable type or a circulation reuse type, or other types can be used if desired.

The electrophotographic lithographic printing plate from which the non-image area photoconductive layer is removed is treated with a protective gum for the purpose of improving scratch resistance of the plate surface and desensitizing the non-image area. The protective gum solution that can be used in the present invention includes a polymer compound, a lipophilic substance,
Known agents can be used for all of these reagents, including surfactants and the like.

[0063]

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 as long as the gist thereof is not exceeded. Further, the weight applied to the plate with respect to the effective measuring width of the liquid measuring instrument according to the present invention will be hereinafter referred to as measuring weight.

Example 1 [Preparation of electrophotographic lithographic printing plate precursor] JIS 1050 aluminum (0.3 mm thickness) was immersed in a 10% sodium hydroxide aqueous solution at 60 ° C. so that the amount of aluminum dissolved was 6 g / m ² . Etched. After washing with water, it was immersed in a 30% nitric acid aqueous 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, followed by washing with water and drying to prepare a printing plate support.

On the surface-treated surface of this support, the following photoconductive composition dispersed 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 The film was dried at 3 ° C for 3 minutes to prepare an electrophotographic lithographic printing plate precursor.

Photoconductive layer coating liquid composition Butyl methacrylate / butyl acrylate / methacrylic acid copolymer (monomer weight ratio 1: 1: 1, molecular weight 15,000) 6.5 parts by weight χ type nothing Metal phthalocyanine (Fastogen Blue 8120, manufactured by Dainippon Ink and Chemicals, Inc.) 1.5 parts by weight 1,4-dioxane 70 parts by weight 1-butyl acetate 12 parts by weight 2-propanol 10 parts by weight

[Toner development] The obtained printing plate precursor was charged in a dark place by a corotron so that the surface potential became about +300 V, and then scanning image exposure was performed using a semiconductor laser (780 nm), and immediately. Positive charge toner (manufactured by Mitsubishi Paper Mills,
Liquid reversal development was performed with LOM-ED 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.

The toner-developed printing plate described above was subjected to a plate making process using the following processing apparatus, eluate, washing solution and protective gum solution. The elution time was adjusted from the relationship between the plate conveyance speed and the solubilization of the photoconductive layer immediately after the liquid metering section was carried out.

[Electrophotographic planographic printing plate processing apparatus] FIG. 1 shows the electrophotographic planographic printing plate processing apparatus used in this embodiment. The basic constitution of this processing apparatus consists of four zones, eluate coating zone A, solubilized photoconductive layer removing waste zone B, water washing zone C, and protective gum solution coating zone D. The printing plate is nipped by a roll and automatically conveyed.

The eluate application zone A further comprises an eluate supply pipe 27, a liquid rectifying plate 28, and an eluate supply part comprising a liquid supply roll 11a, a liquid measuring member 47 and a guide roll 13. The liquid metering section and the photoconductive layer-solubilizing section having the effect of substantially solubilizing the non-image area photoconductive layer therebetween. For the liquid measuring tool 47, a SUS304 round bar whose surface has been polished is used as the rotating shaft 51, and a diameter of 250
Effective measuring length of stainless wire 50 of μm is 760m
A wire bar densely wound in a spiral shape so as to have a length of m was used. The wire bar pressurizes the plate only by its own weight, and the weight is adjusted by the outer diameter of the round bar, and the rotation is transmitted by contact with the plate to be conveyed during liquid measurement. The surplus eluate measured by the eluate metering section flows on the tray 75 installed above the circulating eluent storage tank 3 and flows through the hole 78 to the circulating eluate storage tank 3.
The replenishing solution is collected and replenished from the replenishing solution storage tank 7 through the replenishing pump 94, the valve 100, and the elution replenishing solution supply pipe 54, and is supplied for circulation together with the elution replenishing solution corresponding to the amount of the eluate replenishing solution carried out.

The waste zone B for removing the solubilized photoconductive layer includes a rubber blade 22, a metal guide roller 20, and a guide roller.
And a cleaning blade 23. The liquid scraped off by the rubber blade 22 is temporarily stored in the removal waste liquid primary storage tank 4 and is discarded via the pipe 114 by opening the valve 104 arranged below the connecting pipe 90. It The rubber material of the rubber blade 22 has a rubber hardness of 65.
5mm nitrile butadiene rubber is used, effective elastic length 15mm, contact width with metal guide roller 20 2mm
The pressure is adjusted so that

[Plate-making treatment liquid] 1) Eluent composition (circulation eluate storage tank 3 input: 30 dm ³ ) Potassium silicate aqueous solution (SiO ₂ min 30% by weight, SiO ₂ / K ₂ O molar ratio 3.0) ) 10.0 parts by weight Sodium hydroxide 0.8 parts by weight Pure water 89.2 parts by weight

2) Composition of eluent replenisher (replenisher tank 7: 20 dm ³ ) Sodium silicate aqueous solution (SiO ₂ content 30% by weight, SiO ₂ / Na ₂ O molar ratio 3.0) 10.0 parts by weight Potassium hydroxide 1.7 parts by weight Pure water 88.3 parts by weight

3) Washing liquid composition (circulating washing liquid storage tank 5 input: 30 dm ³ ) Ammonium hydrogen carbonate 0.35 parts by weight Sodium dioctyl sulfosuccinate 0.10 parts by weight 2-methyl-3-isothiazolone 0.1 01 parts by weight Pure water 99.54 parts by weight

4) Composition of protective gum solution (gum solution storage tank 8 input: 10 dm ³ ) gum arabic 10% by weight aqueous solution 50 parts by weight phosphoric acid (85% aqueous solution) 1 part by weight sodium nitrate 1 part by weight ethylenediaminetetra (methylene) Phosphonic acid) 0.5 parts by weight Citric acid 0.25 parts by weight Decaglyceryl monolaurate 0.1 parts by weight 2-Methyl-3-isothiazolone 0.01 parts by weight Sodium hydroxide is added to this to obtain a liquid pH. After adjusting to 4.3, prepare 100 parts by weight with pure water.

[Plate-making process and evaluation] Using the above-mentioned processing apparatus, processing liquid, and wire bar shown in Table 1, a conveying speed of 4 was obtained.
The 50th plate was eluted at m / min. The size (length x width) of the plate used for the treatment is 660 mm x 485 mm. The plate obtained by processing was calculated and evaluated for the following two items. (1) Liquid measurement residual liquid amount The average of the weight difference between before plate making and immediately after the measurement of the eluate is converted into a unit processing area. (2) Ability to suppress solubilized photoconductive layer peeling The degree of solubilized photoconductive layer peeling by sliding the plate surface of the liquid measuring tool was evaluated by coloring the plate surface after the liquid measurement and the circulating eluate.
The obtained results are shown in Table 1. The vertical plate and the horizontal plate in the liquid residual liquid are defined as the plate edges corresponding to the plate size display (vertical x horizontal).

[0077]

[Table 1]

As is clear from Table 1, the weighing weight is 0.49.
In the case of less than kg / m (liquid metering numbers 1 and 2; outside of the present invention), at least as compared with the case in which it is 0.77 kg / m or more, the plate to be processed with a large amount of liquid remaining liquid as a whole. The difference in the residual liquid measurement amount due to the size (conveyance plate width) also became large, which deteriorated the measurement accuracy and caused the unnecessary waste liquid amount and the elution replenishing liquid amount to increase. In addition, since the liquid measuring tool is light, it does not make uniform contact over the entire plate width direction, and because the peripheral speed does not coincide with the transport speed, partial peeling of the solubilized photoconductive layer is induced and circulation occurs. The eluate was polluted faster.

On the other hand, when the weighing load is increased, the influence of the plate size on the residual liquid amount is weakened and at the same time the weighing accuracy is improved, but the photoconductive layer component layer which is swollen and solubilized by the eluent to become a highly viscous liquid There was a tendency that the wire traces of the wire bar of the liquid measuring tool tended to be attached. Weighing load is 4.21 kg / m
In the case of the above (liquid metering numbers 7 and 8; outside of the present invention), not only the coloring of the circulating liquid due to the mixing of the photoconductive layer component into the eluate removed from the plate by the liquid metering tool was the fastest, but especially the weighing load. When the value was 4.92 kg / m, wire streaks were partially generated during the plate making, which sometimes resulted in stains during printing.

When these four printing plates were printed by an offset printing machine (Ryobi 3200 MCD), the four printing plates did not cause soiling in the normal printing, but the printing plate after the normal printing was 90 ° C. In the forced printing stain test in which printing was restarted after heating for 1 hour, the printing plate stain was generated on the 1000th printing plate. Therefore, in order to know the practical limit of the plate-making process, we conducted a forced printing stain test retroactively,
At the latest, at the 800th plate making, a slight background stain was generated, and at least the eluate had to be replaced.

Contrary to these, the weighing weight is at least 0.
In the range of 77 to 3.59 kg / m (liquid measurement number 3 to 6;
According to the present invention, the results of satisfying both the ability of suppressing the separation of the solubilized photoconductive layer component by the liquid measuring tool and the measuring accuracy are obtained. Plate making (longitudinal plate) was continued for the liquid measurement number 4 and a total of 1000 plates were made, but no elution failure was found for all of the plates. Further, when the side etch of the 100th plate, the 500th plate, and the 1000th plate of the plate-making start was measured, there was almost no change between the plate-making products. Next, when the prepressed printing plate used for the side etch measurement was printed with an offset printing machine (Ryobi 3200 MCD),
Also in the forced printing stain test, good printed matter was obtained without generation of background stains on the three sheets. The eluate after the 1000th plate had a slight transparency but had a considerable degree of transparency.
There was also a slight drop in pH. In addition, the amount of waste liquid in the solubilized photoconductive layer-removed portion after the 1000th plate was about 17 dm ³ .

Example 2 Instead of the liquid measuring tool used in Example 1, the rotating shaft has an outer diameter of 1
A wire bar in which a 250 μm diameter stainless steel wire is spirally and densely wound around a SUS decorative tube having a thickness of 3 mm and a thickness of 1 mm.
(Liquid weighing device weight 0.33 kg, weighing load 0.43 kg /
m) is mounted on the SUS round bar (weight 0.83k), which is in contact with only the effective weighing unit to adjust the weighing load.
g, total weighing weight 1.53 kg / m) to uniformly pressurize the effective measuring portion of the liquid measuring tool, the same plate making apparatus, processing liquid, and toner-developed electrophotography as in Example 1. Plate-making processing was performed using the planographic printing plate. As a result of making the 1000th plate, rubbing and peeling of the solubilized photoconductive layer hardly changed, and the printability did not cause any problems as in Example 1. The liquid measurement residual liquid was 52 g / m ² . Next, when the above SUS round bar was removed from the liquid measuring tool and plate making was performed in the same manner, the solubilized photoconductive layer was scraped and peeled off although the liquid measuring residual liquid increased to 56 g / m ^2. , The eluate was contaminated.

Example 3 In place of the wire bar used in Example 1, a nitrile butadiene rubber measuring roll (diameter was coated with a rubber having a hollow rubber-coated portion with a rubber hardness of 35 degrees) was used. 40
mm, weighing load 3.15 kg / m). The metering roll transmits the drive directly to its rotating shaft,
It does not pressurize with the pressure roll etc. used in the above, but the guide roll 13 and the measuring roll come into contact with each other by their own weight and rotate.

Further, the eluate and the eluent replenisher were used by exchanging with the liquids having the following formulations. 1) Eluent composition (circulation eluate storage tank 3 input: 30 dm ³ ) Aqueous sodium silicate solution (SiO ₂ content 30% by weight, SiO ₂ / Na ₂ O molar ratio 3.0) 33.0 parts by weight potassium hydroxide 2.0 parts by weight Pure water 65.0 parts by weight

2) Composition of eluent replenisher (the amount of eluent replenisher tank 7: 20 dm ³ ) Aqueous sodium silicate solution (SiO ₂ content 30% by weight, SiO ₂ / Na ₂ O molar ratio 3.0) 33.0 weight Part Potassium hydroxide 2.3 parts by weight Pure water 64.7 parts by weight

Using the above liquid measuring tools and the respective processing liquids, plate making was carried out under the processing conditions of an eluate discharge rate of 5.5 dm ³ / min and a conveying speed of 2 m / min, and the measured residual liquid amount was 36 g / m ² . there were. Under the same conditions, the 1000th plate was made, and the 10th plate was started.
When the 200th, 500th, and 1000th plate-making products were observed, there was no elution defect in all, and side etching did not change within the same plate, and it hardly changed between plate-making products. Next, offset printing machine (Ryobi)
When these printing plates were printed using a 3200 MCD), good printed matter was obtained without the occurrence of scumming. 10
The effluent after the 00 plate was hardly dyed, no insoluble matter was generated, and the drop in pH was slight. Also, 100
The amount of waste liquid in the solubilized photoconductive layer-removed portion after plate-making was about 11 dm ³ . After making the 2000 plate, plate making is continued under the same conditions except that the elution replenisher is replenished in the liquid storage tank 7.
A total of 3000 plates were prepared without exchanging the treatment liquid, but the plate could be prepared without any problems in terms of elution property and printability.

[0087]

As described above, when an electrophotographic lithographic printing plate is processed by the electrophotographic lithographic printing plate processing method of the present invention, it is possible to prevent the poor dissolution of a residual film while suppressing the thinning of the image line during the dissolution. The entire plate surface can be uniformly eluted, and the deterioration of the liquid property due to the inclusion of the solubilized photoconductive layer in the eluent is suppressed to enable stable elution processing over a long period of time. The amount of remaining liquid after measurement and the frequency of liquid exchange are greatly reduced, and the burden of waste liquid and maintenance management is reduced.
It has an excellent effect.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of a processing apparatus used for carrying out the electrophotographic lithographic printing plate processing method of the present invention.

[Explanation of symbols]

 A Eluent coating zone B Solubilized photoconductive layer removal waste zone C Water washing zone D Protective gum solution coating zone 1 Electrophotographic planographic printing plate 3 Circulating eluate storage tank 7 Replenisher storage tank 13 Guide Roll 12, 17, 18 Transport Guide Roll 20 Metal Guide Roll 22 Rubber Blade 47 Liquid Measuring Tool

Claims (1)

[Claims] 1. A toner image is formed on a lithographic printing plate precursor having a photoconductive layer provided on a conductive support by an electrophotographic method, and then an eluate is excessively supplied to the lithographic printing plate photoconductive layer surface. After solubilizing the non-image area photoconductive layer, the amount of excess eluate is quantitatively measured with a rotatable liquid measuring tool, and the solubilized photoconductive layer is removed after the transportation of the electrophotographic planographic printing plate. 2. The method for treating an electrophotographic lithographic printing plate as described above, wherein the weight applied to the plate with respect to the effective measuring width of the liquid measuring tool is 0.5 to 4.0 kg / m.