JPH0749574A - Processing method of waste liquid from planographic printing plate treatment - Google Patents

Abstract

PURPOSE:To provide a processing method for waste liquid as a byproduct of planographic printing process by which waste liquid can be easily processed and the burden concerning to processing of waste liquid is decreased without using such a method that an acid material is newly added to waste liquid to decrease pH of the liquid when the liquid is to be discharged. CONSTITUTION:After an alkali treating liquid is supplied to the image forming surface of a planographic printing plate to dissolve a nonpicture part, the alkali treating liquid on the plate and the dissolved nonpicture part are removed and discharged. In the processing method of the waste liquid in the planographic printing process, a gas containing at least carbon dioxide is blown into the waste liquid comprising the alkali treating liquid and the nonpicture part.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention provides a printing plate by supplying an alkaline processing liquid to the image forming surface of a lithographic printing plate to dissolve the non-image part and then removing the non-image part components from the printing plate. Regarding processing method of processing waste solution consisting of processing fatigue alkaline processing solution and non-image part component which is by-produced when processing, processing waste solution is processed easily and safely without lowering the pH of the solution again when discarding highly alkaline processing waste solution The present invention relates to a lithographic printing plate processing waste liquid processing method capable of significantly reducing the processing waste liquid processing load.

[0002]

2. Description of the Related Art A non-image area alkali dissolution removing type lithographic printing plate contains an actinic ray-inducing treatment liquid solubilizing substance or an actinic ray curable substance accompanied by a chemical structure change by actinic rays on a hydrophilic support. A photosensitive lithographic printing plate (so-called PS plate) provided with a photosensitive layer is known and is widely used for heavy printing that requires high printing durability. These are exposed to a silver salt photographic film original plate on which an image has been recorded in advance, in close contact with the printing plate image forming surface, whereby a treatment liquid corresponding to a cured portion or a non-image portion corresponding to the image portion in the final printed matter. A solubilized portion is formed, and a non-image portion is dissolved and removed by an alkaline processing liquid.

Further, an electrophotographic lithographic printing plate which forms an image by utilizing an electrophotographic technique is also known, and a printing plate compatible with scanning exposure is also manufactured. The non-image area alkali-removing lithographic printing plate utilizing electrophotographic technology comprises an ink-receptive photoconductive layer in which an organic photoconductive substance is generally dispersed in a resin on a hydrophilic support. After forming a toner image on the photoconductive layer by the method, the toner is used as a resist and the non-image portion is subjected to an elution treatment with an eluate containing an alkaline agent to be used as a printing plate.

The plate-making process of these non-image area alkali-eluting type lithographic printing plates is generally carried out by using an automatic machine for automatically supplying the processing liquid while carrying the printing plate.
As a processing method adopted in the automatic machine, a liquid circulation reuse method, a new liquid disposal processing method, a processing step measurement residual liquid disposal method and the like are known.

The liquid circulation / reuse system is a system in which an excessive amount of the processing liquid is brought into contact with the printing plate, all the processed liquid is removed from the plate, and then the liquid is circulated and reused. Alternatively, in addition to supplying from a shower or the like, there is a method of immersing the printing plate in a treatment liquid tank in a curved manner (dip method).
The new liquid waste disposal method supplies the new liquid for each plate by adjusting the gap of the liquid supply slit and the wire diameter of the wire bar to pre-measure the required minimum amount before supplying the processing liquid to the plate surface. This is a method in which after the treatment promoting means is applied in the treatment process as the case may be, the treated fatigue treatment liquid is removed and discarded together with the solubilized non-image portion. In the process process metering residual liquid disposal method, after supplying an excessive amount of processing liquid to the plate once, the processing liquid is metered to a certain amount during processing and the excess liquid is circulated and reused, and the processing liquid on the plate after weighing is measured. Is a method of discarding together with the solubilized non-image portion after the processing is completed.

The problems common to all of these processing methods are stabilization of plate-making processing, suppression of generation of processing waste liquid, reduction of maintenance management of processing liquid and equipment such as prolongation of liquid exchange cycle. Particularly from the user's point of view, stabilization of the plate-making process caused by the apparatus is a major premise, and reduction in maintenance of the processing liquid and the apparatus determines the performance in actual use in the processing apparatus. In other words, stabilization of the plate-making process is basically stabilization of the activity of the processing solution.In general, components other than the throw-away method are replenished with the components consumed by the process, while the components that increase in concentration during the process are removed. A means for removing and maintaining the components of the treatment liquid constant is adopted, the replenisher is replenished, a part of the treatment liquid is discarded to remove the high-concentration component, and the treatment performance of the treatment liquid is improved. This is because all used processing liquids are discarded when they are out of the allowable limit or when they are discarded.

By the way, since the liquid exchange and the cleaning of the processing liquid tank are usually work steps which are manually performed on a regular basis, the processing apparatus may have a structure and system which can be completed more simply and in a shorter time. Required. In particular, when disposing of the processing waste liquid that accompanies liquid exchange, etc., in order to not only improve workability but also extend the processing liquid exchange period, at least a portion of the fatigue processing liquid generated by the plate making process should be discarded along with the plate making. A method of directly storing in a waste liquid container attached to the device is adopted. In particular, the alkaline treatment liquid used for dissolving and removing the non-image area has a considerably high pH, and accompanying this, the treatment waste liquid also has a considerable liquid pH, so that it can be compared with the waste treatment method. Even if a waste liquid processing company is requested to process this waste liquid, the liquid pH must be adjusted within a specific range.

[0008]

DISCLOSURE OF THE INVENTION According to the present invention, an alkaline processing liquid is supplied to the image forming surface of a lithographic printing plate to dissolve the non-image area, and then the alkaline processing liquid on the printing plate and the dissolved non-image area are separated. Provided is a method for treating a processing liquid waste that accompanies plate-making processing of a planographic printing plate to be removed and discarded, and a method for treating a processing liquid waste of a planographic printing plate that reduces management of the processing liquid waste to be discarded in the plate-making processing. It is in. More specifically, when draining a highly alkaline processing waste liquid, it is possible to easily and safely process the processing waste liquid without lowering the liquid pH anew, and to significantly reduce the processing load of the processing waste liquid. To provide a method.

[0009]

As a result of repeated studies to solve the above problems, an alkaline treatment liquid was supplied to the image forming surface of the lithographic printing plate to dissolve the non-image area, and then the alkaline treatment on the printing plate was performed. A treatment waste liquid treatment method in the plate making process of a lithographic printing plate which removes and discards the liquid and the dissolved non-image portion, wherein at least the waste treatment liquid consisting of the discarded alkaline treatment liquid and non-image portion components It was achieved by a lithographic printing plate processing waste liquid processing method characterized by blowing a gas containing carbon dioxide.

The alkaline processing liquid used for dissolving and removing the non-image area alkaline dissolution type lithographic printing plate generally has a pH of about 13, and the waste liquid containing this processing fatigue solution naturally has a considerably high pH. Become. Due to the revision of the Waste Treatment Law, it is necessary to adjust the pH of the highly alkaline waste liquid below the standard value regardless of whether it is discharged or a waste disposal company is requested to dispose of it.

Therefore, if a method of adding an inorganic and / or organic acid that dissolves in the waste liquid is used in order to lower the pH of the waste liquid, neutralization generally involves a rapid heat generation, and therefore the waste liquid container is made of polyethylene. If they are equal, there is a possibility of thermal deformation. Further, if the alkaline waste liquid or the acid is scattered during the neutralization work, it is not preferable not only from the viewpoint of hygiene but also from the viewpoint of safety. In particular, when an alkali metal silicate represented by the general formula SiO ₂ / M ₂ O is contained as an alkaline agent, there is a high possibility that the entire waste liquid will agglomerate due to a sudden decrease in pH, and the pH of the entire liquid will be the standard value. Before lowering to below, only the vicinity of the acid injection portion in the waste liquid will be aggregated, so it is necessary to add an operation such as stirring.

In that respect, if a gas containing at least carbon dioxide is blown into the processing waste liquid consisting of the discarded alkaline processing liquid and the dissolved non-image part components, carbon dioxide will be an aqueous liquid, especially an alkali. It is easily dissolved in the solution, and the pH of the treated waste liquid can sufficiently reach the standard value or lower without adding acid again when the waste liquid is discarded. Further, since carbonate has a buffering action in the weak alkaline region, even if the alkali metal silicate is contained as the alkaline treatment liquid component, the possibility of causing aggregation is obviously reduced. Therefore, the treatment (request) can be performed without any action at the time of discarding the waste liquid, if only means for preventing the dispersion of the treatment liquid during the blowing of carbon dioxide is taken.

A method of supplying a gas containing at least carbon dioxide and a processing waste liquid according to the processing method of the present invention will be described below. The gas containing at least carbon dioxide according to the present invention supplies the alkaline processing liquid to the image-formed lithographic printing plate to dissolve the non-image portion, and then the alkaline processing liquid on the printing plate and the dissolved non-image portion are separated. It is supplied to the processing waste liquid that has been removed and discarded. The gas blown into the waste liquid may contain at least carbon dioxide, so high concentration carbon dioxide may be supplied from a carbon dioxide source such as dry ice or a carbon dioxide high pressure cylinder, but in normal air Air can be used as the carbon dioxide-containing gas because the pH of the treatment waste liquid can be sufficiently lowered below the reference value even with the concentration of carbon dioxide contained.

The supply of the gas containing at least carbon dioxide in the processing method of the present invention is performed by blowing a carbon dioxide-containing gas containing air into the processing waste liquid. If the carbon dioxide source is air, blow it using a compressor, air pump, or the like. Also, if it is dry ice, it may be put directly into the waste liquid, but since a large amount of carbon dioxide gas is generated at one time and most of it is not absorbed in the waste liquid, keep the atmosphere at a low temperature and gradually It is vaporized or gradually vaporized in a pressure vessel and gradually supplied into the waste liquid. In order to improve the pH lowering efficiency of the treatment waste liquid in any carbon dioxide source, the gas to be blown should be supplied as fine bubbles in the waste liquid to increase the area of the interface with the liquid of unit gas amount. Is essential. Due to the viscosity of the waste liquid, the finer the bubbles, the slower the rising speed in the liquid and the higher the absorption efficiency. Therefore, air diffuser stones may be used at the tip of the gas blowing port.

The gas supply port according to the present invention may be arranged in a container for storing the processing waste liquid prior to the plate-making process, but at the time of the waste liquid processing (request), the standard pH determined by the waste treatment method is set. As long as it is below the value, the supply of the carbon dioxide-containing gas according to the present invention does not have to start immediately after the start of plate making, and it is sufficient after the processing waste liquid has been stored to some extent. The larger the amount of the stored waste liquid, the longer the contact time of the supply gas with the processing waste liquid, and the more efficiently the liquid pH can be lowered. Therefore, the supply may be started or the supply amount per hour may be changed depending on the amount of waste liquid in the liquid storage tank. Carbon dioxide is absorbed by an alkaline solution and acts as an acid, but it is extremely unlikely that the components in the treatment waste liquid that have acted with carbon dioxide will be harmful substances, and post-treatment after pH reduction will reduce other acids. It does not become complicated compared to the case where it is added.

Next, the processing method of the present invention will be described in detail in the order of plate-making processing steps. The plate-making processing step in the processing method of the present invention comprises at least an alkaline processing solution supplying step and a non-image part removing and discarding step, and a carbon dioxide-containing gas supply for blowing a gas containing at least carbon dioxide into the discarded waste solution. A processing means is attached.

In the alkaline treatment liquid supplying step, the alkaline treatment liquid is excessively supplied to the image forming surface of the lithographic printing plate.
A conventionally known mechanism such as a shower, a slide hopper, a curtain coater, or a dip system can be used as the alkaline processing liquid supply system. Particularly when a shower is used, it is preferable that the liquid discharged from the tube is once rectified through another member, for example, a rectifying plate or a plate conveying roll, and then supplied to the image forming surface. In addition, in all methods, in order to further shorten the processing time and prevent defective liquid supply, a flow promoting mechanism is provided to replace the alkaline processing liquid supplied on the plate, and multiple alkaline processing liquids are used. It is desirable to supply over time.

It is important that the minimum supply amount of the alkaline processing liquid is such that the alkaline processing liquid flows down from the edge of the plate during transportation. That is, a part of the non-image part is dissolved, and the surplus part flows over the plate and flows down from the plate end part while partially replacing the existing alkaline processing liquid in the alkali-treated part. As a result, liquid replacement frequently occurs at the plate edge, and the flow rate of the alkaline processing liquid in the vicinity of the interface of the image forming layer increases, so that intra-plate variation in solubility is suppressed.

The alkaline processing liquid excessively supplied onto the printing plate is conveyed to the non-image area removing and discarding step, but all of the alkaline processing liquid on the plate is not consumed in the dissolution process of the non-image area, Moreover, in the non-image area removal / disposal step, all the liquid material on the plate is removed and discarded.Therefore, during the non-image area removal / disposal step after the dissolution of the non-image area image forming layer, the processing liquid supply step is performed. It is preferable to provide and measure and remove at least a certain amount of the alkaline processing liquid on the plate by the liquid measuring means.

When the liquid measurement is carried out, the alkaline processing liquid which is substantially not involved in the dissolution of the image forming layer is prevented from being mixed on the printing plate at the maximum while preventing the mixing of the non-image portion dissolved during the liquid measurement. It is important to remove. Therefore, if the amount of the alkaline treatment liquid left on the plate after the liquid measurement (liquid measurement residual liquid amount) is large, the consumption of the alkaline treatment liquid inevitably increases and the alkaline treatment efficiency per unit amount of the alkaline treatment liquid decreases. However, it is desirable that the residual amount of the alkaline treatment liquid measured be small, because further dissolution may occur after the liquid measurement until the non-image area removal / disposal step, leading to fine image lines.

However, when the residual amount of the alkaline processing liquid is too small, the viscosity of the removal liquid increases remarkably, and in the continuous plate making, the removal liquid accumulates in the non-image part removal discard part (member). The removal effect is reduced, and the image-forming layer dissolved in the liquid metering section is likely to peel off, which is not preferable. Furthermore, if all of the liquid material on the plate is removed in the alkaline treatment step as in the liquid circulation system, the fatigue alkaline treatment liquid and the components of the image forming layer are also mixed, which is not preferable.
The alkaline processing liquid metering residual liquid amount after the liquid metering, depending on whether using any liquid metering means, often 30 to 120 g / m ^2, further preferably from 40 to 100 g / m ^2.

As a liquid measuring tool used in the liquid 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 uniformly in the measuring width direction, and suppresses peeling of the solubilized image forming layer during liquid measurement. It is essential to have a shape that prevents. 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. The liquid measuring device may be rotated by forcibly rotating the rotating shaft in a forward direction or a reverse direction at a certain peripheral speed, or at least only when the plate passes. The pressing weight can cover the range sufficiently with the weight of only the liquid measuring tool, but if desired, the entire liquid measuring tool can be pressed with a pressure roll or the like, or the nip pressure is applied to both ends of the liquid measuring tool for substantial pressing. The weight may be increased.

The printing plate in which the non-image area has been dissolved is subjected to a non-image area removing and discarding step to remove the dissolved image forming layer component remaining in the non-image area by the removing means, and further conveyed to the next step. Most of the removed substances removed in the non-image part removing and discarding step are the dissolved image forming layer components and the fatigue alkaline processing liquid, and are therefore discarded. In addition, it is necessary to replenish the circulating liquid with a new liquid at least as much as the amount of the alkaline processing liquid contained in the waste liquid so as to secure the amount of the circulating liquid and maintain the alkaline processing activity.

As a removing means in the non-image portion removing step according to the present invention, a method using an air knife, a rubber blade, an elastic roll, a rotating and non-rotating (fixed or sliding) brush, a Molton roll, etc. Etc. The elastic roll can remove the alkaline treatment liquid on the plate surface by the nip pressure through the printing plate between the roll pair, and the rubber blade has an elastic material with at least a smooth contact surface with the plate along the conveyance path of the printing plate. It is possible to remove the alkaline treatment liquid on the plate surface by arranging the plate and making a sliding contact with the plate surface. Examples of elastic materials used in these include silicone rubber, neoprene rubber, butyl rubber, ethylene propylene rubber, nitrile butadiene rubber, and Teflon-coated rubber.

In installing the rubber blade, a guide roll rotating at a peripheral speed higher than the conveying speed is provided under the rubber blade, or pressurization is performed immediately after the leading edge of the plate passes through the rubber blade to prevent the conveyance failure from being induced. It is desirable to provide some mechanism for In addition, in the removal with a molton roll and a brush, a small amount of a treatment liquid for removal may be supplied at least at the time of removal in order to accelerate the peeling and removal of the dissolved image forming layer component. 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 alkaline treatment quality. To improve pressure,
A pressure assisting member and means such as a metal plate may be used on the side opposite to the plate contact surface of the rubber blade.

The printing plate carried out from the non-image area removing and discarding step is supplied with a rinse liquid in the rinse processing step to completely remove a slight residual substance removed from the plate. The rinse liquid supply method in the rinse treatment step can use a conventionally known liquid supply mechanism like that of the alkaline treatment liquid, for example, a shower, a high pressure spray, a dip method, etc., but unlike the treatment in the alkaline treatment liquid, The rinsing process must be able to quickly and completely remove the residual substance on the plate with the rinse liquid. Therefore, the liquid may be directly supplied to the printing plate by the method described in JP-A-3-109575, as long as it has a mechanism capable of suppressing the scattering of the liquid.
It may be supplied together with compressed air by the method described in Japanese Patent No. 261543. The treatment method used in the rinse treatment may be a disposal method or a circulation reuse method, or another method can be used if desired. The printing plate after the rinsing treatment is coated with a protective gum solution, treated, and then dried with hot air or the like as necessary for printing.

The non-image area alkali dissolution removal type lithographic printing plate to be treated in the present invention is a photosensitive lithographic printing plate having a photosensitive layer as an image forming layer on a support, or an electrophotographic layer having a photoconductive layer. It is a lithographic printing plate. As the support used for these printing plates, aluminum, zinc, copper-aluminum, copper-stainless steel, chromium-copper, chromium-copper-
Examples of the conductive support include aluminum and a metal plate such as chrome-copper-stainless steel as a base, and at least the surface on which the image forming layer is provided is subjected to a hydrophilic treatment. Further, their thickness is 0.07 to 2.0 mm, more preferably 0.07 mm.
1 to 0.5 mm is good. Among these substrates, the aluminum plate is preferably used. The aluminum plate may contain aluminum as a main component and a slight amount of a foreign element,
Conventionally known / publicly used materials can be appropriately used.

In order to impart desired surface texture to the surface of the support on which the image forming layer is provided, it is preferable to grain and anodize by a known method. Prior to the graining treatment, degreasing treatment with a surfactant or an alkaline aqueous solution may be performed.
The graining treatment method includes a mechanical surface roughening method, an electrochemical surface roughening method, and a chemical surface selective dissolution method. The roughened substrate is used after being subjected to alkali etching treatment and neutralization treatment, if necessary. The treated substrate is anodized to form an oxide film on its surface. Anodized film weight may have 0.1 to 10 g / m ^2, and more is preferably 1 to 6 g / m ^2.

A desired image forming layer is provided on the support thus obtained to obtain a photosensitive lithographic printing plate (PS plate) or an electrophotographic lithographic printing plate. Examples of PS plates relating to the treatment method of the present invention include diazo resins (salts of a condensate of p-diazophenylamine and paraformaldehyde) as described in British Patent 1,350,521 and shellac. A photosensitive layer consisting of a mixture with
Negative PS plate having a photosensitive layer composed of a mixture of a diazo resin described in JP-A No. 978 and No. 1,505,739 and a polymer having a hydroxyethyl methacrylate unit or a hydroxyethyl acrylate unit as a main repeating unit. And a positive PS plate having a photosensitive layer composed of a mixture of an o-quinonediazide photosensitive substance and a novolac type phenolic resin as described in JP-A-50-125806.

Further, a PS plate having a photosensitive layer made of a photocrosslinkable photopolymer as described in US Pat. No. 3,860,426, US Pat. Nos. 4,072,527 and 4 are used. PS plates having a photosensitive layer composed of a photopolymerizable photopolymer as described in JP-B No. 1,072,528, described in British Patent Nos. 1,235,281 and 1,495,861. PS plates having a photosensitive layer made of a mixture of such an azide and a water-soluble polymer are also known and can be used for these.

As an electrophotographic lithographic printing plate, a printing plate having a photoconductive layer composed of an organic photoconductor described in JP-B-37-17162 and a polymer substance containing an alkali-soluble group (acid or acid anhydride group) is disclosed. A printing plate having a photoconductive layer containing a low-molecular-weight alkali-soluble organic photoconductor described in JP-B-38-6961, and a vinyl acetate described in JP-B-41-2426 and a vinyl compound containing an alkali-soluble group. A printing plate having a photoconductive layer containing a copolymer, a printing plate having a photoconductive layer containing a photopolymerizable photoconductive compound described in JP-B-41-39405, JP-B-47-3.
A printing plate having a photoconductive layer containing a quinacridone pigment described in 6778 and an organic resin binder such as a phenol resin, and a light containing a phthalocyanine pigment described in JP-A-54-89801 and a hydrophilic resin. Printing plate having a conductive layer, a printing plate having a photoconductive layer containing a specific ratio copolymer of a vinyl group-containing carboxylic acid and an ester of methacrylic acid and / or acrylic acid described in JP-B-2-43181, Styrene described in JP-B-2-44065 /
A printing plate having a photoconductive layer containing a maleic acid monoester copolymer may be mentioned.

Images can be formed on these photosensitive lithographic printing plates and electrophotographic lithographic printing plates by known operations. In the present invention, the image refers to a portion having a resist in the following alkaline processing liquid which finally becomes an ink receiving portion on a printing plate, the former is exposed to light, the latter is charged and exposed to toner after exposure. Develop and perform. As an 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, or a lithographic printing plate having a highly sensitive photosensitive layer or photoconductive layer Scanning exposure with a laser beam, a light emitting diode, or the like. He is used for scanning exposure.
-Ne laser, He-Cd laser, argon ion laser, krypton ion laser, ruby laser, YAG laser, nitrogen laser, dye laser, excimer laser,
Scanning exposure using a laser light source such as a semiconductor laser such as GaAs / GaAlAs or InGaAsP, an alexandrite laser, or a copper vapor laser, or scanning exposure using a light emitting diode or a liquid crystal shutter (light emitting diode array,
It can be exposed by a line printer type light source using a liquid crystal shutter array or the like).

In the case of an electrophotographic planographic printing plate, toner development is performed after exposure. As a toner developing method, a dry developing method (cascade developing, magnetic brush developing, powder cloud developing) and liquid developing method are known, and any of them can be used. In particular, the liquid development method can form a fine toner image and is suitable for producing a printing plate with good reproducibility. Further, positive / positive development by positive development and negative / positive development by reversal development under application of an appropriate bias voltage are also possible. The formed toner image can be fixed by a known fixing method such as heat fixing, pressure fixing, solvent fixing and the like. As the toner component, a known composition having a resist property in the following alkaline processing liquid can be used.

The image-formed printing plate is treated with an alkaline treatment liquid to dissolve and remove the non-image area. As the alkaline processing liquid used for removing the non-image area, it is desirable to use an alkaline processing liquid containing an alkaline agent and having a buffering capacity in a high alkaline region. Conventionally, as an alkaline agent used in a photosensitive lithographic printing plate developer and an electrophotographic lithographic printing plate eluate, a silicate represented by the general formula: SiO ₂ / M ₂ O (M = Li, Na, K) Inorganic alkali agents such as alkali metal hydroxides, alkali metal and ammonium salts of phosphoric acid and carbonic acid, organic amine agents such as ethanolamines, diethylamine, ethylenediamine, triethylenetetramine, morpholine, and mixtures thereof.

Further, in order to accelerate the penetration of the alkaline agent into the non-image area and shorten the alkaline treatment time, especially in electrophotographic lithographic printing plates, ethanol is used in the range where toner peeling is not induced during the alkaline treatment. Aliphatic alcohols such as 2-propanol and 1-butanol, benzyl alcohol, phenethyl alcohol, and aromatic alcohols such as phenylpropanols, 2-ethoxyethanol, 1-methoxy-2-propanol, and 1,2-dimethoxy Water-soluble organic solvents such as aliphatic ethers such as ethane, and inorganic salts such as sulfite may be used in combination.

The alkaline processing liquid is further described in JP-A-55-55.
Ionic compounds described in Japanese Patent No. 25100, JP-A-55-
Water-soluble cationic polymers described in JP-A-95946, water-soluble amphoteric polymer electrolytes described in JP-A-56-142528, neutral salts described in JP-A-58-75152,
Chelating agents described in JP-A-58-190952, liquid viscosity modifiers described in JP-A-1-177541, preservatives and bactericides described in JP-A-63-226657, and various surfactants and natural agents. Also, known components such as a synthetic water-soluble polymer can be contained if necessary.

[0037]

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.

Example 1 The surface of a JIS 1050 aluminum sheet was grained with a rotating nylon brush using a pumice / water suspension as an abrasive. After washing with water, it was immersed in a 10% sodium hydroxide aqueous solution at 60 ° C. 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. Subsequently, electrolytic surface roughening was performed in a 3% hydrochloric acid aqueous solution, and the surface was washed by immersing in a 20% sulfuric acid aqueous solution at 50 ° C. and then washed with water. Furthermore, anodizing treatment was performed in a 20% aqueous solution of sulfuric acid to form an aluminum oxide film on the surface, washed with water and dried to obtain a support. On the surface-treated surface of the support, the coating liquid for forming a photoconductive layer shown in Table 1 dispersed for 1 hour with Dynomill was applied at a solid content of 4.
After being coated at 4 g / m ² , it was dried at 90 ° C. for 30 seconds to obtain an electrophotographic lithographic printing plate (printing plate A).

[0039]

[Table 1]

The printing plate A was cut into A2 size, shielded from light and heated at 50 ° C. for 2 hours, and then left at room temperature. Next, the surface of the photoconductive layer was charged in a dark place so that the surface potential was about +280 V, and then scanning image exposure was performed using a semiconductor laser (780 nm), and immediately a positively charged toner (L paper manufactured by Mitsubishi Paper Mills Ltd., L
Inverse development (bias voltage: +1) using OM-ED III
20 V), and dried with cold air to remove the toner dispersion medium, and then heat-fixed to form a toner image on the photoconductive layer. The obtained toner-developed printing plate was subjected to plate making using a planographic printing plate processing apparatus as shown below.

FIG. 1 shows a planographic printing plate treating apparatus equipped with a carbon dioxide-containing gas supply means for the removal waste liquid used in this embodiment. The basic constitution of this processing apparatus comprises an alkaline processing liquid supply step and a non-image part removing and discarding step including a carbon dioxide containing gas supply means, and a rinse processing step and a protective gum solution coating / drying step which are not shown are additionally provided. The planographic printing plate is automatically conveyed on the printing plate conveying line 1 in the direction of the arrow, and the processing liquid is supplied.

The alkaline processing liquid supply step is composed of an alkaline processing liquid supply section composed of the processing solution supply pipe 27, the flow rectifying plate 28 and the liquid supply roll 11a, and a liquid measuring section composed of the liquid measuring tool 47 and the guide roll 13. To be done. The alkaline processing liquid 16 is adapted to be supplied to the plate surface via the liquid supply pipe 27 and the straightening plate 28 and the liquid supply roll 11a, and the surplus portion is backed up by the backup roll 11b and the lower guide plate 76.
After that, it is collected in the alkaline treatment liquid storage tank 3. Further, the alkaline processing liquid measured by the liquid measuring unit also flows on the liquid guide plate 75 and is collected again in the alkaline processing liquid storage tank 3 through the liquid drop hole 78.

Inside the alkaline processing liquid storage tank 3, there is arranged a sensor 21 which is a stored liquid amount detecting means whose outer periphery is separated by a liquid surface stationary means (not shown), and the alkaline processing liquid 16 is set as the replenishing liquid. Even if the replenishing means is operated after the quantity is reduced, and the replenishing means is operated by the printing plate passage detecting means 14 for each set number of sheets to be processed so that the replenishing mode can be selected so that the set amount or the sensor upper limit is replenished. Has become. Further, the replenishment of the replenishing liquid is started by the replenishing liquid replenishing control mechanism (not shown) at an arbitrary time immediately after the printing plate passes the printing plate passage detecting means 14.

Liquid supply to the alkaline processing liquid storage tank 3 can be carried out through three routes. Replenisher tank 1
The eluate replenisher 7 stored in 9 is directly replenished to the alkaline processing liquid reservoir 3 via the replenishment pump 94 and the electromagnetic valve 100, and the eluate replenisher 8 stored in the replenisher reservoir 89.
4 is configured to be replenished to the alkaline processing liquid storage tank 3 via the replenishing pump 99, the electromagnetic valve 101, and the replenishing liquid supply pipe 54 and the liquid measuring tool 47. In addition to these two systems of replenishment paths, an alkaline treatment is performed from a liquid storage source not attached to the treatment apparatus according to the present embodiment, via the pipe 128, the electromagnetic valve 125, and the replenishment liquid supply pipe 54, and via the liquid measuring tool 47. The liquid storage tank 3 is also replenished.

The non-image area removing / disposing step is composed of a dissolved non-image area removing section comprising a rubber blade 22 and a backup roll 20 which are means for removing the dissolved non-image area, and a removal waste liquid primary storage tank 4. The pressure of the rubber blade 22 is adjusted by a rubber blade pressing mechanism (not shown) so that the contact width with the backup roll 20 is minimized within a range where the dissolved non-image area image forming layer is optimally removed. There is. The liquid material removed by the rubber blade 22 is temporarily stored in the removal waste liquid primary storage tank 4 and finally disposed in the removal waste liquid secondary storage tank 9.

An air supply pipe 152 is provided in the removal waste liquid secondary storage tank 9.
Is provided so that a gas containing at least carbon dioxide can be blown into the bottom portion of the second removal waste liquid storage tank 9 by the carbon dioxide-containing gas supply means. As the carbon dioxide-containing gas supply means, a supply path for supplying air from the air pump 157 through the valve 145 and a supply path for mainly supplying carbon dioxide from a carbon dioxide-containing gas storage source (not shown) through the conduit 148 and the valve 143. There are two systems of air paths, both of which are connected to the air supply pipe 152. In addition, the air supply pipe 15
An air diffuser air stone 165 is connected to the inlet of No. 2.

The printing plate from which the non-image area has been removed in the non-image area removing and discarding step has the dissolved non-image area image forming layer and the alkaline processing solution remaining on the plate together with the rinse liquid in the rinse processing step (not shown). After being rinsed and removed, the protective gum solution is applied and dried in the protective gum solution applying and drying step.

For the plate-making process, the eluents and replenishers shown in Tables 2 and 3 were used. The replenisher was supplied from the replenisher replenisher tank 89 through the replenisher solution supply pipe 54 and the liquid measuring device 47, and was replenished to the replenisher solution storage tank 89 as appropriate according to the amount of use reduction.
Further, the supply of the carbon dioxide-containing gas to the removal waste liquid secondary storage tank 9 is performed by closing the valve 143 and opening the valve 145 so that the air can be supplied from the air pump 157.
Plate making was started without operating the air pump 157.

[0049]

[Table 2]

[0050]

[Table 3]

The pH of the removal waste liquid in the removal waste liquid secondary storage tank 9 was measured at the time of making the 500th plate, and it was 12.72. Therefore, when the plate making is started again and at the same time, the air pump 157 is operated and air is blown into the removal waste liquid secondary storage tank 9 while the planographic printing plate processing apparatus is being activated, further 1000 plates are produced. Since it was lowered by the absorption of carbon dioxide in the air, the pH became 11.97 without adding a pH-lowering substance again.
The removed waste liquid in which the carbon dioxide-containing gas was blown in did not generate heat or generated agglomerates as compared with before the injection of carbon dioxide, and could be smoothly injected into the waste liquid tank.

Comparative Example 1 When the plate making process was performed in exactly the same manner as in Example 1 except that the carbon dioxide-containing gas was not blown into the removal waste liquid during the plate making period, the amount of the removal waste liquid in the removal waste liquid secondary storage tank 9 was found. Is 18.8
It became dm ³ and the pH was 12.70. No agglomerates were found in the removed waste liquid, but the liquid pH was 12.
Concentrated nitric acid was added again to make it 5 or less. When concentrated nitric acid is added, the removed waste liquid immediately generates heat and a large amount of soft agglomerates are generated at the bottom of the removed waste liquid secondary storage tank 9. As a result, not only the amount of the concentrated nitric acid waste liquid increases but also the agglomerates are destroyed while pouring. Since it had to be done, the transfer to the waste liquid tank could not be performed smoothly.

Example 2 In the planographic printing plate processing apparatus used in Example 1, a pipe line 148 was used.
A carbon dioxide high-pressure cylinder was communicated with the valve, the valve 145 was closed and the valve 143 was opened, and carbon dioxide was supplied during the plate-making process. Similarly, the pH became 12.17 without adding a pH-lowering substance. The removed waste liquid in which carbon dioxide was blown into the waste liquid tank could be smoothly injected into the waste liquid tank, as in Example 1, no particular agglomerates were observed.

Example 3 The surface of a JIS 1050 aluminum sheet was grained with a rotating nylon brush using a pumice / water suspension as an abrasive. After washing with water, it was immersed in a 10% by weight aqueous sodium hydroxide solution at 60 ° C. and etched so that the amount of aluminum dissolved was 6 g / m ² . After washing with water, add 30% by weight nitric acid solution to 1
It was soaked for a minute for neutralization and then thoroughly washed with water. Subsequently, electrolytic surface roughening was performed in a 2 wt% nitric acid aqueous solution, and 20 wt% at 50 ° C.
The surface was washed by immersing it in an aqueous solution of sulfuric acid and then washing with water.
Further, anodization treatment was performed in a 20 wt% sulfuric acid aqueous solution to form an aluminum oxide film on the surface, washed with water and dried to obtain a support. Table 4 shows the surface of this support.
The photosensitive layer forming coating solution described above has a solid content of 2.1 g / m ²
And then dried at 90 ° C. to obtain a photosensitive lithographic printing plate (printing plate B).

[0055]

[Table 4]

This printing plate B was cut into A2 size, and a positive image original was passed through the plate to expose it from a distance of 80 cm using a 2 KW metal halide lamp, and then the planographic printing plate processing apparatus used in Example 1 and Table 5 were used. And plate making was carried out using the treatment liquid described in Table 6. From the suitability of the plate making process, the guide roll 13 was used in the planographic printing plate processing apparatus used in Example 1.
The liquid measuring tool 47 arranged above was moved onto the transport roll 17, and the plate was prepared by adjusting the plate transport speed so that the alkali processing time was such that the photosensitive layer of the non-image part was completely dissolved immediately before the non-image part removal and disposal process was carried in. .

[0057]

[Table 5]

[0058]

[Table 6]

The same as in Example 1, except that the plate conveying speed was changed and air was blown into the removal waste liquid at the time of making the 200th plate (the pH of the removal waste liquid was 12.67).
0 plate was made. As a result, the removed waste liquid dropped due to the absorption of carbon dioxide in the air, so that the pH became 11.85 without adding a pH-lowering substance again. The removed waste liquid in which the carbon dioxide-containing gas was blown in did not generate heat or generated agglomerates as compared with before the injection of carbon dioxide, and could be smoothly injected into the waste liquid tank.

Comparative Example 2 The valve 14 was used in the planographic printing plate processing apparatus used in Example 3.
5 A plate-making process was performed in exactly the same manner as in Example 3 except that a highly alkaline carbon dioxide degassing mechanism was connected between the five air pumps 157, and carbon dioxide-free air was blown into the removed waste liquid during the plate-making period. , PH in the removal waste liquid secondary storage tank 9
Was 12.62 with almost no drop when no gas was blown. No agglomerates were observed in the removed waste liquid, but an acid had to be added again in order to adjust the liquid pH to 12.5 or less.

[0061]

As described above, by treating the highly alkaline processing waste liquid produced by the plate making process by the planographic printing plate processing waste liquid processing method of the present invention, the liquid is added by adding an acidic substance again when the processing waste liquid is discarded. The treatment waste liquid can be treated easily and safely without lowering the pH, and the excellent effect of significantly reducing the treatment waste liquid treatment load is brought about.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional configuration diagram of a planographic printing plate processing apparatus used for carrying out a plate making process according to a planographic printing plate processing waste liquid processing method of the present invention.

[Explanation of symbols]

 1 Printing plate conveyance line 3 Alkaline treatment liquid storage tank 9 Removal waste liquid secondary storage tank 157 Air pump 165 Air diffuser air stone

Claims (1)

[Claims] 1. A lithographic printing plate that is supplied with an alkaline processing liquid on the image forming surface of the lithographic printing plate to dissolve the non-image area, and then the alkaline processing liquid and the dissolved non-image area on the printing plate are removed and discarded. A method for treating waste liquid in the plate making process, wherein a gas containing at least carbon dioxide is blown into the waste treatment liquid consisting of the discarded alkaline processing liquid and non-image part components. Treatment waste liquid treatment method.