JPH05289558A - Plate making method for electrophotographic lithographic printing plate - Google Patents

Abstract

PURPOSE:To restrain fixation at the side end part of a printing plate by using a fixing member provided with a radiant heat generating part whose length in the width direction with reference to the printing plate advancing direction is equal to or below the length of the printing plate in the advance direction. CONSTITUTION:At the stage of the fixation processing to perform the fixation by applying a radiant heat transfer system after toner developing is performed on the printing plate, the fixing member provided with the radiant heat generating part whose length in the width direction with reference to the printing plate advancing direction is equal to or below the width of the printing plate in the advance direction is used so as to perform the fixation. For example, in the case that the width of the printing plate 21 in the advance direction is 295mm, four infrared ray lamps 22 whose filaments 23 are 280mm in length are arranged in parallel so that the center point of the printing plate 21 in the width direction may pass just under the center point of the filament 23 in the length direction. In this fixing device (the printing plate 21 is made to go ahead in a direction vertical to the length direction of the lamp 22), the printing plate 21 is made to pass while taking the longitudinal direction of the printing plate 21 as the advance direction so as to perform the fixation. And continuously, a plate making processing is performed by using an automatic eluting machine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic lithographic printing plate precursor for a non-image area, in which the toner is suppressed from being fixed at the end portion on the side of the electrophotographic lithographic printing plate and printing stains caused thereby are prevented. The present invention relates to a method for making a photolithographic printing plate.

[0002]

2. Description of the Related Art Many methods for producing a lithographic printing plate are already known. For example, a printing original plate is brought into close contact with an original made of a silver salt film, and the photosensitive layer of the original plate is directly exposed to ultraviolet rays or the like,
This is a plate making method in which a cured portion corresponding to the image portion of the original document and a non-cured portion corresponding to the non-image portion are formed, the non-cured portion is washed and removed with alkali or water, and the cured portion is made ink-acceptable. . The printing plate produced by this method is called P
It is called S version and is widely used.

On the other hand, due to advances in computer image processing technology, memory development of large-capacity data, and data communication technology, etc., in recent years, computer operation is consistently performed from original input, correction, editing, layout to page grouping, and high speed communication network. An electronic editing system that can immediately output to a terminal plotter at a remote place through satellite communication has been put to practical use. In particular, in the field of newspaper printing where immediacy is required, not only electronic editing systems but also plate making systems that can directly obtain a printing plate from data from the electronic editing systems are being put to practical use. At present, in such a plate-making system, an electrophotographic process is used, and a laser light source (semiconductor laser, He-Ne laser, etc.) is used.
Exposure-based systems have been studied from various aspects.

Further, in such a system, an elution type electrophotographic lithographic printing plate as described later can be printed under the same printing conditions as the PS plate used conventionally, which is advantageous. Can be used for As the main plate making process, the electrophotographic lithographic printing plate is charged, exposed, and developed with a toner to form an image, and the non-image portion on which the toner does not adhere is removed by an eluent, and the surface of the support which has been subjected to a hydrophilic treatment in advance. Exposed to make a printing plate. Here, since the image portion protected by the toner is lipophilic, offset printing can be performed.

The electrophotographic lithographic printing plate is prepared from an electrophotographic photoreceptor in which a photoconductive layer containing a photoconductive substance is coated on a conductive support such as aluminum. Examples of the material forming the photoconductive layer of this electrophotographic photoreceptor include JP-B-37-17162, 38-758 and 46-3.
9405, JP-A Nos. 52-2437 and 57-161.
No. 863, No. 58-2854, No. 58-28760
No. 58-118658, No. 59-12452,
59-49555, 62-217256, 6
Organic photoconductive compound / binder resin materials such as those described in JP-A-3-226668 and JP-A-1-261569 are excellent in practical sensitivity and printing durability.

In the plate making process of the electrophotographic lithographic printing plate, the photoconductive layer of the electrophotographic photosensitive member is first subjected to a predetermined charging process so that a uniform charge is applied. The exposure then forms an electrostatic latent image corresponding to the image. Subsequently, development using an electrophotographic developer and fixing processing are performed to form a toner image corresponding to the electrostatic latent image.
The non-image area other than the toner image is dissolved and removed (eluted) by a solution containing an alkaline agent, etc., followed by washing with water or adjustment of the apparent pH of the plate surface with an acidic rinse solution, and if necessary. A final printing plate is obtained by performing a treatment such as application of a plate surface protective liquid (protective gum liquid).

In the developing step, if a toner image is obtained by so-called reversal development, a good image with less fog and line thinning can be obtained due to its developing characteristics. Recently, particularly high resolution and high quality image reproducibility have been demanded, and a method for producing an electrophotographic lithographic printing plate by reversal development is a method that meets this quality requirement.

When reversal development is performed, first, in the exposure step, the portion to which the toner is to be attached, that is, the image area is irradiated with light, and the potential of the light irradiated portion is attenuated to almost 0V. .. At this time, the portion where light irradiation is not performed, that is, the portion corresponding to the non-image portion, maintains the initial charging potential as it is. In the developing step, a predetermined developing bias voltage is applied between the electrode and the electrophotographic lithographic printing plate through the electrode filled with the liquid developer. In this case, as the toner particles in the developer, those having the same polarity as that of the electrophotographic planographic printing plate side charged by a predetermined method are used. In such a state, when the photoconductor having an electrostatic latent image is carried into the developing electric field in the developing process area, the toner particles in the developer are migrated to the photoconductor side by the developing bias electric field, and the light irradiation portion is exposed. Toner particles are attached to almost 0V portion of a certain photosensitive member to form a toner image. At this time, the portion corresponding to the non-image portion where the initial charging potential remains repels the toner particles, and the adhesion of the toner particles is avoided.

As a developer used for such reversal development, either a dry developer or a liquid developer can be generally adopted, but when a liquid developer is used, the toner particles are made fine. Therefore, high resolution and good image reproducibility can be obtained. The liquid developer is
A polymer and a pigment (dye) or polymer particles are dispersed in a high insulating medium, colored as necessary, and a charge (charge) control agent is added to this to impart a predetermined charge.

[0010]

By the way, as a method for producing such an electrophotographic lithographic printing plate, a sheet-shaped or coil-shaped aluminum plate is generally prepared by, for example, graining, anodic oxidation, chemical treatment or the like. Various surface treatments may be carried out individually or in combination, after which the electrophotographic photosensitive layer is coated, dried and then cut into a desired size.

When such an electrophotographic lithographic printing plate is printed using a printing plate obtained by imagewise exposure and the above-mentioned processing, especially electrophotographic liquid reversal development processing, a conventional sheet-fed printing machine is used. When printing on paper smaller than the size of the printing plate, there is no problem if the part corresponding to the side edge of the printing plate does not enter the printing surface. When continuous printing is performed on a roll of paper using a turning machine, the side edge of the printing plate also enters the surface of the paper. At this time, if toner adheres to the side edge of the printing plate during the developing process, the toner is ink-receptive, and the ink that has adhered to the side edge of the printing plate is printed on the paper, causing stains. This results in a significant loss of value.

In the electrophotographic reversal development, the toner is developed on the side edge of the printing plate because the conductive support is exposed by cutting at the side edge, and the potential holding ability is maintained even when charged in the charging step. This is because there is no such force, so that there is no force for repelling toner at the time of reversal development, and the bias voltage applied from the developing electrode induces adhesion of toner to the side end. Further, the toner adhered to the side edge portion does not peel off in the next elution step after being fixed in the fixing step, and appears as an ink receiving portion, that is, an image line during printing. Here, the side edge portion of the printing plate includes not only the cross section of the printing plate but also the burr portion and a portion of the photosensitive layer around the burr portion where the conductive support is partially exposed.

In JP-A-63-178240, an insulating polymer is applied to the side edge of the printing plate, and in JP-A-2-61654, a water-soluble polymer is applied to that portion. Japanese Patent Application Laid-Open No. 2-66566 proposes coating an alkali-soluble polymer on the relevant portion. Although these are very effective methods, the elution may be incomplete when the toner locally adheres excessively.

An object of the present invention is to provide a plate-making method capable of obtaining an electrophotographic lithographic printing plate free from ink stains caused by side edges even after electrophotographic development treatment. ..

[0015]

Means for Solving the Problems As a result of intensive studies by the present inventors, the following constitution was achieved as a method for preventing printing stains due to the toner adhering to the end portion of the printing plate side as described above. I was found to be done. That is, a method for making a non-image area eluting type electrophotographic lithographic printing plate whose support is a metal plate, wherein the radiation generating part is used in the fixing step of fixing the printing plate with a radiant heat transfer method after toner development. The length in the width direction of the printing plate in the advancing direction is equal to or less than the width of the printing plate in the advancing direction, and fixing is performed using a fixing member having a radiation generating portion. With this configuration, the fixing of the toner adhered to the side end portions is suppressed, and the toner does not exist at the side end portions after the elution processing step.

Generally, in the fixing step, the toner is phase-changed from a solid to a liquid, or the toner is plastically deformed to widen the contact area between the toner particles or between the toner and the support, and thus between the toner particles or the toner and the support. Adhesion and fixing are performed by generating an intermolecular force between and. Generally, toner fixing methods are classified into heat fixing, pressure fixing, solvent fixing, and the like depending on the form of energy applied to the toner to cause a phase change or plastic deformation (“Basics and Applications of Electrophotographic Technology”, electronic fixing). (Photographic Society, Corona Publishing Co., Ltd.), in order to prepare the non-image area eluting type electrophotographic lithographic printing plate used in the present invention, heat fixing or fixing using heat and pressure in combination in that a dense toner film can be obtained. The method is preferably used. The heat fixing can be further classified into a radiant heat transfer method, a convection heat transfer method, a heat transfer method, etc., depending on the heat transfer method.

The fixing method using the radiant heat transfer method used in the present invention uses radiant heat, and uses an infrared lamp, a xenon flash, or a far-infrared emitting ceramic heater. However, the configuration of the present invention can be applied to all those using radiant heat, and is not limited to the type of radiant heat source. The term "radiation generator" as used in the present invention refers to a portion in the radiant heat source that emits heat and light. Specifically, for example, an infrared lamp refers to a filament, and a xenon flash refers to a discharge tube.

After the non-image area eluting type electrophotographic lithographic printing plate is subjected to the toner development process, the fixing of the side end portion of the printing plate is suppressed during the fixing process, that is, the toner particles are deformed at the side end portion. The toner particles adhering to the portions are maintained in the state of not being fused (dry powder), or only a weak film that is easily peeled off by the subsequent elution treatment is formed. In the subsequent elution treatment, due to the diffusion and permeation of the eluate, the toner particles or a weak film thereof have a significantly poor adhesion between the toner particles or the adhesion between the toner particles / film and the photosensitive layer or the support. It is peeled off from the photosensitive layer or the support. At the same time, the photosensitive layer is also eluted. In the subsequent printing, the side edge portion does not show ink acceptability, and ink stain does not occur on the printed matter.

On the other hand, the portions other than the side edge portions of the printing plate are sufficiently fixed, and the toner particles developed and adhered to the image portion of the portion are made into a continuous film state in which the particles are deformed and fused, and the eluate Prevents penetration and protects the photosensitive layer below the toner layer from the eluent. In the subsequent printing, the toner layer exhibits ink acceptability together with the photosensitive layer below the toner layer, and an image line is printed on the printed matter.

Here, a method of suppressing the fixing of the toner adhering to the side edge portion of the printing plate in the fixing step using the radiant heat transfer method of the present invention will be described in more detail.

When the present inventors use, for example, a fixing lamp such as an infrared lamp or a xenon flash in the fixing process, the electrophotographic toner on which toner is attached by development from the heat and light emitting portion of the lamp, that is, the radiation generating portion. By making a difference in the distance to the surface of the planographic printing plate, it is possible to divide and create the area where the above-mentioned "fixing" is completed or not completed on the same printing plate. I found it.

That is, the portions other than the side edge portions of the printing plate are set to a distance capable of giving a heat quantity enough to complete the fixing of the toner within a fixed time, and at the same time, the side edge portion where the fixing is desired to be suppressed is the radiation generating portion. You can omit it.

That is, the length of the radiation generating portion of the lamp can be achieved by fixing with a fixing lamp having a width equal to or less than the width of the printing plate in the traveling direction (for example, shown in FIG. 2). Method). Further, even when a fixing lamp in which the length of the radiation generation part of the lamp is equal to or larger than the width of the printing plate is used, the fixing part is arranged obliquely to the width direction with respect to the traveling direction of the printing plate, and the radiation generation part of the lamp is Can also be achieved by fixing the toner so that it does not protrude outside the plate (for example, the method shown in FIG. 3).

The thickness of the electrophotographic lithographic printing plate used in the present invention is particularly preferably 0.1 to 0.5 mm as described later, but the heat capacity of the electrophotographic lithographic printing plate varies depending on this thickness and material. The advancing speed of the electrophotographic lithographic printing plate in the fixing step of the present invention is preferably in the range of 0.5 to 10 m / min. Further, the toner used in the present invention preferably has a minimum temperature at which fixing occurs in the range of 40 to 150 ° C. The length of the radiation generating portion of the fixing member in the width direction with respect to the printing plate advancing direction in the present invention varies depending on the various factors as described above, and therefore cannot be generally stated, but the width of the printing plate with respect to the advancing direction is 1 Then,
The range of 0.6 to 1 is preferable. When the length is 1 or more, suppression of fixing of the end portion on the printing plate side becomes insufficient. If the length is less than 0.6, the fixing of the portion other than the end portion on the printing plate side becomes insufficient.

In the constitution of the present invention, in order to give a certain amount of heat to the surface of the electrophotographic lithographic printing plate, the radiant heat source is fixed and the electrophotographic lithographic printing plate is fixed while being conveyed, or the fixed electrophotographic. It can be used without any problems in an apparatus of a system in which a radiant heat source is moved and fixed with respect to a lithographic printing plate, or in a system in which a radiant heat source and an electrophotographic lithographic printing plate are both moved and fixed. In addition, in the fixing step, it is common to convey the surface of the electrophotographic lithographic printing plate with the image side facing upward. However, the constitution of the present invention is not limited to the upward direction, but the image of the electrophotographic lithographic printing plate is present. It can also be used for a device that conveys with the surface facing downward.

When electrophotographic liquid reversal development is performed on a non-image area-eluting electrophotographic lithographic printing plate to make a plate, toner is remarkably adhered to the side edge portion having no potential, but the developing device is substantially biased. If the width of the developing electrode to which a voltage is applied in the direction perpendicular to the plate advancing direction is made equal to or less than the width of the electrophotographic lithographic printing plate, the toner adhering to the side edges is not It will decrease sharply compared to
The method of the present invention can be used more effectively.

Further, it is possible to further increase the effect of the present invention by providing a potential holding layer which holds a potential in advance by a charging step and is soluble in an eluate at a side end portion of the electrophotographic planographic printing plate before plate making. Is desirable. In this way, it becomes possible to elute even an eluate having a relatively low elution capacity, which is advantageous for long-term running performance.

Further, in addition to the plate-making method of the present invention, before the elution of the non-image area, the side edge portion is coated with the liquid containing the eluent component, or in the elution step, the side edge portion of the electrophotographic lithographic printing plate is used. The effect of the present invention can also be improved by installing a sliding or rotating brush or the like for promoting the elution of water.

According to the constitution of the present invention, an image information outputted from an electronic editing system or the like used especially for newspaper printing is directly written on an organic semiconductor by a laser beam and reversal development is carried out to obtain a printing plate. An automatic plate making device for photolithographic printing plates (for example, "Newspaper Technology" by the Japan Newspaper Association NO.
133 P16-23 (1990) computer direct plate-making device) and the like are incorporated into the fixing step, so that it is not necessary to add a part to the side edge of the printing plate to the device, which saves cost and space. It can be advantageously used in terms of

Although the present invention is preferably used in the reversal development as described above, it can be also used in an apparatus having a developing section for performing the positive development without any trouble.

The electrophotographic lithographic printing plate used in the present invention has at least one electrophotographic photosensitive layer on a conductive support. As the conductive support, a plastic sheet or paper having a conductive surface, or a metal plate such as an aluminum plate or a zinc plate is used, and its thickness is preferably 0.1 to 3 mm, particularly 0.1
~ 0.5 mm is preferred. Among these substrates, an aluminum plate that is roughened and has an anodized film is suitable. Further, the aluminum plate applied to the present invention is not limited in its composition, surface treatment, etc., and is conventionally known.
The materials for public printing plates can be appropriately used.

A conventionally known electrophotographic photosensitive layer is provided on such a conductive support. As the photoconductive material used for the electrophotographic photosensitive layer, many conventionally known inorganic or organic compounds can be used. For example, inorganic photoconductive materials include selenium and selenium alloys, amorphous silicon, Cd, CdSe, CdS.
Se, ZnO, ZnS, etc. are listed. Further, as the organic photoconductive material, known organic photoconductive compounds such as phthalocyanine and its derivatives can be used. Two or more kinds of organic photoconductive compounds can be used in combination, if desired. Further, various sensitizers, pigments, dyes and the like can be used together for the purpose of improving the sensitivity of the photoconductor and imparting sensitivity to a desired wavelength range.

In the electrophotographic lithographic printing plate photosensitive layer, the photoconductive compound itself may have a film-forming property, but when the photoconductive compound alone does not have a film-forming property, a binder resin is used. Can be used together. For the electrophotographic photosensitive layer, it is necessary to finally remove the non-image area electrophotographic photosensitive layer, but this step is a process in which the solubility of the electrophotographic photosensitive layer in the eluate and the resist property of the toner image in the eluent Although it is determined by the relationship and cannot be generally expressed, at least the binder resin is preferably a polymer compound that is soluble or dispersible in the eluate. A monomer-containing copolymer having an acid anhydride group or a carboxylic acid group and a phenol resin have high charge retention when used as a photosensitive layer for an electrophotographic lithographic printing plate, and thus can be advantageously used. 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, a copolymer of acrylic acid or methacrylic acid and an alkyl ester, aryl ester or aralkyl ester of two or more of them. Coalescence is preferred. Further, a copolymer of vinyl acetate and crotonic acid is also preferable. Among the phenol resins, particularly preferred are phenol and o-
Examples thereof include novolac resins obtained by condensing cresol, m-cresol, or p-cresol with methanal or ethanal. The binder resins may be used alone or in combination of two or more.

The electrophotographic lithographic printing plate used in the present invention can be obtained by coating an electrophotographic photosensitive layer on a conductive support according to a conventional method. In producing the electrophotographic photosensitive layer,
A method of incorporating the components constituting the electrophotographic photosensitive layer in the same layer, or a method of separately incorporating the components into two or more layers, for example, the charge carrier generating substance and the charge carrier transporting substance are separately used in different layers. Methods and the like are known, and it can be produced by any method. The coating liquid is prepared by dissolving each component constituting the electrophotographic photosensitive layer in a suitable solvent.When a component insoluble in a solvent such as a pigment is used, a ball mill, a paint shaker, a dyno mill, or another dispersing machine is used. It is used by dispersing it to an average particle size of 0.01 to 5 μm. The binder resin and other additives used in the electrophotographic photosensitive layer can be added during or after the dispersion of the pigment. To obtain an electrophotographic lithographic printing plate by coating and drying the coating solution thus prepared on a support by a known method such as spin coating, blade coating, dip coating, rod bar coating, spray coating, and extrusion coating. Can be done. In the electrophotographic photosensitive layer, if necessary, in addition to the photoconductive compound and the binder resin, a plasticizer, a surfactant, and others for the purpose of improving the film properties such as flexibility and coated surface state of the electrophotographic photosensitive layer. Can be added. If necessary, an intermediate layer may be provided between the conductive support and the electrophotographic photosensitive layer in order to improve the adhesion and electrophotographic characteristics.

As the potential holding ability of the potential holding layer which is preferably provided in the electrophotographic lithographic printing plate used in the present invention, charging conditions, exposure conditions, elution conditions, surface potential holding ability of the electrophotographic lithographic printing plate are used. Although it varies depending on the electrical and chemical properties of the toner, the content of the plate-making image, etc., it is preferably in the range of several volts to several hundreds of volts. Also,
The potential holding layer also needs to be soluble in the eluate.
For example, if an eluate such as that described below is used, the following alkali-soluble resins having a certain level of potential holding ability can be used. For example, styrene-maleic anhydride copolymer, maleic acid ester resin, vinyl acetate-maleic anhydride copolymer, phenol resin, styrene-butyl acrylate-acrylic acid copolymer, butyl metaallylate-butyl acrylate-methacryl. Examples thereof include acid copolymers, 2-ethylhexyl acrylate-methacrylic acid copolymers, styrene-maleic anhydride half ester copolymers, vinyl acetate-crotonic acid copolymers, and the like. These may of course be used alone, but 2
Combinations of two or more can also be used.

If necessary, a plasticizer, a surfactant, or other additives may be added to the coating liquid for forming a potential holding layer prepared using these resins, as in the case of the photoconductive layer. Good. Further, it is possible to add a dye, a pigment or the like in order to enhance the recognizability.

Examples of the solvent for the potential holding layer forming coating solution include halogenated hydrocarbons such as dichloromethane, dichloroethane and chloroform, methanol, ethanol and 2-
Alcohols such as propanol and 1-butanol, ketones such as acetone, 2-butanone and cyclohexanone, glycol ethers such as ethylene glycol monomethyl ether and 2-methoxyethyl acetate. , Oxolane, oxane, cyclic ethers such as dioxane, ethyl acetate,
Examples thereof include esters such as propyl acetate and butyl acetate.

As a method of installing the potential holding layer, the coating liquid for forming the potential holding layer is applied and dried on the side end portion of the electrophotographic lithographic printing plate so as to have an appropriate film thickness after drying. Examples of the application method include brush application, roller application, sponge application, non-woven application, and spray application. The electrophotographic lithographic printing plates to be applied can be applied in a state where they are stacked in a large number (for example, 1000) or one by one, but in any case, they should be applied uniformly with an appropriate film thickness. is necessary. Alternatively, the resin or the like may be formed in advance into a film having an appropriate thickness, and the film may be attached to the side end portion. As described above, the proper film thickness in these cases is a film thickness capable of holding a potential in the range of several volts to several hundreds of volts when the obtained printing plate is charged in the plate making process.

In addition, a water-soluble resin or a hydrophilic compound such as an amino acid is contained between the potential holding layer and the side end portion for the purpose of further improving print stain resistance or improving the elution property in the elution step. An intermediate layer may be provided.

The toner used in the plate making method of the present invention is not particularly limited as long as it can be fixed by a radiant heat transfer method and further contains a resin component having a resist property against an eluate as described later. Not something. The resin component of the toner preferably used in the plate making method of the present invention includes, for example, (meth) acrylic acid, acrylic resin composed of (meth) acrylic acid ester, vinyl acetate resin, vinyl acetate and ethylene, vinyl chloride or the like. Copolymers, vinyl chloride resins, vinylidene chloride resins, vinyl acetal resins such as polyvinyl butyral, polystyrene, copolymers of styrene and butadiene, methacrylate esters, polyethylene, polypropylene and their chlorides, polyethylene terephthalate and polyethylene. Polyester resin such as isophthalate, polyamide resin such as polycapramide or polyhexamethylene adipamide, phenol resin,
Examples thereof include xylene resins, alkyd resins, vinyl-modified alkyd resins, gelatin, cellulose ester derivatives such as carboxymethyl cellulose, and other waxes and waxes.

Further, the toner may contain a dye, a pigment and a charge control agent as long as they do not adversely affect development or fixing.

The eluent used in the plate making method of the present invention is preferably an eluent containing an alkaline agent and having a buffering capacity. Conventionally, as an alkaline agent used in a developing solution for a photosensitive lithographic printing plate (PS plate), a general formula SiO ₂ / M ₂ O (M
= Na, K), inorganic alkali agents such as silicates, alkali metal hydroxides, phosphoric acid, alkali metal carbonates and ammonium salts, ethanolamines, ethylenediamine, propanediamines, triethylenetetramine, morpholine, etc. Organic alkaline agents, and mixtures thereof can be mentioned. Especially, since the silicate has a strong buffering capacity,
The eluent according to the present invention preferably contains at least this silicate, and it is more preferable to add another alkali agent such as an alkali metal hydroxide to this. The eluent according to the present invention further includes an ionic compound described in JP-A-55-25100, a water-soluble cationic polymer described in JP-A-55-95946, and JP-A-56-56.
Water-soluble amphoteric polymer electrolytes described in JP-A-142528, neutral salts described in JP-A-58-75152, JP-A-58.
-190952, the chelating agent described in JP-A-1-1
Liquid viscosity adjusting agent described in Japanese Patent No. 77541, JP-A-63-2
If necessary, known components such as antiseptics and bactericides described in JP-B 26657, various surfactants, and natural and synthetic water-soluble polymers can be contained.

The solvent in the eluate is not particularly limited as long as it can stably disperse and dissolve the above components, but water is more preferable and ion-exchanged water is advantageously used. Further, in a solution containing the eluent composition excluding the above alkaline agent, the above components are more stably mixed and dispersed in an amount such that elution does not substantially occur. A solvent may be added and contained.

[0044]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples, and electrophotographic lithographic printing is performed in a fixing step using a radiant heat transfer type fixing means. The gist of the present invention is to suppress the fixing of the toner adhering to the side edges of the plate and prevent the printing stains due to the side edges of the electrophotographic lithographic printing plate.

Example 1 A JIS 1050 aluminum sheet was placed at 60 ° C. and 10% N
Immersed in aOH aqueous solution, aluminum dissolution amount 6g / m
Etched to ² 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. afterwards,
Electrolytic surface roughening was performed in a 0.7% nitric acid aqueous solution for 20 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 carried out in a 20% aqueous solution of sulfuric acid, followed by washing with water and drying to prepare a printing plate support.

On the surface-treated surface of the support, the following photoconductive layer composition dispersed by a paint shaker for 1 hour was coated with a bar coater and dried at 90 ° C. for 5 minutes to prepare an electrophotographic lithographic printing plate. At this time, the coating amount of the photoconductive layer is 4.5.
It was g / m ² .

Photoconductive layer coating solution composition Butyl methacrylate / methacrylic acid copolymer (methacrylic acid 40%) 18 parts Metal-free phthalocyanine 4 parts Butyl acetate 60 parts 2-Propanol 18 parts

The obtained printing plates were stacked by sandwiching 50 sheets of paper having a basis weight of 50 g / m ² so that the polyethylene surface of the interleaving paper in which polyethylene of 10 μm thickness was laminated was in contact with the photoconductive layer, and stacking 50 sheets. 400 mm x 29
It was cut into a size of 5 mm. (Hereinafter, in the Examples, the width of the printing plate in the traveling direction when the lengthwise direction of the plate is the traveling direction refers to this 295 mm.)

The lithographic printing plate thus produced was subjected to corona discharge in a dark place to have a surface potential (V ₀ ) of about +30.
After charging to 0 V, the semiconductor laser (780n
m) for scanning image exposure (image area 350 mm x 2
Liquid reversal development (developing bias voltage 150V) with a positively charged liquid toner in which methyl methacrylate-butyl acrylate copolymer particles are dispersed in an insulating medium.
Was done. When the side edges of the electrophotographic lithographic printing plate after toner development were observed, toner adhesion was observed.

Next, the infrared lamp 22 (tungsten-halogen-quartz lamp) having a filament 23 having a length of 280 mm shown in FIG. 2 is located in the widthwise center of the printing plate 21 just below the center point of the length of the filament 23. The printing plate 21 is placed in a fixing device (where the printing plate advances in a direction perpendicular to the length direction of the lamp) arranged in parallel so that the dots pass, with the longitudinal direction of the printing plate being the advancing direction. It was passed and fixed.

Subsequently, a plate-making process was carried out by using an eluate, a water washing solution and a rinse solution using the automatic elution machine shown below. (1) Automatic elution machine An elution tank followed by a washing tank and a rinse tank (each tank has a capacity of 2
0L), a driving device for conveying the electrophotographic lithographic printing plate, a device for circulating the processing liquid in each processing tank in the cycle of storage tank → pump → spray nozzle → storage tank, an elution tank and a washing tank. An automatic machine having a rotary brush device for promoting elution and a replenishing device for each processing tank was used. (2-a) Eluent composition Sodium silicate aqueous solution (SiO ₂ min 30% by weight, SiO ₂ / Na ₂ O molar ratio 2.5) 20 parts Potassium hydroxide 1 part Pure water 79 parts (2-b) Washing liquid composition Sodium dioctyl sulfosuccinate 0.1 parts Pure water 99.9 parts (2-c) Rinse solution composition Citric acid 0.8 parts Phosphoric acid (85% aqueous solution) 0.5 parts Decaglyceryl monolaurate 0.05 parts Pure 100 parts of water

The presence of toner was not confirmed at the side edges of the electrophotographic lithographic printing plate after the elution step.

After that, the gum was sprayed using a general method, and then the offset foam rotary printing machine (manufactured by Ukida Kogyo Co., Ltd.)
OW-200ER) and printing paper (Mitsubishi Paper Mills Ltd.)
Made diamond foam 45 basis weight 52.3g / m ² paper width 47
0 mm) in the printing condition shown in FIG. 1 by the ordinary method, no ink stain corresponding to the side edge of the printing plate was found on the printed matter after printing 100,000 sheets.

Example 2 The same procedure as in Example 1 was carried out up to toner development. When the side edges of the electrophotographic lithographic printing plate after toner development were observed, toner adhesion was observed.

Next, the infrared lamp 32 (tungsten-halogen-quartz lamp) shown in FIG. 3 having a filament 33 having a length of 310 mm is formed at an angle of 25 between the length direction of the infrared lamp 32 and the width direction of the printing plate 31. The printing plate 31 advances diagonally so that the center of the printing plate 31 in the width direction passes diagonally below the center of the length of the filament 33, and advances in the longitudinal direction of the printing plate. In the direction, the printing plate 31 was passed therethrough to perform fixing.

Subsequently, the elution treatment was carried out in the same manner as in Example 1. No toner was present on the side edges of the electrophotographic lithographic printing plate after the elution step, and when printing was performed according to Example 1,
Similarly, ink stains corresponding to the side edges were not found in the printed matter.

Example 3 The same steps as in Example 1 were carried out until the production and cutting of the electrophotographic lithographic printing plate. Next, the following intermediate layer composition was applied to the side edge of the cut electrophotographic planographic printing plate with a sponge. After drying at room temperature, the coverage was 1 g / m ² .

Intermediate layer composition 30% aqueous gum arabic solution 70 parts 85% phosphoric acid 5.6 parts sodium nitrate 1.4 parts magnesium sulfate 1 part pure water 22 parts

On the intermediate layer of the lithographic printing plate which has been subjected to the above-mentioned treatment, the potential holding layer composition below was charged with a sponge so that the surface potential of the photosensitive layer was about 300 V. The applied potential (holding potential) was 20 V, and the coating was dried.

Potential holding layer composition Lauryl methacrylate-methacrylic acid copolymer (average molecular weight: 15000) 10 parts Methanol 90 parts

The electrophotographic lithographic printing plate thus prepared was charged, exposed and toner-developed in the same manner as in Example 1, and then fixed by the same fixing device as in Example 1. Subsequently, the elution treatment was carried out in the same manner as in Example 1 except that after the elution treatment liquid was put into the automatic elution machine, the 2000 edition treatment was carried out without supplementing the elution plate making treatment. No toner was present on the side edges of the electrophotographic lithographic printing plate after the elution step, and when printing was performed according to Example 1, similarly, ink stains corresponding to the side edges were not found on the printed matter.

Comparative Example 1 Up to toner development, the same procedure as in Example 1 was carried out. When the side edges of the electrophotographic lithographic printing plate after toner development were observed, toner adhesion was observed.

Next, fixing was carried out by the same fixing device as in Example 1 except that the filament 43 of the infrared lamp 42 shown in FIG. 4 had a length of 320 mm.

Subsequently, the same elution treatment as in Example 1 was performed. When the edge of the printing plate side after the elution treatment was observed in detail, toner adhesion was recognized. When printing was carried out in the same manner as in Example 1 using the printing plate thus prepared, ink stains corresponding to the side edges occurred on the printed matter immediately after printing.

[0065]

According to the present invention, a non-image area eluting type electrophotographic lithographic printing plate is subjected to electrophotographic development processing to obtain a printing plate,
Even when printing is performed on an object to be printed that is larger than the printing plate size, it is possible to obtain a printed product corresponding to the side edge of the printing plate and free from ink stains.

[Brief description of drawings]

FIG. 1 is a schematic view of a state in which an electrophotographic lithographic printing plate is attached to an offset form rotary printing press to print.

FIG. 2 is a schematic diagram of a fixing method according to the present invention.

FIG. 3 is a schematic diagram of a fixing method according to the present invention.

FIG. 4 is a schematic view of a fixing method used in a comparative example in the examples of the present invention.

[Explanation of symbols]

 11 plate cylinder 12 blanket cylinder 13 impression cylinder 14 electrophotographic planographic printing plate 15 side edges of electrophotographic planographic printing plate 16 plate mounting section 17 printing paper 21 electrophotographic planographic printing plate 22 infrared lamp 23 filament 31 electrophotographic planographic printing plate 32 Infrared lamp 33 Filament 41 Electrophotographic planographic printing plate 42 Infrared lamp 43 Filament

Claims (2)

[Claims] 1. A method for making a non-image area eluting type electrophotographic lithographic printing plate in which a support is a metal plate, wherein the printing plate is developed with toner and then fixed by a radiative heat transfer method, The length of the radiation generating portion in the width direction with respect to the printing plate advancing direction is the same as or less than the width with respect to the advancing direction of the printing plate, and is fixed using a fixing member having a radiation generating portion. Method for making electrophotographic lithographic printing plate. 2. The method for making an electrophotographic lithographic printing plate according to claim 1, wherein an image is formed by a reversal development method using a liquid developer as the toner.