JPH0549983B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a printing plate that can be made by electrophotography. More specifically, the light source is a new printing plate composed of a negatively charged electrophotographic photoreceptor sensitive to white light. After forming a toner image through a series of electrophotographic processes, the photosensitive layer in the non-image area is eluted. It relates to a printing plate formed by. [Conventional technology] Conventionally, lithographic printing plates have been positive-working PS plates made of diazo compounds using photolysis, and negative-working PS plates made of acrylic prepolymers using photocuring.
The PS version has been put into practical use. However, these have low sensitivity, so originals are prepared using silver halide film and exposed in close contact. This has the disadvantage that the plate-making process is complicated, requires a long plate-making time, and is substantially higher in cost. On the other hand, a zinc oxide-resin dispersion system (zinc oxide master paper) is a highly sensitive printing plate using electrophotography. This is done by forming an electrostatic latent image by exposing the document to reflected light obtained by irradiating it with light, and making it visible with a developer.
Create a lithographic printing plate. Furthermore, in order to make the non-image area hydrophilic, lithographic printing becomes possible by surface treatment with, for example, an aqueous solution (so-called etch solution) containing ferrocyanate or phytic acid as a main component. This is called direct plate making, and while it has the advantages of shortened plate making time and low running costs due to the simplicity of the plate making process, it has a printing life of less than 10,000 sheets and printing conditions (ink, etchant, moisture, etc.). The drawback was that the range of types of water available was narrow. Organic photoconductive material-resin printing plates described in Japanese Patent Publications No. 37-17162, Japanese Patent Publication No. 7758-1982, Japanese Patent Publication No. 39405-1987, Japanese Patent Publication No. 2437-1988, etc. are based on organic photoconductive materials, such as oxadiazole compounds. It is obtained by coating a photoreceptor made by dispersing the styrene-maleic anhydride copolymer in an alkali-soluble binder resin such as a styrene-maleic anhydride copolymer on a grained aluminum plate. This is a method in which a toner image is formed, and the non-image area is eluted with an alkaline aqueous solution using this toner image as a resist.
However, these organic photoconductive substance-resin printing plates have unsatisfactory sensitivity to visible light, and furthermore, the non-image areas of the printed matter are also of a smeared quality. In addition, direct plate making does not require film like PS plates, which simplifies the plate making process.
Since the plate making time can be shortened, there is an advantage that the cost is actually lower. Furthermore, this plate-making process involves forming a toner image using electrophotography, and then using this toner image as a resist to elute the non-image area with an alkaline aqueous solution.As a result, the non-image area of this printing plate has high water retention. PS as it will have a grained aluminum surface
It also has the advantage of having the same printing workability in the same printing environment as the plate. However, these printing plates made of the above-mentioned organic photoconductive material-alkali-soluble dispersed resin photoreceptor do not dissolve in the aqueous alkaline solution because the organic photoconductive material, which is an organic pigment, does not dissolve in an aqueous alkaline solution. When the non-image area was eluted mechanically, insoluble matter adhered to the pump, piping, etc., causing a problem in the elution ability of the non-image area. Also, put an alkaline aqueous solution in a container such as a vat,
Even when the elution step of the non-image area is carried out manually, it has been impossible to produce a high quality image due to the presence of insoluble matter in the alkaline aqueous solution. Furthermore, there is a method in which the non-image area is not eluted in an alkaline aqueous solution and the non-image area is eluted in a water washing process, but this method has an excellent running life for the alkaline aqueous solution, and even in the mechanical elution process of the non-image area. Although it does not cause problems such as clogging of pumps or piping, it is subject to regulations as industrial waste even though it does not contain harmful substances because the waste liquid that is washed with water contains photoreceptors. This can be dealt with by removing the photoreceptor with a filter, etc., or by treating waste liquid with a coagulant, but both require large-scale equipment or are cumbersome, and are not satisfactory plate-making methods. Nakatsuta. In addition, there are dye-resin based organic photoconductive materials, which are soluble in alkaline aqueous solutions, but while they do not have the above-mentioned disadvantages after elution, they are less effective than organic pigment-based photoconductive materials. , the electrical properties such as sensitivity were very poor, and none were satisfactory. [Object of the Invention] An object of the present invention is to provide a printing plate for electrophotolithography that has high sensitivity and can provide a high-quality printed image without stains in non-image areas. Another object of the present invention is to provide a printing plate for electrophotolithography in which a printing original plate is obtained by forming a toner image by an electrophotographic method and then dissolving a non-image area with an alkaline aqueous solution. Since the photoconductive substance of the photoreceptor is an alkali-soluble pigment, the photoreceptor eluted in the plate-making process has solubility in an alkaline aqueous solution, making it possible to obtain a printing plate with high image quality and to eliminate liquid waste. An object of the present invention is to provide a plate-making method that facilitates pollution countermeasures against. [Means for Solving the Problems] As a result of intensive studies by the present inventors, at least one photoconductive substance is 3,4,9,10-perylenetetracarboxylic dianhydride,
The above purpose can be achieved by a printing plate for electrophotolithography, characterized in that a photosensitive layer containing amorphous particles in an alkali-soluble resin is formed on a support having at least a conductive layer. was able to achieve this. Also, 3, 4, 9,
Since 10-perylenetetracarboxylic dianhydride is an alkali-soluble pigment, the photoreceptor eluted in the plate-making process has solubility in an aqueous alkali solution, thereby achieving the other objective. The structural formula of 3,4,9,10-perylenetetracarboxylic dianhydride, which is an alkali-soluble pigment of the photoconductive substance used in the present invention, is expressed as follows. Furthermore, 3,4,9,10- used in the present invention
The shape of perylene tetracarboxylic dianhydride is amorphous, as is clear from the SEM photograph in FIG. 1, and is distinguished from the needle-like shape shown in FIG. 2. Furthermore, 3,4,9, used in the present invention
The crystal structure of 10-perylenetetracarboxylic dianhydride has the X-ray diffraction spectrum pattern shown in FIG. Even if the same 3,4,9,10-perylenetetracarboxylic dianhydride does not satisfy the shape and crystal structure shown above, the electrophotographic properties will be significantly inferior. In order to improve electrophotographic properties, the printing plate of the present invention can contain an electron-donating substance mainly for the purpose of sensitization. Examples of electron-donating substances include 2,5-bis(4-dimethylaminophenyl)
-1,3,4-oxadiazole, 2,5-bis(4-diethylaminophenyl)-1,3,4-oxadiazole, 2,5-bis[4-(4-diethylaminostyryl)phenyl] -1,3,4-
Oxadiazole compounds such as oxadiazole, 2-vinyl-4-(2-chlorophenyl)-5
-(4-diethylamino)oxazole, 2-(4
-diethylaminophenyl)-4-phenyloxazole, triphenylmethane such as 2,2'-dimethyl-4,4'-bis(diethylamino)triphenylmethane, tris(4-diethylaminophenyl)methane Compound,
9-Ethylcarbazole-3-aldehyde-1-
Methyl-1-phenylhydrazone, 9-ethylcarbazole-3-aldehyde-1-benzyl-1
-phenylhydrazone, 4-diethylaminobenzaldehyde-1,1-diphenylhydrazone,
Hydrazone compounds such as 2-methyl-4-dibenzylaminobenzaldehyde-1,1-diphenylhydrazone, dialkylbenzoic acids such as dimethylaminobenzoic acid, diethylaminobenzoic acid, and dipropylaminobenzoic acid, fluoreon, pyrene, perylene, etc. Polycyclic aromatic compounds are used. The printing plate of the present invention uses an alkali-soluble resin as a binder so that the photosensitive layer can be easily eluted with an alkaline aqueous solution. This binder is selected so as to have alkali solubility, as well as electrical properties when used as an electrophotographic photoreceptor, as well as mechanical strength, ink resistance, and the like to ensure sufficient printing durability as a printing plate. These resins include those having hydroxyl groups and carboxyl groups, such as (1) acrylic acid (or methacrylic acid) and methacrylic acid esters (such as methyl methacrylate,
butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, stearyl methacrylate). (2) At least one vinyl ester (e.g. vinyl acetate, vinyl butyrate, vinyl propionate) and an unsaturated carboxylic acid (e.g. crotonic acid,
Itaconic acid, citraconic acid, maleic acid, maleic anhydride) copolymer. (3) Copolymer of styrene and maleic acid or maleic anhydride. (4) Phenol, o-cresol, m-cresol, p-cresol, t-butylphenol,
A novolac-type phenolic resin obtained by a condensation reaction of at least one substituted phenol such as cyclohexylphenol, t-butylcresol, and cyclohexylcresol with an aldehyde such as formaldehyde, acetaldehyde, acrolein, and crotonaldehyde under acidic conditions. (5) A mixture of two or more of the above resins. The support having at least a conductive layer used in the present invention is an aluminum plate, a zinc plate, or a bimetallic plate such as a copper-aluminum plate, a copper-stainless steel plate, a chromium-copper plate, or a chromium-copper plate.
A conductive support having a hydrophilic surface such as a tri-metal plate such as an aluminum plate, a chromium-lead-iron plate, or a chromium-copper-stainless steel plate, or which can be made hydrophilic, or the conductive plate and a plastic plate,
A composite support with paper, synthetic paper, etc., or a conductive support on which the surface of a plastic board, paper, or synthetic paper is made hydrophilic or has a treatment layer that can be made hydrophilic is used, and the thickness thereof is 0.1 to 0.5 Approximately mm is preferable. In addition, in the case of a support having an aluminum surface, graining treatment, sodium silicate, sodium fluoride, potassium fluorozirconate,
It is preferable to use a surface treatment such as immersion treatment in an aqueous solution of phosphate or anodization treatment. In addition, as shown in U.S. Patent No. 2,714,066, an aluminum plate is immersed in a sodium silicate aqueous solution after graining, and anodized as shown in Japanese Patent Application Laid-Open No. 1983-5125. Preferably, the material is immersed in an aqueous solution of an alkali metal silicate. The above anodizing treatment may be performed using an inorganic acid such as phosphoric acid, chromic acid, sulfuric acid, or boric acid, or oxalic acid.
This is carried out by passing an electric current through an aluminum plate as an anode in an electrolytic solution consisting of a solution of an organic acid such as sulfamic acid or a salt thereof. In addition, in the present invention, an alkali-soluble alkali-soluble material such as casein, polyvinyl alcohol, ethyl cellulose, phenol resin, styrene-maleic anhydride copolymer, polyacrylic acid, etc. is optionally provided between the conductive support and the electrophotographic photosensitive layer. An intermediate layer may be provided to improve the adhesion between the support and the electrophotographic photosensitive layer or the electrostatic properties of the electrophotographic photosensitive layer. The photosensitive layer used in the printing plate of the present invention is preferably in a state in which at least 3,4,9,10-perylenetetracarboxylic dianhydride (amorphous) is dispersed in an alkali-soluble resin. An organic solvent is used to adjust the viscosity for coating onto a support. Examples of organic solvents include ketones such as acetone and methyl ethyl ketone, alcohols such as methanol, ethanol, and isopropyl alcohol, aromatic hydrocarbons such as toluene and xylene, cellosolves such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve, and methyl acetate. , acetate esters such as ethyl acetate, etc., and those having good compatibility with the alkali-soluble resin and good film-forming properties during coating are used alone or in combination of two or more. Although simple stirring may be used as the dispersion method, it is preferable to uniformly disperse by mechanical means in order to improve the electrophotographic properties and the plate-made image. Common examples include ball mills and sand mills. Coating methods at this time include blade coating, gravure roll coating, rotary coating, knife coating, and dip coating. The electrophotographic photosensitive layer of the printing plate of the present invention is formed by dispersing at least the 3,4,9,10-perylenetetracarboxylic dianhydride (amorphous) in an alkali-soluble polymer. ,9,10-perylenetetracarboxylic dianhydride (amorphous) and alkali-soluble resin in a solid weight ratio of 1:2 to 1:6.
is preferred. At this time, when the electron donating substance is contained, it is preferable that the weight ratio to the 3,4,9,10-perylenetetracarboxylic dianhydride is 1:0.1 to 1:1. The electrophotographic printing plate of the present invention undergoes the following steps to obtain a final (printable) printing plate. First, according to the usual electrophotographic method, the surface of the photosensitive layer is charged with a charger, and then an electrostatic latent image is formed by exposing the original to reflective light using a halogen lamp or xenon lamp, or exposing the original to transparent light using a fluorescent lamp. Further, this electrostatic latent image is visualized by a developer to form a toner image and fixed. Next, the printing plate on which this electrophotographic image has been formed is cleanly eluted with an alkaline aqueous solution, leaving the toner image behind, and only the non-image areas are exposed, and the support consisting of a hydrophilic surface is exposed, resulting in the final (printable) printing. Get the edition. Here, the toner exhibits resist properties against alkaline aqueous solutions, but in this case, the developer used in this case is determined by the selection of the eluent.If it is a general electrophotographic developer, it will show the same effect, and the resist properties will be further improved. If this is desired, a developer consisting of an alkali-resistant toner component may be used. In addition, the eluate at this time is an alkaline aqueous solution mainly composed of inorganic alkalis such as sodium silicate, sodium hydroxide, sodium phosphate, and sodium carbonate, and organic amines such as monoethanolamine, diethanolamine, and triethanolamine. Alkaline aqueous solution as a component, etc.
Depending on the suitability of the binder resin of the photosensitive layer and the constituent resin of the toner, a wide range of other materials can be selected. As a method of eluating the non-image area with an alkaline aqueous solution, elution can be performed using a machine as shown in FIG. This machine is no different from the development equipment for PS plates, so it is possible to have compatibility with PS plates in the elution process of non-image areas. In FIG. 5, 1 is the plate of the present invention on which a toner image has been formed after completing the electrophotographic process, 2 is a silicone rubber feeding roller that feeds the plate, 3 is shower piping, 4 is an alkaline aqueous solution, and 5 is a non-image A polypropylene brush roller that scrapes off the photosensitive layer of the
is a waste liquid pump, and 7 is tap water. If the photoconductive substance eluted from the photoreceptor at this time is only 3,4,9,10-perylenetetracarboxylic dianhydride, the four carboxyl groups are saponified by the alkali component and solubilized. . Therefore, since it is dissolved in the alkaline aqueous solution together with the alkali-soluble resin, problems such as clogging of mechanical pumps and piping systems will not occur. It goes without saying that the above effects can be obtained even when the photoconductive substance of the photoreceptor contains 3,4,9,10-perylenetetracarboxylic dianhydride and other alkali-soluble substances. do not have. Hereinafter, the present invention will be specifically explained with reference to Examples. Example 1

[Table] The above-mentioned mixture was placed in a glass ball mill and rotated on a ball mill stand for 48 hours to uniformly disperse the mixture. The prepared photosensitive solution was applied onto a grained aluminum plate using a wire bar and dried to produce a printing plate having an electrophotographic photosensitive layer with a film thickness of 4 μm. 3, 4, 9 at this time,
When the shape of 10-perylenetetracarboxylic dianhydride was observed using SEM, it was confirmed that it was amorphous because no clear shape was observed (see Figure 1). On the other hand, when this crystal structure was also measured by X-ray diffraction, it was confirmed that it exhibited the spectral pattern shown in FIG. For this printing plate, the light attenuation characteristics and dark attenuation characteristics of the electrophotographic photosensitive layer were measured using Paper Analyzer SP.
-428 (manufactured by Kawaguchi Electric Co., Ltd.). The measurement conditions are − for optical attenuation characteristics.
The sample was corona charged with a charging voltage of 6 kV, left in the dark for 5 seconds, and then exposed to white light using a tungsten lamp at an exposure dose of 3 Lux. Regarding dark decay characteristics −
Surface potential immediately after corona charging with 6kV charging voltage and
Comparing the surface potential after 60 seconds (1-V60/V0)
The attenuation rate was set to . Next, this printing plate is printed on a direct plate making machine IP-701.
(manufactured by Iwasaki Tsushinki Co., Ltd.) and plate-making using a developer solution set as VP-3, a good plate-made image with little development fog was obtained (electrical property values are shown in Table 1). Furthermore, the printing plate on which this plate-making image was formed was charged with 1% by weight of sodium silicate into the machine shown in Figure 5, and the non-image area was heated at a temperature of 30°C and a conveyance speed of 30 mm/sec of the alkaline aqueous solution. When the elution treatment was carried out, a printing plate with a high-quality plate-making image without stains in the non-image area was obtained. The alkaline aqueous solution after this elution was a green-yellow transparent liquid, and no insoluble matter was observed at all. In this state, when the container capacity of the alkaline aqueous solution was 4 liters, even if 300 plates were eluted with an A3 size plate (310 x 473), the liquid was a green-yellow transparent liquid and the image quality was good. When the printing plate thus obtained was printed on an offset printing machine, a clean printed image was obtained and the printing plate had a printing life of more than 30,000 sheets. Example 2

[Table] The electrophotographic properties and printability were evaluated in the same manner as in Example 1 except that the composition of the mixture was changed as above. The electrophotographic images and printed images showed no fog,
There were no visible stains, the image quality was high, and the print life was 30,000 copies. In addition, when the container capacity of the aqueous alkaline solution was 4 liters, even if 300 plates of A3 size (310 x 473) were eluted, there was no change to a green-yellow transparent liquid.
(The electrical characteristic values are shown in Table 1) Example 3

【table】

[Table] The electrophotographic properties and printability were evaluated in the same manner as in Example 1 except that the composition of the mixture was changed as above. The electrophotographic images and printed images showed no fog,
There were no visible stains, the image quality was high, and the print life was 30,000 copies. (The electrical characteristic values are shown in Table 1) Example 4

【table】

[Table] The electrophotographic properties and printability were evaluated in the same manner as in Example 1 except that the composition of the mixture was changed as above. The electrophotographic images and printed images showed no fog,
There were no visible stains, the image quality was high, and the print life was 30,000 copies. (The electrical characteristic values are shown in Table 1) Example 5

[Table] The electrophotographic properties and printability were evaluated in the same manner as in Example 1 except that the composition of the mixture was changed as above. The electrophotographic images and printed images showed no fog,
There were no visible stains, the image quality was high, and the print life was 30,000 copies. (The electrical characteristic values are shown in Table 1) Example 6

[Table] The electrophotographic properties and printability were evaluated in the same manner as in Example 1 except that the composition of the mixture was changed as above. The electrophotographic images and printed images showed no fog,
There were no visible stains, the image quality was high, and the print life was 30,000 copies. (Electrical characteristic values are shown in Table 1) Comparative example 1

[Table] The electrophotographic characteristics and printability were evaluated in the same manner as in Example 1 except that the composition of the mixture was changed as described above, and it was found that the image formation was incomplete due to the poor sensitivity of the electrophotographic image. Elution of the plate with an alkaline aqueous solution also became incomplete. The shape of 3,4,9,10-perylenetetracarboxylic dianhydride at this time is
When observed with SEM, it was confirmed that it had a needle-like shape as shown in Figure 2, and when the crystal structure was measured by X-ray diffraction, the spectral pattern shown in Figure 4 was confirmed. Therefore, Examples 1 to 4 This is clearly different from the amorphous 3,4,9,10-perylenetetracarboxylic dianhydride used in the above. (Electrical characteristic values are shown in Table 1) Comparative example 2

[Table] When the electrophotographic characteristics and printability were evaluated in the same manner as in Example 1 except that the composition of the mixture was changed as above, it was found that the electrophotographic image had a lot of development fog and the elution with the alkaline aqueous solution was incomplete. Ta. (The electrical property values are shown in Table 1.) Furthermore, since the above perylene pigment is insoluble in an alkaline aqueous solution, the alkaline aqueous solution after elution from the photoreceptor becomes red and cloudy, and the equipment shown in Figure 5 for elution is a pump, piping, etc. This resulted in blockages and malfunctions. Comparative example 3

[Table] When the electrophotographic characteristics and printability were evaluated in the same manner as in Example 1 except that the composition of the mixture was changed as above, it was found that the electrophotographic image had a lot of development fog and the elution with the alkaline aqueous solution was incomplete. Ta. (The electrical property values are shown in Table 1.) Furthermore, since the above perylene pigment is insoluble in an alkaline aqueous solution, the alkaline aqueous solution after elution from the photoreceptor becomes red and cloudy, and the equipment shown in Figure 5 for elution is a pump, piping, etc. This resulted in blockages and malfunctions. Comparative example 4

[Table] When the electrophotographic characteristics and printability were evaluated in the same manner as in Example 1 except that the composition of the mixture was changed as above, it was found that the electrophotographic image had a lot of development fog and the elution with the alkaline aqueous solution was incomplete. Ta. (Electrical characteristic values are shown in Table 1)

〔Effect of the invention〕

In an electrophotographic printing plate in which a printing original plate is obtained by forming a toner image by electrophotography and then eluting the non-image area with an alkaline aqueous solution, the photoconductive substance of the dispersed photoreceptor constituting the printing plate is By using an alkali-soluble pigment, the photoreceptor eluted in the plate-making process has solubility in an alkaline aqueous solution, thereby obtaining a plate-making method that provides high-quality images and takes measures against pollution of waste liquid. was completed.

[Brief explanation of the drawing]

Figure 1 is a SEM photograph showing the amorphous crystal structure of 3,4,9,10-perylenetetracarboxylic dianhydride, and Figure 2 is a SEM photograph showing the amorphous crystal structure of 3,4,9,10-perylenetetracarboxylic dianhydride.
A SEM photograph in place of a drawing showing the needle-shaped crystal structure of 4,9,10-perylenetetracarboxylic dianhydride. FIG. 4 shows an X-ray diffraction spectrum of a needle-shaped 3,4,9,10-perylenetetracarboxylic dianhydride, and FIG. 5 shows an elution device for eluating the photosensitive layer. In Fig. 5, 1 is the plate of the present invention on which a toner image has been formed after the electrophotographic process, 2 is a silicone rubber feed roller that feeds the plate, 3 is shower piping, 4 is an alkaline aqueous solution, and 5 is a non-image. A polypropylene brush roller that scrapes off the photosensitive layer of the
is a waste liquid pump, and 7 is tap water.

Claims (1)

[Claims] 1 At least one photoconductive substance is 3, 4,
A photosensitive layer containing 9,10-perylenetetracarboxylic dianhydride whose particle shape is amorphous in an alkali-soluble resin is formed on a support having at least a conductive layer. Printing plate for electrophotographic printing.