JPS60235143A - Original printing plate for electrophotographic engraving - Google Patents

Abstract

PURPOSE:To improve sensitivity and resistance to printing and to obtain satisfactory printed matter having no ground stains by providing a photosensitive layer consisting of two layers; an electric charge generating layer contg. a specific azo pigment and an electric chrage transfer layer contg. an electric charge transfer layer and alkali soluble resin on a conductive substrate. CONSTITUTION:The photosensitive layer 2 consisting of the two layers; the electric charge generating layer 3 contg. the azo pigment expressed by the formula (A is the residual coupler group) and the electric charge transfer layer 4 contg. the charge transfer material and alkali soluble resin is provided on the conductive substrate 1. Such layer 2 is subjected to formation of an electrostatic latent image, toner developing and heat fixing, by which a toner image 5 is obtd. Such layer is then processed by an alkali eluting liquid, by which the hydrophilic surface of the substrate 1 is exposed and the image part coated by the oleophilic toner is left. Oil ink sticks only to the image part and the sharp image having no ground stains is obtd. if the original printing plate obtd. in such a way is used for, for example, lithographic printing. Such layer 2 has high sensitivity, permits direct photoengraving with various light sources and has excellent resistance to printing.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a novel printing plate that can be made by electrophotography. More specifically, in a new printing plate containing a specific azo pigment, an electrostatic latent image obtained by charging and subsequent image exposure is developed with toner and fixed to obtain a toner image, and then the non-image area is "Removal of photosensitive layer by elution": Relates to printing plates for plate making.

BACKGROUND OF THE INVENTION Hitherto, as planographic printing original plates, those using photosensitive resins or silver oxide photosensitive materials have been known.

However, from Kotobuki, lithographic printing plates using photosensitive resin have high printing durability, but have low sensitivity, and so-called direct plate making is not possible, and it is necessary to create negatives or positives from the original using silver halide film. However, this method requires a lot of equipment and takes a long time to make the plate, which has many drawbacks.

Printing plates using diffusion transfer development or hardening development methods of silver halide photosensitive materials can still be directly plate-made, but they have the drawbacks of low printing durability and high cost per sheet.

As printing plates for direct plate making using electrophotography, for example, Tokko Sho 47-4761.0, Tokko Sho 4B-4
0002, Special Publication No. 48-18325, Special Publication No. 51-15
As shown in Japanese Patent Publication No. 76.6 and Japanese Patent Publication No. 51-25761, a printing plate having an outer zinc oxide-resin dispersion system is known. After forming a toner matrix on this printing plate by electrophotography, it is treated with an acidic aqueous solution containing, for example, a ferrocyanate salt in order to make non-image areas hydrophilic. Printing plates made in this way peel off due to the mechanical pressure applied during printing and the penetration of dampening water into the photosensitive layer and conductive layer, destroying the hydrophilic layer on the surface. Reprint power is 5,000 ~
It was about 10,000 schools.

However, dye sensitization is performed on zinc oxide/resin dispersion printing plates to make them sensitive in the visible light region, but the sensitivity is still insufficient for practical use in the long wavelength light region of 600 nm or more. Therefore, low output and inexpensive He-Ne
It has the disadvantage that it cannot be exposed using a l/- laser or a semiconductor laser.

On the other hand, the special public service No. 37-17162, the special public service No. 38-7758
, JP 46-39405, JP 52 = 2437, JP 56-107246, JP 55-105254,
JP-A-55-153948, JP-A-55-16125,
JP-A-57-147656, JP-A-56-146145
, JP-A No. 57-161863, for example, a layer consisting of an organic photoconductive compound and an alkali-soluble resin, or a phthalocyanine pigment on a hydrophilic conductive support such as a grained aluminum plate. A printing original plate for electrophotographic engraving is disclosed which is provided with a layer in which a charge-generating pigment such as E.g. There is. This type of printing original plate is made by forming a toner image on the photosensitive layer using an electrophotographic method, and then eluting and removing the photosensitive layer in the non-image area with an alkaline solution.It is a printing plate with high printing durability using direct platemaking. However, as a photoreceptor for electrophotography, it has low sensitivity, resulting in slow platemaking speed, and has the disadvantage of requiring the use of a high-output light source.

Object The object of the present invention is to solve the above-mentioned problems of the conventionally known printing original plates for electrophotographic engraving, and to provide a printing original plate with particularly high sensitivity and high printing durability.

Structure The printing original plate for electrophotolithography of the present invention comprises two charge-generating layers containing an azo pigment represented by the following general formula (D) and a charge-transporting layer containing a charge-transporting substance and an alkali-soluble resin on a conductive support. It is characterized by being provided with an electrophotographic photosensitive layer consisting of layers.

General formula (1) The basic structure of the printing original plate for electrophotolithography of the present invention is expressed as
As shown in the figure. Here, 1 is a conductive support, and a charge generation layer 3 and a charge transport layer 4 are laminated on the soil to form an electrophotographic photosensitive layer 2. The charge generation layer 3 and the charge transport layer 4 can also be stacked upside down (5).

Couplers for the azo pigment used in the charge generation layer 3 include:
For example, compounds having a phenolic hydroxyl group such as phenols and naphthols, aromatic amino compounds having an amine group, aminonaphthols having an amine group and a phenolic hydroxyl group, or fatty acids or aromatic, group 3, otonol compounds. A compound having a ketone group (active methylene group) is used, and preferably the coupler residue A has the following general formula (T
I), (III), (IV), (V), (Vl), (
■) Selected from the group represented by.

[In the formula, R1 is hydrogen, an alkyl group, a phenyl group, or a substituent thereof; Substituted product, heterocyclic group (6) Substituted product thereof, or styryl group or substituted product thereof, R3 is hydrogen, alkyl group, phenyl group, or a substituted product thereof, R2 and R3 are A ring may be formed together with the carbon atom to which the straw is attached.

)] +471 (R4 in formulas (1) and (IV) represents a substituted or unsubstituted hydrocarbon group.) Ar1 (In the formula, R5 haalkyl group, carnogumoyl group, carboxyl group or an ester thereof Expression, also A r i
represents a hydrocarbon ring group or a substituted product thereof.

60 60 (wherein R6 is a hydrocarbon group or a substituted product thereof, Ar
2 represents a hydrocarbon ring group or a substituted product thereof. ) The hydrocarbon ring group for X in the general formula used in the present invention includes, for example, a benzene ring, a naphthalene ring, etc.; the heterocycle includes, for example, an indole ring, a carbazole ring,
Hydrocarbon ring groups such as benzofuran rings, Y or R2 include phenyl group, naphthyl group, anthryl group,
Examples of heterocyclic groups such as pyrenyl group include pyridyl group, chenyl group, furyl group, indolyl group, benzofuranyl group,
Examples of rings that can be formed by the truncated R2 and R3 together with the carbon atoms to which they are bonded, such as a carbazolyl group and a dibenzofuranyl group, include fluorene rings.

More R4! Examples of the hydrocarbon group in f or R6 include alkyl groups such as methyl, ethyl, propyl and butyl groups, aralkyl groups such as benzyl, aryl groups such as phenyl, and substituted products thereof.

As substituents in the hydrocarbon group of R4t or R6,
Alkyl groups such as methyl group, ethyl group, propyl group, butyl group, alkoxy groups such as methoxy group, ethoxy group, propoxy group, butoxy group, halokene atoms such as chlorine atom, bromine atom, hydroxyl group, nitro group, etc. Can be mentioned.

(9) As a substituent on the phenyl group or the ring of
Substituents on the ring that can be formed by 3 include alkyl groups such as methyl group, ethyl group, propyl group, butyl group, alkoxy groups such as methoxy group, ethoxy group, 70 lopoxy group, butoxy group, chlorine atom, bromine atom, etc. halokene atoms, dimethylamine groups, diethylamino groups, dialkylamino groups such as nobenzylamino groups, trifluoromethyl groups, halomethyl groups, nitro groups, cyanogen groups, carboxyl groups, or esters thereof; Hydroxyl group, sulfonic acid group (-SO3Na
). Furthermore, the hydrocarbon ring groups in Ar1 and Ar2 include phenyl and naphthyl groups, and substituents for these groups include alkyl groups such as methyl, ethyl, propyl, and butyl; Methoxy group, ethoxy group, propoxy group, butoxy group, alkoxy group such as nitro group, chlorine atom, bromine atom, etc. (10) Halokane atom, cyano group, dimethylamino group, soalkylamino group such as diethylamine group, etc. can be exemplified.

The azo pigment used in the present invention is, for example, JP-A-55-
73057 and is described in Japanese Patent Application Laid-Open No. 55-69654. Examples of these azo pigments are as follows.

(Left below) (11) (13) (12) (14) The charge generation layer 3 is a layer mainly composed of an azo pigment represented by the general formula (1), but may contain a binder if necessary. I can do it. In this case, the proportion of the azo pigment in the charge generation layer is preferably at least 30 weights. Since the printing original plate of the present invention elutes the non-image area during the plate-making process, when using a binder, for example, an alkali-soluble resin such as a styrene-maleic anhydride copolymer or a novolak type phenolic resin (after ) is preferable. However, if the proportion of the binder is small, it is also possible to use other resins. The thickness of the charge generation layer 3 is preferably 001 to 5, more preferably 0.
05-2 μm. If the thickness is less than 0.01 μm, charge generation will not be sufficient, and if the thickness is 5 μm or less, the residual potential will be too high for practical use.

The charge transport layer 4 is formed of a charge transport substance and an alkali-soluble resin. Charge transport substances include hole transport substances and electron transport substances, and hole transport substances include, for example, 2
．． 5-bis(4-diethylaminophenyl) -1,3
,4-oxadiazole, 2°(17) 5-bis(4-(4-diethylaminostyryl)phenyl:] -]1.3.4-oxasoazole 2-(9-
Oxadiazole compounds such as ethylcarbazolyl-3-)-5-(4-diethylaminophenyl)-1,3,4-oxadiazole, 2-vinyl-4-(2-chlorophenyl)-5-( Oxazole compounds such as 4-diethylamino)oxazole, 2-(4-diethylaminophenyl)-4-phenyloxazole, 1-phenyl-3-(4-diethylaminostyryl)-5-(4-
diethylaminophenyl)pyrazoline, 1-phenyl-
Pyrazoline compounds such as 3-(4-dimethylaminostyryl)-5-(4-trimethylaminophenyl)pyrazoline, 2,2'-dimethyl-4,4'-bis(diethylamino)triphenylmethane, 1,1- Diphenylmethane compounds such as bis(/1-)benzylaminophenyl)gulonone, tris(4-diethylaminophenyl)methane, 9-(4-trimethylaminobenzylidene)fluorene, 3-(9-fluorenyritene)-9- Fluorene compounds of ethylcarbasolnato (18), styrylanthracene compounds such as 9-(4-diethylaminostyryl)anthracene, 9-broth, -10-(4-noethylaminostyryl)an I-racene, 1,2- Nostyrylbenzene compounds such as bis(4-diethylaminostyryl)benzene, 1,2-bis(2,4-nomethoxystyryl)benzene, 9-ethylcarbasol-3-fuldehyde 1-methyl-1-phenylhydrazone, 9- Ethylcarbazole-
3-Aldehyde 1-bentlu-1-phenylhydrazone, 4-noethylaminobenzaldehyde 1,1-diphenylhydrazone, 2,4-sometogysibenzaldehyde 1-bentlu-1-phenylhydrazone, 4-nonphenylaminobenzaldehyde 1-methyl- Hydrazone compounds such as 1-phenylhydrazone, 4-diphenylaminostilbene, 4-nobennolaminostilbene, 4-
Notrylaminostilbene and other stilbene compounds '4h
, 1-(/I-diphenylaminostyryl)naphthalene, , 1-(4-nobenzylaminostyryl)naphthalene and other styrylnaphthalene compounds, 4'-diphenylamino-α-phenylstilbene, 4'-methylphenylamino-α -Phenylstilbene i and (7) α-phenylstilbene compound, 3-styryl-9-ethylcarbazole, 3-(4-noethylamino)styryl-9-
Styryl carbazole compounds such as ethyl carbazole are used.

Examples of the electron transport substance include chloranil, zolomuanil, tetracyanoethylene, tetracyanoquinone dimethane, 2,4,7-dolinitro-9-fluorenone, 2,4,5.7-titranitro-9-fluorenone, 2,4, 5.7-Titranitroxanthone, 2,4
．． 8-) linitrothioxanthone, 2,6.8=trinitro-4H-indeno[1,2-b+]thiophene-4
-On, 1,3.7-1-! Examples include J-nitrosyhenzothiophene-5,5-nooxide.

The alkali-soluble resin used in the charge transport layer 4 refers to a resin that becomes soluble in an aqueous solution or an alcoholic solvent by adding an alkali. For the purposes of the present invention, in addition to properties such as film-forming properties, electrical properties, and adhesion strength to a support, solubility properties are particularly important for these resins. Examples of resins having such characteristics include styrene-maleic anhydride copolymer, styrene-methacrylic acid-methacrylate-1 copolymer, methacrylic acid-methacrylate-1 copolymer, and phenol resin. be done.

Examples of phenolic resins include phenol, 0-cresol, m-cresol, p-cresol, ethylphenol, isopropylphenol, t-butylphenol, t-cresol, and t-cresol.
-amylphenol, hexylphenol, t-octylphenol, cyclohegycylphenol, 3-methyl-4-chloro-6-t-butylphenol, isopropylcresol, t-butylcresol, t-amylcresol, hexylcresol, t-octylcresol and a novolak type resin (21) obtained by condensing at least one type of substituted phenols such as cyclohexyl cresol with aldehydes such as formaldehyde, acetaldehyde P17 chlorein, crotonaldehyde, and furfural under acidic conditions.

The charge transport layer 4 is a layer mainly composed of a charge transport substance and an alkali-soluble resin, and the ratio of the charge transport substance in the layer is 10 to 10.
70 weight class, 20 to 60 weight class. When the proportion of the charge transport substance is below this range, almost no charge is transported, and when it is above this range, the mechanical strength of the layer is extremely poor and cannot be put to practical use. Generally, the thickness of the charge transport layer 4 is 2 to 50 μm, preferably 3 to 20 μm.

Below this range, the amount of charge will be insufficient, and above this range, the residual potential will be high and it will take a long time to elute the layer.
Very practical.

The charge transport layer 4 can contain a plasticizer.

Effective plasticizers include, for example, phthalic acid esters such as dimethyl phthalate, diethyl phthalate, and dibutyl phthalate, and glycol esters such as dimethyl glycol phthalate and ethyl phthalyl ethyl glycolate.

These plasticizers can be contained within a range that does not significantly deteriorate the electrostatic properties and alkali solubility of the photoconductive layer (22).

The conductive support 1 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-aluminum plate, a chromium-lead plate. -Iron plate, chrome-
A conductive support with a hydrophilic surface such as a tri-metal plate such as a copper-stainless steel plate is used, and its thickness is from 01 to
One job is preferred.

Surface treatments such as graining, immersion in an aqueous solution of sodium silicate, potassium fluorozirconate, phosphate, etc., or anodizing, especially in the case of supports with a surface of aluminum oxide, etc. It is good to see that this is being done. As shown in U.S. Pat. No. 2,714,066, an aluminum plate is grained and then immersed in an aqueous solution of sodium l-IJ silicate;
It is also preferable to carry out an anodic oxidation treatment and then immersion treatment in an aqueous solution of an alkali metal silicate as disclosed in the May 7-5125 publication.

In the anodizing process, aluminum is heated in an electrolytic solution containing, for example, a solution of an inorganic acid such as phosphoric acid, chromic acid, sulfuric acid, boric acid, etc., or an organic acid such as oxalic acid, sulfamic acid, or a salt thereof. This is carried out by passing an electric current through the plate as an anode.

To produce the electrophotographic printing plate of the present invention, first, the pigment represented by the general formula (1) and a binder, if necessary, are mixed with, for example, tetrahydrofuran, dioxane, trimethylformamide, acetone methyl ethyl ketone, ethylene glycol monomethyl The coating liquid is mixed in an organic solvent such as ether, ethylene glycol monoethyl ether, ethyl acetate, methyl acetate, toluene, or a halogenated hydrocarbon and uniformly dispersed using a dispersing means such as a ball mill or an ultrasonic dispersion machine. The charge generation layer 3 is provided by coating on a support and drying. Next, a solution in which a charge transport substance and an alkali-soluble resin are dissolved in the same organic solvent as above is applied onto the charge generation layer and dried to form the charge transport layer 4.

The plate making of the original printing plate for electrophotographic engraving of the present invention is first carried out according to the usual electrophotographic method, uniformly charged in a dark place using a corona charger, etc., and then charged with a tungsten lamp, a halogen lamp, a xenon lamp, or a fluorescent lamp. An electrostatic latent image is formed by reflective image exposure using a light source such as a lamp, contact image exposure through a transparent positive film, or scanning exposure using a laser beam such as an e-Ne laser, an argon laser, or a semiconductor laser. This electrostatic latent image is developed with toner and fixed by heating to obtain a toner image on the electrophotographic photosensitive layer (FIG. 2).

Next, when the printing plate on which the toner image has been formed is immersed in an alkaline eluent, the electrophotographic photosensitive layer (charge generation layer and charge transport layer) in the non-image area is masked by the toner image. ) is dissolved and removed, the hydrophilic surface of the conductive support is exposed, and only the toner image portion remains, allowing a good printing plate to be obtained (FIG. 3).

The eluent used here is, for example, an alkaline aqueous solution of an inorganic salt such as sodium silicate, thorium phosphate, sodium hydroxide, sulfur and lithium carbonate, or an organic amine such as ethanolamine and ethylenediamine. An alkaline aqueous solution containing the above-mentioned organic solvent such as ethanol, benzyl alcohol, ethylene glycol, or glycerin, or a solution to which a surfactant or the like is added is used.

In the printing plate of the present invention, after the toner image is formed, the non-image area is dissolved and removed in the eluent, so the toner components include:
It is preferable that this eluate contains a resin component having resist properties.

This resin component may be anything that is insoluble in the eluate, such as acrylic resin using methacrylic acid, methacrylic acid ester, vinyl acetate resin, vinyl acetate and ethylene, or vinyl chloride. Copolymers, vinyl chloride resins, vinylidene chloride resins, vinyl acetal resins such as polyvinyl butyral, polystyrene, copolymers of styrene and butadiene, methacrylic acid esters, polyethylene, polypropylene and their chlorides,
There are polycarnate resins, polyester resins, polyamide resins, phenolic resins, kinreno resins, (26) alkyd resins, waxes, polyolefins, and waxes.

The printing original plate of the present invention may also contain a quinone diat compound such as 0-naphthoquinonesoazide or a diazo compound for the purpose of increasing the solubility of the electrophotographic photosensitive layer by full-surface exposure after toner peak formation.

In the printing original plate of the present invention, after the plate-making process is completed, the conductive substrate with a hydrophilic surface is exposed in the non-image area, and the image area covered with the oleophilic toner remains. It adheres only to the image area, resulting in good printed matter without background stains.

In addition, the printing original plate of the present invention has the following characteristics compared to conventional printing original plates:
Direct plate making is possible with a variety of light sources such as a He-Ne laser and a semiconductor laser, and the printing plates obtained thereby have high printing durability.

Next, the present invention will be explained in more detail with reference to Examples.

Hiko, all "parts" in the examples represent parts by weight.

Examples] 1 part of azo pigment flat 1 was mixed with 0.0 parts of m-cresol-phenol copolymerized novolac resin (MP-707 manufactured by Toden Chemical Co., Ltd.).
667 parts of a 74 wt% tetrahydrofuran solution was ground and mixed in a ball mill, and the resulting dispersion was mixed to a thickness of about 0.25 mm.
The grained aluminum plate is coated with 80%
It was dried at .degree. C. for 10 minutes to form a charge generation layer with a thickness of about 1 .mu.m.

2,5-bis(
09 parts of 4-diethylaminophenyl)-1,3,4-oxadiazole, 1.8 parts of styrene-maleic anhydride copolymer (manufactured by Aldrich Chemical Company, copolymerization molar ratio: 1), and 132 parts of tetrahydrofuran. A printing original plate for electrophotographic engraving of the present invention was prepared by applying a mixed and dissolved solution of the following and drying it at 80° C. for 20 minutes to form a charge transport layer having a thickness of about 10 μm.

This printing original plate was tested at -6kV using an electrostatic copying paper testing device (manufactured by Kawaguchi Electric Seisakusho Co., Ltd.: Model SL"428).
After performing corona discharge for 20 seconds to make it negatively charged,
】Surface potential V at that time after being left in a dark place for 0 seconds. (volts), then irradiate the surface with light using a tungsten lamp at an illuminance of 45 lux, and the surface potential becomes V. The half-reduction exposure amount E1/2 (lux/second) was calculated based on the time at No. 1. Table this result.
Shown in 1.

Next, this original printing plate was applied to an electronic copying plate making machine (Ricoh S-1).
A clear toner image was formed on the charge transport layer by charging, imagewise exposure, development and fixing.

This original plate was prepared using 70 g of thorium metasilicate and 14 g of glycerin.
0m1. Ethylene glycol 550mJ and ethanol 150m/! The electrophotographic photosensitive layer in the non-image area to which toner was not attached was removed by immersing it in a solution for 1 minute and then washing it with water while gently brushing it.

The printing plate made in this way is then printed on an offset printing machine (
When printing was carried out using the conventional method (AP-1310 model manufactured by Ricoh), more than 50,000 clear prints could be printed.

Examples 2 and 3 The electrophotographic plate of the present invention was prepared in the same manner as in Example 1, except that the compounds shown in Table 1 were used as the azo pigment used in the charge generation layer and the charge transport substance used in the charge transport layer, respectively. Created the original printing plate, and V. and Ei/2 were measured.

The above results are shown in Table-1.

(The following is a blank space) (30) Example 4 One part of Azo Pigment Flat 4 was mixed with 0.0 parts of m-cresol-phenol copolymerized novolac resin (manufactured by Toden Kagaku: MP-707).
66.7 parts of a 74wt% tetrahydrofuran solution was pulverized and mixed in a ball mill, and the resulting dispersion was mixed to a thickness of about 0.25%.
Coated on a grained aluminum plate of 8 mm.
It was dried at 0° C. for 10 minutes to form a charge generation layer with a thickness of about 1 μm.

3-styryl- as a charge transport substance on this charge generation layer.
15 parts of 9-ethylcarbazole, m-cresol-phenol copolymerized novolak resin (manufactured by Toden Chemical: MP-70
7) Apply a mixed solution of 3.0 parts and 120 parts of tetrahydrofuran, heat at 80°C for 2 minutes, and then heat for 10 minutes.
A charge transporting layer having a thickness of about 10 μm was formed by drying at 0° C. for 10 minutes to prepare a printing original plate for electrophotolithography of the present invention. Regarding this printing original plate, as in Example 1, ■. and E1/? The results of the measurements are shown in Table 2.

Next, after forming a toner image on the electrophotographic photosensitive layer 2 of this printing original plate in the same manner as in Example 1, about 40% of meta(32) was added to a solution consisting of 25 parts of thorium silicate and 100 parts of water.
The film was immersed for 5 seconds, and then washed with water by gently brushing to remove the electrophotographic photosensitive layer in the non-image area.

When the printing plate thus prepared was printed on an offset printing machine, 50,000 clear printed matter could be printed on an I-mail.

Examples 5 to 8 The electrophotographic plate of the present invention was prepared in the same manner as in Example 4, except that the compounds shown in Table 2 were used as the azo pigment used in the charge generation layer and the charge transport substance used in the charge transport layer, respectively. Created the original printing plate, and V. and E1/2 were measured.

The above results are shown in Table-2.

(Margin below) (33)

[Brief explanation of drawings]

FIG. 1 is a diagram showing the basic structure of the printing original plate for electrophotographic engraving of the present invention. Figures 2 and 3 are diagrams explaining the plate-making process of the printing original plate of the present invention, where Figure 2 shows a state in which a toner image has been formed, and Figure 3 shows a state in which a non-image area has been eluted and removed. . 1... Conductive support, 2... Electrophotographic photosensitive layer, 3...
... Charge generation layer, 4... Charge transport layer, 5... Toner image. Patent applicant Rico Co., Ltd. - (35) Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] An electrophotographic photosensitive layer consisting of two layers, a charge generation layer containing an azo pigment represented by the following general formula (1) and a charge transport layer containing a charge transport substance and an alkali-soluble resin, was provided on a conductive support. A printing original plate for electrophotographic engraving characterized by the following.