JPS60239756A - Printing original plate for electrophotographic engraving - Google Patents

Abstract

PURPOSE:To obtain a printing original plate having high sensitivity and high printing resistance by providing an electrophotographic sensitive layer consisting of two layers: an electric charge generating layer contg. the azo pigment expressed by formula I and an electric charge transfer layer contg. an electric charge transfer material and alkali soluble resin on a conductive base. CONSTITUTION:The basic constitution of the printing original plate for electrophotographic engraving consists of the electrophotographic sensitive layer 2 formed by laminating the charge generating layer 3 and further the charge transfer layer 4 on the conductive base 1. The reverse lamination of the layer 3 and the layer 4, i.e., the latter on the former, is also possible. The electrophotographic sensitive layer (the charge generating layer and charge transfer layer) in the non-image part which is not masked by a toner image is dissolved away and the hydrophilic surface of the conductive base is exposed so that the image part coated with the lipophilic toner remains on the printing plate obtd. by forming the toner image on the original plate when said printing plate is immersed into an alkaline eluting soln. Thus oil ink sticks only on the image part in ordinary lithographic printing and the good printed matter having no ground stains is obtd.

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, with 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 This invention relates to a printing plate that is made by eluating and removing a photosensitive layer.

BACKGROUND ART Conventionally, as planographic printing original plates, those using photosensitive resins or silver halide photosensitive materials have been known.

However, although lithographic printing plates made of photosensitive resin have high printing durability, they have low sensitivity and cannot be used in so-called direct plate making, requiring the process of first creating negatives or positives from originals using silver halide film. However, there are drawbacks such as the need for large-scale equipment and the time required for plate making.

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

As printing plates for direct plate making using electrophotography, for example, Japanese Patent Publication No. 47-47610, Japanese Patent Publication No. 4.8-4
0002, Special Publication No. 48-18325, Special Publication No. 51-15
766 and Japanese Patent Publication No. 51-25761 are known printing plates having a zinc oxide-resin dispersion system. After forming a toner image on this printing plate by electrophotography, it is treated with an acidic aqueous solution containing, for example, a ferrocyan salt in order to make the non-image area 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. Printing durability is 5,000 to 1
It was about 0,000 sheets.

In addition, zinc oxide/resin dispersion printing plates are dye sensitized in order to have sensitivity in the visible light region, but even so, they do not exhibit sensitivity sufficient for practical use in the long wavelength light region of 600 nm or more. Therefore, low-power and inexpensive He-Ne
The disadvantage is that exposure cannot be performed using a laser or 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 55-165254,
JP-A-55-153948, JP-A-55-16125,
JP-A-57-147656, JP-A-56-, . 1461
45, JP-A No. 57-161863, etc., disclose a layer consisting of an organic photoconductive compound and an alkali-soluble resin, or a phthalocyanine pigment, etc. on a hydrophilic conductive support such as a grained aluminum plate. A printing original plate for electrophotographic engraving is disclosed, which has a layer in which a charge-generating pigment is dispersed in an alkali-soluble resin, or a layer sensitized by adding an electron-withdrawing substance or an electron-donating substance to this dispersed layer. 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. Although it has the advantage of producing a printing plate, it has low sensitivity as a photoreceptor for electrophotography, so
It has the drawbacks of slow plate making speed and the need to use a high output light source.

The purpose of the present invention is to solve the above-mentioned problems of the conventionally known printing original plates for electrophotolithography, and to provide a printing plate with particularly high sensitivity and high printing durability. Our goal is to provide the original printing version.

Structure The printing original plate for electrophotolithography of the present invention comprises 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 on a conductive support. It is characterized by being provided with an electrophotographic photosensitive layer consisting of two layers.

General formula (1) (However, A represents a Kaglar residue.) The basic structure of the printing original plate for electrophotographic engraving of the present invention is shown in FIG.

Here, reference numeral 1 denotes a conductive support, on which a charge generation layer 3 and a charge transport layer specification 4 are laminated to form an electrophotographic photosensitive layer 2.

The charge generation layer 3 and the charge transport layer 4 can also be stacked upside down.

The azo pigment used in the charge generation layer 3 is Cassirer.
For example, compounds with a phenolic hydroxyl group such as phenols and naphthols, aromatic amino compounds with an amino group, aminonaphthols with an amino group and a phenolic hydroxyl group, or aliphatic or aromatic enolic ketone groups (active methylene group). ) is used,
Preferably, the cassilla residue A is selected from the group represented by the following general formulas (■), (to), (to), (to), (to), (to), and (b).

[In the formula, R1 is hydrogen, an alkyl group, a phenyl group, or a substituent thereof; X is a hydrocarbon ring or a substituent thereof; a heterocycle or a substituent thereof; heterocyclic group or substituted products thereof,
Or it represents a styryl group or a substituted product thereof, R3 hydrogen, an alkyl group, a phenyl group, or a substituted product thereof,
Alternatively, R2 and R3 may form a ring with the carbon atom to which they are attached. )] -rn (R4 in Formula 1 and the Foundation represents a substituted or unsubstituted hydrocarbon group.) r 1 (In the formula, R5 is an alkyl group, a carboxylic group, a carboxyl group, or an ester thereof. 60 60 (wherein, R6 is a hydrocarbon group or a substituent thereof, Ar represents a hydrocarbon group or a substituent thereof,
2 represents a hydrocarbon ring group or a substituted product thereof. ) Examples of the hydrocarbon ring for X in the general formula used in the present invention include a benzene ring and a naphthalene ring; examples of the heterocycle include an indole ring, a carbazole ring,
Hydrocarbon ring groups such as benzofuran ring for 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, carbazolyl group, and dibenzofuranyl group, and as rings that R2 and R3 can form together with the carbon atoms to which they are bonded, An example is a fluorene ring.

Furthermore, examples of the hydrocarbon group for R4 or R6 include alkyl groups such as methyl, ethyl, propyl, and butyl, aralkyl groups such as benzyl, aryl groups such as phenyl, and substituted products thereof. R4
Alternatively, substituents on the hydrocarbon group of R6 include alkyl groups such as methyl group, ethyl group, propyl group, butyl group, alkoxy groups such as methoxy group, ethoxy group, propoxy group, butoxy group, chlorine atom, bromine atom, etc. Examples include halogen atoms, hydroxyl groups, and nitro groups. As a substituent on the phenyl group of R1 or the ring of
Substituents on the ring that can be formed include alkyl groups such as methyl, ethyl, propyl, and butyl; alkoxy groups such as methoxy, ethoxy, propoxy, and butoxy; halogens such as chlorine and bromine; atoms, noalkylamino groups such as trimethylamino groups and diethylamino groups, dialkylamino groups such as dibenzylamine 7 groups, halomethyl groups such as trifluoromethyl groups, nitro groups, cyan groups, carboxyl groups or their esters, hydroxyl groups, sulfonic acid groups (-5O5Na) and the like. Furthermore, examples of the hydrocarbon ring group in Ar1 or Ar2 include a phenyl group and a naphthyl group, and examples of substituents on these groups include alkyl groups such as a methyl group, an ethyl group, a propyl group, and a butyl group;
Examples include alkoxy groups such as methoxy, ethoxy, zolo Ioxy, and butoxy groups, halokene atoms such as nitro, chlorine, and bromine, and dialkylamino groups such as cyano, trimethylamino, and noethylamino groups. .

The azo pigment used in the present invention is, for example, JP-A-57-
It is described in No. 202545. Examples of these azo pigments are as follows.

(Hereinafter, blank space) The charge generation layer 3 is a layer mainly composed of an azo pigment represented by the general formula (1), but can contain a binder if necessary. In this case, the proportion of the azo pigment in the charge generation layer is preferably 30% by weight or more. In order to prevent non-image areas from being eluted during the plate-making process, the printing original plate of the present invention uses a binder such as an alkali-soluble resin such as a styrene-maleic anhydride copolymer or a novolac type phenol resin (after ) is preferably used. However, if the proportion of the binder is small, it is also possible to use other resins. Further, the thickness of the charge generation layer 3 is preferably 001 to 5 μm, more preferably 005 μm.
~2 μm. If the thickness is less than 0.001 μm, charge generation will not be sufficient, and if it is more than 5 μm, 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, 2,5-bis(4-(4-diethylaminostyryl)phenyl)-1,3,4-oxadiazole, 2-(9-ethylcarbazole-3-)
-5-(4-diethylaminophenyl)-1,3,4-
Oxadiazole compounds such as oxadiazole, 2-
Oxazole compounds such as vinyl-4-(2-chlorophenyl)-5-(4-diethylamino)oxazole, 2-(4-diethylaminophenyl)-4-phenyloxazole, 1-phenyl-3-(4-diethylaminostyryl) -5-(4-diethylaminophenyl)pyrazoline, 1-phenyl-3-(4-dimethylaminostyryl)-5-(4-dimethylaminophenyl)pyrazoline and other pyrazoline compounds, 2,2'-dimethyl-4,
4'-bis(diethylamino)triphenylmethane, 1
．． Diphenylmethane compounds such as 1-bis(4-dibenzylaminophenyl) methane, 9-(4-dimethylaminobenzylidene)fluorene, 3-(9-fluorenonedine) )-9-ethylcarbasol and other fluorene compounds; 9-(4-diethylaminostyryl)anthracene and 9-zolomu1O-(4-diethylaminostyryl)anthracene and other styryl anthracene compounds;
Distyrylbenzene compounds such as 1,2-bis(4-diethylaminostyryl)benzene and 1,2-bis(2,4-dimethoxystyryl)benzene, 9-ethylcarbazole-3-aldehyde 1-methyl-1-phenylhydrazone , 9-ethylcarbazole-3-aldehyde 1-
Bennol-l-phenylhydrazone, 4-noethylaminobe/dualdehyde 1,1-diphenylhydrazone, 2
,4-dimethoxybenzaldehyde 1-benzyl-]-
Hydrazone compounds such as phenylhydrazone, 4-nophenylaminobenzaldehyde 1-methyl-1-phenylhydrazone, 4-nophenylaminostilbene, 4-
Stilbene compounds such as nopendylaminostilbene and 4-notrylaminostilpeno; styrylnaphthalene compounds such as 1-(4-diphenylaminostyryl)naphthalene and 1-(4-dibenzylaminostyryl)naphthalene; 4'-diphenyl α-phenylstilpene compounds such as amino-α-phenylstilbene, 4'-methylphenylamino-α-phenylstilbene, 3-styryl-9-ethylcarbazole, 3-(4-diethylamino)styryl-9-ethylcarba Styrylcarbazole compounds such as Sol are used.

Examples of electron transport substances include chloranil, bromoanil, tetracyanoethylene, tetracyanoquino/
Tumethane, 21417-) I) = 0-9-fluorenone, 2,4,5.7-tetranitro-9-fluorenone, 2.4,5.7-titranitroxanthone,
2.4.8-) linitrothioxanthone, 2,6.8-
) dinitro-4H-indeno[1,2-b]]thiophene-4-off 11317-to'J nitrodipenzothiophene-5,5-dioxide, and the like.

The alkali-soluble resin used in the charge transport layer 4 refers to a resin that becomes soluble in an aqueous or 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 copolymers, styrene-methacrylic acid-methacrylate copolymers, methacrylic acid-methacrylate copolymers, and phenol resins.

Examples of phenolic resins include phenol, 0-cresol, m-cresol, p-cresol, ethylphenol, isopropylphenol, t-butylphenol, and t-cresol.
-amylphenol, hexylphenol, t-octylphenol, cyclohexylphenol, 3-methyl-4-chloro-6-butylphenol, impropylcresol, 1-butylcresol, t-amylcresol, hexylcresol, t-octylcresol and A novolak type resin is used which is obtained by condensing at least one substituted phenol such as cyclohexyl cresol with an aldehyde such as formaldehyde, acetaldehyde, acrolein, crotonaldehyde, or 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% by weight, and 20 to 60% by weight for good performance. 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 so poor that it cannot be put to practical use. Further, 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 is insufficient, and above this range, the residual potential becomes high and it takes a long time to elute the layer, making it impractical.

The charge transport layer 4 may 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 otarylethyl glycolate.

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

The conductive support 1 used in the present invention is an aluminum plate, a zinc plate, a bimetal plate such as a copper-aluminum plate, a copper-stainless steel plate, a chrome-copper plate, or a chromium-copper-aluminum plate, a chromium-lead-iron plate. , chromium-
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 0.1
~1Wan is preferred.

In addition, especially in the case of a support having an aluminum surface, surface treatments such as graining, dipping in an aqueous solution of sodium silicate, potassium fluorozirconate, phosphate, etc., or anodizing are performed. Preferably. Further, as shown in U.S. Pat. No. 2,714,066, an aluminum plate immersed in an aqueous sodium silicate solution after graining,
After anodizing as shown in Publication No. 125,
Also preferred are those treated by immersion in an aqueous solution of alkali metal silicate.

The above-mentioned anodizing treatment is performed by applying an electric current using an aluminum plate as an anode in an electrolytic solution consisting of a solution of an inorganic acid such as phosphoric acid, chromic acid, sulfuric acid, or boric acid, or an organic acid such as oxalic acid or sulfamic acid, or a salt thereof. It is carried out by flowing.

To produce the electrophotographic printing plate of the present invention, first, the pigment represented by the general formula (I) and a binder, if necessary, are mixed with, for example, tetrahydrofuran, dioxane, dimethylformamide, acetone, methyl ethyl ketone, ethylene glycol monomethyl ether, etc. , ethylene glycol monoethyl ether, vinegar e:r-tyl, butyl acetate, toluene, halogenated hydrocarbon, etc., mixed in an organic solvent,
A coating solution uniformly dispersed by a dispersing means such as a wheel mill or an ultrasonic dispersion machine is applied onto the conductive support and dried to form the charge generation layer 3. 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 platemaking of the present invention is performed by first uniformly charging it in a dark place using a corona charger or the like, using a tungsten lamp, halogen lamp, etc., according to the usual electrophotographic method.
Electrostatic latent image exposure is performed by reflection image exposure using a light source such as a xenon lamp or a fluorescent lamp, contact image exposure through a transparent positive film, or scanning exposure using laser light such as a He-Ne laser, argon laser, or semiconductor laser. An image is formed, 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 in this way is immersed in an alkaline eluent, the electrophotographic photosensitive layer (charge generation layer and charge transport layer) in the non-image area that is not covered by the toner image is removed. The hydrophilic surface of the conductive support is exposed by dissolution, 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, sodium phosphate, sodium hydroxide, or sodium carbonate, or an alkaline aqueous solution containing organic amines such as triethanolamine or ethylenenoamine, or eluted ethanol, A solution containing an organic solvent such as benzyl alcohol, ethylene glycol, or glycerin or a surfactant 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 one that is insoluble in the eluate, such as acrylic resin using methacrylic acid, methacrylic ester, vinyl acetate resin, or combination of vinyl acetate and ethylene or vinyl chloride. polymer,
Vinyl chloride resin, vinylidene chloride resin, vinyl acetal resin such as polyvinyl butyral, polystyrene, copolymers of styrene and butadiene, methacrylic acid ester, +t? 'JZ tyrene, polyzolopyrene and its chlorides, polycargonates, polyester resins, polyamide resins, phenolic resins, xylene resins, alkyd resins, waxes, polyolefins, waxes, etc.

The printing original plate of the present invention may also contain a quinonediat compound or a diazo compound, such as 0-naphthoquinonediazide, for the purpose of increasing the solubility of the shimiko photosensitive layer during full-surface exposure after toner image 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 particularly high sensitivity compared to conventional printing original plates () (direct plate making is possible with various light sources such as a 6-Ne laser'-1 semiconductor laser, and the printing plate obtained thereby has a high sensitivity. It has printing durability.

Next, the present invention will be explained in more detail using examples.

In addition, all "parts" in the examples represent parts by weight.

Example 1 1 part of azo pigment A6 was mixed with 0.0% of m-cresol-phenol copolymerized Melac resin (manufactured by Toden Kagaku: MP-707).
66.7 parts of a 74wt% tetravitrofuran solution was pulverized and mixed in a ball mill, and the resulting dispersion was mixed to a thickness of about 0125w.
Coated on an aluminum plate treated with a grain size of 80
It was dried at .degree. C. for 10 minutes to form a charge generation layer with a thickness of about 1 .mu.m.

On this charge generation layer, 2,5 to bis(
4-diethylaminophenyl)-1,3,4-oxanoazole 0.9 parts Styrene-maleic anhydride copolymer (
Copolymerization molar ratio 1:1) manufactured by Aldrich Chemical Co., Ltd. 1:1) 1.8 parts and tetrahydrofuran 132
A printing original plate for electrophotographic engraving of the present invention was prepared by applying a solution in which the above components were mixed and dissolved and dried at 80° C. for 20 minutes to form a charge transport layer having a thickness of about 10 μm.

This original printing plate was tested using an electrostatic copying paper tester (newly manufactured by Kawaguchi Denki Co., Ltd.: Model 5P-428) at -6k.
After performing corona discharge of V for 20 seconds to make it negatively charged, it was left in a dark place for 10 seconds, and the surface potential V at that time. (delt), then irradiate the surface with light using a tungsten rung at an illuminance of 4.5 lux,
Its surface potential is V. The half-reduced exposure amount E172 (lux/second) was calculated based on the time spent in the trench at A. The results are shown in Table-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 mixed with 70 g of sodium metasilicate, 14 g of glycerin.
0m1. Ethylene glycol 550ml and ethanol 150ml/! 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 printed using the conventional method using Ricoh's AP-1310 model, more than 50,000 clear prints could be printed.

Examples 2 and 3 Printing for electrophotographic printing of the present invention was carried out 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 version. and E1/2 were measured.

The above results are shown in Table-1.

(Left below) Example 4 1 part of azo pigment Ai 15, m-cresol-phenol copolymerized novolac resin (manufactured by Toden Chemical Co., Ltd.: ]!i'IP-
707) in 0.74 wt% tetrahydrofuran solution 66
．． 7 parts were pulverized and mixed in a ball mill, and the resulting dispersion was applied onto a grained aluminum plate of approximately 0.25 mm thickness and dried at 80° C. for 10 minutes to form a charge generation layer approximately 1 μm thick. Formed.

3-styryl- as a charge transport substance on this charge generation layer.
1.5 parts of 9-ethylcarbazole, m-cresol-phenol copolymerized novolac resin (manufactured by Toden Chemical: M
P-707) 3.0 parts and tetrahydrofuran 1
A solution of 20 parts mixed and dissolved was applied and heated at 80°C for 2 minutes.
Subsequently, the mixture was dried at 100° C. for 10 minutes to form a charge transport layer having a thickness of about 10 μm, thereby producing a printing original plate for electrophotographic engraving of the present invention. Regarding this printing original plate, V was used in the same manner as in Example 1. and E1/2 measurement results are shown in Table-2.

Next, after forming a toner image on the electrophotographic photosensitive layer of the printing original plate in the same manner as in Example 1,
The electrophotographic photosensitive layer in the non-image area was removed by immersing it in a solution of 100 parts of water for about 45 seconds, and then washing it while gently brushing with water.

The printing plate made in this way is printed on an offset printing machine K.
When overprinting was performed, more than 50,000 clear prints could be printed.

Examples 5 to 8 Printing for electrophotographic printing of the present invention was carried out 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 version. and E172 were measured.

The above results are shown in Table-2.

(Margin below)

[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. - Figure 1 Figure 2 Figure 3 Procedural Amendment (Paper) August 30, 1980 Commissioner of the Patent Office Manabu Shiga 1981 Patent Application No. 95860 2, Title of the Invention Printing original plate for electrophotographic engraving 3, relationship with the case of the person making the amendment Patent applicant address: 3-6-4 Nakamagome-chome, Ota-ku, Tokyo 143 Japan
, Date of amendment order (shipment date) July 31, 1980 6
, Contents of amendment (1) Description page 1, page 5, page 6, page 7, page 8
As shown in the engraving of the chemical formulas on pages 12, 27, and 30 (no changes to the content)

Claims (1)

[Claims] An electronic device 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, on a conductive support. A printing original plate for electrophotographic engraving, characterized by being provided with a photosensitive layer. General formula (1”1 (However, the person in the formula represents a Cassilla residue.)