JPS60242472A - Original printing plate for electrophotographic engraving - Google Patents

Abstract

PURPOSE:To obtain an original printing plate having especially high sensitivity and high printing resistance by forming on a conductive substrate an electrophotographic sensitive layer composed of two layers of an electrostatic charge generating layer contg. an azo pigment represented by formula I and a charge transfer layer contg. a charge transfer material and an alkali-soluble resin. CONSTITUTION:The charge generating layer 3 and the charge transfer layer 4 are laminated on the conductive substrate 1 to form an electrophotos layer 2. The layers 3, 4 may be reversely laminated. The azo pigment coupler is reresented by formula I, where (A) is a coupler residue and said coupler is such as compds. having a phenolic OH, e.g., phenols and naphthols, aromatic amino compds. aminonaphthols having NH2 and phenolic OH, compds. having aliphatic ketones or aromatic phenolic ketones (active methylenes), and said coupler residue (A) is, prefereably, selected from a specified group. The charge transfer layer is formed of the charge transfer material and the alkali-soluble resin.

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 elution and removal of 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 using photosensitive resin have high printing durability, they 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. For this purpose, large-scale equipment is required, and there are drawbacks such as the time required for plate making.

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 disadvantages of low printing durability and high cost per sheet.

Examples of printing plates for direct plate making using the electrophotographic method include JP-B No. 47-47610 and JP-B No. 48-4
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
There were about 0,000 copies of the course.

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-56-14'614
5. JP-A-57-1618'63 discloses, for example, a layer consisting of an organic photoconductive compound and an alkali-soluble resin on a hydrophilic conductive support such as a grained aluminum plate, or A printing original plate for electrophotographic engraving is provided with a layer in which a charge-generating pigment such as a phthalocyanine 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. It is shown.

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, it has low sensitivity as a photoreceptor for electrophotography, so
The drawbacks were that the plate making speed was slow and that a high output light source had to be used.

Purpose An object of the present invention is to solve the problems of the conventionally known printing original plates for electrophotographic engraving as described above, and to provide a printing original plate having particularly high sensitivity and high printing durability.

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 having an electrophotographic photosensitive layer consisting of two layers.◎ General formula (1) (However, A represents a coupler residue) The configuration is shown in Figure 1.

Here, 1 is a conductive support, on which a charge generation layer 3 and a charge transport layer 4 are laminated, and an electrophotographic photosensitive layer 2
is formed.

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 amine compounds with an amine group, aminonaphthols with an amine group and a phenolic hydroxyl group, or aliphatic or aromatic enolic ketone groups (active methylene group). ) is used,
Preferably, the Kaglar residue A has the following general formula (■),
The surface is selected from the group represented by (V), (B), and (I).

[In the formula, R1 is hydrogen, an alkyl group 4. phenyl group or a substituent thereof; X is a hydrocarbon ring or a substituent thereof; Y is a hydrocarbon ring group or a substituent thereof; a substituent, a heterocyclic group or a substituent thereof, or a styryl group or a substituent thereof, R3 represents hydrogen, an alkyl group, a phenyl group, or a substituent thereof, or R2 and R3 are carbon atoms to which they are bonded. They may form a ring together. )] (R4 in formula (2) and (Foundation) represents a substituted or unsubstituted hydrocarbon group.) Ar1 (In the formula, R5 represents an alkyl group, a carbamoyl group, a carboxyl group or an ester thereof, and Ar represents a hydrocarbon ring group or a substituted product thereof, ) OH N CAr2 II 60 60 (wherein, R6 is a hydrocarbon group or a substituted derivative thereof, A
r 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,
Y-! such as benzofuran ring! Examples of the hydrocarbon ring group in R2 include phenyl group, naphthyl group, anthryl group, and pyrenyl group; examples of the heterocyclic group include pyridyl group, chenyl group, furyl group, indolyl group, benzofuranyl group, carbazolyl group, and dibenzofuranyl group. Nyl group, etc., and R2
Examples of the ring that R3 can form together with the carbon atoms to which they are bonded include a fluorene ring.

Furthermore, examples of the hydrocarbon group in 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
Examples of the substituent on the hydrocarbon group of t or R6 include alkyl groups such as methyl, ethyl, propyl, and butyl, alkoxy groups such as methoxy, ethoxy, propoxy, and butoxy, chlorine, and bromine. Examples include halogen atoms, hydroxyl groups, nitro groups, and the like. Examples of substituents on the phenyl group of R1 or the ring of X include halogen atoms such as chlorine atoms and bromine atoms, and Y or R
Examples of substituents on the carbocyclic group or heterocyclic group of 2 or the ring formed by R2 and R3 include alkyl groups such as methyl group, ethyl group, propyl group, butyl group,
Alkoxy groups such as methoxy, ethoxy, propoxy, and butoxy groups; rhodane atoms such as chlorine and bromine; dialkylamino groups such as dimethylamino and diethylamino groups; dialkylamino groups such as dialkylamino; Examples include a halomethyl group such as a trifluoromethyl group, a nitro group, a cyan group, a carboxyl group or an ester thereof, a hydroxyl group, a sulfonic acid group (-8OsNa), and the like. Furthermore, as the hydrocarbon ring group in Ar1 or Ar2, phenyl group, naphthyl group, etc.
In addition, substituents for these groups include alkyl groups such as methyl, ethyl, p, lobyl, and butyl groups, alkoxy groups such as methoxy, ethoxy, zoloboxy, and butoxy groups, nitro groups, chlorine atoms, Examples include halogen atoms such as bromine atoms, cyano groups, dimethylamino groups, and noalkylamino groups such as noethylamide groups.

The azo pigment used in the present invention is, for example, JP-A-52-
It is described in Publication No. 4241. 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. Since the printing original plate of the present invention elutes the non-image areas during the plate-making process, when using a binder, examples of the binder include alkali-soluble resins such as styrene-maleic anhydride copolymer and nobilac enol resin ( (described in detail later) is preferably used. 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 0.01 to 5 μm, more preferably 0.01 to 5 μm.
05-2 μm. If the thickness is less than 0.01 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 transporting materials include hole transporting materials and electron transporting materials. Examples of hole transporting materials include 2,5-bis(4-diethylaminophenyl)-1,
3,4-oxadiazole, 2. '! y-bis[4-(
4-diethylaminostyryl)phenyl]-1,3,4
-Oxadiazole, 2-(9-ethylcarbazole-
3-) -5= (4-diethylaminophenyl)-1
, 3,4-oxadiazole compounds such as 2-vinyl-4-(2-chlorophenyl)-5-
Oxazole compounds such as (4-diethylamino)oxazole, 2-(4-diethylaminophenyl)-4-phenyloxazole, 1-pheny/l/-3-, (
4-diethylaminostyryl)-5-(4-diethylaminophenyl)pyrazoline, 1-phenyl-3-(4
pyrazoline compounds such as -dimethylaminostyryl)-5-(4-dimethylaminophenyl)pyrazoline, 2,
Diphenylmethane compounds such as 2'-dimethyl-4,4'-bis(diethylamino)triphenylmethane, 1,1-bis(4-dibenzylaminophenyl)chronocune, tris(4-diethylaminophenyl)methane, 9-
(4-dimethylaminobenzylidene)fluorene, 3-
(9-Fluorene compounds) Fluorene compounds such as -9-ethylcarbasol, styryl anthracene compounds such as 9-(4-diethylaminostyryl) anthracene, 9-bromo-10-(4-diethylaminostyryl) anthracene, 1,2- distyrylbenzene compounds such as 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-benzyl-1-phenylhydrazone,
4-noethylaminobenzaldehyde 1,1-nophenylhydrazone, 2,4-nomethoxypenzaldehyde 1
-Pen True 1- Hydrazone compounds such as phenylhydrazone, 4-diphenylaminohenzaldehyde 1-methyl-1-phenylhydrazone, 4-diphenylaminostilbene, 4-dibenzylaminostilpene, 4-
Stilbene compounds such as ditolylaminostilbene, 1
-(4-diphenylaminostyryl)naphthalene, 1-
Styrylnaphthalene compounds such as (4-diindylaminostyryl)naphthalene, 4'-diphenylamino-α
-Phenylstilbene, 4'-methylphenylamino-
α-Phenylstilbene compound of α-phenylstilbenato, 3-styryl-9-ethylcarbazole, 3-
Styrylcarbazole compounds such as (4-noethylamino)styryl-9-ethylcarbazole are used.

Examples of the electron transport substance include chloranil, bromoanil, tetracyanoethylene, tetracyanoquinone dimethane, 2+:4+7-)linitro-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, 113.7-) IJ nitronopenzothioph x 7-5+5-dioxide, and the like.

The alkali-soluble resin used in the charge transport layer 4 refers to a resin that becomes soluble in a heathering 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 the phenolic resin include phenol, 0-cresol, m-cresol, p-cresol, ethylphenol, isozorobylphenol, t-butylphenol, and t-cresol.
-amylphenol, hexylphenol, t-octylphenol, cyclohexylphenol, 3-mef
Ru 4-Rio Ru 6-t-butylphenol, inglovir cresol, 1-butyl cresol, t-7
A novolac type resin obtained by condensing at least one substituted phenol such as milk cresol, hexyl cresol, t-octyl cresol, and cyclohexyl cresol with an aldehyde such as formaldehyde, acetaldehyde, acrolein, crotonaldehyde, and furfural under acidic conditions is used. It will be done.

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, preferably 20-60% by weight. 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 can contain a plasticizer.

Examples of plasticizers include dimethyl phthalate, diethyl phthalate, and dibutyl phthalate.

Various phthalic acid esters and glycol esters such as dimethyl glycol phthalate and ethyl phthalyl ethyl glycolate are effective.

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
-IWII11 are 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. Furthermore, as shown in U.S. Pat.
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 shown in Japanese Patent No. 5125.

In the above anodizing treatment, the aluminum plate is anodized 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 passing a current as .

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, dimethylformamide, acetone, methyl ethyl ketone, ethylene glycol monomethyl. Mix in an organic solvent such as ether, ethylene glycol monoethyl ether, r-f acetate, y'-thyl acetate, toluene, or halogenated hydrocarbon, and use a dispersion method such as a ball mill or an ultrasonic disperser to uniformly disperse the mixture. A charge generation layer 3 is provided by applying the dispersed coating liquid onto the conductive support and drying it. 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 a charge transport layer 4.
will be established.

The plate making of the printing original 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, a halodan lamp, etc., according to the usual electrophotographic method.
Reflective image exposure using a light source such as a xenon lamp or fluorescent lamp, contact image exposure through a transparent positive film, or scanning exposure using a laser beam such as a He-Ne laser, argon laser, or semiconductor laser f- is used to reduce electrostatic charge. A latent 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. It is dissolved and removed, the hydrophilic surface of the conductive support is exposed, and only the toner image area remains, making it possible to obtain a good printing plate (FIG. 3).

The eluent used here is, for example, an alkaline aqueous solution containing inorganic salts such as sodium silicate, sodium phosphate, sodium hydroxide, and sodium carbonate, or an alkaline aqueous solution containing organic amines such as triethanolamine and ethylenediamine; A solution containing an organic solvent such as benzyl alcohol, ethylene glycol, or glycerin or a surfactant added thereto 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 renostotic 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, copolymer of vinyl acetate and ethylene or vinyl chloride, etc. , vinyl chloride resin, vinylidene chloride resin, polyvinyl butyral, etc.

Nylacetal resin, J'J styrene, copolymers of styrene and butadiene, methacrylic acid esters, polyethylene, polypropylene and its chlorides, polycarbanates, polyester resins, polyamide resins, phenolic resins, xylene resins, alkyd resins, waxes , polyolefins, and waxes.

The printing original plate of the present invention may also contain a quinone shea such as 0-naphthoquinone diazide, a cyto compound, or a diazo compound for the purpose of increasing the solubility of the shimiko photosensitive layer by 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 oleophilic toner remains. The ink adheres only to the image area, resulting in good printed matter without scumming.

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 He-Ne laser and semiconductor laser, and the printing plate obtained thereby has high printing durability). have.

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

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

Example 1 1 part of azo pigment AI was mixed with 0.0 parts of m-cresol-phenol copolymerized lac resin (MP-707 manufactured by Gunei Chemical Co., Ltd.).
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.

2,5-bis(
4-diethylaminophenyl) -1,3,4-oxanoazole 0.9 parts Styrene-maleic anhydride copolymer (manufactured by Aldrich Chemical Company, copolymerization molar ratio 1:1) 1.8 parts and tetrahydrofuran 132 parts 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 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 at that time was V. (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-reduction exposure amount E1/2 (lux/second) was calculated based on the time required to reach 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 and 14 g of glycerin.
It was immersed for 1 minute in a solution consisting of 550 ml of 0 ml of ethylene glycol and 150 M of ethanol, and was further washed with a water jet while gently brushing to remove the electrophotographic photosensitive layer in the non-image areas to which toner was not attached.

The printing plate made in this way is then printed on an offset printing machine (
When printing was carried out using a conventional method using Ricoh Model AP-1310, 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. Create the original version■. and E1/2 were measured.

The above results are shown in Table-1.

(The following is a blank space) Example 4 1 part of azo pigment A1 was mixed with 0.0 parts of m-cresol-phenol copolymerized novolac resin (manufactured by Gunei Chemical Co., Ltd.: MP-707).
74wt% tetrahydrofuran solution 6s, 7 parts?
- Pulverize and mix in a Lumir, and the resulting dispersion has a thickness of about 0.
It was coated on a 25+m grained and treated aluminum plate and dried at 80° C. for 10 minutes to form a charge generating layer with a thickness of about 1 μm.

3-styryl- as a charge transport substance on this charge generation layer.
1.5 parts of 9-ethylcarbazole, m-cresol-
Phenol copolymerized novolak resin (manufactured by Gunei Chemical: MP
-707) 3.0 parts and tetrahydrofuran 12.
A solution in which 0 parts of 0 parts were mixed and dissolved was coated and dried at 80°C for 2 minutes and then at 100°C for 10 minutes to form a charge transport layer with a thickness of about 10 μm, thereby obtaining the printing original plate for electrophotolithography of the present invention. Created. Regarding this printing original plate, as in Example 1, V
. The results of measuring and E, /2 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 and 100 parts of water for about 45 seconds, and then washing it while gently brushing with water.

When the printing plate thus prepared was printed on an offset printing machine, more than 50,000 clear prints could be printed.

Examples 5 to 8 The same procedure as in Example 4 was carried out 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. A printing original plate was prepared and vo and E, /2 were measured.

The above results are shown in Table-2.

(Margin below)

[Brief explanation of the drawing]

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 To Figure 2 Figure 3

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) (However, in the formula, A represents a Kaglar residue.)