JPS6332562A - Printing plate material for electrophotomechanial process - Google Patents

Abstract

PURPOSE:To obtain a printing plate material high in sensitivity and printing resistance, and easy in plate making by forming a layer containing an electric charge generating material, a charge transfer material, and a specified resin on a conductive substrate, and heat treating it to obtain an electrophotographic photosensitive layer having a hydrophilic surface. CONSTITUTION:The photosensitive layer 2 formed on the conductive substrate 1 contains the charge generating material, the charge transfer material, and a resin having cyclic anhydride structures partly opened. The layer 2 is heat treated to form the hydrophilic layer 2, and it is further treated with an aqueous alkaline solution to open the acid anhydride parts by hydrolysis, and to obtain the hydrophilic printing plate material. As said resin, copolymers of methyl vinyl ether or the like lower alkyl vinyl ether and maleic anhydride, and a styrene-maleic anhydride copolymer are used, and the layer 2 may contain a polyester resin, a polyamide resin, or the like in addition to the maleic acid copolymer in order to enhance strength of the layer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a printing original plate for electrophotographic engraving, and more particularly to a printing original plate whose surface is made hydrophilic after forming a toner image by electrophotography.

[Prior Art] As a planographic printing original plate, those using a photosensitive resin or a silver halide photosensitive material are known.

However, lithographic printing original plates using photosensitive resin have high printing durability but low sensitivity and cannot be used for so-called direct plate making. Therefore, during plate making, it is necessary to create a negative or positive from the original using silver halide film. Therefore, it requires large-scale equipment and has drawbacks such as the time required for plate making. Further, although printing original 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 sheet.

Examples of original printing plates for direct plate making using electrophotography include 1, for example, Japanese Patent Publication No. 47610 of 1972, Japanese Patent Publication No. 47610 of 1972,
No. 40002, Special Publication No. 18325, Special Publication No. 18325, Special Publication No. 1971
Zinc oxide-resin dispersion systems are known as described in publications such as No. 15766 and Japanese Patent Publication No. 51-25761. After a toner image is formed on this printing original plate by the electrophotographic λ method, 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 suffer from peeling due to mechanical pressure applied during printing and penetration of dampening water into the photosensitive layer and conductive treatment layer, destroying the hydrophilic layer on the surface. The force is about s, ooo to 10,000 sheets.

In addition, zinc oxide-resin dispersion printing original plates are dye-sensitized to give them sensitivity in the visible light region, but they still do not show sensitivity sufficient for practical use in the long wavelength light region of 600 nm or more. He-Ne with low output power
The disadvantage is that exposure cannot be performed using a laser or semiconductor laser.

On the other hand, Special Publication No. 37-17162, Special Publication No. 3g-775
No. 8, Special Publication No. 46-39405, Japanese Patent Publication No. 52-243
No. 7, JP-A-55-153948, JP-A-55-10
No. 5254, JP-A-56-107246, JP-A-56
-16125, JP-A No. 57-147656, JP-A-56-146145, and JP-A-57-161863, for example, describe the use of hydrophilic conductive materials such as grained aluminum plates. A layer consisting of an organic photoconductive compound and an alkali-soluble resin on a support, a layer in which a charge-generating pigment such as a phthalocyanine pigment is dispersed in an alkali-soluble resin, or an electron-withdrawing substance or an electron-donating substance is added to this dispersed layer. In addition, a printing original plate for electrophotographic engraving that is provided with a sensitized layer is described. 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. Although it has the advantage of being able to obtain
It has the disadvantage that a high output light source must be used.

Furthermore, Japanese Patent Publication No. 45-5606 describes a method for producing a printing original plate with a parent wood treatment type on the surface of the non-image area, which is easy to make by providing a specific resin layer on an ordinary electrophotographic photoreceptor. . That is, a printing original plate is disclosed in which a surface layer comprising a vinyl ether-maleic anhydride copolymer and a hydrophobic resin compatible therewith is provided on an electrophotographic photosensitive layer. This layer is a layer that can be made hydrophilic by treating the non-image area with an alkali to open the acid anhydride ring portion with water after the toner image is formed.

However, the vinyl ether-maleic anhydride copolymer used here becomes water-soluble when the acid anhydride ring portion is ring-opened and made hydrophilic, so high printing durability cannot be obtained. If the proportion of hydrophobic resin in the layer is increased in order to improve water resistance, the hydrophilicity of one surface will decrease, causing background stains on printed matter, so it has been difficult to achieve both hydrophilicity and water resistance.

[Purpose] The purpose of the present invention is to solve the above-mentioned problems of conventional printing plates for electrophotographic engraving, and to provide a printing plate that is particularly sensitive, has high printing durability, and is easy to make. .

[Structure] The electrophotographic printing original plate of the present invention contains a charge generating substance, a charge transporting substance, and a cyclic acid anhydride structure on a conductive support, and contains a resin in which a part of the cyclic structure is ring-opened. I put layers on it, haha.

The layer is characterized by being an electrophotographic photosensitive layer whose surface can be made hydrophilic by heat treatment.

Here, a typical example of a resin having a cyclic acid anhydride ring structure is a copolymer containing maleic anhydride as one copolymerization component (hereinafter abbreviated as "maleic anhydride copolymer").

The present invention will be described in more detail below with reference to the accompanying drawings.

FIG. 1 is a sectional view showing the basic structure of a printing original plate according to the present invention, in which 1 represents a conductive support and 2 represents an electrophotographic photosensitive layer that can be made hydrophilic.

In the image forming process by electrophotography, by image exposure after charging, the charge generating substance in the photosensitive layer 2 absorbs light in the irradiated areas, and carriers of electrons and holes are generated. Due to the electric field, one of these flows to the conductive support 1, and the other neutralizes the charge on the surface to form an electrostatic latent image. At this time, the surface of the photosensitive layer 2 that holds the electrostatic latent image needs to be highly resistive and hydrophobic to the extent that the charge does not diffuse in one direction (if it is hydrophilic, it will absorb water and electrostatic latent image cannot be retained).

Next, the electrostatic latent image is developed with toner charged to the opposite polarity to the surface charge and fixed, forming a toner image on the photosensitive layer 2. Since printing is performed based on the difference between the lipophilicity (inkphilicity) of the toner image thus formed and the hydrophilicity of the non-image area, the surface of the photosensitive layer 2 needs to be hydrophilic during printing.

Thus, in addition to forming an electrostatic latent image, the photosensitive layer 2 is required to have the function of changing its surface from hydrophobicity during electrostatic latent image formation to hydrophilicity during printing.

The heat-treated resin having a partially opened cyclic acid anhydride ring structure used for the photosensitive layer 2 in the present invention is originally hydrophobic and has sufficient resistance to retain an electrostatic latent image. ,
When treated with an alkaline aqueous solution, the acid anhydride ring opens with water and becomes hydrophilic, making printing possible. Moreover, although it is hydrophilic, it is not water-soluble and has sufficient water resistance, so that high printing durability can be obtained.

As the charge generating substance used in the photosensitive layer 3 of the present invention,
Examples include inorganic compounds such as zinc oxide, titanium oxide, zinc sulfide, selenium, selenium alloys, cadmium sulfide, cadmium selenide, and silicon, and organic compounds as shown in (1) to (I4) below.

(1) Triphenylmethane pigments such as malachite green and crystal violet; methylene blue,
Thiazine dyes such as methylene green; Astrazone Orange R;

Astrazone Yellow 3GL, Astrazone Red 6B
Astrazon dyes such as; Cyanine dyes such as Eisen Astrafuroxin FF; Xanthine dyes such as Rhodamine B; Cationic dyes such as pyrylium dyes.

(2) Perylene pigments such as perylene anhydride and perylene imide.

(3) Indigo pigment.

(4) Quinacridone pigment.

(5) Polycyclic quinones such as anthraquinones, pyrenequinones, anthoanthros, and flavanthrones.

(6) Bisbenzimidazole pigment.

(7) Square methine pigment.

(8) Indathlon pigment.

(9) Phthalocyanine pigments such as metal phthalocyanines such as copper phthalocyanine and metal-free phthalocyanines.

(10) A charge transfer type complex consisting of an electron-donating substance such as poly-N-vinylcarbazole and an electron-accepting substance such as 2,4,7-dolinitrofluorenone.

(11) A eutectic complex formed from a pyrylium salt dye and a polycarbonate resin.

(12) Barbyric acid derivative or thiobarbital acid derivative.

(13) Azo pigments such as monoazo pigments, disazo pigments, and triazo pigments; examples of monoazo pigments include monoazo pigments having a central skeleton such as anthraquinone and N-phenylcarbazole; examples of disazo pigments include diane blue and chlordien blue; benzidine pigments such as N-ethyl rubberazole, stilbene, distilbenzene, naphthalene, and fluorenone.

Fluorene, anthraquinone, 2,5-diphenyl-1
,3,,4-oxadiazole, dibenzothiophene,
There are disazo pigments having a central skeleton such as dibenzothiophene dioxide, acridone, and phenanthrenequinone, and examples of trisazo pigments include trisazo pigments having a central skeleton such as triphenylamine or N-phenylcarbazole.

As the resin having a cyclic acid anhydride structure used in the photosensitive layer 2 that can be made hydrophilic, a copolymer containing maleic anhydride as one copolymerization component is suitable as described above, but more specifically, for example, , methyl vinyl ether, ethyl vinyl ether, 2-chlorovinylethyl ether, propyl vinyl ether, isobutyl vinyl ether, 2-
Copolymers of lower alkyl vinyl ethers such as methoxyethyl vinyl ether and maleic anhydride, copolymers of styrene and maleic anhydride, copolymers of ethylene and maleic anhydride, copolymers of vinyl acetate and maleic anhydride There is such a thing as merging. For the photosensitive layer 2, a copolymer of these with a partially opened ring structure is used.

The photosensitive layer 2 contains a charge transport substance. Charge transporting substances include hole transporting substances and electron transporting substances, and examples of hole transporting substances include 2,5-bis(4-diethylaminophenyl)-1,3,4-oxadiazole, 2,5- Bis(4-(4-diethylaminostyryl)phenyl)-
Oxadiazole compounds such as 1,3,4-oxadiazole, 2-(9-ethylcarbazolyl-3-)-5-(4-diethylaminophenyl)-1,3,4-oxadiazole; 2 -vinyl-4-(2-chlorophenyl)
-5-(4-diethylamino)oxazole, 2-(4
-diethylaminophenyl)-4-phenyloxazole; 1-phenyl-3-(4
2,2'
-Diphenylmethane compounds such as dimethyl-4,4'-bis(diethylamino)triphenylmethane, 1,1-bis(4-dibenzylaminophenyl)propane, tris(4-diethylaminophenyl)methane; 9-(
4-dimethylaminobenzylidene) fluorene, 3-
Fluorene compounds such as (9-fluorenonedene)-9-ethylcarbazole; 9-(4-diethylaminostyryl)anthracene.

Styryl anthracene compounds such as 9-bromo-10-(4-diethylaminostyryl) anthracene; 1,2
-bis(4-diethylaminostyryl)benzene, 1,
Distyrylbenzene compounds such as 2-bis(2,4-dimethoxystyryl)benzene: 9-ethylcarbazole-3-aldehyde 1-methyl-1-phenylhydrazone, 9-ethylcarbazole-3-aldehyde 1-benzyl-1- Phenylhydrazone, 4-diethylaminobenzaldehyde 1.1-diphenylhydrazone, 2.4-
Hydrazone compounds such as dimethoxybenzaldehyde 1-benzyl-1-phenylhydrazone, 4-diphenylaminobenzaldehyde 1-methyl-1-phenylhydrazone; 4-diphenylaminostilbene, 4-dibenzylaminostilbene, 4-ditolylaminostilbene, etc. Stilbene compounds; Styrylnaphthalene compounds such as 1-(4-diphenylaminostyryl)naphthalene and 1-(4-dibenzylaminostyryl)naphthalene: 4'-diphenylamino-α-phenylstilbene, 4'-methylphenylamino-α - α-phenylstilbene compounds such as phenylstilbene; styrylcarbazole compounds such as 3-styryl-9-ethylcarbazole, 3-(4-diethylamino)styryl-9-ethylcarbazole; or Molecular compounds are used.

Examples of electron transport substances include chloranil, bromoanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4.7-dolinitro-9-fluorenone, 2,
4,5.7-tetranitro-9-fluorenone, 2,4
, 5.7-titranitroxanthone, 2,4.8-trinidrothioxanthone, 2,6.8-trinitro-4H
-indeno(1,2-b)thiophen-4-one, 1,
Examples include 3°7-dolinitrodipenzothiophene-5,5-dioxide.

In the photosensitive layer 2, these hole or electron transport substances may be used alone or in combination.

As the conductive support 1, for example, a plastic film having a conductive surface such as an aluminum vapor-deposited film:
Paper that has been treated to be water-resistant, solvent-resistant, and conductive; metal plates such as aluminum plates, zinc plates, copper plates, and stainless steel plates are used.

To produce the printing original plate for electrophotolithography of the present invention, first, a maleic anhydride copolymer is mixed with a suitable organic solvent (toluene,
(Tetrahydrofuran, dioxane, dimethylformamide, acetone, methyl ethyl ketone, ethylene glycol monoethyl ether, ethyl acetate, cyclohexanone, etc.) and disperse and mix using a ball mill, ultrasonic dispersion, etc., and then add a charge transport substance to this dispersion. The coating solution prepared by dissolving the coating solution is applied onto the conductive support 1, dried, and then heat-treated to form the photosensitive layer 2 which can be made hydrophilic.

The temperature and time of this heat treatment vary depending on the maleic anhydride copolymer used and the degree of ring opening, but are approximately 80 to 2
The temperature can be selected from several minutes to several hours at 00°C.

The hydrophilic photosensitive layer 2 is mainly composed of a charge generating substance, a charge transporting substance and a maleic anhydride copolymer, but in order to improve the strength of the layer, other resins such as polyester resin, polyamide resin, etc. Polycarbonate resin, acrylic resin, polystyrene resin, vinyl acetal resin, vinyl acetate resin, etc. can be added.

However, in this case, the proportion of these resins contained in the entire layer is preferably 50% by weight or less.

If the ratio is higher than this, the rate of hydrophilicity will be slow and the hydrophilicity will be insufficient in the parent wood treatment of the non-image area surface after image formation, resulting in background stains on printed matter.

The proportion of the charge transport substance in the hydrophilic photosensitive layer 2 is preferably 10 to 90% by weight, more preferably 20 to 70% by weight. Below this range, sensitivity is low, and above this range, stiffness resistance decreases. Further, the proportion of the charge generating substance in the photosensitive layer 2 is 0.1 to 50% by weight, preferably 1 to 30% by weight. Below this range, sensitivity is low, and above this range, the mechanical strength of the layer decreases and is not practical. The thickness of the photosensitive layer 2 is preferably 3 to 50 μm, more preferably 5 μm.
It is ~20μ gourd. Below this range, charging will not be sufficient, and above this range, the residual potential will be high and cause staining of the background.

Plate making using the printing original plate for electrophotographic platemaking of the present invention first follows the usual electrophotographic method, and is uniformly charged in a dark place using a corona charger or the like, and then charged using a tungsten lamp, halogen lamp, xenon lamp, or 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 a He-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 3 on the electrophotographic photosensitive layer (FIG. 2).

Next, when the printing original plate on which this toner image has been formed is immersed in an alkaline hydrophilic treatment liquid, the surface of the non-image area that is not masked by the toner image (the surface of the photosensitive layer 2) is made hydrophilic, resulting in a good printing plate. Obtained (Figure 3), in Figure 3,
4 represents a hydrophilized portion.

The hydrophilic treatment liquid used here is, for example, an alkaline aqueous solution of inorganic salts such as sodium silicate, sodium phosphate, sodium hydroxide, and sodium carbonate, an alkaline aqueous solution containing organic amines such as triethanolamine and ethylenediamine, or an alkaline aqueous solution containing ethanol, benzyl, etc. A solution containing an organic solvent such as alcohol, ethylene glycol, or glycerin or a surfactant is used.

The time required for hydrophilization varies depending on the formulation of the photosensitive layer 2, the concentration of the parent wood treatment liquid, etc., but it can be carried out in about 10 to 120 seconds by selecting appropriate conditions.

Since the printing original plate of the present invention is subjected to hydrophilic treatment only in the non-image areas, it is preferable that the toner component contains a resin component having resistivity in the parent wood treatment liquid.

This resin component may be anything as long as it is insoluble in the eluate; for example, acrylic resin using methacrylic acid, methacrylic acid ester, etc., vinyl acetate resin, copolymer of vinyl acetate and ethylene or vinyl chloride, etc. Union,
Vinyl chloride resin, vinylidene chloride resin, vinyl acetal resin such as polyvinyl butyral, polystyrene, copolymers of styrene and butadiene, methacrylic acid ester, etc., polyethylene, polypropylene and its chloride, polycarbonate, polyester resin, polyamide resin, phenol resin , xylene resin, alkyd resin, wax, polyolefin, wax, etc.

After completing the plate-making process described above, the printing original plate of the present invention becomes a printing plate having an image area covered with lipophilic toner and a surface of a non-image area that has been made highly hydrophilic. It adheres only to the surface of the paper, resulting in good printed matter with no background stains.

EXAMPLES Below, 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 2 parts of a disazo pigment (charge generating substance) represented by the following structural formula ('I) and 20 parts of tetrahydrofuran were mixed,
Next, this dispersion was thoroughly ground in a ball mill, and 100 parts of a 10% tetrahydrofuran solution of a partially ring-opened methyl vinyl ether-maleic anhydride copolymer (manufactured by Aldrich Chemical Company) and the following structural formula (
7 parts of a charge transporting substance represented by n) was added and further dispersed sufficiently to prepare a coating liquid.

This dispersion has a thickness of 100 mm with aluminum vapor-deposited on the surface.
Electrophotographic material that can be coated on a μI polyester film (conductive support), dried at 80°C for 2 minutes and tOS°C for 5 minutes, and then heat-treated at 150°C for 30 minutes to make it hydrophilic to a thickness of approximately 20 μm. A photosensitive layer was formed.

The printing original plate for electrophotographic engraving thus prepared was charged to a surface potential of approximately ÷800 volts by corona discharge in a dark place, and then imagewise exposed through a lens system using a halogen lamp to form an electrostatic latent image. It was then developed with toner for copying machines and fixed by heating to form a toner image.

Next, in order to make the non-image area hydrophilic, it was immersed in a 3% by weight aqueous sodium metasilicate solution for 60 seconds.

When the lithographic printing plate thus prepared was mounted on an offset printing machine and printed according to a conventional method, more than 3,000 copies of good quality prints were printed.

Example 2 In Example 1, a disazo pigment having the following structural formula (m) was used instead of the charge generating substance (1'>), and a compound represented by the following structural formula (IV) was used as the glue θ of the charge transporting substance (II). Except for this, printing was carried out using the printing plate obtained in the same manner as in Example 1, and 3,000 good prints were obtained.
I was able to print more than one page.

Further Example 3 In Example 1, a disazo pigment of the above structural formula (m) was used instead of the charge generating substance (1), and 2,4,7-dolinitrofluorenone was used instead of the charge transporting substance (II) to generate electrons. A photolithographic printing original plate was produced.

This original plate was processed and plate-made in the same manner as in Example 1, except that it was charged to about -800 volts in the plate-making process, and printing was performed using the obtained printing plate.

We were able to print more than 3,000 good quality prints.

Example 4 A printing original plate for electrophotographic engraving was prepared in Example 1 except that a trisazo pigment having the following structural formula (V) was used instead of the charge generating substance (I).

This original plate was processed and plate-made in the same manner as in Example 1, and the resulting printing plate was used to print, resulting in 3 good prints.
I was able to print over 000 pages.

[Effects] The printing original plate of the present invention is particularly sensitive to precipitation in the printing original plate compared to conventional printing original plates, and depending on the selection of the charge-generating substance, direct plate making is possible with various light sources such as He-Ne laser and semiconductor laser. Become.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view of the electrophotographic printing plate of the present invention. Also, Figures 2 and 3 are for explaining the plate-making process, and Figure 2 shows the state after toner image formation,
FIG. 3 shows the state after hydrophilic treatment. 1... Conductive support 2... Electrophotographic photosensitive layer 3...
Toner image 4...Hydrophilized partial patent applicant
Rico Co., Ltd. - Leap) I ¥1 4 pieces -

Claims (1)

[Claims] 1. A layer containing a charge-generating substance, a charge-transporting substance, and a resin having a cyclic acid anhydride structure and a part of the cyclic structure being ring-opened is provided on a conductive support, and the layer is heat-treated. 1. A printing original plate for electrophotographic engraving, characterized in that the surface thereof is an electrophotographic photosensitive layer whose surface can be made hydrophilic.