JPH06175417A - Manufacture of press plate for electrophotographic offset printing - Google Patents

Abstract

PURPOSE:To provide a press plate for offset printing eliminating an anti-pollution measure of waste water treatment and others, of high performance, high reliability and long life. CONSTITUTION:An electrostatic latent image is picked up (A process) by charging and exposing a print material 1 for printing with an organic semiconductor light carrier generation layer 3 and a hydrophilic polysilane electric charge transport layer 4 laminated on a base plate 2, thereafter, by developing it, a toner picture image part to be a positive picture image is formed (B process), and thereafter, by fixing (C process), a print plate for offset printing with the toner picture image part is made. Consequently, lipophilic ink is predominantly adhered on the toner picture image part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an electrophotographic offset printing plate comprising a combination of an organic semiconductor charge generation layer and a hydrophilic polymer charge transport layer.

[0002]

2. Description of the Related Art A method of manufacturing a printing plate using an electrophotographic technique has already been proposed.
According to the method proposed in Japanese Patent Laid-Open No. 1-143408, after a toner image is formed on a photoconductor, the toner image is transferred to a printing plate material made of a photosensitive resin, and the printing plate material is exposed to light to form a non-printed image. A photochemical reaction is caused in the toner portion, and then development elution treatment is performed to form a printing plate having irregularities corresponding to image information.

However, according to the method proposed above,
Since a printing plate material is required in addition to the photoreceptor, the number of members increases and the process becomes complicated. Furthermore, since development elution is performed by a wet process, large-scale equipment is required for pollution control such as wastewater treatment.

Further, according to Japanese Patent Laid-Open No. 58-72145, a photosensitive material is applied to the surface of a printing plate material, a toner image is formed thereon by an electrophotographic method, and then the printing plate material is entirely covered. It is exposed to cause a photochemical reaction in the non-toner portion, and then is subjected to development elution treatment to obtain a printing plate having irregularities according to image information.

However, this method is an improvement over the above-mentioned technique in that a printing plate material is not required separately from the photoconductor, but on the other hand, since development elution is carried out by a wet process, wastewater treatment, etc. It is still unsolved in that large-scale equipment is required for pollution control.

Furthermore, in the method proposed in JP-A-3-158861, an organic photoconductive compound and a binder resin are used as a photosensitive material used in the above wet process, and the binder resin is a specific material. Although the printing durability and the image quality are improved by the method, since the development elution is carried out by the wet process, there are similar problems.

Moreover, in the conventional electrophotographic printing plate material using the organic semiconductor type charge generating layer, the knowledge that the organic semiconductor type charge generating layer has hydrophilicity has not been announced yet.

The inventors of the present invention have made extensive studies in view of the above circumstances, and as a result, the polysilane-based charge transport material which has been already proposed by the inventors of the present invention, which decomposes upon irradiation with ultraviolet rays, has oxygen in its alkyl group. It was found that the hydrophilicity is remarkably increased when a hydroxyl group is bonded. Moreover, it was also found that when the hydrophilic polysilane-based charge transport layer and the charge generation layer laminated thereunder are combined, the offset printing plate can easily obtain a positive image.

The present invention has been completed on the basis of the above-mentioned findings, and its purpose is to provide an electronic printing plate for offset printing, which does not require large-scale equipment and has high performance and high reliability by a simple process. An object of the present invention is to provide a method for manufacturing a photographic offset printing plate.

[0010]

According to a first aspect of the present invention, there is provided an electrophotographic offset printing plate manufacturing method, comprising: an organic semiconductor charge generation layer on a conductive support; and a polymer charge transport layer having a hydrophilic surface. A printing plate material in which
The method for producing an electrophotographic offset printing plate is characterized in that an offset printing plate having a toner image portion is formed by the step of (1) and a lipophilic ink is adhered onto the toner image portion. A ... The printing plate material is charged and exposed to form an electrostatic latent image. B ... The printing plate material having the electrostatic latent image is developed to form a toner image portion which becomes a positive image. C: The developed printing plate material is fixed.

According to a second aspect of the present invention, there is provided a method for producing an electrophotographic offset printing plate in which an organic semiconductor charge generation layer and a polymer charge transport layer having a hydrophilic surface are sequentially laminated on a conductive support. An electrophotographic offset printing plate characterized in that the plate material is made into an offset printing plate having a toner image portion by the following steps A to D, and a lipophilic ink is adhered onto the toner image portion. Printing plate manufacturing method. A ... The printing plate material is charged and exposed to form an electrostatic latent image. B ... The printing plate material having the electrostatic latent image is developed to form a toner image portion which becomes a positive image. C: The developed printing plate material is fixed. D ... The fixed printing plate material is exposed to corona discharge to enhance the hydrophilicity of the exposed surface of the polymer-based charge transport layer.

The present invention will be described in detail below with reference to FIGS. FIG. 1 shows the structure of a printing plate material 1 for making an electrophotographic lithographic printing plate according to the present invention. 2 is a conductive substrate, and its material is aluminum, copper, zinc, SU
For example, a metal such as S, nickel, or brass, or a heat resistant resin having a conductive film deposited on the surface thereof may be used. Further, the shape thereof is appropriately selected such as a flat plate shape, a sheet shape and a drum shape.
An organic semiconductor photocarrier generating layer (charge generating layer) 3 and a polysilane carrier (charge) transporting layer 4, which is an example of the polymer charge transporting layer having a hydrophilic surface, are sequentially formed on the substrate 2. To form the plate material 1.

Further, as shown in FIG. 2, in place of the hydrophilic polysilane carrier (charge) transport layer 4, a hydrophobic polysilane carrier transport layer 4a and a hydrophilic polysilane which are already proposed and decomposed by ultraviolet irradiation. It may have a laminated structure with the system carrier transport layer 4b.

These polysilane-based carrier (charge) transport layers 4, 4a and 4b may be, for example, UV-decomposable polysilane, polysilane of the chemical formula shown in Chemical formula 1 is selected, and hydrophilic polysilane-based carrier transport is performed. Layer 4, 4
In order to obtain b, an oxygen atom or a hydroxyl group may be bonded to the alkyl group of this chemical formula in the hydrophobic polysilane material.

[0015]

[Chemical 1]

Such polysilanes include diethyl polysilane, dipropyl polysilane, dibutyl polysilane,
Diamylpolysilane, dihexylpolysilane, dicumylpolysilane, ethylpropylpolysilane, ethylamylpolysilane, ethylhexylpolysilane, propylbutylpolysilane, propylamylpolysilane, propylhexylpolysilane, propylphenylpolysilane, propylcumylpolysilane, butylamylpolysilane, butylhexylpolysilane , Butylphenyl polysilane, butyl cumyl polysilane, amyl hexyl polysilane, amyl phenyl polysilane, amyl milk mil polysilane, hexyl phenyl polysilane, hexyl mil polysilane, phenyl cumyl polysilane, ethyl butyl polysilane, phenyl ethyl polysilane, cumyl ethyl polysilane, Examples include diphenyl polysilane.

The thickness of the polysilane-based carrier transport layer 4 is appropriately set as an offset printing plate and is 0.5 to 10 μm.
m, preferably 1 to 5 μm.

The carrier transport layer 4 is formed by a dip coating method or a roll coater method. For example, when forming a carrier transport layer of cumylethylpolysilane, the starting material is cumylethyldichlorosilane, which is dechlorinated and polymerized to produce cumylethylpolysilane. This molecular weight is usually on the order of thousands to millions. The polysilane generated in this manner is dissolved in a solvent such as toluene or tetrahydrofuran, and the photoreceptor substrate on which the photocarrier generation layer 3 has been formed is dipped in the solution and applied. Then about 100
The photocarrier generation layer 3 is dried by drying with hot air at ℃.
The printing plate material 1 for printing is completed by forming the polysilane-based carrier transport layer 4 thereon.

The photocarrier generating layer 3 has a function of enhancing the electrostatic latent image contrast as a photoconductor, and it may be formed of a known organic semiconductor photoconductive material. For example, an organic semiconductor having high carrier generation efficiency such as titanyl phthalocyanine, metal phthalocyanine pigment, metal-free phthalocyanine, perylene pigment, polycyclic quinone pigment, squarylium dye, azurenium dye, thiapyrylium dye, trisazo pigment is selected. The layer is formed as a vapor deposition layer or a fine particle dispersion layer.

The thickness of the photocarrier generating layer 3 is 1
The range of μm to 1 mm is preferable, and within this range, the generation of photocarriers is effectively performed, the internal stress of the film does not increase, and the film peels when repeatedly used as an offset printing plate. Disappear. In particular, when the substrate 2 is a flexible sheet, the film is likely to be cracked or peeled off, so that the thickness is preferably 10 μm or less.

The photocarrier generating layer 3 may be a single layer, but may have a laminated structure depending on the required characteristics. For example, a blocking layer that blocks reverse polarity carrier injection from the substrate 2 may be provided at the interface with the substrate 2.

As described above, since this printing plate material 1 is an electrophotographic photosensitive member in which the organic semiconductor type charge generating layer and the hydrophilic polysilane type charge transporting layer are combined, the organic semiconductor type charge generating layer is provided. Commercially available electrophotographic photosensitive member (OPC
A hydrophilic polysilane carrier (charge) transport layer may be thinly applied and formed on the organic semiconductor charge generation layer of the photoreceptor.

Next, a method of manufacturing the electrophotographic offset printing plate according to the present invention will be described with reference to FIGS. This manufacturing method includes the following steps A to C or steps A to D, and each step will be described in detail in order.

Step A: (Charging / Exposure / Electrostatic Latent Image) As shown in FIG. 3, the entire surface of the printing plate material 1 as a photoconductor is uniformly charged by corona discharge or the like. The charging polarity is
When polysilane is used, it is usually negatively charged because it exhibits negative chargeability (hole transport property). The negative charging is not the only option, and positive charging may be used.

Then, as shown in FIG. 4, light corresponding to image information is selectively irradiated to form an electrostatic latent image by negative charges on the surface of the photoconductor. The light incidence means may be an analog recording system in which a plate-making original is irradiated with light from a halogen lamp or the like and the reflected light is directly imaged on a photoconductor, as in a copying machine, or He-Ne, Ar. , Laser diode,
A so-called digital recording method in which light is modulated by a LED head, an EL head, a liquid crystal shutter, or the like in accordance with recording information and is irradiated may be used. In this digital recording method, it becomes possible to make an application in which a manuscript transmitted from a remote place using a digital line is directly plate-made to print a newspaper, which allows newspaper printing to be performed quickly and in a simple process. It is useful. In this case, it is possible to configure a system in which a buffer stage is provided on the receiving side, and after performing the typesetting / calibration there, a signal is input to the recording unit. In this way, for example, it becomes possible to manufacture newspapers by receiving individual newspaper article manuscripts from a plurality of senders at one receiver side and making a plate.

Step B: (Development) Next, as shown in FIG. 5, hydrophobic (lipophilic) toner 5 is dispersed on the surface of the photoconductor to form a toner image corresponding to image information. In this development, various electrophotographic development methods already proposed can be used.
High-definition images can be produced by dry development using a component developer or a two-component developer or liquid development in which developer particles are dispersed in a developer.

Step C: (Fixing) After the toner image is formed, the toner image 6 is fixed by a heating means such as a lamp or a heat fixing roller, whereby the electrophotographic offset printing as shown in FIG. Edition 7
To make. By this fixing, the toner 5 was melted and deformed, the coverage of the surface of the plate material was increased, and a printing plate with good contrast could be manufactured.

Thus, by the steps A to C, the oily ink is repelled by the outstanding hydrophilicity of the area other than the toner image 6, that is, the exposed surface 8 of the hydrophilic polysilane-based charge transport layer. The oil-based ink is dominantly placed on the toner image 6.

In the present invention, if the hydrophilic performance of the exposed surface 8 of the hydrophilic polysilane-based charge transport layer is insufficient even by the steps A to C, the following step D is continued. By doing so, the performance of the offset printing plate 7 can be complemented or enhanced.

Step D: (Corona discharge) In this step, the offset printing plate 7 obtained in Step C is exposed to corona discharge to further increase the hydrophilicity of the exposed surface 8 of the polysilane-based charge transport layer, As a result, the oily ink is repelled on the exposed surface 8 due to its remarkable hydrophilicity, and the oily ink is predominantly placed on the toner image 6.

As described above, according to the above manufacturing method, A to
The offset printing plate 7 can be manufactured while eliminating the need for ultraviolet irradiation in the steps C or A to D, thereby reducing the number of members by eliminating the need for another printing plate material. Furthermore, since chemical development elution processing by wet process is not performed, large-scale equipment is not required for pollution control such as wastewater treatment, and as a result, high performance and highly reliable offset printing plate can be provided by a simple device. It was

Next, examples of the present invention will be described.

[0033]

Examples (Example 1) An aluminum vapor-deposited film whose surface was completely washed was immersed in a liquid in which titanyl phthalocyanine and a polyester resin were dispersed and mixed in methylene chloride, and then dried at 55 ° C. under reduced pressure, A 15 μm thick titanyl phthalocyanine charge generation layer was formed. Next, this film was subjected to dechlorination polymerization of di (4-tri-n-butylsiloxybutyl) dichlorosilane and then desilylated with tri-n-butylammonium fluoride to obtain an average molecular weight of about 500,000. Di (4-hydroxybutyl) polysilane was immersed in a solution of ethyl alcohol and then 10
It was dried with hot air at 0 ° C. In this way, a hydrophilic polysilane-based charge transport layer having a thickness of 2 μm was formed to manufacture a printing plate material.

Next, the surface of the plate material is corona-charged with a DC voltage of -5 kV, and about -600 V is applied over the entire surface.
Was uniformly charged. Thereafter, a halogen lamp was used to form an image of reflected light from the original on the surface of the plate material to form an electrostatic latent image.

Next, the substrate of the plate material was developed with a negatively charged toner while a bias of 100 V was applied, whereby a high-definition image could be produced.

A toner image of a high-definition image corresponding to the image information is formed in this manner, and the toner image is fixed by a lamp, whereby the toner image can be used as an area where oily ink is attached. did it.

The offset printing plate thus obtained was used to print with an oil-based ink by an offset printing method, and as a result, high-resolution printing was possible. Further, even when the abrasion resistance test corresponding to the printing of 40,000 sheets was performed with this offset printing plate, and then printing was performed again, it was possible to print with almost no deterioration in resolution from the initial stage.

(Example 2) Next, an offset printing plate was once produced by the same production method as in (Example 1), and thereafter, the surface of the plate material was exposed to corona discharge by a DC voltage of -7 kV to carry out polysilane charge transport. The exposed surface of the layer was made even more hydrophilic, which caused the oily ink to be repelled on the exposed surface due to its marked hydrophilicity and, on the other hand, the oily ink to dominate the toner image.

The offset printing plate thus obtained was used to print with an oil-based ink by an offset printing method, and as a result, high-resolution printing could be performed. Further, even when the abrasion resistance test corresponding to the printing of 60,000 sheets was performed with this offset printing plate and then printing was performed again, it was possible to perform printing with almost no deterioration in resolution from the initial stage.

The present invention is not limited to the above embodiments, and various modifications and improvements can be made without departing from the scope of the present invention. For example, although a polysilane carrier (charge) transport layer was used as an example of the polymer charge transport layer having a hydrophilic surface, the same type of polymer material may be used.

[0041]

As described above, when offset printing is performed using the electrophotographic printing plate obtained by the production method of the present invention, high resolution and printing with high printing durability can be performed.
As a result, it can be applied to printing a large number of copies such as newspaper printing, and there is no fear of lead pollution problems as in conventional lead alloy plate making.

Further, in the present invention, since the electrostatic latent image can be formed easily and in a short time by laser scanning, there is an advantage that the manufacturing time is shortened and the manufacturing cost is thereby reduced.

Further, in the present invention, automated rapid plate making can be realized by combining with a transmission system utilizing a digital communication line.

Further, in the method of manufacturing an electrophotographic printing plate according to the present invention, it is not necessary to irradiate the printing plate material in which the organic semiconductor charge generation layer and the hydrophilic polymer charge transport layer are combined with ultraviolet rays. In addition, the need for a separate printing plate material reduces the number of parts, and because the development is performed in a dry process, there is no need for large-scale equipment for pollution control such as wastewater treatment, resulting in a simple device. We were able to provide offset printing plates with high performance and high reliability.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an electrophotographic printing plate material of the present invention.

FIG. 2 is a sectional view showing an electrophotographic printing plate material of the present invention.

FIG. 3 is a cross-sectional view showing a plate making process according to the present invention.

FIG. 4 is a cross-sectional view showing a plate making process according to the present invention.

FIG. 5 is a cross-sectional view showing a plate making process according to the present invention.

FIG. 6 is a cross-sectional view showing a plate making process according to the present invention.

[Explanation of symbols]

 2 substrate 3 organic-semiconductor-based photocarrier generation layer 4 hydrophilic polysilane-based carrier transport layer 5 toner 7 offset printing plate 8 exposed surface of hydrophilic polysilane-based charge transport layer

Claims (2)

[Claims] 1. A printing plate material in which an organic semiconductor charge generation layer and a polymer charge transport layer having a hydrophilic surface are sequentially laminated on a conductive support to form a toner image portion by the steps A to C below. A method for producing an electrophotographic offset printing plate, characterized in that the offset printing plate has the same and a lipophilic ink is adhered onto the toner image portion. A ... The printing plate material is charged and exposed to form an electrostatic latent image. B ... The printing plate material having the electrostatic latent image is developed to form a toner image portion which becomes a positive image. C: The developed printing plate material is fixed. 2. A printing plate material in which an organic semiconductor charge generation layer and a polymer charge transport layer having a hydrophilic surface are sequentially laminated on a conductive support to form a toner image portion by the steps A to D below. A method for producing an electrophotographic offset printing plate, characterized in that the offset printing plate has the same and a lipophilic ink is adhered onto the toner image portion. A ... The printing plate material is charged and exposed to form an electrostatic latent image. B ... The printing plate material having the electrostatic latent image is developed to form a toner image portion which becomes a positive image. C: The developed printing plate material is fixed. D ... The fixed printing plate material is exposed to corona discharge to enhance the hydrophilicity of the exposed surface of the polymer-based charge transport layer.