JP3117299B2 - Manufacturing method of printing plate for electrophotographic offset - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an electrophotographic offset printing plate comprising a combination of an amorphous silicon charge generation layer and a charge transport layer decomposed by ultraviolet irradiation such as polysilane.

[0002]

2. Description of the Related Art A method of manufacturing a printing plate using electrophotography has already been proposed. For example, according to the method proposed in Japanese Patent Application Laid-Open No. S51-143408, a toner image is formed on a photosensitive member. Is formed, the toner image is transferred to a printing plate material made of a photosensitive resin, and the printing plate material is entirely exposed to cause a photochemical reaction in a non-toner portion. The printing plate has irregularities corresponding to the above.

[0003] However, according to the method proposed above,
Since a printing plate material is required separately from 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.

In addition, as the photosensitive material described in the above publication, selenium, zinc oxide, organic semiconductor, cadmium sulfide and the like are merely exemplified.

According to Japanese Patent Application Laid-Open No. 58-72145, a photosensitive material is applied to the surface of a printing plate material, and a toner image is formed thereon by an electrophotographic method. Exposure causes a photochemical reaction in the non-toner portion, and then a development elution treatment is performed to obtain a printing plate having irregularities corresponding to image information.

[0006] However, this method is an improvement over the above-mentioned technique in that a printing plate material is not required separately from the photoreceptor, but on the other hand, since development elution is performed by a wet process, wastewater treatment and the like are performed. It is still unsolved that large-scale facilities are required for pollution control. Further, the above-mentioned photosensitive material merely exemplifies a photocurable resin or the like.

Further, 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-mentioned wet process.
Printing durability and image quality are improved by using a specific material for the binding resin. Since the development and elution are performed by a wet process, there is a similar problem.

The present inventors have made intensive studies in view of the above circumstances, and as a result, when an amorphous silicon layer is used as a photosensitive layer, when the surface of the photosensitive layer is exposed to corona discharge, the hydrophilicity of the surface is remarkable. Was found to be higher. In addition, it has been found that the combination of this photosensitive layer and a charge transporting layer laminated thereon, which is decomposed by ultraviolet irradiation, is useful for an offset printing plate.

The present invention has been completed on the basis of the above-mentioned knowledge, and has as its object the purpose of forming an offset printing plate having high performance and high reliability by ultraviolet irradiation and corona discharge without requiring large-scale equipment. An object of the present invention is to provide a method for manufacturing a printing offset printing plate.

[0010]

According to the method of manufacturing an electrophotographic offset printing plate of the present invention, an amorphous silicon-based charge generation layer (hereinafter abbreviated as a-Si) is provided on a conductive support. And a printing plate material in which a charge transport layer that is decomposed by irradiation with ultraviolet rays is sequentially laminated to form an offset printing plate by the following steps A to E.

A: The printing plate material is charged and exposed to form an electrostatic latent image.

B: The printing plate material on which the electrostatic latent image is formed is developed to form a toner image portion.

C: Fix the developed printing plate material.

D: The fixed printing plate material is irradiated with ultraviolet rays to decompose and remove the charge transport layer region located in the non-image area other than the toner image area.

E: Exposing the a-Si-based charge generation layer region from which the charge transport layer region has been decomposed and removed to corona discharge.

Hereinafter, the present invention will be described in detail with reference to FIGS.

FIG. 1 shows the structure of a printing plate 1 for producing an electrophotographic offset printing plate of the present invention. 2 is a conductive substrate, the material of which is aluminum, copper,
Metals such as zinc, SUS, nickel, brass, and the like, and those in which a conductive film is adhered to the surface of a heat-resistant resin are given. Further, the shape thereof is appropriately selected such as a flat plate shape, a sheet shape, and a drum shape. On the substrate 2, an a-Si-based photocarrier generation layer (charge generation layer) 3 and a carrier (charge) transport layer 4 (for example, a polysilane type) that is decomposed by ultraviolet irradiation are sequentially formed to form the plate material 1. The a-Si-based photocarrier generation layer 3 is made of amorphous SiC by adding and mixing carbon, nitrogen, oxygen, and germanium, in addition to a-Si.
It is formed of SiN, SiO, SiGe, or the like, or those further containing B, P, etc., which are impurity elements for controlling conductivity.

The photocarrier generating layer 3 has a function of enhancing the contrast of an electrostatic latent image as a photosensitive member, and its layer thickness is preferably in the range of 0.1 to 10 μm. Within this range, photocarriers are effectively generated, the internal stress of the film does not increase, and the film does not peel when repeatedly used as an offset printing plate. In particular, when the substrate is a flexible sheet, the thicker the a-Si film becomes, the lower the flexibility becomes, and the more easily the film is cracked or peeled off. Therefore, the thickness is preferably 10 μm or less.

The photocarrier generation layer 3 may be a single layer, but may have a laminated structure according to required characteristics. For example, a blocking layer that blocks injection of carriers of opposite polarity from the substrate 2 may be provided at the interface with the substrate 2. In addition, insulating a-
A hydrophilic layer such as SiO may be formed with a thickness of 1 μm or less so as not to hinder the carrier injection.
The exposed surface becomes easily compatible with the aqueous ink.

Such a photocarrier generation layer 3 is formed by a conventionally well-known glow discharge decomposition method, a reactive sputtering method, or the like.

The carrier transport layer 4 is formed of, for example, an ultraviolet-decomposable polysilane, and a polysilane represented by the following chemical formula 1 is selected.

[0022]

Embedded image

Such polysilanes include diethyl polysilane, dipropyl polysilane, dibutyl polysilane,
Diamyl polysilane, dihexyl polysilane, dicumyl polysilane, ethyl propyl polysilane, ethyl amyl polysilane, ethyl hexyl polysilane, propyl butyl polysilane, propyl amyl polysilane, propyl hexyl polysilane, propyl phenyl polysilane, propyl cumyl polysilane, butyl amyl polysilane, butyl hexyl polysilane , Butylphenylpolysilane, butylcumylpolysilane, amylhexylpolysilane, amylphenylpolysilane, amylmillpolysilane, hexylphenylpolysilane, hexylmillpolysilane, phenylcumylpolysilane, ethylbutylpolysilane, phenylethylpolysilane, cumylethylpolysilane, And diphenylpolysilane. In particular, cumylethyl polysilane is desirable in that it has a high decomposition rate upon irradiation with ultraviolet light.

The thickness of the polysilane-based carrier transport layer 4 is set so as to obtain irregularities required for an offset printing plate, and is preferably 10 μm or less, and more preferably 2 μm or less.

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 cumylethyl polysilane, the starting material is cumylethyl dichlorosilane, which is dechlorinated and polymerized to produce cumylethyl polysilane. This molecular weight is usually on the order of several thousand to one million. The polysilane thus formed is dissolved in a solvent such as toluene or tetrahydrofuran, and the photoreceptor substrate formed up to the photocarrier generation layer 3 is immersed in the solution and applied. Then, about 100
By drying with hot air at a temperature of 3 ° C., the photocarrier generation layer 3
The printing material 1 is completed by forming the polysilane-based carrier transport layer 4 thereon.

Next, a method for producing an 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 E, and each step will be described in detail below.

Step A: (Charging / Exposure / Electrostatic Latent Image) As shown in FIG. 2, the entire surface of the printing plate 1 as a photosensitive member is uniformly charged by corona discharge or the like. The charging polarity is
When polysilane is used, it is usually negatively charged because it shows negative chargeability (hole transport property). It should be noted that the present invention is not limited to the negative charge, but may be a positive charge.

Next, as shown in FIG. 3, light corresponding to image information is selectively irradiated to form an electrostatic latent image by negative charges on the surface of the photoreceptor. As the light incident means, an analog recording method may be used in which a plate-making manuscript is irradiated with light such as a halogen lamp as in a copier and the reflected light is directly imaged on a photoreceptor, while He-Ne, Ar , Semiconductor lasers,
A so-called digital recording method, in which light is modulated and irradiated according to recording information using an LED head, an EL head, a liquid crystal shutter, or the like, may be used. In this digital recording system, it is possible to make an original transmitted from a remote place using a digital line and directly make a plate to print a newspaper. This makes it possible to print a newspaper quickly and in a simple process. Useful. In this case, it is possible to configure a system in which a buffer stage is provided on the receiving side, where the typesetting and calibration are performed, and then the signal is input to the recording unit. In this way, for example, it becomes possible to produce a newspaper by receiving individual newspaper article manuscripts from a plurality of transmitting sides at one receiving side and performing typesetting.

Step B: (Development) Next, as shown in FIG. 4, a UV-absorbing (black) toner 5 is sprayed on the surface of the photoreceptor to form a toner image corresponding to image information. In this development, various methods that have already been proposed can be used.For example, there are elution with an alkaline aqueous solution, elution with an organic solvent, elution with water, and the like. , Can produce high-definition images.

Step C: (Fixing) After drying the toner solvent, the toner image is fixed by a lamp. As a result, the toner is melted and deformed to increase the coverage of the surface of the plate material, and light leakage from gaps between the toner particles is prevented, so that a printing plate having good contrast can be manufactured. In addition, if the toner is lipophilic, it can repel the water-based ink and place the ink in the recessed area of the offset printing plate.

Step D: (Ultraviolet irradiation decomposition) When the entire surface of the photoreceptor is irradiated with ultraviolet rays as shown in FIG.
The ultraviolet light applied to the toner-adhered area is absorbed by the toner 5 and does not reach the carrier transport layer 4 made of polysilane or the like. However, when the ultraviolet light is applied to the area where the toner is not applied, as shown in FIG. The region of the carrier transport layer 4 located is decomposed and sublimated, and the region is removed. Thus, the electrophotographic offset printing plate 6 of the present invention can be manufactured. Incidentally, reference numeral 4a in FIG. 6 denotes a remaining carrier transporting layer located in the toner attachment area.

In the case of the polysilane-based carrier transporting layer 4 of which material is appropriately designed, it can be decomposed and removed only by irradiation with ultraviolet rays. However, if the removal is insufficient or the unevenness is small, the residue is not removed. When the influence is large, it is necessary to completely remove the residue, and for that purpose, it is only necessary to air blow or press the pressure-sensitive adhesive sheet against the plate material surface.

Step E: (Corona Discharge) In this step, the electrophotographic offset printing plate 6 obtained in Step D is exposed to corona discharge to expose the a-Si-based photocarrier generation layer 3 to the exposed region. Is oxidized to increase the hydrophilicity of the exposed area. As a result, the water-based ink can be placed on the recessed region of the offset printing plate 6 with superiority.

Thus, according to the above manufacturing method, a-Si
The plate material 1 in which the system photocarrier generation layer 3 and the carrier transporting layer 4 decomposed by ultraviolet irradiation are combined is manufactured by the ultraviolet irradiation decomposition in the D step and the corona discharge in the E step. No printing plate material is required, the number of components is reduced, and the development and elution is performed by a dry process, so large equipment is not required for pollution control such as wastewater treatment. A reliable offset printing plate was provided. Next, examples of the present invention will be described.

[0035]

EXAMPLE An aluminum substrate whose surface was completely cleaned was mounted in a glow discharge decomposition apparatus, and the inside of the reaction vessel was completely evacuated. Then, a discharge was first performed while flowing SiH ₄ gas and PH ₃ gas at a constant rate. Apply voltage and apply 0.1 μm thick a-Si
-An H carrier injection blocking layer was formed. Thereafter, the injection of the PH ₃ gas was stopped, and the flow rate of the SiH ₄ gas was controlled at a constant flow rate to form a 0.2 μm-thick a-Si · H carrier generation layer. Next, the substrate was taken out of the reaction vessel, and immersed in a solution of cumylethyl polysilane having an average molecular weight of about 100,000, which was produced by dechlorination polymerization of cumylethyldichlorosilane, and dissolved in toluene. Dry with hot air. Thus, a polysilane carrier transporting layer having a thickness of 1 μm was formed, and a printing plate material was manufactured.

Next, the surface of the plate material was corona-charged with a DC voltage of -5 KV, and the surface of the plate material was charged to about -200 V
To be uniformly charged. Thereafter, the reflected light from the original was imaged on the surface of the plate using a halogen lamp to form an electrostatic latent image.

Next, in a state where a bias of 100 V was applied to the plate material substrate, reverse development was performed using negatively charged toner.
According to this development, liquid development was performed by passing the solution through an electrode with an alkaline aqueous solution, whereby a high-definition image could be produced.

After the toner image of the high-definition image corresponding to the image information was formed in this manner, the toner solvent was dried, and the toner image was fixed by a lamp. Thereafter, the wavelength of the low-pressure mercury lamp was 253.7 over the entire surface of the plate material.
nm ultraviolet light (light quantity 500 to 1000 mJ / cm ² )
Was irradiated. As a result, the polysilane layer region where the toner does not adhere is decomposed and removed, and finally, a small amount of residue is removed by air blowing to form an offset printing plate having 1 μm unevenness corresponding to the thickness of the polysilane layer. Manufactured.

Further, the printing plate for offset was exposed to corona discharge using a corona discharger to which a DC voltage of -5 KV was applied.

Using the offset printing plate thus obtained, printing was performed by the offset printing method, and as a result, high-resolution printing was possible. In addition, even after the abrasion resistance test corresponding to the printing of 40,000 sheets was performed using this printing plate for offset, and printing was performed again, printing with almost no deterioration in resolution from the initial stage was possible.

[0041]

As described above, when offset printing was performed using the electrophotographic printing plate obtained by the manufacturing method of the present invention, printing with high resolution and high printing durability was obtained.
This makes it possible to apply the method to printing of a large number of copies, such as newspaper printing, and eliminates the risk of a lead pollution problem 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, thereby reducing the manufacturing cost.

Further, in the present invention, it is possible to perform automated and rapid plate making by combining with a transmission system using a digital communication line.

In the method for producing an electrophotographic printing plate according to the present invention, a printing plate material comprising a combination of an a-Si charge generating layer and a charge transporting layer which decomposes upon irradiation with ultraviolet light is irradiated with ultraviolet light. Incorporating each process of decomposition and corona discharge eliminates the need for separate printing plate materials, reduces the number of members, and requires large-scale equipment for pollution control such as wastewater treatment because development and elution are performed by a dry process. As a result, a high-performance and highly reliable offset printing plate could be provided by a simple device.

Further, since the a-Si photosensitive layer is used, its advantages such as abrasion resistance, heat resistance, photosensitivity and pollution-free properties are exhibited. The plate could be used for a long time.

[Brief description of the drawings]

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

FIG. 2 is a sectional view showing a plate making process according to the present invention.

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

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

FIG. 7 is a sectional view showing a plate making process according to the present invention.

[Explanation of symbols]

 2 Substrate 3 Photocarrier generation layer 4 Carrier transport layer 5 Toner

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-43367 (JP, A) JP-A-5-134477 (JP, A) JP-A-5-197177 (JP, A) JP-A-3-197 35248 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 5/07-5/07 105 G03G 5/08 105 G03G 13/26-13/32 B41N 1/14

Claims (1)

(57) [Claims] 1. An offset printing plate obtained by sequentially laminating an amorphous silicon-based charge generation layer and a charge transport layer decomposed by ultraviolet irradiation on a conductive support by the following steps A to E: A method for producing an electrophotographic offset printing plate, which is characterized by the following. A: The printing plate material is charged and exposed to form an electrostatic latent image. B: The printing plate material on which the electrostatic latent image is formed is developed to form a toner image portion. C: The developed printing plate material is fixed. D: The fixed printing plate material is irradiated with ultraviolet rays to decompose and remove the charge transport layer region located in the non-image area other than the toner image area. E: Exposing the amorphous silicon-based charge generation layer region from which the charge transport layer region has been decomposed and removed to corona discharge.