JPS6120048A - Original plate for printing - Google Patents

Abstract

PURPOSE:To provide a printing plate which forms an image having good resolution and sharpness by providing a photoconductive layer on a conductive base of which the surface has a surface shape having 0.2-0.6mum average roughness of center lines and removing the non-image part after forming a toner image. CONSTITUTION:A plate such as, preferably an aluminum plate or a plate of an aluminum alloy consisting essentially of aluminum and contg. zinc, magnesium, iron, etc., an iron plate subjected to a surface treatment or a bi-metal plate or tri-metal plate which has a hydrophilic surface and has the surface shape of 0.2mum-0.6m, more preferably 0.25-0.55mum in average roughness (Ra) of center lines is used for the conductive base. For example, a mechanical method or a method for etching by electrolysis is used for forming the surface shape. The formation of the photoconductive layer on the conductive base is executed by dissolving, for example, an alkali soluble resin in a solvent, adding a prescribed amt. of photoconductive body thereto, dissolving the same or dispersing the same by a method such as ball mill or colloid mill, coating uniformly the resulted photosensitive liquid on the conductive base and drying the same.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a printing original plate having a photoconductive layer on a conductive support. Regarding the improvement of a printing original plate for creating a printing plate by removing the conductive layer, a printing plate with good image resolution and sharpness can be obtained, is free from scumming, and has a long printing life. The present invention relates to a printing original plate that allows a printing plate with high quality to be obtained.

Prior Art For example, in order to create a lithographic printing plate, a plate-making method is also used in which the photosensitive layer on the surface of the original plate is directly exposed through the original, thereby forming hardened and non-hardened areas corresponding to the image and non-image areas of the original. The PS plate is known as the original plate for this purpose, but a method of creating a lithographic plate using electrophotographic technology, which has higher sensitivity than the method of creating a lithographic plate by such exposure, is also widely used. The original version is also produced.

Conventionally, as printing original plates using the principles of electrophotographic technology, for example, Japanese Patent Publications Nos. 47-47610 and 48-400
Zinc oxide described in No. 02, No. 4B-18325, No. 51-15766, No. 51-25761, etc.
A resin dispersion type offset printing original plate is known, and in such an offset printing original plate, a toner image is formed using an electrophotographic method, and then non-image areas other than the toner image area are desensitized. It is used as a printing plate by processing. However, in this type of printing plate, the image area is formed only of toner particles, so the printing durability is poor, and the number of sheets printed with this original plate is approximately 5.00.
It is limited to approximately 00 to io, ooo sheets, and cannot be used for printing larger numbers of sheets.

Furthermore, in order to perform the desensitization treatment, it is necessary to use an acidic solution such as an alkali ferrocyanide salt, which poses problems in terms of pollution control and occupational health.

In addition, Japanese Patent Publications No. 37-17162, No. 3B-7758, No. 46-39405, Japanese Patent Publication No. 52-2437, No. 57-161863, No. 5B-2854, No. 58-
No. 28760 and No. 58-118658, etc., disclose a printing original plate in which an organic photoconductor is held in a resin.
For example, a photoreceptor is used in which a photoconductive layer of an oxazole or oxadiazole photoconductor bound with a styrene-maleic anhydride copolymer is provided on a grained aluminum plate. A method is disclosed in which a toner image is formed by a method, and then the photoconductive layer in non-image areas is removed using an alkaline organic solvent to form an image and a printing plate is created. This plate-making method has long printing durability because the image area consists of not only the toner image area but also the photoconductive layer below it, so even if the toner image area is worn out, the photoconductive layer maintains the function of the image area. Excellent for. These include ethylene glycol, glycerin,
Organic solvents such as isopropyl alcohol and benzyl alcohol are used.

On the other hand, there are printing original plates in which the photoconductive layer in non-image areas can be removed using an alkaline aqueous solution that does not contain organic solvents.
It is described in publications such as No. 9-12452 and No. 59-49555.

The main components of the original printing plates described in these publications are:
A photoconductive layer consisting of a photoconductive pigment such as copper phthalocyanine and an alkali-soluble resin such as phenolic resin is provided on a grained and anodized aluminum plate. It has the following advantages.

■High sensitivity.

■Has color sensitivity over the entire visible range, and is sensitive to white light and He-N.
Image recording must be possible with an e-laser or a semiconductor laser that oscillates in the near-infrared region.

(2) A photoconductive layer can be obtained that is easily soluble in an alkaline aqueous solution containing no organic solvent.

■Excellent electrostatic properties such as charge storage and moisture resistance.

■Excellent printing durability.

etc.

As a result of further research into this printing original plate, which has these various advantages, the present inventor found that this printing original plate is prone to halation due to the large surface roughness of the conductive support, and the resolution and sharpness of images are poor. Not only is this unfavorable in terms of plate making, such as sharpness, but also the elution of non-image areas is not complete, resulting in a phenomenon called pigment residue, which causes background stains on printed matter when used as a printing plate. It has been found that this has an unfavorable adverse effect on printability.

It has also been found that if the surface roughness of the conductive support of the printing original plate is too small, the adhesion of the photoconductive layer to the support will be insufficient, resulting in insufficient printing durability.

The above drawbacks are not limited to those in which the photoconductive layer consisting of a photoconductive pigment and an alkali-soluble resin can be eluted with an alkaline aqueous solution, but also in original printing plates in which the photoconductive layer is provided on a conductive support. It's about being seen.

OBJECTS OF THE INVENTION An object of the present invention is to provide a printing original plate that prevents halation in a printing original plate having a photoconductive layer, thereby providing a printing plate with good image resolution and sharpness. It's about doing.

Another object of the present invention is to provide a printing original plate that has high printing durability, is free from scumming of printed matter, and has good water retention properties.

The above object of the present invention is that the center line average roughness (Ra) of the surface is 0.
．． This is achieved by a printing original plate using a conductive support having a surface topography of 2 to 0.6 .mu.m.

The printing original plate according to the present invention has at least a photoconductive layer on a conductive support.

The conductive support is preferably an aluminum plate or an aluminum alloy containing aluminum as a main component and containing zinc, magnesium, iron, etc., an iron plate surface-treated with chrome plating, aluminum plating, etc., a chrome-steel plate, an aluminum-steel plate. It has a hydrophilic surface such as a bimetal plate such as a chromium-copper-steel plate or a tri-metal plate such as a chromium-copper-stainless plate, and has a center line average roughness (Ra) of 0.
2μ- to 0.6μ fat, preferably 0.25μ- to 0
．． A treatment with a surface profile of 55μ is used. Particularly preferred is a plate whose surface is made of aluminum.

Here, the center line average roughness (Ra) is the German standard DIN
476B is the arithmetic mean of the absolute values of the distances from the center line to each point on the profile, with the horizontal center line as the X axis and the vertical direction as the Y axis. and the point on the roughness profile is (χ + y)
When expressed by
For example, it can be measured using a belt meter manufactured by Perthen.

Examples of methods for forming such a surface shape include a mechanical method and an electrolytic etching method.

Examples of mechanical methods include ball polishing, brush polishing, liquid honing, and puff polishing. Examples of the electrolytic etching method include etching using a solution containing phosphoric acid, sulfuric acid, perchloric acid, hydrochloric acid, nitric acid, pyrophosphoric acid, hydrofluoric acid, etc.

In the above surface roughening method, in order to improve the water retention property of the aluminum support, electrolytic polishing using an electrolyte mainly containing nitric acid is a method to create deeper, denser and more uniform grains than a certain level. Preferable. For example, Special Publication Showa 4B-2
The methods described in JP-A No. 8123 and JP-A No. 55-25381 can be used.

The depth of the grain can be arbitrarily set by controlling the electrolytic conditions, but in order to achieve the object of the present invention, Ra is 0.
．． 2 μR should be in the range of 1 to 0.6 μR.

After the graining treatment, if necessary, a desmut treatment is performed using an aqueous alkali or acid solution, followed by neutralization and washing with water.

Further, the grained aluminum plate is further subjected to anodizing treatment if necessary. When electrolysis is carried out using sulfuric acid, oxalic acid, phosphoric acid, chromic acid, etc., or a mixture of two or more of these as the electrolytic solution, and aluminum is used as an anode, an oxide film is formed on the aluminum surface.

For example, in a sulfuric acid aqueous solution with a concentration of 10 to 20% by weight, a bath temperature of 10 to 30°C, a voltage of 15 to 20ν, a current density of 1 to 2 A/
dnf, conditions for time 2 to IO minutes, and concentrations 1 to 3.
In a 0% by weight phosphoric acid aqueous solution, bath temperature 20-70°C, voltage 20-50V, current density 1-2A/dnf, time.

Examples include a method in which the treatment is carried out for 0.5 to 10 minutes. The amount of anodic oxide film formed in this way is 5 to 70w/d
% is suitable, and preferably an amount of 15 to 30 .mu./drr+ is suitable for printing plates.

The anodized aluminum material may be subjected to treatments such as surface treatment and lining. This surface treatment consists of anodization by immersion in a hot aqueous solution of sodium silicate, hot water, and some inorganic or organic salts, or by a steam bath. This refers to the sealing treatment that is performed immediately after the oxidation treatment.

When the roughened aluminum material is thin like foil, a metal plate, plastic film, paper, etc. may be attached to the back surface directly or via an adhesive layer.

If the surface roughness of these roughened conductive supports exceeds Ra of 0.6 μm, the effect of halation will be significant, resulting in poor image resolution and sharpness. This is not practical. These results appear to be due to the fact that the printing original plate of the present invention has significantly higher sensitivity than conventional PS plates that utilize photochemical reactions.

In addition, when a non-image area of a photoconductive layer using a phthalocyanine pigment (described below) is eluted with an alkaline aqueous solution, pigment remains, which causes background stains on printed matter when used as a printing plate. It was found that this had an undesirable adverse effect on printability. When Ra is 0.2 μ- or less, the above-mentioned adverse effects are not observed, but as a result of poor adhesion with the photoelectric layer, printing durability and water retention in terms of printability tend to be poor, which is not preferred in practice. .

As mentioned above, it was preferable to use nitric acid electropolishing and anodic oxidation as the grain, which has good adhesion, excellent stiffness resistance, and good water retention.

Therefore, the aluminum support used in the present invention should be one that has been subjected to nitric acid electropolishing, anodizing treatment, and sealing treatment and has a surface roughness Ra in the range of 0.2 to 0.6 μ-. More preferable to achieve.

To form a photoconductive layer on the conductive support, for example, an alkali-soluble resin is dissolved in a solvent, and then a predetermined amount of photoconductor is added, and then melted or milled using a ball mill, glass beads, sand mill, colloid mill, etc. A homogenized photosensitive solution is prepared by dispersion using a known method.

The obtained photosensitive liquid was applied to the surface of the conductive support at Ra.

It is uniformly coated onto a conductive support roughened to 0.02 μl to 0.6 μl using a wire bar, roll coater, applicator, etc., and dried.

As the alkali-soluble resin, JP-A-54-134
632, Copper No. 55-105254, etc., and acid group-containing resins such as acrylic acid resin, crotonic acid resin, itaconic acid resin, maleic acid resin, etc., but in particular, the above-mentioned alkaline aqueous solution is used as the eluent. Phenol resin is preferable in order to exhibit the advantages of Φ to ■ of the printing original plate.

The phenolic resin used in the present invention includes phenol or 0-cresol, pycresol, p-cresol, ethylphenol, isopropylphenol, t-cresol,
A small number of substituted phenols such as aminophenol, hexylphenol, t-octylphenol, 3-methyl-4-chloro-6-t-butylphenol, isopropylcresol and cyclohexylcresol (and one type of substituted phenol, formaldehyde, acetaldehyde, acrolein,
Resins obtained by condensing aliphatic aldehydes such as crotonaldehyde and furfural are typically used. Also used is a polyhydroxyphenol resin obtained by polycondensation of pyrogallol or resorcinol with acetone or benzaldehyde.

Among these phenolic resins, preferred are alkali-soluble resins obtained by condensing o-cresol, -mono-cresol, p-cresol, or phenol alone or in combination with formaldehyde. Other resins may also be used in combination to improve alkali solubility, film formation, and lipophilicity as long as they do not substantially inhibit removal of the photoconductive layer by an alkaline aqueous solution.

The photoconductor used in the present invention is at least one of inorganic photoconductors, organic photoconductors, and photoconductive organic pigments. As the inorganic photoconductor, for example, selenium-based, zinc oxide-based, cadmium sulfide-based, etc., which are known in electrophotography, are used. Examples of organic photoconductors include polyvinylcarbazoles, oxazoles, and biryllium salts. As a photoconductive organic pigment, JP-A-47-3
perylene pigments described in JP-A-47-30331, etc., bisbenzimidazole pigments described in JP-A-47-18543, etc.; Showa 47-1854
No. 4, No. 55-98754, No. 55-1216254
No. 55-163543, aromatic polyfused ring compounds described in Japanese Patent Publication Nos. 44-16474 and 48-305
No. 13, azo pigments described in JP-A-56-321465, etc., JP-A-50-7434, JP-A-47-375, etc.
No. 43, No. 55-11715, No. 564944, No. 56-9752, No. 56-2352, No. 5B-80
Bisazo pigment described in Publication No. 050 etc., Japanese Patent Publication No. 44-1
No. 2671, No. 46-30035, No. 49-1753
No. 5, JP-A-49-11136, JP-A No. 49-99142
There are phthalocyanine pigments etc. described in No. 57-148745, etc., and these can be used alone or in a mixture of two or more types, but in particular, in order to jointly exhibit the advantages of (1) to (3) above. Phthalocyanine i! fil+ is preferably used.

Phthalocyanine [14 includes alpha (α), heter (β), gamma (γ), pi (π), X (
X ) and epsilon (ε) type metal-free phthalocyanines or metal phthalocyanines such as copper nickel and cobalt zinc are preferred. These phthalocyanine pigments are disclosed in, for example, Japanese Patent Publication No. 40-2780, Japanese Patent Publication No. 45-8102, Japanese Patent Publication No. 4B-11.
021 Hikari, No. 46-42511, No. 46-42512
No. 48-163, No. 48-34189, No. 49
No. 47535, No. 49-4338, No. 50-5059
No. 5 and Japanese Unexamined Patent Publication No. 50-38543.

Furthermore, in the present invention, a known sensitizer can be used in combination for the purpose of adjusting the sensitivity or sensitive wavelength range. These sensitizers include JP-A Nos. 47-30330 and 47-3.
No. 0331, No. 47-30332, No. 55-1612
Electron donor substance described in Publication No. 50 etc., JP-A-47-30
330, 55-15394, etc., or JP-B No. 40-7333, JP-A-54-1
Sensitizers described in Japanese Patent No. 34632 and the like can be used.

The mixing ratio of the resin used for the photoconductive layer and the photoconductor is preferably from 1:10 to 1:1, and the thickness of the photoconductive layer made of these is from 20 mg/drI (to 80 μg/drI).
Preferably between dad.

The photoconductive layer removal solution (eluent) used in the present invention is:
For example, it is an eluent that can dissolve and remove the photoconductive layer without eluting the developer (toner) film, and it can be an alkaline aqueous solution such as sodium silicate or potassium silicate solution, or an organic solution such as ethylene glycol, isopropyl alcohol, or benzyl alcohol. Although a solution containing a mixture of solvents may be used, a preferable treatment liquid is, for example, an alkaline aqueous solution having a pH of 12 to 13.

In addition to obtaining a toner image by reflection exposure using a xenon lamp, halogen lamp, tungsten lamp, or fluorescent lamp as a light source after charging the printing original plate of the present invention by ordinary electrophotography, a semiconductor laser Ar or 1le-N
The toner image can be obtained by exposure to laser light such as e, or by projection n light or contact exposure through a transparent positive film. After obtaining a toner image by such a method, the non-image area (portion to which toner does not adhere) is dissolved and removed by immersion in the eluent, and only the toner-adhered area remains on the surface of the support, resulting in a good printing plate. can be obtained. In addition, after the toner image is formed on the printing original plate of the present invention,
A quinonediazide compound (for example, 0-naphthoquinonediazide) or a diazo compound may be contained in the photoconductive layer for the purpose of increasing the solubility of the photoconductive layer by full-surface n-light.

Effects of the invention The surface of the conductive support has a center line average roughness (Ra) of 0.2.
A photoconductive layer is provided on a conductive support having a surface shape of .mu.ml to 0.6 .mu.m, and after forming a toner image by electrophotography, removing the non-image area with an alkaline solution improves the resolution of the image. In addition, when used as a printing plate, it is possible to reduce background staining of printed matter, improve water retention, and improve stiffness.

As a support, the aluminum plate is grained by electropolishing in a nitric acid bath and anodized, resulting in a finer grain shape on the surface, which further improves image resolution and dot quality (sharpness). Moreover, the adhesion with the photoconductive layer is also excellent, and a printing plate with higher printing durability can be obtained. Furthermore, since the amount of pigment remaining in non-image areas can be further reduced during elution of the photoconductive layer with an alkaline eluent, background staining of printed matter can be reduced when used as a printing plate.

Next, the present invention will be explained in detail with reference to examples, but the embodiments of the present invention are not limited by these examples.

Example 1 An aluminum plate having a thickness of 0.24 m++ was immersed in an aqueous solution containing 1% sodium hydroxide at 50° C. for 10 seconds to degrease it, and then washed with water. This aluminum plate was subjected to AC electrolytic etching in a 0.4 mol/l nitric acid aqueous solution at 30° C. and a current density of 50 A/dnr for different times. 5% after this
After desmutting in an aqueous sodium hydroxide solution at 60°C for 10 seconds, neutralization and washing with water were performed, and an additional 20%
After anodic oxidation in a sulfuric acid bath at a current density of 3 A/drrr at 20° C. for 1 minute, sealing treatment was performed with hot water at 90° C.

The surface roughness of the aluminum plate thus obtained was measured using a surface roughness needle belt meter S5P manufactured by Pelten, and a grain with a center line average roughness (Ra) of 0.25 μm was obtained. .

A photoconductive layer was formed on this aluminum plate in the following manner.

Rio Photon EK 1 part by weight (Type 8 copper phthalocyanine manufactured by Toyo Ink Co., Ltd.) Phenol and m-1p
- Cocondensation resin of mixed cresol and formaldehyde (molar ratio of phenol and cresol to 3 near, weight average molecular weight 1.500) 3 parts by weight ethylene glycol monoethyl ether 15 parts by weight The composition according to the above weight ratio was mixed with glass beads for 15 minutes. dispersed,
A dispersion was obtained. This dispersion was applied onto the aluminum plate using a wire bar and dried. The film thickness after drying was about 60 .mu./dn. The printing original plate of this example was prepared by drying for about 1 hour in the drying box at t&90.degree.

Corona discharge is applied to this printing master plate so that the surface potential becomes +90ν, and a positive image is reflectively exposed to tungsten light (
40 lux/sec), then use liquid developer (P manufactured by Ricoh).
PC-1000 and Sanyo Chemical's Nwanx 171-P
-t- (mixed and dispersed at a weight ratio of 25:I) was used for development, and an image with a resolution of 12.5 lines/+a- could be obtained. In addition, the sharpness of the image was also good. This original printing plate is 5DP-1
The photoconductive layer was immersed for 45 seconds in a 7-fold diluted solution of sodium silicate (manufactured by Konishi Roku Photo Industry Co., Ltd.: sodium silicate aqueous solution) for 45 seconds to dissolve and remove the photoconductive layer in the area to which toner was not attached (non-image area). As a result, a printing plate faithful to the toner image could be obtained.

Next, this printing plate was used to print on an off-cent printing machine (Hamada Star 900 CDX).
Up to 10,000 copies of good printed matter were obtained. In addition, this printing plate did not cause staining on the background of printed matter and had good water retention.

Comparative Example 1 Graining and surface treatment were carried out in the same manner as in Example 1.
A printing original plate of Comparative Example 1 was prepared in the same manner as in Example 1 except that an aluminum plate with a diameter of 0.8 μ- was prepared, and when charging, exposure, and development were performed, the resolution was 6.
Only 3/-1 images were obtained, and the sharpness of the images was also not good, which was inferior to the sample of Example 1. Furthermore, when the photoconductive layer in the non-image area was removed by the same method as above, pigment remained in the non-image area, making the plate unsuitable as a printing plate.

Example 2 Graining and surface treatment were carried out in the same manner as in Example 1, and Ra was 0.
．． A printing original plate of Example 2 was prepared in the same manner except that a 4μ aluminum plate was used. Charging, exposure, and development were performed in the same manner as in Example 1, and the resolution was 12.5 lines/1 m.
I was able to obtain an image of 1. In addition, the sharpness of the image was also good. Furthermore, elution was carried out in the same manner as in Example 1, and a printing plate faithful to the toner image could be obtained.

Next, this printing plate was used for printing with an offset printing machine, and up to 200,000 copies of good printed matter were obtained. In addition, this printing plate did not cause any staining on the background of the printed matter and had good water retention.

Example 3 A printing original plate of this example was prepared in the same manner as in Example 1 except that the photoconductive layer was formed with the following composition.

Chromophthal Blue 4GN I heavy It part (
β-type copper phthalocyanine (manufactured by Ciba Geigy) Co-condensation resin of phenol, a+-1p- mixed cresol, and formaldehyde (molar ratio of phenol and cresol to 3 near, weight average molecular weight 1,500) 5.7 parts by weight ethylene glycol monoethyl ether 27 parts by weight Example 1
After performing charging, exposure, and development in the same manner as above, the printing original plate of this example had a resolution of 12.5 at a light intensity of 80 lux·sec.
Book/1111 ii! It was possible to obtain an image, and the sharpness of the image was also good. Furthermore, elution was carried out in the same manner as in Example 1, and a printing plate faithful to the toner image could be obtained.

Next, printing was carried out using an offset printing machine using this printing plate, and up to 200,000 copies of good printed matter were obtained. In addition, this printing plate did not cause any staining on the background of the printed matter and had good water retention.

Comparative Example 2 A printing original plate of Comparative Example 2 was prepared by applying and drying the photosensitive liquid used in Example 3 to the aluminum plate prepared in Comparative Example 1 in the same manner as in Example 1, and this printing original plate was used in Example 2. When charging, exposing, and developing were carried out in the same manner as in 1, an image with a resolution of only 6.3 lines/m11 was obtained at a light intensity of 80 lux·sec.
In addition, the sharpness of the image was not good and was inferior to that produced from the printing original plate of Example 3.

Furthermore, when the photoconductive layer in the non-image area was removed in the same manner as in Example 1, pigment remained in the non-image area and the plate could not be passed as a printing plate.

Example 4 Printing of Example 4 was carried out in the same manner as in Example 1 except that grain quality, anodization and sealing were carried out in the same manner as in Example 1, and an aluminum hoe with Ra of 0.55 μ- was used. A master version was created. When charging, exposure and development were carried out in the same manner as in Example 1, an image with a resolution of 12.5 lines/mtn could be obtained. In addition, the sharpness of the image was also good. Further, elution was carried out in the same manner as in Example 1, and printing faithful to the toner image could be obtained.

Example 5 Electrolytic etching, anodizing, and sealing were performed in the same manner as in Example 1, except that an aqueous solution containing 17 g/l of hydrogen chloride was used as the electrolytic bath. The surface of the aluminum plate thus obtained has an Ra of 0.45 μm.
It had a dense and uniform grain texture. Example 5 was carried out in the same manner as in Example 1 except that this aluminum plate was used.
The original printing plate was created. When charging, exposure and development were carried out in the same manner as in Example 1, an image with a resolution of 10 lines/vam could be obtained. In addition, the sharpness of the image was also good. Furthermore, elution was carried out in the same manner as in Example 1, and a printing plate faithful to the toner image could be obtained.

Next, this printing plate was used for printing with an offset printing machine, and up to 150,000 copies of good printed matter were obtained. Furthermore, this printing plate did not cause staining on the background of printed matter during printing and had good water retention.

Comparative Example 3 An aluminum plate with a surface Ra of 0.8 μm was prepared by graining, electrolytic etching, anodizing, and sealing in the same manner as in Example 5, except that this aluminum plate was used. A printing original plate of Comparative Example 3 was prepared in the same manner as Example 5, and after being charged, exposed and developed, the resolution was 5 lines/l.
Only an image of 1 ll+ was obtained, and the sharpness of the image was not good, and was inferior to that produced from the printing original plate of Example 5.

Example 6 An aluminum plate with a thickness of 0.24 mm was roughened with a rotating brush using an abrasive and water suspension, and washed with water for 20 minutes.
After anodizing for 1 minute at 20°C in an aqueous solution of sulfuric acid, the aluminum plate was sealed with hot water at 90°C.The surface of the aluminum plate thus obtained had an Ra of 0.
．． It was 25 μm.

Chromophthal Blue 4GN (described above) 1 part by weight - Cresol novolac resin (weight average molecular weight 2000) 2.3 parts by weight Ethylene glycol monoethyl ether 15 parts by weight The composition according to the above weight ratio was dispersed for 15 minutes using glass beads to form a dispersion liquid. I got it. This dispersion was applied onto the aluminum plate using a wire bar.

The film thickness after drying is approximately 60■/dn? Met. This l&9
The printing original plate of Example 6 was prepared by drying at 0° C. for 1 hour.

When this printing original plate was charged, exposed, and developed in the same manner as in Example 1, the resolution was 2.2 mm at a light intensity of 80 lux·sec.
It was possible to obtain images of 5 lines/1 m1. In addition, the sharpness of the image was also good.

Furthermore, elution was carried out in the same manner as in Example 1, and a printing plate faithful to the toner image could be obtained.

Next, printing was carried out using an offset printing machine using this printing plate, and up to 200,000 copies of good printed matter were obtained. In addition, this printing plate did not cause any staining on the background of the printed matter and had good water retention.

Comparative Example 4 The same process as in Example 6 was carried out by changing the roughness of the abrasive.
An aluminum plate of steel with a of 0.8μ was prepared.

A printing original plate of Comparative Example 4 was prepared in the same manner as in Example 6 except that this aluminum plate was used. When this printing plate was charged, exposed, and developed in the same manner as in Example 1, an image with a resolution of only 6.3 lines/11 was obtained at a light intensity of 80 lux·sec, and the sharpness of the image was also poor. It was not good and was inferior to that made from the printing original plate of Example 6. Furthermore, when the photoconductive layer in the non-image area was removed in the same manner as in Example 6, pigment remained in the non-image area and the plate could not be passed as a printing plate.

Example 7 Ethyl acrylate/butyl acrylate/methacrylic acid (molar ratio 70/10/20) copolymer (molecular weight 120,000) 10 parts by weight 1.3.5
Triphenylpyrazoline 7 parts by weight Rhodamine B
O.05 Commercial weight: Tetrahydrone run 80i: 11 parts A printing original plate of Example 7 was prepared in the same manner as in Example 1 except that the photoconductive layer was formed with the above composition. Charging as in Example 1,
When exposure and development were carried out, an image with a resolution of 12.5 lines/lI- could be obtained at a light intensity of 120 lux·sec.

In addition, the sharpness of the image was also good. Furthermore, the non-image area was removed by immersing the plate in an eluent consisting of 50 g of jetanolamine/30 g of Hensyl alcohol/890 g of water, and a printing plate faithful to the toner image could be obtained.

Comparative Example 5 A printing original plate was obtained in the same manner as in Example 7 except that the aluminum plate used in Comparative Example 1 was used, and this was charged, exposed and developed in the same manner as in Example 1. An image of only 6.3 lines and 7 mm could be obtained with a light intensity of 2. The sharpness of the image was also poor, and was inferior to that obtained from the printing original plate of Example 7.

July 7, 1980 Proceeding Procedure Nei City Official (Spontaneous) July 1988 1411 Commissioner of the Patent Office Manabu Shiga 1, Indication of the case Patent layer 2 filed on July 7, 1980, Name of the invention, t. , rl B971゛/Original printing plate 3, Relationship with the amended person case Patent applicant 1-26-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo (127 > Konishiroku Photo Industry Co., Ltd. Representative Keio Ide 4. Agent ■105 6. Number of inventions increased by amendment None 7. Target of amendment [Claims column of specification” “Detailed explanation of invention column of specification” 8. Contents of amendment + 11 Description No. 1 ``2,'' from line 4 to line 15 of the page.
The scope of the patent claims will be corrected as shown in the attached sheet.

(2) On page 5, line 16 of the specification, the phrase ``(sharpness) etc. on plate making'' is corrected to ``(sharpness) etc. on plate making''.

(3) On page 10, line 16 of the specification, “Tendency Nirimi”
I am correcting it to say, ``It's true that there is a tendency towards 1.''

(4) Statement box 1] In line 6 of the car box, [0.2μ-1 less than or equal to 1, [Smaller than 0.2 μm]” is corrected.

(5) On page 13, line 16 of the specification, the phrase "photoconductive layer" is corrected to "photoconductive layer."

(6) On page 24, line 8 of the specification, "Faithful printing" says, "Faithful printed version," he corrects.

(7) On page 27, line 9 of the specification, It says "other than using" Correct it to "other than using."

2. Scope of Patent 1ri Request (1) After forming the ↓Letoner image area in electrophotography,
In a printing original plate having a photoconductive layer on a conductive support for creating a printing plate by removing the non-image area where the toner image area is not formed, the Center line average roughness (Ra) of the photoconductive layer side surface is 0.2
A printing original plate characterized by having a surface shape ranging from μm to 0.6 μm.

(21Jl) A printing original plate characterized in that the conductive support is an aluminum plate, the surface of which is electrolytically polished with nitric acid and anodized.

(Printed by Hiraito Rishinpo) February 21, 1985

Claims (2)

[Claims] (1) After forming a toner image using electrophotography, a photoconductor layer is placed on a conductive support to create a printing plate by removing the non-image area where the toner image is not formed. In the printing original plate, the support has a centerline average roughness (Ra) of 0.2 μm to 0.6 on the photoconductive layer side surface.
A printing original plate characterized by having a surface shape of μm. (2) The printing original plate according to claim 1, wherein the conductive support is an aluminum plate, the surface of which has been electrolytically polished with nitric acid and anodized.