JPH0746238B2 - Original plate for electrophotographic printing - Google Patents

Description

TECHNICAL FIELD The present invention relates to a printing original plate, and more particularly to an electrophotographic printing original plate having a photoconductor layer as a photosensitive layer.

(Prior Art) A large number of electrophotographic printing original plates of the type in which a photoconductor layer in a non-image area is removed after a toner image is formed are already known.

For example, Japanese Patent Publication No. 37-17162, No. 38-6961, No. 38-7758,
39-12703, 46-39405, JP-A-50-19509, 50
-19510, 52-2437, 54-19803, 56-66863
No. 56, No. 56-130766, No. 57-88457, No. 57-161863, No.
58-2854, 58-100862, 58-118658, 59-1210
No. 58, No. 59-121059, No. 59-121060, No. 59-121061
Issue 59-128559, Issue 59-128560, Issue 59-128561,
59-147355, 59-151157, 59-152456, 59-
152457, 59-168462, 59-168463, 59-16846
4, JP-A-54-134632, JP-A-55-105254, JP-A-55-153948
No. 55, No. 55-161250, No. 56-19063, No. 56-29250, No. 5
6-69644, 59-125751, 59-176756, 60-1775
No. 1, 60-17752, 60-17753, 60-17754, 6
0-17755, 60-17756, 60-17757, 60-17758
No. 60, No. 60-17759, No. 60-17760, No. 60-17761, No. 60
-17762, 61-67869, 61-67870 and the like.

These printing plates can be classified into two types depending on the type of photoconductive substance used in the photoconductive layer. That is, a printing original plate mainly using a photoconductive substance (solvent type photoconductive substance) having a solvent that completely dissolves, and a pigment-based photoconductive substance hardly soluble in the solvent are mainly used, depending on dispersion. A printing original plate having a photoconductor layer formed by preparing a photosensitive liquid for forming a photoconductor layer and coating it on a support.

Among the known printing original plates described above, JP-A-54-134632,
55-105254, 55-153948, 55-161250, 56-
19063, 56-29250, 56-69644, 56-146145
No. 59, No. 59-125751, No. 59-176756, No. 60-17751, No.
60-17752, 60-17753, 60-17754, 60-17755
No. 60, No. 60-17756, No. 60-17757, No. 60-17758, No. 60
-17759, 60-17760, 60-17761, 60-17762
Nos. 61-67869, 61-67870 and the like are printing masters using a photoconductive pigment as a photoconductive substance.

There are advantages and disadvantages when using a soluble photoconductive substance and when using a pigment-based photoconductive substance, but when using a pigment-based photoconductive substance, it must have the following characteristics. Can be done.

(1) High sensitivity (2) Single substance can have electrophotographic sensitivity up to 800 mm or longer wavelength range (3) Can remove photoconductor layer with water-based alkali (4) Clear Can be operated in the room (5) Low material cost (6) Good stability over time, etc.

However, conventionally, when a pigment-based photoconductive substance is used, a problem that must be solved is that after the toner image is formed by an electrophotographic method, the photoconductive layer in the non-image area is removed by an alkaline solution. When creating a printing plate, pigment residue is likely to occur in the non-image area, and in order to avoid that, the amount of the photoconductive pigment used must be reduced, and therefore the sensitivity must be reduced. It had a problem that it would not happen.

(Problems to be Solved by the Invention) In order to solve the above-mentioned problems, an object of the present invention is to use a pigment-based photoconductive substance, and while maintaining its characteristics, high sensitivity with no residual pigment in the non-image area. It is to provide an original plate for electrophotographic printing.

(Means for Solving the Problems) The above object of the present invention has a photoconductor layer using a pigment-based photoconductive substance as a photoconductive substance on a support, and after the toner image is formed, a non-image is formed. Part of the photoconductive layer is removed with a solution containing an alkaline substance and / or an alcohol as a main component to prepare a printing plate. It can be achieved by a printing original plate which is a support having a reflectance of 60% or more after roughening and desmutting.

The present invention will be described in detail below.

Examples of the photoconductive pigment that can be used in the present invention include JP-B Nos. 40-2780, 44-12671, 46-30035 and 44-
16474, 48-30513, 50-7434, JP 47-18543
No. 47, No. 47-18544, No. 47-30330, No. 47-37543, No. 49
-11136, 49-99142, 51-109841, 54-134632
55-11715, 55-105254, 55-153948, 55
55-161250, 56-1944, 56-2352, 56-9752
No. 56, No. 56-19063, No. 56-29250, No. 56-69644, No. 56
-80050, 59-125751, 59-176756, 60-17751
No. 60, No. 60-17752, No. 60-17753, No. 60-17754, No. 60
-17755, 60-17756, 60-17757, 60-17758
No. 60, No. 60-17759, No. 60-17760, No. 60-17761, No. 60
-17762, 60-35750, 61-67869, 61-67870 and the like, perylene pigments, quinacridone pigments, bisbenzimidazole pigments, aromatic polycondensed ring compounds, monoazo pigments, disazo pigments, trisazo There are pigments, metal or metal-free phthalocyanine pigments, and photoconductive pigments such as zinc oxide, and these can be used alone or in combination of two or more.

It is also possible to use a soluble photoconductive substance in combination, and examples of such substances include Japanese Patent Publication Nos. 37-17162 and 38-696.
1, 38-7758, 39-12703, 46-39405, JP-A-50-19509, 50-19510, 52-2437, 54-1980.
No. 3, No. 56-66863, No. 56-130766, No. 57-88457, No.
57-161863, 58-2854, 58-100862, 58-1186
No. 58, No. 59-121058, No. 59-121059, No. 59-121060
No. 59-121061, 59-128559, 59-128560,
59-128561, 59-147355, 59-151157, 59-
152456, 59-152457, 59-168462, 59-16846
3, No. 59-168464, etc., oxazole compounds, oxadiazole compounds, diphenylmethane compounds, triphenylmethane compounds, anthracene compounds, carbazole compounds, pyrene compounds and hydrazone compounds, etc. is there.

Further, in the present invention, a sensitizer may be used in combination, and examples of these sensitizers include xanthene dyes such as rose bengal, eosin S, fluorescein and phloxine; bromphenol blue, bromcresol purple and chlorophenol. Phenolsulfophthalein dyes such as red; Triphenylmethane dyes such as Alphazurin 2G, Pontacyl Brilliant Blue FCF and Acid Bio Red 6B; Diphenylmethane dyes such as auramine; Acridine yellows such as acridine yellow and acridine orange; Rhodamine dyes such as Rhodamine B, Rhodamine 6G, Rhodamine FB, Sulfoludamine B and Acid Eosin G; benzoic acid, phthalic acid, maleic acid,
Examples thereof include organic carboxylic acids such as fumaric acid, maleic anhydride, and phthalic anhydride, and anhydrides thereof.

Examples of the binder resin that can be used in the present invention include JP-B-37-17162, 38-6961, 38-7758 and 39-1.
2703, 46-39405, JP-A-50-19509, 50-19510
No. 52, No. 52-2437, No. 54-19803, No. 56-66863, No. 56-
130766, 57-88457, 57-161863, 58-2854
No. 58, No. 58-100862, No. 58-118658, No. 59-121058,
59-121059, 59-121060, 59-121061, 59-
128559, 59-128560, 59-128561, 59-14735
No. 5, 59-151157, 59-152456, 59-152457,
No. 59-168462, No. 59-168463, No. 59-168464, and the like, phthalic acid resins, maleic acid resins, acrylic acid resins, crotonic acid resins and JP-A Nos. 54-134632 and 55-1052.
Although it is an alkali-soluble resin such as a phenol resin described in No. 54, etc., a resin that is relatively sparingly soluble in alkali can be used in combination as long as it does not hinder the removal of the photoconductor layer by an alkaline aqueous solution. These resins include polystyrene, styrene-butadiene copolymers, hydrocarbon polymers such as polyisobutylene; polyvinyl chloride, chlorinated polyethylene,
Vinyl resins such as polyvinyl acetate, polyvinyl acetal, polyvinyl butyral, and polyvinyl ether; silicone resins; polyamide resins; polyurethane resins; urea resins; melamine resins; polycarbonates; modified or unmodified natural resins such as rosin and balsam.

The support that can be used in the present invention is a plate of which at least the surface is aluminum alone or an alloy containing aluminum as a main component as a material, and the layer structure may be a single layer or may have two or more layers. Includes a paper or film base sandwiched by aluminum layers.

The surface reflectance of the aluminum plate shows a relatively flat absorbance over the entire visible range, but in order to be more precise, in this specification, the reflectance at 600 mm is used unless otherwise specified. And

The surface of the above-mentioned support material is made into Japanese Patent Publication Nos. 40-164 and 39-20310.
No. 48, No. 48-9007, No. 46-27481, No. 48-28123, No. 51-
20922, 51-33444, 54-32424, 55-18638
No. 57, No. 57-16349, No. 55-13918, No. 56-19279, No. 56
-19278, 54-42282, 54-42283, 54-42284
No. 57-45309, No. 55-19191, JP-A-53-123204
No. 53, No. 123205, No. 53-134501, No. 53-145701,
After graining by a mechanical and / or electrochemical method described in JP-A-53-70053, etc., JP-B-39-20310 and JP-B-48-281
No. 23, No. 51-33444, No. 54-42284, No. 60-6799, JP-A No. 53-12739, No. 56-15396, No. 56-70991, No. 56-5
1388, 56-15396, 57-170797, etc. are desmutted so that the reflectance at 600 mm is 60% or more, and further Japanese Patent Publication Nos. 39-20310 and 40- No. 164, the same
46-27481, 48-28123, 51-33444, 54-32424
No. 60-6799, JP-A-52-72338, 53-77702,
53-67507, 53-134501, 53-134501, 54-1
21801, 54-123302, 54-120003, 54-128453
No. 55, No. 55-137993, No. 55-140592, No. 55-158299,
No. 57-89498, No. 57-203593 and the like to perform an oxidation treatment by a method described to form an oxide film, and further, if necessary, JP-B-48-9007, JP-A-51-34007, 51- No. 66007, No. 53-
A support suitable for the present invention can be prepared by performing a pore-sealing treatment by the method described in JP-A No. 58445.

Since this oxide film is usually about 0.5 to 3.0 μm and almost colorless, it is possible to measure the reflectance at 600 mm above the oxide film.

In addition to the reflectance, as a physical property value desirable as a support for the printing plate precursor of the present invention, the center average roughness (Ra) is in the range of 0.2 to 1.0 μm, and the plate thickness is usually in the range of 0.1 to 0.5 mm. .

Here, the center line average roughness (Ra) is the German standard DIN4768.
Is the arithmetic mean of the absolute values of the distances from the center line in the roughness profile to each point on the profile, the horizontal center line is the X axis, and the vertical direction is the Y axis. When the points on the roughness profile are represented by (x, y), the Ra value obtained by the following formula for the measurement length l _m is represented by the unit of micron.

(formula) This value can be measured by, for example, a belt meter S5P manufactured by Pelten.

Next, in order to prepare the printing plate precursor of the present invention, the photoconductive substance, the binder resin, and the sensitizer described above are dissolved in a solvent, and the solution filtered if necessary is subjected to the above-mentioned surface-treated support. It is applied to the body by a coating method such as a roll coater or a wire bar whirler so that the film thickness after drying is about 2 to 10 μm, and then dried.

As the coating solvent usable in the present invention, diethylamine,
Dimethylformamide, tetrahydrofuran, cyclohexanone, phenol, cresol, chloroform, dichloroethane, chlorobenzene, dichlorobenzene, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol It is a single solvent or a mixture of two or more kinds of monoethyl ether acetate, dioxane and the like.

Next, prior to frying the examples of the present invention and comparative examples, a method of preparing a support and a dispersion used in the examples and comparative examples of the present invention will be described.

(Example) Preparation of "Support-A" Two aluminum plates (Japanese Industrial Standard 1050) having a thickness of 0.3 mm were prepared.
% Sodium hydroxide aqueous solution at 60 ° C. for 30 seconds for degreasing treatment, then 5% sulfuric acid aqueous solution for 10 seconds for neutralization and washing with water. This aluminum plate was placed in a 0.3 mol / l nitric acid solution,
The surface was roughened by electrolytic etching at 0 ° C. and an alternating current density of 40 A / dm ² for 1 minute, and then immersed in a 10% NaOH aqueous solution at 30 ° C. for 40 seconds to perform desmutting treatment. Further, after anodizing treatment in a 15% aqueous solution of sulfuric acid at a temperature of 20 ° C. and a current density of 1 A / dm ² for 10 minutes, it was washed with water and dried to prepare a support-A. After finishing all the treatments, the reflectance was measured from the above, and it was 64.3%.

Preparation of "support-a" In preparation of "support-A", "support-A" was prepared except that desmutting after roughening treatment was carried out by immersion in 10% NaOH aqueous solution at 30 ° C for 5 seconds. "Support-a" was prepared in the same manner as in the preparation of ". The reflectance of this product was 52.6%.

Preparation of "Support-B" A 0.15 mm aluminum plate having a purity of 99.5% was degreased with trichlene, washed with water, and then with a 2% HCl aqueous solution in an electrolytic bath having a bath temperature of 30 ° C and an alternating current density of 30 A / dm. ^The surface was roughened by electrolytically etching at ² for 2 minutes. Then the liquid temperature
A desmutting treatment was performed by immersing in a 30% by weight H ₂ SO ₄ aqueous solution at 60 ° C. for 1 minute. Neutralize with 5% Na ₂ CO ₃ solution, wash with water 15
% Sulfuric acid solution was used as an electrolytic bath for direct current anodic oxidation treatment for 2 minutes and then washed with water to prepare a support-B. The reflectance was 62.5%.

Preparation of "Support-b""Support-B" was prepared except that the desmutting treatment after the roughening treatment was carried out by immersing in a 30% sulfuric acid aqueous solution at 50 ° C for 10 seconds. "Support-b" was prepared in the same manner as in the preparation of "-B". The reflectance of this product is 47.0%
Met.

Preparation of "Support-C" After degreasing an aluminum plate (JIS1050) with trichlene, ball polishing was carried out for 15 minutes with alundum having an abrasive grain size of 800 mesh, roughening treatment was performed, and after washing with water, 5% by weight
Was immersed in an aqueous solution of sodium hydroxide for 2 minutes at 50 ° C., desmutted, neutralized with dilute hydrochloric acid, and washed with water. Further
Current density 20 A / dm ² , current flow time 5 in 15 wt% sulfuric acid solution
Anodizing treatment was carried out at a solution temperature of 40 ° C. for 0 seconds to form an oxide film, thereby preparing a support-C. The reflectance of this thing
It was 65.1%.

Preparation of "Support-c" In the preparation of Support-C, the desmut treatment after the roughening treatment was performed by immersing the desmut treatment in a 2% by weight sodium hydroxide aqueous solution at 30 ° C for 10 seconds. A support-c was prepared in the same manner as the preparation of the support-C. The reflectance of this product was 46.5%.

Preparation of "Support-D" A 0.15 mm thick aluminum plate (purity 99.5%) was added to 0.1% NaO.
It was immersed in the H 2 aqueous solution for 10 seconds, degreased, and then washed with water.
A rotating nylon brush and a 400-mesh suspension of Pamistone monohydrate as an abrasive were used to perform a graining treatment, followed by washing with water. Then, it was immersed in a 10% aqueous sodium hydroxide solution at a liquid temperature of 40 ° C. for 50 seconds, desmutted, neutralized with dilute sulfuric acid and washed with water. Next, using a 10% oxalic acid aqueous solution as an electrolytic bath, a current density of 3.0 A / dm ² was applied to carry out anodizing treatment by direct current electrolysis for 2 minutes, washing with water and drying to prepare a support-D. The reflectance of this product was 66.6%.

Preparation of "Support-d" In the preparation of Support-D, all were supported except that desmutting after graining was performed by immersing in a 5% aqueous sodium hydroxide solution at a liquid temperature of 25 ° C for 15 seconds. Support-d was prepared in the same manner as when preparing body-D. The reflectance of this object is 5
It was 3.4%.

Preparation of "Support-E" An aluminum plate having a thickness of 0.15 mm (purity: 99.5%) was degreased with trichlene and then grained by liquid honing using a mixed flow of 400 mesh pumicetone and water. The following treatment was carried out in the same manner as in the production of the support-D to produce a support-E. This product has a reflectance of 66.4
%Met.

Preparation of "Support-e" An aluminum plate having a thickness of 0.15 mm (purity: 99.5%) was degreased with trichlene and then grained by liquid honing using a mixed flow of 400 mesh pumicetone and water. Next, after washing with water, it was immersed in a 5% aqueous sodium hydroxide solution at a liquid temperature of 25 ° C. for 10 seconds for desmutting treatment, neutralized with dilute hydrochloric acid, and washed with water. Then, using 20% sulfuric acid as an electrolytic bath, direct current anodic oxidation treatment was performed at a current density of 2.0 A / dm ² , followed by washing with water and drying to prepare a support-e. The reflectance of this product is 51.4%
Met.

Preparation of [Dispersion A-1] A dispersion for forming a photoconductor layer was prepared according to the following formulation.
First, after dissolving 9 parts by weight of a binder resin having the following structural formula in 40 parts by weight of ethylene glycol monoethyl ether,
Filtered.

1 part by weight of pigment β-type copper phthalocyanine (Chiba Geigy Co., Ltd., Chromophthal Blue 4GN) was added to this solution, followed by dispersion with a ball mill for 24 hours to prepare a dispersion liquid.

Preparation of [Dispersion A-2] Preparation of Dispersion A-1 except that 8.5 parts by weight of the resin having the same structural formula and 1.5 parts by weight of β-type copper phthalocyanine were used in the preparation of Dispersion A-1. Dispersion A-2 was prepared in the same manner as in.

In the same manner, a total of 7 kinds of dispersion liquids having different photoconductive pigment / resin ratios shown in the following table were prepared.

Preparation of [Dispersion B-1] 9 parts by weight of a resin having the following constitution was dissolved in 40 parts by weight of ethylene glycol monomethyl ether, and then filtered with filter paper.

Add ε-type copper phthalocyanine (Toyo Ink Co., Li
ophoton-EK) 30 parts with glass beads after adding 1 part by weight
Dispersion was performed for a minute to prepare a dispersion B-1.

In the same manner, a total of 7 kinds of dispersion liquids having different photoconductive pigment / resin ratios shown in the following table were prepared.

Preparation of [Dispersion C-1] 9 parts by weight of a resin having the following structural formula was dissolved in 40 parts by weight of ethylene glycol monomethyl ether and then filtered.

Ε-type copper phthalocyanine (Li-made by Toyo Ink Co., Ltd.
glass beads were dispersed for 30 minutes to obtain a dispersion C-1.

In the same manner, a total of 7 kinds of dispersion liquids having different photoconductive pigment / resin ratios shown in the following table were prepared.

The support (A to E, a to e) prepared as described above and the dispersion for forming a photoconductor layer (A-1 to 7, B-1 to 7, C-1 to 7) were combined and the results are shown in Table 1. The printing original plates (I-1 to I-42) shown in Table 2 and the comparative printing original plates (II-1 to II-42) shown in Table 2 which are outside the present invention are prepared. did.

Hereinafter, examples of preparation of these printing original plates, measurement of electrophotographic characteristics, and sensitivity and dissolution of non-image areas will be described.

(Example of preparation of printing original plate) A dispersion liquid is applied and dried so that the film thickness after drying is 5 μm by applying a wire bar on the surface that has been subjected to a treatment such as graining. At this time, the film thickness is adjusted by selecting the wire bar number.

(Plate-making) Using an electrophotographic plate-making machine that has a camera-exposure type exposure unit (light source is a halogen lamp) and a developing unit that develops with liquid toner, the amount of charge according to the electrophotographic sensitivity of each printing plate. Also, the exposure amount was changed, and the toner amount was made uniform to about 6 mg / dm ² in the solid portion of all the printing original plates to form a toner image. The non-image area was removed using an eluate containing alkali or alcohol as a main component. The results of the residual pigment in the non-image area and the electrophotographic sensitivity at this time were shown in Table 1 (invention) and Table 2. (Comparative example).

The liquid toner used in this experiment has the following composition and is resistant to the eluate.

(Liquid toner) Carbon black 10 parts by weight (Mitsubishi Chemical Co., Ltd. MA-100) Ethylene vinyl acetate copolymer 1 part by weight (Nippon Unicar DQ, DJ-7197) Stearyl methacrylate: Methacrylic acid = 8: 2 (mol ratio) ) Copolymer 9 parts by weight Average molecular weight about 100,000 Polyethylene 15 parts by weight (Sanyo Chemical Co., Ltd. Sunwax 171P) Isopar G 200 parts by weight (Exxon) mixed solution is dispersed with a sand glider to prepare Isopar G Diluted to a solid content of 1.0% by weight.

Note 1) Elution of non-image area The printing original plates of each of the Examples and Comparative Examples on which the toner image was created were immersed in the eluent for a different time, rubbed lightly with a sponge while sprinkling with water, and dried to dry the non-image area. The degree of residual pigment was observed. The dipping time in the eluate was 60 seconds for each plate. With further immersion, the toner image is touched by the eluate and a defect occurs in the image. Regarding the signal in the column of final elution properties, ◯: Elution was made to the state where there is almost no pigment residue in the non-image area. Δ: Some pigment residue is observed, but there is no problem in practical use. Incompatible with printing plate due to residual pigment Almost undissolved or with a large amount of pigment remaining.In the column of elution liquid immersion time, if the final elution property is ○, the minimum immersion time required to create a condition of ○ is displayed. For the products, the state of the pigment remaining in the non-image area after 60 seconds of immersion, which is the longest immersion time in which deterioration of the toner image does not begin, is indicated in the final elution column.

The eluents used in this experiment are as follows.

(Printing tin original plates of Examples I-12 to I-18 and Comparative Examples II-12 to II-18) Caustic soda 1.0% by weight Isopropyl alcohol 25% by weight Water 74% by weight Melting temperature 30 ° C (other printing plates) Konishi Rokusha Kogyo Co., Ltd. Positive developer SDP-1 (alkaline solution containing sodium metasilicate as the main component) 7-fold dilution, melting temperature 30
℃ Note 2) Sensitivity Measured using an Electrostatic Paper Analyser SP-428 manufactured by Kawaguchi Electric Co., Ltd., and the optical energy required to attenuate the plate surface saturation potential to half the saturation potential is lux.sec.
(Expressed in units of illuminance (lux) x irradiation time (sec). The smaller the value, the higher the sensitivity.

Based on the above experimental data, it was shown that the printing plate precursor of the present invention is superior in sensitivity and / or non-image area elution property to the printing plate precursor of Comparative Example.

(Effects of the Invention) According to the present invention, it is possible to provide a high-sensitivity electrophotographic printing original plate having no pigment residue in the non-image area.

Claims (1)

[Claims] 1. A photoconductive layer using a pigment-based photoconductive material as a photoconductive material on a support, and after forming a toner image, the photoconductive layer in the non-image area is made of an alkaline material and / or Alternatively, after removing with a solution containing alcohol as a main component to prepare a printing plate, the support is roughened on the surface of a plate containing aluminum as a main component, and is desmutted. An original plate for electrophotographic printing, which is a support having a reflectance of 60% or more.