JPS58122897A - Original plate for planography - Google Patents

Abstract

PURPOSE:To enhance etching property and prevent ground staining, by a method wherein a water-insoluble resin layer having an acid number larger than that of a binder in a photoconductive layer by 50 and having free carboxyl groups is provided between a hydrophilic conductive base and the photo-conductive layer. CONSTITUTION:The photo-conductive layer having an acid number of at least about 80 and containing an organic photoconductive compound such as acrylic acid or methacrylic acid as a binder is provided on the hydrophilic conductive base, and a toner image is produced on the photoconductive layer by electrophotography. The layer of a water-insoluble resin having an acid number larger than that of the binder in the photoconductive layer by at least 50, preferably by at least 100 is provided between the base and the photo-conductive layer. An example of the resin is a conpolymer of a polymerizable component having a 1-5C alkyl group as an ester residue of an acrylic acid ester or a methacrylic acid ester, or stylene with a polymerizable carboxylic acid monomer.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a printing plate in which a toner image is formed by electrophotography using an organic photoconductive compound, and non-image areas other than the toner image forming area are etched with an aqueous alkaline solution. be.

Many printing plates using organic photoconductive compounds are already known, for example, Japanese Patent Publication Nos. 37-17162 and 3B-6.
No. 961, No. 41-2426, No. 46-39405,
JP 50-19509, JP 50-19510, JP 54-145538, JP 54-89801, JP 54
-134632, 54-19803, 55-1
No. 05254 etc. are mentioned. The photosensitive layer binders used in these printing plates include styrene maleic anhydride copolymer, maleic ester resin, and vinyl acetate.
Examples include alkali-soluble resins such as crotonic acid copolymer, vinyl acetate-maleic anhydride copolymer, and phenol resin.

In general, the photosensitive layer used in such printing plates has good sensitivity and contrast, excellent adhesion to toner and substrate, and easy removal of non-image areas with etching solution, and is particularly suitable for wet development. In this case, it is possible to perform etching treatment to obtain high resolution, and it has good receptivity to printing ink (even if the toner peels off during printing, there should be no problem with printing) and printing durability. is required.

The photosensitive layer binder that satisfies the above requirements is a resin with a high acid value, such as a resin having a carboxyl group soluble in an alkaline etching solution or an anhydride thereof, such as a resin with an acid value of about 80 or more, or a phenol resin. Preferably, a resin having no valence is used.

However, lithographic printing plates in which a layer containing an organic photoconductive compound with an alkali-soluble resin as a binder is provided on a conductive substrate have good resistivity in the toner image area and high resolution even in wet development. However, in order to obtain a lithographic printing plate with high printing durability of several tens of squares using a metallic substrate such as an aluminum plate, it is necessary to
In general, printing durability cannot be said to be sufficient, and it is desired to develop a lithographic printing plate with improved cb and printing durability. Further, as with general printing plates, it is naturally required that the printing plate be free from scumming.

Although scumming depends on the etching properties of the photosensitive layer, it largely depends on the hydrophilicity of the surface of the substrate. In order to avoid the need for special desensitization treatment before printing starts, it is desirable to anodize or grain the aluminum plate surface and then apply hydrophilic treatment with an alkali metal silicate or phosphate. It is. However, it has also been found that lithographic printing plates in which a layer containing an organic photoconductive compound with a resin with a high acid value as a binder is provided on a hydrophilic base material are inferior, especially in terms of printing durability. An object of the invention is to provide a lithographic printing original plate which has good electrophotographic properties as a printing plate, good etching properties with an alkaline etching solution, is free from scumming, and has high printing durability.

Another object of the present invention is to provide an original plate for electrophotographic lithography which has high resolution by liquid development and high printing durability.

The above-mentioned object of the present invention is to provide a photoconductive layer containing an organic photoconductive compound and an alkali-soluble resin as a binder on a hydrophilic conductive substrate, and toner particles formed on the photoconductive layer by electrophotography. In a lithographic printing original plate for forming a printing plate by forming an image and fixing the toner image, removing a non-image area having no toner with an alkaline etching liquid, the base material and the photoconductive A lithographic printing original plate characterized in that a layer of a water-insoluble resin having an acid value greater than that of the binder used in the photoconductive layer by about 50 or more and having a free carboxyl group is provided between the photoconductive layer and the photoconductive layer. found that it can be achieved.

Examples of the organic photoconductive compound used in the printing plate of the present invention include the following compounds.

(a) Aromatic tertiary amine compounds nitriphenylamine, diphenylbenzylamine, cy(β-naphther)
Hensylamine, diphenylcyclohexylamine, etc.

(b) Aromatic tertiary diamino compound: N, N,
N', N'-f'trahensyl-p-phenylenediamine, N, N, N: N'-tetrabenzylbenzicine, l.

1'-bis-(4-N,N-dibenzylaminophenyl)-ethane, 2,2-bis-(4-N.

N,-dibenzylaminophenyl)butane, bis-(4
-N,N-di(P-chlorobenzylaminophenyl)
)-methane, 3,3-diphenylallyridine-4,47
-bis(N,N-diethyl-m-toluidine), 4
．． 4″-bis(j-p-)lylamino)-1,1,1
-triphenylethane, etc.

(c) Aromatic tertiary triamino compound: 4,4?4'
-tris(diethylaminophenyl)methane, 4-dimethylamino, 4,4-bis(diethylamino)-2,2
”-dimethyl-triphenylmethane, etc.

(,i) Main condensation product: condensation product of aldehyde and aromatic amine, reaction product of tertiary aromatic amine and aromatic halide, poly-p-7 enylene-1.3.4-oxadiazole, Reactants of formaldehyde and fused polycyclic compounds, etc.

, (θ) Metal-containing compounds: 2-mercagtopenzothiazole zinc salt, 2-mercagtopenzoxazole lead salt, 2-mercapto-6-medoxybenzimidazole-lead salt, S-hydroxy- quinoline-aluminum salt,
2-hydroxy-4-methyl-azobenzene-copper salt, (
f) Polyvinylcarbazole compounds: polyvinylcarbazole, halogen-substituted polyvinylcarbazole, copolymers of vinylcarbazole and styrene, copolymers of vinylanthracene-vinylcarbazole, etc.

Heterocyclic compounds: 1.3.5-)! jPhenylupyrazoline, 1-phenyl-3-(p-dimethylaminostyryl)-5-(p-dimethylaminophenyl)-
Pyrazoline, 1.5-diphenyl-3-styryl-pyrazoline, 1.3-diphenyl-5-styryl-pyrazoline, 1.3-diphenyl-5-(p-dimethylaminophenyl)-pyrazoline, 3-(4'- dimethylaminophenyl)-5,6-di(4-methoxyphenyl) -
1,2,4-) riazine, 3-(4'-dimethylaminophenyl)-5,6-diviridyl-1,2,4-) riazine, 2-phenyl-4-(4'-dimethylaminophenyl)-quinazoline , 6-hydroxy-2,3-di(P
-methoxyphenyl)benzofuran, 2,5-bis-[
4'-ethylamino-phenyl-ω:] -1,3゜4
-Oxadiazole etc.

Further, the organic photoconductive compounds used in the present invention include phthalocyanine pigments, quinacridone pigments, indigo pigments, cyanine pigments, perylene pigments, bisbenzimidazole pigments,
Good printing plates can also be obtained using pigments such as quinone pigments, azo pigments, and indigo pigments.

Examples of resins having an acid value of about 80 or more that are preferably used in the present invention as binders for organic photoconductive compounds include acrylic acid,
Polymerizability of methacrylic acid, crotonic acid, etc. - How many years have polymerizable components with vinyl or acrylic groups such as saturated carboxylic acid monomers, polymerizable polyunsaturated carboxylic acids such as maleic acid, fumaric acid, and maleic anhydride been used? Copolymers with other polymerizable components are included. Other polymerizable components mentioned above include styrene, acrylic esters, methacrylic esters, vinyl acetate, and the like. The number of these other polymerizable components may be one, or two or more may be used to form a ternary or higher copolymer.

Ester residues of acrylic esters and methacrylic esters include, for example, methyl, ethyl, n-propyl, inglovir, n-7"f-isobutyl, θθC-
Butyl, t-butyl, n-amyl, 3-pentyl, 2-
Mef-1-butyl, 3-methyl-1-butyl, n-hexyl, 2-methyl-1-pentyl, 2-ethyl-1-
Butyl, 5ee-amyl, t-amyl, 4-methyl-2
-pentyl, n-heptyl, 2-heptyl, n-octyl, 2-ethyl-1-hexyl, 2-octyl, n-nonyl, n-decyl, 5-ethyl-2-nonyl, n-dodecyl, n-tetradecyl , n-hexadecyl, cyclohexyl, 2-methylcyclohexyl, 3-methylcyclohexyl, 4-t-amylcyclohexyl, phenyl,
O-)ruyl, P-t-7'tylphenyl, 2-10 luether, 3-10 luprovir, pentachlorphenyl,
2-hydroxyethyl, 3-hydroxybutyl, 2-methoxyethyl, 2-ethoxyethyl, 2-butoxyethyl, glycidyl, 3,4-epoxy-6-methylcyclohexylmethyl, tetrahydrofurfuryl, trifluoropropyl, 11.5 -) +) H)-loba-fluoropentyl, 1,1.3-1J hydroperfluoroglovir, and the like.

Polymerizable carboxylic acids have important effects on solubility in alkaline etching solutions, electrophotographic properties, toner adhesion, printing ink receptivity, etc., and the type and degree of polymerization of other polymerizable components. Although there are changes due to
It is desirable to appropriately determine the amount in the range of 5 molti to 70 molti. Furthermore, phenolic resins can also be used. The average molecular weight of these binders is from 1,000 to
It can be used in the range of 500,000, but the film strength of the formed film and the etching speed are from the top to s, o o o ~ 1
A range of 50,000 is preferred.

Representative examples of the binder used in the photoconductive layer of the present invention are listed below, but the binder is not limited thereto. 0 indicates the molar ratio 0 Butyl acrylate-acrylic acid (70:30)
Butyl methacrylate-methacrylic acid (80:20
) 2-ethylhexyl acrylate-methacrylate 4 (7
0:30) Ethyl acrylate-methacrylic acid (
80:20) Methyl methacrylate-butyl acrylate-acrylic acid (50
: 20 : 30) Butyl acrylate-itaconic acid (85:15) Methyl methacrylate-methyl acrylate-methacrylic acid
(40:30:30) 2-ethylhexyl acrylate-methyl methacrylate-acrylic acid
(10:50:40) Lauryl methacrylate-acrylic acid (60:40) Methyl methacrylate-Lauryl methacrylate-Crotonic acid
(40:20:30) n-butyl methacrylate-methacrylic acid (75:25)s
ec-butyl acrylate-hydroxyethyl methacrylate-acrylic acid (60:1
0:30) 2-ethoxyethyl methacrylate-n-
Butyl acrylate-methacrylic acid (
50:30:20) styrene-maleic anhydride (50:
50) Partial octyl ester of styrene-maleic anhydride (50:50, degree of esterification 40 mol%) These synthetic polymer compounds can be subjected to bulk polymerization, solution polymerization, and suspension polymerization using peroxides and azo compounds as polymerization initiators. It can be synthesized very easily, and the synthesis method is generally well known.

The ratio of the photoconductive compound to the binder is 0.01 to 50 parts by weight of the binder per 1 part by weight of the photoconductive compound, preferably 0.2 to 10 parts by weight, although it varies depending on the binder and photoconductive compound used. is appropriate.

Those that can be used as solvents include all organic solvents that are capable of dissolving the binder and dissolving or dispersing the photoconductive compound.

For example, alcohols such as methanol, ethanol, propatool, phthanol, and hexyl alcohol, cellosolves such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve, aromatics such as benzene, toluene, and xylene, and cyclic ethers such as dioxane and tetrahydrofuran. esters such as ethyl acetate, butyl acetate, and amyl acetate, ketones such as acetone, methyl isobutyl ketone, and methyl ethyl ketone, dimethyl formamide, dimethyl sulfoxide, and halogenated hydrocarbons.

To produce a printing original plate, the photoconductive compound and binder are dissolved in a solvent. If the photoconductive compound is not dissolved, a dispersion liquid is prepared using a colloid mill, a holing generator, an ultrasonic dispersion machine, etc. ), and if necessary, add a sensitizing dye, etc., and coat and dry to a thickness of about 1 to 10 μm.

The resin for the intermediate layer provided between the photoconductive layer and the base material can be selected from the binder resins described above. However, resins that do not have free carboxyl groups, such as acid anhydrides, are excluded, and the acid value is about 50 or more, preferably 100 or more than the acid value of the binder used in the photoconductive layer.
A water-insoluble resin having a higher acid value is used.

In particular, the acid value of the binder resin of the photoconductive layer is 80 to 25.
The intermediate layer provided between the photoconductive layer and the base material should have an acid value of 200 or more, and the resin used for the photoconductive layer (if several types of resins with an acid value of 80 to 250 are used) It is preferable to use a water-insoluble resin with an acid value at least 100 higher than the resin with the highest acid value. A resin with a high acid value can be easily obtained by increasing the proportion of polymerizable carboxylic acid, and by increasing the proportion of polymerizable carboxylic acid in the resin exemplified as the pinter of the photoconductive layer, It may be added herein as a specific example. Examples of particularly preferable resins include ester residues of acrylic esters and methacrylic esters of 01 to . A polymerizable component having an alkyl group or a copolymer of styrene and a polymerizable carboxylic acid monomer,
Examples include copolymers such as terpolymers. The thickness of the resin layer is preferably about 0.5 seconds or less. If the thickness is too large, the electrophotographic properties will be deteriorated, and in particular, the residual potential will become high, causing fogging and poor etching, so care should be taken.

To give an example of the present invention, when a binder with an acid value of 150 is used in the photoconductive layer, a water-insoluble resin having the same components as the binder of the photoconductive layer but with an acid value of 300 is used in the intermediate layer. , a lithographic printing plate material is obtained in which the above-mentioned chain objectives of the present invention are achieved. The above-mentioned photoconductive layer may be applied directly, a photoconductive layer using a resin having an acid value of 300 may be applied directly to a base material, or the photoconductive layer and intermediate layer resin may be used in reverse.

However, it is not possible to obtain a lithographic printing plate material having the above-mentioned effects of the present invention.

The base material used in the present invention can be used without any restriction as long as it has conductivity and hydrophilicity. Examples include metal plates such as aluminum plates, zinc plates, and copper plates, aluminum foil, and aluminum vapor-deposited films. However, photoconductive compounds and binders are removed by etching treatment, and non-image areas have hydrophilic properties. Therefore, it is necessary to previously perform a hydrophilic treatment on a base material having a hydrophobic surface. A metal plate, particularly an aluminum plate, is most suitable, but it is preferable that the surface has been subjected to a hydrophilic treatment such as a grain treatment, an alkali treatment, an acid treatment, or anodization. In particular, the advantages of the present invention are significantly exhibited in substrates that have been subjected to hydrophilic treatment using phosphoric acid or its salts, or alkali metal silicates.

The toner used for image formation may be either a so-called dry toner or a wet toner, but the advantages of the present invention are particularly exhibited when using a liquid toner with excellent resolution using a liquid development method. It is obtained by forming a toner image on a printing original plate using an electrophotographic method, and then etching the non-image area with an aqueous solution of alkali or alcohol. Examples of the alkali include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium phosphate, potassium phosphate, and ammonia.

Examples of the alcohol include lower fluoroaromatic alcohols such as methanol, ethanol, clopanol, butanol, benzyl alcohol, and phenethyl alcohol, as well as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, and cellosolves. Etching treatment can be performed using an alkaline aqueous solution or alcohol alone, but the etching speed
From the viewpoint of safety and health, it is preferable to use amino alcohols such as monoethanolamine, jetanolamine, and triethanolamine, and from the viewpoint of resolution and image reproducibility, a combination of amino alcohols and alcohols is most preferable.

A surfactant can also be added if necessary. The present invention will be specifically explained below using examples.

Example 1 As a binder, methyl methacrylate-butyl acrylate-acrylic acid copolymer (50:20:3
0) (acid value 178) xylene 45019
.

Dissolved in a mixed solvent of 300.9 g of butanol and 50 g of tetrahydrafuran, 709 g of 1.3.5-triphenylpyrazoline as an organic photoconductive compound was dissolved in this solution, and 1% of Rhodamine B as a sensitizing dye. DMF solution 501
9 was added and the total amount was adjusted to 1.000 g with xylene.

Anodic oxidation treatment and silicate treatment) It was coated and dried to a solid content of 417 m' on a 300μ aluminum plate treated with IJum (Comparison A). The binder used in the photoconductive layer was a styrene-maleic anhydride copolymer (50:
50) and butyl methacrylate-methacrylic acid copolymer (30 near 0) (acid value 355) were coated and dried on the aluminum plate to give 031B, and then the photoconductive layer was provided in the same manner. .Sequentially (
Comparison B), (Comparison C) and (Invention A) original printing plates. After applying a corona discharge of 16 KV to negatively charge them in a dark place, a positive image was exposed to white light. Immediately, development was performed using Ricoh's MRP toner as a liquid toner, and heat fixation was performed using fusθr.

Next, these were immersed in the following etching treatment solution, and while being rubbed lightly with a sponge, the time until the aluminum surface of the non-image area other than the toner image was etched and exposed was measured.

Furthermore, after washing the printing plate obtained in this way with water, using compound-containing Tack 15 ink, Ryobi K.
A printing durability test was conducted using a P2700 printing machine.

[Etching treatment liquid]

The results are shown in the table below. It should be noted that there was no difference in the electrophotographic properties of any of the printing plates, which were satisfactory and had no background stains.

Example 2 The binder for the photoconductive layer was a 2-ethylhexyl acrylate-methyl methacrylate-acrylic acid copolymer (10
:50:40), [acid value 215] styrene-maleic anhydride partial octyl ester (50:50 degree of esterification 4o%), ethyl acrylate-methacrylic acid copolymer (80:20) (acid value 110) Example 1 except that
Twelve types of printing original plates were prepared and tested in the same manner as above.

It was confirmed that exactly the same results were obtained regarding printing durability.Example 3 n-Butyl methacrylate and methacrylic acid were dissolved in a mixed solvent of 500I and 200 g of butanol to prepare a binder solution. 4. As an organic photoconductive compound in this solution.
4"-bis(diethylamino)-2,2"'-dimethyl-triphenylmethane at 7Of? After dissolving, 80 g of a 1% DMF solution of ethyl violet was added as a sensitizing dye, and the total amount was adjusted to 1000 g with xylene. Aluminum plate acrylic acid copolymer (30:70) used in Example 1
, [acid value 355] styrene-methacrylic acid copolymer (
50:50), (Acid value 280) Ethyl methacrylate-itaconic acid copolymer (85:15) (Acid value 240
] on an aluminum plate.
The photoconductive layer was applied thereon in the same manner as described above (Inventions BD). When a printing test was carried out in the same manner as in Example 1, it was confirmed that the comparison had a printing durability of 20 ρ00 sheets or less, but it was confirmed that both inventions B and D had a printing durability of 50 ρ00 sheets or more.

Claims (1)

[Claims] (1) A photoconductive layer containing an organic photoconductive compound No. 3 and an alkali-soluble resin as a binder is provided on a hydrophilic conductive base material, and an electrophotographic method is applied on the photoconductive layer. In a lithographic printing original plate for forming a printing plate by forming a toner image and fixing the toner image, removing the non-image area having no toner with an alkaline etching liquid, the base material and the photoconductive A lithographic printing original plate, characterized in that a water-insoluble resin layer having an acid value approximately 50 or more higher than the binder of the photoconductive layer and having a free carboxyl group is provided between the photoconductive layer and the photoconductive layer.