JP3115083B2 - Electrophotographic lithographic printing plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing plate having a photoconductive layer provided on a conductive support, wherein a toner image is formed by an electrophotographic method, and then a non-image portion light other than the toner image portion is formed. The present invention relates to an electrophotographic lithographic printing plate having a printing plate obtained by removing a conductive layer, and more particularly to an electrophotographic lithographic printing plate which is excellent in resolution of a plate-making image, has no background stain, and has high printing durability.

[0002]

2. Description of the Related Art In general, a lithographic printing plate is known as a PS plate in which a diazo resin or the like is applied as a photosensitive layer on an aluminum plate.
It exposes the surface photosensitive layer of the printing plate precursor through close contact with the film, thereby forming cured and uncured portions corresponding to the image and non-image portions of the document. Have been. However, PS plates have low sensitivity, and electrophotographic lithographic printing plates and silver halide lithographic printing plates have been widely used for plate making by projection exposure or laser exposure.

Heretofore, as a printing plate utilizing the principle of electrophotography, for example, JP-B-47-47610 and JP-B-47-47610.
No.-40002, No.48-18325, No.51-15
No. 766, No. 51-25761, etc., an offset printing master using a zinc oxide / resin dispersion system as a photosensitive layer is known. In such an offset printing master, an electrophotographic method is used. To form a toner image,
Next, the non-image portion other than the toner image portion is desensitized to be used as a printing plate. However,
In these printing plates, the printing strength is poor because the strength of the photosensitive layer is low.
It is limited to about 10,000 sheets, which is unsuitable for printing many more sheets. Further, in order to perform the above desensitization treatment, it is necessary to use an acidic solution such as a hexacyano iron salt, which has problems in pollution control and occupational health.

Further, Japanese Patent Publication Nos. 37-17162 and 38
-7758 and 46-39405, JP-A-52-2
No. 437, No. 57-161863, No. 58-2854
JP-A-58-28760 and JP-A-58-118658 disclose a printing plate having an organic photoconductor held in a resin, for example, sensitized with an oxazole or oxadiazole-based photoconductor. An electrophotographic lithographic printing plate is disclosed in which a photoconductive layer in which a dye is bound with a resin such as a styrene / maleic anhydride copolymer is provided on an aluminum plate which is grained. Also, Japanese Patent Application Laid-Open Nos. 54-134632 and 55-16
Nos. 5254, 59-12452, 59-4955
No. 5 discloses an electrophotographic lithographic printing plate in which a photoconductive layer in which an organic photoconductive pigment such as copper phthalocyanine is bonded to a resin such as a phenol resin is provided on a grained aluminum plate. Have been.

In these general plate making methods, a toner image is formed by an electrophotographic image forming method, and then the toner image is formed.
By treating the non-image part other than the image part with a solution containing an alkali and / or an alcohol, the non-image part photoconductive layer is dissolved (so-called elution) from the plate, and more generally an excess eluate Neutral or higher pH of the solubilized photoconductive layer
Is removed from the plate with a water washing solution having the following, and a plate surface protecting solution (protective gum solution) is applied as required to make the plate. In the plate making method according to this method, the image portion is formed not only of the toner image portion but also of the photoconductive layer under the toner image portion, and even if the toner image portion is worn, the photoconductive layer retains the function of the image portion. Excellent in printing durability.

In plate making by electrophotography, a surface charge is applied to a photoconductive layer using corona discharge or the like, and an electrostatic latent image formed by image exposure is developed with toner particles. Plate making is performed by forming a resist layer and eluting a non-image portion. Therefore, when the thickness of the photoconductive layer becomes thin or uneven due to the unevenness of the support, it becomes a spot of high or low surface potential and is detected as a difference in toner adhesion amount. In particular, in the case of laser exposure and camera projection exposure, a distribution occurs in the exposure amount at the boundary between the image portion and the non-image portion (image edge portion), and the unevenness of the photoconductive layer as described above occurs. In the case where the toner exists at the boundary, the difference in the amount of adhered toner appears as a difference in resist properties, and the edge portion of the image becomes jagged after elution, resulting in deterioration in resolution.

Usually, the surface of the photoconductive layer is manufactured so as to be as smooth as possible. In this case, the thickness of the photoconductive layer is reduced in accordance with the unevenness of the support. In positive development (for example, developing the photoconductive layer with a negatively charged or positively charged toner), the image becomes thicker in a thick portion of the photoconductive layer and becomes thinner in a thin portion of the photoconductive layer. On the other hand, in reversal development (for example, developing the photoconductive layer with positive charge or positively charged toner), the image becomes thinner in a thick portion of the photoconductive layer and becomes thicker in a thin portion. Such development is unique to electrophotographic lithographic printing plates. If the unevenness of the support is reduced, the image becomes clearer, but the adhesiveness with the photoconductive layer is deteriorated, and as a result, the printing durability is reduced, and even the water retention of the non-image part is deteriorated. It cannot be used as a lithographic printing plate.
In addition, if the thickness of the photoconductive layer is increased, the influence of the unevenness of the support is relatively reduced. Causes dirt. In order to completely elute the non-image portion, if the solubility of the eluate is increased, the side etch becomes large, the thin line drops off, and the resolving power deteriorates. Furthermore, the processing capacity of the eluate is reduced by the large amount of the photoconductive layer applied.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic lithographic printing plate having a photoconductive layer provided on a conductive support so as to improve the resolution and sharpness of a plate-making image. It is to provide an electrophotographic lithographic printing plate from which a printing plate can be obtained. It is another object of the present invention to provide an electrophotographic lithographic printing plate having a high printing durability, free from soiling of printed matter, and capable of obtaining a printing plate with good water retention.

[0009]

SUMMARY OF THE INVENTION The object of the present invention is to provide an electrophotographic lithographic printing plate in which the center line average roughness (Ra ₁ ) of the photoconductive layer side surface of the conductive support is 0.3. To 1.0 μm and a surface shape in which the ratio [Ra ₂ / Ra ₁ ] to the center line average roughness (Ra ₂ ) of the photoconductive layer surface is 0.5 to 1.0. .

The electrophotographic lithographic printing plate according to the present invention has at least a photoconductive layer on a conductive support. As the conductive support used in the present invention, a plastic sheet having a conductive surface, a sheet laminated with paper,
A conductive support having a hydrophilic surface, such as a metal plate of aluminum or zinc, may be used. Their thickness is 0.
It is preferably from 0.7 to 2 mm, more preferably from 0.1 to 0.5 mm. Among these supports, an aluminum plate is preferably used. This aluminum plate may contain aluminum as a main component and a small amount of various foreign elements, and conventionally known and publicly available materials can be appropriately used.

The conductive support according to the present invention is used by processing at least the surface on which the photoconductive layer is provided, if necessary. As a method of surface treatment, a known method, for example, graining or anodic oxidation can be used. Prior to the graining treatment, if necessary, a degreasing treatment is performed with a surfactant or an aqueous alkali solution. Graining methods include mechanical surface roughening, electrochemical surface roughening, and chemical surface selective dissolution. As the mechanical surface roughening method, known methods such as a ball polishing method, a brush polishing method, a blast polishing method, and a buff polishing method can be used. As the electrochemical surface roughening method, there is a method in which an alternating current or a direct current is used in a hydrochloric acid or nitric acid electrolyte. Further, as disclosed in Japanese Patent Application Laid-Open No. 54-63902, a method combining the two can be used.

In the present invention, a method for improving the water retention of the surface of a support and forming a dense and uniform grain with a depth of at least a certain level, particularly an electrochemical roughening process using an electrolyte mainly containing a mineral acid. Surface treatment is preferred. The depth of the grain is, for example,
As disclosed in JP-A-5-34240, it can be arbitrarily set within a specific range by controlling electrolysis conditions and the like. The aluminum plate thus roughened is used after desmutting and neutralizing if necessary.

The aluminum plate subjected to the above treatment is subjected to an anodizing treatment. As the electrolyte used for the anodizing treatment, sulfuric acid, phosphoric acid, oxalic acid or the like or a mixed acid thereof is used, and the electrolyte and the concentration thereof are appropriately determined depending on the type of the electrolyte. Anodizing conditions vary greatly depending on the electrolyte used and cannot be specified unconditionally. However, in general, the electrolyte concentration is 1.0 to 80% by weight, the liquid temperature is 5.0 to 70 ° C., and the current density is 0. 0.5 to 10 A / dm ² , a voltage of 1.0 to 100 V, and an electrolysis time of 10 to 3000 seconds. The amount of the anodic oxide film thus obtained is preferably 0.10 to 10 g / m ^{2, and more} preferably 1.0 to 6.0 g / m ^2.
/ M ² is preferred.

Further, as described in JP-B-47-5125, those treated with an alkali metal silicate aqueous solution after anodizing treatment are also suitable. Also, U.S. Pat.
The electrodeposition of silicate described in Japanese Patent No. 662 is also effective.
The treatment with polyvinyl sulfonic acid described in West German Patent Application No. 162478 is also suitable. In the present invention, the surface roughness of the photoconductive layer side surface of the conductive support is evaluated by the center line average roughness (Ra ₁ ), and the value is preferably in the range of 0.3 to 1.0 μm.

The surface roughness is used to express one-dimensional shape of three-dimensional unevenness from an algebraic viewpoint from a specific viewpoint, and indicates various properties obtained from a cross-sectional curve and a roughness curve. Here, the cross-sectional curve is a contour that appears at the cut surface when cut along a plane perpendicular to the surface to be measured. This cutting is performed in the direction in which the surface roughness appears most unless otherwise specified. For example, on a surface to be measured having directionality, it is cut at right angles to the direction. The surface roughness can be measured by the stylus method, topographer,
The conductivity according to the present invention is determined by various measurement methods such as light cutting, interferometry repetition, scene gloss, light scattering, laser speckle, white light speckle, porographic interference, interference fringe contrast, and capacitance method. The surface shape of the support photoconductive layer side surface and the photoconductive layer surface adopts a numerical value measured by a stylus type contact type device in consideration of the scanning length and the surface roughness level.

In a stylus type surface roughness measuring device of the type which directly reads the center line average roughness, the number of peaks per unit length, and the like, a so-called surface waviness component is removed. And an electrical filter for removing the same. Therefore, a curve different from the sectional curve (referred to as a roughness curve)
Is used to directly indicate the center line average roughness. The center line average roughness Ra is obtained by extracting a portion of the measurement length L from the extraction curve in the direction of the center line, and defining the center line of the extracted portion as X.
When the direction of the axis and the vertical magnification is the Z axis, and the extraction curve is represented by Z = f (x), it is given by the following equation and is displayed in μm. Ra = (1 / L) ∫ | f (x) | dx (μm) where Ra represents a value obtained by dividing the area of a portion surrounded by the extraction curve and the center line by the measured length.

The center line average roughness Ra in the present invention is defined by JIS B 0601 as in the above equation. In the present invention, the cutoff value is 0.08 mm and the measured length is 0.5 m.
m, the scanning speed is 0.06 mm / sec, and an average value of 10 measurements is adopted. The measurement point is the central part of the printing plate, and the measurement direction is perpendicular to the rolling direction of the aluminum, and each measurement is performed in the same direction.
It shall be measured at equal intervals of 00 μm. Further, in the present invention, the size and depth of the unevenness of the surface-treated conductive support cannot be evaluated with a standard 5 μm stylus which is finer than the standard. Therefore, in the present invention, a probe having a tip having a radius of curvature of 1 μm is used. In the present invention, Saascom 570A manufactured by Tokyo Seimitsu Co., Ltd. is used as a measuring device, and SAS-2010 manufactured by Meishin Koki Co., Ltd. is used as an analyzing device. Further, the data taking pitch in the X-axis direction is set to 0.2 μm or less.

By providing a known electrophotographic photoconductive layer on the conductive support thus obtained, an electrophotographic photosensitive member can be obtained. In the present invention, it is necessary to apply the photoconductive layer so that the thickness of the photoconductive layer does not differ as much as possible along the unevenness of the rough surface of the support. Such a change in thickness can be directly verified by cutting the conductive support coated with the photoconductive layer and observing the cross section, but this method can only perform local evaluation. In the present invention, in order to perform an average evaluation, the surface roughness of the surface of the photoconductive layer was measured, and it was found that the above-described direct evaluation could be substituted by the center line average roughness. The center line average roughness (Ra ₂ ) of the photoconductive layer surface is dependently determined by the center line average roughness (Ra ₁ ) of the surface-treated conductive support.
When a ₁ is in the range of 0.3 to 1.0 μm, Ra ₂ / Ra ₁
Is preferably in the range of 0.5 to 1.0.

As the photoconductive material used for the photoconductive layer according to the present invention, known organic compounds can be used. Examples of the organic photoconductive material include: a) a triazole derivative described in U.S. Pat. No. 3,121,197; b) an oxadiazol derivative described in U.S. Pat. No. 3,189,447; No. 16096, etc., and imidazole derivatives. D) U.S. Pat. Nos. 3,542,544 and 3,615,402.
No. 382089, JP-B-45-555
No. 51-10983, JP-A-51-93224
No. 55-108667, No. 55-156953
E) Polyarylalkane derivatives described in JP-A-56-36636, etc. e) U.S. Pat. Nos. 3,180,729 and 4,278,746, JP-A-55-88064, and JP-A-55-8806.
No. 5, No. 49-105537, No. 55-51086
No. 56-80051, No. 56-88141, No. 57-45545, No. 54-112637, No. 55
Pyrazoline derivatives and pyrazolone derivatives described in JP-A-74546; f) U.S. Pat. No. 3,615,404;
No. 10105, No. 46-3712, No. 47-2833
No. 6, JP-A-54-83435 and JP-A-54-11083.
6, phenylenediamine derivatives described in JP-A-54-119925 and the like; g) U.S. Pat. No. 3,567,450;
No. 3180703, No. 3240597, No. 3658
No. 520, No. 4232103, No. 4175961,
No. 4012376, West German Patent (DAS) 11105
No. 18, JP-B-49-35702, JP-B-39-2
No. 7577, JP-A-55-144250, and JP-A-56-1
19132, 56-22437, etc .; h) amino-substituted chalcone derivatives described in U.S. Pat. No. 3,526,501; i) N, N described in U.S. Pat. No. 3,542,546;
N-bicarbazyl derivatives, j) US Pat.
Oxazole derivatives described in the specification of JP-A No. 3 (1994) -46, k) styryl anthracene derivatives described in JP-A-56-46234, etc., 1) fluorenone derivatives described in JP-A-54-110837, etc., m) U.S. Pat. No. 3,717,462;
No. 59143 (corresponding to U.S. Pat. No. 4,150,987),
No. 55-52063, No. 55-52064, No. 55
No. 46760, No. 55-85495, No. 57-11
No. 350, No. 57-148749, No. 57-1041
No. 44, etc., hydrazone derivatives; n) US Pat.
Nos. 4,265,990, 4,273,846, 42
No. 99897, No. 4306008, etc .; benzidine derivatives; o) JP-A-58-90953, JP-A-59-95540.
No. 59-97148, No. 59-195658,
Stilbene derivatives described in JP-B-62-36674 and the like; p) Polyvinyl carbazole and derivatives thereof described in JP-B-34-10966; q) JP-B-43-18874 and JP-B-43-19192. Vinyl polymers such as polyvinyl vinylene, polyvinyl anthracene, poly-2-vinyl-4- (4′-dimethylaminophenyl) -5-phenyloxazole, poly-3-vinyl-N-ethylcarbazole, etc. r) Polymers such as polyacenaphthylene, polyindene, acenaphthylene / styrene copolymer described in JP-B-43-19193, and s) pyrene / polymers described in JP-B-56-13940.
Condensed resins such as formaldehyde resin and ethyl carbazole / formaldehyde resin; t) JP-A-56-90883 and JP-A-56-161550.
U) U.S. Pat. Nos. 3,397,086 and 4,666,802; Japanese Patent Publication Nos. 44-121671, 46-300.
No. 35, No. 49-17535, JP-A-49-11113
No. 6, No. 51-90827, No. 52-655543
And metal-free or metal (oxide) phthalocyanines and naphthalocyanines described in JP-A Nos. 57-148745, 64-2061 and 64-4389, and derivatives thereof.

The organic photoconductive compound according to the present invention is not limited to the compounds described in a) to u), but may be any of known organic photoconductive compounds. Two or more photoconductive compounds can be used in combination as desired.

The photoconductive layer for an electrophotographic lithographic printing plate according to the present invention comprises at least an organic photoconductive compound and an alkali and / or alcohol soluble binder resin. Since it is necessary to finally remove the non-image area photoconductive layer as the binder resin according to the present invention, this step involves the solubility of the photoconductive layer in the eluate, the toner adhesion amount in the image area, and the eluate. It is determined by the relative relationship with the resist property and cannot be unambiguously expressed, but at least the binder resin is preferably a polymer compound soluble or dispersible in the eluate.

Specific examples include styrene / maleic anhydride copolymer, styrene / maleic acid monoester copolymer, methacrylic acid / methacrylic acid ester copolymer, styrene / methacrylic acid / methacrylic acid ester copolymer, acrylic Styrene and methacrylic acid esters such as acid / methacrylic acid ester copolymer, styrene / acrylic acid / methacrylic acid ester copolymer, vinyl acetate / crotonic acid copolymer, vinyl acetate / crotonic acid / methacrylic acid ester copolymer; Acrylic acid ester, vinyl acetate,
A copolymer or methacrylamide of a carboxylic acid-containing monomer or an acid anhydride group-containing monomer such as vinyl benzoate or the like with acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, maleic anhydride, or fumaric acid; Vinylpyrrolidone, acryloylmorpholine, phenolic hydroxyl group,
Copolymers containing monomers having sulfonic acid groups, sulfonamide groups, and sulfonimide groups, phenolic resins, partially saponified vinyl acetate resins, xylene resins, and vinyl acetal resins such as polyvinyl butyral. Can be done.

A monomer-containing copolymer having an acid anhydride group or a carboxylic acid group and a phenol resin have a high charge retention when used as a photoreceptor for an electrophotographic printing plate, and can therefore be advantageously used. I can do it. As the monomer-containing copolymer having an acid anhydride group, a copolymer of styrene and maleic anhydride is preferable. Examples of the monomer-containing copolymer having a carboxylic acid group include a copolymer of styrene and maleic acid monoester, and a copolymer of acrylic acid or methacrylic acid and their alkyl esters, aryl esters or aralkyl esters. Polymers are preferred. Also, vinyl acetate and crotonic acid are good. Particularly preferred phenol resins are those obtained by condensing phenol, o-cresol, m-cresol, or p-cresol with methanal or ethanal under acidic conditions. And novolak resins. The binder resin may be used alone or in combination of two or more.

When only the photoconductive compound and the binder resin are used, if the content of the photoconductive compound is small, the sensitivity becomes low, so that the photoconductive compound (P) is used with respect to the binder resin (B). ) Is preferably used in a mixture of P / B (weight conversion) of 1/20 or more, more preferably 1/6 or more.

The electrophotographic lithographic printing plate according to the present invention can be obtained by coating a photoconductive layer on a conductive support according to a conventional method. In producing the photoconductive layer, a method of including the components constituting the photoconductive layer in the same layer, or a method of separately including two or more layers, for example, a charge carrier generation material and a charge carrier transport material A method of separating and using different layers is known, and it can be manufactured by any method.
The coating liquid is prepared by dissolving each component constituting the photoconductive layer in an appropriate solvent, but when using a component insoluble in a solvent such as a pigment, a ball mill, a paint shaker, a dyno mill,
Using a disperser such as an attritor, the average particle diameter is 0.01 to 5
μm, more preferably 0.05 to 0.2 μm. The binder resin and other additives used in the photoconductive layer can be added during or after the dispersion of the pigment or the like.

The coating solution thus prepared is spin-coated,
Electrophotographic lithographic printing plate coated and dried on a support by a known method such as blade coating, knife coating, reverse roll coating, dip coating, rod bar coating, spray coating, extrusion coating. However, when coating the photoconductive layer, the time from the application of the coating liquid to the support to the drying, that is, the so-called set time is an important point.
For example, if it takes a long time for the solvent to evaporate and dry after the application of the coating liquid, the coating liquid fills in the recesses on the surface of the roughened support, the dried photoconductive layer surface is flattened, and the photoconductive layer is dried. The difference in thickness between the convex portions and the concave portions of the support of the layer increases. Therefore, in the present invention, the viscosity of the coating liquid (solids) is adjusted so that the ratio Ra ₂ / Ra ₁ of the roughness Ra ₁ of the conductive support to the roughness Ra _{2 of the} surface of the photoconductive layer is in the range of 0.5 to 1.0. (E.g., concentration, solvent), coating and drying conditions, and the like.
In the case of 0 to 100 cp, the dryer d
The setting time of the coating photosensitive layer is shortened by raising the drying temperature of the coating, increasing the wind speed, or increasing the coating speed so as to enter the dryer zone as quickly as possible (within about 10 seconds) after the coating liquid is applied. Rapid drying is desirable.

The coating amount of the photoconductive layer is not particularly limited, but is preferably 5 g / m ² or less, particularly preferably 1.5 to 4 g / m ^2.
Is preferable. If the amount is too large, the charged potential can be maintained, but the side etch during elution is large, and if the amount is too small, the photosensitive layer partially escapes, making uniform coating difficult. INDUSTRIAL APPLICABILITY The present invention is advantageous for improving image resolution, reducing side etching during elution, improving the processing capacity of eluate, and the like.

The electrophotographic lithographic printing plate used in the present invention can be made by a known operation using the above-described electrophotographic photosensitive member. That is, it is charged substantially uniformly by corona discharge or the like in a dark place, and forms an electrostatic latent image by image exposure. Examples of the exposure method include reflection image exposure using a xenon lamp, a tungsten lamp, a fluorescent lamp or the like as a light source, contact exposure through a transparent positive film, and scanning exposure using laser light, a light emitting diode, or the like. When performing scanning exposure, a He-Ne laser, a He-Cd laser, an argon ion laser, a krypton ion laser, a ruby laser, a YAG laser, Nitrogen laser, dye laser, excimer laser, GaAs / GaAlA
scanning exposure using a laser light source such as a semiconductor laser such as s, InGaAsP, an Alexa dry laser, a copper vapor laser, or a scanning exposure using a light emitting diode or a liquid crystal shutter ( (Including a line printer type light source using a light emitting diode array, a liquid crystal shutter array, etc.).

In any of the above exposure methods, the boundary between the image area and the non-image area has a more or less distribution of the exposure amount, and accordingly, the toner adhesion amount is correspondingly reduced from the adhesion amount maintaining the resist properties near the boundary. It continuously decreases to the adhesion amount that cannot maintain the resist property. In the present invention, Ra ₂ / Ra ₁ is 0.1.
In the electrophotographic lithographic printing plate of 5 to 1.0, the unevenness of the charged potential is small, the boundary between the image portion and the non-image portion of the plate-making image after plate-making is formed along the unevenness of the surface of the support, and the line width is reduced. The run-out is virtually negligible.

Next, the electrostatic latent image is developed by toner. As the developing method, any of dry developing methods (cascade developing, magnetic brush developing, powder cloud developing) and liquid developing can be used. In particular, the liquid development method is suitable for producing a printing plate having good reproducibility, which can form a toner fine image. Further, positive / positive development by positive development and negative / positive development by reversal development under application of an appropriate bias voltage are also possible. The formed toner image can be fixed by a known fixing method such as heat fixing, pressure fixing, and solvent fixing. Using the toner image thus formed as a resist, the non-image portion photoconductive layer is removed with an eluent to prepare a printing plate.

The electrophotographic lithographic printing plate having been subjected to the toner development can be prepared by using the toner image as a resist and treating the non-image portion of the photoconductive layer with a plate-making processing solution.

The plate-making processing solution and the processing method according to the present invention will be described below. As the eluate for dissolving and removing the non-image portion photoconductive layer according to the present invention, any solution that at least solubilizes the binder resin can be used, and is not particularly limited, but preferably contains an alkali agent. Those having a buffer capacity are desirable. Examples of the alkaline agent include a silicate represented by a general formula SiO ₂ / M ₂ O (M = Na, K);
Inorganic alkali agents such as alkali metal hydroxides, alkali metal and ammonium salts of phosphoric acid and carbonic acid, ethanolamines, organic alkali agents represented by amines such as propanediamine, and mixtures thereof, and in particular, The above silicate is advantageously used because it exhibits a strong buffering capacity. In terms of formulation, it is desirable to add an alkali metal hydroxide to this.

The eluate according to the present invention contains a surfactant in order to improve the wettability of the eluate on the surface of the photoconductive layer, thereby improving the elution ability and expanding the elution conditions. Is preferred. Examples of preferred surfactants include alkyl benzene sulfonates (the alkyl group has 8 to 18 carbon atoms, more preferably 12 to 16 carbon atoms), and alkyl naphthalene sulfonates (the alkyl group has 3 to 3 carbon atoms).
10) Formalin condensate of naphthalenesulfonic acid, dialkylsulfosuccinates (the alkyl group has 2 carbon atoms)
To 18), anionic surfactants such as dialkyl amide sulfonates (the alkyl group has 11 to 17 carbon atoms), imidazoline derivatives, carboxybetaines, aminocarboxylic acids, sulfobetaines, aminosulfates, and imidazolines. And other amphoteric surfactants.

The eluate further includes ionic compounds described in JP-A-55-25100, water-soluble cationic polymers described in JP-A-55-95946, and JP-A-56-1.
Water-soluble amphoteric polymer electrolyte described in JP-A-42528, a neutral salt described in JP-A-58-75152,
Chelating agent described in JP-A-1909552, JP-A No. 1-17
No. 7541, a liquid viscosity modifier described in JP-A-63-22
No. 6657, preservatives and bactericides, US Pat.
50727 and 3545970, British Patent No. 138
Known components such as antifoaming agents described in JP-A Nos. 2901 and 1387713, and natural and synthetic water-soluble polymers can be contained as necessary.

The solvent in the eluate is not particularly limited as long as it can stably disperse and dissolve the above components, but water, more preferably, ion-exchanged water is advantageously used. Further, an appropriate amount of an organic solvent may be contained in order to further stabilize the above components or adjust the elution rate.

In order to make the electrophotographic lithographic printing plate of the present invention, an automatic elution machine is preferable, and a lithographic printing plate having at least an elution portion and a washing portion and further having a plate surface protective agent coating portion is preferable. It is sufficient that the plate is automatically conveyed and at least elution and rinsing (washing) can be performed, and the specifications of each part are not particularly limited. However, considering the aging of the eluate, depending on the method of supplying the eluate to the photoconductive layer surface, a large amount of the solubilized photoconductive layer flows into the eluate from the plate in the eluate to reduce the deterioration. It is desirable that the eluate be supplied as softly as possible, since it may accelerate. As a method for supplying the elution portion softly, a method is preferable in which the liquid discharged from the eluate supply pipe is uniformly supplied to the photoconductive layer through another member, for example, a rectifying plate, a roll on plate transport, or the like. . The discharge amount of the eluate at this time may be the minimum amount that can be uniformly supplied to the printing plate, but is preferably 1.5 to 100 times the liquid amount taken out of the printing plate when transported to the washing section, more preferably 5.0 to 50 times is good. It is preferable that the amount of the eluate carried out is as small as possible, and it is desirable to mechanically adjust the amount to be 10 g / m ² or less.

In the water washing section, a mechanism must be provided which can completely remove the solubilized photoconductive layer and excess eluate by supplying the water washing solution onto the plate. The liquid may be directly supplied to the solubilized photoconductive layer as long as the mechanism can suppress the scattering, or the elution promoting member described in JP-A-60-76395 may be applied to the water washing mechanism. In the washing section,
The solubilized photoconductive layer can be scraped off by directly contacting the rotating brush with the photoconductive layer, but usually the solubilized photoconductive layer can be easily removed without mechanical scraping, and the side-etch Because it can accelerate the deterioration.
Its use is undesirable.

The washed electrophotographic lithographic printing plate is treated with a rinsing solution containing an acidic substance, if necessary. The rinsing liquid that can be used in the present invention is preferably a liquid whose pH has been adjusted so that the binder resin in the electrophotographic lithographic printing plate photoconductive layer to be subjected to plate making does not re-aggregate. In other words, unless the initial pH of the rinsing liquid at least promotes the insolubilization of the binder resin, the binder resin flowing in with the washing liquid having a neutral or higher liquid pH at least during the liquid circulation pass is in a solubilized state. Therefore, the above-mentioned trouble due to the re-insolubilization of the binder resin can be prevented. However, since the rinsing liquid flows into the protective gum solution for plate surface protection, which is usually performed after that, even if slightly, if the pH of the rinsing solution is high, the p
Since H also inevitably rises early and the plate surface protection effect is attenuated, it is desirable to maintain the pH of the rinsing liquid at 7 or less.

Various test materials can be added to the rinsing liquid to adjust the pH of the rinsing liquid. In particular, in order to more stably process a large number of electrophotographic lithographic printing plates with an automatic dissolution machine or the like, it is desirable that the pH of the rinsing solution does not fluctuate during the plate making of at least the rinsing solution. It is desirable to include at least one of a water-soluble salt as an agent. Thereby, when the rinsing solution according to the present invention is applied to an electrophotographic lithographic printing plate, a basic component caused by an eluate remaining on the plate is neutralized, and the non-image portion becomes more hydrophilic.

The electrophotographic lithographic printing plate from which the non-image part photoconductive layer has been removed is subjected to a protective gum treatment for the purpose of improving the scratch resistance of the plate surface and desensitizing the non-image part. The protective gum solution that can be used in the present invention includes a polymer compound, a lipophilic substance,
And surfactants and the like, and all of these reagents can be known ones.

[0041]

EXAMPLES The present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the invention.

Example 1 JIS1050 aluminum sheet was treated with NaOH at 60 ° C.
Immerse in an aqueous solution for 1 minute and dissolve 4.5 g of aluminum
/ M ² . After washing with water, it was immersed in a 30% aqueous nitric acid solution for 1 minute to neutralize, and sufficiently washed with water. next,
Electrolytic surface roughening was performed in a 2.0% hydrochloric acid aqueous solution at 25 A / dm ² for 45 seconds, and the surface was immersed in a 2% aqueous NaOH solution at 30 ° C. to wash the surface, and then washed with water. Further, anodizing treatment was performed in a 20% sulfuric acid aqueous solution to form an aluminum oxide film on the surface, and the substrate was washed with water and dried to prepare a printing plate support. At this time, the center line average roughness (Ra ₁ ) of the surface treated surface of the support was 0.75 μm.

* Preparation and coating of photoconductive layer coating solution The following photoconductive layer composition dispersed in a paint shaker for 1 hour was coated on the surface-treated surface of the support with a bar coater, and immediately after 1 kW. While moving the hair dryer to the left and right, blowing temperature 1 from a distance of 10 cm from the plate
Hot air was rapidly dried while applying hot air at a temperature of 00 ° C. and a wind speed of 20 m / min to set an electrophotographic lithographic printing plate. At this time, the set time was 30 seconds. At this time, the coating amount of the photoconductive layer was 3.0 g / m ² , and the center line average roughness (Ra ₂ ) of the surface was 0.42 μm (that is, 0.42 μm).
_{5 <Ra 2 / Ra 1 <} 1.0).

Composition of Photoconductive Layer Coating Solution 1 Butyl methacrylate / methacrylic acid copolymer (40 mol% of methacrylic acid) 5.5 parts by weight χ type metal-free phthalocyanine 1.5 parts by weight 1,4-dioxane 75 parts by weight Part 2-propanol 8 parts by weight Viscosity (B-type viscometer rotor No. 1 rotation speed 60 rpm) 50 cp

* Toner development The obtained printing plate precursor was charged in a dark place by corona discharge so that the surface potential (V ₀ ) was about +300 V.
Scanning image exposure was performed using a semiconductor laser (780 nm), and immediately a positive charge toner (LOM- manufactured by Mitsubishi Paper Mills, Ltd.) was used.
When the toner was heat-fixed by liquid reversal development using EDIII), a toner image having a resolution of 50 lines / mm without jagged edges of lines along the irregularities on the surface of the photoconductive layer was obtained with good reproducibility. The sharpness of the image was also good.

* Plate-making treatment Next, plate-making treatment was performed using an automatic elution machine, an eluate, a washing solution and a rinsing liquid as described below.

1) Automatic dissolution machine The dissolution tank has a dissolution tank, a subsequent washing tank, and a rinsing tank.
A driving device for transporting the developed electrophotographic lithographic printing plate;
Storage tank for processing liquid in each processing tank → pump → spray nozzle →
An automatic machine having a device for circulating in a storage tank cycle and a replenishing device for each processing tank was used.

[0048] 2) eluent 1 Composition aqueous solution of sodium silicate (SiO ₂ minutes 30 wt%, SiO ₂ / Na ₂ O molar ratio of 2.5) 20 parts by weight of potassium hydroxide, 1 part by weight of pure water 79 parts by weight

3) Composition of washing liquid 1 (20 dm ³ ) 0.1 part by weight of dioctylsulfosuccinate Na 0.1 part by weight of 2-methyl-3-isothiazolone was dispersed and dissolved in pure water to make 100 parts by weight. 5% by weight for every 10 plate printing plate (A2 size) after 100 plate plate making.
15 ml of an aqueous glycine solution was added.

4) Rinse solution 1 composition (20 dm ³ ) Succinic acid 0.5 part by weight Phosphoric acid (85% aqueous solution) 0.5 part by weight Decaglyceryl monolaurate 0.05 part by weight 2-methyl-3- Isothiazolone 0.01 parts by weight Sodium hydroxide was added to adjust the solution pH to 4.7, and then made up to 100 parts by weight with pure water.

Plate making was performed using the above-mentioned processing solution (elution time was set to 6 seconds). As a result, a plate making image having a constant line width without jagged edges was obtained along irregularities on the surface of the support. No failures such as elution delay (pigment remaining) in the non-image area were observed in all the printing plates.

Next, when the printing plate was used for printing on an offset printing machine (Hamadastar 600 CD), a good printed matter was obtained on at least 100,000 sheets without generation of stain on the printed matter.

COMPARATIVE EXAMPLE 1 In Example 1, the photoconductive layer was coated with a bar coater.
Let stand for 0 seconds, and in a 90 ° C oven with a wind speed of 2 m / min for 5 seconds.
Dry slowly for minutes. At this time, the set time was 120 seconds. The center line average roughness (Ra ₂ ) of the surface is 0.1 mm.
It was 24 μm (Ra ₂ / Ra ₁ <0.5). All the obtained electrophotographic lithographic printing plates were developed and made under the same conditions as in Example 1. As a result, local unevenness in the thickness of the photoconductive layer became large. The potential was lowered, the photoconductive layer was thicker in the recesses, the surface potential was higher, and the edges of the lines after plate making were jagged. For this reason, the resolving power after plate-making was greatly reduced.

Example 2 The fountain type coater was prepared by using the photoconductive layer coating solution of Example 1 and adjusting the discharge amount so that the coated amount of the photosensitive layer after drying was 3.5 g / m ^2. To obtain an electrophotographic lithographic printing plate. At this time, the coating speed was 30 m / min, and the time from adhering the coating to entering the dryer zone was 5 sec.
The zone length, drying speed and wind speed of each dryer are respectively the first zone: 5 m, 120 ° C., 5 m / min, the second zone.
Zone: 5m, 140 ° C, 7.5m / min, 3rd zone
10 m, 140 ° C., 10 m / min, and set time was 20 sec. The center line average roughness (Ra ₂ ) of the surface was 0.5 μm (that is, 0.5 <Ra ₂ /
Ra ₁ <1.0).

When the obtained printing plate precursor was developed and made under the same conditions as in Example 1, a toner image having a resolution of 50 lines / mm without jagged edges of lines along the irregularities on the surface of the photoconductive layer was obtained. It was obtained with good reproducibility. The sharpness of the image was also good.

Comparative Example 2 In Example 2, the coating speed was set to 10 m / min, and the discharge amount was adjusted so that the coated amount of the photosensitive layer after drying was 3.5 g / m ^2. The drying of each dryer zone was performed. The temperature and the wind speed are respectively set in the first zone: 90 ° C., 3 m / min, the second zone: 1
20 ° C., 5 m / min, third zone: 140 ° C., 10 m
/ Min and set, the application time is 75
sec. At this time, the center line average roughness (Ra ₂ ) of the surface was 0.2 μm (Ra ₂ / Ra ₁ <0.2).
5).

The resulting electrophotographic lithographic printing plate was developed and plate-made under the same conditions as in Example 1. As a result, local unevenness in the thickness of the photoconductive layer became large. The thinner, lower surface potential, the thicker photoconductive layer in the recess, the higher surface potential, and the edge of the line after plate making was jagged. For this reason, the resolving power after plate-making was greatly reduced.

Examples 3 to 7 During the surface treatment step of the conductive support prepared in Example 1, a new support was prepared by changing the current density during roughening. The photoconductive layer coating solution 1 was applied to this in the same manner as in Example 1 to obtain an electrophotographic lithographic printing plate having the surface shape shown in Table 1.

[0059]

[Table 1]

All of the above electrophotographic lithographic printing plates were prepared in Example 1.
Developed under the same conditions as described above, and subjected to plate-making processing.
As in Table 1, in all of the printing plates, a toner image having a resolution of 50 lines / mm was obtained with good reproducibility without jagged edges of lines along the unevenness of the surface of the photoconductive layer, and the image after elution was also used for the support. A plate making image having a constant line width without jagged edges of the line was obtained along the irregularities on the surface. In addition, the dissolution property and the printing durability (100,000 sheets) were equivalent, and there was no problem.

Comparative Example 3 A photoconductive layer coating liquid 2 was prepared on the support of Example 3 in which the amount of the solvent dioxane in the photoconductive layer coating liquid 1 was reduced to a solid content concentration of 12%. Was applied and dried to produce an electrophotographic lithographic printing plate. The coating amount of the photoconductive layer was 4.0 g / m ² , and the center line average roughness (Ra ₂ ) of the surface was: It was 0.53 μm. That is
Ra ₂ / Ra ₁ = 1.5

After plate making, the edge of the image was observed. As a result, the side etch was large, as in Comparative Example 1, and the edge of the image was jagged.

Comparative Examples 4 to 6 During the surface treatment step of the conductive support prepared in Example 1, a new support was prepared by changing the current density during roughening. A support having the surface configuration shown in Table 2 was obtained.

[0064]

[Table 2]

The photoconductive layer coating solution 1 was applied to each of the above-mentioned supports in the same manner as in Comparative Example 2, and slowly dried with a dryer at 90 ° C. for 5 minutes. When all of the obtained electrophotographic lithographic printing plates were developed and subjected to plate making under the same conditions as in Example 1, the printing plate of Comparative Example 4 provided a toner image having a resolution of 50 lines / mm with good reproducibility. Of the photoconductive layer was peeled off during printing, and the plate jumped.

On the other hand, in Comparative Examples 5 and 6, the unevenness of the thickness of the photoconductive layer was increased, and the toner adhesion amount was uneven, and the edge of the image after plate making was jagged, as in Comparative Example 1.
The image resolving power deteriorated, and in the elution, the photoconductive layer remained in the valley of the support surface without being eluted, and the side etch also fluctuated greatly, and toner thin wire jumps occurred in some parts.

Example 8 JIS 1050 aluminum sheet was treated with NaOH at 60 ° C.
Immerse in an aqueous solution for 1 minute and dissolve 4.5 g of aluminum
/ M ² . After washing with water, it was immersed in a 30% aqueous nitric acid solution for 1 minute to neutralize, and sufficiently washed with water. next,
Electrolytic surface roughening was performed in a 1.7% aqueous nitric acid solution at 22 A / dm ² for 45 seconds, and the surface was washed by immersion in a 2% aqueous NaOH solution at 30 ° C., followed by water washing. Further, anodizing treatment was performed in a 20% sulfuric acid aqueous solution to form an aluminum oxide film on the surface, and the substrate was washed with water and dried to prepare a printing plate support. At this time, the center line average roughness (Ra ₁ ) of the surface treated surface of the support was 0.65 μm.

[0068] * Preparation and coating the support treated surface of the photoconductive layer coating solution, Peintosheika - at 1 hour dispersed was the following photoconductive layer composition the bus - co - data - after coating, Example Under the same conditions as in Example 1, rapid drying with hot air using a 1 kW hair dryer was performed to prepare an electrophotographic lithographic printing plate. At this time, the coating amount of the photoconductive layer was 3.0 g / m ² , and the center line average roughness (Ra ₂ ) of the surface was 0.38 μm (that is, 0.5 <Ra ₂ / Ra). ₁ <1).

Composition of Coating Solution for Photoconductive Layer 3 Vinyl acetate / crotonic acid copolymer (3 mol% of crotonic acid) 6 parts by weight Chlordiamble-2 parts by weight Diethylaminobenzaldehyde-N, N-diphenylhydrazone 1 part by weight 1,4 -Dioxane 84 parts by weight Dimethylformamide 7 parts by weight Viscosity 70 cp (Measurement conditions: same as in Example 1)

The obtained printing plate precursor was charged in a dark place by corona discharge so as to have a surface potential (V ₀ ) of about −400 V, and then was charged with a He-Ne laser (633 nm). Immediately after exposure to a scanning image, the toner was heat-fixed by liquid development with a positively charged toner (LOM-ED III, manufactured by Mitsubishi Paper Mills, Ltd.). Toner with resolution of 50 lines / mm without jaggedness
Images were obtained with good reproducibility. Next, a plate making process was performed using an eluate, a washing solution, and a rinse solution as described below.

[0071] solution 2 composition potassium silicate solution (SiO ₂ minutes 20 wt%, SiO ₂ / K ₂ O molar ratio of 3.5) 30 parts by weight of sodium hydroxide 1 part by weight of pure water 69 parts by weight

Rinse solution 2 composition (20 dm ³ ) 0.1 part by weight of sodium dioctylsulfosuccinate 0.01 part by weight of butyl p-hydroxybenzoate is dispersed and dissolved in pure water to make 100 parts by weight. After preparation, 100 printing plates, printing plate (A2 size) 10
Every time the plate was treated, 15 ml of a 5% by weight aqueous glycine solution was added.

Rinse solution 2 composition (20 dm ³ ) 0.2 part by weight of succinic acid 0.3 part by weight of citric acid 0.05 part by weight of sorbitan monolaurate 0.01 part by weight of 2-methyl-3-isothiazolone After adjusting the pH of the solution to 4.7 by adding sodium hydroxide, the solution was adjusted to 100 parts by weight with pure water.

When plate making was performed using the above processing solution (elution time was set to 6 seconds), side etching was about 2 μm on one side.
The variation was slight, and a plate-making image having a constant line width without jagged edges of the line was obtained along the irregularities on the surface of the support. No failures such as elution delay (pigment remaining) in the non-image area were observed in all the printing plates.

Next, when printing was carried out using this printing plate with an offset printing machine (Hamadastar 600 CD), good printed matter was obtained on at least 100,000 sheets without generation of stain on the printed matter.

Example 9 A JIS1050 aluminum sheet was heated at 50 ° C. and 10% N.
It was immersed in an aOH aqueous solution and etched so that the amount of aluminum dissolved was 6 g / m ² . After washing with water, it was immersed in a 30% aqueous nitric acid solution for 1 minute to neutralize, and sufficiently washed with water. Then 2.0
Electrolytic surface roughening was performed in a 20% aqueous hydrochloric acid solution at 20 A / dm ² for 60 seconds, and after desmutting in a 4% aqueous NaOH solution at 25 ° C., the surface was thoroughly washed with water. In addition, 20%
An anodizing treatment was carried out in a sulfuric acid aqueous solution, followed by washing with water and drying to prepare a printing plate support. At this time, the center line average roughness (Ra ₁ ) of the surface treated surface of the support was 0.60 μm.
Met.

The following photoconductive layer composition dispersed in a paint shaker for 1 hour was coated on the surface-treated surface of the support.
After coating with a coater, it was dried in the same manner as in Example 1 to produce an electrophotographic lithographic printing plate. At this time, the coating amount of the photoconductive layer was 5.0 g / m ² , and the center line average roughness (Ra
₂ ) was 0.40 μm (that is, Ra ₂ / Ra ₁ = 0.40).
67).

Composition of Photoconductive Layer Coating Liquid 4 Butyl methacrylate / methacrylic acid copolymer (40% by mole of methacrylic acid) 6 parts by weight Dibromo zanthrone 3 parts by weight 1,4-dimethylaminoethyl oxadiazole 2 parts by weight Part 2-propanol 79 parts by weight Dimethylformamide 10 parts by weight Viscosity 75 cp (measurement conditions: same as in Example 1)

The obtained printing plate precursor was charged in a dark place by corona discharge so as to have a surface potential (V ₀ ) of about −400 V, and then an underprint image was projected by a camera exposure, and then immediately corrected. Charge toner (LOM-ED II, manufactured by Mitsubishi Paper Mills, Ltd.)
When the toner was subjected to liquid development in step I) and thermally fixed, a toner image having a resolution of 30 lines / mm was obtained on the photoconductive layer with good reproducibility. The sharpness of the image was also good.

Next, plate making was performed using the treatment liquid of Example 8 (elution time was set to 8 seconds). As a result, the side etch had a slight variation of about 3 μm on one side, and the image was formed along irregularities on the surface of the support. A plate-making image without jagged edges was obtained. No failures such as elution delay (pigment remaining) in the non-image area were observed in all the printing plates.

Next, when the printing plate was used for printing with an offset printing machine (Hamadastar 600 CD), a good printed matter was obtained on at least 100,000 sheets without generation of stain on the printed matter.

[0082]

By using the electrophotographic lithographic printing plate of the present invention, the image resolution without jagged edges of a plate-making image can be obtained even in scanning exposure with a He-Ne laser or a semiconductor laser. The electrophotographic lithographic printing plate can be provided with high water retention, high water retention, no generation of stain on the printed matter, and high printing durability equal to or higher than that of a conventional photosensitive lithographic printing plate.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-212967 (JP, A) JP-A-4-51155 (JP, A) JP-A-4-29253 (JP, A) JP-A-2- 183271 (JP, A) JP-A-61-20048 (JP, A) JP-A-59-67095 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 13/26-13 / 32 G03G 5/04 G03G 5/05 102 G03G 5/10 B41N 1/14

Claims (1)

(57) [Claims] 1. A lithographic printing plate having a photoconductive layer comprising at least an organic photoconductive compound and an alkali and / or alcohol-soluble binder resin provided on a conductive support,
A toner image is formed by an electrophotographic method, and then the non-image portion photoconductive layer other than the toner image portion is dissolved and removed by contact with an alkaline eluent. the ratio of the conductive support of the center line average roughness of the photoconductive layer surface (Ra ₁₎ is 0.3 to 1.0 [mu] m, and the center line average roughness of the photoconductive layer surface and the (Ra ₂₎ [ Ra ₂ / R
electrophotographic lithographic printing plate a _1] is characterized by having a surface shape which is 0.5 to 1.0.