JPH11115334A - Original plate for lithographic printing and forming method of lithographic printing plate using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a large number of printed matters, which have no scumming and have a clear picture quality, by means of a dry aliphatic-desensitizing treatment. SOLUTION: This original plate for lithographic printing has an image accepting layer, which includes at least anatase type titanium particles and a binding resin and the contact angle between the surface of which and the water is 30 deg. or more and the contact angle between the surface of which after the irradiation of ultraviolet light and the water is 20 deg. or less, on a water resistant support. After a toner colored image is formed by means of an electrophotographic recording system on the image accepting layer, the ultraviolet light is applied to the whole surface of this image accepting layer so as to convert a non-image part into the state having a hydrophilic surface, which accepts no printing ink, in order to obtain a lithographic printing plate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithographic printing original plate and a method for preparing a lithographic printing plate using the lithographic printing plate. More specifically, the present invention relates to lithographic printing capable of printing a large number of clear printed images without background contamination. It relates to the preparation of a lithographic printing plate and a lithographic printing plate using the same.

[0002]

2. Description of the Related Art Lithographic printing plates currently used mainly in the field of light printing include (1) a water-resistant support,
(2) A direct-printing type master provided with a hydrophilic image-receiving layer, (2) a non-image area after directly making a plate on a water-resistant support provided with an image-receiving layer (lipophilic) containing zinc oxide Is subjected to a desensitizing treatment with a desensitizing solution to form a printing plate. (3) An electrophotographic light-sensitive material having a photoconductive layer containing photoconductive zinc oxide on a water-resistant support is used as an original plate. , The non-image part after image formation,
A printing plate is prepared by desensitizing with a desensitizing solution, and (4) a silver salt photographic original plate in which a silver halide emulsion layer is provided on a water-resistant support.

With the recent development of office equipment and the development of OA, in the printing field, various methods such as an electrophotographic printer, a thermal transfer printer, and an ink jet printer have been applied to the above-mentioned (1) original plate for direct drawing type lithographic printing. There is a demand for an offset lithographic printing method in which a printing plate is directly produced without performing a specific process for making a printing plate (that is, forming an image) to form a printing plate. In particular, digital signal input is supported as a terminal plotter in an electronic editing system that can be output to a remote terminal plotter via a high-speed communication network or satellite communication by operating a computer consistently from document input, correction, editing, layout to page set. A method of directly outputting a printing plate by using an electrophotographic printer has been proposed.

[0004] Conventional direct-drawing lithographic printing plate precursors are provided with a surface layer serving as an image receiving layer on both sides of a support such as paper via a back layer and an intermediate layer. Back layer or intermediate layer is PV
It is composed of a water-soluble resin such as A or starch, a water-dispersible resin such as a synthetic resin emulsion, and a pigment. The image receiving layer is
It is composed of an inorganic pigment, a water-soluble resin and a waterproofing agent. Conventionally, inorganic pigments include kaolin, clay, talc, calcium carbonate, silica, titanium oxide, zinc oxide, barium sulfate, alumina and the like.

As the water-soluble resin, modified PVA such as polyvinyl alcohol (PVA) and carboxy PVA;
Starch and derivatives thereof, carboxymethyl cellulose, cellulose derivatives such as hydroxyethyl cellulose,
Water-soluble resins such as casein, gelatin, polyvinylpyrrolidone, vinyl acetate-crotonic acid copolymer, and styrene-maleic acid copolymer are mentioned.

Examples of the waterproofing agent include an initial condensate of aminoplasts such as glyoxal, melamine formaldehyde resin, and urea formaldehyde resin, a modified polyamide resin such as a methylolated polyamide resin, and a polyamide.
Polyamine / epichlorohydrin adducts, polyamide epichlorohydrin resins, modified polyamide polyimide resins and the like are mentioned. It is also known that ammonium chloride, a crosslinking catalyst for a silane coupling agent, and the like can be used in combination.

However, in the conventional printing plate thus obtained, when the hydrophobicity is increased by increasing the amount of a water-proofing agent or using a hydrophobic resin in order to improve the printing durability. In addition, although the printing durability is improved, the hydrophilicity is reduced to cause printing stains. On the other hand, if the hydrophilicity is improved, the water resistance is deteriorated and the printing durability is reduced.

In particular, in a use environment at a high temperature of 30 ° C. or higher, the surface layer dissolves in a fountain solution used for offset printing, and has disadvantages such as reduced printing durability and generation of printing stains. Furthermore, in the case of direct drawing type lithographic printing, oily ink or the like is drawn as an image portion on the image receiving layer, and if the adhesiveness between the receiving layer of the printing original plate and the oily ink is not good, the hydrophilicity of the non-image portion can be improved. However, even if the above-described printing stains do not occur, the problem that the oily ink in the image area is lost at the time of printing and the printing durability is reduced as a result is still sufficiently solved. Not in.

On the other hand, after forming an image on an original plate having an image receiving layer containing zinc oxide, a method of desensitizing the non-image portion to desensitize the non-image portion to perform printing is performed by the following method. It has good image quality and can print many sheets. However, the complexity of wet processing such as the use of a desensitizing solution in the preparation of a printing plate and the necessity of a liquid containing a desensitizing component similar to the desensitizing solution as a fountain solution during printing is essential. Is mentioned. Further, since a fountain solution containing the above-mentioned components is used, depending on the printing ink used, it may interact with the components in the printing ink and cause stains on a printed matter. There is a problem that the used color printing cannot be performed.

[0010]

Recently, the technical improvement of digitally compatible electrophotographic printers has been remarkable, for example, high-resolution copy image formation or liquid formation using an electrophotographic printer using fine dry toner of 6 to 8 μm. High-definition copy image formation with good repetitive reproducibility by an electrophotographic printer using toner has been realized. Therefore, by using these laser printers and the like, in drawing by image transfer to a direct-printing type printing original plate, it is possible to achieve both background prevention of non-image portions after transfer and image reproducibility of the image portion, and to obtain a printed material with background contamination. It is desired that a clear image is obtained, that a large number of clear image prints can be printed, and that various color image prints can be easily obtained. Furthermore, in preparing a printing plate, it is required that the desensitizing process of a non-image portion be performed easily.

The present invention is to improve the above-mentioned problems in the preparation of the conventional electrophotographic printing plate. SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing an electrophotographic printing plate capable of printing a large number of clear printed images without background stains and without missing or distorted images. Another object of the present invention is to provide a lithographic printing plate precursor capable of printing a large number of prints of clear image quality without any background stains on various printing inks by dry desensitization treatment. Another object of the present invention is to provide a method for preparing an electrophotographic printing plate using a liquid toner capable of printing a large number of clear printed images having no background stain and no image bleeding.

[0012]

The above object is achieved by the following constitutions (1) to (6). (1) An image-receiving layer containing at least anatase-type titanium oxide particles and a binder resin on a water-resistant support,
A lithographic printing plate precursor for electrophotographic recording, wherein the contact angle with water on the surface of the image receiving layer is 30 degrees or more, and the contact angle with water on the surface after irradiation with ultraviolet light is 20 degrees or less. . (2) The smoothness of the surface of the image receiving layer is 30 in Beck smoothness.
(Sec / 10 cc) or more.
The lithographic printing original plate as described in the electrophotographic recording method. (3) The electrophotographic recording method according to (1) or (2), wherein the water-resistant support has an intrinsic electric resistance value of at least a portion immediately below the image receiving layer of 10 ¹³ Ω · cm or less. Lithographic printing plate.

(4) Toner coloration using an electrophotographic recording method on an image receiving layer of a lithographic printing plate precursor having an image receiving layer containing at least anatase type titanium oxide particles and a binder resin on a water-resistant support. A lithographic printing plate, characterized in that, after forming an image, the entire surface of the image receiving layer is irradiated with ultraviolet light to convert a non-image portion into a hydrophilic surface state that does not accept printing ink to form a lithographic printing plate. How to create (5) The method for preparing a lithographic printing plate as described in (4) above, wherein the image formation using the electrophotographic recording method is performed using a liquid developer. (6) The lithographic printing plate as described in (4) or (5) above, wherein the water-resistant support has at least a portion immediately below the image receiving layer having an intrinsic electric resistance of 10 ¹³ Ω · cm or less. How to create

[0014]

Embodiments of the present invention will be described below in detail. The present invention provides a lithographic printing plate precursor
After forming a colored image by an electrophotographic recording method or the like, the entire image is exposed to ultraviolet light and the non-image area is converted to hydrophilic to form a lithographic printing plate.The lithographic printing plate used has excellent image strength. The printing plate thus obtained does not cause the printing ink stain on the non-image area after the hydrophilization treatment, and the obtained printing plate can print many clear images.

The lithographic printing original plate used in the present invention will be described below. The image receiving layer provided on the water-resistant support of the present invention contains anatase type titanium oxide and a binder resin as main components. The surface Beck smoothness is 30
(Second / 10 cc) or more is preferable. More preferably, 60
~ 2,000 (sec / 10cc).

Here, the Beck smoothness can be measured by a Beck smoothness tester. A Beck smoothness tester is a tester in which a test piece is pressed at a constant pressure (1 kg / cm ² ) onto a highly smooth finished circular glass plate with a hole at the center, and a fixed amount (10 cc) is obtained under reduced pressure. It measures the time required for air to pass between the glass surface and the specimen.

The image receiving layer has a contact angle with water of 30 degrees or more, preferably 40 degrees to 120 degrees, and more preferably 50 degrees to 100 degrees. By adjusting to this range, the toner image formed by the electrophotographic recording method or the like is sufficiently adhered to the image receiving layer, and even when used as a printing plate, the image portion does not drop during printing.

Further, the non-image part is brought into the above-mentioned hydrophilic surface state of 20 ° or less, preferably 15 ° or less, more preferably 10 ° or less in contact angle with water by irradiation with ultraviolet light. It is characterized by changing. Further, the present invention is characterized in that even when a printing plate having a non-image portion made hydrophilic is left for a long time, its hydrophilic state is sufficiently maintained.

The titanium oxide particles used in the present invention have
The crystal form is anatase type, photo-excited by irradiation of ultraviolet light,
Make sure that the particle surface becomes hydrophilic at a contact angle with water of 20 degrees or less.
And features. The surface is converted to hydrophilic by light irradiation.
For details of elephants, for example, Toshiya Watanabe, ceramics,31
(No. 10), 837 (1966), etc.
I have. The average particle size of the anatase type titanium oxide particles is 5 nm
~ 500 nm, more preferably 5-10
0 nm. In this range, by ultraviolet light irradiation
The surface is hydrophilized appropriately. Anatase-type titanium oxide
In the crystal, at least 30% by weight or more of the
It is sufficient if it has a natase type crystal structure, preferably 50 weight
% Or more.

The particles are commercially available as a powder or as a titania sol dispersion. Examples include Ishihara Sangyo Co., Ltd., Titanium Industry Co., Ltd., Sakai Chemical Co., Ltd., Nippon Aerosil Co., Ltd., Nissan Chemical Industry Co., Ltd. Further, the anatase type titanium oxide particles used in the present invention may contain another metal element or an oxide thereof.
The inclusion includes coating, supporting, or doping on the surface and / or inside of the particles.

As the metal element contained, for example, S
i, Mg, V, Mn, Fe, Sn, Ni, Mo, Ru,
Rh, Re, Os, Cr, Sb, In, Ir, Ta, N
b, Cs, Pd, Pt, Au and the like. Specifically, JP-A-7-228738 and JP-A-7-187677
Nos. 8-81223, 8-257399, 8
No. -283022, No. 9-25123, No. 9-714
37 and 9-70532. The content of the anatase type titanium oxide used in the present invention is 90% by weight or more, preferably 95% by weight or more.

As the binder resin provided for the image receiving layer of the present invention, all those known as conventional binder resins can be used. Typical are vinyl chloride-vinyl acetate copolymer, styrene-butadiene copolymer, styrene-
Methacrylate copolymer, methacrylate copolymer, acrylate copolymer, vinyl acetate copolymer, polyvinyl butyral, alkyd resin, silicone resin, epoxy resin, epoxy ester resin, polyester resin, etc., and polyvinyl alcohol as a water-soluble polymer compound , Modified polyvinyl alcohol, starch, oxidized starch, carboxymethylcellulose, hydroxyethylcellulose, casein, gelatin, acrylic acid copolymer, methacrylic acid copolymer, vinylpyrodoline copolymer, polyvinyl ether-maleic anhydride copolymer, polyamide And polyacrylamide. These resins may be used alone or in combination of two or more.

The molecular weight of the binder resin used in the image receiving layer of the present invention is preferably 10 ³ to 10 ⁵ , and more preferably 5 to 5.
× 10 ^{3 to} 5 × 10 ⁵ . The glass transition point of the resin is preferably from -10C to 120C, more preferably from 0C to 90C. The image receiving layer of the present invention may contain other constituent components in addition to the components described above. As other components, inorganic pigment particles other than the anatase type titanium oxide particles of the present invention may be contained. For example, silica, alumina, kaolin, clay, zinc oxide, calcium carbonate,
Examples include barium carbonate, calcium sulfate, barium sulfate, magnesium carbonate, and titanium oxide other than anatase type crystals. These other inorganic pigments are present in an amount not exceeding 40 parts by weight based on the anatase type titanium oxide particles of the present invention. Preferably, it is within 30 parts by weight.

The ratio of pigment / binder resin in the image receiving layer is as follows:
Generally, the binder resin is 8 to 25 parts by weight based on 100 parts by weight of the pigment.
Parts by weight, preferably 10 to 22 parts by weight. Within this range, the effects of the present invention are effectively exhibited, and the film strength is maintained during printing or the high hydrophilicity is maintained during desensitization treatment. In addition, a crosslinking agent may be added to the image receiving layer in order to further improve the film strength. In particular, when a water-soluble resin is used as the binder resin, it is preferable to use a crosslinking agent in combination to cure the film and improve the water resistance. Examples of the crosslinking agent include compounds that are usually used as a crosslinking agent. Specifically, compounds described in Shinzo Yamashita, Tosuke Kaneko, “Handbook of Crosslinking Agents” Taiseisha (1981), edited by The Society of Polymer Science, “Polymer Data Handbook, Basic Edition”, Baifukan (1986), etc. Can be used.

For example, ammonium chloride, metal ions,
Organic peroxides, organic silane compounds (for example, silanes such as vinyltrimethoxysilane, vinyltributoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-aminopropyltriethoxysilane, etc. Coupling agents, etc.), polyisocyanate compounds (for example, toluylene diisocyanate, diphenylmethane diisocyanate, triphenylmethane triisocyanate, polymethylene polyphenylisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, high Molecular polyisocyanate, etc.), polyol compounds (for example, 1,4-butanediol, polyoxypropylene glycol, polyoxyethylene glycol, 1,1,1-trimethylolpropane, etc.), Amine compound (e.g., ethylenediamine, .gamma.-hydroxypropyl ethylenediamine, phenylenediamine, hexamethylenediamine-diamine, N
-Aminoethylpiperazine, modified aliphatic polyamines, etc.), titanate coupling compounds (eg, tetrabutoxytitanate, tetrachloroepoxytitanate, isopropyl tristearoyl titanate, etc.), aluminum coupling compounds (eg, aluminum butyrate, aluminum acetyl acetate) , Aluminum oxide octate, aluminum tris (acetyl acetate), etc.), polyepoxy group-containing compounds and epoxy resins (for example, "New epoxy resin" edited by Hiroshi Kakiuchi)
Compounds described in Shokodo (1985), "Epoxy Resins" edited by Kuniyuki Hashimoto and published by Nikkan Kogyo Shimbun (1969), etc., and melamine resins (for example, "Uria Melamine Resin" edited by Ichiro Miwa and Hideo Matsunaga) Kogyo Shimbun (196
9), poly (meth) acrylate compounds (for example, “Oligomers” edited by Shin Ogawara, Takeo Saegusa, Toshinobu Higashimura, Kodansha (1976), Eizo Omori “Functional acrylic resin” Compounds described in Techno System (1985) and the like.

In the present invention, a reaction accelerator may be added as needed to accelerate the crosslinking reaction in the image receiving layer. In the case of a reaction mode in which a crosslinking reaction forms a chemical bond between functional groups, for example, organic acids (acetic acid, propionic acid, butyric acid, benzenesulfonic acid, p-toluenesulfonic acid, etc.), phenols (phenol, chlorophenol, Nitrophenol, cyanophenol, bromophenol, naphthol, dichlorophenol, etc.), organometallic compounds (acetylacetonato zirconium salt, acetylacetone zirconium salt, acetylacetocobalt salt, dibutoxytin dilaurate, etc.), dithiocarbamic acid compounds (diethyldithiocarbamate, etc.) ), Tinouram disulfide compounds (such as tetramethyltinouram disulfide), carboxylic anhydrides (phthalic anhydride, maleic anhydride, succinic anhydride, butylsuccinic anhydride,
3,3 ', 4,4'-tetracarboxylic acid benzophenone dianhydride, trimellitic anhydride, etc.).
When the cross-linking reaction is a polymerization reaction mode, a polymerization initiator (a peroxide, an azobis-based compound, or the like) may be used.

The binder resin is preferably thermoset after the application of the image receiving layer composition. In order to carry out thermosetting, for example, the drying conditions are made stricter than the drying conditions at the time of the conventional receiving layer production. For example, it is preferable to set the drying conditions to a high temperature and / or a long time, or to further heat-treat after drying the coating solvent. For example, the treatment is performed at 60 ° C. to 150 ° C. for 5 to 120 minutes. When the above-mentioned reaction accelerator is used in combination, the treatment can be performed under milder conditions. Furthermore, JP-A-4-201387 and JP-A-4-22319.
No. 6, No. 4-319492, No. 5-5807
No. 1, No. 4-353495, No. 5-1195
No. 45, etc., may contain resin particles containing a specific functional group.

By using these inorganic pigments or resin particles within the above-mentioned usage range, the printing plate after desensitization (hydrophilicity) of the non-image area by irradiation with ultraviolet light can prevent the background stain of the printed matter, Further, the image portion is sufficiently adhered to the image receiving layer, and sufficient printing durability can be obtained without causing image defects even when the number of printed sheets increases. Further, it is preferable because the film strength of the image portion layer of the plate-making printing plate is also improved.

Other additives may be used in the image receiving layer in order to improve various properties such as adhesiveness, film formability, and film strength. For example, rosin, petroleum resin, silicone oil, etc., such as polybutene, DOP, DBP, low molecular styrene resin, and low molecular Polyethylene wax, microcrystalline wax, paraffin wax and the like can be added within a range that does not affect the background of the printing plate. The thickness of the image receiving layer is preferably 0.1 to 10 μm, more preferably 0.5 to 5 μm.
Range. Within this range, it is possible to print a large number of sheets without background stain on the printed matter.

As the water-resistant support, an aluminum plate,
Bimetal plates such as zinc plate, copper-aluminum plate, copper-stainless plate, chromium-copper plate, etc., and tri-metal plates such as chrome-copper-aluminum plate, chrome-lead-iron plate, chromium-copper-stainless plate, etc. Is 0.1 to 3 mm, especially 0.1 mm.
1 to 1 mm. Moreover, the thickness is 80 μm or more.
Paper, plastic film or metal film-laminated paper or plastic film which has been subjected to a water resistance treatment of 200 μm, and the like can be used. The support provided in the present invention has a surface smoothness on the side adjacent to the image receiving layer of 300 (sec / 10 cc) or more, preferably 90 in Beck smoothness.
It is preferably adjusted to 0 to 3000 (sec / 10 cc), more preferably 1000 to 3000 (sec / 10 cc).
cc).

By regulating the smoothness of the surface of the support on the side adjacent to the image receiving layer to a Beck smoothness of 300 (sec / 10 cc) or more, image reproducibility and printing durability can be further improved. . Such an improvement effect can be obtained even if the smoothness of the image receiving layer surface is the same, and the adhesion between the image portion and the image receiving layer is improved by increasing the smoothness of the support surface. Conceivable. The highly smooth surface of the water-resistant support thus regulated refers to a surface on which the image receiving layer is directly applied. For example, when an underlayer or an overcoat layer described later is provided on the support, Means the surface of the underlayer or overcoat layer.

As a result, the image receiving layer in which the surface shape is adjusted as described above is sufficiently retained without receiving the unevenness of the surface of the support, and the image quality can be further improved. As a method for setting the smoothness in the above range, various conventionally known methods can be used. Specifically, a method of adjusting the Beck smoothness of the surface of the support body by a method such as a method of melting and bonding the substrate surface with a resin, a method of strengthening a calendar with a high-smooth heat roller, and the like can be used. .

Further, in the present invention, a toner image is formed on an image receiving layer provided on a water-resistant support by an electrophotographic recording method. Usually, the toner image is formed on an image-receiving material by an electrophotographic process. The transfer of the toner image is performed by electrostatic transfer, and the original plate of the present invention can be preferably used as a lithographic printing original plate used for forming such an electrostatic transfer image. The lithographic printing plate can print a large number of clear images. Further, the specific resistance of the water-resistant support as a printing original plate is preferably 10 ¹³ Ω · cm or less. Also, when a PPC copying machine using electrostatic transfer is used for transfer to a transfer material using dry toner,
It is more preferably 10 ³ to 10 ¹³ Ω · cm, and still more preferably 10 ⁶ to 10 ¹² Ω · cm. As a result, it is possible to obtain a good image which has practically no problem such as bleeding / distortion of the transferred image and toner contamination on the non-image portion.

In order to impart the above-described conductivity to the portion of the support immediately below the image receiving layer, a layer comprising a conductive filler such as carbon black and a binder is provided on a substrate such as paper or film. Examples of the method include coating, attaching a metal foil, and depositing a metal. On the other hand, examples of the support having conductivity as a whole include conductive paper impregnated with sodium chloride and the like, plastic films mixed with a conductive filler such as carbon black, and metal plates such as aluminum.

The measurement of the specific electric resistance (also called the volume specific electric resistance or the specific electric resistance) is performed by Jls
The test was performed by a three-terminal method provided with a guard electrode based on K-6911. As a method of adjusting the conductivity of the support, there are a method of adjusting the entire support and a method of providing a conductive layer on one side and / or both sides of the support. For example, the support can be obtained by using a conductive base paper impregnated with sodium chloride or the like on a substrate and providing a water-resistant conductive layer on both surfaces thereof.

In the present invention, as the base paper used as the base, for example, wood pulp paper, synthetic pulp paper, or a mixed paper of wood pulp paper and synthetic pulp paper can be used as it is. The thickness of the base paper is 80 μm to 200 μm.
μm is preferred. When the conductive layer is adjusted by providing the conductive layer, the conductive layer is a layer containing a conductive agent and a binder.

The conductive agent may be either inorganic or organic, and may be used alone or in combination of two or more. Examples of inorganic materials include, for example, Na,
Salts of monovalent metals such as K and Li, Mg, Ca, Ba, Zn,
Examples include salts or oxides of polyvalent metals such as Ti, Co, Ni, Zr, Al, and Si, and ammonium salts. The organic compound may be a low-molecular compound or a high-molecular compound, and examples thereof include compounds conventionally used as a conductive agent, an antistatic agent, a surfactant, and the like. For example, metal soaps (eg, metal salts of organic carboxylic acids / sulfonic acids / phosphonic acids, etc.), quaternary salt compounds (quaternary ammonium salts, phosphonium salts, etc.), anionic surfactants,
Nonionic surfactants, cationic surfactants, alcohol compounds (for example, crystalline compounds such as acetylene-1,2-diol, xylylene diol, bisphenol A)
Known materials such as the above can be used alone or in a mixture of two or more.

The amount of the conductive agent to be added is 3 to 50% by weight, preferably 5 to 30% by weight of the binder resin used in the layer. On the other hand, as the resin used as the binder, various resins are appropriately selected and used. Specifically, as the hydrophobic resin, for example, acrylic resin, vinyl chloride resin, styrene resin, styrene-butadiene resin, styrene-acrylic resin, urethane resin,
Vinylidene chloride-based resins, vinyl acetate-based resins, etc. are used. Examples of hydrophilic resins include polyvinyl alcohol-based resins, cellulose derivatives, starch and its derivatives, polyacrylamide resins, vinyl ether-maleic anhydride copolymers, and styrene. Maleic anhydride copolymers and the like can be mentioned. The coating amount of these conductive layers is 1 to 30
g / m ^2, it is suitable in particular 3 to 20 g / m ^2. As described above, a water-resistant support having conductivity having a specific electric resistance value of 10 ¹³ Ω · cm or less can be obtained.

In the present invention, as described above, a back coat layer (back layer) can be provided on the surface of the support opposite to the image receiving layer for the purpose of preventing curling, but the back coat layer has a smoothness. It is preferably in the range of 150 to 700 (sec / 10 cc). Thus, when the printing plate is supplied to the offset printing press, the printing plate is accurately set on the printing press without causing displacement or slippage.

More preferably, the water-resistant support provided with an under layer or a back coat layer has a thickness of 90%.
１３０130 μm, preferably 100-120 μm. As a result, in plate making by a PPC copying machine using an electrostatic transfer method, a clear image without background contamination can be obtained, and the fixability of the toner image can be sufficiently performed. Even with an adhesive force, the toner image does not drop. An image is formed by electrophotography on the lithographic printing original plate as described above to form a plate making plate.

As an electrophotographic recording method, any of conventionally known recording methods can be used. For example, edited by the Electrographic Society of Japan, "Basics and Application of Electrophotographic Technology", published by Corona Co., Ltd. (1988), Kenichi Eda, Journal of the Electrophotographic Society
27 , 113 (1988), Kawamoto Akio, 33 , 149
(1994), Akio Kawamoto, 32 , 196 (1993)
And PPC copiers on the market. . A combination of a scanning exposure method using a laser beam for exposing based on digital information and a development method using a liquid developer is an effective process because a high-definition image can be formed. An example is shown below.

First, the photosensitive material is positioned on the flat bed by the register pin method, and then suction-fixed from the back surface by air suction and fixed. Next, the photosensitive material is charged by the charging device described in, for example, the above-mentioned “Basics and Application of Electrophotographic Technology”, page 212 et seq. The corotron or scotron system is common. At this time, it is also preferable to control the charging conditions by applying feedback so that the surface potential always falls within a predetermined range based on the information from the charged potential detecting means of the photosensitive material. Thereafter, for example, scanning exposure using a laser light source is performed using the method described on page 254 and thereafter of the above-cited reference material.

Next, a toner image is formed using a liquid developer. The photosensitive material charged and exposed on the flatbed can be removed therefrom, and the wet developing method described on page 275 et seq. The exposure mode at this time is performed in correspondence with the toner image development mode. For example, in the case of reversal development, the negative image, that is, the same charge polarity as when the photosensitive material is charged by irradiating the image portion with laser light and charging the photosensitive material Is applied, and a developing bias voltage is applied so that the toner is electrodeposited on the exposed portion. Details of the principle are described on page 157 et seq.

In order to remove excess developer after development, squeeze such as rubber roller, gap roller, reverse roller, corona squeeze, air squeeze, etc. are performed as shown on page 283 of the same document. It is also preferable to rinse only the carrier liquid of the developer before squeezing. Next, the toner image layer formed as described above on the photoreceptor is transferred and fixed on a lithographic printing original plate which is a transfer material, or is transferred and fixed on a transfer material via an intermediate transfer member. Things.

The plate-making master obtained as described above is irradiated with ultraviolet light over the entire surface, and only the non-image portion is selectively converted to a hydrophilic surface state. The image portion is a colored toner image, and retains lipophilicity because it is impermeable to ultraviolet light. As the ultraviolet light source to be used, any lamp having a wavelength of 300 to 450 nm may be used. Preferably, those having a wavelength of 350 to 420 nm are effectively used.

For example, there are a mercury lamp, a metal halide lamp, a xenon lamp and the like. Light irradiation is arbitrarily selected as long as the contact angle with water on the surface of the irradiated portion changes to 5 degrees or less, preferably to 0 degrees. For example, an irradiation time of 30 seconds to 5 minutes is preferable. As described above, it is possible to create a printing plate that enables a printed material having a clear print image without background smearing by offset printing.

[0047]

EXAMPLES The present invention will be described in detail with reference to examples below, but the contents of the present invention are not limited to these examples. Example 1 <Preparation of a lithographic printing original plate> A composition having the following contents was added to a paint shaker (Toyo Seiki Co., Ltd.) together with glass beads.
And dispersed for 60 minutes, and then the glass beads were separated by filtration to obtain a dispersion. Photocatalytic titanium oxide sol 40% solution: titanium oxide slurry 100 g STS-21 (manufactured by Ishihara Sangyo Co., Ltd.) Alumina sol 520 20.7% liquid (manufactured by Nissan Chemical Industries, Ltd.) 48 g polyvinyl alcohol: 10% aqueous solution of PVA-117 100 g (Manufactured by Kuraray Co., Ltd.) 80% aqueous solution of melamine formaldehyde resin 1.1 g 10% aqueous solution of ammonium chloride 1.0 g

A support of ELP-1 type master (trade name, manufactured by Fuji Photo Film Co., Ltd.) used as an electrophotographic planographic printing plate for light printing (Beck smoothness of one under side: 500 (second / 10 cc)) The above composition was applied thereon using a wire bar, and dried at 130 ° C. for 30 minutes to form an image receiving layer having a coating amount of 5 g / m ² , thereby obtaining a lithographic printing original plate. Using a Beck smoothness tester (manufactured by Kumagai Riko Co., Ltd.), the lithographic printing plate precursor was measured for its smoothness (second / 10 cc) under the condition of an air volume of 10 cc, and it was 800 (second / 10 cc). . Further, 2 μl of distilled water was placed on the surface of the lithographic printing plate precursor, and the surface contact angle (degree) after 30 seconds was measured using a surface contact meter (CA-D, trade name, manufactured by Kyowa Interface Science Co., Ltd.). Then, it was 70 degrees.

The electrophotographic photosensitive member prepared as described below is charged in a dark place with a corona and charged to a surface potential of +450 V. Then, the original is read in advance from a document by a color scanner, color-separated, and subjected to some system-specific operations. After making corrections related to the color reproduction of the image, based on the information stored on the hard disk in the system as digital image data, the beam spot diameter was changed to 788 nm using a semiconductor laser drawing device as an exposure device. Exposure was performed at a pitch of 10 μm and a scan speed of 300 cm / sec (that is, 2500 dpi). Exposure was performed so that the exposure amount on the photoconductor at this time was 25 erg / cm ² .

<Electrophotographic Photoreceptor> 2 g of X-type metal-free phthalocyanine (manufactured by Dainippon Ink and Chemicals, Inc.) and the following binder resin (P
-1) 14.4 g, the following binder resin (P-2) 3.6 g,
0.15 g of the following compound (A) and cyclohexanone 80
g of the mixture was placed in a 500 ml glass container together with glass beads, and dispersed in a paint shaker (manufactured by Toyo Seiki Seisaku-sho) for 60 minutes. The glass beads were filtered off to obtain a photosensitive layer dispersion.

[0051]

Embedded image

Next, this dispersion was subjected to a degreasing treatment.
Apply on a 2mm thick aluminum plate with a wire bar,
After drying to the touch, it was heated in a circulation oven at 110 ° C. for 20 seconds. The thickness of the obtained photosensitive layer was 8 μm.

Subsequently, development was carried out using a liquid developer having the following contents, followed by rinsing in a single bath of Isopar G to remove stains on the non-image area, and then using hot air having a photoconductor surface temperature of 50 ° C. The remaining amount of Isopar G is (10mg / toner weight mg)
And dried. Subsequently, the photosensitive member was precharged at -6 KV by a corona charger, the image surface of the photosensitive member was overlapped with the lithographic printing plate precursor, and transferred by applying a negative corona discharge from the electrophotographic photosensitive member side. .

<Liquid developer> The following components were mixed in a kneader and kneaded at 95 ° C for 2 hours to obtain a mixture. The mixture was cooled in a kneader and then ground in the same kneader. One part by weight of the ground product and 4 parts by weight of Isopar H were dispersed with a paint shaker for 6 hours to obtain a dispersion. This dispersion is diluted with Isopar G so that the toner solid content is 1 g per liter, and at the same time, basic barium petrone is used as a charge control agent for imparting negative charge.
A liquid developer was prepared so as to contain 0.1 g per liter. (Kneading composition) Ethylene / methacrylic acid copolymer 3 parts by weight (Mitsui DuPont, Nucrel N-699) Carbon black # 30 (Mitsubishi Kasei Co., Ltd.) 1 part by weight Isopar L (Exxon) 12 parts by weight Department

The lithographic printing original plate (plate making plate) on which the image was formed was heated at 100 ° C. for 30 seconds to completely fix the toner image portion. The drawing image of the obtained plate-making product is obtained by an optical microscope.
It was observed and evaluated at a magnification of 200 times. The image was clear with no bleeding or missing of fine lines and characters. Next, this plate-making original plate was irradiated with light from a light source at a distance of 10 cm for 3 minutes using a 100 W high-pressure mercury lamp. The surface wettability of the non-image portion and the image portion (solid image portion) of the obtained plate was measured by the contact angle with water. The surface of the non-image part changed to 8 degrees, and the surface of the image part was 90 degrees.

Next, the printing plate prepared as described above was used as a printing machine with an Oliver 94 type (manufactured by Sakurai Seisakusho Co., Ltd.), and as a dampening solution, an SLM-OD (Mitsubishi Paper Mills Co., Ltd.).
Was diluted 100 times with distilled water, placed in a fountain solution tray, and printed using a black ink for offset printing on a printing paper through a plate. When the printed image of the tenth printed material was visually evaluated using a 20-fold loupe, no background stain due to adhesion of the printing ink to the non-image portion was observed, and the uniformity of the solid image portion was good. Further, when observed with an optical microscope at a magnification of 200 times, no fine lines or fine characters were found to be thin or missing. More than 3,000 prints of the same print quality were obtained.

Examples 2 to 5 and Comparative Examples A to C [Preparation of Water-Resistant Support] A high-quality paper weighing 100 g / m ² was used as a substrate, and a back layer paint having the following composition was coated on one surface of the substrate with a wire. Apply using a bar, dry application amount 12g /
After the m ² back layer was provided, calendering was performed so that the back layer had a smoothness of about 50 (second / 10 cc).

(Coating for back coat layer) ・ Kaolin (50% aqueous dispersion) 200 parts ・ Polyvinyl alcohol aqueous solution (10%) 60 parts ・ SBR latex (solid content 50%, Tg 0 ° C.) 100 parts ・ Melamine resin (solid 80%, Sumiretz Resin SR-613) 5 parts

Next, under layer coatings A to G (detailed in Table 1) having the following composition were applied to the other surface of the substrate using a wire bar, and the under layer having a dry coating amount of 10 g / m ^{2 was} applied. Is provided, the smoothness of the under layer is 1500 (seconds / 1
Calendar processing was performed so as to be about 0 cc). As shown in Table 1, the seven types of water-resistant supports obtained in this manner were used as support samples N in accordance with the coating amounts A to G, respectively.
o. 01-No. 07.

[0060]

[Table 1]

<Coating for under layer> Carbon black (30% aqueous dispersion) Clay (50% aqueous dispersion) SBR latex (solid content 50%, Tg 25 ° C.) Melamine resin (solid content 80%, Sumi Let's Resin SR
-613)

Each of the above components was mixed with the composition shown in Table 1 above, and water was added so that the total solid content became 25% to obtain coating solutions A to G for the under layer. 1) Specific electric resistance value of the under layer The specific electric resistance value of the under layer was measured as follows. Each of the underlayer coatings A to G was applied to a sufficiently degreased and washed stainless steel plate, and the applied amount was 10 g / m ² on a dry basis.
Was formed. With respect to the obtained seven types of samples, their intrinsic electric resistance values were measured by a three-terminal method provided with guard electrodes based on JIS K-6911. The results are shown in Table 2.

[0063]

[Table 2]

[Preparation of Lithographic Printing Precursor] 01-No. 07, an image receiving layer was provided so that the applied amount of the dispersion of the following composition after drying was 5 g / m ² after drying to prepare lithographic printing original plates. The surface smoothness of each master was in the range of 700 to 800 (sec / 10 cc), and the contact angle with water was 55 degrees.

<Coated product of image receiving layer> A composition having the following contents was put together with glass beads in a paint shaker (manufactured by Toyo Seiki Co., Ltd.) and dispersed for 10 minutes. Then, the glass beads were separated by filtration to obtain a dispersion. Was. Gelatin 10% aqueous solution 180 g Photocatalytic titanium powder: ST-01 (manufactured by Ishihara Sangyo Co., Ltd.) 45 g Colloidal silica 20% solution: Snowtec C 25 g (manufactured by Nissan Chemical Industries, Ltd.) Fluoroalkylester FC-430 ( 0.25 g Hardener 1.2 g CH ₂ = CHSO ₂ CH ₂ CONH (CH ₂ ) ₃ NHCOCH ₂ SO ₂ CH = CH ₂ water 100 g

Sample No. of the lithographic printing original plate prepared as described above. 1 to No. Plate making was carried out by using a laser printer using a dry toner: Xante Plate Maker-8200J using No.7. Subsequently, in the same manner as in Example 1, irradiation with ultraviolet light was performed at a distance of 20 cm for 3 minutes.
The contact angle between the non-image part and the water of the image part was 5 degrees and 90 degrees, respectively.

Next, the printing plate prepared as described above was used as a fountain solution using a fully automatic printing machine (AM-2850, trade name, manufactured by Am Co., Ltd.), and SLM-OD was distilled water. The 50-fold diluted solution was placed in a fountain solution pan, and printing was performed through a plate using a printing machine using black ink for offset printing. The image quality of the drawn image of the plate-making product thus obtained was evaluated as follows. Table 3 shows the results.

[0068]

[Table 3]

1) Image quality of plate making A drawing image of the plate making obtained was taken by an optical microscope for 200 hours.
It was observed and evaluated at a magnification of 1 ×. In the table, ◎, ○, △,
Display with ×. ◎ There is no problem in the drawn image and fine lines and fine characters are also very good. ○ There is no problem in the drawn image and fine lines and fine characters are also good. 微 Fine missing occurs in fine lines and fine characters. White spots on solid area

2) Printed Image The image of the obtained printed matter was evaluated in the same manner as in the plate making image quality, and the print image quality was exactly the same as the plate making image quality. 3) Printing durability The number of printed sheets was checked until the background contamination of the printed matter or the lack of the image could be visually discriminated.

Referring to the specific electric resistance values shown in Table 2, Table 3
Let us consider the result. In Examples 2 to 5 of the present invention, the underlayer had a specific electrical resistance of 10 ¹² to 10 ⁸ Ω · cm, and was composed of a support. The image had no problem, and fine lines and fine characters were good. . High printing durability. On the other hand, Comparative Examples A and 10 ⁴ Ω · c having specific electric resistances as large as 10 ¹⁴ Ω · cm or more.
In each of the masters of Comparative Examples B and C, which are as small as less than m, an image is missing or a solid portion is blank. That is, it shows that the plate making quality and the printing quality are good when the conductivity of the support underlayer immediately below the image receiving layer is within the predetermined range.

Example 6 <Preparation of a lithographic printing plate precursor> A composition having the following contents was added together with glass beads to a paint shaker (Toyo Seiki Co., Ltd.)
And dispersed for 5 minutes, and the glass beads were separated by filtration to obtain a dispersion. Photocatalytic titanium oxide sol 30% solution: STS-OZ 150 g (Ishihara Sangyo Co., Ltd.) Colloidal silica: Snowtec C 25 g Self-crosslinking acrylate latex 40% solution 20 g Nipol LX855 (Daicel Chemical Industries, Ltd.) Water 93 g

Using the water-resistant support used in Example 1, the above composition was applied thereon using a wire bar.
After drying at 0 ° C. for 60 minutes, an image receiving layer having a coating amount of 4 g / m ² was formed, and a lithographic printing original plate was obtained. The Beck smoothness of the surface layer was 850 (sec / 10 cc), and the contact angle with water was 75 degrees. Using this printing original plate, as in Example 1,
The plate was subjected to plate making, fixing, and ultraviolet irradiation treatment to form a printing plate, and offset printing was performed. The obtained printed matter had a clear image quality with no stain on the non-image area, similarly to the printing plate of Example 1, and had a good printing durability of 3,000 sheets or more.

Example 7 <Preparation of a lithographic printing plate precursor> A composition having the following contents was placed in a homogenizer disperser (manufactured by Nippon Seiki Co., Ltd.) and the number of rotations was set to 1
The mixture was dispersed at 10,000 rpm for 30 minutes to obtain a dispersion. Photocatalytic titanium oxide powder: ST-21 50 g Acrylic resin: Dianal LR-689 40% solution 40 g (manufactured by Mitsubishi Rayon Co., Ltd.) Acrylic resin particle dispersion having the following content 5 g (as solid content) methyl isobutyl ketone 210 g

(Acrylic resin particles) 8 g of acrylic acid,
AA-6 (trade name: methyl methacrylate macromonomer manufactured by Toa Gosei Chemical Co., Ltd.) 3 g, ethylene glycol dimethacrylate 2 g, methyl 3-mercaptopropionate 0.3 g, and methyl ethyl ketone 55 g were heated at a temperature under a nitrogen stream. Heated to 60 ° C. To this,
0.2 g of 2'-azobis (isovaleronitrile) was added and reacted for 3 hours.
Reacted for hours. The resulting dispersion had a conversion of 98%, the average particle size of the dispersed resin particles was 0.13 μm, and had good monodispersity (particle size measurement: CAPA-500 (trade name, manufactured by Horiba, Ltd.)) ).

This dispersion was treated with the sample No. of Example 4.
A lithographic printing plate precursor was obtained by coating the same water-resistant support as that used in Example 04 with a wire bar so as to give a coating amount of 5 g / m ² , followed by drying. The surface Beck smoothness of the obtained image receiving layer was 650 (sec / 10 cc), and the contact angle of the surface with water was 85 degrees. Using this printing original plate, plate-making and fixing were performed in the same manner as in Example 1 to obtain a plate-making plate.

Next, a 150 W xenon lamp was used on the entire surface of the plate-making master plate, and the light source was irradiated with light for 5 minutes from a distance of 10 cm. The contact angle with water on the non-image portion surface was 6 degrees, and that on the image portion surface was 95 degrees. This printing plate was prepared in Example 1
The offset printing was performed in the same manner as described above. The obtained printed material had a clear image quality with no stain on the non-image area, as in the printing plate of Example 1, and had a good printing durability of 3,000 sheets or more.

Example 8 <Preparation of a lithographic printing plate precursor> A composition having the following contents was added to a paint shaker (Toyo Seiki Co., Ltd.) together with glass beads.
And dispersed for 20 minutes, and the glass beads were separated by filtration to obtain a dispersion. Photocatalytic titanium oxide ST-01 45 g Polypropylene oxide-modified starch 18 g PENON HV-2 (manufactured by Nisseki Chemical Co., Ltd.) Alumina sol 24 g 24% glyoxal 40% solution 5 g Water 258 g

The dispersion was degreased to a thickness of 150
Using a wire bar on a μm aluminum plate, apply 11
Heat at 0 ° C. for 20 minutes. An image receiving layer having a coating amount of 3 g / m ² was formed to prepare a lithographic printing plate. The surface of the obtained image receiving layer had a Beck smoothness of 900 (sec / 10 cc) and a contact angle with water of 45 degrees. In the same manner as in Example 1,
When plate making, light irradiation, and printing were performed to make a printing plate and offset printing was performed, all of the obtained prints had clear image quality without stain on the non-image area, similarly to the printing plate of Example 1. The properties were as good as 3,000 sheets or more.

Example 9 A lithographic printing plate precursor was prepared in the same manner as in Example 8 except that a corona-treated 100 μm-thick PET film was used as the water-resistant support. Printing was performed in the same manner. The obtained printed material had a clear image quality with no stain on the non-image area, as in the printing plate of Example 8, and had a good printing durability of 10,000 sheets or more.

[0081]

According to the lithographic printing plate precursor of the present invention, the anatase type titanium oxide particles and the binder have a contact angle of 30 ° or more with water on the surface and a contact angle of 20 ° or less after irradiation with ultraviolet light. By having an image receiving layer containing a resin, a lithographic printing plate capable of printing a large number of clear, clear image quality prints without soiling can be obtained by dry desensitization treatment by irradiation with ultraviolet light. Further, the method of preparing a lithographic printing plate of the present invention makes it possible to perform simple image formation and dry desensitization treatment by irradiating ultraviolet light by using an electrophotographic recording method or the like for the lithographic printing plate precursor, and It is possible to obtain a lithographic printing plate which is excellent in property, has no background stain, and is capable of printing a large number of prints of clear images without any missing, distorted, or blurred images.

Claims (6)

[Claims] An image-receiving layer containing at least anatase-type titanium oxide particles and a binder resin on a water-resistant support, wherein the surface of the image-receiving layer has a contact angle with water of 30 ° or more, In addition, the contact angle with water on the surface after irradiation with ultraviolet light is 20
The lithographic printing plate precursor of the electrophotographic recording method, wherein the lithographic printing plate is not more than a degree. 2. The lithographic printing plate precursor according to claim 1, wherein the smoothness of the surface of the image receiving layer is 30 (sec / 10 cc) or more in Beck smoothness. 3. The electrophotographic lithographic printing plate according to claim 1, wherein the water-resistant support has an intrinsic electric resistance value of at least a portion immediately below the image receiving layer of 10 ¹³ Ω · cm or less. Original plate for printing. 4. A toner-colored image formed by an electrophotographic recording method on an image receiving layer of a lithographic printing plate precursor having an image receiving layer containing at least anatase-type titanium oxide particles and a binder resin on a water-resistant support. After forming the lithographic printing plate, irradiating the entire surface of the image receiving layer with ultraviolet light to convert the non-image portion into a hydrophilic surface state that does not accept the printing ink to form a lithographic printing plate. How to make. 5. The method according to claim 4, wherein the image formation using the electrophotographic recording method is performed using a liquid developer. 6. The lithographic printing plate according to claim 4, wherein the water-resistant support has an intrinsic electrical resistance of at least a portion immediately below the image receiving layer is 10 ¹³ Ω · cm or less. How to make.