JPH08267946A - Direct drawing type planographic printing original plate - Google Patents

Abstract

PURPOSE: To provide a direct drawing type planographic printing original plate excellent in desensitizing properties not generating not only background stains over an entire surface but also spot like background stains as an offset original plate and capable of obtaining printed matter of a sharp image free from printing stains even by the drawing from an electrophotographic copier of an electrostatic transfer system. CONSTITUTION: In a direct drawing type planographic printing original plate wherein an image receiving layer containing zinc oxide and a binder resin is provided on a water-resistant support, zinc oxide is composed of zinc oxide containing a specific aliphatic carboxylic acid group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct drawing type lithographic printing plate precursor, and more particularly to a direct drawing type lithographic printing plate precursor suitable for light printing.

[0002]

2. Description of the Related Art At present, a direct drawing type lithographic printing original plate having an image receiving layer on a support is widely used as an office printing original plate. In order to form a plate on such a printing original plate, that is, to form an image, a method of drawing an oil-based ink by hand on the image receiving layer, or a method of printing by a typewriter, an inkjet method, or a transfer type heat-sensitive method is generally used. . In addition, a method of transferring and fixing a toner image formed on a photoconductor to an image receiving layer through a process of charging, exposing and developing using a plain paper electrophotographic copying machine (PPC) has also started to be used in recent years. In any case, the printing original plate after plate making is subjected to surface treatment with a desensitizing solution (so-called etchant) to desensitize the non-image area, and then used as a printing plate for lithographic printing. In a conventional direct drawing type lithographic printing plate precursor, a surface layer was provided on both sides of a support such as paper with a back layer and an intermediate layer interposed. The back surface layer or the intermediate layer is composed of a water-soluble resin such as PVA and starch, a water-dispersible resin such as a synthetic resin emulsion, and a pigment. The surface layer is composed of a pigment, a water-soluble resin and a waterproofing agent.

A typical example of such a lithographic printing plate precursor for direct drawing is, as described in US Pat. No. 2,532,865, a water-soluble resin binder such as PVA, silica, an image receiving layer, and the like. It is composed mainly of an inorganic pigment such as calcium carbonate and a water-proofing agent such as a melamine-formaldehyde resin initial condensation product. Furthermore,
As a binder used in the image-receiving layer of a direct-drawing lithographic printing plate, it has a functional group capable of generating a carboxyl group, a hydroxyl group, a thiol group, an amino group, a sulfone group or a phosphono group upon decomposition, A resin that contains a functional group that cures and is pre-crosslinked is used (Japanese Patent Laid-Open No. 1-22).
6394, 1-269593, 1-28848.
No. 8), the above-mentioned functional group-containing resin is used in combination with a thermosetting / photocurable resin (JP-A-1-266546 and 1-275).
No. 191, No. 1-309068), the functional group-containing resin is used in combination with a crosslinking agent (Japanese Patent Laid-Open No. 1-267093).
No. 1-271292, No. 1-309067), it has been investigated to improve the hydrophilicity of the non-image area, the film strength of the image-receiving layer, and the printing resistance.

Further, in the image receiving layer, resin particles having a fine particle diameter of 1 μm or less containing a hydrophilic group such as a carboxyl group, a sulfo group and a phosphono group are contained together with an inorganic pigment and a binder (special feature: Kaihei 4-201387, 4-2
No. 23196), or fine resin particles containing a functional group that produces a hydrophilic group as described above by decomposition (Japanese Patent Laid-Open Nos. 4-319491 and 4-353).
No. 495, No. 5-119545, No. 5-58071
JP-A-5-69684) to improve the hydrophilicity of the non-image area.

On the other hand, zinc oxide is used in a direct-drawing type lithographic printing plate precursor in which zinc oxide is used as an inorganic pigment in the image-receiving layer and a non-image area is desensitized to form a printing plate after forming an image. As the above, zinc oxide produced by a wet method is used, and it is used in combination with zinc oxide produced by a dry method (JP-A-5-246166 and JP-A-5-254267).
Alternatively, by using zinc oxide containing a small amount of ferrocyan group (Japanese Patent Laid-Open No. 6-72058), a toner image can be sufficiently transferred to a printing original plate and printing stains can be obtained, especially when used in electrostatic transfer type plate making. It is being studied to suppress this.

[0006]

However, in the conventional printing plate thus obtained, in order to improve printing durability, the water-proofing agent is added in a large amount or a hydrophobic resin is used. When the hydrophobicity is increased, the printing durability is improved, but the hydrophilicity is lowered to cause printing stains. On the other hand, when the hydrophilicity is improved, the water resistance is deteriorated and the printing durability is deteriorated. Particularly, under a use environment at a high temperature of 30 ° C. or higher, the surface layer was dissolved in the immersion water used for offset printing, and there were drawbacks such as deterioration of printing durability and occurrence of printing stains. Further, in the case of direct drawing type lithographic printing, an oil-based ink or the like is drawn on the image-receiving layer as an image area.If the adhesion between the receiving layer of the printing original plate and the oil-based ink is not good, even if the non-image area is hydrophilic However, even if the above-mentioned printing stains do not occur, the problem that the oil-based ink in the image area is lost during printing, and as a result the printing durability is reduced, is still sufficiently solved. Not in.

Further, in recent high-resolution copy image formation by electrophotography using fine dry toner, for example, drawing by electrostatic transfer onto an image receiving layer by a racer printer or the like, especially non-image after transfer is performed. It is desired that both the prevention of the background stain of the image portion and the image reproducibility of the image portion be compatible with each other so that the obtained printed matter has a clear image without the background stain.

The present invention improves the above-mentioned problems of the conventional direct drawing type lithographic printing plate precursor. An object of the present invention is to provide, as an offset original plate, a direct drawing type lithographic printing original plate having excellent desensitizing property which does not cause spotwise background stain as well as uniform background stain. Another object of the present invention is to provide a direct-drawing lithographic printing plate precursor capable of obtaining a printed matter having a clear image without printing stain even by drawing from an electrophotographic copying machine by an electrostatic transfer system. is there.

[0009]

The above-mentioned object is to provide a direct-drawing type lithographic printing plate precursor having an image receiving layer containing zinc oxide and a binder resin on a water-resistant support, wherein the zinc oxide is a hydroxyl group. , A direct drawing type lithographic printing plate precursor comprising zinc oxide containing an aliphatic carboxylic acid group having at most 6 carbon atoms and containing at least one polar group selected from thiol group, amino group and carboxyl group Found out what was achieved by. The above-mentioned zinc oxide containing a specific aliphatic carboxylic acid (hereinafter referred to as carboxylic acid) group in the present invention means zinc oxide particles by chemically reacting zinc oxide particles with the carboxylic acid or the carboxylic acid salt. Part of that is chemically modified to zinc carboxylate.

The image receiving layer of the present invention mainly contains the carboxylic acid group-containing zinc oxide particles as described above, which makes it possible to use an electrophotographic copying machine or a heat-sensitive transfer system using a dry toner. In the image formation from the copier, a plate-free product with no missing images and stains in the non-image area can be obtained, and the printed matter offset-desensitized to form a printing plate is also clear without background stains. It is possible to obtain a clear image. The image receiving layer of the present invention is one in which the carboxylic acid group-containing zinc oxide particles are dispersed, and the surface thereof preferably has a Bekk smoothness of 30 to 120 (sec / 1.
0 cc), more preferably 40 to 100 (seconds / 10 c)
It is adjusted to the range of c). As a result, the scattering of toner in the non-image area or the stain due to ink adhesion does not pose a practical problem, and the adhesion of toner or ink in the image area is made uniform and sufficient, and the reproducibility of thin lines and fine characters and the uniformity of solid areas are improved. Will be good.

On the other hand, in the image receiving layer using the zinc oxide particles which have not been treated with the carboxylic acid, the non-image area is stained even within the above range of Beck's smoothness.
When observing the non-image area after plate making with a 200 × optical microscope, the number of scattered toner adhering per unit area is almost the same, but there is a large difference in the size of the adhering toner, which is larger than 15 μm. The number of toner particles of the present invention is remarkably reduced to about 60% or less as compared with the conventional one. As a result, the background stain is suppressed to a level that does not pose a practical problem. Furthermore, when a printing plate that has been subjected to a desensitizing treatment, which is the final purpose, is prepared and printed, the printing plate according to the present invention is sufficiently desensitized to a slight amount of scattered toner, and stains on non-image areas are more likely to occur. It is possible to provide a printed matter of an image which has few practical problems and has excellent reproducibility of fine lines and fine characters and uniformity of solid portions.

One of the main reasons for producing such excellent effects of the present invention is the effect of the shape of the surface of the image receiving layer of the present invention. That is, when the three-dimensional surface roughness measured by a stylus type surface roughness meter and the surface photograph by SEM were examined, it was found that the image receiving layer of the present invention was compared with the image receiving layer using zinc oxide not treated with carboxylic acid. The layer forms a surface state in which unevenness is high and the intervals are close. Specifically, it is defined by ISO-468. Surface center average roughness S
Ra is in the range of 1.36 to 2.0 μm, and the average wavelength Sλa indicating the density of surface roughness is in the range of 45 μm or less. It is presumed that this suppresses the adhesion of the scattered toner to the non-image area after electrophotographic plate making and the thickening of the adhered toner during fixing.

As another reason, when the contact angle of the image-receiving layer of the present invention with water is examined, the contact angle of the original plate made of untreated zinc oxide is 90 °, which is 70 ° or less and is extremely hydrophilic. Has an improved surface. This allows
During the desensitizing treatment for rapid treatment, the wettability of the film surface with the desensitizing treatment liquid is improved, and hydrophilic carboxylic acid groups are formed on the surface as compared with untreated zinc oxide particles having a hydrophobic surface. The modified particles of the present invention themselves have extremely improved hydrophilicity, and thus desensitization is likely to proceed sufficiently,
The non-image area is sufficiently hydrophilized. As described above, the image receiving layer of the present invention using the zinc oxide particles chemically treated with the carboxylic acid has a synergistic effect such that the surface shape is controlled in a specific state and the hydrophilicity is maintained. It becomes a direct drawing type lithographic printing plate precursor that can give good printed matter. The zinc oxide used for producing the carboxylic acid group-containing zinc oxide is described, for example, in "New Edition Pigment Handbook" edited by Japan Pigment Technology Association, page 319, Seibundou Co., Ltd. (1
968), any of those marketed as zinc oxide, zinc white, wet zinc white, or activated zinc white may be used. That is, depending on the starting material and the manufacturing method, zinc oxide is classified into a dry method, which is called a French method (indirect method), an American method (direct method), or a wet method. For example, Shodo Kagaku Co., Ltd., Sakai Chemical Co., Ltd. ), Hakusui Chemical Co., Ltd.,
Examples include those commercially available from companies such as Honjo Chemical Co., Ltd., Toho Zinc Co., Ltd., and Mitsui Kinzoku Kogyo Co., Ltd.
It is preferable to use the zinc oxide obtained by the wet method because the background fog is further reduced.

The carboxylic acid used in the present invention may be either itself or the carboxylic acid salt. Examples of the carboxylic acid include aliphatic carboxylic acids having 6 or less carbon atoms and containing at least one polar group selected from a hydroxyl group, a thiol group, an amino group and a carboxyl group. That is, formic acid, propionic acid acetate, acetic acid, valeric acid,
Alkane carboxylic acids such as caproic acid and propene carboxylic acids, butene carboxylic acids, pentene carboxylic acids, in alkene carboxylic acids such as hexene carboxylic acid, the above-mentioned as a substituent, a compound containing at least one polar group, further , May contain other substituents. Other substituents include, for example, halogen atoms (fluorine, chlorine,
(Bromine, iodine), alkyl group having 1 to 3 carbon atoms, 1 carbon atom
~ 4 alkoxy group (methoxy group, ethoxy group, propoxy group, butoxy group), cyano group, formyl group, alkyl group-substituted carboxylic acid ester group having 1 to 40 carbon atoms (eg, methoxycarbonyl group, ethoxycarbonyl group, etc.) , An alkylthiol group (methylthiol group, ethylthiol group, etc.), an acyl group (eg, acetyl group, propionyl group, etc.), an alkanesulfonyl group (eg, methanesulfonyl group, etc.), an amide group and the like.

More specifically, polybasic acids (eg, oxalic acid, malonic acid, succinic acid, glutaric acid, glutaconic acid,
Adipic acid, maleic acid, acetylenedicarboxylic acid, itaconic acid, fumaric acid, muconic acid, carboxymethylmercaptopropionic acid, fluorosuccinic acid, chlorosuccinic acid, dichlorosuccinic acid, methylsuccinic acid, dimethylsuccinic acid, chloromaleic acid, dichloromaleic acid , Methylmaleic acid, dimethylmaleic acid, methylmercaptomaleic acid, cyanomalonic acid, carboxymethylsuccinic acid, methoxycarbonylethylsuccinic acid, 3-methylglutaric acid, etc., oxycarboxylic acids (eg glycolic acid, lactic acid, hydroacryl) Acid, oxybutyric acid, glyceric acid, tartronic acid, malic acid, tartaric acid, citric acid,
Gluconic acid, galactaric acid, mandelic acid 3,4-dihydroxybutyric acid, etc.), aminocarboxylic acids and their derivatives (eg, glycine, alanine, valine, leucine, isoleucine, serine, threonine, cysteine, cystine, methionine, aspartic acid, glutamic acid) , Lysine, arginine, N- (2-carboxyethylcarbamoyl) serine, aminobutyric acid, etc.), thioglycolic acid,
Examples thereof include mercaptopropionic acid and 3,4-dimercaptobutyric acid. The carboxylic acid used in the present invention is not limited to these specific examples. These compounds may be used alone or in combination of two or more. When two or more kinds are mixed and used, as a result, 1 × 10 ⁻⁴ mol (per 100 g of zinc oxide) or less is used.

The carboxylic acid of the present invention may be used as a salt, and specific salts include inorganic salts (eg salts of lithium, sodium, potassium etc.), ammonium salts,
Alternatively, salts with organic bases (eg, primary amine, secondary amine or tertiary amine (as the hydrocarbon group, for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group , A cyclohexyl group, a cyclooctyl group, a benzyl group, a phenethyl group and the like, and these hydrocarbon groups may have a substituent such as a hydroxy group, a halogen atom, a cyano group, an alkoxy group and an amide group) , Anilines (eg aniline,
N-methylaniline, N, N-dimethylaniline, N-
Ethylaniline, N-butylaniline, N-methyl-N
-Butylaniline, etc.) or a heteroatom-containing cyclic nitrogen compound (eg, pyridine, morpholine, piperazine, pyridine, etc.)]. In the case of a polybasic acid, some or all of these salt compounds may be salts, and the salts formed may be the same or different. Alternatively, in the present invention, when the zinc oxide surface is modified as described below, the carboxylic acid may be used as a corresponding carboxylic acid anhydride.

The content of the carboxylic acid group contained in the zinc oxide is 1.0 × 10 ^-4 mol to 1.0 × 10 ^-1 mol of the carboxylic acid group per 100 g of zinc oxide. preferable. This range is suitable for obtaining a printed product consisting of the image portion of a clear copy image and the non-image portion free of background stain. It is more preferably 2.0 × 10 ^{−4 to} 5.0 × 10 ⁻² mol.

The carboxylic acid group-containing zinc oxide of the present invention is prepared by dispersing zinc oxide powder in a dispersion medium in which the carboxylic acid, carboxylic acid salt or carboxylic acid anhydride is preferably dissolved, and then subjecting to acidic conditions. It is obtained by adding and mixing a predetermined amount of the compound of the present invention below. Zinc oxide is produced on the surface of the zinc oxide fine particles by the interfacial reaction with protons, which rapidly causes a chelate reaction with the carboxylate ion, and because this chelate compound is insoluble in the dispersion medium, it is rapidly precipitated and fixed on the fine particle surface, It is considered that the surface portion of the present invention becomes chemically modified acidic zinc particles, or that the carboxylic acid anhydride is adsorbed on the zinc oxide surface and chemically reacts with zinc oxide to form the chelate compound on the surface.
Basically, the amount of chelate can be easily controlled by adjusting the amount of protons present in the dispersion system together with the amount of zinc oxide / carboxylic acid.

Further, the dispersion medium in which zinc oxide is dispersed and the dispersion medium in which carboxylic acid is dissolved do not necessarily have to be dissolved,
That is, even in a heterogeneous system, the same treatment can be performed if both are dispersed in a microscopic state by a disperser. Specifically, after dispersing the zinc oxide powder with a dispersion medium under acidic conditions using the conventionally known wet dispersion medium with the carboxylic acid or its acid salt,
The dispersion can be collected by centrifugation or the like, washed thoroughly with water, and then dried to obtain a desired powder. At this time, in order to improve or adjust the dispersibility of the zinc oxide powder, it is preferable to use a conventionally known dispersant together. Alternatively, as described above, the carboxylic acid-treated dispersion is added to the binder resin of the image-receiving layer without further separation and isolation, and further added, and redispersed to prepare the image-receiving layer application process. A method of preparing a dispersion and coating it on a support, or zinc oxide, a binder resin and other additives are previously dispersed together with a dispersion medium, and then a predetermined amount of the carboxylic acid, its salt or acid anhydride is added. Examples thereof include a method of mixing and mixing to prepare a coating dispersion and coating the dispersion on the support, but the present invention is not limited thereto.

A binder resin used for the image receiving layer of the present invention;
Is all known as conventional binder resin
Is available. A typical one is vinyl chloride-vinyl acetate.
Copolymer, styrene-butadiene copolymer, styrene-
Methacrylate copolymer, methacrylate copolymer,
Crylate copolymer, vinyl acetate copolymer, polyvinyl
Butyral, alkyd resin, silicone resin, epoxy
Resin, epoxy ester resin, polyester resin, etc.
Polyvinyl alcohol as a water-soluble polymer compound
Polyvinyl alcohol, starch, oxidized starch, carboxy
Methyl cellulose, hydroxyethyl cellulose, cold
In, gelatin, polyacrylate, polyvinylpyrroli
Don, polyvinyl ether-maleic anhydride copolymer,
Examples thereof include polyamide and polyacrylamide. this
These resins may be used alone or in combination of two or more kinds.
Good. Molecular weight of the binder resin used in the image receiving layer of the present invention
Is preferably 10³-10 ⁶, And more preferably 5 × 1
0³~ 5 × 10^FiveIs. Also, the glass transition of this resin
The point is preferably −10 ° C. to 120 ° C., more preferably 0.
C to 90C. The image receiving layer of the present invention has the above
Other constituents may be contained together with the constituents.

In addition to the surface-modified zinc oxide used in the present invention as another component that may be contained, examples of the inorganic pigment include zinc oxide, kaolin clay, calcium carbonate, barium carbonate, calcium sulfate, and the like. Examples thereof include barium sulfate, magnesium carbonate, titanium oxide, silica and alumina. Among these inorganic pigments, when zinc oxide is used in combination, it can be used in a proportion of preferably 10 to 90 parts by weight with respect to 100 parts by weight of the surface-modified zinc oxide of the present invention. It is more preferably 20 to 80 parts by weight.
Alternatively, when another inorganic pigment is used in combination, it can be used within a range not exceeding 20 parts by weight with respect to the surface-modified zinc oxide of the present invention. Furthermore, in order to improve the desensitization of the image-receiving layer, JP-A-4-201387 and 4-223196 are incorporated.
No. 4, No. 4-319491, No. 5-58071, No. 4
Resin particles containing a specific functional group described in JP-A-353495 and JP-A-5-119545 may be contained. By using these other inorganic pigments or resin particles within the above-mentioned range of use, desensitization of the non-image area (hydrophilicity) by the desensitization treatment is sufficiently performed, and the background stain of the printed matter is suppressed, and The image portion is sufficiently adhered to the image receiving layer, and sufficient printability can be obtained without causing image defects even when the number of printed sheets increases.

The ratio of pigment / binder resin in the image receiving layer is
Generally, the binder resin is 10 to 2 with respect to 100 parts by weight of the pigment.
The proportion is 5 parts by weight, preferably 13 to 22 parts by weight. Within this range, the effect of the present invention is effectively exhibited, and the film strength is maintained during printing or high hydrophilicity is maintained during desensitizing 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, a crosslinking agent is used together to cure the film,
It is preferable to improve water resistance.

Examples of the cross-linking agent include compounds that are usually used as cross-linking agents. Specifically, Shinzo Yamashita and Tosuke Kaneko, "Handbook for Crosslinking Agents," published by Taiseisha (19
81), edited by The Society of Polymer Science, "Polymer Data Handbook,
The basic compounds described in "Baifukan (1986)" and the like 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) Coupling agents, etc.), polyisocyanate compounds (for example, toluylene diisocyanate, diphenylmethane diisocyanate, triphenylmethane triisocyanate, polymethylene polyphenyl isocyanate, hexamethylene diisocyanate, isophorone diisocyanate, high Molecular polyisocyanate, etc.), polyol compound (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 (e.g. tetrabutoxy titanate, tetrachloroepoxy titanate, isopropyl tristearoyl titanate etc.), aluminum coupling compounds (e.g. aluminum butyrate, aluminum acetylacetate). , Aluminum oxide octate, aluminum tris (acetylacetate), etc., polyepoxy group-containing compounds and epoxy resins (for example, "New epoxy resin" edited by Hiroshi Kakiuchi)
"Epoxy Resins" edited by Shokoido (1985), Kuniyuki Hashimoto, compounds listed in Nikkan Kogyo Shimbun (1969), melamine resins (for example, "Yuria Melamine Resin", edited by Ichiro Miwa and Hideo Matsunaga) Kogyo Shimbun (196
9)), poly (meth) acrylate compounds [eg, Shin Okawara, Takeo Saegusa, Toshinobu Higashimura, "Oligomer" Kodansha (1976), Eizo Omori, "Functional Acrylic Resins" Compounds described in Techno System (published in 1985) and the like.

In the present invention, a reaction accelerator may be added, if necessary, in order to accelerate the crosslinking reaction in the image receiving layer. When the crosslinking reaction is a reaction mode in which a chemical bond between functional groups is formed, 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 (acetylacetonate zirconium salt, acetylacetone zirconium salt, acetylacetocobalt salt, dibutoxytin dilaurate, etc.), dithiocarbamic acid compounds (diethyldithiocarbamate, etc.) ), Tinoulam disulfide compound (tetramethyltinourum disulfide, etc.), carboxylic acid anhydride (phthalic anhydride, maleic anhydride, succinic anhydride, butylsuccinic anhydride,
3,3 ′, 4,4′-tetracarboxylic acid benzophenone dianhydride, trimellitic acid anhydride, etc.) and the like.
When the crosslinking reaction is a polymerizable reaction mode, a polymerization initiator (peroxide, azobis compound, etc.) may be used.

The binder resin is preferably cured by light and / or heat after applying the image receiving layer composition. In order to carry out heat curing, for example, the drying conditions are made stricter than the conventional drying conditions for preparing the receiving layer. 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, 60 ℃
Process at -150 ° C for 5-120 minutes. When the above reaction accelerator is used in combination, the treatment can be performed under milder conditions.

As a method of curing the specific functional group in the resin by irradiation with light, a step of irradiating with light of chemically active light may be included. The chemical actinic ray may be any of visible ray, ultraviolet ray, far ultraviolet ray, electron beam, X-ray, γ ray, α ray, etc., but is preferably ultraviolet ray, more preferably light ray in the wavelength range of 310 nm to 500 nm. . Generally, low-pressure, high-pressure or ultra-high-pressure mercury lamps,
The light irradiation process, which uses a halogen lamp, is usually 5
Irradiation for 10 seconds to 10 minutes from the distance of 50 cm to 50 cm is sufficient.

The image receiving layer of the present invention is provided on a water resistant support. As the water-resistant support, water-resistant paper, plastic film, paper laminated with metal foil, plastic film, or the like can be used. In the present invention, an intermediate layer is provided between the support and the image receiving layer for the purpose of improving water resistance and interlayer adhesion, and a back coat layer (back surface layer) is provided on the support surface opposite to the image receiving layer for the purpose of preventing curling. ) Can be provided. Here, the intermediate layer is an emulsion type resin such as an acrylic resin, an ethylene-butadiene copolymer, a methacrylic acid ester-bucadiene copolymer, an acrylonitrile-butadiene copolymer, an ethylene-vinyl acetate copolymer; an epoxy resin, a polyvinyl butyral. , Solvent-type resins such as polyvinyl chloride and polyvinyl acetate; at least one of the above water-soluble resins and the like
Although it is composed mainly of seeds, an inorganic pigment or a water-proofing agent can be added if necessary. The structure of the back coat layer is almost the same as that of the intermediate layer.

When used as an electrophotographic plate,
In order to further reduce the background stain of the printing original plate of the present invention, the image receiving layer as the printing original plate has a volume resistivity of 10 ⁸ to 1 1.
A conductive agent can be added to the image receiving layer, the intermediate layer and / or the back coat layer so as to obtain 0 ¹³ Ωcm. The conductive agent may be either an inorganic type or an organic type, and may be used alone or in combination of two or more kinds.
Examples of inorganic materials include 1 such as Na, K, Li
Valous metal salts, Mg, Ca, Ba, Zn, Ti, Co, N
Examples thereof include salts or oxides of polyvalent metals such as i, Zr, Al and Si, and ammonium salts. The organic compound may be a low molecular weight compound or a high molecular weight compound, and examples thereof include compounds conventionally used as a conductive agent, an antistatic agent or a surfactant. For example, metal soap (for example, metal salt of organic carboxylic acid, sulfonic acid, phosphonic acid, etc.), quaternary salt compound (quaternary ammonium salt, phosphonium salt, etc.), anionic surfactant, nonionic surfactant, cationic surfactant , Known compounds such as alcohol compounds (for example, crystalline compounds such as acetylene-1,2-diolxylylenediol and bisphenol A) can be used alone or in admixture of two or more.

The amount of these conductive agents added is 3 to 40% by weight, preferably 5 to 20% by weight of the amount of binder used in each layer.
% By weight. In order to prepare the direct drawing type lithographic printing plate precursor of the present invention, generally, a solution containing an intermediate layer component is applied and dried on one surface of a support to form an intermediate layer, and then an image receiving layer component is contained. The solution may be applied and dried to form an image receiving layer, and if necessary, a solution containing a backcoat layer component may be applied and dried on the other surface to form a backcoat layer. Incidentally image receiving layer, an intermediate layer, the coating amount of the backcoat layer are each 1 to 30 g / m ^2, in particular 6~20g / m ² is suitable.

A printing plate using the direct drawing type lithographic printing plate precursor of the present invention is prepared by forming and fixing an image on the direct drawing type lithographic printing plate precursor having the above-mentioned structure by a known technique to prepare a plate.
The non-image area is desensitized by surface-treating it with a desensitizing solution. Desensitization of zinc oxide has hitherto been carried out as a desensitizing treatment liquid of this type, as a ferrocyanine salt, a cyanide-containing treatment liquid containing a ferricyanide as a main component, an amminecobalt complex, phytic acid and its derivatives, and a guanidine derivative. There are known cyan-free treatment liquids containing as a main component, treatment liquids containing inorganic acids or organic acids that form chelates with zinc ions as main components, treatment liquids containing a water-soluble polymer, and the like. For example, as a cyanide-containing treatment liquid, JP-B-44-9045, JP-A-46-39403, JP-A-52-76101, JP-A-57-107889, and JP-A-54-107489.
The thing described in each gazette, such as -117201, is mentioned.

As the phytic acid compound-containing treatment liquid,
JP-A Nos. 53-83807, 53-83805, 53-102102, 53-109701 and 5
No. 3-127003, No. 54-2803, No. 54-4
Those described in Japanese Patent No. 4901 and the like are listed. Examples of the treatment liquid containing a metal complex compound such as a cobalt complex include those described in JP-A-53-104301, JP-A-53-140103, JP-A-54-18304 and JP-B-43-28404. As the treatment liquid containing an inorganic or organic acid, Japanese Patent Publication No. 39-13702 and 40-103.
No. 08, No. 43-28408, No. 40-26124
And Japanese Patent Application Laid-Open No. 51-118501. As the guanidine compound-containing treatment liquid,
Examples thereof include those described in JP-A-56-111695. Treatment solutions containing a water-soluble polymer include those disclosed in JP-A-52-126302, JP-A-52-134501 and JP-A-52-134501.
No. 3-49506, No. 53-59502, No. 53-1
No. 04302, Japanese Patent Publication No. 38-9665, 39-22
No. 263, No. 40-763, No. 40-2202, and JP-A-49-36402.

In any of the above desensitizing treatments,
Zinc oxide in the surface layer is ionized to zinc ions,
It is considered that these ions cause a chelation reaction with a compound forming a chelate in the desensitizing treatment liquid to form a zinc chelate, which is deposited in the surface layer to be hydrophilized.

[0034]

The present invention will be described in detail below with reference to examples, but the contents of the present invention are not limited thereto. Example 1 100 g of dry zinc oxide (SAZEX-2000: trade name manufactured by Sakai Chemical Industry Co., Ltd.), 3.2 g of a binder resin (A-1) having the following structure, and 12.8 g of a binder resin (A-2). ,
A mixture of 10 g of an aqueous solution of 4 g of oxalic acid and 174 g of toluene was homogenized with a homogenizer (manufactured by Nippon Seiki Co., Ltd.) at a rotation speed of 7 × 10 ³ r. p. m. For 5 minutes to obtain a composition for an image receiving layer.

Binder resin A-1

Embedded image

Binder resin A-2

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A support of ELP-1 type master [trade name of Fuji Photo Film Co., Ltd.] used as an electrophotographic lithographic printing original plate for light printing was used, and the above composition was applied thereto with a wire bar. And then dried at 100 ° C. for 1 minute to form an image receiving layer having a coating amount of 12 g / m ² to obtain a direct drawing type lithographic printing original plate.

Comparative Example 1 A direct drawing type lithographic printing plate precursor was prepared in exactly the same manner as in Example 1 except that the oxalic acid 4.0 used in Example 1 was omitted.

(Comparative Example 2) In Comparative Example 1, Example 1
A direct drawing type lithographic printing original plate was prepared in the same manner as in Comparative Example 1 in which the dispersion conditions were adjusted so that the Bekk smoothness of the surface of the original plate prepared in 1. was almost the same. Using each of the printing original plates of Example 1 and Comparative Examples 1 and 2 prepared as described above, a plate was prepared by a laser printer using a dry toner as described below, and desensitized to obtain a printing plate. When it was created and printed, the results shown in Table 1 were obtained.

[0040]

[Table 1]

The evaluation items shown in Table-1 are as follows. Note 1) Smoothness of image receiving layer: The smoothness (second / 10 cc) of the printing original plate was measured using a Beck's smoothness tester (manufactured by Kumagai Riko Co., Ltd.) under the condition of an air capacity of 10 cc.

Note 2) Three-dimensional surface roughness: A printing original plate is measured by a three-dimensional roughness measuring device (SE-3FK, Kosaka Laboratory Ltd. trade name) and a three-dimensional roughness analyzing device (SPA-11, (stock). The three-dimensional surface roughness was measured under the following conditions using a) manufactured by Kosaka Laboratory. Measurement conditions Measurement length X-axis: 2.5 mm, Y-axis: 0.4 mm Axial sampling pitch: 0.05 μm With inclination correction, without cut-off Measured value Surface / center average roughness: SRa (μm) Average wavelength: Sλa (μm ) These measurements follow the standard of ISO-468, and specifically, for example, Jiro Nara "Measurement and evaluation method of surface roughness"
It is described in detail in General Technology Center Co., Ltd. (published in 1983).

Note 3) Surface wettability 2 μl of distilled water was placed on the surface of the printing original plate, and the surface contact angle (degree) after 30 seconds was measured by a surface contact angle meter [CA-D, a product of Kyowa Interface Science Co., Ltd. Name]. The lower this value, the better the wettability with water and the hydrophilicity.

Note 4) Plate-making image quality The printing original plate is subjected to AM-Straight Imaging.
Commercially available as System: Laser printer using dry toner (AMSIS 1200-J
The copied image of the plate-making product obtained through the Plate Setter-trade name-) was visually evaluated using a 20-fold loupe.

Note 5) Image quality of printing After making a printing original plate by the same operation as that of Note 4), a desensitizing treatment liquid (SICS, manufactured by Japan AM Co., Ltd.) was applied to a fully automatic printing machine (AM-2850, Put it in the etcher part of AM Co., Ltd.) and use it as the dampening water, which is a desensitizing solution (SICS) diluted 4 times with distilled water, and put it in the dampening water pan to perform offset printing. Use black ink,
Printing was performed by passing the plate through the printing machine. Printed image of the 10th printed matter (background fog, solid image uniformity)
Was visually evaluated using a 20-fold loupe.

Note 6) Printing durability Printing was performed in the same manner as in Note 5) above, and the number of printed sheets was checked until it was possible to visually determine the background stain of the printed matter or the lack of the image.

As shown in Table 1, in Comparative Example 1 obtained in the image receiving layer of each original plate provided on the same support under the same dispersion conditions as the original plate of the present invention, the smoothness of the original plate was There was a significant difference in the smoothness. Further, as described above in Comparative Example 2, the dispersion conditions had to be adjusted in order to obtain Beck smoothness equivalent to that of the original plate of the present invention. It is considered that this is because the dispersibility of the zinc oxide particles is different. Further, when the surface roughness of each of these original plates is examined and seen, the Beck smoothness is equivalent from the numerical values of the central average roughness SRa representing the size of the surface irregularities and the average wavelength Sλa serving as a guide for the intervals of the irregularities. The original plate of the present invention and the original plate of Comparative Example 2 have almost the same SRa, but there is a large difference in Sλa, and the one of the present invention densely forms irregularities.

When the wettability of the surface layer was measured by the contact property with water, the value of the present invention was low and the hydrophilicity was high. On the other hand, the surfaces of Comparative Examples 1 and 2, which were mainly zinc oxide without surface treatment, had a high contact angle. Next, offset printing was carried out as a printing plate on which the original plate was actually made and the surface was not subjected to desensitization treatment, and the results were compared and examined.Only the original plate of the present invention showed good plate making image quality and printing image quality. It was That is, the plate-making product of the present invention obtained by dry-type toner transfer from a laser printer has no thin lines and fine characters missing, the solid part is uniform, and the unevenness of toner transfer is not recognized at all, and the non-image part is also not present. However, the background fog caused by the toner scattering was also slight, and it was good without any practical problems.

On the other hand, in the plate-making product of Comparative Example 1 using the wet zinc oxide which was not surface-treated, a slight unevenness was generated in the solid image portion, and the background fog in the non-image portion was increased, which was a practical level. Did not reach. In Comparative Example 2 having the same Beck's smoothness, the transferred image portion (reproducibility of thin lines / fine characters and solid uniformity) was good, but fog in the non-image portion was Comparative Example 1. It deteriorated more and became significantly more.

Next, the plate-making product was subjected to a desensitizing treatment to obtain a printing plate, and the performance of the printing plate was evaluated. As a result, only the printing plate according to the present invention was found to have fine lines and fine characters and uneven solid areas. It provided 3,000 or more good prints having no image and no practical problems with ink stains on the non-image area. On the other hand, in Comparative Examples 1 and 2, the background stain of the non-image area was generated from the printing, and it did not change even after printing 3000 sheets.

From these results, it is considered that there is a close relationship between the characteristics of the image receiving layer caused by the zinc oxide particles provided and the image performance in plate making / printing. That is, the zinc oxide whose surface was partially chemically modified by the carboxylic acid used in the present invention has a particle size distribution that is comparable to that of untreated zinc oxide from the results of the dispersion conditions for preparing the image-receiving layer dispersion. It is possible to obtain a uniformly uniform and dense surface irregularity. On the other hand, the oxidized particles that have not been surface-modified with the carboxylic acid cannot form the surface state as described above, and have a tendency of toner scattering to the non-image area during toner transfer and transfer from the printer. It is thought that it became remarkable.

Although the Beck's smoothness is almost the same, as can be seen from the three-dimensional surface roughness, the original plate of the present invention has
The unevenness is formed in a dense state. Further, when the non-image area of the non-image area after plate making was observed under an optical microscope of 200 times, the number of scattered toner areas of the background area was 1 unit area (1 mm ² ). The number of toner particles is the same as 15, but when the number of toner particles having a size of 15 μm or more is examined, the number of toner particles of the present invention is as small as 0 to 1, while that of Comparative Example 2 is extremely large at 4 to 5. Was becoming.

From these facts, when the original plate of the present invention was made into a plate, the toner particles were prevented from sticking to the non-image and the toner particles were prevented from becoming thick even when fixing with the heating roller, and as a result, they were visually observed. It is thought that it had a great influence on the bad dirt of the time. Further, the difference in the background stain of Example 1 and Comparative Example 2 in the printed matter corresponds to the size of the scattered toner on the plate-making product, and small scattered toner of 15 μm or less is hydrophilized during the desensitizing treatment, but is coarse. The toner of particles remains, causes ink stains, and further, the surface of the present invention is improved in hydrophilicity because the surface of the hydrophobic zinc oxide is modified to be hydrophilic. It is considered that the wettability of the composition was remarkably improved, and even in the desensitizing treatment in which the rapid treatment is performed, it was easily and sufficiently hydrophilized. As described above, only the printing original plate of the present invention can provide a good printed matter.

(Example 2) 100 g of wet zinc oxide [AZO: trade name of Shodo Kagaku Co., Ltd.], dispersant [CALIBON L]
-400, trade name of Sanyo Kasei Co., Ltd.] 1 g and a mixture of 150 g of an aqueous solution prepared by dissolving 5.5 g of gluconic acid and adjusting the pH to 4.0 with aqueous ammonia, using a Dynomill disperser, a rotation speed of 3 × 10 ³ r. p. m. After dispersing for 30 minutes, the glass beads were filtered off. To this dispersion, 15 g (as solid content) of an acrylate emulsion [AE932, trade name of Nippon Synthetic Rubber Co., Ltd.] was added as a binder resin, and a homogenizer was used to produce 1 × 10 ³ r.p. p. and further dispersed for 1 minute to prepare an image receiving layer composition. As the support, A. M-Straight Imaging Ma
A water-resistant treated paper support used for sterSIM (trade name, manufactured by Japan AM Co., Ltd.) is used, and the above composition is applied thereto using a wire bar.
After drying at 0 ° C. for 1 minute, an image receiving layer having a coating amount of 10 g / m ² and a Beck's smoothness of 58 (sec / 10 cc) was provided.

This printing original plate was processed in the same manner as in Example 1.
Plate-making, desensitizing treatment was performed to obtain a printing plate, and offset printing was performed. The obtained printed matter had a clear image quality with no stains on the non-image areas, as in Example 1, and had a good printing durability of 3000 sheets or more. Further, the plate-making image obtained by making a plate using a thermal transfer type printer [Write Movel, a product name of Kanto Electronics Co., Ltd.] has a small amount of ink transfer from the ink ribbon to the non-image area, which is a practical problem. It was not enough. Further, similarly to the above, a desensitizing treatment with a processing solution of SICS was performed to obtain a printing plate, and offset printing was performed. The obtained printed matter had a slight non-image stain, which was not a problem in practical use, and the image portion was free of fine lines and fine characters. 1000 or more such good prints were obtained.

(Example 3) Wet zinc oxide (AZO) 10
0 g, dispersant [Demol EP, trade name manufactured by Kao Corporation]
A mixture of 150 g of an aqueous solution in which 1.5 g (as solid content) and 6 g of oxalic acid was dissolved and pH was adjusted to 4.0 with aqueous ammonia was added to 150 g of glass beads having a diameter of 0.7 to 1 mm.
Also, using a Dynosil disperser, the rotation speed was 6 × 10
³ r. p. m. After 15 minutes of dispersion, the glass beads were filtered off. The precipitate was collected by a centrifuge, washed thoroughly with water, and dried under reduced pressure to obtain 90 g of a solid powder.

A mixture of 60 g of the above treated zinc oxide, 40 g of zinc oxide (AZO), 1.2 g of demole EP (as solid content) and 150 g of water was added to a diameter of 0.7 to 1 mm.
With 150 g of glass beads of No. 3 in a Dynomill disperser at a rotation speed of 3 × 10 ³ r. p. m. After dispersing for 30 minutes with the glass beads, the glass beads are filtered off, and the dispersion is further used as a binder resin in an acrylic emulsion [Sevian-A4648].
8, trade name of Daicel Chemical Industries, Ltd.] 15 g (as solid content) was added, and the mixture was stirred at 1 × 10 ³ r. p.
m. And stirred for 1 minute to prepare an image receiving layer dispersion.

This is the same SIM as used in the second embodiment.
Apply on a paper support using a wire bar,
After being dried for 1 minute, the coating amount is 12 g / m ² and Beck's smoothness is 7
An image receiving layer of 5 (sec / 10 cc) was formed. This printing original plate was subjected to plate making, desensitizing treatment to obtain a printing plate and offset printing in the same manner as in Example 1. The obtained printed matter had a clear image quality with no stains on the non-image areas, as in Example 1, and had a good printing durability of 3000 sheets or more.

Example 4 A mixture of 100 g of dry zinc oxide (manufactured by Shodo Kagaku Co., Ltd.), 1 g of sodium polystyrene sulfonate, 10 g of malic acid, and 140 g of water was adjusted to pH 3.0 with a 0.1 N hydrochloric acid aqueous solution. After that, the mixture was homogenized with a homogenizer disperser (manufactured by Nippon Seiki Co., Ltd.) at a rotation speed of 1 × 10 ³ r. p. m. After 5 minutes of dispersion, immediately add 10% aqueous sodium hydroxide to the pH of this dispersion.
Was neutralized to 7.0. The dispersion was centrifuged with a centrifuge to precipitate zinc oxide particles, the precipitate was taken out by decantation, washed thoroughly with water, and the granular material was dried under reduced pressure to obtain 190 g of a white powder. The content of carboxylic acid group in 100 parts by weight of zinc oxide obtained from the result obtained by measuring Zn / ratio of this powder by fluorescent X-ray analysis was 7.0 × 10 ^-2 mol. , Indicates that the reaction has proceeded.

<Preparation of printing original plate> A mixture of 100 g of the above-treated zinc oxide, 12 g of the binder resin (A-3) having the following structure, 3 g of the binder resin (A-4) and 250 g of toluene was rotated with a homogenizer disperser. Number 7 × 10 ³ r. p.
m. For 7 minutes to obtain a composition for an image receiving layer. This dispersion was coated on the SIM support with a wire bar, heated at 110 ° C. for 30 seconds and dried to obtain a coating amount of 1
An image receiving layer having a Beck's smoothness of 60 (seconds / 10 cc) was formed at ² g / m ² .

Binder resin A-3

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Binder resin A-4

[Chemical 4]

This printing original plate was processed in the same manner as in Example 1.
Plate-making, desensitizing treatment was performed to obtain 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, and had a printing durability of 3 as in Example 1.
The number was as good as 000 sheets or more.

(Example 5) Wet zinc oxide (AZO) 30
g, dry zinc oxide (SAZEX-2000) 70 g, sodium polystyrene sulfonate 1 g, and tartaric acid 6 g were dissolved, and the pH was adjusted to 4.0 with aqueous ammonia solution 13
After dispersing 0 g in the same manner as in Example 3, the dispersion was collected by filtration. Acrylic emulsion (AE93
2) Add 14 g (as solid content) and 50 g of water and add 1
× 10 ³ r. p. m. And stirred for 1 minute to prepare a dispersion for the image receiving layer. This dispersion was coated on a SIM paper support with a wire bar and dried at a temperature of 100 ° C. for 10 minutes to give a coating amount of 12 g / m ² and a Beck smoothness of 65 (seconds / 10 cc).
The image receiving layer of was formed. This printing original plate was subjected to plate making in the same manner as in Example 1 and subjected to desensitization treatment to obtain a printing plate, which was subjected to offset printing. As a result, 3000 or more printed products with clear image quality without stains on non-image areas were obtained. It was Further, in the same manner as in Example 2, a printing plate was prepared by making a plate with a thermal printer, and when printing was performed, 1000 or more prints having clear image quality with no stain on the non-image area were obtained.

Example 6 100 g of surface-treated zinc oxide used in Example 4 and a binder resin (A-5) having the following structure
14 g, 1.5 g of acrylic resin particle dispersion having the following contents
A mixture of (as solid content) and 230 g of toluene,
Rotation speed 7 × 10 ³ with homogenizer disperser. p. m.
Dispersed for 7 minutes.

Binder resin A-5

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Acrylic acid resin particle dispersion A mixed solution of 10 g of acrylic acid, 2 g of AA-6 (trade name of Toagosei Co., Ltd .: macromonomer of methyl methacrylate) and 55 g of methyl ethyl ketone was heated to 60 ° C. under a nitrogen stream. Heated. To this, 0.2 g of 2,2'-azobis (isovaleronitrile) was added and reacted for 3 hours, and 0.1 g of the above initiator was further added and reacted for 4 hours. The obtained dispersion had a reaction rate of 95% and had an average particle size of dispersed resin particles of 0.20 μm and good monodispersibility (particle size measurement: CAPA-500 (trade name, manufactured by Horiba Ltd.)). This dispersion was coated on a SIM paper support with a wire bar and dried at a temperature of 100 ° C. for 1 minute to obtain a coating amount of 12
An image-receiving layer having a Beck's smoothness of 65 (sec / 10 cc) was formed at g / m ² . This printing original plate was made into a plate in the same manner as in Example 1 and subjected to a desensitizing treatment to form a printing plate, which was offset printed. The obtained printed matter had a clear image quality with no stain in the non-image area as in Example 1, and had a good printing durability of 3000 sheets or more.

(Examples 7 to 14) In Example 1, 5 x 1 of each compound shown in Table 2 below was used instead of 4 g of oxalic acid.
0 ^-2 except for using mol was prepared in the same manner as in operation to a direct drawing type lithographic printing plate precursor as in Example 1. The Bekk smoothness of the surface of each original plate was in the range of 50 to 60 (seconds / 10 cc).

[0069]

[Table 2] This printing original plate was subjected to plate making in the same manner as in Example 1 and subjected to a desensitizing treatment to obtain a printing plate, and offset printing was performed. The obtained printed matter had a clear image quality with no stain in the non-image area as in Example 1, and had a good printing durability of 3000 sheets or more.

[0070]

According to the present invention, it is possible to provide a direct-drawing type lithographic printing plate precursor which is excellent in desensitization and does not cause spot stains as well as uniform stain stains on the entire surface as an offset master plate. Further, it is possible to provide a direct-drawing type lithographic printing plate precursor that can obtain a printed matter having a clear image without printing stains even by drawing from an electrophotographic copying machine using an electrostatic transfer system.

Claims (2)

[Claims] 1. A direct-drawing type lithographic printing plate precursor having an image receiving layer containing zinc oxide and a binder resin on a water-resistant support, wherein the zinc oxide is a hydroxyl group, a thiol group,
A direct-drawing lithographic printing plate precursor comprising zinc oxide containing an aliphatic carboxylic acid group having 6 or less carbon atoms and containing at least one polar group selected from an amino group and a carboxyl group. 2. The zinc oxide contains the aliphatic carboxylic acid group in an amount of 1.0 × 10 ⁻⁴ mol / 100 g of zinc oxide.
The direct-drawing lithographic printing plate precursor as claimed in claim 1, which is zinc oxide containing 5.0 × 10 ^-1 mol.