JP2002293050A - Original sheet for heat-sensitive lithographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an original sheet for a heat-sensitive lithographic printing plate which can be directly mounted on a printing machine to perform printing without performing development processing after exposure and is hardly stained and exhibits excellent wear resistance and in which abrasion ( scattering) of the hydrophilic layer is suppressed and a device for exposure to light and a light source are less stained. SOLUTION: The original sheet for the heat-sensitive lithographic printing plate is characterized by having a hydrophilic layer in which exposed parts to light are easily removed with dampening water or an ink and a water-soluble overcoat layer in this order on a base sheet having an ink receiving surface or coated with an ink receiving layer and containing a photo-thermal conversing agent in at least one layer among the hydrophilic layer, the ink receiving layer and the overcoat layer and the dynamic hardness of the hydrophilic layer being at least 20 mN/μm<2> .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct heat-sensitive lithographic printing plate precursor for offset printing which does not require development and has excellent printing durability. More specifically, it is possible to record an image by scanning exposure based on a digital signal, and the recorded image can be directly attached to a printing machine and printed without going through a conventional liquid developing process. It relates to a lithographic printing plate precursor.

[0002]

2. Description of the Related Art In general, a lithographic printing plate comprises an oleophilic image area which receives ink during a printing process and a hydrophilic non-image area which receives fountain solution. As such a lithographic printing plate, a PS plate in which a lipophilic photosensitive resin layer is provided on a hydrophilic support has been widely used. As a plate making method, usually, after exposing through an original such as a lith film, a non-image portion is dissolved and removed with a developing solution, and a desired printing plate is obtained by this method.

[0003] The plate making process in the conventional PS plate requires an operation of dissolving and removing a non-image portion after exposure, and it is necessary to eliminate or simplify such additional wet processing. This is one problem that has been desired to be improved over the prior art. In particular, in recent years, the disposal of the waste liquid discharged by wet processing has become a major concern of the entire industry due to consideration for the global environment, and the demand for improvement in this aspect has been further increased.

[0004] As one of the simple plate making methods responding to this demand, an image recording layer is used which enables the non-image portion of a printing plate to be removed in a normal printing process. And a method for obtaining a final printing plate has been proposed. The lithographic printing plate making method by such a method is called an on-press development method. Specific examples of the method include a method of using an image recording layer soluble in a fountain solution or an ink solvent, and a method of mechanically removing the image recording layer by contact with an impression cylinder or a blanket cylinder in a printing press. However, in the conventional on-press developing method of an image recording method using ultraviolet light or visible light, since the image recording layer is not fixed even after exposure, for example, the original plate is completely shielded from light until it is mounted on a printing press. Alternatively, it was necessary to take a time-consuming method such as preservation under constant temperature conditions.

On the other hand, as another trend in this field in recent years, digitization technology for electronically processing, storing, and outputting image information using a computer has become widespread. I have. Along with this, a computer that carries digitized image information in high-convergent radiation such as laser light, scans and exposes the original plate with this light, and directly manufactures a printing plate without passing through a lith film. Attention has been focused on to-plate technology. Accordingly, obtaining an original plate for a printing plate adapted to this purpose has become an important technical problem. Therefore, simplification, dry processing, and non-processing of plate making operations are more and more desired than ever in view of both the above-mentioned environmental aspects and adaptation to digitalization.

Recently, as a method of manufacturing a printing plate by scanning exposure, which is easy to incorporate into digital technology, semiconductor lasers,
Since high-power solid-state lasers such as YAG lasers have become available at low cost, plate-making methods using these lasers as image recording means have become particularly promising. In the conventional plate-making method, image recording is performed by giving an imagewise exposure of the photosensitive original plate at low to medium illuminance and changing the image-like physical properties of the original plate surface by a photochemical reaction. In the method using density exposure, a large amount of light energy is concentratedly irradiated onto an exposure area during an instantaneous exposure time, and the light energy is efficiently converted into heat energy, and the heat causes a chemical change, a phase change,
A thermal change such as a change in form or structure is caused, and the change is used for image recording. That is, image information is input by light energy such as laser light, while image recording is recorded by a reaction by heat energy. Normally, a recording method using heat generated by such high power density exposure is called heat mode recording, and changing light energy to heat energy is called photothermal conversion.

The major advantages of the plate making method using the heat mode recording means are that the plate is not exposed to light having a normal illuminance level such as indoor lighting, and that an image recorded by high illuminance exposure is not essential. . In other words, the heat mode photosensitive material is used for image recording. Before exposure, it is safe against room light, and it is not essential to fix the image after exposure.
Therefore, for example, if an image recording layer that is insolubilized or solubilized by heat mode exposure is used, and a plate making process in which the exposed image recording layer is imagewise removed to form a printing plate is performed by an on-press development method, development (non-image Part removal) allows for a printing system in which the image is not affected for some time after image exposure, even if exposed to room ambient light. Therefore, if heat mode recording is used, it is expected that a lithographic printing plate precursor that is desirable for an on-press development system can be obtained.

[0008] As one of the preferred methods for producing a lithographic printing plate based on heat mode recording, a hydrophobic image recording layer is provided on a hydrophilic substrate, and is subjected to heat mode exposure in the form of an image. A method has been proposed in which the dispersibility is changed and, if necessary, the non-image areas are removed by wet development. As an example of such an original plate, for example, Japanese Patent Publication No. 46-279
No. 19 discloses an original plate provided with a recording layer having a so-called positive action in which solubility is improved by heat, specifically a recording layer having a specific composition such as a saccharide or a melamine formaldehyde resin, on a hydrophilic support. A method of obtaining a printing plate by recording in a heat mode is described.

However, all of the recording layers described above have insufficient heat sensitivity, and thus have insufficient sensitivity to heat mode scanning exposure. In addition, the hydrophobic / hydrophilic discrimination before and after exposure, that is, a small change in solubility was also a practical problem. If discrimination is poor, it is practically difficult to make plate making by the on-press development system.

JP-A-55-105560 discloses that a hydrophilic layer containing colloidal alumina or silica is provided on a substrate coated with a lipophilic light-to-heat conversion layer, and the hydrophilic layer is removed by ablation (scattering). A printed version is listed. WO 94/18005 also discloses that polyvinyl alcohol is crosslinked with a hydrolyzate of tetraethoxysilicon,
A printing plate is described in which a hydrophilic layer containing titanium dioxide particles is ablated and removed. However, these techniques do not satisfy all the performances required for an excellent printing plate, such as high sensitivity, excellent stain resistance, and high printing durability, and require further improvement.

[0011] WO 98/40212 discloses that plate making can be performed without developing, provided that a hydrophilic layer comprising a transition metal oxide colloid is provided on a substrate coated with an ink receiving layer containing a photothermal conversion agent. Possible lithographic printing plate precursors are described. In this method, the hydrophilic layer composed of the transition metal oxide colloid is ablated and removed by heat generated by the photothermal conversion agent in the exposed portion. However, in this printing plate, the printing durability was insufficient.

Further, the printing plate precursors utilizing these abrasions have the disadvantage that ablation (scattering) contaminates the optical system of the exposing machine and lowers the laser power, thereby greatly reducing the maintainability. Therefore, in the conventional heat-sensitive lithographic printing plate precursor, in order to prevent the above-mentioned contamination due to the ablation of the hydrophilic layer, it is necessary to provide these devices with an ablation residue capturing device. Was difficult to remove.

Plate making using heat mode image recording
The printing method has the advantages that the printing plate can be made directly from under the plate without the use of a film, so that the plate can be made on-press, and the developing operation can be omitted. It has such disadvantages.

[0014]

SUMMARY OF THE INVENTION An object of the present invention is to solve the drawbacks of the conventional heat mode plate making method using laser exposure. That is, a heat-sensitive lithographic plate that can be scanned and exposed in a short time, and can be directly mounted on a printing machine for printing without performing a developing process, and has excellent printing durability and has no stain in printing. An object of the present invention is to provide a printing plate. Another object of the present invention is to provide a heat-sensitive lithographic printing plate precursor in which ablation (scattering) of a hydrophilic layer is suppressed during laser exposure and contamination of an exposure device and a light source is reduced.

[0015]

Means for Solving the Problems As a result of earnest study, the present inventor has found that the above object can be achieved by the following constitution. That is, the present invention is as follows.

1. A hydrophilic layer having an ink receptive surface or on a substrate on which the ink receptive layer is applied, the exposed portion is easily removed by a fountain solution or ink during printing,
And a water-soluble overcoat layer in this order, a hydrophilic layer,
A heat-sensitive lithographic printing plate precursor comprising at least one of an ink receiving layer and an overcoat layer containing a photothermal conversion agent, wherein the hydrophilic layer has a dynamic hardness of 20 mN / μm ² or more. Lithographic printing plate precursor

2. The hydrophilic layer contains a colloid of at least one compound selected from oxides or hydroxides of beryllium, magnesium, aluminum, silicon, titanium, boron, germanium, tin, zirconium, iron, vanadium, antimony, and transition metals. 2. The heat-sensitive lithographic printing plate precursor as described in 1 above, wherein

3. The hydrophilic layer is a colloid of at least one compound selected from oxides or hydroxides of beryllium, magnesium, aluminum, silicon, titanium, boron, germanium, tin, zirconium, iron, vanadium, antimony and transition metals; 20% by weight of solid content of hydrophilic layer containing hydrophilic resin
3. The heat-sensitive lithographic printing plate precursor as described in 1 or 2 above,

The inventor of the present invention has found that the abrasion of the hydrophilic layer with the progress of printing is the dominant factor in the printing durability of the system for producing a printing plate by ablating the hydrophilic layer, and also suppresses the abrasion. Is preferably a hydrophilic layer having a material composition of high hardness, and the hydrophilic layer has a dynamic hardness of 20 mN / μm ^2.
It has been found that it is necessary to have the above.

Furthermore, it has been found that by providing a water-soluble overcoat on the outermost surface layer above the hydrophilic layer, a latent image can be formed while suppressing ablation (scattering) of the hydrophilic layer more effectively. That is, in the present invention, the laser exposure does not cause the hydrophilic layer to be ablated (scattered) due to the heat generated by the photothermal conversion agent contained in at least one of the overcoat layer, the hydrophilic layer, and the ink receiving layer. Is easily removed by the dampening solution or the ink, and an image portion (latent image) is formed. Although the details of this mechanism are not clear, it is considered that ablation occurs near the hydrophilic layer interface of the ink receiving layer, and in the present invention, the phenomenon as described above causes the hydrophilic layer to be “ablation-like”.
Is called a latent image formation. In practice, the hydrophilic layer is visually observed to form an image at the start of printing due to a decrease in adhesion to the underlying ink receiving layer. This ablative latent image formation is effectively performed by the presence of the overcoat layer.

In the present invention, the hydrophilic layer in the exposed portion where the latent image has been formed by ablation is removed by a dampening solution or ink during printing. The upper overcoat layer is first removed by a dampening solution, and at the time of this removal, the hydrophilic layer on the exposed portion where the latent image is formed is simultaneously removed. By removing the hydrophilic layer, the lower ink receiving layer appears,
It becomes an image part. The unexposed portion receives water while maintaining hydrophilicity and repels the ink. In this manner, printing can be performed simultaneously with development on the printing press. There is no need for wet processing with a developing solution as in conventional lithographic printing plates. That is, a lithographic printing plate is produced without any processing.

In addition, after the exposure, before mounting on a printing machine,
The printing plate may be left in the air for a long time or may be handled with ink-coated hands, causing lipophilic substances to adhere to the plate and causing stains during printing. The layers also made it possible to prevent the attachment of lipophilic substances to these hydrophilic layers.

As described above, the present invention provides a hydrophilic layer having a dynamic hardness value of 20 mN / μm ² or more, and a water-soluble overcoat layer, in which the exposed portion can be easily removed by a fountain solution or ink at the time of printing. This solves the basic problems of unprocessed direct printing plates, such as low printing durability and scattering of abrasion debris, at the same time.

[0024]

Embodiments of the present invention will be described below in detail.

The dynamic hardness (DH) used as the physical property value of the hydrophilic layer in the present invention is a measure of the load in the process of pushing the indenter into the sample and the amount of penetration of the indenter into the sample (indentation depth). Required, load P
(MN) and DH (m
N / μm ² ) = α · P / D ² . At this time, α is a constant peculiar to the indenter and the ridge angle 11 used in the present invention.
For a 5 ° triangular pyramid indenter, α = 3.8584. As can be seen from this equation, the dynamic hardness is different from Vickers hardness and Knoop hardness, which are widely used, and is a strength characteristic in a state including not only the amount of plastic deformation but also elastic deformation of the sample. In order to accurately measure the value of the target sample, it is necessary to have a sufficient thickness with respect to the indentation depth. Therefore, a heat-sensitive lithographic printing plate is formed so that the hydrophilic layer is 3 μm thick on 0.24 mm thick aluminum. The measurement was performed using a dynamic ultra-micro hardness tester DUH-201 manufactured by Shimadzu Corporation, which was provided separately from the original plate. As the indentation depth, a value obtained when the load reached 2 mN at a load acceleration of 0.3 mN / sec and was held for 5 seconds was used.

The water-soluble overcoat layer used in the present invention can be easily removed at the time of printing and contains a resin selected from water-soluble organic or inorganic polymer compounds.
A light-to-heat conversion agent may be contained. As the water-soluble organic or inorganic resin used herein, a film formed by coating and drying has a film-forming ability, and specifically, polyvinyl alcohol (a hydrolysis rate of polyvinyl acetate of 65%)
The above), homopolymers or copolymers of acrylic acid and their alkali metal salts or amine salts, homopolymers or copolymers of methacrylic acid and their alkali metal salts or amine salts, homopolymers of acrylamide Or copolymer, polyhydroxyethyl acrylate, homopolymer or copolymer of vinylpyrrolidone, polyvinyl methyl ether, vinyl methyl ether / maleic anhydride copolymer, 2-acrylamido-2-methyl-1-propanesulfonic acid Homopolymers or copolymers and their alkali metal salts or amine salts, gum arabic, water-soluble soybean polysaccharides, cellulose derivatives (eg, carboxymethylcellulose, carboxyethylcellulose, methylcellulose, etc.) and modified products thereof, white dextrin, pullulan , Enzymatic degradation etherification And the like can be given dextrin. Further, according to the purpose, two or more of these resins can be used in combination.

The photothermal conversion agent used together with the above water-soluble resin may be any substance that absorbs light of 700 nm or more, and various pigments and dyes can be used. Examples of the pigment include commercially available pigments and Color Index (CI).
Handbook, "Latest Pigment Handbook" (edited by Japan Pigment Technical Association, 197
7th year), “Latest Pigment Application Technology” (CMC Publishing, 198
6) and "Printing Ink Technology" published by CMC, 1984) can be used.

Examples of the kind of the pigment include a black pigment, a brown pigment, a red pigment, a violet pigment, a blue pigment, a green pigment, a fluorescent pigment, a metal powder pigment, and a polymer-bound pigment. Specifically, insoluble azo pigments, azo lake pigments, condensed azo pigments, chelated azo pigments, phthalocyanine pigments, anthraquinone pigments, perylene and perinone pigments, thioindigo pigments, quinacridone pigments, dioxazine pigments, isoindolinone pigments And quinophthalone pigments, dyed lake pigments, azine pigments, nitroso pigments, nitro pigments, natural pigments, fluorescent pigments, inorganic pigments, carbon black, and the like.

These pigments may be used without surface treatment or may be used after surface treatment. The method of surface treatment is a method of surface coating a hydrophilic resin or lipophilic resin,
A method of attaching a surfactant, a method of bonding a reactive substance (for example, silica sol, alumina sol, a silane coupling agent, an epoxy compound, an isocyanate compound, and the like) to the surface of the pigment are considered. The above surface treatment method,
It is described in "Properties and Applications of Metallic Soaps" (Koshobo), "Printing Ink Technology" (CMC Publishing, 1984) and "Latest Pigment Application Technology" (CMC Publishing, 1986). Among these pigments, those that absorb infrared light or near-infrared light are particularly preferable because they are suitable for use in lasers that emit infrared light or near-infrared light.

As such a pigment absorbing infrared light or near infrared light, carbon black, carbon black coated with a hydrophilic resin, and carbon black modified with silica sol are preferably used. Among them, carbon black whose surface is coated with a hydrophilic resin or silica sol is useful as a material which is easily dispersed in a water-soluble resin and does not impair hydrophilicity.

The particle size of the pigment is preferably in the range of 0.01 μm to 1 μm, and more preferably in the range of 0.01 μm to 0.5 μm. As a method for dispersing the pigment, a known dispersion technique used in the production of ink or toner can be used. As the disperser, an ultrasonic disperser,
Sand mills, attritors, pearl mills, super mills, ball mills, impellers, dispersers, KD mills, colloid mills, dynatrons, three-roll mills, pressure kneaders and the like can be mentioned. Details are described in "Latest Pigment Application Technology" (CMC Publishing, 1986).

As the dye, commercially available dyes and known dyes described in literatures (for example, "Dye Handbook" edited by The Society of Synthetic Organic Chemistry, published in 1970) can be used. Specific examples include dyes such as azo dyes, metal complex salt azo dyes, pyrazolone azo dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinone imine dyes, methine dyes, and cyanine dyes. Among these dyes, those that absorb infrared light or near-infrared light are particularly preferable because they are suitable for use in lasers that emit infrared light or near-infrared light.

Dyes that absorb infrared light or near infrared light include, for example, JP-A-58-125246 and JP-A-59-8.
4356, a cyanine dye described in JP-A-60-78787, a methine dye described in JP-A-58-173696, JP-A-58-181690, JP-A-58-194595, etc. JP-A-58-1127
No. 93, JP-A-58-224793, and JP-A-59-4
No. 8187, JP-A-59-73996, JP-A-60-
No. 52940, JP-A-60-63744 and the like; naphthoquinone dyes described in JP-A-58-112792 and the like; British Patent 43
And cyanine dyes described in U.S. Pat.
The dyes described as formulas (I) and (II) in US Pat. No. 6,993 can be exemplified.

[0034]

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[In the formula (I), R¹, R^Two, R^Three, R^Four, R^Five
And R⁶Is a substituted or unsubstituted alkyl group; Z¹And Z^TwoIs
A substituted or unsubstituted phenyl or naphthalene group; L is
A substituted or unsubstituted methine group, wherein the substituent has 8 or more carbon atoms;
A lower alkyl group, a halogen atom or an amino group,
The methine group is such that the substituents on the two methine carbons
A cyclohexyl which may have a substituent formed by bonding
Even those containing a xen ring or a cyclopentene ring
Often, the substituent is an alkyl group having 6 or less carbon atoms or halo.
X is an anionic group; n is 1 or 2;
R¹, R^Two, R^Three, R^Four, R ^Five, R⁶, Z¹And Z^TwoSmall of
At least one is an acid group or an alkali metal base of an acid group or
Represents a substituent having an amine base. ]

[0036]

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[In the formula (II), R¹¹Is replaced or unsubstituted
An alkyl group, a substituted or unsubstituted aryl group or
A substituted or unsubstituted heterocyclic group; R¹²And R¹⁵Is hydrogen field
A group which can be substituted for a substituent or a hydrogen atom: R¹³And R¹⁴Is
Hydrogen atom, halogen atom, substituted or unsubstituted alcohol
A xy group or a substituted or unsubstituted alkyl group, provided that R¹³
And R¹⁴Are not simultaneously hydrogen atoms: R¹⁶And R¹⁷Is
Substituted or unsubstituted alkyl group, substituted or unsubstituted
An aryl group, an acyl group or a sulfonyl group, or R ¹⁶And R
¹⁷Represents a non-metallic 5- or 6-membered ring. ]

As a dye, US Pat. No. 5,156,
No. 938 is also preferably used, and substituted arylbenzo (thio) pyrylium salts described in U.S. Pat. No. 3,881,924;
No. 42645 (U.S. Pat. No. 4,327,169), a trimethinethiapyrylium salt described in JP-A-58-1810.
No. 51, No. 58-220143, No. 59-41363
Nos. 59-84248, 59-84249, 59-146063, and 59-146061 and pyrylium compounds described in JP-A-59-2161.
No. 46, a cyanine dye disclosed in U.S. Pat. No. 4,283,4.
No. 75, pentamethine thiopyrylium salts and the like, and pyrilium compounds described in JP-B-5-13514 and 5-19702, Epolin Epolight
III-178, Epollight III-130, Epo
Light III-125 and the like are particularly preferably used.
Particularly preferred among these dyes are the water-soluble cyanine dyes of the above formula (I). Specific compounds are listed below.

[0039]

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[0040]

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[0041]

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[0042]

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[0043]

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[0044]

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The amount of the pigment or dye added to the overcoat layer is 50% by weight or less, preferably 20% by weight or less, based on the total solids of the overcoat layer. For dyes, particularly preferably 10% by weight or less. Particularly preferably, the proportion is 30% by weight or less. Within this range, the sensitivity can be improved without impairing the uniformity and durability of the layer.

In addition, a nonionic surfactant can be mainly added to the overcoat layer in the case of aqueous solution application for the purpose of ensuring uniformity of application. Specific examples of such a nonionic surfactant include sorbitan tristearate, sorbitan monopalmitate, sorbitan triolate, stearic acid monoglyceride, and polyoxyethylene nonyl phenyl ether. The proportion of the nonionic surfactant in the total solid content of the overcoat layer is preferably 0.05 to 5% by weight, more preferably 1 to 3% by weight.

The thickness of the overcoat layer used in the present invention is preferably from 0.05 to 4.0 μm, and more preferably from 0.1 to 1.0 μm. If it is too thick, it will take time to remove the overcoat layer during printing, and a large amount of the water-soluble resin will affect the dampening solution, causing roller strips during printing and ink sticking to the image area. There are adverse effects such as no meat. If it is too thin, the film properties may be impaired.

The hydrophilic layer used in the present invention is a lithographic printing method using water and / or ink, which is a layer which has an affinity for a fountain solution but does not dissolve in the fountain solution, and has a dynamic hardness. Is not particularly limited as long as the value is not less than 20 mN / μm ² , but it is desirable to comprise the following colloid in consideration of the balance between hydrophilicity and hardness. Beryllium, magnesium, aluminum, silicon, titanium, boron, germanium, tin, zirconium, iron, vanadium, antimony or a transition metal oxide or hydroxide is a colloid comprising a sol-gel conversion system. In some cases, a colloid comprising a complex of these elements may be used. These colloids have a network structure in which the above-mentioned elements form a network structure via an oxygen atom and also have an unbonded hydroxyl group or alkoxy group, and these colloids have a mixed structure. From the initial hydrolysis-condensation stage, which is rich in active alkoxy groups and hydroxyl groups, the particle size increases and becomes inactive as the reaction proceeds. Colloidal particles generally have a diameter of 2 nm to 500 nm, and in the case of silica, spherical particles having a diameter of 5 nm to 100 nm are suitable in the present invention. Furthermore, 10 nm
Collars in the form of pearl necklaces in which spherical particles having a diameter of 50 to 400 nm are connected in a length of 50 to 400 nm can also be used. 100x like an aluminum colloid
Feathers such as 10 nm are also effective. Commercially available products such as Nissan Chemical Industries, Ltd. can be purchased as a dispersion of these colloids.

The colloid may be used alone,
Furthermore, it is also possible to use a mixture with a hydrophilic resin. Further, a colloidal crosslinking agent may be added to promote crosslinking.

Usually, the colloid is often stabilized by a stabilizer. For a colloid charged with a cation, a compound having an anionic group is added as a stabilizer, and conversely, for a colloid charged with an anion, a compound having a cationic group is added as a stabilizer. For example, a silicon colloid is charged with an anion, so an amine compound is added as a stabilizer, and an aluminum colloid is charged with a cation, so a strong acid such as hydrochloric acid or acetic acid is added. When such a colloid is applied on a substrate, a transparent film is often formed at room temperature.However, gelation is incomplete only by evaporation of the colloid solvent, and by heating to a temperature at which the stabilizer can be removed, By performing strong tertiary cross-linking, a hydrophilic layer preferable in the present invention is obtained.

Without using the above-mentioned stabilizer, a hydrolysis and condensation reaction is directly carried out from a starting material (for example, di-, tri- and / or tetraalkoxysilane) to form an appropriate sol state and directly onto a substrate. The reaction may be completed by coating and drying. In this case, three-dimensional crosslinking can be performed at a lower temperature than when a stabilizer is included.

In addition, a colloid obtained by dispersing and stabilizing an appropriate hydrolysis-condensation reaction product in an organic solvent is also suitable for the present invention. A stable film can be obtained only by evaporating the solvent. These solvents include methanol, ethanol, propanol,
If a low-boiling solvent such as butanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether or methyl ethyl ketone is selected, drying at room temperature becomes possible. In particular, in the present invention, a colloid of a methanol or ethanol solvent is useful because a film can be easily formed at a low temperature. The value of the dynamic hardness of such a hydrophilic layer composed solely of colloid is 20 to 30 mN / μm ² .

As the hydrophilic resin used together with the above colloid, those having a hydrophilic group such as hydroxyl, carboxyl, hydroxyethyl, hydroxypropyl, amino, aminoethyl, aminopropyl and carboxymethyl are preferred.

Specific hydrophilic resins include gum arabic, casein, gelatin, starch derivatives, carboxymethylcellulose and their sodium salts, cellulose acetate, sodium alginate, vinyl acetate-maleic acid copolymers, styrene-maleic acid copolymers, Polyacrylic acids and their salts, polymethacrylic acids and their salts, hydroxyethyl methacrylate homopolymers and copolymers, hydroxyethyl acrylate homopolymers and copolymers, hydroxypropyl methacrylate homopolymers and copolymers,
Hydroxypropyl acrylate homopolymers and copolymers, hydroxybutyl methacrylate homopolymers and copolymers, hydroxybutyl acrylate homopolymers and copolymers, polyethylene glycols, hydroxypropylene polymers, polyvinyl alcohols, and a degree of hydrolysis of at least 60% by weight; Preferably at least 80% by weight of hydrolyzed polyvinyl acetate, polyvinyl formal, polyvinyl butyral, polyvinyl pyrrolidone, homopolymers and copolymers of acrylamide, homopolymers and copolymers of methacrylamide, homopolymers and copolymers of N-methylolacrylamide and the like. it can.

Particularly preferred hydrophilic resins include hydroxyethyl methacrylate homopolymers and copolymers, hydroxyethyl acrylate copolymers, and polyacrylic acid.

These hydrophilic resins are used together with a colloid. The proportion of the hydrophilic resin is as follows when the hydrophilic resin is water-soluble.
The total solid content of the hydrophilic layer is preferably 20% by weight or less, more preferably 10% by weight or less. In the case of a hydrophilic resin that is not water-soluble, the content is preferably 10% by weight or less of the total solids. If the addition ratio of the hydrophilic resin is too large, the value of the dynamic hardness becomes 2
Below 0 mN / μm ² , the printing durability is insufficient.

These hydrophilic resins can be used as they are, but in order to further increase the printing durability during printing,
A crosslinking agent for a hydrophilic resin may be added. Examples of the crosslinking agent for such a hydrophilic resin include initial hydrolysis and condensate of formaldehyde, glyoxal, polyisocyanate and tetraalkoxysilane, dimethylol urea and hexamethylol melamine.

The hydrophilic layer of the present invention may contain, in addition to the above-mentioned oxide or hydroxide colloid and the hydrophilic resin, a crosslinking agent for promoting the crosslinking of the colloid. As such a crosslinking agent, an initial hydrolysis condensate of tetraalkoxysilane, trialkoxysilylpropyl-N, N, N-trialkylammonium halide or aminopropyltrialkoxysilane is preferable. The value of the dynamic hardness increases in proportion to the addition amount, and the printing durability also improves. However, if the addition ratio exceeds 25% by weight of the total solids in the hydrophilic layer, the affinity for dampening water decreases, and background fouling occurs. . Therefore, the proportion of the crosslinking agent added is preferably 25% by weight or less based on the total solid content of the hydrophilic layer.

Further, to the hydrophilic layer of the present invention, a hydrophilic photothermal conversion agent added to the above-mentioned overcoat layer may be added in order to enhance the heat sensitivity. Particularly preferred photothermal conversion agents are water-soluble infrared-absorbing dyes, such as the cyanine dyes having a sulfonic acid group of the formula (I), an alkali metal base of a sulfonic acid or an amine base. The addition ratio of these dyes is 20% by weight or less, more preferably 5% by weight or less, based on the total amount of the hydrophilic layer. If it exceeds 20% by weight, the affinity for the dampening solution is reduced, and the soil is easily soiled. For this reason, it is particularly desirable to add a light-to-heat conversion agent to the other layer and not to add the light-to-heat conversion agent to the hydrophilic layer, or to set a small amount.

The coating thickness of the hydrophilic layer of the present invention is 0.1 to 3 μm.
m is preferable. More preferably, 0.3 to 2
μm. Within this range, it is possible to obtain a good lithographic printing original plate which does not require a large amount of energy or a long time for the formation of an abrasion latent image due to the deterioration of printing durability due to the decrease in durability of the hydrophilic layer.

The substrate having an ink-receiving surface or the ink-receiving layer to be used in the present invention includes:
A dimensionally stable plate is used. Paper, paper laminated with lipophilic plastics (eg, polyethylene, polypropylene, polystyrene, etc.), metal plate (eg, aluminum, zinc, copper, nickel, stainless steel plate, etc.), and ink-receptive organic polymer resin applied Metal plates, plastic films (eg, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.) The above-mentioned plastic film coated with an ink-receiving organic polymer resin, paper or a plastic film on which the above-mentioned ink-receiving metal is laminated or vapor-deposited, and the like are included.

A preferred substrate is a polyethylene terephthalate film, a polycarbonate film, aluminum or a steel plate coated with an ink-receptive organic polymer resin, or an aluminum or steel plate laminated with a lipophilic plastic film.

The aluminum plate suitable for use in the present invention is a pure aluminum plate or an alloy plate containing aluminum as a main component and containing a trace amount of a different element. Is applied or an ink-receptive plastic is laminated. The foreign elements contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, titanium and the like. The content of the foreign element in the alloy is at most 10% by weight or less. However, the aluminum plate applied to the present invention is:
A conventionally known and used aluminum plate can also be used as appropriate.

It is preferable to roughen the surface of the aluminum plate before using it. When an ink receiving layer containing an organic polymer is applied by roughening, adhesion to a substrate can be easily secured. For roughening, first, a degreasing treatment with, for example, a surfactant, an organic solvent or an alkaline aqueous solution is performed to remove rolling oil on the surface of the aluminum substrate.

The surface roughening treatment of the aluminum plate is performed by various methods. For example, a method of mechanically roughening the surface, a method of electrochemically dissolving and roughening the surface, and a method of chemically roughening the surface. Is selectively dissolved. As a mechanical method, a known method such as a ball polishing method, a brush polishing method, a blast polishing method, and a buff polishing method can be used. The chemical method is described in JP-A-54-3118.
The method of immersing in a saturated aqueous solution of an aluminum salt of a mineral acid as described in No. 7 is suitable. Further, as an electrochemical surface roughening method, there is a method of carrying out an alternating current or a direct current in an electrolytic solution containing an acid such as hydrochloric acid or nitric acid. Also,
An electrolytic surface roughening method using a mixed acid as described in JP-A-54-63902 can also be used. The surface roughening by the above-described method is preferably performed in a range where the center line surface roughness (Ha) of the surface of the aluminum plate is 0.3 to 1.0 μm.

The roughened aluminum plate is subjected to an alkali etching treatment using an aqueous solution of potassium hydroxide or sodium hydroxide, if necessary, and further subjected to a neutralization treatment. Is anodized.

As the electrolyte used for the anodic oxidation treatment of the aluminum plate, various electrolytes forming a porous oxide film can be used, and generally, sulfuric acid, hydrochloric acid, oxalic acid, chromic acid or a mixed acid thereof is used. Can be The concentration of these electrolytes is appropriately determined depending on the type of the electrolyte.

The anodizing treatment conditions vary depending on the electrolyte used and cannot be specified unconditionally. However, in general, the concentration of the electrolyte is a 1 to 80% by weight solution, the liquid temperature is 5 to 70 ° C.,
It is appropriate that the current density ranges from 5 to 60 A / dm ² , the voltage ranges from 1 to 100 V, and the electrolysis time ranges from 10 seconds to 5 minutes. The amount of the formed oxide film is 1.0 to 5.0 g / m ² , particularly 1.5 to 5.0 g / m ² .
It is preferably 4.0 g / m ² .

The thickness of the substrate used in the present invention is about 0.05 mm to 0.6 mm, preferably 0.1 mm to 0.6 mm.
It is 0.4 mm, particularly preferably 0.15 mm to 0.3 mm.

The organic polymer applied as an ink receiving layer on the surface of the substrate of the present invention is soluble in a solvent and has a lipophilic film-forming ability. Furthermore, it is desirable that the solvent is insoluble in the coating solvent for forming the upper hydrophilic layer. However, in some cases, a material that swells partially in the upper layer coating solvent has good adhesiveness to the upper layer, and may be desirable. In addition, when an organic polymer that is soluble in the upper layer coating solvent is used, it is preferable that the organic polymer be cured in advance by, for example, adding crosslinking or the like.

Examples of useful organic polymers include polyester, polyurethane, polyurea, polyimide, posisiloxane, polycarbonate, phenoxy resin, epoxy resin, phenol / formaldehyde resin, alkylphenol / formaldehyde resin, polyvinyl acetate, acrylic resin and copolymers thereof. Polyvinyl phenol, polyvinyl halogenated phenol, methacrylic resin and its copolymer, acrylamide copolymer, methacrylamide copolymer, polyvinyl formal, polyamide, polyvinyl butyral, polystyrene, cellulose ester resin, polyvinyl chloride and polyvinylidene chloride Can be mentioned.

Among these, as a more preferred compound, a resin having a hydroxyl group, a carboxy group, a sulfonamide group or a trialkoxysilyl group in a side chain is excellent in adhesiveness to a substrate or an upper hydrophilic layer, and in some cases, is crosslinked. It is desirable because it easily cures with the agent. In addition, an acrylonitrile copolymer, polyurethane, a copolymer having a sulfonamide group in a side chain or a copolymer having a hydroxyl group in a side chain is preferably photocured with a diazo resin.

Other phenol, cresol (m-cresol, p-cresol, m / p mixed cresol), phenol / cresol (m-cresol, p-cresol, m / p mixed cresol), phenol-modified xylene, tert-butylphenol, A novolak resin and a resole resin of condensation with formaldehyde such as octylphenol, resorcinol, pyrogallol, catechol, chlorophenol (m-Cl, p-Cl), bromophenol (m-Br, p-Br), salicylic acid, and phloroglucinol; Further, a condensation resin of the above phenol compound and acetone is useful.

As other suitable high molecular compounds, copolymers having a molecular weight of usually 10,000 to 200,000 using the monomers shown in the following (1) to (12) as structural units can be exemplified.

(1) Acrylamides, methacrylamides, acrylates, methacrylates and hydroxystyrenes having an aromatic hydroxyl group, such as N- (4-hydroxyphenyl) acrylamide or N- (4-hydroxyphenyl) ) Methacrylamide, o-, m- and p-hydroxystyrene, o-,
m- and p-hydroxyphenyl acrylates or methacrylates, (2) acrylates and methacrylates having an aliphatic hydroxyl group, for example,
2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate,

(3) Methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, cyclohexyl acrylate, octyl acrylate, phenyl acrylate, benzyl acrylate, acrylic acid-2 (Substituted) acrylates such as -chloroethyl, 4-hydroxybutyl acrylate, glycidyl acrylate, N-dimethylaminoethyl acrylate, (4) methyl methacrylate,
Ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, octyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-chloroethyl methacrylate, 4-hydroxybutyl methacrylate (Substituted) methacrylates such as glycidyl methacrylate, N-dimethylaminoethyl methacrylate,

(5) Acrylamide, methacrylamide, N-methylol acrylamide, N-methylol methacrylamide, N-ethyl acrylamide, N-ethyl methacrylamide, N-hexyl acrylamide, N
-Hexyl methacrylamide, N-cyclohexyl acrylamide, N-cyclohexyl methacrylamide, N
-Hydroxyethylacrylamide, N-hydroxyethylacrylamide, N-phenylacrylamide, N
Acrylamides such as -phenylmethacrylamide, N-benzylacrylamide, N-benzylmethacrylamide, N-nitrophenylacrylamide, N-nitrophenylmethacrylamide, N-ethyl-N-phenylacrylamide and N-ethyl-N-phenylmethacrylamide Or methacrylamide,

(6) Ethyl vinyl ether, 2-chloroethyl vinyl ether, hydroxyethyl vinyl ether, propyl vinyl ether, butyl vinyl ether,
Vinyl ethers such as octyl vinyl ether and phenyl vinyl ether; (7) vinyl esters such as vinyl acetate, vinyl chloroacetate, vinyl butyrate and vinyl benzoate; (8) styrenes such as styrene, methyl styrene and chloromethyl styrene; 9)
Vinyl ketones such as methyl vinyl ketone, ethyl vinyl ketone, propyl vinyl ketone, and phenyl vinyl ketone; (10) olefins such as ethylene, propylene, isobutylene, butadiene, and isoprene; (11) N
-Vinylpyrrolidone, N-vinylcarbazole, 4-vinylpyridine, acrylonitrile, methacrylonitrile, etc.

(12) N- (o-aminosulfonylphenyl) acrylamide, N- (m-aminosulfonylphenyl) acrylamide, N- (p-aminosulfonylphenyl) acrylamide, N- [1- (3-aminosulfonyl) Naphthyl] acrylamide, acrylamides such as N- (2-aminosulfonylethyl) acrylamide, N- (o-aminosulfonylphenyl) methacrylamide, N- (m-aminosulfonylphenyl) methacrylamide, N- (p-aminosulfonyl) Methacrylamides such as phenyl) methacrylamide, N- [1- (3-aminosulfonyl) naphthyl] methacrylamide, N- (2-aminosulfonylethyl) methacrylamide, and o-aminosulfonylphenyl acrylate, m-amino Sulfo sulfonyl phenyl acrylate,
p-aminosulfonylphenyl acrylate, 1- (3
-Aminosulfonylphenylnaphthyl) unsaturated sulfonamides such as acrylates such as acrylate, o-aminosulfonylphenylmethacrylate, m
Unsaturated sulfonamides such as methacrylic esters such as -aminosulfonylphenyl methacrylate, p-aminosulfonylphenyl methacrylate and 1- (3-aminosulfonylphenylnaphthyl) methacrylate;

These organic polymers can be dissolved in an appropriate solvent, applied to a substrate and dried to form an ink receiving layer on the substrate. The organic polymer alone can be used by dissolving it in a solvent, but it is usually used together with a crosslinking agent, an adhesion aid, a coloring agent, inorganic or organic fine particles, a coating surface condition improving agent, or a plasticizer. In addition, a light-to-heat conversion agent for increasing the sensitivity or a heating color-developing system or a decoloring system for forming a printout image after exposure may be added to the ink receiving layer.

Specific crosslinking agents for crosslinking organic polymers include diazo resins, aromatic azide compounds, epoxy resins, isocyanate compounds, blocked isocyanate compounds, initial hydrolysis-condensation products of tetraalkoxy silicon, glyoxal, aldehyde compounds and methylol. Compounds can be mentioned.

As the adhesion aid, the above diazo resin is excellent in adhesion to a substrate and a hydrophilic layer. In addition, a silane coupling agent, an isocyanate compound and a titanium coupling agent are also useful.

As the coloring agent, ordinary dyes and pigments can be used. In particular, rhodamine 6G chloride, rhodamine B chloride, crystal violet, malachite green oxalate, oxazine 4 perchlorate, quinizarin,
2- (α-naphthyl) -5-phenyloxazole and coumarin-4. Specifically, as other dyes,
Oil Yellow # 101, Oil Yellow # 103, Oil Pink # 312, Oil Green BG, Oil Blue BOS, Oil Blue # 603, Oil Black B
Y, oil black BS, oil black T-505
(The above are manufactured by Orient Chemical Industry Co., Ltd.), Victoria Pure Blue, Crystal Violet (CI4255)
5), methyl violet (CI42535), ethyl violet, methylene blue (CI52015), patent pure blue (manufactured by Sumitomo Sangoku Chemical Co., Ltd.), brilliant blue, methyl green, erythricin B, basic fuchsin, m-cresol purple, auramine, 4
Triphenylmethane-based, diphenylmethane-based, oxazine-based, xanthene-based, iminonaphthoquinone-based, azomethine-based or anthraquinone-based dyes such as -p-diethylaminophenyliminaphthoquinone and cyano-p-diethylaminophenylacetanilide; No. -293247, Japanese Patent Application No. 7-33514
No. 5 can be mentioned.

When the above dye is added to the ink receiving layer, it is usually used in an amount of about 0.02 to 10% based on the total solid content of the receiving layer.
%, More preferably from about 0.1 to 5% by weight.

Further, fluorine-based surfactants and silicon-based surfactants which are well-known compounds as coating surface condition improvers can also be used. Specifically, a surfactant having a perfluoroalkyl group or a dimethylsiloxane group is useful for preparing the coated surface.

Examples of the fine inorganic or organic powder that can be used in the present invention include colloidal silica and colloidal aluminum having a diameter of 10 to 100 nm, as well as inert particles having a particle size larger than these colloids, such as silica particles.
Examples include silica particles, alumina particles, titanium dioxide particles, other heavy metal particles, clay, talc, and the like whose surfaces have been hydrophobized. The addition of these inorganic or organic fine powders to the ink receiving layer has the effect of improving the adhesion to the upper three-dimensionally crosslinked hydrophilic layer and increasing the printing durability in printing. The proportion of these fine powders in the ink receiving layer is 80% by weight or less, preferably 40% by weight or less of the total amount.

Further, a plasticizer may be added to the ink receiving layer of the present invention, if necessary, in order to impart flexibility to the coating film. For example, polyethylene glycol, tributyl citrate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, tricresyl phosphate, tributyl phosphate, trioctyl phosphate, tetrahydrofurfuryl oleate, oligomers of acrylic acid or methacrylic acid And polymers.

Further, it is preferable to add a coloring or decoloring compound to the ink receiving layer of the present invention in order to sharpen the image area and the non-image area when exposed. For example, together with thermal acid generators such as diazo compounds and diphenyliodonium salts, leuco dyes (leucomalachite green, leuco crystal violet, lactones of crystal violet, etc.) and PH discoloration dyes (eg, ethyl violet, Victoria Poor Blue BOH, etc.) Dye) is used. In addition, a combination of an acid coloring dye and an acidic binder as described in EP 897134 is also effective. In this case, the bond in the associated state forming the dye is broken by heating, and a lactone is formed to change from colored to colorless. The addition ratio of these coloring systems is 10% by weight or less, preferably 5% by weight or less based on the total amount in the receiving layer.

Further, a light-to-heat converting agent may be added to the ink receiving layer of the present invention in order to increase the heat sensitivity. The addition ratio is 1 to 25% by weight based on the total amount of the ink receiving layer.
And more preferably 10 to 20% by weight. The photothermal conversion agent may be the above-mentioned infrared absorbing dye or pigment, but in this case, a lipophilic dye or pigment is preferable. Particularly preferred are lipophilic ones of carbon black and the cyanine dyes represented by the above formula (I). Specific compounds of the lipophilic cyanine dye are described below.

[0090]

Embedded image

Solvents for coating the ink receiving layer include alcohols (methanol, ethanol, propyl alcohol, ethylene glycol, diethylene glycol,
Propylene glycol, dipropylene glycol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether, etc.), ethers (tetrahydrofuran, ethylene glycol dimethyl ether, propylene glycol dimethyl ether, tetrahydropyran, etc.), ketones (acetone, methyl ethyl ketone, Acetylacetone, etc.), esters (methyl acetate, ethylene glycol monomethyl monoacetate, etc.), amides (formamide, N-methylformamide, pyrrolidone, N-methylpyrrolidone, etc.), gamma-butyrolactone, methyl lactate, ethyl lactate, etc. it can. These solvents are used alone or in a mixed state. When preparing a coating solution, the concentration of the components of the ink receiving layer (total solids including additives) in the solvent is preferably 1 to 50% by weight. In addition, a film can be formed not only from the above-mentioned application from an organic solvent but also from an aqueous emulsion. In this case, the concentration is preferably 5% by weight to 50% by weight.

The thickness of the ink receiving layer in the present invention after coating and drying is not particularly limited, but may be 0.1 μm or more. When it is provided on a metal plate, it has a role as a heat insulating layer, so that it is preferably 0.3 μm or more. If the ink receiving layer is too thin, the heat generated will dissipate toward the metal plate, lowering the sensitivity. In addition, in the case of a hydrophilic metal plate, the ink receiving layer is required to have abrasion resistance, so that the printing durability cannot be ensured. When a lipophilic plastic film is used as the substrate, the ink receiving layer only has to function as an adhesive layer with the upper layer, so the coating amount may be smaller than that of the metal plate, and may be 0.05 μm. The above is preferred.

Next, a method of making the heat-sensitive lithographic printing plate precursor will be described. The lithographic printing plate precursor may be, for example, directly subjected to image-wise thermal recording by a thermal recording head or the like, or a solid laser or semiconductor laser emitting infrared rays having a wavelength of 700 to 1200 nm, or a high-intensity flash light such as a xenon discharge lamp. Light-to-heat conversion type exposure such as infrared lamp exposure can also be used.

The writing of an image may be performed by either a surface exposure method or a scanning method. In the former case, an infrared irradiation method,
This is a method of irradiating a short time light of high illuminance of a xenon discharge lamp onto an original plate to generate heat by light-heat conversion. When a surface exposure light source such as an infrared lamp is used, the preferable exposure amount varies depending on the illuminance, but the surface exposure intensity before modulation with a printing image is usually 0.1 to 10 J / cm ² . It is preferably in the range, more preferably in the range of 0.1 to 1 J / cm ² . If the support is transparent, it can be exposed through the support from the back side of the support. The exposure time is preferably selected such that the above-mentioned exposure intensity is obtained by irradiation of 0.01 to 1 msec, preferably 0.01 to 0.1 msec. When the irradiation time is long, it is necessary to increase the exposure intensity due to the competition between the heat energy generation rate and the generated heat energy diffusion rate.

In the latter case, a method is employed in which a laser light source containing a large amount of infrared components is used to modulate a laser beam with an image and scan the original plate. Examples of the laser light source include a semiconductor laser, a helium neon laser, a helium cadmium laser, and a YAG laser. Irradiation can be performed with a laser having a laser output of 0.1 to 300 W. When a pulse laser is used, it is preferable to irradiate a laser having a peak output of 1000 W, preferably 2000 W. In this case, the exposure amount is preferably such that the surface exposure intensity before modulation with the image for printing is in the range of 0.1 to 10 J / cm ² ,
More preferably, it is in the range of 0.3 to 1 J / cm ² .

The printing plate precursor of the present invention can be mounted on a printing press without further processing the image-exposed printing plate precursor. When you start printing with ink and water,
The overcoat layer is removed by the fountain solution, and at the same time the hydrophilic layer in the exposed area is removed. The ink is deposited on the ink receiving layer below the ink receiving layer, and printing is started.

[0097]

The present invention will be described in detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto.

Example 1 (Preparation of aluminum substrate) Copper was added to 99.5% by weight of aluminum, 0.01% by weight of titanium was added to 0.03% by weight,
JI containing 0.3% by weight of iron and 0.1% by weight of silicon
A roll of a 0.24 mm thick sheet of SA1050 aluminum material was converted to a 400 mesh pumice stone (manufactured by Kyoritsu Ceramics).
Weight percent aqueous suspension and a rotating nylon brush (6,10-
(Nylon) and the surface was grained, and then washed well with water. This was immersed in a 15% by weight aqueous sodium hydroxide solution (containing 4.5% by weight of aluminum), etched so that the amount of aluminum dissolved was 5 g / m ² , and washed with running water. Furthermore, neutralize with 1% by weight nitric acid,
Next, in a 0.7% by weight nitric acid aqueous solution (containing 0.5% by weight of aluminum), a rectangular wave alternating waveform voltage (current ratio r = 0.9) having an anode voltage of 10.5 volts and a cathode voltage of 9.3 volts was used.
0, current roughening described in Examples of Japanese Patent Publication No. 58-5796), and an electrolytic surface roughening treatment was carried out at an anode charge of 160 clones / dm ² . After washing with water, the substrate was immersed in a 10% by weight aqueous solution of sodium hydroxide at 35 ° C., etched so that the amount of aluminum dissolved was 1 g / m ² , and then washed with water. Next, it was immersed in a 30% by weight aqueous sulfuric acid solution at 50 ° C., desmutted, and washed with water. Further, a porous anodic oxide film forming treatment was performed in a 20% by weight aqueous sulfuric acid solution (containing 0.8% by weight of aluminum) at 35 ° C. using a direct current. That is, electrolysis is performed at a current density of 13 A / dm ² ,
Anodized film weight 2.7 g / m ² by adjusting electrolysis time
And The support was washed with water, immersed in a 0.2% by weight aqueous solution of sodium silicate at 70 ° C. for 30 seconds, washed with water and dried. The aluminum substrate obtained as described above had a reflection density measured by a Macbeth RD920 reflection densitometer of 0.30 and a center line average roughness of 0.58 μm.

(Synthesis of Organic Polymer for Ink Receiving Layer) In a 200 ml three-necked flask equipped with a stirrer, a condenser, and a dropping funnel, 4.61 g (0.0192 mole) of N- (p-aminosulfonylphenyl) methacrylamide was placed. 2.94 g (0.0258 mole) of ethyl methacrylate, 0.80 g (0.015 mole) of acrylonitrile and 20 g of N, N-dimethylacetamide were added, and the mixture was stirred while being heated to 65 ° C. in a hot water bath. 0.15 g of V-65 (manufactured by Wako Pure Chemical Industries, Ltd.) was added to the mixture, and the mixture was stirred for 2 hours under a nitrogen stream while maintaining the temperature at 65 ° C. The reaction mixture was further charged with N- (p
-Aminosulfonylphenyl) methacrylamide 4.6
1 g, 2.94 g of ethyl methacrylate, 0.80 g of acrylonitrile, N, N-dimethylacetamide and V-6
5 0.15 g of the mixture was added dropwise with a dropping funnel over 2 hours. After completion of the dropwise addition, the mixture was further stirred at 65 ° C. for 2 hours. After completion of the reaction, 40 g of methanol was added, and the mixture was cooled.
And stirred for 30 minutes, followed by filtration and drying to obtain 15 g of a white solid. The weight average molecular weight (polystyrene standard) of this N- (p-aminosulfonylphenyl) methacrylamide copolymer was measured by gel permeation chromatography and found to be 53,000.
It was.

(Preparation of Ink Accepting Substrate)
After dissolving 1 g of (p-aminosulfonylphenyl) methacrylamide copolymer in a mixed solution consisting of 1.3 g of methyl ethyl ketone / 23.1 g of propylene glycol monomethyl ether, the coating amount of the above aluminum substrate was 12 ml / m ^2. It was applied using a bar coater. Then, it was dried by heating at 100 ° C. for 1 minute to prepare an aluminum substrate having an ink receiving layer having a dry coating amount of about 0.4 g / m ² .

(Preparation of heat-sensitive lithographic printing plate precursor)
5% solution of poly-2-hydroxyethyl methacrylate (weight average molecular weight 250,000) in methyl alcohol 2
g, methanol silica (Nissan Chemical: 10 nm to 20 n)
A solution consisting of 3 g of a methanol solution containing 30% by weight of silica particles of m), 1.0 g of methyl lactate and 17.5 g of methanol was coated on the substrate coated with the above-mentioned ink receiving layer in an amount of 12 ml / m2. ² was applied. Dry at 100 ° C for 1 minute.
A 4 g / m ² hydrophilic layer was provided on the ink receiving layer. The value of the dynamic hardness of this hydrophilic layer was 32 mN / μm ² . On top of this, 1.5% of a 28% aqueous solution of gum arabic
g, the water-soluble cyanine dye described in the present specification (I-31)
An aqueous solution consisting of 0.042 g and 0.025 g of polyoxyethylene nonylphenyl ether was coated with an amount of coating liquid of 12 m.
1 / m ² . After the coating, the coating was dried at 100 ° C. for 2 minutes, and an overcoat layer having a dry coating weight of about 0.2 g / m ² was provided on the hydrophilic layer to prepare a heat-sensitive lithographic printing plate precursor.

(Exposure and Printing Evaluation) The above lithographic printing plate precursor was used as a trend setter 32 of CreoScitex.
It was mounted at 44 VX and irradiated with energy of 250 mJ / cm ² to form a latent image. At this time, no contamination of the optical system of the trend setter was observed. Next, the original plate on which the latent image was formed was attached to a Komori Lithrone printing machine, and printing was performed using a dampening solution and ink containing a 10% by volume aqueous solution of isopropyl alcohol containing an etchant. The exposed portion of the hydrophilic layer was removed, and 1
7,000 parts of a good printed matter free of stains were obtained.

Example 2 2 g of a 5% solution of poly-2-hydroxyethyl methacrylate (weight average molecular weight 250,000) in methyl alcohol of Example 1 was added to polyacrylic acid (weight average molecular weight 25
The same procedure as in Example 1 was carried out except that 2 g of a 5% solution of methyl alcohol (0,000) was used to obtain a heat-sensitive lithographic printing plate precursor. The value of the dynamic hardness of this hydrophilic layer is 21 mN /
μm ² . The obtained original plate is used as a trend setter 32
It was mounted at 44 VX and irradiated with energy of 200 mJ / cm ² to form a latent image. At this time, no contamination of the optical system of the trend setter was observed. Next, when mounted and printed on a Komori Lithrone printing machine in the same manner as in Example 1, the overcoat layer and the hydrophilic layer in the exposed area were removed in about 15 printed sheets, and 12,000 copies of a good, stain-free printed material were obtained. was gotten.

Example 3 The hydrophilic layer coating solution of Example 1 was replaced with methanol silica 2.2
g, a heat-sensitive lithographic printing plate precursor was obtained in the same manner as in Example 1 except that 0.81 g of a 12.7% by weight aqueous solution of a hydrolyzate of tetraethoxysilane, 1.0 g of methyl lactate and 11 g of methanol were used. . The value of the dynamic hardness of this hydrophilic layer was 42 mN / μm ² . The obtained original plate was attached to a trend setter 3244VX, and 300 mJ / cm ²
Was irradiated to form a latent image. At this time, no contamination of the optical system of the trend setter was observed. next,
When mounted and printed on a Komori Lithrone printing machine in the same manner as in Example 1, the overcoat layer and the hydrophilic layer in the exposed area were removed in about 40 prints, and 25,000 parts of a good printed product free of stains were obtained. Was.

Example 4 The coating solution for the hydrophilic layer of Example 1 was replaced with methanol silica 2.5
g, a heat-sensitive lithographic printing plate precursor was obtained in the same manner as in Example 1 except that g, methyl lactate 1.0 g and methanol 11.5 g were used. The value of the dynamic hardness of this hydrophilic layer is 27 mN.
/ Μm ² . Use the obtained original plate as a trend setter 3
It was mounted on a 244VX and irradiated with energy of 200 mJ / cm ² to form a latent image. At this time, no contamination of the optical system of the trend setter was observed. Next, when mounted and printed on a Komori Lithrone printing machine in the same manner as in Example 1, the overcoat layer and the hydrophilic layer in the exposed area were removed in about 25 printings, and 15,000 copies of good, stain-free printed matter were obtained. was gotten.

Example 5 N- (p-aminosulfonylphenyl) obtained in Example 1
1.0 g of the methacrylamide copolymer and 0.2 g of the photothermal conversion agent (I-35) described in this specification were mixed with 1.4 g of methyl ethyl ketone / propylene glycol monomethyl ether 2
A coating solution of the ink receiving layer dissolved in 5.6 g of the mixed solution was applied to the aluminum substrate obtained in Example 1 with a bar coater, and dried by heating at 100 ° C. for 1 minute. An aluminum substrate having an ink receiving layer of / m ² was prepared. The same hydrophilic layer and the overcoat layer as in Example 2 were provided on this substrate to obtain a heat-sensitive lithographic printing plate precursor. The value of the dynamic hardness of this hydrophilic layer is 2
It was 1 mN / μm ² . The obtained original plate was mounted on a trend setter 3244VX, and irradiated with energy of 180 mJ / cm ² to form a latent image. At this time, no contamination of the optical system of the trend setter was observed. Next, when mounted and printed on a Komori Lithrone printing machine in the same manner as in Example 1, the overcoat layer and the hydrophilic layer in the exposed area were removed in about 15 printed sheets, and 12,000 copies of a good, stain-free printed material were obtained. was gotten.

Comparative Example 1 The hydrophilic layer coating solution of Example 1 was prepared using methanol silica 1.25
g, polyacrylic acid (weight average molecular weight 250,000)
7.5 g of a 5% solution of methyl alcohol, methyl lactate 1.
A heat-sensitive lithographic printing plate precursor was obtained in the same manner as in Example 1, except that 0 g and 5.25 g of methanol were used. The value of the dynamic hardness of this hydrophilic layer was 14 mN / μm ² .
The obtained original plate was mounted on a trend setter 3244VX, and irradiated with energy of 200 mJ / cm ² to form a latent image. At this time, no contamination of the optical system of the trend setter was observed. Next, when attached to a Komori Lithrone press and printed in the same manner as in Example 1, the hydrophilic layer was worn out at 500 parts, the ink receiving layer was exposed, and the non-image area was stained.

Comparative Example 2 A heat-sensitive lithographic printing plate precursor was obtained in the same manner as in Example 3 except that the overcoat layer was not provided. The value of the dynamic hardness of this hydrophilic layer was 42 mN / μm ² .
When the obtained original plate was mounted on a trend setter 3244VX and irradiated with energy of 400 mJ / cm ² , contamination of the optical system of the trend setter was observed, and it was necessary to clean the lens.

[0109]

According to the present invention, it is possible to perform scanning exposure in a short time, and furthermore, it is possible to directly mount and print on a printing machine without performing a developing process, and it is excellent in printing durability. ,
It is possible to provide a heat-sensitive lithographic printing plate precursor that is free from stains during printing. Further, it is possible to provide a heat-sensitive lithographic printing plate precursor in which ablation (scattering) of the hydrophilic layer during laser exposure is suppressed, and the exposure apparatus and light source are less contaminated.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) G03F 7/11 501 G03F 7/11 501 F term (Reference) 2H025 AA00 AA01 AA12 AB03 AC08 AD01 BH03 CC11 CC20 DA01 DA36 DA37 FA10 2H096 AA06 BA01 EA04 EA23 2H114 AA04 AA22 AA24 AA30 BA01 BA10 DA05 DA08 DA51 DA52 DA53 EA01 EA03 EA04 GA03 GA05 GA06 GA08 GA09 GA34 GA36 GA38

Claims (3)

[Claims] 1. A hydrophilic layer whose exposed portion is easily removed by a fountain solution or ink at the time of printing on a substrate having an ink-receiving surface or coated with an ink-receiving layer, and a water-soluble overcoat. A heat-sensitive lithographic printing plate precursor having a coating layer in this order, wherein at least one of the hydrophilic layer, the ink receiving layer and the overcoat layer contains a light-to-heat conversion agent, wherein the dynamic hardness of the hydrophilic layer is 20 mN / μm. A heat-sensitive lithographic printing plate precursor characterized in that the number is ² or more. 2. The method according to claim 1, wherein the hydrophilic layer is beryllium, magnesium,
2. A colloid of at least one compound selected from oxides or hydroxides of aluminum, silicon, titanium, boron, germanium, tin, zirconium, iron, vanadium, antimony and transition metals. The heat-sensitive lithographic printing plate precursor as described in the above. 3. The method according to claim 1, wherein the hydrophilic layer is beryllium, magnesium,
Aluminum, silicon, titanium, boron, germanium, tin, zirconium, iron, vanadium, antimony and at least one compound selected from oxides or hydroxides of transition metals, and a hydrophilic resin,
3. The heat-sensitive lithographic printing plate precursor according to claim 1, wherein the content of the hydrophilic resin is not more than 20% by weight of the solid content of the hydrophilic layer.