JPH11263082A - Manufacture of photo-lithographic printing plate and carrier for photo-lithographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve an erasing property at the time of erasing unnecessary image line parts with erasing liquid by providing a photo-composition layer after treating the carrier by cation-containing treatment liquid in matter with a photo-composition layer provided on an aluminum carrier subjected to a roughened surface treatment and an anode oxidation treatment. SOLUTION: A printing plate is manufactured from a photo-lithographic printing plate (PS), and at this time, a film manuscript is passed through the PS plate to subsequently be developed with alkali-developing liquid before removing nonimage parts, and thereafter cleaning and drying processes are carried out, and photo-layers left by being undeveloped at the back of film edges or dust are removed by removing liquid. Such a PS plate is formed by furnishing a photo-composition layer on an aluminum carrier subjected to a roughened surface treatment and an anode oxidation treatment; however in this instance, the aluminum-containing carrier is treated by cation-containing treatment liquid, followed by providing a photo-composition layer, thus improving an erasing property at the time of erasing unnecessary image line parts with erasing liquid, and preventing the occurrence of any trace of erasing marks.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a photosensitive lithographic printing plate and a support for the photosensitive lithographic printing plate.

[0002]

2. Description of the Related Art Usually, when a printing plate is prepared from a photosensitive lithographic printing plate (hereinafter, also referred to as a PS plate), an image is exposed through a film original to the PS plate, and then developed with an alkaline developer to develop a non-image area. After the cleaning, a washing and drying process is performed, and an operation of removing the photosensitive layer which remains behind the film edge and dust without being developed by the erasing liquid is performed. The erasing liquid is usually composed of an acidic substance, a solvent, a thickener, and the like.However, in recent years, available solvents have been limited due to an increase in environmental and safety consciousness, and erasing is insufficient with a conventional printing plate. And other inconveniences.

[0003] For example, Japanese Patent Application Laid-Open No. 60-149491 discloses
And JP-A-60-149491 disclose a method of treating a roughened and anodized aluminum support with a substance having an amino group and an acidic group before providing a photosensitive composition layer on the aluminum support. Although it has been proposed, even with this processing method, good erasing with the above erasing liquid is not achieved, there are many erasing traces, and the change in the grain color before and after erasing is large. There is a problem that it is difficult to confirm the situation.

In preparing a printing plate from the PS plate, after exposing the PS plate to an image through a film original,
A process of developing with an alkaline developer to remove the non-image portion is performed. At this time, since the support is made of aluminum, the aluminum is dissolved by touching the alkaline developer, and the dissolved component is contained in the developer. There is a problem that sludge is generated by reacting with the components, thereby shortening the life of the developer.

[0005] For example, Japanese Patent Application Laid-Open No. 2-107490 discloses a technique of treating a roughened and anodized aluminum support with an alkali metal silicate having a pH of 11.5 to 13.0 at 25 ° C. Is disclosed in JP-A-2-185493.
Japanese Patent Application Publication No. JP-A-2005-26095 discloses a roughened and anodized aluminum support having a pH of 11.5 to 13.0 and a specific gravity of 1.02 to 1.02.
1.17, a technique of treating with an alkali metal silicate having a conductivity of 35 to 180 ms / cm is disclosed in JP-A-5-27836.
In Japanese Patent Publication No. 2 (1993), etc., a roughened and anodized aluminum support is treated with an alkali metal silicate having a pH of 11.5 to 13.0 at 25 ° C., and then treated with an acidic aqueous solution having a pH of 1 to 6. Techniques for manufacturing a PS plate by providing a photosensitive layer on a lever and, if necessary, providing a hydrophilic undercoat layer before providing the photosensitive layer have been proposed. It describes that the printing plate has printing durability and the dissolution of an aluminum support in a developer is suppressed.

However, although the dissolution of the aluminum support at the time of development is suppressed to some extent by the above-mentioned technique, a problem arises in that the non-image area after development is dyed blue and plate inspection becomes difficult. Further, since the surface of the aluminum support before providing the photosensitive layer is made hydrophilic by the silicate treatment, there is a problem that the adhesion to the hydrophobic photosensitive layer is weakened and the printing durability becomes insufficient.

[0007]

SUMMARY OF THE INVENTION The present invention has been proposed based on the above-mentioned circumstances, and a first object of the present invention is to erase unnecessary image portions with an erasing liquid in a process of producing a printing plate from a PS plate. An object of the present invention is to provide a method for producing a PS plate which is excellent in erasability and does not cause erasure traces.

Further, a second object is to prevent the dye from remaining in the non-image area after the development of the PS plate, to facilitate the plate inspection, and to obtain an aluminum support obtained by roughening. An object of the present invention is to provide a method for producing a PS plate having good adhesion to a photosensitive layer and excellent printing resistance of a lithographic printing plate.

A third object is to provide an excellent erasability when erasing unnecessary image portions with an erasing liquid in a step of preparing a lithographic printing plate from a PS plate, and to prevent erasure traces from remaining. In addition, the present invention provides a PS plate support that has no dye residue on a non-image area after development, is easy to inspect, has excellent adhesion to a photosensitive layer, and has excellent printing resistance. Is to do.

[0010]

The first and second aspects of the present invention are described.
The third object is achieved by the following configuration.

1. In a method for producing a photosensitive lithographic printing plate comprising providing a layer of a photosensitive composition on a roughened and anodized aluminum support, after treating the aluminum support with a processing solution containing a cation, A method for producing a photosensitive lithographic printing plate, comprising providing a layer of a photosensitive composition.

2. A method for producing a photosensitive lithographic printing plate comprising providing a layer of a photosensitive composition on an aluminum support that has been subjected to a surface roughening treatment, an anodic oxidation treatment and then an alkali metal silicate treatment, wherein the aluminum support contains a cation. A method for producing a photosensitive lithographic printing plate, comprising providing a layer of a photosensitive composition after treating with a treating solution.

3. After the alkali metal silicate treatment, the amount of the alkali metal detected from the surface of the aluminum support after the treatment with the treatment solution containing cations is reduced from that before the treatment, and contained in the treatment liquid detected from the support surface. A method for producing a photosensitive lithographic printing plate, characterized by increasing the amount of an element corresponding to the cation to be produced.

4. In a method for producing a photosensitive lithographic printing plate comprising a surface roughening treatment, an anodizing treatment, and a layer of a photosensitive composition provided on an aluminum support that has been subsequently treated with an alkali silicate, a treatment used for the alkali silicate treatment The photosensitive lithographic printing wherein the solution contains cations other than alkali metal ions, and the ratio of cations other than alkali metal ions to all cations in the treatment solution is in the range of 0.01 to 1.0. Plate production method.

[0015] 5. The cation has 2 to 20 carbon atoms.
It is an organic basic substance of Claim 1 characterized by the above-mentioned.
5. The method for producing a photosensitive lithographic printing plate according to any one of 4.

6. The method according to any one of claims 1 to 4, wherein the cation is a divalent or higher valent metal ion.

[7] The method for producing a photosensitive lithographic printing plate according to claim 6, wherein the divalent or higher valent metal ion is an alkaline earth metal ion.

[8] In a support for a photosensitive lithographic printing plate which has been subjected to a surface roughening treatment, an anodizing treatment, and then at least an alkali silicate treatment, the total amount of nitrogen atoms and alkaline earth metals detected from the support surface is determined to be an alkali metal. A support for a lithographic printing plate, characterized in that the amount is greater than the amount of

Hereinafter, the present invention will be described in detail.

The method for producing a PS plate of the present invention and the support for the PS plate obtained by the method are provided by a method for treating an aluminum support for producing the PS plate and the PS plate obtained by the treatment method. There is a characteristic in the support for use. That is, in Claims 1, 5 to 7, the aluminum support is subjected to a roughening treatment and anodizing treatment, and then treated with a treatment solution containing a cation. After performing a roughening treatment, an anodizing treatment, and a treatment with an alkali metal silicate treatment solution, a treatment with a treatment solution containing a cation is performed. After treatment with an alkali metal silicate treatment solution containing a cation, a photosensitive layer is provided and P
I try to get the S version. Claim 8 defines a PS plate obtained by the manufacturing method of claims 2 to 7.

[Method for Producing PS Plate According to Claims 1, 5 to 7] In the method for producing a PS plate according to the present invention described in claims 1, 5 to 7, the method for producing a PS plate according to the present invention to be described later is used. After the surface roughening treatment and the anodic oxidation treatment in the step, the aluminum support is treated with a treatment solution containing the following cations before providing the photosensitive layer. Is from 2 to 20 carbon atoms
In the above claim 6, a divalent or higher valent metal ion is preferably used as the cation. In the above claim 7, the divalent or higher valent metal ion is preferably used as the alkaline earth metal. Ions are used.

<Examples of organic basic substance having 2 to 20 carbon atoms as cation> Specific examples of the organic basic substance having 2 to 20 carbon atoms include trialkylamine, trimethylamine, triethylamine and triethylamine. −
n-propylamine, dipropylamine, dibutylamine, dicyclohexylamine, N-methylcyclohexylamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetra-n-propylammonium hydroxide, tetra-n-pentylammonium hydroxide, Choline hydroxide, butyldimethylamine, propylamine, butylamine, pentylamine, cyclohexylamine, dimethylbenzylamine, diethylethanolamine, aminodiethylethanolamine, dimethylethanolamine, methyldiethanolamine, methylethanolamine, pyrrolidine, picoline, pyridine, piperidine , Methylpiperidine, dimethylpiperazine, ethylenediamine, ethyleneurea, tetramethylethylenediamine, tet Methyl propylene diamine, can be exemplified quinuclidine and the like.

Here, when the number of carbon atoms of the basic substance of the present invention is less than 2, when an unnecessary image portion is erased with an erasing liquid in the step of preparing a lithographic printing plate from a PS plate, the erasability becomes poor. It is bad and easily causes an erased trace. Even when the number of carbon atoms exceeds 20, the erased trace tends to be generated.

Further, in the method for producing a PS plate of the present invention according to any one of the first to fifth aspects of the present invention, for example, a lower alcohol such as methanol, ethanol or propanol, or a mixed solution thereof may be mixed with the organic basic compound. A processing solution obtained by dissolving the substance to a concentration of preferably 0.1 to 5% by weight is used. The processing solution is immersed in an aluminum support after anodic oxidation, shower-supplied, and coated using the processing solution. Is done. Further, at the time of treatment with the treatment liquid, the surface of the aluminum support and / or the treatment liquid is preferably treated at 10 to 80%.
It may be cooled / heated to ℃, and the treatment time is preferably about 0.1 seconds to 3 minutes. If necessary, after the treatment with the treatment liquid, it is preferable to wash with water or alcohol, and then dry.

In the present invention, the cation may be a divalent or higher valent metal ion. Examples of the divalent or higher valent metal ion include Mg ²⁺ , Ca ²⁺ , Zn ²⁺ , Sr ²⁺ , Cd
²⁺ , Ba ²⁺ , Cu ²⁺ , Al ³⁺ , Sc ³⁺ , Ga ³⁺ , T
and polyvalent metal ions such as l ³⁺ and Pb ⁴⁺ , and more preferably Mg ²⁺ , Ca ²⁺ , Zn ²⁺ , Sr ²⁺ , Cd ²⁺ , Ba
Alkaline earth metal ions such as ²⁺ are preferable, and monovalent metal ions, that is, alkali metal ions, result in poor erasability with the erasing solution.

In the treatment using a metal ion having a valence of 2 or more as the cation, an aqueous solution containing 0.1 to 5% by weight of the metal ion having a valence of 2 or more is preferable as the treatment liquid. The same applies to the case of the organic basic substance.

The pH may be adjusted by adding another acid or base to the treatment liquid.

The method according to any one of claims 1 to 5, further comprising the step of treating with a treatment solution containing the cation.
The S plate manufacturing process will be described below.

<Production process of PS plate> The aluminum support material used in the production method of the PS plate of the present invention includes:
An aluminum plate or an aluminum alloy plate is used, and the alloy of the aluminum alloy plate may be any material that can be used as a plate material of a lithographic printing plate, such as silicon, copper, manganese, chromium, zinc, lead, bismuth, nickel, An alloy of a metal such as titanium, sodium or iron and aluminum is used.

The aluminum plate and aluminum alloy plate (hereinafter, also referred to as aluminum plate) are preferably subjected to a degreasing treatment to remove oils, fats, rust, dust, etc. on the surface of the aluminum plate prior to surface roughening. . As the degreasing treatment, solvent degreasing using a solvent such as trichlene or thinner, emulsion degreasing treatment using an emulsion of kerosene, triethanol or the like can be used. In addition, an alkaline aqueous solution such as caustic soda can be used to remove stains and natural oxide films that cannot be removed only by the above degreasing treatment. When an alkaline aqueous solution such as caustic soda is used for the degreasing treatment, smut is formed on the surface of the support. In this case, phosphoric acid, nitric acid, sulfuric acid,
It is preferable to perform desmut treatment by dipping in an acid such as chromic acid or a mixed acid thereof.

The aluminum plate subjected to the degreasing treatment and the desmutting treatment as necessary is subjected to a roughening treatment.
Electrochemical surface roughening is important as the surface roughening method, but mechanical surface roughening may be used in combination. In the above-mentioned electrochemical graining, the applied voltage is preferably 1 to 50 V, more preferably 2 to 30 V. Further, an alternating waveform current such that the quantity of electricity at the anode (Qa) is larger than the quantity of electricity at the cathode (Qc) is added, and the current density at the anode is 10-15.
It is preferable to perform electrolytic surface roughening under the conditions of 0 A / dm ² , preferably 20 to 100 A / dm ² .

The alternating waveform current is a waveform obtained by alternately exchanging positive and negative polarities.
Any shape can be used as long as it increases. Qa and Qc are 100-100
0 coulomb / dm ² is preferred. The temperature of the acidic electrolyte is preferably from 10 to 50 ° C, more preferably from 15 to 45 ° C. The acid used for the acidic electrolyte is preferably hydrochloric acid or nitric acid, particularly nitric acid, and its concentration is preferably 0.01 to 5% by weight.

If necessary, nitrate, chloride, amines, aldehydes, phosphoric acid, chromic acid, boric acid, acetic acid, oxalic acid, etc. can be added to the acidic electrolyte.

Regarding the electrochemical surface roughening, for example, JP-B-48-28123, UK Patent No. 896563
This method is described in JP-A-53-67507, and these methods can be applied in the present invention. Alternatively, a method of electrolytically treating the surface with a direct current in an acidic electrolytic solution containing hydrochloric acid or nitric acid may be used.

As the mechanical surface roughening method used in combination with the electrochemical surface roughening method, for example, a method such as ball polishing, brush polishing, blast polishing, buff polishing, and honing polishing can be used. Among them, brush polishing and / or honing polishing are preferable. Further, roughening can be performed by bonding a sheet which has been roughened in advance to the surface of the support, and applying pressure to transfer the rough surface pattern. Surface treatment is performed.

When a plurality of surface roughening treatments are performed as described above, it is preferable to perform a chemical etching treatment by dipping in an aqueous acid or alkali solution between each surface roughening treatment. Examples of the acid include sulfuric acid, persulfuric acid, hydrofluoric acid, phosphoric acid, nitric acid, and hydrochloric acid, and examples of the base include sodium hydroxide and potassium hydroxide. Among these, it is preferable to use an aqueous alkali solution. The chemical etching treatment is performed using a 0.05 to 40% by weight aqueous solution of these acids or alkalis,
It is preferable to carry out the treatment at a liquid temperature of 5 ° C. for 5 to 300 seconds.

When a chemical etching treatment by immersion in an aqueous alkali solution is performed, a smut is formed on the surface of the aluminum plate. Therefore, the aluminum plate is subjected to an acid such as phosphoric acid, nitric acid, sulfuric acid, chromic acid, or a mixed acid thereof. It is preferable to perform immersion and desmut treatment.

The roughened aluminum plate is then subjected to an anodic oxidation treatment. As the electrolytic solution used for the anodic oxidation treatment, any one can be used as long as it forms a porous oxide film. In general, sulfuric acid, phosphoric acid, oxalic acid, chromic acid, sulfamic acid, benzenesulfonic acid, etc., or a mixture thereof. Although a mixed acid of a combination of more than two kinds is used, in the present invention, an electrolyte mainly containing sulfuric acid is preferable. Anodizing treatment conditions vary depending on the electrolytic solution used, and thus cannot be specified unconditionally. However, in general, the concentration of the electrolytic solution is 1 to 80% by weight, the temperature is 5 to 70 ° C,
Appropriate conditions are a current density of 1 to 60 A / dm ² , a voltage of 1 to 100 V, and an electrolysis time of 10 seconds to 5 minutes. Preferred is a sulfuric acid method, which is usually treated with a direct current, but an alternating current can also be used. The concentration of sulfuric acid is 10 to 50% by weight, the temperature is 20 to 50 ° C, and the current density is 20 to ² at a current density of 1 to 20 A / dm ² .
Preferably, the electrolytic treatment is performed for 50 seconds. Preferably, the electrolyte contains aluminum ions.

The anodized aluminum plate may be subjected to a sealing treatment using a silicate treatment liquid, if necessary. If necessary, the aluminum plate that has been subjected to the sealing treatment is treated with a treatment solution containing the basic substance, which is a feature of the present invention, to obtain the aluminum support of the present invention.

Incidentally, a hydrophilic layer may be further provided on the obtained aluminum support of the present invention. For forming the hydrophilic layer, the alkali metal silicate described in U.S. Pat. No. 3,181,461, U.S. Pat.
No. 426, the hydrophilic cellulose described in JP-B-6-426.
Amino acids and salts thereof described in JP-A-94234 and JP-B-6-2436, amines having a hydroxyl group and salts thereof described in JP-B-5-32238, and JP-A-62-19494. Phosphate, JP-A-59
For example, a polymer compound containing a monomer unit having a sulfo group described in JP-A-10-16551 can be used.

Further, in order to prevent abrasion of the photosensitive layer at the time of superposition in the case of a photosensitive lithographic printing plate, and to prevent elution of an aluminum component into a developing solution during development. JP-A-50-151136 and JP-A-5-151136
JP-A-7-63293, JP-A-60-73538, JP-A-61-67863, JP-A-6-35174, etc. perform a process of providing a protective layer on the back surface of a support. be able to.

The PS plate of the present invention can be obtained by providing a photosensitive layer on the aluminum support obtained as described above.

[Method of producing PS plate according to claims 2, 3, 5 to 7] The PS according to claims 2, 3, 5 to 7 of the present invention.
The method of producing a plate is characterized in that the surface of an aluminum support is subjected to a surface roughening treatment, an anodic oxidation treatment, a treatment with an alkali metal silicate treatment liquid, and then a treatment liquid containing a cation. In other words, except that after the anodizing treatment and before the cation treatment, a treatment with an alkali metal silicate treatment solution is performed.
It is the same as in the case of the method for producing the S plate, and an organic basic substance having 2 to 20 carbon atoms or a divalent or higher valent metal ion is preferably used as the cation.

As the alkali metal silicate treatment liquid,
The molar ratio of SiO ₂ / M ₂ O (M represents an alkali metal) is 3.0 to 4.0, and the concentration of the alkali metal silicate is 0.0
An alkali metal silicate aqueous solution of 5 to 0.5% by weight is used. The immersion conditions for the hydrophilization treatment with the aqueous alkali metal silicate solution include, for example, an alkali metal silicate aqueous solution having a pH of 9 to 12 at 25 ° C.
It is preferred to soak for ~ 90 seconds. As the alkali metal silicate, sodium silicate, potassium silicate and the like are used. Also, a small amount of hydroxide may be added to adjust the pH.

Further, as a more preferred embodiment of the present invention as defined in claim 3, the surface of the aluminum support is roughened, anodized, treated with an alkali metal silicate treatment solution and treated with cations. When producing an aluminum support by treating with a treatment solution containing, reducing the amount of alkali metal detected from the aluminum support surface after treatment with the treatment solution containing the cation than before treatment with the cation, Further, it is obtained by processing so as to increase the amount of the element corresponding to the cation contained in the treatment liquid detected from the surface of the aluminum support after the treatment with the treatment liquid containing the cation as compared to before the treatment with the cation. A PS plate is manufactured by providing a layer of the photosensitive composition on the aluminum support thus prepared. As a result, a PS plate having better erasing properties and printing durability with an erasing liquid can be obtained.

Here, when the amount of the alkali metal detected from the surface of the aluminum support after the treatment with the treatment solution containing the cation is increased as compared with that before the treatment with the cation, the erasing ability by the erasing solution is increased. And no improvement in printing durability. Further, when the amount of the element corresponding to the cation contained in the treatment liquid detected from the surface of the aluminum support after the treatment with the treatment liquid containing the cation does not increase as compared to before the treatment with the cation, the above-described method is also used. No improvement in erasability and printing durability is observed with the erasing liquid.

The amount of the alkali metal detected from the surface of the aluminum support before and after the treatment with the treatment solution containing the cation according to claim 3 and the amount of the alkali metal detected from the surface of the aluminum support before and after the treatment with the treatment solution containing the cation. The measurement of the amount of the element corresponding to the cation contained in the processing solution to be performed was performed by XPS measurement under the following conditions.

Resolution: 1.5 to 1.7 eV (resolution is:
(Defined by the half-width of a clean Ag3d5 / 2 peak).

Quantitative method: The obtained spectrum was analyzed by VAMA
COMMON DATA made by S-SCA-JAPAN
PROCESSING SYSTEM Ver. 2.3
Hereafter (hereinafter referred to as VAMAS software), the VA
After conversion to the format of the MAS software, calibration of the Count Scale is performed for each element, and a 5-point smoothing process is performed. The peak area intensity (cps x
eV). The atomic number concentration (at.%) Of each element is determined using the following sensitivity coefficients.

Al2p: 0.570, Ca2p: 5.1
30, K2s: 1.950, Mg2s: 0.525, N
a1s: 7.990, Si2p: 0.865, N1s:
1.770 [Method for producing PS plate according to claims 4 to 7] The method for producing a PS plate according to claims 4 to 7 is characterized in that when performing silicate treatment after anodizing treatment, The treatment liquid used for the silicate treatment contains cations other than alkali metal ions, and alkali metal ions (Li ⁺ , Na ⁺ , K ⁺ , Rb ⁺ , Cs ⁺ ,
It is characterized in that the amount of cations other than alkali metal ions is in the range of 0.01 to 1.0 with respect to all cations including Fr ⁺ ). If the amount of cations other than alkali metal ions with respect to all cations including alkali metal ions in the processing solution is less than 0.01, the effect of improving the residual dye of the PS plate after development becomes insufficient, and if it exceeds 1.0, The hydrophilicity of the surface is reduced, and stains are likely to occur during printing. When the amount of cations other than alkali metal ions with respect to all cations including alkali metal ions in the treatment liquid exceeds 1.0, the hydrophilicity of the surface also decreases,
Smears easily occur during printing.

The cations other than the alkali metal ions are the same basic organic cations as in the method for producing a PS plate according to any one of claims 1 to 5, preferably 2 to 20 carbon atoms. Alternatively, a divalent or higher valent metal ion can be used.

[Support for PS plate according to claim 8] The support for PS plate according to claim 8 of the present invention is the support according to claim 2.
A support obtained by the production method described in any one of (1) to (7), wherein the total amount of nitrogen atoms and alkaline earth metals detected from the surface of the support is larger than the total amount of alkali metals. When the total amount of nitrogen atoms and alkaline earth metals detected from the support surface is less than the total amount of alkali metals, a dye residue easily occurs, and when the total amount is larger than the total amount of alkali metals, an effect of improving the dye residue is obtained. be able to.

The amounts of nitrogen atoms, alkaline earth metals and alkali metals detected from the surface of the support correspond to cations in the case of the method for producing a PS plate support according to the third aspect. It is measured by a method similar to the method for detecting the amounts of elements and alkali metals.

The state in which the total amount of nitrogen atoms and alkaline earth metals detected from the surface of the support is larger than the amount of alkali metal can be obtained by the production method according to any one of claims 2 to 7.

On the support for PS plate (including the support according to claim 8) obtained by the production method of claims 1 to 7, a layer of a photosensitive composition described below (hereinafter also referred to as a photosensitive layer). )
Are formed to obtain the PS plate of the present invention.

<Formation of Photosensitive Layer> The PS plate of the present invention can be obtained by coating and processing the following photosensitive composition on an aluminum support to form a photosensitive layer. As the photosensitive composition,
For example, a positive photosensitive composition containing an o-quinonediazide compound as a photosensitive component, a negative photosensitive composition containing a photosensitive diazonium salt or a photosensitive azide compound as a photosensitive component, an ethylenically unsaturated double polymerizable by addition polymerization. Examples thereof include a photopolymerizable composition containing a compound having a bond as a main component and a negative photosensitive composition containing a photocrosslinkable compound containing a cinnamic acid or a dimethylmaleimide group as a photosensitive component. As the photosensitive composition, Japanese Patent Application Nos. 8-151036 and 7-2.
Those described in 31444 are preferred.

<Treatment of PS Plate with Erasing Solution> In a lithographic printing plate, for example, a lithographic printing plate manufactured by photolithography, an unnecessary image which is inevitably generated or an image portion which needs to be deleted and corrected is generated. So it needs to be fixed. For example, unnecessary image portions are generated based on overexposure and underexposure generated on the printing plate surface due to dirt, scratches, cuts, etc. of the original film, and it is necessary to correct them.

Erasing liquids for removing unnecessary image portions of the lithographic printing plate are disclosed in, for example, JP-A-54-89806 and JP-B-5-2231, but are preferably used in the present invention. As the solvent of the erasing liquid to be used, for example, lactones, ethers, ketones, alcohols and the like are preferably used. The lactones include butyrolactone, valerolactone, and hexanolactone, and the ethers include glycol ethers.
For example, glycol monoalkyl ethers such as 2-methoxyethanol, 2-ethoxyethanol, 2-isopropoxyethanol, and 2-butyl glycol, for example, 2
-Glycol monoaryl ethers such as phenylethanol, for example, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monoalkyl ethers such as diethylene glycol monoisobutyl ether, such as triethylene glycol monomethyl ether , Triethylene glycol monoethyl ether, triethylene glycol monoalkyl ethers such as triethylene glycol monobutyl ether,
For example, ethylene glycol dialkyl ethers such as ethylene glycol dimethyl ether, and diethylene glycol dialkyl ethers such as diethylene glycol diethyl ether such as diethylene glycol dimethyl ether and diethylene glycol diethyl ether are included. Ketones include, for example, methyl ethyl ketone, methyl propyl ketone, diethyl ketone, methyl butyl ketone, methyl isobutyl ketone, ethyl butyl ketone, butyrone, methyl amyl ketone, methyl hexyl ketone, valerone, mesityl oxide, diacetone alcohol, cyclohexanone, methyl Cyclohexanone,
Acetophenone, isophorone, acetylacetone, acetonylacetone and the like are included. As alcohols,
For example, methanol, ethanol, butanol, octyl alcohol, benzyl alcohol and the like can be mentioned. Besides these, N, N-dimethylformamide, tetrahydrofuran, dioxane, N-methylpyrrolidone, dimethylsulfoxide and the like can also be mentioned.

The solvent is used in an amount of 20 to 90% by weight, more preferably 30 to 85% by weight, based on the total weight of the erasing liquid of the present invention.
It is appropriate to contain in the range of.

The erasing solution used in the present invention may contain a surfactant, if necessary. The surfactant promotes better penetration of the components contained in the erasing solution used in the present invention into the image area of the lithographic printing plate, and furthermore, the components contained in the erasing solution are well mixed and stable. It is effective to be able to form a suitable solution. Such surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers,
Polyoxyethylene polystyryl phenyl ether, polyoxyethylene polyoxypropylene alkyl ether, glycerin fatty acid partial ester, sorbitan fatty acid partial ester, pentaerythritol fatty acid partial ester, propylene glycol monofatty acid ester, sucrose fatty acid partial ester, oxyethylene Oxypropylene block copolymer, polyoxyethylene sorbitan fatty acid partial ester, polyoxyethylene sorbitol fatty acid partial ester, polyethylene glycol fatty acid ester, polyglycerin fatty acid partial ester, polyoxyethylated castor oil, polyoxyethylene glycerin fatty acid partial ester , Fatty acid diethanolamides, N, N-bis-2-hydroxyalkylamines, polyoxo Nonionic surfactants such as ethylene alkylamine, triethanolamine fatty acid ester, and trialkylamine oxide, fatty acid salts, avicenates, hydroxyalkanesulfonates, alkanesulfonates, dialkylsulfosuccinates, straight-chain Alkyl benzene sulfonates, branched-chain alkyl benzene sulfonates, alkyl naphthalene sulfonates, alkyl phenoxy polyoxyethylene propyl sulfonates, polyoxyethylene alkyl sulfophenyl ether salts, N-methyl-N-oleyltaurine sodium, N- Alkylsulfosuccinic acid monoamide disodium salts, petroleum sulfonates,
Sulfated castor oil, sulfated beef leg oil, fatty acid alkyl ester sulfates, alkyl sulfates, polyoxyethylene alkyl ether sulfates,
Fatty acid monoglyceride sulfates, polyoxyethylene alkyl phenyl ether sulfates, polyoxyethylene styryl phenyl ether sulfates, alkyl phosphates, polyoxyethylene alkyl ether phosphates, polyoxyethylene alkyl phenyl ether phosphate Anionic surfactants such as ester salts, partially saponified styrene-maleic anhydride copolymers, partially saponified olefin-maleic anhydride copolymers, and naphthalenesulfonate formalin condensates; alkylamine salts , Quaternary ammonium salts, polyoxyethylene alkylamine salts, cationic surfactants such as polyethylene polyamine derivatives, carboxybetaines, aminocarboxylic acids,
Examples include amphoteric surfactants such as sulfobetaines, aminosulfates, and imidazolines. Among the surfactants mentioned above, the term "polyoxyethylene" can be read as a polyoxyalkylene such as polyoxymethylene, polyoxypropylene, or polyoxybutylene.

Of these, a nonionic surfactant and an anionic surfactant are preferable, and a surfactant having an HLB of 9 or more is more preferable because the components contained in the correction liquid are mixed well. Further, polyoxyethylene alkyl phenyl ethers, oxyethylene oxypropylene block copolymer, polyoxyethylene sorbitan fatty acid partial ester, polyoxyethylene sorbitol fatty acid partial ester, polyerythylene glycol fatty acid ester, polyglycerin fatty acid partial ester,
This is preferable because the effect of eliminating the image portion of the erasing liquid is improved.

Most preferred are oxyethylene oxypropylene block copolymers. These surfactants may be used alone or as a mixture of two or more kinds, and are contained preferably in the range of 1 to 40% by weight, more preferably 3 to 25% by weight, based on the total weight of the erasing liquid according to the present invention. .

The erasing liquid used in the present invention can contain a coloring agent, an acidic substance, water, a viscosity modifier and the like in addition to the above components.

The colorant can be contained when visual contrast is desired. Specifically, for example, dyes such as crystal violet, safranin, brilliant blue, malachite green, and acid rhodamine B, as well as inorganic pigments and organic pigments There are pigments and the like. These coloring agents are used in an amount of 0.000 to the total weight of the erasing solution used in the present invention.
1 to 0.05% by weight, preferably 0.001 to 0.01
It is used in the range of weight%.

Examples of the acidic substance include hydrofluoric acid, hydrochloric acid,
Inorganic acids such as sulfuric acid, persulfuric acid, nitric acid, permanganic acid, phosphoric acid, borofluoric acid, hydrofluoric acid, acetic acid, citric acid, malic acid, lactic acid, oxalic acid, trichloroacetic acid, tannic acid, phytic acid Organic acids such as p-toluenesulfonic acid and phosphonic acid and salts thereof and the like. Of these acidic substances, hydrofluoric acid, phosphoric acid, borofluoric acid or salts thereof are preferred for improving the correcting effect. These acidic substances can be used alone or in combination of two or more, and preferably 0.1 to 1 based on the total weight of the erasing solution.
The content is 5% by weight, more preferably in the range of 0.3 to 8.0% by weight.

As for water, in addition to those which are inevitably added to the above-mentioned erasing solution by adding various compounds such as an acid containing a water component in the structure, those which are selectively added to the erasing solution are also used. Good. The preferred amount of addition is 1 to 30% by weight, more preferably 3 to 20% by weight, based on the total weight of the erasing liquid.

Examples of the viscosity modifier include inorganic thickeners such as fine silica powder, modified cellulose such as methylcellulose, hydroxypropylmethylcellulose and sodium carboxymethylcellulose, gum arabic, polyvinylpyrrolidone, polyvinylmethylether, polyethylene glycol, and the like. Polymer compounds such as polypropylene glycol, vinyl methyl ether-maleic anhydride copolymer, and vinyl acetate-maleic anhydride copolymer are exemplified. Among them, modified cellulose, polyvinylpyrrolidone and the above-mentioned two types of maleic anhydride copolymer are preferred, and most preferred are modified cellulose such as hydroxypropylmethylcellulose and polyvinylpyrrolidone. These viscosity modifiers can be used alone or as a mixture of two or more kinds, and the amount of addition can be changed so as to obtain a desired viscosity. It is used in the range of 25% by weight, more preferably 1 to 15% by weight.

When the lithographic printing plate after the development processing has an unnecessary image portion, the above-mentioned erasing liquid is applied to the image portion to erase the image portion. When the erasing liquid used in the present invention is applied to a lithographic printing plate, it is preferable that the lithographic printing plate be washed with water after development, and then squeezed with the rinsing water before erasing. As a specific method of erasing, a method in which an erasing liquid is contained in a brush and applied to an image area and set for about 10 seconds to several minutes, or gently rubbed with a brush after application, and then washed off with water to wash off the floating float. Is common. The planographic printing plate from which the image of the unnecessary portion has been erased in this way is subjected to normal gumming and other processing steps, and then subjected to printing.

[0069]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to examples, but embodiments of the present invention are not limited thereto.

[Embodiments 1 to 7 according to Claims 1 to 5 to 8]
(For the present invention) and Comparative Example 1 (for comparison) <Preparation of Supports 1 to 8> The surface of an aluminum plate (jis1050, tempered H16) having a thickness of 0.24 mm was heated at 50 ° C1.
After degreased by immersion in a 0% by weight aqueous sodium hydroxide solution for 20 seconds, the resultant was washed with water, neutralized with 10% sulfuric acid, and further washed with water. Next, the aluminum plate was heated at a temperature of 30 ° C.
1% hydrochloric acid electrolyte, current density 6
Electrolytic surface roughening treatment was performed using a sine wave alternating current so as to adjust the amount of etching to a value of 35 mg / dm ² at 0 A / dm ² , thereby producing an aluminum support. The amount of etching in the above-mentioned electrochemical surface roughening was determined by immersing in the 30% by weight sulfuric acid aqueous solution kept at 60 ° C. for 30 seconds after the above-mentioned electrochemical surface roughening treatment. The difference between the weight after the removal of the smut component mainly composed of aluminum hydroxide generated in the above and the weight before the above-mentioned electrochemical graining treatment was defined.

After the above-mentioned electrochemical graining treatment, 1 ° C.
% Sodium hydroxide solution to dissolve 2.0 g
/ M ² and then 10 ° C at 25 ° C.
% Sulfuric acid aqueous solution to perform a neutralization treatment.
% Sulfuric acid aqueous solution, temperature 25 ° C, current density 2 A / dm ²
Anodizing treatment was performed for 60 seconds under the conditions described above, and post-treatment with a basic substance treatment solution was performed under the conditions shown in Table 1 to support 1 to 7
A support 8 (for comparison) was obtained by performing only the treatment (for the present invention) and washing with water.

<Preparation of PS Plates> Coating solutions of the following photosensitive compositions were applied to the supports 1 to 8 using a wire bar, and dried at 80 ° C. to obtain eight types of PS plates. At this time, the applied weight of the photosensitive composition after drying was 1.8 g / m ^2.
Met.

(Photosensitive Composition) Esterification reaction product of 1,2-naphthoquinonediazide-5-sulfonyl chloride and 2,3,4-trihydroxybenzophenone 0.5 g phenol formaldehyde resin (weight average molecular weight: 2300) 2 0.0 g 2- (p-butoxyphenyl) -4,6-bis (trichloromethyl) -S-triazine 0.02 g naphthoquinone-1,2-diazide-4-sulfonic acid chloride 0.03 g crystal violet 0.01 g oil Blue # 603 (manufactured by Orient Chemical Industry Co., Ltd.) 0.015 g Ethylene dichloride 18 g 2-methoxyethyl acetate 12 g Positive film in which images were printed on the eight PS plates obtained as described above in a vacuum printing frame From a distance of 1m through a 3kW metal housing After 50 seconds exposure with Idoranpu, 5.26% aqueous solution of sodium silicate in a molar ratio of SiO ₂ / Na ₂ O 1.74 (pH =
12.7).

Then, after thoroughly washing with water and drying, a part of the image was erased with an erasing liquid having the following composition, washed with water, and developed with ink (FP-2, manufactured by Fuji Photo Film Co., Ltd.).
The erased state of the image and the reflection density of the grain at the portion where the erase liquid was adhered were measured. The results are shown in Table 1.

(Erasing liquid) γ-butyrolactone 71.0 parts by weight Pure water 10.0 parts by weight Acid rhodamine B 0.02 parts by weight Polyoxyethylene polyoxypropylene ether 8.0 parts by weight Hydroxypropyl methylcellulose 2.0 parts by weight 9.0 parts by weight of powdered silicon dioxide

[0076]

[Table 1]

According to Table 1, the P of the present invention using supports 1 to 7
The S plate is excellent in the erasability of the printing plate after exposure and development with an erasing liquid, and the erasing trace is small, and the PS plate in comparison with the support 8 is excellent in the printing plate after exposure and development. Of the erasing liquid by the erasing liquid is very poor,
It turns out that the utility is poor.

[Embodiment 8 according to claims 2, 3, 5 to 8]
To 15 (for the present invention) and Comparative Examples 2 to 4 (for comparison)><Preparation of Supports 9 to 19> The surface of an aluminum plate (jis1050, tempered H16) having a thickness of 0.24 mm was heated to 50 ° C.
After degreased by immersion in a 10% by weight aqueous sodium hydroxide solution for 20 seconds, the product was washed with water, neutralized with 10% sulfuric acid, and further washed with water. Then, the aluminum plate was heated at a temperature of 30 ° C.
At a temperature of 60 ° C., a distance between electrodes of 9 mm and a 1% hydrochloric acid electrolyte at a current density of 60 A / dm ² , the etching amount was 35 mg / d.
Using a sine wave alternating current to adjust the electrolysis time so as to obtain a value of m ² , an electrochemical surface-roughening treatment was performed to prepare a support. The amount of etching in the above-mentioned electrochemical graining treatment was kept at 60 ° C. after the electrochemical graining treatment.
The weight after removing the smut component mainly composed of aluminum hydroxide generated by the electrochemical surface roughening treatment by immersing in a 30% by weight aqueous sulfuric acid solution for 30 seconds, and the weight before the electrochemical surface roughening treatment. And the difference.

After the above-mentioned electrochemical graining treatment, 1 ° C.
% Sodium hydroxide aqueous solution to dissolve 2.0 g /
etched so as to m ^2, followed by 25 ° C. 10%
Neutralize by immersing in sulfuric acid aqueous solution.
Anodizing treatment was performed in a sulfuric acid aqueous solution at a temperature of 25 ° C. and a current density of 2 A / dm ² for 60 seconds. Then SiO
Using sodium silicate having a molar ratio of ₂ / Na ₂ O of 3.7, it was immersed in an aqueous solution having a concentration of 0, 2 weight and a temperature of 30 ° C. for 30 seconds, washed with water and dried, and treated with a basic substance under the conditions shown in Table 2. Post-treatment with the liquid was performed to obtain Supports 9 to 16 (for the present invention) and Supports 17 to 19 (for comparison).

<Preparation of PS Plates> Coating solutions of the following photosensitive compositions were applied to the supports 9 to 19 using a wire bar, and dried at 80 ° C. to obtain 11 types of PS plates. At this time, the applied weight of the photosensitive composition after drying was 1.8 g / m2.
^{Was 2} .

(Photosensitive Composition) Esterification reaction product of 1,2-naphthoquinonediazide-5-sulfonyl chloride and 2,3,4-trihydroxybenzophenone 0.5 g phenol formaldehyde resin (weight average molecular weight: 2300) 2 0.0 g 2- (p-butoxyphenyl) -4,6-bis (trichloromethyl) -S-triazine 0.02 g naphthoquinone-1,2-diazide-4-sulfonic acid chloride 0.03 g crystal violet 0.01 g oil Blue # 603 (manufactured by Orient Chemical Industry Co., Ltd.) 0.015 g Ethylene dichloride 18 g 2-methoxyethyl acetate 12 g Positive film in which an image was printed on the 11 types of PS plates obtained as described above in a vacuum printing frame 3kW metal from 1m distance through After 50 seconds exposure with a halide lamp, 5.26% aqueous solution of sodium silicate in a molar ratio of SiO ₂ / Na ₂ O 1.74 (pH
= 12.7).

Next, it was thoroughly washed with water and dried. afterwards,
A part of the image was erased using an erasing liquid having the following composition, printed with Heidel GTO, and the dye remaining after erasing, the erasing trace remaining, and the printing durability were evaluated. The results are shown in Table 2.

(Erasing Liquid) γ-butyrolactone 71.0 parts by weight Pure water 10.0 parts by weight Acid rhodamine B 0.02 parts by weight Polyoxyethylene polyoxypropylene ether 8.0 parts by weight Hydroxypropyl methylcellulose 2.0 parts by weight 9.0 parts by weight of powdered silicon dioxide

[0084]

[Table 2]

As shown in Table 2, the PS plate of the present invention using the supports 9 to 16 has good erasability of the printing plate after exposure and development with an erasing liquid, has little erasure traces, and has excellent printing durability. However, the comparative PS plate using the supports 17 to 19 has a large erasing trace after erasing with a erasing liquid of the printing plate after exposure and development, has a small printing durability, and is poor in practicality. I understand.

[Embodiments 16 to 21 of Claims 4 to 8]
(For the present invention) and Comparative Example 5 (for the purpose of comparison) <Preparation of Supports 20 to 26> The surface of an aluminum plate (jis1050, tempered H16) having a thickness of 0.24 mm was set to 50.
The resultant was immersed in a 10% by weight aqueous solution of sodium hydroxide for 20 seconds to perform a degreasing treatment, washed with water, neutralized with 10% sulfuric acid, and further washed with water. Then, the aluminum plate was heated at a temperature of 30 ° C.
At a temperature of 60 ° C., a distance between electrodes of 9 mm and a 1% hydrochloric acid electrolyte at a current density of 60 A / dm ² , the etching amount was 35 mg / d.
Using a sine wave alternating current, the electrolysis time was adjusted to obtain a value of m ² , and a surface roughening treatment was performed to produce a support. In addition,
The amount of etching in the above-mentioned electrochemical surface-roughening treatment is as follows: after the electrochemical surface-roughening treatment, immersion for 30 seconds in a 30% by weight aqueous sulfuric acid solution maintained at 60 ° C. The difference between the weight after removal of the smut component mainly composed of aluminum oxide and the weight before electrochemical surface roughening treatment was used.

After the above-mentioned electrochemical graining treatment, 1 ° C.
% Sodium hydroxide solution to dissolve 2.0 g
/ M ² and then 10 ° C at 25 ° C.
% Sulfuric acid aqueous solution to perform a neutralization treatment.
% Sulfuric acid aqueous solution, temperature 25 ° C, current density 2 A / dm ²
Anodizing treatment is performed for 60 seconds under the conditions of
Using sodium silicate having a molar ratio of ₂ / Na ₂ O of 3.7, immersed in an aqueous solution having a concentration of 0.2 wt. The post-treatment with the liquid was performed to obtain supports 20 to 25 (for the present invention) and supports 26 (for comparison).

<Preparation of PS plate> A coating solution of a photosensitive composition having the following composition was applied to the above supports 20 to 26 using a wire bar, and dried at 80 ° C to obtain a PS plate. At this time, the coating weight of the photosensitive composition after drying was 1.8 g / m ² .

(Photosensitive Composition) Esterification reaction product of 1,2-naphthoquinonediazide-5-sulfonyl chloride and 2,3,4-trihydroxybenzophenone 0.5 g phenol formaldehyde resin (weight average molecular weight: 2300) 2 0.0 g 2- (p-butoxyphenyl) -4,6-bis (trichloromethyl) -S-triazine 0.02 g naphthoquinone-1,2-diazide-4-sulfonic acid chloride 0.03 g crystal violet 0.01 g oil Blue # 603 (manufactured by Orient Chemical Industry Co., Ltd.) 0.015 g Ethylene dichloride 18 g 2-methoxyethyl acetate 12 g 1 m of the PS plate obtained as described above was passed through a positive film on which an image was printed in a vacuum printing frame in a vacuum printing frame. 3 kW from the distance After 50 seconds exposure using flop, the molar ratio of SiO ₂ / Na ₂ O 1.74
5.26% aqueous solution of sodium silicate (pH = 12.
Developed in 7).

Next, after thoroughly washing with water and drying, a part of the image was erased using an erasing solution having the following composition, and the image was removed using a Heidel GTO.
After DE printing, the dye remaining after erasing, the erasing trace remaining, and the printing durability (the number of prints) were evaluated. The results are shown in Table 3.

(Erasing solution) 7-butyrolactone 71.0 parts by weight Pure water 10.0 parts by weight Acid rhodamine B 0.02 parts by weight Polyoxyethylene polyoxypropylene ether 8.0 parts by weight Hydroxypropyl methylcellulose 2.0 parts by weight 9.0 parts by weight of powdered silicon dioxide

[0092]

[Table 3]

As shown in Table 3, the PS plate of the present invention using the supports 20 to 25 has little residual dye on the printing plate after exposure and development.
Although the erasability with the erasing liquid is good, the erasure trace remains little, and the printing durability is excellent, the comparative PS plate using the support 26 is erasable with the erasing liquid of the printing plate after exposure and development. It can be seen that the print quality was poor, the erasure trace was large, the printing durability was poor, and the utility was poor.

[0094]

As demonstrated by the examples, according to the method for producing a PS plate of the present invention and the support for the PS plate, 1
Finally, it has excellent erasability when erasing unnecessary image areas with an erasing liquid in the process of producing a lithographic printing plate from a PS plate, and has the excellent effect of not causing erasure traces. Secondly, no dye remains in the non-image area after development of the PS plate, plate inspection is easy, and the aluminum support obtained by the surface roughening treatment and the photosensitive layer It has the excellent effect of excellent adhesiveness and excellent printing resistance of the lithographic printing plate. In addition, the third effect is to remove unnecessary image areas in the process of preparing the lithographic printing plate from the PS plate. It is excellent in erasability when erasing with, and no erasing trace remains, and no dye remains in the non-image area after development, plate inspection is easy, and photosensitive layer and Has excellent effects such as adhesiveness, and thus excellent printing resistance.

Claims (8)

[Claims] 1. A method for producing a photosensitive lithographic printing plate comprising providing a layer of a photosensitive composition on an aluminum support which has been subjected to a surface roughening treatment and an anodic oxidation treatment, wherein the aluminum support contains a cation. A method for producing a photosensitive lithographic printing plate, comprising providing a layer of a photosensitive composition after treating with a liquid. 2. A method for producing a photosensitive lithographic printing plate comprising: providing a layer of a photosensitive composition on an aluminum support which has been subjected to a surface roughening treatment, an anodic oxidation treatment and a subsequent alkali metal silicate treatment. A method for producing a photosensitive lithographic printing plate, comprising providing a layer of a photosensitive composition after treating the body with a treatment solution containing a cation. 3. The amount of alkali metal detected from the surface of the aluminum support after the treatment with the treatment solution containing cations after the alkali metal silicate treatment is reduced from that before the treatment, and the amount of alkali metal detected from the surface of the support is reduced. 3. The method for producing a photosensitive lithographic printing plate according to claim 2, wherein the amount of the element corresponding to the cation contained in the processing solution is increased. 4. A method for producing a photosensitive lithographic printing plate comprising: providing a layer of a photosensitive composition on an aluminum support that has been subjected to a surface roughening treatment, an anodic oxidation treatment, and then an alkali silicate treatment. The treatment liquid used for the salt treatment contains a cation other than the alkali metal ion, and the amount ratio of the cation other than the alkali metal ion to all the cations in the treatment liquid is in the range of 0.01 to 1.0. For producing a photosensitive lithographic printing plate. 5. The cation according to claim 1, wherein the cation is an organic basic substance having 2 to 20 carbon atoms.
The method for producing a photosensitive lithographic printing plate according to any one of the above. 6. The method for producing a photosensitive lithographic printing plate according to claim 1, wherein the cation is a divalent or higher metal ion. 7. The method for producing a photosensitive lithographic printing plate according to claim 6, wherein the divalent or higher valent metal ion is an alkaline earth metal ion. 8. In a support for a photosensitive lithographic printing plate which has been subjected to a surface roughening treatment, an anodic oxidation treatment and then at least an alkali silicate treatment, the total of nitrogen atoms and alkaline earth metals detected from the support surface. A support for a photosensitive lithographic printing plate wherein the amount is greater than the amount of alkali metal.