JP2002123002A - Makeup method for positive type photosensitive planographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a makeup method for a positive type photosensitive planographic printing plate having large development latitude and excellent in processing stability. SOLUTION: In the makeup method in which a photosensitive planographic printing plate with a positive type photosensitive composition layer containing (A) a photothermal converting material and (B) an alkali-soluble resin on the base is exposed with laser light and developed with an alkali developing solution, the photosensitive composition layer contains (C) a surfactant having a HLB(hydrophile-lipophile balance) of <10 and the alkali developing solution contains (D) a surfactant having an HLB of >=10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of making a novel positive photosensitive lithographic printing plate. More specifically, 65
The present invention relates to a method for making a positive photosensitive lithographic printing plate suitable for direct plate making using a light beam in a wavelength range of 0 to 1300 nm, in particular, a semiconductor laser or a YAG laser.

[0002]

2. Description of the Related Art With the advance of computer image processing technology, a photosensitive or heat-sensitive direct plate making in which a resist image is directly formed by a laser beam or a thermal head without outputting digital image information to a silver halide mask film. The system is drawing attention. In particular, realization of a high-resolution laser-sensitive direct plate making system using a high-output semiconductor laser or YAG laser has been strongly desired in view of miniaturization, environmental light during plate making work, and plate material cost.

Among printing plates for laser-sensitive direct plate making, recently, a method of forming a positive image by using an infrared laser and increasing the solubility of an exposed portion in a developing solution mainly by a change other than a chemical change has attracted attention. For example, JP-A-10-268512, JP-A-11-194504, and JP-A-11-2239
No. 36, JP-A-11-84657, JP-A-1
1-1174681, WO97 / 39894, WO
98/42507 and the like. Conventional positive-type photosensitive lithographic printing plates typically increase the solubility in a developing solution by photodecomposition of an o-quinonediazide compound, that is, by a chemical change, and use this for image formation. The positive-type photosensitive lithographic printing plate described in the literature has a main photosensitive layer component containing a substance that absorbs infrared light such as an infrared absorbing dye and converts it into heat and an alkali-soluble resin such as a novolak resin. The heat generated by the external laser light exposure causes a physical change such as a conformational change of the resin to increase the solubility in a developing solution.

[0004] Positive-type photosensitive lithographic printing plates utilizing the increase in solubility due to non-chemical changes do not require substances sensitive to white light such as o-quinonediazide compounds. It has the advantage that it can be done. However, such a printing plate has a printing durability, a sensitivity, and a development latitude (a time until the exposed portion is completely removed during development, since the photosensitive layer component does not substantially undergo a chemical change upon exposure, It is difficult to satisfy all of the basic performances of the printing plate, such as the difference in the time during which the residual film ratio of the unexposed portion is sufficiently ensured during the development.

To solve this problem, it is conceivable to reduce the thickness of the photosensitive layer. However, in the case of a heat conversion type photosensitive layer, if the thickness is too small, heat diffusion to the support increases, and conversely the sensitivity decreases. was there. Further, the storage stability, printing durability, and chemical resistance were greatly affected by changes over time and storage conditions. In particular, when the molecular weight and the like of the binder component in the photosensitive material are changed in order to improve the chemical resistance and printing durability, the alkali solubility deteriorates and the developability becomes difficult. As described above, the chemical resistance, storage stability, and printing durability always conflict with performances such as sensitivity and developability, and the performance required as a positive photosensitive lithographic printing plate was not satisfactory. .

[0006] For example, Japanese Patent Application Laid-Open No. 2000-105454 discloses that a positive photosensitive composition containing a novolak resin and a photothermal conversion substance contains a surfactant, preferably HL.
It is described that by adding a nonionic surfactant or a fluorine-based surfactant having a B8 or more, particularly preferably an HLB of 10 or more, the residual film ratio of an image area is improved.
An example using a surfactant of 11.5 or more is shown. However, according to the study of the present inventor, even in this method in which the photosensitive composition contains a surfactant, the development latitude is still narrow, and practically, the removal of the non-image area in the development processing and the image area It has been found that further improvement is necessary in simultaneously realizing a high residual film ratio in a portion.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for making a photosensitive lithographic printing plate having an excellent development latitude.

[0008]

The present inventors have conducted intensive studies and as a result, in order to increase the development latitude of the photosensitive layer,
A surfactant having a low HLB (lipophilicity) is effective in the photosensitive layer, while a surfactant having a high HLB (hydrophilicity) in the developer is required to increase the residual film ratio of an unexposed portion. Was found to be effective, and the present invention was reached.
Was.

That is, the gist of the present invention resides in that
Positive photosensitive lithographic printing plate in which a photosensitive lithographic printing plate having a positive photosensitive composition layer containing (A) a light-to-heat conversion material and (B) an alkali-soluble resin is laser-exposed and then developed with an alkali developer. Wherein the photosensitive composition layer contains (C) a surfactant having an HLB of less than 10;
In addition, the present invention resides in a method for making a positive photosensitive lithographic printing plate, characterized in that the alkali developer contains (D) a surfactant having an HLB of 10 or more.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The plate making method of the present invention comprises: (A) a photothermal conversion substance, (B) an alkali-soluble resin,
And (C) a photosensitive lithographic plate having a positive photosensitive composition layer containing a surfactant having an HLB of less than 10 as an essential component, and further containing a dissolution inhibitor, a thermally crosslinkable compound, and other additives as necessary. Using a printing plate, this is exposed to laser light, and then (D) developed using an alkali developer containing a surfactant having an HLB of 10 or more.

As the support on which the photosensitive composition layer used in the present invention is provided, a metal plate such as aluminum, zinc, steel or copper, or chromium, zinc, copper, nickel, aluminum or iron is plated or deposited. Metal sheet, paper, plastic film and glass plate, paper coated with resin, paper covered with metal foil such as aluminum, sheet such as plastic film subjected to hydrophilic treatment, and the like. Of these, an aluminum plate is preferred. As the support of the photosensitive lithographic printing plate of the present invention, graining treatment by electrolytic etching or brush polishing in a hydrochloric acid or nitric acid solution,
It is more preferable to use an aluminum plate which has been subjected to anodizing treatment in a sulfuric acid solvent and, if necessary, surface treatment such as sealing treatment.

The roughness of the surface of the support is generally indicated by the value of the surface roughness Ra. This can be measured using a surface roughness meter. The support used in the present invention has an average roughness Ra of 0.3 to 1.
0 μm aluminum plate is preferable,
0.8 μm is more preferable. This support can be used after further performing a surface treatment with an organic acid compound, if necessary.

The (A) “photothermal conversion substance”, which is the first component used in the positive photosensitive composition of the present invention, will be described. The photothermal conversion material is not particularly limited as long as it can convert absorbed light into heat.
Among the organic or inorganic pigments and dyes having an absorption band in a part or the whole of the near infrared region of 50 to 1300 nm, organic dyes, metals, metal oxides, metal carbides, metal borides, etc. Is particularly effective. These light-absorbing dyes efficiently absorb light in the above-mentioned wavelength region, but hardly absorb light in the ultraviolet region, or do not substantially respond to absorption, and are weakly sensitive to ultraviolet light contained in white lamps. Is a compound having no action of modifying the photosensitive composition.

These light absorbing dyes include a nitrogen atom,
Representative examples include so-called cyanine dyes in a broad sense, in which a heterocyclic ring containing an oxygen atom or a sulfur atom or the like is bonded by polymethine (-CH =) n, and specifically, for example, quinoline ( So-called cyanine-based in a narrow sense, indole-based (so-called indocyanine-based), benzothiazole-based (so-called thiocyanine-based), oxazole-based (so-called oxacyanine-based), aminobenzene-based (so-called polymethine-based), pyrylium-based , Thiapyrylium, squarylium, croconium, azurenium, aminium, immonium, phthalocyanine, anthraquinone, etc., among which quinoline, indole, benzothiazole, aminobenzene, pyrylium,
Alternatively, a thiapyrylium-based, aminium-based, or immonium-based dye is preferable.

In the present invention, among the cyanine-based dyes, quinoline-based dyes include those represented by the following general formula (I)
Those represented by a), (Ib) or (Ic) are preferred.

[0016]

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[In the formulas (Ia), (Ib) and (Ic), R¹And R^Two
Is each independently an alkyl which may have a substituent
Group, an alkenyl group which may have a substituent,
Optionally having an alkynyl group or a substituent
Represents a phenyl group which may be ¹Has a substituent
A tri, penta, or heptamethine group;
Two substituents on the amino or heptamethine group are linked to each other
To form a cycloalkene ring having 5 to 7 carbon atoms
The quinoline ring may have a substituent,
When two adjacent substituents are linked to each other,
May form a ring. X^-Indicates a counter anion
You. Where R in formulas (Ia), (Ib) and (Ic)¹And R^Two
As the substituents, an alkoxy group, a phenoxy
Group, a hydroxy group, a phenyl group or the like;¹
As the substituent for, an alkyl group, an amino group, or
A halogen atom or the like; a substituent on the quinoline ring;
As an alkyl group, an alkoxy group, a nitro group, or
And a halogen atom.

The indole, benzothiazole and benzoxazole dyes are particularly preferably those represented by the following formula (II).

[0019]

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[In the formula (II), Y ¹ and Y ² are each independently
Represents a dialkylmethylene group, a sulfur atom or an oxygen atom,
R ³ and R ⁴ are each independently an alkyl group optionally having a substituent, an alkenyl group optionally having a substituent,
An alkynyl group which may have a substituent, or a phenyl group which may have a substituent; L ² represents a tri, penta, or heptamethine group which may have a substituent; Two substituents on the penta or heptamethine group may be linked to each other to form a cycloalkene ring having 5 to 7 carbon atoms, and the condensed benzene ring may have a substituent, in which case May be linked to each other to form a fused benzene ring. X ^- is a counter anion. Here, examples of the substituent for R ³ and R ⁴ in the formula (II) include an alkoxy group, a phenoxy group, a hydroxy group, and a phenyl group. Examples of the substituent for L ² include an alkyl group and an amino group. And a substituent on the benzene ring, such as an alkyl group, an alkoxy group, a nitro group, or a halogen atom.

Further, as the aminobenzene-based dye, those represented by the following general formula (III) are particularly preferred.

[0022]

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[In the formula (III), R ⁵ , R ⁶ , R ⁷ and R ⁸ each independently represent an alkyl group, and R ⁹ and R ¹⁰ each independently represent a substituent. L3 represents a mono-, tri-, or pentamethine group which may have a substituent, and two substituents on the tri- or pentamethine group are linked to each other; To form a cycloalkene ring having 5 to 7 carbon atoms, and the quinone ring and the benzene ring may have a substituent. X ^- is a counter anion. Here, specifically, as R ⁹ and R ¹⁰ in the formula (III),
A phenyl group, a 1-naphthyl group, a 2-naphthyl group, a 2-furyl group, a 3-furyl group, a 2-thienyl group, a 3-thienyl group, and the like. Examples of such substituents include an alkyl group, an alkoxy group, dialkylamino group, hydroxy group, or a halogen atom, and examples of the substituent in L ^3, alkyl group, amino group, or a halogen atom, and examples of the substituent in the quinone ring and the benzene ring, an alkyl group , An alkoxy group, a nitro group, or a halogen atom.

Further, as the pyrylium-based and thiapyrylium-based dyes, the following general formulas (IVa), (IVb), and
Those represented by (IVc) are preferred.

[0025]

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In the formulas (IVa), (IVa) and (IVc), Y ³
And Y ⁴ each independently represent an oxygen atom or a sulfur atom, and R ¹¹ , R ¹² , R ¹³ , and R ¹⁴ each independently represent a hydrogen atom or an alkyl group, or R ¹¹ and R ¹³ , and R ¹² and R
¹⁴ may be linked to each other to form a cycloalkene ring having 5 or 6 carbon atoms, and L ⁴ represents a mono, tri, or pentamethine group which may have a substituent, and the tri or pentamethine group The above two substituents may be connected to each other to form a cycloalkene ring having 5 to 7 carbon atoms, and the pyrylium ring and the thiapyrylium ring may have a substituent. Two substituents may be linked to each other to form a fused benzene ring. X ^- is a counter anion. Here, examples of the substituent in L ⁴ of formulas (IVa), (IVa), and (IVc) include an alkyl group, an amino group, and a halogen atom, and examples of the substituent in the pyrylium ring and the thiapyrylium ring include And an aryl group such as a phenyl group and a naphthyl group.

Further, as the aminium-based and immonium-based dyes, those having at least one N, N-diaryliminium salt skeleton are preferable.
Those represented by (Va) or (Vb) are preferred.

[0028]

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[In the formulas (Va) and (Vb), R^Fifteen, R¹⁶,
R¹⁷, R¹⁸, R¹⁹, R²⁰, R^{twenty one}, And R ^{twenty two}Are independent
Represents a hydrogen atom, an alkyl group, or a phenyl group,
The non-ring and the benzene ring may have a substituent. X
^-Represents a counter anion. Note that the electronic bond (─) in the formula (Vb)
Indicates a resonance state with another electronic bond. Here, the quinone ring and the benzene ring in the formulas (Va) and (Vb)
Examples of the substituent include an alkyl group, an alkoxy group,
Acyl group, nitro group, or halogen atom, etc.
You.

The above-mentioned general formulas (Ia to c), (II), (III),
Examples of the counter anion X ⁻ in (IVa to c) and (Va to b) include, for example, Cl ⁻ , Br ⁻ , I ⁻ , ClO ₄ ⁻ , PF ₆ ⁻ ,
And, BF ₄ ^- inorganic acid anion, benzenesulfonic acid inorganic borate such as, p- toluenesulfonic acid, naphthalenesulfonic acid, acetic acid, and methyl, ethyl, propyl, butyl, phenyl, methoxyphenyl, naphthyl, difluorophenyl And organic acid anions such as organic boric acid having an organic group such as pentafluorophenyl, thienyl and pyrrolyl.

As described above, the quinoline dyes represented by the general formulas (Ia to c), the indole or benzothiazole dyes represented by the general formula (II), and the amino acids represented by the general formula (III) Benzene-based dyes, pyrylium-based or thiapyrylium-based dyes represented by the general formulas (IVa to c), and aminium- or immonium-based dyes represented by the general formulas (Va to b) are excellent in sensitivity. I have. Specific examples of the photothermal conversion material preferably used are shown below.

[0032]

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[0033]

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[0034]

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[0035]

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[0036]

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[0037]

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[0038]

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[0039]

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[0040]

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[0041]

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[0042]

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The content ratio of these heat conversion materials in the positive photosensitive composition of the present invention is usually 0.5 to 0.5 by weight.
30%, preferably 1-20%, more preferably 2-1
0%, especially 3-10%. In particular, in combination with the surfactant described below, the content of the light-to-heat conversion substance can be relatively increased, and as a result, sensitivity and development latitude are particularly improved, which is preferable.

Next, the second component (B) “alkali-soluble resin” used in the positive photosensitive composition of the present invention.
(Hereinafter, may be referred to as a polymer or a resin) will be described. The alkali-soluble resin is basically composed of a combination of the component (A) and the photothermal conversion substance, wherein the exposed portion and the unexposed portion are mainly changed by a change other than a chemical change.
It is a polymer that can cause a difference in solubility in an alkali developing solution, and naturally includes the case where the polymer itself is a polymer compound whose solubility in an alkali developing solution is changed mainly by a change other than a chemical change. Examples of such a polymer include a novolak resin, a resol resin, a polyvinylphenol resin, and an alkali-soluble resin such as a copolymer of an acrylic acid derivative. Among them, it is preferable to contain a novolak resin.

As the novolak resin, phenol, m
-Cresol, o-cresol, p-cresol, 2,
5-xylenol, 3,5-xylenol, resorcinol, pyrogallol, bisphenol, bisphenol-
A, at least one kind of aromatic hydrocarbons such as trisphenol, o-ethylphenol, m-ethylphenol, p-ethylphenol, propylphenol, n-butylphenol, t-butylphenol, 1-naphthol and 2-naphthol; Polycondensation with aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde and furfural and at least one aldehyde or ketone selected from ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone under an acidic catalyst. Is mentioned.

Instead of formaldehyde and acetaldehyde, paraformaldehyde and paraaldehyde, respectively, may be used. Weight average molecular weight in terms of polystyrene by gel permeation chromatography (hereinafter abbreviated as GPC) measurement of the novolak resin (hereinafter, the weight average molecular weight as measured by GPC is abbreviated as Mw).
Is preferably 1,000 or more, more preferably 1.5
Those having a molecular weight of 00 or more, preferably 15,000 or less, more preferably 10,000 or less are used.

The aromatic hydrocarbons of the novolak resin are more preferably phenol, o-cresol, m
-Cresol, p-cresol, 2,5-xylenol, and 3,5-xylenol, at least one phenol selected from resorcinol, formaldehyde,
Novolak resins polycondensed with at least one selected from aldehydes such as acetaldehyde and propionaldehyde are exemplified.

Among them, the mixing ratio of m-cresol: p-cresol: 2,5-xylenol: 3,5-xylenol: resorcin was 40 to 100: 0 to 5 in molar ratio.
Phenols of 0: 0 to 20: 0 to 20: 0 to 20 or phenols and aldehydes having a molar ratio of phenol: m-cresol: p-cresol of 1 to 100: 0 to 70: 0 to 60 Novolak resins which are polycondensates with the compounds are preferred. Of the aldehydes, formaldehyde is particularly preferred. As described later, the photosensitive composition of the present invention may further contain a dissolution inhibitor. In this case, m-cresol: p-cresol: 2,5-xylenol: 3,5-xylenol: resorcinol Are mixed in a molar ratio of 70 to 100: 0 to 30: 0 to 20: 0.
Phenols or phenol: m-cresol: p-cresol in a molar ratio of 10 to 10
Novolak resins, which are polycondensates of phenols and aldehydes at 0: 0 to 60: 0 to 40, are preferred.

Examples of the resin other than the novolak resin include an alkali-soluble resin described in JP-A-2000-105454. These resins may be used alone or as a mixture. Among the above-mentioned resins, it is particularly preferable to contain a novolak resin in terms of sensitivity and development latitude. The content of these resins in the positive photosensitive composition is preferably 50% to 99% by weight, more preferably 60% to 99%, and particularly preferably 7%.
0 to 98%.

The photosensitive layer used in the present invention must contain (C) "a surfactant having an HLB of less than 10" as a third component. Preferably, the HLB is 9 or less. When the HLB is less than 10, the development latitude is particularly widened, and the developability is improved.

Although the reason is not clear, it is estimated as follows. That is, the positive photosensitive lithographic printing plate in which the alkali solubility of the exposed portion is increased by laser light exposure, as described below, preferably, a polar compound such as moisture is supplied from the surface of the photosensitive layer, and By heating and holding at a certain temperature, (1) in the surface layer portion of the photosensitive layer, an alkali-soluble resin such as a novolak resin does not dissolve in a developing solution due to a hydrogen bond between its hydroxyl group and water. It forms a leopard conformation. (2) On the other hand, a portion closer to the support than the surface layer of the photosensitive layer maintains high solubility. (3) The exposure improves the solubility by changing the conformation of the surface layer of the photosensitive layer in the exposed part into a structure that is easily dissolved in the developing solution, and (4) improving the solubility of the exposed part and the unexposed part with respect to the developing solution. It is estimated that the difference in solubility will be large. In such a tilt-type positive photosensitive lithographic printing plate, in particular, HLB is less than 10, that is, by containing a surfactant having high hydrophobicity, a polar compound such as water penetrates and diffuses into the deep part of the photosensitive layer. To reduce
Therefore, only the surface layer becomes less soluble in the developer than the heat generated by the laser exposure reaches sufficiently,
It is presumed that the difference in solubility between exposed and unexposed areas becomes larger, and the development latitude is enlarged.

The surfactant having an HLB of less than 10 (hereinafter sometimes referred to as a lipophilic surfactant) may be any of anionic, cationic, nonionic and the like. Examples include ionic surfactants, such as ether type, ester type, amino ether type, ether ester type and alkanolamide type. Specifically, polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene derivative, oxyethylene / oxypropylene block copolymer, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester,
Glycerin fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene alkylamine, alkyl alkanolamide, polyoxyethylene alkylamino ether, pentaerythritol fatty acid ester,
Polyethylene glycol, polyoxypropylene polyoxyethylene alkyl ether, polyoxyethylene polyoxypropylene ether derivative, polyoxypropylene glyceryl ether, methoxy polyethylene glycol, glycerol borate fatty acid ester, polyoxyethylene alkylamine, polyoxyethylene glycerol borate fatty acid Ester, polyoxyethylene fatty acid alkanolamide, polyglycerin fatty acid ester, propylene glycol fatty acid ester, polyoxyethylene sorbitol fatty acid ester, polyoxyethylene phytosterol, polyoxyethylene phytostanol, polyoxyethylene vegetable oil, polyoxyethylene lanolin, polyoxyethylene Lanolin alcohol, polyoxyethylene Tsurou derivatives, polyoxyethylene alkylphenyl formaldehyde condensates and the like. Among them, preferred are polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene / polyoxypropylene block polymer, polyoxyethylene sorbite fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyethylene glycol, polyoxyethylene Glycerin fatty acid ester, polyethylene glycol fatty acid ester, glycerin fatty acid ester, sorbitan fatty acid ester, pentaerythritol fatty acid ester, propylene glycol fatty acid ester, and polyglycerin fatty acid ester, more preferably polyoxyethylene alkyl ether, polyoxyethylene sorbite fatty acid Esters, polyoxyethylene sorbitan fatty acid esters Polyglycerol fatty acid esters, polyethylene glycol, particularly preferably polyoxyethylene sorbit fatty acid ester.
Even if the above-mentioned surfactants are of the same type, for example, H
Since the LB is also different, one having an HLB of less than 10 is selected and used. In particular, a nonionic surfactant having an HLB of 9 or less is preferable. The lower limit of HLB is not particularly limited, but is preferably 3 or more.

H in the positive photosensitive composition of the present invention
If the content of the surfactant having an LB of less than 10 is too small, the effect of the present invention is small, and if the content is too large, the component responsive to the laser beam becomes small, and the residual film ratio is reduced. It is at least 5%, more preferably at least 1%, particularly preferably at least 2%, preferably at most 20%, more preferably at most 10%, particularly preferably at most 8%. Incidentally, in the photosensitive composition layer of the present invention, as long as its performance is not impaired, for example, JP 200
Surfactants other than the above described in JP-A-105454 may be used in combination. Further, as described later, a surfactant having an HLB of 10 or more may be used in combination as long as the effects of the present invention are not impaired.

The photosensitive composition layer of the present invention may contain a dissolution inhibitor having a property of reducing the solubility of the photosensitive composition in an alkali developing solution. Examples of the dissolution inhibitor used in the present invention include JP-A-10-2684.
12, sulfonic acid esters, phosphoric acid esters, aromatic carboxylic acid esters, aromatic disulfones, carboxylic acid anhydrides described in JP-A-11-288089 and the like.
Examples thereof include aromatic ketones, aromatic aldehydes, aromatic amines and aromatic ether compounds, and compounds having a triarylmethane skeleton. Also, JP-A-11-1
Lactone skeleton, an N, N-diarylamide skeleton, an acid coloring dye having a diarylmethylimino skeleton, a lactone skeleton, a thiolactone skeleton described in JP-A-90903 and the like.
Base coloring dyes having a sulfolactone skeleton can also be mentioned.

The photosensitive layer of the present invention may contain a compound capable of crosslinking an alkali-soluble resin by the action of heat (hereinafter, may be abbreviated as a thermally crosslinkable compound). When a heat-crosslinking compound is contained in the photosensitive layer, the alkali-soluble resin can be crosslinked by performing post-heating treatment after exposure, and as a result, it is possible to improve chemical resistance and printing durability. it can. As such a thermally crosslinkable compound, a compound which can crosslink an alkali-soluble resin by heating to 150 ° C to 300 ° C is usually mentioned.

Examples of the thermally crosslinkable compound include a nitrogen-containing compound having thermal crosslinkability, preferably a compound containing an amino group, and more specifically, for example, a methylol group as a functional group and an alcohol thereof. Examples thereof include condensation-modified alkoxymethyl groups, and other amino compounds having at least two acetoxymethyl groups. Among the compounds having an amino group, the compound preferably has a heterocyclic structure, particularly a nitrogen-containing heterocyclic structure, and more preferably a compound having a melamine skeleton. Specifically, for example, as such a thermally crosslinkable compound, a thermally crosslinkable compound described in JP-A-11-202481 and the like can be mentioned.

The photosensitive composition of the present invention may contain various additives such as dyes, pigments,
It may also contain a coating improver, a development improver, an adhesion improver, a sensitivity improver, a sensitizer, and the like. It is also possible that the cause of color development includes an ionic dye due to the non-polarization of a cation or an anion. Oxazine dyes, azine dyes, pyrylium dyes,
And thiopyrium dyes, viologen dyes, xanthene dyes, rhodocyanine dyes, styryl dyes, and the like. It should be noted that such ionic dyes are distinguished from dyes that can be used as a light-to-heat conversion material, and are dyes having an absorption maximum (λmax) of 700 nm or less. Of these, preferred are triphenylmethane dyes having a triphenylmethyl group as a partial structure in the structure thereof. I. No. When represented by C. I.
BasicViolt3, C.I. I. BasicBlue
5, C.I. I. Basic Green 1, C.I. I. Bas
icBlue 26, C.I. I. AcidBlue1, C.I.
I. solventBlue2, C.I. I. BasicB
lue7 and the like; Crystal Violet manufactured by Tokyo Chemical Industry Co., Ltd .; Primocyanin manufactured by Sumitomo Chemical Co., Ltd.
eBxconc. AizenDi manufactured by Hodogaya Chemical Co., Ltd.
amondGreenGH, Aizen Victory
aBlueBH, AizenBrilliantAci
dPureBlueVH, Eisen Victoria Pia Blue BOH, Victoria Blue4RB manufactured by BASF
case and the like.

The photosensitive lithographic printing plate of the present invention comprises the photothermal conversion material of the component (A), the alkali-soluble resin of the component (B) and the surfactant having an HLB of less than 10 of the component (C), The dissolution inhibitor and other additives are dissolved in an appropriate solvent according to the above, and the solution is applied to a support and dried. The solvent is not particularly limited as long as it has a sufficient solubility for the components used and gives good coating properties, but cellosolve solvents such as methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, and ethyl cellosolve acetate. Propylene glycol solvents such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monobutyl ether acetate, and dipropylene glycol dimethyl ether; butyl acetate; Amyl acetate, ethyl butyrate, butyl butyrate, diethyl oxalate, ethyl pyruvate, ethyl-2-hydroxy Ester solvents such as tylate, ethyl acetoacetate, methyl lactate, ethyl lactate, and methyl 3-methoxypropionate; alcohol solvents such as heptanol, hexanol, diacetone alcohol, and furfuryl alcohol; ketone solvents such as cyclohexanone and methyl amyl ketone Solvents, dimethylformamide, dimethylacetamide, highly polar solvents such as N-methylpyrrolidone, or a mixed solvent thereof,
Further, those obtained by adding an aromatic hydrocarbon to these are also exemplified. The usage ratio of the solvent is usually in the range of about 1 to 20 times by weight based on the total amount of the photosensitive composition.

As the coating method used when the photosensitive composition used in the present invention is provided on the surface of the support, conventionally known methods, for example, spin coating, wire bar coating, dip coating, air knife coating, roll coating, It is possible to use blade coating, curtain coating and the like. The photosensitive layer has a thickness of 1 to 3 μm, and a weight thickness of 13 to 30 mg / dm ^2.
Is more preferred, and more preferably 1-2 μm, 16-28 m
g / dm ² is preferred.

The positive photosensitive lithographic printing plate obtained as described above is exposed to an image with a laser beam and then developed with an alkali developing solution to form a positive image. Here, the light source for imagewise exposing the positive photosensitive lithographic printing plate is mainly a HeNe laser, an argon ion laser,
YAG laser, HeCd laser, semiconductor laser,
Although a laser light source such as a ruby laser is mentioned, particularly, when an image is formed by heat generated by absorbing light, a light source that generates a near-infrared laser beam in a wavelength range of 650 to 1,300 nm is preferable, For example, solid-state lasers such as a ruby laser, a YAG laser, a semiconductor laser, and an LED can be used. In particular, a small-sized and long-life semiconductor laser or a YAG laser is preferable.

The laser light source usually scans the surface of the photosensitive composition layer as a high-intensity light beam (beam) condensed by a lens, and the sensitivity of the photosensitive composition layer according to the present invention responds to the scanning. The characteristic (mJ / cm ² ) may depend on the light intensity (mJ / s · cm ² ) of the received laser beam. Here, the light intensity of the laser beam is obtained by dividing the amount of energy per unit time (mJ / s) of the laser beam measured by the optical power meter by the irradiation area (cm ² ) of the laser beam on the surface of the photosensitive composition layer. Can be obtained by The irradiation area of the laser beam is usually defined as an area of a portion exceeding 1 / e ² intensity of the laser peak intensity, but it can be simply measured by exposing a photosensitive composition exhibiting a reciprocity law. .

In the plate making method of the present invention, the light intensity of the light source is preferably 2.0 × 10 ⁶ mJ / s · cm ² or more, and 1.0 × 10 ⁷ mJ / s · cm ² or more. It is particularly preferred to do so. If the light intensity is within the above range,
The sensitivity characteristics of the positive photosensitive composition layer in the present invention can be improved, and the scanning exposure time can be shortened, which is a great practical advantage.

Next, in the plate making method of the present invention, the above-described photosensitive lithographic printing plate is preferably exposed to near-infrared light in the range of 650 to 1300 nm and then developed with an alkali developing solution. It is characterized in that the developer contains (D) a surfactant having an HLB of 10 or more. The alkali developer mainly comprises an alkali component and water, and an appropriate amount of a surfactant and other additives. In this specification,
"Alkaline developer" means a developer that is in a developing tank and is about to be subjected to the development of a printing plate. It changes (process deterioration). Further, the developer initially supplied to the developing machine is referred to as “initial developer” and is distinguished from the developer in the developing machine which changes according to the development processing of the printing plate. Furthermore, a solution that is replenished in order to cope with the fatigue of the alkaline developer in the developing tank and to recover the processing deterioration is referred to as “development replenisher”. Commercially available developing solutions and developing replenishers (developing solutions sold in containers) can be used as undiluted solutions, or concentrated solutions can be diluted with a certain amount of water when used. In this specification, the concentration of a component in a developer or a replenisher initially means a concentration in a state where it is actually used (a concentrated state is a diluted state).

When the printing plate is developed, the processing deterioration of the alkali developing solution proceeds. The process of deterioration of the alkaline developer is estimated as follows. If it is a positive type, the unexposed portion of the photosensitive composition layer elutes into the developer, so that the concentration of the photosensitive composition increases as the number of developed images increases. As the concentration of the photosensitive composition in the developer increases, the affinity of the photosensitive composition layer on the printing plate for the alkali developer increases (developability increases), and the solubility of the unexposed portion increases. Therefore, it is presumed that film thinning occurs as a result. Here, if a hydrophilic surfactant having an HLB of 10 or more is contained in the alkali developer, the affinity between the developer and the photosensitive composition layer on the printing plate is suppressed, and the film loss is reduced (the residual film ratio is improved). It is presumed that the processing stability against the deterioration of the alkaline developer due to the increase in the number of processed printing plates is improved.

Examples of the alkali component used in the initial developer and replenisher include sodium silicate, potassium silicate, lithium silicate, ammonium silicate, sodium metasilicate, potassium metasilicate, sodium hydroxide, potassium hydroxide, and hydroxide. Inorganic alkali salts such as lithium, sodium carbonate, sodium bicarbonate, potassium carbonate, sodium diphosphate, sodium tertiary phosphate, ammonium diphosphate, ammonium tertiary phosphate, sodium borate, potassium borate, ammonium borate, monomethylamine, dimethyl Amine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, monobutylamine, monoethanolamine, diethanolamine, triethanolamine, monoisoamine Ropanoruamin, organic amine compounds such as diisopropanolamine, and the like, these alkali components preferably an aqueous solution of about 0.1 to 5 wt%, is used as the alkaline developer.

Among the above, in the present invention, inorganic alkali salts such as hydroxides of alkali metals such as sodium hydroxide, potassium hydroxide and lithium hydroxide, and sodium silicate, potassium silicate and lithium silicate The alkali developer containing the alkali metal silicate is preferred.

A surfactant having an HLB of 10 or more (hereinafter sometimes referred to as a hydrophilic surfactant) in an alkaline developer.
Is not particularly limited, preferably,
The concentration of the surfactant having an HLB of 10 or more is controlled in accordance with the amount of the photosensitive composition eluted into the alkaline developer by the development treatment. The preferred embodiment will be specifically described below. In a first preferred embodiment, a surfactant having an HLB of 10 or more is contained in the photosensitive composition, so that a surfactant having an HLB of 10 or more in a developing solution is produced depending on the amount of the photosensitive composition eluted by development. Is used to control the concentration of In this case, a surfactant having an HLB of less than 10 and a surfactant having an HLB of 10 or more coexist in the photosensitive composition layer. As described above, HLB10
It is believed that less than 10% of the surfactant acts to improve the development latitude, while 10% or more of the surfactant acts to prevent film loss after it elutes into the developer. The advantage of this method is that the hydrophilic surfactant is supplied to the developer in proportion to the amount of the photosensitive composition eluted, so that `` according to the amount of the photosensitive composition eluted by development, Controlling the concentration of a surfactant having an HLB of 10 or more in the developer "is the most effective.

Examples of the surfactant having an HLB of 10 or more contained in the photosensitive composition include HLB 10 or more among known surfactants such as anionic surfactants, amphoteric surfactants, and nonionic surfactants. Can be used. The content of the surfactant having an HLB of 10 or more in the photosensitive composition is preferably 0.2% or more, more preferably 0.3% or more, and particularly preferably 0.1% or more.
5% or more, preferably 15% or less, more preferably 10% or less, particularly preferably 5% or less.
When the content of the surfactant having an HLB of 10 or more is too small,
Since the amount of supply to the developer is reduced, the effect of preventing film thinning is not effectively exerted. If the content is too large, the effect of increasing the development latitude caused by a surfactant having a coexistence of less than HLB10 may be hindered. is there.

Next, as a second preferred embodiment, HLB1 is placed in a place other than the photosensitive composition layer of the photosensitive lithographic printing plate.
By holding 0 or more surfactants, the HL in the developer can be adjusted according to the amount of the photosensitive composition eluted by the development.
It controls the concentration of the surfactant of B10 or more.
Specifically, for example, a hydrophilic surfactant itself or a mixture with an alkali-soluble resin is applied to the back surface of the printing plate (the surface without the photosensitive composition layer) or the edge of the surface (a region not used for image formation) and applied. And a method of holding. The hydrophilic surfactant thus retained is supplied after being eluted into the developer during development.

As described above, the method of keeping the hydrophilic surfactant in a portion other than the photosensitive composition layer on the printing plate is based on the development latitude of the surfactant less than HLB10 in the photosensitive composition. It has the advantage of not impeding the augmentation effect at all. However, in this supply method, since the elution amount of the photosensitive layer and the elution amount of the hydrophilic surfactant are not at all proportional, the average amount of the exposed portion is calculated from the application of the printed material and the like, and the expected hydrophilicity is calculated therefrom. It is necessary to calculate the elution amount of the surfactant to determine the amount retained on the printing plate.

Next, as a third preferred embodiment, an alkali developer having an HLB of 10 or more is additionally replenished in the alkaline developer according to the amount of the photosensitive composition eluted by the development, whereby the developer in the developer is prepared. It controls the concentration of a surfactant having an HLB of 10 or more. Specifically, the developing machine is provided with a replenishing device for the hydrophilic surfactant, and on the other hand, the amount of the photosensitive composition in the developing solution is monitored by various analyzers or the number of developed sheets is counted. The elution amount of the photosensitive composition is calculated, and the hydrophilic surfactant is supplied from the replenishing device according to the calculation results. This method requires a new replenishing device, but is advantageous in terms of productivity and quality stability because control on the photosensitive lithographic printing plate side is unnecessary.

As a fourth preferred embodiment, there is a method in which a hydrophilic surfactant having an HLB of 10 or more is contained in a developing replenisher, and the hydrophilic surfactant is supplied in conjunction with the supply of the developing replenisher. This method is advantageous in terms of productivity and quality stability because control on the photosensitive lithographic printing plate side is unnecessary, but the type and amount of replenisher are adjusted according to the degree of aging and printing deterioration. There is a need to. Therefore, when this method is adopted, a replenisher replenisher similar to the above-described hydrophilic surfactant replenisher is provided in the developing machine,
It is preferable that the deterioration over time and the processing deterioration are calculated from the number of developed sheets and the residence time of the developing solution in the developing machine, and the type and amount of the replenisher are controlled and automatically supplied according to the calculation result.

[0073]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the invention. Examples 1 to 3, Comparative Example 1 An aluminum plate (0.24 mm thick) was degreased in a 5% by weight aqueous sodium hydroxide solution at 60 ° C. for 1 minute, and then the concentration was 0.5 mol / L. In hydrochloric acid aqueous solution at a temperature of 28 ° C., a current density of 60 A / dm ² and a treatment time of 4
Electrolytic etching was performed under the condition of 0 second. Then, after washing with water, a 60% aqueous solution of 4% by weight sodium hydroxide was added.
After desmutting for 2 seconds and washing with water, in a 20% by weight sulfuric acid solution, the temperature is 20 ° C., the current density is 3.5 A / dm ² ,
The anodic oxidation treatment was performed under the condition of a treatment time of 1 minute. In addition, 8
Hot water sealing treatment was performed for 20 seconds with hot water at 0 ° C., followed by washing with water and drying to prepare an aluminum plate for a lithographic printing plate support.
The average roughness Ra of the plate surface was 0.6 μm by a surface roughness meter (“SE-3DH” manufactured by Kosaka Laboratory Co., Ltd.).

A coating solution having the following composition was applied to the surface of the obtained aluminum plate support using a wheeler.
After drying at 90 ° C. for 2 minutes, post-heating treatment is performed at 55 ° C. for 16 hours to obtain a positive photosensitive lithographic plate having a positive photosensitive composition layer having a dry film thickness of 2.1 g / m ^2. A printing plate was prepared.

[0075]

Table 1 Photothermal conversion substance: 10 parts by weight of the following indole dye (a): Novolak resin: A mixed phenol of phenol / m-cresol / p-cresol = 20/50/30 (molar ratio) is polycondensed with formaldehyde. Combined resin (weight average molecular weight: 4,000) 100 parts by weight Dissolution inhibitor 1: Acid-color-forming dye (b) having a lactone skeleton having the following structure: 10 parts by weight Dissolution inhibitor 2: Novolak resin and the following compound (c) Ester-bonded 10 parts by weight Hydrophilic surfactant: Compound shown in Table 1 Blending amount shown in Table 1 Lipophilic surfactant: GO-4 Blending amount shown in Table 1 Organic acid: 1, 6 parts by weight of 2-cyclohexanedicarboxylic acid Crosslinking agent: 1 part by weight of Cymel C-300 (melamine-based crosslinking agent) manufactured by Mitsui Cytec Co., Ltd. Coatability improver: Surflon S- manufactured by Asahi Glass Co., Ltd. 381 (fluorinated surfactant) 0.0025 parts by weight Solvent 1: 735 parts by weight of methyl cellosolve Solvent 2: 184 parts by weight of ethyl cellosolve However, GO-4: polyoxyethylene sorbite tetraoleate (“GO4” manufactured by Nikko Chemicals Co., Ltd.) HLB =
8.5).

[0076]

Embedded image

For each of the positive photosensitive lithographic printing plates described above,
An exposure apparatus using a semiconductor laser having a wavelength of 830 nm as a light source ("Trend Setter 3244, manufactured by Creo Corporation")
T ") at an intensity of 113 mJ / cm ² ,
Subsequently, development was performed at 28 ° C. with a developer (new solution) having the following composition. [Developer composition] KOH 3.1 parts by weight Potassium silicate A 21 parts by weight Amogen K 0.3 parts by weight DLP-10 0.2 parts by weight A15 0.07 parts by weight Demineralized water 76 parts by weight However, Amogen K: betaine Type amphoteric surfactant ("Amogen K" manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), DLP-10: phosphate compound ("NIKKOL" manufactured by Nikko Chemicals Co., Ltd.)
DLP10, HLB = 17.0 "), A15: oleic acid highly sulfated oil (" Pionin A1 "manufactured by Takemoto Yushi Co., Ltd.)
5 ").

(Evaluation of residual film ratio: time required for the unexposed portion to reach a residual film ratio of 90%: t1) For each of the obtained lithographic printing plates, the reflection density before and after development in the image area was measured using a reflection densitometer (manufactured by Macbeth Co.) "RD-514"), the remaining film ratio of the image portion was calculated based on the following equation, and evaluated according to the following criteria. Remaining film ratio (%) = [(reflection density of image area after development−reflection density of support surface) / (reflection density of plate surface before development−reflection density of support surface)] × 100 Was calculated until the residual film ratio became 90% (development time).

(Evaluation of Removability: Time to reach 3% of residual film ratio in exposed area: t2) In the same manner as in the above evaluation of residual film rate, arrival time until the residual film rate of exposed area reaches 3%. Was calculated. (Evaluation of development latitude: current lattice index) From the evaluation of residual film ratio (t1) and the evaluation of removability (t2), (t1-t2)
The value of / t1 was determined as an index of development latitude. The larger the development latitude index is, the larger the development latitude is. The results of each evaluation are shown in Table 1 below, and it can be seen that all the printing plates have almost the same development latitude with a new developer.

[0080]

[Table 2] However, MYS-25: polyethylene glycol monostearate (“MYS-25” manufactured by Nikko Chemicals; HLB
= 15.0), MYS-10: polyethylene glycol monostearate (“MYS-1” manufactured by Nikko Chemicals Co., Ltd.)
0 "; HLB = 11.0).

(Running Adequacy Evaluation) Next, each plate was subjected to a developing treatment with a developing solution having the following composition so as to be 1.4 m ² / L, to prepare a fatigue developing solution for each plate. . Each plate was developed at 28 ° C. using the obtained fatigue developer. [Developer Composition] 3.1 parts by weight of KOH 21 parts by weight of potassium silicate A 0.3 parts by weight of Ammogen K 0.2 parts by weight of DLP-10 0.07 parts by weight of A15 76 parts by weight of deionized water The results are shown in Table 2. As can be seen from Table 2, the printing plate not containing a hydrophilic surfactant (Comparative Example 1) had a narrower development latitude when treated with a fatigue developer, whereas a printing plate containing a hydrophilic surfactant did not. Printing plate (Examples 1 to 5)
In (3), even when processed with the fatigue developing solution, the development latitude when processed with the new solution is relatively maintained.

[0082]

[Table 3]

Examples 4 to 20, Comparative Example 2 Photosensitive composition of the positive photosensitive lithographic printing plate used in Comparative Example 1
Dissolved amount of material is 1.4m ^Two/ L of the following composition
Developing treatment was carried out with a developing solution to prepare a fatigue developing solution. [Developing solution composition] 3.1 parts by weight of KOH 21 parts by weight of potassium silicate A 0.3 parts by weight of amogen K 0.2 parts by weight of DLP-10 A150 0.07 parts by weight Demineralized water 76 parts by weight Amogen K: betaine-type amphoteric surfactant (Daiichi
"Amogen K" manufactured by Kogyo Seiyaku Co., Ltd.), DLP-10: phosphorus
Acid ester compound (NIKKOL manufactured by Nikko Chemicals Co., Ltd.
 DLP10 ”), A15: Oleic acid highly sulfated oil
("Pionin A15" manufactured by Takemoto Yushi Co., Ltd.).

Next, the surfactants shown in Table 3 were added to the above-mentioned fatigue developing solution in the amounts shown in Table 3,
Fatigue developers containing various surfactants were prepared. Note that the fatigue developer used in Comparative Example 2 did not contain a surfactant. For the positive photosensitive lithographic printing plate of Comparative Example 1, an exposure apparatus using a semiconductor laser having a wavelength of 830 nm as a light source (“Trend Sette” manufactured by Creo Corporation).
r 3244T ”) at an intensity of 100 mJ / cm ² , and then developed at 28 ° C. with a fatigue developer containing the various surfactants described above. The residual film rate evaluation and the removability evaluation were measured in the same manner as in Example 1 above.

[0085]

[Table 4]

In Table 1, the symbols in the column of surfactant indicate the following corresponding to the trade names of surfactants manufactured by Nikko Chemicals. The numbers in parentheses indicate the number of repetitions of polyoxyethylene.

[0087]

[Table 5] GO430 Polyoxyethylene tetraoleate sorbate (30) GO460 Polyoxyethylene tetraoleate sorbite (60) MYS10 Monostearate PEG (10) MYS25 Monostearate PEG (25) MYS40 Monostearate PEG (40) DLP10 Sodium polyoxyethylene lauryl ether phosphate (10) HCO-100 Polyoxyethylene hydrogenated castor oil (100) TL-10 Polyoxyethylene monococonut oil fatty acid sorbitan (20) BWA40 Polyoxyethylene lanolin alcohol (40) PBC34 POE ( 20) POP (4) Cetyl ether (20) BC40 Polyoxyethylene cetyl ether (40) BO50 Polyoxyethylene oleyl ether (50) NP20 Polyoxyethylene nonyl phenyl ether (20) OP30 Polyoxyethylene octyl phenyl ether (30)

[0088]

According to the present invention, it is possible to provide a plate making method of a positive photosensitive lithographic printing plate having a large developing latitude and excellent processing stability.

Continued on the front page F term (reference) 2H025 AA04 AA12 AB03 AC08 AD03 BH02 CB29 CB42 CC04 CC11 FA10 FA17 2H096 AA06 BA09 EA04 EA23 GA11

Claims (12)

[Claims] 1. A photosensitive lithographic printing plate having a positive-type photosensitive composition layer containing (A) a photothermal conversion substance and (B) an alkali-soluble resin on a support, followed by laser exposure, and then an alkali developer. In the method of making a positive photosensitive lithographic printing plate developed by the method described in (1), the photosensitive composition layer comprises (C) HLB10.
The method of making a positive photosensitive lithographic printing plate, wherein the alkali developer contains (D) a surfactant having an HLB of 10 or more. 2. The positive photosensitive composition according to claim 1, wherein the concentration of the surfactant having an HLB of 10 or more in the alkaline developer is controlled in accordance with the amount of the photosensitive composition eluted by the development. Plate making method for lithographic printing plates. 3. When the photosensitive composition contains a surfactant having an HLB of 10 or more, the concentration of the surfactant having an HLB of 10 or more in the developing solution can be adjusted according to the amount of the photosensitive composition eluted by development. 3. The method according to claim 2, wherein the control is performed.
A plate-making method for a positive photosensitive lithographic printing plate as described in 1 above. 4. By holding a surfactant having an HLB of 10 or more in a place other than the photosensitive composition layer of the photosensitive lithographic printing plate, the amount of the photosensitive composition eluted by development can be adjusted according to the amount of the photosensitive composition. 3. The method according to claim 2, wherein the concentration of the surfactant having an HLB of 10 or more is controlled. 5. The concentration of the HLB 10 or more surfactant in the developer is controlled by additionally replenishing the HLB 10 or more surfactant in the developer according to the amount of the photosensitive composition eluted by the development. The method of making a positive photosensitive lithographic printing plate according to claim 2, wherein 6. The amount X (g) of the eluted photosensitive composition and H
The relationship with the amount Y (g) of the surfactant having an LB of 10 or more is defined as 0.
6. Control is performed in the range of 001X ≦ Y ≦ 0.5X.
A method of making a positive photosensitive lithographic printing plate according to any one of the above. 7. The method for making a positive photosensitive lithographic printing plate according to claim 1, wherein the surfactant having an HLB of less than 10 in the photosensitive composition layer is a polyoxyethylene sorbite fatty acid ester. 8. The method of making a positive photosensitive lithographic printing plate according to claim 1, wherein the content of the surfactant in the photosensitive composition layer is 2 to 8% by weight. 9. The method according to claim 1, wherein the average value of the HLB of the surfactant in the developer is controlled in the range of 8 to 12.
A plate-making method for a positive photosensitive lithographic plate according to any one of claims 1 to 8. 10. The method for making a positive photosensitive lithographic printing plate according to claim 1, wherein the alkali-soluble resin contains a novolak resin. 11. The method of making a positive photosensitive lithographic printing plate according to claim 1, wherein the photosensitive composition layer has substantially no sensitivity to ultraviolet light. 12. A laser exposure wavelength of 650 to 1300.
The method of making a positive photosensitive lithographic printing plate according to any one of claims 1 to 11, which is in the range of nm.