JPH10282643A - Positive photosensitive lithographic printing plate - Google Patents

Abstract

(57) [Problem] To provide a novel positive photosensitive lithographic printing plate excellent in contrast and having a sufficient residual film ratio in an image area. SOLUTION: In an exposed part and a non-exposed part, as a component of a positive photosensitive composition that causes a difference in solubility in an alkali developing solution mainly due to a change other than a chemical change, (a) a photothermal conversion material (b) an alkali-soluble material A positive photosensitive lithographic plate obtained by providing a positive photosensitive composition containing a resin on a support, wherein the positive photosensitive composition further contains an organic acid or an organic acid salt, And / or a positive photosensitive lithographic printing plate characterized in that the surface of the support has been previously treated with the organic acid or organic acid salt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a 650 to 1300
The present invention relates to a novel positive photosensitive lithographic printing plate for light in the wavelength range of nm. More specifically, semiconductor lasers and YAG
The present invention relates to a positive photosensitive lithographic printing plate suitable for direct plate making using a laser or the like.

[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.

On the other hand, conventionally, as an image forming method utilizing laser exposure or heat sensitivity, a method of forming a color material image using a sublimation transfer dye and a method of preparing a lithographic plate have been known. In the latter case, for example, a method of preparing a lithographic printing plate utilizing a crosslinking reaction of a diazo compound (for example, Japanese Patent Application Laid-Open No.
No. 1732, Japanese Patent Application Laid-Open No. 50-15603, Japanese Patent Publication No. 3-3
No.4051, No.61-21831, No.60-
No. 12939, U.S. Pat. No. 3,664,737 or the specification), a method of preparing a lithographic printing plate utilizing a decomposition reaction of nitrocellulose (for example, Japanese Patent Application Laid-Open No.
No. 102403, JP-A-50-102401) and the like.

In recent years, a technique of combining a chemically amplified photoresist with a long-wavelength light-absorbing dye has been found. For example, JP-A-6-43633 discloses a photosensitive material in which a specific squarylium dye is combined with a photoacid generator, a binder and the like. Further, as a technique similar to this, there has been proposed a technique of preparing a lithographic printing plate by imagewise exposing a photosensitive layer containing an infrared absorbing dye, a latent Bronsted acid, a resol resin and a novolak resin to an image by a semiconductor laser or the like ( JP-A-7-20629), and further, s- is substituted for the latent Bronsted acid.
A technique using a triazine compound has also been disclosed (JP-A-7-271029).

Japanese Patent Application Laid-Open No. 9-43847 discloses a resist material which changes the crystallinity of a photosensitive material by heating by irradiation with infrared rays, and a pattern forming method using the same. However, according to our studies, these conventional techniques have not always had sufficient properties for practical use. For example, in the case of a photosensitive material that requires a heat treatment after exposure, the stability of the quality of an image obtained due to the fluctuation of the processing condition is not always satisfied. On the other hand, in the case of a photosensitive material that does not require such a heat treatment after exposure, the contrast in the exposed and unexposed areas is insufficient. As a result, non-image areas are not sufficiently removed, The residual film ratio of the line portion was not sufficiently maintained. Further, the lithographic printing plate did not always have sufficient printing durability.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, that is, the object of the present invention is to
An object of the present invention is to provide a novel positive photosensitive lithographic printing plate excellent in contrast and having a sufficient residual film ratio in an image area. Still another object is to provide a novel positive photosensitive lithographic printing plate having a sufficient printing durability.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to provide the following constitutions of the present invention, that is, a positive type in which the solubility in an alkali developing solution causes a difference between an exposed portion and a non-exposed portion mainly due to a change other than a chemical change. A positive-type photosensitive lithographic plate comprising a support and a positive-type photosensitive composition containing (a) a photothermal conversion substance and (b) an alkali-soluble resin as components of the photosensitive composition. Or the organic composition further comprises an organic acid or an organic acid salt, and / or the surface of the support is preliminarily treated with the organic acid or the organic acid salt. This is achieved by a positive working photosensitive lithographic printing plate.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. Hitherto, as a positive photosensitive composition, a system containing an alkali-soluble resin and a compound containing an o-quinonediazide group as a photosensitizing component has been known. In this system, by irradiating ultraviolet light that can be absorbed by the o-quinonediazide group-containing compound, the diazo moiety is decomposed and finally a carboxylic acid is generated, thereby increasing the alkali solubility of the photosensitive composition. It is considered that an image is formed by dissolving only the exposed portion in the alkaline developer. Therefore, in this system, the components in the photosensitive composition are accompanied by a chemical change.

On the other hand, the present invention provides a photosensitive lithographic printing plate capable of forming a positive image with a very simple system in which a chemical change of a photothermal conversion material and an alkali-soluble resin cannot be expected. .

[0010] Such an effect is mainly caused by a change other than a chemical change. For example, when the photosensitive lithographic printing plate of the present invention which has been once irradiated with light is heated at about 50 ° C for 24 hours, immediately after exposure, It can also be inferred from the fact that the increased alkali solubility of the exposed part often returns to a state close to that before the exposure, which is a reversible phenomenon. Furthermore, as a result of examining the relationship between the glass transition temperature (or softening point) of the photosensitive composition itself and the degree of difficulty of the reversible phenomenon, it was found that the lower the transition temperature, the more likely the reversible phenomenon occurs. This fact also supports the mechanism described above.

The reason why the photosensitive lithographic printing plate of the present invention forms such a positive image is not always clear, but the light energy absorbed by the photothermal conversion material is converted into heat, and the heat-receiving portion It is considered that the alkali-soluble resin causes a change other than a certain chemical change such as a conformational change and the alkali solubility of the portion is increased, whereby an image is formed by an alkali developer. We have previously proposed a photosensitive composition and a photosensitive lithographic printing plate that form a positive image by a change other than such a chemical change (for example, Japanese Patent Application Nos. 8-207003, 8-302722, and 9-9264). .

[0012] Furthermore, we have recently reported that the technology of the present invention can improve the removability of exposed portions (non-image portions) and the phenomenon of film thinning of image portions during plate making of this type of positive photosensitive lithographic printing plate. Although it has been found, it is presumed that the reason is, for example, due to the following mechanism. That is, in the case of a photosensitive material that is solubilized in a developing solution by utilizing such a change in physical properties, the change is insufficient due to thermal diffusion near the surface of the support, and dissolution and removal of the photosensitive layer are difficult. Not enough. In this regard, it is considered that this is basically different from the conventional positive type photosensitive material using the photon mode quinonediazide. Therefore, when an organic acid or an organic acid salt (hereinafter, these are referred to as organic acid compounds) is adhered to the surface of a support as in the present invention, even when the organic acid or the organic acid salt is blended in a photosensitive layer, a highly polar organic compound is used. It is considered that the acid compound gathered near the surface of the support having the same polarity and improved the removability of the positive image. As a result, excessive development was not required, and the residual film ratio in the image area could be improved.

That is, the photosensitive layer used in the positive photosensitive lithographic printing plate according to the present invention comprises, as an essential component, (a)
It contains a light-to-heat conversion material as the component and an alkali-soluble resin as the component (b), and further contains an organic acid compound as a treating agent for the photosensitive layer component and / or the surface of the support. The photosensitive layer used in the present invention may further contain components. For example, it may contain a dissolution inhibitor having an action of lowering the alkali solubility of the photosensitive layer.Also, apart from these dissolution inhibitors, the alkali solubility of the photosensitive layer in the exposed portion is accompanied by a chemical change. It should also be understood that the inclusion of a compound having an enhancing effect by the above is allowed.

First, the photothermal conversion material, which is the first component used in the positive photosensitive composition of the present invention, is not particularly limited as long as it generates heat when irradiated with light. The light-absorbing dye (a) (hereinafter, referred to as a light-absorbing dye) having an absorption band in a part or the entirety of the region of 650 to 1300 nm, which will be mainly described below. The light-absorbing dye used in the present invention efficiently absorbs light in the wavelength range of 650 to 1300 nm, while light in the ultraviolet region hardly absorbs, or is substantially insensitive to absorption, and is used in white light. It is a compound that has no function of denaturing the photosensitive composition depending on the weak ultraviolet rays contained. Table 1 shows specific examples of these light absorbing dyes.

[0015]

[Table 1]

[0016]

[Table 2]

[0017]

[Table 3]

[0018]

[Table 4]

[0019]

[Table 5]

[0020]

[Table 6]

[0021]

[Table 7]

[0022]

[Table 8]

[0023]

[Table 9]

[0024]

[Table 10]

[0025]

[Table 11]

[0026]

[Table 12]

[0027]

[Table 13]

[0028]

[Table 14]

[0029]

[Table 15]

[0030]

[Table 16]

Of these, cyanine dyes, polymethine dyes, squarylium dyes, croconium dyes, pyrylium dyes, and thiopyrylium dyes are preferred. Further, a cyanine dye, a polymethine dye, a pyrylium dye, and a thiopyrylium dye are more preferable. Among these, a particularly preferred dye is a cyanine dye represented by the following general formula [I] or a polymethine dye represented by the following general formula [II] in a wavelength range of 650 to 900 nm, and a wavelength range of 800 to 1300.
In nm, it is a pyrylium dye or a thiopyrylium dye represented by the following general formula [III].

[0032]

Embedded image

[Wherein, R¹, R^TwoHas a substituent
Good C₈The following alkyl groups, wherein the substituents are
Nyl group, phenoxy group, alkoxy group, sulfonic acid group,
A carboxyl group; Q¹May have a substituent
Heptamethine group, wherein the substituent is C₈The following al
A kill group, a halogen atom, an amino group,
The tin group is bonded to the substituents on the two methine carbons
Optionally formed cyclohexene formed by
May contain a ring or a cyclopentene ring
And the substituent is C₆The following alkyl groups or halogen sources
Child; m¹, M ^TwoIs each 0 or 1;
Z¹, Z^TwoIs a group of atoms necessary to form a nitrogen-containing heterocyclic ring.
Yes; X^-Represents a counter anion. ]

[0034]

Embedded image

[Wherein, R ^{3 to} R ⁶ are an alkyl group of C ₈ or less; Z ⁴ and Z ⁵ are an aryl group which may have a substituent, and the aryl group is a phenyl group, naphthyl group, a furyl group or a thienyl group, the substituents C ₄
An alkyl group, a dialkylamino group having a C ₈ an alkyl group, a C ₈ an alkoxy group and a halogen atom. Q ² represents a trimethine group or a pentamethine group; X ⁻ represents a counter anion. ]

[0036]

Embedded image

Wherein Y ¹ and Y ² are an oxygen atom or a sulfur atom; R ⁷ , R ⁸ , R ¹⁵ and R ¹⁶ are a phenyl group or a naphthyl group which may have a substituent; the substituent is an C ₈ an alkyl group or a C ₈ an alkoxy group; l ¹ and l ² each independently represents 0 or 1; R ⁹ ~R ¹⁴ is hydrogen atom or C ₈ an alkyl group Or independently represent R ⁹ and R ¹⁰ , R ¹¹ and R ¹²
Or R ¹³ and R ¹⁴ are mutually bonded

[0038]

Embedded image

(However, R¹⁷~ R¹⁹Is a hydrogen atom or C₆Less than
It is a lower alkyl group, and n represents 0 or 1. ) Ream
A linking group may be formed; Z^ThreeIs a halogen atom or hydrogen
Atom x ^-Represents a counter anion. In the above formulas [I], [II] and [III],
On X^-Specifically, for example, Cl^-, Br^-,
I^-, ClO_Four ^-, BF_Four ^-, PF₆ ^-Inorganic acid ani such as
On, benzenesulfonic acid, p-toluenesulfonic acid,
Organic acids such as naphthalene-1-sulfonic acid and acetic acid
Can be mentioned. The invention of these light absorbing dyes
The proportion used in the positive photosensitive composition of
Preferably 0.1-30%, more preferably 1-20
%, More preferably 2 to 10%.

Next, the alkali-soluble resin (hereinafter, referred to as polymer or resin) (b) as the second component used in the positive photosensitive composition of the present invention will be described. The alkali-soluble resin basically has a difference in solubility in an alkali developing solution between the exposed material and the unexposed portion mainly due to a change other than a chemical change in combination with the photothermal conversion material of the component (a). This 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 an alkali-soluble resin such as a novolak resin, a resol resin, a polyvinylphenol resin, and a copolymer of an acrylic acid derivative. Of these, a novolak resin or a polyvinylphenol resin is preferable.

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. The polystyrene estimated weight average molecular weight by gel permeation chromatography (hereinafter abbreviated as GPC) measurement of the novolak resin (hereinafter, the weight average molecular weight by GPC measurement is abbreviated as Mw) is preferably 1,000 to 15,000, and particularly preferably. Of 1,500 to 10,000 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.

As the polyvinyl phenol resin, o-
Hydroxystyrenes such as hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene, 2- (o-hydroxyphenyl) propylene, 2- (m-hydroxyphenyl) propylene, and 2- (p-hydroxyphenyl) propylene; Two or more polymers are mentioned. Hydroxystyrenes may have a halogen such as chlorine, bromine, iodine or fluorine or a substituent such as a C ₁ -C ₄ alkyl substituent on the aromatic ring. or include better polyvinyl phenol which may have an alkyl substituent of C ₁ -C _4.

The polyvinylphenol resin is usually obtained by polymerizing hydroxystyrenes which may have a substituent alone or in the presence of two or more hydroxystyrenes in the presence of a radical polymerization initiator or a cationic polymerization initiator. Such a polyvinyl phenol resin may be partially hydrogenated. Further, a resin in which some OH groups of polyvinylphenols are protected by a t-butoxycarbonyl group, a pyranyl group, a furanyl group, or the like may be used. Mw of the polyvinyl phenol resin is preferably 1,000 to 100,000.
0, particularly preferably 1,500 to 50,000.

The polyvinyl phenol resin is more preferably a polyvinyl phenol which may have an alkyl substituent having a carbon number of C _{1 to} C _{4 on} the aromatic ring, and unsubstituted polyvinyl phenol is particularly preferred. If the Mw of the novolak resin or the polyvinyl phenol resin is smaller than the above range, a sufficient coating film cannot be obtained. If the Mw is larger than the above range, the solubility of the unexposed portion in an alkali developing solution is reduced, and a pattern is obtained. Tend not to be.

Among the above resins, a novolak resin is particularly preferred. The proportion of these resins used in the positive photosensitive composition comprising component (a) and component (b) used in the present invention is preferably 70% to 99% by weight.
9%, more preferably 80% to 99%, particularly preferably 90 to 98%. An organic acid compound is further used in the positive photosensitive lithographic plate of the present invention. It is incorporated as a component in the photosensitive layer and / or is used as a component of a treating agent or a subbing agent on the surface of a support carrying the photosensitive layer. Examples of the organic acid compound include a carboxyl group, a sulfonic acid group, a sulfinic acid group,
Examples thereof include compounds having a group selected from a phosphonic acid group and a phosphinic acid group, and organic acids such as phosphoric acid mono- or diester compounds, and salts thereof.

Specifically, for example, oxalic acid, maleic acid,
Succinic acid, citric acid, malic acid, lactic acid, benzoic acid, phthalic acid, poly (meth) acrylic acid, (meth) acrylic acid /
Compounds having a carboxyl group such as a copolymer of alkyl (meth) acrylate, a copolymer of maleic acid / styrene and carboxymethyl cellulose; benzenesulfonic acid, p-toluenesulfonic acid, 1-naphthalenesulfonic acid, 2-naphthalenesulfonic acid, styrenesulfone Compounds having sulfonic acid groups such as acid / maleic acid copolymers; polyvinylphosphonic acid, copolymers of vinylphosphonic acid / monomethyl vinylphosphonate, compounds having phosphonic acid groups such as methylphosphonic acid; mono (methacryloxyethyl) phosphate And organic acids such as phosphoric acid esters such as bis (methacryloxyethyl) phosphate and salts corresponding thereto.

The counter cation in the case of having a salt structure includes
Examples include alkali metal ions such as sodium and potassium, and amine bases such as NH ₄ ⁺ and quaternary ammonium. When a compound having a carboxyl group is used as the organic acid compound, a polymer of (meth) acrylic acid or a copolymer containing (meth) acrylic acid is more preferable. When these organic acid compounds are used by being blended in the photosensitive layer, the amount added is preferably 0.1 to 10% by weight based on the total amount of the (a) photothermal conversion substance and (b) the alkali-soluble resin. , More preferably 0.2 to 5%
Good to use.

When an organic acid compound is used as a component of a treating agent or an undercoating agent for a support, it is usually used by dissolving it in water or an alcohol. If necessary, other components such as a binder and the like are used. And the support is immersed in the solution or applied and dried to prepare a support. The amount of the organic acid compound adhering to the surface of the support is not particularly limited, and a range that provides suitable various properties may be determined and used, but is usually 0.5 g / m ² or less.
The photosensitive composition used in the present invention comprises, as components thereof, a dissolution inhibitor (c) capable of reducing the dissolution rate of a composition comprising the photothermal conversion substance (a) and the alkali-soluble resin (b) in an alkaline developer. (Hereinafter, simply referred to as a dissolution inhibitor).

When the photosensitive composition of the present invention contains a dissolution inhibitor, the photosensitive composition often shows good positive photosensitive characteristics. In the present composition, the action of the dissolution inhibitor is not necessarily clear,
At least, the light-sensitive material of the present composition exhibits a dissolution inhibiting property in a developer by adding the dissolution inhibitor in a non-exposed area, but not only does the effect disappear in the exposed area, but often exhibits a dissolution accelerating effect. That is, it is considered that the effect of increasing the contrast between the exposed portion and the unexposed portion is exhibited, and as a result, a favorable positive image is obtained.

Since the photosensitive composition of the present invention contains the alkali-soluble resin (b) and the photothermal conversion substance (a) as essential components, the dissolution inhibitor (c) is used as described above. Although it shows an action of inhibiting the dissolution of the blends of (a) and (b), it is considered that it substantially inhibits the dissolution of the alkali-soluble resin (b). The dissolution inhibitor must be at least a compound that suppresses the dissolution rate of the composition comprising the components (a) and (b) in an alkaline developer to 80% or less by the addition of the dissolution inhibitor. When the dissolution rate is 50% or less,
The compound is more preferably suppressed to 30% or less.

As a simple method for measuring the dissolution inhibiting effect,
For example, first, a predetermined amount of the blend of the components (a) and (b) is applied on a support, and the resultant is immersed in the alkaline developer. Ask for. Next, after adding a predetermined amount of the dissolution inhibitor and the sample to the above-mentioned composition, the mixture is applied with the same film thickness as before, and the relationship between the immersion time and the film thickness reduction amount is similarly determined. From these measured values, the dissolution rate ratio of both can be determined,
The dissolution rate reduction effect of the sample of the dissolution inhibitor used can be measured as its relative speed.

It has been found that a wide range of compounds can be applied as effective dissolution inhibitors used in the present invention. However, since the dissolution inhibitor must remain stably in the photosensitive layer, it is solid at normal temperature and pressure, or has a boiling point of 180 at normal pressure.
It is preferably a liquid at a temperature of at least ° C. Illustrative of these effective compounds are sulfonic acid esters, phosphoric acid esters, aromatic carboxylic acid esters, aromatic disulfones, carboxylic anhydrides, aromatic ketones, aromatic aldehydes, aromatic amines and aromatic ether compounds. These can be used alone or in combination of two or more.

Further specific examples thereof include, for example, ethyl benzenesulfonate, benzenesulfonate-
n-hexyl, phenyl benzenesulfonate, benzyl benzenesulfonate, phenylethyl benzenesulfonate, ethyl p-toluenesulfonate, t-butyl p-toluenesulfonate, n-octyl p-toluenesulfonate, p-toluene 2-ethylhexyl sulfonic acid, phenyl p-toluenesulfonate, phenylethyl p-toluenesulfonate, ethyl 1-naphthalenesulfonate, phenyl 2-naphthalenesulfonate, benzyl 1-naphthalenesulfonate, phenylethyl 1-naphthalenesulfonate , Sulfonates such as bisphenol A dimethyl sulfonate; trimethyl phosphate, triethyl phosphate, tri (2-ethylhexyl) phosphate, triphenyl phosphate, tritolyl phosphate, tricresyl phosphate, and tri- ( - phosphoric acid esters naphthyl) and the like; benzoic acid, benzoic acid n- heptyl, phenyl benzoate, benzoic acid 1-naphthyl, 1-pyridinecarboxylic acid n- octyl, tris (n- butoxycarbonyl)
Aromatic carboxylic esters such as -s-triazine; carboxylic anhydrides such as mono-, di- or trichloroacetic anhydride, phenylsuccinic anhydride, maleic anhydride, phthalic anhydride and benzoic anhydride; benzophenone, acetophenone , Benzyl, aromatic ketones such as 4,4'-dimethylaminobenzophenone; aromatic aldehydes such as p-dimethylaminobenzaldehyde, p-methoxybenzaldehyde, p-chlorobenzaldehyde, 1-naphthaldehyde; triphenylamine, diphenylamine ,
Aromatic amines such as tolylamine and diphenylnaphthylamine; ethylene glycol diphenyl ether;
2-methoxynaphthalene, diphenyl ether, 4,
Aromatic ethers such as 4'-diethoxybisphenol A can be mentioned. These compounds may be substituted with a substituent that does not impair the effects of the present invention, such as an alkyl group, an alkoxy group, a halogen atom, and a phenyl group. Furthermore, it may have a structure incorporated in a polymer or a resin, and examples thereof include a novolak resin and a sulfonic acid ester carried by an ester bond to a hydroxyl group of polyvinyl phenol. Gives a deterrent effect.

Examples of these dissolution inhibitors include those having a structure sensitive to ultraviolet light in their structure, for example, o
A good image can be obtained even when an o-quinonediazide group-containing compound such as quinonediazidesulfonic acid ester or an aromatic disulfone such as diphenyldisulfone is contained. However, in this case, it is usually necessary to work under a yellow light. Accordingly, a more preferred embodiment of the present invention is a technique using a dissolution inhibitor having substantially no sensitivity to ultraviolet light. They are photosensitive materials that can withstand long-term work in a white light environment.
Brings great benefits. These dissolution inhibitors (c) optionally used are preferably added in an amount of preferably not more than 50% by weight, more preferably not more than 40% by weight, based on the total weight of the above components (a) and (b). You may.

When an o-quinonediazide group-containing compound is used as a dissolution inhibitor, a positive image can be obtained by the same action as in the prior art when the photosensitive composition is irradiated with ultraviolet rays. The composition preferably has a wavelength range of 6
It is characterized in that an image is formed by light having a wavelength of 50 to 1300 nm, and it is considered that a photodecomposition reaction of an o-quinonediazide group-containing compound cannot substantially occur in this wavelength range. However, since 1,2-diazoketones such as o-quinonediazide group-containing compounds are known to cause a decomposition reaction even by heat, the wavelength range is 650 to 1300.
When irradiated with light of nm, it is considered that it is decomposed by the heat converted by the light-absorbing dye, and as a result, the effect of increasing the alkali solubility of the exposed portion is also caused.

In addition to the o-quinonediazide group-containing compound, the dissolution inhibitor thermally undergoes a chemical change by light irradiation in the wavelength range of 650 to 1300 nm in the presence of the light absorbing dye of the component (a). Compounds such as aromatic disulfones such as diphenyldisulfone can also be used. When such a dissolution inhibitor accompanied by a thermal chemical change is used, the difference in solubility in an alkali developer between an exposed portion and a non-exposed portion may be large. The addition of auxiliary components can of course be employed as the case may be. However, in an advantageous embodiment of the present invention, the difference in developability between the exposed part and the unexposed part in the developing solution is essentially 650-130.
It should be understood that the combination of a dye that absorbs light in the wavelength range of 0 nm and an alkali-soluble resin is achieved by causing a difference in solubility in an alkali developer due to a change other than a chemical change due to light absorption.

The photosensitive composition used in the present invention is usually
The above components are used by dissolving them in an appropriate solvent. 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-
Ester solvents such as hydroxybutyrate, ethyl acetoacetate, methyl lactate, ethyl lactate, methyl 3-methoxypropionate, heptanol, hexanol,
Alcohol solvents such as diacetone alcohol and furfuryl alcohol, ketone solvents such as cyclohexanone and methyl amyl ketone, highly polar solvents such as dimethylformamide, dimethylacetamide and N-methylpyrrolidone, or mixed solvents thereof, and furthermore, Those to which an aromatic hydrocarbon is added are 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.

The photosensitive composition of the present invention may contain various additives, for example, dyes and pigments, as long as the performance is not impaired.
It may also contain a coating improver, a development improver, an adhesion improver, a sensitivity improver, a sensitizer, and the like. As a coating method used when providing the photosensitive composition used in the present invention on the surface of the support, conventionally known methods, for example, spin coating, wire bar coating, dip coating, air knife coating, roll coating, blade coating and It is possible to use curtain coating or the like. The drying temperature or the heating temperature is, for example, 20 to 170 ° C., preferably 30 to 15 ° C.
0 ° C. is employed.

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

The surface roughness of the support is generally represented by the value of 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. As described above, the present support can be used after being subjected to a surface treatment with an organic acid compound, if necessary.

As a light source for imagewise exposing the photosensitive lithographic printing plate of the present invention, any light source can be used as long as the photothermal conversion material can achieve the intended purpose, and a light source such as a near infrared laser having a wavelength of 650 to 1300 nm is generated. A light source is preferable, and examples thereof include a ruby laser, a YAG laser, a semiconductor laser, an LED, and other solid-state lasers. A small-sized and long-life semiconductor laser or a YAG laser is particularly preferable.
With these laser light sources, a lithographic printing plate having an image can usually be obtained by developing with a developer after scanning exposure.

The laser light source usually scans the surface of the photosensitive material as a high-intensity light beam (beam) condensed by a lens. The sensitivity characteristic (mJ / mJ / m) of the positive type lithographic printing plate of the present invention which responds to the light beam is scanned. cm ² ) may depend on the light intensity (mJ / s · cm ² ) of the laser beam received on the photosensitive material surface. Here, the light intensity of the laser beam (mJ
/ S · cm ² ) is the amount of energy (mJ / s) of the laser beam on the plate surface per unit time measured with an optical power meter, and the beam diameter (irradiated area; cm ² ) on the surface of the photosensitive material is measured. It can be obtained by dividing the amount of energy per unit time by the irradiation area. The irradiation area of the laser beam is usually defined as the area of the portion exceeding 1 / e ² intensity of the laser peak intensity, but it can be simply measured by exposing a photosensitive material exhibiting a reciprocity law.

The light intensity of the light source used in the present invention is preferably 2.0 × 10 ⁶ mJ / s · cm ² or more, and 1.0 × 10 ⁷ mJ / s · cm ² or more. Is more preferred. When the light intensity is within the above range, the sensitivity characteristics of the positive planographic printing plate of the present invention are improved, and the scanning exposure time can be shortened.

As the developer used for developing the photosensitive lithographic printing plate of the present invention, an alkali developer mainly composed of an aqueous alkali solution is particularly preferred. Examples of the alkaline developer include aqueous solutions of alkali metal salts such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium metasilicate, potassium metasilicate, dibasic sodium phosphate, and tertiary sodium phosphate. No. The concentration of the alkali metal salt is preferably from 0.1 to 20% by weight. or,
If necessary, an anionic surfactant, an amphoteric surfactant, or an organic solvent such as alcohol can be added to the developer.

[0068]

(Preparation of lithographic printing plate)

[Production of Aluminum Plate] A 0.24 mm-thick aluminum plate (material 1050, tempered H16) was degreased in a 5% by weight aqueous sodium hydroxide solution at 60 ° C. for 1 minute, and then 0.5 mol In a hydrochloric acid aqueous solution having a concentration of 1 / liter, electrolytic etching was performed under the conditions of a temperature of 28 ° C., a current density of 60 A / dm ² , and a processing time of 40 seconds. Then, in a 4% by weight aqueous sodium hydroxide solution at 60 ° C., 12
After a desmutting treatment for 2 seconds, an anodic oxidation treatment was carried out in a 20% by weight sulfuric acid solution at a temperature of 20 ° C., a current density of 3.5 A / dm ² and a treatment time of 1 minute. In addition, 80 ° C
Hot water sealing treatment was performed for 20 seconds to prepare an aluminum plate as a lithographic printing plate support. The value of the average roughness Ra of this plate was 0.60 μm. The Ra value was measured using a surface roughness meter SE-3DH (manufactured by Kosaka Laboratories), scan length 4 mm, no high-frequency cutoff, low-frequency cutoff 0.
Measured under the condition of 8 mm

[Measurement Method of Coating Amount of Photosensitive Layer] A photosensitive lithographic printing plate sample obtained by coating a photosensitive solution on a support under the conditions shown in the following examples, drying and heating is used. 10
cut to the size of cm square, after measuring the weight of the sample piece, the photosensitive layer dissolved is removed by acetone, again, the decrease amount determined by measuring the weight, the coating film as the weight per 1 m ² from that value The amount was determined. In addition, the residual film ratio was determined by the same method as the amount of the remaining coating film after development, and was determined from the ratio to the initial coating film amount.

Example 1 A photosensitive solution comprising the following components was coated on an aluminum plate prepared by the above-mentioned method using a wire bar, dried at 85 ° C. for 2 minutes, and then heat-treated at 130 ° C. for 4 minutes. The amount of the coating film was 2.8 g / m ² .

[0071]

(Photosensitive solution) Polymer compound: Novolak resin PR-4 (manufactured by Sumitomo Durez) 3.2 g Light absorbing pigment: 0.096 g of S-54 Coloring material: 0.032 g of Victoria Pureable-BOH Organic acid compound : Polyacrylic acid julimer AC-10P (manufactured by Nippon Pure Chemical Co., Ltd.) 0.032 g Solvent: cyclohexanone / N-methylpyrrolidone (mixed) 16 g / 1.7 g

Next, the photosensitive lithographic printing plate was mounted on a rotating drum, and scanning exposure was performed with a laser beam (120 mW) using a YAG laser (manufactured by Applied Techno Co., 1064 nm) focused to a beam diameter of 35 μm with a lens. . Then, an alkaline developer SDR-1 (manufactured by Konica Corporation,
(For positive type lithographic plate) was diluted 8 times and developed at 25 ° C. The development time was appropriately changed until the time when a scanning positive image of 50 cm / sec was formed. The residual film ratio of the unexposed portion of the obtained image sample was measured. The results are shown in Table 2.

Example 2 Evaluation was made in the same manner as in Example 1 except that the organic acid compound was changed to 0.032 g of p-toluenesulfonic acid. The results are shown in Table-2.

Example 3 The same aluminum plate as used in Example 1 was preliminarily treated according to the following procedure. First, Julimar AC
After being immersed in an aqueous solution containing 0.3 wt% of -10 L (manufactured by Nippon Pure Chemical Co., Ltd.), it is leaned and air-dried naturally. Next, of the components of the photosensitive solution used in Example 1, the organic acid compound: AC-1
The photosensitive solution except for 0P was applied under the same conditions as in the same example, and the subsequent preparation conditions and evaluation conditions were the same as in the same example. The results are shown in Table 2.

Example 4 In Example 3, p-toluenesulfonic acid was replaced with an equivalent amount of p-toluenesulfonic acid in place of julimer AC-10L in the aluminum plate treating solution. (Manufactured by Kagaku) was dissolved in the same weight. The others were evaluated in the same manner as in Example 3. The results are shown in Table 2.

Example 5 Evaluation was made in the same manner as in Example 3 except that the same amount of polyvinylphosphonic acid was used instead of julimer AC-10L in the treatment liquid for the aluminum plate. The results are shown in Table 2.

Comparative Example 1 Evaluation was made in the same manner as in Example 1 except that the photosensitive solution except for the organic acid compound AC-10P was used. The results are shown in Table 2.

[0078]

[Table 18]

[0079]

According to the present invention, it is possible to provide a novel positive photosensitive lithographic printing plate which is excellent in contrast and has a sufficient residual film ratio in an image area.

Claims (5)

[Claims] 1. A component of a positive photosensitive composition which causes a difference in solubility in an alkali developer mainly due to a change other than a chemical change in an exposed portion and a non-exposed portion, (a) a photothermal conversion material, and (b) an alkali A positive photosensitive lithographic plate obtained by providing a positive photosensitive composition containing a soluble resin on a support, wherein the positive photosensitive composition further contains an organic acid or an organic acid salt; And / or a support type photosensitive lithographic printing plate characterized in that the surface of the support is previously treated with the organic acid or organic acid salt. 2. The light-to-heat conversion material has a wavelength range of 650 to 1300.
The positive photosensitive lithographic printing plate according to claim 1, which is a light absorbing dye having an absorption band in part or all of nm. 3. The positive photosensitive lithographic printing plate according to claim 1, wherein the solubility of the alkali-soluble resin in an alkali developer can be changed mainly by a change other than a chemical change. 4. A compound having a group selected from a carboxyl group, a sulfonic acid group, a sulfinic acid group, a phosphonic acid group, and a phosphinic acid group, mono- or diesters of phosphoric acid, or salts thereof. The positive photosensitive lithographic printing plate according to any one of claims 1 to 3, wherein 5. The method according to claim 1, wherein the support is a plate made of roughened aluminum or an aluminum alloy, and the positive photosensitive composition has a dry coating amount of 2.0 to 12.0 g / m ² . The positive photosensitive lithographic printing plate according to any one of claims 1 to 4, which is coated.