JP4437896B2 - Planographic printing plate precursor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a positive lithographic printing plate precursor, and more particularly, to a positive lithographic printing plate precursor for infrared laser for so-called direct plate making which can be directly made from a digital signal of a computer or the like.
[0002]
[Prior art]
The development of lasers in recent years has been remarkable, and in particular, solid-state lasers and semiconductor lasers having a light emitting region from the near infrared to the infrared can be easily obtained with high output and small size. These lasers are very useful as an exposure light source when directly making a plate from digital data such as a computer.
[0003]
In a known positive photosensitive image forming material for infrared laser for direct plate making, a novolak resin or the like is used as an alkaline aqueous solution-soluble resin.
For example, as a positive type photosensitive image forming material, a substance capable of generating heat by absorbing light, a variety of onium salts, quinonediazide compounds, etc., in an aqueous alkali-soluble resin having a phenolic hydroxyl group such as a novolak resin. A positive photosensitive compound, which acts as a dissolution inhibitor that substantially reduces the solubility of the aqueous alkali-soluble resin in the image area, and is heated by heat in the non-image area. There has been disclosed a technique in which an image is formed so that the dissolution inhibiting ability does not appear and can be removed by development (see, for example, Patent Document 1).
[0004]
Further, the positive photosensitive image forming material is composed of a substance that generates heat by absorbing light and a resin whose alkali aqueous solution solubility is changed by the heat. Low and non-image areas are disclosed in which an aqueous alkali solution becomes highly soluble by heat and can be removed by development to form an image (see Patent Documents 2 and 3).
[0005]
In conventional lithographic printing plate precursors, novolak resin interacts strongly with the dissolution inhibitor, so the difference in solubility in the developer between the exposed and non-exposed areas is large, and the reasons for excellent ink acceptability, etc. Therefore, it is particularly preferably used. In addition, novolak resin is also used in positive-type planographic printing plate precursors for infrared lasers for the same reason. As the novolak resin, a resin obtained by polymerizing phenols such as phenol, cresol and xylenol using formaldehyde under acidic conditions is generally used.
[0006]
However, it has been found that the lithographic printing plate precursor using the above-described novolak resin has a problem that developability deteriorates and development failure occurs with time after exposure. Such a decrease in developability with time after exposure is a problem in the plate making process, and improvement is required. (Hereinafter, the degree of change in developability after exposure is expressed by the quality of image transferability, and the greater the decrease in developability is referred to as “bad image transfer”.)
[0007]
[Patent Document 1]
JP-A-7-285275
[Patent Document 2]
International Publication No. 97/39894 Pamphlet
[Patent Document 3]
European Patent Application No. 0823327A2
[0008]
[Problems to be solved by the invention]
Therefore, the object of the present invention is excellent in the difference in solubility in the developer between the exposed area and the unexposed area (dissolvable discrimination: hereinafter referred to as “soluble disk” as appropriate), and after exposure. It is an object of the present invention to provide a positive planographic printing plate precursor having a small degree of change in developability with time (good shrinkage).
[0009]
[Means for Solving the Problems]
  As a result of intensive research,Novolac phenolic resinIt has been found that the above problem can be solved by incorporating a resin in which a part of the phenolic hydroxyl group possessed by an ether group is substituted into an image recording layer of a positive type lithographic printing plate precursor, thereby completing the present invention. It was.
[0010]
  That is, the positive type lithographic printing plate precursor according to the present invention comprises (A) a hydrophilic support.Novolac-type phenolic resin containing a partial structure represented by the following general formula (I)(Hereinafter referred to as “specific phenol resin” as appropriate) and (B) an image recording layer containing a photothermal conversion agent and having increased solubility in an alkaline aqueous solution by infrared laser exposure. And
[Chemical 2]
[In general formula (I), R ¹ Represents a linear unsubstituted alkyl group having 1 to 12 carbon atoms, a branched unsubstituted alkyl group having 3 to 12 carbon atoms, or a cyclic unsubstituted alkyl group having 5 to 10 carbon atoms, R ² , R ^Three And R ^Four Each independently represents a hydrogen atom, an alkyl group, or a halogen atom. ]
[0011]
Although the action mechanism of the present invention is not clear, it is presumed as follows.
That is, the specific phenol resin contained in the image recording layer according to the present invention has improved alkali dissolution inhibiting ability by replacing the phenolic hydroxyl group of the resin with an ether group, thereby improving the development resistance of the image area. It can improve and suppress film loss. In addition, by replacing the phenolic hydroxyl group with an ether group, the specific phenol resin has a high degree of freedom in mobility during exposure and is likely to cause a large position shift. Furthermore, recombination due to hydrogen bonding between phenolic hydroxyl groups is unlikely to occur. Since the change resulting from this, that is, the release of the dissolution inhibiting ability in the exposed portion is maintained even after the exposure that has lost the instantaneous heat due to the exposure, it is presumed that this has led to an improvement in the shrinkage.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the lithographic printing plate precursor according to the invention will be described in detail.
[0013]
[Image recording layer]
  The image recording layer according to the present invention includes (A)specificPhenolic treeFat,And (B) It is necessary to contain a photothermal conversion agent.
  First, a resin (specific phenol resin) obtained by substituting a part of the hydroxyl groups of the phenol resin (A), which is a characteristic component constituting the image recording layer according to the present invention, with an ether group will be described.
[0014]
<(A) Specific phenol resin>
  The specific phenolic resin according to the present invention isNovolac phenolic resinA resin in which a part of the phenolic hydroxyl group possessed byTherefore, it is necessary to be a novolac type phenol resin containing a partial structure represented by the following general formula (I).
[Chemical Formula 3]
[In general formula (I), R ¹ Represents a linear unsubstituted alkyl group having 1 to 12 carbon atoms, a branched unsubstituted alkyl group having 3 to 12 carbon atoms, or a cyclic unsubstituted alkyl group having 5 to 10 carbon atoms, R ² , R ^Three And R ^Four Each independently represents a hydrogen atom, an alkyl group, or a halogen atom. ]
  Here, the phenolic hydroxyl group (hereinafter referred to as “hydroxyl group” as appropriate in the description of the specific phenol resin) means a hydroxyl group directly bonded to the benzene skeleton constituting the phenol resin. The lithographic printing plate precursor according to the invention contains a phenolic resin in which a part of the hydroxyl group is substituted with an ether group in the image recording layer, so that the soluble discreet and the tempering can be performed without lowering the sensitivity. It exhibits an excellent effect on the properties.
  Although the substitution rate of the hydroxyl group to the ether group in the specific phenol resin is appropriately determined depending on the type of the phenol resin to be substituted, etc., it is preferably about 1 mol% to 50 mol%.
[0015]
  As a phenol resin constituting the specific phenol resin in the present invention,From the point of solubility of novolac type phenolic resin in alkaline developerUsed.
[0018]
The general formula (I) will be described.
  In general formula (I), R¹IsA linear unsubstituted alkyl group having 1 to 12 carbon atoms, a branched unsubstituted alkyl group having 3 to 12 carbon atoms, or a cyclic unsubstituted alkyl group having 5 to 10 carbon atomsRepresents R², R^ThreeAnd R^FourEach independently represents a hydrogen atom, an alkyl group or a halogen atom.
[0019]
  In general formula (I), R¹IsA linear unsubstituted alkyl group having 1 to 12 carbon atoms, a branched unsubstituted alkyl group having 3 to 12 carbon atoms, and a cyclic unsubstituted alkyl group having 5 to 10 carbon atoms..
  Among these, FurtherA linear alkyl group having 1 to 8 carbon atoms and a cyclic alkyl group having 5 to 7 carbon atoms are preferable, and a linear alkyl group having 3 to 7 carbon atoms is most preferable.
  Specific examples of the alkyl group include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, hexadecyl group. , Octadecyl group, eicosyl group, isopropyl group, isobutyl group, s-butyl group, t-butyl group, isopentyl group, neopentyl group, 1-methylbutyl group, isohexyl group, 2-ethylhexyl group, 2-methylhexyl group, cyclohexyl group , Cyclopentyl group, 2-norbornyl group and the like.
[0021]
In general formula (I), R²And R^ThreeIs preferably an alkyl group having 1 to 3 carbon atoms, and more preferably an alkyl group having 1 or 2 carbon atoms.
Specific examples of the alkyl group include a methyl group or an ethyl group.
In general formula (I), R^FourThe alkyl group represented by is preferably an alkyl group having 3 to 6 carbon atoms or a cycloalkyl group.
In general formula (I), R², R^ThreeAnd R^FourIs a fluorine atom, a chlorine atom, a bromine atom or an iodine atom, preferably a chlorine atom or a bromine atom.
[0022]
A more preferable embodiment of the specific phenol resin including the partial structure represented by the general formula (I) is selected from (A-1) a resin obtained by substituting a part of the hydroxyl group of the novolac type phenol resin with an alkyl ether group. Resin. A more preferred embodiment is a resin selected from (A-2) a resin obtained by substituting a part of the hydroxyl group of a novolac type phenol resin containing phenol as a structural unit with an alkyl ether group.
[0023]
<(A-1) Resin formed by substituting a part of hydroxyl group of novolak type phenolic resin with an alkyl ether group>
First, the resin (hereinafter referred to as (A-1) resin as appropriate) obtained by substituting a part of the hydroxyl group of the (A-1) novolak type phenol resin with an alkyl ether group will be described in detail.
[0024]
(A-1) As a novolak type phenol resin used for obtaining a resin, a novolac type phenol resin obtained by condensing one or more of phenols represented by the following general formula (II) with an aldehyde Is mentioned.
[0025]
[Chemical 2]
[0026]
In general formula (II), R², R^ThreeAnd R^FourEach independently represents a hydrogen atom, an alkyl group, or a halogen atom.
In general formula (II), R²And R^ThreeThe alkyl group represented by these is synonymous with the alkyl group in the said general formula (I), and its preferable range is also the same.
In general formula (II), R^FourThe alkyl group represented by these is synonymous with the alkyl group in the said general formula (I), and its preferable range is also the same.
In general formula (II), R², R^ThreeAnd R^FourThe halogen atom represented by these is synonymous with the halogen atom in the said general formula (I), and its preferable range is also the same.
[0027]
Specific examples of phenols represented by the general formula (II) include isopropylphenol, t-butylphenol, t-amylphenol, hexylphenol, cyclohexylphenol, 3-methyl-4-chloro-6-t- Examples include butylphenol, isopropyl cresol, t-butyl cresol, and t-amyl cresol. T-butylphenol and t-butylcresol are preferable.
[0028]
(A-1) Examples of aldehydes used for obtaining a novolak-type phenol resin used for the resin include aliphatic and aromatic aldehydes such as formaldehyde, acetaldehyde, acrolein, and crotonaldehyde. Formaldehyde or acetaldehyde is preferred, and formaldehyde is most preferred.
[0029]
(A-1) The substitution rate of hydroxyl groups to alkyl ether groups in the resin is preferably 1 to 80 mol%, more preferably 1 to 50 mol%, and more preferably 1 to 20 mol%. Most preferred.
[0030]
The weight average molecular weight of the (A-1) resin is preferably 1,000 to 30,000, more preferably 1,500 to 20,000, and 2,000 to 10,000. Is particularly preferred.
[0031]
The ratio of the resin (A-1) to the total solid content in the image recording layer of the lithographic printing plate precursor according to the invention is preferably 0.1% from the viewpoint of exerting the effects of the invention without reducing the sensitivity. % To 20% by weight, more preferably 0.2% to 10% by weight, and particularly preferably 0.2% to 5% by weight.
[0032]
<(A-2) Resin formed by substituting a part of hydroxyl groups of a novolak type phenol resin containing phenol as a structural unit with an alkyl ether group>
Next, a resin obtained by substituting a part of hydroxyl groups of a novolak type phenol resin containing phenol as the structural unit (A-2) with an alkyl ether group (hereinafter, appropriately referred to as (A-2) resin). This will be described in detail.
[0033]
(A-2) As a novolak-type phenol resin used in order to obtain resin, the novolak-type phenol resin formed by condensing phenol and substituted phenol with aldehydes is mentioned.
[0034]
(A-2) Examples of the aldehydes used for obtaining the novolak type phenol resin used for the resin include those described in the description of (A-1).
[0035]
(A-2) As a novolak type phenol resin used for obtaining a resin, a phenol formaldehyde resin, a phenol / cresol (any of m-, p-, or m- / p-mixed) mixed formaldehyde resin, etc. A novolak resin etc. are mentioned preferably.
[0036]
(A-2) The phenol content in the monomer constituting the novolak type phenol resin used for obtaining the resin is preferably 10 to 90 mol%, more preferably 15 to 70 mol%, Most preferred is ˜60 mol%.
[0037]
Further, the number of components other than phenol (substituted phenol component) contained in the monomer is preferably 2 or less, more preferably 1 component.
As the substituted phenol component used as one component, cresol is preferable, and m-cresol is most preferable.
A preferable combination of two components is a combination of “m-cresol” and “p-cresol, o-cresol, or xylenol”, and more preferably a combination of m-cresol and p-cresol. .
Moreover, as a component amount in the case of 2 components, what contained 10 mol% or more of m-cresol is preferable, More preferably, it is made to contain 20 mol% or more.
The amount of components other than phenol in the case of one component is preferably 10 mol% or more, more preferably 20 mol% or more, and particularly preferably 30 mol% or more.
[0038]
(A-2) The substitution rate of the hydroxyl group to the alkyl ether group in the resin is preferably 1 to 80 mol%, more preferably 1 to 60 mol%, and most preferably 1 to 50 mol%. preferable.
[0039]
(A-2) The weight average molecular weight of the resin is preferably 1,000 to 30,000, more preferably 1,500 to 20,000, and particularly 2,000 to 10,000. preferable. The number average molecular weight is preferably 500 or more, and more preferably 750 to 650,000. The dispersity (weight average molecular weight / number average molecular weight) is preferably 1.1 to 10.
[0040]
The resin (A-2) is preferably 10% by weight to 95% by weight in the total solid content of the image recording layer of the lithographic printing plate precursor, from the viewpoint of the printing durability improvement effect by the burning treatment, It is preferable that it is weight%-90 weight%.
[0041]
The specific phenol resin such as the (A-1) resin and the (A-2) resin according to the present invention may be used alone or in combination of two or more. When a general novolac resin other than the specific phenol resin according to the present invention is used in combination, the content ratio of the novolac resin other than the specific phenol resin to the total novolak resin is in the range of 5 to 90% by weight, and 10 to 80% by weight. Is preferable, and the range of 20 to 70% by weight is particularly preferable.
[0042]
A novolac-type phenol resin for substituting a part of the phenolic hydroxyl group with an alkyl ether group can be produced, for example, as follows.
That is, phenol and / or substituted phenols (for example, (A-1) resin and cresols mentioned in the description of (A-2) resin) are reacted with an aqueous formaldehyde solution in a solvent using an acid as a catalyst. The o-position or p-position in the phenol or substituted phenol component and formaldehyde can be produced by dehydration condensation.
[0043]
Dehydration condensation between the o-position or p-position of the phenol or substituted phenol component and formaldehyde can be carried out as follows.
That is, the total weight of phenol and substituted phenol components is dissolved in a solvent to a concentration of 60 to 90% by weight (preferably 70 to 80% by weight), and formaldehyde is added to this in a molar ratio to the total number of moles of phenol and substituted phenol components. Is 0.2 to 2.0 (preferably 0.4 to 1.4, particularly preferably 0.6 to 1.2), and an acid catalyst is added to the total number of moles of phenol and substituted phenol components. Add under a temperature condition of 10 ° C to 150 ° C so that the molar ratio is 0.01 to 0.1 (preferably 0.02 to 0.05), and stir for several hours while maintaining the temperature range This can be done. In addition, it is preferable that reaction temperature is the range of 70 to 150 degreeC, and it is more preferable that it is the range of 90 to 140 degreeC.
[0044]
Examples of the solvent used for the reaction include water, acetic acid, methanol, ethanol, 2-propanol, 2-methoxyethanol, ethyl propionate, ethoxyethyl propionate, 4-methyl-2-pentanone, dioxane, xylene, Examples include benzene.
[0045]
Examples of the acid catalyst include hydrochloric acid, sulfuric acid, p-toluenesulfonic acid, phosphoric acid, oxalic acid, tartaric acid, citric acid, zinc acetate, manganese acetate, cobalt acetate, magnesium methylsulfonate, aluminum chloride, and zinc oxide. Can be mentioned.
[0046]
The specific phenol resin according to the present invention includes a novolak type phenol resin for substituting a part of the hydroxyl group with an ether group, in a solvent, with a base as a catalyst, together with an alkylating agent, thereby eliminating the alkylating agent. It can be prepared by substituting a group with an alkoxide (phenoxide).
[0047]
The substitution reaction of the phenoxide of the novolak type phenol resin for substituting a part of the hydroxyl group with the ether group and the leaving group of the alkylating agent can be carried out as follows.
That is, the total weight of the novolak-type phenol resin for substituting a part of the hydroxyl group with an ether group is dissolved in a solvent so as to have a concentration of 20 to 80% by weight (preferably 30 to 70% by weight). The molar ratio of the alkylating agent to the molar ratio of the alkylating agent is further added to the total molar number of hydroxyl groups of the type phenol resin so that the molar ratio of the alkylating agent is desired to be replaced with an ether group. It is carried out by adding it under a temperature condition in the range of 40 ° C. to 200 ° C. so as to be 0.5 to 5.0 (preferably 1.0 to 2.5) and stirring for several hours while maintaining the temperature range. be able to. In addition, it is preferable that reaction temperature is the range of 50 to 150 degreeC, and it is more preferable that it is the range of 60 to 100 degreeC.
[0048]
Examples of the alkylating agent used in the reaction include alkyl halides, sulfuric acid esters, aromatic sulfonic acid esters, oxalic acid esters, carboxylic acid esters, phosphoric acid esters, orthoesters, dimethylformamide acetals, trifluoromethanesulfonic acid esters, Examples include alkylammonium salts, alkyldiazonium, alkyloxodium salts, alkylsulfonium salts, alkyliodonium salts, fluorosulfuric acid esters, and trifluoromethanesulfonic acid esters. Among these, it is particularly preferable to use an alkyl halide. Of the alkyl halides, alkyl iodide is more preferably used.
[0049]
Examples of the solvent used in the reaction include acetone, toluene, benzene, DMSO, DMF, DME, THF, and the like, and it is preferable to use acetone as the solvent.
[0050]
Examples of the base catalyst include sodium amide, potassium carbonate, triethylamine, sodium hydroxide, barium oxide, silver oxide, sodium hydride, potassium iodide, pyridine, copper (I) iodide, potassium hydroxide, and the like. Preference is given to using potassium carbonate as the base catalyst.
[0051]
Specific examples [(S-1) to (S-19)] of specific phenol resins suitably used in the present invention are shown below. The specific phenol resin according to the present invention is not limited to these.
[0052]
(S-1) A novolak in which the hydroxyl group of a polycondensation product of phenol and m-cresol (molar ratio 60:40, weight average molecular weight 12000) is substituted with 10 mol% pentyl group with respect to the total number of moles of hydroxyl group. resin.
(S-2) The hydroxyl group of a polycondensation product of phenol, m-cresol and p-cresol (molar ratio 20:70:10, weight average molecular weight 4600) is 5 mol% with respect to the total number of moles of hydroxyl groups. A novolak resin substituted with a nonyl group.
(S-3) A novolak in which the hydroxyl group of a polycondensation product of phenol and p-cresol (molar ratio 40:60, weight average molecular weight 3200) is substituted with 15 mol% isopentyl group with respect to the total number of moles of hydroxyl group resin.
(S-4) The hydroxyl group of the polycondensation product of m-cresol and p-cresol (molar ratio 50:50, weight average molecular weight 4900) is substituted with 1 mol% cyclohexyl group with respect to the total number of moles of hydroxyl groups. Novolac resin.
[0053]
(S-6) The hydroxyl group of the polycondensation product of phenol and p-ethylphenol (molar ratio 60:40, weight average molecular weight 4900) is 0.5 mol% 2-norbornyl with respect to the total number of moles of hydroxyl groups. Novolac resin substituted on the group.
(S-7) The hydroxyl group of the polycondensation product of phenol and p-tertiary butylphenol (molar ratio 70:30, weight average molecular weight 3100) is substituted with 55 mol% methyl group based on the total number of moles of hydroxyl group. Novolac resin
(S-8) A hydroxyl group of a polycondensation product of phenol and 2,5-xylenol (molar ratio 60:40, weight average molecular weight 3500) is substituted with 3 mol% isobutyl group based on the total number of moles of hydroxyl groups. Novolac resin.
(S-10) The hydroxyl group of the polycondensation product of phenol and 2,4-xylenol (molar ratio 60:40, weight average molecular weight 5500) is replaced with 55 mol% butyl group based on the total number of moles of hydroxyl group. Novolac resin.
[0054]
(S-11) 12 mol% 2-ethylhexyl group based on the total number of moles of the hydroxyl group of the condensation polymer of phenol and 3,4-xylenol (molar ratio 55:45, weight average molecular weight 6800) Novolak resin replaced with.
(S-12) The hydroxyl group of the polycondensation product of phenol and p-nonylphenol (molar ratio 80:20, weight average molecular weight 8800) is replaced with 15 mol% 1-methylbutyl group with respect to the total number of moles of hydroxyl groups. Novolac resin.
(S-13) A novolak in which the hydroxyl group of a polycondensation product of phenol and p-nonylphenol (molar ratio 80:20, weight average molecular weight 8800) is substituted with 5 mol% cyclopentyl group with respect to the total number of moles of hydroxyl group resin
[0056]
  Among these, (S-1) to(S-4), (S-6) to(S-8) is preferable, and (S-1) to (S-3) are more preferable.
[0057]
In the lithographic printing plate precursor according to the present invention, a water-insoluble and alkaline water-soluble resin (hereinafter, appropriately referred to as “other alkali-soluble”) other than the specific phenol resin such as the resin (A-1) or the resin (A-2). May be used in combination.
[0058]
Examples of other alkali-soluble resins include polyhydroxystyrene, polyhalogenated hydroxystyrene, N- (4-hydroxyphenyl) methacrylamide copolymer, hydroquinone monomethacrylate copolymer, and JP-A-7-28244. Examples thereof include sulfonylimide-based polymers described in the publication, and carboxyl group-containing polymers described in JP-A-7-36184. In addition, an acrylic resin containing a phenolic hydroxyl group as disclosed in JP-A-51-34711, an acrylic resin having a sulfonamide group described in JP-A-2-866, and a urethane-based resin Various alkali-soluble polymer compounds can also be used.
[0059]
Other alkali-soluble resins preferably have a weight average molecular weight of 500 to 200,000 and a number average molecular weight of 200 to 60,000.
Other alkali-soluble resins may be used singly or in combination of two or more. The addition amount that can be used in combination is preferably 0.5 to 30% by weight, more preferably 0.5 to 20% by weight, based on the total solid content of the image recording layer.
[0060]
Moreover, as content ratio of specific phenol resin and other alkali-soluble resin, 1: 1 to 100: 1 are preferable and 5: 1 to 25: 1 are more preferable.
[0061]
[(B) Photothermal conversion agent]
The image recording layer according to the lithographic printing plate precursor according to the invention needs to contain (B) a photothermal conversion agent.
The (B) photothermal conversion agent according to the present invention can be used without any limitation in the absorption wavelength region as long as it is a substance that absorbs light energy irradiation rays and generates heat. From the viewpoint of compatibility with a high-power laser that is easily available, an infrared-absorbing dye or pigment having an absorption maximum at a wavelength of 760 nm to 1200 nm is preferable.
[0062]
As the infrared absorbing dye, a commercially available dye, for example, a known dye described in documents such as “Dye Handbook” (edited by the Society for Synthetic Organic Chemistry, published in 1970) can be used. Specifically, azo dyes, metal complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes, squarylium dyes, pyrylium salts, metal thiolate complexes, oxonol dyes And dyes such as diimonium dyes, aminium dyes, and croconium dyes.
[0063]
Preferred infrared absorbing dyes are described in, for example, JP-A-58-125246, JP-A-59-84356, JP-A-59-202829, JP-A-60-78787, and the like. Cyanine dyes: methine dyes described in JP-A-58-173696, JP-A-58-181690, JP-A-58-194595, etc .; JP-A-58-112793, JP-A Naphthoquinone dyes described in JP-A-58-224793, JP-A-59-48187, JP-A-59-73996, JP-A-60-52940, JP-A-60-63744, etc. A squarylium dye described in JP-A-58-112792, a cyanine dye described in British Patent 434,875, and the like It is possible.
[0064]
Further, near infrared absorption sensitizers described in US Pat. No. 5,156,938 are also preferably used, and substituted aryl benzoates described in US Pat. No. 3,881,924 are also preferably used. (Thio) pyrylium salt; trimethine thiapyrylium salt described in JP-A-57-142645 (US Pat. No. 4,327,169); JP-A-58-181051 and JP-A-58-220143 No. 59-41363, 59-84248, 59-84249, 59-146063, 59-146061, and pyrylium compounds described in JP-A-59-216146. Cyanine dyes described in US Pat. No. 4,283,475, pentamethine thiopyrylium salts described in US Pat. No. 4,283,475, etc .; Pyrylium compounds disclosed in JP same 5-19702 are also preferably used.
[0065]
Another example of a preferable dye is a near-infrared absorbing dye described as formulas (I) and (II) in US Pat. No. 4,756,993.
[0066]
Particularly preferred among these dyes are cyanine dyes, phthalocyanine dyes, oxonol dyes, squarylium dyes, pyrylium salts, thiopyrylium dyes, and nickel thiolate complexes. Further, the dyes represented by the following general formulas (a) to (e) are preferable because of their excellent photothermal conversion efficiency. Particularly, the cyanine dye represented by the following general formula (a) is used in the image recording layer according to the present invention. In this case, it is most preferable because it gives a high interaction with the alkali-soluble resin and is excellent in stability and economy.
[0067]
[Chemical Formula 3]
[0068]
In general formula (a), X¹Is a hydrogen atom, a halogen atom, -NPh₂, X²-L¹Or the group shown below is represented. Where X²Represents an oxygen atom or a sulfur atom, and L¹Represents a C 1-12 hydrocarbon group, an aromatic ring having a hetero atom, and a C 1-12 hydrocarbon group containing a hetero atom. In addition, a hetero atom shows a nitrogen atom, a sulfur atom, an oxygen atom, a halogen atom, and a selenium atom here.
[0069]
[Formula 4]
[0070]
In the above formula, Xa^-Is Za which will be described later^-Is defined in the same way as R^aRepresents a substituent selected from a hydrogen atom, an alkyl group, an aryl group, a substituted or unsubstituted amino group, and a halogen atom.
[0071]
In general formula (a), R¹And R²Each independently represents a hydrocarbon group having 1 to 12 carbon atoms. From the storage stability of the recording layer coating solution, R¹And R²Is preferably a hydrocarbon group having 2 or more carbon atoms, and further R¹And R²Are particularly preferably bonded to each other to form a 5-membered ring or a 6-membered ring.
[0072]
Ar¹, Ar²These may be the same or different and each represents an aromatic hydrocarbon group which may have a substituent. Preferred aromatic hydrocarbon groups include a benzene ring and a naphthalene ring. Moreover, as a preferable substituent, a C12 or less hydrocarbon group, a halogen atom, and a C12 or less alkoxy group are mentioned.
Y¹, Y²May be the same or different and each represents a sulfur atom or a dialkylmethylene group having 12 or less carbon atoms.
R^Three, R^FourThese may be the same or different and each represents a hydrocarbon group having 20 or less carbon atoms which may have a substituent. Preferable substituents include an alkoxy group having 12 or less carbon atoms, a carboxyl group, and a sulfo group.
R^Five, R⁶, R⁷And R⁸May be the same or different and each represents a hydrogen atom or a hydrocarbon group having 12 or less carbon atoms. From the availability of raw materials, a hydrogen atom is preferred.
Za^-Represents a counter anion. However, when the cyanine dye represented by the general formula (a) has an anionic substituent in its structure and charge neutralization is not necessary, Za^-Is not necessary. Preferred Za^-Is a halogen ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, and a sulfonate ion, particularly preferably a perchlorate ion, a hexafluorophosphate, from the storage stability of the recording layer coating solution. Ions and aryl sulfonate ions.
[0073]
Specific examples of the cyanine dye represented by the general formula (a) that can be suitably used in the present invention include those exemplified below, and paragraph numbers [0017] to [0019] of JP-A No. 2001-133969, Examples thereof include those described in paragraph numbers [0012] to [0038] of JP-A No. 2002-40638 and paragraph numbers [0012] to [0023] of JP-A No. 2002-23360.
[0074]
[Chemical formula 5]
[0075]
[Chemical 6]
[0076]
[Chemical 7]
[0077]
[Chemical 8]
[0078]
In general formula (b), L represents a methine chain having 7 or more conjugated carbon atoms, the methine chain may have a substituent, and the substituents may be bonded to each other to form a ring structure. .
Zb⁺Indicates a counter cation. Preferred counter cations include ammonium, iodonium, sulfonium, phosphonium, pyridinium, alkali metal cations (Ni⁺, K⁺, Li⁺) And the like.
R⁹To R¹⁴And R¹⁵To R²⁰Are independently selected from a hydrogen atom or a halogen atom, a cyano group, an alkyl group, an aryl group, an alkenyl group, an alkynyl group, a carbonyl group, a thio group, a sulfonyl group, a sulfinyl group, an oxy group, or an amino group. Represents a group or a combination of two or three of these, and may be bonded to each other to form a ring structure.
Here, in the general formula (b), L represents a methine chain having 7 conjugated carbon atoms, and R⁹To R¹⁴And R¹⁵To R²⁰In which all represent hydrogen atoms are preferred from the viewpoint of availability and effects.
[0079]
Specific examples of the dye represented by formula (b) that can be suitably used in the present invention include those exemplified below.
[0080]
[Chemical 9]
[0081]
[Chemical Formula 10]
[0082]
In general formula (c), Y^ThreeAnd Y^FourEach independently represents an oxygen atom, a sulfur atom, a selenium atom, or a tellurium atom. M represents a methine chain having 5 or more conjugated carbon atoms.
R^{twenty one}To R^{twenty four}And R^{twenty five}To R²⁸Each may be the same or different, and may be a hydrogen atom, halogen atom, cyano group, alkyl group, aryl group, alkenyl group, alkynyl group, carbonyl group, thio group, sulfonyl group, sulfinyl group, oxy group, Or represents an amino group.
In the formula, Za^-Represents a counter anion, and Za in the general formula (a)^-It is synonymous with.
[0083]
In the present invention, specific examples of the dye represented by formula (c) that can be suitably used include those exemplified below.
[0084]
Embedded image
[0085]
Embedded image
[0086]
In general formula (d), R²⁹To R³¹Each independently represents a hydrogen atom, an alkyl group, or an aryl group. R³³And R³⁴Each independently represents an alkyl group, a substituted oxy group, or a halogen atom.
n and m each independently represents an integer of 0 to 4.
R²⁹And R³⁰Or R³¹And R³²May be bonded to each other to form a ring. R²⁹And / or R³⁰Is R³³And R³¹And / or R³²Is R³⁴To form a ring. In addition, R³³Or R³⁴If there is more than one, R³³Each other or R³⁴They may be bonded to each other to form a ring.
X²And X^ThreeEach independently represents a hydrogen atom, an alkyl group, or an aryl group, and X²And X^ThreeAt least one of represents a hydrogen atom or an alkyl group.
Q is a trimethine group or a pentamethine group which may have a substituent, and may form a ring structure together with a divalent organic group.
Zc^-Represents a counter anion, and Za in the general formula (a)^-It is synonymous with.
[0087]
In the present invention, specific examples of the dye represented by the general formula (d) that can be suitably used include those exemplified below.
[0088]
Embedded image
[0089]
Embedded image
[0090]
In general formula (e), R³⁵To R⁵⁰Each independently represents a hydrogen atom, halogen atom, cyano group, alkyl group, aryl group, alkenyl group, alkynyl group, hydroxyl group, carbonyl group, thio group, sulfonyl group, sulfinyl group, oxy group which may have a substituent. A group, an amino group, or an onium salt structure is shown.
M represents two hydrogen atoms or metal atoms, a halometal group, and an oxymetal group, and the metal atoms contained therein include IA, IIA, IIIB, IVB group atoms of the periodic table, first, second, third Examples include periodic transition metals and lanthanoid elements. Among these, copper, magnesium, iron, zinc, cobalt, aluminum, titanium, and vanadium are preferable.
[0091]
In the present invention, specific examples of the dye represented by formula (e) that can be suitably used include those exemplified below.
[0092]
Embedded image
[0093]
Examples of the pigment used as the photothermal conversion agent in the present invention include commercially available pigments and Color Index (CI) manual, “Latest Pigment Handbook” (edited by Japan Pigment Technical Association, published in 1977), “Latest Pigment Applied Technology”. (CMC Publishing, published in 1986) and “Printing Ink Technology”, published by CMC Publishing, published in 1984).
[0094]
Examples of the pigment include black pigments, yellow pigments, orange pigments, brown pigments, red pigments, purple pigments, blue pigments, green pigments, fluorescent pigments, metal powder pigments, and other polymer-bonded dyes. Specifically, insoluble azo pigments, azo lake pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, anthraquinone pigments, perylene and perinone pigments, thioindigo pigments, quinacridone pigments, dioxazine pigments, isoindolinone pigments In addition, quinophthalone pigments, dyed lake pigments, azine pigments, nitroso pigments, nitro pigments, natural pigments, fluorescent pigments, inorganic pigments, carbon black, and the like can be used. Among these pigments, carbon black is preferable.
[0095]
These pigments may be used without surface treatment, or may be used after surface treatment. The surface treatment method includes a method of surface coating with a resin or wax, a method of attaching a surfactant, a method of bonding a reactive substance (eg, silane coupling agent, epoxy compound, polyisocyanate, etc.) to the pigment surface, etc. Is mentioned. The above-mentioned surface treatment methods are described in “Characteristics and Applications of Metal Soap” (Yokoshobo), “Printing Ink Technology” (CMC Publishing, 1984) and “Latest Pigment Application Technology” (CMC Publishing, 1986). Yes.
[0096]
The particle diameter of the pigment is preferably in the range of 0.01 μm to 10 μm, preferably from 0.05 μm to 1 μm, from the viewpoints of dispersion stability of the pigment in the image recording layer coating solution and uniformity of the image recording layer. More preferably, it is in the range of 0.1 μm to 1 μm.
[0097]
As a method for dispersing the pigment, a known dispersion technique used in ink production, toner production, or the like can be used. Examples of the disperser include an ultrasonic disperser, a sand mill, an attritor, a pearl mill, a super mill, a ball mill, an impeller, a disperser, a KD mill, a colloid mill, a dynatron, a three-roll mill, and a pressure kneader. Details are described in "Latest Pigment Applied Technology" (CMC Publishing, 1986).
[0098]
These pigments or dyes are 0.01 to 50% by weight, preferably 0.1 to 10% by weight, particularly preferably 0 to 10% by weight, based on the total solid content, from the viewpoint of sensitivity and uniformity of the image recording layer. In the case of a pigment, it can be added at a ratio of 3.1 to 10% by weight.
These dyes or pigments may be added to the same layer as other components, or another layer may be provided and added thereto.
[0099]
Next, other components that can be added in preparing the photosensitive composition for the image recording layer in the production of the lithographic printing plate precursor according to the invention will be described.
[0100]
In the photosensitive composition, cyclic acid anhydrides, phenols, and organic acids for enhancing sensitivity can be added as necessary. Moreover, a printing-out agent for obtaining a visible image immediately after exposure, a dye as an image coloring agent, other fillers, and the like can be added.
[0101]
Examples of cyclic acid anhydrides include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, and 3,6-endooxy-Δ4-tetrahydrophthalic anhydride described in US Pat. No. 4,115,128. Tetrachlorophthalic anhydride, maleic anhydride, chloromaleic anhydride, α-phenylmaleic anhydride, succinic anhydride, pyromellitic anhydride and the like can be used.
[0102]
As phenols, bisphenol A, p-nitrophenol, p-ethoxyphenol, 2,4,4'-trihydroxybenzophenone, 2,3,4-trihydroxybenzophenone, 4-hydroxybenzophenone, 4,4 ', 4 "-Trihydroxytriphenylmethane, 4,4 ', 3", 4 "-tetrahydroxy-3,5,3', 5'-tetramethyltriphenylmethane and the like.
[0103]
Examples of organic acids include sulfonic acids, sulfinic acids, alkyl sulfates, phosphonic acids, phosphoric esters, carboxylic acids and the like described in JP-A-60-88942 and JP-A-2-96755. is there. Specifically, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, p-toluenesulfinic acid, ethyl sulfate, phenylphosphonic acid, phenylphosphinic acid, phenyl phosphate, diphenyl phosphate, benzoic acid, isophthalic acid, adipic acid, Examples include p-toluic acid, 3,4-dimethoxybenzoic acid, phthalic acid, terephthalic acid, 4-cyclohexene-1,2-dicarboxylic acid, erucic acid, lauric acid, n-undecanoic acid, ascorbic acid and the like.
The proportion of the cyclic acid anhydrides, phenols, and organic acids in the photosensitive composition is preferably 0.05 to 15% by weight, and more preferably 0.1 to 5% by weight.
[0104]
Examples of the print-out agent for obtaining a visible image immediately after exposure include a combination of a photosensitive compound that releases an acid upon exposure and an organic dye that forms a salt with the acid to change the color tone.
[0105]
Examples of the photosensitive compound that releases an acid upon exposure include o-naphthoquinone diazide-4-sulfonic acid halogenide described in JP-A-50-36,209; JP-A-53-36223. Trihalomethyl-2-bilone and trihalomethyl-s-triazine; various o-naphthoquinonediazide compounds described in JP-A-55-62444; described in JP-A-55-77742 And 2-trihalomethyl-5-aryl-1,3,4-oxadiazole compounds; diazonium salts and the like.
These compounds can be used alone or in combination. The addition amount is preferably in the range of 0.3 to 15% by weight with respect to the total weight of the photosensitive composition.
[0106]
In the composition for image recording layer (photosensitive composition) used in the lithographic printing plate precursor according to the present invention, the color tone of the composition by interacting with the photodecomposition product of a compound that generates an acidic substance upon photolysis. At least one kind of organic dye is used.
As such organic dyes, diphenylmethane, triarylmethane, thiazine, oxazine, phenazine, xanthene, anthraquinone, iminonaphthoquinone, and azomethine dyes can be used. Specifically, it is as follows.
[0107]
Brilliant green, eosin, ethyl violet, erythrosine B, methyl green, crystal violet, basic fuchsin, phenolphthalein, 1,3-diphenyltriazine, alizarin red S, thymolphthalein, methyl violet 2B, quinaldine red, rose bengal, Thymolsulfophthalein, xylenol blue, methyl orange, orange IV, diphenylthiocarbazone, 2,7-dichlorofluorescein, paramethyl red, congo red, benzopurpurin 4B, α-naphthyl red, Nile blue 2B, Nile blue A , Phenacetalin, methyl violet, malachite green, parafuchsin, oil blue # 603 [manufactured by Orient Chemical Co., Ltd.], oil pink # 312 [ Oil Red 5B [Orient Chemical Industries, Ltd.], Oil Scarlet # 308 [Orient Chemical Industries, Ltd.], Oil Red OG [Orient Chemical Industries, Ltd.], Oil Red RR [manufactured by Orient Chemical Co., Ltd.], Oil Green # 502 [manufactured by Orient Chemical Co., Ltd.], Spiron Red BEH Special [manufactured by Hodogaya Chemical Co., Ltd.], Victoria Pure Blue BOH [Hodogaya Chemical Industry ( Manufactured by)
[0108]
Patent Pure-Blue (manufactured by Sumitomo Sangoku Chemical Co., Ltd.), Sudan Blue II (manufactured by BASF), m-cresol purple, cresol red, rhodamine B, rhodamine 6G, first acid violet R, sulforhodamine B, auramine, 4-p-diethylaminophenyliminonaphthoquinone, 2-carboxyanilino-4-p-diethylaminophenyliminonaphthoquinone, 2-carbostearylamino-4-p-dihydroxyoxyethyl-amino-phenyliminonaphthoquinone, p-methoxybenzoyl-p '-Diethylamino-o'-methylphenyliminoacetanilide, cyano-p-diethylaminophenyliminoacetanilide, 1-phenyl-3-methyl-4-p-diethylaminophenylimino-5-pyrazolone 1-beta-naphthyl -4-p-diethylamino-phenyl imino-5-pyrazolone and the like, can be mentioned.
[0109]
Particularly preferred organic dyes are triarylmethane dyes. As triarylmethane dyes, those having a sulfonic acid compound as a counter anion as disclosed in JP-A-62-2932471 and JP-A-296921 are particularly useful.
These dyes can be used alone or in combination. The addition amount is preferably 0.3 to 15% by weight based on the total weight of the image recording layer composition.
Moreover, it can use together with another dye and a pigment as needed. The amount used is 70% by weight or less, more preferably 50% by weight or less, based on the total weight of the dye and the pigment.
[0110]
In addition, various additives can be added to the image recording layer composition according to various purposes. Specifically, it is as follows. Various resins having a hydrophobic group for improving the ink inking property of an image, such as octylphenol / formaldehyde resin, t-butylphenol / formaldehyde resin, t-butylphenol / benzaldehyde resin, rosin-modified novolak resin, and o of these modified novolak resins -Naphthoquinone diazide sulfonate ester etc .; Plasticizers for improving the flexibility of the coating film, such as dibutyl phthalate, dioctyl phthalate, butyl glycolate, tricresyl phosphate, dioctyl adipate, etc.
The addition amount of these various additives is preferably in the range of 0.01 to 30% by weight based on the total weight of the image recording layer composition.
[0111]
Furthermore, a known resin for further improving the abrasion resistance of the film can be added to the image recording layer composition. Examples of these resins include polyvinyl acetal resin, polyurethane resin, epoxy resin, vinyl chloride resin, nylon, polyester resin, and acrylic resin. These can be used alone or in combination. The addition amount is preferably in the range of 2 to 40% by weight with respect to the total weight of the composition.
[0112]
Further, in the composition for an image recording layer, a nonionic surfactant as described in JP-A Nos. 62-251740 and 4-68355 is used in order to widen the development latitude. , Amphoteric surfactants as described in JP-A-59-121044 and JP-A-4-13149 can be added.
Specific examples of the nonionic surfactant include sorbitan tristearate, sorbitan monopalmitate, sorbitan trioleate, stearic acid monoglyceride, polyoxyethylene sorbitan monooleate, polyoxyethylene nonylphenyl ether and the like. Specific examples of the amphoteric surfactant include alkyldi (aminoethyl) glycine, alkylpolyaminoethylglycine hydrochloride, Amorgen K (trade name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., N-tetradecyl-N, N-betaine type) 2-alkyl-N-carboxyethyl-N-hydroxyethyl imidazolinium betaine, Levon 15 (trade name, Sanyo Kasei Co., Ltd., alkyl imidazoline series) and the like.
The proportion of the nonionic surfactant and amphoteric surfactant in the image recording layer composition is preferably 0.05 to 15% by weight, and more preferably 0.1 to 5% by weight.
[0113]
In the image recording layer composition, a surfactant for improving the coating surface quality, for example, a fluorosurfactant as described in JP-A No. 62-170950 can be added. . A preferable addition amount is 0.001 to 1.0% by weight of the total composition, and more preferably 0.005 to 0.5% by weight.
[0114]
In the image recording layer composition, a yellow dye, preferably a yellow dye having an absorbance at 417 nm of 70% or more of the absorbance at 436 nm can be added.
[0115]
In obtaining the lithographic printing plate precursor according to the invention, first, an image recording layer is provided by applying a resin composition for an image recording layer on a suitable support.
The image recording layer is formed by dissolving or dispersing the composition for an image recording layer in the following organic solvent, alone or in a mixture, coating the support, and drying.
Any known organic solvent can be used. In the present invention, those having a boiling point in the range of 40 ° C. to 200 ° C., particularly 60 ° C. to 160 ° C. are selected because of the advantage in drying.
[0116]
Examples of the organic solvent include alcohols such as methyl alcohol, ethyl alcohol, n- or iso-propyl alcohol, n- or iso-butyl alcohol, diacetone alcohol; acetone, methyl ethyl ketone, methyl propyl ketone, methyl butyl ketone, methyl Ketones such as amyl ketone, methyl hexyl ketone, diethyl ketone, diisobutyl ketone, cyclohexanone, methylcyclohexanone, acetylacetone; hydrocarbons such as benzene, toluene, xylene, cyclohexane, methoxybenzene; ethyl acetate, n- or iso-propyl acetate , N- or iso-butyl acetate, ethyl butyl acetate, hexyl acetate and other acetic acid esters; methylene dichloride, ethylene dichloride, monochloro Halides such as benzene; isopropyl ether, n- butyl ether, dioxane, dimethyl dioxane, tetrahydrofuran and the like;
[0117]
Ethylene glycol, methyl cellosolve, methyl cellosolve acetate, ethyl cellosolve, diethyl cellosolve, cellosolve acetate, butyl cellosolve, butyl cellosolve acetate, methoxymethoxyethanol, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, propylene glycol, propylene glycol monomethyl Polyhydric alcohols such as ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether, propylene glycol monoethyl ether acetate, propylene glycol monobutyl ether, 3-methyl-3-methoxybutanol and derivatives thereof; Methyl sulfoxide, N, N-and special solvents such as dimethylformamide are suitably used singly or as a mixture. The solid content in the composition to be applied is suitably 2 to 50% by weight.
[0118]
In the planographic printing plate precursor of the present invention, the image recording layer composition may be applied by, for example, roll coating, dip coating, air knife coating, gravure coating, gravure offset coating, hopper coating, blade coating, wire doctor coating, spraying. A method such as coating is used.
The weight of the image recording layer after drying is 0.3 to 4.0 g / m.²Is preferred. As the coating amount decreases, the exposure amount for obtaining an image can be reduced, but the film strength decreases. As the coating amount increases, the exposure amount is required but the photosensitive film becomes stronger, and a printing plate having a high printable number (high printing durability) can be obtained.
[0119]
The image recording layer composition coated on the support is usually dried by heated air. As a drying temperature, the range of 30 degreeC-200 degreeC, especially 40 degreeC-140 degreeC is suitable. In addition to a method in which the drying temperature is kept constant during drying, a method in which the drying temperature is increased stepwise can be implemented. Also, good results may be obtained by dehumidifying the dry air. The heated air is preferably supplied at a rate of 0.1 m / second to 30 m / second, particularly 0.5 m / second to 20 m / second, with respect to the coated surface.
[0120]
A mat layer is preferably provided on the surface of the image recording layer provided as described above in order to reduce the time for evacuation and prevent blurring during close contact exposure using a vacuum baking frame. . Specifically, a method for providing a mat layer as described in JP-A-50-125805, JP-B-57-6582, and JP-A-61-2986, and JP-B-62-62337. And a method of heat-sealing the solid powder as described above.
[0121]
[Support]
The support used in the lithographic printing plate precursor according to the invention may be a dimensionally stable plate-like material, and those conventionally used as a support for printing plates can be suitably used. .
Such supports include paper, paper laminated with plastics (eg, polyethylene, polypropylene, polystyrene, etc.), metal plates such as aluminum (including aluminum alloys), zinc, iron, copper, etc., cellulose diacetate , Cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose butyrate acetate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc. Paper or plastic film is included. In the present invention, an aluminum plate is particularly preferable. The aluminum plate includes a pure aluminum plate and an aluminum alloy plate. Various aluminum alloys can be used. For example, an alloy of metal such as silicon, copper, manganese, magnesium, chromium, zinc, lead, bismuth, nickel, and aluminum is used. These compositions contain some iron and titanium plus other negligible amounts of impurities.
[0122]
The support is surface-treated as necessary. When the surface treatment is performed on the support, it is preferable to perform a hydrophilic treatment. In the case of a support having a surface of metal, particularly aluminum, surface treatment such as graining treatment, immersion treatment in an aqueous solution of sodium silicate, potassium fluoride zirconate, phosphate or the like, or anodization treatment may be performed. It is preferable that it is made. Further, as described in U.S. Pat. No. 2,714,066, as a support, an aluminum plate which has been grained and then immersed in an aqueous sodium silicate solution, U.S. Pat. No. 3,181,461. As described in the specification, an aluminum plate that has been anodized and then immersed in an aqueous solution of an alkali metal silicate is also preferably used.
The anodizing treatment may be performed by, for example, using an inorganic acid such as phosphoric acid, chromic acid, sulfuric acid or boric acid, an organic acid such as oxalic acid or sulfamic acid, or an aqueous solution of these salts, or a non-aqueous solution alone or in combination. This is carried out by passing an electric current in the combined electrolyte using an aluminum plate as an anode.
[0123]
In addition, silicate electrodeposition as described in US Pat. No. 3,658,662 is also effective as a hydrophilic treatment. These hydrophilic treatments are performed to make the surface of the support hydrophilic, in order to prevent harmful reactions with the photosensitive composition provided thereon, and to adhere to the image recording layer. It is given in order to improve. Prior to graining the aluminum plate, the surface may be pretreated as necessary to remove the rolling oil on the surface and expose a clean aluminum surface.
For the former, a solvent such as trichlene, a surfactant or the like is used. For the latter, a method using an alkali / etching agent such as sodium hydroxide or potassium hydroxide is widely used.
[0124]
As the graining method, any of a mechanical method, a chemical method, and an electrochemical method is effective. Examples of the mechanical method include a ball polishing method, a blast polishing method, and a brush polishing method in which an aqueous dispersion slurry of an abrasive such as pumice is rubbed with a nylon brush. As a chemical method, a method of immersing in a saturated aqueous solution of an aluminum salt of a mineral acid as described in JP-A No. 54-31187 is suitable. As the electrochemical method, an AC electrolysis method in an acidic electrolyte such as hydrochloric acid, nitric acid or a combination thereof is preferable. Among such surface roughening methods, in particular, a surface roughening method that combines mechanical surface roughening and electrochemical surface roughening as described in JP-A-55-137993 is a fat-sensitive material. This is preferable because the adhesive strength of the image to the support is strong. Graining by the method as described above is preferably performed in such a range that the center line surface roughness (Ra) of the surface of the aluminum plate is 0.3 to 1.0 μm.
[0125]
The grained aluminum plate is washed with water and chemically etched as necessary.
The etching treatment liquid is usually selected from an aqueous solution of a base or acid that dissolves aluminum. In this case, a film different from aluminum derived from the etching solution component should not be formed on the etched support surface. Examples of preferable etching agents include sodium hydroxide, potassium hydroxide, trisodium phosphate, disodium phosphate, tripotassium phosphate, dipotassium phosphate and the like as basic substances; Examples include sulfuric acid, phosphoric acid, hydrochloric acid, and salts thereof, but salts of metals that have a lower ionization tendency than aluminum (such as zinc, chromium, cobalt, nickel, copper, etc.) form unnecessary films on the etched surface. It is not preferable. These etching agents have a dissolution rate of aluminum or an alloy to be used of 0.3 g to 40 g / m / min.²Although it is most preferable to carry out so that it becomes, it may be above or below this.
[0126]
Etching is performed by immersing an aluminum plate in an etchant or applying an etchant to the aluminum plate. For etching, the etching amount is 0.5 to 10 g / m.²It is preferable to process so that it may become this range. As the etching agent, it is desirable to use an aqueous solution of a base because of its high etching rate. In this case, since a smut is generated, a normal desmut process is performed. Examples of the acid used for the desmut treatment include nitric acid, sulfuric acid, phosphoric acid, chromic acid, hydrofluoric acid, and borohydrofluoric acid.
[0127]
The etched aluminum plate is washed with water and anodized as necessary. Anodization can be performed by a method conventionally used in this field. Specifically, when a direct current or an alternating current is passed through aluminum in an aqueous solution or non-aqueous solution in which sulfuric acid, phosphoric acid, chromic acid, oxalic acid, sulfamic acid, benzenesulfonic acid and the like or a combination of two or more thereof are combined, An anodized film can be formed on the surface of the aluminum support. Since the treatment conditions for anodization vary depending on the electrolyte used, they cannot generally be determined, but in general, the concentration of the electrolyte is 1 to 80% by weight, the solution temperature is 5 to 70 ° C., and the current density is 0.8. 5-60 amps / dm²A voltage of 1 to 100 V and an electrolysis time of 30 seconds to 50 minutes are suitable. Among these anodizing treatments, in particular, the method of anodizing at high current density in sulfuric acid described in British Patent 1,412,768, and U.S. Pat. No. 3,511,661. A method of anodizing the described phosphoric acid as an electrolytic bath is preferred.
[0128]
The aluminum plate roughened and further anodized as described above may be hydrophilized as necessary. Preferred examples of the hydrophilization treatment include alkali metal silicates (for example, sodium silicate aqueous solution) such as those disclosed in US Pat. Nos. 2,714,066 and 3,181,461, There is a method of treatment with potassium fluorinated zirconate disclosed in JP-A 36-22063 and polyvinylphosphonic acid as disclosed in US Pat. No. 4,153,461.
[0129]
[Organic subbing layer]
In the lithographic printing plate precursor according to the invention, an organic undercoat layer can be provided between the image recording layer and the support, if necessary.
[0130]
Examples of organic compounds used in the organic undercoat layer include carboxymethylcellulose, dextrin, gum arabic; phosphonic acids having an amino group such as 2-aminoethylphosphonic acid, phenylphosphonic acid optionally having a substituent, and naphthyl. Organic phosphonic acids such as phosphonic acid, alkylphosphonic acid, glycerophosphonic acid, methylenediphosphonic acid and ethylenediphosphonic acid; organic such as phenylphosphoric acid, naphthylphosphoric acid, alkylphosphoric acid and glycerophosphonic acid which may have a substituent Phosphoric acid; organic phosphinic acids such as phenylphosphinic acid, naphthylphosphinic acid, alkylphosphinic acid and glycerophosphinic acid which may have a substituent; amino acids such as glycine and β-alanine; and hydrochloride of triethanolamine With hydroxyl group Amine hydrochloride; -alanine etc., may be used by mixing two or more of these.
The organic undercoat layer preferably contains a compound having an onium group. The compounds having an onium group are described in detail in JP-A Nos. 2000-10292 and 2000-108538.
[0131]
In addition, for the organic undercoat layer, at least one compound selected from the group of polymer compounds having a structural unit represented by poly (p-vinylbenzoic acid) in the molecule can be used. More specifically, a copolymer of p-vinylbenzoic acid and vinylbenzyltriethylammonium salt, a copolymer of p-vinylbenzoic acid and vinylbenzyltrimethylammonium chloride, and the like can be given.
[0132]
This organic undercoat layer can be provided by the following method. That is, (i) a solution in which the above organic compound is dissolved in water or an organic solvent such as methanol, ethanol, methyl ethyl ketone, or a mixed solvent thereof is applied onto an aluminum plate and dried to form an organic undercoat layer. And (ii) water or an organic solvent such as methanol, ethanol, methyl ethyl ketone, or a mixed solvent thereof in which the above organic compound is dissolved, and an aluminum plate is immersed in the organic compound. In this method, the organic undercoat layer is formed by adsorbing and then washing and drying with water or the like.
In the former method, a solution of the organic compound having a concentration of 0.005 to 10% by weight can be applied by various methods. As a coating method, for example, any method such as bar coater coating, spin coating, spray coating, or curtain coating may be used. In the latter method, the concentration of the solution is 0.01 to 20% by weight, preferably 0.05 to 5% by weight, the immersion temperature is 20 to 90 ° C., preferably 25 to 50 ° C., and the immersion time. Is 0.1 second to 20 minutes, preferably 2 seconds to 1 minute.
[0133]
The coating solution for the organic undercoat layer can be used in the pH range of 1 to 12 by adjusting the pH with a basic substance such as ammonia, triethylamine or potassium hydroxide, or an acidic substance such as hydrochloric acid or phosphoric acid.
A yellow dye can also be added to improve the tone reproducibility of the lithographic printing plate precursor. Furthermore, the compound shown by the following general formula (f) can also be added to this coating liquid.
[0134]
Formula (f)
(HO)_x-R^Five-(COOH)_y
[0135]
In general formula (f), R^FiveRepresents an arylene group having 14 or less carbon atoms which may have a substituent. x and y each independently represents an integer of 1 to 3.
Specific examples of the compound represented by the general formula (f) include 3-hydroxybenzoic acid, 4-hydroxybenzoic acid, salicylic acid, 1-hydroxy-2-naphthoic acid, 2-hydroxy-1-naphthoic acid, 2 -Hydroxy-3-naphthoic acid, 2,4-dihydroxybenzoic acid, 10-hydroxy-9-anthracenecarboxylic acid and the like.
[0136]
The coating amount after drying of the organic undercoat layer is 1 to 100 mg / m from the viewpoint of printing durability.²Is suitable, preferably 2 to 70 mg / m²It is.
[0137]
[Organic intermediate layer]
In the lithographic printing plate precursor according to the invention, an organic intermediate layer can be provided between the image recording layer and the support, if necessary.
By providing an organic intermediate layer, an infrared-sensitive layer (image recording layer) whose solubility in an alkali developer is improved by exposure is provided on the exposed surface or in the vicinity thereof, and sensitivity to an infrared laser is improved. . In addition, when an organic intermediate layer made of a polymer is provided between the support and the infrared sensitive layer, the organic intermediate layer functions as a heat insulating layer, so that the heat generated by the infrared laser exposure is diffused to the support. Therefore, it has the advantage that it can be used efficiently for image formation and can be highly sensitive.
Further, in the unexposed area, the image recording layer itself that is impermeable to the alkali developer functions as a protective layer for the organic intermediate layer, so that the development stability is improved and the discrimination is excellent. It is considered that an image can be formed and stability over time is secured.
Further, since the organic intermediate layer is configured as a layer containing an alkali-soluble polymer, the organic intermediate layer is a layer having extremely good solubility in a developing solution. Therefore, such an organic intermediate layer is provided adjacent to the support. For example, even when a developer with reduced activity is used, a residual film or the like may be generated when the components of the photosensitive layer whose dissolution inhibiting ability is released by exposure are dissolved and dispersed in the developer. The exposed part is removed quickly. This is considered to contribute to the improvement of developability. For these reasons, the organic intermediate layer is considered useful.
[0138]
This organic intermediate layer is configured to contain a water-insoluble and alkali-soluble resin. As such an alkali-soluble resin, it is necessary for the organic intermediate layer itself to exhibit high alkali-solubility, particularly in the non-image area, and therefore it is necessary to select a resin that does not impair this property. From this viewpoint, other alkali-soluble resins described in the description of the image recording layer are preferable. Among these, from the viewpoints of sensitivity and image formability, it is preferable to select a resin that is less likely to form an interaction than the specific phenol resin used in the image recording layer and has excellent solubility in an alkaline developer. Preferred examples of such a resin include polyamide resin, epoxy resin, acetal resin, acrylic resin, methacrylic resin, styrene resin, urethane resin, and the like.
[0139]
As the alkali-soluble resin used for the organic intermediate layer, it is important to select a resin that is difficult to be dissolved by the coating solvent when the image recording layer is applied. By selecting such a resin, undesired compatibility is suppressed at the interface between the two layers, and further improvement in chemical resistance can be expected. From such a viewpoint, acrylic resin is particularly preferable among the above-described resins.
[0140]
Hereinafter, a water-insoluble and alkali-soluble acrylic resin (hereinafter, appropriately referred to as “acrylic resin”) suitable as an alkali-soluble resin applied to the organic intermediate layer will be described in detail.
The acrylic resin used here is not particularly limited as long as it is insoluble in water and soluble in an alkaline aqueous solution. Such an acrylic resin is particularly suitable for forming a multilayer structure with the image recording layer because of its low compatibility with an alkali-soluble resin having a phenolic hydroxyl group that is preferably used in the image recording layer. The acrylic resin is also excellent in alkali solubility of the resin itself.
[0141]
Acrylic resins include sulfonamide groups (-SO₂NH—R, where R represents a hydrocarbon group which may have a substituent. ), An active imide group [-SO₂NHCOR, -SO₂NHSO₂R, -CONHSO₂R, where R represents a hydrocarbon group which may have a substituent. ], Carboxylic acid group (-CO₂H), a sulfonic acid group (—SO_ThreeH), phosphate group (-OPO_ThreeH₂Acrylic acid esters and methacrylic acid esters having an aliphatic hydroxyl group, which have an alkali-soluble group such as) and are suitable as a copolymer component of an alkali-soluble resin; alkyl acrylates; alkyl methacrylates; acrylamide or methacrylamide A resin containing inactive imides such as alkylmaleimide and arylmaleimide, and nitriles such as acrylonitrile and methacrylonitrile; Also, acrylic resins having a sulfonamide group described in JP-A-2-866 can be suitably applied to the present invention.
[0142]
As the molecular weight of the acrylic resin, those having a weight average molecular weight of 2,000 or more and a number average molecular weight of 500 or more are preferable. More preferably, the weight average molecular weight is 5,000 to 300,000, the number average molecular weight is 800 to 250,000, and the dispersity (weight average molecular weight / number average molecular weight) is 1.1 to 10. .
[0143]
The content of the alkali-soluble resin in the organic intermediate layer component according to the present invention is about 40 to 95% by weight, preferably about 50 to 90% by weight, based on the total solid content in the organic intermediate layer.
Also. In addition to the alkali-soluble resin, the organic intermediate layer can be used in combination with a photothermal conversion agent and various additives as used in the image recording layer.
[0144]
<Back coat>
A back coat is provided on the back surface of the support as necessary. Such a back coat comprises an organic polymer compound described in JP-A-5-45885 and a metal oxide obtained by hydrolysis and polycondensation of an organic or inorganic metal compound described in JP-A-6-35174. A coating layer is preferably used. Of these coating layers, Si (OCH_Three)_Four, Si (OC₂H_Five)_Four, Si (OC_ThreeH₇)_Four, Si (OC_FourH₉)_FourA silicon alkoxy compound such as the above is inexpensive and readily available, and a metal oxide coating layer obtained therefrom is particularly preferable because of its excellent developer resistance.
[0145]
The produced lithographic printing plate precursor is usually subjected to image exposure and development. As an actinic ray light source used for image exposure, a light source having an emission wavelength in the near infrared to infrared region is preferable, and a solid laser or a semiconductor laser is particularly preferable.
[0146]
The developer that can be applied to the development processing of the lithographic printing plate precursor according to the invention is a developer having a pH in the range of 9.0 to 14.0, preferably in the range of 12.0 to 13.5. A conventionally known alkaline aqueous solution can be used as the developer (hereinafter referred to as developer including the replenisher). For example, sodium silicate, potassium, tribasic sodium phosphate, potassium, ammonium, dibasic sodium phosphate, potassium, ammonium, sodium carbonate, potassium, ammonium, sodium bicarbonate, potassium, Examples include inorganic alkali salts such as ammonium, sodium borate, potassium, ammonium, sodium hydroxide, ammonium, potassium, and lithium. Moreover, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, Organic alkali agents such as ethyleneimine, ethylenediamine, and pyridine are listed. These alkaline aqueous solutions may be used individually by 1 type, and may use 2 or more types together.
[0147]
Among the above alkaline aqueous solutions, one of the developing solutions that exert the effect according to the present invention is a so-called one containing an alkali silicate as a base or containing an alkali silicate by mixing a silicon compound with a base. An aqueous solution having a pH of 12 or more called “silicate developer”, and another more preferable developer does not contain an alkali silicate but contains a non-reducing sugar (an organic compound having a buffering action) and a base. Non-silicate developer ".
[0148]
In the former developer, the aqueous solution of alkali metal silicate is silicon oxide SiO which is a component of silicate.₂And alkali metal oxide M₂O ratio (generally [SiO₂] / [M₂The development property can be adjusted by adjusting the concentration and the concentration of O], for example, as disclosed in JP-A-54-62004.₂/ Na₂The molar ratio of O is 1.0 to 1.5 (ie [SiO₂] / [Na₂O] is 1.0 to 1.5), and SiO₂An aqueous solution of sodium silicate having a content of 1 to 4% by weight, and as described in JP-B-57-7427, [SiO 2₂] / [M] is 0.5 to 0.75 (ie, [SiO₂] / [M₂O] is 1.0 to 1.5), and SiO₂An aqueous alkali metal silicate solution having a concentration of 1 to 4% by weight and wherein the developer contains at least 20% potassium, based on gram atoms of all alkali metals present therein. Preferably used.
[0149]
A so-called “non-silicate developer” which does not contain an alkali silicate and contains a non-reducing sugar and a base is also preferable for application to the development of the lithographic printing plate material of the present invention. When the development processing of the lithographic printing plate material is performed using this developer, the surface of the image recording layer is not deteriorated and the inking property of the image recording layer can be maintained in a better state.
[0150]
Such a developer preferably comprises at least one compound selected from non-reducing sugars and at least one base, and the pH of the solution is in the range of 9.0 to 13.5. Such non-reducing sugars are saccharides that do not have a free aldehyde group or ketone group and do not exhibit reducing properties, and are trehalose-type oligosaccharides in which reducing groups are bonded to each other, and glycosides in which a reducing group of saccharides and non-saccharides are bonded. It is classified into sugar alcohols reduced by hydrogenating the body and saccharides, and any of them is preferably used. Trehalose type oligosaccharides include saccharose and trehalose. Examples of glycosides include alkyl glycosides, phenol glycosides, mustard oil glycosides, and the like. Examples of the sugar alcohol include D, L-arabit, rebit, xylit, D, L-sorbit, D, L-mannit, D, L-exit, D, L-talit, zulsiit and allozulcit. Furthermore, maltitol obtained by hydrogenation of a disaccharide and a reduced form (reduced water candy) obtained by hydrogenation of an oligosaccharide are preferably used.
Among these, sugar alcohol and saccharose are particularly preferred non-reducing sugars, and D-sorbite, saccharose, and reduced syrup are particularly preferred because they have a buffering action in an appropriate pH region and are inexpensive.
[0151]
These non-reducing sugars can be used alone or in combination of two or more thereof, and the proportion of the non-reducing sugar in the developer is preferably 0.1 to 30% by weight, more preferably 1 to 20% by weight.
Below this range, a sufficient buffering effect cannot be obtained, and when the concentration is above this range, it is difficult to achieve high concentration and there is a problem of increased costs. In addition, when reducing sugar is used in combination with a base, there is a problem that the color changes to brown over time, the pH gradually decreases, and thus developability decreases.
[0152]
A conventionally known alkaline agent can be used as the base to be combined with the non-reducing sugar. For example, sodium hydroxide, potassium hydroxide, lithium hydroxide, trisodium phosphate, tripotassium phosphate, triammonium phosphate, disodium phosphate, dipotassium phosphate, diammonium phosphate, sodium carbonate, potassium carbonate, Examples include inorganic alkali agents such as ammonium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, ammonium hydrogen carbonate, sodium borate, potassium borate, and ammonium borate. Moreover, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, Organic alkali agents such as ethyleneimine, ethylenediamine, and pyridine are also used.
[0153]
These alkali agents are used alone or in combination of two or more. Among these, sodium hydroxide and potassium hydroxide are preferable. The reason is that the pH can be adjusted in a wide pH range by adjusting these amounts relative to the non-reducing sugar. Further, trisodium phosphate, tripotassium phosphate, sodium carbonate, potassium carbonate and the like are preferable because they have a buffering action.
These alkali agents are added so that the pH of the developer is in the range of 9.0 to 13.5, and the addition amount is determined by the desired pH, the type and addition amount of the non-reducing sugar, but is more preferable. The pH range is 10.0 to 13.2.
[0154]
Further, an alkaline buffer composed of a weak acid other than saccharides and a strong base can be used in combination with the developer. As the weak acid used as such a buffer, one having a dissociation constant (pKa) of 10.0 to 13.2 is preferable.
Such a weak acid is selected from those described in IONATION CONSTANTS OF ORGANIC ACIDS IN AQUEOUS SOLUTION published by Pergamon Press. For example, alcohols such as 2,2,3,3-tetrafluoropropanol-1 (PKa 12.74), trifluoroethanol (12.37), trichloroethanol (12.24), pyridine-2-aldehyde ( 12.68), aldehydes such as pyridine-4-aldehyde (12.05), salicylic acid (13.0), 3-hydroxy-2-naphthoic acid (12.84), catechol (12. 6), gallic acid (12.4), sulfosalicylic acid (11.7), 3,4-dihydroxysulfonic acid (12.2), 3,4-dihydroxybenzoic acid (11.94), 1 2,4-trihydroxybenzene (11.82), hydroquinone (11.56), pyrogallol (11.34), o-cresol (10.33) Resorcinol (same 11.27), p-cresol (at 10.27), m-cresol compound having a phenolic hydroxyl group, such as (at 10.09),
[0155]
2-butanone oxime (12.45), acetoxime (12.42), 1,2-cycloheptanedione dioxime (12.3), 2-hydroxybenzaldehyde oxime (12.10), dimethylglyoxime (11.9), ethanediamide dioxime (11.37), oximes such as acetophenone oxime (11.35), adenosine (12.56), inosine (12.5), guanine (same) 12.3), nucleic acid-related substances such as cytosine (12.2), hypoxanthine (12.1), xanthine (11.9), diethylaminomethylphosphonic acid (12.32), 1- Amino-3,3,3-trifluorobenzoic acid (12.29), isopropylidenediphosphonic acid (12.10), 1,1-ethylidene Phosphonic acid (11.54), 1,1-ethylidene diphosphonic acid 1-hydroxy (11.52), benzimidazole (12.86), thiobenzamide (12.8), picoline thioamide (12) .55) and weak acids such as barbituric acid (12.5).
[0156]
Of these weak acids, sulfosalicylic acid and salicylic acid are preferred. As the base to be combined with these weak acids, sodium hydroxide, ammonium, potassium and lithium are preferably used. These alkali agents are used alone or in combination of two or more. The above various alkali agents are used by adjusting the pH within a preferable range by the concentration and combination.
[0157]
Various surfactants and organic solvents can be added to the developer as necessary for the purpose of promoting developability, dispersing development residue, and improving the ink affinity of the printing plate image area. Preferred surfactants include anionic, cationic, nonionic and amphoteric surfactants.
[0158]
Preferable examples of the surfactant include the following.
Nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene polystyryl phenyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, glycerin fatty acid partial esters, sorbitan Fatty acid partial esters, pentaerythritol fatty acid partial esters, propylene glycol mono fatty acid esters, sucrose fatty acid partial esters, polyoxyethylene sorbitan fatty acid partial esters, polyoxyethylene sorbitol fatty acid partial esters, polyethylene glycol fatty acid esters, poly Glycerin fatty acid partial esters, polyoxyethylenated castor oil, polyoxyethylene glycerin fatty acid partial esters, fatty acid di Ethanol amides, N, N-bis-2-hydroxyalkylamines, polyoxyethylene alkylamines, triethanolamine fatty acid esters, such as trialkylamine oxides.
[0159]
Anionic surfactants include fatty acid salts, abietic acid salts, hydroxyalkane sulfonic acid salts, alkane sulfonic acid salts, dialkyl sulfosuccinic acid ester salts, linear alkyl benzene sulfonic acid salts, branched alkyl benzene sulfonic acid salts, alkyl naphthalene sulfone. Acid salts, alkylphenoxy polyoxyethylene propyl sulfonates, polyoxyethylene alkyl sulfophenyl ether salts, N-methyl-N-oleyl taurine sodium salt, N-alkyl sulfosuccinic acid monoamide disodium salt, petroleum sulfonates, sulfuric acid Tallow oil, fatty acid alkyl ester sulfate ester salt, alkyl sulfate ester salt, polyoxyethylene alkyl ether sulfate ester salt, fatty acid monoglyceride sulfate ester Oxyethylene alkylphenyl ether sulfates, polyoxyethylene styrylphenyl ether sulfates, alkyl phosphates, polyoxyethylene alkyl ether phosphates, polyoxyethylene alkylphenyl ether phosphates, styrene / anhydrous maleic Examples include anionic surfactants such as partially saponified products of acid copolymers, partially saponified products of olefin / maleic anhydride copolymers, and naphthalene sulfonate formalin condensates.
[0160]
Examples of the cationic surfactant include cationic surfactants such as alkylamine salts, quaternary ammonium salts such as tetrabutylammonium bromide, polyoxyethylene alkylamine salts, and polyethylene polyamine derivatives.
Examples of amphoteric surfactants include amphoteric surfactants such as carboxybetaines, aminocarboxylic acids, sulfobetaines, aminosulfuric esters, and imidazolines.
Among the surfactants listed above, those having polyoxyethylene can be read as polyoxyalkylenes such as polyoxymethylene, polyoxypropylene and polyoxybutylene, and these surfactants are also included.
[0161]
A more preferred surfactant is a fluorosurfactant containing a perfluoroalkyl group in the molecule. Such fluorosurfactants include perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, anionic types such as perfluoroalkyl phosphates, amphoteric types such as perfluoroalkyl betaines, and perfluoroalkyltrimethylammonium salts. Cationic and perfluoroalkyl amine oxides, perfluoroalkyl ethylene oxide adducts, perfluoroalkyl group and hydrophilic group-containing oligomers, perfluoroalkyl group and lipophilic group-containing oligomers, perfluoroalkyl groups, hydrophilic groups and lipophilic groups Nonionic types such as group-containing oligomers, perfluoroalkyl groups, and lipophilic group-containing urethanes can be mentioned. Said surfactant can be used individually or in combination of 2 or more types, and is added in 0.001 to 10 weight% in a developing solution, More preferably, it is added in 0.01 to 5 weight%.
[0162]
Various development stabilizers can be used in the developer. Preferred examples thereof include polyethylene glycol adducts of sugar alcohols described in JP-A-6-282079, tetraalkylammonium salts such as tetrabutylammonium hydroxide, phosphonium salts such as tetrabutylphosphonium bromide, and iodonium such as diphenyliodonium chloride. Salt. Furthermore, anionic surfactants or amphoteric surfactants described in JP-A No. 50-51324, water-soluble cationic polymers described in JP-A No. 55-95946, and JP-A No. 56-142528 are described. And water-soluble amphoteric polymer electrolytes that have been used.
[0163]
Furthermore, an organic boron compound to which an alkylene glycol is added as described in JP-A-59-84241, a polyoxyethylene / polyoxypropylene block polymerization type water-soluble surfactant as described in JP-A-60-111246, An alkylenediamine compound substituted with polyoxyethylene / polyoxypropylene disclosed in JP-A-60-129750, a polyethylene glycol having a weight average molecular weight of 300 or more described in JP-A-61-215554, and a cation described in JP-A-63-175858 And fluorine-containing surfactants having a functional group, water-soluble ethylene oxide addition compounds obtained by adding 4 mol or more of ethylene oxide to an acid or alcohol described in JP-A-2-39157, water-soluble polyalkylene compounds, and the like.
[0164]
If necessary, an organic solvent is further added to the developer. As such an organic solvent, those having a solubility in water of about 10% by weight or less are suitable, and preferably those having a solubility in water of 5% by weight or less are selected. For example, 1-phenylethanol, 2-phenylethanol, 3-phenyl-1-propanol, 4-phenyl-1-butanol, 4-phenyl-2-butanol, 2-phenyl-1-butanol, 2-phenoxyethanol, 2- Benzyloxyethanol, o-methoxybenzyl alcohol, m-methoxybenzyl alcohol, p-methoxybenzyl alcohol, benzyl alcohol, cyclohexanol, 2-methylcyclohexanol, 3-methylcyclohexanol and 4-methylcyclohexanol, N-phenylethanol Examples include amines and N-phenyldiethanolamine.
The content of the organic solvent is 0.1 to 5% by weight with respect to the total weight of the used solution. The amount used is closely related to the amount of surfactant used, and it is preferable to increase the amount of surfactant as the amount of organic solvent increases. This is because the amount of the surfactant is small, and when the amount of the organic solvent is large, the organic solvent is not completely dissolved, so that it is impossible to expect good developability.
[0165]
A reducing agent can be further added to the developer. This prevents the printing plate from being stained. Preferable organic reducing agents include phenol compounds such as thiosalicylic acid, hydroquinone, metol, methoxyquinone, resorcin, and 2-methylresorcin, and amine compounds such as phenylenediamine and phenylhydrazine. More preferable inorganic reducing agents include sodium, potassium and ammonium salts of inorganic acids such as sulfurous acid, bisulfite, phosphorous acid, hydrogen phosphite, dihydrogen phosphite, thiosulfuric acid and dithionite. A salt etc. can be mentioned.
Among these reducing agents, sulfites are particularly excellent in the antifouling effect. These reducing agents are preferably contained in the range of 0.05 to 5% by weight with respect to the developer at the time of use.
[0166]
An organic carboxylic acid can also be added to the developer. Preferred organic carboxylic acids are aliphatic carboxylic acids and aromatic carboxylic acids having 6 to 20 carbon atoms. Specific examples of the aliphatic carboxylic acid include caproic acid, enanthylic acid, caprylic acid, lauric acid, myristic acid, palmitic acid and stearic acid, and particularly preferred are alkanoic acids having 8 to 12 carbon atoms. . In addition, the aliphatic carboxylic acid may be an unsaturated fatty acid having a double bond in the carbon chain or a branched carbon chain. The aromatic carboxylic acid is a compound in which a carboxyl group is substituted on a benzene ring, naphthalene ring, anthracene ring, etc., specifically, o-chlorobenzoic acid, p-chlorobenzoic acid, o-hydroxybenzoic acid, p -Hydroxybenzoic acid, o-aminobenzoic acid, p-aminobenzoic acid, 2,4-dihydrobenzoic acid, 2,5-dihydroxybenzoic acid, 2,6-dihydroxybenzoic acid, 2,3-dihydroxybenzoic acid, 3 , 5-dihydroxybenzoic acid, gallic acid, 1-hydroxy-2-naphthoic acid, 3-hydroxy-2-naphthoic acid, 2-hydroxy-1-naphthoic acid, 1-naphthoic acid, 2-naphthoic acid, etc. Hydroxynaphthoic acid is particularly effective.
[0167]
The aliphatic and aromatic carboxylic acids are preferably used as sodium salts, potassium salts or ammonium salts in order to enhance water solubility. The content of the organic carboxylic acid in the developer used in the present invention is not particularly limited, but if it is less than 0.1% by weight, the effect is not sufficient, and if it is 10% by weight or more, the effect is further improved. Not only can it be measured, it can interfere with dissolution when used with other additives. Therefore, the preferable addition amount is 0.1 to 10% by weight, and more preferably 0.5 to 4% by weight with respect to the developing solution in use.
[0168]
If necessary, the developer may further contain a preservative, a colorant, a thickener, an antifoaming agent, a hard water softening agent, and the like.
Examples of water softeners include polyphosphoric acid and its sodium, potassium and ammonium salts, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, hydroxyethylethylenediaminetriacetic acid, nitrilotriacetic acid, 1,2-diaminocyclohexanetetra Aminopolycarboxylic acids such as acetic acid and 1,3-diamino-2-propanoltetraacetic acid, and their sodium, potassium or ammonium salts; aminotri (methylenephosphonic acid), ethylenediaminetetra (methylenephosphonic acid), diethylenetriaminepenta ( Methylenephosphonic acid), triethylenetetramine hexa (methylenephosphonic acid), hydroxyethylethylenediaminetri (methylenephosphonic acid) and 1- Dorokishitaen 1,1 diphosphonic acid, and sodium salts thereof, and potassium salts or ammonium salts.
[0169]
The optimum value of such a hard water softener varies depending on the chelation, the hardness of the hard water used, and the amount of hard water. A general usage amount of the water softener is 0.01 to 5% by weight, more preferably 0.01 to 0.5% by weight in the developing solution at the time of use. If the addition amount is less than this range, the intended purpose is not sufficiently achieved. If the addition amount is more than this range, adverse effects on the image area such as color loss will occur. The remaining component of the developer is water. It is advantageous in terms of transportation that the developer is a concentrated solution having a water content less than that in use and is diluted with water when in use. In this case, the degree of concentration is appropriate such that each component does not cause separation or precipitation.
[0170]
As the developer for the lithographic printing plate precursor according to the invention, a developer described in JP-A-6-282079 can also be used. This is SiO₂/ M₂Water-soluble ethylene oxide addition obtained by adding 5 mol or more of ethylene oxide to a sugar alcohol having a molar ratio of O (M represents an alkali metal) of 0.5 to 2.0 and a sugar alcohol having 4 or more hydroxyl groups A developer containing a compound. Sugar alcohols are polyhydric alcohols corresponding to those obtained by reducing sugar aldehyde groups and ketone groups to form primary and secondary alcohol groups, respectively. Examples of sugar alcohol shells include D, L-trait, erythrite, D, L-arabit, rebit, xylit, D, L-sorbit, D, L-mannit, D, L-exit, D, L-talit, dulcite, allozulcit, and the like, and di-, tri-, tetra-, penta-, and hexaglycerin condensed with a sugar alcohol are also included. The water-soluble ethylene oxide addition compound can be obtained by adding 5 mol or more of ethylene oxide to 1 mol of the sugar alcohol. Further, propylene oxide may be block-copolymerized in the ethylene oxide addition compound as required in a range where solubility is acceptable. These ethylene oxide addition compounds may be used alone or in combination of two or more.
The addition amount of these water-soluble ethylene oxide addition compounds is suitably 0.001 to 5% by weight, more preferably 0.001 to 2% by weight, based on the developer (working solution).
[0171]
The above-mentioned various surfactants and organic solvents can be added to the developer as needed for the purpose of promoting developability, dispersing development residue, and improving the ink affinity of the printing plate image area.
[0172]
A lithographic printing plate precursor developed with a developer having such a composition is subjected to a post-treatment with a washing water, a rinse solution containing a surfactant, a finisher or a protective gum solution mainly composed of gum arabic or starch derivatives. Is done. These treatments can be used in various combinations for the post-treatment of the lithographic printing plate precursor according to the invention.
[0173]
In recent years, automatic developing machines for PS plates have been widely used in the stencil and printing industries in order to rationalize and standardize plate making operations. This automatic developing machine is generally composed of a developing section and a post-processing section, and is composed of a device for transporting the PS plate, each processing solution tank and a spray device, and is pumped by a pump while transporting the exposed PS plate horizontally. Each processing solution is sprayed from a spray nozzle to develop and post-process. In addition, recently, a PS plate is immersed and transported in a processing solution tank filled with a processing solution by a guide roll in the solution, and a small amount of washing water after development is supplied to the plate surface for washing. A method is also known in which the waste water is reused as dilution water for the developer stock solution.
[0174]
In such automatic processing, each processing solution can be processed while being replenished with each replenishing solution according to the processing amount, operating time, and the like. In addition, a so-called disposable processing method of processing with a substantially unused processing solution can be applied to the present invention. The planographic printing plate obtained by such processing is loaded on an offset printing machine and used for printing a large number of sheets.
[0175]
【Example】
EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
[0176]
(Production of support)
Supports A, B, C, and D were prepared by using a JIS-A-1050 aluminum plate having a thickness of 0.3 mm in combination with the following processes.
(A) Mechanical roughening treatment
While a suspension of a polishing agent (silica sand) having a specific gravity of 1.12 and water was supplied to the surface of the aluminum plate as a polishing slurry, mechanical surface roughening was performed with a rotating roller-like nylon brush. The average particle size of the abrasive was 8 μm, and the maximum particle size was 50 μm. The material of the nylon brush was 6 · 10 nylon, the hair length was 50 mm, and the hair diameter was 0.3 mm. The nylon brush was planted so as to be dense by making a hole in a stainless steel tube having a diameter of 300 mm. Three rotating brushes were used. The distance between the two support rollers (φ200 mm) at the bottom of the brush was 300 mm. The brush roller was pressed until the load of the drive motor for rotating the brush became 7 kW plus with respect to the load before the brush roller was pressed against the aluminum plate. The rotating direction of the brush was the same as the moving direction of the aluminum plate. The rotation speed of the brush was 200 rpm.
[0177]
(B) Alkali etching treatment
The aluminum plate obtained above was sprayed with an aqueous NaOH solution (concentration 26 wt%, aluminum ion concentration 6.5 wt%) at a temperature of 70 ° C., and the aluminum plate was 6 g / m 2.²Dissolved. Thereafter, washing with water was performed using well water.
[0178]
(C) Desmut treatment
The desmutting treatment was performed by spraying with a 1% by weight aqueous solution of nitric acid having a temperature of 30 ° C. (containing 0.5% by weight of aluminum ions), and then washed with water by spraying. The nitric acid aqueous solution used for the desmut was the waste liquid from the step of electrochemical surface roughening using alternating current in nitric acid aqueous solution.
[0179]
(D) Electrochemical roughening treatment
An electrochemical surface roughening treatment was continuously performed using an alternating voltage of 60 Hz. The electrolytic solution at this time was a nitric acid 10.5 g / liter aqueous solution (aluminum ion 5 g / liter) at a temperature of 50 ° C. The AC power supply waveform has an electrochemical surface roughening treatment using a carbon electrode as a counter electrode using a trapezoidal rectangular wave alternating current, with a time TP of 0.8 msec until the current value reaches a peak from zero, a duty ratio of 1: 1 went. Ferrite was used for the auxiliary anode. The electrolytic cell used was a radial cell type.
The current density is 30 A / dm at the peak current value.²The amount of electricity is 220 C / dm in terms of the total amount of electricity when the aluminum plate is the anode.²Met. 5% of the current flowing from the power source was shunted to the auxiliary anode.
Thereafter, washing with water was performed using well water.
[0180]
(E) Alkali etching treatment
The aluminum plate was etched at 32 ° C. with a caustic soda concentration of 26 wt% and an aluminum ion concentration of 6.5 wt%, and the aluminum plate was 0.20 g / m.²Dissolve and remove the smut component mainly composed of aluminum hydroxide that was generated when electrochemical roughening was performed using alternating current in the previous stage, and dissolve the edge part of the generated pit to produce the edge part Made smooth. Thereafter, washing with water was performed using well water.
[0181]
(F) Desmut treatment
The desmutting treatment was performed by spraying with a 15% by weight aqueous solution of nitric acid at a temperature of 30 ° C. (containing 4.5% by weight of aluminum ions), and then washed with water using well water. The nitric acid aqueous solution used for the desmut was the waste liquid from the step of electrochemical surface roughening using alternating current in nitric acid aqueous solution.
[0182]
(G) Electrochemical roughening treatment
An electrochemical surface roughening treatment was continuously performed using an alternating voltage of 60 Hz. The electrolytic solution at this time was a hydrochloric acid 7.5 g / liter aqueous solution (containing 5 g / liter of aluminum ions) at a temperature of 35 ° C. The AC power supply waveform was a rectangular wave, and an electrochemical surface roughening treatment was performed using a carbon electrode as a counter electrode. Ferrite was used for the auxiliary anode. The electrolytic cell used was a radial cell type.
The current density is 25 A / dm at the peak current value.²The amount of electricity is 50 C / dm as the total amount of electricity when the aluminum plate is the anode.²Met.
Thereafter, washing with water was performed using well water.
[0183]
(H) Alkali etching treatment
The aluminum plate was etched at 32 ° C. with a caustic soda concentration of 26 wt% and an aluminum ion concentration of 6.5 wt%, and the aluminum plate was 0.10 g / m.²Dissolves and removes the smut component mainly composed of aluminum hydroxide generated when electrochemical roughening treatment is performed using the alternating current of the previous stage, and dissolves the edge part of the generated pit The part was smoothed. Thereafter, washing with water was performed using well water.
[0184]
(I) Desmut treatment
A desmutting treatment was performed by spraying with an aqueous solution of sulfuric acid having a concentration of 25% by weight (containing 0.5% by weight of aluminum ions) at a temperature of 60 ° C., followed by washing with water using well water.
[0185]
(J) Anodizing treatment
Sulfuric acid was used as the electrolytic solution. All electrolytes had a sulfuric acid concentration of 170 g / liter (containing 0.5% by weight of aluminum ions) and a temperature of 43 ° C. Thereafter, washing with water was performed using well water.
Both current densities are about 30 A / dm²Met. The final oxide film amount is 2.7 g / m²Met.
[0186]
<Support A>
The steps (a) to (j) are performed in order, and the etching amount in the step (e) is 3.4 g / m.²The support A was prepared as described above.
<Support B>
A support B was prepared by sequentially performing the steps except that the steps (g), (h), and (i) were omitted.
[0187]
<Support C>
A support C was prepared by sequentially performing the steps except that the steps (a), (g), (h), and (i) were omitted.
<Support D>
Of the above steps, the steps (a) and (d) (e) (f) are omitted except that the steps are performed in order, and the total amount of electricity in the step (g) is 450 C / dm.²Thus, a support D was produced.
The following supports A, B, and C obtained as described above were subsequently subjected to the following hydrophilization treatment and undercoating treatment.
[0188]
(K) Alkali metal silicate treatment
The aluminum support obtained by the anodizing treatment is immersed in a treatment layer of 1 wt% aqueous solution of sodium silicate No. 3 at a temperature of 30 ° C. for 10 seconds to perform alkali metal silicate treatment (silicate treatment). went. Then, the water washing by the spray using well water was performed. In this case, the amount of silicate attached is 3.6 mg / m²Met.
[0189]
[(1) Formation of undercoat]
On the aluminum support after the alkali metal silicate treatment obtained as described above, an undercoat solution having the following composition was applied and dried at 80 ° C. for 15 seconds. The coating amount after drying is 18 mg / m²Met.
[0190]
<Undercoat liquid composition>
The following polymer compound 0.3g
Methanol 100g
1.0g of water
[0191]
Embedded image
[0192]
[Synthesis of specific phenolic resin]
(Synthesis Example) Phenol / m-cresol / p-cresol (20/70/10) nonylation (5 mol%)
11.18 g of phenol / m-cresol / p-cresol (20/70/10) and 1.13 g of nonyl iodide were dissolved in 10 g of acetone. This solution was heated to 65 ° C., and 0.69 g of potassium carbonate was added thereto. After stirring at 65 ° C. for 8 hours, the temperature was gradually returned to room temperature. 20 ml of 1N hydrochloric acid was added to the reaction solution and stirred for a while. 75 ml of distilled water was added to the reaction solution and washed twice. The obtained solid was dissolved in 30 ml of methanol and then added dropwise to 3 L of distilled water over 30 minutes. When 5 mol% nonylated phenol / m-cresol / p-cresol (20/70/10) A novolac resin was obtained.
The specific phenol resins other than those used in the following examples were also synthesized in the same manner.
[0193]
(Examples 1-6)
The following image recording layer coating liquid 1 (photosensitive composition) is applied to the obtained supports A to D, dried in an oven at 150 ° C. for 1 minute, and the dry film thickness is 1.7 g / m.²A positive lithographic printing plate precursor was prepared.
[0194]
<Image recording layer coating solution 1>
[0195]
Embedded image
[0196]
(Example 7)
On the obtained support A, the following image recording layer coating solution 2 was applied in an amount of 0.9 g / m.²After coating, the Wind Control was set to 7 with PERFECT OVEN PH200 manufactured by Tabai Co. and dried at 160 ° C. for 60 seconds to obtain a positive planographic printing plate precursor of Example 7.
[0197]
<Image recording layer coating solution 2>
[0200]
(Example8)
  A coating solution for the first layer (organic intermediate layer) having the following composition was applied to the obtained support A with a wire bar, and then dried in a drying oven at 135 ° C. for 90 seconds to obtain a coating amount of 0.85 g / m.²It was.
  A coating solution for the second layer (image recording layer) having the following composition was applied to the obtained support with an organic intermediate layer with a wire bar. After coating, drying is performed at 150 ° C. for 50 seconds in a drying oven, and the total coating amount is 1.1 g / m.²A positive type lithographic printing plate precursor was prepared.
[0201]
<First layer (organic intermediate layer) coating solution>
[0202]
Embedded image
[0203]
<Second layer (image recording layer) coating solution>
[0204]
Embedded image
[0208]
(Example9)
  Instead of the specific phenol resin used in the image recording layer coating solution 1, a resin in which a part of the hydroxyl group of the novolak type phenol resin is modified with a fluorine-containing alkyl ether group [a novolak resin comprising phenol, m-cresol and p-cresol Example 1 was carried out in the same manner as in Examples 1 to 6 except that a novolak resin (weight average molecular weight 4800) obtained by 5% 6- (perfluorobutyl) hexylation (molar ratio 20:70:10) was used.9A positive lithographic printing plate precursor was prepared.
[0209]
(Comparative Example 1)
In the image recording layer coating solution 1, except that a novolak resin (molar ratio 20:70:10, weight average molecular weight 4600) composed of phenol, m-cresol and p-cresol was used instead of the specific phenol resin, In the same manner as in Examples 1 to 6, a positive planographic printing plate precursor of Comparative Example 1 was obtained.
[0210]
(Evaluation of lithographic printing plate precursor)
1. Evaluation of development latitude
Each lithographic printing plate precursor thus obtained was stored for 6 days under conditions of a temperature of 20 ° C. and a relative humidity of 45%. I did.
Thereafter, by using a PS processor 900H manufactured by Fuji Photo Film Co., Ltd., in which the conductivity was changed by changing the dilution rate by changing the amount of water of the alkaline developer of the following A composition and B composition, The liquid temperature was kept at 30 ° C., and development was performed with a development time of 22 seconds. At this time, the image portion is not eluted, and the developer having the highest and lowest conductivity of the developer that can be satisfactorily developed without being stained or colored due to poorly developed image recording layer residual film. Was evaluated as development latitude. The results are shown in Table 2.
[0211]
<Alkali developer A composition>
・ SiO₂・ K₂O (K₂O / SiO₂= 1/1 (molar ratio)) 5.0 wt%
・ Citric acid 0.4% by weight
・ Polyethylene glycol lauryl ether 0.6% by weight
(Weight average molecular weight 1,000)
・ Water 94.0% by weight
[0212]
<Alkali developer B composition>
・ D sorbit 3.0% by weight
・ 0.8% by weight of sodium hydroxide
・ Polyethylene glycol lauryl ether 0.6% by weight
(Weight average molecular weight 1,000)
・ Water 95.6% by weight
[0213]
2. Sensitivity evaluation
With respect to each obtained lithographic printing original plate, the exposure energy was changed with a Trendsetter 3244VX manufactured by Creo, and a test pattern was drawn in an image form. Thereafter, in the evaluation of the development latitude, the image portion was not eluted, and the developer having the highest conductivity was able to be satisfactorily developed without being stained or colored due to a poorly developed image recording layer residual film. Developed with an alkaline developer having an intermediate conductivity (average value) of the lowest one, and measured the exposure amount (beam intensity at a drum rotation speed of 120 rpm) that can develop a non-image area with this developer. It was. The smaller the numerical value, the higher the sensitivity. The results are shown in Table 2 below.
[0214]
3. Evaluation of bakeability
Each obtained lithographic printing plate is exposed in the same manner as in the sensitivity evaluation, and after being stored for one hour in an environment of 20 ° C. and a relative humidity of 80%, the same evaluation as in the sensitivity evaluation is performed. The degree of decrease in sensitivity was used as a guideline for shrinkage. The numerical value represents the sensitivity after 1 hour of exposure, and the closer the numerical value is to the sensitivity immediately after exposure, the better the shrinkage.
[0215]
[Table 1]
[0216]
[Table 2]
[0217]
  As is apparent from Table 2, Examples 1 to 3 using the specific phenol resin according to the present invention were used.9The lithographic printing plate precursor was excellent in shrinkage regardless of silicate development or non-silicate development. Further, the obtained lithographic printing plate precursor was excellent in sensitivity and wide in development latitude, so that it was found that the formation of a residual film during development was suppressed and image formation with excellent contrast was possible. Further examples8From these results, it was found that the lithographic printing plate precursor according to the present invention exhibits excellent effects not only when it has a single layer but also when it has an image recording layer having a multilayer structure.
  On the other hand, the lithographic printing plate precursor of Comparative Example 1 using a novolak resin composed of phenol, m-cresol and p-cresol as the phenolic resin is inferior in shrinkage compared to the examples and has a somewhat narrow development latitude. I understand.
[0218]
【The invention's effect】
The lithographic printing plate precursor according to the present invention can be directly made by an infrared laser, is excellent in a difference in solubility in a developing solution between an exposed portion and a non-exposed portion (dissolvable discrepancy), and depends on the time after exposure. There is an effect that the degree of change in developability is small (the shrinkage is good).

Claims (1)

The hydrophilic support contains (A) a novolak type phenol resin containing a partial structure represented by the following general formula (I) , and (B) a photothermal conversion agent, and is soluble in an alkaline aqueous solution by infrared laser exposure. A positive-type lithographic printing plate precursor comprising an image recording layer having an increased number of layers.
[In General Formula (I), R ¹ is a linear unsubstituted alkyl group having 1 to 12 carbon atoms, a branched unsubstituted alkyl group having 3 to 12 carbon atoms, or a carbon number having 5 to 10 carbon atoms. A cyclic unsubstituted alkyl group is represented, and R ² , R ³ and R ⁴ each independently represents a hydrogen atom, an alkyl group or a halogen atom. ]