Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
  • B41C1/00—Forme preparation
  • B41C1/10—Forme preparation for lithographic printing; Master sheets for transferring a lithographic image to the forme
  • B41C1/1008—Forme preparation for lithographic printing; Master sheets for transferring a lithographic image to the forme by removal or destruction of lithographic material on the lithographic support, e.g. by laser or spark ablation; by the use of materials rendered soluble or insoluble by heat exposure, e.g. by heat produced from a light to heat transforming system; by on-the-press exposure or on-the-press development, e.g. by the fountain of photolithographic materials
  • B41C1/1016—Forme preparation for lithographic printing; Master sheets for transferring a lithographic image to the forme by removal or destruction of lithographic material on the lithographic support, e.g. by laser or spark ablation; by the use of materials rendered soluble or insoluble by heat exposure, e.g. by heat produced from a light to heat transforming system; by on-the-press exposure or on-the-press development, e.g. by the fountain of photolithographic materials characterised by structural details, e.g. protective layers, backcoat layers or several imaging layers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
  • B41C2210/00—Preparation or type or constituents of the imaging layers, in relation to lithographic printing forme preparation
  • B41C2210/02—Positive working, i.e. the exposed (imaged) areas are removed
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
  • B41C2210/00—Preparation or type or constituents of the imaging layers, in relation to lithographic printing forme preparation
  • B41C2210/06—Developable by an alkaline solution
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
  • B41C2210/00—Preparation or type or constituents of the imaging layers, in relation to lithographic printing forme preparation
  • B41C2210/14—Multiple imaging layers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
  • B41C2210/00—Preparation or type or constituents of the imaging layers, in relation to lithographic printing forme preparation
  • B41C2210/22—Preparation or type or constituents of the imaging layers, in relation to lithographic printing forme preparation characterised by organic non-macromolecular additives, e.g. dyes, UV-absorbers, plasticisers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
  • B41C2210/00—Preparation or type or constituents of the imaging layers, in relation to lithographic printing forme preparation
  • B41C2210/24—Preparation or type or constituents of the imaging layers, in relation to lithographic printing forme preparation characterised by a macromolecular compound or binder obtained by reactions involving carbon-to-carbon unsaturated bonds, e.g. acrylics, vinyl polymers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
  • B41C2210/00—Preparation or type or constituents of the imaging layers, in relation to lithographic printing forme preparation
  • B41C2210/26—Preparation or type or constituents of the imaging layers, in relation to lithographic printing forme preparation characterised by a macromolecular compound or binder obtained by reactions not involving carbon-to-carbon unsaturated bonds
  • B41C2210/262—Phenolic condensation polymers, e.g. novolacs, resols

Definitions

• the present invention relates to a planographic printing plate precursor that can be used as an offset printing master. More particularly, it relates to a so-called positive planographic printing plate precursor for direct plate-making, capable of forming a printing plate directly from digital signals from a computer or the like.
• Materials which can be used for positive type planographic printing plate precursors applicable for infrared lasers include, as essential components, a binder resin soluble in an aqueous alkaline solution (hereinafter referred to where appropriate as an "alkali-soluble resin"), and an infrared dye which absorbs light to generate heat.
• the infrared dye interacts with the binder resin in its unexposed portions (image portions) so as to function as a dissolution inhibitor which can substantially reduce the solubility of the binder resin to the developer.
• image portions image portions
• dissolution inhibitor which can substantially reduce the solubility of the binder resin to the developer.
• interaction of the infra red dye with the binder resin is weakened by the heat generated. Consequently, the exposed portions are able to be dissolved in an alkaline developer, so that an image is formed thereon and a planographic printing plate is formed.
• the image forming ability of the positive planographic printing plate precursor used with the infrared laser depends on heat generation caused by irradiation with the infrared laser on a surface of the recording layer, the amount of heat used for forming images, i.e., for solubilization of the recording layer, is lowered in the vicinity of the support due to heat diffusion to the support, thereby lowering the sensitivity of the recording layer. Therefore, a problem arises in that an effect of losing the development inhibiting function of the recording layer is not sufficiently obtained in the non-image area, and consequently, the difference between the image area and the non-image area decreases. In particular, the reproducibility of highly fine images, such as halftone dots and thin lines, is insufficient.
• the image forming property must be improved because the images have only a small area. If a recording layer comprising a material that allows the non-image area to be readily developed is used for this purpose, the planographic printing plate is susceptible to damage by the action of a developer, an ink cleaner, a plate cleaner or the like used when printing. In other words, such a planographic printing plate is poor in chemical resistance and printing durability.
• a planographic printing plate precursor has been disclosed that has a recording layer which comprises a lower layer containing an acrylic resin and being excellent in alkali solubility and an upper layer including a water-insoluble alkali-soluble resin and an infrared absorber, the solubility of the upper layer in an aqueous alkali solution being greatly increased by exposure (see, for example, Japanese Patent Application Laid Open ( JP-A) No. 10-250255 ).
• planographic printing plate precursor it is possible to improve sensitivity and chemical resistance.
• problems for example, (1) the adhesion between the support and the recording layer is insufficient, (2) the edge of the lower layer is damaged by an alkali developer in the boundary between an image area and a non-image area to cause a phenomenon called "side edge" and, as a result, the ON/OFF of images becomes unclear and the sharpness of images is reduced, and (3) especially in small-area image areas, the recording layer readily peels off and the printing durability in halftone dots or thin lines is poor.
• a first aspect of the present invention provides a planographic printing plate precursor comprising:
• the present invention has been made in view of the aforementioned problems associated with the conventional art, and aims to provide a positive planographic printing plate precursor which can directly form a printing plate by scanning exposure based on digital signals, which is superior in reproducibility of highly fine images to the extent that sharp images can be formed and which is superior in both printing durability and chemical resistance of small-area image areas such as halftone dots and thin lines.
• a polymer compound contained in an lower layer of the planographic printing plate precursor of the invention and having a constituent expressed by the formula (I) is, even when it is singularly formed into a film, excellent in the film strength, contributing to improve the printing durability, and more excellent in the dissolution resistance to organic solvents in comparison with known acrylic alkali-soluble resins for instance. Accordingly, the particular polymer compound is considered resistant to damages due to a plate cleaner.
• the polymer compound owing to the presence of the phenolic hydroxyl group therein, is excellent in the affinity with the alkali-soluble resin contained in the upper layer, resulting as well in excellent adhesiveness between the upper layer and the lower layer. Accordingly, it is considered that in an image portion, that is, in a region where an image recording layer that is an upper layer exists as an alkali development resistant layer, since high film strength and chemical resistance work effectively and, furthermore, the adhesiveness with the alkali development resistant layer is excellent, even in a small area image portion, excellent printing durability is exhibited, and, in a non-image portion where the upper layer is removed, owing to intrinsic alkali solubility, the polymer compound is readily dissolved and dispersed in an alkali development solution, resulting in excellent image formability of a fine image.
• a planographic printing plate precursor of the invention is formed by disposing, on a support, a recording layer that includes an lower layer containing a polymer compound having a constituent expressed by a formula (I) below and a upper layer that contains a water-insoluble and alkali-soluble resin and an infrared absorber and causes an increase in the solubility to an alkaline aqueous solution under exposure.
• a recording layer that includes an lower layer containing a polymer compound having a constituent expressed by a formula (I) below and a upper layer that contains a water-insoluble and alkali-soluble resin and an infrared absorber and causes an increase in the solubility to an alkaline aqueous solution under exposure.
• n represents an integer from 0 to 2 and A represents an aryl group.
• a lower layer according to the invention includes a particular polymer compound having a constituent expressed by the formula (I) below.
• n represents an integer from 0 to 2 and A represents an aryl group.
• An aryl group may further have a substitution group.
• substitution groups that can be introduced include a methyl group, ethyl group, propyl group, methoxy group and ethoxy group.
• the particular polymer compound is preferably insoluble in water, soluble in an alkaline aqueous solution and a resin obtained through a condensation polymerization of a diazonium salt and any of monomers selected from a group of phenols, bisphenols, hydroxyl naphthalenes and low molecular weight condensation compounds of p-cresol/formaldehyde.
• a phenolic hydroxyl group may be substituted through a reaction of degeneration, more specifically, a phenolic hydroxyl group may be substituted with any of a group made of an ether group (-OR 0 ), ester group (-OCOR 0 ), urethane group (-OCONHR 0 ) and carbonate group (-OCO 2 R 0 ).
• ether group -OR 0
• ester group -OCOR 0
• urethane group -OCONHR 0
• carbonate group -OCO 2 R 0
• reaction of degeneration of the particular polymer compound a reaction of substitution with an organic halide, organic silane compound or organic silyl chloride or an addition reaction with a reactive compound such as isocyanate compounds or epoxy compounds can be cited.
• examples of reactions of the specified macromolecular compound which are conducted in the presence of a basic compound include the following.
• modified resins include ether derivatives resulting from a reaction with an organic halogen compound, silyl ether derivatives resulting from a reaction with an organic silyl chloride, silyl ether derivatives resulting from a reaction with an organic silane or siloxane, ester derivatives resulting from a reaction with an organic acid chloride such as an organic acid chloride, an organic sulfonic acid chloride or an organic phosphoric acid chloride, and carbonate derivatives resulting from a reaction with a chloroformic acid ester.
• Urethane derivatives resulting from an addition reaction with an isocyanate and ether derivatives resulting from an addition reaction with an epoxy compound are also preferred.
• the particular polymer compound of the invention preferably contains 20 to 100 mass percent of a constituent expressed by the formula (I) in a molecule, more preferably 40 to 100 mass percent and still more preferably 60 to 100 mass percent.
• the particular polymer compound may be a random, alternative, block or graft copolymer of different monomers.
• resins having such constituents for instance, polymers or copolymers of vinyl phenol and novolak resins can be cited. Among these, the novolak resins are preferred.
• polymer compounds having a phenolic hydroxyl group such as a phenol formaldehyde resin, m-cresol formaldehyde resin, p-cresol formaldehyde resin, m-/p-mixture cresol formaldehyde resin, and phenol/cresol (any of m-, p-, or m-/p- mixture may be acceptable) mixture formaldehyde resin can be cited.
• the macromolecular compound having a phenolic hydroxyl group it is preferable to use macromolecular compounds having a phenolic hydroxyl group at their side chains besides the above compounds.
• the macromolecular compound having a phenolic hydroxyl group at its side chain include macromolecular compounds obtained by homopolymerizing a polymerizable monomer comprising a low-molecular compound having one or more phenolic hydroxyl groups and one or more polymerizable unsaturated bonds or copolymerizing this monomer with other polymerizable monomers.
• Examples of the polymerizable monomer having a phenolic hydroxyl group include acrylamides, methacrylamides, acrylates and methacrylates each having a phenolic hydroxyl group or hydroxystyrenes.
• Specific examples of the polymerizable monomer which may be preferably used include N-(2-hydroxyphenyl)acrylamide, N-(3-hydroxyphenyl)acrylamide, N-(4-hydroxyphenyl)acrylamide, N-(2-hydroxyphenyl)methacrylamide, N-(3-hydroxyphenyl)methacrylamide, N-(4-hydroxyphenyl)methacrylamide, o-hydroxyphenylacrylate, m-hydroxyphenylacrylate, p-hydroxyphenylacrylate, o-hydroxyphenylmethacrylate, m-hydroxyphenylmethacrylate, p-hydroxyphenylmethacrylate, o-hydroxystyrene, m-hydroxystyrene, p-hydroxystyren
• condensation polymers of phenols having an alkyl group having 3 to 8 carbon atoms as a substituent and formaldehyde such as a t-butylphenol formaldehyde resin and octylphenol formaldehyde resin as described in the specification of U.S. Patent No. 4,123,279 may be used together.
• structural units having an acid group specifically, structural units having (1) a phenolic hydroxyl group, (2) a sulfoneamide group or (3) an active imide group, which will be detailed below, can be cited, and more specifically, bisphenol A of the phenols and naphthalenes can be preferably cited.
• the particular polymer compound of the invention can be obtained through several kinds of methods. For instance, a method where a polymer containing a phenolic monomer unit is caused to react with a diazonium salt and a method where after a phenolic monomer unit is caused to react with a diazonium salt, the reacted monomer is polymerized or copolymerized can be cited. Furthermore, a method where a phenolic monomer caused to react with a diazonium salt is preferably copolymerized or condensation copolymerized with other monomer can be used to obtain.
• aromatic amines that can be diazotized to a diazonium salt that can be further used in an azo-coupling with a phenol group of a phenolic monomer, for instance, ones such as (A-1) through (A-18) exemplified below can be cited.
• a molecular weight of the particular polymer compound is, from the viewpoint of the solvent resistance and the solubility to a coating solvent, preferably in the range of 500 to 150,000 and more preferably in the range of 1,500 to 15,000 in the weight average molecular weight. Furthermore, a number average molecular weight is 500 or more and more preferably in the range of 1,000 to 20,000.
• the particular polymer compounds that are used in the invention are known compounds and known as a heat sensitive composition.
• a heat sensitive composition when it is used in the outermost surface of a recording layer, there remain such problems as the inking properties of ink, which have to be overcome.
• the particular polymer compound when used as a lower layer of a multi-layered recording layer, an excellent advantage can be exhibited in the sharpness of an image and dot printing durability.
• the particular polymer compounds may be used in the lower layer singularly or in a combination of at least two kinds thereof.
• a content of the particular polymer compound contained in the lower layer component of the invention is, to a total solid content, preferably in the range of 20 to 95 mass percent and more preferably in the range of 60 to 90 mass percent.
• the lower layer component of the invention in addition to the particular polymer compound, other resin can be used together in the range that does not damage the advantages of the invention.
• a resin that does not damage the foregoing characteristics is necessarily selected.
• a polymer than can be used together therein water-insoluble and alkali-soluble polymers can be cited.
• a polyamide resin, epoxy resin, polyacetal resin, acrylic resin, methacrylic resin, polystyrenic resin and novolak type phenolic resin can be preferably cited.
• an amount to be mixed it is preferably 50 mass percent or less to the particular polymer compound.
• the upper layer of the invention is characterized by containing a water-insoluble alkali-soluble resin (hereinafter, referred sometimes to as an "alkali-soluble resin") and an infrared absorber, and in that the solubility of the upper layer in an aqueous alkali solution is increased by exposure.
• alkali-soluble resin water-insoluble alkali-soluble resin
• infrared absorber infrared absorber
• the alkali-soluble resin that may be used in the upper layer of the invention is not particularly limited insofar as it has such characteristics as being soluble in an alkali developer upon contact therewith, and preferable examples are a homopolymer containing an acidic group in a main chain and/or a side chain of the polymer, and a copolymer or a mixture thereof
• the alkali-soluble resin having an acidic group include a polymer compound containing in the molecule a functional group selected from (1) a phenolic hydroxyl group, (2) a sulfonamide group and (3) an active imide group. Specific examples thereof include the following, but the invention is not limited thereto.
• Examples of the macromolecular compounds comprising phenolic hydroxyl group may include novolak resin such as condensation polymers of phenol and formaldehyde, condensation polymers of m-cresol and formaldehyde, condensation polymers of p-cresol and formaldehyde, condensation polymers of m-/p-mixed cresol and formaldehyde, and condensation polymers of phenol/cresol (m-, p-, or m-/p-mixture) and formaldehyde; and condensation copolymers of pyrogallol and acetone.
• novolak resin such as condensation polymers of phenol and formaldehyde, condensation polymers of m-cresol and formaldehyde, condensation polymers of p-cresol and formaldehyde, condensation polymers of m-/p-mixed cresol and formaldehyde, and condensation polymers of phenol/cresol (m-, p-, or m-/p-mixture) and formaldehyde
• the macromolecular compound having a phenolic hydroxyl group it is preferable to use macromolecular compounds having a phenolic hydroxyl group at their side chains besides the above compounds.
• the macromolecular compound having a phenolic hydroxyl group at its side chain include macromolecular compounds obtained by homopolymerizing a polymerizable monomer comprising a low-molecular compound having one or more phenolic hydroxyl groups and one or more polymerizable unsaturated bonds or copolymerizing this monomer with other polymerizable monomers.
• Examples of the polymerizable monomer having a phenolic hydroxyl group include acrylamides, methacrylamides, acrylates and methacrylates each having a phenolic hydroxyl group or hydroxystyrenes.
• Specific examples of the polymerizable monomer which may be preferably used include N-(2-hydroxyphenyl)acrylamide, N-(3-hydroxyphenyl)acrylamide, N-(4-hydroxyphenyl)acrylamide, N-(2-hydroxyphenyl)methacrylamide, N-(3-hydroxyphenyl)methacrylamide, N-(4-hydroxyphenyl)methacrylamide, o-hydroxyphenylacrylate, m-hydroxyphenylacrylate, p-hydroxyphenylacrylate, o-hydroxyphenylmethacrylate, m-hydroxyphenylmethacrylate, p-hydroxyphenylmethacrylate, o-hydroxystyrene, m-hydroxystyrene, p-hydroxystyren
• condensation polymers of phenols having an alkyl group having 3 to 8 carbon atoms as a substituent and formaldehyde such as a t-butylphenol formaldehyde resin and octylphenol formaldehyde resin as described in the specification of U.S. Patent No. 4,123,279 may be used together.
• Examples of the alkali-soluble resin having a sulfonamide group include macromolecular compounds obtained by homopolymerizing polymerizable monomers having a sulfonamide group or by copolymerizing the monomer with other polymerizable monomers.
• Examples of the polymerizable monomer having a sulfonamide group include polymerizable monomers comprising a low-molecular compound having, in one molecule thereof, one or more sulfonamide groups -NH-SO 2 - in which at least one hydrogen atom is added to a nitrogen atom and one or more polymerizable unsaturated bonds.
• low-molecular compounds having an acryloyl group, allyl group or vinyloxy group and a substituted or monosubstituted aminosulfonyl group or substituted sulfonylimino group are preferable.
• high molecular compounds containing an active imide group in the molecule thereof are preferable.
• the high molecular compound include high molecular compounds obtained by homopolymerizing a polymerizable monomer comprising a low molecular compound containing at least one active imide group and at least one polymerizable unsaturated bonding in one molecule thereof or copolymerizing such a monomer and other polymerizable monomer.
• N-(p-toluenesulfonyl)methacrylamide and N-(p-toluenesulfonyl)acrylamide for example, may be suitably employed.
• the alkali-soluble resin used in the invention is preferably a polymer compound obtained by polymerizing two or more of a polymerizable monomer having a phenolic hydroxyl group, a polymerizable monomer having a sulfonamide group and a polymerizable monomer having an active amide group.
• a polymerizable monomer having a phenolic hydroxyl group a polymerizable monomer having a sulfonamide group
• a polymerizable monomer having an active amide group There is no particular limitation to the copolymerization ratio of the polymerizable monomers and the combination of the polymerizable monomers.
• the ratio by weight of these components to be compounded is preferably in a range from 50:50 to 5:95 and particularly preferably in a range from 40:60 to 10:90.
• the alkali-soluble resin used in the invention be a polymer compound obtained by copolymerizing another polymerizable monomer in addition to one kind or two or more kinds of polymerizable monomer selected from a polymerizable monomer having a phenolic hydroxyl group, a polymerizable monomer having a sulfonamide group and a polymerizable monomer having an active amide group.
• the copolymerization ratio used in this case is preferably determined so that the monomer imparting alkali-solubility is contained in an amount of 10 mole% or more, and more preferably 20 mole% or more.
• the amount of the copolymerization component derived from the monomer imparting alkali-solubility is less than 10 mole%, alkali-solubility is liable to be insufficient and the development latitude tends to decrease.
• the other polymerizable monomers include the following compounds (m1) to (m12), but the invention is not limited thereto.
• the alkali-soluble resin used in the invention is a homopolymer or a copolymer of a polymerizable monomer having a phenolic hydroxyl group, a polymerizable monomer having a sulfonamide group and a polymerizable monomer having an active imide group
• it preferably has a weight-average molecular weight of 2,000 or more and a number-average molecular weight of 500 or more. More preferably, it has a weight-average molecular weight of from 5,000 to 300,000, a number-average molecular weight of from 800 to 250,000 and a dispersion degree (weight-average molecular weight/number-average molecular weight) of from 1.1 to 10.
• the alkali-soluble resin used in the invention is a phenol-formaldehyde resin or a cresol-aldehyde resin, it particularly preferably has a weight-average molecular weight of from 500 to 20,000 and a number-average molecular weight of from 200 to 10,000.
• the alkali-soluble resin used in the invention is preferably a resin having a phenolic hydroxyl group from the standpoint of being capable of forming strong hydrogen bonding in an unexposed area while readily releasing some of the hydrogen bonds in an exposed area.
• a novolak resin is preferred as the resin having a phenolic hydroxyl group.
• two or more kinds of alkali-soluble resins differing in dissolving rate in an aqueous alkali solution may be used as a mixture, and, in such a case, the mixing ratio thereof may be freely determined.
• an acrylic resin is preferable since it has a low compatibility with the resin having a phenolic hydroxyl group, and an acrylic resin having a sulfonamide group is more preferable.
• the content of the alkali-soluble resin in the upper layer of the invention is preferably from 50 to 98% by mass, based on the total solid content of the upper layer, from the viewpoint of sensitivity and durability of the recording layer.
• the content amount indicates the total amount of the resins.
• an infrared absorber In the planographic printing plate precursor of the invention, an infrared absorber must be added to the upper layer of the recording layer.
• the addition of the infrared absorber renders the recording layer infrared laser-sensitive.
• various dyes known as infrared absorbing dyes may be used without any particular limitations as long as they have an absorption maximum at wavelengths of from 750 nm to 1,400 nm and they absorb light of such wavelengths to generate heat.
• the infrared ray-absorbing dyes favorably used in the invention include commercially available dyes and publicly known dyes described in literature (e.g., "Dye manual", the Society of Synthetic Organic Chemistry, Japan Ed., 1970). Specific examples thereof include azo dyes, metal complex salt azo dyes, pyrazolone azo dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinonimine dyes, methine dyes, cyanine dyes and the like.
• dyes absorbing an infrared light or dyes absorbing a near-infrared light are particularly preferable in the invention, as they are suitable for use together with a laser having a wavelength in the infrared light or near-infrared region.
• Examples of such a dye capable of absorbing infrared light or near infrared light which can be used include cyanine dyes as described in JP-A Nos. 58-125246 , 59-84356 , 59-202829 , and 60-78787 , etc.; methine dyes as described in JP-A Nos. 58-173696 , 58-181690 , and 58-194595 , etc.; naphthoquinone dyes as described in JP-A Nos. 58-112793 , 58-224793 , 59-48187 , 59-73996 , 60-52940 , and 60-63744 , etc.; squarylium dyes as described in JP-A No. 58-112792 , etc.; and cyanine dyes as described in UK Patent No. 434,875 .
• the dyes include infrared-absorbing sensitizers described in U.S. Patent No. 5,156,938 ; arylbenzo(thio)pyrylium salts described in U.S. Patent No. 3,881,924 ; trimethine thiapyrylium salts described in JP-A No. 57-142645 ; pyrylium compounds described in JP-A Nos. 58-181051 , 58-220143 , 59-41363 , 59-84248 , 59-84249 , 59-146063 , and 59-146061 ; cyanine dyes described in JP-A No.
• cyanine dyes particularly preferable among these dyes are cyanine dyes, squalelium dyes, pyrylium salts, nickel/thiolate complexes and indolenine cyanine dyes. Cyanine dyes and indolenine cyanine dyes are even more preferable.
• X 1 represents a hydrogen atom, a halogen atom, -NPh 2 , X 2 -L 1 (wherein X 2 represents an oxygen atom, an nitrogen atom or a sulfur atom, L 1 represents a hydrocarbon group having 1 to 12 carbon atoms, an aromatic cyclic group having a heteroatom, or a hydrocarbon group containing a heteroatom and having 1 to 12 carbon atoms, and the heteroatom referred to herein is N, S, O, a halogen atom, or Se), or a group represented by the following:
• Xa - has the same definition as Za - , which will be described below, and R a represents a substituent selected from a hydrogen atom, an alkyl group, an aryl group, a substituted or unsubstituted amino group, or a halogen atom;
• R 1 and R 2 each independently represents a hydrocarbon group having 1 to 12 carbon atoms, and from the viewpoint of the storage stability of the photosensitive composition of the invention when it is used in a coating solution for forming a recording layer of a planographic printing plate precursor, it is preferable that R 1 and R 2 each independently represents a hydrocarbon group having 2 or more carbon atoms, and more preferably R 1 and R 2 are bonded to each other to form a 5-membered or 6-membered ring.
• Ar 1 and Ar 2 which may be the same or different, each represent an aromatic hydrocarbon group which may have a substituent.
• the aromatic hydrocarbon group include benzene and naphthalene rings.
• the substituent include hydrocarbon groups having 12 or less carbon atoms, halogen atoms, and alkoxy groups having 12 or less carbon atoms.
• Y 1 and Y 2 which may be the same or different, each represents a sulfur atom, or a dialkylmethylene group having 12 or less carbon atoms.
• R 3 and R 4 which may be the same or different, each represents a hydrocarbon group which has 20 or less carbon atoms and may have a substituent.
• substituents include alkoxy groups having 12 or less carbon atoms, a carboxyl group, and a sulfo group.
• R 5 , R 6 , R 7 and R 8 which may be the same or different, each represents a hydrogen atom, or a hydrocarbon group having 12 or less carbon atoms, and since the raw materials thereof can easily be obtained, each preferably represents a hydrogen atom.
• Za - represents a counter anion. It should be noted that when the cyanine dye represented by formula (i) has an anionic substituent in its structure and does not require neutralization of the charge, Za - is not necessary.
• Za - is preferably a halogen ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion or a sulfonate ion, and particularly preferably a perchlorate ion, a hexafluorophosphate ion or an aryl sulfonate ion.
• Examples of the cyanine dyes represented by the formula (i), which can be preferably used in the invention, include those disclosed in paragraphs [0017] to [0019] of JP-A No. 2001-133969 .
• the infrared absorber is contained as an essential component in the upper layer of the recording layer from the viewpoint of sensitivity, it may also be contained in the lower layer.
• an infrared absorber By adding an infrared absorber to the lower layer, it is possible to improve the sensitivity due to local generation of heat in an exposed area.
• a substance having dissolution inhibitability such as a cyanine dye, as an infrared absorber, it is possible to make the lower layer serve as a heat-sensitive recording layer.
• an infrared absorber is added to both the upper and lower layers, the same compound may be used for both layers or alternatively different compounds may be used. Further, such infrared absorbers may by added to the recording layer or alternatively may be added to another layer formed separately from the recording layer.
• Infrared absorbers such as the cyanine dyes provided above as preferable dyes can serve as agents for inhibiting dissolution of the aforementioned alkali-soluble resin through formation of an interaction with the alkali-soluble resin.
• a compound as an infrared absorber other than such compounds having dissolution inhibitability it is desirable to add a dissolution inhibitor mentioned below to the upper layer.
• An addition amount of the infrared absorber is, to a total solid content, in the range of 0.01 to 50 mass percent, preferably in the range of 0.1 to 30 mass percent and particularly preferably in the range of 1.0 to 30 mass percent.
• the addition amount of the infrared absorber is set in the range, excellent sensitivity and excellent uniformity and durability of the upper recording layer can be obtained.
• the infrared absorber may optionally be added also to the lower layer. When adding it to the lower layer, it is desirable to add it in an amount of from 0 to 20% by mass, preferably from 0 to 10% by mass, and particularly preferably from 0 to 5% by mass, based on the total solid content of the lower layer. In the case where the infrared absorber is added to the lower layer, if an infrared absorber having dissolution inhibitability is used, the solubility of the lower layer is lowered. On the other hand, since the infrared absorber generates heat on exposure to infrared laser, the solubility of the lower layer is expected to increase due to the heat. Therefore, the kind of compound to be added and the amount thereof should be determined with consideration of the balance between these characteristics.
• a development inhibitor be contained in the upper layer of the invention for enhancing inhibition (solubilization inhibiting function).
• the development inhibitor used in the invention is not particularly limited insofar as it causes an interaction with the alkali-soluble resin such that the solubility of the alkali-soluble resin in a developer is substantially lowered in an unexposed area, and in an exposed area, the alkali-soluble resin exhibits a reduced interaction and is soluble in the developer.
• a quaternary ammonium salt and a polyethylene glycol-type compound are preferably used.
• the quaternary ammonium salt is not limited to specific kinds, and examples thereof include tetraalkylammonium, trialkylarylammonium, dialkyldiarylammonium, alkyltriarylammonium, tetaraarylammonium, cyclic ammonium, and bicyclic ammonium salts.
• tetrabutylammonium bromide examples include tetrabutylammonium bromide, tetrapentylammonium bromide, tetrahexylammonium bromide, tetraoctylammonium bromide, tetralaurylammonium bromide, tetraphenylammonium bromide, tetranaphthylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium iodide, tetrastearylammonium bromide, lauryltrimethylammonium bromide, stearyltrimethylammonium bromide, behenyltrimethylammonium bromide, lauryltriethylammonium bromide, phenyltrimethylammonium bromide, 3-trifluoromethylphenyltrimethylammonium bromide, benzyltrimethylammonium
• An addition amount of the quarternary ammonium salt is, to a total solid content of the upper layer, preferably in the range of 0.1 to 50 mass percent and more preferably in the range of 1 to 30 mass percent.
• the addition amount of quarternary ammonium salt is set in the foregoing range, a development suppression effect can be made larger and the film forming properties can be made excellent.
• the polyethylene glycol type compound is not limited to specific kinds, and may be a compound having a structure represented by the following general formula (ii): R 1 - ⁇ -O-(R 3 -O-) m -R 2 ⁇ n formula (ii) wherein R 1 represents a polyhydric alcohol residue or polyhydric phenol residue; R 2 represents a hydrogen atom, or an alkyl, alkenyl, alkynyl, alkyloyl, aryl or aryloyl group which may each have a substituent and each have 1 to 25 carbon atoms; R 3 represents an alkylene group which may have a substituent; m and n are an integer of 10 or more and an integer of 1 or more and 4 or less, respectively, on average.
• polyethylene glycol type compound represented by the general formula (ii) examples include polyethylene glycols, polypropylene glycols, polyethylene glycol alkyl ethers, polypropylene glycol alkyl ethers, polyethylene glycol aryl ethers, polypropylene glycol aryl ethers, polyethylene glycol alkylaryl ethers, polypropylene glycol alkylaryl ethers, polyethylene glycol glycerin esters, polypropylene glycol glycerin esters, polyethylene sorbitol esters, polypropylene glycol sorbitol esters, polyethylene glycol aliphatic acid esters, polypropylene glycol aliphatic acid esters, polyethylene glycolized ethylenediamines, polypropylene glycolized ethylenediamines, polyethylene glycolized diethylenetriamine, and polypropylene glycolized diethylenetriamines.
• polyethylene glycol 1000 polyethylene glycol 2000, polyethylene glycol 4000, polyethylene glycol 10000, polyethylene glycol 20000, polyethylene glycol 5000, polyethylene glycol 100000, polyethylene glycol 200000, polyethylene glycol 500000, polypropylene glycol 1500, polypropylene glycol 3000, polypropylene glycol 4000, polyethylene glycol methyl ether, polyethylene glycol ethyl ether, polyethylene glycol phenyl ether, polyethylene glycol dimethyl ether, polyethylene glycol diethyl ether, polyethylene glycol diphenyl ether, polyethylene glycol lauryl ether, polyethylene glycol dilauryl ether, polyethylene glycol nonyl ether, polyethylene glycol cetyl ether, polyethylene glycol stearyl ether, polyethylene glycol distearyl ether, polyethylene glycol behenyl ether, polyethylene glycol dibehenyl ether, polypropylene glycol methyl ether, polypropylene glycol
• the amount of the polyethylene glycol compound added is preferably from 0.1 to 50% by mass, and more preferably from 1 to 30% by mass, based on the total solid content of the upper layer, from the viewpoint of development inhibition effect and image formability.
• X 1 , X 2 , X 3 and X 4 may be the same or different, and each represent a bivalent nonmetallic atom or nonmetallic atomic group which constitutes a part of the ring. These may each independently have a substituent. It is preferable that at least one of X 1 , X 2 and X 3 in the general formula (L-I), and at least one of X 1 , X 2 , X 3 and X 4 in the general formula (L-II) each have an electron withdrawing substituent or a substituent substituted with an electron withdrawing group.
• the nonmetallic atom or nonmetallic atomic group is preferably an atom or atomic group selected from methylene, sulfinyl, carbonyl, thiocarbonyl, and sulfonyl groups, and sulfur, oxygen and selenium atoms, and is more preferably an atomic group selected from methylene, carbonyl and sulfonyl groups.
• the electron withdrawing substituent (or group) referred to in the invention means a group having a positive Hammett substituent constant ⁇ p.
• the Hammett substituent constant the following can be referred to: Journal of Medicinal Chemistry, 1973, Vol. 16, No. 11, 1207-1216 , and so on.
• Examples of the electron withdrawing group having a positive Hammett substituent constant ⁇ p include halogen atoms (such as a fluorine atom ( ⁇ p value: 0.06), a chlorine atom ( ⁇ p value: 0.23), a bromine atom ( ⁇ p value: 0.23) and a iodine atom ( ⁇ p value: 0.18)); trihaloalkyl groups (such as tribromomethyl ( ⁇ p value: 0.29), trichloromethyl ( ⁇ p value: 0.33), and trifluoromethyl ( ⁇ p value: 0.54)); a cyano group ( ⁇ p value: 0.66); a nitro group ( ⁇ p value: 0.78); aliphatic, aryl or heterocyclic sulfonyl groups (such as methanesulfonyl ( ⁇ p value: 0.72)); aliphatic, aryl or heterocyclic acyl groups (such as acetyl ( ⁇ p value: 0.50) and benzoyl ( ⁇ p
• the electron withdrawing group include an amide group, an azo group, a nitro group, fluoroalkyl groups having 1 to 5 carbon atoms, a nitrile group, alkoxycarbonyl groups having 1 to 5 carbon atoms, acyl groups having 1 to 5 carbon atoms, alkylsulfonyl groups having 1 to 9 carbon atoms, arylsulfonyl groups having 6 to 9 carbon atoms, alkylsulfinyl groups having 1 to 9 carbon atoms, arylsulfinyl groups having 6 to 9 carbon atoms, arylcarbonyl groups having 6 to 9 carbon atoms, thiocarbonyl groups, fluorine-containing alkyl groups having 1 to 9 carbon atoms, fluorine-containing aryl groups having 6 to 9 carbon atoms, fluorine-containing allyl groups having 3 to 9 carbon atoms, an oxo group, and halogen atoms.
• the electron withdrawing group include a nitro group, fluoroalkyl groups having 1 to 5 carbon atoms, a nitrile group, alkoxycarbonyl groups having 1 to 5 carbon atoms, acyl groups having 1 to 5 carbon atoms, arylsulfonyl groups having 6 to 9 carbon atoms, arylcarbonyl groups having 6 to 9 carbon atoms, an oxo group, and halogen atoms.
• the lactone compounds in the invention may be used alone or in combination of two or more thereof.
• the ratio between the added amounts of the these compounds may be arbitrary set if the total added amount of the compounds is within the above-mentioned range.
• a substance that is thermally decomposable and that substantially lowers the solubility of the alkali-soluble resin in an undecomposed state such as onium salts, o-quinonediazide compounds, aromatic sulfone compounds and aromatic sulfonate compounds, in order to improve the solution-inhibition of image areas to a developer.
• onium salts used in the invention include diazonium salts, ammonium salts, phosphonium salts, iodonium salts, sulfonium salts, selenonium salts, and arseninum salts.
• Particularly preferable examples thereof include diazonium salts described in S. I. Schlesinger, Photogr. Sci. Eng., 18, 387 (1974 ), T. S. Bal et al., Polymer, 21, 423 (1980 ), and JP-A No. 5-158230 ; ammonium salts described in USP Nos. 4,069,055 and 4,069,056 , and JP-A No. 3-140140 ; phosphonium salts described in D. C. Necker et al, Macromolecules, 17, 2468 (1984 ), C. S. Wen et al., The, Proc. Conf. Rad. Curing ASIA p.478, Tokyo, Oct: (1988) , and USP Nos.
• diazonium salts are particularly preferable.
• Particularly preferable examples of the diazonium salts include salts described in JP-A No. 5-158230 .
• Examples of the counter ion for the onium salt include tetrafluoroboric acid, hexafluorophosphoric acid, triisopropylnaphthalenesulfonic acid, 5-nitro-o-toluenesulfonic acid, 5-sulfosalicylic acid, 2,5-dimethylbenzenesulfonic acid, 2,4,6-trimethylbenzenesulfonic acid, 2-nitrobenzenesulfonic acid, 3-chlorobenzenesulfonic acid, 3-bromobenzenesulfonic acid, 2-fluorocaprylnaphthalenesulfonic acid, dodecylbenzenesulfonic acid, 1-naphthol-5-sulfonic acid, 2-methoxy-4-hydroxy-5-benzoyl-benzenesulfonic acid, and paratoluenesulfonic acid ions.
• hexafluorophosphoric acid and alkylaromatic sulfonic acids such as triisopropylnaphthalenesulfonic acid and 2,5-dimethylbenzenesulfonic acid, are particularly preferred.
• the quinonediazide compounds are preferably o-quinonediazide compounds.
• the o-quinonediazide compounds are compounds which each have at least one o-quinonediazide group and each have alkali-solubility increased by being thermally decomposed, and which may have various structures.
• the o-quinonediazide compounds assist the dissolution of the upper layer by both of the effect that the compounds are thermally decomposed so that their inhibition for the developing inhibitor is lost and the effect that the o-quinonediazide compounds themselves change to alkali-soluble substances.
• Such an o-quinonediazide compound may be, for example, a compound described in J Cohser "Light-Sensitive Systems” (John & Wiley & Sons. Inc.), pp. 339-352 .
• Particularly preferable is a sulfonic acid ester or sulfonamide of o-quinonediazide, which is obtained by reacting the o-quinonediazide with an aromatic polyhydroxy compound or aromatic amino compound.
• esters made from benzoquinone-(1,2)-diazidesulfonic acid chloride or naphthoquinone-(1,2)-diazide-5-sulfonic acid chloride and pyrogallol-acetone resin described in Japanese Patent Application Laid-Open ( JP-B) No. 43-28403 ; an ester made from benzoquinone-(1,2)-diazidesulfonic acid chloride or naphthoquinone-(1,2)-diazide-5-sulfonic acid chloride and phenol-formaldehyde resin, described in USP Nos. 3,046,120 and 3,188,210 .
• an ester made from naphthoquinone-(1,2)-diazide-4-sulfonic acid chloride and phenol formaldehyde resin or cresol-formaldehyde resin and an ester made from naphthoquinone-(1,2)-diazide-4-sulfonic acid chloride and pyrogallol-acetone resin.
• Other useful o-quinonediazide compounds are reported and disclosed in many examined or unexamined patent documents, for example, JP-A Nos. 47-5303 , 48-63802 , 48-63803 , 48-96575 , 49-38701 and 48-13354 , JP-B Nos.
• the added amount of the o-quinonediazide compound is preferably from 1 to 50% by mass, more preferably from 5 to 30% by mass, even more preferably from 10 to 30% by mass of all solid contents of the upper layer.
• the above-mentioned o-quinonediazide compounds may be used alone or in a mixture form.
• An alkali-soluble resin that has been at least partially esterified, as disclosed in JP-A No. 11-288089 may also be included.
• a polymer containing, as a polymerization component, a (meth)acrylate monomer having two or three perfluoroalkyl groups having from 3 to 20 carbon atoms in the molecule as disclosed in JP-A No. 2000-187318 .
• the amount of the polymer added is preferably from 0.1 to 10% by mass, and more preferably from 0.5 to 5% by mass, based on the total solid content of the upper layer.
• additives may further be added, depending on necessity, in addition to the aforementioned essential components, as long as the effect of the invention is not thereby impaired. Examples of the additives are shown below, and these may be added only to the lower layer, only to the upper layer, or to both layers.
• an acid anhydride, a phenol compound and an organic acid may be added to the upper layer and/or the lower layer of the recording layer of the invention.
• cyclic acid anhydrides are preferred.
• Specific examples of the cyclic acid anhydrides include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, 3,6-endoxy-tetrahydrophthalic anhydride, tetrachlorophthalic anhydride, maleic anhydride, chloromaleic anhydride, a-phenylmaleic anhydride, succinic anhydride and pyromellitic anhydride as described in U.S. Patent No. 4,115,128 .
• Examples of acyclic acid anhydrides include acetic anhydride.
• phenols examples include, bisphenol A, 2,2'-bishydroxysulfone, 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.
• examples of the organic acids include the sulfonic acids, sulfinic acids, alkylsulfuric acids, phosphonic acids, phosphoric acid esters and carboxylic acids described in JP-A Nos. 60-88942 and 2-96755 , and others, and specific examples thereof include p-toluenesulfonic acid, dodecylbenzenesulfonic acid, p-toluenesulfinic acid, ethylsulfuric acid, phenylphosphonic acid, phenylphosphinic acid, phenyl phosphate, diphenyl phosphate, benzoic acid, isophthalic acid, adipic acid, p-toluyl acid, 3,4-dimethoxybenzoic acid, phthalic acid, terephthalic acid, 4-cyclohexene-1,2-dicarboxylic acid, erucic acid, lauric acid, n-undecane acid, ascorbic acid
• the content of the acid anhydride, the phenol compound and the organic acid in the lower layer or the upper layer is preferably from 0.05 to 20% by mass, more preferably from 0.1 to 15% by mass, and particularly preferably from 0.1 to 10% by mass, based on the respective total solid content of the lower layer or the upper layer.
• the upper layer and/or the lower layer of the recording layer of the invention may contain a nonionic surfactant such as those disclosed in JP-A Nos. 62-251740 and 3-208514 , an amphoteric surfactant such as those disclosed in JP-A Nos. 59-121044 and 4-13149 , a siloxane compound such as those disclosed in EP-A No. 950517 , and a copolymer of fluorine-containing monomers as disclosed in JP-A Nos. 62-170950 and 11-288093 and Japanese Patent Application Laid-Open No. 2003-057820 .
• a nonionic surfactant such as those disclosed in JP-A Nos. 62-251740 and 3-208514
• an amphoteric surfactant such as those disclosed in JP-A Nos. 59-121044 and 4-13149
• a siloxane compound such as those disclosed in EP-A No. 950517
• nonionic surfactant examples include sorbitan tristearate, sorbitan monopalmitate, sorbitan trioleate, monoglyceride stearate, and polyoxyethylene nonyl phenyl ether.
• amphoteric surfactant examples include alkyldi(aminoethyl)glycine, alkylpolyaminoethylglycine hydrochloride, 2-alkyl-N-carboxyethyl-N-hydroxyethylimidazolium betaine, and N-tetradecyl-N,N-betaine type surfactants (trade name: "Amorgen K", manufactured by Daiichi Kogyo Co., Ltd., and others).
• the siloxane compound is preferably a block copolymer of dimethylsiloxane and polyalkylene oxide.
• Specific examples thereof include polyalkylene oxide modified silicones (trade names: DBE-224, DBE-621, DBE-712, DBP-732 and DBP-534 (trade name, manufactured by Chisso Corp.), and Tego Glide 100 (trade name, manufactured by Tego Co. in Germany)).
• the content of the nonionic surfactant and the amphoteric surfactant in the lower layer or the upper layer is preferably from 0.01 to 15% by mass, more preferably from 0.1 to 5% by mass, and even more preferably from 0.05 to 0.5% by mass, based on the total solid content in the lower layer or the upper layer, respectively.
• the upper layer and/or the lower layer of the recording layer of the invention may contain a printing-out agent for obtaining visible images immediately after heating by exposure, and a dye and a pigment may be added as an image coloring agent.
• a typical example of the printing-out agent is a combination of a compound which releases an acid by being heated by exposure to light (optically acid-releasing agent) with an organic dye which can form a salt. Specific examples thereof include combinations of o-naphthoquinonediazide-4-sulfonic acid halogenide with a salt-formable organic dye, described in JP-A Nos. 50-36209 and 53-8128 ; and combinations of a trihalomethyl compound with a salt-formable organic dye, described in JP-A Nos.
• the trihalomethyl compound is an oxazole type compound or a triazine type compound. Either of these compounds are excellent in stability over time and can give vivid printed-out images.
• the image coloring agent may be the above-mentioned salt-formable organic dye or some other dye than the salt-formable organic dye, and is preferably an oil-soluble dye or a basic dye. Specific examples thereof include Oil Yellow #101, Oil Yellow #103, Oil Pink #312, Oil Green BG, Oil Blue BOS, Oil Blue #603, Oil Black BY, Oil Black BS, and Oil Black T-505 (trade name, manufactured by Orient Chemical Industries Ltd.), Victoria Pure Blue, Crystal Violet Lactone, Crystal Violet (CI42555), Methyl Violet (CI42535), Ethyl Violet, Rhodamine B (CI145170B), Malachite Green (CI42000), and methylene Blue (CI52015). Dyes described in JP-A No.
• 62-293247 are particularly preferable. These dyes may be added to the lower layer or the upper layer in an amount of from 0.01 to 10% by mass, and preferably from 0.1 to 3% by mass, based on the total solid content in the lower layer or the upper layer, respectively.
• the upper layer and/or the lower layer of the recording layer of the invention may contain a plasticizer for imparting flexibility to a coating film.
• a plasticizer for imparting flexibility to a coating film.
• examples thereof include butylphthalyl, polyethylene glycol, tributyl citrate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, tricresyl phosphate, tributyl phosphate, trioctyl phosphate, tetrahydrofurfuryl oleate and an oligomer or a polymer of acrylic acid or methacrylic acid.
• a compound that lowers a static friction coefficient of the surface may be added in order to impart scratch resistance.
• the compound include compounds having an ester of a long-chain alkyl carboxylic acid as disclosed in U.S. Patent No. 6,117,913 and Japanese Patent Application Laid-Open No. 2004-012770 .
• the amount of the wax added is preferably from 0.1 to 10% by mass, and more preferably from 0.5 to 5% by mass, based on the weight of the upper layer.
• the lower layer and the upper layer of the recording layer of the planographic printing plate precursor according to the invention may be formed by dissolving the aforementioned components in a solvent, and applying a coating on an appropriate support.
• the solvent that may be used herein include ethylene dichloride, cyclohexanone, methyl ethyl ketone, methanol, ethanol, propanol, ethylene glycol monomethyl ether, 1-methoxy-2-propanol, 2-methoxyethyl acetate, 1-methoxy-2-propyl acetate, dimethoxyethane, methyl lactate, ethyl lactate, N,N-dimethylacetamide, N,N-dimethylformamide, tetramethylurea, N-methylpyrrolidone, dimethylsulfoxide, sulfolane, ⁇ -butyrolactone and toluene, but the invention is not limited to these.
• These solvents may be used independently or in combination of two or
• the method for forming the two layers separately include a method that utilizes a difference in solubility in the solvent between the components contained in the lower layer and the components contained in the upper layer, and a method in which the upper layer is coated and then quickly dried to remove the solvent. These methods will be described below, but the method for coating the two layers separately is not limited thereto.
• a solvent system that does not dissolve all the components contained in the lower layer is employed for coating the coating solution for the upper layer.
• the two layers can clearly be formed as separate coated films even when conducting a double-layer coating.
• components that are insoluble in a solvent capable of dissolving the alkali-soluble resin component of the upper layer such as methyl ethyl ketone and 1-methoxy-2-propanol solvents, are employed as components of the lower layer, and the lower layer is coated and dried by using a solvent system that dissolves the components of the lower layer.
• the components of the upper layer containing the alkali-soluble resin as a main component are dissolved, coated and dried by using a solvent that does not dissolve the lower layer, such as methyl ethyl ketone and 1-methoxy-2-propanol, whereby the two layers are separately formed.
• a solvent that does not dissolve the lower layer such as methyl ethyl ketone and 1-methoxy-2-propanol
• Examples of the method of quickly drying the solvent after coating the upper layer include a method of blowing high-pressure air from a slit nozzle disposed substantially perpendicular to the running direction of the web, a method of applying heat energy to the lower surface of the web through a roll (heating roll) to which a heating medium, such as steam, is internally fed, and a method combining these methods.
• the lower layer and the upper layer may be partially admixed to such an extent that the effect of the invention remains sufficiently exhibited.
• the partial admixture can be achieved by controlling the difference in solubility in solvent in the method utilizing the difference in solubility between the layers or controlling the drying rate in the method in which the upper layer is coated and then quickly dried to remove the solvent.
• the concentration of the components other than the solvent (total solid content including the additives) in the lower layer and upper layer coating solutions to be coated on the support is preferably from 1 to 50% by mass, respectively.
• There are various possible methods for coating the coating composition on the support examples thereof include bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating and roll coating.
• the coating method is preferably a non-contact coating method.
• Bar coater coating which is generally used for solvent-based coating, could be used in the invention, although bar coater coating is a contact coating method. However, when bar coater is used, it is preferable that the bar coater coating is effected by forward rotation in order to prevent damage to the lower layer.
• a dry coated amount of a lower layer component coated on a support of a planographic printing plate precursor of the invention is preferably in the range of 0.5 to 4.0 g/m 2 and more preferably in the range of 0.6 to 2.5 g/m 2 .
• the drying durability, image reproducibility and sensitivity can be made excellent.
• a dry coated amount of the upper layer component is preferably in the range of 0.05 to 1.0 g/m 2 and more preferably in the range of 0.08 to 0.7 g/m 2 .
• the dry coated amount is set in the foregoing range, the development latitude, scratch resistance and sensitivity can be made excellent.
• a dry coated amount in combination of the upper layer and lower layer is preferably in the range of 0.6 to 4.0 g/m 2 and more preferably in the range of 0.7 to 2.5 g/m 2 .
• the combined dry coated amount is set in the foregoing range, the printing durability, image reproducibility and sensitivity can be made excellent.
• the support which is used in the planographic printing plate precursors of the invention may be any plate-form product that has necessary strength and endurance and is dimensionally stable.
• Examples thereof include a paper sheet; a paper sheet on which a plastic (such as polyethylene, polypropylene, or polystyrene) is laminated; a metal plate (such as an aluminum, zinc, or copper plate), a plastic film (such as a cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose lactate, cellulose acetate lactate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, or polyvinyl acetal film); and a paper or plastic film on which a metal as described above is laminated or vapor-deposited.
• a plastic such as polyethylene, polypropylene, or polystyrene
• a polyester film or an aluminum plate is preferable in the invention.
• An aluminum plate is particularly preferable since the plate is good in dimensional stability and relatively inexpensive.
• Preferable examples of the aluminum plate include a pure aluminum plate, and alloy plates comprising aluminum as the main component and a small amount of different elements.
• a plastic film on which aluminum is laminated or vapor-deposited may be used.
• the different elements contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. The content by percentage of the different elements in the alloy is at most 10% by mass.
• the aluminum plate used in the invention may be any aluminum plate that has been known or used hitherto.
• the thickness of the aluminum plate used in the invention is generally from about 0.1 to 0.6 mm, preferably from 0.15 to 0.4 mm, and more preferably from 0.2 to 0.3 mm.
• the aluminum plate may be subjected, depending on necessity, to a surface treatment, such as a surface roughening treatment and an anodic oxidation treatment.
• a surface treatment such as a surface roughening treatment and an anodic oxidation treatment.
• the surface treatment will be described below.
• the plate is subjected to degreasing treatment with a surfactant, an organic solvent, an aqueous alkaline solution or the like if desired, in order to remove rolling oil on the surface.
• the roughening treatment of the aluminum plate surface is performed by any one of various methods, for example, by a mechanically surface-roughening method, or a method of dissolving and roughening the surface electrochemically, or a method of dissolving the surface selectively in a chemical manner.
• the mechanically surface-roughening method which can be used may be a known method, such as a ball polishing method, a brush polishing method, a blast polishing method or a buff polishing method.
• the electrochemically surface-roughening method may be a method of performing surface-roughening in a hydrochloric acid or nitric acid electrolyte by use of alternating current or direct current. As disclosed in JP-A No. 54-63902 , a combination of the two may be used.
• the aluminum plate the surface of which is roughened as described above is subjected to alkali-etching treatment and neutralizing treatment if necessary.
• the aluminum plate is subjected to anodizing treatment if desired, in order to improve the water holding ability or wear resistance of the surface.
• the electrolyte used in the anodizing treatment of the aluminum plate is any one selected from various electrolytes which can make a porous oxide film. There is generally used sulfuric acid, phosphoric acid, oxalic acid, chromic acid, or a mixed acid thereof. The concentration of the electrolyte may be appropriately decided dependently on the kind of the electrolyte.
• Conditions for the anodizing treatment cannot be specified without reservation since the conditions vary dependently on the used electrolyte.
• the following conditions are generally suitable: an electrolyte concentration of 1 to 80% by mass, a solution temperature of 5 to 70°C, a current density of 5 to 60 A/dm 2 , a voltage of 1 to 100 V, and an electrolyzing time of 10 seconds to 5 minutes. If the amount of the anodic oxide film is less than 1.0 g/m 2 , the printing durability is insufficient or non-image areas of the planographic printing plate are easily injured so that the so-called "injury stains", resulting from ink adhering to injured portions at the time of printing, are easily generated. If necessary, the aluminum surface is subjected to treatment for hydrophilicity after the anodizing treatment.
• the treatment for hydrophilicity which can be used in the invention may be an alkali metal silicate (for example, aqueous sodium silicate solution) method, as disclosed in USP Nos. 2,714,066 , 3,181,461 , 3,280,734 , and 3,902,734 .
• the support is subjected to immersing treatment or electrolyzing treatment with aqueous sodium silicate solution.
• there may be used a method of treating the support with potassium fluorozirconate disclosed in JP-B No. 36-22063 or with polyvinyl phosphonic acid, as disclosed in USP Nos. 3,276,868 , 4,153,461 , and 4,689,272 .
• an undercoat layer may be provided, as necessary, between the support and the recording layer.
• various organic compounds may be used. Examples thereof include carboxymethylcellulose, dextrin, gum arabic, phosphonic acids having an amino group such as 2-aminoethylphosphonic acid, organic phosphonic acids such as phenylphosphonic acid, naphthylphosphonic acid, alkylphosphonic acid, glycerophosphonic acid, methylenediphosphonic acid and ethylenediphosphonic acid, each of which may have a substituent, organic phosphoric acids such as phenylphosphoric acid, naphthylphosphoric acid, alkylphosphoric acid and glycerophosphoric acid, each of which may have a substituent, organic phosphinic acids such as phenylphosphinic acid, naphthylphosphinic acid, alkylphosphinic acid, and glycerophosphinic acid, each of which are examples of organic phosphinic acids such as phenylpho
• This organic undercoat layer can be formed by the following method: a method of dissolving the above-mentioned organic compound into water, an organic solvent such as methanol, ethanol or methyl ethyl ketone, or a mixed solvent thereof to prepare a solution, applying the solution onto an aluminum plate, and drying the solution to form the undercoat layer; or a method of dissolving the above-mentioned organic compound into water, an organic solvent such as methanol, ethanol or methyl ethyl ketone, or a mixed solvent thereof to prepare a solution, dipping an aluminum plate into the solution to cause the plate to adsorb the organic compound, washing the plate with water or the like, and then drying the plate to form the undercoat layer.
• the solution of the organic compound having a concentration of 0.005 to 10% by mass can be applied by various methods.
• the concentration of the organic compound in the solution is from 0.01 to 20% by mass, preferably from 0.05 to 5% by mass
• the dipping temperature is from 20 to 90°C, preferably from 25 to 50°C
• the dipping time is from 0.1 second to 20 minutes, preferably from 2 seconds to 1 minute.
• the pH of the solution used in this method can be adjusted into the range of 1 to 12 with a basic material such as ammonia, triethylamine or potassium hydroxide, or an acidic material such as hydrochloric acid or phosphoric acid.
• a yellow dye can be added to the solution in order to improve the reproducibility of the tone of the image recording material.
• the coated amount of the organic undercoat layer is appropriately from 2 to 200 mg/m 2 , and preferably from 5 to 100 mg/m 2 . In cases where the coated amount is within the range, sufficient printing durability and sufficient developablity would be obtained.
• the planographic printing plate precursor thus produced is exposed imagewise and then subjected to a developing treatment.
• Examples of the light source of the active rays used for image exposure of the planographic printing plate precursor of the invention include a mercury lamp, metal halide lamp, xenon lamp, chemical lamp and carbon arc lamp.
• Examples of the radioactive rays used for image exposure of the planographic printing plate precursor of the invention include electron rays, X-rays, ion beams and far infrared radiation. G-rays, i-rays, Deep-UV light and high-density energy beams (laser beams) may also be used.
• Examples of the laser beam include helium ⁇ neon laser, argon laser, krypton laser, helium ⁇ cadmium laser and KrF excimer laser.
• the planographic printing plate precursor is particularly preferably exposed to light from a light source having an emitting wavelength in the near-infrared region to the infrared region. Examples of such a light source include solid laser or semiconductor laser.
• a conventionally known alkali developer which contains an organic compound having a buffering activity and a base as major ingredients and which is substantially free of silicon dioxide can be used as a developer and also as a replenisher for the development of the planographic printing plate precursor of the invention.
• a developer is hereinafter referred to as a "non-silicate developer.”
• substantially means that the presence of unavoidable impurities and a minor amount of silicate dioxide as a side product is acceptable.
• the "non-silicate developer" used in the development of the planographic printing plate precursor of the invention is a solution containing a base and an organic compound having a buffering activity as main components as described above.
• the organic compound having a buffering activity include sugars which are described as compounds providing a buffer action in JP-A No. 8-220775 (particularly those represented by formulae (I) or (II)), oximes (particularly those represented by formula (III)), phenols (particularly those represented by formula (IV)) and fluorinated alcohols (particularly those represented by formula (V)).
• the sugars represented by formulae (I) and (II) and the phenols represented by formula (V) are preferred.
• non-reducing sugars such as saccharose, and sulfosalysilic acid are particularly preferred.
• the non-reducing sugars include trehalose-type oligosaccharides in which reducing groups are bonded to each other, glycosides in which a reducing group of a sugar and a non-sugar compound are bonded to each other, and sugar alcohols obtained by reducing sugars by hydrogenation. Any of these organic compounds can be used suitably for the invention.
• Examples of the trehalose type oligosaccharides include saccharose and trehalose.
• Examples of the glucosides include alkylglucosides, phenolglucosides, and mustard seed oil glucoside.
• Examples of the sugar alcohols include D, L-arabite, ribitol, xylitol, D, L-sorbitos, D, L-mannitol, D, L-iditol, D, L-talitol, dulcitol, and allodulcitol.
• maltitol obtained by hydrogenating a disaccharide
• a reductant obtained by hydrogenating an oligosaccharide i.e., reduced starch syrup
• sugar alcohol and saccharose are more preferable.
• D-sorbitol, saccharose, and reduced starch syrup are even more preferable since they have buffer effect within an appropriate pH range and are inexpensive.
• These nonreducing sugars may be used alone or in combination of two or more thereof
• the percentage thereof in the developer is preferably from 0.1 to 30% by mass, more preferably from 1 to 20% by mass.
• an appropriate conventional alkali agent may be combined, as a base, with the above-described organic compounds having buffering effect.
• the alkali agent include inorganic alkali agents such as sodium hydroxide, potassium hydroxide, lithium hydroxide, trisodium phosphate, tripotassium phosphate, triammonium phosphate, disodium phosphate, dipotassium phosphate, diammonium phosphate, sodium carbonate, potassium carbonate, ammonium carbonate, sodium hydrogencarbonate, potassium hydrogencarbonate, ammonium hydrogencarbonate, sodium borate, potassium borate, ammonium borate, potassium citrate, tripotassium citrate and sodium citrate; and organic alkali agents such as monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine,
• sodium hydroxide and potassium hydroxide are preferred, because the pH can be regulated across a wide pH range by adjusting the amount added relative to the non-reducing sugar.
• Trisodium phosphate, tripotassium phosphate, sodium carbonate and potassium carbonate are also preferred because they inherently possess a buffering activity.
• a conventionally employed replenishing system is known to be able to process a large amount of planographic printing plates without exchanging the developer in the tank for a long period of time by adding, to a developer, an aqueous solution (replenisher) having an alkali strength higher than that of the developer.
• This replenishing system is suitably used also in the invention.
• the developer and the replenisher may contain a surfactant or an organic solvent for such purposes as increasing or decreasing developability, dispersing the sludge resulting from development, and increasing the ink affinity of the image areas of a printing plate.
• preferable surfactants include anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants.
• the developer and the replenisher may contain a reducing agent such as hydroquinone, resorcinol, and sodium and potassium salts of inorganic acids such as sulfurous acid and hydrogensulfurous acid, or, further, an organic carboxylic acid, a defoaming agent or a water softener.
• a reducing agent such as hydroquinone, resorcinol, and sodium and potassium salts of inorganic acids such as sulfurous acid and hydrogensulfurous acid, or, further, an organic carboxylic acid, a defoaming agent or a water softener.
• the printing plate developed with the developer and replenisher described above is subsequently subjected to treatments with washing water, a rinse solution containing a surfactant and other components, and a desensitizing solution containing gum arabic and a starch derivative.
• a post treatment for the planographic printing plate precursor of the invention various combinations of the aforementioned treatments may be employed.
• automatic developing machines for printing plate precursors have been widely used in order to rationalize and standardize plate-making processes in the plate-making and printing industries.
• These automatic developing machines are generally made up of a developing section and a post-processing section, and include a device for carrying printing plate precursors, various treating solution tanks, and spray devices.
• These machines are machines for spraying respective treating solutions, which are pumped up, onto an exposed printing plate through spray nozzles, for development, while the printing plate is transported horizontally.
• a method has also attracted attention in which a printing plate precursor is immersed in treating solution tanks filled with treating solutions and conveyed by means of in-liquid guide rolls.
• Such automatic processing can be performed while replenishers are being replenished into the respective treating solutions in accordance with the amounts to be treated, operating times, and other factors.
• a so-called use-and-dispose processing manner can also be used, in which treatments are conducted with treating solutions which in practice have yet been used.
• unnecessary image portions for example, a film edge mark of an original picture film
• unnecessary image portions can be erased.
• the erasing is preferably performed by applying an erasing solution to unnecessary image portions, leaving the printing plate as it is for a given time, and washing the plate with water, as described in, for example, JP-B No. 2-13293 .
• This erasing may also be performed by a method of radiating active rays introduced through an optical fiber onto the unnecessary image portions, and then developing the plate, as described in JP-A No. 59-174842 .
• planographic printing plate obtained as described above is, if desired, coated with a desensitizing gum, and subsequently the plate can be made available for a printing step.
• baking treatment is applied to the planographic printing plate.
• the planographic printing plate is subjected to the baking treatment, it is preferable that before the baking treatment takes place the plate is treated with a surface-adjusting solution as described in JP-B No. 61-2518 , or JP-A Nos. 55-28062 , 62-31859 or 61-159655 .
• This method of treatment is, for example, a method of applying the surface-adjusting solution onto the planographic printing plate with a sponge or absorbent cotton infiltrated with the solution, a method of immersing the planographic printing plate in a vat filled with the surface-adjusting solution, or a method of applying the surface-adjusting solution to the planographic printing plate with an automatic coater.
• a method of applying the surface-adjusting solution onto the planographic printing plate with a sponge or absorbent cotton infiltrated with the solution a method of immersing the planographic printing plate in a vat filled with the surface-adjusting solution
• a method of applying the surface-adjusting solution to the planographic printing plate with an automatic coater In a case where after application the amount of solution applied is made uniform with a squeegee or a squeegee roller, a better result can be obtained.
• the amount of surface-adjusting solution applied is suitably from 0.03 to 0.8 g/m 2 (dry mass).
• the planographic printing plate onto which the surface-adjusting solution is applied can be dried, and then the plate is heated to a high temperature by means of a baking processor (for example, a baking processor (BP-1300) sold by Fuji Photo Film Co., Ltd.) or the like.
• a baking processor for example, a baking processor (BP-1300) sold by Fuji Photo Film Co., Ltd.
• the heating temperature and the heating time which depend on the kind of components forming the image, are preferably from 180 to 300°C and from 1 to 20 minutes, respectively.
• a planographic printing plate subjected to baking treatment can be subjected to treatments which have been conventionally conducted, such as a water-washing treatment and gum coating.
• treatments which have been conventionally conducted such as a water-washing treatment and gum coating.
• the so-called desensitizing treatment for example, gum coating
• the planographic printing plate obtained as a result of such treatments is applied to an offset printing machine or to some other printing machine, and is used for printing on a great number of sheets.
• the diazonium solution was dropped in the phenolic polymer solution over 10 min, followed by agitating for 30 min at 0°C and for 2 hr at room temperature. A generated mixture was continuously added to 1.5 liter of ice water over 30 min under agitation. A polymer was precipitated from an aqueous medium and a precipitate was isolated by filtration. The isolated matter was washed with water, followed by drying at 45°C, and thereby a desired particular polymer compound (1) was obtained.
• a 0.24 mm-thick aluminum sheet (aluminum alloy containing 0.06% by weight of Si, 0.30% by weight of Fe, 0.014% by weight of Cu, 0.001% by weight of Mn, 0.001% by weight of Mg, 0.001% by weight ofZn, and 0.03% by weight of T i , with the remainder being Al and inevitable impurities) was consecutively subjected to the following surface treatments.
• the surface of the aluminum sheet was continuously subjected to electrochemical roughening treatment using an alternating current voltage of 60 Hz.
• the electrolyte was an aqueous solution of 10 g/L of nitric acid (containing 5 g/L of aluminum ions and 0.007 % by mass of ammonium ions) at a temperature of 80°C.
• the aluminum sheet was subjected to etching treatment by spraying with a sodium hydroxide concentration of 26% by weight and an aluminum ion concentration of 6.5% by weight at a temperature of 32°C and dissolved in an amount of 0.20 g/m 2 , followed by rinsing with water by spraying.
• the resulting aluminum sheet was subjected to desmutting treatment by spraying with an aqueous solution having a sulfuric acid concentration of 25% by weight at a temperature of 60°C (containing 0.5% by mass of aluminum ions) and then rinsed with water by spraying.
• the resulting aluminum sheet was subjected to anodic oxidation treatment using an anodic oxidation device for.two-stage feeding electrolysis.
• anodic oxidation device for.two-stage feeding electrolysis.
• sulfuric acid was used as the electrolyte to be fed to the electrolysis part.
• the aluminum sheet was rinsed with water by spraying.
• a final oxidized film amount was 2.7 g/m 2 .
• the aluminum sheet subjected to the anodic oxidation treatment was then subjected to treatment with an alkali metal silicate (silicate treatment) by immersion into an aqueous solution of 1% by weight of No. 3 sodium silicate at a temperature of 30°C for 10 seconds. Thereafter, the aluminum sheet was rinsed with water by spraying.
• the silicate-treated aluminum sheet thus obtained was coated with an undercoating solution having the following composition and was dried at 80°C for 15 seconds to form an undercoat film having a coverage after drying of 15 mg/m 2 to form a support A.
• the support in web form obtained above was coated with a lower layer coating solution 1 having the following formulation using a bar coater to give a coating amount of 0.85 g/m 2 and then dried at 160°C for 44 seconds, and it was immediately cooled by cold blasting at 17 to 20°C until the temperature of the support decreased to 35°C. Thereafter, an upper layer coating solution 1 having the following composition was applied using a bar coater to give a coating amount of 0.22 g/m 2 and was dried at 148°C for 25 seconds. Then it was cooled gradually by cold blasting at 20 to 26°C. Thus, a planographic printing plate precursor of Example 1 was formed.
• a planographic printing plate precursor of Comparative Example 1 was prepared in the same manner as in Example 1 except that the polyurethane resin used in the lower layer coating solution 1 was changed to the comparative compound [N-(4-aminosulfonylphenyl)methacrylamide/acrylonitrile/methyl methacrylate (36/34/30: weight-average molecular weight 50000, acid value 2.65)].
• a test pattern image was formed on the planographic printing plate precursors of Examples 1 to 2 and the planographic printing plate precursor of Comparative Example 1 by varying the exposure energy with Trendsetter manufactured by Creo Products Inc. Thereafter, the planographic printing plates, developed with a developer DT-2 manufactured by Fuji Photo Film Co., Ltd. (diluted to have an electric conductivity 43 of mS/cm), were subjected to continuous printing using a printing machine LITHRONE manufactured by Komori Corporation. The printing resistance was evaluated by visually measuring the number of sheets printed with a sufficient ink concentration, such that the larger the number of sheets measured, the better the evaluation of printing durability. The results are shown in Table 1 below.
• planographic printing plate precursors of Examples 1 to 2 and the planographic printing plate precursor of Comparative Example 1 were subjected to exposure, development and printing in the same manner as that used in the evaluation of printing durability described above.
• a step of wiping the plate surface with a cleaner (MULTICLEANER, manufactured by Fuji Photo Film Co., Ltd.) was added every 5,000 sheets of printing to evaluate chemical resistance.
• the chemical resistance was evaluated by visually measuring the number of sheets printed with a sufficient ink concentration, such that the larger the number of sheets measured, the better the evaluation of chemical resistance. The results are shown in Table 1 below.
• planographic printing plate precursors of Examples 1 to 2 and the planographic printing plate precursor of Comparative Example 1 were subjected to scanning exposure at a beam strength of 9 W and a drum speed of 150 rpm to form 0.5% halftone dots (highlights).
• the planographic printing plate precursors were then exposed and subsequently developed with the developer mentioned above.
• the developed planographic printing plates were subjected to continuous printing using a printing machine LITHRONE manufactured by Komori Corporation.
• the halftone dot printing durability was evaluated by visually measuring the number of sheets printed with a sufficient ink concentration. The larger the number of sheets, the better the evaluation of halftone dot printing durability. The results are shown in Table 1 below.
• a test pattern (Staccato 10) image was formed on the heat-sensitive planographic printing plates of Examples 1 to 2 and the planographic printing plate precursor of Comparative Example 1 using a Trendsetter manufactured by Creo Products Inc. at a beam strength of 9 W and a drum speed of 150 rpm.
• the planographic printing plate precursors 1 to 3 which had been exposed under the above conditions were developed at a solution temperature of 30°C for a developing time of 12 seconds using a PS processor 940HII manufactured by Fuji Film Co., Ltd. containing DT-2 manufactured by Fuji Photo Film Co., Ltd. (diluted to have an electric conductivity of 43 mS/cm). Edge portions of the image obtained were observed by an electron microscope (Hitachi S-800 manufactured by Hitachi, Ltd.). The sharpness of images was evaluated according to the following standards.
• Each of the photosensitive planographic printing plates of Examples 1 to 2 and Comparative Example 1 was rubbed 15 times under a load of 250 g with an Abraser Felt CS5 using a rotary abrasion tester (manufactured by TOYOSEIKI). Thereafter, each planographic printing plate was developed at a solution temperature of 30°C for a developing time of 12 seconds using a PS processor 940HII manufactured by Fuji Film Co., Ltd. containing DT-2 manufactured by Fuji Photo Film Co., Ltd. (diluted to have an electric conductivity of 43 mS/cm). The scratch resistance was evaluated according to the following standards.
• a planographic printing plate precursor of Example 3 was produced by forming a recording layer (including a lower layer and an upper layer) on a support B prepared by forming an undercoat layer in the same manner as in the preparation of the support of Example 1 except that no silicate treatment was carried out after the anodic oxidation treatment.
• the resulting photosensitive planographic printing plate was exposed in the same manner as in Example 1 and then was developed at a developing temperature of 28°C for a developing time of 25 seconds using a PS processor 900HII manufactured by Fuji Film Co., Ltd. containing an alkali developer A having the following formulation. Thereafter, printing durability, chemical resistance, scratch resistance and image sharpness were evaluated in the same manner as for Example 1
• the results obtained were printing durability of 150,000 sheets, chemical resistance of 100,000 sheets and halftone dot printing durability of 130,000 sheets, which results are similar to the number of printed sheets obtained in Example 1. Further, the scratch resistance and the sharpness of images were also excellent as in Example 1.
• planographic printing plate precursor was prepared.
• the planographic printing plate precursor was evaluated similarly to example 1 and found that the printing durability was 150 thousands sheets, the chemical resistance was 100 thousands sheets, the dot printing durability was 130 thousands sheets and the scratch resistance and image sharpness were excellent similarly to example 1.
• An aluminum plate having a thickness of 0.3 mm (material: JIS A 1050) was etched at a liquid temperature of 60°C for 10 sec at a caustic soda concentration of 30 g/l and an aluminum ion concentration of 10 g/l, washed with running water, followed by neutralizing and washing with nitric acid of 10 g/l, further followed by washing with water.
• a desmutting process was applied at a liquid temperature of 30 °C in a sulfuric acid aqueous solution of which sulfuric acid concentration was 15 mass percent, followed by washing with water. Furthermore, in a 10 mass percent sulfuric acid aqueous solution set at 20°C, under the DC current density of 6 A/dm 2 , an anodic oxidation process was applied so that an amount of anodic oxidized film may be 2,5 g/m 2 , followed by washing with water and drying. Thereafter, the aluminum plate was processed at 30°C for 10 sec in an aqueous solution of 2.5 mass percent of sodium silicate, and thereby, a support was prepared.
• the centerline average roughness (Ra) of the support was measured with a stylus having a diameter of 2 ⁇ m and found to be 0.48 ⁇ m.
• an undercoat solution same as that of example 1 was coated, followed by drying at 80°C for 15 sec, and thereby, a support C having an undercoat layer having a coated amount of 17 mg/m 2 was obtained.
• a positive planographic printing plate precursor that can be subjected to direct plate making due to scanning exposure based on a digital signal, is excellent in the reproducibility of a high definition image to be able to form a sharp image, and is excellent in the printing durability of a small area image portion such as a dot or a fine line and the chemical resistance can be provided.
• the present invention provides item ⁇ 1>: a planographic printing plate precursor of the invention formed by disposing, on a support, a recording layer that includes an lower layer containing a polymer compound having a constituent expressed by a formula (I) below and a upper layer that contains a water-insoluble and alkali-soluble resin and an infrared absorber and causes an increase in the solubility to an alkaline aqueous solution under exposure.
• a planographic printing plate precursor of the invention formed by disposing, on a support, a recording layer that includes an lower layer containing a polymer compound having a constituent expressed by a formula (I) below and a upper layer that contains a water-insoluble and alkali-soluble resin and an infrared absorber and causes an increase in the solubility to an alkaline aqueous solution under exposure.
• n represents an integer from 0 to 2 and A represents an aryl group.
• the invention provides following items of ⁇ 2> to ⁇ 10>; ⁇ 2> a planographic printing plate precursor in which the water-insoluble and alkali-soluble resin is a novolak resin;

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