Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41N—PRINTING PLATES OR FOILS; MATERIALS FOR SURFACES USED IN PRINTING MACHINES FOR PRINTING, INKING, DAMPING, OR THE LIKE; PREPARING SUCH SURFACES FOR USE AND CONSERVING THEM
  • B41N3/00—Preparing for use and conserving printing surfaces
  • B41N3/08—Damping; Neutralising or similar differentiation treatments for lithographic printing formes; Gumming or finishing solutions, fountain solutions, correction or deletion fluids, or on-press development

Definitions

• the present invention relates to a fountain solution composition for lithographic printing, and more specifically to a fountain solution composition for lithographic printing to be used for an offset printing process.
• Lithography is a printing process utilizing the nature that water and oil do not mix each other inherently.
• the surface of a printing plate is composed of a non-image area, which receives water and repels oil based ink, and an image area, which repels water and receives oil based ink.
• a non-image area which receives water and repels oil based ink
• an image area which repels water and receives oil based ink.
• a lithographic press is usually based on an offset printing process, in which an ink and a fountain solution are supplied on to a plate, the ink attaches to an image area and the fountain solution attaches to a non-image area to form an image, and the image on the plate is transferred to a rubber blanket, and is further transferred from the rubber blanket to a paper to complete printing.
• aqueous solution containing a colloidal substance such as a bichromate, a phosphate, gum arabic, and carboxymethylcellulose (CMC).
• CMC carboxymethylcellulose
• the Dahlgren system in which an aqueous solution containing approx. 20 to 25% of isopropyl alcohol is used as a fountain solution, has been proposed.
• isopropyl alcohol is volatile, it requires special equipment to maintain constant its concentration in the fountain solution. Further, isopropyl alcohol has an unpleasant odor, and is not preferable from a standpoint of the work environment.
• Patent Literature 1 As a fountain solution without containing isopropyl alcohol have been proposed recently a fountain solution containing a specific propylene glycol series compound (see Patent Literature 1); a fountain solution containing an addition compound of ethylenediamine with ethylene oxide and propylene oxide (see Patent Literature 2 and 3); and a fountain solution containing an addition compound of diethylenetriamine with ethylene oxide and propylene oxide (see Patent Literature 4). Further, as printing chemicals to be used in a fountain solution, etc., in Patent Literature 5 are described printing chemicals containing a water soluble polymer having an adsorptive group, which can be adsorbed on the surface of a plate substrate for lithographic printing, and a sulfonic acid group.
• Patent Literature 6 proposes addition of a diol series compound to overcome a drawback of such (so-called) blanket piling that an ink component and a paper component build up gradually at a non-image area on a rubber blanket over long-time continuous printing. While, as a problem during a lithography printing process there is a pending problem that dirt appears on a non-image area, more specifically, when a printing press is stopped for a while for some reasons such as a tea break, at restart of printing a tiny speck may occasionally appear at a non-image area (hereinafter referred to as "dirt after a break").
• An object of the present invention is to provide a fountain solution composition for lithographic printing which is superior in preventing dirt at a non-image area of a lithographic plate.
• Another object of the present invention is to provide a fountain solution composition for lithographic printing, which can attain effectively high quality printing by mitigating dirt at a non-image area during the initial startup of printing, or dirt after a break, caused by dirt at a non-image area of a plate surface at a restart of printing after a stop of a printing press.
• An additional object of the present invention is to provide a fountain solution composition for lithographic printing, which can suppress decrease in the ink density at an image area attaining high quality printing, even when the component concentration of the fountain solution is increased.
• the present invention is a fountain solution composition for lithographic printing characterized by containing a star polymer having at least one hydrophilic group.
• a star polymer having at least one hydrophilic group.
• the star polymer one containing further at least one substrate adsorptive group is also preferable.
• a star polymer having 3 branches to 10 branches (both inclusive) can be favorably used.
• a specific structure of a star polymer it has 3 branches to 10 branches (both inclusive) of polymer chains branched from a skeleton through sulfide bonds, and more specifically it has 3 branches to 10 branches (both inclusive) of polymer chains branched from a skeleton through sulfide bonds, the polymer being obtained by polymerizing an ethylenic unsaturated monomer in the presence of a multifunctional thiol.
• Examples of at least one hydrophilic group in a star polymer of the present invention include at least one selected from the group consisting of a sulfonic acid group and a salt thereof, an amide group, a polyalkylene oxide group, a hydroxy group, a sulfuric monoester group and a salt thereof, a sulfonamide group, an amino group, a sulfuric acid-monoamide group and a salt thereof, and a betaine structure.
• Examples of a substrate adsorptive group of a star polymer include at least one selected from the group consisting of a phosphonic acid group and a salt thereof, a phosphoric ester group and a salt thereof, and a carboxylic acid group and a salt thereof.
• Examples of a preferable embodiment of the present invention include a fountain solution composition for lithographic printing containing a water soluble polymer not having a star structure.
• the water soluble polymer not having a star structure include at least one water soluble macromolecular compound selected from the group consisting of gum arabic, a cellulose derivative and a modification thereof, polyvinyl alcohol and a derivative thereof, polyvinylpyrrolidone, a vinyl methyl ether/maleic anhydride copolymer, a vinyl acetate/maleic anhydride copolymer, a styrene/maleic anhydride copolymer, a water soluble soybean polysaccharides, starch, a starch derivative, pullulan and a pullulan derivative, gelatin, and hemicellulose extracted from a soybean.
• the present invention is directed also to a fountain solution composition for lithographic printing as a concentrated fountain solution composition having the above described characteristics.
• a fountain solution composition for lithographic printing according to the present invention is superior in prevention of dirt at a non-image area of a lithographic plate.
• a fountain solution composition for lithographic printing according to the present invention a high quality print can be provided effectively by mitigating dirt after a break, which is caused by dirt at a non-image area at a restart of printing after a stop of a printing press.
• a printing operation can be conducted with limited number of waste of paper.
• the term "waste of paper” or “waste paper” means herein the number of paper sheets required from the start of printing until an ink disappears completely from a non-image area on a print out.
• a good print out can be provided with little paper waste at a restart of printing, after a printing press is stopped during a printing operation. Further, if the concentration of an additive, etc. in a fountain solution is increased in order to prevent dirt at a non-image area, decrease in the ink density at an image area can be prevented, and as the result a high quality print can be provided.
• a star polymer to be used according to the present invention is a kind of a branched macromolecule, namely a polymer having a structure, in which 3 or more linear macromolecules bond especially at a single point.
• Examples of the structure of a star polymer to be used according to the present invention are schematically shown with a skeleton A and polymer chains Pl as follows. Namely, it has a structure in which either of the terminals of a plurality of polymer chains Pl bond to the skeleton A, and an appropriate branch number is 3 to 10.
• Any star polymer may be used as a star polymer to be used according to the present invention, insofar as it has the structure depicted above.
• a star polymer include a star polymer prepared by a coupling process or a living anion process as described in " Shin Jikken-kagaku Kouza, Koubunshi Kagaku I", edited by The Chemical Society of Japan, p. 208 to 210 ; a star polymer prepared by a synthetic method conducting a polymerization reaction under photoirradiation using as an initiator a compound containing a dithiocarbamate group and/or a compound containing a xanthate group as described in Japanese Published Unexamined Application No. 10-279867 ; and a star polymer prepared by a usual radical polymerization using a multifunctional thiol as a chain transfer agent.
• a star polymer according to the present invention from viewpoints of the easiness in synthesis and the performance of an obtained polymer, a polymer prepared by polymerizing an ethylenic unsaturated monomer in the presence of a multifunctional thiol, constituted of polymer chains branched from a skeleton through sulfide bonds is preferable.
• a hub portion which is a 3 or more functional thiol residue as the skeleton, is preferable.
• a main chain of an addition polymer outshoots from each thio part in the hub. Consequently, 3 or more main chains outshoot from thio parts.
• a skeleton A preferably has a structure represented by the following general formula (1).
• a 1 is an n-valent organic group, and n is an integer of 3 or higher.
• Specific examples of A 1 include the following structures and an organic group constituted to n-valent by a combination of a plurality of the following structures.
• n is an integer of 3 to 10, more preferably an integer of 3 to 8, and especially preferably an integer of 4 to 8.
• any compound having a plurality of thiol groups per each molecule can be favorable used, a multifunctional thiol with 3 to 10 functional groups is preferable, a thiol with 3 to 8 functional groups is more preferable, and a thiol with 4 to 8 functional groups is especially preferable.
• Examples of such a multifunctional thiol include the following compound A to compound F.
• Compound A is a compound prepared by reacting an electrophile, such as a halogenide, and a sulfonic acid ester with an alcohol, with a sulfurizing agent, such as thiourea, potassium thiocyanate, and thioacetic acid, followed by various treatments.
• an electrophile such as a halogenide
• a sulfurizing agent such as thiourea, potassium thiocyanate, and thioacetic acid
• a compound B is a compound prepared by a dehydration condensation reaction between a multifunctional alcohol and a carboxylic acid having a thiol group, and among others a compound prepared by a condensation reaction between a multifunctional alcohol with 3 to 10 functional groups and a monocarboxylic acid with a single thiol group is preferable.
• a multifunctional alcohol examples include cyclohexanetriol (3), glycerol (3), 2-hydroxymethyl-1,3-propanediol (3), 1,1,1-tris(hydroxymethyl)ethane (3), 1,2,4-butanetriol (3), trimethylol propane (3), 1,2,3-trihydroxyhexane (3), 1,2,6-trihydroxyhexane (3), 1,2,3-heptanetriol (3), pyrogallol (3), 1,2,4-benzenetriol (3), phloroglucinol (3), 1,1,1-tris(4-hydroxyphenyl)ethane (3), 1,3,5-tris(2-hydroxyethyl)isocyanurate (3), pentaerythritol (4), threitol (4), erythritol (4), xylulose (4), ribulose (4), quebrachitol (5), adonitol (5), arabitol (5), xylitol (5)
• cyclohexanetriol, glycerol (3), 2-hydroxymethyl-1,3-propanediol (3), 1,1,1-tris(hydroxymethyl)ethane (3), trimethylol propane (3), phloroglucinol (3), 1,1,1-tris(4-hydroxyphenyl)ethane (3), 1,3,5-tris(2-hydroxyethyl)isocyanurate (3), pentaerythritol (4), catechin (5), epicatechin (5), inositol (6), dipentaerythritol (6), and tripentaerythritol (8) are preferable; cyclohexanetriol (3), 2-hydroxymethyl-1,3-propanediol (3), 1,1,1-tris(hydroxymethyl)ethane (3), trimethylol propane (3), phloroglucinol (3), 1,1,1-tris(4-hydroxyphenyl)ethane (3), 1,3,5-tris
• a monocarboxylic acid having a thiol group examples include mercaptoacetic acid, 3-mercaptopropionic acid, 2-mercaptopropionic acid, 3-mercapto isobutyric acid, N- acetylcysteine, N- (2-mercaptopropionyl)glycine, and thiosalicylic acid.
• a compound B Mercaptoacetic acid, 3-mercaptopropionic acid, 2-mercaptopropionic acid, 3-mercapto isobutyric acid, N- acetylcysteine, and N- (2-mercaptopropionyl)glycine are preferable; 3-mercaptopropionic acid, 2-mercaptopropionic acid, 3-mercapto isobutyric acid, N- acetylcysteine, and N- (2-mercaptopropionyl)glycine are more preferable; and 3-mercaptopropionic acid, 3-mercapto isobutyric acid, N -acetylcysteine, and N -(2-mercaptopropionyl)glycine are especially preferable.
• Specific examples of a compound B include the following compounds, provided that it is not limited thereto.
• SB-1 to SB-34 SB-36 to SB-48, SB-50 to SB-55, SB-57 to SB-62, SB-64 to SB-69, SB-71 to SB-76, SB-78 to SB-111, SB-113 to SB-118, SB-120 to SB-125, SB-127 to SB-132, SB-134 to SB-139, SB-141 to SB-146, SB-148 to SB-153, SB-155 to SB-181, SB-183 to SB-188, SB-190 to SB-195, SB-197 to SB-202, and SB-204 to SB-217; more preferable are SB-1 to SB-6, SB-9 to SB-13, SB-15 to SB-20, SB-22 to SB-27, SB-36 to SB-41, SB-78 to SB-83, SB-85 to SB-90, SB-92 to SB-97, SB-99 to SB-104, SB-155 to SB-160, SB-162 to SB-167, SB-169 to SB-174, SB-204 to SB-209, and
• a compound C is a compound prepared by a dehydration condensation reaction between a multifunctional amine and a carboxylic acid having a thiol group, and among others a compound prepared by a condensation reaction between a multifunctional amine with 3 to 10 functional groups and a monocarboxylic acid with a thiol group is preferable.
• a multifunctional amine examples include diethylenetriamine (3), N -(2-aminoethyl)-1,3-propanediamine (3), N -(3-aminopropyl)-1,3-propanediamine (3), spermidine (3), bis(hexamethylene)triamine (3), 4-(aminomethyl)-1,8-octanediamine (3), triethylenetetramine (4), 1,4,7,11-tetraazaundecane (4), N,N '-bis(3-aminopropyl)ethylenediamine (4), N,N '-bis(2-aminoethyl)-1,3-propanediamine (4), N,N '-bis(3-aminopropyl)-1,3-propanediamine (4), spermine (4), tris(2-aminoethyl)amine (3), tetraethylenepentamine (5), pentaethylenehexamine (6), 1,4,7-triazacyclononon
• carboxylic acid having a thiol group examples include the carboxylic acids described for the compound B.
• Specific examples of the compound include the following compounds, provided that the present invention is not limited thereto.
• a compound D is a compound prepared by a dehydration condensation reaction between a compound having alcohol and amine and a carboxylic acid having a thiol group, and a compound prepared by a condensation reaction between a multifunctional alcoholamine with 3 to 10 functional groups of alcohol and amine and a monocarboxylic acid with a thiol group is preferable.
• a multifunction alcoholamine examples include diethanolamine (3), serinol (3), diisopropanolamine (3), 2-amino-2-ethyl-1,3-propanediol (3), 2-amino-2-methyl-1,3-propanediol (3), tris(hydroxymethyl)aminomethane (4), bishomoTRIS (4), 1,3-diamino-2-hydroxypropane (3), 2-(2-aminoethylamino)ethanol (3), N,N' -bis(2-hydroxyethyl)ethylenediamine (4), 1,3-bis[tris(hydroxymethyl)methylamino]propane (8), 1-amino-1-deoxy-D-sorbitol (6), N -methyl-D-glucamine (6), 2,3-diaminophenol (3), 4-aminoresorcinol (3), norphenylephrine (3), octopamine (3), synephrine (3), 3,4-dihydroxybenzy
• a numeral in ( ) means a number of functional groups.
• Specific examples of the carboxylic acid having a thiol group include the carboxylic acids described for the compound B.
• Specific examples of the compound include the following compounds, provided that the present invention is not limited thereto.
• a compound E is a compound prepared by a dehydration condensation reaction between a multifunctional carboxylic acid and an alcohol having a thiol group, and among others a compound prepared by a condensation reaction between a multifunctional carboxylic acid with 2 to 10 functional groups and an alcohol with 1 or more thiol groups is preferable.
• a multifunctional carboxylic acid examples include oxalic acid (2), malonic acid (2), methylmalonic acid (2), succinic acid (2), methylsuccinic acid (2), glutaric acid (2), adipic acid (2), pimelic acid (2), suberic acid (2), azelaic acid (2), sebacic acid (2), tricarballylic acid (3), 1,2,3,4-butanetetracarboxylic acid (4), aconitic acid (3), hexafluoroglutaric acid (2), malic acid (2), tartaric acid (2), citric acid (3), diglycolic acid (2), 3,6-dioxaoctanedicarboxylic acid (2), tetrahydrofuran-2,3,4,5-tetracarboxylic acid (4), mercaptosuccinic acid (2), thiodiglycolic acid (2), 2,2',2",2'''-[1,2-ethanediylidenetetrakis(thio)]te
• an alcohol having a thiol group examples include 2-mercaptoethanol (1), 1-mereapto-2-propanol (1), 3-mercapto-1-propanol (1), 3-mercapto-2-butanol (1), 2,3-dimercapto-1-propanol (2), and 4-hydroxythiophenol (1); preferable are 2-mercaptoethanol (1), 3-mercapto-1-propanol (1), and 2,3-dimercapto-1-propanol (2); more preferable are 2-mercaptoethanol (1), and 3-mercapto-1-propanol (1); and especially preferable is 3-mercapto-1-propanol (1).
• a numeral in ( ) means a number of functional groups. Examples of the compound include the compounds listed in Table 4 and Table 5 below, provided that it is not limited thereto.
• a compound F is a compound prepared by a dehydration condensation reaction between a multifunctional carboxylic acid and an amine having a thiol group, and among others a compound prepared by a condensation reaction between a multifunctional carboxylic acid with 2 to 10 functional groups and an amine with 1 or more thiol groups is preferable.
• Specific examples of a multifunctional carboxylic acid include the above described multifunctional carboxylic acids.
• an amine with 1 or more thiol groups include 2-aminoethanethiol, 2-aminothiophenol, 3-aminothiophenol, and 4-aminothiophenol; preferable are 2-aminoethanethiol, and 4-aminothiophenol; and more preferable is 2-aminoethanethiol.
• Specific examples of the compound include the following compounds, provided that the present invention is not limited thereto.
• the compound A to the compound E are preferable, the compound A, the compound B, the compound C, and the compound E are more preferable, and the compound A, the compound B, and the compound C are especially preferable.
• Examples of a polymer chain in a star polymer to be used according to the present invention include a vinyl polymer, a (meth)acrylic acid series polymer, and a styrene series polymer, which have been heretofore known and can be produced by a radical polymerization; and a (meth)acrylic acid series polymer is especially preferable.
• a star polymer to be used according to the present invention has at least one hydrophilic group.
• a polymer chain of a star polymer to be used according to the present invention has at least one hydrophilic group in order to enhance the hydrophilicity of the surface of a substrate and improve the resistance to dirt. More preferably a star polymer having at least one hydrophilic group contains a recurring unit having at least one hydrophilic group as a copolymer component.
• a polymer chain of a star polymer to be used according to the present invention may have one, or two or more such hydrophilic groups.
• hydrophilic group examples include the following.
• M 1 represents a hydrogen atom, a metal atom belonging to an alkali metal or an alkaline earth metal, or an ammonium group.
• X + is a group expressed by -N + R 1 R 2 -, -S + R 1 -, -I + -, and -P + R 1 R 2 -.
• R 1 , R 2 independently represent a hydrogen atom, an alkyl group, an aryl group, an alkenyl group, and alkynyl group;
• R 3 represents an alkylene group;
• R 4 represents a hydrogen atom, an alkyl group, an aryl group, an alkenyl group, and an alkynyl group.
• the n represents an integer of 1 to 100.
• R 1 is preferably a hydrogen atom or a C1 to C3 alkyl group, and among others preferably a hydrogen atom or a methyl group.
• R 2 is preferably a hydrogen atom or a C1 to C3 alkyl group, and among others preferably a hydrogen atom or a methyl group.
• R 3 is preferably a C2 to C5 alkylene group, and among others preferably ethylene or propylene.
• R 4 is preferably a hydrogen atom or a C1 to C6 alkyl group, and the n is preferably an integer of 2 to 90.
• any functional group which can enhance the affinity with water, can be utilized favorably as a hydrophilic group; and a sulfonic acid (salt) group, an amide group, a polyalkylene oxide group, a hydroxy group, a sulfuric monoester (salt) group, a sulfonamide group, an amino group, a sulfuric monoamide (salt) group, and a betaine structure are preferable; a sulfonic acid (salt) group, an amide group, a polyalkylene oxide group, a hydroxy group, a sulfuric monoester (salt) group, a sulfonamide group, an amino group, a sulfuric monoamide (salt) group, and a betaine structure are more preferable, and a sulfonic acid (salt) group, an amide group, a polyalkylene oxide group, a hydroxy group and a betaine structure are especially preferable.
• R a to R c independently represent a hydrogen atom, a C1 to C6 alkyl group, or a halogen atom.
• L has the same meaning as described above.
• W represents a hydrophilic group and preferable embodiments are as described above.
• a recurring unit having a hydrophilic group in a polymer chain of a star polymer to be used according to the present invention include the following, provided that the present invention is not limited thereto.
• a star polymer to be used according to the present invention may contain a recurring unit having one kind of hydrophilic group or a recurring unit having 2 or more kinds of hydrophilic groups.
• the content of a recurring unit having a hydrophilic group in a polymer chain of a star polymer to be used according to the present invention is preferably 30 to 98 mol-% based of the total recurring units contained in a star polymer, more preferably 40 to 90 mol-%, and further preferably 50 to 90 mol-%.
• a polymer chain of a star polymer to be used according to the present invention contains at least one functional group, which can be adsorbed on the surface of a substrate by interacting with the surface of a substrate (herein referred to as a "substrate adsorptive group”), in order to enhance adherence to a substrate.
• a polymer chain of a star polymer to be used according to the present invention contains a recurring unit having at least one substrate adsorptive group as a copolymer component.
• a functional group, which can be adsorbed by interacting with the surface of a substrate include a group, which can interact with a metal, a metallic oxide, a hydroxy group, etc.
• the substrate adsorptive group examples include a phosphonic acid group or a salt thereof, a phosphoric ester group or a salt thereof, and a carboxylic acid group or a salt thereof.
• a polymer chain of a star polymer to be used according to the present invention may contain one kind, or two or more kinds of such substrate adsorptive groups. While, in a star polymer to be used according to the present invention, a hydrophilic group and a substrate adsorptive group are different group from each other. Therefore, if a star polymer has at least one hydrophilic group and at least one substrate adsorptive group, it has namely at least two kinds of functional groups. Specific examples of a substrate adsorptive group include the following.
• M 1 and M 2 independently represent a hydrogen atom, a metal atom belonging to an alkali metal or an alkaline earth metal, or an ammonium group.
• a substrate adsorptive group should be preferably selected from a phosphonic acid group or a salt thereof (structure 1), a phosphoric ester group or a salt thereof (structure 2), and a carboxylic acid group or a salt thereof; and among others a phosphoric ester group or a salt thereof, and a phosphonic acid group or a salt thereof are preferable.
• Specific examples of a recurring unit having at least one substrate adsorptive group in a polymer chain of a star polymer to be used according to the present invention are preferably represented by the following general formula (B1).
• R a to R c independently represent a hydrogen atom, a C1 to C6 alkyl group, or a halogen atom.
• Q represents a substrate adsorptive group, whose preferable embodiments are same as above.
• L is a single bond, or a divalent linking group.
• the divalent linking group is constituted of 1 to 60 carbon atoms, 0 to 10 nitrogen atoms, 0 to 50 oxygen atoms, 1 to 100 hydrogen atoms, and 0 to 20 sulfur atoms; and more specifically examples thereof include those constituted of a combination of the following structure units.
• R d and R e represent a hydrogen atom, a C1 to C20 alkyl group, a C6 to C20 aryl group, or a halogen atom.
• the n represents an integer of 1 to 4.
• a star polymer according to the present invention may contain one kind, or two or more kinds of substrate adsorptive groups in it.
• the content of a recurring unit having a substrate adsorptive group in a polymer chain of a star polymer usable according to the present invention is preferably 2 to 80 mol-% based on the total recurring units included in the star polymer, more preferably 2 to 70 mol-%, further preferably 5 to 50 mol-%, and especially preferably 10 to 40 mol-%.
• a polymer chain of a star polymer to be used according to the present invention may be a copolymer containing a recurring unit other than the above (hereinafter occasionally referred to simply as "(an)other recurring unit").
• another recurring unit include such recurring units as originated from a heretofore known variety of monomers.
• a polymer chain of a star polymer to be used according to the present invention may contain, in addition to the above described recurring unit having a hydrophilic group and recurring unit having a substrate adsorptive group, for example, a polymerized unit of an alkyl or aralkyl (meth)acrylate, or a polymerized unit of a styrene derivative.
• An alkyl group of an alkyl (meth)acrylate is preferably a C1 to C5 alkyl group, or an C2 to C 8 alkyl group having the aforedescribed substituent, and more preferably a methyl group.
• Examples of an aralkyl (meth)acrylate include benzyl (meth) acrylate.
• Examples of a styrene derivative include styrene, and 4- tert -butylstyrene.
• the content of another recurring unit in a polymer chain of a star polymer usable according to the present invention is preferably 40 mol-% or less based on the total recurring units included in the star polymer, more preferably 30 mol-% or less, and further preferably 20 mol-% or less.
• a substrate adsorptive group is a phosphonic acid group or a salt thereof, a phosphoric ester group or a salt thereof, or a carboxylic acid group or a salt thereof
• a hydrophilic group is a sulfonic acid group or a salt thereof, an amide group, a polyalkylene oxide group, a hydroxy group, or a betaine structure
• a substrate adsorptive group is a phosphonic acid group or a salt thereof, or a phosphoric ester group or a salt thereof
• a hydrophilic group is a sulfonic acid group or a salt thereof, a polyalkylene oxide group, a hydroxy group, or a betaine structure
• especially preferably a substrate adsorptive group is a phosphonic acid group or
• the mass average molar mass (Mw) of the star polymer is preferably 5,000 or higher, more preferably 10,000 or higher, but preferably 1,000,000 or lower, more preferably 500,000 or lower.
• the number average molar mass (Mn) of the star polymer is preferably 1,000 or higher, more preferably 2,000 or higher, but preferably 500,000 or lower, more preferably 300,000 or lower.
• the polydispersity (Mw/Mn) of the star polymer is preferably 1.1 to 10.
• Star polymers shown in Table 7 to 12 include polymers P A -1, 2 and so forth, whose polymer chain has a structure constituted of a recurring unit (A) having a hydrophilic group, as well as polymers P A B -1, 2 and so forth, whose polymer chain has a structure constituted of a recurring unit (A) having a hydrophilic group and a recurring unit (B) having a substrate adsorptive group.
• a fountain solution composition for lithographic printing according to the present invention may contain a single kind of star polymer or 2 or more kinds.
• the appropriate content of a star polymer in a fountain solution composition for lithographic printing according to the present invention is in general 0.005 to 10 mass-% with respect to a fountain solution before using, and within the range a dirt prevention effect on a non-image area and a mesh image area can be obtained sufficiently.
• the content is more preferably 0.01 to 5 mass-% and further preferably 0.1 to 3 mass-%.
• a fountain solution composition is preferably used by diluting appropriately a concentrated solution generally before using, and a dilution rate of approx. 10 to 200-fold is appropriate, and especially approx. 30 to 100 is preferable. If the concentration rate is too high, such troubles as deposition, or liquid separation in a concentrated solution are apt to happen.
• a fountain solution composition ready for use is called simply as a "fountain solution”.
• solubilizer in preparing a concentrated solution, compounds according to the following general formula (I) are used, by which the advantageous effects of the present invention can be synergistically enhanced.
• R 1 -O-(CH 2 CHR 2 O) m -H (I) wherein R 1 represents a C1 to C4 alkyl group or an OH group, R 2 represents a hydrogen atom or a methyl group, and m represents an integer of 1 to 5.
• R 1 in the formula represents an OH group or a C1 to C4 alkyl group with a straight chain or a branched chain; and specific examples thereof include an OH group, a methyl group, an ethyl group, a propyl group, an isopropyl group, an n -butyl group, an isobutyl group, and a t-butyl group; and among others an OH group, an n -butyl group and a t-butyl group are especially preferable.
• m represents an integer of 1 to 5, and an integer of 1 to 3 is preferable, and especially preferable 1.
• R 1 in the general formula (I) is an alkyl group
• R 1 in the general formula (I) is an alkyl group
• examples include ethylene glycol mono- t -butyl ether, ethylene glycol mono- n -butyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monoethyl ether, tetrapropylene glycol monoethyl ether, propylene glycol monopropyl ether, dipropylene glycol monopropyl ether, tripropylene glycol monopropyl ether, propylene glycol monoisopropyl ether, dipropylene glycol monoisopropyl ether, tripropylene glycol monoisopropyl ether, propylene glycol monon-butyl ether,
• R 1 in the general formula (I) is an OH group
• R 1 in the general formula (I) examples include propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol and pentapropylene glycol.
• propylene glycol, dipropylene glycol, and tripropylene glycol are preferable, and propylene glycol is most preferable.
• a compound expressed by the general formula (I) are used preferably a plurality of compounds listed above in a combination, and especially if a compound whose R 1 is an alkyl group and a compound whose R 1 is an OH group are used in a combination, the activity for suppressing blanket piling can be high, and further roller stripping, etc. can be prevented.
• a fountain solution composition according to the present invention can use as a fountain solvent 3-methoxy-3-methylbutanol, 3-methoxybutanol, ethylene glycol, diethylene glycol, triethylene glycol, butylene glycol, hexylene glycol, glycerol, diglycerol, polyglycerol, trimethylol propane, etc.
• the solvent is used in a range of 0.1 to 3 mass-% with respect to the fountain solution, and preferably in a range of 0.3 to 2 mass-%.
• a fountain solution composition according to the present invention may contain also water soluble polymeric compounds used conventionally in a fountain solution composition in addition to a star polymer described above.
• a water soluble polymeric compound to be used in a fountain solution composition according to the present invention include a natural product and a modification thereof, such as gum arabic, a starch derivative (e.g., dextrin, enzyme-degraded dextrin, hydroxypropyl enzyme-degraded dextrin, carboxymethyl starch, starch phosphate , and octenyl succinate starch), an alginic acid salt, a cellulose derivative (e.g., carboxymethylcellulose, carboxyethyl cellulose, methylcellulose, hydroxypropyl cellulose, hydroxypropylmethyl cellulose, and hydroxyethyl cellulose); and a synthetic product, such as polyethylene glycol and a copolymer thereof, polyvinyl alcohol and a derivative thereof, polyvinylpyrrolidone, polyacrylamide
• water soluble polymeric compounds carboxymethyl cellulose, polyvinylpyrrolidone, hydroxypropyl cellulose, and hydroxypropylmethyl cellulose can be used especially favorably.
• the molecular weight of the water soluble polymeric compound is preferably 300 to 500,000, more preferably 300 to 100,000, and especially preferably 500 to 30,000.
• An appropriate content of a water soluble polymeric compound is 0.0001 to 0.1 mass-% with respect to the fountain solution, and more preferably 0.0005 to 0.05 mass-%.
• a fountain solution composition according to the present invention is preferably further adjusted to a favorable pH value with a pH adjustor. It is preferably used in an acidic range with a pH value of 3 to 7, but it can also be used in an alkali range of pH 7 to 11.
• a pH adjustor a water soluble organic or inorganic acid and a salt thereof can be used.
• Examples of a preferable organic acid include acetic acid, citric acid, oxalic acid, malic acid, tartaric acid, succinic acid, lactic acid, ascorbic acid, gluconic acid, hydroxyacetic acid, malonic acid, levulinic acid, sulfanilic acid, p-toluenesulfonic acid, phytic acid, and an organic phosphonic acid;
• examples of an inorganic acid include phosphoric acid, nitric acid, sulfuric acid, and polyphosphoric acid; and an alkali metal salt, an alkaline earth metal salt, an ammonium salt, and an organic amine salt thereof can be also favorably used. They may be used as a mixture of two or more.
• the content of such a pH adjustor in a fountain solution is generally in a range of 0.001 to 0.3 mass-%.
• a fountain solution composition according to the present invention contains preferably further as an aid for improving wettability a pyrrolidone derivative, acetylene glycols or acetylene alcohols.
• a pyrrolidone derivative include ethylpyrrolidone, butylpyrrolidone, pentapyrrolidone, hexapyrrolidone, octylpyrrolidone, and laurylpyrrolidone; and examples of acetylene glycols and acetylene alcohols include 3,5-dimethyl-1-hexyn-3-ol., 2,5-dimethyl-3-hexyne-2,5-diol, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, 2-butyne-1,4-diol, and 3-methyl-l-butyn-3-
• a fountain solution composition according to the present invention contains preferably further 2-ethyl-1,3-hexanediol, an adduct of 2-ethyl-1,3-hexanediol with ethylene oxide and/or propylene oxide, an adduct of trimethylol propane with propylene oxide, an adduct of glycerol with propylene oxide, an adduct of sorbitol with propylene oxide, tetrahydrofurfuryl alcohol, etc.
• a compound listed above should be used at an appropriate content of 0.01 to 7 mass-% with respect to a fountain solution, and more preferably at 0.05 to 5 mass-%.
• a fountain solution composition according to the present invention may additionally contain, for example, a compound derived from ethylenediamine or diethylenetriamine by adding ethylene oxide and propylene oxide, and such a compound does not inflict damages to an image area, even if a residual aqueous drop is left standing on a plate and concentrated by water evaporation while a printing press is stopped.
• the addition mole number ratio of ethylene oxide to propylene oxide thereof is preferably in a range of 5/95 to 50/50, and more preferably in a range of 20/80 to 35/65.
• Each copolymer chain may have a block structure or a random structure.
• the weight-average molecular weight of the addition compound used according to the present invention is preferably 500 to 5000, more preferably 800 to 1500, and optimally the weight-average molecular weight is about 1000.
• the molecular weight and the ratio of ethylene oxide to propylene oxide can be determined by measurements of hydroxyl value and amine value, NMR analysis, etc.
• a fountain solution composition according to the present invention can use a surfactant as an aid for wettability improvement.
• a surfactant examples include a fatty acid salt, an abietate, a hydroxyalkanesulfonate, an alkanesulfonate, a dialkylsulfosuccinate, an alkylbenzenesulfonate, an alkylnaphthalenesulfonate, an alkylphenoxypolyoxyethylene propylsulfonate, a polyoxyethylene alkylsulfenyl ether salt, an N-methyl-N-oleyltaurine sodium salt, an N-alkylsulfosuccinate monoamide disodium salt, a petroleum sulfonate, sulfated castor oil, sulfated tallow, a sulfate salt of a fatty acid alkyl ester, an alkylsulfate salt, a polyoxy
• nonionic surfactant examples include a polyoxyethylene alkyl ether, a polyoxyethylene alkylphenyl ether, a polyoxyethylene polystyryl phenyl ether, a polyoxyethylene polyoxypropylene alkyl ether, a partial ester of glycerol and a fatty acid, a partial ester of sorbitan and a fatty acid, a partial ester of pentaerythritol and a fatty acid, a propylene glycol mono-fatty acid ester, a partial ester of sucrose and a fatty acid, a partial ester of polyoxyethylene sorbitan and a fatty acid, a partial ester of polyoxyethylene sorbitol and a fatty acid, a polyethylene glycol fatty acid ester, a partial ester of polyglycerol and a fatty acid, a polyoxyethylene castor oil, a partial ester of polyoxyethylene glycerol and a fatty acid
• a polyoxyethylene alkyl ether a polyoxyethylene alkylphenyl ether, a polyoxyethylene-polyoxypropylene block copolymer, and polyoxyethylene castor oil ether can be favorably used.
• a fluorinated surfactant and a silicone surfactant can be used. If a surfactant is used, considering foaming, the content of 1.0 mass-% or less, preferably 0.001 to 0.5 mass-%, with respect to a fountain solution is appropriate.
• a fountain solution composition according to the present invention may contain also a sugar.
• a sugar to be used includes a sugar alcohol produced by hydrogenation.
• Specific examples of a preferable sugar include D-erythrose, D-threose, D-arabinose, D-ribose, D-xylose, D-erythropentulose, D-allulose, D-galactose, D-glucose, D-mannose, D-talose, ⁇ -D-fructose, ⁇ -L-sorbose, 6-deoxy-D-glucose, D-glycero-D-galactose, ⁇ -D-allo-heptulose, ⁇ -D-altro-3-heptulose, saccharose, lactose, D-maltose, isomaltose, inulobiose, hyaluronic acid, maltotriose, D,L-arabitol, ribitol, x
• a calcium ion, etc. contained in tap water or well water for diluting a concentrated solution before using may affect printing negatively and make a print susceptible to dirt.
• a chelating agent can overcome the drawback.
• a preferable chelating agent include a potassium salt or a sodium salt of the acid listed below.
• the acid examples include an organic phosphonic acid, such as ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, hydroxyethylethylenediaminetriacetic acid, nitrilotriacetic acid, 1-hydroxyethane-1,1-diphosphonic acid, and aminotri(methylenephosphonic acid), as well as a phosphonoalkanetricarboxylic acid.
• a salt of an organic amine can be also used effectually.
• a chelating agent which can be stably present in a fountain solution composition in use without disturbing printing, is selected among them.
• An appropriate content of a chelating compound in a fountain solution composition in use is 0.001 to 0.5 mass-% and preferably 0.002 to 0.25 mass-%.
• a fountain solution composition according to the present invention may contain as an odor masking reagent an ester, which has been heretofore known for use as a fragrance.
• an ester which has been heretofore known for use as a fragrance.
• Preferable examples thereof include n -pentyl acetate, isopentyl acetate, n -butyl butyrate, n -pentyl butyrate and isopentyl butyrate; and especially n -butyl butyrate, n -pentyl butyrate and isopentyl butyrate are favorable.
• a fountain solution composition according to the present invention may contain an antiseptic agent; and examples of an antiseptic agent include phenol or a derivative thereof, formalin, an imidazole derivative, sodium dehydroacetate, a 4-isothiazolin-3-one derivative, a benztriazole derivative, a derivative of amidine or guanidine, a quaternary ammonium salt, pyridine, a derivative of quinoline or guanidine, a derivative of diazine or triazole, a derivative of oxazole or oxazine, bromonitropropanol of a bromonitroalcohol, 2,2-dibromo-2-nitroethanol, and 3-bromo-3-nitropentane-2,4-diol.
• an antiseptic agent include phenol or a derivative thereof, formalin, an imidazole derivative, sodium dehydroacetate, a 4-isothiazolin-3-one derivative, a benztriazole derivative, a derivative
• a preferable addition amount is an amount, which can exert stably activity against bacteria, fungi, yeast, etc., and is preferably in a range of 0.001 to 1.0 mass-% with respect to a fountain solution.
• Antiseptic agents should preferably be used in a combination of 2 or more thereof, which have respectively activity against certain fungi, bacteria or yeast.
• a fountain solution composition according to the present invention can favorably use a food dye as a colorant, and examples thereof include, as a yellow dye, C.I. No. 19140, 15985; as a red dye, C.I. No. 16185, 45430, 16255, 45380, 45100; as a purple dye, C.I. No. 42640; as a blue dye, C.I. No. 42090, 73015; and as a green dye, C.I. No. 42095.
• an anti-corrosive agent usable according to the present invention include benzotriazole, 5-methylbenzotriazole, thiosalicylic acid, benzoimidazole, and a derivative thereof.
• a defoaming agent usable according to the present invention a silicone defoaming agent is preferable, for which both an emulsion type and a solution type can be used.
• the balance component of a fountain solution composition according to the present invention is water.
• a fountain solution composition for merchandizing a fountain solution composition is in general concentrated and packaged. Accordingly, the aforedescribed components are dissolved in water, preferably in desalted water, namely pure water, to an aqueous solution to prepare a concentrated solution. When such a concentrated solution is used, it is diluted generally before using by tap water, well water, etc. 10 to 200-fold, preferably approx. 30 to 100-fold, to a ready-for-use fountain solution composition.
• the present invention is also directed to a fountain solution composition for lithographic printing in a form of a concentrated solution.
• an appropriate concentration rate is selected so that deposition or liquid separation in a concentrated solution can be prevented, and that a ready-for-use fountain solution composition containing the components at proper concentrations can be prepared by dilution at a proper dilution rate.
• a concentrated fountain solution composition for lithographic printing according to the present invention there is a concentrated fountain solution containing the star polymer in a range of 0.5 to 10 mass-%.
• a further specific example include a formation containing the star polymer in a range of 0.5 to 10 mass-%, a compound according to the general formula (I) from 1 to 80 parts by mass with respect to 1 part by mass of the star polymer, a water soluble polymeric compound other than the star polymer from 0.5 to 10 parts by mass, at least one selected out of an organic acid, an inorganic acid, and a salt thereof from 0.5 to 10 parts by mass, an antiseptic agent from 0.1 to 2.0 parts by mass, optionally another component, and water as the balance.
• a formation containing the star polymer in a range of 0.5 to 10 mass-% a compound according to the general formula (I) from 1 to 80 parts by mass with respect to 1 part by mass of the star polymer, a water soluble polymeric compound other than the star polymer from 0.5 to 10 parts by mass, at least one selected out of an organic acid, an inorganic acid, and a salt thereof from 0.5 to 10 parts by mass, an antiseptic agent from 0.1 to 2.0 parts
• a fountain solution composition according to the present invention can be applied to various lithographic plates, it can be favorably applied especially to a lithographic plate prepared by exposing and developing an image on a photosensitive lithographic plate having a photosensitive layer on a substrate aluminum plate.
• a preferable PS plate include that with a photosensitive layer composed of a mixture of a diazo resin (a salt of a condensation product between p -diazodiphenylamine and paraformaldehyde) and shellac provided on an aluminum plate as described in GB Patent No.
• an alkali-soluble resin other than the alkali-soluble novolac resin can be added according to need.
• examples thereof include a styrene-acrylic acid copolymer, a methyl methacrylate-methacrylic acid copolymer, an alkali-soluble polyurethane resin, an alkali-soluble vinyl resin according to Japanese Published Examined Application 52-28401 , and an alkali-soluble polybutyral resin.
• a PS plate with a photosensitive layer composed of a mixture of an azide and a water-soluble polymer provided on an aluminum plate as described respectively in GB Patent No. 1,235,281 and GB Patent 1,495,861 are also preferable. Further, it is favorably applicable to a CTP plate, which is directly exposed by a visible or infrared laser.
• a photopolymer type digital plate e.g. LP-NX by Fujifilm Corporation
• a thermal positive type digital plate e.g. LH-PI by Fujifilm Corporation
• a type of plate, which is developed on a printing press by a fountain solution and an ink e.g. ET-S by Fujifilm Corporation
• a thermal negative-type digital plate e.g. LH-NI by Fujifilm Corporation
• the present invention will be described more specifically below by way of Examples and Comparative Examples, provided that the examples should not be considered to limit the scope of the invention in any way. While with respect to a macromolecular compound, unless otherwise specified, the molecular weight is in mass average molar mass (Mw), and the content of a recurring unit is in molar percentage.
• Mw mass average molar mass
• a 0.30 mm-thick aluminum plate (aluminum alloy containing Si: 0.09 mass-%, Fe: 0.30 mass-%, Cu: 0.013 mass-%, Mn: 0.001 mass-%, Mg: 0.001 mass-%, Zn: 0.001 mass-%, Ti: 0.027 mass-%, Al and incidental impurities: the balance) was subjected continuously to the following surface treatments (a) to (k) While a liquid was remove by nip rollers after respective treatments and water washing.
• a mechanical surface roughening treatment was carried out by a revolving roller-shaped nylon brush.
• the average particle size of the polishing material was 30 ⁇ m, and the maximum particle size was 100 ⁇ m.
• the material of the nylon brush was 6.10-nylon, the bristle length was 45 mm, and the bristle diameter was 0.3 mm.
• the nylon brush was constructed by boring holes in a 300 mm ⁇ -stainless steel cylinder and planting bristles dense thereto. Three revolving brushes were used.
• the brush roller was so pressed to an aluminum plate that the load of a driving motor for revolving the brush increased by 7 kW compared to the load before pressing.
• the rotational direction of the brush was identical with the travelling direction of an aluminum plate.
• the revolving rate of the brush was 200 rpm.
• the thus prepared aluminum plate was subjected to an etching treatment by spraying an aqueous solution of caustic soda at a concentration of 2.6 mass-%, and aluminum ion at a concentration of 6.5 mass-% at a temperature of 70°C to dissolve the aluminum plate by 10 g/m 2 . Thereafter it was washed by water spraying.
• a desmutting treatment was conducted by spraying an aqueous solution of 1 mass-% concentration nitric acid (containing 0.5 mass-% of aluminum ion) at a temperature of 30°C, followed by washing by water spraying.
• nitric acid used for the desmutting treatment was utilized a waste fluid from a process step, in which an electrochemical surface roughening treatment was carried out using alternating current in an aqueous solution of nitric acid.
• An electrochemical surface roughening treatment was conducted continuously using 60 Hz alternating voltage.
• the then electrolytic liquid was a 10.5 g/L nitric acid aqueous solution (containing 5 g/L of aluminum ion and 0.007 mass-% of ammonium ion) at the liquid temperature of 50°C.
• the electrochemical surface roughening treatment was conducted with a carbon electrode as a counter electrode using an alternating current power source giving trapezoidal (rectangular) alternating current with the TP of 0.8 msec (time from current zero to the peak current) and the duty ratio of 1/1.
• ferrite was used for an auxiliary anode.
• the current density at the current peak value was 30 A/dm 2
• the quantity of electricity as the total quantity of electricity when an aluminum plate was an anode was 220 C/dm 2 .
• To an auxiliary anode 5% of the current flown from the power source was shunted. Washing by water spraying was followed.
• An etching treatment was conducted on an aluminum plate at 32°C by spraying an aqueous solution of caustic soda at a concentration of 26 mass-%, and aluminum ion at a concentration of 6.5 mass-% to dissolve the aluminum plate by 0.50 g/m 2 , so that a smut component composed mainly of aluminum hydroxide formed during the upstream electrochemical surface roughening treatment using alternating current was removed, and the edges of formed pits were smoothed by dissolving the edges. Washing by water spraying was followed.
• a desmutting treatment was conducted at 30°C by spraying a 15 mass-% aqueous solution of nitric acid (containing 4.5 mass-% of aluminum ion), followed by washing by water spraying.
• nitric acid solution used for desmutting was utilized a waste fluid from a process step, in which an electrochemical surface roughening treatment was carried out using alternating current in an aqueous solution of nitric acid.
• An electrochemical surface roughening treatment was conducted continuously using 60 Hz alternating voltage.
• the then electrolytic liquid was a 5.0 g/L aqueous hydrochloric acid solution (containing 5 g/L of aluminum ion) at the temperature of 35°C.
• the electrochemical surface roughening treatment was conducted with a carbon electrode as a counter electrode using an alternating current power source giving trapezoidal (rectangular) alternating current with the TP of 0.8 msec (time from current zero to the peak current) and the duty ratio of 1/1.
• ferrite was used for an auxiliary anode.
• the current density at the current peak value was 25 A/dm 2
• the quantity of electricity as the total quantity of electricity when an aluminum plate was an anode was 50 C/dm 2 . Washing by water spraying was followed.
• An etching treatment was conducted on an aluminum plate at 32°C by spraying an aqueous solution of caustic soda at a concentration of 26 mass-%, and aluminum ion at a concentration of 6.5 mass-% to dissolve the aluminum plate by 0.10 g/m 2 , so that a smut component composed mainly of aluminum hydroxide formed during the upstream electrochemical surface roughening treatment using alternating current was removed, and the edges of formed pits were smoothed by dissolving the edges.
• a desmutting treatment was conducted at 60°C by spraying a 25 mass-% aqueous solution of sulfuric acid (containing 0.5 mass-% of aluminum ion), followed by washing by water spraying.
• An anodizing treatment was conducted using an anodizing apparatus (the 1st and the 2nd electrolytic part lengths 6 m respectively, the 1st and the 2nd power supply part lengths 3 m respectively, and the 1st and the 2nd power supply electrode part lengths 2.4 m respectively).
• anodizing apparatus As electrolytic solutions supplied to the 1 st and the 2nd electrolytic parts, sulfuric acid was used. For both the electrolytic solutions the concentration of sulfuric acid was 50 g/L (containing 0.5 mass-% of aluminum ion), and the temperature was 20°C. Washing by water spraying was followed.
• An alkali metal silicate treatment (silicate treatment) was conducted by immersing an aluminum substrate prepared by an anodizing treatment in a treatment bath wirh a 1 mass-% aqueous solution of disodium trisilicate at a temperature of 30°C for 10 sec. Thereafter washing was carried out by spraying well water to obtain a substrate with a surface hydrophilized by the silicate treatment.
• substrate S-1 An aluminum plate subjected to all the treatment steps of (a) to (k) was defined as substrate S-1, whose center line average roughness (arithmetic average roughness Ra according to JIS B0601) was measured using a needle with the diameter of 2 ⁇ m to find 0.50 ⁇ m for the substrate S-1.
• the following prime coat coating liquid (A) was applied on to the aluminum substrate S-1 subjected to the aforedescribed surface treatments, to a dry coating weight of 10 mg/m 2 , and followed by drying.
• polyvinylphosphonic acid (Mw 20000) 0.017 part by mass methanol 9.00 parts by mass water 1.00 part by mass
• the following coating liquid (A) for a photosensitive layer was prepared and coated by a wire bar coater on the prime coat prepared as above to form a photosensitive layer. Drying was carried out by a hot air dyer at 125°C for 34 sec. The coating weight after drying was 1.4 g/m 2 .
• infrared absorber IR-1) 0.038 part by mass polymerization initiator A (S-1) 0.061 part by mass polymerization initiator B (I-1) 0.094 part by mass mercapto compound (E-1) 0.015 part by mass ethylenic unsaturated compound (M-1) 0.425 part by mass (Trade name: A-BPE-4, by Shin-Nakamura Chemical Co., Ltd.) binder polymer A (B-1) (Mw: 110000) 0.311 part by mass binder polymer B (B-2) (Mw: 100000) 0.250 part by mass binder polymer C (B-3) (Mw: 120000) 0.062 part by mass additive (T-1) 0.079 part by mass polymerization inhibitor (Q-1) 0.0012 part by mass ethyl violet (EV-1) 0.021 part by mass fluorinated surfactant 0.0081 part by mass (Megafac F-780-F, by DIC; methyl isobutyl ketone (
• the structures of the infrared absorber (IR-1), the polymerization initiator A(S-1), the polymerization initiator B(I-1), the mercapto compound (E-1), the ethylenic unsaturated compound (M-1), the binder polymer A (B-1), the binder polymer B (B-2), the binder polymer C (B-3), the additive (T-1), the polymerization inhibitor (Q-1), and ethyl violet (EV-1) used for the coating liquid (A) for a photosensitive layer are shown below. While, in the following, Me represents a methyl group, and the ratios of respective monomer units of the binder polymers A to C shown below are in molar ratio.
• a mixed aqueous solution (a coating liquid for forming a lower protective layer) of synthetic mica (Somasif MEB-3L, 3.2 mass-% water dispersion, by Co-op Chemical Co., Ltd.), polyvinyl alcohol (Gohseran CKS-50, degree of saponification 99 mol-%, degree of polymerization 300, sulfonic acid modified polyvinyl alcohol, by The Nippon Synthetic Chemical Industry Co., Ltd.), a surfactant A (Emalex 710, by Nihon Emulsion Co., Ltd.), and a surfactant B (Adeka Pluronic P-84, by ADEKA Corporation) was coated by a wire bar coater and dried in a hot air dyer at 125°C for 30 sec.
• synthetic mica Somasif MEB-3L, 3.2 mass-% water dispersion, by Co-op Chemical Co., Ltd.
• polyvinyl alcohol Gohseran CKS-50, degree of saponification 99 mol-%, degree
• the content ratio of synthetic mica (solid portion)/polyvinyl alcohol/surfactant A/surfactant B was 7.5/89/2/1.5 (mass-%), and the coating amount (coating weight after drying) was 0.5 g/m 2 .
• an organic filler Article-Pearl J-7P, by Negami Chemical Industrial Co., Ltd.
• synthetic mica
• the content ratio of organic fille/synthetic mica (solid portion)/polyvinyl alcohol/thickening agent/surfactant was 3.2/2.0/80.5/11.5/2.8 (mass-%) and the coating amount (coating weight after drying) was 1.76 g/m 2 .
• the obtained lithographic original plate was treated following the sequence of the steps of exposure, developing treatment , and plate surface treatment.
• Image-wise exposure was carried out by a light source (setter) based on an infrared semiconductor laser (Trendsetter 3244VX: equipped with water-cooling 40 W infrared semiconductor laser, by Creo Inc. (Kodak)) under the conditions of the output power 9 W, the external drum rotation speed 210 rpm, and the resolution 2,400 dpi.
• As an exposed image an image with an array of reverse thin lines with the width of 5 to 100 ⁇ m (at intervals of 5 ⁇ m) was used as an image for a reverse thin line evaluation.
• For a plate life evaluation an image suitable for plate life evaluation of solid printing was used.
• a developing solution a 1/4 (by water) diluted solution of a developing solution HN-D (old trade name DH-N, by Fujifilm Corporation) was used.
• the pH of the developing solution was 12, and the temperature of a developing bath was 30°C.
• Printing was conducted by a printing press Lithron 26 (by Komori Corporation) using an ink Super Reoeco SOY Black L (by Toyo Ink Co., Ltd.), a lightweight coated paper OK Top Coat+ (by Oji Paper Co., Ltd.) and fountain solution composition.
• the used fountain solution composition is described below.
• propylene glycol mono- n -butyl ether 0.5 part by mass propylene glycol 0.5 part by mass any of star polymers in Table 7, or B-1 comparative polymer 0.02 part by mass carboxymethylcellulose 0.01 part by mass ammonium nitrate 0.05 part by mass citric acid 0.01 part by mass malic acid 0.01 part by mass 2,2-dibromo-2-nitroethano 0.001 part by mass benzotriazole 0.002 part by mass 2-methyl-5-chloro-4-isothiazolin-3-one 0.002 part by mass water add to 100 parts by mass
• Comparative polymer B-1 MW 100,000
• Evaluation-1 ⁇ Evaluation of ink removal at initial start of printing>
• Evaluation-2 ⁇ Evaluation of resistance to dirt at non-image area (Evaluation of resistance to dirt after break)>
• a lithographic plate original plate was subjected to forced aging at 60°C for 4 days, and then exposed and developed according to the above plate making process to obtain a lithographic plate.
• the plate was mounted on a printing press (2N-600, by Tohama Seiki Co.) and printing was conducted using a groundwood paper, an ink Soibi Red (by Inctec Inc.) and the fountain solution composition.
• the printing press was temporarily stopped and left standing for 5 hours, and then printing was restarted to print another 200 sheets.
• the sheet number until the ink disappeared completely from a non-image area was inspected (Table II). The smaller number means that the number of waste paper from the printing restart is fewer and therefore it is advantageous.
• Evaluation-3 ⁇ Evaluation of decrease in print density by increase in total component concentration of fountain solution>
• the evaluation item was evaluated by determining density decrease on a print when the total component concentration of a fountain solution composition was increased 2-, 3- and 4-fold, wherein the water scale of a printing press was changed to determine the minimum supply quantity of a fountain solution required for preventing dirt at a no-image area on a print.
• the water scale was firstly determined and then the solid image on the 500th print sheet was measured by a Macbeth densitometer (by Gretag Macbeth) With respect to the density of a solid printed part for the 1-fold case as 100, relative densities at a solid printed part for the 2-, 3-, and 4-fold cases are shown (Table III).
• Table II Evaluation of resistance to dirt at non-image area (Evaluation of resistance to dirt after break Example Various polymer Paper consumed for cleaning Example 1 P A -1 65 2 P A -2 55 3 P A -3 50 4 P A -4 55 5 P A -5 50 6 P A -6 60 Comparative example 1 B-1 90 2 none 130
• Table III Evaluation of decrease in print density by increase in total component concentration of fountain solution
• Example 1 P A -1 100 100 95 95 2 P A -2 100 100 100 95 3 P A -3 100 100 95 95 4 P A -4 100 100 95 90 5 P A -5 100 95 90 90 6 P A -6 100 95 95 95 Comparative example 1 B-1 100 85 75 75 2 none 100 100 95 90
• a thermal negative-type digital plate was prepared identically with Example 1 and plate making was carried out.
• Printing was carried out by a printing press Lithron 26 (by Komori Corporation) using an ink Super Reoeco SOY Black L (by Toyo Ink Co., Ltd.), a lightweight coated paper OK Top Coat+ (by Oji Paper Co., Ltd.), and a fountain solution composition.
• the used fountain solution composition is described below.
• Evaluation-1 to Evaluation-3 were conducted with respect to each fountain solution identically with Example 1. The results are shown in Tables IV to VI.
• the consumed sheet number at the initial start of printing as well as at a restart of printing after a stop for a certain period can be less than a half, namely very few. It is obvious that by a fountain solution composition using a star polymer according to the invention, the dirt resistance of a non-image area at the initial start of printing as well as at a restart of printing can be improved. Further, as obvious from Table VI, even if the component concentration of a fountain solution is increased up to about 4-fold, the density of a print is substantially not decreased to demonstrate an advantageous effect.

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