WO2007057410A1 - Procede de fabrication d'une plaque d'impression lithographique - Google Patents

Procede de fabrication d'une plaque d'impression lithographique Download PDF

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Publication number
WO2007057410A1
WO2007057410A1 PCT/EP2006/068492 EP2006068492W WO2007057410A1 WO 2007057410 A1 WO2007057410 A1 WO 2007057410A1 EP 2006068492 W EP2006068492 W EP 2006068492W WO 2007057410 A1 WO2007057410 A1 WO 2007057410A1
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WIPO (PCT)
Prior art keywords
precursor
layer
compound
coating
photopolymerizable layer
Prior art date
Application number
PCT/EP2006/068492
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English (en)
Inventor
Alexander Williamson
Marc Van Damme
Willi-Kurt Gries
Original Assignee
Agfa Graphics Nv
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from EP05111014A external-priority patent/EP1788449A1/fr
Application filed by Agfa Graphics Nv filed Critical Agfa Graphics Nv
Publication of WO2007057410A1 publication Critical patent/WO2007057410A1/fr

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Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/26—Processing photosensitive materials; Apparatus therefor
    • G03F7/30—Imagewise removal using liquid means
    • G03F7/3035—Imagewise removal using liquid means from printing plates fixed on a cylinder or on a curved surface; from printing cylinders
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/004—Photosensitive materials
    • G03F7/085—Photosensitive compositions characterised by adhesion-promoting non-macromolecular additives
    • 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
    • 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
    • B41C2201/00—Location, type or constituents of the non-imaging layers in lithographic printing formes
    • B41C2201/04—Intermediate layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
    • B41C2201/00—Location, type or constituents of the non-imaging layers in lithographic printing formes
    • B41C2201/14—Location, type or constituents of the non-imaging layers in lithographic printing formes characterised by macromolecular organic compounds, e.g. binder, adhesives
    • 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
    • B41C2210/04—Negative working, i.e. the non-exposed (non-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
    • B41C2210/08—Developable by water or the fountain 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
    • B41C2210/20—Preparation or type or constituents of the imaging layers, in relation to lithographic printing forme preparation characterised by inorganic additives, e.g. pigments, salts
    • 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

Definitions

  • the present invention relates to a method for making a lithographic printing plate whereby an negative-working photopolymer printing plate precursor is image-wise exposed, mounted on a press and processed on-press by applying ink and fountain to remove the unexposed areas from the support.
  • the coating of the precursor comprises a polymer having a cyclic vinyl amide monomeric unit having the structure of formula I .
  • a so-called printing master such as a printing plate is mounted on a cylinder of the printing press.
  • the master carries a lithographic image on its surface and a printed copy is obtained by applying ink to said image and then transferring the ink from the master onto a receiver material, which is typically paper.
  • ink as well as an aqueous fountain solution (also called dampening liquid) are supplied to the lithographic image which consists of oleophilic (or hydrophobic, i.e. ink-accepting, water-repelling) areas as well as hydrophilic (or oleophobic, i.e. water-accepting, ink-repelling) areas.
  • driographic the lithographic image consists of ink-accepting and ink-abhesive (ink- repelling) areas and during driographic printing, only ink is supplied to the master.
  • Printing masters are generally obtained by the so-called computer-to-film (CtF) method, wherein various pre-press steps such as typeface selection, scanning, color separation, screening, trapping, layout and imposition are accomplished digitally and each color selection is transferred to graphic arts film using an imagesetter.
  • the film can be used as a mask for the exposure of an imaging material called plate precursor and after plate processing, a printing plate is obtained which can be used as a master.
  • the so-called 'computer-to-plate' (CtP) method has gained a lot of interest.
  • This method also called ⁇ direct-to-plate' , bypasses the creation of film because the digital document is transferred directly to a printing plate precursor by means of a so-called plate-setter.
  • a printing plate precursor for CtP is often called a digital plate.
  • Digital plates can roughly be divided in three categories : (i) silver plates, which work according to the silver salt diffusion transfer mechanism; (ii) photopolymer plates which contain a photopolymerizable composition that hardens upon exposure to light and (iii) thermal plates of which the imaging mechanism is triggered by heat or by light-to-heat conversion.
  • Thermal plates are mainly sensitized for infrared lasers emitting at 830 nm or 1064 nm.
  • Photopolymers can be sensitized for blue, green or red light (i.e. wavelength range between 450 and 750 nm) , for violet light (i.e. wavelength range between 350 and 450 nm) or for infrared light (i.e. wavelength range between 750 and 1500 nm) .
  • Laser sources have been increasingly used to expose a printing plate precursor which is sensitized to a corresponding laser wavelength.
  • an Ar laser (488 nm) or a FD-YAG laser (532 nm) can be used for exposing a visible light sensitized photopolymer plate.
  • the wide-scale availability of low cost blue or violet laser diodes, originally developed for data storage by means of DVD, has enabled the production of plate- setters operating at shorter wavelength.
  • semiconductor lasers emitting from 350 to 450 nm have been realized using an InGaN material.
  • An infrared laser diode emitting around 830 nm or a Nd-YAG laser emitting around 1060 nm can also be used.
  • a photopolymer plate is processed in alkaline developer having a pH > 10 and subsequently gummed to protect the plate from contamination, e.g. by oxidation, fingerprints, fats, oil or dust, or from damaging, e.g. by scratches during handling of the plate.
  • Photopolymer plates are also described in the literature wherein the wet processing and gumming steps are replaced by an on- press processing whereby the imaged precursor is mounted on a press and processed on-press by applying ink and fountain to remove the unexposed areas from the support .
  • a compound for increasing the adhesion between the photopolymer coating and the support can also added to the printing plate precursor for increasing the resistance of the exposed areas during the processing step and for improving the durability of the plate in the printing process as disclosed in EP 851 299, EP 1 091 251, US 2004/214105, EP 1 491 356, US 2005/39620, EP 1 495 866, EP 1 500 498, EP 1 520 694 and EP 1 557 262.
  • the binder for the photopolymerisable layer may be selected from a broad list of polymers without limitations including linear organic polymers having film-forming properties or having crosslinkable functional groups.
  • polymers having hydrophilic groups include acrylic resins, methacrylic resins, polystyrene resins, novolac type resins, polyester resins, synthetic rubbers, natural rubber, and polymers having ethylenically unsaturated bonds.
  • Polymers having hydrophilic groups are preferred and specific examples of such hydrophilic polymers are listed in the literature.
  • Specific examples of such hydrophilic polymers are poly (meth) acrylic acid and salts thereof, polyvinyl alcohol, hydrolyzed polyvinyl acetate having a degree of hydrolysis of 60 % by weight or higher, preferably 80 % by weight or higher, polyvinylpyrrolidone and copolymers of polyvinylpyrrolidone.
  • hydrophilic polymers as binder in lithographic printing plate precursors is an insufficient clean-out of the non-exposed areas by means of fountain and ink in an on-press processing step, even after printing a high number of sheets .
  • This object is realized by the method of claim 1, having the specific feature that the photopolymerizable layer comprises a polymer comprising a cyclic vinyl amide monomeric unit of formula I.
  • the precursor further comprises a compound capable of interacting with the support, hereinafter also referred to as "adhesion promoting compound" , which is present in the photopolymerizable layer or in an intermediate layer between the photopolymerizable layer and the support.
  • a method of making a lithographic printing plate comprising the steps of: (a) providing a lithographic printing plate precursor comprising
  • a coating provided thereon comprising a photopolymerizable layer and, optionally, an intermediate layer between the photopolymerizable layer and the support, wherein said photopolymerizable layer comprises a polymerizable compound, a polymerization initiator and a polymer comprising a cyclic vinyl amide monomeric unit, wherein an adhesion promoting compound is present in the intermediate layer or in the photopolymerizable layer, wherein said adhesion promoting compound is a compound capable of interacting with said support, (b) image-wise exposing said precursor, (c) optionally, heating the precursor in a preheating unit, (d) mounting the exposed precursor on a plate cylinder of a lithographic printing press, (e) developing by rotating the plate cylinder while feeding dampening liquid and/or ink to the coating, thereby removing non- exposed areas of the coating, characterised in that said cyclic vinyl amide monomeric unit has the structure of formula I : (formula I)
  • the lithographic printing plate precursor used in the method of the present invention is negative-working and develops a lithographic image consisting of hydrophobic and hydrophilic areas at the exposed and non-exposed areas respectively.
  • the hydrophilic areas are defined by the support which has a hydrophilic surface or is provided with a hydrophilic layer.
  • the hydrophobic areas are defined by the coating, hardened upon exposing, optionally followed by a heating step.
  • hardened means that the coating becomes insoluble or non- dispersible for the fountain and ink on the press and may be achieved through polymerization and/or crosslinking of the coating, optionally followed by a heating step to enhance or to speed-up the polymerization and/or crosslinking reaction.
  • this optional heating step hereinafter also referred to as "pre-heat"
  • the plate precursor is heated, preferably at a temperature of about 80 0 C to 150 0 C and preferably during a dwell time of about 5 seconds to 1 minute .
  • a particularly preferred lithographic support is an electrochemically grained and anodized aluminum support. Graining an anodizing of aluminum supports is well known.
  • the acid used for graining can be e.g. nitric acid or sulfuric acid.
  • the acid used for graining preferably comprises hydrogen chloride. Also mixtures of e.g. hydrogen chloride and acetic acid can be used.
  • electrochemical graining and anodizing parameters such as electrode voltage, nature and concentration of the acid electrolyte or power consumption on the one hand and the obtained lithographic
  • the anodized aluminum support may be subject to a so-called post-anodic treatment to improve the hydrophilic properties of its surface.
  • the aluminum support may be silicated by treating its surface with a sodium silicate solution at elevated temperature, e.g. 95°C.
  • a phosphate treatment may be applied which involves treating the aluminum oxide surface with a phosphate solution that may further contain an inorganic fluoride.
  • the aluminum oxide surface may be rinsed with a citric acid or citrate solution. This treatment may be carried out at room temperature or may be carried out at a slightly elevated temperature of about 30 to 50 0 C.
  • a further interesting treatment involves rinsing the aluminum oxide surface with a bicarbonate solution.
  • the aluminum oxide surface may be treated with polyvinylphosphonic acid, polyvinylmethylphosphonic acid, phosphoric acid esters of polyvinyl alcohol, polyvinylsulfonic acid, polyvinylbenzenesulfonic acid, sulfuric acid esters of polyvinyl alcohol, and acetals of polyvinyl alcohols formed by reaction with a sulfonated aliphatic aldehyde.
  • Another useful post-anodic treatment may be carried out with a solution of polyacrylic acid or a polymer comprising at least 30 mol% of acrylic acid monomeric units, e.g. GLASCOL E15, a polyacrylic acid, commercially available from ALLIED COLLOIDS.
  • a solution of polyacrylic acid or a polymer comprising at least 30 mol% of acrylic acid monomeric units e.g. GLASCOL E15, a polyacrylic acid, commercially available from ALLIED COLLOIDS.
  • the grained and anodized aluminum support may be a sheet-like material such as a plate or it may be a cylindrical element such as a sleeve which can be slid around a print cylinder of a printing press .
  • the support can also be a flexible support, which may be provided with a hydrophilic layer, hereinafter called 'base layer' .
  • the flexible support is e.g. paper, plastic film or aluminum.
  • Preferred examples of plastic film are polyethylene terephthalate film, polyethylene naphthalate film, cellulose acetate film, polystyrene film, polycarbonate film, etc.
  • the plastic film support may be opaque or transparent .
  • the base layer is preferably a cross-linked hydrophilic layer obtained from a hydrophilic binder cross-linked with a hardening agent such as formaldehyde, glyoxal, polyisocyanate or a hydrolyzed tetra-alkylorthosilicate .
  • a hardening agent such as formaldehyde, glyoxal, polyisocyanate or a hydrolyzed tetra-alkylorthosilicate .
  • the thickness of the hydrophilic base layer may vary in the range of 0.2 to 25 ⁇ m and is preferably 1 to 10 ⁇ m. More details of preferred embodiments of the base layer can be found in e.g. EP-A 1 025 992.
  • the coating on the support comprises a photopolymerizable layer and, optionally, an intermediate layer between the photopolymerizable layer and the support.
  • the photopolymerizable layer comprises a polymerizable compound, a polymerization initiator capable of hardening said polymerizable compound in the exposed areas and a polymer comprising a cyclic vinyl amide monomeric unit of formula I as binder.
  • the coating further comprises an adhesion promoting compound, which is a compound capable of interacting with the support, and which is present in the photopolymerizable layer or in the intermediate layer.
  • the thickness of the coating preferably ranges between 0.4 and
  • the photopolymerizable layer has a coating thickness preferably
  • the optional intermediate layer has a coating thickness
  • the adhesion promoting compound is a compound capable of interacting with said support, preferably a compound having an addition-polymerizable ethylenically unsaturated bond and a functional group capable of interacting with the support, more preferably a functional group capable of interacting with a grained and anodised aluminium support.
  • a bond is formed which can be a covalent bond, an ionic bond, a complex bond, a coordinate bond or a hydrogen-bridge bond, and which can be formed by an adsorption process, a chemical reaction, an acid-base reaction, a complex- forming reaction or a reaction of a chelating group or a ligand.
  • the adhesion promoting compound is present in the photopolymerizable layer and/or in an intermediate layer between the photopolymerizable layer and the support.
  • the adhesion promoting compound may be selected from at least one of the low molecular weight compounds or polymeric compounds as described in EP-A 851 299 from lines 22 on page 3 to line 1 on page 4, EP-A 1 500 498 from paragraph [0023] on page 7 to paragraph [0052] on page 20, EP-A 1 495 866 paragraph [0030] on page 5 to paragraph [0049] on page 11, EP-A 1 091 251 from paragraph [0014] on page 3 to paragraph [0018] on page 20, and EP-A 1 520 694 from s paragraph [0023] on page 6 to paragraph [0060] on page 19.
  • Preferred compounds are those compounds which comprise a phosphate or phosphonate group as functional group capable of adsorbing on the aluminium support and which comprise an addition-polymerizable ethylenic double bond reactive group, especially those described in o EP-A 851 299 from lines 22 on page 3 to line 1 on page 4 and EP-A 1 500 498 from paragraph [0023] on page 7 to paragraph [0052] on page 20.
  • tri-alkyl- oxy silane groups hereinafter also referred to as "trialkoxy silane” groups, wherein the alkyl is preferably methyl or ethyl, or s wherein the trialkyloxy silane groups are at least partially hydrolysed to silanol groups, as functional group capable of adsorbing on the support, especially silane coupling agents having an addition-polymerizable ethylenic double bond reactive group as described in EP-A 1 557 262 paragraph [0279] on page 49 and EP-A 1 0 495 866 paragraph [0030] on page 5 to paragraph [0049] on page 11.
  • the adhesion promoting compound may be present in the photopolymerizable layer in an amount ranging between 1 and 50 wt%, preferably between 3 and 30 wt%, more preferably between 5 and 20 wt% of the non-volatile components of the composition. 5
  • the adhesion promoting compound may be present in the intermediate layer in an amount of at least 50 wt%, preferably at least 80 wt%, more preferably at least 90 wt%, most preferably 100 wt% of the non-volatile components of the composition.
  • said polymerizable monomer or oligomer is a monomer or oligomer comprising at least one epoxy or vinyl ether functional group and 5 said initiator is a Bronsted acid generator capable of generating free acid, optionally in the presence of a sensitizer, upon exposure, hereinafter said initiator also referred to as "cationic photoinitiator” or “cationic initiator” .
  • Suitable polyfunctional epoxy monomers include, for example, 3 , 4-epoxycyclohexylmethyl-3 , 4-epoxycyclohex-ane carboxylate , bis- (3,4 -epoxycyclohexymethyl) adipate, difunctional bisphenol Aepichlorohydrin epoxy resin and multifunctional epichlorohydrinitetraphenylol ethane epoxy resin.
  • Suitable cationic photoinitiators include, for example, triarylsulfonium hexafluoroantimonate, triarylsulfonium hexafluorophosphate, diaryliodonium hexafluoroantimonate, and haloalkyl substituted s-triazine. It is noted that most cationic initiators are also free radical initiators because, in addition to generating Bronsted acid, they also generate free radicals during photo or thermal decomposition.
  • said polymerizable monomer or oligomer is a ethylenically unsaturated compound, having at least one terminal ethylenic group, hereinafter also referred to as "free-radical polymerizable monomer”, and said initiator is a compound, capable of generating free radical, optionally in the presence of a sensitizer, upon exposure, hereinafter said initiator also referred to as "free radical initiator” .
  • Suitable free-radical polymerizable monomers include, for example, multifunctional (tneth) acrylate monomers (such as
  • the (meth) acrylic monomers may also have other double bond or epoxide group, in addition to (meth) acrylate group.
  • the (meth) acrylate monomers may also contain an acidic (such as carboxylic acid) or basic (such as amine) functionality.
  • Any free radical initiator capable of generating free radical directly or in the presence of a sensitizer upon exposure can be used as a free radical initiator of this invention.
  • Suitable free- radical initiators include, for example, the derivatives of acetophenone (such as 2 , 2-dimethoxy-2-phenylacetophenone, and 2- methyl-1- [4- (methylthio) phenyll-2-morpholino propan-1-one) ; benzophenone; benzil; ketocoumarin (such as 3-benzoyl-7-methoxy couraarin and 7-methoxy coumarin) ; xanthone; thioxanthone; benzoin or an alkyl-substituted anthraquinone ; onium salts (such as diaryliodonium hexafluoroantimonate, diaryliodonium triflate, (4- (2- hydroxytetradecyl-oxy) -phenyl) phenyliodonium
  • borate salts such as tetrabutylammonium triphenyl (n-butyl) borate, tetraethylaramonium triphenyl (n-butyl) borate, diphenyliodonium tetraphenylborate, and triphenylsulfonium triphenyl (n-butyl) borate, and borate salts as described in U.S. Pat. Nos .
  • haloalkyl substituted s-triazines such as 2 , 4-bis (trichloromethyl) -6- (p- methoxy-styryl) -s-triazine, 2 , 4-bis (trichloromethyl) -6- (4-methoxy- naphth-1-yl) -s-triazine, 2 , 4-bis (trichloromethyl) -6-piperonyl-s- triazine, and 2 , 4-bis (trichloromethyl) -6- [ (4 -ethoxy-ethylenoxy) - phen-1-yl] -s-triazine, and s-triazines as described in U.S.
  • the photopolymerizable composition according to the present invention comprises a hexaaryl-bisimidazole (HABI; dimer of triaryl -imidazole) compound as a photopolymerization initiator alone or in combination with further photoinitiators .
  • HABI hexaaryl-bisimidazole
  • a procedure for the preparation of hexaarylbisimidazoles is described in DE 1470 154 and their use in photopolymerizable compositions is documented in EP 24 629, EP 107 792, US 4 410 621, EP 215 453 and DE 3 211 312.
  • Preferred derivatives are e. g.
  • the amount of the HABI photoinitiator typically ranges from 0.01 to 30 % by weight, preferably from 0.5 to 20 % by weight, relative to the total weight of the non volatile components of the photopolymerizable composition.
  • a very high sensitivity can be obtained in the context of the present invention by the combination of an optical brightener as sensitizer and a hexaarylbisimidazole as photoinitiator.
  • Suitable classes of photoinitiators other than hexaarylbisimidazole compounds include aromatic ketones, aromatic onium salts, organic peroxides, thio compounds, ketooxime ester compounds, borate compounds, azinium compounds, metallocene compounds, active ester compounds and compounds having a carbon-halogen bond, but preferably the composition comprises a non-boron comprising photopolymerization initiator and particularly preferred the photopolymerization initiator comprises no boron comopound.
  • Many specific examples of photoinitiators suitable for the present invention can be found in EP-A 1 091 247. Other preferred initiators are trihalo methyl sulphones .
  • hexaarylbisimidazole compounds and/or metallocene compounds are used alone or in combination with other suitable photoinitiators, in particular with aromatic ketones, aromatic onium salts, organic peroxides, thio compounds, ketoxime ester compounds, azinium compounds, active ester compounds or compounds having a carbon halogen bond.
  • the hexaarylbisimidazole compounds make more than 50 mol-%, preferably at least 80 mol-% and particularly preferred at least 90 mol-% of all the photoinitiators used in the photopolymerizable composition of the present invention.
  • said polymerizable monomer or oligomer may be a combination of a monomer or oligomer comprising at least one epoxy or vinyl ether functional group and a polymerizable ethylenically unsaturated compound, having at least one terminal ethylenic group
  • said initiator may be a combination of a cationic initiator and a free-radical initiator.
  • a monomer or oligomer comprising at least one epoxy or vinyl ether functional group and a polymerizable ethylenically unsaturated compound, having at least one terminal ethylenic group can be the same compound wherein the compound contains both ethylenic group and epoxy or vinyl ether group.
  • Examples of such compounds include epoxy functional acrylic monomers, such as glycidyl acrylate.
  • the free radical initiator and the cationic initiator can be the same compound if the compound is capable of generating both free radical and free acid.
  • Examples of such compounds include various onium salts such as diaryliodonium hexafluoroantimonate and s-triazines such as 2 , 4-bis (trichloromethyl) -6- [ (4-ethoxyethylenoxy) -phen-1-yl] - s-triazine which are capable of generating both free radical and free acid in the presence of a sensitizer.
  • the photopolymerizable layer may also comprise a multifunctional monomer.
  • This monomer contains at least two functional groups selected from an ethylenically unsaturated group and/or an epoxy or vinyl ether group.
  • Particular multifunctional monomers for use in the photopolymer coating are disclosed in US 6,410,205 , US 5,049,479 , EP 1079276 , EP 1369232 , EP 1369231 EP 1341040 , US 2003/0124460 , EP 1241002 , EP 1288720 and in the reference book including the cited refences : Chemistry & Technology UV & EB formulation for coatings, inks & paints - Volume 2 - Prepolymers andReactive Diluents for UV and EB Curable Formulations by N.
  • urethane (meth) acrylate multifunctional monomers which can be used alone or in combination with other (meth) acrylate multifunctional monomers .
  • the photopolymerizable layer may also comprise a co- initiator .
  • a co-initiator is used in combination with a free radical initiator and/or cationic initator.
  • Particular co-initiators for use in the photopolymer coating are disclosed in US 6,410,205 , US 5,049,479 , EP 1079276 , 1369232 , EP 1369231 EP 1341040 , US 2003/0124460 , EP 1241002 , EP 1288720 and in the reference book including the cited refences : Chemistry & Technology UV & EB formulation for coatings, inks & paints - Volume 3 -Photoinitiators for Free Radical and Cationic Polymerisation by K. K. Dietliker - Edited by P. K. T. Oldring - 1991 - ISBN 0 947798161.
  • the photopolymerizable layer may also comprise an inhibitor.
  • Particular inhibitors for use in the photopolymer coating are disclosed in US 6,410,205, EP 1288720 and the unpublished patent application EP-A 04101955, filed on 6/5/2004.
  • the binder of the photopolymerizable layer in the present invention is a polymer comprising a cyclic vinyl amide monomeric unit of formula I.
  • n is 2, 3 or 4 in the cyclic vinyl amide monomeric unit of formula I.
  • n is 2 and a is 0.
  • Q is an alkyl group. Said alkyl group comprises preferably 1 to 40 carbon atoms, more preferably 2 to 35 carbon atoms, most preferably 3 to 30 carbon atoms.
  • the polymer of the present invention can be obtained by polymerizing or copolymerizing a cyclic vinyl amide monomer of formula II: (formula II)
  • the group Q is preferably substituted on the monomer before polymerization.
  • n is 2, 3 or 4 in the cyclic vinyl amide monomer of formula II.
  • n is 2 and a is 0.
  • n is 1 and a is 1 and Q is an alkyl group.
  • Said alkyl group comprises preferably 1 to 40 carbon atoms, more preferably 2 to 35 carbon atoms, most preferably 3 to 30 carbon atoms.
  • the group Q can also be substituted on monomeric units after formation of the polymer.
  • Examples of cyclic vinyl amide monomer of formula II are vinylpyrrolidone, vinylcaprolactam, and vinylpyrrolidone substituted by an alkyl group, hereinafter also referred to as "alkylated vinylpyrrolidone" , wherein the alkyl group preferably comprises 1 to 40 carbon atoms, more preferably 2 to 35 carbon atoms, most preferably 3 to 30 carbon atoms.
  • alkylated monomers can be obtained by a grafting reaction of an alfa-olefine, e.g. 1-butene, hexadecene, eicosene and tricontene, on the corresponding cyclic vinyl amide monomer.
  • an alfa-olefine e.g. 1-butene, hexadecene, eicosene and tricontene
  • the vinylpyrrolidone is preferably substituted in position 3 of the cyclic amide ring, i.e. the carbon atom neighbouring the carbonyl group of the cyclic amide.
  • the vinylpyrrolidone monomeric units in the polymer are substituted preferably for at least 5 mol% relative to the other monomeric units of the polymer, more preferably for an amount ranging between 10 and 95 mol% relative to the other monomeric units of the polymer.
  • the polymer of s the present invention may be obtained by polymerizing vinylcaprolactam in combination with other monomers, preferably in an amount ranging between 30 and 100 mol% of vinylcaprolactam, more preferably in an amount ranging between 60 and 100 mol% of vinylcaprolactam, most preferred in an amount ranging between 80 and o 100 mol% of vinylcaprolactam.
  • the polymer of the present invention may be obtained by polymerizing an alkylated vinylpyrrolidone in combination with other monomeric units, preferably in an amount ranging between 5 and 95 mol% of the alkylated vinylpyrrolidone, more preferably in an amount s ranging between 10 and 90 mol% of the alkylated vinylpyrrolidone, most preferred in an amount ranging between 20 and 80 mol% of the alkylated vinylpyrrolidone.
  • the coating comprising this polymer of the present invention in the photopolymerizable layer exhibits an excellent clean-out of the o non-exposed areas after a few number of printed sheets in the on- press processing step. Under clean-out is understood a complete removal of the coating on non-exposed areas by means of the fountain and ink in an on-press processing step, revealing the hydrophilic surface of the support. The non-exposed areas become hydrophilic, 5 accepting the fountain solution during printing.
  • POL-02 GANEX V-216 is a polyvinylpyrrolidone substituted by hexadecenyl groups for 80 %, commercially available from ISP.
  • POL-04: GANEX V-220 is a polyvinylpyrrolidone substituted by eicosenyl (C-20) groups for 80 %, commercially available from ISP.
  • POL- 05 GANEX WP- 660 is a polyvinylpyrrolidone substituted by triconenyl (C-30) groups for 80 %, commercially available from ISP.
  • POL-07 LUVITEC VPC55K65W is a copolymer of vinylcaprolactam and vinylpyrolidone, commercially available from BASF.
  • the average molecular weight M w of the polymers of the present invention ranges preferably between 1 000 and 500 000 g/mol, more preferably between 5 000 and 400 000 g/mol, most preferably between 10 000 and 250 000 g/mol.
  • the amount of the polymer of the present invention in the photopolymerizable layer preferably ranges from 10 to 90 % by weight, more preferably 20 to 80 % by weight, relative to the total weight of the non-volatile components of the composition.
  • the photopolymerizable layer may also further comprise an other binder in admixture with the polymer of the present invention.
  • the additional binder can be selected from a wide series of organic polymers. Compositions of different binders can also be used.
  • Useful additional binders include for example chlorinated polyalkylene (in particular chlorinated polyethylene and chlorinated polypropylene) , polymethacrylic acid alkyl esters or alkenyl esters (in particular polymethyl (meth) acrylate, polyethyl (meth) acrylate , polybutyl (meth) acrylate, polyisobutyl (meth) acrylate, polyhexyl (meth) acrylate, poly (2-ethylhexyl) (meth) acrylate and polyalkyl (meth) acrylate copolymers of (meth) acrylic acid alkyl esters or alkenyl esters with other copolymerizable monomers (in particular with (met)
  • binders containing carboxyl groups are binders containing carboxyl groups, in particular copolymers containing monomeric units of ⁇ , ⁇ -unsaturated carboxylic acids or monomeric units of ⁇ , ⁇ -unsaturated dicarboxylic acids (preferably acrylic acid, methacrylic acid, crotonic acid, vinylacetic acid, maleic acid or itaconic acid) .
  • copolymers are to be understood in the context of the present invention as polymers containing units of at least 2 different monomers, thus also terpolymers and higher mixed polymers.
  • Particular examples of useful copolymers are those containing units of (meth) acrylic acid and units of alkyl
  • (meth) acrylates allyl (meth) acrylates and/or (meth) acrylonitrile as well as copolymers containing units of crotonic acid and units of alkyl (meth) acrylates and/or (meth) acrylonitrile and vinylacetic acid/alkyl (meth) acrylate copolymers.
  • copolymers containing units of maleic anhydride or maleic acid monoalkyl esters are, for example, copolymers containing units of maleic anhydride and styrene, unsaturated ethers or esters or unsaturated aliphatic hydrocarbons and the esterification products obtained from such copolymers.
  • binders are products obtainable from the conversion of hydroxyl-containing polymers with intramolecular dicarboxylic anhydrides.
  • Further useful binders are polymers in which groups with acid hydrogen atoms are present, some or all of which are converted with activated isocyanates. Examples of these polymers are products obtained by conversion of hydroxyl- containing polymers with aliphatic or aromatic sulfonyl isocyanates or phosphinic acid isocyanates.
  • polymers with aliphatic or aromatic hydroxyl groups for example copolymers containing units of hydroxyalkyl (meth) acrylates , allyl alcohol, hydroxystyrene or vinyl alcohol, as well as epoxy resins, provided s they carry a sufficient number of free OH groups.
  • Particular useful binder and particular useful reactive binders are disclosed in EP 1 369 232, EP 1 369 231, EP 1 341 040, US 2003/0124460, EP 1 241 002, EP 1 288 720, US 6,027,857, US 6,171,735 and US 6,420,089.
  • binders are copolymers of vinylacetate and o vinylalcohol , preferably comprising vinylalcohol in an amount of 10 to 98 mol% vinylalcohol, more preferably between 35 and 95 mol %, most preferably 40 and 75 mol % vinylalcohol.
  • the ester-value, measured by the method as defined in DIN 53 401, of the copolymers of vinylacetate and vinylalcohol ranges preferably between 25 and s 700 mg KOH/g, more preferably between 50 and 500 mg KOH/g, most preferably between 100 and 300 mg KOH/g.
  • the viscosity of the copolymers of vinylacetate and vinylalcohol are measured on a 4 % by weight aqueous solution at 20°C as defined in DIN 53 015 and the viscosity ranges preferably between 3 and 60 mPa.s, more preferably 0 between 4 and 30 mPa.s, most preferably between 5 and 25 mPa.s.
  • the average molecular weight M w of the copolymers of vinylacetate and vinylalcohol ranges preferably between 5 000 and 500 000 g/mol , more preferably between 10 000 and 400 000 g/mol, most preferably between 15 000 and 250 000 g/mol. 5
  • Other suitable binders are disclosed in EP 152 819 Bl on page 2 lines 50-page 4 line 20, and in EP 1 043 627 Bl on paragraph [0013] on page 3.
  • the polymeric binder may also comprise a hydrophobic backbone, and pendant groups including for example a hydrophilic poly (alkylene 0 oxide) segment.
  • the polymeric binder may also include pendant cyano groups attached to the hydrophobic backbone.
  • a combination of such binders may also be employed.
  • the polymeric binder is a solid at room temperature, and is typically a non-elastomeric thermoplastic.
  • the polymeric binder comprises both hydrophilic and s hydrophobic regions, which is thought to be important for enhancing differentiation of the exposed and unexposed areas by facilitating developability .
  • the polymeric binder is characterized by a number average molecular weight (Mn) in the range from about 10.000 to 250.000, more commonly in the range from about 25.000 to 200.000.
  • the polymerizable composition may comprise discrete particles of the polymeric binder.
  • the discrete particles are particles of the polymeric binder which are suspended in the polymerizable composition. The presence of discrete particles tends to promote developability of the unexposed areas.
  • Specific examples of the polymeric binders according to this embodiment are described in US 6.899.994, 2004/0260050, US2005/0003285 , US2005/0170286 and US2005/0123853.
  • the imageable layer may optionally comprise one or more co-binders.
  • co-binders are water-soluble or water- dispersible polymers, such as, cellulose derivatives, poly vinyl alcohol, poly acrylic acid poly (meth) acrylic acid, poly vinyl pyrrolidone, polylactide, poly vinyl phosphonic acid, synthetic copolymers, such as the co-polymer of an alkoxy polyethylene glycol (meth) acrylate .
  • specific examples of co-binders are described in US2004/0260050, US2005/0003285 and US2005/0123853.
  • Printing plate precursors the imageable layer of which comprises a binder and optionally a co-binder according this embodiment and described in more detail in US2004/0260050 , US2005/0003285 and US2005/0123853 , optionally comprises a topcoat and an interlayer.
  • Nonionic surfactants are preferred.
  • Preferred nonionic surfactants are polymers and oligomers containing one or more polyether (such as polyethylene glycol, polypropylene glycol, and copolymer of ethylene glycol and propylene glycol) segments.
  • nonionic surfactants are block copolymers of propylene glycol and ethylene glycol (also called block copolymer of propylene oxide and ethylene oxide) ; ethoxylated or propoxylated acrylate oligomers; and polyethoxylated alkylphenols and polyethoxylated fatty alcohols.
  • the nonionic surfactant is preferably added in an amount ranging between 0.1 and 30% by weight of the coating, more preferably between 0.5 and 20%, and most preferably between 1 and 15%.
  • the photocurable composition may also comprise a sensitizer.
  • a sensitizer are violet light absorbing sensitizers, having an absorption spectrum between 350 nm and 450 nm, preferably between 370 nm and 420 nm, more preferably between 390 nm and 415 nm.
  • Particular preferred sensitizers are disclosed in EP 1 349 006 paragraph [0007] to [0009], EP-A-3103499, filed on 22/03/2003, and WO2004/047930 , including the cited references in these patent applications.
  • sensitizers are infrared light absorbing dyes, having an absorption spectrum between 750 nm and 1300 nm, preferably between 780 nm and 1200 nm, more preferably between 800 nm and 1100 nm.
  • Particular preferred sensitizers are heptamethinecyane dyes, specially the dyes disclosed in EP 1 359 008 paragraph [0030] to [0032] .
  • Other preferred sensitizers are blue, green or red light absorbing sensitizers, having an absorption spectrum between 450 nm and 750 nm.
  • Useful sensitizers can be selected from the sensitizing dyes disclosed in US 6,410,205, US 5,049,479, EP 1 079 276, EP 1 369 232, EP 1 369 231, EP 1 341 040, US 2003/0124460, EP 1 241 002 and EP 1 288 720.
  • the photopolymerizable layer or another layer of the coating may also comprise a printing-out agent, i.e. a compound which is capable of changing the color of the coating upon exposure.
  • a printing-out agent i.e. a compound which is capable of changing the color of the coating upon exposure.
  • a visible image is produced, hereinafter also referred to as "print-out image” .
  • the contrast of the image formed after exposure has to be as high as possible. This enables the end-user to establish immediately whether or not the precursor has already been exposed, to inspect the image quality on the printing plate and to distinguish the different color selections. Since development of the plate is not carried out before starting the printing process, a previous inspection and discrimination of the plate is not possible unless a print-out image is formed by the image-wise exposure.
  • a high contrast of the printout image is defined by a color distance of at least 3, measured between the exposed and non-exposed areas, preferably at least 4.
  • the color distance is defined by the CIE color coordinates, lightness and chroma, as described by CIE 15.2-1986: Colorimetry, CIE 1116-1995: Industrial Colour Difference Evaluation, or R. W. G. Hunt in Measuring Colour, second edition, edited in 1992 by Ellis Horwood Limited, England, and are calculated from the spectral density curve of the exposed and non-exposed areas following the "CIE 1976 Colour Difference" formulae as described in the same document .
  • the printing-out agent may be a compound as described in EP-A-I 491 356 paragraph [0116] to [0119] on page 19 and 20, and in US 2005/8971 paragraph [0168] to [0172] on page 17.
  • Preferred printing- out agents are the compounds described in the unpublished PCT Application PCT/EP 2005/053141, filed on 1 July 2005, from line 1 page 9 to line 27 page 20. More preferred are the IR-dyes as described in the unpublished Patent Application EP 05 105 440.1, filed on 21 June 2005, from line 32 page 5 to line 9 page 32.
  • the IR-dyes of this application may be added to the coating of the present invention or may replace, at least partially, the IR- absorbing compound present in the coating of the present invention.
  • the photopolymerizable layer or another layer of the coating may also comprise a colorant.
  • the colorant can be a dye or a pigment.
  • a dye or pigment can be used as a colorant when the layer, comprising the dye or pigment, is colored for the human eye.
  • the colorant can be a pigment.
  • Various types of pigments can be used such as organic pigments, inorganic pigments, carbon black, metallic powder pigments and fluorescent pigments.
  • Organic pigments are preferred.
  • organic pigments include quinacridone pigments, quinacridonequinone pigments, dioxazine pigments, phthalocyanine pigments, anthrapyrimidine pigments, anthanthrone pigments, indanthrone pigments, flavanthrone pigments, perylene pigments, diketopyrrolopyrrole pigments, perinone pigments, quinophthalone pigments, anthraquinone pigments, thioindigo pigments, benzimidazolone pigments, isoindolinone pigments, azomethine pigments, and azo pigments.
  • pigments usable as colorant are the following (herein is C.I. an abbreviation for Color Index; under a Blue colored pigment is understood a pigment that appears blue for the human eye,- the other colored pigments have to be understood in an analogue way) :
  • C.I. Pigment Red 5 C.I. Pigment Red 7, C.I. Pigment Red 12, C.I. Pigment Red 48 (Ca), C.I. Pigment Red 48 (Mn), C.I. Pigment Red 57 (Ca), C.I. Pigment Red 57 : 1, C.I. Pigment Red 112, C.I. Pigment Red 122, C.I. Pigment Red 123, C.I. Pigment Red 168, C.I. Pigment Red 184, C.I. Pigment Red 202, and C.I. Pigment Red 209;
  • Orange colored pigments include C.I. Pigment Orange 36, C.I. Pigment Orange 43, and a mixture of these pigments.
  • Green colored pigments include C.I. Pigment Green 7, C.I. Pigment Green 36, and a mixture of these pigments;
  • Black colored pigments include: those manufactured by Mitsubishi Chemical Corporation, for example, No. 2300, No. 900, MCF 88, No. 33, No. 40, No. 45, No. 52, MA 7 , MA 8 , MA 100, and No. 2200 B; those manufactured by Columbian Carbon Co., Ltd., for example, Raven 5750, Raven 5250, Raven 5000, Raven 3500, Raven 1255, and Raven 700; those manufactured by Cabot Corporation, for example, Regal 400 R, Regal 330 R, Regal 660 R, Mogul L, Monarch 700, Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, and Monarch 1400; and those manufactured by Degussa, for example, Color Black FW 1, Color Black FW 2, Color Black FW 2 V, Color Black FW 18, Color Black FW 200, Color Black S 150, Color Black S 160, Color Black S 170, Printex 35, Printex U, Printex V, Printex 140 U, Special Black 6, Special Black 5, Special Black 4
  • pigments such as brown pigments, violet pigments, fluorescent pigments and metallic powder pigments can also be used as colorant.
  • the pigments may be used alone or as a mixture of two or more pigments as colorant. Blue colored pigments, including cyan pigments, are preferred.
  • the pigments may be used with or without being subjected to surface treatment of the pigment particles.
  • the pigments are subjected to surface treatment.
  • Methods for surface treatment include methods of applying a surface coat of resin, methods of applying surfactant, and methods of bonding a reactive material (for example, a silane coupling agent, an epoxy compound, polyisocyanate, or the like) to the surface of the pigment.
  • a reactive material for example, a silane coupling agent, an epoxy compound, polyisocyanate, or the like
  • Suitable examples of pigments with surface treatment are the modified pigments described in WO 02/04210. Specifically the blue colored modified pigments described in WO 02/04210 are preferred as colorant in the present invention.
  • the pigments have a particle size which is preferably less than 10 ⁇ m, more preferably less than 5 ⁇ m and especially preferably less than 3 ⁇ m.
  • the method for dispersing the pigments may be any known dispersion method which is used for the production of ink or toner s or the like.
  • Dispersing machines include an ultrasonic disperser, a sand mill, an attritor, a pearl mill, a super mill, a ball mill, an impeller, a dispenser, a KD mill, a colloid mill, a dynatron, a three-roll mill and a press kneader. Details thereof are described in " Latest Pigment Applied Technology" (CMC Publications, published o in 1986) .
  • a dispersing agent may be omitted in the preparation of dispersions of so-called self -dispersing pigments.
  • Specific examples of self-dispersing pigments are pigments with are subjected to a surface treatment in such a way the pigment surface is compatible s with the dispersing liquid.
  • Typical examples of self -dispersing pigments in an aqueous medium are pigments which have ionic or ionisable groups or polyethyleneoxide chains coupled to the particle-surface. Examples of ionic or ionisable groups are acid groups or salts thereof such as carboxylic acid group, sulphonic 0 acid, phosphoric acid or phosphonic acid and alkali metal salts of these acids.
  • Suitable examples of self-dispersing pigments are described in WO 02/04210 and these are preferred in the present invention.
  • the blue colored self-dispersing pigments in WO 02/04210 are preferred. 5
  • the amount of pigment in the coating may be in the
  • 2 2 2 2 range of about 0.005 g/m to 2 g/m , preferably about 0.007 g/m to
  • the colorant can also be a dye.
  • Any known dyes such as 0 commercially available dyes or dyes described in, for example, "Dye Handbook" (edited by the Organic Synthetic Chemistry Association, published in 1970) which are colored for the human eye, can be used as colorant in the photopolymerizable coating.
  • Specific examples thereof include azo dyes, metal complex salt azo dyes, pyrazolone azo dyes, anthraquinone dyes, phthalacyanine dyes, carbionium dyes, quinonimine dyes, methine dyes, and the like.
  • Plithalocyanine dyes are preferrred.
  • Suitable dyes are salt-forming organic dyes and may be selected from oil -soluble dyes and basic dyes. Specific examples thereof are (herein is CI an abbreviation for Color Index) : Oil
  • the amount of dye in the coating may be in the range
  • the top layer is the top layer
  • the coating may comprise a top layer which acts as an oxygen barrier layer, hereinafter also referred to as "overcoat layer” or “overcoat” .
  • Preferred binders which can be used in the top layer are polyvinyl alcohol and the polymers disclosed in EP-A-3103498 , filed on 22/03/2003, US 6,410,205 and EP 1 288 720, including the cited references in these patents and patent applications.
  • the most preferred binder for the toplayer is polyvinylalcohol .
  • the polyvinylalcohol has preferably an hydrolysis degree ranging between 74 mol % and 99 mol %.
  • the weight average molecular weight of the polyvinylalcohol can be measured by the viscosity of an aqueous solution, 4 % by weight, at 20 0 C as defined in DIN 53 015, and this viscosity number ranges preferably between 3 and 26, more preferably between 3 and 15, most preferably between 3 and 10.
  • the coating thickness of the top layer is preferably between
  • the toplayer has a coating thickness
  • the toplayer comprises a polyvinylalcohol having an hydrolysis degree ranging between 74 mol % and 99 mol % and a viscosity number as defined above ranging between 3 and 26.
  • the composition and the thickness of of the toplayer are optimised in order to obtain a high sensitivity, a good daylight stability and less or no contamination of fountain and/or ink during on-press processing.
  • the toplayer comprises less polyvinylalcohol and polyvinylalcohol with a lower molecular weight, preferably a viscosity number of less than 26, more preferably less than 10 is used and a thickness as low as possible but more than 0.25 g/m .
  • the good oxygen barrier is desired, using a polyvinylalcohol with a high hydrolysis degree, preferably 88-98%, and a bigger thickness or the toplayer.
  • small penetration of oxygen is desired by a using an oxygen barrier with reduced barrier property for oxygen, preferably by using a smaller thickness of the toplayer and with polyvinylalcohol having a lower hydrolysis degree. Due to a good balance of these elements, an optimised property for the precursor can be obtained.
  • the top layer may also comprise a component selected from the compounds of a gum solution as disclosed in the unpublished PCT Application PCT/EP 2005/052298, filed on 18 May 2005, from lines 1 on page 5 to line 35 on page 11.
  • the image-wise exposing step can be carried out off-press in a plate setter, i.e. an exposure apparatus suitable for image-wise exposing the precursor by a laser such as a laser diode, emitting around 830 nm, a NdYAG laser, emitting around 1060 nm, a violet laser, emitting around 400 nm or a gas laser such as Ar laser, by digital modulated UV-exposure, e.g. by means of digital mirror devices, or by a conventional exposure in contact with a mask.
  • the precursor is image-wise exposed by a laser emitting IR- light or violet light.
  • the image-wise exposing step can also carried-out in an on press configuration whereby the precursor is mounted on a plate cylinder and image-wise exposed with a laser.
  • the precursor may be heated in a preheating unit to enhance or to speed-up the polymerization and/or crosslinking reaction.
  • this preheat step may be carried out within a time period of less than 10 minutes, preferably less than 5 minutes, more preferably less than 1 minute, most preferably the preheat is carried out immediately after the image-wise exposing, i.e. within less than 30 seconds.
  • the precursor is heated as soon as possible after exposing, usually after a few seconds to transport the plate to the preheating unit and start the heating process.
  • the precursor is heated at a temperature of preferably 80 0 C to 15O 0 C and during a dwell time of preferably 5 seconds to 1 minute.
  • the preheating unit is preferably provided with heating elements such as IR- lamps, UV-lamps, heated air, a heated metal roll, etc.
  • the exposed, optionally exposed and preheated, precursor is processed on-press, i.e. while the precursor is mounted on the plate cylinder of a lithographic printing press, by rotating said plate cylinder while feeding dampening liquid and/or ink to the coating of the precursor.
  • dampening liquid is supplied to the plate during start-up of the press.
  • the ink supply is switched on.
  • supply of dampening liquid and ink can be started simultaneously or only ink can be supplied during a number of revolutions before switching on the supply of dampening liquid.
  • the precursor may be exposed and processed on-press, i.e. after step (a) and before step (b) , an additional step (a' ) is provided wherein the precursor is mounted on a plate cylinder of a lithographic printing press, and wherein step (d) is not present; optionally, after step (b) and before step (e) , an additional pre-heat step (c') is provided.
  • the image-wise exposed precursor is heated at a temperature ranging between 80 and 15O 0 C during a dwell time of 5 seconds to 1 minute, and within a time period preferably of less than 5 minutes, more preferably less than 1 minute, most preferably the preheat is carried out immediately after the image-wise exposing, i.e. within less than 30 seconds .
  • a 0.3 mm thick aluminum foil was degreased by spraying with an aqueous solution containing 34 g/1 of NaOH at 70°C for 6 seconds and rinsed with demineralized water for 3.6 seconds.
  • the foil was then electrochemically grained during 8 seconds using an alternating current in an aqueous solution containing 15 g/1 of HCl, 15 g/1 of SO 4 2" ions and 5 g/1 of Al 3+ ions at a temperature of 37 0 C and a current density of about 100 A/dm .
  • the aluminum foil was desmutted by etching with an aqueous solution containing 145 g/1 of sulfuric acid at 8O 0 C for 5 seconds and rinsed with demineralized water for 4 seconds.
  • the foil was subsequently subjected to anodic oxidation during 10 seconds in an aqueous solution containing 145 g/1 of sulfuric acid at a temperature of 57 0 C and a current density of 33 A/dm , then washed with demineralized water for 7 seconds and post-treated for 4 seconds by spraying a solution containing 2.2 g/1 of polyvinylphosphonic acid at 70 0 C, rinsed with demineralized water for 3.5 seconds and dried at 120 0 C for 7 seconds.
  • the support thus obtained was characterized by a surface roughness Ra of 0.35 a 0.4 ⁇ m, measured with interferometer NTIlOO, and had an anodic weight of 4.0 g/m 2 .
  • this support is carried out in the same way as described for support S-I with the exception that the polyvinyl phosphonic acid layer is partially removed by treatment with PD91, a water-based alkaline developer solution, commercially available from Agfa-Gevaert , followed by washing with water.
  • a 0.3 mm thick aluminum foil was degreased by spraying with an aqueous solution containing 34 g/1 of NaOH at 7O 0 C for 6 seconds and rinsed with demineralized water for 3.6 seconds.
  • the foil was then electrochemically grained during 8 seconds using an alternating current in an aqueous solution containing 15 g/1 of HCl, 15 g/1 of SO 4 ⁇ ions and 5 g/1 of Al ions at a temperature of 37 0 C and a current density of about 120-130 A/dm 2 .
  • the aluminum foil was desmutted by etching with an aqueous solution containing 145 g/1 of sulfuric acid at 80 0 C for 5 seconds and rinsed with demineralized water for 4 seconds.
  • the foil was subsequently subjected to anodic oxidation during 10 seconds in an aqueous solution containing 145 g/1 of sulfuric acid at a temperature of 57 0 C and a current density of 25 A/dm 2 , then washed with demineralized water for 7 seconds and post-treated for 4 seconds by spraying a solution containing 2.2 g/1 of polyvinylphosphonic acid at 70 0 C, rinsed with demineralized water for 3.5 seconds and dried at 12O 0 C for 7 seconds.
  • the support thus obtained was characterized by a surface roughness Ra of 0.50 a 0.65 ⁇ m, measured with interferometer NTIlOO, and had an anodic weight of 3.0 g/m .
  • Preparation of aluminum support S-4 The preparation of this support is carried out in the same way as described for support S-3 with the exception that the polyvinyl phosphonic acid layer is partially removed by treatment with PD91, a water-based alkaline developer solution, commercially available from Agfa-Gevaert , followed by washing with water.
  • the coating compositions for the intermediate layers 1-1 to 1-3 were prepared by mixing the ingredients as specified in Table 1. The resulting solutions were coated with a bar-coater on a support. After coating, the plate was dried for 1 minute at 12O 0 C in a circulation oven.
  • Table 1 Compositions of the intermediate layer solutions and thickness of dried layer.
  • Sipomer PAM 100 is a phosphate functional speciality methacrylate monomer, obtained from RHODIA. This compound was treated by extraction with methyl-tert-butylether, collection of the lower phase, and subsequent addition of 250 ppm (parts per million) of para-methoxyphenol .
  • Dowanol PM is propylene glycol monomethylether , trade mark of Dow Chemical Company.
  • Preparation of photosensitive layers P-I to P-7 The coating compositions for the photosensitive layers P-I to P-7 were prepared by mixing the ingredients as specified in Table 2. The resulting solutions were coated with a bar-coater on a support or on an intermediate layer. After coating, the plate was dried for 1 minute at 120 0 C in a circulation oven. The resulting applied amount is and 1.50 g/m for the photosensitive layers.
  • the high hydrophilic binders used in P- 5 and P- 6 are incompatible with the photosensitive composition resulting in flocculation of composition (see further in Table 4) .
  • Table 2 Compositions of the photosensitive layer solutions.
  • ANTARON V220 is a polyvinylpyrrolidone grafted with eicosene, commercially available from MAPRIC
  • ANTARON V904 is a butylated polyvinylpyrrolidone, commercially available from MAPRIC
  • LUVITEC VCAPK43E is a 40% by weight solution in isopropanol of polyvinylcaprolactam, commercially available from ISP
  • LUVITEC K30 is a polyvinylpyrrolidone, commercially available from BASF
  • Mowiol 4/88 is a polyvinylalcohol having a hydrolysis degree of 88 mol%, commercially available from Clariant
  • Mowiol 6/98 is a polyvinylalcohol having a hydrolysis degree of 98 mol%, commercially available from Clariant
  • KL 7177 is a solution containing 32.4 wt . % of a methylmethacrylate/methacrylic acid copolymer (ratio 4:1 by weight; acid number: 110 mg KOH/g) in 2 -butanone (viscosity 105 mrnVs at 25 0 C)
  • IR-dye-01 has the following structure
  • OTos represents a tosylate anion
  • TBMPS is tri-bromo-methylphenyl-sulphone
  • FST 426R is a solution in 2-butanone containing 88.2 wt . % of a reaction product from 1 mole of 2 , 2 , 4-trimethyl- hexamethylenediisocyanate and 2 moles of hydroxy- ethylmethacrylate (viscosity 3.30 mm /s at 25 0 C) ;il)
  • Edaplan LA411 is a surfactant (1 % solution in Dowanol PM® trade mark of Dow Chemical Company) obtained from Munzing Chemie .
  • Table 3 Composition of overcoat solution.
  • Acticide LA1206 is a biocide, commercially available from Thor
  • Metolat FC 355 is an ethoxylated ethylenediamine, commercially available from M ⁇ nzing Chemie
  • Lupasol P is a solution of 50% by weight of a polyethylene imine in water, commercially available from BASF (4) Lutensol A8 (90%) is a surface active agent, commercially available from BASF
  • the plates were imaged with a Creo Trendsetter IR laser (830 nm) at different energies varying between 100 mJ/cm and 300 mJ/cm 2 .
  • the clean-out is defined by the number of sheets needed to obtain on the non-exposed areas on optical density of 0.0 while on the full exposed areas (or the 100 % dot areas of a screen) the optical density is at least 1.5, indicating an excellent ink- acceptance.
  • the indication ⁇ 5 means that a full clean-out is obtained after printing 2, 3 or 4 sheets; >1000 means that no clean- out is obtained after printing 1000 sheets.
  • the sensitivity is defined as the minimum exposing energy at which the 2% dots of a 200 lpi screen were still present on the printed paper after 1000 prints.
  • Table 4 summarizes the compositions of the printing plate precursors and the obtained results.
  • the invention examples in Table 4 demonstrate that printing plate precursors comprising a binder of the present invention in the photopolymerizable layer and having an adhesion promoting compound in an intermediate layer, exhibit an excellent clean-out in the on- press processing: a full clean-out is obtained after printing less than 5 sheets. In the comparative examples, no clean-out can be obtained, even after printing a high number of sheets, or no printing plate precursor can be prepared due to flocculation of the coating solution of the photopolymerizable layer.

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  • General Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Materials For Photolithography (AREA)

Abstract

L'invention concerne un procédé de fabrication d'une plaque d'impression lithographique qui comprend les étapes consistant: a) à produire un précurseur de plaque d'impression lithographique comportant (i) un support à surface hydrophile ou qui est revêtu d'une couche hydrophile, (ii) un revêtement placé sur celui-ci, comportant une couche photopolymérisable, et éventuellement, une couche intermédiaire entre la couche polymérisable et le support, cette couche photopolymérisable contenant un composé polymérisable, un initiateur de polymérisation et un polymère comprenant une unité monomère d'amide vinylique cyclique, un composé favorisant l'adhésion étant présent dans la couche intermédiaire ou la couche photopolymérisable, ce composé consistant en un composé pouvant interagir avec le support, b) à exposer ce revêtement à l'image, c) à éventuellement chauffer le précurseur dans une unité de préchauffage, d) à monter le précurseur exposé sur un cylindre porte-plaque d'une presse lithographique, e) à développer par rotation le cylindre porte-plaque tout en alimentant le revêtement en liquide d'amortissement et/ou en encre, éliminant ainsi les zones non exposées du revêtement, caractérisées en ce que l'unité monomère d'amide vinylique cyclique possédant la structure de la formule (I) dans laquelle n prend la valeur d'un entier = 1, a prend la valeur d'un entier = 1, lorsque n = 1, ou un entier = 0, lorsque n= 2, et Q représente un groupe alkyle, alcényle, aryle ou arylalkyle éventuellement substitué.
PCT/EP2006/068492 2005-11-21 2006-11-15 Procede de fabrication d'une plaque d'impression lithographique WO2007057410A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
EP05111014.6 2005-11-21
EP05111014A EP1788449A1 (fr) 2005-11-21 2005-11-21 Procédé de fabrication d'une plaque d'impression lithographique
US74875505P 2005-12-08 2005-12-08
US60/748,755 2005-12-08

Publications (1)

Publication Number Publication Date
WO2007057410A1 true WO2007057410A1 (fr) 2007-05-24

Family

ID=37719402

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2006/068492 WO2007057410A1 (fr) 2005-11-21 2006-11-15 Procede de fabrication d'une plaque d'impression lithographique

Country Status (1)

Country Link
WO (1) WO2007057410A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113168096A (zh) * 2018-12-10 2021-07-23 爱克发有限公司 Uv或紫色敏化的平版印刷版的在机加工

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1557262A2 (fr) * 2004-01-23 2005-07-27 Fuji Photo Film Co., Ltd. Précurseur de plaque d'impression lithographique et méthode pour l'impression lithographique.

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1557262A2 (fr) * 2004-01-23 2005-07-27 Fuji Photo Film Co., Ltd. Précurseur de plaque d'impression lithographique et méthode pour l'impression lithographique.

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113168096A (zh) * 2018-12-10 2021-07-23 爱克发有限公司 Uv或紫色敏化的平版印刷版的在机加工
CN113168095A (zh) * 2018-12-10 2021-07-23 爱克发有限公司 平版印刷版前体
CN113168096B (zh) * 2018-12-10 2024-05-24 易客发有限公司 Uv或紫色敏化的平版印刷版的在机加工
CN113168095B (zh) * 2018-12-10 2024-05-24 易客发有限公司 平版印刷版前体

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