EP0987104B1 - Ein thiosulfatpolymeres enthaltendes wärmeempfindliches Bildelement und Methoden zu seiner Benutzung - Google Patents

Ein thiosulfatpolymeres enthaltendes wärmeempfindliches Bildelement und Methoden zu seiner Benutzung Download PDF

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Publication number
EP0987104B1
EP0987104B1 EP19990202885 EP99202885A EP0987104B1 EP 0987104 B1 EP0987104 B1 EP 0987104B1 EP 19990202885 EP19990202885 EP 19990202885 EP 99202885 A EP99202885 A EP 99202885A EP 0987104 B1 EP0987104 B1 EP 0987104B1
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European Patent Office
Prior art keywords
imaging
imaging member
heat
polymer
layer
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EP19990202885
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English (en)
French (fr)
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EP0987104A1 (de
Inventor
Shiying Zheng
Thap Dominh
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Eastman Kodak Co
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Eastman Kodak Co
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Priority claimed from US09/156,833 external-priority patent/US5985514A/en
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
    • B41M5/36—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used using a polymeric layer, which may be particulate and which is deformed or structurally changed with modification of its' properties, e.g. of its' optical hydrophobic-hydrophilic, solubility or permeability properties
    • B41M5/368—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used using a polymeric layer, which may be particulate and which is deformed or structurally changed with modification of its' properties, e.g. of its' optical hydrophobic-hydrophilic, solubility or permeability properties involving the creation of a soluble/insoluble or hydrophilic/hydrophobic permeability pattern; Peel development
    • 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
    • B41C1/1041—Forme preparation for lithographic printing; Master sheets for transferring a lithographic image to the forme by modification of the lithographic properties without removal or addition of material, e.g. by the mere generation of a lithographic pattern
    • 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
    • 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
    • B41C2210/22—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

  • This invention relates in general to lithographic imaging members, and particularly to heat-sensitive imaging members that can be used with or without wet processing after imaging.
  • the invention also relates to a method of digitally imaging such imaging members, and to a method of printing using them.
  • lithographic printing is based upon the immiscibility of oil and water, wherein an oily material or ink is preferentially retained by an imaged area and the water or fountain solution is preferentially retained by the nonimaged areas.
  • an oily material or ink is preferentially retained by an imaged area and the water or fountain solution is preferentially retained by the nonimaged areas.
  • the background or nonimaged areas retain the water and repel the ink while the imaged areas accept the ink and repel the water.
  • the ink is eventually transferred to the surface of a suitable substrate, such as cloth, paper or metal, thereby reproducing the image.
  • Very common lithographic printing plates include a metal or polymer support having thereon an imaging layer sensitive to visible or UV light. Both positive- and negative-working printing plates can be prepared in this fashion. Upon exposure, and perhaps post-exposure heating, either imaged or nonimaged areas are removed using wet processing chemistries.
  • Thermally sensitive printing plates are less common. Examples of such plates are described in US-A-5,372,915. They include an imaging layer comprising a mixture of dissolvable polymers and an infrared radiation absorbing compound. While these plates can be imaged using lasers and digital information, they require wet processing using alkaline developer solutions.
  • a lithographic printing plate could be created containing an IR absorbing layer.
  • Canadian 1,050,805 discloses a dry planographic printing plate comprising an ink receptive substrate, an overlying silicone rubber layer, and an interposed layer comprised of laser energy absorbing particles (such as carbon particles) in a self-oxidizing binder (such as nitrocellulose).
  • laser energy absorbing particles such as carbon particles
  • a self-oxidizing binder such as nitrocellulose
  • Thermally switchable polymers have been described for use as imaging materials in printing plates.
  • switchable is meant that the polymer is rendered from hydrophilic to relatively more hydrophobic, or from hydrophilic to relatively more hydrophobic, upon exposure to heat.
  • US-A-4,634,659 describes imagewise irradiating hydrophobic polymer coatings to render exposed regions more hydrophilic in nature. While this concept was one of the early applications of converting surface characteristics in printing plates, it has the disadvantages of requiring long UV light exposure times (up to 60 minutes) and the plate's use is in a positive-working mode only.
  • EP-A 0 652 483 describes lithographic printing plates imageable using IR lasers, and which do not require wet processing. These plates comprise an imaging layer that becomes more hydrophilic upon the imagewise exposure to heat.
  • This coating contains a polymer having pendant groups (such as t -alkyl carboxylates) that are capable of reacting under heat or acid to form more polar, hydrophilic groups. Imaging such compositions converts the imaged areas from hydrophobic to relatively more hydrophilic in nature, and thus requires imaging the background of the plate, which is generally a larger area. This can be a problem when imaging to the edge of the printing plate is desired.
  • Positive-working photoresists and printing plates having crosslinked, UV-sensitive polymers are described in EP-A 0 293 058.
  • the polymers contain pendant iminosulfonate groups that are decomposed upon UV exposure, generating a sulfonic group and providing polymer solubility.
  • US-A-5,512,418 describes the use of polymers containing pendant ammonium groups for thermally induced imaging.
  • US-A-4,693,958 also describes a method of preparing printing plates that are wet processed.
  • the imaging layers contain polyamic acids and vinyl polymers containing quaternary ammonium groups.
  • Japanese Kokai 9-197,671 describes a negative-working printing plate and imaging method in which the imaging layer includes a sulfonate-containing polymer, an IR radiation absorber, a novolak resin and a resole resin.
  • an imaging member comprising a support having thereon a hydrophilic imaging layer comprising a hydrophilic heat-sensitive polymer comprising recurring units comprising a heat-activatable thiosulfate group, represented by structure I: wherein X is a divalent linking group, and Y is hydrogen or a cation.
  • This invention also includes a method of imaging comprising the steps of:
  • the method is carried further with the step of:
  • the imaging member of this invention has a number of advantages, thereby avoiding the problems of known printing plates. Specifically, the problems and concerns associated with ablation imaging (that is, imagewise removal of surface layer) are avoided because imaging is accomplished by "switching" (preferably irreversibly) the exposed areas of its printing surface to be more hydrophobic, or oil-receptive by heat generated or provided during exposure to an appropriate energy source.
  • the resulting imaging members display high ink receptivity in exposed areas and excellent ink/water discrimination.
  • the imaging members also perform well with or without wet chemical processing after imaging to remove the unexposed areas. Preferably, no wet chemical processing (such as processing using an alkaline developer) is used in the practice of this invention.
  • the imaging members are durable because the exposed areas are crosslinked during imaging.
  • the printing members resulting from imaging the imaging members of this invention are generally negative-working.
  • the imaging members can also be on-press printing cylinders.
  • hydrophilic heat-sensitive polymer in the hydrophilic imaging layer.
  • These polymers have heat-activatable thiosulfate groups (also known as Bunte salts) pendant to the polymer backbone that are believed to provide crosslinking sites upon exposure to heat.
  • heat-activatable groups are described in more detail below.
  • the imaging members of this invention comprise a support and one or more layers thereon that are heat-sensitive.
  • the support can be any self-supporting material including polymeric films, glass, metals or stiff papers, or a lamination of any of these materials.
  • the thickness of the support can be varied. In most applications, the thickness should be sufficient to sustain the wear from printing and thin enough to wrap around a printing form.
  • a preferred embodiment uses a polyester support prepared from, for example, polyethylene terephthalate or polyethylene naphthalate, and having a thickness of from 100 to 310 ⁇ m.
  • Another preferred embodiment uses a metal (such as aluminum) sheet having a ⁇ thickness of from 100 to 600 ⁇ m.
  • the support should resist dimensional change under conditions of use.
  • the aluminum and polyester supports are most preferred for lithographic printing plates.
  • the support can also be a cylindrical surface having the heat-sensitive imaging polymer composition coated thereon, and can thus be an integral part of the printing press.
  • the use of such cylinders is described for example in US-A-5,713,287.
  • cylindrical support is meant printing cylinders used on press as well as printing sleeves that are fitted over a printing cylinder.
  • the support may be coated with one or more "subbing" layers to improve adhesion of the final assemblage.
  • subbing layer materials include, but are not limited to, gelatin and other naturally occurring and synthetic hydrophilic colloids and vinyl polymers (such as copolymers prepared from vinylidene chloride) known for such purposes in the photographic industry, vinylphosphonic acid polymers, alkoxysilanes, aminopropyltriethoxysilane, glycidoxypropyltriethoxysilane, sol-gel materials, epoxy functional polymers and ceramics.
  • the backside of the support may be coated with antistatic agents and/or slipping layers or matte layers to improve handling and "feel" of the imaging member.
  • the imaging member preferably has only one layer, that is the heat-sensitive layer that is required for imaging.
  • the hydrophilic imaging layer includes one or more heat-sensitive polymers, and optionally but preferably a photothermal conversion material (described below), and preferably provides the outer printing surface. Because of the particular heat-sensitive polymer(s) used in the imaging layer, the exposed (imaged) areas of the layer are crosslinked and rendered more hydrophobic in nature. The unexposed areas remain hydrophilic and can be washed off with a fountain solution on press, or developed in tap water after imaging.
  • the heat-sensitive layer of the imaging members only the heat-sensitive polymer and optionally the photothermal conversion material are necessary or essential for imaging.
  • Each of the heat-sensitive polymers useful in this invention has a molecular weight of at least 1000, and preferably of at least 5000.
  • the polymers can be vinyl homopolymers or copolymers prepared from one or more ethylenically unsaturated polymerizable monomers that are reacted together using known polymerization techniques and reactants. Alternatively, they can be addition homopolymers or copolymers (such as polyethers) prepared from one or more heterocyclic monomers that are reacted together using known polymerization techniques and reactants. Additionally, they can be condensation type polymers (such as polyesters, polyimides, polyamides or polyurethanes) prepared using known polymerization techniques and reactants. Whatever the type of polymers, at least 10 mol % of the total recurring units in the polymer comprise the necessary heat-activatable thiosulfate groups.
  • the heat-sensitive polymers useful in the practice of this invention can be represented by the structure II wherein the thiosulfate group (or Bunte salt) is a pendant group: wherein A represents a polymeric backbone, X is a divalent linking group, and Y is hydrogen or a cation.
  • polymeric backbones include, but are not limited to, vinyl polymers, polyethers, polyimides, polyamides, polyurethanes and polyesters.
  • the polymeric backbone is a vinyl polymer or polyether.
  • Useful "X" linking groups include -(COO) n (Z) m - wherein n is 0 or 1, m is 0 or 1, and Z is a substituted or unsubstituted alkylene group having 1 to 6 carbon atoms (such as methylene, ethylene, n -propylene, isopropylene, butylenes, 2-hydroxypropylene and 2-hydroxy-4-azahexylene) that can have one or more oxygen, nitrogen or sulfur atoms in the chain, a substituted or unsubstituted arylene group having 6 to 14 carbon atoms in the aromatic ring (such as phenylene, naphthalene, anthracylene and xylylene), or a substituted or unsubstituted arylenealkylene (or alkylenearylene) group having 7 to 20 carbon atoms in the chain (such as p -methylenephenylene, phenylenemethylenephenylene, biphenylene and phenyleneis
  • X is an alkylene group of 1 to 3 carbon atoms, an arylene group of 6 carbon atoms in the aromatic ring, an arylenealkylene group of 7 or 8 carbon atoms in the chain, or -COO(Z) m - wherein Z is methylene, ethylene or phenylene. Most preferably, X is phenylene, methylene or -COO-.
  • Y is hydrogen, ammonium ion, or a metal ion (such as sodium, potassium, magnesium, calcium, cesium, barium, zinc or lithium ion).
  • Y is hydrogen, sodium ion or potassium ion.
  • the thiosulfate group is generally pendant to the backbone, preferably it is part of an ethylenically unsaturated polymerizable monomer that can be polymerized using conventional techniques to form vinyl homopolymers of the thiosulfate-containing recurring units, or vinyl copolymers when copolymerized with one or more additional ethylenically unsaturated polymerizable monomers.
  • the thiosulfate-containing recurring units generally comprise at least 10 mol % of all recurring units in the polymer, preferably they comprise from 15 to 100 mol % of all recurring units, and more preferably, they comprise from 15 to 50 mol % of all recurring units.
  • a polymer can include more than one type of repeating unit containing a thiosulfate group as described herein.
  • the imaging member is a negative-working imaging member.
  • Thiosulfate-containing molecules can be prepared from the reaction between an alkyl halide and thiosulfate salt as taught by Bunte, Chem.Ber. 7, 646, 1884.
  • Polymers containing thiosulfate groups can either be prepared from functional monomers or from preformed polymers. If the polymer is a vinyl polymer, the functional vinyl polymerizable monomer can be prepared as illustrated below: wherein R 1 is hydrogen or an alkyl group, Hal is halide, and X is a divalent linking group.
  • Polymers can also be prepared from preformed polymers in a similar manner as described in US-A-3,706,706:
  • Thiosulfate-containing molecules can also be prepared by reaction of an alkyl epoxide with a thiosulfate salt, or between an alkyl epoxide and a molecular containing a thiosulfate moiety (such as 2-aminoethanethiosulfuric acid), and the reaction can be performed either on a monomer or polymer as illustrated by Thames, Surf. Coating , 3 (Waterborne Coat.), Chapter 3, pp. 125-153, Wilson et al (Eds.):
  • Synthesis Example 1 Synthesis of poly[vinyl benzyl thiosulfate sodium salt -co-N - (3 -aminopropyl)methacrylamide hydrochloride] from monomer: Polymer 9 :
  • Vinyl benzyl chloride (20 g, 0.131 mol) was dissolved in 50 ml of ethanol in a 250 ml round-bottomed flask and placed in a 30°C water bath.
  • Sodium thiosulfate (18.8 g, 0.119 mol) was dissolved in 60 ml of 2:1 ethanol:water mixture, added to an addition funnel, and dripped into vinyl benzyl chloride solution over a period of 60 minutes. The reaction was stirred warm for additional 2 hours. Solvent was then evaporated and the white solid was dissolved in hot ethanol and hot filtered. White crystalline product was formed in the filtrate.
  • the resulting monomer (2 g, 8 mmol), 3-aminopropyl methacrylamide hydrochloride (0.16 g, 0.8 mmol), and 4,4'-azobis(4-cyanovaleric acid) (75 % in water, 30 mg) were added to a 25 ml round-bottomed flask. The solution was purged with dry nitrogen for 15 minutes and then heated at 60°C overnight. After cooling to room temperature, the solution was dialyzed against water overnight. The resulting polymer was subject to characterization and imaging testing.
  • Synthesis Example 2 Synthesis of poly(vinyl benzyl thiosulfate sodium salt) from polymer: Polymer 7 :
  • Vinyl benzyl chloride (21.5 g, 0.141 mol) and azobisisobutylronitrile (hereafter referred to as "AIBN") (0.25 g, 1.5 mmol) were dissolved in 50 ml of toluene.
  • the solution was purged with dry nitrogen and then heated at 65°C overnight. After cooling to room temperature, the solution was diluted to 100 ml and added dropwise to 1000 ml of isopropanol.
  • the white powdery polymer was collected by filtration and dried under vacuum at 40°C overnight.
  • This polymer (10 g) was dissolved in 150 ml of N,N'-dimethylformamide. To this solution was added sodium thiosulfate (10.44 g, 0.066 mol) and 30 ml of water. Some polymer precipitated out. The cloudy reaction mixture was heated at 95°C for 12 hours. After cooling to room temperature, the hazy reaction mixture was dialyzed against water. A small amount of the resulting polymer solution was freeze dried for elemental analysis and the rest of the polymer solution was subject to imaging testing. Elemental analysis indicated the reaction conversion was 99 mol%.
  • Synthesis Example 3 Synthesis of poly(chloromethyl-ethylene oxide-co-sodium thiosulfate methyl-ethylene oxide) from polymer: Polymers 1-3 :
  • DMSO dimethylsulfoxide
  • Synthesis Example 4 Synthesis of Polymers 4-6 and 8 : Synthesis of poly(vinyl benzyl thiosulfate sodium salt-co-methyl methacylate) from polymer: Polymer 6 :
  • Vinyl benzyl chloride (10 g, 0.066 mol), methyl methacrylate (15.35 g, 0.153 mol) and AIBN (0.72g, 4 mmol) were dissolved 120 ml of toluene. The solution was purged with dry nitrogen and then heated at 65°C overnight. After cooling to room temperature, the solution was dropwise added to 1200 ml of isopropanol. The resulting white powdery polymer was collected by filtration and dried under vacuum at 60°C overnight. 1 H NMR analysis indicate that the copolymer contained 44 mol% of vinyl benzyl chloride.
  • This polymer (16 g) was dissolved in 110 m ofN,N'-dimethylformamide. To this solution was added sodium thiosulfate (12 g) and water (20 ml). Some polymer precipitated out. The cloudy reaction mixture was heated at 90°C for 24 hours. After cooling to room temperature, the hazy reaction mixture was dialyzed against water. A small amount of the resulting polymer solution was freeze dried for elemental analysis and the rest of the polymer solution was subject to imaging testing. Elemental analysis indicated that all the vinyl benzyl chloride was converted to sodium thiosulfate salt.
  • Synthesis Example 5 Synthesis of poly(2-sodium thiosulfate-ethyl methacrylate): Polymer 13 :
  • 2-Chloroethyl methacrylate (10 g, 0.067 mol) and AIBN (0.11 g, 0.7 mmol) were dissolved in 20 ml of tetrahydrofuran. The solution was purged with dry nitrogen and then heated at 60°C for 17 hours. After cooling to room temperature, the solution was diluted to 80 ml and added dropwise to 800 ml of methanol. The resulting white powdery polymer was collected by filtration and dried under vacuum at 40°C overnight.
  • the above polymer (5 g) was dissolved in 50 ml of N,N'-dimethylformamide. To this solution was added sodium thiosulfate (5.3 g) and water (10 ml). Some polymer precipitated out. The cloudy reaction mixture was heated at 90°C for 52 hours. After cooling to room temperature, the reaction mixture was dialyzed against water. A small amount of the resulting polymer solution was freeze dried for elemental analysis and the rest of the polymer solution was subject to imaging testing. Elemental analysis indicated that the conversion to sodium thiosulfate was 90 mol%.
  • Synthesis Example 6 Synthesis of polymers 10-12 : Synthesis ofpoly (2-hydroxy -3-sodium thiosulfate-propyl methacrylate-co-2-(methacryloyloxy)ethyl acetoacetate) from polymer: Polymer 12 :
  • the above polymer (10 g) was dissolved in 150 ml of N,N'-dimethylformamide. To this solution was added sodium thiosulfate (11 g) and water (30 ml). Some polymer precipitated out. The cloudy reaction mixture was heated at 65°C for 24 hours. After cooling to room temperature, the hazy reaction mixture was dialyzed against water. Small amount of the resulting polymer solution was freeze-dried for elemental analysis and the rest of the polymer solution was subject to imaging testing. Elemental analysis indicated complete conversion of glycidyl methacrylate to sodium thiosulfate salt.
  • Polymer 10 and 11 were similarly prepared.
  • Synthesis Example 7 Synthesis of poly (4 -aza -2-hydroxy-6-sodium thiosulfate-hexyl methacrylate) from monomer: Polymer 14 :
  • the flask was capped with a septum, purged with dry nitrogen for 15 minutes, and then heated at 60°C for 17 hours. After cooling to room temperature, the solution was dialyzed against water overnight. The resulting polymer was subject to characterization and imaging testing.
  • Vinyl polymers can be prepared by copolymerizing monomers containing the thiosulfate functional groups with one or more other ethylenically unsaturated polymerizable monomers to modify polymer chemical or functional properties, to optimize imaging member performance, or to introduce additional crosslinking capability.
  • Useful additional ethylenically unsaturated polymerizable monomers include, but are not limited to, acrylates (including methacrylates) such as ethyl acrylate, n -butyl acrylate, methyl methacrylate and t -butyl methacrylate, acrylamides (including methacrylamides), an acrylonitrile (including methacrylonitrile), vinyl ethers, styrenes, vinyl acetate, dienes (such as ethylene, propylene, 1,3-butadiene and isobutylene), vinyl pyridine and vinylpyrrolidone. Acrylamides, acrylates and styrenes are preferred.
  • Polyesters, polyamides, polyimides, polyurethanes and polyethers are prepared from conventional starting materials and using known procedures and conditions.
  • a mixture of heat-sensitive polymers described herein can be used in the imaging layer of the imaging members, but preferably only a single polymer is used.
  • the polymers can be crosslinked or uncrosslinked when used in the imaging layer. If crosslinked, the crosslinkable moiety is preferably provided from one or more of the additional ethylenically unsaturated polymerizable monomers when the polymers are vinyl polymers. The crosslinking cannot interfere with the heat activation of the thiosulfate group during imaging.
  • the imaging layer of the imaging member can include one or more of such homopolymers or copolymers, with or without minor (less than 20 weight % based on total layer dry weight) amounts of additional binder or polymeric materials that will not adversely affect its imaging properties.
  • the imaging layer includes no additional materials that are needed for imaging, especially those materials conventionally required for wet processing with alkaline developer solutions (such as novolak or resole resins).
  • the amount of heat-sensitive polymer(s) used in the imaging layer is generally at least 0.1 g/m 2 , and preferably from 0.1 to 10 g/m 2 (dry weight). This generally provides an average dry thickness of from 0.1 to 10 ⁇ m.
  • the imaging layer can also include one or more conventional surfactants for coatability or other properties, or dyes or colorants to allow visualization of the written image, or any other addenda commonly used in the lithographic art, as long as the concentrations are low enough so that they are inert with respect to imaging or printing properties.
  • the heat-sensitive composition in the imaging layer preferably includes one or more photothermal conversion materials to absorb appropriate energy from an appropriate source (such as a laser), which radiation is converted into heat.
  • an appropriate source such as a laser
  • photothermal conversion materials convert photons into heat phonons.
  • the radiation absorbed is in the infrared and near-infrared regions of the electromagnetic spectrum.
  • Such materials can be dyes, pigments, evaporated pigments, semiconductor materials, alloys, metals, metal oxides, metal sulfides or combinations thereof, or a dichroic stack of materials that absorb radiation by virtue of their refractive index and thickness. Borides, carbides, nitrides, carbonitrides, bronze-structured oxides and oxides structurally related to the bronze family but lacking the WO 2.9 component, are also useful.
  • One particularly useful pigment is carbon of some form (for example, carbon black).
  • the size of the pigment particles should not be more than the thickness of the layer. Preferably, the size of the particles will be half the thickness of the layer or less.
  • Useful absorbing dyes for near infrared diode laser beams are described, for example, in US-A-4,973,572. Particular dyes of interest are "broad band” dyes, that is those that absorb over a wide band of the spectrum. Mixtures of pigments, dyes, or both, can also be used.
  • Particularly useful infrared radiation absorbing dyes and pigments include those illustrated as follows:
  • the photothermal conversion material(s) are generally present in an amount sufficient to provide an optical density of at least 0.3, and preferably at least 1.0, at the operating wavelength of the imaging laser.
  • the particular amount needed for this purpose would be readily apparent to one skilled in the art, depending upon the specific material used.
  • a photothermal conversion material can be included in a separate layer that is in contact with the heat-sensitive imaging layer.
  • the action of the photothermal conversion material can be transferred to the heat-sensitive polymer layer without the material originally being in the same layer.
  • the heat-sensitive composition can be applied to a support using any suitable equipment and procedure, such as spin coating, knife coating, gravure coating, dip coating or extrusion hopper coating. In addition, it can be sprayed onto the support (including on-press cylinders) using suitable spraying equipment, as described in US-A-5,713,287 (noted above).
  • the imaging members of this invention can be of any useful form including, but not limited to, printing plates, printing cylinders, printing sleeves and printing tapes (including flexible printing webs).
  • the imaging members are printing plates.
  • Printing plates can be of any useful size and shape (for example, square or rectangular) having the requisite heat-sensitive imaging layer disposed on a suitable support.
  • Printing cylinders and sleeves are known as rotary printing members having the support and heat-sensitive layer in a cylindrical form. Hollow or solid metal cores can be used as substrates for printing sleeves.
  • the imaging member of this invention can be exposed to any suitable source of energy that generates or provides heat, such as a focused laser beam or thermoresistive head, in the imaged areas, typically from digital information supplied to the imaging device.
  • a laser used to expose the imaging member of this invention is preferably a diode laser, because of the reliability and low maintenance of diode laser systems, but other lasers such as gas or solid state lasers may also be used.
  • the combination of power, intensity and exposure time for laser imaging would be readily apparent to one skilled in the art. Specifications for lasers that emit in the near-IR region, and suitable imaging configurations and devices are described in US-A-5,339,737.
  • the imaging member is typically sensitized so as to maximize responsiveness at the emitting wavelength of the laser. For dye sensitization, the dye typically is chosen such that its ⁇ max closely approximates the wavelength of laser operation.
  • the imaging apparatus can operate on its own, functioning solely as a platemaker, or it can be incorporated directly into a lithographic printing press. In the latter case, printing may commence immediately after imaging, thereby reducing press set-up time considerably.
  • the imaging apparatus can be configured as a flatbed recorder or as a drum recorder, with the imaging member mounted to the interior or exterior cylindrical surface of the drum.
  • the requisite relative motion between the imaging device (such as a laser beam) and the imaging member can be achieved by rotating the drum (and the imaging member mounted thereon) about its axis, and moving the imaging device parallel to the rotation axis, thereby scanning the imaging member circumferentially so the image "grows" in the axial direction.
  • the imaging device can be moved parallel to the drum axis and, after each pass across the imaging member, increment angularly so that the image "grows" circumferentially. In both cases, after a complete scan an image corresponding (positively or negatively) to the original document or picture can be applied to the surface of the imaging member.
  • a laser beam is drawn across either axis of the imaging member, and is indexed along the other axis after each pass.
  • the requisite relative motion can be produced by moving the imaging member rather than the laser beam.
  • thermoresistive head or thermal printing head
  • thermal printing as described for example, in US-A-5,488,025.
  • thermal printing heads are commercially available (for example as Fujitsu Thermal Head FTP-040 MCS001 and TDK Thermal Head F415 HH7-1089).
  • Imaging of heat-sensitive compositions on printing press cylinders (or sleeves) can be accomplished using any suitable means, for example, as taught in US-A-5,713,387 (noted above).
  • the imaging member (including an on-press sprayed cylinder) can be used for printing by applying a lithographic ink to the image on its printing surface, with a fountain solution, and by transferring the ink to a suitable receiving material (such as cloth, paper, metal, glass or plastic) to provide a desired impression of the image thereon.
  • a suitable receiving material such as cloth, paper, metal, glass or plastic
  • an intermediate "blanket” roller can be used in the transfer of the ink from the imaging member to the receiving material.
  • the imaging members can be cleaned between impressions, if desired, using conventional cleaning means.
  • a thermal IR-laser platesetter was used to image the printing plates, the printer being similar to that described in US-A-5,168,288.
  • the printing plates were exposed using approximately 450 mW per channel, 9 channels per swath, 945 lines/cm, a drum circumference of 53 cm and an image spot (1/e2) at the image plane of 25 ⁇ m.
  • the test image included text, positive and negative lines, halftone dot patterns and a half-tone image. Images were printed at speeds up to 1100 revolutions per minute (the exposure levels do not necessarily correspond to the optimum exposure levels for the tested printing plates).
  • imaging members of this invention comprising homopolymers and copolymers coated on polyester support were prepared and imaged on press.
  • Heat-sensitive imaging formulations were prepared from the following components: One of Polymer 1-14 (see below) 0.20g IR dye 6 0.02g Water 4.00 g Methanol 1.00 g
  • Each formulation containing 4.21 weight % of solids was coated at 100 mg/ft 2 (1.08 g/m 2 ) dry coverage onto a gelatin-subbed 0.10 mm poly(ethylene terephthalate) support.
  • the resulting printing plates were dried in a convection oven at 82°C for 3 minutes, clamped on the rotating drum of a conventional platesetter and digitally exposed to an 830 nm laser printhead at exposure levels ranging from 550 to 1350 mJ/cm 2 .
  • the resulting blue-green coatings rapidly discolored to a typically off-white color in the exposed regions.
  • Heat-sensitive coatings similar to those described in Examples 1-14 were prepared, and coated onto 0.14 mm grained, anodized aluminum supports. After imaging as described in the previous examples, the printing plates were developed with tap water or several common "developing" solutions. Various methods of development and test results from printing are summarized in TABLE II, including one press run exceeding 40,000 impressions.
  • Example Polymer Developing Solution Press Results 15 2 KODAK MX-1587-1 Negative Plate Developer 40,000 16 3 Varn Universal Pink fountain solution (28 ml in 4 liters of water) 1,500 17 7 2 % Borax in water 1,500 18 12 Tap water 1,500 19 9 Tap water 1,500
  • a heat sensitive composition either an aqueous or non-aqueous composition
  • a coating method that is compatible with a printing press environment, including spraying, dipping or roller coating.
  • the coating surfaces that is, supports
  • the resulting heat-sensitive layers exhibit adequate uniformity and dry quickly and are ready to be laser imaged in minutes.
  • the energy requirement for imaging is ideally about 500 mJ/cm 2 .
  • the imaging members can be either processless (that is, no wet processing after imaging) or wet processable on press, and should be capable of some 15-50,000 impressions. After printing, the coating along with residual ink can be cleaned off and the printing surfaces can be reused.
  • compositions were spray coated using convenient commercial spray devices such as an artist air brush available from Paasche, or a Preval spray unit available from Valve Corp, of Yonkers, N.Y., at a distance of about 30-40 cm onto grained anodized aluminum.
  • a heat-sensitive coating was also prepared by simply spreading the composition ("gravity coating") on the aluminum support and uniformly distributing it by tilting the support sideways to drain off excess fluid by gravity. All coating thicknesses were in the range of 0.8 to 1.5 ⁇ m. Each coating was dried at 82°C for 3 minutes, and imaged at 830 nm using a laser print head at energies ranging from 300 to 800 mJ/cm 2 .
  • Each resulting imaging member was put onto a commercial press (either an A.B. Dick 9870 duplicator using Varn Universal pink fountain solutions, or a Heidelberg GTO/DI press with Prisco Alkaless 3000 fountain solution).
  • the fountain solutions acted initially also as on-press developers to remove nonimaged areas of the imaging members.
  • Each imaging member rolled up within 20-25 sheets and printed with full density and clean background for at least 300-1000 sheets as shown on Table IV below.
  • the inked images were also readily removed by rubbing with a commercially available negative or alkaline positive developer.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Printing Plates And Materials Therefor (AREA)
  • Photosensitive Polymer And Photoresist Processing (AREA)
  • Materials For Photolithography (AREA)
  • Rotary Presses (AREA)

Claims (15)

  1. Abbildungselement mit einem Träger mit einer darauf angeordneten hydrophilen Abbildungsschicht, die ein hydrophiles, wärmeempfindliches Polymer umfasst, das periodische Einheiten aus einer wärmeaktivierbaren Thiosulfatgruppe, wie durch Struktur I dargestellt, umfasst:
    Figure 00280001
    worin X eine zweiwertige Verknüpfungsgruppe ist und Y ein Wasserstoff oder ein Kation.
  2. Abbildungselement nach Anspruch 1, worin X eine Alkylengruppe, eine Arylengruppe, eine Arylenalkylengruppe oder -(COO)n(Z)m ist, worin n für 0 oder 1 steht und Z eine Alkylengruppe, eine Arylengruppe oder eine Arylenalkylengruppe ist und Y für Wasserstoff, ein Ammoniumion oder ein Metallion steht.
  3. Abbildungselement nach Anspruch 1 oder 2, worin die Abbildungsschicht die alleinige Schicht auf dem Träger ist.
  4. Abbildungselement nach Anspruch 1 bis 3, worin das wärmeempfindliche Polymer ein Vinylpolymer oder ein Polyether ist.
  5. Abbildungselement nach Anspruch 1 bis 4, worin die periodischen Einheiten mit der wärmeaktivierbaren Thiosulfatgruppe mindestens 10 Mol% aller periodischen Einheiten in dem wärmeempfindlichen Polymer umfassen.
  6. Abbildungselement nach Anspruch 4 oder 5, worin das wärmeempfindliche Polymer ein Copolymer ist, das von zwei oder mehr verschiedenen, ethylenisch ungesättigten, polymerisierbaren Monomeren abgeleitet ist, wobei mindestens eines der Monomere die wärmeaktivierbare Thiosulfatgruppe enthält.
  7. Abbildungselement nach Anspruch 1 bis 6, worin die Abbildungsschicht zudem ein fotothermisches Umwandlungsmaterial umfasst.
  8. Abbildungselement nach Anspruch 7, worin das fotothermische Umwandlungsmaterial Rußschwarz oder ein IR-Strahlung absorbierender Farbstoff oder ein Pigment ist.
  9. Abbildungselement nach einem der Ansprüche 1 oder 8, worin die Abbildungsschicht eine Oberflächenabbildungsschicht ist und das Abbildungselement eine Offset-Druckplatte ist.
  10. Abbildungselement nach einem der Ansprüche 1 oder 8, welches ein Abbildungszylinder mit einem zylindrischen Träger ist.
  11. Abbildungsverfahren, das folgende Schritte umfasst:
    A) Bereitstellen des Abbildungselements nach einem der Ansprüche 1 bis 10, und
    B) bildweises Belichten des Abbildungselements, um belichtete und unbelichtete Bereiche der Abbildungsschicht des Abbildungselements zu erzeugen, wodurch die belichteten Bereiche mithilfe von Wärme, die durch das bildweise Belichten erzeugbar ist, vemetzt und stärker hydrophob ausgebildet werden als die unbelichteten Bereiche.
  12. Verfahren nach Anspruch 11, worin das bildweise Belichten mit einem thermischen Druckkopf ausführbar ist.
  13. Abbildungsverfahren, das folgende Schritte umfasst:
    A) Erzeugen eines Abbildungselements durch Sprühbeschichten auf einem Träger, einer wärmeempfindlichen Zusammensetzung, die ein hydrophiles, wärmeempfindliches Polymer umfasst, das periodische Einheiten aus einer wärmeaktivierbaren Thiosulfatgruppe, wie durch Struktur I dargestellt, umfasst:
    Figure 00300001
    worin X eine zweiwertige Verknüpfungsgruppe ist und Y ist Wasserstoff oder ein Kation zur Bildung einer wärmeempfindlichen Abbildungsschicht auf dem Träger; und
    B) bildweises Belichten des Abbildungselements, um belichtete und unbelichtete Bereiche der Abbildungsschicht des Abbildungselements zu erzeugen, wodurch die belichteten Bereiche mithilfe von Wärme, die durch das bildweise Belichten erzeugbar ist, vernetzt und stärker hydrophob ausgebildet werden als die unbelichteten Bereiche.
  14. Verfahren nach Anspruch 13, worin das Abbildungselement ein Druckmaschinen-Druckzylinder oder eine Hülse ist.
  15. Druckverfahren, das folgende Schritte umfasst:
    A) Bereitstellen des Abbildungselements nach einem der Ansprüche 1 bis 10,
    B) bildweises Belichten des Abbildungselements, um belichtete und unbelichtete Bereiche auf der Oberfläche des Abbildungselements zu erzeugen, wodurch die belichteten Bereiche mithilfe von Wärme, die durch das bildweise Belichten erzeugbar ist, vernetzt und stärker hydrophob ausgebildet werden als die unbelichteten Bereiche.
    B) Berühren des bildweise belichteten Abbildungselements mit einer Feuchtlösung und einer Offset-Druckfarbe und bildweises Übertragen der Druckfarbe von dem Abbildungselement auf ein Empfangsmaterial.
EP19990202885 1998-09-18 1999-09-06 Ein thiosulfatpolymeres enthaltendes wärmeempfindliches Bildelement und Methoden zu seiner Benutzung Expired - Lifetime EP0987104B1 (de)

Applications Claiming Priority (4)

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US156833 1980-06-05
US09/156,833 US5985514A (en) 1998-09-18 1998-09-18 Imaging member containing heat sensitive thiosulfate polymer and methods of use
US09/260,465 US6136503A (en) 1998-09-18 1999-03-02 Imaging cylinder containing heat sensitive thiosulfate polymer and methods of use
US260465 1999-03-02

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US6465152B1 (en) * 2000-06-26 2002-10-15 Kodak Polychrome Graphics Llc Imaging member containing heat sensitive thiosulfate polymer on improved substrate and methods of use
US6482571B1 (en) * 2000-09-06 2002-11-19 Gary Ganghui Teng On-press development of thermosensitive lithographic plates
DE10110728A1 (de) 2001-03-06 2002-10-02 Agfa Gevaert Nv Strahlungsempfindliches Aufzeichnungsmaterial mit elektrisch leitfähiger Rückseitenbeschichtung
US6846608B2 (en) * 2001-11-29 2005-01-25 Kodak Polychrome Graphics Llc Method to reduce imaging effluence in processless thermal printing plates
CN101166769B (zh) 2005-04-27 2011-12-14 大金工业株式会社 具有硫-硫酸盐基的含氟聚合物及含有该聚合物的拨水拨油剂组合物
US8313885B2 (en) 2005-11-10 2012-11-20 Agfa Graphics Nv Lithographic printing plate precursor comprising bi-functional compounds
JP6235324B2 (ja) * 2013-12-03 2017-11-22 高砂香料工業株式会社 チオール化合物含有混合物から、チオール化合物を単離及び／又は回収する方法

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