Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
  • B41C1/00—Forme preparation
  • B41C1/10—Forme preparation for lithographic printing; Master sheets for transferring a lithographic image to the forme
  • B41C1/1008—Forme preparation for lithographic printing; Master sheets for transferring a lithographic image to the forme by removal or destruction of lithographic material on the lithographic support, e.g. by laser or spark ablation; by the use of materials rendered soluble or insoluble by heat exposure, e.g. by heat produced from a light to heat transforming system; by on-the-press exposure or on-the-press development, e.g. by the fountain of photolithographic materials
  • B41C1/1016—Forme preparation for lithographic printing; Master sheets for transferring a lithographic image to the forme by removal or destruction of lithographic material on the lithographic support, e.g. by laser or spark ablation; by the use of materials rendered soluble or insoluble by heat exposure, e.g. by heat produced from a light to heat transforming system; by on-the-press exposure or on-the-press development, e.g. by the fountain of photolithographic materials characterised by structural details, e.g. protective layers, backcoat layers or several imaging layers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
  • 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
  • B41C2210/00—Preparation or type or constituents of the imaging layers, in relation to lithographic printing forme preparation
  • B41C2210/02—Positive working, i.e. the exposed (imaged) areas are removed
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
  • B41C2210/00—Preparation or type or constituents of the imaging layers, in relation to lithographic printing forme preparation
  • B41C2210/06—Developable by an alkaline solution
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
  • B41C2210/00—Preparation or type or constituents of the imaging layers, in relation to lithographic printing forme preparation
  • B41C2210/14—Multiple imaging layers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
  • B41C2210/00—Preparation or type or constituents of the imaging layers, in relation to lithographic printing forme preparation
  • B41C2210/24—Preparation or type or constituents of the imaging layers, in relation to lithographic printing forme preparation characterised by a macromolecular compound or binder obtained by reactions involving carbon-to-carbon unsaturated bonds, e.g. acrylics, vinyl polymers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
  • B41C2210/00—Preparation or type or constituents of the imaging layers, in relation to lithographic printing forme preparation
  • B41C2210/26—Preparation or type or constituents of the imaging layers, in relation to lithographic printing forme preparation characterised by a macromolecular compound or binder obtained by reactions not involving carbon-to-carbon unsaturated bonds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
  • B41C2210/00—Preparation or type or constituents of the imaging layers, in relation to lithographic printing forme preparation
  • B41C2210/26—Preparation or type or constituents of the imaging layers, in relation to lithographic printing forme preparation characterised by a macromolecular compound or binder obtained by reactions not involving carbon-to-carbon unsaturated bonds
  • B41C2210/262—Phenolic condensation polymers, e.g. novolacs, resols
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
  • B41C2210/00—Preparation or type or constituents of the imaging layers, in relation to lithographic printing forme preparation
  • B41C2210/26—Preparation or type or constituents of the imaging layers, in relation to lithographic printing forme preparation characterised by a macromolecular compound or binder obtained by reactions not involving carbon-to-carbon unsaturated bonds
  • B41C2210/264—Polyesters; Polycarbonates
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
  • B41C2210/00—Preparation or type or constituents of the imaging layers, in relation to lithographic printing forme preparation
  • B41C2210/26—Preparation or type or constituents of the imaging layers, in relation to lithographic printing forme preparation characterised by a macromolecular compound or binder obtained by reactions not involving carbon-to-carbon unsaturated bonds
  • B41C2210/266—Polyurethanes; Polyureas
• • 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
  • 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
  • B41M5/40—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used characterised by the base backcoat, intermediate, or covering layers, e.g. for thermal transfer dye-donor or dye-receiver sheets; Heat, radiation filtering or absorbing means or layers; combined with other image registration layers or compositions; Special originals for reproduction by thermography
  • B41M5/42—Intermediate, backcoat, or covering layers
• • 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
  • B41M5/40—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used characterised by the base backcoat, intermediate, or covering layers, e.g. for thermal transfer dye-donor or dye-receiver sheets; Heat, radiation filtering or absorbing means or layers; combined with other image registration layers or compositions; Special originals for reproduction by thermography
  • B41M5/42—Intermediate, backcoat, or covering layers
  • B41M5/44—Intermediate, backcoat, or covering layers characterised by the macromolecular compounds
• • 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
  • B41M5/40—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used characterised by the base backcoat, intermediate, or covering layers, e.g. for thermal transfer dye-donor or dye-receiver sheets; Heat, radiation filtering or absorbing means or layers; combined with other image registration layers or compositions; Special originals for reproduction by thermography
  • B41M5/46—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used characterised by the base backcoat, intermediate, or covering layers, e.g. for thermal transfer dye-donor or dye-receiver sheets; Heat, radiation filtering or absorbing means or layers; combined with other image registration layers or compositions; Special originals for reproduction by thermography characterised by the light-to-heat converting means; characterised by the heat or radiation filtering or absorbing means or layers
  • B41M5/465—Infrared radiation-absorbing materials, e.g. dyes, metals, silicates, C black
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41N—PRINTING PLATES OR FOILS; MATERIALS FOR SURFACES USED IN PRINTING MACHINES FOR PRINTING, INKING, DAMPING, OR THE LIKE; PREPARING SUCH SURFACES FOR USE AND CONSERVING THEM
  • B41N1/00—Printing plates or foils; Materials therefor
  • B41N1/04—Printing plates or foils; Materials therefor metallic
  • B41N1/08—Printing plates or foils; Materials therefor metallic for lithographic printing

Definitions

• the present invention relates to thermal lithographic printing plates which are imaged with an infrared laser and processed with an aqueous alkaline developer.
• U.S. 5,493,971 discloses lithographic printing constructions which include a grained-metal substrate, a protective layer that can also serve as an adhesion-promoting primer, and an ablatable oleophilic surface layer.
• imagewise pulses from an imaging laser interact with the surface layer, causing ablation thereof and, probably, inflicting some damage to the underlying protective layer as well.
• the imaged plate may then be subjected to a solvent that eliminates the exposed protective layer, but which does no damage either to the surface layer or to the unexposed protective layer lying thereunder.
• a heat-sensitive imaging element for making positive working lithographic printing plates is disclosed in European Patent Publication EP 0864420 A1.
• the imaging element disclosed comprises a lithographic base, a layer comprising a polymeric material which is soluble in an aqueous alkaline solution and an IR-radiation sensitive second layer.
• a lithographic base a layer comprising a polymeric material which is soluble in an aqueous alkaline solution and an IR-radiation sensitive second layer.
• the capacity of the aqueous alkaline solution to penetrate and/or solubilize the second layer is changed.
• Image-wise exposure can be performed with an infrared laser with a short as well as with a long pixel dwell time.
• the present invention is a positive-working, lithographic printing plate, precursor comprising;
• An added embodiment of this invention is a method for forming a planographic printing plate comprising the steps, in the order given:
• the first layer of the thermal imaging element contains photothermal conversion material and a photohardenable material activatable by ultraviolet radiation.
• the thermal imaging element of this embodiment is imaged and developed according to the method of this invention to form the imaged lithographic printing plate. The imaged lithographic printing plate is then uniformly exposed to ultraviolet radiation.
• the aqueous solution preferably has a pH of about 6 or greater; the first polymeric material preferably is insoluble in an organic solvent, and the second polymeric material is soluble in the organic solvent; and the first layer preferably contains a photothermal conversion material particularly when the element is imagewise exposed with a radiant source of energy such as an infrared emitting laser.
• the second layer is free of the photothermal conversion material.
• This invention relates to an imaging element which can be imaged with thermal energy. More particularly, this invention relates to thermal lithographic printing plates, which can be imaged by thermal energy typically by imagewise exposure with an infrared emitting laser, a thermal printing head, or the like.
• the lithographic plates described in this invention are made up of a hydrophilic substrate, typically an aluminum or polyester support, and adhered thereto, a thermally sensitive composite layer structure typically composed of two layer coatings.
• An aqueous developable polymeric mixture typically containing a photothermal conversion material is coated on the hydrophilic substrate to form the first layer.
• the second layer is composed of one or more non-aqueous soluble polymeric materials which are soluble or dispersible in a solvent which does not dissolve the first layer.
• the term"photothermal conversion material is intended to be one or more thermally sensitive components which absorb incident radiation and convert the radiation to thermal energy.
• the photothermal conversion material is an "infrared absorbing" compound.
• the first layer contains a photothermal conversion material, i.e., a first material
• the second layer may contain the same first material or a different photothermal conversion material, i.e., a second material.
• thermally sensitive is intended to be synonymous with the term “heat sensitive”
• image area(s) is intended to mean the surface area(s) of the imaged plate which is ink-receptive.
• the plate is exposed in non-image area(s), i.e., areas outside the "image areas" which are not ink-receptive, typically with an infrared laser or a thermal print head.
• non-image area(s) i.e., areas outside the "image areas" which are not ink-receptive, typically with an infrared laser or a thermal print head.
• the exposed portions are developed away thus exposing hydrophilic surfaces of the substrate which are receptive to conventional aqueous fountain solutions.
• the second layer composed of ink-receptive image areas, protects the underlying aqueous-soluble coating areas from the aqueous developer.
• the second layer may also contain a photothermal conversion material.
• imaging exposure may result in at least partial removal of exposed areas of the second layer from the underlying coating. Any remaining exposed areas of the second layer are removed during development of the imaged plate.
• the invention will be illustrated using infrared radiation, and infrared absorbing material as the photothermal conversion material
• the plate construction of the present invention includes a composite layer structure supported by a substrate.
• the composite layer structure contains at least an ink-receptive, aqueous-insoluble second layer overlying an aqueous-soluble infrared absorbing layer which is adhered to the surface of the substrate.
• the composite structure may additionally contain intermediate layers such as substrate subbing layers to enhance hydrophilicity or adhesion to the composite structure, or an adhesion promoting interlayer between the second layer and the infrared absorbing layer.
• Hydrophilic substrates which may be used in the planographic plate of this invention may be any sheet material conventionally used to prepare lithographic printing plates such as metal sheet materials or polymeric sheet material.
• a preferred metal substrate is an aluminum sheet.
• the surface of the aluminum sheet may be treated with metal finishing techniques known in the art including brushing roughening, electrochemical roughening, chemical roughening, anodizing, and silicate sealing and the like. If the surface is roughened, the average roughness Ra is preferably in the range from 0.1 to 0.8 ⁇ m, and more preferably in the range from 0.1 to 0.4 ⁇ m.
• the preferred thickness of the aluminum sheet is in the range from about 0.005 inch to about 0.020 inch.
• the polymeric sheet material may be comprised of a continuous polymeric film material, a paper sheet, a composite material or the like.
• the polymeric sheet material contains a sub-coating on one or both surfaces to modify the surface characteristics to enhance the hydrophilicity of the surface, to improve adhesion to subsequent layers, to improve planarity of paper substrates, and the like.
• a preferred polymeric substrate comprises polyethylene terephthalate.
• the composite layer structure may be applied to the substrate by sequentially applying the first layer and then the second layer using conventional coating or lamination methods. Alternatively, both layers may be applied at the same time or from a single solution which undergoes self-stratification into top and bottom layers upon drying. However it is important to avoid intermixing the two layers which tends to reduce the sensitivity.
• the first layer of the applied composite has an inner surface which is contiguous to the substrate, and the second layer of the applied composite has an outer surface.
• the first layer may be applied to the hydrophilic substrate by any conventional method.
• the ingredients are dissolved or dispersed in a suitable coating solvent, and the resulting solvent mixture is coated by known methods such as by whirl coating, bar coating, gravure coating, roller coating, and the like.
• suitable coating solvents include alkoxyalkanols such as 2-methoxyethanol; ketones such as methyl ethyl ketone; esters such as ethyl acetate or butyl acetate; and mixtures thereof.
• the second or top layer may be applied to the surface of the thermal conversion first layer by any conventional method such as those described above.
• the ingredients are dissolved or dispersed in a suitable organic coating solvent which is not a solvent for the thermal conversion layer.
• suitable coating solvents for coating the second layer include aromatic solvents such as toluene and mixtures of aromatic solvents with alkanols such as a 90:10 weight ratio of toluene and butanol.
• the first layer, the second layer or both layers may be applied by conventional extrusion coating methods from a melt mixture of layer components.
• a melt mixture typically contains no volatile organic solvents.
• the thermal digital lithographic printing plate precursor is imaged by the method comprising the following steps.
• a lithographic printing plate precursor which comprises a hydrophilic substrate and adhered thereto, a composite layer structure having an inner surface contiguous to the hydrophilic substrate and an outer oleophilic, ink-receptive surface.
• the composite layer structure comprises a first layer which forms the inner surface of the composite layer structure and a second layer which forms the outer surface of the composite layer structure.
• the first layer comprises a first polymeric material and a photothermal conversion material, as previously described, in which the first polymeric material is soluble or dispersible in an aqueous solution having a pH of about 6 or greater, and which is insoluble in an organic solvent.
• the second layer consists essentially of a second polymeric material, as previously described, which is soluble in the organic solvent, wherein the second layer is insoluble in the aqueous solution.
• the composite layer structure is imagewise exposed to thermal energy to provide exposed portions, or areas, and complimentary unexposed portions, or areas, in the composite layer structure. The exposed portions surprisingly are selectively removable by the aqueous solution.
• the aqueous solution is then applied to the outer oleophilic surface to remove the exposed portions of the composite layer structure to produce an imaged lithographic printing plate.
• the resulting imaged lithographic printing plate has uncovered hydrophilic areas of the hydrophilic substrate and complimentary ink receptive areas of the outer oleophilic surface.
• selective removability of the exposed portions is believed to result from an increased rate of dissolution or dispersibility of the first layer in the aqueous solution, from enhanced permeability of the second layer to the aqueous solution or to a combination thereof.
• This plate may be imaged with a laser or an array of lasers emitting infrared radiation in a wavelength region that closely matches the absorption spectrum of the first infrared absorbing layer.
• Suitable commercially available imaging devices include image setters such as a Creo Trendsetter (available from the CREO Corporation, British Columbia, Canada) and a Gerber Crescent 42T (available from the Gerber Corporation). While infrared lasers are preferred other high intensity lasers emitting in the visible or ultraviolet may also be used to image the lithographic plate of this invention.
• the lithographic plate of this invention may be imaged using a conventional apparatus containing a thermal printing head or any other means for imagewise conductively heating the composite layer such as with a heated stylus, with a heated stamp, or with a soldering iron as illustrated in the following examples.
• the developer liquid may be any liquid or solution which can both penetrate the exposed areas and dissolve or disperse the exposed areas of the infrared absorbing layer without substantially affecting the complimentary unexposed portions of the composite layer structure.
• Useful developer liquids are the aqueous solutions having a pH of about 6 or above as previously described. Preferred developer solutions are those that have a pH between about 8 and about 13.5.
• Useful developers include commercially available developers such as PC3000, PC955, PC956, and PC9000 aqueous alkaline developers each available from Kodak Polychrome Graphics, LLC.
• the developer liquid is applied to the imaged plate by rubbing or wiping the second layer with an applicator containing the developer liquid.
• the imaged plate may be brushed with the developer liquid or the developer liquid may be applied to the plate by spraying the second layer with sufficient force to remove the exposed areas.
• the imaged plate can be soaked in the developer liquid, followed by rubbing or brushing the plate with water.
• press life surprisingly is further enhanced by uniformly exposing the imaged lithographic printing plate to thermal energy after it has been developed in step III.
• a uniform thermal exposure may be carried out by any conventional heating technique, such as baking, contact with a heated platen, exposure to infrared radiation, and the like.
• the developed imaged lithographic printing plate is passed through a baking oven at 240° C for 3 minutes after treatment with a baking gum.
• the developed, imaged lithographic printing plate may be uniformly exposed to ultraviolet radiation to further enhance press life and resistance to press room chemicals.
• Such post development flood exposures may be carried out using any conventional ultraviolet exposure source.
• the developed, imaged plate is placed in a conventional exposure device such as a 5W Theimer device for 20 seconds.
• a conventional exposure device such as a 5W Theimer device for 20 seconds.
• the term "ultraviolet radiation” is intended to include actinic radiation within the spectral region from about 2500 ⁇ to about 4200 ⁇ with the near ultraviolet spectral region from about 3600 ⁇ to about 4000 ⁇ being preferred.
• thermal lithographic printing plate of the present invention will now be illustrated by the following examples, but is not intended to be limited thereby.
• a lithographic printing plate was prepared as follows:
• the plate precursor was laser imaged on a Creo Trendsetter thermal exposure device having a laser diode array emitting at 830 nm with a dose of 100 to 300 mJ/cm 2 .
• a Creo Trendsetter thermal exposure device having a laser diode array emitting at 830 nm with a dose of 100 to 300 mJ/cm 2 .
• positive developer PC3000 from Kodak Polychrome Graphics
• a lithographic printing plate was prepared as follows:
• This plate was laser imaged on a Creo Trendsetter system as described in Example 1. Upon alkali development with positive developer PC3000, laser exposed areas of both the first and second layers were removed without affecting the unexposed areas of either layer.
• a lithographic printing plate was prepared as follows:
• This plate was laser imaged on a Creo Trendsetter system as described in Example 1. Upon alkali development with positive developer PC3000, laser exposed areas of both the first and second layers were removed without affecting the unexposed areas of either layer.
• a lithographic printing plate was prepared as follows:
• This plate was laser imaged on a Creo Trendsetter system as described in Example 1. Upon alkali development with positive developer PC3000, laser exposed areas of both the first and second layers were removed without affecting the unexposed areas of either layer.
• a lithographic printing plate was prepared as follows:
• This plate was laser imaged on a Creo Trendsetter system as described in Example 1. Upon alkali development with positive developer PC3000, laser exposed areas of both the first and second layers were removed without affecting the unexposed areas of either layer.
• a lithographic printing plate was prepared as follows:
• This plate was laser imaged on a Creo Trendsetter system as described in Example 1. Upon alkali development with positive developer PC3000, laser exposed areas of both the first and second layers were removed without affecting the unexposed areas of either layer.
• a lithographic printing plate was prepared as follows:
• This plate was laser imaged on a Creo Trendsetter system as described in Example 1. Upon alkali development with positive developer PC3000, laser exposed areas of both the first and second layers were removed without affecting the unexposed areas of either layer.
• a lithographic printing plate was prepared as follows:
• This plate was laser imaged on a Creo Trendsetter system as described in Example 1. Upon development with developer Goldstar from Kodak Polychrome Graphics, laser exposed areas of both first and second layers were removed without affecting the unexposed areas of either layer.
• a lithographic printing plate was prepared as follows:
• One of the above developed plates was then flood exposed with UV radiation with a dose of 350 mJ/cm 2 using a SACK LCX3 5W source. Both the UV flood exposed and unexposed plates were then soaked for 2 min in developer T-153. The UV exposed plate exhibited higher resistance to developer and solvent.
• a lithographic printing plate was prepared as follows:
• Two plates were laser imaged with a 810 nm laser diode mounted on a rotating drum to provide single lines and solid areas.
• the plates were then developed with aqueous alkaline developer 956 (from Kodak Polychrome Graphics) to obtain a good image with a clean background.
• One of the plates was then flood exposed to UV radiation with a dose of 300 mJ/cm 2 , using a SACK LCX3 5W radiation source. Both plates were soaked in diacetone alcohol for 15 minutes, resulting in a coating weight loss of 94% for the plate which was not flood exposed. The flood exposed plate had a weight loss of 46%, corresponding mainly to the loss of the nitrocellulose second layer.
• a lithographic printing plate was prepared as follows:
• the plate was laser imaged with a 810 nm laser diode mounted on a rotating drum to obtain single lines and solid areas.
• the plate was then developed with aqueous alkaline developer 956 to obtain a good image with a clean background.
• a lithographic printing plate was prepared as follows:
• Two plates were laser imaged with a 810 nm laser diode mounted on a rotating drum to provide single lines and solid areas. The plates were then developed with an aqueous alkaline developer 956 to obtain a good image with a clean background.
• One of the plates was then flood exposed to UV radiation with a dose of 150 mJ/cm 2 , using a SACK LCX3 5W radiation source. Both plates were soaked in diacetone alcohol for 15 minutes, resulting in a coating weight loss of 95% for the plate which was not flood exposed. The flood exposed plate had a weight loss of 37%, corresponding mainly to the loss of the PMMA second layer.
• a lithographic printing plate was prepared as follows:
• Two plates were laser imaged with a 810 nm laser diode mounted on a rotating drum to provide single lines and solid areas. The plates were then developed with aqueous alkaline developer 956 to obtain a good image with a clean background.
• One of the plates was then flood exposed to UV radiation with a dose of 150 mJ/cm 2 , using a SACK LCX3 5W radiation source. Both plates were soaked in diacetone alcohol for 15 minutes, resulting in a coating weight loss of 93% for the plate which was not flood exposed. The flood exposed plate had a weight loss of 32%, corresponding mainly to the loss of the PMMA second layer.

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

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• 1999
  • 1999-06-08 EP EP04078162A patent/EP1506856A3/de not_active Withdrawn
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