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
  • B41C1/1041—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

Definitions

• the present invention relates to a lithographic printing plate requiring no liquid developing treatment process (hereinafter abbreviated as developing process) in which a thermoplastic polymer film having a high glass transition temperature and a strong absorption band in an ultraviolet range is exposed to a pulsed ultraviolet laser having an absorption band range in the ultraviolet range to impart hydrophilicity to the irradiated portion of the polymer.
• developing process a lithographic printing plate requiring no liquid developing treatment process
• a thermoplastic polymer film having a high glass transition temperature and a strong absorption band in an ultraviolet range is exposed to a pulsed ultraviolet laser having an absorption band range in the ultraviolet range to impart hydrophilicity to the irradiated portion of the polymer.
• the lithographic printing plate of the present invention is especially used in an offset printing utilizing repulsion between water and oil.
• a printing plate is roughly classified from the viewpoint of printing manner into a letter press printing plate, a lithographic printing plate used in an offset printing, an intaglio printing plate used in a gravure printing, or a screen printing plate.
• These printing manners are selected according to kind of an object to be printed, printing quality, the number of printing copies, or managing policy and nature of a printing company.
• offset printing has enlarged and diversified its market in the fields of general commercial printing paper printing package material printing and the like because of rapid developments in a photosensitive material technique and a system technique of a photographic plate making, and has occupied more than 80 % of whole printing industry.
• a printing plate comprising an aluminum base and a photosensitive material coated on the aluminum base (referred as PS plate) has been mainly used.
• PS plate is exposed to an active beam discharged from a mercury electric discharge lamp or laser through a plate making photographic film having an image information, and then developed by removing a photosensitive substance on an exposed or unexposed portion with a developing liquid (referred as development) to form a printing plate.
• development developing liquid
• the offset printing using PS plate does not meet the demands of the plate making industry, for example lowering of a plate making cost, shortening of a plate making time, reduction of the treatment of waste developing liquid and the like.
• the printing plate used for the computer-to-plate system (1) has to have a photosensitive layer having photosensitivity enough to form an image by a low output laser, and does not require wet developing treatment which uses liquid developer.
• an electric discharge destruction type print plate is obtained by making a picture forming layer consisting of an aluminum metal layer and a silicone layer on a PET film, and both layers are destructed by a multistylus electric discharge head modulated by an image signal to form an ink receiving layer, thus forming a printing plate.
• a printing plate suitable for the computer-to-plate system is obtained by using a generally used polymer material and an existing apparatus without using such specific material and plate making apparatus, a great contribution to the printing industry may be expected.
• thermoplastic resin film was irradiated by laser to divide into a hydrophilic area and a hydrophobic area.
• the object of the present invention is to provide a lithographic printing plate for laser direct plate making requiring no liquid developing treatment process, by irradiating a pulsed ultraviolet laser having a specific wave length on a commercially available polymer material.
• a lithographic printing plate for laser direct plate making requiring no liquid developing treatment process in which a pulsed ultraviolet laser having a wave length in an ultraviolet range is imagewise irradiated on a thermoplastic polymer film having the absorption band range in an ultraviolet range to impart hydrophilicity to the irradiated portion of the thermoplastic polymer.
• the present invention also provides a method for offset printing, in which a pulsed ultraviolet laser having a wave length in an ultraviolet range is imagewise irradiated on a thermoplastic polymer film having an absorption band range in an ultraviolet range to form an image and then an ink for lithographic printing is applied on the thermoplastic polymer film to conduct printing.
• thermoplastic polymer film having a high glass transition temperature (hereinafter abbreviated as Tg) and a high ultraviolet absorbance thus providing technical effects such as lowering of cost of a printing plate and print making, making clean of a print making environment, dispelling of uneasiness of material supply and the like.
• Tg glass transition temperature
• a thermoplastic polymer having a high Tg and having art absorption band in an ultraviolet range is irradiated by an ultraviolet pulse laser having an energy just in the absorption band range, to enhance hydrophilicity of an irradiated surface and to realize a selective sticking of an ink.
• the thermoplastic polymer film having an absorption band in an ultraviolet range may have Tg of not less than 160°C and an absorbance in a wave length of a laser of not less than 1 ⁇ 10 2 cm -1 .
• it includes a polyimide resin, polyphenylquinoxaline (PPQ) and polysulfone, or a polymer having these polymer structures.
• PPQ polyphenylquinoxaline
• PPQ polyphenylquinoxaline
• Polysulfone or a polymer having these polymer structures.
• the polyimide resin especially a film obtained by polycondensation, for example, Kapton film available from Du Pont company (USA) is more suitable.
• Film thickness is optionally controlled, however, a thickness of not less than 50 ⁇ m is preferred in order to satisfy mechanical strength and physical conditions required as a printing plate.
• the film can be a printing plate as a single substance, however, a thermoplastic film layer may be optionally formed on a support substance (for example, various
• the thermoplastic polymer film may also be formed by applying an organic solvent solution of the polymers on the support substance and then by removing the solvent. Or the thermoplastic polymer film may also be formed by applying a precursor solution of the polymers on the support substance and then conducting thermosetting.
• the organic solvent solution includes a solution of a polyimide resin having an aromatic ring soluble in an organic solvent (MATRIMID 5218: commercial name, manufactured by CIBA-GEIGY company) dissolved in a specific organic solvent, and the like.
• the precursor solution includes a fluorohydrocarbon solution of a polyamide resin having an aromatic ring soluble in an organic solvent (for example, a resin obtained by a solution polymerization in a solvent of 3,3',4-4'-benzophenone tetracarboxylic anhydride with 3,3'-diaminobenzophenone), or of a copolymer of tetrafluoroethylene with 2,2'-bis(trifluoromethyl)-4,5-difluoro-1,3-dioxolene (TEFLON AF: commercial name), and the like.
• An applied film of the aforementioned polymer is made into a thermoplastic polymer film by a heat treatment.
• the laser as light source is a pulse type UV laser, and a multi mode Nd: YAG laser (4th harmonic mode: 266 nm, and 3rd harmonic mode: 355 nm), ArF excimer laser (wavelength: 193 nm), KrF excimer laser (wavelength: 248 nm) or XeCl excimer laser (wavelength: 308 nm). From the viewpoint of easiness of maintenance, YAG laser is more preferable than excimer laser. An energy density (fluence) required for enhancing hydrophilicity is in a range of 10 - 100 mJ/cm 2 .
• the film should have a light absorbance of not less than 1 ⁇ 10 2 cm -1 , preferably 5 ⁇ 10 2 - 5 ⁇ 10 3 cm -1 .
• the laser irradiation can enhance hydrophilicity when the irradiation is carried out in any of the air, water and an alkaline solution such as tetramethyl ammonium hydroxide. Hydrophilicity may be expressed by a change of a contact angle against water.
• a contact angle against water varies from 80° to 0°. in the printing industry, it is proposed that an offset printing is possible if a contact angle against water on a printing plate is not more than 20°. Any printing plates of the present invention suffice this value.
• hydrophilicity of the irradiated part may be maintained for at least several months, for obtaining a practical printing plate, hydrophilicity should be maintained semipermanently.
• a conventional desensitizing method which uses phosphoric acid as a main component may be adopted.
• Picture formation is conducted by scanning and irradiating a laser previously modulated with a image signal.
• an apparatus developed for the other computer-to-plate system can be used only if a laser light source is changed.
• a mask having a image information is laid on the aforementioned thermoplastic polymer film, and the aforementioned laser is irradiated thereon.
• the mask a photographic negative film, a metal mask and the like can be used.
• a printing plate can be manufactured only by using a generally used polymer film and by irradiating a laser beam on the surface, and a printing plate is provided which requires no developing treatment process. Therefore, the present invention is useful for development of the printing industry.
• Kapton film manufactured by Du Pont company; film thickness is 50 ⁇ m
• Nd YAG laser (4th synchronized mode: 266 nm, manufactured by Spectra Physics company, Quanta-Ray GCR-4) at an energy density of 14 mJ/cm 2 and a pulse width of 15 nsec.
• a solution prepared by diluting an etching liquid for light offset printing (Ricoh Fax Etch Liquid) with water was used as a wetting water, An ink sticking characteristic to the surface of the film was examined using a process ink (CAPS-G: manufactured by Dainippon Ink & Chemicals, Inc.) to find that the irradiated part repelled the ink and the ink stuck to the unirradiated part.
• a process ink (CAPS-G: manufactured by Dainippon Ink & Chemicals, Inc.) to find that the irradiated part repelled the ink and the ink stuck to the unirradiated part.
• Kapton film manufactured by Du Pont company; film thickness is 50 ⁇ m
• ArF excimer laser wave length: 193 nm, manufactured by Lambda Physik company
• a solution prepared by diluting an etching liquid for light offset printing (Ricoh Fax Etch Liquid) with water was used as a wetting water.
• An ink sticking characteristic to the surface of the film was examined using a process ink (CAPS-G: manufactured by Dainippon Ink & Chemicals, Inc.) to find that the irradiated part repelled the ink and the ink stuck to the unirradiated part.
• PPQ film (commercially available from CEMOTA company; polyphenylquinoxaline) instead of Kapton film was scanned and exposed to Nd: YAG laser (4th harmonic mode: 266 nm) at an energy density of 14 mJ/cm 2 and a pulse width of 15 nsec.
• a solution prepared by diluting an etching liquid for light offset printing (Ricoh Fax Etch Liquid) with water was used as a wetting water.
• An ink sticking characteristic to the surface of the film was examined using a process ink (CAPS-G: manufactured by Dainippon Ink & Chemicals, Inc.) to find that the irradiated part repelled the ink and the ink stuck to the unirradiated part.
• PPQ film (commercially available from CEMOTA company; polyphenylquinoxaline) instead of Kapton film was scanned and exposed to ArF excimer laser (wave length: 193 nm) at an energy density of 20 mJ/cm 2 and a pulse width of 15 nsec.
• a solution prepared by diluting an etching liquid for light offset printing (Ricoh Fax Etch Liquid) with water was used as a wetting water.
• An ink sticking characteristic to the surface of the film was examined using a process ink (CAPS-G: manufactured by Dainippon Ink & Chemicals, Inc.) to find that the irradiated part repelled the ink and the ink stuck to the unirradiated part.
• etching liquid for light offset printing (Ricoh Fax Etch Liquid) was applied on the film of Example 1, and a desensitizing treatment was conducted to find no change in a contact angle after half a year.
• the aforementioned etching liquid was diluted with water to prepare a wetting water, and printing was conducted.
• a process ink (CAPS-G: manufactured by Dainippon Ink & Chemicals, Inc.) and a fine quality printing paper were used.
• a printed article having an excellent image reproductivity equivalent to a conventional PS plate was obtained.
• a mask having a image information was closely laid on Kapton film (manufactured by Du Pont company; film thickness is 50 ⁇ m), and thus obtained complex was exposed to Nd: YAG laser (3th harmonic mode: 355 nm, manufactured by Spectra Physics company, Quanta-Ray GCR-4) at an energy density of 14 mJ/cm 2 and a pulse width of 15 nsec.
• Nd YAG laser (3th harmonic mode: 355 nm, manufactured by Spectra Physics company, Quanta-Ray GCR-4) at an energy density of 14 mJ/cm 2 and a pulse width of 15 nsec.
• An etching liquid for light offset printing (Ricoh Fax Etch Liquid) was diluted with water to prepare a wetting water, and printing was conducted.
• a process ink (CAPS-G: manufactured by Dainippon Ink & Chemicals, Inc.) and a fine quality printing paper were used. An excellent printed article which reproduces a image of the mask was obtained.
• An diethyleneglycoldimethylether solution of polyamide acid having a solid content of 30% (viscosity at 25°C: 20,000 cps) obtained by a solution polymerization in a solvent of 3,3',4-4'-benzophenonetetracarboxylic anhydride with 3,3'-diaminobenzophenone was applied (wet film thickness: 7 ⁇ m) on an aluminum plate by a spin coater. Thermosetting was conducted at 300°C for 30 minutes.
• Nd YAG laser (4th harmonic mode: 266 nm, manufactured by Spectra Physics company, Quanta-Ray GCR-4) at an energy density of 14 mJ/cm 2 and a pulse width of 15 nsec.
• a solution prepared by diluting an etching liquid for light offset printing (Ricoh Fax Etch Liquid) with water was used as a wetting water.
• An ink sticking characteristic to the surface of the film was examined using a process ink (CAPS-G: manufactured by Dainippon Ink & Chemicals, Inc.) to find that the irradiated part repelled the ink and the ink stuck to the unirradiated part.
• N-methylpyrrolidone solution of a soluble polyimide (commercial name: MATRIMIDE 5218, manufactured by CIBA-GEIGY company) (solid content: 20%) was applied on an aluminum plate by a spin coater. Drying was conducted to remove the solvent.
• Nd YGA laser (4th harmonic mode: 266 nm, manufactured by Spectra Physics company, Quanta-Ray GCR-4) at an energy density of 14 mJ/cm 2 and a pulse width of 15 nsec.
• a solution prepared by diluting an etching liquid for light offset printing (Ricoh Fax Etch Liquid) with water was used as a wetting water.
• An ink sticking characteristic to the surface of the film was examined using a process ink (CAPS-G: manufactured by Dainippon Ink & Chemicals, Inc.) to find that the irradiated part repelled the ink and the ink stuck to the unirradiated part.
• Example 1 The film of Example 1 was scanned and exposed to ArF excimer laser (wave length: 193 nm) at an energy density of 20 mJ/cm 2 and a pulse width of 15 nsec.
• a solution prepared by diluting an etching liquid for light offset printing (Ricoh Fax Etch Liquid) with water was used as a wetting water.
• An ink sticking characteristic to the surface of the film was examined using a process ink (CAPS-G: manufactured by Dainippon Ink & Chemicals, Inc.) to find that the irradiated part repelled the ink and the ink stuck to the unirradiated part.
• a copolymer of tetrafluoroethylene with2,2-bis(trifluoromethyl)-4,5-difluoro-1,3-dioxolene soluble in an organic solvent was dissolved in fluorohydrocarbon, and the resulting solution was spin-coated on an aluminum plate. Drying with heating was conducted to evaporate the solvent. A wet film thickness was previously controlled so as to obtain a dry film thickness of 10 ⁇ m.
• the coating film was doped by 25% by weight of tri-C 9 F 18 substituted triazine, then was heated at 200°C for 1 hour and irradiated by an ultraviolet beam to find an improved ultraviolet absorption (absorbance: 0.14, wave length: 240 nm).
• an ultraviolet absorption as Absorbance: 0.14, wave length: 240 nm

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• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Photosensitive Polymer And Photoresist Processing (AREA)
• Printing Plates And Materials Therefor (AREA)
• Manufacture Or Reproduction Of Printing Formes (AREA)
• Printing Methods (AREA)

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Cited By (6)

Citations (5)

• 1995
  • 1995-05-16 JP JP11712595A patent/JPH08310148A/ja active Pending
• 1996
  • 1996-05-15 EP EP96107779A patent/EP0743177A1/de not_active Withdrawn

Patent Citations (5)

Non-Patent Citations (3)

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