Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41N—PRINTING PLATES OR FOILS; MATERIALS FOR SURFACES USED IN PRINTING MACHINES FOR PRINTING, INKING, DAMPING, OR THE LIKE; PREPARING SUCH SURFACES FOR USE AND CONSERVING THEM
  • B41N3/00—Preparing for use and conserving printing surfaces
  • B41N3/03—Chemical or electrical pretreatment
  • B41N3/034—Chemical or electrical pretreatment characterised by the electrochemical treatment of the aluminum support, e.g. anodisation, electro-graining; Sealing of the anodised layer; Treatment of the anodic layer with inorganic compounds; Colouring of the anodic layer
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
  • C25D11/02—Anodisation
  • C25D11/04—Anodisation of aluminium or alloys based thereon
  • C25D11/06—Anodisation of aluminium or alloys based thereon characterised by the electrolytes used

Definitions

• Aluminum in the present specification this term includes aluminum alloys
• this term includes aluminum alloys
• aluminum alloys has often been used as a support for printing plates because of its excellent flexibility and dimensional stability, light weight, price and ready availability. Utilizing these advantages, aluminum has further been used for building materials, improved weather resistance being obtained by forming an oxide layer on the surface of the aluminum. The formation of such an oxide film layer has hitherto been carried out by anodic oxidation in an electrolytic solution of sulfuric acid, oxalic acid or chromic acid, as is well known in the art.
• a method for the surface treatment of an aluminum plate which comprises subjecting the aluminum plate to anodic oxidation in an aqueous solution containing -50 percent by weight of trisodium phosphate (based on the total aqueous solution by weight) at a liquid temperature of 20-40C and at current density of 5-20 volts, 0.8-3 amperes per 1 dm for 3-10 minutes.
• the process is always practiced at atmospheric pressure, though if one wishes sub or super atmospheric pressure can be used. Little is to be gained by such operation, however.
• the aluminum plate pure aluminum plates and alloy plates such as aluminum alloys with copper, zinc, magnesium and iron are used.
• Such an aluminum plate is generally subjected to a pretreatment to remove stains and oily materials, for example, by immersing in a 5-15 percent by weight aqueous solution of sodium hydroxide for 30-90 seconds, washing with water and then treating with a percent by weight solution of ammonium bifluoride.
• Any standard art technique for degreasing can be used in the present invention.
• Other known method include trisodium phosphate treatment and treatment with organic solvents such as trichlorostyrene, carbon tetrachloride and the like.
• the anodic oxidation treatment characteristic of the invention is then carried out in an aqueous solution containing 5-50 percent by weight, preferably 10-30 percent by weight, of trisodium phosphate at a temperature of 2040C and a current density of 5-20 volts, 0.8-3 amperes per 1 dm preferably 8-15 volts, 0.8-2 amperes, for 3-10 minutes, preferably 4-8 minutes.
• Excellent results are provided when the anodic film is deposited in an amount of about 10 mg to about 200 mg per square meter of support, more practically for commercial usage, at about 50 mg to about mg per square meter of support. These ranges are not, of course, limitative, but provide a product of excellent properties.
• a relatively inert material such as lead is used as a cathode.
• the present invention is not limited to lead as a cathode, though this is commonly used because of its low cost and the fact it is not corroded by the electrolytic solution.
• Aluminum and other materials can also be used, though for economic reasons lead will usually be used.
• the thus obtained aluminum support is an excellent support for plate making.
• a thin layer of a water-soluble high molecular weight compound can be provided on the anodic oxide film weight as occasion demands. Excellent results are obtained when such a water-soluble high molecular weight compound is provided in a thickness of 0.05 microns to 0.2 microns, better yet about 0.1 micron.
• water-soluble high molecular weight compound examples include polyvinyl alcohol, polyacrylamide, polyvinyl pyrrolidone, gelatin, hydroxyethyl cellulose, carboxymethyl cellulose, casein and sodium alginate.
• the water-soluble high molecular weight compound is generally provided in an amount of about 10-30 per 1 m by coating or immersing.
• the hydrophilic property of the substrate is further increased by providing such a film of the water-soluble high molecular weight compound.
• good results are provided when the high molecular weight compound has a molecular weight of from about 10,000 to about 500,000, better yet from about 50,000 to about 150,000. This includes most materials as above as they are commercially available.
• a higher hydrophilic property is given by carrying out a graining treatment prior to the above described anodic oxidation.
• KPR Kodak Photo Resist, manufactured by Eastman Kodak Co.
• KPR has, as its active chemical constituents the repeating group:
• These materials are high molecular weight compounds having the following recurring structural unit (generally, these materials are available at a molecular weight of from about l0,000 to about 500,000, and are most preferably used at a molecular weight from about 50,000 to 100,000):
• a suitable solvent for example, cellosolve acetate, in which a pigment and/or a sensitizer is dispersed, and then coated onto the aluminum plate subjected to the above mentioned anodic treatment, thus obtaining the desired plate for printing plate manufacture.
• the thus resulting material is then brought into intimate contact with a transparent negative and exposed to a high voltage mercury lamp to yield insoluble exposed areas.
• the non-exposed areas i.e., background, can be removed with a suitable organic solvent such as dimethylformamide or cellosolve acetate which does not affect the exposed areas.
• the sensitizer 5-nitroacenaphthene, Michlers ketone and 2,4,7-trinitrofluorenone are preferably used.
• a suitable pigment is copper phthalocyanine.
• sensitizer from about 1 percent to about 15 percent of a sensitizer, more preferably 3 weight percent to 10 weight percent, is used in most commonly encountered systems, and such usually provides excellent results. This range is not, however, limitative.
• the printing plate using the aluminum plate processed according to the invention is excellent with respect to adhesiveness to an image forming film, water maintenance on non-image areas prevention of adherence of ink to incorrect portions of the printing plate and maintenance of water on correct portions of the printing plate and wear resistance, that is, printing resistance, which are favourably compared with those of the prior art.
• EXAMPLE 1 ous solution of trisodium phosphate at a liquid temperature of 30C for 5 minutes with a lead plate cathode. The voltage was 10 volts and the current density was l ampere per 1 dm The plate was then taken out of the electrolytic bath and washed well with water. The thus treated aluminum plate was coated with a solution forming a lightsensitive layer having the following composition, followed by drying.
• the resulting printing plate was brought into intimate contact with a transparent negative, exposed for about seconds with a 50 watt mercury lamp at 10 cm using a Plano PS Printer A 3 (made by Fuji Photo Film Co.) and developed, by rubbing the surface with an absorbent cotton pad impregnated with cellosolve acetate at room temperature for about half a minute. The high molecular weight compound at non-exposed areas was dissolved and the hydrophilic surface appeared.
• EXAMPLE 3 An aluminum plate which had not been sand set was treated by immersion in a percent by weight aqueous solution of caustic soda for 30 seconds and then in a 10 percent by weight aqueous solution of ammonium bifluoride for 90 seconds and washed well with distilled water. All processings were at room temperature.
• the treated plate was then subjected to anodic oxidation by immersing it as an anode in a percent by weight aqueous solution of trisodium phosphate at a liquid temperature of 30C for about 6 minutes with a lead plate cathode.
• the voltage was 12 volts and the current density was 1.2 amperes per 1 dm
• the plate was then taken out of the electrolytic bath and washed well with water.
• the resulting aluminum plate was coated with the light-sensitive solution used in Example 1 to a thickness of about 1.5 microns, followed by drying.
• Example 1 When the resulting plate was exposed and developed, followed by printing, all as in Example 1, about thirty thousands good image quality prints were obtained, but the printing resistance was inferior to that of Example 1. This was possibly due to the fact that the water maintenance was lowered due to lack of sand setting.
• EXAMPLE 4 An aluminum plate which had previously been grained by brushing was immersed at room temperature in a 10 percent by weight aqueous solution of caustic soda for 30 seconds and then in a 10% by weight aqueous solution of ammonium bifluoride for 90 seconds to remove oily substances thereon and washed with distilled water for 10 minutes. All these processings were at room temperature.
• the thus treated aluminum plate was then subjected to anodic oxidation by immersing it as an anode in a percent by weight aqueous solution of trisodium phosphate at a liquid temperature of C and applying a voltage of 12 volts at a current density of 1.5 ampere/dm for 4 minutes, using an apparatus as described in Example 1.
• the plate was then taken out of the electrolytic bath, washed well with water and dried.
• the plate was then coated with a 0.2 percent by weight aqueous solution of polyvinyl alcohol (hydrolysed to percent, molecular weight about 10,000) followed by drying, the dry thickness of the polyvinyl alcohol layer was 0.05 p.) and then coated with a lightsensitive solution having the following composition to give a coating thickness of about 2 microns and a proportion of about 2.3 g/m poly-y-cinnamoyloxy-fi-oxypropyl 1 part methacrylate (molecular weight about 150,000-170,000)
• a printing plate comprising image and nonimage areas, the image areas being carried on an aluminum plate which has been subjected to anodic oxidation as in claim 1.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Printing Plates And Materials Therefor (AREA)
• Electrochemical Coating By Surface Reaction (AREA)
• Photosensitive Polymer And Photoresist Processing (AREA)

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Citations (5)

• 1972
  • 1972-06-03 JP JP5547172A patent/JPS5432424B2/ja not_active Expired
• 1973
  • 1973-06-01 GB GB2636673A patent/GB1409625A/en not_active Expired
  • 1973-06-01 FR FR7320000A patent/FR2187937B1/fr not_active Expired
  • 1973-06-04 US US00367068A patent/US3836437A/en not_active Expired - Lifetime
  • 1973-06-04 DE DE2328311A patent/DE2328311A1/de active Pending

Patent Citations (5)

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