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
  • B41C1/1066—Forme preparation for lithographic printing; Master sheets for transferring a lithographic image to the forme by spraying with powders, by using a nozzle, e.g. an ink jet system, by fusing a previously coated powder, e.g. with a laser

Definitions

• the invention relates to a method for producing offset printing plates using the ink jet method.
• the solution to this problem is based on a method for producing offset printing plates using the ink jet method, which is characterized in that an offset printing plate support is imaged with an ink which forms oleophilic image components and the sprayed-on image is dried.
• the printing plate support can be treated during or after the imaging at an elevated temperature in the range from approximately 80 to 200 ° C. This means that the sprayed and dried image is hardened or baked.
• An uncoated offset printing plate tracer is preferably used.
• offset printing plates can now be produced quickly in a simple manner without the necessary precoating and without the use of complicated development steps. Expensive and complex optical Exposure systems can be saved according to the invention.
• Suitable inks forming oleophilic image constituents are aqueous dispersions of oleophilic resin particles, which can also be pigmented, or dispersions of optionally pigmented resin particles in organic solvents.
• the liquid developers known from electrophotography which represent pigmented resin particles dispersed in petrol-like solvents, are preferably used. This can e.g. Full areas can be reproduced with a small order quantity.
• the liquid developers are preferably used as a developer concentrate.
• the resin particles that can be used in accordance with the invention must meet the requirements for stress during several thousand printing processes and have good adhesive force on the offset printing plate carriers. This can be improved, if necessary, by post-curing the finished printing plate at an elevated temperature up to about 200 ° C.
• the dispersed resin particles of the invention are generally more demanding than e.g. on ink materials of the known type.
• offset printing plate carriers everyone is in printing technology known printing forms, such as metal foils and plates, multi-metal plates, plastic films, cellulose-based substrates, etc. are suitable. In particular, metallic supports made of aluminum are used. These carriers are expediently roughened mechanically or electrochemically on the surface and, in special cases, anodized. Aluminum offset printing plate supports, which are provided with a microporous aluminum oxide layer, are particularly preferred.
• the printing plate supports can be used uncoated according to the invention, it can be advantageous in some cases to provide a coating which improves the printing properties.
• Such coatings consist for example of polyvinyl phosphonic acid or of potassium or sodium silicate.
• the method according to the invention not only permits the production of single-color prints, in particular black and white prints, but can also be used for multi-color printing. This is possible if the data is in digitized form. From each color separation (for example cyan blue, yellow, magenta and black in four-color printing), the analog image data supplied by an optical image scanner is digitized with an analog / digital converter and onto one Grid evaluation unit given. This unit creates halftone dots of different sizes by means of a mosaic-like composition from the fine ink-jet dots, which is easily possible, since print heads with 14 dots / mm can already be built. The offset printing plate produced in this way from each color separation is then colored with the corresponding printing ink, so that multicolor printing can be carried out in a known manner.
• aqueous copolymer dispersion of vinyl acetate and a maleic acid derivative (approx. 55%) was diluted 2: 1 with water. Approx. 30 ml of this diluted dispersion were now poured into the reservoir of a Grafo spray gun and the spray gun was connected to a compressed air line with about -3 bar.
• a writing template plastic film, letters cut out was then placed on an anodized aluminum printing plate support 280 ⁇ m thick and the dispersion was sprayed with the spray gun until a homogeneous film had formed at the image points.
• the printing plate was then dried in a drying cabinet at a temperature of 120 ° C. for 5 minutes.
• the anodized surface of the printing plate was treated with a cleaning or hydrophilizing solution.
• the printing plate surface with a Potassium permanganate solution pretreated and post-treated with an enriched H202 solution. Good prints were obtained on a Dualith 500 printing machine.
• an electrophotographic liquid developer which consists of pigmented polymer particles, which contain protective colloids, control agents and, if appropriate, dispersion aids dispersed in an electrically insulating organic carrier liquid, as can be found in DE-OS 23 33 064.
• a liquid developer concentrate are poured into the reservoir of a spray gun, the nozzle diameter of which is 0.8 mm.
• the liquid developer concentrate is pigmented polymer particles which, together with the usual constituents, are dispersed up to about 10% in an electrically insulating hydrocarbon as carrier liquid.
• This concentrate was sprayed with compressed air of about 3 bar onto a printing plate support as in Example 1 using a stencil. The imaged printing plate was then dried in the drying cabinet at a temperature of 120 ° C. for 5 minutes.
• the printing plate was treated with potassium permanganate solution and then with H 2 0 2 solution and then rinsed with water The printing plate was then rubbed with a gum arabic solution. Perfect prints were obtained on a printing press.

Landscapes

• Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Manufacture Or Reproduction Of Printing Formes (AREA)
• Duplication Or Marking (AREA)
• Printing Plates And Materials Therefor (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=6032253

Family Applications (1)

Country Status (3)

Cited By (9)

Families Citing this family (11)

Citations (4)

• 1978
  • 1978-02-17 DE DE19782806802 patent/DE2806802A1/de not_active Withdrawn
• 1979
  • 1979-02-12 EP EP79100401A patent/EP0003789A1/fr not_active Withdrawn
  • 1979-02-15 JP JP1556079A patent/JPS54117203A/ja active Pending

Patent Citations (4)

Non-Patent Citations (2)

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