Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D5/00—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures
  • B05D5/04—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures to obtain a surface receptive to ink or other liquid
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M1/00—Inking and printing with a printer's forme
  • B41M1/02—Letterpress printing, e.g. book printing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D2202/00—Metallic substrate
  • B05D2202/20—Metallic substrate based on light metals
  • B05D2202/25—Metallic substrate based on light metals based on Al

Definitions

• the invention relates to a material having a hydrophilic surface sealing, and to a method for producing it.
• Such a material can be used as support for a radiation-sensitive layer of an offset printing plate.
• a printing image is photomechanically copied, image-free locations on the support being formed by removing the corresponding areas of the radiation-sensitive layer. Simultaneously, the image- free locations form the background of the image.
• the image locations are hydrophobic and colour-absorbing and the image-free locations are hydrophilic and thus repel the oily or oleophilic printing colours.
• the support must ensure a good adhesion of the radio-sensitive layer in the image areas.
• the prior art suggests an additional coating, the so-called sealing, between the support and the radio- sensitive layer for improving the adhesion of the latter and preventing staining of the support.
• Known methods are for instance the sealing with silicate, with condensed aryl sulfonic acid (DE-A-32 17 870) , with polyvinyl phosphonic acid (PVPA) (DE-A-16 21 478) or with an aqueous mixture of a hydrolysate or a condensate of a silane and a fluoride of an alkali metal or of the metals Ti, Zr or Si (DE-A-39 28 794) .
• EP-A-0 089 510 discloses a support material of aluminum or an alloy thereof which is covered with a hydrophilic sealing layer which is produced inter alia by using polyvinyl phosphonic acid with admixtures of silicates, borates and fluoroborates. These admixtures improve the adhesion of the image, the shelf-life of the radiation-sensitive layer, the hydrophilic action and the resistance to SnCl 2 .
• the problem underlying the invention is to provide a support material having a hydrophilic surface sealing and a method for producing it by means of which the support characteristics are further improved and a universally usable sealing is achieved which has advantages for positively, negatively as well as for instance electrophotographically working printing plates.
• the solution according to the invention is based on the idea to mix polyvinyl phosphonic acid with hydrofluoric acid as an agent which etches the support surface, and to use this as sealing solution.
• the invention makes it possible to develop also strongly tinted coatings with weak positive developers in a staining-free manner.
• the amount of hydrophilizing PVPA may be increased without impairing the adhesion of the coating and thus the pressure stability.
• the sealing solution according to the invention allows the sealing of mechanically and electrolytically roughened surfaces as well as of surfaces which are galvanically plated with chromium. In the following, the invention is explained in detail by means of Examples.
• An electrolytically grained aluminum substrate was anodized in sulfuric acid to 4 g/m 2 oxide. After repeated rinsing with deionized water the plate was dipped in the following sealing solution: 0.5 g/1 PVPA and 0.3 g/1 HF (100 %) , at a temperature of the bath of 50 ⁇ C for 10 seconds. This was followed by a rinse of tap water, squeegee and drying at 100°C for l min.
• the resulting sealed basis was coated with the following positive solution (indicated in parts by weight) :
• Example 2 (negative plate) A basis sealed as in Example 1 was coated with the following solution (indicated in parts by weight) :
• a coating weight of 0.7 g/m 2 was obtained.
• 988 B - 1 1 988 B contains 10 g diethanol amine, 10 g sodium octyl sulfate and 980 g water - , a shorter exposure time was found compared to a basis which was only sealed with PVPA. During printing, wear appeared considerably later than with the comparative plate which had been exposed to the same solid layer.
• Example 1 For comparison, the aluminum support of Example 1 was treated with a conventional coating solution.

Landscapes

• Printing Plates And Materials Therefor (AREA)
• Photosensitive Polymer And Photoresist Processing (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=6450852

Family Applications (1)

Country Status (4)

Cited By (4)

Families Citing this family (1)

Citations (1)

• 1992
  • 1992-02-03 DE DE19924203010 patent/DE4203010C1/de not_active Expired - Lifetime
• 1993
  • 1993-02-02 EP EP93914522A patent/EP0625175A1/en not_active Ceased
  • 1993-02-02 CA CA002129243A patent/CA2129243A1/en not_active Abandoned
  • 1993-02-02 WO PCT/EP1993/000235 patent/WO1993015156A1/en not_active Ceased

Patent Citations (1)

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