DE1123337B - Etching process for the production of planographic printing forms - Google Patents

Description

The plates used for etching in planographic or offset printing processes have so far been general usual etchant solutions, especially those solutions that are used to etch multi-metal plates with Chromium surface have the disadvantage of developing strong hydrochloric acid vapors their use becomes uncomfortable and even harmful.

To avoid this disadvantage, an etching process, preferably for etching, is used according to the invention of single-metal or multi-metal plates intended for flat or offset printing, in which the free Hydrochloric acid (hydrochloric acid) of the etchant solution bound by a weak organic base will.

In the compound obtained in this way, the hydrochloric acid is not found as in the previously customary etchant solutions in the free state, but in conjunction with an organic base which is sufficiently weak is that the solution of their chloride is very acidic.

The combination of a strong acid with a weak base is known to give salts, their Solutions are ionized and strongly acidic.

The concentration of the ions contained in the solution of such a compound is large enough to To attack zinc or chromium, but without producing hydrochloric acid vapors as when using of free hydrochloric acid in the etchant solution.

Urea or its derivatives can be used as the organic base, as can any other organic substance containing an amino or amido group of weakly basic character and suitable is to form salts with strong mineral acids, the solutions of which react strongly acidic.

The individual components need not necessarily be provided in equimolecular amounts Rather, one can be in excess in relation to the other.

A solution that practically does not develop any acid fumes and is suitable for the rapid etching of chromium is obtained, for example, from the following combination:

60 · 10 ^{: i} l hydrochloric acid of 22 Baume concentration, 48 g urea,

1 1 calcium chloride solution enriched at 41 ° Baume.

The calcium chloride solution can be replaced by a zinc chloride solution or by a Mixture of calcium and zinc chloride or any other soluble chloride.

Etching process for manufacture
of flat printing forms

Applicant:

Societe Technique d'Applications Chimiques et Physiques, Paris

Representative: Dipl.-Ing. A. Boshart

and Dipl.-Ing. W. Jackisch, patent attorneys,

Stuttgart. Birkenwaldstrasse 213 D

Claimed priority:
France of September 14, 1959 (No. 805 098)

Jean Stamboulian, Paris,
has been named as the inventor

For zinc etching, a non-smoking etchant solution can be obtained in the following way:

22 · ΙΟ * ³ 1 pure hydrochloric acid,

11 g urea,

1 1 of a solution of calcium chloride at 41 ° Baume, to which zinc chloride has been added, until the concentration increases to 51 ° Baume Has.

Of course, the concept of the invention is not limited to the examples given above, but rather countless variants can be derived from these, none of which are out of the ordinary of the invention falls out.

Claims (2)

PATENT CLAIMS: 1. A method for etching single or multi-metal plates for the production of planographic or offset printing forms, characterized in that the free hydrochloric acid contained in the etchant is bound by a weak organic base in such a way that the formation of corrosive acid vapors is prevented. 2. The method according to claim 1, characterized in that urea or a base of its derivatives is used.