US1692528A - Method for the manufacture of bichromate-glue printing plates for hand printing or press deep printing - Google Patents

Description

Patented Nov. 20, 1928.

TUNII'T'ED'ISTATESV PATENT osnciz.

lj MAX WIELAND, or BERLIN-rEMPn-LHoF, GERMAu METHOD FORTHE MANUFACTURE OF BICHROMzlTE-GLUE PRINTING PLATES 150R UT-HAND PRINTING on PRESS'DEEP PRINTING.

No Drawing. -Applieat'ion filed November 7, 1924, Serial No 748,487, and in'Germany November 13, 1923.

' Renewed September 22, 1928.

'My invention relates to a method for the manufacture of. blchromate-glue pr nting plates, especiallysuch for handprinting and press deep-printing, and the subjectunatter 5 of the invention IGSlClBS'lIl mixing a glue or an equivalent substance which is able toswell in liquid state, with a hydraulic agglutinant or cementing medium which. is able to set,

suchas cement, gypsum, or'the like, the purpose being to increase the resistant capacity of the printing plates, the mixture being thenapplied in liquid state on to the plates or upon bands. 1 The admixture of the hydraulic agglutinant or cementing medium or the like, such for instance as stated, to the liquid glue of a kind as stated answers the purpose if the respectiveagglutinant or cementing medium is admixed to the respective glue in a proportion in which the swelling capacity of the layer of certain depth of that layer.

As the layer of the agglutinant or cementing medium is completely penetrated by the glue it remains united firmly and organically with the layer o'it' glue that separates at the surface of the mixture.

Owing to the admixture of the agglutinant or cementing medium the inner strength or resistant capacity of the form is increased and the period of time during which the form can be utilized practically is extended in comparison to the known forms which consist only of layers of glue. To increase the setting capacity of the cementing medium a certain amount of finely ground quartz can be added to the mixture.

In order to render the novel. method as actually used more comprehensive, there will be described in the following the accurate method of producing bichromate glue printknown methods.

ing plates taking into"consideration the 4 ing so-called photo-printingform's is based on the formation of a grain of irregular.

shape. This production of the irregular grain layer in the upper part of gelatine which has been sensitizedagainst light b chromic acid salts is a dry process and is carglue is not ail'ected downto a The generally known method 'for pr0duc- I and depending Y repelling them, and in aplate for printing. 7

Injthe present method, however, we want to produce a relief suitable for printing and x which may be used directly as a recessed printing form (intaglio). r 60.

A viscous mass, that is colloid, as for instance gelatine, glues which mayswel-l up, etc, ismixed with'a hydraulic binder in order to impart to the gelatine or some other suit able acting substance the required rigidity. For instance a substance of 10% gelatine is mixed with 2 to4% of extremely fine ground Portland cement. But it is necessary to be very carefully on the look-out to note that the hydraulic binder must be ground so fine that this addition'is combined or solidified in colloidal state. It is, therefore, most advisably ground in the 1 well known colloid grinder of Paulson, together with alcohol. g

This mass which 'is'not sensitized is then poured upon the carrier of the emulsion. The carrier maybe any suitably selected material, as for instance a strip of aluminium or plates made from some other substance. The mass after having been poured on it becomes rigid and the binder organically tied up with thecolloid will settle downward," forming thereby a skeleton structure of carrying ribs which taper to a point upward so as to have triangular cross-section. The glue itself is then near the top ineXcess. The specifically heavier binder, however, ads heres very firmly on they lower surface to the carrier and in this wayabsolutely guaran- 9 tees a permanent connection of the congealed substance with'the carrier.

These plates orstripsmay be prepared in the manner described in daylight, since they V have not been sensitized yet. In this manner there is assured the possibility of maintaining in stock these plates or strips in larger quantities without risking the danger that they spoil in time.

If thenthis plate or it is sensitized in the darker room by immersing it for short time in a chromic acid salt solution. Then it is dried, placed underneath the negative to be printed and is ex-x posed for a (short time in a known way. 7

After. washing out-then the sensitizing salts there is obtained a tanned'reliet suitable for intaglioprinting and which upon thatway it; produces 55 1 application of the printing ink absorbs more or less of the ink.

WVhen the printing forms have become solid they are rendered sensitive in lmown manner with the aid of a bichroinate, and when the plates have been exposed under a photographic negative or the like they are further treated also in'known manner.

I am aware of the proposal to add powdered stone to a gelatine-niass in order to serve as a filling material therefor and to render the 'mass more absorbing for moisture, but the powdered stone or equivalent sub: stance employed has not been such that is capable of setting so, that the particles thereoi are not able to "form a solid structure and to increase the resisting capacity of the print i-ng plate, especially as regards tensile stress.

I claim:

1. In the method of producing chromic acid salt colloid printing plates the step of mixing a colloid with a hydraulic binding substance in such proportions as to preserve the ability of the colloid to swell.

2. In the method of producing chromic acid salt colloid printing plates the steps of mixing a colloid with a'hydraulic hardening and binding substance in such proportions as to preserve the ability of the colloid to swell and pouring the resulting mass on a base to harden thereon to produce .a rigid layer with a chromic .i cid salt.

3. The method of producing chromic acid salt colloid printing plates consisting in mixing a colloid with a hydraulic hardening and binding substance in such proportions as to preserve the ability of the colloid to swell; pouring the resulting mass upon a :base to harden thereon to produce a rigid layer, sensitizing said layer and exposing and .de: veloping the same. i

, In testimony whereof I affix my signature.

winLAnn.