US2217544A

US2217544A - Method of treating photographic material to obtain colored pictures

Info

Publication number: US2217544A
Application number: US274837A
Authority: US
Inventors: Goldfinger Paul
Original assignee: Individual
Current assignee: Individual
Priority date: 1938-05-27
Filing date: 1939-05-20
Publication date: 1940-10-08
Anticipated expiration: 1957-10-08
Also published as: GB535130A; BE434581A; FR855366A

Description

Patented Oct. 8, 1940 UNITED STATES METHOD OF MATERIAL TURES TREATING PHOTOGRAPHIC TO OBTAIN COLORED PIC- Paul Goldfinger, Brussels-Uccle, Belgium, assignor to Bla. Gaspar, Brussels, Belgium No Drawing.

Application May'20, 1939, Serial No. 274,837. In Germany May 27, 1938 I 4 Claims.

The present invention relates to a treatment bath for the production of dye-images from uniformly dyed photographic silver imagesby treat- 1 ing solutions that locally destroy the dye pres- 5 ent in the layer at the areas where metallic silver is present, and in proportion to the quantity of such silver. Aqueous solutions of hydrohalic acids are already known as treatment solutions suitable for this purpose. It is moreover known that the eflicacy of such baths may be intensified by the addition of various chemicals; particu- (1) Hydrochloric acid 1.8% litre 1 Potassium iodide grams.. 2.2 (2) Hydrochloric acid 1.8% litre 1 Potassium iodide grams 2.2

2,3-dimethyl-quinoxaline; gram 1' (3) Hydrochloric acid 0.6%..-- litre 1 Potassium iodide grams 3.3 2,3-dimethyl-quinoxaline "gram" 0.2

The increase in the efficacy of the new baths is shown by the following comparative test, viz.: 0.1% of dimethyl-quinoxaline is added to a 0.51). hydrochloric acid. Metallic silver images dyed with'Brillantbenzoechtgriin BL, Benzoazurine G (Schultz Farbstofftabellen, Leipzig 1931, 7th ed., vol. 1, No. 497) or with Chrysophenin G (Schultz Farbstofftabellen l. e., No. 726) are treated with this solution and dye-images are obtained within about four minutes. If the solution contains in addition such a, quantity of potassium iodide that in respect of this salt the solution is 1/ 7511 silver images dyed in the same manner are converted to dye-images much more speedily and successfully, i. e., in about one minute. A silver image dyed red with Supranolbrillantrot B (Schultz Farbstoiftabellen, Leipzig 1932, 7th ed., vol. 2,

page 204) when treated for six minutes in a bath without the addition of potassium iodide yields but an unsatisfactory dye-image, whereas a good dye-image is obtained within three minutes if a bath containing the potassium iodide is employed. Even the addition of a much smaller proportion of potassium iodide, say one-five-hundredth mol per litre, is still effective.

56 The dyes cited above are to be understood as but examples; suitable dyes are also the other known dyes used in the art, in particular azo dyes, such as the .yellow Xylenwalkgelb G (Schultz Farbstofftabellen, Leipzig 1932, 7th ed., vol. 2, page 232), the blue Diaminreinblau FF 6 (Schultz Farbstofftabellen, Leipzig 1931, 7th ed., vol. 1 No. 510) and the red Polarbrillantrot B (Schultz Farbstoiftabellen, Leipzig 1932, 7th ed., vol. 2, page .An addition to the bath of hydrobromic acidor bromides also is effective, 10 but to a'less degree than hydroiodic acid. On the other hand; the addition of hydroiodic acid to a hydrobromic acid bath' is even more -eifectivethan to a hydrochloric acid solution, for the hy-. drobromic acid treating baths are in themselves 15 more effective than hydrochloric acid solutions. However, in view of the question of greater econ-' omy, the tests as to the accelerating effect were mainly carried out in connectionwith hydrochloric acid baths. 20

In the course of these experiments, other chemicals were tested as to their accelerating effect,

and it was found that not only iodides and bro-p mides, but also sulphocyanides, such as am-' monium-sulphocyanides and thiocarbamide, in- 25 I crease the efiect of a hydrochloric acid bath. These experiments werecarried out with a 0.5n hydrochloric acid, to which was added 0.1% of dimethylquinoxaline and in addition either 0.01 mol of thiocarbamide or 0.01 mol of ammonium so sulphocyanide or 0.01 mol of potassium. bromide for each litre of solution. In the case of the silver image dyed with Diaminreinblau FF, the bath containing thiocarbamidehad the speediest effeet. When the images were dyed with Benzol- 5 ichtrot (Schultz Farbstofftabellen, Leipzig 1931, 7th ed., vol. 1, No. 566) or with Brillantbenzoechtgriin BL, it turned out that potassium bromide and ammonium sulphocyanidehad the greatest accelerating effect. On the other hand, in every 40 experiment it was found that the effect of thiocarbamide, sulphocyanide and bromide was surpassed by the effect of the iodide. The effect of the additional component to the bath appears to be due to'the fact that the substances used, and

especially the hydroiodic acid, reduce" the con-, centration of free silver ions in the aqueous solution to a greater extent than does the hydrochloric acid. 1

-It will probably also be due to this fact that the hydroiodic acid or other substance added to the solution may be employed in such a quantity that the hydrochloric acid is present in an excess to the equivalent amount of the added substance. When using hydroiodic acid as the addition toss hydrochloric acid, useful baths were obtained when the concentration of the solution in respect of hydrochloric acid was from 0.111, to normal, and in respect of hydroiodic acid from 0.00211. to 0.1n. It follows as a matter of course that higher or lower concentrations are quite possible,

' and that the limits mentioned above designate only a range of concentration that is to be recommended for practical purposes.

What is claimed is: v 1. For the production of colored photographic pictures by means of local destruction of the dye at areas where metallic silver is present in photographic layers uniformly dyed with reduci-- ble dyes, a treating bath comprising an acid aqueous solution of hydrochloric acidvand hyd'roiodic acid, the concentration of chloride ions ranging from 0.1 normal to 1.0 normal, the concentration of iodide ions ranging from 0.002 normal to 0.1 normal.

2. For the production, of colored photographic pictures by means of local destruction of the dye at areas where metallic silver is present in photographic layers uniformly dyed with reducible dyes, a treating bath comprising an acid aqueous solution of hydrochloric acid and hydroiodic acid, the concentration of'chloride ions ranging from 0.1 normal to 1.0 normal, the concentration of iodide ions ranging from 0.002 normal to 0.1' normal, the bath further comprising a small amount of dimethyl-quinoxaline.

3. For the production of colored photographic pictures by means of local destruction of the dye at areas where metallic silver is present in;

photographic layers uniformly dyed with reducible dyes, a treating bath comprising hydroiodic acid and hydrochloric acid in an at least ten-fold excess to the equivalent amount of hydroiodicacid, the concentration of the iodide ions ranging from 0.002-normal to 0.1-normal.

4. For the production of colored photographic pictures by means of local destruction of the dye at areas where metallic silver is present in