US2453347A - Stabilization of photographic prints with thiophenols - Google Patents

Description

Patented Nov. 9, 1948 i v UNITED STATES PATENT OFFICE STABILIZATION OF PHOTOGRAPHIC PRINTS WITH THIOPHENOLS Harold D. Russell, Rochester, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application November 30; 1946, Serial No. 713,383

Claims. (01. 95-88) 1 v 2 This invention relates to photography and paris exposed in the usual way and is then developed ticularly to the rapid processing of photographic in the customary silver halide developing agent. materials. If the emulsion is coated on a paper or other In Yackel U. S. application Ser. No 594,589, porous support, it is desirable to moisten the filed May 1.8, 1945, a rapid processing method is 5 surface of the emulsion with a sponge, a rubber described which involves the use of stabilizing roll or other applicator wet with developingsoluagents such as potassium thiocyanate, sodium tion so that the paper sup-port is not soaked with sulfate; thiourea, etc. The photographic prints the developing solution, are developed in' the usual way and are then After development has taken place, the excess treated with a' solution of the potassium thiodeveloping e t e r a e of t e print is cyanate or other stabilizing agent after which removed by any Convenient means Such as a they" are dried without washing. This produces Squeegee d t print is treatediwiththe thioa stable photographic print and materially rep l stabilizing 80111111011- The P11113058 0 duces the time necessary for processing the exstabilizing agent is o make e p d posed emulsion. ver halide remaining in the print substantially I have now found that exposed and develo d incapable of further photosensitivity. The silver photographic emulsions may be stabilized by compound p c y the stabilizing agent treating them with a solution of a thiophenol should be light-colored or transparent so that it such as thiophenol itself or a substituted thiodoes not f re with the View or p n of phenol. The thiophenol ma be one which conthe final image.v Solutions containing thiotain-s one or more benzene nuclei and may be hydroqilinone produce a ht yellow Silver salt substituted with groups such as -C00-H, NH while thiosalicylic acid produces a colorless sil- OH, -SH, 3031-1, -CSNH2, -SO2NH2. The vefsaltfollowing, compounds may, for example, b d Stabilization of a photographic print accordaccording to my invention. ing to my process consists in exposing a photo- SH SH graphic paper to a negative followed by, develop- I i ment in the following solution diluted 1 part of' COOH developer to two parts of water.

i Grams 3U Monomethyl-p-amino'phenol sulfate 3.1

Sodium sulfite (desiccated) 45 Thiosalicylic acid on g g g 0 mm c r ona e esicca e Thmhydmqumm Potassium bromide 1.9

Water to 1 liter.

After development for from 5 to 60 seconds,

for 5 seconds and bathed for 15 seconds to 15 minutes in the stabilizing solution, Prints treated in o-Aminothioplienol iii-Amino thiophenol this way were stable to sunlight, heat and hu- SH SH SH midity without printing-out or fading. The foll lowing examples illustrate stabilizing solutions sQ H which may be used.

Example 1 Thiosalicylic acid grams- 30 i NHCOOH3 Ammonium citrate do 60 2-WIercapto-5mitro p-Acetaininoo-Hydroxy thio- Ammonlm hydroxide 60 benzene sulfonamirle thioplienol phenol Water liter 1 $97K? SH 00 Example 2 Thiohydroquinone "grams" 10 Alcohol ml 250 Acetic acid ml 20 I Water liter 1 11 soiH Example 3 p-Mercapto thiobenzaimde p-Mercapto benzenesulfonate Ortho amino thiophenol "grams" 10 According to my invention a silver halide emul- Acetic acid ml 20 sion preferably a gelatino silver halide emulsion Water liter 1 the print is treated in an acetic acid stop bath 7 Example 4 Meta amino thiophenol grams' 10 Acetic acid ml 20 Water liter 1 The stabilizing solutions may contain one or more of the thiophenol stabilizing agents as Well as various buffer salts and solvents to help solubilizing the various compounds. Hardening agents such as Formalin, glyoxal, zirconium salts, potassium alum, chrome alum, ammonium molybdate, etc., may also be incorporated in the solutions. Auric chloride or other chloride of a metal below silver and above osmium in the electromotive series may be added to the stabilizing bath as described-in Brice application Ser. No. 624,570, filed October 25, 1945, now Pat. No. 2,448,857, September 7, 1948, I

It will be apparent that my invention may be used either with positive emulsions such as are used on photographic papers or on negative film emulsions. It is generally necessary to use hardened emulsions according to my invention. Positive emulsions such as those employed on photographic papers are generally hardened and no further hardening treatment is required. However, in the case of certain negative film emulsions, the emulsion must be hardened before or during stabilizing according to my invention.

Although the emulsion may be immersed in l the developing and stabilizing solutions, I prefer merely to moisten the surface of the emulsion with these solutions except in the case of films. Thus in the case of paper supports, the support does not become wet and the drying time is then greatly reduced.

It will be apparent from the foregoing descrip tion of my invention that all or a major part of the silver remains'in the emulsion after stabilizing treatment. This differs from the customary fixing and washing in which the intent is to remove the residual silver halide from the emulsion.

I claim: 1. A rapid process for the formation of an image in a hardened silver halide photographic layer which comprises exposing said layer, developing it-with a silver halide developing agent to form a silver image and immediately thereafter stabilizing it by treatment with a solution of a thiophenol only until the silver halide has been sub-.

stantially completely converted to a complex with said thiophenol, leaving said complex in said layer and drying said stabilized image Without any further treatment.

2. A rapid process for the formation of an image in a hardened silverhalide photographic layer which comprises exposing said layer, developing it with a silver halide developing agent to form a silver image and immediately thereafter stabilizing it by treatment with a solution of thiosalicylic acid only until the silver halide has been substantially'completely converted to a complex with thiosalicylic acid, leaving said complex in said layer and drying said stabilized image without any further treatment.

3. A rapid process for the formation of an image in a hardened silver halide photographic layer which comprises exposing said layer, developing it with a silver halide developing agent to form a silver image and immediately thereafter stabilizing it by treatment with a solution of thiohydroquinone only until the silver halide has been substantially completely converted to a complex with thiohydroquinone, leaving said complex in said layer and drying said stabilized image without any further treatment.

4. A rapid process for the formation of an image in a hardened silver halide photographic layer which comprises exposing said layer, de-. veloping it with a silver halide developing agent to form a silver image, and immediately thereafter stabilizing it by treatment with a thiophenol in the presence of a silver salt of a metal below silver'and above osmium inthe electromotive series and drying said stabilizedimage without any further treatment.

5. A rapid process for the formation of a image in a hardened silver halide photographic layer which comprises exposing said layer, de-

- veloping it with a silver halide developing agent to form a silver image and immediately thereafter stabilizing it by treatment with a thiophenol in the presence of auric chloride'and drying said stabilized image without any further treatment.

HAROLD D.'RUSSELL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,356,236 Sulzberger Oct. 19, 1920 1,361,352 Sulzb'erger Dec. 7, 1920 2,377,375 Russell June 5, 1945 OTHER REFERENCES Kraft, Uber das Photochemische usw, Zeitschrift fur Wissenschaftliche Photographic usw., band 31, May 1933, pages 329 to 364, pages 342, 343, 345, 349 and 350 cited.