USRE21513E - Method of and material fob indi - Google Patents

Description

Reissued July 23, 1940 UNITED STATES PATENT OFFICE METHOD OF AND MATERIAL FOR INDI- BECTLY GRAPES PBODUCIN G COLOR. PHOTO- Bla Gaspar, Brussels. Belgium 27 Claims.

This invention relates to a metnod for the indirect production of color photographs.

It has already been proposed for the indirect production of color photographs to add leuco-bases to a silver salt ulsion, and to convert these into the particular color as a result of the interaction between the silver reduced upon the development and the leuco-bases,

whereby the locally deposited quantity of silver in the developed picture determines the degree of color formation (including therefore the intensity oi the color) for every point of the sensitized layer.

1 This method, however, has not been successful in view of the fact that the leuco-bases are very inconsistent, while the plates or papers are not capable 01' being stored for any length of time in their unexposed state, this aisoapplying to the finished picture, as the resulting colors very easily difiuse and the colors which it has been proposed to employ are extremely unlasting, i. e., not fast.

According now to the invention, there are employed in place of the leuco bases the esters, ester salts or ethers of the leuco-compounds, or other equivalent colorless substances from which the dyes are derived.

In the process according to the invention silver salt emulsions will, generally speaking, also form the basis ofroperations, and for this reason these will be primarlly referred to in the following.

For the purpose of converting the ester, etc., into the corresponding colors, the silver deposit of the developed picture is first converted into a compound which will act on the ester, etc. This compound may have an oiddizing, condensing, reducing or saponiiying action, in accordance with the chemical nature of the color-forming substance employed.

According to a more recent invention, it is proposed with the assistance of esters or ester salts of the leuco-compounds to produce colorforming substances by the direct method effected 4 by light. In this case the leuco-substances take the part of the sensitized substance, which part, in the present invention, is assigned to the silver salt (or more generally speaking, to the sensitized metallic salt). The new method with its subsequent conversion of the image, consisting of a metallic deposit, into a color image accordingly represents in face of the said direct method an indirect process. The invention covers a reaction in the dark and the known direct method a reaction under the eiiect of light.

In Germany March 1, 1930 To more clearly explain the invention, various examples are quoted in the following:-

In order, for example, to produce a blue picture diacetyl indigo white is' incorporated in the silver emulsion and the sensitized layer is exposed, developed and fixed in the customary fashion. The leuco-substance in question, is not sensitive to the ordinary photographic baths employed, which condition, of course, requires to be observed not only in connection with the 10 present example, but also in all other cases. The silver image produced is converted in the known manner into one consisting of an oxidizing compound, preferably into a lead chromate image. This is immersed in an acid solution, for example, a weak muriatic acid or sulphuric acid solution, whereupon the leuco-substance is converted into the desired color. The superfluous lead salt is thereupon removed, and the leucosubstance which has not been acted upon (at the unexposed or less exposed parts) treated with the known means (fixing salts and acetone).

The conversion 0! the leucosubstance into the dye represents in the example above described an oxidizing and at the same time also a saponifying process. If as an equivalent color-forming substance there is employed indoxyl sulphate of potassium or other salts of indoxyl sulphuric acid or analogous compounds, for example thionaphthenic acid, etc., indol or indol-carbonic acid and the lead chromate image is immersed in a hydroiodic acid solution, and thereupon in an alkaline solution, indigo is again formed by Olddation and condensation. If diacetylindigotine is employed as color-forming substance, and the silver image is converted into a ferrous iron salt image, indigo is formed by reduction.

As an example of the use of an insoluble ester salt and the formation of a red color, reference may be made to the cinchonic salt of the sulphuric acid ester from the leuco-compound 6.6 dibrom-dimethyl-bis-thionaphthene-indigo. The silver developed from a layer containing this substance is converted in the known manner into peroxide of manganese, and the layer thereupon 45 treated in an acid solution, the red color forming thioindigo rose. In similar manner it is also possible to employ the esters'of other dyes, for example, helindon yellow, tetrabromide indigo, etc. Ethers of the leuco-compound of the dyes may also be employed, for example, ethyl ether of the hydroiiavanthrene.

An additional example of conversion of the ester salts into the particular color at the points which have been subjected o exposure, or at certain points 01 the silver image resides in the following:-

The silver image is converted in the known manner into vanadyl-ierrocyanide, which acts as oxygen carrier, or catalyst respectively, and is subsequently converted into the particular color in a weak sulphate solution of potassium bromate or sodium chlorate. If desired, the conversion of the silver image into a color image may be performed with one single solution it the developed silver image is treated in a solution of certain oxidizing agents, for example potassium chlorochromate (or potassium bichromate muriatic acid) or in a diluted potassium bromate solution, which is weakly acidified and contains a small amount of iodine potassium. Suitable leuco-substances are, for example, sulphate esters from the leuco-compounds of 6.6 dibrom-dimethyl-bis-thionaphthene indigo and hexabrom-indigo. The use of these baths, or the conversion into the particular color respectively, may also be performed after the development and prior to the fixing.

The leuco-substances may also be converted into the particular colors at the points which have not been exposed, i. e. at the points which are free from metallic or silver deposit, by taking a diluted potassium bichromate solution which has been weakly acidified with sulphuric acid, dissolving the silver image at first formed, and thus again developing the remaining halogen silver and converting the silver image thus formed into the particular colour. However, it is also possible to convert a silver image containing a leucosubstance into an inverse image in direct fashion. In this connection a suitable leuco-substance will be found to exist, for example in sulphate ester of the leuco-compound of tetrabrom-indigo. This is treated in a solution as iol1ows:'.l g. potassium bichromate, .1 g. sodium chlorate, 1 cubic centimetre 20% sulphuric acid and 50 cu. cms. water.

An additional possibility resides in the use of water-soluble leuco-compounds, for example sodium salts of sulphuric acid esters from the leuco-compounds of indigoidal dyes. These are subsequently deposited in the layer in the form of insoluble cinchonine salts, or mixed with carrier colloids of that kind which greatly adsorb the salts, !or example gelatine, collodion or cellulose ester.

The sulphate esters of the leuco compounds of vat dyestufl's have the property 01 impregnating the gelatine (for example the sodium salt of sulphate ester from the leuco-compound oi hexabrom-indigo) so that the same cannot be removed by washing and may therefore also be incorporated in the gelatlne without a fixing agent. The fixing is even better it at the same time there is added an organic acid, for example tartaric acid, or a tanning agent, such as chromium alum. The developer should be neutral as far as possible or responsive to a weak acid. In the present case the fixing agent requires to contain a substance, for example sodium carbonate, responding to alkali. By utilizing the said property of the sulphate ester the latter may be introduced into the layer prior to or following exposure and development, the layer being immersed in a solution of this ester or ester salts, or the substance applied to or pressed into the same. In the latter case, it is also possible to apply several difierent colors, for example in the manner of a screen, if necessary, mixed with filter colors and sensibilizers. The conversion to the particular color occurs in the same manner as described above.

Water-soluble leuco-substances may also be fixed at the exposed points of the image by tanning, whereupon the soluble leuco-substance at the unexposed or weakly exposed points is removed, for example by acetone, and thereafter the leuco-compounds, which have been fixed by the tanning process, converted into the particular color by a sodium nitrite solution. The welllmown ierricyanide bichromate bath or also a tanning developer may be employed for the tanning process.

The method in question is not confined merely to silver salt emulsions. It is, for example. quite possible to produce a picture composed of manganese or iron salts, in which case, of course, conversion of the metallic deposit into a compound capable of undergoing reaction is unnecessary.

According to the invention two or more color pictures may also be produced by super-imposing two or more layers, 1. e. applying the layers one above the other, which are each tuned to a certain character of light (wave-length limits) and have the corresponding leuco-substance incor porated therein. In addition to leuco-substances resulting in brilliant colors it is also possible to add to the emulsions leuco-substances providing a black or similar color on the lines of four-colour print. Use will naturally-be made 0! corresponding sensibilizers and filter colors. Two difierent emulsions may be applied to the front and rear side of a film respectively. Alternatively, two or more difi'erent emulsions may be combined by re-emulsion". According to this process at first complementary color negatives, or negatives containing the correct colors but permutated black and white, are produced, which may be copied on to a similar material, for example from film on to film, or plate on to film, or plate and film on to paper. It is, however, also possible to make copies on copying material prepared according to this process from any desired source, such as color diapositive, color screen plate, color tracing, etc.

The process according to the invention also permits of combination with the known photographic coloring processes, more particularly in those cases in which the silver compound is converted into those chemical substances which, in addition to the purpose of converting the leucooompounds into the particular color, are also adapted for fixing colors or for tanning the gelatlne, etc. For example, the lead chromate according to the first example described in the above is converted into lead sulphate, whereby an oxidizing process is caused by reason of the chromlc acid released, and the lead sulphate is coloured with a basic dye, for example fuchsin. This particular method will be found to offer advantages for subsequent correction of the coloring.

It will be understood that no restriction is made to the specific examples above referred to and that various modifications are quite possible within the meaning of the description and the annexed claims' without departing from the spirit oi the invention.

What I claim as new and desire to secure by Letters Patent is:

1. A method of producing colored photographic images which comprises adding a durable leuco compound of vat dyestufls to a light-sensitive metallic salt emulsion layer, exposing the layer, developing the latent silver image and fixing in the customary manner and then treating the layer with an oxidizing agent.

2. A method of producing colored photographic images which comprises adding esters of leuco compounds of vat dyestufis. to a sensitized metallic salt emulsion, performing exposure, developing and fixing in the customary manner, and then treating the exposed, developed and fixed image withan agent acting on the said compound and converting the said compound into the color at the desired points.

3. The method of producing colored photographic images which comprises adding ester salts of leuco compounds of vat dyestufi's to a sensitized metallic salt emulsion, performing exposure, developing and fixing in the customary manner and then treating the exposed, developed and fixed image with an agent acting on'the said compound and converting the said compound into the color at the desired points.

4. Amethod of producing colored photographic images which comprises adding ethers of leuco compounds of vat dyastufis to a sensitized metallic salt emulsion, performing exposure, developing and fixing in the customary manner and then treating the exposed, developed and fixed image with an agent acting on the said compound and converting the said compound into the color a.

images, which comprises adding a durable leuco compound of vat dyestuiis to a sensitized metallic salt emulsion, performing exposure, developing and fixing in the customary manner, and then introducing the image into a bath and convertin the exposed, developed and fixed metallic salt into a compound rich in oxygen, and liberating oxidizing agents at subsequent treatment, thereby producing the desired color by oxidation of the said leuco compound.

7. A method of producing color photographic images, which comprises adding a durable leuco compound of vat dyestuifs to a sensitized metallic salt emulsion, performing exposure, developing and fixing in the customary manner, and then introducing the exposed, developed and fixed image into a bath rich in oxygen, thereby producing the desired color by interaction between the said compound, the metallic deposit and the said oxygeneous bath.

8. A method of producing color photographic images which comprises adding a stable vat dyestuil forming substance to a sensitized metallic salt emulsion, performing exposure, developing and fixing the image into a bath, converting the metallic deposit into a condensing agent, and then introducing the said image into a second bath thereby producing the desired color by condensation.

9. A method of producing color photographic images, which adding a stable vat dyestuii forming substance to a sensitised metallic salt emulsion, performing exposure, developing andfixingintbccmtomary-mannenintroduclng theexpoccd. andnxedimase a bath, converting the metal deposit into a reducing agent and then introducing the said image into a second bath thereby producing the desired color by reduction.

10. A method of producing colored photographic images which comprises adding a stable vat dyestuif forming substance to a sensitized metallic salt emulsion, performing exposure, developing and fixing in the customary manner, introducing the exposed, developed and fixed image into a bath, thereby converting the metal deposit into a catalyzing agent, and then introducing the said image into a second bath thereby producing the desired color by catalyzation.

11. A method of producing colored photographic images, which comprises adding a durable leuco compound of vat dyestufifs to a sensitized metallic salt emulsion, performing exposure, developing and fixing in the customary manner, introducing the exposed. developed and fixed image into a bath acting on the said compound and converting the said compound into the desired color and subjecting the picture after the color formation to a photographic toning process of the known kind.

12. A method of producing colored photographic images, according to claim 1, which comprises adding the said leuco compound after production of the sensitized emulsion and prior to development.

13. A method of producing colored photographic images, according to claim 1, which comprises adding the said leuco compound after production of the sensitized emulsion and following development.

14. A method of producing colored photographic images, according to claim 1, which comprises adding the said leuco compound after production of the sensitized emulsion and prior to development by impregnation.

15. A method of producing colored photographic images, according to claim 1, which comprises adding the said leuco compound after production of the sensitized emulsion and following development by impregnation.

16. A method of producing colored photographic images, according to claim 1, which comprises adding the said leuco compound after production ofthe sensitized emulsion and prior to development by impression.

17. A method of producing colored photographic images, according to claim 1, which comprises adding the said leuco compound after production of the sensitized emulsion and following development by im 18. A method of producing colored photographic images, according to claim 1, which comprises adding the said leuco compound after production of the sensitized emulsion and prior to development by application thereof in the form of a coating.

19. A method of producing colored photographic images, according to claim 1 which comprises adding the said leuco compound after production of the sensitised emulsion and following development by application thereof in the form of a coating.

20. A method of producing colored photographic which comprises adding a durable ieucocompoimdofvatdyestufl'stoametallic salt emulsion,- performing exposure, developing and fixing in'the manner, and then converting the said compound into the desired color in one single bath.

21. A method at producing colored photographic images which comprises adding a stable vat dyestufi forming substance to a light sensitive metallic salt emulsion layer, exposing the layer. developing the latent silver image and fixing in the customary manner, and then treating the layer by a vat dyastufl forming bath.

22. A photographic material for producing colored images, comprising a sensitized metallic sale emulsion and a durable leuco compound oi a vat dyestufi.

23. A photographic material for producing colored images comprising a sensitized metallic salt emulsion and an ester of a leuco compound of vat dyestuffs.

24. A photographic material for producing colored images comprising a sensitized metallic salt emulsion and a salt of an ester of a leuco compound of vat dyestuffs.

25. A photographic material for producing colored images comprising a sensitized metallic salt emulsion and an ether of a leuco compound 0! vat dystufls.

26. A photographic material for producing colored images comprising a sensitized metallic salt emulsion containing a substance of the class consisting of esters, wter-salts and ethers of a leuco compound of a vat dyestufl.

27. A photographic material for producing coiored images comprising a sensitized metallic salt emulsion and a water insoluble durable leuco compound of a vat dyestufi.

BELA oAsPAn.

CERTIFICATE OF CORRECTION Reissue No. 21,515. July 25, 1914.0.

BELA GASPAR.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, first column, line 52, claim 5, for vate read -vat-; page 1;, first column,

line 8, claim 22, for the word "sale" read --salt--; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 10th day of September, A. D. 1910.

Leslie Frazer (Seal) Acting Commissioner of Patents.