US1956017A

US1956017A - Method of indirectly producing color photographs

Info

Publication number: US1956017A
Application number: US514706A
Authority: US
Inventors: Bela Gaspar
Original assignee: Individual
Current assignee: Individual
Priority date: 1930-03-01
Filing date: 1931-02-09
Publication date: 1934-04-24
Anticipated expiration: 1951-04-24
Also published as: BE377456A; FR712472A; GB379679A; DE528318C

Description

Patented Apr. 24, 1934 UNITED STATES METHOD OF INDIRECTLY PRODUCING.

COLOR PHOTOGRAPHS Bela Gaspar, I Berlin, Germany No Drawing. Application February 9, 1931,

Serial 1930 22 Claims.

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

It has already been proprosed ,for the indirect production of color photographs to add leuco-bases to a silver salt emulsion, 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 of the color) for every point of the sensitized layer.

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 of being stored for any length of time in their unexposed state, this also applying to the finished picture, as the resulting colors very easily diffuse and the colors which it has been proposed to employ are extremely unlasting, i. e. not fast.

According now to the invention, there are em-' ployed 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 of operations, and for this reason these will be primarily referred to in the followmg.

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 oxidizing, condensing, reducing or saponifying action, in accordance with the chemical nature of the color-form- 40 ing 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 thedirect method effected by light. In this case the leuco-substances take the part ofthe sensitized. substance, which part, inthe present invention, is assigned to the silver salt (orinore'generally speak to the semi -Jtized 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 areaction under thaefiect of light.

In Germany March 1,

To more clearly explain the invention, various examples are quoted in the followingf- In order, for example, to produce a blue pic- REISSU ED JUN 23 1940' ture diacetyl indigo white is incorporated in the silver emulsion and the sensitized layer is exposed, developed and fixed'in the customary v 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 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 orsulphuric acid solution, whereupon the leuco-substance is converted into the desired color. The superfluous leadsalt is thereupon removed, and the leucosubstance which has not been acted upon (at the unexposed or less exposed parts) treatedwith the known means (fixing salts and acetone).

The conversion of the leuco-substance 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., iiidol 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 oxidation and condensation. If dia'cetylindigotine is employed as color-forming substance, and the silver image is converted into a ferrous iron salt image, indigo is formed by reduction.

may be made to the cinchonic salt of the sul- 9 phuric acid ester from the leuco-compound 616' 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 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-compoundof the dyes may also be employed, for example, ethyl ether of the hydrofiavanthrene.

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

The silver image is converted in the known manner into vanadyl-ferrocyanide, which acts as 5 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 if the developed silver image is treated in a solution of certain oxidizing agents, for example potassium chlorochromate (or potassium bicliromate 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 follows:--.1 g.-

potassium bichromate, .1 g. sodium chlorate, 1 cubic centimetre 20% sulphuric acid and 50 cu. ems. 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, for example gelatine, collodion or cellulose ester.

The sulphate esters of the leuco compounds of vat dyestufis have the property of impregnating the gelatine (for example the sodium salt of sulphate ester'from the leucoeco'rnpound 'oi' hexabrom-indigo) so that the same cannot be re moved by washing, andmay' thereforeals'o be incorporated in the'gelatinewithout 'a fixing.

agent. The fixing is even better if 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 substancafor example sodium carbonate, responding to alkali. By utilizi g the said prop-, erty 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 different 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 weaklyexposed 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 wellknown ferricyanide 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 aso be produced by super-imposing two or more layers, i. e. applying the layers one above the other, whichare each tuned to a certain character of light (wave-length limits) and t have the corresponding leuco-substance incorporated 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 of corresponding sensibilizers and filter colors. Two different emulsions may be applied to the front and rear side of a film respectively. Alternatively, two

or more different 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 leucocompounds into the particular color, are also adapted for fixing colors or for tanning the gelatine, etc.v For example, the lead chromate ac- 130 cording to the first example described in the above is converted into lead sulphate, whereby an oxidizi'ng process is caused by reason of the chromic, acid released, and thlead sulphate is coloured with a basic dye, for example fuchsin. This par- 135.

ticular 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 of the invention.

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

l. A method of producing colored photographic images, consisting in adding to a durable leuco compound in the preliminary stages of vat dyestuffs, from which the dyestuffs are derived; a sensitized metallic salt emulsion, performing exdesired colo *7; A method of producing color photographic 9 images, cgnsisting massing a durable leuco corn-;-

pound to a sensitize .m tallicsalt emulsion, per-" posure, developing and fixing in the customary manner, and then introducing the exposed, developed and fixed image into a bath acting on the said compound and locally converting the said compound into the colorat the desired points.

2. A method of producing colored photographic images, consisting in adding esters of leuco compounds to a sensitized metallic salt emulsion, performing exposure, developing and fixing in the customary manner, and then introducing the ex posed, developed and fixed image into a bath acting on the said compound and locally converting the said compound into the color at the de sired points.

3. A method of producing colored photographic images, consisting in adding ester salts of leuco compounds 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 acting on the said compound and locally converting the said compound into the color at the desired points.

4. A method of producing colored photographic images, consisting in adding ethers of leuco compounds 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 acting on the said compound and locally converting the said compound into the color at the desired points.

5. A method of producing colored photographic images, consisting in adding to a durable leuco compound in thepreliminary stages of vat dyestuffs, from which the dyestuffs are derived; a sensitized metallic salt emulsion, performing ex posure, developing and fixing in the customary manner, and then introducing the exposed, developed and fixed image into a bath and converting the said image into a compound acting on the said leuco compound, thereby producing the color at the desired points by interaction with the said leuco compound.

6. A method of producing colored photographic images, consisting in adding a durable leuco compound to a sensitized metallic salt emulsion, performing exposure, developing and fixing in the customary manner, and then introducing the image into a bath and converting the exposed, developed and fixed metallic salt into a compound rich in oxygen, and liberating oxidizing agents at subsequent treatment, thereby producing the y' 'oiiidation of the said leuco comforming exposure, developing and fixing in the customary manner, and then introducing theexposed, 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 colored photographic images, consisting in adding a durable leuco compound to a sensitized metallic salt emulsion, performing exposure, developing and fixing in the customary manner, introducing the exposed, developedand fixed image into a bath, converting the metal deposit into a condensing agent, and then introducing the said image into a second bath thereby producing the desired color by condensation.

duigtionof the sensitizedemulsionand prior to 9. A method of producing colored photographic images, consisting in adding a durable leuco compound 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, 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, consisting in adding a durable leuco compound 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, consisting in adding a durable leuco compound 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, consisting in 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, consisting in 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, consisting in 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, consisting in adding the said leuco compound after produc tion of the sensitized emulsion and following development by impregnation.

16. A method of producing colored photographic images, according to claim 1, consisting infadding the said leuco compound after provjelopment by impression. f

-17 A. method of producinglcolored. photo- 'raphic images, "according 'to c'laiml, consisting .jir'iadding the said leuco compound after produc; "tion of the sensitized emulsionand'fol1owing"iie -ve1'opmentby impression.

I18. A method of producing colored "photographic images, according to claim 1, consisting inadding the said leuco compound after produc- .tion'of the sensitized emulsion and pricrto development by application thereof in the form of a coating.

19. A method of producing colored photographic images, according to claim 1, consisting in adding the said leuco compound after produc tion of the sensitized emulsion and following development by application thereof in the form of a coating.

20. A method of producing colored photographic images, consisting in adding a durable leuco compound to a metallic salt emulsion, per- 150 },.which are free of metallic deposit, and finally treating with a solution or a powerful oxidizm' g agen 22. A method of producing. multi-colored photographic images, consisting in adding to a durable leuco compound in the preliminary stages of 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 acting on the said compound and locally converting the said compound into the desired color at the points which arefree of metallic deposit,

and finally treating with a solution of a powerful oxidizing agent.

BELA GASPAR.