US2201591A - Photographic processing - Google Patents

Description

`May 21, 1940. G. G. MORENO 2,201,591

v PHoToGRAPHIc PROCESSINGv Filed May 11, 1939 GAE/wa 6fm-cm /VaRf/vo /N VEA/TOR A TT ORNE Y Patente'clr'May 2.1, 1940 PHOTOGRAPHIC PROCESSING Gabriel Garcia Moreno, Mixcoac, D. F., Mexico, assigner .to CMC Corporation, New York, N. Y., a corporation of Delaware ,y

`Application May 11, 1939, Serial o. 273,023

The present invention relates to an improved method of photography whereby pictures of better quality and greater range-of density variations may be obtained. It also relates to a method of processing any and all types of emulsions subsequent to exposure and priorA to development whereby the latitude. of the emulsion is greatly enhanced, its inertia very materially reduced, and the developability of the latent image very materially increased, so that in effect the sensitivity of the emulsion is increased to say 400% or '700% of its original value.

Moreover, the invention relates to means and reagents particularly adapted for use in such treatment, these reagents being hereinafter referred to as activating compounds. Although the present invention is applicable for use in all forms of photography, it appears to be particularly well adapted for use in motion picture work since the processing may be carried out rapidly and for this reason may be coordinated with the usual continuous developing processes used in motion picture'lm laboratories. Moreover, .the use of the process gives rise to very material savings in time and money when used in motion picture work.

In motion picture photography, very intense illumination is employed, necessitating numerous 'electricians and sources of illumination and therebyvincreasing the cost and rendering working conditions on the set or scene disagreeable. The

present invention permits the use of from one'- fourth to one-seventh of the light intensity ordinarily employed and in some instances good results are obtained with materially smaller intensities of light. The methods and means of this invention are therefore of considerable value in monochromatic and in color motion picture photography.

There are other instances where available light intensity is not suflicient for the production of good pictures by the ordinary methods. For example, in the background projection method (Where a background picture is projected upon a screen andr such projected image is then photographed in conjunction with actors) difficulties have been heretofore encountered. Newspaper photographers often desire to obtain photographs at night or in improperly illuminated areas. By

means of the reagents hereafter described, any photographic emulsion carrying a latent image is capable of being treated so as to produce a good visible image even though the ordinary methods of development would notproduce a good visible image. i

An object of the present invention, therefore, is to provide a reagent containing activating materials and compounds, such reagent being adapted for use in the treatment of photographic emulsions containing latent images whereby the latent image is rendered developable to such an extent that whereas ordinarily no image would be obtained, a fully graded, well dei-ined and detailed image is now obtained in accordance r'ing amino hydroxyl compounds derived frombenzene or naphthalene and having a substituting radical in the meta position or 1,3- relation to the amino or hydroxyl group. The action of these activating compounds is not well understood but such compounds tend to actas normal developers. Many developers are benzene ring compounds but developers are distinguishable fromthe activating compounds of this invention ,in that developers contain substituents in the paraposition and are capable of distinguishing lbetween exposed and unexposed grains in an emulsion. Moreover, normal developers do .not render visible latent-images of the character which are rendered developable by the activating substances disclosed herein. Y

An object of the invention is to provide a method and means for treating photographic emulsions whereby better quality, greater range in tonal values and greater latitude are obtained.

Another object is to provide a method of treating photographic lm whereby underexposed emulsions may be developed to form images having the required degree of contrast and definition. y Another object is to provide means for and methods of treating exposed lms to increase their latitude and ability to reproducibly/record a wider range of density gradations.

Still another object is to provide means for and methods of treating previously exposed photographic film whereby latent images which are f not responsiveto usual development are now made developable.

Other objects,v advantages, uses and adaptations will become apparent to those skilled in the artfrom the following description.

As previously stated, the primary reagent to be employed in the performance of the inventions herein is an aqueous, alkaline solution containing an activating agent, such activating agent being any meta-substituted amino derivative of benzene or any benzene ring amino hydroxyl compound derived from benzene or naphthalene and-having a substituting radical in the meta position or'1,3 relation to the amino or hydroxyl group. A large number of activating agentshave been found satisfactory, `among them meta-dihydroxy-benzene, meta-phenyle'ne-diamine, meta-nitraniline, meta-toluidine, metatoluene-diamine (2,4- diamine toluene), metacresol, meta-amino-phenol, 2,4- diamine-phenol- ,dihydrochlorida 2,4- diamino-anisole-dihydrochloride, etc. A fElachfofthe substances mentioned and embraced by the general group is capable ofv y group mentioned. Such solution'may also nontain a dispersing or SOIubiIiZIng aid; forexample,

when a difilcultly soluble activating compound/is' being employed, alcohol acetone or other watermiscible solvent may be used` inA the solution for the purpose of dispersing andv solubilizingthe activating compound.

The treating and activating solution should be4 alkaline and its alkalinity may be equivalent to that obtained by the use of `about 0.3% to 1.0% of sodium hydroxide by weight. Small amounts of sodium hydroxide may therefore be present in the solution, although other alkali or alkaline salts and substancesV may bepresent such as, for example, any of the .salts'oi strong bases and weak acids suchas bo'r'ax, sodium phosphate, sodium citrate and the like. VMoreover, the solution may contain an antioxidant or stabilizing material such as sodium' sulilte.'l

'I'he concentration of the activating agents in the treating bath may be varied appreciably and the presence or absence of numerous ingredients will depend somewhat upon the conditions encountered and the manner in which the treating bath is to be employed. The following illustrative examples are typical:

Acetone 25 cc. 1.1% Meta-cresci 15 cc. 0.7% Meta-toluene-diamine 10 gr. 0.5% Meta-nitraniline. 1.25 gr. 0.06% Meta-resorcinol 10 gr. 0.5% Sodium sulite 50 gr. 2.2% Potassium meta-bisuliite....-- 50 gr. 2.2% Water 1 litre 92.7%

It is to be understood that the above represents a treating solution of approximately the concentration used in treating the exposedlm. Weaker solutions have been found very eifective, as for example, those obtained by diluting the bath with another litre of water. Moreover, the

solutions may be prepared in more concentrated l t0 90 F. mailv be used. .Furthermore, the time form and then diluted shortly prior to use.

A solution of the specic characterl given hereinabove may be used with advantage by adding the same to a litre of water containing approximately 7 grams of sodium hydroxide,` 90 grams of sodium sulte and averytsmall quantity, say 1/2 gram, of potassium bromide.'

Another typical treating solution may comprise the following:

Meta-dihydroxy-benzene 1 gram Meta-toluidine 0.75 gr. Meta-phenylene-diamine 0.25 gr. Meta-nitraniline 0.25 gr. Acetone- 5 cc.

Sodium phosphate 15 gr.

Water 1000 cc.

A 4:amuser activating agent', and nally render the solution alkaline by the `addition of sodium phosphate, borax or the like.l

The etect. ot a treatment' of exposed but un- .d'eveio'pedlmm with a treating solution having the above. composition is graphically shown on the appended drawing.' The ordinates represent densities whereas the abscissa represent exposure or light intensity. The abscissa numbered from 1 to 20 are indications of exposure corresponding to those used on the sensitometric strips made `on the machines approved and used `by Eastman Kodak Company. Curve Il shown on the appended drawing represents the charv acteristics of a standard `Eastman Super X iilm whereas curve Il depicts the lcharacteristics of the same type of film which has been treated, after exposure and prior to development, with thb activatingv agent solution described hereina ve.

Attention is particularly called to the fact that the length of the straight line portion of lcurve I l is appreciably greater than the straight in the treatment of iilm may involve several modiiicationsf In one method, exposed photographic emulsion containing a latent image is subjected 'to'` the action of the activating agent solution, washed and then subjected to the action of a Adeveloping bath. 'I'he activating solution in instances does not contain any-developers.' l*.llhe or emulsion, after being vtreated with the activating reagents and washed.

may be driedbefore it is subjected to the action pi' the developer, although drying is not essential. The-graphical illustration appended hereto inustrates lthis method of treatment. when this method is carried out, it will be found that the temperature at which the treating solution is applied does not materially anect the results and therefore temperatures from.' say about 50 F.

of treatment orth'e time during which the activating solution is permitted to act on the film.

may Varyvwithin wide limits. Ordinarily, times entirely satisiactormi' times may be used,`

X-ray emulsions' andextremely sensitive emulsions such as those employed by pressphotographers, are Ivery'efi'ectively treated by adding a solution of activating agents of the character described hereinabove directly to a developing bath of any suitable type. 'I'he exposed illm carrying an emulsion bearing a latent image can then be developed in the solution of the actigrating agents and developers' and under these conditions the activating agents appear to act although even` -shorter upon the latent image immediately prior to the development of the images with the production of negatives, or positives as the oase mayl be,

which show greater detail and less fog than is obtained by the use of the developer alone or by .the sequential use of activating agents and developer.' Ordinarily. from about 0.3 volume to 25 etc.

2.0 volumes of an activating solution of the character mentioned hereinbefore may be added to 1 volume of any commercial developing solution with very good results.

r It will be -found that usually the timle necessary for development in the subsequent step can be materially reduced from that normally employed with the developer, assuming temperature and concentration conditions of the developing solution to beconstant.

In addition to simple meta-substituted amino derivatives, the present invention contemplates the use of the secondary substitution products, such as meta-substituted diaminoor hydroxyg r amino benzene derivatives, one or more amino groups of which may carry methyl or other alkyl groups as substituents on the nitrogen, the amino or hydroxyl groups of such compounds being in a 1,3- relationship to each other. Examples of 2o such secondary substitution products which can be used successfully are: mono-methyl-metaphenylene-diamineedihydrochloride; 2,4- diamino-anisole-dihydrochloride; meta-methylaminophenol; dimethyl-metaphenylene-diamine; Since different photographic emulsions often exhibit minordifferences in their reaction to the activating solutions and to diierent developers, the operator may wish to try a number Iof activating agentsifrom the groups referred 30 to before selecting those which produce results mfost agreeable to his taste.

This application is a continuation-impart of Serial No'. 140,626, filed May 4, 1937. I claim: 35

graphic emulsions containing a latent image, the steps of subjecting a photographic emulsion after exposure and prior to development to the action of an aqueous alkaline medium containing from do about 0.2 to 4.0 grams of an activating agent from the group consisting of meta-phenylene-diamine, meta-nitraniline and meta-toluidine, per 1000 cc. of said medium, for a period of from 2 to 10 minutes and in the absence of a developer,

4.', then washing and drying the lm, and then developing the lm in a developer for a shorter' time than that normally employed for such de veloper. .1

2. in a process of treating photographic emul- 1. In a process of treating lexposed photo? sionscontaining a latent image, the steps of: subjecting a photographic film after exposure and prior to development to the action of anv alkaline aqueous medium free from developers and containing an activating agent from the.

consisting of` meta substituted amino derivatives of benzene, having a substituting radical in the meta position to the amino group, derivatives of l-aminonaphthalene having a substitution radical in the 3 position, and derivatives of .2- aminonaphthalene having a substitution radical in the 4 position, said solution having an alkalinity equivalent to between about 0.3% and 1.0%

sodium hydroxide by weight.

5. A solution for use in the treatment of photographic silver halide gelatin emulsions containing latent'.v images, comprising: an aqueous alkaline solution containing from about 0.15% to 2.5% of an` activating agent comprising a meta substituted amino derivative of benzene, having a 'substitutingeradical in the meta. position to the amino group, said solution having an alkalinity equivalent to between about 0.3%' and 1.0%

sodium hydroxide by weight.

6. A process oi' treating underexposed silver halide gelatin negatives containing'latent images to properly develop the same, comprising: sub.

jecti'ng an underexposed photographic emulsion containing a latent image to the action of an aqueous alkaline medium containing from about 0.15% to 2.5% by weight of a meta substituted amino derivative of benzene having a substituting radical in the meta position to the amino group.

GABRIEL GARIIA MORENO.

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