US2280300A - Light sensitive photographic coating and method of manufacturing the same - Google Patents

Description

Patented Apr. 21,1942

FICE

LIGHT- SENSITIVE PHOTOGRAPHIC COAT- ING AND METHOD OF MANUFACTURING THE SAIVIE Rowland 8. Potter, Brightford Heights, and Ray Seward Hagaman, Irondequoit, N. Y., assignors to Defender Photo Supply 00., Inc., Rochester. N. Y., a co poration of New York No Drawing.

This invention relates to a light sensitive photographic coating and method of manufacturing the same, and has for its purpose to afford a light sensitive coating having a variable steepness of gradation, or gamma, dependingupon the wave length or spectral region of the light to which the coating is exposed, so that any desired gradation can be had as the negative or character of the subject may require, by varying the color of the light, this application being Application January 14, 1941, Serial No. 374,368

18 Claims.

a continuation in part of application Serial No.

332,536, filed April 30, 1940, which application was a continuation in part of application Serial No. 300,236, filed October 19, 1939.

More particularly the invention has for its purpose to produce such a coating by utilizing an emulsion that is sensitive to light of a given wave length and characterized by a certain steepness of gradation, or gamma, when exposedto such light, and adding to said emulsion a sensitizing dye which not only gives sensitivity to light of a different spectral region than the region of natural sensitivity but when exposed to light of that region to which it has been made sensitive, it gives a characteristic gamma or contrast differing greatly-usually softer--from the gamma of the natural region, so that by varying the light between that to which the emulsion is' naturally sensitive and that to which the dye renders it sensitive, any gradation or contrast can be had.

Another object of the invention is to produce v gradation before dyeing, and accomplishing this by using a lesser quantity of the dye than would be required to confer maximum sensitivity within the spectral region affected by the dye, or by using a' larger amount of the dye and restricting its sensitizing action either by coating the emulsion on its support quickly after the dye is added, or by setting the emulsion rapidly and washing out a portion of the dye.

A further purpose of the invention is to afford a photographic light sensitive coating that can be manufactured economically, and which with normal developing and'fixing technique, is capable of producing. prints of widely varying contrast or steepness of gradation.

An emulsion can by this procedure be obtained that is'characterized .by a certain steepness of gradation, or gamma, when exposed to light of I a color within the spectral region to which the emulsion is naturally sensitive, and a markedly softer gradation or contrast, varying from as little as to 50% or more, when exposed to light within the spectral region to which the dye has made the emulsion sensitive. A paper. coated 1:1-diethyl, thiopseudocyanine iodide.

with such an emulsion possesses a wide variation in gradation that permits it to be used commercially in place of several different papers that have heretofore been required to give various degrees of gradation from soft to hard,

The invention may be carried out in different ways or by utilizing different dyes, and according to a preferred method, the selected dye is ,added to the emulsion in a restricted quantity,

substantially less than required to produce a maximum color sensitization.

As an example of this procedure, a coating can be produced from 'an emulsion which naturally gives a high contrast or steep gradation,

by adding to one liter of such finished emulsion after washing from '7 cc. to 11 cc. or approximately 9 cc. of a .05% solution in alcohol of The dye can be added either before or after washing-the emulsion, but preferably after. The amount of dye thus used is considerably less than would be addedto produce maximum sensitivity, and

as a result, the emulsion possesses a considerably softer gradation when exposed to light of a color within the spectral region to which the dye has made-the emulsion sensitive than when exposed to light of a color within the spectral region to which the emulsion is naturally sensitive. The amount of dye indicated above is substantially less than would be required to produce maximum color sensitivity, and after adding the dye, the emulsion may be coated on the support as usual.

Another method of carrying out the invention resides in using a larger quantity of dye and restricting the length of time of action on the emulsion. One method of accomplishing this consists. ;in introducing the dye into the emulsion before setting and washing, While maintaining the emulsion at a relatively low temperature, and limiting the time during'which the dye is permitted to remain in the emulsion before chil1- ing the latter.

For example, 300 cc. of a .05% solution of the dye may be added to 15 liters of emulsion at approximately 86 F. The emulsion is permitted to stand for about two minutes, or other suitably short period of time, and cooled as rapidly as possible to a temperature of F., or lower, in a conventional chill room or. setting tank; The usual shredding, washing, and remelting operations of the emulsion are then carried out, after which the emulsion can be digested at moderate temperatures or heated to comparatively high temperatures without risk of destroying its variable gradation characteristics, the more so because a considerable amount'of dye has been washed out. Following this, the paper or support is coated in the usual manner.

In the procedure outlined, where 300 cc. of a .05% solution of dye is added to 15 liters of emulsion, the emulsion preferably includes one part silver bromide to about three parts gelatin and fifteen parts water, although .the emulsion may be otherwise composed as long .as this approximate relation between the amount of dye and silver halide is maintained.

Any suitable dye which when used in restricted quantity will confer on the emulsion a markedly different gamma, or gradation steepness in the sensitized region, or which is slow acting so as to enable restricting the dye sensitization by limiting the time' of action on the emulsion, may be successfully used to accomplish the stated results.

Among other dyes that are suitable and can be successfully employed are the following:

(2 methyl-dihydrobenzthiazolylidene) -l 3'-ethylidenel -ethyl-oxindole) 2 :2-diethyl-7 :7 -o -phenylene-thiacarbocyaninep-toluene sulphonate;

2:3 diethyl 5:6 benzthia-l :4 -quinazocyanine iodide;

2 l-diethyl-3 4-benzoxa-pseudocyanine iodide;

' l 1'-diethyl-thia-pseudocyanine iodide;

1:1 diethyl 9:9 ethylene 2:2 carbocyanine bromide;

thiacarbocyanine-p-toluene sulphonate; 2 :2'-diethyl-5 6-5 6 -dibenz-7 :7'-ethylene-thiacarbocyanine-p-toluene sulphonate; 1:1'- diethyl-,3 3-3 :3 -tetramethylindocarbocyanine iodide; 2' diethyl -4 5 4 :5-tetramethyloxacarbocyanine iodide; 1' diethyl a. methyl seleno pseudo cyanine iodide; 2' diethyl 8 methyl thia-carbocyanine bromide; 2' -diethyl-8-methyl-4: 4'-dichlor thiacarbocyanine chloride;

(1 :3 3 :5 tetramethyl-indolylidene) -2 :4 ethylidene- 1 -phenyl-3 -methyl-pyrazole-5' -one) (1 :3:3: tri methyl indolylidene) 2:4 ethylidene- 1 -m-tolyl-3 -methyl-pyrazole-5' -one) (-1 :3:3 trimethyl-indolylidene) 2:4'-ethy1idene- (1 -phenyl-3-methyl-pyrazole-5' -one) (l 3:3 trimethyl indolylidene) 2:4-ethylidene- (1' p ethoxyphenyl 3' methyl-pyrazole 5- one (1 3 :3 :5 tetramethyl indolylidene) -2 4' -ethylidene- 1 -phenyl-3 -methyl-pyrazole -5 -one) 1:3:3 trimethyl indole 2:2 trimethine 6' methyl quinoline;

2:2 diethyl 5,-5 dimethyl oxacarbocyanine iodide; 2-:2 diethyl 5:5 dimethoxy oxacarbocyanine iodide.

Another method of carrying out the invention by restricting the sensitizing action of the dye consists in adding the dye to the finished washed emulsion when the latter is ready for coating, and coating the paper or other. support immediately. A dye such as described above, may be emulsions, rendered color sensitive by means of certain sensitizers such as erythrosin, carbo; cyanine, isocyanine type dyes, frequently varies according to the spectral region to which the emulsion is exposed, but the gradation conferred by such a dye is constant or of the same degree,

irrespective of the amount of dye used.

Thus while the gradation conferred by the dye in such instance is different from that of the 'regionand when exposed to the region of the natural emulsion sensitivity, is slight and definitely insuflicient for any practical purposes in obtaining the necessary effects that have heretofore required different papers of considerably varying contrast characteristics.

It is believed that the dyes disclosed herein have preferential action on some of the silver halide particlesapparently,'the larger particles being more rapidly and more completely sensitized than the smaller particles. Hence, if action of the dye is restricted either by time, or quantityavailable in the emulsion bulk, then the particles of silver halide distributed in the emulsion will be of varying color sensitivity. It is known that gradation is dependent on the relative sensitivity to light of the different halide particles; so if the silver halide particles are made widely variable in speed sensitivity, when exposed to light to which the dye confers sensitivity, then softer gradation will obviouslybe obtained in the sensitized spectral region. It is this characteristic of the emulsion" that confers-a widely variable gradation and makes possible the use of one paper to obtain the various results that previously required several papers. If the action of the dye is not restricted, then all the silver halide particles will eventually be equally color sensitized, thus giving similar gradations whether exposed to light of the natural sensitivity region or to light of the region of conferred spectral sensitivity.

With this method, the sensitizing action of the dye on the emulsion is less than if the dye were permitted to remain in the emulsion for a longer period before coating, and the sensitizing action of the dye is stopped by coating and drying the emulsion on the paper before maximum sensitization is reached, and at a point substantially less than such maximum.

With this procedure, the degree'of variation in the steepness of gradation, or gamma, of the paper, between the spectral region of the dye and the spectral region to which the emulsion is naturally sensitive, depends upon the shortness of time between adding the dye to the emulsion and coating the latter on the support, and best results are had by completing the coating operation within approximately five minutes after the dye is added to the emulsion, during which the emulsion is maintained at the usual coating temperature.

While-the invention has been described with reference to certain definite methods, it is not confined to the particular steps, proportions, or dyes herein disclosed, and this application is intended to cover such other dyes or methods as may come within the purposes of the improvement or the scope of the following claims.

6. The method of manufacturing a light sen- We claim:

1. The method'of manufacturing a light sen sitive photographic coating having a widely variable gamma depending upon the spectral region of the color of the light to which it is exposed, which consists in distributing throughout 9. molten emulsion a sensitizing dye in a consider-.

ably less quantity than required to produce maximum sensitivity, said'dye acting on the silver halide particles and possessing the characteristic of conferring a gradation which varies in the sensitized region with the amount of dye used and acting to impart to the emulsion a substantially softer gradation when exposed to light within the spectral region to which the dye has conferred sensitivity than when exposed to light to which the emulsion is naturally sensitive.

2. The method of manufacturing a light sensitive photographic coating having a widely variable gamma depending upon the spectral region of the color of the light to which itv is exposed, which consists in distributing throughout a molten emulsion a relatively small quantity of a sensitizing dye which imparts to the emulsion a substantially softer gradation when exposed to light within the spectral region to which the dye has conferred sensitivity than when exposed to light to which the emulsion is naturally sensitive, said dye acting on the silver halide particles and possessing the characteristic of conferring a gradation which varies in the sensitized region with the amount of dye used.

3. The method of manufacturing a light sensitive photographic coating having a widely variable gamma depending upon the spectral region of the color of the light to which it is exposed, which consists in distributing a dye having a slow sensitizing action throughout a molten emulsion, limiting the time of action of the dye so as to produce lower contrast in the sensitized region, and coating the paper or support with the dye sensitized emulsion, said dye acting on the silver halide particles and possessing the characteristic of conferring a gradation which varies in the sensitized region with the amount of dye used.

4. The method of manufacturing a light sensitive photographic coating having a widely variable gamma depending upon the spectral region of the color of the light to which it is exposed, which consists in distributing a dye having a slow sensitizing action throughout a molten emulsion at a temperature of approximately 86 F., said dye acting on the silver halide particles and possessing the characteristic of confer- .ring a gradation which varies in the sensitized region with the amount of dyeused, permitting the emulsion to stand for approximately two minutes, cooling the emulsion as rapidly as possible to approximately 50 F., thereafter shredding, washing, and remelting the emulsion, and coating the support therewith.

5. The method of manufacturing alight sensitive photographic coating having a widely variable gamma depending upon the spectral region of the color of the light to which it is exposed, which consists in distributing a dye having a slow sensitizing action throughout amolten emulsion and immediately thereafter coating the support, said dye acting on the sliver halide particles and possessing the characteristic of conferring a gradation which varies in the sensitized region with the amount of dye used.

sitive photographic coating having a widely variable gamma depending upon the spectral region of vthe color of the light to which it is exposed, which consists in distributing a dye having a slow sensitizing action throughout a molten emulsion, said dye acting on the silver halide particles and possessing the characteristic of conferring a gradation which varies in the sensitized region with the amount of dye used; lowering the temperature of the emulsion and limiting the time and temperature during which the dye is permitted to remain in the emulsion before chilling the latter, thereafter shredding, washing, and remelting the emulsion, and coating the support.

I. The method of manufacturing a light sensitive photographic coating having a widely variable gamma depending upon the spectral region of the color of the light to which it is exposed,

, which consists in distributing a dye having a slow sensitizing action throughout a :rnolten of the color of the light to which it is exposed,

which consists in distributing throughout a molten emulsion a sensitizing dye, said dye acting on the silver halide particles and possessing the characteristic of conferringa gradation which varies in the sensitized region with the amount of dye used, and restricting the sensitizing action of the dye on the emulsion to substantially less than its maximum sensitizing action, whereby the emulsion has a substantially softer gradation when exposed to light within the spectral region to which the dye has conferred sensitivity than when exposed to light to which the emulsion is naturally sensitive.

- 9. The method of manufacturing a light sensitive photographic coating having a widely variable gamma depending upon the spectral region of the color of the light to which it is exposed, which consists in distributing throughout a molten emulsion a dye having a slow sensitizing action, said dye acting on the silver halide particles and possessing the characteristic of ,conferring a gradation which varies in the sensitized region with the amount of dye used, and restricting the sensitizing action of the dye on the emulsion to substantially less than its maximum sensitizing action, whereby the emulsion has a substantially softer gradation when exposed to light within the spectral region to which the dye has conferred sensitivity than when exposed to light to which the emulsion is naturally sensitive.

10. The product of the process of claim 1. 11. The product of the process of claim 2. 12. The product of the process of claim 3. 13. The product of the process of claim 4. 14. The product of the process of claim 5. 15. The product of the process of claim 6. 16. The product of the process of claim 7. 17. The product of the process of claim 8. 18. The product of the process of claim 9'.

ROWLAND S. POTTER. RAY SEWARD HAGAMAN.