US2304925A

US2304925A - Photographic developer

Info

Publication number: US2304925A
Application number: US365787A
Authority: US
Inventors: Edwin E Jelley
Original assignee: Eastman Kodak Co
Current assignee: Eastman Kodak Co
Priority date: 1940-11-15
Filing date: 1940-11-15
Publication date: 1942-12-15
Anticipated expiration: 1959-12-15

Description

Patented Dec. 15, 1942 UNITED STATES PATENT ()FFICE PHQIDGRAPHIC DEVELOPER No Drawing. Application November 15, 1940,

Serial No. 305,737

6 Claims.

This invention relates to photographic developers and particularly to developers for producing colored photographic images.

The methods for forming colored photographic images by coupling development are divided into two classes, namely those in which the color forming or coupling component is incorporated in the emulsion layer prior to exposure and those in which it is dissolved in developing solution. Among the methods in which the coupler is incorporated in the emulsion layer, one type was described in Mannes and Godowsky U. S. application Serial No. 314,689, flied January 19, 1940. According to the process of that application, a coupler is mixed with a cellulosic material and the mixture is dispersed in gelatin in the form of minute particles. Sensitive silver halide grains may be incorporated either in the particles of cellulosic material in coupler or in gelatin in the form of the usual silver halide emulsions.

It has beeniound that when couplers are incorporated in gelatin layers in this manner in certain cases a very weak color or no color at all is produced when the emulsion is exposed in the usual manner and developed with the customary type of color producing developer.

It is, therefore, an object of the present invention to provide a coupling developer suitable for the development of emulsion layers in which the coupler is rendered non-dimming by admixture with celluloslc or other particles. iect is to provide a novel coupling developer for the development oi colored photographic images. Other objects will appear from the following description 01' my invention.

These objects are accomplished by adding to the developing solution of an aromatic alcohol having a relatively low solubility in water, in which thearomatic nucleus is separated by one or more methylene groups lrom the hydrous-7i radical. Such alcohols are powerful solvents for ionized molecules such as the reaction products resulting from the action of exposed silver halide on a color developer. They are also eilicient plasticizers for cellulose esters such as celluloc nitrate and ior natural gums.

Benzyl alcohol Oomph A further 01%- V fl-Dhenyl ethyl alcohol 7-phenyl-n-propyl alcohol Ocmomcmoa The concentration of the aromatic alcohol should not exceed about 50% of its solubility in the developer used. Benzyl alcohol is soluble in water to the extent of about 40 grams per liter and ,s-phenylethyl alcohol is soluble in water to the extent oi about 16 grams per liter. The amounts used in the developing solution should, accordingly, be kept within the solubility limits.

Suitable developers ior use with the photographic elements described in Marines and Godowsky application Serial No. 314,689 are the following:

It has been found that aromatic alcohols according to my invention are of value for incorporation in coupler developers in which the coupler is incorporated in the developing solutlon. When used with developers of this type,

there is a great increase to dye density particulerly in the denser regions of the scale. This ection may be due to the client of the phenyl aliryl alcohols in aiding penetration of the developer and white developers.

and coupler through the shell of the dye which forms around the silver halide crystals as they develop, although I do not wish to be limited to this explanation of the action of the agents used according to my invention, I have found that the addition of about 1% of benzyl alcohol, 0.-"

of p-phenylethyl alcohol or 0.2% of -phenyl-npropyl alcohol to coupler developers containing dissolved couplers produce this beneficial result. The following example illustrates a developer of this type.

Example 4 Solution A: pAminodimethylaniline sulfate grams 1 Sodium sulfite do 2 Sodium carbonate d 30 Potassium thiocyanate do 0.5 Benzyl alcohol do Water to; cc. 900

Solution B:

i-nitroacetoacetanilide grams 2.5 Isopropylalcohol cc 100 (In use, B is added to A.)

amples 1, 2 and 3 will produce black and white images in the absence of a coupler in the emulsion layer.

It will be understood that the couplers or color formers used to produce the dye images .to which this invention principally relates are asoaoas of the well known type contair 1g phenolic hydroxyl or reactive methylene g1 oup which produce dye images in the presence of the oxidation product of primary aromatic amino coupling developing agents.

My invention is to he considered as limited only by the scope of the appended claims.

I claim:

1. A photographic developer comprising a sliver halide developing agent and an aromatic alcohol having the following formula:

Gammon where :c is a positive integer of from 1 to 3.

2. A photographic color developer comprising a primary aromatic amino developing agentand an aromatic alcohol having the following formula:

( DSO where m is a positive integer of from 1 to 3.

3. A photographic color developer comprising a primary aromatic amino developing agent and. an appreciable amount, not in excess of of its solubility in the developer, of an aromatic alcohol having the following formula:

where z is a positive integer of from 1 to 3.

a. A photographic color developer comprising a primary aromatic amino developing agent and a small amount of benzyl alcohol.

5. A photographic color developer comprising a primary aromatic amino developing agent and a small amount of 5-pheriyl ethyl alcohol.

6. A photographic color. developer comprising a primary aromatic amino developing agent and a small amount of -phenyl-n-propyl alcohol.

EDW'IN E. JELL Y.