US2150704A

US2150704A - Photographic reversal process

Info

Publication number: US2150704A
Application number: US162331A
Authority: US
Inventors: Joseph C Ville
Original assignee: Eastman Kodak Co
Current assignee: Eastman Kodak Co
Priority date: 1937-09-03
Filing date: 1937-09-03
Publication date: 1939-03-14
Anticipated expiration: 1956-03-14

Description

Patented M... '14-, 1939 UNITED, STATES PATENT OF Fl CE man Kodak Company, ltoc poration of New Jersey Application September 3, Serial No. 182,331

No Drawing.

. 10 Claims.

This invention relates to a photographic reversal process and particularly to agents which fog the unexposed portions of a sensitive photographic layer prior to reversal.

In making positive photographic images by reversal from negative photographic images, it is customary tobleach or remove the metallic silver image before fixing the photographic element and while sensitive silver halide remains in the element, and then to re-expose the sensitive layer and develop a positive image in the originally unexposed portions of the element. Methods have been proposed for fogging the sensitive layer after the first development so that the second exposure is unnecessary and then developing a positive image in the usual way. Many of the methods, previously suggested for thispurpose were undesirable for various reasons, among which were that some of the fogging agents-required the use. of special developers for formationof the positive image with an attendant lime itation on the physical properties'pf the final positive image, while others tended to produce a stain in the film or paper in which'the image was formed.

It is accordingly an object of the present invention to provide a reversal process in which positive images may be produced on development without a second exposure. A further object is to provide a reversal process in, which an ordinary'developer may be used in the second devel-- especially the aromatic-ring -substituted derivatives. Specific compounds which I have found suitable are semicarbazide, pheny hydrazine, acetyl phenyl hydrazine, hydrazino benzoic acid and naphthyl hydrazine. The hydrazine may, therefore, be substituted with various groups, such as an aromatic ring of eitherthe benzene or the naphthalene series, or a carbamyl group, and these groups may themselves contain substituent groups. The carbamyl group is NHzC0-, so that hydrazine substituted with this group would have the structural formula NHzCO-NHNHflsemictirbMlde) The following is a specific example of one method of forming a reversed P s tive image according to m'yinventi'on.

A sensitive photographic element which may be aplate, film, or paper is expo'sedto a subject K namely, that of about heater, N. 1., a corin the usual way and is then developed in a solution having the following composition:

Water liter" .75 Sodium sulphite, desiccated grams 48.8 Hydroquinone d0 24.4 5 Boric a do 5.6 Potassium bromide do 2.6 Sodium hydr do 24.4 Water liter 1 10 After development at F. the film or paper is treated in the following solution at 65-70 F. for a sufilcient length of time to bleach and remove the silver image formed by development without afiectingthe silver halide: j 5

Water men- 1 Potassium bichromate grams.... 9.4 Sulfuric .acid (concentrated) cc. 12

The film or paper is then washed and im- 20 mersed in a clearing hath made up of grams of sodium sulfite in 1 liter'of water. The film or paper is then again washed and without being exposed to light is developed for 30 seconds in a developer having the same composition as for the first development, but having added thereto 10 grams of semicarbazide hydrochloride.

After development the film is again washed and dried although the fixing at this stage is not essential. 30

I have described my redeveloping solution as containing 10 grams of semicarbazide hydrochloride in 1 liter. However, the amount of hydrazine derivative used may-be varied widely, without departing from my invention. 3

Although I have described above the addition of my fogging or nucleating agent to the second developer, this compound mayalso be added 'to the clearing bath, if the clearing bath ismade alkaline. In this case the fogging agent is used 40 in the same concentration as in the developer,

10 grams per liter of solution. 4 v

It isto be understood that the above example is illustrative only and that my invention is to' tuted with a group selected from aromatic ring 5 and carbamyl groups, and developing a positive image in the film.

2. The method of a positive photographic image from a negative image in a photo- 5 graphic element without a second exposure to light, which comprises removing the negative image, treating the element in a bath containing a semi-carbazide as a nucleus-forming agent, and developing a positive image in the film. 3. The method of making a positive photographic image from a negative image in a photographicv element without a second exposure to light, which comprises removing the negative image, treating the element in a bath containing a phenyl hydrazine as a nucleus-formin solution of a hydrazine substituted with a group selected from aromatic ring and carbamyl groups as a nucleus-forming agent, and without exposing the element to light, developing a'positive image in the film.

5. The method of making a positiveph'otographic image by reversal from an element containing a visible negative image and a transparent, sensitive, positive image, which' comprises removing the negative image, subjecting the element in the absence or an exposing light, to the action of an aqueous solution or a hydrazine suhstituted with a group selected from aromatic ring and carbamyl groups and developing a visible positive image-in the element.

v 6. A photographic reversal process comprising v forming a silver image in a gelatino-silver halide smut; No. 2,150,701,.

CERTIFICATE-OF comcrIo u,

emulsion layer, removing the silver image with- 10 out aiiecting the remaining silver halide, subjecting the layer to the action of an aqueous solution oi semi carbazide as anucleus-forming agent, and developing a positive image in the layer. 15

8. A photographic reversal process comprising forming a silver image in a gelatino silver halide emulsion layer, removing the silver image without aiieoting the remaining silver halide, subjecting the layer to the action of an aqueous 20 solution of a phenyl hydrazine as a nucleus-forming agent, and developing a positive image in the layer.

9. A photographic reversal process comprisin forming a silver image in a gelatino-silver halide 25 emulsion layer, removing the silver image without affecting the remaining silver halide," subtion of hydrzino benzoic acid as a nucleusjecting the layer to the action of an aqueous solution-oi hydrazine enzoic acid as a nucleusforming agent, and eveloping a positive image in the layer.

10. A photographic reversal process comprising forming a silver image in a gelatino-silver halide emulsion layer, removing the silver image 5 without afiecting the remaining silver halide, subjecting the layer to the action of an aqueous solution of acetyl phenyl hydrazine as a nucleusforming agent, and developing a positive image in the layer. 7 40 JOSEPH ,C. VILLE.

Lama ii, i939.

.iosnrn c. V ILL'E is hereby certified. that error appe ersin the printed specification of the above" numbered patent .r'equt-ri:n5 correction ee'follows': Page 2, second coma, "line 23, claim 9, f "an-ira e: the; syllable-{worms and. syllable ue r hydrzinofhenzoic dam-as a ma a, me that. the maid Letters Patent" should'be-read with this oorre'ctlenftherein that the may cone for-n to any record remises in tho-Patent i e.

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