US3615580A

US3615580A - Photographic compositions and processes for making same

Info

Publication number: US3615580A
Application number: US766322A
Authority: US
Inventors: Richard W Karlson
Original assignee: Eastman Kodak Co
Current assignee: Eastman Kodak Co
Priority date: 1968-10-09
Filing date: 1968-10-09
Publication date: 1971-10-26
Anticipated expiration: 1988-10-26
Also published as: DE1950736B2; FR2020248A1; DE1950736A1; BR6913157D0; JPS54649B1; GB1282785A; BE740045A

Abstract

Photographic silver-halide emulsions comprising silver-halide grains which have been formed in the presence of a water-soluble nitrite. In one aspect, photographic silver-halide emulsions comprising said grains provide improved direct-print emulsions. In another aspect, this invention relates to a process for improving the photographic properties of a direct-print composition by adding water-soluble nitrites to the precipitation medium wherein the silver-halide grains are formed.

Description

United States Patent [72] Inventor Richard W. Karlson Rochester, N.Y.

[21] Appl. No. 766,322

[22] Filed Oct. 9, 1968 [45] Patented Oct. 26, 1971 [73] Assignee Eastman Kodak Company Rochester, N.Y.

[54] PHOTOGRAPHIC COMPOSITIONS AND PROCESSES FOR MAKING SAME 12 Claims, No Drawings [52] US. Cl 96/94 R, 96/108, 96/119 [51] Int. Cl G03c 1/06 [50] Field of Search 96/108, 110, 94 R,94 BF; 1/119 [56] References Cited UNITED STATES PATENTS 2,112,140 3/1938 Brooker et al. 260/240.6

2,493,747 1/ 1950 Brooker et a1. 260/2404 2,493,748 1/1950 Brooker et al. 260/2404 2,519,001 8/ 1950 Sprague 260/2401 Primary Examiner-William D. Martin Assistant Examiner- Bernard D. Pianalto Attorneys-W, H. J. Kline, Bernard D. Wiesde and Gerald E.

Battist ABSTRACT: Photographic silver-halide emulsions comprising silver-halide grains which have been formed in the presence of a water-soluble nitrite. In one aspect, photographic silver-halide emulsions comprising said grains provide improved direct-print emulsions. In another aspect, this invention relates to a process for improving the photographic properties of a direct-print composition by adding water-soluble nitrites to the precipitation medium wherein the silver-halide grains are formed.

PHOTOGRAPIIIC COMPOSITIONS AND PROCESSES FOR MAKING SAME This invention relates to new photographic silver-halide emulsions. In one aspect, this invention relates to direct-print silver-halide emulsions wherein the silver-halide grains are formed in the presence of a water-soluble nitrite. In another aspect, this invention relates to a novel method of improving the photographic properties, such as print stability, speed, Dmin, discrimination, etc., in direct-print silver-halide emulsions.

It is known in the art to add various addenda to direct-print silver-halide compositions to improve the photographic properties of these compositions. Compounds such as thioureas, sodium nitrite, stannous chloride, urazoles and the like have been added as coating addenda to provide halogen acceptors in direct-print compositions. It is also known to use com-- pounds such as thiocyanates, thioethers and lead salts during the formation of the silver-halide grains to provide improved image properties in direct-print compositions. However, it is desirable to provide means which will further improve the photographic properties of direct-print compositions.

We have now found that direct-print compositions having improved photographic properties can be obtained with a direct-print silver-halide emulsion therein the grains of said silver-halide emulsion are formed in the presence of a watersoluble nitrite. In a preferred embodiment of this invention, the direct-print composition comprises a halogen acceptor as an addendum. In another preferred embodiment, the halide of said silver-halide is predominantly bromide.

According to the present invention, water-soluble nitrites I can be effectively utilized during the formation of the silverhalide grains to provide improved photographic properties such as improved print stability, photographic speed, Dmin, discrimination, etc. Generally, the water-soluble nitrites can be added to any of the solutions used in the precipitation step of forming the silver-halide grains. Typical useful water-soluble nitrites include sodium nitrite, potassium nitrite, and the like. The water-soluble nitrites are generally added to the solutions to provide a concentration of 1X10 to about one mole and preferably from 0.001 to about 0.5 mole of water-soluble nitrite per mole of silver halide formed in the precipitation step. in a preferred embodiment, the water-soluble nitrites are those which are soluble in water at room temperature in a concentration of at least 0.1 gram per 100 ml. of water. Those nitrites which are highly preferred in the emulsions are the alkali metal nitrites which have a water solubility of at least 10 grams per 100 ml. of water at room temperature.

It is not completely understood whether the nitrite is incorporated into the grain or whether reaction products of the nitrite are responsible for the improved photographic properties. Therefore, it is contemplated to be within the scope of the invention that the grains are formed in the presence of nitrites (or reaction products thereof) as long as they are added to or present in the precipitation medium during formation of the silver-halide grains.

The water-soluble nitrites can be generally utilized in any of the photographic compositions which will function as directprint emulsions. Suitable silver halides include internally sensitive silver bromide, silver iodobromide, silver chlorobromide, silver chloroiodobromide, and the like. The preferred emulsions are those wherein the halide of the silver is predominantly bromide. in a typical embodiment, the preferred emulsions are direct-print emulsions having higher internal sensitivity than surface sensitivity as' described by Hunt in Photographic Science and Engineering," Vol. 5, No. 2, Mar.-Apr., 1961, pages 104-108. For a description of suitable emulsions, reference is made to Davey et al., U.S. Pat. No. 2,592,250 issued Apr. 8, 1952; U.S. Pat. No. 3,206,316; Porter et al., U.S. Pat. No. 3,206,313; Sutherns, U.S. Ser. No. 667,091 filed Sept. 12, 1967; Kitze, Belgian Pat. No. 689,515 issued Jan. 13, 1967; Glafkides, Photographic Chemistry," Vol. 1, pages 31-32, Fountain Press, London; and in McBride, U.S. Pat. No. 3,271,157 issued Sept. 6, 1966, and U.S. Pat. No. 3,287,137.

In one preferred embodiment, the silver-halide compositions are direct-print compositions which contain halogen acceptors. Generally, suitable halogen acceptors are compounds which enhance the photolytic yield (as determined by radiographic analysis, for example) and/or the photolytic density of a printout emulsion. Typical halogen acceptors for use in the present emulsions include those disclosed in McBride, U.S. Pat. No. 3,287,137; McBride, U.S. Pat. No. 3,271,157; and Kitze, U.S. Pat. No. 3,241,971. In one preferred embodiment, nitrogen-containing halogen acceptors according to the Mc- Bride patents, above, are utilized in the emulsions. In another preferred embodiment, the halogen acceptors are of the type disclosed in Kitze, U.S. Pat. No. 3,241,971, which contain mercaptan groups and especially the heterocyclic mercaptans and thiones. In yet another embodiment, the halogen acceptors are urazoles of the type disclosed in in Bacon et al., U.S. Pat. No. 3,396,017 issued Aug. 6, 1968-.

The emulsions of the invention are generally made with a slight excess of halide ion present over that necessary initially to precipitate all of the silver as silver halide in the preparation thereof.

The silver-halide emulsions of this invention can be sensitized with various dyes. Typical dyes are disclosed in Mc- Bride, U.S. Pat. No. 3,287,136; Brooker, U.S. Pat. Nos. 1,846,301 issued Feb. 23, 1932, 1,846,302 issued Feb. 23, 1932, and 1,942,854 issued Jan. 9, 1934; White, U.S. Pat. No. 1,990,507 issued Feb. 12, 1935; Brooker and White, U.S. Pat. Nos. 2,112,140 issued Mar. 22, 1938, 2,165,338 issued July 11, 1939, 2,493,747 issued Jan. 10, 1950, and 2,739,964 issued Mar. 27, 1956; Brooker and Keyes, U.S. Pat No. 2,493,748 issued Jan. 10, 1950; Sprague, U.S. Pat. Nos. 2,503,776 issued Apr. 11, 1950, and 2,519,001 issued Aug. 15, 1950; l-leseltine and Brooker, U.S. Pat. No. 2,666,761 issued Jan. 19, 1954; l-leseltine, U.S. Pat. No. 2,734,900 issued Feb. 14, 1956; Van Lare, U.S. Pat. No. 2,739,149 issued Mar. 20, 1956; British Pat. No. 450,958 accepted July 15, 1936, and elsewhere in the literature.

The sensitizing amount of the spectral-sensitizing dyes utili-zed can be widely varied. The concentration of the dyes will vary according to the type of emulsion and according to the effect desired. The suitable and most economical concentration for any given emulsion will be apparent to those skilled in the art upon making the ordinary tests and observations customarily used in the art of emulsion making. Generally about 10 to 1000 mg. of dye per mole of silver halide in the emulsion are utilized. About 0.005 to 0.5 mole percent of sensitizing dye based on the silver halide in the emulsion is a typical working range. A single dye or combinations of several dyes can be used in the present emulsions for spectral sensitization.

Merocyanine-spectra1-sensitizing dyes are preferably utilized in the emulsions of the invention as stain imparted to emulsions containing such dyes is substantially bleached or made colorless during photodevelopment. Also, merocyanine dyes tend to be less easily displaced or desorbed from the silver-halide crystals of the emulsions of the invention than cyanine dyes by many halogen acceptors that are utilized in light-developable, direct-print silver-halide emulsions.

Various colloids can be used as vehicles or binding agents in preparing the silver-halide emulsions of this invention. Satisfactory colloids which can be used for this purpose include any of the hydrophilic colloids generally employed in the photographic field, including, for example, gelatin, colloidal albumin, polysaccharides, cellulose derivatives, synthetic resins such as polyvinyl compounds, including polyvinyl alcohol derivatives, acrylamide polymers and the like. In addition to the above hydrophilic colloids, the vehicle or binding agent can also contain hydrophobic colloids such as dispersed polymerized vinyl compounds, particularly those which increase the dimensional stability of photographic materials. Suitable compounds of this type include water-insoluble polymers of alkyl acrylates or methacrylates, acrylic acid, sulfoalkyl acrylates or methacrylates, and the like.

The above-described emulsions of the invention can becoated on a wide variety of supports in accordance with usual practice. Typical supports for photographic elements of the invention include glass, metal, paper, polyolefin-coated paper, cellulose nitrate film, cellulose acetate film, polystyrene film, polyester films such as polyethylene terephthalate film, heatresistance polymeric films such as high temperature polyester, polyimide, polycarbonate films, and the like.

In one embodiment, a direct-print image can be formed with a photographic element containing an emulsion of the invention; the photographic element is initially exposed to a relatively short duration and high-intensity source of electromagnetic radiation (e.g., at least about 0.1 foot-candle second at an intensity of more than about 100 foot-candles) such as a high-intensity mercury, xenon or X-radiation source to form a latent image in the emulsion of the photographic element, and thereafter the resulting latent image is photodeveloped by overall exposure to a radiation source of lower intensity than the original exposure. Generally, the latent image formed in the emulsion in the first instance is not visible and does not become visible until photodevelopment. Heat can also be utilized during the photodevelopment step. Typically, the subject emulsions are heated to a temperature of about 90 C. to 200 C. for about 1 to 30 seconds and photodeveloped after the initial high-intensity exposure.

Photographic elements containing direct-print emulsions can also be latensified to increase the speed of the emulsion. This can be accomplished by exposure between the initial high-intensity exposure and photodevelopment with a filtered light which is filtered to remove substantially all of the radiation absorbed directly by the silver halide, but transmits radiation in the regions conferred to the silver halide by the sensitizing dyes normally used in direct-print emulsions. where the silver halide has been prepared in the presence of a thioether and/or a lead salt, the latensification procedure is quite useful to improve speed when the halide of the silver halide is less than about 90 percent bromide and the balance is either chloride or iodide. When the silver halides are prepared in the presence of water-soluble nitrites, similar improvements can be obtained by latensification when the low-bromide concentrations are utilized.

The invention can be further illustrated by the following examples:

EXAMPLE 1 A direct-print silver chlorobromide emulsion is prepared in the presence of a thioether and a lead salt as described in example of McBride, US. Pat. No. 3,271,157, except 2 grams of NaNO per mole of silver is present in the mixture during the formation of the silver-halide crystals.

To 168 g. of this emulsion containing 0.07 mole of silver melted at 40 C. is added a solution containing 2.8 g. urazole and conventional coating aids. The emulsion is coated on a single weight paper stock at 256 mg. of silver per ft. and 558 mg. of gelatin per ft.

A second emulsion is made and coated in the same way except that the N aNO is omitted.

After drying, one set of coatings is exposed in an Edgerton G and G. Mark IV Sensitometer for 10 seconds modulated by a step tablet containing 21 2 steps. The coatings are then photodeveloped by exposing them to cool white fluorescent lamps at 50 F.C. for 5 minutes. A second set is incubated one week at 120 F 35 percent RH, exposed and photodeveloped as above.

Both sets of tests are faded for two weeks by exposure to 50 PC. of cool white fluorescent light to give the speeds and densities shown below.

Fresh test incubated test No. of No. of

visibl e visible Emulsion Dmin. AD steps Dmin. AD steps Control 33 25 14 32 13 15 +NaNO2 (2 gJAg mole) 31 .28 15 31 .14 16 Similar improvements are obtained when potassium nitrite, ammonium nitrite and magnesium nitrite are used in the precipitation in place of the sodium nitrite.

EXAMPLE 2 An emulsion is made and coated as in example 1, except only 1.0 g. NaNO /Ag. mole is used and the NaNO and lead salt are dissolved in water before adding to the gelatin solution.

An emulsion is prepared and coated as in example 1, except that 1.0 g. of NaNO is used and the NaNO lead salt and thioether are dissolved in water before adding to the gelatin solution.

Fresh test incubated test No. of No. 0

visib l e visibl e Emulsion Dmin AD stops Dmin. AD steps Control 05 15 3'2 09 i5 +NuNOz (l gJAg mole) 30 .10 16 .31 11 16 it can be seen from examples l-3 that the nitrite can be added to the precipitation medium in a number of ways and it will still provide improvements in the photographic properties of the resultant emulsion.

EXAMPLE 4 This example demonstrates the effectiveness of the watersoluble nitrite when used during the precipitation of the silverhalide grains in contradistinction to the use of the same watersoluble nitrite when used as a halogen acceptor. Emulsion A is prepared in the presence of a thioether and a lead salt, as described in example 10, McBride, US. Pat. No. 3,271,157. Emulsion B is prepared in the presence of a thioether, a lead salt and 1 g. of sodium nitrite per silver mole.

The spectral-sensitizing dye 5-[(5,6-dichloro-l-B-diethylamino ethyl-3-ethyl-2-benzimidazolinylidene)ethylidene1-3- ethyl rhodanine is added to both emulsions at mg. per silver mole along with other conventional coating aids. One g. of sodium nitrite per mole of silver is also added to Emulsion A as a coating addendum. The emulsions are then coated, exposed, processed and incubated for one week as described in example 1. The following table illustrates the results:

The water-soluble nitrites provide highly improved properties when incorporated in the grain, as evidenced by Emulsion B as compared with Emulsion A wherein sodium nitrite is added as a halogen acceptor.

EXAMPLE 5 Fresh results Incubation results Addi- N o. of No. of Emulsion tional visible visible number addenda Dmin. AD steps Dmin. AD steps A 28 909 28 07 15 II 35 36 16 .33 21 16 I-l-II .34 36 16 34 16 II 34 35 16 32 22 17 Improved image properties are also obtained when the halogen acceptors. dithiourazole, dithiourazole hydrazine salt, thiourea, thiosemicarbazide and l-n-butyl-l ,2,5,6-tetrahydro- 1,3,5-triazine-4-thiol are used in silver-halide emulsions containing grains formed in the presence of water-soluble nitrites.

Although the invention has been described in considerable detail with particular reference to certain preferred embodiments thereof, variations and modifications can be effected within the spirit and scope of the invention as described hereinbefore and in the appended claims.

I claim:

l. A silver-halide emulsion containing silver-halide grains formed in the presence of a water-soluble nitrite, said nitrite being present in a concentration of about 1X10 to about one mole per mole of silver halide formed.

2. A silver-halide emulsion according to claim 1 wherein said grains are formed in the presence of thioether and said water-soluble nitrite.

3. A silver-halide emulsion according to claim 1 wherein said grains are formed in the presence of a water-soluble lead salt, a thioether and said water-soluble nitrite.

4. A silver-halide emulsion according to claim 1 wherein said nitrite is an alkali metal nitrite.

5. A silver-halide emulsion according to claim 1 wherein said nitrite is sodium nitrite.

6. A direct-print silver-halide composition according to claim 1 wherein said silver-halide grains have a predominant amount of radiation sensitivity internal tosaid grains.

7. A silver-halide composition according to claim 1 wherein the halide of said silver halide is predominantly bromide.

8. A direct-print silver-halide composition according to claim 1 further comprising a halogen acceptor in admixture with said silver-halide grains.

9. A direct-print silver-halide composition according to claim 1 further comprising a nitrogen-containing halogen acceptor.

10. A direct-print silver-halide composition according to claim 1 comprising a urazole compound as a halogen acceptor.

11. A photographic element comprising a support and a layer of the silver-halide emulsion of claim 1.

12. An improved process for preparing direct-print silverhalide emulsions, the improvement comprising forming the silver-halide grains of said emulsion in a precipitation medium containing from about 1X10 to about one mole per mole of silver halide formed of a water-soluble nitrite.

mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,61 5, 580 Dated October 22, 1971 Invent r( Richard Warren Karlson It is certified that error appears in the above-identified patent: and that said Letters Patent are hereby corrected as shown below:

F- Column 1 line 2L "therein" should read wherein---; 1

line 39, "1x10 should read ---lx1O" Column 3, line35, "where" should read ---where--; line 66, "10 should read ---1o""---; line 7, "21 2" should read 2'N'2- line 37, "0" should read -of--- (second oocurenoe) line 2L "909" should read ---.O9---; line 31 sEIould read Claim 1, liu 'zg 3, "10 should re 1 "-10" should read ---10 Claim 12, line 1 "1O Signed and sealed this 2nd day of May 1972.

(SEAL) Attest;

EDWARD M.FLETCHER,Jz-. ROBERT GOT'ISCHALK Attesting Officer Commissioner of Patents

Claims

2. A silver-halide emulsion according to claim 1 wherein said grains are formed in the presence of thioether and said water-soluble nitrite.
3. A silver-halide emulsion according to claim 1 wherein said grains are formed in the presence of a water-soluble lead salt, a thioether and said water-soluble nitrite.
4. A silver-halide emulsion according to claim 1 wherein said nitrite is an alkali metal nitrite.
5. A silver-halide emulsion according to claim 1 wherein said nitrite is sodium nitrite.
6. A direct-print silver-halide composition according to claim 1 wherein said silver-halide grains have a predominant amount of radiation sensitivity internal to said grains.
7. A silver-halide composition according to claim 1 wherein the halide of said silver halide is predominantly bromide.
8. A direct-print silver-halide composition according to claim 1 further comprising a halogen acceptor in admixture with said silver-halide grains.
9. A direct-print silver-halide composition according to claim 1 further comprising a nitrogen-containing halogen acceptor.
10. A direct-print silver-halide composition according to claim 1 comprising a urazole compound as a halogen acceptor.
11. A photographic element comprising a support and a layer of the silver-halide emulsion of claim 1.
12. An improved process for preparing direct-print silver-halide emulsions, the improvement comprising forming the silver-halide grains of said emulsion in a precipitation medium containing from about 1 X 10 5 to about one mole per mole of silver halide formed of a water-soluble nitrite.