US3689270A

US3689270A - Light-sensitive compositions comprising a silver salt of a tetraazaindene

Info

Publication number: US3689270A
Application number: US788933A
Authority: US
Inventors: George De Winter Anderson; Hatfield Broad Oak; Ronald E Watts
Original assignee: Minnesota Mining and Manufacturing Co
Current assignee: 3M Co
Priority date: 1968-01-08
Filing date: 1969-01-03
Publication date: 1972-09-05
Anticipated expiration: 1989-09-05
Also published as: JPS53296B1; GB1230642A; BE726623A; CA918989A; FR2000052A1; DE1900780A1

Abstract

A LIGHT-SENSITIVE COMPOSITION COMPRISING THE SILVER SALT OF A TETRAAZAINDENE COMPOUND AND INTIMATELY ASSOCIATED PORTION OF SILVER HALIDE IS SHOWN, TOGETHER WITH METHODS FOR PREPARING THE COMPOSITION.

Description

3,639,276 Patented Sept. 5, 1972 LIGHT-SENSITIVE COMPOSITIONS COMPRISING A SILVER SALT OF A TETRAAZAINDENE George de Winter Anderson, Hatfield Broad Oak, near Bishops Stortford, and Ronald E. Watts, Bishops Stortford, England, assignors to Minnesota Mining and Manufacturing Company, St. Paul, Minn. I No Drawing. Filed Jan. 3, 1969, Ser. No. 788,933 Claims priority, application (age-at Britain, Jan. 8, 1968,

Int. Cl. G03c 1/02 US. CI. 96-76 17 Claims ABSTRACT OF THE DISCLOS R A light-sensitive composition comprising the silver salt of a tetraazaindene compound and intimately associated portion of silver halide is shown, together with methods for preparing the composition.

This invention relates to light-sensitive compositions which, upon exposure to a light image, may be developed to yield photographic image reproductions. The invention further relates to processes for preparing these compositions.

It is desired that photographic elements having lightsensitive compositions be capable of providing sharp photographic reproductions having dense images and having stable and clear backgrounds. Such photographic elements desirably are further capable of being conveniently and rapidly processed.

It is an object of the present invention to provide a lightsensitive composition which is characterized by excellent resolution, by high image and background stability and by negligible fog accumulation.

Briefly, the present invention relates to a light-sensitive composition comprising a silver salt of a tetraazaindene having the formula:

wherein R is a hydrogen atom, or an alkyl (e.g., methyl,

ethyl, butyl, etc.), aralkyl (e.g., methyl, phenyl, etc.), or an alkylthio group; R and R which may be the same or different, are a hydrogen atom or a lower alkyl (e.g., methyl, ethyl, propyl, butyl, etc.) or substituted alkyl group such as a hydroxyalkyl group, or R and R together with the adjacent nitrogen atom may form a heterocyclic ring such as morpholine or pyridine ring; and Y represents a hydrogen atom or an alkyl, e.g., methyl, ethyl, propyl, alkylthio, aryl such as phenyl, naphthyl, etc., or amino such as --NH dimethylamino, etc. group;

together with an intimately associated portion of :a silver halide of amount sufiicient to provide a weight ratio of silver in the silver halide to silver in the light-sensitive composition of from 0.001/1 to 0.5/1.

The present invention also relates to photographic elements comprising a base and at least one layer having a light-sensitive composition of the present invention and further relates to a method of producing such light-sensitive compositions. Briefly, the light-sensitive compositions of the present invention may be produced by a method comprising reacting in aqueous media a water-soluble silver salt with a tetraazaindene having the general formula:

wherein R, R R and Y are as described above, to form the silver salt of said tetnaazaindene; and

contacting said aqueous media with a Water soluble halide to form light-sensitive halide therein.

Photographic elements prepared from light-sensitive compositions of the present invention may be rapidly developed and fixed by conventional wet processing techniques to yield excellent image reproductions which are characterized by very little fog. Considering the quantity of silver in the compositions, the images produced therefrom are unusually dense.

The tetraazaindene-silver salt compounds of the present inventionmay conveniently be prepared by reacting in aqueous media the tetraazaindene compounds represented by the above formula, or a soluble salt of these tetraazaindene compounds adjusted to pH 6 to 8.5 with nitric acid, with from about 0.5 to 1.5 molecular equivalents of a soluble silver salt, such as, for example, silver nitrate. The resulting tetraazaindeue-silver salts are soluble in water but may crystallize or precipitate out if the aqueous media is sufficiently concentrated. Although the soluble silver salt (e.g., silver nitrate) may be used in up to 1.5 molecular proportions relative to the tetraazaindene compounds, the preferred limits are from 0.5 to 0.95 molar proportions, since it appears that an excess of tetraazaindene acts as a stabilizer and antiioggant for the composition.

The light-sensitivity of the compositions of the present invention is believed to be due to the presence therein of silver halide. It is believed that the tetraazaindene-silver salts are but slightly if at all light sensitive. Once a latent image has been formed in the silver halide, however, it appears that subsequent development utilizes the silver provided by the tetraazaindene-silver salt, since only very small amounts of silver halide need be present in the lightsensitive compositions of the present invention to yield sharp, dense images.

Silver halide is present in the compositions of the present invention preferably in amounts sufiicient to yield a weight ratio of silver in the silver halide to total silver in the composition of from 0.001/1 to 0.5/ 1. The optimum ratio is best found by trial'and error, and is usually not greater than about 0.1/ 1.

Silver halides which are suitable for use in the present invention include, for example, silver chloride, silver bromide, silver iodide or mixtures thereof.

Light-sensitive compositions of the present invention may be produced by several methods. In one method, for example, a tetraazaindene compound in aqueous media is treated with silver nitrate to form the tetraazaindenesilver salt. Soluble halide is then added which reacts in situ with silver from either an excess of the silver nitrate or from the soluble tetraazaindene-silver salt, to form silver halide. The media may then be coated onto a photographic substrate such as glass, film, or paper to form a tion, for example, by coating the composition from aqueous media onto a photographic substrate. The aqueous coating media preferably contains a suitable water-soluble binder material, such as gelatin or Gelvatol (polyvinylalcohol, a trademarked product of Monsanto Chemic'al Co.). In another method, aqueous media containing a tetraazaindene-silver salt and a water-soluble binder may be coated on a substrate which contains soluble halide, so that some of the halide is leached from the substrate to form silver halide in the coated media as explained above.

Photographic elements prepared from the light-sensitive compositions of the present invention may, after exposure, be developed with wet developers such as aqueous phenidone hydroquinone or meto hydroquinone developers. Fixing can thereafter be affected by methods which are commonly employed for silver halide photographicelements. For example, a thiosulfate fixer may be employed. Due to the water solubility of the tetraazaindene-silver salt, fixing is usually rapid. In one variation, a solution of hydroquinone developer is coated onto an unexposed photographic element containing a composition of the present invention to yield a heat-developable photographic element. After exposure, the photographic element is heated to, for example 160 C. to develop the image. In yet another variation, an unexposed photographic element comprising a composition of the present invention and a developer for silver halide, such as hydroquinone, may, after exposure, be developed and substantially fixed in one step by treating the element with an alkaline solution. Preferably, however, a photographic element prepared from a light-sensitive composition of the present invention first developed by a Wet developer and is then fixed in a thiosulfate fixer as described above.

Photographic elements prepared from the light-sensitive compositions of the present invention are particularly useful as masters in diazo reproductions. It has been found that such photographic elements can be used without fixing to produce many copies by this process. It has been further found that the photographic images produced by this process are unusually sharp. Line images of 1000 lines per millimeter can be accurately reproduced. Photographic elements containing the light-sensitive compositions of the present invention consequently are particularly useful for producing micro images.

The light-sensitive compositions of the present invention are sensitive primarily to ultraviolet light and to light in the shorter wavelength region of the visible spectrum. The sensitivity of the compositions can be extended to longer wavelengths by the addition of spectral sensitizers which are commonly employed in silver halide emulsions, such as, for example, cyanine and merocyanine dyes.

The following examples are presented for illustrative purposes only and should not be construed as limiting the scope of the present invention.

EXAMPLE 1 The diethylamine salt of 5-diethylaminomethyl-4-hydroxy 6 methyl 2 methylthio-l,3,3a,7-tetraazaindene (17.7 g.) was dissolved in water. Sufiicient 2 N nitric acid was added to give 100 ml. of solution of pH 8.0. This solution was stirred and warmed to 35 C. and 1 M silver nitrate (37.5 ml.) was added through a glass jet, followed by 1 M potassium bromide solution (3.75 ml.). To this mixture was then added a 12% aqueous gelatin solution (100 ml.), 4% chrome alum solution (6 ml.) and Teepol 610 (0.4 ml.) (aqueous sodium lauroyl sulfate, a product of Shell Chemical Co.). This emulsion was coated at a wet thickness of 0.005 inch onto a clear polyester film base and dried.

After exposure of the coating through a photographic negative to 2.84 l meter candle seconds of tungsten light the film was developed for 15 seconds in a commercial phenidone-hydroquinone developer (P.Q. Universal, a product of Ilford, Ltd.) at a dilution of 1 part of developer to 9 parts of water. A black and white positive transparency of density 3.0 and contrast 1.0 was obtained.

EXAMPLE 2 To this mixture was then added 12% aqueous gelatin solution ml.), 4% aqueous chrome alum solution (6 ml.) and Teepol 610 (0.4 ml.) (a product of Shell Chemical Co.). The resulting emulsion was then coated at a wet thickness of 0.005 inch onto a clear polyester film base and dried.

After exposure through a photographic negative to 284x10 meter candle seconds of tungsten light, the film was developed for 15 seconds as in Example 1 to give a black and wln'te positive transparency of density 2.6 and contrast 1.1. The sensitivity of this film was found to have been extended into the green region of the spectrum by the sensitizing dye.

EXAMPLE 3 The diethylamine salt of 5-diethylaminomethyl-4-hydroxy-6-methyl-2-methylthio-1,3,3a,7-tetraazaindene (17.7 g.) was dissolved in water. Sutficient 2 N nitric acid was added to give 100 ml. of solution of pH 8.0. This mixture was then stirred and warmed to 35 C. and a 12% aqueous solution of gelatin (100 ml.) added. 1 M silver nitrate solution (37.5 ml.) was added through a glass jet followed by 1 M potassium bromide solution (3.75 ml.). Finally 4% chrome alum solution (6 ml.) and Teepol 610 (0.4 ml.) (a product of Shell Chemical Co.) were added and the resulting emulsion was coated at a wet thickness of 0.05 inch onto a clear polyester base.

After exposure through a photographic negative to 2.84 10 meter candle seconds of tungsten light the film was developed for 20 seconds as in Example 1 to give a black and white positive transparency of density 2.0 and contrast 2.0.

EXAMPLE 4 The sodium salt of 5-diethylaminomethyl-4-hydroxy-6- methyl-2-methylthio-l,3,3a,7-tetraazaindene (15.2 g.) was dissolved in water. Sufiicient 2 N nitric acid was added to give 100 ml. of solution of pH 8.0. This solution was stirred and warmed to 35 C. and 12% aqueous gelatin solution was added (100 ml.). Then 1 M silver nitrate solution (37.5 ml.) was added through a glass jet followed by 1 M potassium chloride solution (3.75 ml.) and Teepol 610 (0.4 ml.) (a product of Shell Chemical Co.). The emulsion so prepared was coated at a wet thickness of 0.005 inch onto a clear polyester film base and dried.

After exposure of the coating through a negative to 1.25 X 10' meter candle seconds of tungsten light the film was developed for 10 seconds as in Example 1 to give a black and white positive transparency of density 2.4 and contrast 4.0.

EXAMPLE 5 The diethylamine salt of 5-diethylaminomethyl-4-hydroxy-6-methyl-Z-methylthio-l,3,3a,7-tetraaza.indene (17.7 g.) was dissolved in water. Sulfic-ient 2 N nitric acid was added to give 100 ml. of solution of pH 8.0. This solution was stirred and warmed to 35 C. and a 12% aqueous solution of gelatin (100 ml.) was added. Then 1 M silver nitrate solution (37.5 ml.) was added through a glass jet followed by 1 M potassium bromide solution (3.75 ml.). An aqueous solution ml.) of the following sensitizing dye was then added:

Finally to this mixture was added 4% chrome alum solution (6 m1.) and Teepol 610 (0.4 ml.) (a product of Shell Chemical Co.) The emulsion so obtained was coated at a wet thickness of 0.005 inch onto a clear polyester film base and dried.

After exposure through a photographic negative to 284x10 meter candle seconds of tungsten light the film was developed for seconds as in Example 1. This gave a black and white positive transparency of density 2.9 and contrast 1.5. The sensitivity of this film was found to have been extended into the green region of the spec trum by the sensitizing dye.

EXAMPLE 6 The diethylamine salt of S-diethylaminomethyl-4-hydroxy-6-mefihyl-2-methylthio-l,3,3a,7 tetraazaindene (l g.) was dissolved in water (10 ml.) and the pH was adjusted to 6.0 with nitric acid. 5 ml. of a aqueous solution of partially hydrolyzed polyvinyl acetate (Gelvatol, a trademarked prdouct of Monsanto Chemical Co.) was added and under red safe lights a solution of 0.3 g. silver nitrate dissolved in 2.5 ml. water was added. No crystals separated immediately and the solution was coated onto a paper which contained 0.1 mg. of soluble chloride per square decimeter and dried. During coating at least some of this soluble chloride became incorporated in the coating composition and it was calculated that the coating contained up to 4.3% by weight of silver chloride.

The coated paper was exposed to light behind a negative image and developed in P.Q. Universal developer (a product of Ilford Ltd.) diluted 1 part of developer with 19 parts water. The paper was then washed in water at room temperature, and a black image with low background fog was obtained. The image processed in this manner was found to be stable against further light exposure.

When the initial solution was allowed to crystallize before coating, an image of comparable quality was found to be obtained.

To a second sheet of the coated paper of this example was applied a coating of an alcoholic solution of hydroquinone. The paper was dried and similarly exposed to light. A portion of this sheet was developed by immersing in an alkaline solution to form an image and was fixed by washing in water. Another portion of this exposed sheet was developed solely by heating to a temperature of 160 C.

EXAMPLE 7 The diethylamine salt of 5 diethylaminomethyl-4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene (0.85 g.) was dissolved in water (10 ml.) and the solution was adjusted to pH 2.5 with nitric acid. 5 ml. of a 12% gelatin solution were added, and under red safe lights a solution of 0.3 g. of silver nitrate dissolved in 2.5 ml. water was added. The resulting suspension of fine crystals was coated onto a paper base which contained 0.1 mg. of soluble chloride per square decimeter and dried. During coating at least some of this soluble chloride became incorporated in the coating and it has been calculated that the coated composition contained up to 4.3% by weight of silver chloride.

The paper was exposed to light through a negative image and developed in the phenidone-hydroquinone developer of Example 6 and was subsequently washed in water at room temperature. A strong black image with low fog was obtained. The image processed in this manner was stable against further light exposure.

To another sheet of the light-sensitive coated paper of this example was applied a coating of a solution of hydroquinone. The sheet was dried and exposed to light in a similar way. One half of the sheet was developed by immersing it in an alkaline solution and was fixed by washing in water. The other half was developed by heating the exposed dry sheet to a temperature of C.

EXAMPLE 8 The diethylamine salt of 5 diethylaminomethyl-4-hydroxy-6-methyl-2-methylthio-1,3,3a,7-tetraazaindene (0.85 g.) was dissolved in water, the pH adjusted to 8 and the volume adjusted to 3.75 ml. Silver nitrate (0.3 g.) was dissolved in 2.5 ml. of water and, under red safelights, the silver nitrate and tetraazaindene solutions were simultaneously jetted into a mixture of 6 ml. of a 0.001 M aqueous solution of l[2'(3' methyl-thiazolidine)] 2-methyl-2[5" (2" thio-3" carboxymethyl-thiozolid-4"-one)] dimethinemero-cyanine which had been adjusted to pH 7 by addition of ammonia solution and 1 ml. of 20% aqueous Gelvatol (a trademarked product of Monsanto Chemical Co.). The resulting emulsion was coated onto a paper containing 0.1 mg. of soluble chloride per square decimeter and dried. During coating at least some of this soluble chloride became incorporated in the coating, and it was calculated that the coated composition contained up to 4.3 by weight of silver chloride.

The coating was exposed to light through a negative image and was developed in the developer of Example 6. It was subsequently washed in water at room temperature and showed a strong black image with low fog. The image processed in this manner was stable against further light exposure.

This coating showed a speed increase of fifty times over a corresponding coating having no sensitizing dye.

EXAMPLE 9 4 hydroxy-6-methyl-5-piperidinomethyl-l,3,3a,7-tetraazaindene (0.7 g.) was dissolved in 10 ml. of water and the solution adjusted to pH 2.5 with nitric acid. 5 ml. of 20% Gelvatol (a trademarked product of Monsanto Chemical Co.) was added, and under red safelights a solution of 0.3 g. of silver nitrate dissolved in 2.5 ml. of water was added. The resulting suspension of fine crystals was coated onto a paper base containing 0.1 mg. of soluble chloride per square decimeter and dried. During coating at least some of this soluble chloride became incorporated in the coating, and it was calculated that the coated composition contained up to 4.3 by weight of silver chloride.

The paper was exposed to light through a negative image and was developed in the developer of Example 6. It was subsequently washed at room temperature and showed a strong black image with low fog.

To a second sheet of the coated paper was applied a coating of hydroquinone. This sheet was dried and was exposed to light in a similar way. The image was developed by dipping a portion of the paper into an alkaline solution and was fixed by washing in water. The remaining portion of the sheet was developed by heating to a temperature of 160 C.

EXAMPLE 10 5 diethylaminomethyl 4-hydroxy-2-methyl-6-methylthio-l,3,3a,7-tetraazaidene (2.81 g.) was dissolved in water (15 ml.). This solution was stirred, warmed to 45 C., and 10% gelatin solution (35 ml.) was added. 1 M silver nitrate solution (10 ml.) was added slowly with efiicient stirring and after stirring for 10 minutes a 1 M potassium bromide/iodide solution containing 3% iodide (1.0 ml.) was added slowly. After stirring for a further 10 minutes 7 chrome alum solution (2 ml.) was added and the emulsion so prepared was coated at a wet thickness of 0.003 inch onto baryta paper and dried.

After exposure of the coating through a negative image to 1.14 meter candle seconds of tungsten light, the paper was developed for 13 seconds by the method of Example 1 to give a black and white positive of density 1.66 and contrast 1.84.

EXAMPLE ll 5 diethylamino 4 hydroxy-2,6,-bis methylthiol,3, 3a,7-tetraazaindene (1.56 g.) and sodium hydroxide (0.2 g.) were dissolved in water ml.). This solution was stirred, warmed to 45 C., and 10% gelatin solution (35 ml.) was added. 0.5 M silver nitrate solution (10 ml.) was added slowly with efficient stirring and after stirring for 10 minutes, 0.5 M potassium bromide/ iodide solution containing 3% iodide (1.0 ml.) was added slowly. After stirring for a further 10 minutes, 5% chrome alum solution (2 ml.) was added. The resulting emulsion was coated to a wet thickness of 0.003 inch on baryta paper and dried.

After exposure of the coating through a negative to 1.36 10 meter candle seconds of tungsten light the paper was developed for seconds by the method of Example 1 to give a black and white positive of density 1.97 and contrast 1.9.

EXAMPLE 12 4-hydroxy-6-methyl-2-methylthio 5 piperidinomethyl- 1,3,3a,7-tetraazaindene (2.93 g.) and sodium hydroxide (0.4 g.) were dissolved in water (15 ml.). This solution was stirred, warmed to 45 C., and 10% gelatin solution ml.) was added. 1 M silver nitrate solution (10 ml.) was added slowly with efiicient stirring, and after stirring for 10 minutes 1 M potassium bromide/iodide solution containing 3% iodide (1.0 ml.) was added slowly. After stirring for a further 10' minutes, 5% chrome alum solu tion (2 ml.) was added and the emulsion so prepared was coated at a wet thickness of 0.03 inch on baryta. paper and dried.

After exposure of the coating through a negative to 1.136 10 meter candle seconds of tungsten light, the paper was developed for 20 seconds by the method of EX- ample 1 to yield a black and white positive of density 1.56 and contrast 1.5.

EXAMPLE 13 4 hydroxy-S-hydroxyethylethylaminomethyl-6-methyl- 1,3,3a,7-tetraazaindene (2.51 g.) and sodium hydroxide (0.35 g.) were dissolved in water (15 ml.) This solution was stirred, warmed to C., and 10% gelatin solution (35 ml.) was added. 1 M silver nitrate solution (10 ml.) was added slowly with efficient stirring and after stirring for 10 minutes 1 M potassium bromide/iodide solution containing 3% iodide (1.0 ml.) was added slowly. After stirring for a further 10 minutes, 5% chrome alum solution (2 ml.) was added and the emulsion so prepared was coated at a wet thickness of 0.003 inch on baryta paper and dried.

After exposure of the coating through a negative to 1.137 10 meter candle seconds of tungsten light, the paper was developed for 45 seconds by the method of Example 1 to yield a black and white positiveof density 1.3 and contrast 0.75.

EXAMPLE 14 S-diethylaminomethyl-4-hydroxy 2 methylthio-l,3,3a, 7-tetraazaindene (2.67 g.) was dissolved in water (15 ml.). This solution was stirred, warmed to 45 C., and 10% gelatin solution (35 ml.) was added. 1 M silver'nitrate solution (10 ml.) was added slowly with efficient stirring and after stirring for 10 minutes, 1 M potassium bromide/ iodide containing 3% iodide (1.0 ml. was'added slowly. After stirring for a further 10 minutes, 5% chrome alum solution (2 ml.) was added and the emulsion so prepared was coated at a wet thickness of 0.003 inch on baryta paper and dried.

After exposure of the coating through a negative to 1.5l6 l0 meter candle seconds of tungsten light, the paper was developed for 40 seconds by the method of Example 1 to give a black and white positive of density 1.6 and contrast 1.6.

What is claimed:

1. A light-sensitive composition comprising,

a silver salt of a tetraazaindene having the general formula wherein R is a hydrogen atom, an alkyl group, an aralkyl group, or an alkylthio group; R and R are a hydrogen atom, a lower alkyl group, or a substituted alkyl group, or R and R together with the adjacent nitrogen atom form a heterocyclic ring; and Y is a hydrogen atom, an alkyl group, an alkylthio group, an aryl group or an amino group; and an intimately associated portion of a silver halide of amount sufi'icient to provide a weight ratio of silver in the silver halide to silver in the light-sensitive composition of from 0.001/ 1 to 0.5/ 1. 2. The composition of claim 1 wherein said weight ratio is not greater than about 0.1/1.

3. The composition of claim 1 additionally comprising a water-soluble binder.

4. The composition of claim 3 wherein said binder is gelatin.

5. The composition of claim 3 wherein said binder is polyvinylalcohol.

6. The composition of claim 1 additionally comprising a spectral sensitizer for silver halide.

-7. A photographic element comprising a base and at least one layer having a light-sensitive composition comprising a silver salt of a tetraazaindene having the general formula:

Y /NGH2 N\N/ R2 wherein R is a hydrogen atom, an alkyl group, an

aralkyl group, or an alkylthio group; R and R are a hydrogen atom, a lower alkyl group, or a substituted alkyl group, or R and R together with the adjacent nitrogen atom form a heterocyclic ring; and Y is a hydrogen atom, an alkyl group, an alkylthio group, an aryl group or an amino group; and an intimately associated portion of a silver salide such that the weight ratio of silver in the silver halide to silver in the light-sensitive composition is from 0.001/1 to 0. 5/ 1. 8. The photographic element of claim 7 wherein said weight ratio is not greater than about 0.1/1.

9. The photographic element of claim 7 wherein said at least one layer additionally comprises a water-soluble binder.

10. The photographic element of claim 7 additionally comprising a spectral sensitizer for silver halide.

11. The photographic element of claim 9 wherein said spectral sensitizer is a cyanine or merocyanine dye.

12. The photographic element of claim 7 additionally comprising a layer containing a developer for silver halide.

13. The photographic element of claim 12 wherein said developer is hydroquinone.

14. Method of producing a photographic element comprising reacting in aqueous media a tetraazaindene having the 16. The method of claim 15 wherein said developer is general formula a hydroquinone developer.

N N 17. A photographic image reproduction produced from El R Y Y the photographic element of claim 7. N-CH2 5 References Cited R2 H UNITED STATES PATENTS 2,835,581 5/1958 Tinker et al 96-107 wherein R is a hydrogen atom, an alkyl group, an 3 418 130 12/1968 Stevens et a1 aralkyl group, or an alkylthio group with from 0.5 to 10 3462272 8/1969 Duflin et a1 1.5 molecular equivalents of a water-soluble silver 3375114 8/1968 Hayakawa 5 96 94 salt; R and R are a hydrogen atom, a lower alkyl 3519426 7/1970 Halwig group, or a substituted alkyl group, or R and R together with the adjacent nitrogen atom form a hetero- FOREIGN PATENTS cyclic ring; and Y is a hydrogen atom, an alkyl group, 15 751,867 1/1967 Canada 9 6-109 an alkylthio group, an aryl group or an amino group; 1,054,344 1/19'67 Great Britain 96-109 to form the silver salt of said tetraazaindene; and spreading the resulting media onto a substrate contain- NORMAN G, TORCIflN, P i E i ing soluble halide therein such that at least a portion of said halide is leached from said substrate by said 20 KELLY Asslstant Examiner media to form silver halide therewithin. U S C1 X R 15. The method of claim 14 additionally comprising spreading onto said resulting media on said substrate a 114-7, 117-34 developer for silver halide.

ENE- EE S AT KATENT @F ifiE QERTE F Q @EF Patent No. 3 689,27O Dated Segtember 5, 1972 Inventor 3 George De Winter Anderson and Ronald E. Watts It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 4, Example 3, line 5,, "0,05" should be --o.oo5--;

Column 7, Example 12, line 39, 0.03" should be -0.003--;

Column 8, line +8,

R R N N R R N N Y Y should be k Y Y m-cll k l /N-CH R R s OH Column 8, line 57 "salide" should be -halide-.

Signed and sealed this ZQth-day of May 1973.

(SEAL) Attest:

EDWARD M.PLETCHER,JR ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents FORM PO-105O (10-69) USCOMM-DC 60376-1 69 .J,' U.S. GOVERNMENT PRINTING OFFICE: 1969 0-366-334