US3573916A - Method for preparing color elements providing mottle-free dye images - Google Patents

Abstract

MOTTLING OF DYE IMAGES IN COLOR COUPLER-BEARING SILVER HALIDE EMULSIONS WHICH HAVE BEEN COATED ON ELECTRON BOMBARDED HYDROPHOBIC SURFACES WITHIN ABOUT 30 MINUTES AFTER BOMBARDMENT IS SUBSTANTIALLY ELIMINATED BY USING SULFO-SUBSTITUTED CYANINE OR MEROCYANINE SPECTRAL SENSITIZING DYES.

Description

United States Patent ABSTRACT OF THE DISCLOSURE Mottling of dye images in color coupler-bearing silver halide emulsions which have been coated on electron bombarded hydrophobic surfaces within about 30 minutes after bombardment is substantially eliminated by using sulfo-substituted cyanine or merocyanine spectral sensitizing dyes.

This invention relates to a method for preparing photographic elements, and more particularly to a method for preparing spectrally sensitized photographic elements which are coated on hydrophobic surfaces.

It is well known that photographic silver halide emulsions can be coated on supports having a hydrophobic surface. One highly useful photographic support is polyolefin coated paper, the polyolefin being the hydrophobic surface. Such supports offer considerable advantages over prior art paper supports in that the polyolefin acts as an emcient barrier between the emulsion and various contaminants or materials which can be contained in the paper. The polyolefin prohibits such contaminants from exerting adverse effects on the emulsion. In addition, paper supports which have polyolefin coatings on both sides are effectively waterproofed.

Photographic substrates having a hydrophobic surface, such as a polyolefin surface, require some treatment in order to obtain suflicient adhesion between the hydrophobic surface and the photographic silver halide emulsion. One of the most convenient techniques for obtaining sufficient adhesion is to electron bombard the hydrophobic surface. Electron bombardment is also known as corona discharge treatment. Processes for electron bombarding hydrophobic surfaces are described in Alsup and Venor British Patents 971,058 and 1,060,526 (polyolefin surfaces); Carroll et al. US. Patent 3,220,842, issued Nov. 30, 1965 [poly(ethy1ene terephthalate)]; and Crawford et al. US. Patent 3,117,865, issued Jan. 14, 1964 (paper coated with chromium halide complex, such as sterato chromic chloride).

The use of electron bombarded hydrophobic surfaces for photographic silver halide emulsions containing a color former has presented a problem in color photoggraphy. Spectrally sensitized silved halide emulsions containing color former coated on a hydrophobic surface which has been electron bombarded have produced mottled dye images.

The problem of dye mottle with silver halide emulsions containing color former which are coated on electron bombarded hydrophobic surfaces appears to be most severe for a short period of time, such as up to about one hour, after electron bombardment. Mottle is not as severe if spectrally sensitized emulsions containing color former are coated on the electron bombarded hydrophobic surface a considerable time (e.g., 24 to 36 hours) after the electron bombardment treatment. Although a holding period avoids mottle, it introduces serious disadvantages in manufacturing operations. Thus, the support must be stored after electron bombardment for asutficient time to avoid mottle, but the emulsion must be coated on the support within about 24 to 36 hours after electron bombardment to obtain adequate emulsion adhesion.

3,573,915 Patented Apr. 6, 1971 There is a need, therefore, for a process whereby spectrally sensitized photographic silver halide emulsions containing color former can be coated on a hydrophobic surface substantially immediately after the surface has been electron bombarded.

One object of this invention is to provide a novel process for preparing light sensitive photographic elements.

Another object of this invention is to provide a novel process for preparing light sensitive photographic elements which have a Spectrally sensitized photographic silver halide emulsion layer containing color former coated on an electron bombarded hydrophobic surface.

A further object of this invention is to provide a method for coating spectrally sensitized silver halide emulsions containing color former on an electron bombarded hydrophobic surface whereby mottle-free dye images can be obtained.

Still another object of this invention is to provide a method for coating spectrally sensitized light sensitive silver halide emulsions containing color former onto an electron bombarded hydrophobic surface without undue photographic speed loss.

Other objects of this invention will be apparent from the disclosure herein and the appended claims.

These and other objects of the present invention are accomplished by the method for preparing light sensitive photographic elements which comprises:

(1) Spectrally sensitizing alight sensitive photographic silver halide emulsion with a methine dye having at least one sulfo group;

(2) incorporating photographic color-former in said emulsion;

(3) electron bombarding a hydrophobic surface to provide good adhesion for said emulsion; and,

(4) coating said emulsion onto said hydrophobic surface substantially immediately after said electron bombarding treatment.

Spectral sensitization of photographic silver halide emulsions with a sulfo substituted methine dye allows the preparation of photographic elements by coating an emulsion containing color former onto a hydrophobic surface substantially immediately after it has been electron bombarded. Photographic elements prepared in accordance with this invention are free from mottle.

The process of this invention can be carried out by Spectrally sensitizing photographic silver halide emulsions with a methine dye of the type used to Spectrally sensitize silver halide emulsions, which methine dye contains a sulfo group.

One particularly useful class of methine dyes which can be employed in the process of this invention are the sulfo-substituted cyanine dyes. As used herein and in the appended claims, the term cyanine includes simple cyanine dyes and higher homologs, e.g., carbocyanine, dicarbocyanine and tricarbocyanine dyes. As is well known, cyanine dyes feature the amidinium-ion chromophore system. In cyanine dyes, each nitrogen atom of the amidinium-ion system is contained in a heterocyclic ring. See Mees and James, The Theory of Photographic Process, third edition, 1966, at pages 201 and 202. Any cyanine dye containing a sulfo group can be used in the practice of this invention. The most useful cyanine dyes are those wherein at least one of the nitrogen atoms of the amidinium-ion system in the dye contains a sulfoalkyl group, such as sulfomethyl, sulfopropyl, sulfobutyl, etc. A highly useful class of sulfoalkyl substituted cyanine dyes is represented in Formula I below:

, --Z R1- N(=OHCH)d 1=CL =(L L;) 1=C(CH=CH) 1-'N-R In the above formula, Z and Z each represents the nonmetallic atoms required to complete a heterocyclic nucleus of the type used in cyanine dyes, typically containing from to 6 atoms in the heterocyclic ring, which ring can contain a second hetero atom such as oxygen, sulfur, selenium or a second nitrogen atom, such as quaternary salts formed from nuclei of the thiazole series (e.g., thiazole, 4-methylthiazole, 4-phenylthiazole, 5-methylthiazole, S-phenylthiazole, 4,5-dimethylthiazole, 4,5-di phenylthiazole, 4-(2-thienyl)-thiazole, benzothiazole, 4- chlorobenzothiazole, 5-ehlorobenzothiazole, 6-chlorobenzothiazole, 7-chlorobenz0thiazole, 4-methylbenzothiazole, 5-methylbenzothiazole, 6-methylbenzothiazole, 5-bromobenzothiazole, 6-bromobenzothiazole, 4-phenylbenzothiazole, 5-phenylbenzothiazole, 4-rnethoxybenzothiazole, 5- methoxybenzothiazole, 6-methoxybenzothiazole, 5 -iodobenzothiazole, 6 iodobenzothiazole, 4 ethoxybenzothiazole, S-ethoxybenzothiazole, tetrahydrobenzothiazole, 5,6- dimethoxybenzothiazole, 5,6 dioxymethylenebenzothiazole, 5 hydroxybenzothiazole, 6 hydroxybenzothiazole, naphtho[1,2]thiazole, naphtho[2,1]thiazole, 5 methoxynaphtho[2,1]thiazole, 5 -ethoxynaphtho[2,1]thiazole, 8- methoxynaphtho[1,2]thiazole, 7 methoxynaphtho[1,2] thiazole, 4-methoxythianaphtheno-7',6',4,5-thiazole, etc., those of the oxazole series (e.g., 4-methyloxazole, S-methyloxazole, 4-phenyloxazole, 4,5-diphenyloxazole, 4-ethy1- oxazole, 4,5-dimethyloxazole, S-phenyloxazole, benzoxazole, 5-chlorobenzoxazole, 5-methylbenzoxazole, 5-phenylbenzoxazole, 6-methylbenzoxazole, 5,6-dimethylbenzoxazole, 4,6-dimethylbenzoxazole, 5-methoxybenzoxazole, 5- ethoxybenzoxazole, 5 chlorobenzoxazole, 6 methoxybenzoxazole, S-hydroxybenzoxazole, 6 hydroxybenzoxazole, naphtho[1,2]oxazole, naphtho[2,1]oxazole, etc.), those of the selenazole series (e.g., 4-methylselenazole, 4- phenylselenazole, benzoselenazole, 5 chlorobenzoselenazole, S-methoxybenzoselenazole, 5 -hydroxybenzoselenazole, tetrahydrobenzoselenazole, naphtho[1,2]selenazole, naphtho[2,1]selenazole, etc.), those of the thiazoline series (e.g., thiazoline, 4-methylthiazoline, etc.), those of the quinoline series such as Z-quinoline (e.g., quinoline, 3- methylquinoline, S-methylquinoline, 7-methylquinoline, 8- methylquinoline, 6-chloroquinoline, 8-chloroquinoline, 6- methoxyquinoline, 6-ethoxyquinoline, 6-hydroxyquinoline, 8-hydroxyquinoline, etc.), 4-quinoline (e.g., quinoline, 6- methoxyquinoline, 7-methylquinoline, 8-methylquinoline, etc.), l-isoquinoline (e.g., isoquinoline, 3,4-dihydroisoquinoline, etc.), 3-isoquinoline (e.g., isoquinoline, etc.), and those of the :benzimidazole series (e.g., 1,3-diethylbenzimidazole, 1,3-diethy1-5-chlorobenzimidazole, 1,3-diethyl-5,6-dichlorobenzimidazole, 1-ethyl-3-phenylbenzimidazole, etc.), L L and L each represents a methine group such as etc.; R and R each represents an alkyl group, including substituted alkyl (preferably a lower alkyl containing from 1 to 4 carbon atoms), e.g., methyl, ethyl, propyl, isopropyl, butyl, hexyl, cyclohexyl, decyl, dodecyl, etc, and substituted alkyl groups (preferably a substittued lower alkyl containing from 1 to 4 carbon atoms), such as a hyd roxyalkyl group, e.g., 2-hydroxyethyl, 4-hydroxybutyl, etc., an alkoxyalkyl group, e.g., 2-rnethoxyethyl, 4- butoxybutyl, etc., a sulfoalkyl group, e.g., 2-sulfoethyl, 2- sulfopropyl, 3 sulfopropyl, 2-sulfobutyl, 3-sulfobutyl, 4- sulfobutyl, 6- sulfohexyl, etc; an acyloxyalkyl group, e.g., ,B-acetoxyethyl, 'y-acetoxypropyl, w-butyryloxybutyl, etc., an alkoxyearbonylalkyl group, e.g., fl-methoxycarbonylethyl, w-ethoxycarbonylbutyl, etc., an aralkyl group, e.g., benzyl, phenethyl, etc., or an aryl group, e.g., phenyl, tolyl, naphthyl, methoxyphenyl, chlorophenyl, etc.; sulfoalkoxyalkyl groups such as those described in Brooker and Keyes U.S. Pat. 3,352,857, issued Nov. 14, 1967,

e.g., 3 (sulfopropoxy)ethyl, (4 sulfobutoxy)ethyl, and (3-sulfobutoxy)propyl, at least one of Z, Z R and R including a sulfo group; at and e each represents an integer of from 1 to 2; n represents an integer of from 1 to 3; and X represents an acid anion, which can be a sulfo group combined with R or R or an acid anion such as chloride, bromide, iodide, thiocyanate, sulfonate, perchlorate, p-toluenesulfonate, methyl sulfate, ethyl sulfate and so forth. Preferably, at least one of R and R represents a sulfoalkyl group, the alkyl group advantageously containing from 1 to 4 carbon atoms. Especially useful are the N-sulfoalkyl substituted cyanine dyes containing a benzoxazole nucleus, the N,N'-disulfoalky1 substituted oxacarbocyanines being particularly useful.

A large number of typical useful sulfo substituted cyanine dyes are described in Sprague U.S. Patent 2,503,776 issued Apr. 11, 1950 and the sulfoalkyl substituted benzimidazole carbocyanine dyes described in Jones and Spence U.S. Patent 2,912,329, issued November 10, 1959. Representative useful nuclear sulfo-substituted cyanine dyes are described in Heseltine U.S. Patent 3,148,187, issued Sept. 8, 1964. The disclosure of the foregoing patents are included herein by reference. The following are typical specific dyes which can be used in the practice of this invention:

Anhydro 5 chloro-9-ethyl-5-phenyl-3'-(3-sulfobutyl)- 3-(3 sulfopropyl)oxacarbocyanine hydroxide, sodium salt Anhydro 9 ethyl-5,5'-diphenyl-3,3'-di(3-sulfobutyl)- oxacarbocyanine hydroxide, monosodium salt Anhydro 5,5 dichloro-9-ethyl-3,3-di(3-sulfopropyl)- oxacarbocyanine hydroxide, monosodium salt Anhydro 5,5',6,6' tetrachloro-1,1diethyl 3,3'-di(3- su-lfobutyl)benzimidazolocarbocyanine hydroxide Anhydro 5,5',6,6' tetrachloro-1,1',3-triethyl-3'-(3-sulfobutyl)benzimidazolocarbocyanine hydroxide Anhydro 5,6 dichloro-1,3'-diethyl-3-(3-sulfopropyl)- benzimidazolooxacarbocyanine hydroxide Anhydro-5,5dichloro 3,3 di(3-sulfopropyl)thiadicarbocyanine hydroxide, monosodium salt Anhydro 9 ethyl-5,5'-diphenyl-3,3'-di(3-sulfobutyl)- selenacarbocyanine hydroxide, monosodium salt Anhydro-S-chloro 9 ethyl-5'-pheny1-3'-(3-sulfobutyl)- 3-(3-sulfopropyl)thiacarbocyanine hydroxide, sodium salt Anhydro 5,5 dichloro-3,3-di(3 sulfopropyl)oxacy anine hydroxide, monosodium salt Anhydro 1' ethyl-3-fl-sulfoethylthia 2' cyanine hydroxide Anhydro 3 ethyl-4'-methyl-3-(3-sulfobutyl)oxathiazolocarbocyanine hydroxide Anhydro 3,3 diethyl-9-methyl-4,5,4,5'-dibenzothiacarbocyanine hydroxide, disulfonated Anhydro 3,3',9-triethyl-5,5'-di(p-sulfophenyl)oxacarbocyanine hydroxide Sulfo substituted methine dyes containing the amidic chromophoric system (see Mees and James, supra, page 201) can also be used in the practice of this invention. Methine dyes having the amidic chromophore system are referred to herein, and in the art, as merocyanine dyes. Any mercocyanine dye containing a sulfo group can be employed in the practice of this invention.

A preferred class of merocyanine dyes which is employed in the method of this invention is shown in Formula II below:

wherein Z has a meaning selected from those given for Z, and Z above, R represents an alkyl or aryl group selected from those described for R and R above; L and L each represents a methine group as described for L -L above; a represents an integer of from 1 to 2; m represents an integer of from 1 to 3; and Q represents the non-metallic atoms required to complete a to 6 membered heterocyclic nucleus of the type used in merocyanine dyes, typically containing a hetero atom selected from nitrogen, sulfur and oxygen, such as a 2-pyrazolin-5-one nucleus, e.g., 1-phenyl-3-(2-sulfopropyl)-2-pyrazolin-5-one, 1-(4- sulfophenyl)-2-pyrazolin-5-one, etc., an isoxazolone nucleus (e.g., 3-(4-sulfophenyl)-5(4H)-isoxazolone, 3-(4- sulfobutyl)-5-(4H)-isoxazolone, etc.); an oxindole nucleus (e.g., l-x-sulfoalkyl)-2,3-dihydro-2-oxindoles, etc.), a 2,4,6-triketohexahydropyrimidine nucleus (e.g., barbituric acid or 2-thiobarbituric acid having a sulfoalkyl group, e.g., 1-(2-sulfoethyl); 1-(3-sulfopropyl); 1-(4-sulfoheptyl); etc. or a l,3-di(sulfoall yl group e.g., 1,3-di- (2 sulfoethyl); 1,3-di-(3-sulfopropyl); l,3-di-(4-sulfocy clohexyl); [(4-sulfobutoxy)ethyl], etc., or 1,3-di-(sulfoaryl); e.g., 1,3-di-(4-sulfophenyl); etc., or l-sulfoaryl, e.g., l-(4-sulfophenyl); etc.; a sulfo-substituted rhodanine nucleus (i.e., Z-thio-2,4-thiazolidinedione series), such as 3- sulfoalkylrhodanines, e.g., 3-(2-sulfoethyl)rhodanine. 3- (3-sulfopropyl)rhodanine, 3 (4- sulfobutyDrhodanine, etc), or 3-sulfoarylrhodanines e.g., 3 (4-sulfophenyl) rhodanine, etc; a 2-thio-2,4-oxazolidinedione nucleus (i.e., those of the 2-thio-2,4(3H,5H)-oxazoledione series; e.g., 3-(2-sulfoethyl)-2-thio-2,4-oxazolidinedione, 3 (4-sulfobutyl)-2-thio-2,4-oxazolidinedione; a 2,4-thiazolidinedione nucleus e.g., 3 (4-sulfophenyl)-2,4-thiazolidinedione; a thiazolidinone nucleus e.g., 3-(2-sulfoethyl)-4-thiazolidinone, 3-(4-sulfophenyl)-4-thiazolidinone; a 2,4-imidazolidinedione (hydantoin) series e.g., 3-(2-sulfoethyl)-2,4- imidazolidinedione, 3-(4 sulfophenyl)2,4-imidazolidincdione; a 2thio-2,4-imidazolidinedione (i.e., 2-thiohydantoin) nucleus e.g., 3-(Z-sulfopropyl)-2-thio-2,4-imidazo lidinedione, 3-(4-sulfobutyl) 2 thio-2,4-imidazolidinedione, a 2-imidazolin-5-one nucleus (e.g., 2-(3-sulfopropyl)-2-imidazolin-5-one, etc.), etc. or any other ketomethylene nucleus of the type used in merocyanine dyes, at least one of Q, Z and R containing a sulfo group. Especially useful are nuclei wherein Q represents a sulfosubstituted heterocyclic nucleus containing 5 atoms in the heterocyclic ring, 3 of said atoms being carbon atoms, 1 of said atoms being a nitrogen atom, and 1 of said atoms being selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom. Preferred merocyanine dyes are those in which Q includes a heterocyclic nitrogen atom which has attached thereto a sulfoalkyl (preferably alkyl groups of from 1 to 4 carbon atoms) or a sulfoaryl group, such as a psulfophenyl group.

Specific useful merocyanine dyes of this invention include the following:

5- 3-ethyl-2(3 -bcnzothiazolylidene) -3-,8-sulfoethylrhodanine 5- l-buty1-4 1 quinolylidene) -3 -,8-sulfoethylrhodanine 5- (3-methyl-2 3 -thiazolinylidene) isopropylidene] 3 -fi-sulfoethylrhodanine 5- [(3 -ethyl-2(3)-benzoxazolylidene)ethylidene] 3 8- sulfoethyl rhodanine 5- (3 -ethyl-2 (3 benzoxazolylidene) ethylidene] -3-5- sulfoethyl-2-thio-2,4( 3 ,5 -oxazoledione 5- 3-ethyl-2 3 )-benzothiazolyidene) isopropydilene]- 3 -fl-sulfoethyl-2-thio-2,4 (3 ,5) -oxazoledione 5- (3 -ethyl-2 3 -benzoxazolylidene ethylidene] -3- 'sulfomethyl-2-thio-2,4 3 ,5 -oxazoledione 1-sulfomethyl-5-[ 3-ethyl-2 (3 )-benzoxazolylidene) ethylidene] -3-phenyl-2-thiohydantoin 5- (3 -ethyl-2 3 -benzothiazolylidene -2-butenylidene] 3-sulfoethyl rhodanine 4-[ 3-ethyl-2 (3H) -benzoxazolylidene) ethylidene] -3 methyl- 1- (p-sulfophenyl -2-pyrazolin-5-one, monosulfonated 4- [4- (3 -ethyl-2 3H) -benzoxazo1ylidene) -2-butenyl idene] -3-methyl-1- (p-sulfophenyl) -2-pyrazolin-5-one, monosulfonated 5-{ [5,6-dichloro-1-ethyl-3- (4-sulfobutyl)2-benzimidazolinylidene] ethylidene}-1,3 -diethy1-2-thiobarbituric acid, sodium salt 4-[ (3-ethyl-2 3H) -b enzoxazolylidene) ethylidene] -3- methyl1-p-sulfophenyl-2-pyrazolin-5-one, monosulfonated 4 [4-( 3-ethyl-2 (3H) -benzoxazolylidene) -2-butenyl-.

idene1-3-methyl-l-p-sulfophenyl-2-pyrazolin-5-one, monosulfonated In accordance with this invention, photographic silver halide emulsions containing color former are coated on hydrophobic surfaces. As used herein, the term color formers includes any of those compounds which react or couple with the oxidation product of primary aromatic amino developing agents (e.g., a paraphenylenediamine) on photographic color development to form a dye, and are non-diffusible in photographic silver halide emulsions. Typical useful color for-mers include phenolic, S-pyrazolone, and open chain ketomethylene compounds, such as those described and referred to in US. Patents 2,322,027 and 2,801,171. Typical useful couplers producing cyan images which can be used herein are described by Graham et al. US. Patent 3,046,129 issued July 24, 1962 at 001$. 15 and 16. Typical couplers producing magenta images which can be used in this invention are described by Graham et al., supra, col. l1. Couplers typical of those which can be used in this invention to produce yellow images are described by Graham et al., supra, Cols. 17 and 18. Such color formers can be dispersed in any suitable coupler solvent such as one of those described in many of the following US. patents: 2,304,939; 2,322,027; 2,801,170; 2,801,171 and 2,949,360.

The photographic silver halide emulsions utilized in the processes hereof are preferably spectrally sensitized first with a dye of the type described herein, and then photographic color former is added to the emulsion. However, the order of addition of spectral sensitizer and then color former to the emulsion is not essential to the practice of this invention.

The present invention is practiced by coating spectrally sensitized photographic silver halide emulsions containing color former onto a hydrophobic surface which has been subjected to corona discharge. The term hydrophobic is used herein in its normal sense as inclusive of substances which do not absorb or adsorb water. Typical hydroprobic surfaceswhich are advantageously electron bombarded includes any hydrophobic materials which can be electron bombarded to improve adhesion, such as continuous hydrophobic films (which may or may not be self supporting) that have an ionizable hydrogen or hydroxyl group. Specific supports having hydrophobic surfaces that can be utilized in the practice of this invention include electron bombarded poly(ethylene terephthalate) films, such as those electron bombarded to have a contact angle less than 45, by the process described in Carroll et al. US. Patent 3,220,842, issued Nov. 30, 1965 (which disclosure is incorporated herein by reference); electron bombarded surfaces comprising a chromium halide complex, such as sterato chromic chloride, for example those which are electron bombarded by the process described by Crawford et al. US. Patent 3,117,865 issued Jan. 14, 1964 (which disclosure is incorporated herein by reference); and, electron bombarded hardened gelatin coatings, such as hardened gelatin coated papers, e.g., by the process described by Crawford and Venor US. patent application Ser. No. 411,059 filed Nov. 13, 1964, now US. Patent No. 3,411,910, Nov. 19, 1968 and corresponding Belgian Patent 671,661, Nov. 15, 1965 (which disclosure is incorporated herein by reference). Other hydrophobic surfaces which can be electron bombarded for use in the present invention, using processes and apparatus similar to that described in the literature referred to herein, include poly-u-olefins, preferably derived from olefins having from 2 to 10 carbon atoms; polyamides; polyacetals, polycarbonates; and, cellulose esters and ethers such as cellulose triacetate, cellulose acetate butyrate, ethyl cellulose, etc.

The preferred hydrophobic surfaces utilized in the practice of this invention are polyolefins, polyethylene and polypropylene being especially useful. The support can be composed exclusively of polyolefin. That is, self supporting polyolefin films can be electron bombarded and coated substantially immediately after electron bombardment with spectrally sensitized photographic silver halide emulsions containing color former, in accordance With this invention. The invention can also be practiced when the polyolefin surface is a permanent support for the photographic emulsion, the polyolefin support being removably adhered to a suitable temporary support to form a stripping film of the type described by Goffe et al. U.S. Patent 3,359,107, issued Dec. 19', 1967. Other polyolefin coated supports can also be utilized, such as polyethylene or polypropylene coated paper supports.

The polyolefin surface can be electron bombarded by any convenient method, such as that by Alsup and Venor in British Patents 971,058 and 1,060,526. As noted in those patents, any suitable corona discharge or electron bombardment apparatus can be employed, such as the apparatus disclosed in U.S. Patents 2,864,755 and 2,864,- 756. When the surface is polyethylene, it is desirable to subject the polyolefin surface to sufficient corona discharge or electron bombardment to obtain a contact angle of less than about 75. A contact angle of less than about 54 is desirable when the polyolefin utilized is polypropylene. The method for obtaining and determining the contact angle of the corona discharge treated surface is described by Alsup and Venor in British Patent 971,058

and by TAPPI (Technical Association of the Pulp and Paper Industry) specification T458M-59.

When a paper support is used and a hydrophobic film is coated thereover, it is advantageous to incorporate an antistatic agent in just the paper, as described in Chu et al. U.S. Patent 3,253,922, issued May 31, 1966.

This invention is practiced by coating spectrally sensitized emulsions containing color former onto a hydrophobic surface substantially immediately after the hydrophobic surface has been subjected to corona discharge treatment. As used herein and in the appended claims, substantially immediately after corona discharge treatment refers to a period within about 30 minutes, and is advantageously within a few seconds (from less than one second up to about 30 seconds) after the corona discharge treatment. In the preferred mode of carrying out this invention, a web having a hydrophobic surface is continuously passed by a first station where the hydrophobic surface is electron bombarded, and then to a second station where a spectrally sensitized emulsion containing color-former is coated onto the electron bombarded hydrophobic surface. Utilizing such techniques, the interval between electron bombardment and coating the emulsion is generally less than a few seconds, and can be a fraction of a second, depending upon the speed selected for operation.

This invention may be satisfactorily utilized when a spectrally sensitized emulsion containing color former is coated as a single layer upon a support of the type described herein, or when a plurality of emulsion coatings are applied to such support. When a plurality of coatings are applied to the support, suitable multiple coating techniques of the type heretofore utilized in photographic processes can be employed. When multiple emulsion coatings are applied over a corona discharge treated hydrophobic surface, the most serious problems of mottle appear in the two emulsion layers closest the hydrophobic surface. The problem of mottle has generally not been too severe with emulsions coated further from the support than two emulsion layers.

The present invention is especially well suited to the preparation of multicolor photographic elements having light sensitive layers of the general type described in Knott et al. Belgian Patent 641,414, issued Jan. 16, 1964, and corresponding U.S. Patent No. 3,434,837 issued Mar. 25, 1969. Thus, a support having a hydrophobic surface, such as a polyethylene or polypropylene coated paper support, can have coated thereon, in the following order, a blue sensitive photographic silver halide emulsion layer containing a yellow coupler, an optional interlayer comprising a hydrophilic colloid such as gelatin; a green sensitive photographic silver halide emulsion layer containing a magenta coupler; an optional hydrophillic colloid layer such as gelatin; and, a red sensitive photographic silver halide emulsion layer containing a cyan coupler. When such photographic silver halide emulsions are coated on an electron bombarded hydrophobic surface, mottle is most severe in the magenta dye image produced by green sensitive silver halide emulsion layer. When the blue sensitive layer contains a spectral sensitizer other than one of the type described herein, mottle is severe in the yellow dye image. In the arrangement just described, the cyan dye image formed by the red sensitive layer does not appear to be seriously susceptible to mottle. When a similar multicolor element is desired but the red sensitive emulsion layer is coated adjacent the polyolefin surface, with the green and blue sensitive emulsion layers thereover, the most serious mottle appears in the cyan and magenta dye images produced by the spectrally sensitized red and green sensitive emulsions.

The term mottle is used herein as a word of art which describes a defect occurring when a light sensitive silver halide emulsion layer containing color former is subjected to an overall even exposure, color developed to provide a dye image, and the dye image, which should have even dye density throughout, instead exhibits finger or lightning marks which are areas having distinctly higher dye density than that of the remaining areas of the dye image. The areas having the higher dye density exhibit greater density than would be expected or predicted from the photographic speed of the particular system. Mottle is also frequently accompanied by a lower speed than would be predicted in areas outside the finger or lightning marks. Frequently, the speed loss is about .1 Log E over that which would be predicted from the results obtained with a mottle free element corresponding to the test element.

The following examples are included for a further understanding of the invention.

EXAMPLE 1 A photographic silver bromoiodide emulsion is spectrally sensitized with 149 mg. per mole of silver of the dye anhydro-5-chloro-9-ethyl-5 -phenyl-3 3-sulfobutyl) 3-(3-sulfopropyl)oxacarbocyanine hydroxide, sodium salt. A coupler is added to form a magenta image, the coupler being a pyrazolone coupler of the type described in Loria et al. U.S. Patent 2,600,788, dated June 17, 1952 (e.g., 3- {3 2",4"-di-tert-amylphenoxy) acetamido benzoamido}- 1-(2,4,6-trichlorophenyl)-5-pyrazolone), dissolved in a suitable coupler solvent, such as dibutyl phthalate. A polyethylene coated paper support is electron bombarded with a corona discharge by the process described in Alsup and Venor British Patent 971,058, the polyethylene surface passing the corona discharge station at the rate of about 500 feet per minute. The polyethylene has a contact angle of less than 76. At a station situated just beyond the corona discharge apparatus, the spectrally sensitized silver chlorobromide gelatin emulsion containing magenta coupler is coated onto the support, at a concentration of about mg. silver per square foot, about mg. gelatin per square foot and about 65 mg. coupler per square foot. The emulsion passes the coater at the same rate it is passing by the corona discharge apparatus. The coated sample is chill set, dried and processed exactly as described in Col. 5, line 40 through Col. 6, line 44 of Van Campen U.S. Patent 2,956,879. The coating is then exposed to green radiation, i.e., radiation of about 500-600 nm. The dye image is free from mottle. Similar results are obtained when the polyethylene coated support is replaced with polypropylene coated paper, the polypropylene being electron bombarded to provide a contact angle of less than about 54 as described by Alsup and Venor in British Patent 1,060,526; or by a hardened gelatin coated paper electron bombarded as described by Crawford and Venor in Belgian Patent 671,661; or sterato chromic chloride coated paper electron bombarded as described by Crawford and Venor in US. Patent 3,117,865; or, poly(ethylene)terephthalate electron bombarded as described by Carroll and Chapman in US. Patent 3,220,- 842.

EXAMPLE 2 The procedure of Example 1 is duplicated except that the emulsion is spectrally sensitized with 162 mg. per mole of silver of the dye anhydro-9-ethyl-5,5'-diphenyl- 3,3-di(3-sulfobutyl)-oxacarbocyanine hydroxide, monosodium salt. The sample obtained is tested exactly as described in Example 1. The magenta dye image is free from mottle.

EXAMPLE 3 The procedure of Example 1 is duplicated except that the emulsion is spectrally sensitized with 157 mg. per mole of silver of the dye anhydro-5,5-dichloro-9-ethy1- 3,3'-di(3-sulfopropyl)-oxacarbocyanine hydroxide, monosodium salt. The sample obtained is tested exactly as described in Example 1. The magenta dye image is free from mottle.

EXAMPLE 4 The procedure of Example 1 is duplicated except that the emulsion is spectrally sensitized With 156 mg. per mole of silver of the dye anhydr-5,5,6,6-tetrachloro-1,1-diethyl 3,3 di(3 sulfobutyl)benzimidazolocarbocyanine hydroxide. The sample obtained is tested exactly as described in Example 1. The magenta dye image is free from mottle.

EXAMPLE 5 The procedure of Example 1 is duplicated except that the emulsion is spectrally sensitized with 137 mg. per mole of silver of the dye anhydro-5,5,6,6-tetrachloro-1,1',3- triethyl 3' (3 sulfobutyl) benzimidazolocarbocyanine hydroxide. The sample obtained is tested exactly as described in Example 1. The magenta dye image is free from mottle.

EXAMPLE 6 The procedure of Example 1 is duplicated except that the emulsion is spectrally sensitized with 114 mg. per mole of silver of the dye anhydro-5,6-dichloro-1,3'-diethyl-3-(3- sulfopropyl) benzimidazolooxacarbocyanine hydroxide. The sample obtained is tested exactly as described in Example 1. The magenta dye image is free from mottle.

EXAMPLE 7 The procedure of Example 1 is duplicated except that the emulsion is spectrally sensitized with 149 mg. per mole of silver of the dye 5-(3-ethyl-2-benzothiazolinylidene)- 3-,8-sulfoethylrhodanine. The sample obtained is tested exactly as described in Example 1. The magenta dye image is free from mottle.

EXAMPLES 814 The procedures of Examples 1-7 are repeated except that the dispersion of pyrazolone coupler is replaced with about 50 mg. per square foot of a cyan forming coupler, e.g., coupler number 1 of Fierke et al. US. Patent 2,801,- 171 (Col. 2) in a conventional coupler solvent such as tri-ocresyl phosphate. The emulsion is coated at about 65 mg. silver per square foot, 50 mg. cyan coupler per square foot and 110 mg. gelatin per square foot. The results obtained in Examples 8-14 are essentially the same as those of Examples 1-7; i.e., the cyan dye images are free from mottle. Similar results are obtained when the polyethylene coated support is replaced with polypropylene coated paper, the polypropylene being electron bombarded to provide a contact angle of less than about 54 as described by Alsup and Venor in British Patent 1,060,526; or by a hardened gelatin coated paper electron bombarded as described by Crawford and Venor in Belgian Patent 671,661; or sterato chromic chloride coated paper electron bombarded as described by Crawford and Venor in US. Patent 3,117,865; or, poly(ethylene) terephthalate electron bom barded as described by Carroll and Chapman in U.S. Patent 3,220,842.

EXAMPLES l5-21 The procedure of Examples 1-7 is repeated except that the pyrazolone coupler dispersion is replaced with a yellow image dye-forming coupler, e.g., coupler No. l of McCrossen et al., US. Pat. 2,875,057, issued Feb. 24, 1959, dispersed in dibutyl phthalate, and the emulsion is coated at about 70 mg. square foot silver, mg. per square foot gelatin and 50 mg. per square foot coupler. The yellow dye images obtained are free from mottle. Similar results are obtained when the polyethylene coated support is replaced with polypropylene coated paper, the polypropylene being electron bombarded to provide a contact angle of less than about 54 as described by Alsup and Venor in British Pat. 1,060,526; or by a hardened gelatin coated paper electron bombarded as described by Crawford and Venor in Belgian Pat. 671,661; or sterato chromic chloride coated paper electron bombarded as described by Crawford and Venor in US. Pat. 3,117,865; or, poly(ethylene)terephthalate electron bombarded as described by Carroll and Chapman in US. Pat. 3,220,842.

Examples 22-28 illustate the severe mottle which occurs when basic dyes, various acid-substituted cyanine and merocyanine dyes are used instead of the sulfo-substituted spectral sensitizing methine dyes utilized in the process of this invention.

EXAMPLE 22 The procedure of Example 1 is repeated except that the emulsion is spectrally sensitized with 31 mg. per mole of silver of the dye 3,3-di(/3-hydroxethyl)thiadicarbocyanine bromide. Severe mottle is readily apparent in the magenta dye image.

EXAMPLE 23 The procedure of Example 1 is repeated except that the emulsion is spectrally sensitized with 139 mg. per mole of silver of the dye 5-[(3-ethyl-2(3H)-naphth[2,1joxazolyidene)ethylidene]-3-n-heptyl-1-phenyl-2 thiohydantoin. Severe mottle is readily apparent in the magenta dye magenta dye image.

EXAMPLE 24 The procedure of Example 1 is repeated except that the emulsion is spectrally sensitized with mg. per mole of silver of the dye 3,3',9-triethyl-5,5-diphenyloxacarbocyanine bromide. Severe mottle is readily apparent in the magneta dye image.

EXAMPLE 25 The procedure of Example 1 is repeated except that the emulsion is spectrally sensitized with 145 mg. per mole of silver of the dye 9-ethyl-3,3-di(}8-methoxyethyl)-5,5- diphenyloxacarbocyanine iodide. Severe mottle is readily apparent in the magenta dye image.

EXAMPLE 26 The procedure of Example 1 is repeated except that the emulsion is spectrally sensitized with 131 mg. per mole of silver of the dye anhydro-3,3-di-(fl-carboxyethyl)-9-ethyl-5,5' diphenyloxacarbocyanine hydroxide. Severe mottle is readily apparent in the magenta dye image.

EXAMPLE 27 The procedure of Example 1 is repeated except that the emulsion is spectrally sensitized with 135 mg. per mole 1 l of silver of the dye 3-ethyl-5-[(3-methyl-2-(3H)-thiazolinylidene -ethylidene] -2-thio-2,4-oxazolidinedione. Severe mottle is readily apparent in the magenta dye image.

EXAMPLE 28 The procedure of Example 1 is repeated except that the emulsion is spectrally sensitized with 135 mg. per mole of silver of the dye 3-carboxymethyl-5-[(3-methyl-2 (3H) thiazolinylidene isopropylidene] rhodanine. Severe mottle is readily apparent in the magenta dye image.

Example 29 illustrates the practice of this invention with overlying blue, green and red sensitive silver halide layers containing, respectively, yellow, magenta and cyan color former.

EXAMPLE 29 A polyethylene coated paper support is electron bombarded to provide a contact angle of less than 75 on the polyethylene surface. Substantially immediately after the electron bombardment, i.e., within seconds after the elec tron bombardment, blue, green and red sensitive silver halide emulsion layers containing, respectively, yellow, magenta, and cyan color formers are simultaneously coated, from a multiple coating hopper, onto the electron bombarded polyolefin surface, the blue sensitive layer containing yellow color former being closest to the electron bombarded polyethylene surface with the green sensitive layer containing magenta coupler over the blue sensitive layer and the red sensitive layer containing cyan color former overlying the green sensitive layer and being furthest from the polyethylene surface. The blue sensitive layer does not contain a spectral sensitizing dye. The yel low image formingcoupler is coupler No. l of McCrossen et al. U.S. Pat. 2,875,057, issued Feb. 24, 1959, dispersed in dibutyl phthalate and coated at a concentration of 115 mg. per square foot gelatin, 70 mg. per square foot silver and 50 mg. per square foot coupler. The green sensitive silver halide emulsion layer is spectrally sensitized with 149 mg. per mole of silver with the dye 5-chloro-9- ethyl-5 -phenyl-3 (3 -sulfobutyl) -3-( 3 sulfopropyl oxacarbocyanine hydroxide, sodium salt. The green sensitive emulsion layer has dispersed therein pyrazole coupler No. 7 of Fierke et al. U.S. Pat. 2,801,171 (Col. 2), dissolved in coupler solvent, such as tri-o-cresyl phosphate. The green sensitive layer is coated at the rate of 165 mg. per square foot gelatin, 95 mg. per square foot silver and 65 mg. per square foot coupler. The red sensitive layer is spectrally sensitized with a conventional sensitizer, such as anhydro-3,3'-di(,8 sulfoethyl)thiadicarbocyanine hydroxide at a concentration of about 130 mg. sensitizing dye per mole of silver. The red sensitive layer contains a dispersion of coupler No. 1 of Fierke et al. U.S. Pat. 2,801,171 (Col. 2) in a coupler solvent, such as tri-o-cresyl phosphate. The red sensitive emulsion layer is coated at the rate of 110 mg. per square foot gelatin, 65 mg. per square foot silver, 50 mg. per square foot cyan coupler. The element is given a color sensitometric exposure and processed as described in Van Campen U.S. Pat. 2,956,879, Col. 5, line 40 through Col. 6, line 44. The yellow, magenta and cyan dye images obtained are free from mottle. No speed loss is observed when the speed of each of the emulsion layers is compared to an element having the same emulsion layers but coated on a baryta coated paper which is not electron bombarded. Similar results are obtained when the polyethylene coated support is replaced with polypropylene coated paper, the polypropylene being electron bombarded to provide a contact angle of less than about 54 as described by Alsup and Venor in British Pat. 1,060,526; or by a hardened gelatin coated paper electron bombarded as described by Crawford and Venor in Belgian Pat. 671,661; or sterato chromic chloride coated paper electron bombarded as described by Crawford and Venor in U.S. Pat. 3,117,865; or, poly(ethylene) terephthalate electron bOmbarded as described by Carroll and Chapman in U.S. Pat. 3,220,842.

12 EXAMPLE 30 Example 29 is repeated except that the blue sensitive silver halide emulsion layer is spectrally sensitized with about 140 mg. per mole of silver of the dye 5-(3-ethyl-2- benzothiazolinylidene)-3-fl-sulfoethylrhodanine. The dye images obtained, including the yellow dye image, are free from mottle. However, when this example is repeated but using the dye 3-carboxymethyl-5-(3-ethyl-2(3H)-benzothiazolylidene)rhodanine as the sole spectral sensitizing dye in the blue sensitive emulsion layer, the yellow dye image obtained exhibits objectionable mottle.

EXAMPLE 3 1 Example 29 is repeated except that the green sensitive emulsion layer is spectrally sensitized with about mg. per mole of silver of dye anhydro-3,3di(,8-carboxyethyl) 9-ethyl-5,5'-diphenyloxacarbocyanine hydroxide, severe mottle appears in the magenta dye image. In addition, the green sensitive emulsion exhibits an undesirable speed loss of .09 when compared to the speed of the same emulsion containing the same spectral'sensitizer and coupler but using a baryta coated paper support which is not electron bombarded.

In the preparation of the above photographic elements by the process of this invention, the sensitizing dyes can be incorporated in the washed, finished silver halide emulsion and should, of course, be uniformly distributed throughout the emulsion. The methods of incorporating dyes and other addenda in emulsions are relatively simple and well known to those skilled in the art of emulsion making. For example, it is convenient to add them from solutions in appropriate solvents, in which case the solvent selected should be completely free from any deleterious effect on the ultimate light-sensitive materials. Methanol, isopropanol, pyridine, water, etc., alone or in admixtures, have proven satisfactory as solvents for this purpose. The type of silver halide emulsions that can be sensitized in the process of this invention include any of those prepared with hydrophilic colloids that are known to be satisfactory for dispersing silver halides, for example, emulsions comprising natural materials such as gelatin, albumin, agaragar, gum arabic, alginic acid, etc. and hydrophilic synthetic resins such as polyvinyl alcohol, polyvinyl pyrrolidone, cellulose ethers partially hydrolyzed cellulose acetate, and the like. Any suitable silver halide can be used, such as silver chloride, silver bromide, silver bromoiodide, silver chlorobromide, etc.

The binding agents for the emulsion layer of the photographic element can also contain dispersed polymerized 'vinyl compounds. Such compounds are disclosed, for example, in U.S. Patents 3,142,568; 3,193,386; 3,062,674 and 3,220,844 and include the water insoluble polymers of alkyl acrylates and methacrylates, acrylic acid, sulfoalkyl acrylates or methacrylates and the like.

The sulfo-substituted methine dyes can be used in any suitable concentration in the practice of this invention. Good results are obtained, for example, with from about 50 to 200 mg. dye per mole of silver. However, optimum concentrations vary widely, depending on the particular dye and emulsion used.

The problem of dye mottle which occurs when emulsions containing color former are coated on corona discharge treated hydrophobic supports does not occur when a long holding period is initiated between the corona discharge treatment of the support and coating of the emulsion onto the support. Thus, when the examples hereof are repeated, with at least a two hour holding period between the corona discharge treatment of the polyolefin surface and the coating of the emulsion, no mottle is apparent.

Certain dyes of this invention are especially useful since they are free from any speed loss when coated on a polyolefin surface after it has been electron bombarded. Such preferred dye species include N,N-disulfoalkyl substituted oxacarbocyanine dyes (i.e., the dyes contain two benzoxazole nuclei joined, at the respective Z-carbon atoms thereof, by a methine linkage, and the hetero nitrogen atom of each benzoxazole nucleus has a sulfoalkyl group attached thereto) and unsymmetrical benzimidazole oxacarbocyanine dyes wherein at least one of the nitrogen atoms in one of the heterocyclic rings of the cyanine dye (i.e., the nitrogen atom of either the benzoxazole ring, the benzimidazole ring, or both of those nitrogen atoms) contains a sulfoalkyl group. Specific preferred dyes which result in emulsion coatings which are free from any speed loss are the dyes of Examples 1, 2, 3 and 6.

The cause of mottle in dye images produced when conventional methine dyes are used to sensitize silver halide emulsions containing color former, when the emulsions are coated on a hydrophobic surface substantially immediately after it has been electron bombarded, is not fully understood. It may be related to ozone or nascent oxygen, which is present on electron bombarded hydrophobic surfaces substantially immediately after electron bombardment. The reason why sulfo-substituted methine dyes avoids mottle, whether caused by nascent oxygen, ozone or some other cause, is not known.

The invention has been described in detail with particular reference to preferred embodiments thereof, but, it will be understood that variations and modifications can be effected within the spirit and scope of the invention dc scribed hereinabove and in the appended claims.

We claim:

1. The method for preparing a light sensitive photographic element which provides dye images substantially free from mottle, which comprises:

(1) spectrally sensitizing a light sensitive photographic silver halide emulsion with a cyanine or merocyanine dye having at least one sulfo group;

(2) incorporating photographic color coupler in said emulsion;

(3) electron bombarding a hydrophobic surface to provide good adhesion for said emulsion; and,

(4) coating said emulsion onto said hydrophobic surface within about 30 minutes after said electron bombarding treatment.

2. The method for preparing a light sensitive photographic element as defined in claim 1 wherein said methine wherein Z and Z each represents the non-metallic atoms required to complete a heterocyclic nucleus of the type used in cyanine dyes; L L and L each represents a methine group; R and R each represents a member selected from the group consisting of an alkyl group and an aryl group, at least one of said Z, Z R and R including a sulfo group; d and e each represents an integer of from 1 to 2; n represents an integer of from 1 to 3; and, X represents an acid anion.

3. The method forpreparing a light sensitive photographic element as defined in claim 2 wherein at least one of said R and R represents a sulfoalkyl group.

4. The method for preparing a light sensitive photographic element as defined in claim 3 wherein said dye is an N,N'-disulfoalkyl substituted oxacarbocyanine dye.

5. The method for preparing a light sensitive photographic element as defined in claim 3 wherein said dye is a benzimidazole-oxaczrrbocyanine dye wherein at least one of the nitrogen atoms in one of the heterocyclic rings thereof contains a sulfoalkyl group.

6. The method for preparing a light sensitive photographic element as defined in claim 2 wherein at least one of said R and R represents a sulfoalkyl group; and, said Z and Z each represents the non-metallic atoms required to complete a heterocyclic nucleus selected from the group consisting of a benzimidazole nucleus and a benzoxazole nucleus; and, said emulsion is coated onto said hydrophobic surface within about 30 seconds after electron bombarding treatment.

7. The method for preparing a light sensitive photographic element as defined in claim 2 wherein said hydrophobic surface is selected from the group consisting of a poly-a-olefin, a polyester, a polyamide, a polyacetal, a polycarbonate, cellulose ester, cellulose ether and hardened gelatin.

8. The method for preparing a light sensitive photographic elemcnt as defined in claim 2 wherein said hydrophobic surface is a polyethylene film coated on a paper support.

9. The method for preparing a light sensitive photographic element as defined in claim 1 wherein said methine dye has the following general formula:

wherein Z represents non-metallic atoms to complete a heterocyclic nucleus of the type used in cyanine dyes; R represents a member selected from the group consisting of an alkyl group and an aryl group; Q represents the non-metallic atoms required to complete a 5 to 6 membered sulfo-substituted heterocyclic nucleus of the type used in merocyanine dyes, at least one of Q, Z and R containing a sulfo group; L and L each represents a methine group; a represents an integer of from 1 to 2; and, m represents an integer of from 1 to 3.

10. The method for preparing a light sensitive photographic element as defined in claim 9 wherein Q of said formula represents the atoms required to complete a heterocyclic nucleus containing 5 atoms in the heterocyclic ring, three of said atoms being carbon, 1 of said atoms being nitrogen and 1 of said atoms being selected from the group consisting of a nitrogen atom, an oxygen atom and a sulfur atom, a nitrogen atom included within the meaning of said Q containing a substituent selected from the group consisting of a sulfoalkyl group and a sulfoaryl group.

11. The method for preparing a light sensitive photographic element as defined in claim 9 wherein said hydrophobic surface is selected from the group consisting of a poly-a-olefin, a polyester, a polyamide, a polyacetal, a polycarbonate, cellulose ester, cellulose ether and hardened gelatin.

12. The method for preparing a light sensitive photographic element as defined in claim 9 wherein said hydrophobic surface is a polyethylene film coated on a paper support.

13. The method for preparing a light sensitive photographic element as defined in claim 1 wherein said color coupler is selected from the group consisting of phenolic, S-pyrazolone, heterocyclic and open chain ketomethylene photographic couplers, said couplers being dissolved in a solvent and the solution being dispersed in the photo graphic silver halide emulsion.

14. The method for preparing a light sensitive photographic element as defined in claim 1 wherein said hydrophobic surface is selected from the group consisting of a poly-a-olefin, a polyester, a polyamide, a polyacetal, a polycarbonate, cellulose ester, cellulose ether and hardened gelatin.

15. The method for preparing a light sensitive photographic element which comprises:

(1) spectrally sensitizing a photographic silver bromoiodide emulsion with the dye anhydro-5-chloro-9- ethylS-phenyl-3'-(3-sulfobutyl)-3-(3 sulfopropyl)- oxacarbocyanine hydroxide, sodium salt;

(2) dispersing in the said silver halide emulsion a solution of photographic pyrazolone color former dissolved in a solvent;

(3) electron bombarding the polyethylene surface of a polyethylene coated paper support, said electron bombardment being of sufficient intensity to provide 1 5 1 6 a contact angle on the polyethylene surface of less FOREIGN PATENTS than 76; 1 460 174 11/1966 F 685 coating Said spectrally sensitized silver emulgi g sion containing pyrazolone coupler onto said electron bombarded polyethylene surface Within about 5 NORMAN TORCHIN Primary Examiner one minute from the time of said electron bombardmerm J. WINKELMAN, Assistant Examiner References Cited U S CL X R UNITED STATES PATENTS 96-85, 106 3,480,434 11/1969 Hanna 96-74 10