US3573057A - High resolving power photographic emulsions and materials - Google Patents

Abstract

PHOTOGRAPHIC HYDROPHILIC COLLOID BINDER SILVER HALIDE LIPPMANN EMULSIONS THAT CONTAIN A REMOVABLE AND SUBSTANTIALLY PHOTOGRAPHICALLY INERT DYE WHICH ABSORBS LIGHT OF THE SPECTRAL COMPOSITION SELECTED FOR EXPOSING THE EMUSLION WHEN COATED ON A SUPPORT AS THE LIGHT-SENSITIVE LAYER ARE USED TO ADVANTAGE TO PRODUCE IMAGE REPRODUTIONS OF EXCEPTIONALLY HIGH RESOLUTION AND SHARPNESS.

Description

United States Patent Olfice 3,573,057 Patented Mar. 30, 1971 HIGH RESOLVING POWER PHOTOGRAPHIC EMULSIONS AND MATERIALS Guy W. W. Stevens, Berkhamsted, England, assignor to Eastman Kodak Company, Rochester, NY. N Drawing. Filed May 3, 1967, Ser. No. 635,705 Int. Cl. G03c 1/72, 1/02 US. Cl. 96-112 18 Claims ABSTRACT OF THE DISCLOSURE Photographic hydrophilic colloid binder silver halide Lippmann emulsions that contain a removable and substantially photographically inert dye which absorbs light of the spectral composition selected for exposing the emulsion when coated on a support as the light-sensitive layer are used to advantage to produce image reproductions of exceptionally high resolution and sharpness.

This invention relates to light-sensitive photographic materials and is concerned with those photographic silver halide materials with which high resolution reproductions of fine grain originals and the like are obtainable.

Dyes, especially yellow dyes, have often been incorporated in light-sensitive gelatin silver halide emulsion layers to reduce image spread upon exposure. This method has been very successful where the reduction in contrast and speed produced by the presence of the dye has been acceptable for the purpose at hand.

However, this method has not proved adequate where emulsion layers have been required for producing images of high resolution and sharpness such as are needed in the produtcion of printed electronic circuits and electronic elements particularly for microminiaturization. For this purpose it has been usual to project images with a microscope on a so-called Lippmann emulsion (i.e., a silver halide emulsion having average grain diameter up to about 0.1a). For some high resolution Work, the wet-collodion process may be used even today.

Antihalation backing coatings are required for prior art high resolution materials, however, they are easily scratched by the sharp edges of glass plate supports and elimination of the antihalation coating is highly desirable.

It is an object of my invention to provide a novel Lippmann emulsion which when coated on supports give superior control of line image Width reproduction.

It is another object of my invention to provide a novel sensitive photographic material for producing image reproductions of exceptionally high resolution and sharpness which does not require an antihalation layer.

Still another object is to provide a novel method for obtaining superior control of line image width reproduction required in the production of images of exceptionally high resolution and sharpness by use of my dry emulsion layers.

Still other objects will be apparent from a consideration of the following specification and claims.

These and still other objects are accomplished by providing my novel hydrophilic colloid binder silver halide Lippmann emulsions that contain a high concentration of at least one removable and substantially photographically inert light-absorbing dye. My emulsions are advantageously coated on suitable supports preferably free of any antihalation coatings to make photographic elements used to produce image reproductions of exceptionally high resolution and sharpness. The removable and substantially photographically inert dye preferably absorbs light of the spectral composition selected for exposing the photographic material. By a removable dye I mean a dye that is removable during photographic processing by virtue of the dye being soluble in water or the alkaline processing solutions or by virtue of the dye being bleached or rendered colorless by the processing solutions. The emulsions are advantageously coated in a thin layer on a suitable support, usually to give a dry lay-er thickness in the range of from about 2 to about 6,u. The weight ratio of silver halide to hydrophilic colloid binder in my Lippmann emulsions is advantageously at least about 1:3 and preferably at least about 2:1, and the concentration of the lightabsorbing dye in the emulsion is made sufficient to coat a layer having a density of at least 0.15 density units per micron thickness to light of the selected spectral composition. I have found that use of my preferred emulsions is exceptionally advantageous since the increase in silver halide content counteracts the loss of speed and contrast resulting from the use of a large amount of dye.

Any of the hydrophilic colloid binders used in photographic emulsion layers are used to advantage in my novel Lippmann emulsions including gelatin, albumin, cellulose derivatives and various synthetic polymeric binders. The polymeric binders include polyvinyl alcohol or a hydrolyzed polyvinyl acetate as described in Lowe US. Pat. 2,286,215, issued June 16, 1942; a far hydrolyzed cellulose ester such as cellulose acetate hydrolyzed to an acetyl content of 10-26 percent as described in US. Pat. 2,327,- 808 of Lowe and Clark, issued Aug. 24, 1943; a watersoluble ethanolamine cellulose acetate as described in Yutzy US. Pat. 2,322,085; issued June 15, 1943; a polyacrylamide having a combined acrylamide content of 30- 60 percent and a specific viscosity of 025-15 on an imidized polyacrylamide of like acrylamide content and viscosity as described in Lowe, Minsk and Kenyon US. Pat. 2,541,474, issued Feb. 13, 195 1; zein as described in Lowe US. Pat. 2,563,791, issued Aug. 7, 1951; a vinyl alcohol polymer containing urethane carboxylic acid groups of the type described in Unruh and Smith US. Pat. 2,768,154, issued Oct. 23, 1956; or containing cyanoacetyl groups such as the vinyl alcohol-vinyl cyanoacetate copolymer as described in Unruh, Smith and Priest US. Pat. 2,808,331, issued Oct. 1, 1957; or a polymeric material which results from polymerizing a protein or a saturated acylated protein with a monomer having a vinyl group as described in US. Pat. 2,852,382, of Illingsworth, Dann and Gates, issued Sept. 16, 1958.

Any of the pure or mixed silver halides are used in making the Lippmann emulsions of my invention including silver bromide, silver chloride, silver iodide, silver chloroiodide, silver bromoiodicle, silver chlorobromoiodide, etc. Silver halide emulsions in which the halide comprises more than mole percent bromide and the average silver halide grain size is up to about 0.1,u. are particularly advantageous.

The upper limits of silver halide to hydrophilic colloid binder ratio and of the light-absorbing dye concentration are governed by practical considerations. Thus, the silver halide to binder ratio can be as high as can be tolerated in the preparation of the emulsion, it being desirable to avoid coarse grain formation during precipitation, and faults such as those known as peppers caused by silver halide grains touching One another and becoming spontaneously developable (i.e., without exposure) and development faults, such as chemical fogging and excessive graining. The weight ratio of silver halide to hydrophilic colloid binder in the operable range of from about 1:3 to about 8:1 is used to advantage in making my novel emulsions. A preferred ratio range is from 2:1 to about 6:1.

The upper limit of light-absorbing dye concentration depends to some extent on the particular dye. For instance, some dyes more readily crystallize out from gelatin mixtures than other dyes. Too much dye can also prevent the colloid binder from setting when coated on its support.

The dye chosen should be One having a minimum deleterious action (such as fogging or desensitization) on the emulsion and should be readily washed out of the emulsion layer, or bleached during processing. The density of the dye in the layer can be measured directly or can be calculated from the density and volume of either the dye solution used during the preparation of the layer or a solution obtained by extracting the dye from the layer. The dry coating thickness may readily be calculated from the coating weights of hydrophilic colloid binder and silver halide, and the specific gravity of these substances.

In the case where the support is of paper, the dye is preferably one which is substantive to or can be mordanted to the colloid binder in order that it will not bleed into the paper.

The light-absorbing dyes used in my Lippmann emulsions can be any of the Well-known removable light-absorbing dyes used in photographic elements. Included among light absorbing dyes used to advantage in my emulsions are the oxonol dyes of Keys et al. U.S. Pat. 2,611,- 696; the styryl dyes of Sprague U.S. Pat. 2,622,082; the pyrrole dyes of Reed US. Pat. 2,725,378; the merocyanine dyes of Silberstein et al. U.S. Pat. 2,527,583; the azonaphthalene dyes of Van Campen U.S. Pat. 2,956,879; the merocarbocyanine dyes of Mader et al. U.S. Pat. 3,016,-

306; the oxonol dyes of Bailey U.S. Pat. 3,247,127; the oxonol, merocarbocyanine and merodicarbocyanine dyes of Jones et al. U.S. Pat. 3,282,699; the dyes derived from substituted 3-pyrrocolines described by Bailey in U.S. P'at. 3,260,601; the 4-phenylaZo-2-phenyloxazoles of Sawdey U.S. Pat. 2,852,376; the azo dyes of Straley U.S. Pat. 2,860,979, etc.

Particularly elficacious dyes include those represented by the formulas:

wherein R represents an alkyl group such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tertiary butyl, etc., or a carboxyalkyl group, such as carboxymethyl, carboxyethyl, carboxypropyl, etc., or a sulfoalkyl group, such as sulfoethyl, sulfopropyl, sulfobutyl, etc.; Z represents the nonmetallic atoms necessary to complete a heterocyclic nucleus of the benzoxazole series (including benzoxazole and benzoxazole substituted with substituents such as methyl, ethyl, phenyl, methoxy, ethoxy, chlorine, bromine, etc.) or a nucleus of the benzoxazole series which has a sulfo-substituent on the benzene ring as Well as one or more of the above-mentioned simple substituents, such that when R represents an alkyl group, Z represents the sulfosubstituted benzoxazole nucleus and when R represents a carboxyalkyl group or a sulfoalkyl group, Z represents the nonmetallic atoms necessary to complete a benzoxazole nucleus; Q represents the nonmetallic atoms necessary to complete a heterocyclic nucleus of the sulfophenyl pyrazolinone series and n is an integer from 1 to 3.

wherein Q and n are as defined previously, and the oxonol dyes of formula:

wherein R is a carboxyalkyl group in which the carboxy substituent is attached to an alkyl group having from 1 to 2 carbon atoms such as methyl and ethyl; R is a member selected from the class consisting of an alkyl group having from 1 to 8 carbon atoms, such as methyl, benzyl, ethyl, propyl, isopropyl, butyl, secondary butyl, tertiary butyl, hexyl, octyl, cyclohexyl, etc., an aryl group, such as phenyl, 2-methylphenyl, 2-methoxyphenyl, 2,4- dimethylphenyl, etc.; n is an integer of from 1 to 3; X is a hydrogen atom or an alkyl group having from 1 to 4 carbon atoms such as methyl, ethyl, propyl, butyl, etc., such that not more than one X is an alkyl group.

in which R represents a hydrogen atom, a lower alkyl group (sulfonated or not), such as methyl, sulfoethyl, sulfopropyl, propyl, sulfobutyl, etc., a lower alkoxy group, such as methoxy, ethoxy, propoxy, butoxy, etc., a benzene ring which may be fused to the pyridine ring of the pyrrocoline group, etc.; R and R each can represent an alkyl group (sulfonated or not), such as methyl, sulfomethyl, ethyl, propyl, isopropyl, sulfopropyl, n-butyl, sulfobutyl, etc., an aryl group (sulfonated or not), such as phenyl, 4-sulfophenyl, 4-tolyl, 2-sulfo-4-tolyl, 5-methoxyphenyl, 4-acetamidophenyl, etc., an arylalkyl group (sulfonated or not), such as phenylmethyl, phenylethyl, phenylpropyl, 4-sulfophenylethyl, 2-sulfophenylpropyl, etc.; and Z is a group of atoms which together with the nitrogen of the pyrrocoline nucleus completes a conjugated chain and terminates in another nitrogen atom or in an oxygen atom. All of these dyes may have in the molecule one or more sulfonic acid substituents and may also have one or more carboxyl groups.

Illustrative examples of typical dyes used to advantage include the following:

(1) 3 (3,5 disulfobenzamido) 4 [(3ethyl-2-(3H)- benzoxazolylidene)ethylidene] 1-phenyl-2-pyrazolin- S-one (2) 3 methyl 4 [(3 [3 sulfoethyl-2(3H)benzoxazolylidene)ethylidene] 1 p-sulfophenyl-2-pyrazolin- 5-one (3) 4 [(3 ethyl 2(3H) benzoxazolylidene)ethylidene] 3 methyl 1 (p-sulfophenyl) 2 pyrazolin- 5-one, monosulfonated (4) 4 [4 (3 ethyl 2(3H)-benzoxazolylidene)-2- butenylidene] 3 methyl 1 (p-sulfophenyD-Q- pyrazolin-S-one, monosulfonated (5) 4 3 B carboxyethyl 2(3H) benzoxazolylidene)ethylidene] 3 methyl 1-(p-sulfophenyl)-2- pyrazolin-S-one (6) 4 [4 (3 f3 ethyl 2(3H) benzoxazolylidene)- .2 butenylidene] 3 methyl 1 (p-sulfophenyl)-2- pyrazolin-S-one (7) 3 methyl 4 {6 [3-(4-sulfobutyl)-2-benzoxazolinylidene] 1,3 neopentylene 2,4 hexadienylidene}-1-p-sulfophenyl-Z-pyrazolin-5-one (8) 3 methyl 4 {6 [3 (2-sulfoethyl)-2-benzoxazolinylidene] 1,3 neopentylene 2,4 hexadienylidene} 1 p sulfophenyl 2 pyrazolin-S-one (9) 3 methyl 4 {6 [3 (2 carboxyethyl) -.2- benzoxazolinylidene] 1,3 neopentylene 2,4 hexadienylidene} 1 p sulfophenyl 2 pyrazolin-S-one (10) 3 methyl 4 {6 [3 (4-sulfobutyl)-2-benzoxazolinylidene] 1,3 neopentylene 2 butenylidene}- 1 p sulfophenyl 2 pyrazolin 5 one (11) bis(l butyl 3 carboXymethyl hexahydro 2,4,6-

trioxo 5 pyrimidine)-trimethinoxonol (12) bis[l (p sulfophenyl) 3 methyl 2 pyrazolin- 5 one (4)1-trimethinoxonol (l3) bis[1 (p sulfophenyl) 3 methyl 2 pyrazolin- 5-one-(4) ]-pentamethinoxonol, etc.

(14) bis(1 butyl 3 carboxymethyl hexahydro 2,4,6-

trioxo-S-pyrimidine) -trimethinoxonol bis(1 butyl 3 carboxymethyl hexahydro 2,4,6-

trioxo-S-pyrimidine) -pentamethinoxonol (16) bis(l carboxymethylhexahydro 3 n octyl- 2,4,6 trioXo 5 pyrimidine)-3-methylpentamethinoxonol (17) bis(1 n butyl 3 carboxymethylhexahydro- 2,4,6-trioxo-5-pyrimidine) trimethinoxonol 18) (3 ethyl .2 benzoxazole) (1 methyl 2- phenyl 3 pyrrocoline sulfonic acid)dimethincyanine iodide (19) bis(1-methyl 2 phenyl 3 pyrrocoline sulfonic acid) methincyanine acetate (20) 1 butyl 3 carboxymethylhexahydro 5 [3- (1 methyl 2 phenyl 3 pyrrocolinyl sulfonic acid) allylidene]-2,4,6-trioxopyrimidine (2 1) l ethyl 2,5 dimethyl 3 pyrrole) (l-methyl- 2 phenyl 3 pyrrocoline sulfonic acid)methincyanine acetate (22) 3 p dimethylaminobenzylidene l methyl-2- phenyl 3 pyrrocolinium sulfonic acid acetate (23) 4 (4 n dodecyloxy 2 sulfophenylazo) 5- hydroxy-Z-phenyloxazole sodium salt (24) 4 (3 carboxyphenylazo) 2 (2-carboxyphenyl)- 5 hydroxyoxazole (25) 5 anilinomethylene 3 (Z-dimethylaminoethyl) rhodanine (126) 5 acetanilide methylene 3 (2 dimethylaminoethyl)rhodanine (27) 3(2 dimethylaminoethyl) 5 piperidinornethylenerhodanine Dyes 25, 26 and 27 above are illustrative of the dialkylaminoalkyl substituted light filtering dyes of Taber et al. French Pat. 1,444,772 such as, for example, the dialkylaminoalkyl substituted hemioxonol dyes.

The light-absorbing dyes are incorporated in my emulsions by the methods conventionally used for incorporating light filtering dyes in hydrophilic colloids for filter layers in photographic elements. Usually my dyes are Water-soluble, however, other conventional solvents, such as, ethanol, pyridine, etc., are also used to advantage. As will be noted in Example 1 below, some dyes are advantageously added in solid form to the emulsion and intimately stirred until dissolved in the water contained in the emulsion.

When my emulsions are to be coated on a paper support, mordants are advantageously added to the emulsion to prevent the dye from wandering from the emulsion into the paper. For this purpose, dyes having acid solubilizing group substituents are advantageously mordanted with any of the well known basic mordants, including those described by Minsk in U.S. Pat. 2,882,156; Reynolds et al. U.S. Pat. 2,768,078; U.S. Pat. 2,531,468; 2,531,469; Carroll et al. U.S. Pat. 2,675,316; Sprague et al. U.S. Pat. 2,548,564; etc. Particularly efficacious are the mordants of Minsk U.S. Pat. 2,882,156 prepared by condensing a polyvinyloxonol compound or certain copolymers with styrene or alkylmethacrylates.

My emulsions are advantageously optically sensitized by any of the well-known optical sensitizers including the cyanine and merocyanine dyes such as those described in Brooker U.S. Pats. 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. 1,990,507, issued Feb. 12, 1935; Brooker and White U.S. Pats. 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. 2,493,748, issued Jan. 10, 1950; Sprague U.S. Pats. 2,503,776, issued Apr. 11, 1950, and 2,519,001, issued Aug. 15, 1950; Heseltine and Brooker U.S. Pat. 2,666,761, issued Jan. 19, 1954; Heseltine U.S. Pat. 2,734,900, issued Feb. 14, 1 956; Van Lare U.S. Pat.

2,739,149, issued Mar. 20, 1956; and Kodak Limited British Pat. 450,958, accepted July 15, 1936.

A preferred material of my invention comprises a green-sensitized Lippmann emulsion. In my photographic materials which are spectrally sensitized, it is convenient to select light for exposing the emulsion layer which contains predominant wavelengths in the region of spectral sensitization of the emulsion.

My emulsions are advantageously treated with salts of noble metals, such as, ruthenium, rhodium, palladium, iridium, platinum, as described in Smith and Trivelli U.S. Pat. 2,448,060, and Trivelli and Smith U.S. Pats. 2,566,245 and 2,566,263.

My emulsions can also be chemically sensitized with gold salts such as described in Waller et al., U.S. Pat. 2,339,083, or stabilized with gold salts as described in Damschroder U.S. Pat. 2,597,856 and Yutzy and Leermakers U.S. Pat. 2,597,915.

My emulsions advantageously contain the thiopolymers of Graham et al. U.S. Pat. 3,046,129.

My emulsions can also be stabilized with the mercury compounds, the triazoles, the azaindenes, the disulfides, the quaternary benzothiazolium compounds, the zinc and cadmium salts which are described in the patent references listed in column 20, line 51 through column 21, line 3 in Graham et a1. U.S. Pat. 3,046,129.

My emulsions may be hardened advantageously with any suitable hardener for hydrophilic colloids, such as, gelatin, including such hardeners as formaldehyde; a halogen substituted aliphatic acid such as mucobromic acid; a compound having a plurality of acid anhydride groups; a bisester of methane sulfonic acid; a dialdehyde or a sodium bisulfite derivative thereof such as fi-methylglutaraldehyde bis sodium bisulfite; a bis-aziridine carboxamide such as trimethylene bis(1-aziridine carboxamide) etc., such as are described in column 21, lines 32 through 61 of U.S. Pat. 3,046,129.

Any of the conventional coating aids such as are described in U.S. Pat. 3,046,129, columns 21 and 22 are used to advantage in the preparation of the coatings of my emulsions.

My emulsions are advantageously coated on any of the supports conventionally used for photographic elements including glass, cellulose acetate, cellulose nitrate, synthetic resins (e.g., polystyrene, polyethylene terephthalate, etc.), Paper, etc.

The following examples will still further illustrate my invention.

EXAMPLE. 1

An emulsion is prepared with 50 grams of gelatin and 188 grams silver bromide in a total volume of 1,400 ml. The precipitation conditions are controlled to give an emulsion with an average grain diameter of about 0.06 Information on suitable precipitation conditions is to be found in Small Scale Preparation of Fine Grain Photographic Emulsions by B. H. Crawford, N. P. L. Notes on Applied Science No. 20, 1960, and Perfilov, N. A., Novikova, N. R., and Prokofyeva, E. I., Trav. Inst. Rad. Chlopin, 7, 257, 1956. The emulsion is sensitized with 0.25 gram of 4-methyl-2,3'-diethoxathiazolocarbocyanine iodide, giving particularly strong spectral sensitization in the band 510-530 mg. Three grams of solid dye No. 12, i.e., bis (3 methyl-1-(p-sulfophenyl)-2-pyrazolin-5-one (4) trimethinoxonol are then added to the emulsion at 35 C., and stirring is continued for 15 minutes to dissolve this dye. The resulting heavily dyed emulsion is then coated on a glass plate support to give a dry layer 5;; thick. The plate is exposed to a resolution test image reduced with a microscope objective. The illuminant is a tungsten lamp filtered with a green band Wratten No. 16 filter, so that latent image formation only occurs in the band effectively absorbed by the absorbing dye. The coating is developed in a p-methylaminophenol-hydroquinone developer such as Kodak developer D-19 according to the invention to give sharp images; also image quality changes very little with changing exposure, hence having advantageous working tolerances. The range of line widths adequately reproduced at a single exposure value is also increased. Determination of the density of the unprocessed layer at 520 m gives a value of 0.4 per unit micron thickness of the dry emulsion. Similar results are obtained when still other conventional black-and-white developing solutions are used.

EXAMPLE 2 Results similar to those obtained in Example 1 are obtained when Example =1 is repeated using approximately equivalent amounts of dyes 1, 2, 3, 5, 11, l4, 17, 23, 24, 25, 26 and 27 in separate emulsions in place of dye 12 used in Example 1.

Similarly it can be shown that these and other greenlight absorbing dyes are advantageously used in still other Lippmann emulsions of my invention using silver bromide and other silver halides (either without optical sensitization, or with green-sensitization with the same or different optical sensitizing dye), dispersed in gelatin or other hydrophilic colloid binder in which the weight ratio of silver halide to hydrophilic colloid is in the range from about 2:1 to about 8:1.

EXAMPLE 3 Example 1 is repeated but using an optical sensitizing dye sensitizing in the orange region of the spectrum (i.e., in range of from about 580 to 600 m in place of the green-sensitizer of Example 1, and using in place of dye 12 approximately equivalent amounts of dyes 4, 6, l0, 13, 15, 17, and 22 in separate emulsions. The exposures to the resolution test image are made using as the light source a tungsten lamp filtered with an orange colored Wratten No. 24 filter in place of the Wratten No. 16 filler. The image reproductions obtained upon processing as in Example 1 are of high resolution.

EXAMPLE 4 Example 1 is repeated but using an optical sensitizing dye sensitizing in the red region of the spectrum in place of the green-sensitizer of Example 1, and using in place of dye 12 approximately equivalent amounts of dyes 7, 8, 9 and 21 in separate emulsions. The exposures to the resolution test image are made using as the light source a tungsten lamp filtered with a red colored Wratten No. 29 filter. High resolution image reproductions similar to those from Examples 1, 2 and 3 are obtained upon development with the usual developer solutions.

It should be noted that no halation is observed in the images developed in my photographic elements of Examples 1, 2, 3 and 4 even though these elements do not contain any anti-halation coatings. My elimination of the need for anihalation layers in photographic elements is a valuable technical advance especially in high resolution plates where no halation can be tolerated. As has been mentioned previously, antihalation backing layers, particularly on glass plates are vulnerable to scratching and digs from the sharp corners and edges of the glass plates while they are being handled. Elimination of this backing layer therefore eliminates a potentially serious if not serious source of defects. Because of the exacting requirements for high resolution and image sharpness, especially in the field of manufacturing microminiaturized electronic components and circuits, it is obvious that halation, and defects such as scratches and digs cannot be tolerated in the image reproductions. My emulsions are valuable because they are halation free even without the protection of an antihalation coating, and because they produce image reproductions of exceptionally high resolution and sharpness.

The following example will still further illustrate the advantages provided by my invention.

8 EXAMPLE 5 An emulsion is made as described in Example 1 but in which the weight ratio of silver bromide to gelatin is about 1:3 is coated on a glass plate having an antihalation backing coat. The antihalation backing coating is then carefully removed from one-half of the plate. The light-sensitive emulsion layer is then contact printed with a plate having a parallel line /2 tone tint image using a sensitometer for a light source. The printing is done so that the half of the plate with and the half of the plate without any antihalation backing receive identical sensitometric exposures. After photographic processing as described in Example 1, a comparison of the parallel line reproduction even at the high exposure end of the sensitometric exposures shows that there is no halation or developed silver in the non-image areas, i.e., between consecutive parallel lines reproduced on the half of the plate from which the antihalation backing was removed. When Example 5 is repeated using the same emulsion but containing none of the dye, the parallel line image reproduction in the half of the plate from which the antihalation backing is removed prior to exposure is completely obscured by silver development of silver halide exposed by halation in the higher and intermediate exposure levels. This illustrates that high resolution emulsions outside my invention are inoperative over a substantial range of exposure levels when no antihalation backing protection is provided on the photographic plate. A comparison of the image reproductions in the prior art material (with an antihalation backing) against image reproductions in my elements (either with or without the antihalation backing) shows that the image reproductions made in my elements are substantially higher in resolution and sharpness than those made in the prior art material.

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

I claim:

1. A photographic hydrophilic colloid binder silver halide Lippmann emulsion with an average silver halide grain size of up to about 0.1; containing incorporated a removable and substantially photographically inert dye with respect to fogging and desensitization of said emulsion, said dye absorbing light of a spectral composition selected for exposing the emulsion when coated as a light-sensitive layer of a photographic element, the concentration of said dye being suflicient to give a layer density of at least about 0.15 density units per micron thickness to light of the selected composition, said dye being selected from the class consisting of hemioxonol dyes, oxonol dyes, styryl dyes, pyrrole dyes, mecrocyanine dyes, azonaphthalene dyes, dyes derived from 3-pyrrocolines and 4-phenylazo-2-phenyloxazole dyes, said emulsion being halation-free when coated as a layer on a support, even without the protection of an antihalation coating, said emulsion having a weight ratio of silver halide to binder of at least about 1:3.

2. A photographic hydrophilic colloid binder silver halide Lippmann emulsion with an average silver halide grain size up to about 0.1 containing incorporated a removable and substantially photographically inert dye with respect to fogging and desensitization of said emulsion, said dye absorbing light of a spectral composition selected for exposing the emulsion when coated as a lightsensitive layer of a photographic element, the concentration of said dye being suflicient to give a layer density of at least about 0.15 density units per micron thickness to light of the selected composition, said dye being selected from the class consisting of those having the formulas:

wherein R represents a group selected from the class consisting of alkyl, sulfoalkyl and carboxyalkyl; Z represents the nonmetallic atoms necessary to complete a benzoxazole nucleus such that when Z does not contain a sulfo group, R represents a group selected from the class consisting of sulfoalkyl and carboxyalkyl; Q represents the nonmetallic atoms necessary to complete a sulfophenyl pyrazolinone nucleus; and n represents an integer of from 1 to 3;

wherein Q and n are as defined previously;

wherein R represents a carboxyalkyl group in which said alkyl moiety contains from 1 to 2 carbon atoms; R represents a group selected from the class consisting of an alkyl group and an aryl group; n is as defined previously; and X represents a member selected from the class consisting of hydrogen and alkyl having from 1 to 4 carbon atoms, such that not more than one X is alkyl; and

wherein R represents a member selected from the class consisting of hydrogen, a lower alkyl group, a lower alkoxy group and a benzene ring fused to the pyridine ring; R and R each represent a group selected from the class consisting of an alkyl group and an aryl group; and Z represents a group of atoms which together with the nitrogen of the pyrrocoline nucleus completes a conjugated chain and terminates in an atom selected from the class consisting of nitrogen and oxygen, said dye (4) having one or more sulfonic acid substituents, said emulsion being halation-free when coated on a support even Without the protection of an antihalation coating, said emulsion having a weight ratio of silver halide to binder of at least about 1:3.

3. A photographic hydrophilic colloid binder silver halide Lippmann emulsion with an average silver halide grain size up to about 0.1 containing incorporated a re movable and substantially photographically inert dye with respect to fogging and desensitization of said emulsion, said dye absorbing light of a spectral composition selected for exposing the emulsion when coated as a light-sensitive layer of a photographic element, the concentration of said dye being sufiicient to give a layer density of at least about 0.15 density units per micron thickness to light of the selected composition, said dye being selected from the class consisting of dyes having the formulas:

Q Q O=C CHCH(=CHCH)n G=O wherein Q represents the nonmetallic atoms required to complete a sulfophenyl pyrazolinone nucleus; and n represents an integer of from 1 to 3; and

wherein R represents a carboxyalkyl group in which said alkyl moiety contains from 1 to 2 carbon atoms; R represents a group selected from the class consisting of an alkyl group and an aryl group; n is as defined previously; and X represents a member selected from the class consisting of hydrogen and alkyl having from 1 to 4 carbon atoms, such that not more than one X is alkyl, said emulsion being halation-free when coated as a layer on a support, even without the protection of an antihalation coating, said emulsion having a weight ratio of silver halide to binder of at least about 1:3.

4. An emulsion of claim 1 in which said binder is gelatin.

5. An emulsion of claim 1 having a weight ratio of silver halide to hydrophilic colloid binder of at least about 2:1.

6. An emulsion of claim 1 in which the hydrophilic colloid is gelatin and the emulsion is spectrally sensitized.

7. An emulsion of claim 1 in which said halide comprises more than mole percent bromide.

8. A gelatin silver bromide Lippmann emulsion wherein the weight ratio of silver halide to gelatin is about 3.8 to 1, the said emulsion containing silver bromide grains having an average diameter of about 0.06 and containing incorporated about 0.06 gram of bis(3-methyl-1-psulfophenyl-4-pyrazole-5-one)-trimethineoxonol per gram of gelatin.

9. A sensitive photographic material which comprises a support bearing a photographic gelatino silver bromide Lippmann emulsion layer having a dry layer thickness of about 5 wherein the weight ratio of silver bromide to gelatin is about 3.8:1, the said emulsion containing silver bromide grains having an average diameter of about 0.06 the said layer containing incorporated about 0.06 gram of bis(3 methyl-1-p-sulfophenyl-4-pyrazole-5-one) trimethineoxonol per gram of gelatin.

10. A sensitive photographic element which comprises a support bearing a layer of a photographic hydrophilic colloid binder silver halide Lippmann emulsion with an average silver halide grain size of up to about 0.1 containing a removable and substantially photographically inert dye with respect to fogging and desensitization of said emulsion, said dye absorbing light of a spectral composition selected for exposing the emulsion layer, the concentration of said dye in the layer being great enough to give the layer a density of at least 0.15 density unit per micron thickness to light of the selected composition, said dye being selected from the class consisting of hemioxonol dyes, oxonol dyes, styryl dyes, pyrrole dyes, merocyanine dyes, azonaphthylene dyes, dyes derived from 3-pyrrocolines and 4-phenylazo-2phenyloxazole dyes, said emulsion being halation-free when coated as a layer on a support, even without an antihalation coating, said emulsion having a weight ratio of silver halide to binder of at least about 1:3.

11. In the method of producing high resolution photographic reproductions of fine grain originals which cornprises exposing a light-sensitive emulsion layer of a photographic material and processing the exposed layer to produce a silver image therein, the improvement comprising the use of a sensitive photographic material which comprises a support bearing a layer of a photographic hydrophilic colloid silver halide Lippmann emulsion with an average silver halide grain size of up to about 0.1 containing a removable and substantially photographically inert dye with respect to fogging and desensitization of said emulsion, said dye absorbing light of a spectral composition selected for exposing the emulsion layer, the concentration of the dye in the layer being great enough to give the layer a density of at least 0.15 density unit per micron thickness to light of the selected composition, said dye being selected from the class consisting of hemioxonol dyes, oxonol dyes, styryl dyes, pyrrole dyes, merocyanine dyes, azonaphthylene dyes, dyes derived from 3- pyrrocolines and 4-phenylazo-2-phenyloxazole dyes, said emulsion being halation-free when coated as a layer on a support even without an antihalation coating, said emul- 12 sion having a weight ratio of silver halide to binder of at 17. A sensitive photographic material of claim 10 least about wherein the support is paper.

12. A sensitive photographic material of claim 10 which is free of an antihalation layer.

13. A sensitive photographic material of claim 10 wherein said hydrophilic colloid binder is gelatin and said dye is an oxonol dye. References Cited 14. A sensitive photographic material of claim 10 wherein the said emulsion has a weight ratio of silver The Blmsh Journal of Photography 1900 halide to hydrophilic colloid binder of at least 2: 1. 10 Pages 27 and 15. A sensitive photographic material of claim 10 wherein the hydrophilic binder is gelatin and said emul- NORMAN TORCHIN Primary Exammer sion has a Weight ratio of silver halide to binder of at A, T. SURO PICO, Assistant Examiner least 2:1.

16. A sensitive photographic material of claim 10 15 US- C X- wherein the hydrophilic colloid binder is gelatin and the 9694 emulsion is spectrally sensitized.

18. A sensitive photographic material of claim 10 wherein the support is glass.