US3811891A

US3811891A - Silver halide photographic element containing a vinylsulfonyl compound hardener and an acrylic urea as formaldehyde scavenger

Info

Publication number: US3811891A
Application number: US00266767A
Authority: US
Inventors: R Darlak; C Wright
Original assignee: Eastman Kodak Co
Current assignee: Eastman Kodak Co
Priority date: 1972-06-27
Filing date: 1972-06-27
Publication date: 1974-05-21
Anticipated expiration: 1991-05-21
Also published as: AU5728373A; FR2191150A1; JPS4953434A; BE801553A; FR2191150B1; DE2332426A1; CA1001472A

Abstract

An acyclic urea aldehyde scavenger is concurrently associated with a hardenable hydrophilic colloid and a vinylsulfonyl hardener. In a preferred form the acyclic urea aldehyde scavenger is incorporated into a hydrophilic colloid layer that is located between a coupler containing photographic layer and an aldehyde source.

Description

United States Patent 1191 Inventors: Robert S. Darlak, Penfield; Charles J. Wright, Rochester, both of NY.

Assignee: Eastman Koadak Company, Rochester, N.Y.

Filed: June 27, 1972 Appl. No.2 266,767

US. Cl 96/74, 96/76 R, 96/95;l00;l09;l1l Int. Cl. G03c 1/76, G03c l/48, G03c l/30, G03c l/06,'G03c l/40, G030 l/30 Field of Search 96/111, 55, 95, 100, 109, 96/76 R, 74, 22

1111 3,811,891 Darlak et al. I May 21, 1974 SILVER HALIDE PHOTOGRAPHIC [56] References Cited ELEMENT CONTAININ A UNITED STATES PATENTS VINYLSULFONYL COMPOUND HARDENER 3,490,911 1/1970 Burness et al. 96/111 AND AN ACRYLIC UR AS 2,579,435 12/1951 Mackey 96/5 6 FORMALDEHYDE SCAVENGER 3,168,400 ,2/1965 Blackmer er al 96/56 Primary ExaminerRonald H. Smith Assistant Examiner-Won H. Louie, Jr. Attorney, Agent, or Firm-M. Carl 0. Thomas [57] ABSTRACT 14 Claims, N0 Drawings SILVER HALIDE PHOTOGRAPI-IIC ELEMENT CONTAINING A VINYLSULFONYL COMPOUND IIARDENER AND AN ACRYLIC UREA AS FORMALDEI-IYDE SCAVENGER ments by forming on a support one or more photographically active. layers. Typically these photographically active layers contain silver halide dispersed in a hydrophilic colloid, such as gelatin, to form an emulsion. ln multi-layer photographic elements used in color photography there are at least three selectively sensitive color forming units each made up of one or more emulsion layers'coated on one side of a photographic support, such as film or paper.-The color forming units are typically rendered variously responsive to the red, green and blue'regions of the spectrum. The blue-sensitive color forming unit typically contains a yellow coupler, the green-sensitive color forming unit amagenta coupler and the red-sensitive color forming unit a c'yan coupler. In an alternative form color couplers are not initially present in the photographic element, but are introduced during processing after an imageforming exposure. l-lydrophilic colloid subbing layers, interlayers and over-layers are also typically present. The blue-sensitive color forming unit forms the outermost unit, and a Carey Lea silver filter layer various cyclic and acyclic ureas as aldehyde scavengers. Albers et al. U.S. Pat. No. 2,309,492, issued Jan. 26, 1943, points out the problem of traces of formaldehyde causing color-fog in photographic elements by attacking pyrazolone couplers to produce yellow compounds and suggests the use of aldehyde scavengers such as hydroxyl amines, hydrazine derivatives, hydrazo derivatives, semicarbazides, dimethylhydroresorcin or naphthylene diamines. Callear et al. U.S. Pat. No. 2,895,827, issued July 21, 1959, points to the problem of aldehyde migration from photographic paper supports coated with formaldehyde resins such as ureaformaldehyde and melamine-formaldehyde and'suggest normally overlies the green and the red sensitive color forming'units to protect them against residual blue light not absorbed in the blue-sensitive color forming unit. Multi-layer photographic elements used in color phot'ography of this general type and processes for their preparation are well known in the art, as is illustrated,

for example, by Product Licensing Index, Vol. 92, De-

cember 1971, publication 9232, at page 110.

1 It is conventional practice to incorporate into photographic hydrophilic colloid layers addenda, referred to as hardeners, having as their purpose the reduction or elimination. of the susceptibility of such colloid layers to abrasion, swelling in aqueous solutions and softening atelevated temperatures. Abrasion is a particular concern during such fabrication steps as winding and spooling wh'ileswelling and softening are of primary concern during processing, especially in those in-- stances where it is desired to accelerate processing by resort to elevated temperatures.

Aldehydes, such as formaldehyde, glyoxal, succinaldehyde,glutaraldehyde, etc. have been proposed for this purpose. However, certain disadvantages have been observed by those skilled in the art to result from associating aldehydes with photographic elements, even, in some instances, in the trace amounts found in the atmosph ere. Aldehydes, in some cases, can produce excessive hardening of the hydrophilic colloid containing'layers, direct interaction with color couplers, and emulsion fogging.

To combat these disadvantages associated with the presence of aldehydes it has been proposed to utilize the utilization of urea or melamine sizing layers on the surfaceof such supports to act as aldehyde scavengers. Blackmer et al U.S. Pat. No. 3,168,400, issued Feb. 2, 1965, teaches that the carrythrough of aldehyde'hardening agents into developing solutions can lead to the formation of sludge and scum and suggests the incorporation of various amine compounds, including biuret, in

predevelopment baths to scavenge any residual aldehyde hardener that remains in the emulsion layers before processing. Asano U.S. Pat. No. 3,652,278, issued Mar. 28, l972, teaches the use of a variety of compounds including amines and amides, such as N,N'-

ethylene urea, acetamide, N,N-diacetylethylene diamine, monomethylamine or dimethylamine as scavengers for formaldehyde gas contained in the atmosphere.

the use of cyclic hydrazide stabilizers and antifoggants in emulsions hardened with ,a mixture of mucochloric acid and formaldehyde to prevent interaction of the hydrazides with the formaldehyde. Jones U.S. Pat. No. 2,708,161 and Carroll et al. U.S. Pat. No. 2,708,162, both issued May 10, 1965, teach that the use of parabanic acid and urazole, respectively, as antifoggants for polyalkylene oxide sensitized emulsions interfere with the hardening action of formaldehyde and glyoxal, and the alternative use of alpha-hydroxyadipaldehyde or l,5-bi's(methane sulfonoxy)-pentane as hardeners is suggested. Dersh U.S. Pat. No. 3,582,346, issued June I, 1971, follows the teachings of Jones and Carroll et al in recognizing that polyalkylene oxide sensitized emulsions are particularly fog sensitive and suggest the use of ethylene diurea as an antifoggant.

The art has recognized distinct advantages to the utilization of vinylsulfonyl compounds in place of aldehydes as hardeners for the hydrophilic colloid layers of photographic elements. Such compounds are characterized by the inclusion of a plurality of vinylsulfonyl groups. In perhaps the simplest possible structural form, divinylsulfone, a single sulfonyl group joins two vinyl groups. Most typically a plurality of vinylsulfonylalkyl groups, such as vinylsulfonylmethyl, ethyl, propyl or butyl groups, are joined through an intermediate ether, amine, diamine or hydrocarbon linkage. Bis(- vinylsulfonyl) ethers such as bis(vinylsulfonylmethyl) and bis(vinylsulfonylethyl) ethers have been found particularly suitable for use as hardeners. Representative vinylsulfonyl hardeners as well as procedures for their synthesis and use are disclosed in Bumess et'al. U.S. Pat. Nos. 3,490,911, issued Jan. 20, 1970; 3,539,644,

issued Nov. 10, 1970, and 3,642,486, issued Feb. 15, 1972, the disclosures of which are incorporated by reference.

In one aspect, the present invention is directed to a process wherein a vinylsulfonyl hardener and an acyclic urea aldehyde scavenger are concurrently associated within a hydrophilic colloid forming a portion of a photographic element. In an additional aspect, this invention is directed to a photographic element having a hydrophilic colloid layer containing a vinylsulfonyl harde'ner and an acyclic urea scavenger.

As utilized herein the term an acyclic urea refers to those compounds in which none of the urea moieties HN E NH present form a portion of a ring structure, as is the case, for example, in compounds such as barbituric acid and urazole. It is contemplated that these acyclic ureas can include one or more cyclic nitrogen substituents, as is hereinafter more fully illustrated.

It has been discovered that vinylsulfonyl hardeners and acyclic urea aldehyde scavengers are compatible in the hydrophilic colloid layers of photographic elements. This is quite unexpected, since both cyclic and acyclic amides, including ureas, having been generally known in the art to be directly reactive with aldehyde hardeners for hydrophilic colloid layers. To further illustrate the unexpected characterof this discovery it is noted that the behavior of acyclic urea aldehyde scavengers in combination with vinylsulfonyl hardeners differs from the behavior of heterocyclic ureas, such as N,N-ethylene urea, barbituric acid and urazole. Vinylsulfonyl hardeners incorporated in hydrophilic colloid.

layers containing one of these heterocyclic ureas are reactive with the heterocyclicurea in preference to the hydrophilic colloid, to the detriment of both the hardening and aldehyde scavenging properties desired to be imparted by these addenda.

lt is a distinctly advantageous feature of this invention that the vinylsulfonyl hardener and acyclic urea aldehyde scavenger can be concurrently associated with a hydrophilic colloid layer of a photographic element. This means simply that the colloid, the acyclic urea aldehyde scavenger and the vinylsulfonyl hardener (as opposed to the scavenger and the reaction product of the vinylsulfonyl hardener with the colloid) can be brought together. This permits both addenda to be introduced into or on the colloid in a substantially contemporaneous manner during formation of the photographic element, rather than waiting until the vinylsulfonyl compound has hardened the hydrophilic colloid to the extent desired before incorporation of the aldehyde scavenger into the element. The full extent of this advantage can be better appreciated when it is considered that in forming a photographic element a number of hydrophilic colloid layers can be advantageously concurrently formed on a support and that the vinylsulfonyl hardener, even if it is initially present within only one of these layers, can distribute itself throughout the layers, as is taught more fully by Graham French Pat. 2,090,921, issued Dec. 20, 1971. Additionally, the acyclic urea scavenger when non-ballasted can also wander from its situs of introduction in the photographic element. Utilizing an aldehyde scavenger which is incompatible with the vinylsulfonyl hardener in this circumstance requires a subsequent preparation step to associate this addenda with a hydrophilic colloid layer.

Since hydrophilic colloids employed in the formation of photographic elements frequently contain water as one ingredient at the time they are deposited as layers on a support, it is preferred to utilize water soluble acrylic urea aldehyde scavengers. Preferred acyclic ureas contemplated for use in the practice of this invention are aldehyde scavengers having the formula:

wherein m O A.. O a

H 8 11 X is a HN-(OHz)mN or HN- group;

m is l or 2; n is 0 or 1; and R and R are independently selected from the class consisting of hydrogen, lower alkyl, hydroxyalkyl and aryl, such as a phenyl substituent. As utilized herein the term lower alkyl" refers to those alkyl groups having six or fewer carbon atoms. Exemplary water soluble acyclic ureas within the contemplation of this invention include urea, methyl urea, ethyl urea, butyl urea, hexyl urea, N,N'-dimethyl urea, N,N'-diethyl urea, hydroxymethyl urea, N,N-di(2-hydroxyethyl) urea, N,N'-di(2- hydroxyhexyl) urea, phenyl urea, biuret, hydroxyethyl biuret, l,5-di(hydroxyethyl) biuret, methylene diurea, l,l-ethylene diurea, and- 3,3'-dihydroxyethyl-l ,1- ethylene diurea. While it is preferred to utilize water soluble ureas, it is recognized that photographic addenda are frequently incorporated using other solvents. lt is accordingly contemplated that any acyclic urea aldehyde scavenger known to be useful in photographic elements can be employed.

In one form of the invention the acyclic urea scavenger can be incorporated within the vinylsulfonyl hardener containing hydrophilic colloid layer of the photographic element to be protected from aldehyde attack. Thus in an exemplary simple form a photographic element according to this invention can comprise a support having thereon a single silver halide photographic emulsion layer containing a hydrophilic colloid, an acyclic urea aldehyde scavenger and a vinylsulfonyl hardener. Since most photographic elements contain a plurality of hydrophilic colloid layers, it is generally preferred to maximize the protection of the photographic element by locating the aldehyde scavenger in a hydrophilic colloid layer between the aldehyde source and the layer to be protected from aldehyde attack. Where the support for the photographic element is itself penneable to or a source of aldehydes, the aldehyde scavenger may be located beneath the layer to be protected or may be located both under and over the layer to be protected, as in a colloid subbing layer, interlayer, overcoat layer, or a combination of such layers. In most instances photographic supports such as polymeric films, glass, metal and the like are impermeable to aldehydes and it is only necessary to protect the photographic element from aldehyde incursion through the overcoat. In a typical color photographic element having a film support in which it is desired to protect the magenta and/or cyan coupler conv taining layers from aldehyde attack, the scavenger is preferably located in the outer hydrophilic colloid layer or the Carey Lea silver filter layer, but can be advantageously incorporated in any overlying layer or interlayer, including a blue-sensitive emulsion layer. It is recognized that the aldehyde scavenger need not be blended into a vinylsulfonyl hardener hydrophilic colloid layer to be associated therewith as contemplated by this invention, but can simply contiguously overlie the hardener containing hydrophilic colloid layer.

The concentration of acyclic ureaaldehyde scavengerassociated with a photographic element according to this invention can vary widely, depending upon such factors as the degree of protection from aldehyde attack desired, the concentrations of aldehyde expected to be encountered, the sensitivity of the ingredients within the photographic element sought to be protected, the water solubilityof the acyclic ureachosen and the like. In order to effectively protect photographic elementsfrom visible degradation attributable to attack by formaldehyde present in the atmosphere during storage it is generally preferred that the acyclic urea be present in a concentration of at least 0.1 milligrams per square decimeter. Generally acyclic urea concentrations of from 0.1 to 40 milligrams per square decimeter are preferred with concentrations of from 1 to. 30 milligrams per square .decimeter being particularly useful. The vinylsulfonyl hardener associated with the acyclic urea aldehyde scavenger can be incorporated in any conventional useful concentration and will typically be employed in a concentration of from 0.1 to 10 percent and, most commonly 0.5 to 6.0 percent, by weight, based on the weight of the hardenable material present. I

Most commonly, gelatin constitutes the hardenable material present within the hydrophilic colloid layers of photographic elements. Other materials known to be hardenable by vinylsulfonyl hardeners which may be present in one or more hydrophilic colloid layers of a photographic element-are colloidal albumin, acid or water-soluble vinyl polymers, cellulose derivatives, proteins, various polyacrylarnides, dispersed polymerized vinyl compounds, particularly those which increase the dimensional stability of photographic materials exemplified by amine-containing polymers of alkyl acrylates,

methacr'ylat es, acrylic acid, sulfoalkyl acrylates or methacrylat'es or the like. One function of the acyclic urea aldehyde scavengers of this invention can be to protect such hardenable materials from further hardening by aldehydes after the desired degree of hardening has been imparted by the vinylsulfonyl hardener.

Another function of the acyclic urea aldehyde scavenger can be to protect one or more other ingredients of a photographic element. For example, the acyclic urea-aldehyde scavenger can be used to protect fixed color couplers, such as those which are reactive with aryl amines,which can be present in one or more of the color forming units of a photographic element. Certain of these couplers are quite sensitive to the presence of aldehydes and, if left unprotected, during storage between preparation and processing, will readily react with formaldehyde present in the atmospheres to produce a compound visibly distinguishable from the compound desired to be formed by reaction of the coupler with the aryl amine developer. In the reaction of a fixed coupler contained in a photographic element with an aldehyde a marked color loss can occur. For example, magenta couplers such as S-pyrazolone couplers as described in Loria et al. U.S. Pat. No. 2,600,788, issued June 17, 1952, are known to suffer marked color loss when associated with relatively small quantities of aldehydes.

Photographic elements utilizing non-ballasted couplers such as those added during development are protected from color loss by protecting the colloid layers from undesirable hardeningthat can retard or impede introduction of these couplers. Accordingly, it is apparent that this invention is applicable to color photographic elements generally and is specifically noted to be useful in protecting photographic elements for producing both positive and reversal color images. Exemplary color photographic elements capable of being benefited by the practice of this invention are set forth in Graham et al. U.S. Pat. No. 2,725,292, Salminen et al. U.S. Pat. No. 2,895,826, Bush et al. U.S. Pat. No. 2,920,961, Beavers U.S. Pat. No. 2,983,608, Loria et al. U.S. Pat. No. 3,006,759, Whitmore et al. U.S. Pat. No. 3,l48,062,-Loria et al. U.S. Pat. No. 3,214,437, Barr et al. U.S. Pat. No. 3,227,554, Young U.S. Pat. No. 3,419,391and Lestina U.S. Pat. No. 3,519,429.

This invention can be further illustrated by the following examples of preferred embodiments thereof although it will be understood that these examples are included merely for purposes of illustration and are not intended to limit the scope of the invention unless otherwise indicated.

EXAMPLE 1 containing a magenta-dye-forming coupler, which was in this case a S-pyrazolone coupler'as disclosed by Loria et a1, cited above; a yellow Carey-Lea silver gelatin filter layer; a blue-sensitive silver halide emulsion layer containing a yellow-dye-forming coupler; and a gelatin outerlayer containing the scavenging compound and bis(vinyl-sulfonylmethyl) ether hardener. The hardener was incorporated in the outerlayer to diffuse through and harden each of the gelatin layers present at a concentration of 1.5 percent by weight based on the gelatin present. One of the photographic elements served as a control and contained no aldehyde scavenger; the second element contained 3 mg/dm of barbituric acid; and the third element 5 mg/dm of 1,1- ethylene diurea. The scavengers were prepared as an aqueous solution for blending with the gelatin prior to forming the layers.

Each of the photographic elements was given a sensitometric exposure and then exposed to an aldehyde by suspension for 16 hours in a stream of room temperature air having a relative humidity of from 50 to 60 percent and containing from 0.4 to 0.8 mg of gaseous formaldehyde'per liter of air. After exposure to aldehyde the elements were immersed at 38C. for 3 minutes in Kodak F-6 developer, for 6 minutes in bleach-fix solution comprised of a ferric ethylene diamine te'tracetic acid and ammonium thiosulfate, for minutes in water and finally for 10 seconds in a stabilizer bath comprised of 6 ml of 35 percent formalin and 8 to 9 ml of an ethylene oxide wetting agent per liter.

Even though the photographic elements were processed at relatively low temperatures the emulsion layers were lost from the barbituric acid containing photographic element during processing. This indicated that the barbituric acid had reacted directly with the bis(vinylsulfonylmethyl) ether so that the emulsion layers were inadequately hardened to permit processing. In the remaining two photographic elements the relative maximum densities of the magenta image forming dyes contained in the initially green-sensitive emulsion layer of each photographic element were compared to determine the effectiveness of the 1,1 -ethylene diurea as an aldehyde scavenger. Whereas the element containing no aldehyde scavenger exhibited a 57 percent dye loss, the 1,1 '-ethylene diurea protected element exhibited only a 30 percent dye loss under the stringent conditions of comparison. Percentage dye loss attributable to aldehyde attack wasin each instance determined by comparison with an identical photographic element identically exposed and processed, but not subjected to aldehyde exposure. The fact that the emulsion layers remained on the photographic element containing the l,l T-ethylene diurea during processing indicated that the bis(vinylsulfonylmethyl) ether had effectively hardened the gelatin layers and had not preferentially interacted with the acrylic urea aldehyde scavenger. This was corroborated by comparing the swelling of the acyclic urea containing photographic element with that of the element free of aldehyde scavengers.

EXAMPLES 2-7 The procedures of Example 1 were repeated using l,l-ethylene diurea and varying the concentration and location of the scavenger. The results are set forth in Table I.

Carey Lea Silver Layer EXAMPLES 8-16 A number of photographic elements were prepared differing only by the choice of aldehyde scavenger, each photographic element comprised a support impermeable to aldehydes on which was deposited a gray silver gelatin emulsion layer; a photographically active layer containing 28.5 mg/dm silver bromide, 24.5

mg/dm gelatin and 9.5 mg/dm of the magenta dyeforming coupler of Example 1; and an overlayer comprised of 8.0 mg/dm of gelatin having dispersed therein 7.0 mg/dm of aldehyde scavenger and sufficient bis(vinylsulfonylmethyl) ether to adequately harden each of the gelatin layers present. The image exposure, aldehyde exposure and processing were carried out as described in Example 1. The specific aldehyde scavengers incorporated and the percentage of magenta dye loss are set forth in Table ll.

No evidence was apparent of interaction of the vinylsulfonyl hardener and the aldehyde scavenger, and in every instance the aldehyde scavenger effectively reduced the percentage of dye loss attributable to aldehyde attack.

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

We claim:

1. In a silver halide emulsion containing photographic element in which a vinylsulfonyl hardener is associated with a hydrophilic colloid layer, the improvement in which said hydrophilic colloid layer contains in addition to said vinylsulfonyl hardener an acyclic urea aldehyde scavenger in an amount of at least 0.1 milligrams per square decimeter, said scavenger having the formula:

wherein:

m is l or 2;

n is 0 or 1; and

R and R are independently selected from the class consisting of hydrogen, alkyl containing one to six carbon atoms, hydroxyalkyl and aryl.

2. In a silver halide emulsion containing photographic element in which a vinylsulfonyl hardener is associated with a plurality of superimposed hydrophilic colloid layers on a support which is substantially impenetrable by formaldehyde and in which at least one of said layers contains a coupler capable of reacting with an aryl amine to produce a first compound having a visible color and, alternatively, capable of reacting with formaldehyde to produce a second compound visibly distinguishable from the first compound, the improvement comprising at least one of said hydrophilic colloid layers overlying said formaldehyde reactive coupler containing layer including an acyclic urea formaldehyde scavthe further improvement in which 9 enger in an amount of at least 0.] milligrams per square decimeter, said scavenger having the following structural formula:

wherein Rand R are independently selected from the class consisting of hydrogen, alkyl containing one to six carbon atoms, hydroxyalkyl and a phenyl substituent.

3. In a photographic element according to claim 2, the further improvement in which said scavenger ,is present in an amount of from 1 to 30 milligrams per square decimeter.

4. In a photographic element according to claim 2, the further improvement in which said scavenger is urea.

5. In a photographic element according to claim 2, the further improvement in which said scavenger is an aryl substituted urea.

6. In a photographic element according to claim 2, the further improvement in which said scavenger is phenyl urea.

7. In a photographic element according to claim 2, the further improvement in which said scavenger is an alkyl substituted urea.

8. In a photographic element according to claim 2, said scavenger is a dialkyl urea. I

9. In a photographic element according to claim I, the further improvement in which said scavenger is biuret.

10. In a photographic element according to claim 1, the further improvement in which said scavenger is an alkylene diurea.

11. In a photographic element according to claim 1, the further improvement in which said scavenger is ethylene diurea.

12. In a photographic element according to claim 2, the further improvement in which said hardener is a bis(vinylsulfonyl) ether.

13. In a photographic element according .to claim 2, the further improvement in which said hardener is bis(vinylsulfonylmethyl) ether.

14. In a silver halide emulsion containing photographic element comprising a plurality of bis(vinylsulfonyl) hardener containing gelatin layers located in superimposed relationship on a support which is substantially impenetrable to formaldehyde and in which said layers form at least three color forming units each sensitive to a different region of the visible spectrum, one of which units contains a S-pyrazolone coupler, the improvement comprising at least one of said gelatin layers overlying said 5- pyrazolone coupler containing layer comprising a concentration of ethylene diurea of at least 0.1 milligrams per square decimeter.

Claims

2. In a silver halide emulsion containing photographic element in which a vinylsulfonyl hardener is associated with a plurality of superimposed hydrophilic colloid layers on a support which is substantially impenetrable by formaldehyde and in which at least one of said layers contains a coupler capable of reacting with an aryl amine to produce a first compound having a visible color and, alternatively, capable of reacting with formaldehyde to produce a second compound visibly distinguishable from the first compound, the improvement comprising at least one of said hydrophilic colloid layers overlying said formaldehyde reactive coupler containing layer including an acyclic urea formaldehyde scavenger in an amount of at least 0.1 milligrams per square decimeter, said scavenger having the following structural formula:
3. In a photographic element according to claim 2, the further improvement in which said scavenger is present in an amount of from 1 to 30 milligrams per square decimeter.
4. In a photographic element according to claim 2, the further improvement in which said scavenger is urea.
5. In a photographic element according to claim 2, the further improvement in which said scavenger is an aryl substituted urea.
6. In a photoGraphic element according to claim 2, the further improvement in which said scavenger is phenyl urea.
7. In a photographic element according to claim 2, the further improvement in which said scavenger is an alkyl substituted urea.
8. In a photographic element according to claim 2, the further improvement in which said scavenger is a dialkyl urea.
9. In a photographic element according to claim 1, the further improvement in which said scavenger is biuret.
10. In a photographic element according to claim 1, the further improvement in which said scavenger is an alkylene diurea.
11. In a photographic element according to claim 1, the further improvement in which said scavenger is ethylene diurea.
12. In a photographic element according to claim 2, the further improvement in which said hardener is a bis(vinylsulfonyl) ether.
13. In a photographic element according to claim 2, the further improvement in which said hardener is bis(vinylsulfonylmethyl) ether.
14. In a silver halide emulsion containing photographic element comprising a plurality of bis(vinylsulfonyl) hardener containing gelatin layers located in superimposed relationship on a support which is substantially impenetrable to formaldehyde and in which said layers form at least three color forming units each sensitive to a different region of the visible spectrum, one of which units contains a 5-pyrazolone coupler, the improvement comprising at least one of said gelatin layers overlying said 5-pyrazolone coupler containing layer comprising a concentration of ethylene diurea of at least 0.1 milligrams per square decimeter.