Blocked incorporated developers in a photographic element

A photographic element is disclosed including a support bearing at least one photographic silver halide emulsion layer and at least one non-photosensitive layer between the emulsion layer and the support, wherein the non-photosensitive layer comprises at least one blocked developing agent.

BACKGROUND OF THE INVENTION 
This invention pertains to photographic elements, and in particular to 
photographic elements incorporating blocked photographic developers in a 
novel arrangement of layers. 
It is well known in the art that the introduction of conventional color 
developers, such as p-aminophenols, into sensitized photographic elements 
containing silver halide salts, leads to desensitization of the silver 
halide emulsion and unsuitable fog in such layers. Much effort has 
therefore been directed at trying to produce effective blocked developers, 
which can be introduced in silver halide emulsion elements without 
deleterious desensitization or fog effects and which unblock chemically 
under conditions of development so that developer is free to participate 
in color forming (dye forming) reactions. 
U.S. Pat. No. 3,342,599, to Reeves, discloses the use of Schiff base 
developer precursors. Schleigh and Faul, in a Research Disclosure (129 
(1975) pp. 27-30), described the quaternary blocking of color developer 
and the acetamido blocking of p-phenylenediamines. Subsequently, U.S. Pat. 
No. 4,157,915, to Hamaoka et al., and U.S. Pat. No. 4,060,418, to Waxman 
and Mourning, describe the preparation and use of carbamate blocked 
p-phenylenediamines. 
All of these approaches and inventions have failed in practical product 
applications because of one or more of the following problems: 
desensitization of sensitized silver halide; unacceptably slow unblocking 
kinetics; instability of blocked developer yielding increased fog and/or 
decreased Dmax after storage. 
Recent developments in blocking and switching chemistry have led to blocked 
p-phenylenediamines that perform well. In particular, compounds having 
".beta.-ketoester" type blocking groups (strictly, .beta.-ketoacyl 
blocking groups) are described in U.S. Pat. No. 5,019,492. With the advent 
of the .beta.-ketoester blocking chemistry, it has become possible to 
incorporate p-phenylenediamine developers in film systems in a form from 
which they only become active when required for development. 
The incorporation of these blocked developers in photographic elements is 
carried out using colloidal gelatin dispersions of the blocked developers. 
These dispersions are prepared using means well known in the art, wherein 
the developer precursor is dissolved in a high vapor pressure organic 
solvent (for example, ethyl acetate), along with, in some cases, a low 
vapor pressure organic solvent (such as dibutylphthalate), and then 
emulsified with an aqueous surfactant and gelatin solution. After 
emulsification, usually done with a colloid mill, the high vapor pressure 
organic solvent is removed by evaporation or by washing, as is well known 
in the art. 
The .beta.-ketoacyl blocked developers are released from the film layers in 
which they are incorporated by an alkaline developing solution containing 
a dinucleophile, for example hydroxylamine. 
There has been a need for a photographic element incorporating a blocked 
developer which is stable until development. Then the element can be 
developed rapidly and easily. There has also been a need for a process for 
developing an image in a photographic element which employs a developing 
solution having a simplified composition. 
SUMMARY OF THE INVENTION 
This and other needs have been satisfied by providing a photographic 
element comprising a support bearing at least one photographic silver 
halide emulsion layer and at least one non-photosensitive layer between 
the emulsion layer and the support, wherein the non-photosensitive layer 
comprises at least one blocked developing agent. 
In a preferred embodiment, the blocked developing agent has a structure 
according to the formula (I): 
EQU D--(T).sub.m --S (I) 
in which 
D is a silver halide developer, 
T is a timing group, 
m is an integer from 0 to 6 and denotes the number of timing groups 
connected in series, and 
S is a blocking group. 
In preferred embodiments, the blocking group is an acyl group, particularly 
preferably a .beta.-ketoacyl group. 
Additionally, there is provided a process for developing an image in a 
photographic element comprising a support, a photographic silver halide 
emulsion layer containing an imagewise distribution of developable silver 
halide grains, and a non-photosensitive layer between the emulsion layer 
and the support containing at least one blocked developing agent, 
comprising the step of contacting the element with a processing solution 
comprising a nucleophile. Preferably, the developing agent is blocked with 
an acyl group. Particularly preferably, the developing agent is blocked 
with a .beta.-ketoacyl group and the nucleophile is a dinucleophile. Also 
preferably, the blocking group is a simple acyl group, and the nucleophile 
is a peroxide, particularly hydrogen peroxide. 
Furthermore, there is provided a process for producing the foregoing 
photographic element which comprises the steps of providing a support, 
applying to the support a non-photosensitive layer comprising at least one 
blocked developing agent, and subsequently applying to the 
non-photosensitive layer a photographic silver halide emulsion layer.

DETAILED DESCRIPTION OF THE INVENTION 
It has now been discovered that a photographic element having a blocked 
developing agent in a non-photosensitive layer disposed between the 
element support and the photosensitive layer or layers, can be developed 
more efficiently upon processing. It has further been discovered that the 
use of .beta.-ketoacyl blocked developing agents in the non-photosensitive 
layer is particularly advantageous. Use of simple acyl blocked developing 
agents is also advantageous. 
Related inventions and embodiments are described in U.S. patent application 
Ser. No. 07/810,241 (use of blocked photographically useful groups with 
peroxide-containing processes), U.S. patent application Ser. No. 810,322 
(use of .beta.-ketoacyl type blocked developers in image intensification 
chemistry systems) and U.S. patent application Ser. No. 810,232 (use of 
solid particle dispersions of .beta.-ketoacyl blocked developers), filed 
simultaneously herewith and incorporated in their entireties by reference. 
The invention achieves simplification of the composition of the developing 
solution, in that incorporation of a developing agent into the 
photographic element leads to a reduction in the concentration of 
developing agent in the processing solution required to obtain a high 
quality dye image. The developer solution is also utilized more 
efficiently. 
Incorporation of blocked compounds in sensitized layers can lead to small 
but unwanted desensitization of the silver halide emulsion. Thus, 
separation of the emulsions and blocked developers by coating the latter 
in a non-sensitized layer of the photographic element overcomes this 
problem. 
Incorporation of the blocked developer in a layer beneath an imaging layer 
in the photographic elements according to the invention also enables more 
efficient development of the element. This is because the release of 
developers from the blocked forms involves a series of chemical reactions 
during which intermediates having high mobility under development 
conditions are generated. These intermediates may diffuse from the 
photographic element into the bulk of the processing solution, which can 
result in an inefficiency in development. By coating the blocked developer 
beneath an imaging layer, the diffusion distance of the released 
intermediates to the developer solution is increased, and moreover, the 
compounds diffuse through the imaging layer before reaching the processing 
solution. 
In formula I, the timing group(s), T, can contain one or more substituents 
to control the aqueous solubility of the precursor compound. Exemplary 
timing groups are disclosed in U.S. Pat. Nos. 4,248,962; 4,741,994; 
4,772,537; 4,985,336; and 5,019,492, the disclosures of which are 
incorporated by reference. Up to six timing groups can be joined 
sequentially according to the invention (that is, m=0 to 6). Preferably, 
m=0, 1 or 2. 
The blocking group S must have appropriate hydrolysis kinetics, that is, it 
must be a group that completely unblocks in the course of the development 
process. The blocking group S preferably is an acyl group, particularly a 
.beta.-ketoacyl group as described in U.S. Pat. No. 5,019,492, or a simple 
acyl ester as described in Ser. No. 07/810,241. Exemplary preferred 
blocking groups include: 
##STR1## 
in which R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 individually are H 
or an unsubstituted or substituted alkyl group having 1 to 20 carbon 
atoms, and preferably are H or methyl. In the simple acyl blocking group, 
R.sub.1 can be an unsubstituted or substituted alkyl, alkoxy, aryl or 
aryloxy group, as described in U.S. patent application Ser. No. 
07/810,241. 
The group S can also contain one or more substituents to control the 
aqueous solubility of the developer precursor. Exemplary substituents can 
include halogen, alkyl, aryl, heterocyclic, cyano, alkoxy, aryloxy, acyl, 
acylamino, anilino, ureido, alkylthio, arylthio, alkoxycarbonylamino, 
sulfonamido, unsubstituted or substituted carbamoyl, sulfamoyl, sulfonyl, 
alkyoxycarbonyl, heterocyclic oxy, acyloxy, carbamoyloxy, 
aryloxycarbonylamino, imido, heterocyclic thio, sulfinyl, phosphonyl, 
aryloxycarbonyl, alkylsulfonyl, arylsulfonyl, hydroxy, carboxy, and sulfo 
groups, as well as others known to those skilled in the art. The timing 
group T can likewise be substituted. 
Both the timing and blocking groups can be unballasted or ballasted. In 
other words, at least one of T and S can include a group of such molecular 
size and configuration as to render the present compound nondiffusible as 
described, for example, in U.S. Pat. Nos. 4,420,556 and 4,923,789. 
Advantageous ballast groups include alkyl and aryl groups having from 
about 8 to 32 carbon atoms. 
In formula I, the silver halide developer D can preferably be a color 
developer. The silver halide color developer D preferably is of the 
p-phenylenediamine or p-aminophenol type. Preferred developers according 
to the invention are given below in Table I. These developers according to 
the invention are prepared by well-known techniques, such as those 
described in U.S. Pat. No. 5,019,492, and also those described in U.S. 
patent application Ser. No. 07/700,006, U.S. patent application Ser. Nos. 
07/810,241 and 07/810,322, as well as in U.S. Pat. No. 3,342,599, U.S. 
Pat. No. 4,060,418, and U.S. Pat. No. 4,157,915, the disclosures of each 
of which are incorporated in their entireties by reference. 
The color developer, D, like the timing and blocking groups, may contain 
one or more substituents to control the aqueous and/or oil solubility of 
the developer precursor. Typical substituents include alkyl, hydroxyalkyl, 
sulfonamidoalkyl, sulfoalkyl, sulfo and carboxyalkyl, as well as others 
previously listed and known to those skilled in the art. 
The preferred color developer compounds include those of the 
p-phenylenediamine type described in Table I, and in addition include 
analogous aminophenol compounds. The aminophenol compounds have structures 
according to the following formulas: 
##STR2## 
where S, T and m are as defined above. Here, R, R.sub.1, R.sub.2, R.sub.3, 
R.sub.4, R.sub.5 and R.sub.6 are independently H, halogen, alkyl, alkoxy, 
alkylsulfonamido, acylamido or aryl. Specific examples of such blocked 
aminophenols are listed in Table II. 
Other blocked p-phenylenediamines of this invention include carbamate, 
oxamide, urea, thiourea, trihaloacetamido, perfluoroacyl, hydroxamic acid, 
and Schiff base derivatives. Examples of such blocked p-phenylenediamines 
are listed in Table III. 
TABLE I 
__________________________________________________________________________ 
V Z Y X 
__________________________________________________________________________ 
##STR3## 
1 C(CH.sub.3).sub.2COCH.sub.3 
NHSO.sub.2 CH.sub.3 
2 C(CH.sub.3).sub.2COCH.sub.3 
NHSO.sub.2 CH.sub.2 (CH.sub.2).sub.14 CH.sub.3 
3 C(CH.sub.3).sub.2COCH.sub.3 
H 
4 C(CH.sub.3).sub.2COCH.sub.3 
NHCO(CH.sub.2).sub.3 CO.sub.2 C(CH.sub.3).sub.3 
5 
5 C(CH.sub.3).sub.2COCH.sub.3 
NHCO(CH.sub.2).sub.3 CO.sub.2 H 
6 
##STR4## NHSO.sub.2 CH.sub.3 
7 CH(CH.sub.3).sub.2 H 
##STR5## 
8 C(CH.sub.3).sub.2COCH.sub.3 
NHSO.sub.2 CH.sub.3 
9 C(CH.sub.3).sub.3 NHSO.sub.2 CH.sub.3 
10 
##STR6## H 
11 CH(CH.sub.3).sub.2 NHCO(CH.sub.2).sub.3 CO.sub.2 H 
12 CH(CH.sub.3).sub.2 NHSO.sub.2 CH.sub.3 
13 CH.sub.2 CH.sub.3 NHCO(CH.sub.2).sub.3 CO.sub.2 H 
14 
##STR7## NHCO(CH.sub.2).sub.3 CO.sub.2 H 
15 CH.sub.2 CH.sub.3 
##STR8## 
16 
##STR9## 
##STR10## 
17 
##STR11## NHSO.sub.2 CH.sub.3 
##STR12## 
18 
H CH.sub.2 CH.sub.3 
NHSO.sub.2 CH.sub.3 
##STR13## 
19 
H CH.sub.2 CH.sub.3 
OH 
##STR14## 
20 
H CH.sub.2 CH.sub.3 
H 
##STR15## 
21 
H CH.sub.3 NHSO.sub.2 CH.sub.3 
##STR16## 
22 
H CH.sub.2 CH.sub.2 CH.sub.3 
NHSO.sub.2 CH.sub.3 
##STR17## 
23 
H CH(CH.sub.3).sub.2 
NHSO.sub.2 CH.sub.3 
##STR18## 
24 
H CH.sub.2 CH.sub.3 
NHSO.sub.2 CH.sub.3 
##STR19## 
25 
H CH.sub.2 CH.sub.3 
NHSO.sub.2 CH.sub.3 
##STR20## 
26 
CH.sub.3 
CH.sub.2 CH.sub.3 
NHSO.sub.2 CH.sub.3 
##STR21## 
27 
H 
##STR22## NHSO.sub.2 CH.sub.3 
##STR23## 
__________________________________________________________________________ 
TABLE II 
__________________________________________________________________________ 
Z X R R.sub.1 R.sub.2 
__________________________________________________________________________ 
##STR24## 
28 
C(CH.sub.3).sub.2COCH.sub.3 
NHSO.sub.2 CH.sub.3 
CH.sub.2 CH.sub.3 
29 
C(CH.sub.3).sub.2COCH.sub.3 
NHCO(CH.sub.2).sub.3 CO.sub.2 H 
CH.sub.2 CH.sub.3 
30 
C(CH.sub.3).sub.2COCH.sub.3 
##STR25## CH.sub.3 
31 
##STR26## 
##STR27## CH.sub.3 
32 
CH.sub.2 CH.sub.3 
##STR28## CH.sub.3 
33 
CH(CH.sub.3).sub.2 
NHSO.sub.2 CH.sub.3 
CH.sub.2 CH.sub.3 
34 
CH(CH.sub.3).sub.2 
##STR29## CH.sub.3 
35 
CH(CH.sub.3).sub.2 
##STR30## H 
##STR31## 
36 
CH.sub.3 OCH.sub.3 CH.sub.2 CH.sub.3 
CH.sub.2 CH.sub.3 
37 
CH(CH.sub.3).sub.2 
H CH.sub.2 CH.sub.2 OH 
CH.sub.2 CH.sub.3 
38 
CH.sub.2 CH.sub.3 
NHSO.sub.2 CH.sub.3 CH.sub.3 
CH.sub.3 
39 
CH.sub.2 CH.sub.3 
H CH.sub.2 CH.sub.3 
CH.sub.2 CH.sub.3 
__________________________________________________________________________ 
TABLE III 
__________________________________________________________________________ 
40 
##STR32## 41 
##STR33## 
42 
##STR34## 43 
##STR35## 
44 
##STR36## 45 
##STR37## 
46 
##STR38## 47 
##STR39## 
48 
##STR40## 49 
##STR41## 
50 
##STR42## 51 
##STR43## 
52 
##STR44## 53 
##STR45## 
__________________________________________________________________________ 
The blocked developing agents according to the invention can be 
incorporated in the non-photosensitive layer, for example, as a 
dispersion, including a dispersion of solid particles as described in U.S. 
patent application Ser. No. 07/810,232. Another method is to add the 
blocked developer to a melt as a solution in an organic, water-miscible 
solvent. Other incorporation methods will be readily apparent to those 
skilled in the art. 
In the following discussion of suitable materials for use in the emulsions 
and elements according to the invention, reference will be made to 
Research Disclosure, December 1989, Item 308119, published by Kenneth 
Mason Publications Ltd., Emsworth, Hampshire PO10 7DQ, U.K., the 
disclosures of which are incorporated in their entireties herein by 
reference. This publication will be identified hereafter as "Research 
Disclosure". 
The support of the element of the invention can be any of a number of well 
known supports for photographic elements. These include polymeric films, 
such as cellulose esters (for example, cellulose triacetate and diacetate) 
and polyesters of dibasic aromatic carboxylic acids with divalent alcohols 
(such as polyethylene terephthalate), paper, and polymer-coated paper. 
The photographic elements according to the invention can be coated on the 
selected supports as described in Research Disclosure Section XVII and the 
references cited therein. 
The radiation-sensitive layer of a photographic element according to the 
invention can contain any of the known radiation-sensitive materials, such 
as silver halide, or other light sensitive silver salts. Silver halide is 
preferred as a radiation-sensitive material. Silver halide emulsions can 
contain, for example, silver bromide, silver chloride, silver iodide, 
silver chlorobromide, silver chloroiodide, silver bromoiodide, or mixtures 
thereof. The emulsions can include coarse, medium, or fine silver halide 
grains bounded by 100, 111, or 110 crystal planes. 
The silver halide emulsions employed in the elements according to the 
invention can be either negative-working or positive-working. Suitable 
emulsions and their preparation are described in Research Disclosure 
Sections I and II and the publications cited therein. 
Also useful are tabular grain silver halide emulsions. In general, tabular 
grain emulsions are those in which greater than 50 percent of the total 
grain projected area comprises tabular grain silver halide crystals having 
a grain diameter and thickness selected so that the diameter divided by 
the mathematical square of the thickness is greater than 25, wherein the 
diameter and thickness are both measured in microns. An example of tabular 
grain emulsions is described in U.S. Pat. No. 4,439,520. Suitable vehicles 
for the emulsion layers and other layers of elements according to the 
invention are described in Research Disclosure Section IX and the 
publications cited therein. 
The radiation-sensitive materials described above can be sensitized to a 
particular wavelength range of radiation, such as the red, blue, or green 
portions of the visible spectrum, or to other wavelength ranges, such as 
ultraviolet, infrared, X-ray, and the like. Sensitization of silver halide 
can be accomplished with chemical sensitizers such as gold compounds, 
iridium compounds, or other group VIII metal compounds, or with spectral 
sensitizing dyes such as cyanine dyes, merocyanine dyes, or other known 
spectral sensitizers. Exemplary sensitizers are described in Research 
Disclosure Section IV and the publications cited therein. 
Multicolor photographic elements according to the invention generally 
comprise a blue-sensitive silver halide layer having a yellow 
color-forming coupler associated therewith, a green-sensitive layer having 
a magenta color-forming coupler associated therewith, and a red-sensitive 
silver halide layer having a cyan color-forming coupler associated 
therewith. Color photographic elements and color-forming couplers are 
well-known in the art. The elements according to the invention can include 
couplers as described in Research Disclosure Section VII, paragraphs D, E, 
F and G and the publications cited therein. These couplers can be 
incorporated in the elements and emulsions as described in Research 
Disclosure Section VII, paragraph C and the publications cited therein. 
A photographic element according to the invention, or individual layers 
thereof, can also include any of a number of other well-known additives 
and layers. These include, for example, optical brighteners (see Research 
Disclosure Section V), antifoggants and image stabilizers (see Research 
Disclosure Section VI), light-absorbing materials such as filter layers of 
intergrain absorbers, and light-scattering materials (see Research 
Disclosure Section VIII), gelatin hardeners (see Research Disclosure 
Section X), oxidized developer scavengers, coating aids and various 
surfactants, overcoat layers, interlayers, barrier layers and antihalation 
layers (see Research Disclosure Section VII, paragraph K), antistatic 
agents (see Research Disclosure Section XIII), plasticizers and lubricants 
(see Research Disclosure Section XII), matting agents (see Research 
Disclosure Section XVI), antistain agents and image dye stabilizers (see 
Research Disclosure Section VII, paragraphs I and J), 
development-inhibitor releasing couplers and bleach accelerator-releasing 
couplers (see Research Disclosure Section VII, paragraph F), development 
modifiers (see Research Disclosure Section XXI), and other additives and 
layers known in the art. 
Photographic elements according to the invention can be exposed to actinic 
radiation, typically in the visible region of the spectrum, to form a 
latent image as described in Research Disclosure Section XVIII, and then 
processed to form a visible dye image as described in Research Disclosure 
Section XIX. During processing, the developer precursor compound of 
formula I will generally be solubilized and undergo a sequence of 
reactions to release the color developer. Processing can be any type of 
known photographic processing, although it is preferably carried out at pH 
9 to 14 and includes a nucleophile such as hydrogen peroxide, 
hydroxylamine, perborate, an alkyl peroxide, an aryl peroxide, or a 
compound releasing such nucleophiles. 
In particular, when S is a .beta.-ketoacyl group, the nucleophile is a 
dinucleophile, as discussed in U.S. Pat. No. 5,019,492. When S is a simple 
acyl group, the nucleophile preferably is a peroxide having the structure 
EQU R.sub.6 --OOH 
in which R.sub.6 is H or an unsubstituted or substituted alkyl, aryl, 
alkaryl, aralkyl or acyl group. R.sub.6 can also be a sulfonyl, 
oxycarbonyl or borate group, or any group in general which hydrolyzes 
readily in alkaline solution to yield hydrogen peroxide. Hydrogen peroxide 
is the particularly preferred reagent (hydrogen peroxide is present as a 
salt in alkaline solution, that is, in the form H--O--OM.sup.+, which is 
the active species). 
A negative image can be developed by color development using one or more of 
the aforementioned nucleophiles. A positive image can be developed by 
first developing with a nonchromogenic developer, then uniformly fogging 
the element, and then developing by a process employing one or more of the 
aforementioned nucleophiles. If the material does not contain a 
color-forming coupler compound, dye images can be produced by 
incorporating a coupler in the developer solutions. 
Development is followed by the conventional steps of bleaching, fixing, or 
bleach-fixing, to remove silver and silver halide, washing and drying. 
Bleaching and fixing can be performed with any of the materials known to 
be used for that purpose. Bleach baths generally comprise an aqueous 
solution of an oxidizing agent such as water soluble salts and complexes 
of iron (III) (such as potassium ferricyanide, ferric chloride, ammonium 
or potassium salts of ferric ethylenediaminetetraacetic acid), 
water-soluble dichromates (such as potassium, sodium, and lithium 
dichromate), and the like. Fixing baths generally comprise an aqueous 
solution of compounds that form soluble salts with silver ions, such as 
sodium thiosulfate, ammonium thiosulfate, potassium thiocyanate, sodium 
thiocyanate, thioureas, and the like. 
The invention is further illustrated by the following examples, without 
being limited thereby. 
EXAMPLE 1 
Three .beta.-ketoacyl blocked developers (nos. 6, 8 and 16) were dispersed 
in di-n-butylphthalate (DBP) such that the ratio developer:DBP:ethyl 
acetate was 1:1/2:1 1/2, and the dispersion was 3% developer and 4% 
gelatin. The dispersions were used unwashed. 
The .beta.-ketoacyl blocked developer dispersions incorporated in the 
non-photosensitive layer of the monochrome tri-layer test format shown in 
Table IV below. The emulsion-containing layer contained image coupler A 
and a green sensitized bromoiodide emulsion. 
TABLE IV 
______________________________________ 
##STR46## 
______________________________________ 
DOC Gelatin (5375 mg/m.sup.2) 
1,1'-(oxybis(methylenesulfonyl))bis-ethene 
hardener (2% of total gelatin) 
saponin (1.5% melt volume) 
EMULSION Gelatin (2152 mg/m.sup.2) 
LAYER Coupler A (806 mg/m.sup.2) 
green sensitized AgBrI emulsion, 6.4 mol % 
iodide, with mean particle size 0.46 .mu.m 
(1613 mg/m.sup.2 as Ag) 
saponin (1.5% melt volume) 
UNDERLAYER Gelatin (2688 mg/m.sup.2) 
ketoacyl blocked developer (1.12 or 
2.24 mmol/m.sup.2) 
saponin (1.5% melt volume) 
FILMBASE 
______________________________________ 
Coatings were exposed and processed at 100.degree. F. using a development 
step of 4 mins. in pH10 potassium carbonate buffer with or without 2.41 
g/L of hydroxylamine sulphate (HAS). The remainder of the process was 
according to a C41 protocol modified to include a stop bath. 
Sensitometric results are shown in Table V below. 
TABLE V 
__________________________________________________________________________ 
BLOCKED LEVEL Dmax-no 
DEVELOPER 
mmol/m.sup.2 
Dmin 
Dmax 
Contrast.sup.(a) 
Speed.sup.(b) 
HAS 
__________________________________________________________________________ 
check -- 0.04 
0.05 
0.02 -- 0.04 
6 1.12 0.09 
0.50 
0.29 165 0.04 
2.24 0.15 
0.84 
0.58 139 0.04 
8 1.12 0.09 
0.57 
0.34 191 0.04 
2.24 0.15 
0.93 
0.57 181 0.09 
16 1.12 0.12 
0.76 
0.46 200 0.04 
2.24 0.17 
1.15 
0.78 190 0.04 
check -- 0.04 
0.05 
0.03 -- 0.04 
__________________________________________________________________________ 
.sup.(a) Contrast is defined as the maximum slope between any two density 
points which are two steps apart. 
.sup.(b) Speed is defined as the exposure at which the density above Dmin 
is 20% of the average gradient from that point to 0.6 log E greater 
exposure. 
No coating processed using potassium carbonate solution alone gave a Dmax 
greater than 0.1. The absence of any substantial development of dye in the 
absence of HAS demonstrates the stability of the blocked developers. 
COMATIVE EXAMPLE 1 
Blocked developers 6 and 8 were dispersed in DBP as in Example 1. The 
blocked developer dispersions were then incorporated into the emulsion 
layer of a monochrome bi-layer test format similar to the upper two layers 
of the test format in Table IV. The bi-layer test format is shown in Table 
VI below. 
TABLE VI 
______________________________________ 
DOC Gelatin (5375 mg/m.sup.2) 
1,1'-(oxybis(methylenesulfonyl))bis-ethene 
hardener (2% of total gelatin) 
saponin (1.5% melt volume) 
EMULSION Gelatin (3225 mg/m.sup.2) 
LAYER Coupler A (806 mg/m.sup.2) 
green sensitized AgBrI emulsion, 6.4 mol %, 
with mean particle size 0.46 .mu.m (1613 
mg/m.sup.2 as Ag) 
ketoacyl blocked developer (1.12 or 
2.24 mmol/m.sup.2) 
saponin (1.5% melt volume) 
FILMBASE 
______________________________________ 
Coatings were exposed and processed as in Example 1. Sensitometric results 
are tabulated in Table VII below. 
TABLE VII 
__________________________________________________________________________ 
BLOCKED LEVEL Dmax-no 
DEVELOPER 
mmol/m.sup.2 
Dmin 
Dmax 
Contrast 
Speed 
HAS 
__________________________________________________________________________ 
check -- 0.05 
0.07 
0.02 -- 0.04 
6 1.12 0.11 
0.43 
0.28 150 0.06 
2.24 0.17 
0.70 
0.44 148 0.09 
8 1.12 0.09 
0.44 
0.29 155 0.08 
2.24 0.13 
0.81 
0.54 148 0.14 
check -- 0.05 
0.07 
0.02 -- 0.04 
__________________________________________________________________________ 
The differences in Dmax, contrast (DOG) and speed between the two coating 
formats are given in Table VIII, below. A positive value indicates that 
the response was greater when the blocked developer was incorporated in 
the non-photosensitive underlayer below the emulsion layer. 
TABLE VIII 
______________________________________ 
BLOCKED LEVEL Con- Dmax-no 
DEVELOPER mmol/m.sup.2 
Dmax trast 
Speed HAS 
______________________________________ 
check -- -0.02 -- -- 0.0 
6 1.12 0.07 0.01 15 -0.02 
2.24 0.14 0.14 3 -0.05 
8 1.12 0.13 0.05 36 -0.04 
2.24 0.12 0.03 33 -0.05 
check - -0.02 0.01 -- -- 
______________________________________ 
Incorporation of blocked developers in photographic elements according to 
the present invention enables dye formation with simple developing 
solutions, with the potential for an increased rate of development in 
lower layers due to generation of high local concentrations of color 
developer. 
It is to be understood that the foregoing detailed description and specific 
examples, while indicating preferred embodiments of the present invention, 
are given by way of illustration and not limitation. Many changes and 
modifications within the scope of the present invention may be made 
without departing from the spirit thereof, and the invention includes all 
such modifications.