CA1178477A - Photographic recording material having a thin agx layer of high packing density sandwiched between colour coupler containing layers - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

In a photographic recording material, a light-sensi-tive silver halide emulsion layer which is relatively thin and has a high packing density is situated between layers which contain colour couplers and are either free from silver halide or contain a relatively low speed silver halide.

Description

1 ~7~

Photographic recording materlal This invention relates to a photographic recording material comprising several silver halide emulsion layers and containing colour couplers. At least one silver halide emulsion layer is situated between layers which contain colour couplers and are either free from light-sensitive silver halide or contain relatively light-insensitive silver halide. The invention also relates to a process for the production of photographic images by imagewise exposure and development of the material according to the invention.
For the production of colour photographic images, it is known to use recording materials containing a red-sensitive, a green-sensitive and a blue-sensitive silver halide emulsion layer on a layer support, each of the said silver halide emulsion layers containing non-diffusible colour couplers to produce, respectively, the cyan, magenta and yellow partial colour images, the colour of each partial colour image produced being complementary to the spectral sensitivity of the corresponding silver halide emulsion layer. Conventional colour photographic material also contain additional layers such as, for example, a yellow filterlayer between the blue-sensitive silver halide emulsion layer above it and the green-sensitive silver halide emulsion layer below it and an antihalation layer between the support and the lowermostsilver halide emulsion layer. Additional intermediate layers of gelatine and covering layers may also be provided.
It is also known to use recording material for the production of colour photographic images in which two silver halide emulsiGn layers are provided for the production of each of one or more of the three different partial colour images. Thus, for example, according to British Patent No. 818,687, the lowermost light-sensitive colour-producing layer unit of a colour photographic 117~ 7

- 2 -multilayered material consicts of two partlal layers which are sensitized to light of the same region of the spectrum and contain silver halide and colour coupler, the upper of these two layers having the greater 5 speed.
The use of such double layers with dif~ering speed in which the faster layer produces the lower colour density on colour development is known from German Patent No. 1~121~470. It provides the possi-bility of incraasing the speed without at the sametime adversely affecting the graininess. See also US Pater.t No. 4rl73r479 and the literature quoted there.
The increased standards demanded of photographic recording materials require a material which combines high speed with sharpness and improved graininess.
From US Patent No. 4~04Q~829 (German Offenlegung-sschrift No. 2 r524 ~835) ~ it is known that the sharpness OL
colour photographic images can be improved by accommodating colour couplers-and silver halide in different layers of photographic material. In this method, the thickness of the silver halide emulsion layer is reduced and a colour coupler with limited capacity ~or diffusion is used. The use of colour couplers with limited diffusion capacity has also been disclosed in US Patent No. 2~546~400.
From German Auslegeschrift No. 1~002~626 (British Patent No. 818/233) 1 it is known that improved colour separation is obtained in colour photographic materials if a gelatine layer containing a colour coupler is arrar.ged between adjacent emulsion layers containing colour co~plers.
Such gelatine layers cor.taining colour couplers may be arranged above and below the associated silver halide emulsion layer. German Offenlegungsschrift No. 2~650~715 (US Patent No. 4 / 186,011) discloses a colour photographic recording material comprising a silver halide emulsion layer which is subdivided into two or more partial layers with dif~ering speed. A layer of binder containing , ~, 7~4';;'7 colour coupler and free from silver halide is arranged immediately above the more sensitive silver halide emulsion layer. The said layer of binder has a high concentration of colour couplers and may be kept very thin. United States Patent No. 2,350,380 discloses colour photographic recording materials having a silver halide emulsion layer and adjacent thereto at least one other layer containing a colour-producing compound. This layer preferably has a thickness of 1.5 to 5.0 ,u. The silver halide emulsion layer generally has a thickness of 2.0 to 6.0 ~.
It is also known to use layers containing a relatively low proportion of gelatine to silver in photographic recording materials. United States Patent No. 3,372,030, for example, discloses a colour photographic recording material in which the individual layers are generally no thicker than 4 ~ and the gelatine/silver ratio is about 1. In this material, the colour couplers are embedded in the silver halide emulsion layer in order to be as close as possible to the silver halide grains. British Patent No. 531,243 also discloses materials having a relatively low gelatine/silver halide ratio, but these do not contain colour couplers.
It is an object of the present invention to provide an improved photographic material in which the sharpness and colour graininessare improved, in particular at a higher speed.
According to one aspect of the present invention there is provided a photographic material having at least one light-sensitive silver halide emulsion layer for each of the red, green and blue spectrai region wherein at least one emulsion layer E
is enclosed by associated layers K containing at least one color ;~ - 3 -.

'` ~17~

coupler wherein at least one layer K i9 arranged in a water-permeable relationship above layer E and at least one layer K is arranged in a water-permeable relationship below E, said layers X containing no silver halide or only silver halide having a speed to blue light which is less by a factor of at least S0 than that of the image-recording blue-sensitive layer and said layer E being relatively thin and having a silver halide packing density of at least 1Ø
The silver halide packing density is the ratio of silver contained in a layer (calculated as grams of silver nitrate) to the dry volume of this layer (calculated in cm3).
According to another aspect of the present invention there is provided a process for the production of photographic images by im~!gewise exposure of a photographic material and development with a p-phenylenediamine developer compound, wherein a photographic material as defined above is used.
In a preferred embodiment, layer E has a thickness of at the most 1.5 ~u. The binder/silver ratio in this embodiment is at most 0.4. This binder/silver ratio is defined as the quotient of binder, e.g. gelatine, in grams to the silver contained in it, calculated as grams of silver nitrate.
The colour coupler-containing layers K generally con-tain a binder, preferably gelatine, in addition to the colour coupler. A layer X may contain several colour couplers, and a layer K arranged above the silver halide emulsion layer E
may contain the same colour couplers as layer K below layer ~, or ine two layers associated with layer E may contain different colour couplers, which when reacted with oxidized colour developer under conditions of development may give rise ' .

~17~4~Y7 to the same colour, a similar colour or a completely different colour. The latter is appropriate if, for example, only black-and-white dye images are to be produced.
As already indicated above, the layers ~ containing colour couplers are either free from silver halide or contain only silver halide with comparatively low speed. If a compara-tively low speed silver halide is used, this may contain AgC1, AgBr, AgI or mixtures thereof. It is preferred to use a non-sensitized silver halide emulsion containing at least 20 mol %
of silver chloride. It is particularly preferred to use silver halide emulsions in which the silver halide grains have an average grain diameter of less than 0.5 ,um. These include silver halide emulsions which are known under the term of mikrat emulsions or Lippman emulsions and ha~e an average grain diameter of less than 0.1 ,um. Such emul-- 4a -117~77 sions have relatively little sensitivity to light. The speed of these silver halide emulsions to blue light is preferably less by a factor or at least ~0 than that of the image-recording blue-sensitive layer.
Such a silver halide emulsion with comparatively low speed is not intended to record an lmage but may have an advantageous effect on the adjacent image-recording layers. Such comparatively insensitive silver halide emulsions may also be present in the silver halide emulsion layers E in addition to the light-sensitive -- silver halide.
In a preferred embodiment, the silver halide emulsion layer E is free from colour coupler and has a thickness of preferably not more than 2.0 ,u, in particular not more than - 15 1.2 ~ and a binder/silver ratio as defined above of pref-erably not more than 0.4, in particular not more than 0.2.
The packing density is preferably at least l.5 and in particular at least 2Ø
In another preferred embodiment, the silver halide emulsion E also contains at least one colour coupler, but this is generally not so reactive as the most highly reactive colour coupler in the associated layers K. A measure of -~ the reactivity is the reaction velocity constant of couplingof the colour coupler with the oxidation product of the colour developer. Such velocity constants may be measured by known methods as indicated, ~or example, in the publication by J. Eggers in "Mitteilungen aus den Forschung-slaboratorien der Ag~a", Leverkusen-Munchen, Volume III, 1961, page 81 et seq. The velocity constant of the coupling ~- 30 reaction of the colour couplers contained in the layers K
is preferably greater by a factor of at least 2, in particular by a factor of 5, than that of the colour couplers contained in the silver halide emulsion layer E.
In this embodiment, the silver halide emulsion layer E
again has a high packing density, generally containing 0.5 gram of coupler to 1 gram of silver halide. ~hen . ~ .

1178~

conventional colour couplers and conventiGnal hydrcphilic binders are used in this embodiment, the silver halide packing densities in layer E are preferably at least 0.7, in particular at least 0.9. Furthermore, in this embodiment, ; 5 the silver halide emulsion layer has a maximum thickness of at most 3.S ~1, preferably not more than 2.8 ,u, and a binder/
silver ratio of not more than 0.4, in particular not more than 0.2. The maximum thickness of the colour coupling containing layers K in this embodiment is preferably at most 3.0 ,u, more particularly not more than 2.5 ,u. The - figures given for the thickness of the layers are based on the layers in the dry state. In order to obtain as thin layers as possible when dry, the proportion by weight of ballast materials to colour couplers in the layers K generally does not exceed the value 1 in the dry state. The ballast material is taken to be the sum of binders, oil formers, plasticizers and other additives.
The thickness of the coupler layers is preferably chosen so that the colour developer oxidation product leaving the emulsion layer E in the course of colour develop-ment will still completely react in these coupler layers even in the case of maximum colour density without migrating to any significant extent into adjacent layer elements which couple to form different colours and with-out substantial quantities of unreacted coupler, not con-verted into dye, being left behind in the case of maximum colour density.
Both emulsion layers E and coupler layers K may contain mixtures of different colour couplers as well as masking couplers, DIR couplers ar.d the like.
Layers K containing colour couplers are associated with the silver halide layer E in such a manner that, under the conditions of photographic development, the oxidation products of colour developer leaving layer r react virtual-ly completely in layers K with the colour couplers presentthere. It is for this reason that layers K containing colour couplers are in a "water-permeable relationshlp"
with silver halide emulsion layer E. In a preferred embodiment, layers K are therefore arranged directly adjacent to the silver halide emulsion layer E although intermediate layers, ~or example of gelatine, can be arranged ; between layers E and K.
The colour photographic recording materials usually contain one silver halide emulsion layer unit for each of the three spectral regions red, green and blue to record, in each case, the light from these spectral regions. The light-sensitive layers are therefore spec-trally sensitized by suitable sensitizing dyes in known manner. The blue-sensitive silver halide emulsion layer unit need not necessarily contain a spectral sensitizer since the intrinsic sensitivity of silver halide is in many cases sufficient for recording the blue light.
Each of the above mentioned silver halide emulsion layer units may contain a single silver halide emulsion layer or it may, as is known, contain two or more silver halide emulsion layers, e.g. in a so-called double layer arrangement. Colour photographic recording mater-ials having double layers for the various spectral regior.s have been disclosed, for example, in US Patents No.

3,663,228 and No. 3,849,138. In thece materials, the upper of the two partial layers which are sensitive to the same spectral region has the higher speed.
Another suitable layer arrangement with double layers has been disclosed in German Offenlegungsschrift No. 2,530,645 (VS Patent No. 4,18~,876), in which the red-sensitive and green-sensitive layers of equal speed are in each case combined. The red-sensitive silver halide emulsion layer units are usually arranged closer to the layer support than the green-ser.sitive silver halide emulsion layer unit, which in turn is situated closer to the support than the blue-sensitive layers, and a light-insensitive yellow filter layer is generally '7 arranged between the green sensitive layers and the blue sensitive layers, although different arrangements are conceivable. A light-insensitive intermediate layer is generally interposed between layers of diEEerent spectral sensitivities. Such an intermediate l~yer m~y contain a scavanger for preventing a~errant dlf~usion of developer oxidation products.
Preferred arrangements of layers E and ~ in relationship to each other are illustrated in Figures 1 to ---Io 5. In Fig.l, a silver halide emulsion layer E 1 is enclosed by the two colour coupler-containing layers K 1 and X 2. In Fig.2, the silver halide emulsion layer E
is split up into two partial layers E 21 and E 22 which have the same spectral sensitivity but differ in their lS speed. The silver halide emulsion layers are enclosed by the colour coupler layers K 21 and K 22 and, respectively, K 22 and K 23. As shown in Fig.3, however, the silver halide emulsion layer E may also be split up into directly adjacent partial layers E 31 to E 33, and layers E 33 and E 31, for example, may contain relatively fine silver halide grains while layer E 32 contains relatively coarse silver halide grains. Layers K 31 and K 32 which contain colour couplexs then enclose the packet cf emulsion layers. According to Fig. 4, several colour couplers containing layers (K 41 to K 44) may be arranged on the two sides of the silver halide emulsion layer E 40. Fig.5, shows an asymmetric structure in which a silver halide emulsion layer E 50 is enclosed on one side by a colour coupler-containing layer K 53 and on the other side by colour coupler-containing layers K 52 and K 51.
The non-diffusible colour couplers associated with the light-sensitive silver halide emulsior. layer units may in principle be any type of non-diffusible compounds from which, with suitable treatment (development), image dyes having the required spectral and sensitometric properties can be produced. When a colour coupler is said to be associated with a silver halide emulsion laye., 11'7~ 7 g this means that under the conditions of photographic development it reacts with the developer oxidation product produced in the given silver halide emulsion layer. In the arrangement according to the invention, therefore, this applies to the colour couplers contained in the emulsior. la~er E and in the associated layers K.
Each of the above mentioned light-sensitive silver halide emulsiGn layers preferably has associated with it a non-diffusible colour coupler which is capable of reacting with colour developer oxidation products to form a non-diffusible dye.
The colour couplers associated with or.e o~ possibly more than one partial layer of the same spectral sensitivity ` need not necessarily be identical. In general, they are merely required to give rise to the same colour in the course of colour development, normally a cOlour which is ~ complementary to the colour of the light to which the '; associated light-sensitive silver halide emulsion layers : are sensitive. Each of the red-sensitive silver halide emulsion layers therefore has associated with it at least one non-diffusible colour coupler to produce the cyan partial colour images, generally a coupler of the phenol or ~-naphthol series. Associated with each green-sensitive silver halide emulsion layer is at least `one non-diffusible colour coupler to produce the magenta partial colour image, usually a colour coupler of the 5-pyrazolone or the indazolone series. Associated with each blue sensitive silver halide emulsion layer is at least one non-diffusible colour coupler to produce the yellow partial colour image, generally a colour coupler having an open-chain keto methylene group. ~ifferent associations between emulsion layers and colour couplers, however, can also be used for special purposes. Colour couplers of this type are known in large numbers and have been described in numerous patent specifications. 2eference may be had, for example, to the publication "Farbkuppler" by 1178~ 7 - 10 _ W.Pelz in "~litteilungen aus den Forschungslaboratorien der Agfa, Leverkusen/Munchen", Volume III, page 111 ~1961) and K. Venkataraman in "The Chemistry of Synthetic Dyes", Vol.4, 341 to 387, Academic Press (1971).
The colour couplers may be either conventional

4-equivalent couplers or 2-equivalent couplers which require a smaller quantity of silver halide to produce the colour.
2-Equivalent couplers are derived, as is known, from 4-equivalent couplers in that they contain in the coupling position a substituent which is split off in the coupling reaction. The 2-equivalent couplers suitable for the present invention include both couplers which are virtually colourless and couplers which have an intense colour of their own which disappearsin the process of colour coupling or is replaced by the colour of the image dye produced. According to the invention, the last mentioned couplers may in addition be present in the light-sensitive silver halide emulsion layers to serve as masking couplers which com~ensate for unwanted absorption of light by the image dyes. ~he 2-ecuivalent couplers also include t~e kncwn " white couplers although these produce no dye when reacted with colour developer oxidation products. 2-Equivalent couplers also include the known DIR couplers, which contain `- a releasable group in the coupling position so that, when the coupler reacts with colour developer oxidation products, this group is released as a diffusible development inhibitor.
The colour couplers may be used as mixtures if required to produce a particular colour shade or particular reactivity. Water-soluble couplers, for example, may be used in combination with hydrophobic water-insoluble couplers.
The silver halide emulsions may be prepared either by single nflow or by double inflow. Suitable methods of this type have been described, for example, in British Patent Nc. 1,027,146 and in the publication by E. ~loisar and S. Wagner in "Berichte der Bunsengesellschaft fur physikalische Chemie", 67 (1963), pages 356 to 359. It 117~ ~ 7 is also possible to prepare coarser grained emulsions by redissolving fine grained starting emulsions in the pre-sence of silver complex formers and in the presence o~
suitable peptising agents. Such methods have been dis-closed, for example, in US Patents No. 2,146,938, No.
3,206,313 and No. 3,317,322 and German Auslegeschrlft No.
1,207,791.
Both emulsions with a narrow grain size distribution and those with a relatively wide grain size distribution may be used, e.g. both homodisperse and heterodisperse silver halide emulsions.
The term "homodisperse emulsions" is used to denote emulsions having a narrow grain size distribution, preferably at least 95% of the silver halide grains having a diameter which deviates by not more than 40~, preferably not more than 20%, from the average grain diameter.
The silver halide grains may have any of the known forms, e.g. they may be cubical, octahedric or mixed tetradecahedric.
- The term "heterodisperse emulsions" means in parti- cular emulsions in which at least lO~, preferably at least 20%, of the silver halide grains have a diameter which deviates from the average grain diameter by at least 40%.
Silver halide grains of such emulsions generally have an irregular form.
The silver halide grains in layer E preferably have a size of at the most 1.5 ,u; their minimum size is generally about 0.1 ~.
To remove the water-soluble salts, the silver halide emulsions may either be solidified, shredded or washed in known manner after the addition of gelatine or they may be coagulated with a coagulating agent and ther. washed, for example as disclosed in German Offenlegungsschrift ~o.
2,614,862.
The photographic materials may be developed with the 1178~'77 usual colour developer substances, e.g. N,N-dimethyl-p-phenylene diamine, 4-amino-3-mcthyl-N-ethyl-N-methoxy-ethylaniline, 2-amino-5-diethylaminotoluene, N-butyl-N-~-sulphobutyl-p-phenylenediamine, 2-amino-5-(n-ethyl-N-~-methanesulphonamidoeth~1-amino)-toluerle, N-ethyl-N-~-hydroxyethyl-p-phenylenediamine, N,N-bis-(~-hydroxy-ethyl)-p-phenylenediamine and 2-amino-S-(N-ethyl-N-~-hydroxyethylamino)-toluene. Other suitable colour developers have been described, for example, in J. Amer.
Chem.Soc. 73, 3100 (1951).
The binder used for the layers is preferably gelatine although this may be partly or completely re-placed by other natural or s~nthetic binders.
The emulsions may also be chemicallysenzitized, e.g. by the addition cf sulphur compounds such as allyl isothiocyanate, allylthiourea or sodium thiosulphate at the stage of chemical ripening. Reducing agents may also be used as chemical sensitizers, e.g. the tin compound described in Belgian Patents Nos. 493,464 and 568,587, or polyamines such as diethylenetriamine or aminomethylsulphinic acid derivatives, e.s. according to Belgian Patent No. 547,323. Noble metals such as gold, platinum, palladium, iridium, ruthenium or rhodium and compounds of such metals are also suitable chemical sensiti-ers. The emulsions may also be sensitiGed with polyalkylene oxide derivatives, e.g. with a polyethylerle oxide having â molecular weight of from lOOO to 20,000, or with condensation products of alkylene oxides and alcohols, aliphatic carboxylic acids, aliphatic amines, aliphatic diamines and amides.
The emulsions may also be optically sensitized, e.g. with the usual polymethine dyes such as neutro-cyanines, basic or acid carbocyanines, rhodacyanines, hemicyanines, styryl dyes, oxGnoles and the like. Such sensitizers have been described in the work by F.~1.Hamer, ` ~784'77 ~` "The Cyanine Dyes and related Compounds" (1964).
The emulslons may ln addition contaln the usual ` stabilizers, e.g. homopolar or salt ty~e c~mpounds of mercury containing aromatic or heterocyclic rings, such as

5 mercaptotriazoles, simple mercury salts, sulphonium mercury double salts or other mercury compoun~ls. Particularly suitable stabilizers are the azaindenes, particularly tetra- and pentaazaindenes and e~pecially t:hose which are su~stltuted with hydroxyl or amino groups. Compounds of this type ~, 10 have been described e.g. in the article by Birr, Z.Wiss.Phot.
-` 47 (1952), 2 to 58. Suitable stabilizers are also inter alia heterocyclic mercapto compounds, e.g. phenylmercapto-tetrazole, quaternary benzothiazole derivatives and benzotriazole.
The layers of photographic material may be hardened ~ in the usual manner, ~or example with formaldehyde cr halogen-substituted aldehydes containg a carboxyl group, such as mucobromic acid, diketones, methanesulphor~ic acid esters, dialdehydes and the like. The photographic layers may also be hardened with epoxide hardeners, heterocyclic ethylene imine hardeners or acryloyl hardeners.
They may also be hardened by the process according to German Offenlegungsschrift No. 2,218,009 to produce colour photographic materials suitable for high temperature c 25 processing. The photographic layers or colour photographic multilayered materials may also be hardened with hardeners of the dia~ine, triazine or 1,2-dihydroquinoline series.
Examples of such hardeners include diazine derivatives containing alkylsulphonyl or arylsulphonyl groups, derivatives of hydrogenated diazines or tria ines, e.g. 1,3,5-hexahydro-triazine, fluoro-substituted diazine deri~,-atives. e.g. fluoro-pyrimidine, and esters of 2-substituted 1,2-dihydroquinoline-or 1,2-dihydroisoquinoline-N-carboxylic acids. Vinyl sulphonic acid hardeners and carbodiimide or carbamoyl hardeners are also suitable, e.g. those described in German Offenlegungssch-riften No. 2,263,602, No. 2,225,230 and No. 1,801,685, French , , ' ' ~

' , :

, '7~'7~

Patent No. 1,491,807, German Patent No. 872,153 and DDR
Patent No. 7218. Other suitable hardeners have been described, for example, in British Patent No. 1,268,550.

Examples ',~
; 5 The following colour couplers are used in the .` Examples described below:
.
Colour Coupler No.l ,.~

.~ Cl ~ NH-CO-CH-O ~ C~3 Cl CH3-C-CH3 ,,, CX2 , .
, ~ Colour CouPler No.2 . OH
`~ 10 C3F7-co-NH ~ ,CH3 NH-CO-CH-O ~ -C-CH2-CH3 4 9 r CH3 ,CH2 : CH3 117~4'~7 Colour_CouPler No.3 ~__<C1 ~ NH-C-CH
'~ C1 4H29-CO-NH /y N C=O
\N~
Cl ~ C1 ~ I 11 ~Y

Colour CouPler No.4 :-C15H31 ~ C2H5 ~~ O-CH-CO-NH-C - CH
~==J // ~ 2 N C=O
\N/

Cl ~ CH3 Colour Coupler No.5 CH3 l 16H33 H-co-NH r~ ~

~ ~ COXH3 S02-NH-CH3 -11784';i 7 Arrangements of l~yers are described ln the follow-ing Examples. ~he quantitles given refer in each case to 1 m of layer support used unless otherwise indicated.
The amount of silver applied is given in terms of the corresponding quantities of silver nitrate. The thicknesses of the layers are those found in the dry state unless otherwise indicated.

Example 1 The following layers are applied to a layer support irl the sequence given:

LaYer K 1 containinq colour coupler This layer contains 800 mg of colour coupler No.l emulsified with a total of 320 mg of oil formers. The layer also contains 160 mg of gelatine and binder. Small quantities Of polystyrene $ulphonic acid and a wetting agent were added to the casting solution used to prepare the layer.

Emulsion layer E

This layer contains 2140 mg of a silver iodobromide emulsion (6 mol% silver iodide) with the silver halide grains having an average grain size of 0.8 ~1. The silver halide emulsion is red-sensitized and stabilized with a tetraazaidene. Emulsion layer E also contains 530 mg of colour coupler No.2 emulsified with a total of 215 mg of oil fornmer and 460 mg of gelatine as binder. In addition, the layer contains small proportions of polystyrene sulphonic acid and a wetting agent.

Layer K 2 containing colour coupler This layer is identical to layer K 1 described ab~ve.

`` 1178477 The various layers ~ere cast simultaneously ih a so-called cascade arran~ement. The thicknesses of the layers after drying are as follows:

Layer 1 1.3 1,l Layer 2 1.6 ,u Layer 3 1.3 ~u The material was hardened in the usual manr.er and subjected to a colour negative process as described in "The British Journal of Photograph~", 12, 1974, pages 597 to 598.
; Another material was prepared for comparison.
; This contained the same substances in the same concen-trations as the material according to the invention but the castirlg solutions used for preparing the various layers were mixed together before they were applied to the layer support so that only one layer was formed. This material was processed in the same manner as the material according to the invention. The results shown in Table 1 below were obtained:
- 20 Table 1 ~aterial Graininess (~Dx102) at density D Speed max D=o.5 D=l D D=1.5 D-2.0 D=2.5 Invention 5.3 6.5 6.0 5.6 5.0 25.8 2.58 Comparis- 5.5, 8.9 10.2 11.0 11.8 26.3 2.87 Inreasing the speed by 3 units a nounts tc ~ doubling the speed. For a definition and method of determining the graininess, see Ullmanns Enzyklopadie der techni-schen Chemie, 4th Edition, 1979, pages 412 et seq.
Table 1 shows that a marked improvement in graini-ness at virtually the same speed is obtained in the ma-terial according to the invention.

:

~17t3~77 ~ 18 -Example 2 The following layers are applied to a layer support in the sequence given;

Layer K l containinq colour couPler This layer contains 600 mg of colour coupler No.3 emulsified with a total of 240 of oil former. In addition, the layer contains 120 mg of gelatine and small quantities of polystyrene sulphonic acid and a wetting agent.

.
Layer K 2 containinq colour couPler This layer is identical to layer K l except that colour coupler No.3 is replaced by 450 mg of the slower - nagenta coupler No.4.

Emulsion laYer E

This layer contains 1500 mg of a silver iodobromide emulsion (8 mol ~ iodide) with an average grain size of the silver halide grains of 0.7 ~u. The silver halide grains are sensitized to green and stabilized with a tetraazaidene. Layer E also contains 500 mg of the slow magenta coupler No.4, 200 mg of oil- former for the colour coupler and a total of 470 mg of gelatine as binder.

Layer K 3 containinq colour couPler This layer contains 800 mg of colour coupler No.3 emulsified with a total of 320 mg of oil former. In addition, the layer contains 160 mg of gelatine as binder and small quantities of polystyrene sulphonic acid and of a wetting agent.

117~7~7 The assembled layers are hardened with a conventional wetting agent. The layers have the following thicknesses after drying:
: K l: l.O ~u ; 5 K 2: O.9 ,u :~ E : l.l ,u ~` K 3: 1.3 ,u A material is prepared for comparison, containing the same substances in the same quantities as the mater-ial according to the invention but in which the castingsolutions for the individual layers were mixed before being cast on the layer support so that there is only one ; Gverall layer.
The materials were exposed imagewise and subjected to reversal processing in which they were treated with the follo~ing baths:
' Bath Time Temperature (min) (C) First developer 6 38C
Washing 2 "
Fogging bath 2 "
Colour developer 6 Conditioner 10 Bleaching bath 6 "
Fixing bath 4 "
Washing 2 The compositions of the baths were substantially as described ir. the Manual for Processing Kodak Ekta-chrome Films Using Process E-7, Eastman Kodak Company, 1977, The following results were obtained:

117~'77 Table 2 .`~laterial Graininess (~Dx102) at density G Speed D
D=0.5 D=l.0 D=1.5 D=2.0 D=2.5 max Invention 3.8 4.2 3.8 3.6 3.5 23.8 2.85 Comparis- 4.0 5.8 7.0 7.5 7.8 24.0 3.2 The Table shows that a significant improvement in the graininess is achieved with the arrangement according to the invention.

Example 3 The following layers were applied to a layer support ir. the given sequence in accordance with Fig.6:
1 Antihalation layer This layer contains 1800 mg of gelatine and 400 mg of Ag (= 618 mg AgN03) per m .

2. LaYer K (cY) 1 containinq colour coupler This layer contains 1300 mg of colour coupler No.l emulsified in a total of 500 mg of an oil former~ The layer also contains 260 mg of gelatine as binder and small quantities of polystyrene sulphonic acid and a wetting agent. The thickness of the dry layer is 2.1 ~.

3. Silver halide emulsion layer 3 (cY) This layer contains 2500 mg of a silver iodobromide emulsion (6 mol ~ silver iodide, average grain size 0.8 ~) which is red-sensiti~ed and is stabilised w~th an azaindene.
The layer also contains 640 mg of colour coupler No.2 -, ~, 117~'77 ; em~ulsified in 250 mg of oil former. The layer containsa total of 550 mg of gelatine as bin~er. It also contains 80 mg of a red correction mask and 40 mg of a DIR coupler. me thickness of the layer is 2.1 ~.

4. Layer K (cy) 2 containing colour coupler This layer contains 800 mg of colour coupler ~o. l emulsified in a total of 300 mg of oil former. The layer also contains 160 mg of gelatine as binder and small quantities cf pclystyrene sulphonic acid and wetting agent.
The thickness of the layer is l.3 ,u.

5. Layer K (mq) l containing cc]our couPler This layer contains lO00 mg of the fast magenta coupler No.3 emulsified in 500 mg of oil former. The layer also contains 250 mg of gelatine and small quantities of polystyrene sulphonic acid and a wetting agent. The thickness of the layer is l.8 ~.

- 6. _ Silver halide emulsion layer E (mq) -This layer contains 1700 Mg of a silver iodobronlide emulsion containing 8 mol ~ of silver iodide and having an - 20 average grain si e of 0.7 ~. The layer is green-sensitized and stabilised with an azaindene. The layer also contains 540 mg of the relatively slow magenta coupler No.4, 270 mg of oil former and lO0 mg of a yellow mask and 60 mg of a DIR
coupler. The layer contains a total of 520 mg of gelatine as binder. The thickness of the layer is l.6 ,u.

., 'i, 117~7

7. LaYer ~ (mq) 2 containlnq colour couPler This layer is identical in composition and thickness to layer K (mg) 1 indicated under 5.

8. Filter layer F

This layer contains colloidal silver having a yellow density of D - 0.8 measured behind a blue filter. Dry layer thickness 0.6 ,u.

9. Layer K ~y) 1 containinq colour coupler This layer contains 800 mg of yellow coupler No. 5,

10 emulsified with 300 mg of gelatine without oil former. The layer also contains small quantities of polystyrene sulphonic acid and wetting agents. The thickness of the layer is 1.1 I~.

10. Silver halide emulsion laYer E (Y) This layer contains 1800 mg of a silver iodobromide emulsion containing 2 mol ~ of silver iodide and having an average grain size of 1.0 ,u. The layer is spectrally sensitized to blue and stabilised with an azaindene.
The layer also contains 800 mg of the yellow coupler indicated in layer 9 which has been emulsified without oil former, - 20 and a total of 650 mg of gelatine. The thickness of the layer is 1.8 ~.

11. Layer K (y~ 2 containin~ colour coupler .' This layer has the same thickness and composition as layer K (y) 1 indicated under 9.

1171~4~'~

12. Protective qelatine layer havinq a drY laYer thic~ness of 0.5 ~

The material described is hardened in the usual manner.
For comparison, a material is prepared as in Examples S 1 and 2 but in this case the casting solutions of the partial layers of each colour element (cy = cyan, mg = magenta and y =
- yellow) are mixed together in the proportions in which they are applied in the material according to the invention.
In other words, the casting solutions used in the arrange-10 ment according to the invention are mixed to prepare the following partial layers of the comparison material:
a) Casting solutions for the layers indicated under 2.
to 4;

b) casting solutions for the layers indicated under 5.
to 7. and c) casting solutions for the layers indicated under 9.
to 11.

In the comparison material, the resulting mixtures of casting solutions are cast in quantities, measured as 20 wet applications, corresponding to the sum of the wet applications of the partial layers used for the various colour elements in the material according to the invention.
As in the material according to the invention, so also in tnis case the antihalation layer in~icaied in the mater-25 ial according to the invention is arranged between thelayer support and the cyan element, and the yellow filter layer indicated in the material according to the invention is arranged betweerl the masenta element and the yellow element. Since the quantities of wet applications are the 30 same, the comparison material contains the same quantities .

-- 117~4 ~7 per unit surface area of the substances used in the material according to the invention. The total layer thickness in the comparison material is the same as in the layer arrangements according to the invention indicated above. The comparisor.
5 material is hardened in the same way as the material according to the invention.
Both materials are exposed imagewise to white light and subjected to the negative process indicated in Example 1.
The following data are obtained:

10 Table 3 ial Graininess (~Dx102) at density D Speed Dmax D=0.5 D=l.0 D=1.5 D=2.0 mg cy mg cy mg cy mg cy mg cy mg cy _ . _ _ . . -_ tnicv)nn- 2.5 3.2 2.8 3.2 2.0 2.6 1.5 1.9 24.1 24.0 2.5 2.;~
Comp- 2.6 3.3 3.8 3.4 2.8 3.0 2.5 2.6 24.5 24.3 2.8 2.4 The Table again demonstrates the marked improvement in graininess obtained in the material according to the invention. The graininess of the yellow partial colour image can be disregarded since a yellow colour grain makes 15 little visual impact. Conventional yellow layers or yellow layer packets can therefore be used in the arrangement mentioned in this Example.

Example 4 In this Example, the silver halide emulsion layer 20 contains no colour coupler. The following layers are applied to a layer support in the sequence given:

.
. :

117~4~7 l. LaYer K l containina colour couPler This layer contains 360 mg of the followlng magenta coupler No.3 and 140 mg of the following magenta coupler ~ 0-NH-C CH

2H5 ~ ~ C2H5 1 \N /
3 C-c2H~ C1 ~ 1 Cl The layer contains 1.49 g of gelatine and has a thickness of 1.6 ~u.

2. Silver halide emulsion layer E

This layer contains an emulsion of cubic silver bromide grains. me silver halide grains have an average grain size of 0.8 ~ and are stabilised with azaindene. The silver application is 3.8 g and the gelatine application is 0.5 g. The gelatine/silver nitrate ratio is about 0.132. The thickness of the layer is 1.04 ,u.

3. Layer X 2 containing colour couPler This layer is similar to layer K l in its compos-ition and the quantities applied.
The silver halide packing density P defined in the description is 3.65, and the coupler/silver nitrate ratio is 0.265.
For comparison, an arrangement is prepared in which the casting solutions for th~ individual partial layers 117~4'~7 are mixed before casting ln the same way as in the comparison arrangements of Examples l to 3. This comparison arrangement thus contains the same substances and in the same quantities as the material according to the invention and has the same total thickness of 4.24 u.
Both materials are subjected to a negative process as indicated in Example l. The variation of graininess in the material according to the invention and in the comparison material shows that in the material according to the invention the graininess unexpectedly diminishes at a higher ~ density whereas in the comparison material it continues to : increase also at high densities.

.

.~.

Claims (10)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A photographic material having at least one light-sensitive silver halide emulsion layer for each of the red, green and blue spectral region wherein at least one emulsion layer E
is enclosed by associated layers K containing at least one color coupler wherein at least one layer K is arranged in a water-permeable relationship above layer E and at least one layer K is arranged in a water-permeable relationship below layer E, said layers K containing no silver halide or only silver halide having a speed to blue light which is less by a factor of at least 50 than that of the image-recording blue-sensitive layer and said layer E being relatively thin and having a silver halide packing density of at least 1Ø

2. A material according to claim 1, wherein layer E has a thickness of at the most 1.5 µ and the ratio of binder in grams to the silver contained therein, calculated as grams of silver nitrate is, at the most, 0.4:1.

3. A material according to claim 1, wherein the colour couplers in the associated layers result in substantially the same colour, when coupling.

4. A material according to claim 1, wherein at least one layer E is free from colour couplers, has a thickness of at the most 2.0 µ and the ratio of binder in grams to the silver contained therein, calculated as grams of silver nitrate is, at the most, 0.4:1.

5. A material according to claim 4, wherein layer E has a thickness of at the most 1.2 µ and the ratio of binder in grams to the silver contained therein, calculated as grams of silver nitrate is, at the most, 0.2:1.

6. A material according to claim 1, wherein at least one silver halide emulsion layer E contains at least one colour coupler.

7. A material according to claim 1, wherein at least one silver halide emulsion layer E contains a colour coupler which couples more slowly than the coupler in the associ-ated layer containing colour couplers.

8. A material according to claim 7, wherein the velocity constant of the coupling reaction with the oxidation pro-duct of a p-phenylene diamine developer compound is at least twice as high in the case of the couplers of the associated layers containing colour couplers as in the case of the couplers contained in the silver halide emul-sion layer E.

9. A material according to claim 1, wherein all the couplers are embedded in a diffusion resistant form.

10. A process for the production of photographic images by imagewise exposure of a photographic material and development with a p-phenylenediamine developer compound, wherein a photographic material as claimed in claim 1 is used.