JPH01150128A - Photographic material - Google Patents

Abstract

PURPOSE: To prevent the degradation in photosensitivity by specifying the iron content of a photographic material having emulsion layers of a high silver chloride content. CONSTITUTION: The photographic material is provided with >=1 layers of the emulsion layers contg. >=60mol% AgCl and the total of the iron content in the layer on a base (e.g.: paper coated with polyethylene) is specified to <=50ppm of the silver halide calculated as AgNo3 . A device having a surface subjected to enameling or plastic coating or a device consisting of an alloy having the low iron content is usable for prepn. of the emulsion and processing by using a starting raw material (e.g.: gelatin) of the lowest possible iron content. The addition of chemical sensitizers, stabilizers, etc., for the emulsions is possible and the constitution of the emulsion layers by red-, green- and blue photosensitive emulsion layers is possible as well.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to photographic materials in which the layers applied to the support have a low content of iron.

Silver halide-containing layers of photographic materials have conventionally always contained considerable amounts of iron ions or compounds, which have a number of detrimental effects on the photographic properties of the material. Primarily,
Iron compounds can be introduced with the starting materials used in the preparation of emulsions and, secondly, can be contaminated with iron from refined steels commonly used in equipment for the preparation and processing of emulsions (Ullmans et al.・Enchilopedi del・
Teichnisien Hemy, Verlag Hemy Weinheim (lJllmans Encyclopadie)
der technischen Chemie,
Verlag Chemie Weinheim) (
1979), vol. 18, p. 428, O. Rapp (0
゜Lapp); V, C, Zerichman, S, M,
Levi, Making and Coating Photographic Emulsions, Focal Press London/New York (V, C, Zelikman, S,
M. Levi.

Making and Coating Photo
rapic emulsions.

Focal Press London/New Y
(1964), p. 19).

Silver halide emulsions attack even high quality austenitic FJ, especially when the emulsion contains an excess of soluble halide salts, as is usually found in its preparation, and especially when the silver halide is partially Or it occurs when it is all silver chloride.

Iron ions are highly detrimental to emulsions because they tend to reduce silver ions or halogen silver particles to elemental silver, giving rise to photographic fog.

Iron ions are a possible system for many undesirable redox reactions in photographic emulsions, since they are easily converted from divalent to trivalent states, and conversely, in which the photosensitive nuclei and latent image nuclei It has already been reported by Borginon et al., Journal Photographic Science, that
Sci.) L8.111 (1980). In the former case there is a general loss of emulsion sensitivity and in the latter case there is partial or complete destruction of the latent image at a point between exposure and development of the photographic material.

Therefore, many attempts have been made to prepare photographic emulsions that are as iron-free as possible. One important source of iron ions is, for example, the gelatin used.

For example, Xuan-Ya, Journal 7 Autographic Science (L, Xuan-Ya, J, Ph
ot.

gr, Sci,) Vol. 30, p. 20 (1982) found iron contents of lO to 80 ppm in various gelatins, and W. Long-King et al., 7 Oto Gelatin Report 1983. p. 283, No. 4 IAG Conference Freiburg 1983, H.

Edited by Amman-Plas and Pouladaye (1985) (
W, Rong-gin eL al, Photo-G
Elatin Report 983, page
283, 4th IAG Conference
Fribourg1983. edited by H,
Amman-Brass and Pouradier
(1985)) have shown that iron ions are likely to cause significant sensitivity loss in photographic emulsions. Even 5 ppm of iron ions can reduce photosensitivity by about 15%, and many attempts have been made to remove at least as much iron ion from gelatin as possible.

Currently high quality gelatin for photographic purposes contains less than 5 ppIn iron.

Another possibility to prevent iron ions from undergoing redox reactions in the emulsion is to use complexing agents for iron. However, such compounds are not specific only to iron ions, but also form complexes with other multivalent ions, such as calcium ions. The resulting gelatin contains high amounts of calcium ions, up to 4500 ppm, and therefore requires the addition of large amounts of complexing agent, which also entails photographic disadvantages.

Until now, it has been found impossible to prepare photographic materials in which the layers applied to the support have a very low iron content, especially if the materials contain chloride emulsions. .

The present invention has at least one silver halide emulsion layer containing at least 60 mole % A IcQ, the layers applied to the support having a total halogen content calculated as A9NO1. Based on silver oxide, total iron content ≦50
ppl preferably <20 ppm5 especially '-10 ppm
This invention relates to photographic materials having the following characteristics.

The iron content of the support itself is not important in this connection, especially if the support is a polyethylene-coated paper, but of course the iron content of the total material is also based on the silver halide content mentioned above. can be within range.

The silver halide of the l or more silver halide emulsion layers preferably has a silver chloride content of at least 80 mole %. Preferably the silver halide in all silver halide emulsion layers has a silver chloride content of at least 60 mole %, preferably at least 80 mole %. Other materials are 0-40
mole %, preferably 0 to 20 mole % silver bromide and 0 to 2
Contains mole % silver iodide, especially 0% silver iodide.

The photographic materials of the invention are prepared using starting materials with as low an iron content as possible, this applies in particular to gelatin, and using equipment and equipment that do not contaminate the materials with iron.

For the preparation and processing of the emulsions according to the invention, all equipment in contact with the emulsions must have enamelled or plastic-coated surfaces, or metallic materials with a low iron content, such as nickel, titanium, etc. It has been found to be particularly advantageous to use alloys based on tantalum or tantalum.

The photosensitive layer of the material according to the invention contains, in addition to the silver halide, a binder.

The binder used is preferably gelatin, but
It can be partially or completely replaced by other synthetic, semi-synthetic or natural polymers. Examples of synthetic gelatin substitutes include polyvinyl alcohol, poly-N-vinylpyrrolidone, polyacrylamide, polyacrylic acid and derivatives thereof, especially copolymers thereof. Examples of natural gelatin substitutes include albumin or other proteins such as casein, cellulose, sugar, starch and alginates. Semi-synthetic gelatin substitutes are generally modified natural products. Suitable examples are gelatin derivatives obtained by reaction with hydroxyalkyl cellulose derivatives and alkylating or acylating agents or by grafting of polymerizable septamers.

The binder should have a sufficient amount of functional groups to be capable of producing a resistant layer by reaction with a suitable curing agent. Amino groups are particularly suitable functional groups for this purpose, but carboxyl groups, hydroxyl groups and active methylene groups are also suitable.

Gelatin, the preferably used binder, can be obtained by acid or alkaline decomposition. The production of such gelatin is described, for example, in A.

G. Ward and A. Kreutz, Academic Press (
A. G. Ward and A. Courts, Aca.
The Science and Technology of Gelatin (The Science and Technology of Gelatin), published by
Science and Technology
f Gelatin) 1977, pages 295 et seq. The gelatin used should contain as few photographically active impurities as possible (inert gelatin).
It should be. Gelatin with high viscosity and low swelling is particularly advantageous. Oxidized gelatin can also be used.

The silver halide present as a light-sensitive component in the photographic material can consist of chloride, bromide, iodide or mixtures thereof. As mentioned above, chloride-rich emulsions are preferred. The silver halide consists primarily of close crystals, such as equiaxed rhombic or octahedral crystals or transition forms, but platelet crystals can also be present. The latter preferably have an average diameter-to-thickness ratio of greater than 5:1, where the particle diameter is defined as the diameter of a circle with a surface area equal to the projected area of the particle.

Silver halide grains can have a multilayered grain structure, in the simplest case consisting of an inner region and an outer region (core/shell), which regions are modified by their halogenide composition and/or by other modifications, e.g. The doping can be different. The average grain size of the emulsion is preferably 0.2 μm to 2.0 μm.
μm, and the particle size distribution can be homodisperse or heterodisperse. Homogeneous particle size distribution means that 95% of the particles
This means that the particle size does not deviate by more than ±30% from the average particle size. In addition to silver halide, the emulsions may contain organic silver salts, such as silver pencitriacylate or silver behenate.

Two or more types of silver halide emulsions made separately can be used as a mixture.

Photographic emulsions can be made by various methods from soluble silver salts and soluble silver salts (e.g., P. Glafkides, Nmyi Ko, Fujik Photographic, Paul Montel, Paris).
Chimie et Physique Photog
raphique, paul montel, pari
s) (1967) G-F.

Dufuin, Photography Inc., Emulsion Chemistry, The 7 Orcal Press, London (G.F.
．． Duffin, Photographic Emul
sion Chemistry, The Focal
Press, London) (1966)
,V.

L. Zelikman et al., Making and Coating Photographic Emulsions, The Focal Press, London (V.L. Zelikman
eL al, Making and Coatin
g Photographic Emulsions,
The Focal Press, London)
(1955)).

Precipitation of the silver halide is preferably carried out in the presence of a binder, such as gelatin, and can be carried out at acidic, neutral or alkaline pH, preferably with the addition of a /10 silver halide complex former. The latter include, for example, ammonia, thioethers, imidazole, ammonium thiocyanate and excess halides. The water-soluble silver salt and the halide are selectively added sequentially by a single jet method or simultaneously by an overlapping jet method.
Or they can be combined by any combination of these two methods. They are preferably controlled by an increasing inflow velocity, but at a "critical" point, where the generation of new nuclei is just prevented.
’ is added so that the speed is not exceeded. The pA2 range during the precipitation process can be varied within a wide range. The so-called pAj+ regulation method is preferably applied, in which during precipitation pA, 9, is kept at a constant value or passes through a predetermined contour. As an alternative to the preferred method of precipitation with an excess of halide, a so-called reverse precipitation method using an excess of silver ions can also be carried out. Silver halide crystals are
Not only due to precipitation, but also due to excess halides and/or
Alternatively, growth can also be achieved by physical ripening (Ostwald ripening) in the presence of a silver halide complex forming agent. In fact, emulsion grain growth occurs primarily by Ostwald ripening, in which a finely grained so-called Lippmann emulsion is advantageously mixed with a less readily soluble emulsion, redissolved and precipitated onto the latter.

During the precipitation and/or physical ripening of the silver halide grains, salts or complex salts of metals such as Cd, Zn, Pb, TQ, BixIr or Rh may be present. Precipitation can also be carried out in the presence of a sensitizing dye. The complexing agent and/or dye can be inactivated at any stage, for example by changing the pH or by oxidative treatment.

The soluble salts can be removed after the completion of crystal formation or at an earlier stage, for example by fibrillation and washing, by fibrillation and washing, by ultrafiltration or by ion exchangers.
removed from the emulsion.

Silver halide emulsions generally have a specified pH of 5p Al
s Subjected to chemical sensitization under conditions of temperature and concentration of gelatin, silver halide and sensitizer until best sensitivity and best fog are achieved. The operating method is, for example, H, Freezer, Die Grundlagen der Fotographischen Prozess Mits Zilberhalogenienden"Academie Verlagsgesellschaft () 1. Fr1eser, "Die Grundl.
photography
Prozesse mit Silberhalog
Akademische Verla
gsgesellschaft) (1968),
It is described on pages 675-734.

Chemical sensitization can be carried out using compounds of sulfur, selenium, tellurium and/or compounds of gold, platinum, palladium, rhodium or iridium, or thiocyanate compounds, surface-active compounds such as thioethers, heterocyclic nitrogen compounds (such as imidazoles, azaindenes) and spectra. Sensitizers (e.g. F.

Hamer, '°The Cyanine Soybean and Related Compounder (F, Hamer, “The Cy
anineDyes and Re1ated Com
Pounds'') l 964, and Ulmans Enticlopedie der Technicienchemii (Ul.
lmans Encyclopjidie delte
chnischen Chemie) 4th edition, vol. 18,
From page 431, and Research Disclosure (R
e5earch Disclosure) No, l
7643, described in Chapter ①). Instead or in addition to adding these compounds, reducing agents (tin-n salts, amines, hydrazine derivatives, aminoporanes, silanes, formamidine sulfinic acids) can be added to reduce pAj? Reduction sensitization can be carried out by adjusting the pH (eg below 5) and/or applying a high pH (eg above 8).

Photographic emulsions may contain compounds to prevent fog or stabilize photographic functionality during manufacture, storage, or photographic processing.

Azaindenes are particularly suitable, especially tetra- and pentaazaindene, and more particularly those substituted with hydroxyl or amino groups. Such compounds are described, for example, by Birr in the Zeitschlitt-Witssenschaftlitzch-Photography (Z
, Wiss, Photo, ) 4U (1952), 2~
It is described on page 58. Salts of metals such as mercury or cadmium, aromatic, sulfonic or sulfinic acids such as benzenesulfinic acids, or nitrogen-containing heterocyclic compounds such as nitrobenzimidazole, nitroimidazole, (substituted) benzotriazoles or benzothiazolium salts. can also be used as antifogging agents.

Heterocyclic compounds containing mercapto groups are particularly suitable, such as mercaptobenzothiazole, mercaptobenzimidazole, mercaptotetrazole, mercaptothiadiazole and mercaptopyrimidine.

These mercaptoazoles can also contain water solubilizing groups, such as carpoquine or sulfo groups. Other suitable compounds are Research Disclosure No.
17643 (1978), Chapter V1.

Stabilizers can be added to the silver halide emulsion before, during or after ripening. The compounds can of course also be added to other photographic layers associated with the silver halide layer.

Mixtures of two or more of the above compounds can also be used.

Photographic emulsion layers and other hydrophilic colloid layers of light-sensitive materials made according to the invention may contain surfactants for various purposes, such as as coating aids, as charge build-up inhibitors, to improve slip properties, and in dispersions. They can be included to emulsify, prevent sticking and improve photographic properties such as accelerated development, high contrast, sensitization.

Photographic emulsions can be spectrally sensitized with methine dyes or other dyes. Cyanine dyes, merocyanine dyes and complexed merocyanine dyes are particularly suitable.

When the inherent photosensitivity of the silver halide is sufficient for a particular spectral region, such as the blue sensitivity of silver bromide, the sensitizer can be omitted.

Color photographic materials usually contain at least one red-sensitive, one green-sensitive and one blue-sensitive emulsion layer. These emulsion layers are associated with non-diffusible monomeric or polymeric color couplers that are present in the same layer or in adjacent layers.

Cyan couplers are usually associated with red-sensitive layers, magenta couplers with green-sensitive layers, and yellow couplers with blue-sensitive layers.

Color couplers for producing cyan partial color images are generally phenolic or σ-naphthol based couplers. Suitable examples of these can be found in the literature.

Color couplers for producing yellow color images are generally couplers containing open chain ketomethylene groups, especially couplers of the σ-acylacetamide series.

Suitable examples of these include α-benzoylacetanilide couplers and α-pivaloylacetanilide couplers, which are also known from the literature.

Color couplers for producing magenta partial color images are generally 5-pyrazolone, indasilone or pyrazoloazole couplers. Many suitable examples of these are described in the literature.

Color couplers can be 4-equivalent couplers or 2-equivalent couplers. The latter are derived from 4-equivalent couplers in that they have substituents in their coupling positions that are removed during the coupling reaction. 2-equivalent couplers include those that are colorless as well as those that have a strong color themselves but which disappears upon color coupling and are replaced by the color of the image dye formed (masking couplers), and those that react with color developer oxidation products. white couplers which give substantially colorless products. 2-equivalent couplers also have a releasable group in the coupling position that is released during reaction with color developer oxidation products to achieve certain desired photographic activities, such as activity as a development inhibitor or accelerator. directly or after removal of one or more groups from the initially released group (eg, DE 2703145, DE 2855 697, DE 28 55 697; No. 3105026 and No. 33
No. 19428). The known DIR couplers and DAR and FAR couplers are examples of such 2-equivalent couplers.

These DIR, DAR and FAR couplers give mainly colorless products during the coupling reaction, since the activity of the groups released during the coupling reaction is of primary importance and their color-forming properties are less important. , DAR and FAR couplers are also suitable (
German Patent Application No. 1547640).

The group released may also be a ballast group, whereby reaction with color developer oxidation products yields a fogging product with diffusive or at least some limited mobility (as described in U.S. Pat. No. 4420556).

High molecular weight color couplers can be used, for example, in German Patent No. 129
No. 7417, German Patent Application No. 2407569,
Same No. 3148125, Same No. 3217200, Same No. 3
No. 320079, No. 3324932, No. 3 3
3 1 7. No. 43, No. 3340376, European Patent No. 27284 and US Pat. No. 4,080,211. High molecular weight color couplers are generally made by polymerization of ethylenically unsaturated monomeric color couplers, but can also be obtained by polyaddition or polycondensation.

To incorporate couplers or other compounds into silver halide emulsion layers, a solution, dispersion or emulsion of the desired compound is first prepared and then added to the casting solution for a given layer. The selection of a suitable solvent or dispersant depends on the solubility of the compound.

Methods using a grinding step to introduce substantially water-insoluble compounds are described, for example, in German Patent Application No. 260,974.
No. 1 and No. 2609742.

Hydrophobic compounds can also be introduced into the casting solution by means of high-boiling solvents, so-called oil formers. Suitable methods of operation include U.S. Pat.
No. 01170, No. 2801171 and European Patent No. 0
No. 043037.

Instead of high-boiling solvents, oligomers or polymers, so-called polymeric oil formers, can be used.

The compound can also be introduced into the casting solution in the form of a loaded latex. For example, German Patent Application Publication No. 2
54 1 230, 2541274, 28
35856, European Patent No. 0014921, European Patent No. 00
No. 69671, Ol30115 and U.S. Patent No. 4
See No. 291113.

Diffusion-resistant incorporation of anionic, water-soluble compounds (eg dyes) can also be achieved with cationic polymers, so-called mordant polymers.

Examples of suitable oil formers include alkyl phthalates, phosphate esters, citrate esters, benzoate esters,
Includes alkylamides, fatty acid esters and trimesic acid esters.

Color photographic materials typically have at least one red-sensitive emulsion layer, at least one green-sensitive emulsion layer and at least one blue-sensitive emulsion layer on a support. The order of these layers can be varied as desired. Couplers giving cyan, magenta and yellow dyes are generally red-sensitive and red-sensitive, respectively.
They are combined into green-sensitive and blue-sensitive emulsion layers, but different combinations can also be used.

Each of the light-sensitive layers can consist of a single layer or of two or more silver halide emulsion partial layers (DE 11 21 470). A red-sensitive silver halide emulsion layer is often located closer to the support than a green-sensitive silver halide emulsion layer, the latter is located closer to the support than a blue-sensitive layer, and a non-light-sensitive silver halide emulsion layer is The yellow filter layer is generally located between the green-sensitive layer and the blue-sensitive layer.

If the intrinsic sensitivity of the green or red sensitivity is low enough, the yellow filter layer can be omitted and other layer arrangements can be used, for example the blue sensitive layer closest to the support. , then a red-sensitive layer and finally a green-sensitive layer.

A non-photosensitive interlayer, typically placed between layers of different spectral sensitivities, allows developer oxidation products to diffuse incidentally from one light-sensitive layer to another layer of different spectral sensitivities. It can contain substances to prevent it from happening.

If a photographic material contains a number of sublayers sensitive to the same spectrum, they can differ from each other in their composition, in particular in the nature and amount of silver halide grains. Partial layers with high photosensitivity are generally arranged further from the support than partial layers with low photosensitivity. Partial layers of the same spectrally sensitive nature can be arranged next to each other or separated by other layers, for example layers of different spectrally sensitive nature. Thus, for example, all highly light-sensitive layers can be combined to form one layer packet and all low-light-sensitive layers can be combined to form another layer packet (DE-A-195-8709, ibid. No. 2530645, No. 2622922).

Photographic materials can also contain UV light absorbing compounds, optical brighteners, spacers, filter dyes, formalin acceptors, and others.

The UV light absorber compound protects the image dye from being bleached by high ultraviolet sunlight and absorbs the filter dye of the UV light present in the sunlight when exposure is carried out, thereby improving the color reproduction of the film. Both are required. Compounds used for these two different functions generally have different structures. The following are examples of UV absorber compounds, 4-
Thiazolidone compounds (US Pat. Nos. 3,314,794 and 3,352,681), benzophenone compounds (JP-A-46-2784), cinnamic acid ester compounds (US Pat. Nos. 3,705,805 and 3,707,375), butadiene compounds (US Pat. No. 3,707,375), No. 4,045,229) and benzoxazole compounds (U.S. Pat. No. 3,700,455).

UV absorbing couplers (eg cyan couplers based on α-naphthol) and UV absorbing polymers are also used. These UV absorbers can be fixed in specific layers by mordants.

Suitable filtration dyes for visible light include oxanol dyes, hemioxanol dyes, styrene dyes, merocyanine dyes, cyanine dyes and azo dyes. Of these, oxanol dyes, hemioxanol dyes and merocyanine dyes are particularly advantageous.

Suitable optical brighteners are described, for example, in Research Disclosure, December 1978, p. 22 et seq., Report No. 17.
It is described in Chapter 643.7.

Inorganic or organic photographically inert particles can be used, for example as matting agents or spacers, in layers comprising binders,
In particular, they can be present in the layers furthest from the support, but optionally also in intermediate layers, in particular those which were farthest away from the support during the production of the material (German patent Publication No. 3331542, Publication No. 34
No. 24893, Research Disclosure, 197
(December 1988, p. 22 onwards, Report No. 17643, Chapter X■).

The average particle size of the spacers is typically in the range of 0.2 to IO μm. The spacer is insoluble in water and can be soluble or insoluble in alkali. Those soluble in alkali are generally removed from the photographic material by an alkaline development bath. Examples of suitable polymers include polymethyl methacrylate, copolymers of acrylic acid and methyl methacrylate, and hydroxypropyl methyl cellulose hexahydroctate.

The binder of the material according to the invention is hardened with a suitable hardening agent, especially when gelatin is used as binder. The curing agents used include those of epoxide type, ethyleneimine type, acryloyl type and vinyl sulfone type. Curing agents based on diazine, triazine and 1,2-dihydroquinoline are also suitable.

The binder of the material according to the invention is preferably hardened with an instant hardener.

Immediate hardeners are used immediately after casting or after at least 24 hours,
Preferably, suitable binders are crosslinked quickly enough that curing is sufficiently complete after a time of no more than 8 hours, so that no further photosensitization or swelling of the combined layer due to the crosslinking reaction can occur. It is a compound of

Swelling is the difference between the wet and dry layer thickness of a film processed under aqueous conditions (Photogr.
aphic Sci, Eng,) 8 (1964)
(1972), 449).

Hardening agents that react very quickly with these gelatins include
For example, carbamoylpyridinium salts are included, which are capable of reacting with free carboxyl groups of gelatin, whereby the latter react with free amine groups of gelatin to form peptide bonds and effect cross-linking of gelatin. .

Suitable examples of instant curing agents include, for example, compounds corresponding to the following general formula: where R1 is alkyl, aryl or aralkyl, R3 has the same meaning as R1, or alkylene, arylene, aralkylene or alkalkylene in which the second group is linked to a group of or the atoms necessary to complete a morpholine ring, which ring may be substituted with e.g. C1-C, alkyl or halogen; R1 is hydrogen, alkyl, aryl, alkoxy, N.R.
, -COR,, -(COx)m-NRaR,, -(CH
,)n-C0NR□J14 or -(CHI)p-CI
-Y-R, or a cross-linker or direct bond to the polyRIS mer chain, and R7, R9, RI4, RIS, R17, R
1 and R8 are hydrogen or C1-C4 alkyl, R1 is hydrogen, C1-C4 alkyl or NR,R.

Hail, R, is COR,. Hail, RIG is N R,,R,! , R11 is C,-
C, alkyl or aryl, especially phenyl, R1 is hydrogen, 01-C, alkyl or aryl, especially phenyl, R13 is hydrogen% C1-C4 alkyl or aryl, especially phenyl; R16 is hydrogen, 01-C4 alkyl, COR, or CON HR, 1 is a number, m is a number from 1 to 3, n is a number from 0 to 3, and p is a number from 2 to 3. Hail, and Y hail O or NR+y, or R13 and RI
4 together are the atoms necessary to complete an optionally substituted heterocycle, such as a piperidine, piperazine or morpholine ring, which ring may be substituted with, for example, C, -C, alkyl or halogen. , 2 represents the carbon atoms required to complete a 5- or 6-membered aromatic heterocycle with an optionally fused benzene ring, and xO represents an anion, which is already If an anionic group is attached to the remainder of the molecule, it shall not be present;

Of course, it is necessary to ensure that all components of the photographic material are iron-free or have a sufficiently low iron content. This applies especially to binders.

The materials according to the invention are processed by generally recommended methods depending on whether they are black-white materials, color photographic materials, negative materials, direct positive materials or reversal materials.

Example 1 (Comparative Example) A silver chloride emulsion was deposited in a V4A refined steel container (DIN material number 1).
．． 457L Al5I standard 316L) using the following grammar.

2.5N AgN○3 solution lOQ and 2.5N NaC
(2 solution IQ was vigorously stirred by overlapping jet method into a 9% by weight solution 4Q of inert bone gelatin containing NaCf225.? and 0.52 1,8-dihydroxy-3,6-cythiaoctane at 45 °C. for 55 minutes, the inflow rate at the end of the period being 10 times the rate at the beginning. The pCQ value is kept at 0.95 and the pH is kept at 4.0 with nitric acid. The emulsion had an average grain size (diameter of spheres of equal volume) of 0.8 μm.

Excess salt is removed from the emulsion by a coagulation method, and inert low-iron bone gelatin is added to give a gelatin concentration of 7.
The silver content at 5% by weight is adjusted to 2002 CA9N○3)/kl.

The emulsion is chemically ripened with thiosulfate and gold salts and cast onto a layered support at a thickness corresponding to 52 cm of silver (as INO). Exposure to a 200 watt tungsten lamp for 5 seconds through a step wedge with the following composition: N-methyl-p-aminophenol 1.0. ? Sodium sulfite, anhydrous 13. (L? Hydroquinone 3.02 Sodium carbonate, anhydrous 26.0.9 Potassium bromide
After developing with a developer in which -L Yuan is dissolved in water lQ, a relative sensitivity of 100 is obtained with a fog of 0.16.

The iron content of the emulsion was tested using atomic absorption spectroscopy, and A, ? Based on N○3, it was found to be 150 ppm Fe.

Example 2 (according to the invention) A silver chloride emulsion is prepared in the same way as in Example 1, except that all other parts of the container and equipment with which the emulsion comes into contact, such as stirrers etc., are made of titanium (DIN material no. 37025).
, Al5I standard Ti grade 2).

The emulsions were chemically ripened and photographically examined as described in Example 1. A relative sensitivity of 125 was measured with a fog of 0.11.

The iron content of the emulsions was assayed in the same manner as in Example 1. The iron content found was 2 ppm based on A, 9NO,
Met.

Example 3 (comparative) A support coated on both sides with polyethylene was coated with the following layers. Amounts are based on l m2.

1. Gelatin 200 with KNO3 and chrome alum
mp base layer 2, adhesive layer 3 of 320 m2 of gelatin, 1600 m5 of gelatin, 1.0 mmol of yellow coupler, 27.7 m2 of 2,5-dioctylhydroquinone and 650 mg of tricresyl phosphate in A2N O
3600ml? blue-sensitive silver chloride bromide emulsion layer (99 mol% chloride).

Emulsions were made with a particle size of 0.8 .mu.m by the double flow method, hair-flotted in the conventional manner, washed and redispersed with gelatin. The weight ratio of gelatin to silver (as /M?NO1) was 0.5. The emulsion was then adjusted to 60% per mole of Al.
It was aged to best sensitivity with μMole of thiosulfate, sensitized to the blue spectral region and stabilized.

4. Gelatin 1200m, 9.2.5-Dioctylhydroquinone 80m, ? and tricresyl phosphate 1
00r+J middle class.

5. Gelatin 750m7, magenta coupler 0.625
mmol, α-(3-t-butyl-4-hydroxyphenoxy)-myristate ethyl ester 118 m2.2
．． 5-dioctylhydroquinone 43rrll,',;
A green-sensitive silver chlorobromide emulsion layer (99 mole % chloride) of A7NOx 530 m7 containing 343 m2 of phthyl phthalate and 43 m7 of tricresyl phosphate.

6. Gelatin 1550r+J, following formula: CH.

CH3 UV absorber 285 ml. Dioctylhydroquinone 8
Interlayer of 0 mF and tricresyl phosphate 650 m2.

7. Gelatin 1470m, ? , cyan coupler 0.78
AIN Ox containing 0 mmol, 285 ml of dibutyl phthalate and 122 mjF of tricresyl phosphate
400 ml red-sensitive silver chloride bromide emulsion layer (99 mol%
chloride).

8. Gelatin 1200mj+, UV used in the 6th layer
Absorbent 134m2 and tricresyl phosphate 240m2
Protective layer of rl.

9. Gelatin 400m, 9 and the following formula 400m of curing agent, 9 curing layers.

The following compounds were used as color couplers: Yellow coupler: Magenta coupler: Cyan coupler: Shil The gelatin used was the same as in Example 1. The emulsion was made in the steel vessel described in Example 1. The iron content of the layer packet applied to the support is 85p based on AlNo.
It was pm.

Example 4 Materials were made as described in Example 3 except that the emulsion was prepared in the apparatus described in Example 2. The iron content of the layer packet applied to the support is AlN0. It was 12 ppm based on .

Example 5 The materials of Examples 3 and 4 were used in standard method RA4 for color negative paper.
/AP94.

The following results were obtained for the various color layers (E=relative sensitivity, S=fog).

The main features and aspects of the invention are as follows.

(2) having at least one silver halide emulsion layer containing at least 60 mol% AICQ, all layers applied to the support taken together are A2N0. Photographic material characterized in that it has an iron content of ≦50 ppm, based on silver halide calculated as

2. Photographic material according to item 1 above, characterized in that the iron content is <20 ppm.

3. The photographic material according to item 1 above, characterized in that the iron content is ≦lOppm.

4. Photographic material according to claim 1, characterized in that the silver halide of more than 1 or 1 silver halide emulsion layers consists of silver chloride to the extent of at least 80 mol %.

5. Photographic material according to claim 1, characterized in that the silver halide of all silver halide emulsion layers consists of silver chloride to the extent of at least 60 mol %.

6. Photographic material according to claim 5, characterized in that the silver halide of all silver halide emulsion layers consists of silver chloride to the extent of at least 80 mol %.

7. Photographic material according to item 1 above, characterized in that the support is paper coated with polyethylene.

8. The photographic material comprises at least one red-sensitive silver halide emulsion layer containing at least one cyan coupler, at least one green-sensitive silver halide emulsion layer containing at least one magenta coupler, and at least one green-sensitive silver halide emulsion layer containing at least one magenta coupler. a color photographic material containing at least one blue-sensitive silver halide emulsion layer containing one yellow coupler;
Photographic material as described in item 1 above.

Claims (1)

[Claims] 1. having at least one silver halide emulsion layer containing at least 60 mol% AgCl, all layers applied to the support taken together, based on silver halide calculated as AgNo_3; Photographic material characterized in that it has an iron content of ≦50 ppm.