DE2907596A1 - PROCESS FOR MANUFACTURING A SPECTRALLY SENSITIZED, RADIATION-SENSITIVE SILVER HALOGENIDE EMULSION - Google Patents

Description

" ⁴ " 2307596

The invention relates to a process for the preparation of a spectrally sensitized, radiation-sensitive silver halide emulsion, in which one in a reaction vessel an aqueous solution of a silver salt, an aqueous solution of a Introduces a halide salt, a peptizer, and a methine spectral sensitizing dye, the dye during the introduction of at least one of said aqueous salt solutions into the reaction vessel.

In the spectral sensitization of silver halide emulsions it is common for the spectral sensitizing dye to absorb on the surface of the silver halide grains after the preparation of the silver halide grains is completed.

It is known from US Pat. No. 2,735,766 that the migration of a photographic spectral sensitizing dye can be eliminated or reduced if a spectral sensitizing merocyanine dye during the Silver halide precipitation is added. US Pat. No. 2,735,766 also discloses the mixing of the spectral sensitizing agent Dye with either the silver salt or the halide salt prior to combining the salts for purposes known for silver halide formation.

From U.S. Patent 3,628,960, in which the spectral sensitization of a mixed silver halide emulsion with a Methine dye is described, it is also known that the dyes are added by a separate additive can be or can be mixed with one or more of the components that are used to produce the various Silver halide grains can be used. The addition of the dyes can be done during the physical or chemical Ripening or during another stage of the process prior to application of the emulsion to a support.

-S-

The known methods by which spectral sensitizing dyes are added to silver halide emulsions, often lead to the following disadvantages:

1) It becomes less than the desired minus blue sensitivity achieved (i.e., sensitivity when exposed through a # 16 yellow Wratten filter);

2) stability in keeping or storage is less than desired;

3) dye desorption occurs;

4) there is color haze and discoloration;

5) there will be undesirable changes in the dye absorption characteristics established and / or

6) there is less than desirable control or modification of the silver halide grain structure.

The invention was based on the knowledge that one or more of the disadvantages shown in the production of spectrally sensitized, radiation-sensitive silver halide emulsions can be remedied if, according to the invention, the addition of the spectral sensitizing dye is so long delayed until silver halide grain nuclei are present in the reaction vessel.

The inventive method can be applied to any of the customary known methods for producing radiation-sensitive silver halide grains in which an aqueous solution of a silver salt and an aqueous solution a halide salt for the purpose of producing radiation-sensitive silver halide grains in contact with each other to be brought. The inventive method is particular

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applicable to the spectral sensitization of radiation-sensitive silver chloride, silver iodide, silver bromide, silver bromide iodide, silver chlorobromide, silver chloride iodide and silver chlorobromide iodide crystals. It has proven to be particularly advantageous if the silver haloiodide crystals have less than about 10 mol% iodide, based on the total halide, although in special applications silver haloiodides with a high iodide content can be advantageous.

The process of the present invention for preparing silver halide emulsions with simultaneous spectral sensitization of the same can be modified by modifying the usual known processes, i.e. the preparation of silver halide emulsions Apply according to the bin entry method and according to the double entry method. In the case of the single enema method As is known, an aqueous solution of a silver salt, for example an aqueous solution of silver nitrate, is placed in a reaction vessel introduced, in which an aqueous solution of a halide salt is present, for example an aqueous solution of a Alkali halides such as sodium or potassium halide and a peptizer. In the case of the double enema method will be the aqueous silver salt solution and the aqueous halide salt solution simultaneously and separately from one another into the reaction vessel introduced. Typically, at least some of the peptizing agent is present in the reaction vessel from the start, with additional peptizer typically being introduced into the reaction vessel during the addition of the solutions.

A typical single inlet process is known, for example, from the magazine "The Photographic Journal", No. LXXIX, May 1939, pages 330 to 338. A typical double enema process is known, for example, from US Pat. No. 2,222,264. For the rest, the single inlet method and the double inlet method are used for the preparation of silver halide emulsions discussed in detail in Chapters I and II of the book by

Mees and James, "The Theory of the Photographic Process," Third edition, published by McMillan Company, 1966.

After the introduction into the reaction vessel, the dissolved reacts Silver salt with dissolved halide salt to form silver halide crystals. This first phase of silver halide emulsion production, at which new silver halide crystals are generated is usually called the kernel or Called nucleation phase. During the subsequent Addition of silver salt can add further silver halide, which is called Reaction product is deposited on these nuclei or nuclei, thereby reducing the mean particle size of the silver halide grains is increased. This ultimately leads to the formation of silver halide grains of the desired mean particle size. The nucleation and growth of the silver halide grains in most cases take place in a single reaction vessel. However, nucleation or nucleation can also take place in a first reaction vessel., namely under Use of the single inlet method or the double inlet method, whereupon the obtained fine grain silver halide emulsion is introduced into a second reaction vessel, and with or before further halide salt and silver halide salt for the purpose of facilitating another Kanwak turn. Multi-stage or cascade silver halide precipitation processes of this type are from, for example, work by Terwilliger et al., Precipitation of Silver Halide Emulsions in a Continuous Reaction, published in the reference Research Disclosure, September 1976, Item 14987 and U.S. Patent 4,046,576.

According to the method of the invention, during the introduction of the aqueous silver salt solution into the reaction vessel with the Silver halide nuclei or nuclei, a conventional methine spectral sensitizing dye is introduced into the reaction vessel. If the spectral sensitizing dye is soluble, so it can be added in the form of an aqueous solution without an auxiliary solvent - 8 -

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is present. In most cases it has been found to be useful to mix the dye in an organic one that is miscible with water Solvent to dissolve, for example acetone or an alcohol with 1 to 3 carbon atoms. If necessary, can Surface-active compounds and / or peptizers added to the spectral sensitizing dye solutions will. The solution of the spectral sensitizing dye can be poured into the reaction vessel by means of a special flow nozzle can be added or the solution can be mixed with the aqueous silver salt solution and / or the aqueous halide salt solution are mixed, which is fed into the reaction vessel. The spectral sensitizing dye can be used in the reaction vessel can be introduced continuously or intermittently in the form of various portions. For example the introduction of the silver salt and / or the halide salt can be interrupted periodically, with during of these interruptions the spectral sensitizing dye is introduced. With the exception of the specific one below methods described can be applied, as described, for example, in US Pat. No. 2,735,766, as well as customary methods of introducing spectral sensitizers Dyes in pre-formed silver halide emulsions. Such customary methods are known, for example from Paragraph XVII of the reference "Product Licensing Index", Volume 92, December 1971, Publication 9232.

By delaying the introduction of the spectral sensitizing dye to silver halide nuclei or nuclei in the reaction vessel are present, a disturbance with the nucleation or nucleation is avoided.

The introduction of the spectral sensitizing dye is preferably delayed until the mean diameter of the Silver halide nuclei or nuclei at least one hundredth, particularly advantageously with at least five

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One hundredth of the mean diameter of the silver halide grains in the finished emulsion is. If the reaction vessel is initially free of silver halide nuclei or nuclei at the beginning of the silver salt addition, adequate nucleation in the absence of dye is achieved by delaying the introduction of the dye until at least 1 % of the silver salt has been added to the reaction vessel, preferably 2 % and in particular at least 5 %. Although the addition of the spectral sensitizing dye can be delayed depending on the addition of the silver salt, it is alternatively also possible to delay the addition of the spectral sensitizing dye depending on the addition of the halide salt, with corresponding percentages. If silver halide nuclei are produced separately and introduced into the reaction vessel, the spectral sensitizing dye can be introduced into the reaction vessel together or shortly before the introduction of the silver and / or halide salt.

The introduction of the spectral sensitizing dye into the reaction vessel after the presence of silver halide nuclei or nuclei can be continued throughout the silver halide precipitation, as well as beyond the silver halide precipitation. Advantageously, the spectral sensitizing dye is introduced into the reaction vessel in a spectral sensitizing amount before at least 85 l of the silver salt have been introduced into the reaction vessel, preferably before 80% of the silver salt have been introduced and especially before 75 % of the silver salt have been introduced . In those cases in which there are no silver halide nuclei or nuclei in the reaction vessel at the beginning of the silver salt addition, the addition of the spectral sensitizing dye is advantageously carried out when 1 to 85 % , preferably 2 to 80% and in particular 5 to 75 % of the silver salt are introduced have been.

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To achieve particularly advantageous results, it has proven advantageous after an appropriate delay for the purpose of nucleation (quantitatively based on the silver halide core diameter or the 1, 2 and 5% silver salt introduction amounts, as indicated above), the spectral sensitizing dye partially at intervals or continuously fed into the reaction vessel during the silver salt introduction, the addition preferably being terminated before the silver salt introduction into the reaction vessel is complete (expressed quantitatively as 85, 80 and 75% xg silver salt introduction as indicated above). The rate at which the dye is continuously introduced can be kept constant or it can be accelerated, taking into account the increasing surface area of the silver halide grains produced. If the introduction of the spectral sensitizing dye is delayed until after greater proportions of the silver salt have been introduced into the reaction vessel (ie greater than 75 % of the silver salt), the spectral sensitization achieved begins to approach more that which is observed when the spectral sensitizing dye is introduced into the reaction vessel after the silver halide precipitation is completed according to the usual known methods.

If spectral sensitizing dye is introduced into the reaction vessel during the silver salt addition as required above and additional dye is introduced into the reaction vessel during the latter stages of the silver salt addition (i.e. after at least 75 % of the silver salt has been introduced), and / or spectral sensitizing dye becomes the silver halide emulsion added by customary methods after the silver halide precipitation has ended, a further unexpected improvement in the spectral sensitization achievable according to the invention can be achieved. Ie, a further spectral sensitization after

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usual methods and / or towards the end of the silver salt addition in combination with a spectral sensitization according to the preferred embodiments of the invention, as described above, has proven to be particularly advantageous.

Any common known spectral sensitizing dye which alone improves the ectral response of the emulsion, can in combination with a spectral sensitizing methine dye in the reaction vessel according to the described Procedures are introduced. It has proven to be particularly advantageous, the same methine dyes for the spectral sensitization of the emulsions during the silver halide Precipitation as described above and throughout the year the latter stages of silver halide precipitation or after the completion of silver halide precipitation.

According to the process of the invention, one or more of the usual methine spectral sensitizing dyes can be used are fed into the reaction vessel »Such dyes are described in more detail, for example, in US Pat. No. 2,526,632, 2 503 776, 2 493 748 and 3 384 486ο to the invention Usable spectrally sensitizing dyes include cyanine, merocyanine, complex (tri- or tetra-nuclear) Cyanine, holopolar cyanine, styryl, hemicyanine (e.g. tnaminhemicyanine), oxonols and hemioxonols.

Dyes of the cyanine classes suitable for carrying out the process according to the invention, which are suitable for the semsibilization of silver halide, can, for example, have basic nuclei such as thiazolines, oxazoline, pyrroline, pyrydine-j, xazole, thiazole-j, selenazole and imidazole nucleus © » These ICsrn © can optionally be substituted, see p. by alkyl-j, alkylene- _r hydroscyallcyl-, sulfoalkyl = *

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29Q7596

Carboxyalkyl, aminoalkyl and / or iinamine groups. Further these cores can optionally be attached to carbocyclic or heterocyclic ones Rings or ring systems, which in turn can optionally be substituted, by halogen atoms, Phenyl, alkyl, haloalkyl, cyano and / or alkoxy groups.

The dyes can be symmetrical or asymmetrical dyes be and can have a methine or polymethine chain by alkyl, phenyl, enamine or heterocyclic Substituents is substituted.

Merocyanine dyes which can be used according to the invention can be those described have basic nuclei as well as acidic nuclei, e.g. thiohydantione, rhodanine, oxazolidendione, thiazolidendione, barbituric acid, thiazolinone and malononitrile nuclei. The acidic nuclei can optionally be substituted, e.g. by alkyl, alkylene, phenyl, carboxyalkyl, suIfoalkyl, Hydroxyalkyl, alkoxyalkyl and / or alkylamino groups and / or heterocyclic nuclei.

If necessary, combinations of such dyes can also be used be used. In addition, additives which make supersensitization possible can be added which are not visible Absorb light, e.g. ascorbic acid derivatives, azaindenes, cadmium salts and organic sulfonic acids, e.g. from the U.S. Patents 2,933,390 and 2,937,089 of the known type.

It has proven to be particularly advantageous if the used to carry out the method according to the invention Methine dyes consist of conventional spectral sensitizing methine dyes that contain at least one imidazole, Have oxazole or thiazole nucleus. In particularly advantageous The spectral sensitizing dyes consist of Cyanine dyes in which at least two nuclei of the dye consist of imidazole, oxazole and thiazole nuclei.

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Particularly advantageous dyes are cyanine dyes, in which both nuclei are imidazole, uxazole or thiazole and which are represented by the following formula let go:

Ή L =

where mean:

d and η each = 1 or 2;

■ <i = 1, 2 or 3;

L is an optionally substituted methine group, e.g. of the formula -CIi = or -C (CiI,) =;

H ₁ and

Usually, an alkyl group in each case, preferably a short-chain alkyl group with 1 to 4 carbon atoms, for example a methyl, ethyl, propyl, isopropyl, butyl, hexyl, decyl or odecyl group or a substituted alkyl group , preferably a short-chain substituted alkyl group with 1 to 4 carbon atoms, for example a hydroxyalkyl group, for example a β-hydroxyethyl, γ-hydroxy propyl or ω-hydroxybutyl group or an alkoxyalkyl group, for example a 3-methoxyethyl or g-butoxybutyl group, a carboxyalkyl group , for example a ß-carboxyethyl or ω-carboxybutyl group, a sulfoalkyl group, for example a ß-sulfatoethyl or ω-sulfatobutyl group, an acyloxyalkyl group, for example a ß-acetoxyethyl or ω-propionyloxybutyl group, an alkoxycarbonylethyl or methoxycarbonylalkyl group, eg an ß-carbonylethyl ω-ethoxycarbonylbutyl group, an allyl group,

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an aralkyl group such as a benzyl or phenethyl group or an aryl group such as phenyl, tolyl, chlorophenyl, sulfophenyl or carboxypnenyl group and

Z _{1 in} each case the atoms which are necessary to complete a heterocyclic nucleus, in particular an imidazole nucleus, for example an iridazole; Alkyiimidazol-; 1-aryliniidazole-; Beiizimidazole-; 1-alkylbenzimidazole-; 1-arylbenzimidazole-; 5-chloro-1-alkylbenzimidazo1-; 5-chloro-1-arylbenzimidazole-; 5,6-l) chloro-1-alkylbeiizimidazole-; 5, δ-dichloro-iarylbenzimidazole-; 5-methoxy-1-alkylbenzimidazoI-; 5-methoxy-1-arylbenzimidazole-; 5-cyano-1-alkylbenzimidazole-; 5-cyano-i-arylbenziinidazole-; Naphth / T, 2-d / imidazole-; 1-alkylnaphth ^ T, 2-d / imidazole or a 1-arylnaphth / T, 2-d / imidazole nucleus; a Üxazolkernes, for example an Üxazol-; 4-alkyloxazole-; 4,5-alkyloxazole-; 4-aryloxazole-; 4,5-diaryloxazole-; 4-nitrooxazole-; Benzoxazole-; 5-chlorobenzoxazole-; 5- or 6-nitrobenzoxazole-; 5-arylbenzoxazole-; 5- or 6-alkoxybenzoxazole-; 5- or 6-hydroxybenzoxazole or a naphthiio / T, 2-d7oxazole nucleus or a nitro-substituted naphth / T, 2-d.7oxazole nucleus or a thiazole nucleus, for example a 'ihiazol-;4-alkylthiazole-;2-thienylthiazole-;4-arylthiazole-;4,5-diarylthiazole-;Benzothiazole; 5- or 6-chloro or ßrombenzothiazole nucleus or a 4-alkylbenzothiazole nucleus; 5- or 6-alkoxybenzothiazole or a 4-arylbenzothiazole nucleus.

It should be noted that the acid anion, which is represented by X in the above formula, part of a substituent represented by R ",

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e.g. in the case of dyes with a betaine structure. In the case of the core substituents, the alkyl groups preferably have 1 to 4 carbon atoms and the aryl substituents 6 to 10 carbon atoms, i.e. the aryl substituents advantageously from phenyl or naphthyl groups.

According to the invention advantageously usable spectrally Sensitizing imidazole, oxazole and thiazole cyanine dyes are known and are described in more detail, for example by A. II. Herz in the journal "Photographic Science and Engineering ", Vol. 18, No. 2, March-April 1974, pages 207 to 215 and in" JS-PS 3,482,981.

Examples of particularly advantageous spectral sensitizing imerocyanine dyes which can be used according to the invention, are described in more detail, for example, in U.S. Patent 2,735,766.

using a single inlet process or a According to the invention, double-jet precipitation processes can be used to produce particularly advantageous silver halide emulsions Establish properties. Are such emulsions on conventional photographic film supports or paper supports to produce photographic recording materials applied, they have a particularly advantageous spectral response, as a result of which the recording materials differ from those for the production of which emulsions were used in which the spectral sensitizing dye was added after the silver halide precipitation was complete. According to the method of the invention produced emulsions can further impart additional advantageous and unexpected properties \ verden when the emulsions are prepared as described in more detail below.

Although an additional silver halide grain formation (additional Nucleation or nucleation) after the introduction of the spectral

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sensitizing dye can take place in the reaction vessel, but it has proven to be advantageous that the nucleation of the silver halide grains (formation of new grains) is essentially or practically completed before the spectral Sensitizing dye is introduced into the reaction vessel, a method which has proven to be particularly advantageous for the Has been shown to shorten the silver halide precipitation time and which ensures that additional silver halide deposited on existing silver halide grain cores is to either gradually or gradually increase the rate or to increase the level of halide and silver salt additions. Such methods are known, for example from US-PS 3,672,900. From this patent it is known, for example, the speed or the degree to increase the silver and halide salt introductions according to the following formula:

at + bt + c
Herein mean:
t the time of precipitation and

a, b and

c constant quantities that depend on various factors, e.g. temperature, concentration, the metal ion concentration and the like, the constant values being based on theoretical Paths can be determined or preferably can be determined empirically for the special conditions of a procedure. The constant sizes are preferably for one Determined value at which new nuclei are not formed after the initial excretion, with all Kernels or grains generally grow at the same rate, producing one

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practically monodisperse emulsion.

All known reaction vessels and apparatus can be used to carry out the process according to the invention. J) the combination of the aqueous silver salt and iialogenide salt solutions and the handling of the siluer halide emulsion produced can also take place according to customary known methods. Reaction vessels, devices and methods that can be used are known, for example, from: US-i'S L 755 706 and 3 ο28 96υ

and the reference "Product Licensing Index", Publication 9232, Paragraph XVII.

Furthermore, vessels and can be used according to the invention Apparatus and methods to be used known from US Patents 3 821 002, 3 650 757, 2 996 584, 3 415 650, 3 785 777, 3 782 954, 3 790 386 and 3 897 935 as well as Gß-PS 1 302 and 846190 and UU-OS 2 555 364 and 2 555 885.

Spectrally sensitized after practicing the invention Silver halide emulsions can also have a number of common features, i.e., features such as, for example are described in more detail in the reference "Product Licensing Index", Volume 92, December 1971, Publication 9232, pages 107 to 110. For example, washed as well as unwashed emulsions can be produced, as described, for example, in Paragraph II under the heading "Emulsion Washing". The emulsions can also be chemically sensitized, for example, as described in Paragraph III under the heading "Chemical Sensitizing" is described. Development modifiers, Antifoggants and stabilizers as well as developer compounds and hardeners are added

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as described in paragraphs IV to VII of the cited reference. For the production of the emulsions can also be used customary known binders, as for example in Paragraph Vl11 of cited literature are described in more detail. The emulsions can also be applied to conventionally known substrates may be plotted, for example those as they are in paragraph X of the cited literature with the heading "Supports" are explained in more detail. Finally, the emulsions can be prepared using conventionally known dyes be prepared as described in more detail, for example, in Paragraph XV under the heading "Spectral Sensitization" will. These further additional spectral sensitizing dyes as well as other additives can be included in the Emulsions made by the process of the invention are incorporated by conventionally known methods are, for example, by methods as described in Paragraph XVII of the cited literature under the heading "Methods of addition "are given.

The remaining paragraphs of the cited reference "Product Licensing Index" describe further photographic ones Features and methods of photographic processing processes used in combination with the method of the present invention can be applied. At the Literajiturs share "Product Licensing Index "(Research Disclosure) is a publication by Industrial Opportunities Limited, Homewell, Havant Hampshire, Pü9 1EF, UK.

The following examples are intended to further illustrate the invention:

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Example 1 : Spectral sensitization of a silver chloride with an ßenzothiazolmerocyanin.

Initially, the following solutions were made:

Solution a

Phthalated gelatin Solution b Sodium chloride Silver nitrate 240 G 1,8-dihydroxy-3,6-dithiaoctane Made up with distilled water
fills to a total volume of Made up with distilled water
fills to a total volume of 2 , 1 g 21.9% by weight solution of sodium
chloride in water Solution C Solution D 246 ml Distilled water 8400 ml 520 G 3460 ml 1020 G 3460 ml

Dye I.

Mixture of acetone and water in a volume ratio of 1: 1

Distilled water

0.78 g

500 ml 127 ml

5- (S-Ethyl-Z-benzothiazolidinylidene) -3-ß-sulfoethylrhodanine

V-

N- "

^C 2 ^H 5

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Solution A was placed in a reaction vessel equipped with a mechanical stirrer. It was adjusted to a pH of 5.6 and a pAg of 6.7 at 60 ⁰ C. While solution A was stirred, solutions B and C were allowed to run separately from one another into the reaction vessel via separate inlet nozzles. The solutions were run in at a constant rate over a period of 40 minutes, the pAg value of the mixture in the reaction vessel being kept at 6.7. Two minutes after the start of the introduction of solutions B and C xv, solution D was allowed to run into the reaction vessel through a special inlet nozzle at a uniform rate, the addition of solution D being terminated 2 minutes before the end of the addition of solutions B and C.

The emulsion produced was coagulated by reducing the pH. The supernatant liquid was decanted off. After decanting off the supernatant liquid, the coagulum was redispersed in water. this Procedure was repeated twice. The resulting coagulum was then dispersed in water at 40 ° C. / pH 5.6 / pAg 7.6.

Electron ^ photomicrographs showed that the Silver halide grains of the emulsion were predominantly octahedral.

The emulsion was chemically sensitized with gall sulfide, added a cyan dye-forming coupler, namely 1-hydroxy-2- / 4- (2,4-di-tert-amylphenoxy) -n-butyl7-naphthamide, and then coated on a cellulose acetate film support in a coating thickness corresponding to 1.62 g Ag / m ² , 7.0 g gelatin / m ² and 1.78 g coupler / m ² .

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The dried layer was then treated for 1/25 second with "iVolfram-LicJit" which was filtered in such a way that a L exposure at 47U n.n took place. The recording material was then used For 60 seconds at 31 ° C in a solution the i-composition given in the following table I:

Table 1
I-'color developer solution

l-Amino-IS-ynethyl-N'-ethyl - \ - ß- (juetnansulfonamido) -

Ethylani 1 insulphate hydrate 4.3 g

K a 1 i aiab ro mi d 0.1 5 g

κ.ίΐ iui.iCuloriu 1.0 g

tSenzylalkonol 11.0 g

hydroxylariine sulfate 3.4 g

potassium carbonate 31.0 g

kai iujubicarbonate 0.5 g

Potassium sulfite 2.0 g

hydroxyethylcellulose (i \ ^: atrosül 25OL,

Manufacturer iicrcules, Inc., USA) 0.06 g

■ Make up to 1 liter with water

The grains of the silver chloride emulsion had an average one Grain diameter of 0. C5 microns. One was received i-ionodisperse silicon chloride emulsion with an oetahedral Grain morphology. The contrast of the emulsion was 2.00, the minimum density 0.10 and the maximum density 2.00.

For purposes of comparison with the other examples, the Linulsion has a relative sensitivity of 100. The sensitivity was measured at 0.30 above Minimum service on the characteristic curve.

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BAD ORJGJNAL

The developed silver image was bleached. The density measurements were carried out with red light (i.e. white light that shone through a Status i-i-Rot filter and a L 97SO 1.5 uu.i filter) was conducted. The contrast was over the straight part of the Characteristic curve determined.

Example 2 : Changed dye addition.

The procedure described in Example 1 was repeated, with the exception, however, that the addition of solutions β and C was interrupted 5ü minutes after the beginning of the precipitation step and solution D was then added to the reaction vessel within a period of 5 minutes. When the addition of solution D was complete, solutions ό and C were added to the reaction vessel in order to complete the precipitation of the silver halide.

The silver halide emulsion prepared in the manner described was polydisperse, with a grain diameter of 0.45 to 0.95 microns. The contrast of the emulsion was 2.16, the minimum density 0.10 and the maximum density 2.00. The relative sensitivity compared to Example 1 was 4b.

In a further experiment, the introduction of solution D was delayed until solutions B and C were introduced for 35 minutes had been. The emulsion obtained in this way showed comparable minimum and maximum densities, but one slightly lower sensitivity and a slightly lower contrast.

Example 3 (comparative example) : comparison with a conventional,

after precipitation, spectrally sensitized emulsion.

In order to enable a direct comparison with conventional precipitation methods, the method described in Example 1 was used

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repeated except that Dye I was not present during the precipitation step. Rather, the Dye I shortly before application of the emulsion to a layer support in a coverage of 130 mg / mol Ag admitted.

The emulsion produced was monodisperse with a mean pumpkin diameter of 0.70 microns. The silver chloride grains were cubic. The contrast was 2.20, the minimum density 0.10 and the maximum density 2.00. The relative sensitivity compared to Example 1, was 25.

This example, compared to Examples 1 and 2, illustrates that silver halide emulsions are produced using the process of the invention of considerably increased sensitivity and that also various grain structures as a result of the introduction of the spectral sensitizing dye after nucleation and after silver halide precipitation can be obtained.

The process of Examples 1 and 3 was repeated, but this time the recording materials produced were exposed to a wavelength of 565 nm, which was selected to ensure that the natural sensitivities of the emulsions were outside the range of the spectral sensitization. It was found that the recording material which had been produced according to the method of Example 1 was 100 % more sensitive than the recording material which was produced according to the method of Example 3.

Sections of the recording materials produced after the process of Examples 1 and 3 were prepared separately from one another in an agitated methanol-water solution (Weight ratio 1: 1) immersed. It was found that the spectral sensitizing dye from the recording material of the

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Example 3 entered the solution. In contrast, there was no spectral sensitizing dye from the recording material of example 1 removed. It follows from this that the dye in the case of Example 1 is bound so tightly had become that he did not wander.

It is not yet completely clear how the spectrally sensitizing one Dye added during silver halide precipitation is bound to the silver halide grains is. It can be assumed, however, that the binding of the dye to the grains produced in the manner described is fundamentally different from the binding that is achieved when the spectral sensitizing dye is after Silver halide precipitation is introduced.

Example 4 (comparative example) : Dye addition before

Keiu formation.

The principle of introducing a spectral sensitizing Dye in the reaction vessel together with one of the Silver or halide salts prior to silver halide nucleation is known. See, for example, the teachings of U.S. Patents 2,735,76b and 3,628,960.

The procedure described in Example 1 was repeated, using the dye I of the aqueous halide salt solution, Solution B added xv. It turned out to be a considerably worse polydisperse silver halide emulsion obtained. The relative sensitivity of the emulsion, compared to the emulsion of the Example 1, was only 1.

In a further experiment, the spectral sensitizing dye was combined with the aqueous silver salt solution, solution C. The liquid in the reaction vessel separated into two separate phases, so that the experiment had to be canceled.

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Example 5 : Use of spectral sensitizing cyanine dyes.

The procedure described in Example 1 was repeated, but this time using other dyes instead of the dye I were used. The following dyes were used:

Dye II: anhydro-S-chloro-9-ethyl-S'-phenyl-3 ¹ - (3-sulfobutyl) -3- (S-sulfopropyljoxacarbocyanine hydroxide, Na salt

Dye III: anhydro-5,5 ¹ , 6,6'-tetrachloro-1, Γ, 3-triethyl.3 ¹ - (3-sulfobutyl) benzimidazole carbocyanine hydroxide

Cl
Cl

CH ₀ CH, ι 2 3

, ι = CH-CH = CH-

CiL CH.

CH ₂ CH ₃

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Dye IV: anhydro-9-ethyl-5 ', 6'-dimethoxy-S-phenyl-S ¹ - (3-sulfobutyl) -3- (3-sulfopropyl) oxathiacarbocyanine hydroxide, sodium salt

Dye V: Anhydro-3,3 ¹ -bis (3-sulfopropyl) -4,5,4 ^f , 5'-dibenzothiacyanine hydroxide, Na salt

- 27 -

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Dye VI: anhydro-5,5-dimethoxy-3,3'-bis (3-sulfopropyl) thiacyanine hydroxide, sodium salt

-C ₅ H ₅ = phenyl

The results obtained are qualitatively similar to the results of Example 1, although in some cases a change in grain morphology was observed. Although Dye I produced monodisperse octahedral silver halide grains, Dye II produced very distinct cubic grains Grain structures. This suggests that dye I is preferentially adsorbed on 111 crystal surfaces and consequently promotes octahedral grain growth, whereas xio Dye II is best adsorbed on 100 crystal surfaces, reducing the likelihood of the occurrence of a cubic crystal formation is increased.

Example 6 : Combination of a spectral sensitization

during the silver salt addition with a spectral sensitization after the precipitation.

The procedure described in Example 3 was repeated, however, Dye II was used in place of Dye I. I2s tests were carried out with two different dye concentrations, as indicated in Table II below. In addition, that described in Example 1 was used Repeat procedure using 250 mg of dye

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II per mole of silver as indicated in Table II below. In a fourth experiment, the procedure described in Example 1 was repeated using 200 mg of dye II per mole of silver. Furthermore, Dye II became the emulsion just before the emulsion was applied to a substrate added to bring the total dye II concentration to 450 mg increase per mole of silver. The relative sensitivities obtained are shown in Table II below.

Table II Comparison of relative sensitivities

Total amount of relative dye sensitivity. Example 11 / Mo 1 Ag ßemerkungen

Comparison 25Ü 100 spectral sensitization after the Precipitation

as in Example 5 250 389 Spectral sensitization after nucleation

Compare 450 363 Spectral sensitization after precipitation

Example 6 450 661 Spectral Sensitization After Kein Formation and After the precipitation

The values for the relative sensitivity result in a pronounced advantage for spectral sensitization after nucleation versus spectral sensitization after precipitation. It also follows from the data obtained that, a spectral sensitization after nucleation with a spectral sensitization combined after precipitation, an unexpected increase in relative sensitivity is observed.

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Example 7 : Spectral Sensitization of Silver Bromide Iodide.

Initially, the following solutions were made:

Solution a

Phthalated gelatin Solution b Solution C 116 era KBr 609 G AI Made up with distilled water
fills to a total volume of 4th , 4 g Distilled water Made up with distilled water
fills to a total volume of 4943 ml AgNO ₃ AI HgCl ₂ Solution D 46 , 6 g 2070 ml 822 G O , 13 rag 9300 ml

Dye VI

Made up to a total volume of with distilled water

1.1 g

639 ml

Level 1 :

The solution A was placed in a reaction vessel and on

brought a temperature of 80 ⁰ C.

Level 2 ;

Solutions B and C were introduced into solution A (with agitation) such that solution B within 20 minutes was completely added and the solution C was completely added within 40 minutes. 2 minutes after At the beginning of the inflow of solutions B and C, solution D became

36/07313

added to A. U was added within 35 minutes.

Level 3 :

Bine minute after completing the addition of solution C was the temperature of the solution to ⁰ C .50 reduced. Then 60 g of sodium thiocyanate was added to the solution, and the resulting mixture was stirred for 25 minutes.

Level 4 :

The emulsion was coagulated by reducing the pH. The supernatant liquid was decanted off. The coagulum was redispersed in water. 5.6 g of KBr were added to the redispersed emulsion, whereupon the emulsion was ^{stirred at 30 °} C. for a further 3 minutes. The coagulation procedure was repeated two more times. The coagulum obtained in this way was then dispersed in water at 40 ° C. / pH 6.5 / pAg 8.0.

Photomicrographs of the emulsion produced showed that the emulsion grains have a diameter of less than 0.2 μm to over 3.0 ym.

A comparative emulsion was used to wake up the comparison Way prepared, with the exception, however, that the dye of the emulsion just before the coating of the same was added to a support. Photomicrographs showed that this emulsion contained grains of 0.3 to 3.5 microns with most of the grains 0.5 to 0.7 microns in diameter. This grain size contributed noticeably to light scattering and was not nearly as predominant in the emulsion that was then obtained, when the dye was added after nucleation.

The two emulsions were sensitized with gold and sulfur, / and then added a color coupler to produce a color photographic one

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2307596

Recording material on a cellulose acetate!: Film layer

2 carrier applied in such a way that on a carrier area of 1 m 1.62 g of silver and 7.0 g of gelatin were omitted. The recording materials produced were then 1/25 seconds with the Light from an IVoIfram lamp exposed in a color detoxifier solution with p-puenylenediamine as a twisting compound at 25 ° C and a pH of 10 and sensitometrically to each other compared. It was found that the comparison material, in which the emulsion is spectrally sensitized after the precipitation had a higher contrast than the recording material with the emulsion having a spectral sensitization after nucleation. However, both recording materials showed identical threshold sensitivities. The fog or haze of the comparative emulsion was higher than that of those made by the process of the invention Emulsion. This result results in an improved sensitivity-Z-sharpness characteristic for the recording material, made using an emulsion made by the process of the invention.

Example 8: Spectral Sensitization of Silver Chlorobromide.

Solution a

Phthalated gelatin
21.9 ° solution of NaCl / H ₂ 0
4.4 aige solution of KBr / H ₂ O
Distilled water

240 g 260 ml 147 ml 8400 ml

Solution b

NaCl NaBr

Made up to a total volume of with distilled water

temperature

489 g 51.7 g

3380 ml 50 ⁰ C

§ 09836/0731

Solution C

AgNO ₃ 1020 g

Made up to a total volume of 3380 ml with distilled water

Temperature 50 C

Solution D

Dye I 0.78 g

Mixture of methanol and water

in a ratio of 1: 1,500 ml

Distilled water 127 ml

Temperature 50 ⁰ C

Level 1 :

Solution A was increased to 80 ° C / pH = 5.55 / pAg = 7.2 brought.

Level 2 :

Solutions B and C were added simultaneously to solution A with stirring over a period of 90 minutes. 10 minutes after the start of the 'addition of solutions B and C, solution D became within a period of 34 minutes Solution A added.

Level 3 :

The emulsion was cooled to 33 ° C. and coagulated by reducing the pH to 3.90. The supernatant liquid was decanted, was redispersed after which the coagulum in water at a pH of 6.0 and a temperature of 40 ⁰ C. This procedure was repeated, whereupon the coagulum was redispersed at a pH of 5.6 and a pAg of 7.6 after adding a solution of distilled water (600 ml) and bone gelatin (120 g).

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Electron photomicrographs showed that one polydisperse cubic-octahedral emulsion with silver halide grains from 0.75 µm to 1.25 µm. The emulsion was chemically sensitized with a dye providing agent Couplers combined, coated on a support, exposed and developed as described in Example 1. the Emulsion had a relative speed of 25 compared to Example 1.

Example 9 : Gradual addition of the dye during silver iodide precipitation.

Initially, the following solutions were made:

Gelatin water temperature

pll value 6.0

Solution b
200 ml of a 2.5 molar aqueous solution of sodium iodide.

Solution C
200 ml of a 2.5 molar solution of silver nitrate.

Solution D

170 ml of a solution of 606 mg of dye VII, viz Anhydro-5,5 ', ό, 6'-tetrachloro-1,1'-diethyl-3,3'-di (3-thiosulfatopropyl) benzimidazolocarbocyanine hydroxide, Tetramethylguanidinium salt. (The dye VII was initially used in Phenoxyethanol (Dowanol, commercial product from Dow Chemical Company, USA) dissolved, whereupon the solution acidified and then by adding methanol to a volume of 170 ml was brought.

solution Λ 17th , 5 G 1 , 5 1 35 ⁰ C

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The solution A was placed in a reaction vessel and, by adding part of the solution B, was brought to a pAg value of 6.45 brought. Solutions B and C were then added simultaneously at an increasing rate (1 ml per minute as the initial rate and 9 ml per minute as the final speed) into the reaction vessel with the solution A within a period of time added from 50 minutes. The introduction of solutions B and C interrupted, whereupon the specified amounts of solution D were added:

Time (minute)
ml of solution D 5
3, 9 11
7th , 25 18th
11 1 22.2
15.6 Time (minute)
ml of solution D 28,
21 2
15th 34
27 , 2
, 3 39
32, 2
6th 44.3
37.5

After each dye addition, the emulsion was brought to pH IVert set of 7.5 and left at this pH for 2 minutes, after which a pH of 6.0 was adjusted. Thereupon the precipitation was restarted by introducing solutions B and C.

After the addition had ended, the pAg value of the emulsion was adjusted by adding an additional amount of solution C. After finished In addition, the emulsion contained 1.1 g of dye VII per mole of silver. Excess soluble salts were released from the emulsion removed by means of an ion exchange resin according to the method known from US Pat. No. 3,782,953. The emulsion was then brought to 4.5 kg / mol of silver and a pH of 3.0 and a pAg of 2.0.

Further emulsions were used in a similar manner of the following dyes:

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Dye VIII anhydro-9-methy1-3,3'-di (3-sulfobutyl) benzo-

thiazole carbocyanine, triethylamine, sodium salt;

Dye IX 5,5 ', 6,6'-tetrachloro-1,1', 3,3'-tetraethyl

benzimidazole carbocyanine p-toluenesulfonate;

Dye X 3,3'-diethyl-S ^ 5'-diphenylbenzoxazolocar-

bocyanine iodide.

the emulsions are applied to transparent photographic film supports in a layer thickness of 8.07 mg silver per

2 2

dm and 9 7 ₅ 9 mg of gelatin applied per dm of support surface.

The layers contained saponin and 2-methyl-2,4-pentanediol as spreading agents and moisturizing agents, respectively. Before coating the emulsions were brought to a pH of and a pAg of 6 at 35.degree. Samples of the received Recording materials were exposed using a step spectrograph and then exposed for 10 minutes developed for a long time at room temperature in a developer solution of the following composition:

water, about 50 ° C 500 ml

p-methylaminophenol sulfate 2.0 g

Sodium sulfite, dehydrated 90.0 g

Hydroquinone 8.0 g

Sodium carbonate, monohydrate 52.5 g

Potassium bromide 5.0 g

Poly (ethylene oxide) 1.0 g

Made up to 1 liter with cold water

The recording materials were then using fixed with a fixing solution of the following composition:

Water, about SO ⁰ C 600 ml

Sodium thiosulfate 240.0 g

Sodium sulfite, dehydrated 15.0 g

Acetic acid, 28 Ug 48.0 ml boric acid, crystalline 7.5 g

Potassium aluminum sulfate 15.0 g Make up to 1 liter with cold water

§09836 / 0733

For comparison purposes, other recording materials were used produced, exposed and exposed, but this time in the silver halide production the dye of the emulsion after the silver halide precipitation had ended, was added according to the usual method of the prior art.

The photographic recording materials under Using an emulsion prepared by the process of the invention and containing the dye VII, showed a stronger absorption band at 545 mn with a coating pAg value of 6.5 and a red-shifted one J band when used to produce the recording material an emulsion with a pAg value of 1.5 was used. For example, J bands are described in the book by T. H. · James, "The Theory of the Photographic Process," 4th Edition, MacMillan Publishing Company, pp. 218 to 222.

Dye 8 showed a bathochromic absorption shift compared to the comparative material and a J band which was not present in the comparative material. When using the dye IX, a large increase in maximum densities over the region of the visible spectrum was obtained as well a strengthening of the J band. In the case of using dye X, there was an increase in blue sensitivity achieved. Although changes in response due to the addition of the dye into the reaction vessel during the Silver halide precipitation appeared to be a function of the particular dye selected in each case but it is evident that the emulsion produced by the process of the invention differs in its properties from the Comparative emulsion differed.

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Claims (11)

Claims Process for the production of a spectrally sensitized, s reaction-sensitive silver halide emulsion, in which an aqueous solution of a silver salt, an aqueous solution of a halide salt Introduces peptizing agents and a spectral sensitizing dye, x ^ obei the dye during the üinfünrung at least one of the aforementioned aqueous salt solutions is added to the reaction vessel, characterized in that that the addition of the spectral sensitizing dye is delayed until silver halide nuclei are present in the reaction vessel. 2. The method according to claim 1, characterized in that the introduction of the spectral sensitizing dye delayed in the reaction vessel until the formed Silver halide grain cores have an average diameter that is at least one hundredth of the average Diameter of the silver halide grains of the radiation-sensitive silver halide emulsion to be prepared. 3. The method according to claim 1, characterized in that the Linführung of the spectral sensitizing dye into the reaction vessel delayed until the silver halide grain cores have a mean diameter, of at least five hundredths of the mean diameter of the silver halide grains of the radiation-sensitive grains to be produced Silver halide emulsion · is. 4. The method according to claim 1, characterized in that there is a spectrally sensitizing amount of the dye in the reaction vessel is introduced before 85 wt .- ^ of the silver salt solution have been introduced. 5. The method according to claim 1, characterized in that there is a spectrally sensitizing amount of the dye in the reaction vessel is introduced before 75% by weight of the silver salt solution have been introduced. 6. The method according to claim. 1, characterized in that one adding another spectral sensitizing dye after silver halide precipitation. 7. The method according to claim 1, characterized in that the introduction of the spectral sensitizing dye delayed in the reaction vessel until at least 1% by weight of the silver salt solution has been introduced. 8. The method according to claim 1, characterized in that the introduction of the spectral sensitizing dye delayed in the reaction vessel until at least 2% by weight of the silver salt solution have been introduced and 909836/0733 that one stops the introduction of spdstral sensibilierenden dye, before 80 weight - have been introduced% of the silver salt solution.. 9. The method according to claim 1, characterized in that the introduction of the spectral sensitizing dye into the reaction vessel is delayed until at least 5 wt. I of the silver salt solution have been introduced and that the introduction of the spectral sensitizing dye is ended before 75 wt. -I of the silver salt solution have been introduced. 1ü. Process according to Claim 1, characterized in that at least part of the silver salt solution and the ilalogenide salt solution at the same time introduced into the reaction vessel. 11. The method according to claim 1, characterized in that one the spectral sensitizing dye is added in proportions during interruptions in the introduction of the silver salt. Process according to Claim 1, characterized in that the silver salt solution and the ilalogenide salt solution are added to the Introduces reaction vessel with increasing speed. SÖ9836 / 0733