CA1105761A - Method of introducing water insoluble sensitizers or stabilizers into silver halide emulsions - Google Patents
Method of introducing water insoluble sensitizers or stabilizers into silver halide emulsionsInfo
- Publication number
- CA1105761A CA1105761A CA273,559A CA273559A CA1105761A CA 1105761 A CA1105761 A CA 1105761A CA 273559 A CA273559 A CA 273559A CA 1105761 A CA1105761 A CA 1105761A
- Authority
- CA
- Canada
- Prior art keywords
- sensitizer
- stabilizer
- water
- silver halide
- emulsion
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
- G03C1/00—Photosensitive materials
- G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
- G03C7/00—Multicolour photographic processes or agents therefor; Regeneration of such processing agents; Photosensitive materials for multicolour processes
- G03C7/30—Colour processes using colour-coupling substances; Materials therefor; Preparing or processing such materials
- G03C7/388—Processes for the incorporation in the emulsion of substances liberating photographically active agents or colour-coupling substances; Solvents therefor
Abstract
METHOD OF INTRODUCING PHOTOGRAPHIC ADDITIVES
INTO SILVER SALT EMULSIONS
Abstract of the Disclosure Photographic additives such as spectrally sensitizing dyes and stabilizers for silver salt emulsion can be incorporated by making first an aqueous dispersion of the sensitizer or stabilizer by milling said substances to form particles of an average grain size of less than 1 /um in an aqueous phase which is substantially free from organic solvents in the presence of a dispersing agent which gives rise to a surface tension of not less than 38 dyn/cm in water when used in a quantity of 1g/1. The aqueous dispersion of sensitizer or stabilizer may then be taken up in an aqueous hydrophilic binder solution, and may then be prepared for further use or storage by freeze-drying or spray drying.
INTO SILVER SALT EMULSIONS
Abstract of the Disclosure Photographic additives such as spectrally sensitizing dyes and stabilizers for silver salt emulsion can be incorporated by making first an aqueous dispersion of the sensitizer or stabilizer by milling said substances to form particles of an average grain size of less than 1 /um in an aqueous phase which is substantially free from organic solvents in the presence of a dispersing agent which gives rise to a surface tension of not less than 38 dyn/cm in water when used in a quantity of 1g/1. The aqueous dispersion of sensitizer or stabilizer may then be taken up in an aqueous hydrophilic binder solution, and may then be prepared for further use or storage by freeze-drying or spray drying.
Description
;7~
This invention relates to a method o~ introducing photographic additives which are substantially insoluble in water into silver salt emulsions such as light-sensitive photographic silver halide emul~ions or light-insensitive silver salt emulsions comprising silver salts of long chain carboxylic acidsO The additives should be of the kind which are capable of influencing the silver salt in silver salt emulsions, e~gO sensitizers or stabilizersO
The invention thus relates to a method of stabilizing or spectrally sensitizing silver salt emulsions by means of stabilizers or spectrally sensitizing dyes which are practically insoluble in water.
It .is known that photographic additives which are capable of being adsorbed on the grain surfaces of silver salts, such as sensitizing dyes or stabili~ers, may be added to photographic sil~er halide emulsions in the form of solutions in suitable solvents such as methyl alcohol . ~
or dimethylformamlde (see P. Gla~kides, Photographic :Chemistry, London, 1958, Volume II7 pages 902 and 90~)~
; These known methods, however, are unsuitable for the incorporat.ion of stab1lizers or spectrally se~si$i~ing dyes whioh are praotically insoluble in water ~nd difficult to dissolve in the usual 30lve~ts because, a~ is ~nown, e~.cessive quantitie~ of solvents oause diificulties connected with the dif~sion or migratio~ of the sensitizing dye3 A-G 1413 - 2 ~ ~ ~
~ 57~
within the emulsion as described in Column 1 o~ German Patent Specification No. l,964,l69.
It is known that other emulsion additive~ such as colour couplers which need not be held on the surface o~
the silver halide crystal by adsorption after their introduction into the photographic emulsion can be incorporated in the silver halide emulsion in the form of dispersions. For this purpose, the coupler compound is usually dissolved in a suitable solvent which is generally immiscible with water, optionally in the pre~ence of an oil ~ormer and suitable wetting agent, and then emulsified in an aqueous gelatine solution. The low boiling solvent is generally subsequently removed from the emulsion and the resulting dispersion i9 added to the photographic silver halide emulsion.
The application of ~uch a method o~ incorp~ra~
tion for the purpose of spectrally sensitizing a ~ilver hali~e emulsion has been described in German Patent Specification No. 1,547,705. In German Patent Spe¢ifioation No~ l,964,169 a procass is dascribed in whioh the preparatio~ of a :disper~ion oi speotrally sensitizing dye~ in an &queou~
gelatin~ solution is a¢hieved b~ the ~ollowing operations:
he sensitizing dya a~d an organio liquid WhiGh i9 mi~oible with water are ground up together and
This invention relates to a method o~ introducing photographic additives which are substantially insoluble in water into silver salt emulsions such as light-sensitive photographic silver halide emul~ions or light-insensitive silver salt emulsions comprising silver salts of long chain carboxylic acidsO The additives should be of the kind which are capable of influencing the silver salt in silver salt emulsions, e~gO sensitizers or stabilizersO
The invention thus relates to a method of stabilizing or spectrally sensitizing silver salt emulsions by means of stabilizers or spectrally sensitizing dyes which are practically insoluble in water.
It .is known that photographic additives which are capable of being adsorbed on the grain surfaces of silver salts, such as sensitizing dyes or stabili~ers, may be added to photographic sil~er halide emulsions in the form of solutions in suitable solvents such as methyl alcohol . ~
or dimethylformamlde (see P. Gla~kides, Photographic :Chemistry, London, 1958, Volume II7 pages 902 and 90~)~
; These known methods, however, are unsuitable for the incorporat.ion of stab1lizers or spectrally se~si$i~ing dyes whioh are praotically insoluble in water ~nd difficult to dissolve in the usual 30lve~ts because, a~ is ~nown, e~.cessive quantitie~ of solvents oause diificulties connected with the dif~sion or migratio~ of the sensitizing dye3 A-G 1413 - 2 ~ ~ ~
~ 57~
within the emulsion as described in Column 1 o~ German Patent Specification No. l,964,l69.
It is known that other emulsion additive~ such as colour couplers which need not be held on the surface o~
the silver halide crystal by adsorption after their introduction into the photographic emulsion can be incorporated in the silver halide emulsion in the form of dispersions. For this purpose, the coupler compound is usually dissolved in a suitable solvent which is generally immiscible with water, optionally in the pre~ence of an oil ~ormer and suitable wetting agent, and then emulsified in an aqueous gelatine solution. The low boiling solvent is generally subsequently removed from the emulsion and the resulting dispersion i9 added to the photographic silver halide emulsion.
The application of ~uch a method o~ incorp~ra~
tion for the purpose of spectrally sensitizing a ~ilver hali~e emulsion has been described in German Patent Specification No. 1,547,705. In German Patent Spe¢ifioation No~ l,964,169 a procass is dascribed in whioh the preparatio~ of a :disper~ion oi speotrally sensitizing dye~ in an &queou~
gelatin~ solution is a¢hieved b~ the ~ollowing operations:
he sensitizing dya a~d an organio liquid WhiGh i9 mi~oible with water are ground up together and
2. the resulting ground material is added to ~n aquaous ; gelatine ~olution. In this process, the organio liquid ha~ the objeot o~ producing a separating ef~ect of the dye moleoulas during the grindin~ prooess and thu3 preventing A-~ 1413 3 -.f.~
agglomeration of the dyestuff particles~
A disadvantage of this known process, however, is that removal of the solvent from the resulting di~persion can only be achieved if low boiling organic solvents have been used, and even then only to a certain extent whereas attempts to remove polar solvents cause considerable problems~ Polar solvents, in particular polar protic solvents, can be removed from gelatine dispersions only by heating, a process which has a very harm$ul e~fect on the stability of the sensitizing dye molecule. Moreover, removal o~ the solvent from the disperYion under vacuum may c~use considerable ~oami~g.
Even when non-polar solvents are use~, all the known methods of removing low boiling solvents from aqueous dispersions are unsatis~actory in prao-ticeO If elevated temperatures are not used for evaporating of~
the solvent, only an insuf~icient qu~ntity o~ solvent can be removedO Applicatlon o~ a vaouum is contraindicated by the foaming which i liable to oocur, as already mentioned above, ~hioh is inoreased under vacuum conditionsO Applica-tion o~ elevated evaporatlon~temperature~, however, i~
unadvisable~ as alread~ mentioned above, owing to the readiness o~ the sensitizing dyes to decompose.
: : :
Residues o~ solvent le~t in the dispersion are a disadvantage for several rea~ons. First, even minute residues o~ solvent promote recrystallisation pro~esses in the photographic layer, which deleteriou~ly ~fect not 13 _ 4 _ ' ' -only the additives which have been specially introduced but also other additives such as coupler compounds.
Moreover, i~ residues of polar org~nic solvents which are miscible with water are left in silver halide emulsions, in particular in emulsions which are rich in silver. and have a hi~h silver packing density, they considerably reduoe the stability of the casting emulsion, and this is sho~ in a reduced stability to digestion. The following problems are then liable to occur: Phase separation between the hydrophilio and hydrophobic phase~ agglomeration and coalescence as well as flocculation before castingO
For a long time now there has therefore bee~ a need for a process by which even photographic additives which are virtually insoluble in water, such as sensitizing dyes or stabilizers, c~n be incorporated in silver salt emulsions without any harmful ef~ects to the emulsion layer due to the presenoe of water-miscible or water-immiscible organic solvents and wi-thout the dispersions required for preparation o~ the emulsion layers undergoing any deleteriou~ cha~ges even when leit to st~nd ~or proIonged periods~ ~
It is an objeot of the pre3ent invention to provide :~ a proces~ by means o~ which eYen photographlc additives which are practioally insoluble in water9 such as ~5 stabilizers and Bensitizing dyes, oan be incorporated in : silvcr salt emulsion~ 90 that these emulsions can be , .
ef~e¢tively s~abilized even with stabilizer3 which are ~ 1413 ~ 5 ~
:-' 7~:~
insoluble in water and can be effectively sensitized with sensit-iæin~ dyes which are insoluble in water.
Accordingly, the invention provides process for introducing a substantially water-insoluble sensitizer or stabil-izer into a light-sensitive silver halide emulsion comprising the steps of:
(a) preparing an aqueous dispersion of a substantial-ly water-insoluble sensitizer or stabilizer having a particle size of less ~han 1 ~, and ~b) adding the aqueous or dried dispersion of said substantially water-insoluble sensitizer or stabilizer to a light-sensitive silver halide emulsion, the aqueous dispersion of step ~a) being prepared by milling the sensitizer or stabilizcr in an aqueous phase which is substantial-ly free from organic solvents in the presence of a dispersing ~
agent selected from monomeric, oligomeric and polymeric alkyl-aryl sulphonates, The present invention thus rela~es to a process for the introduction into a silver salt emulsion of photographic 20 additives which are substantially insoluble in water~ which additives have been milled to a particle size of less than 1 micron and are capable of influencing the sensitometric proper-ties of the silver salt in si~lver salt emulsions, as is the case with stabilizers or sensitizers.
The process is characterised in t~at the substantially water-insolu~le photographic additive is milled in the aqueous phase which is su~stantially free from organic solvents in the presence of surface-active substances ~so-called dispersing agents), preferably those which give rise to a surface tension of not less than 38 dyn/cm in water ~hen used in a quantity of 1 g/l, and the resulting aqueous dispersion is added to the silver L ",~
salt emulsion, either immediately or af~er storage or after purification and isolation.
In contrast to the known methods, the method accord-ing to the invention consists of grinding the photographic additive without substantial amounts of any water-miscible organic solvent so that when the photographic additives are introduced into emulsions by the method according to the invention, no time and labour consuming removal of solvents from the resulting dispersions is necessary and, moreover, the emulsion layers are in no way affected by unwanted residues of organic liquids.
- 6a -f~
"; "
In addition, the method according to the invention requires no precautions for ab~orption of ~olvent from the surrounding atmosphere when the silver ~alt emul~ion is being cast or dried, so tha-t the method according to the invention does not give rise to any environmental problems.
In the method according to the invention, milling the photographic additive is carried out in an aqueouæ
phase9 iOeO a phase consisting mainly of water, eOg.
dis~illed water or tap w~terO ~he aqueous pha~e may also contain minor quantitias o~ the usual additives which may occur, ~or example, in tap water. Such additives may include calcium salts in quantities of not more than about 0,5% or traoes of hea~y met~l~0 I~ desired, the ~queous phase may also contain hydrophilio binders suoh a~ gelatine or inorganio or organic salt~ such a~ sodium chloride or water æoftenersO
Aocording to the i~Yentio~, however, the aqueous phase does not contain substantial amounts o~ any or-ganic solvents which would be capable of partially dissolv-ing the photo~raphic additivesO The a~ueous phase ln which : the photographic additive is dispersed may be ~ompletely free from org~nic solventsO It is~ however~ consldered to be within the ambit o~ this in~ention~ lf the aqueous phase con-tains a ~ery small amou~t or traces of an organic solvent~
provlded however~ that such solvent does not ex~.eed an amount of 1 % by weight9 based on the amount of photographic additive to be dispersedO Su~-h small amount of organic sol~ent in the aqueous phase may have its origin ~rom an organic qolvent in A-~ 1413 _ 7 _ which the photographic additive has been crystallized and which has not completely been removed from the additiveO Also a very small amount of organic solvent such as amyl alcohol may have been deliberately added as an antifoaming agentO
According to the invention, milling is carried out in the presence of a dispersing agentO The term l'dispersing agent" for sur~ace active substances is in practice applied to organic compounds which are soluble in water but practically insoluble in organic solvents and which, in contrast to the so-called wetting agent~, reduce the surface tension of water to an only insigni~icant extent and pre-ferably to not less than 38 dyn/cm when used Pt a concentra~
tion o~ 1 g/l of waterO
Methods of introducing coupler compounds into photographic emulsions are known in the art, according to which couplers are milled in the presence of wetting agents and suitable coupler solvents.
It was surprising to find that, when w~tting agents were used instead of dispersing agents in the prooess aacording $o the invention> the resul$s obtained were praotically u~eless because the milllng operation g~e rise to extremely di~flcult problems. It was practioally impo~sible to prevent ~oaming and the subst~nae belng milled migrated ~ro~ the milling elements due to ~lotation so that fur-ther reductio~ to the required size was impo sible~
'rhe quantity o~ di~persing agent required in the process according to the in~e~tion, based on the quantity ,~
s~
of phctographic additive required $o be dispersed, may vary within wide limits and depends mainly on the nature of the dispersing agen~ used and the particular photographic additiveO It has generally been found to be suf~icient to add from O.l to 3 parts by weight of dispersing agent to l part by weight of photographic addi$ive but it is al~o possible to add more tha~ 3 part~ of dispersing agentO
When the additives used are eOgO spectral sen~itizers or stabilizers9 the aqueous dispersions prepared aocording to the invention are ~ound to have excellent stability in storage, particularly if an aqueous solution o~ a water-soluble polymer, e.g. an aqueous gelatine solution, has been added to the aqueous phase after milling and removal of the milling elements. An aqueous gelatine dispersion prepared in this way can be stored for months at room temperature without showing ~ny signs o~ decomposition of the dispersed dye molecules or dispersed stabilizer molecules and henoe without reduction of $he spectral sensitizing efiect or stabilizing e~fect aiter addition to the emulsion.
If desired, however, an aqueous dispersion oontaini~g peptides may be stored by casting i~ on a substrate and drying. A~ter the desired storage time, the dried disper~ion may be redissolved a~d added to the photographic emulsion~
In another embodiment o~ the process according to the invention, the aqueou3 dispersion is worked up under particularly careiul a~d mild conditio~s to be oonYerted into a ~ery stable and durable iorm ~e~ore it i~ introduced into the photographic emulsion. I~ thi3 ~orm, it can easily 7~
be added to the photographic emulsion at any time without any complicated operations to dissolve it and/or application o~ heat.
According to a preferred embodiment of the invention, the aqueous dispersion i~ worked up by drying in one of the usual apparatus of the kind employed in the art for working up formed pigments or dyes, e.g. paddle driers, disc atomizeris or, pre~erably, apparatus of the kind which are suitable ~ for atomization drying or freeze drying.
- 10 Freeze drying or atomization drying effects very oareful removal o~ the water used ~or dispersion without causing any agglomeration or caking of the dispersed particlesO
The iapparatus used ~or atomization drying may be equipped with a one-material nozzle, which normally produces a granulate, or a two-material nozzle, which produces a powder. Further details about atomization dryi~g may be found in the handbook by Ullman~, Enzyklop~die der Teohnischen Chemie, 4th Edition, Vol~ 2, pages 255 et seq.
The partioulate photographio additive produced in this way cRn be kept practicall~ inde~in~tely and is extremely st~ble and~can be stored in a very sm~ll spacs, whi¢h was impossiblb for addltiYes prepared by the ~now~
prooes~e~.
~5 ~he particulate photogr~phic additive may be added to the liquid photographio emul ion at any time after its preparation~
A-G 141~ - 10 -:
7~
I~ desired, however, the additive may first be mixed with water or an aqueous binder solution to produce an aqueous dispersion and added to the liquid photographic emulsion in this formO
The method o~ addition is immaterial and depends mainly on the nature of the photographic emulsion and the desired effect~ For preparing an emulsion which has a low gelatine content but high silver content, direct introduction of the particulate photographic addi$ive or introduction of the additive in the ~orm of a highly concentrated aqueous dispersion are both suitable.
Examples of ~uitable dispersing agents whioh may be used according to the invention include monomeric, oligomeric and polymeric alkyl aryl sulphonates, pre~erably having at least 18 carbon atoms.
Examples of monomeric alkyl-aryl sulphonates i~clude the alkali metal salts o~ biisopropylnap~thalene sulpho~ic acids a~d di sec~-butylnaphthalene sulphonic acids.
E~amples of oligomeric and po1ymerio alkyl-aryl sulphonates include ¢o~densation products of naphthale~e or ditolylether with formaldehyde and sulphuric acid or lignin sulphonic acids.
Milling o~ the photographic additives tQ red~ce them to particle size~ of le~9 tha~ l mioron is carried out in suitable mills of the kind already kno~ but their ~hearing force~ must be su~ioient to reduoe the material to the necessary partiole si~e w~thin a ~uitable length of tims~
Suitable ~iIls of this kind are a~ailable eo~mer¢ially under the general heading b~ oolloid mill~.
. ' ' ' ~
Colloid mills which are particularly suitable for the process according to the invention are the so-called sand millsO
~he ~ollowing are examples of types of mills avilable on the market:
lo Sand mill manufactured by P. Vollrath, Maschinen~abriken K81n 20 ~ead mill manufactured by Draiswerke GmbH, Mannheim
agglomeration of the dyestuff particles~
A disadvantage of this known process, however, is that removal of the solvent from the resulting di~persion can only be achieved if low boiling organic solvents have been used, and even then only to a certain extent whereas attempts to remove polar solvents cause considerable problems~ Polar solvents, in particular polar protic solvents, can be removed from gelatine dispersions only by heating, a process which has a very harm$ul e~fect on the stability of the sensitizing dye molecule. Moreover, removal o~ the solvent from the disperYion under vacuum may c~use considerable ~oami~g.
Even when non-polar solvents are use~, all the known methods of removing low boiling solvents from aqueous dispersions are unsatis~actory in prao-ticeO If elevated temperatures are not used for evaporating of~
the solvent, only an insuf~icient qu~ntity o~ solvent can be removedO Applicatlon o~ a vaouum is contraindicated by the foaming which i liable to oocur, as already mentioned above, ~hioh is inoreased under vacuum conditionsO Applica-tion o~ elevated evaporatlon~temperature~, however, i~
unadvisable~ as alread~ mentioned above, owing to the readiness o~ the sensitizing dyes to decompose.
: : :
Residues o~ solvent le~t in the dispersion are a disadvantage for several rea~ons. First, even minute residues o~ solvent promote recrystallisation pro~esses in the photographic layer, which deleteriou~ly ~fect not 13 _ 4 _ ' ' -only the additives which have been specially introduced but also other additives such as coupler compounds.
Moreover, i~ residues of polar org~nic solvents which are miscible with water are left in silver halide emulsions, in particular in emulsions which are rich in silver. and have a hi~h silver packing density, they considerably reduoe the stability of the casting emulsion, and this is sho~ in a reduced stability to digestion. The following problems are then liable to occur: Phase separation between the hydrophilio and hydrophobic phase~ agglomeration and coalescence as well as flocculation before castingO
For a long time now there has therefore bee~ a need for a process by which even photographic additives which are virtually insoluble in water, such as sensitizing dyes or stabilizers, c~n be incorporated in silver salt emulsions without any harmful ef~ects to the emulsion layer due to the presenoe of water-miscible or water-immiscible organic solvents and wi-thout the dispersions required for preparation o~ the emulsion layers undergoing any deleteriou~ cha~ges even when leit to st~nd ~or proIonged periods~ ~
It is an objeot of the pre3ent invention to provide :~ a proces~ by means o~ which eYen photographlc additives which are practioally insoluble in water9 such as ~5 stabilizers and Bensitizing dyes, oan be incorporated in : silvcr salt emulsion~ 90 that these emulsions can be , .
ef~e¢tively s~abilized even with stabilizer3 which are ~ 1413 ~ 5 ~
:-' 7~:~
insoluble in water and can be effectively sensitized with sensit-iæin~ dyes which are insoluble in water.
Accordingly, the invention provides process for introducing a substantially water-insoluble sensitizer or stabil-izer into a light-sensitive silver halide emulsion comprising the steps of:
(a) preparing an aqueous dispersion of a substantial-ly water-insoluble sensitizer or stabilizer having a particle size of less ~han 1 ~, and ~b) adding the aqueous or dried dispersion of said substantially water-insoluble sensitizer or stabilizer to a light-sensitive silver halide emulsion, the aqueous dispersion of step ~a) being prepared by milling the sensitizer or stabilizcr in an aqueous phase which is substantial-ly free from organic solvents in the presence of a dispersing ~
agent selected from monomeric, oligomeric and polymeric alkyl-aryl sulphonates, The present invention thus rela~es to a process for the introduction into a silver salt emulsion of photographic 20 additives which are substantially insoluble in water~ which additives have been milled to a particle size of less than 1 micron and are capable of influencing the sensitometric proper-ties of the silver salt in si~lver salt emulsions, as is the case with stabilizers or sensitizers.
The process is characterised in t~at the substantially water-insolu~le photographic additive is milled in the aqueous phase which is su~stantially free from organic solvents in the presence of surface-active substances ~so-called dispersing agents), preferably those which give rise to a surface tension of not less than 38 dyn/cm in water ~hen used in a quantity of 1 g/l, and the resulting aqueous dispersion is added to the silver L ",~
salt emulsion, either immediately or af~er storage or after purification and isolation.
In contrast to the known methods, the method accord-ing to the invention consists of grinding the photographic additive without substantial amounts of any water-miscible organic solvent so that when the photographic additives are introduced into emulsions by the method according to the invention, no time and labour consuming removal of solvents from the resulting dispersions is necessary and, moreover, the emulsion layers are in no way affected by unwanted residues of organic liquids.
- 6a -f~
"; "
In addition, the method according to the invention requires no precautions for ab~orption of ~olvent from the surrounding atmosphere when the silver ~alt emul~ion is being cast or dried, so tha-t the method according to the invention does not give rise to any environmental problems.
In the method according to the invention, milling the photographic additive is carried out in an aqueouæ
phase9 iOeO a phase consisting mainly of water, eOg.
dis~illed water or tap w~terO ~he aqueous pha~e may also contain minor quantitias o~ the usual additives which may occur, ~or example, in tap water. Such additives may include calcium salts in quantities of not more than about 0,5% or traoes of hea~y met~l~0 I~ desired, the ~queous phase may also contain hydrophilio binders suoh a~ gelatine or inorganio or organic salt~ such a~ sodium chloride or water æoftenersO
Aocording to the i~Yentio~, however, the aqueous phase does not contain substantial amounts o~ any or-ganic solvents which would be capable of partially dissolv-ing the photo~raphic additivesO The a~ueous phase ln which : the photographic additive is dispersed may be ~ompletely free from org~nic solventsO It is~ however~ consldered to be within the ambit o~ this in~ention~ lf the aqueous phase con-tains a ~ery small amou~t or traces of an organic solvent~
provlded however~ that such solvent does not ex~.eed an amount of 1 % by weight9 based on the amount of photographic additive to be dispersedO Su~-h small amount of organic sol~ent in the aqueous phase may have its origin ~rom an organic qolvent in A-~ 1413 _ 7 _ which the photographic additive has been crystallized and which has not completely been removed from the additiveO Also a very small amount of organic solvent such as amyl alcohol may have been deliberately added as an antifoaming agentO
According to the invention, milling is carried out in the presence of a dispersing agentO The term l'dispersing agent" for sur~ace active substances is in practice applied to organic compounds which are soluble in water but practically insoluble in organic solvents and which, in contrast to the so-called wetting agent~, reduce the surface tension of water to an only insigni~icant extent and pre-ferably to not less than 38 dyn/cm when used Pt a concentra~
tion o~ 1 g/l of waterO
Methods of introducing coupler compounds into photographic emulsions are known in the art, according to which couplers are milled in the presence of wetting agents and suitable coupler solvents.
It was surprising to find that, when w~tting agents were used instead of dispersing agents in the prooess aacording $o the invention> the resul$s obtained were praotically u~eless because the milllng operation g~e rise to extremely di~flcult problems. It was practioally impo~sible to prevent ~oaming and the subst~nae belng milled migrated ~ro~ the milling elements due to ~lotation so that fur-ther reductio~ to the required size was impo sible~
'rhe quantity o~ di~persing agent required in the process according to the in~e~tion, based on the quantity ,~
s~
of phctographic additive required $o be dispersed, may vary within wide limits and depends mainly on the nature of the dispersing agen~ used and the particular photographic additiveO It has generally been found to be suf~icient to add from O.l to 3 parts by weight of dispersing agent to l part by weight of photographic addi$ive but it is al~o possible to add more tha~ 3 part~ of dispersing agentO
When the additives used are eOgO spectral sen~itizers or stabilizers9 the aqueous dispersions prepared aocording to the invention are ~ound to have excellent stability in storage, particularly if an aqueous solution o~ a water-soluble polymer, e.g. an aqueous gelatine solution, has been added to the aqueous phase after milling and removal of the milling elements. An aqueous gelatine dispersion prepared in this way can be stored for months at room temperature without showing ~ny signs o~ decomposition of the dispersed dye molecules or dispersed stabilizer molecules and henoe without reduction of $he spectral sensitizing efiect or stabilizing e~fect aiter addition to the emulsion.
If desired, however, an aqueous dispersion oontaini~g peptides may be stored by casting i~ on a substrate and drying. A~ter the desired storage time, the dried disper~ion may be redissolved a~d added to the photographic emulsion~
In another embodiment o~ the process according to the invention, the aqueou3 dispersion is worked up under particularly careiul a~d mild conditio~s to be oonYerted into a ~ery stable and durable iorm ~e~ore it i~ introduced into the photographic emulsion. I~ thi3 ~orm, it can easily 7~
be added to the photographic emulsion at any time without any complicated operations to dissolve it and/or application o~ heat.
According to a preferred embodiment of the invention, the aqueous dispersion i~ worked up by drying in one of the usual apparatus of the kind employed in the art for working up formed pigments or dyes, e.g. paddle driers, disc atomizeris or, pre~erably, apparatus of the kind which are suitable ~ for atomization drying or freeze drying.
- 10 Freeze drying or atomization drying effects very oareful removal o~ the water used ~or dispersion without causing any agglomeration or caking of the dispersed particlesO
The iapparatus used ~or atomization drying may be equipped with a one-material nozzle, which normally produces a granulate, or a two-material nozzle, which produces a powder. Further details about atomization dryi~g may be found in the handbook by Ullman~, Enzyklop~die der Teohnischen Chemie, 4th Edition, Vol~ 2, pages 255 et seq.
The partioulate photographio additive produced in this way cRn be kept practicall~ inde~in~tely and is extremely st~ble and~can be stored in a very sm~ll spacs, whi¢h was impossiblb for addltiYes prepared by the ~now~
prooes~e~.
~5 ~he particulate photogr~phic additive may be added to the liquid photographio emul ion at any time after its preparation~
A-G 141~ - 10 -:
7~
I~ desired, however, the additive may first be mixed with water or an aqueous binder solution to produce an aqueous dispersion and added to the liquid photographic emulsion in this formO
The method o~ addition is immaterial and depends mainly on the nature of the photographic emulsion and the desired effect~ For preparing an emulsion which has a low gelatine content but high silver content, direct introduction of the particulate photographic addi$ive or introduction of the additive in the ~orm of a highly concentrated aqueous dispersion are both suitable.
Examples of ~uitable dispersing agents whioh may be used according to the invention include monomeric, oligomeric and polymeric alkyl aryl sulphonates, pre~erably having at least 18 carbon atoms.
Examples of monomeric alkyl-aryl sulphonates i~clude the alkali metal salts o~ biisopropylnap~thalene sulpho~ic acids a~d di sec~-butylnaphthalene sulphonic acids.
E~amples of oligomeric and po1ymerio alkyl-aryl sulphonates include ¢o~densation products of naphthale~e or ditolylether with formaldehyde and sulphuric acid or lignin sulphonic acids.
Milling o~ the photographic additives tQ red~ce them to particle size~ of le~9 tha~ l mioron is carried out in suitable mills of the kind already kno~ but their ~hearing force~ must be su~ioient to reduoe the material to the necessary partiole si~e w~thin a ~uitable length of tims~
Suitable ~iIls of this kind are a~ailable eo~mer¢ially under the general heading b~ oolloid mill~.
. ' ' ' ~
Colloid mills which are particularly suitable for the process according to the invention are the so-called sand millsO
~he ~ollowing are examples of types of mills avilable on the market:
lo Sand mill manufactured by P. Vollrath, Maschinen~abriken K81n 20 ~ead mill manufactured by Draiswerke GmbH, Mannheim
3. Dy,no mill manufactured by W.A. Bachofen~
Masehinen~abriken, Basel, 10 4. Masap mills manufactured by Masap AG Matzendorf Schweiz Processes and suitable mills have also been described in US Patent Specifications No. 2,581,414 and 2,855,156.
An example of a sand mill suitable for use on a laboratory scale is show~ in Figure 1.
The container B for the milling process may be made of glass or steel, Steel eontalners used ~or *he proeess according to the invention are pre~erably made of hardened ~: steel to pre~ent exeessi~e abrasion whieh would cause , 20 considerable contamination o~ the dispersion and hence of ;~ ~ the~photographic emulsion and ~ay have a deleterious e~feet ,~ on the photographie properties of the emul~ion.
~he mill container B i~s enolosed in a eooling iacket ~: of PV~ or metal K and may be oooled during the milling :: :
:~ 25 proeess br a eoollng liquid F~ Running water used as eoolant i s generally su~ieie~t to effeet praetieally eomplete removal o~ the heat produoed by milllng and to ensure that A-G ~413 - 12 -:: .
:, , :
'7~L
the temperature of the material being milled does not rise above 40C o The dimensions of the container are: Wall thickness 4mm, internal wqdth 75 mm, height 230mm. A
stirrer shaft R having a diameter of 15 mm and carrying four Duramid or Durethan discs 5 mm in thickness and 60 mm in diameter extends into the containerO The four di~cs are arranged at intervals of 20 mm.
The shaft is rotated at the rate of lO~ revs/min~
by a drive motor Mo 'rhe motor may be arranged cen$rally or laterally to the drive shaft and may drive the shaft via a cone beltO
The container is filled to about one third of its height and from about 5 to 80 g o~ substance are milled in each cycle. This re~uires the addition of a$ least about 3 to 4 times this quantity of milling elementsO
rrhe average partiole diameter o~ the milling elements used depends on the particle diameter o$ the substance before it is milled. Optimum results ars obtained i~ the average particle diameter of the substance to be milled i9 le9s than or equaI to two-thirds of $he particle diameter of the milling elements. I~ the substanoe to be ~ilied : has a greater partiole di~meter~ it is advisable *irst to size reduoe it by one o~ the usual methods.
~; The quantity of water required $or milling may vary from 20 ml to 200 ml dependi~g on the subst~nce to be milled and the dispersing age~t, and the quantity o~
dispersing agent u~ed may also vary within wide limits, as already men-tioned above.
A-G 141~ ~ 13 -7~
A milling cycle is generally as follows:
~0 g of substance to be milled are mixed with 200 g of glass beads7 e~g. reflex beads of Dragonwerk ~eorg Wild, ]3eyreuth, having a diameter of from 0.85 mm to 0095 mm, depending on the particle si~e of the sub~tance to be milled, and the substance is then milled together with lO0 ml of water and 15 ml of a 40~ dispersing agent, using the laboratory sand mill described in Figure 1 (3 hours at a rate of stirring of 7000revs/min. The temperature inside the mill is kept below 40G by adjusting the rate of flow of cooling water The ~hole contents of tha mill are then filtered into a glass filter pot through a glass fri$
- (pore size 40 to 90 ~m)0 According to one particular embodiment, the glass filter pot contains 2.5 l of a lO~ gelatine solution ~hich has been heated to 40C. A ~urther 2.5 l o~ a lO~
gelatine solution are subsequently added to the ~iltrate ~nd the ~olume of the resulting dispersion i6 made up to lO 1 with water.
The filtrate obtained in this way is again briefly heated to 40C an~ then stored at ~C to solidl~y~
The dispersion~ which ~olidi~ies in a gel form~ may now be added to the photographic ~ilver halide emulsion either immediately or a~-tsr ~urther storage~
Instead of u~ing the glas~q beads desoribed above as milling element~, it i~q al~o po~sible to u~e quartz ~md or ~ilico~ carbide sand.
According to the preferred embodiment, the ~iltrate obtained as described above is immediately subjected either to freeze drying or to spray drying, as will be described in ~etail below.
The photographic additive used in the process according to the invention is dispersed in the aqueous phase in ; the presence of dispersing agents without being dissolved.
Any photographic sp0ctrally sensitizing dye may be subjected to the process according to the invention. Particularly suitable are those dyes which are practically insoluble in aqueous solutions, e.gO dyes which have a solubility in water o~ less than about 0.1% at 20C. Dyes suitable for carrying out the process of the in~ention have already been disclosed .in n~erous patent specifications, for example some have been described in German Patent Specification NoO 1,964,169.
The following Table A shows a ~umber o~ spectrally sensitizing dyes which have bee~ used in the ex~mples described hereinafterO
.
Table A
, .
Dye-stuff No~ ~or~l 2H5 C2~5 ~N 'N ~ ;E~s~
NC~ J~ C~
(~2~4~ 0~C~3 Table A (Continuation) II
C6H5 ~C2H5 ~C6H5 (~H2)4S03N~ 2)45 3 CH ~ C2H5~ ~ CH~
III ~ ~ CH ~ H - ~ CH3 C ~ 5 (CX233so ~
:, ~ CH3~ ~ C2~ ~
V ~- CH C -~
~2)3SO3 -:: " ~H :
V 3 ~=CN-C~CN~
1H2CH2COO~
' V~ ' ~ C2H5 ~"Cl 2 H5(Cll233So~9 .. . .. .. .
';- - , ~, ', .
i7$~
:
`~ Table A (Continuation) V~
C2~5 (CH2)3 , : :; Dye-stuff-No. Formula VIII ~ ~J=CH-C=C--S S--1 1 J
C N J~NJ;CI;-C ~
; ,~;
., ~
; IX ~ N C2H5 : CzH5 ~
, ~: ~ : :
x c~L ~1 2H5 (C H2 ) 3$0~3 ;:
: : A-G 1413 - 17 ~
,:
:' ' :
~; :
:
The dye dispersions used in the process according to the invention may also contain binders, for example, gelatine. The proportion of dye to gelatine may vary ~ithin a wide range but, for spectral sensitization, the best results are obtained with dispersions in which the ~ye content is between 5 and 20~, based on the total ~eigh-t of dye and binderO The dye dispersions used for spectral sensitiza$ion of photographic ~ilver halide emulsions in the process according to the invention may also contain two or more dyes in each dispersion, or dispersions containing only one dye may be used in combination with two or more ; such dispersions. For achieving optimum sensitivity by the process according to the invention, the optimum concentration of dye incorporated in the emulsions may generally vary between about 0~2 and 4 g of dye per mol of silver halide in the emulsion, depe~ding on the particular dye and emulsion used. Fi~e grained emulsions generally require a large quantity of sensiti~ing dyes than coarse grained emulsions.
Any photographic stabilizers m~ be used in the process according to bhe invention. Particularly suitable again are those w~ioh are pr~ctically insoluble in aqueous ~ solution~ e.g. stabilizers havi~g a ~olubility of less - than about Ool~ in wate~ at 20C.
Examples of suoh stabilizers are known and have been described in numerous publioations,eOg, in ~S Patent Speci~ication No. 3,692,527 7~;~
The following Table B shows stabili~ers used in the examples described hereinafterO
Table B
Stabilizer No.. Formel XI ~ N~ H
~ C~
XI~ CH ~ SH
.'~ .
~' , :;
~, : AG 1413 - 19 ~
, . .
~5 ~
The stabilizer dispersions used in the process according to the invention may also contain polymeric binders such as gelatine. The ratio of stabilizer to gelatine may vary over a wide range but, for stabilization, it has also generally been found suitable to use disper~ions having a stabilizer content o~ from abou-t 5 to 20~, based on the total weight of stabilizer and binderl For achieving sufficient stabilization by the process according to the inven-tion, the concentration of stabilizer incorporated in -the silver salt emulsions may be varied from 20 mg to 2 g of stabilizer per mol of silver salt, depending on the nature of the stabilizer and of the emulsion u~qed.
~he process according to the inven$ion is particularly suitable for the spectral sensitization or stabilization of any photographic silver salt emulsio~sO The light-sensitive silver halide may be dispersed in any hydrophilic colloids (binders~ suitable for dispersing silver halides, e.g~
gelatine; albumen; alginic aoid; polyvinyl aloohol; polyvinyl ; pyrrolidone; cellulose ethers or partially hydrolysed cellulose acetate. The hydrophilic oolloid may also contain dispersed vinyl polymers or water-insoluhle polymers of alkyl acrylates and methacrylates~ aorylic aoid~ sulpho-~- alkylacrylates or methacrylate~0 Suitable photographic silver salt emul~ions include light-sensitive silver halide emul~ions or silver salt emulsions i~ whioh the silver salt consists partly or comp1etely of light insensitive silver salts of long chain A-G 1413 - 20 ~
.
.. . . .
aliphatic carboxylic acids, in particular those having from lO to 30 carbon atoms, e.g. silver salts o~ behenic acid or palmitic or stearic acid. Such silver salt emulsions may also contain silver halides which are added directly to the light insensitive silver salt emulsion or produced in situ on the grain surface of the light insensitive silver salts by addition of halides. Such emulsions include the so-called heat developable silver salt emulsions which are sensitive to light and to W or IR radiation.
The silver halide emul~ions used may be the usual silver chloride, silver bromide, silver chlorobromide or silver iodobromochloride emulsion30 The process according to the invention i~ particularly suitable for stabilizing or spectrally se~sitizing photo-graphic emulsions whioh have a high silver content.
By photographic emulsion~h~ving a high silver content :i are generally meant emulsions in which the proportion by weight o~ gelatine to silver ex~ressed as silver nitrate is less than about l. Emulsions of this kind have beoome knowrl ~or use as ~ilm emulsion~ ~or photogr~phic recording materials.
As ~ result oi attempts to improve the sensitivity and sharpness o~ photographic reoording materialB~ the silver halide packing den~it~ in mode~n photographic emulsions is constantly being increased with a eorresponding reduction in the proportion of binder~ ~hese emulsions frequently have a ratio o~ gelatine to ~llver o~ less than 0.7 to 0.2, ' ' '57~
in extreme cases as little as 0~10 For colour photographic purpo-ses emulsified Golour couplers may be added to these emulsionsO
In such emulsions or casting melts, the resistance to digestion is extremely important and undesirably high quan-tities of re~i-dual solvent as we.l as substantial quantities of wetting agents which cause excessive reduction in the surface tension may make it impossible to obtain a uniform casting and hence to produce high quality materials~
The apparatus and procedure required for the drying :~ 1o processes such as spray drying or ~reeze drying used in :~ the pre~erred embodiment of the invention are well ~nown in the art ~nd need not be described in detail hereO
~eference may be had, ~or e~ample, to the handbook by ~- Ullmann, Enzyklop~die der ~echnischen Chemie, 4th Edition, . pages 712 et seq and 716 et seq and "Das Trocknen" in the series "Grundlagen der chemischen Technik~ by Dr. Ing.
Friedrich Kneule, 3rd Edition, 1975, in whioh methods o$
freeze drying are described on page 472 et seq and of atomization drying on pages 40l et seq.
: I~ the spray dr~ing proce s, drying itsel~, may, i~
.: :
desired, be carried ou~ in an inert ga~ atmosphere~ Fo~
freeze drying, it is particularly advantageous fir~t to carry ~: out a;prooess of shook ~reezing, e.g. using liquid nitrogen, ~ollowed by the u~ual sublimation at elevated temperatures which must, however, be below the melting po~nt o~ the dispersion.
,,, :
.: .
,: , ' The proce~s according to the invention is particularly advantageous for the introduction of photographic additives which contain water-solubilizing groups such as sulpho groups but which are not ~u~ficiently water-soluble to : 5 allow them to be introduced as aqueous solutions into photographic emulsions. When such photographic additives are first emulsified in an aqueous gelatine solution by the process described in German Patent Specifications NoO 1,547,705 and 1,964,169, the photographic additives are liable to be adsorbed so iirmly on gelatine as a result of van der Waals interaction that~ when the aqueous gelatine dispersion is subsequen$1y introduced into the : photographic silver salt emulsion, the capacity of the photographic additive to inYluence the sensitomatric propertie~ o~ the silver salt are progressively reduced.
If 3uch additive~ are con~erted into a particulate ~orm by one o~ the abo~e mentioned drying methods in the process according to the invention, thay can be stored :: indefinitely without sufiering any loss of their capacity ; 20 to in~luence silver 3alts in photographic emul~qions.
~he inventlon will now be described in more detail w1th the aid o~ example~.
- ~k~
~ 3 g oi ~ensitizer VIII were stirred up wlth 7 g oi ; 25 the ~odiwm ~alt o~ di-(sulphonaphthyi)-methane with the addition o~ ~ small quantity o~ water (about 50 ml~ and the slurry obtalned wa~ then milled wi$h 200 g o~ quartz -~ A-G 1413 - 23 -. .
sand having an average particl0 diameter of a~out 1 mm in a sand mill, e.g. as illustrated in Figure 1, for 2 hour~.
The sensitizer compound used had an average particle size before milling of about o.6 mm. A~ter milling, it had an average particle size of 0.5 ~m (if the sen~itizer has a particle size of more than o.6 mm before millin~, it must first be reduced to a particle size of less than or equal to 0.6 mm in an ordinary mill before it iB milled in a sand mill as described above). The proportion of the particle size of the substance which is required to be milled and the diameter of the milling elements should alway~ be optimisedO A use~ul rule of thumb is that the be~t results are always obtained when the average particle diameter of the substance to be milled is less than or equal to 2/3 of the average particle diameter o~ the milling elements.
The aqueo~s dispersion obtained as described above was shock frozen wi$h liquid nitrogen after removal of the milling eleme~ts and then stored in the dry state after subli~ation.
A sample containing 260 mg o~ ~ensitizer was added i~mediately, and other sampleæ at interval~ o~ 4 week~, ~ to 1000 g oi a silver halide emulsio~ ~hich had been ; prepared as described below.
Tv 1000 g of a silver iodobromide emulsion havi~g a 6ilver halide content o~ 0~55 mol per kg were added 100 ml o~ a 1~ ~queoue solution of 4~hydroxy-6-methyl-1,3,3a,7-, .
.~ .
: :. , ,. ,- . '-. :. : . . ' , .: .
,: , ~ ' f~S~
tetraazaindene, 20 ml o~ a l~ aqueous pyrocatechol solution and 50 ml of a 5~ sodium salt solu~ion of pentadecylene succinic acid diglycolide. 42 g of cyan colour coupler of the ~ormula OH
~ CONH~2)40- ~3t~C4Hg ` ~
were added to the ~ilver halide emulsion in the ~orm of a coupler dispersion prepared by emulsifying the colour coup er together with 21 g of dibutylphthalate and ~.2 g of dodecyl benzene sulphonic acid sodium in 400 ml of a 2.5~ gelatine solution.
The photographic emulsions obtained were sensitometric-ally assessed in the usual manner after they had been cast on a transparent cellulose triacetate substrate.
Sensitometric assessment showed that the individual photographic materials prepared ~rom the individual s~mples were completely identical in their sensiti~ity, gradation and ma~imum density o~er a period of half a year.
The sensitizi~g ef~ect o~ the sensitiz0r was not reduc2d by storage in tha dry state.
A photographic material whlch had been prepared as described above e~cept that the sensitizer dispersion was - immediately added to the silver halide emulsio~ ~fter ~ ~ milling ln the sand mill wa~ also sen~itometrioally assessed ' ~ A-G 1413 - 25 -,, ,. ~ - , , . , :
for comparison.
This assessment of the sensitometric results showed tha-t the photographic emulsion which had been sensitized with freshly prepared sensitizer dispersion provided the same results with regard to sensitivity, gradation a~d maximum density as emulsions which had been s~ntized with freeze dried sensitizer.
The comparison shows that the sffect ~f the spectral sen~itizer has in no way been deleteriously affected by the freeze drying treatment.
E ~MPLE 2 80 g of sensiti~er or stabilizer were mixed with 250 g o~ glass beads obtainable under the name o~ reflex beads (Dragonwerke, Bayreuth) ha~ing a diameter o~ from 0.85mm to 0.95mm and the mixture, together with lO0 ml of water and 3 ml of a 40% aqueous solution o~ a polymeric alkyl naphthalene sulphonate, was milled for 3 hours in a laboratory sand mill illustrated in Figure 1, which was operated at a speed of 7000 rev~/min. The temperature inside the mill iB kep-t below 40C by adjusting the rate of supply of cooling water. The ~hole contents of the mill were then ~iltered through a glass ~rit having a pore diame$er o~ from 40~to 90 ~ into a gla~s filter pot containing 5 l o~ a 10% gelatine ~olution which had been :;~ 25 heated to 40C~ When the filter had been thoroughly washed, a ~urther 5 l of li~uid 10 % gelatine solution were added to the ~1ltrate~ The volume was then made up to :~ 20 l with waterO
.; .
.:., ' - ' ' - ` ' ', ,' -', ' . ' ~57~
The resulting filtrate was again briefly heated to 40C and stored at 4C to solidify. The dispersion, which solidi~ied in the form of a gel, could be immediately added to the silver halide emulsion for sensitization or stabilization purposes or it may first bs stored for any length of time.
Sensitizer dispersions prepared as described above contain, in the disperse ~orm, one of the above mentioned sensitizers I to X while the stabilizer dispersions contain one of the above mentioned stabilizers XI or XII. The sensitizer or stabilizer dispersions are then added to the silver halide emulsions as desoribed below.
l kg of a silver iodobromide emulsion containing l mol of silver halide per kg was spectrally sensitized with one of the sensitizer dispersions described above, containing 260 mg of sensitizer IV, and a colour coupler dispersion obtained by emulsifying 30 g of the colour coupler described in Example 1~ 12 g of colour coupler of the formula .
OH
': Cl~0~2~
z o ~ ~l 4H29 .
21 g of dibutyl phthalate and 4.2 g of dodecylbenzene sulphonic acid ~odium in 300 ml of an aqueous gelatine ~olution containing lO g o~ gelatine/were then added.
Emulsion A9~ w~ich was now ready ior oasting, was transferred , -to a circulatory system tempered at 40C and driven by a Centrichem rotary pump of EC0-Pump-Corporation.
For comparison, a similar colour coupler containing silver halide emulsion B was prepared except that the sensi-tizer was added to the silver halide emulsion in the form o~
a 0005 ~ solution in dimethylformamide instead of by the method according to the inventionO
Small portions were removed from both samples at intervals of 4 hours and examined microscopically~
Another small portion was applied to a transparent cellulose triacetate substrate and, after hardening with a water-soluble carbodiimide and the usual photographic processing (colour development with colour developer N-ethyl-N-~-oxyethyl~3~methyl-p-phenylenediamine at 38C
for 3~4 minutes) 7 it was examined to determine the gradation and sur~ace glossO
; Both in the miorosoopio investigation a~d in the ex~mination for sur~ace gloss, the photogr~phic emulsion containing colour coupler was examined to determine the resistance of the colour ooupler to cry~tallisation. .
Crystalli~ed ¢olour ¢oupler compounds can either be seen microscopically or detected by the resulting clouding or . ~ , matting o~ the s~rfaoe of the resulting photogra~hic materi al O
~he ~ollowing results were obtained:
: ;
: A-G 1413 - 28 -:~
Sample Digestion Gradation Surface Crystallisation time gloss (hours) y 1 ~ 2 .. . . ..
~ 0 0.68 1.04 glossy no crystal~
B 0 o.65 1.05 glossy no crystals ; A 8 o~65 1007- glossy no crysta~
B 8 0058 0.98 slight isolated crys$al matting plates A 24 0.70 1.10 glossy no crysta~
B 24 0.48 0.75 very mainly ootagonal severe crystal plates matting due to crystall-isation The experimant shows that the presence o~ dimethyl-formamide in the casting solution reduces very considerably the resistance to digestion so that crystallisation phenomena can be observed after a diges~ontime o~ only 8 hours.
A comparison of the photographic materials shows that i~
the comparison casting solution has been digested for 8 hours, its use ~or photographic materials is difficult since the photographi¢ properties, expr~ssed by the gradation values and Y2 and by the surface gloss of the photographic : material, are oonsiderably impairedO The comparlson also shows that photographic castlng solutio~ prepared in accord~nce with the invention have e~cellent resistance to digestion and produoe exoelle~t photographic materials in which the~properties are in no way deleter~ously ~: af~eoted by prolonged storage o~ the casting solutionO
A-G 1413 ~ 29 -,:
.
~5~
EXA~LE 3 A) 1 kg of a silver iodobromide emulsion containing 1 mol of silver halide was spectrally sensitized by means of a sensitizer dispersion which had been prepared as described in Example 2 and contained 130 mg of sensitizer I. To this sensitized emulsion were then added 150 ml of a 1~ aqueous solution of 4-hydroxy-6-methyl~ ,3a,7-tetraazaindene, 2 ml o~ a 50% aqueous glycerine solution and 35 g of magenta coupler of the formula ~ 10 ~1 C ~ Cl . t~H11 2 ~ -C5H11 together with ~5 g of tricresylphosphate and 3.5 g o~
.' sodium dodecylbenzene sulphonate emulsified in 250 ml of 3.5 % aqueous gelatine solutionO 60 ml o~ a 4~ solution . of a wetting agent of the formula ` C4H9cH(~2H5)cH2oooc~lgcH(so3Na)cooN~Iso~cl5H3l~
: 20 5 ml of a N-sodium hydro~ide solution, 5 ml of a 5~ solution Qf basic chrom~um acetate and 30 ml of a 1% pyrocatechol ; ~ solution were then added.
B) ~he procedure 1~ the same a~ that described ~or ~B sample A3 except that a gensitizer dispersion prepared as described i~ E~ample 2 a~d containi~g 130 mg o~ ~ensitizer - II was also added.
... .
C) I'he procedure is the same a~ that described for sample A-G 1413 _ 30 _ ~5~
B) except that, in addition, a stabilizer disper~ion prepared according to Example 2 and containing 65 mg of stabilizer compound XI was added.
For comparison, comparison compositions D) to F) were prepared by the method described for samples A) to C) except that instead of using sensitizer dispersions or stabilizer dispersion, sensitizer I was added to the silver iodobromide emulsion in the form of a 0.1~ methanolic solution, sensitizer II was added in the form of a 0.05 methanolic solution and the stabilizer in the form of a 0.05~ me-thanolic solutionO In Figure 2, tAe resulting viscosity values ~ o~ the individual casting 30lutions ~ o~ samples D) to F) are plotted against the quantity : of methanol added, It can be seen tha$ even a small addition of methanol to the ca~tingsolution cau3es severe changes in viscosity. In contrast to the comparison samples, samples A)y B) and C) are virtually independent in their viscosity on the nature and quantity of sensitizer or stabilizer added, and their VisCoBitieS are 39.5, 39 and 38.5. Moreo~er, the viSCOS1ty o~ emulsion~ prepared : : aocording to th~ invention is appro~imately the ~ame a~
that oi a~ emul~ian which has been prepared in a similar : manner but using pure ge~atine solution instead of the sensitizer dispersion, In comparison solution~ E) and F), : 25 $he vi8cosity 18 already so much reduoed that casting on a film sub~trate does not result in the formation of a photographio layer ¢ontaining a su~fioient quantity of ~-~ 1413 - 31 -silver halide. Due to sedimentation phenomenaJ low : viscosity casting solu-tions become depleted o~ silver halide in the casting apparatus at the point where the film substrate dips into the solution ~o that, with low viscosity casting solutions, i-t is not possible to obtain layers containing more than a small quantity o~ silver halide.
EXAMPLE_4 100 ml of a 1~ aqueous solution of 4-hydroxy-6-methyl-10 1,3,3a,7-tetraazaindene, 20 ml of a 1~ aqueou~ pyrocatechol solution and 50 ml of a 5~ solution o~ the sodium salt of pentadecylene succinic aoid diglycolide were added to 1000 g of a silver iodobromide emulsion containing 0.55 mol of silver halide per ~g. As colour coupler were used ~2 g of the colour coupler described in Example 1 in emulsi~ied form together with 21 g of dibutyl phthalate and 201 g of dodecylbenzeneslllphonic acid sodium in k20 ml of ~ ~ gelatine, The emulsion was sensitized by the method described in Example 3. Comparison sample H was sensitized wi-th 190 mg of sensitizer dye III in the ~orm of a 0005~ solution in a mixture of methanol a~d dimethylformamide (volumetric ratio 1:1) while s~mple G according to the inYentiOn was sensitized with a ~ensitizer dispersion according to E~ample 2 containing 190 mg of sensitizer III. The 9ample9 prepared in this way ~ere ~tored at 40C. Thi~ storage at 40~C
is in practice a necessary part of prepara$ion for casting.
When the solu-tions ready for oasting were ~torod at 40C, .
S7~i~
the comparison composition H showed signs of considerable sedimentation of the dispersed silver halide grainsO By contrast, sample G according to the invention was seen to be much less susceptible to sedimentation.
The si.lver halide emulsion used in Example 4 was an emulsion containing silver halide grains in which the most frequently occurring grain diameter was about 0.55 ~m.
The percentage proportion of silver halide grains containing the most frequent grain diameter was about 15~.
Curve 1 of Figure ~ represents the frequency of individual grains plotted against their grain diameter in percent.
Ex~mple 4 was repeated e~cept that the silver iodo-bromide emulsion used was replaced by a~ emulsion which wa~
similar except that the silver halide grains having the most frequently occurring grain diameter of o.6 ~m wa~ present only to an extent of about 8 % while a larger proportion of the silver halide grains than in the compariso~ emulsion of Example 4 had a grain diameter of 1 pm and 2 ~m and the : proportion of coarse grained silver halide grains was : oonsiderably higher than in Example 4. A comparison o~
: the ~requency distribution o~ two emul-sio~s can be seen in ~; Figure 39 in whioh curve 2 represe~ts th0 ~requenoy distribution of silver halide grains in the emulsion used in Exa,mple 5 whlle ourve 1, as already me~tioned above, repre~ents the frequenoy distribution in the emulsion of Example 1413 33 ~
, .
' ,, ,, :
57~L
Figure 4 shows the results obtained from ~edimentatio~
measurements9 Along the ordinate are plotted the height in the storage tank (filling height 40 cm) ~rom which the individual samples for measurement were removed and along the abscissa are entered the silver content found at these different height~, measured as g of silver nitrate per kg of emulsionO The mea~urements represe~ted in Figure 4 were carried out after the emulsion had been left to stand for 6 hours. Curves G and ~I represent the values obtained with emulsions o~ Example 4 and curve~ G' and H~ the ~alues obtained with emulsions of Example 5. Curves G and G~ ~re obtained from samples according to the invention and curves H and H~ from comparison sample~.
The comparison shows that photographic emulsions prepared according to ~he invention have much less tendency ; to sedimentation phenomena than compari~on emulsions9 the results depending on whether the silver halide emulsions used are comparatively homodisperse or heterodisperse.
EX~MPLE 6 This example shows that compared with proces3es known in the art, the sen~itization process according to the invention i~ capable of producin~ photographic materials ~`~ with improved sensitivity.
To 1 kg of an iodobrQmide emulsion (silver content 0.3 mol per kg) oontaining 4-hydroxy-6-methyl-1,3,3a-7-tetraazaindene, a pyrocatechol solution and a sodium salt solution oi pentadeoylenesuccinic aoid dîglycolide were ; ' ' ' ' .
7~
added 24 g of coupler of the formula Cl O
Cl ~ ~ ~COC13H27 Cl Cl in an emulsi~ied ~orm with 6 g of dibutyl phthalate and ~ 180 g o~ a 2.5~ aqueous gelatine solution.
: Sensitization was carried out by the process described in Example 2. Sample I according to the inve~tion was sensitized with a sensiti~er dispersion according to Example 2 containing 45 mg of sensitizer I while comparison sample K was sensitized with 45 mg of sensitizer I dissolved to ~orm a 1:1000 solution in methyl alcohol.
Each o~ the resulting emulsions was hardened with 2 ml of a 5% triaorylo~ormal solution and cast on a transparent cellulose triacetate substrate, ' - Af-ter exposure and development oi the photographic : ~ ~ 20 materials~, U31~g N-butyl-N- 6-sulpho~utyl-p-phenylene ;diamine as developer sub~tanoe at room temperature, oompari-. : son shows that the ~ample acoording to the in~ention i9 more sensitive by 1.5 DIN than the comparison ~ample to ,~
~ : which the sensiti2ing dye had been added in methanolic : ~ 25 solution.
.
Other ~amples according to the-invention L and N
a~d comparison samples M and O were prepared in a similar : ~ h-G 1413 - 35 -~ .
' , ~
, . .. . . . . .
manner except that, for comparison with sample I and with comparison sample K, instead of using 45 mg of sen~itizer - II, only 20 mg were used in samples L and M and 10 mg in samples N and 0, When the sensitometric results are assessed, it is surprisingly found that even when smaller quantities of sensitizer are used in the materials according to the invention, these materials ~till show a sensitivity gain of from 1 to 105 DIN compared with comprison samples K, M and 0.
~Z .
~nother comparison example shows th0 advantage obtained with the process according to the invention when freeze dried sensitizer dispersions are used, in comparison ~: 15 with processe~ known in the art~
120 ml o~ a 1~ aqueous solution of 4-hydroxy-6-methyl-1,393a,7-tetraazaindene and 1 ml of glycerol were added to 1 kg of an iodobromide emul~ion (0.7 mol of sil~er per kg). The colour coupler used consisted of 42 g o~ the ~ 20 colour coupler degcribed in Example 6 added in emulsified j form in 12 g o~ dibutyl phthalate in 180 g o~ a 2.5 gelatine SOlUtiDn.
The amulsion was sansitized with 110 mg of sensitizer II which had been pretreated as ~ollows:
10 g of son~itizer II were milled as desoribed in Example 1 with 23.3 g o~ a oondensation product o~ naphthalene with formaldehyde and sulphurio acid ~aYerage molecular : wei~ht 420) as sodium ~alt, 100 g of sand a~d 100 ml of water.
A-a 1413 - 36 ;
The sand was then filtered off and the filtrate shock ~rozen with liquid nitrogen while the water was removed by sublimation under vacuum at a temperature below the melting point of the crystallised aqueous phase. l g of the resulting produc-t was taken up in 75 ml of water and from it, the quantity corresponding to llO mg of sensitizer was added to the emulsion previously described.
Working up the emul~ion, preparation of the photo-graphic material, exposure and processing were carried out as desc~ibed in Example 6.
A comparison material Q was prepared in a similar manner. In contrast to material P prepared according to the invention, it was sensitized with llO mg of sensitizer ~ which had been emulsified a~ described below before it was - added to the emulsion:
l g of sensitizer II was dissolved in a mixture of 50 ml of m-oresol and 25 ml of methyl alcohol and to this solution was added a solution of 3.33 g of a 50~ aqueous sodium dodecylbenzene sulphonate paste in 17 ml of ethyl acetate.
The oombined solutions were then emulsiXied i~ 350 ml of a 6~ gelatine solution with vigorou~ ~tirring ~nd $he volume of the emulsion was then made up $o lO0 ml wnth water. A qu~nt1ty of this sensit1zer emulsion w~ich corresponded to llO ~g of se~æitizer was added to l kg o~
the above desor1bed silver halide emulsion.
~he compari~on shows that the sensitivity of material ~-C 1413 _ 37 _ ,~ ~
i7~
P prepared according to the invention is higher by one ~IN than that of the comparison material Q.
1 kg of a silver iodobromide emulsion containing 1 mol of silver halide per kg and provided in the form o~
a mixture of a conventional silver iodobromide emulsion Wit}l a convert emulsion in proportions of 8:2 was màde ready for casting, using the cyan coupler a~d additives indicated in Example 2.
The emulsion was sensitized with 130 mg o~ sensitizer V and 130 mg of sensitizer III. In sample R according to the invention, the sensitizer mixture was dispersed in a dilute gelatine solution by the method described in Example 2 whereas in comparison s~mple S the sensitizer mixture was added as a 0.05% solution of sen3itizer V in dimethylformamide and as a 001% solution o~ sensitizer III
in methyl alcohol.
When the resulting emulsions had been cast and hardened with a water-soluble carbodiimide9 the photographic m~terials obtained were exposed and then developed in the usual manner, using N-ethyl-N-~-o~yethyl-3-methyl-p-phenylene diamine as developer sub~tanceO Sensitometric assessment shows that, in comparison wqth s~mple S o~ the known art7 Sample R a¢cording ~o the invention has gained in sensi-tivity by two DIN and its colour ~og is reduced by o . o6 colour densit~ units~
A-G 1413 - ~8 -.
Masehinen~abriken, Basel, 10 4. Masap mills manufactured by Masap AG Matzendorf Schweiz Processes and suitable mills have also been described in US Patent Specifications No. 2,581,414 and 2,855,156.
An example of a sand mill suitable for use on a laboratory scale is show~ in Figure 1.
The container B for the milling process may be made of glass or steel, Steel eontalners used ~or *he proeess according to the invention are pre~erably made of hardened ~: steel to pre~ent exeessi~e abrasion whieh would cause , 20 considerable contamination o~ the dispersion and hence of ;~ ~ the~photographic emulsion and ~ay have a deleterious e~feet ,~ on the photographie properties of the emul~ion.
~he mill container B i~s enolosed in a eooling iacket ~: of PV~ or metal K and may be oooled during the milling :: :
:~ 25 proeess br a eoollng liquid F~ Running water used as eoolant i s generally su~ieie~t to effeet praetieally eomplete removal o~ the heat produoed by milllng and to ensure that A-G ~413 - 12 -:: .
:, , :
'7~L
the temperature of the material being milled does not rise above 40C o The dimensions of the container are: Wall thickness 4mm, internal wqdth 75 mm, height 230mm. A
stirrer shaft R having a diameter of 15 mm and carrying four Duramid or Durethan discs 5 mm in thickness and 60 mm in diameter extends into the containerO The four di~cs are arranged at intervals of 20 mm.
The shaft is rotated at the rate of lO~ revs/min~
by a drive motor Mo 'rhe motor may be arranged cen$rally or laterally to the drive shaft and may drive the shaft via a cone beltO
The container is filled to about one third of its height and from about 5 to 80 g o~ substance are milled in each cycle. This re~uires the addition of a$ least about 3 to 4 times this quantity of milling elementsO
rrhe average partiole diameter o~ the milling elements used depends on the particle diameter o$ the substance before it is milled. Optimum results ars obtained i~ the average particle diameter of the substance to be milled i9 le9s than or equaI to two-thirds of $he particle diameter of the milling elements. I~ the substanoe to be ~ilied : has a greater partiole di~meter~ it is advisable *irst to size reduoe it by one o~ the usual methods.
~; The quantity of water required $or milling may vary from 20 ml to 200 ml dependi~g on the subst~nce to be milled and the dispersing age~t, and the quantity o~
dispersing agent u~ed may also vary within wide limits, as already men-tioned above.
A-G 141~ ~ 13 -7~
A milling cycle is generally as follows:
~0 g of substance to be milled are mixed with 200 g of glass beads7 e~g. reflex beads of Dragonwerk ~eorg Wild, ]3eyreuth, having a diameter of from 0.85 mm to 0095 mm, depending on the particle si~e of the sub~tance to be milled, and the substance is then milled together with lO0 ml of water and 15 ml of a 40~ dispersing agent, using the laboratory sand mill described in Figure 1 (3 hours at a rate of stirring of 7000revs/min. The temperature inside the mill is kept below 40G by adjusting the rate of flow of cooling water The ~hole contents of tha mill are then filtered into a glass filter pot through a glass fri$
- (pore size 40 to 90 ~m)0 According to one particular embodiment, the glass filter pot contains 2.5 l of a lO~ gelatine solution ~hich has been heated to 40C. A ~urther 2.5 l o~ a lO~
gelatine solution are subsequently added to the ~iltrate ~nd the ~olume of the resulting dispersion i6 made up to lO 1 with water.
The filtrate obtained in this way is again briefly heated to 40C an~ then stored at ~C to solidl~y~
The dispersion~ which ~olidi~ies in a gel form~ may now be added to the photographic ~ilver halide emulsion either immediately or a~-tsr ~urther storage~
Instead of u~ing the glas~q beads desoribed above as milling element~, it i~q al~o po~sible to u~e quartz ~md or ~ilico~ carbide sand.
According to the preferred embodiment, the ~iltrate obtained as described above is immediately subjected either to freeze drying or to spray drying, as will be described in ~etail below.
The photographic additive used in the process according to the invention is dispersed in the aqueous phase in ; the presence of dispersing agents without being dissolved.
Any photographic sp0ctrally sensitizing dye may be subjected to the process according to the invention. Particularly suitable are those dyes which are practically insoluble in aqueous solutions, e.gO dyes which have a solubility in water o~ less than about 0.1% at 20C. Dyes suitable for carrying out the process of the in~ention have already been disclosed .in n~erous patent specifications, for example some have been described in German Patent Specification NoO 1,964,169.
The following Table A shows a ~umber o~ spectrally sensitizing dyes which have bee~ used in the ex~mples described hereinafterO
.
Table A
, .
Dye-stuff No~ ~or~l 2H5 C2~5 ~N 'N ~ ;E~s~
NC~ J~ C~
(~2~4~ 0~C~3 Table A (Continuation) II
C6H5 ~C2H5 ~C6H5 (~H2)4S03N~ 2)45 3 CH ~ C2H5~ ~ CH~
III ~ ~ CH ~ H - ~ CH3 C ~ 5 (CX233so ~
:, ~ CH3~ ~ C2~ ~
V ~- CH C -~
~2)3SO3 -:: " ~H :
V 3 ~=CN-C~CN~
1H2CH2COO~
' V~ ' ~ C2H5 ~"Cl 2 H5(Cll233So~9 .. . .. .. .
';- - , ~, ', .
i7$~
:
`~ Table A (Continuation) V~
C2~5 (CH2)3 , : :; Dye-stuff-No. Formula VIII ~ ~J=CH-C=C--S S--1 1 J
C N J~NJ;CI;-C ~
; ,~;
., ~
; IX ~ N C2H5 : CzH5 ~
, ~: ~ : :
x c~L ~1 2H5 (C H2 ) 3$0~3 ;:
: : A-G 1413 - 17 ~
,:
:' ' :
~; :
:
The dye dispersions used in the process according to the invention may also contain binders, for example, gelatine. The proportion of dye to gelatine may vary ~ithin a wide range but, for spectral sensitization, the best results are obtained with dispersions in which the ~ye content is between 5 and 20~, based on the total ~eigh-t of dye and binderO The dye dispersions used for spectral sensitiza$ion of photographic ~ilver halide emulsions in the process according to the invention may also contain two or more dyes in each dispersion, or dispersions containing only one dye may be used in combination with two or more ; such dispersions. For achieving optimum sensitivity by the process according to the invention, the optimum concentration of dye incorporated in the emulsions may generally vary between about 0~2 and 4 g of dye per mol of silver halide in the emulsion, depe~ding on the particular dye and emulsion used. Fi~e grained emulsions generally require a large quantity of sensiti~ing dyes than coarse grained emulsions.
Any photographic stabilizers m~ be used in the process according to bhe invention. Particularly suitable again are those w~ioh are pr~ctically insoluble in aqueous ~ solution~ e.g. stabilizers havi~g a ~olubility of less - than about Ool~ in wate~ at 20C.
Examples of suoh stabilizers are known and have been described in numerous publioations,eOg, in ~S Patent Speci~ication No. 3,692,527 7~;~
The following Table B shows stabili~ers used in the examples described hereinafterO
Table B
Stabilizer No.. Formel XI ~ N~ H
~ C~
XI~ CH ~ SH
.'~ .
~' , :;
~, : AG 1413 - 19 ~
, . .
~5 ~
The stabilizer dispersions used in the process according to the invention may also contain polymeric binders such as gelatine. The ratio of stabilizer to gelatine may vary over a wide range but, for stabilization, it has also generally been found suitable to use disper~ions having a stabilizer content o~ from abou-t 5 to 20~, based on the total weight of stabilizer and binderl For achieving sufficient stabilization by the process according to the inven-tion, the concentration of stabilizer incorporated in -the silver salt emulsions may be varied from 20 mg to 2 g of stabilizer per mol of silver salt, depending on the nature of the stabilizer and of the emulsion u~qed.
~he process according to the inven$ion is particularly suitable for the spectral sensitization or stabilization of any photographic silver salt emulsio~sO The light-sensitive silver halide may be dispersed in any hydrophilic colloids (binders~ suitable for dispersing silver halides, e.g~
gelatine; albumen; alginic aoid; polyvinyl aloohol; polyvinyl ; pyrrolidone; cellulose ethers or partially hydrolysed cellulose acetate. The hydrophilic oolloid may also contain dispersed vinyl polymers or water-insoluhle polymers of alkyl acrylates and methacrylates~ aorylic aoid~ sulpho-~- alkylacrylates or methacrylate~0 Suitable photographic silver salt emul~ions include light-sensitive silver halide emul~ions or silver salt emulsions i~ whioh the silver salt consists partly or comp1etely of light insensitive silver salts of long chain A-G 1413 - 20 ~
.
.. . . .
aliphatic carboxylic acids, in particular those having from lO to 30 carbon atoms, e.g. silver salts o~ behenic acid or palmitic or stearic acid. Such silver salt emulsions may also contain silver halides which are added directly to the light insensitive silver salt emulsion or produced in situ on the grain surface of the light insensitive silver salts by addition of halides. Such emulsions include the so-called heat developable silver salt emulsions which are sensitive to light and to W or IR radiation.
The silver halide emul~ions used may be the usual silver chloride, silver bromide, silver chlorobromide or silver iodobromochloride emulsion30 The process according to the invention i~ particularly suitable for stabilizing or spectrally se~sitizing photo-graphic emulsions whioh have a high silver content.
By photographic emulsion~h~ving a high silver content :i are generally meant emulsions in which the proportion by weight o~ gelatine to silver ex~ressed as silver nitrate is less than about l. Emulsions of this kind have beoome knowrl ~or use as ~ilm emulsion~ ~or photogr~phic recording materials.
As ~ result oi attempts to improve the sensitivity and sharpness o~ photographic reoording materialB~ the silver halide packing den~it~ in mode~n photographic emulsions is constantly being increased with a eorresponding reduction in the proportion of binder~ ~hese emulsions frequently have a ratio o~ gelatine to ~llver o~ less than 0.7 to 0.2, ' ' '57~
in extreme cases as little as 0~10 For colour photographic purpo-ses emulsified Golour couplers may be added to these emulsionsO
In such emulsions or casting melts, the resistance to digestion is extremely important and undesirably high quan-tities of re~i-dual solvent as we.l as substantial quantities of wetting agents which cause excessive reduction in the surface tension may make it impossible to obtain a uniform casting and hence to produce high quality materials~
The apparatus and procedure required for the drying :~ 1o processes such as spray drying or ~reeze drying used in :~ the pre~erred embodiment of the invention are well ~nown in the art ~nd need not be described in detail hereO
~eference may be had, ~or e~ample, to the handbook by ~- Ullmann, Enzyklop~die der ~echnischen Chemie, 4th Edition, . pages 712 et seq and 716 et seq and "Das Trocknen" in the series "Grundlagen der chemischen Technik~ by Dr. Ing.
Friedrich Kneule, 3rd Edition, 1975, in whioh methods o$
freeze drying are described on page 472 et seq and of atomization drying on pages 40l et seq.
: I~ the spray dr~ing proce s, drying itsel~, may, i~
.: :
desired, be carried ou~ in an inert ga~ atmosphere~ Fo~
freeze drying, it is particularly advantageous fir~t to carry ~: out a;prooess of shook ~reezing, e.g. using liquid nitrogen, ~ollowed by the u~ual sublimation at elevated temperatures which must, however, be below the melting po~nt o~ the dispersion.
,,, :
.: .
,: , ' The proce~s according to the invention is particularly advantageous for the introduction of photographic additives which contain water-solubilizing groups such as sulpho groups but which are not ~u~ficiently water-soluble to : 5 allow them to be introduced as aqueous solutions into photographic emulsions. When such photographic additives are first emulsified in an aqueous gelatine solution by the process described in German Patent Specifications NoO 1,547,705 and 1,964,169, the photographic additives are liable to be adsorbed so iirmly on gelatine as a result of van der Waals interaction that~ when the aqueous gelatine dispersion is subsequen$1y introduced into the : photographic silver salt emulsion, the capacity of the photographic additive to inYluence the sensitomatric propertie~ o~ the silver salt are progressively reduced.
If 3uch additive~ are con~erted into a particulate ~orm by one o~ the abo~e mentioned drying methods in the process according to the invention, thay can be stored :: indefinitely without sufiering any loss of their capacity ; 20 to in~luence silver 3alts in photographic emul~qions.
~he inventlon will now be described in more detail w1th the aid o~ example~.
- ~k~
~ 3 g oi ~ensitizer VIII were stirred up wlth 7 g oi ; 25 the ~odiwm ~alt o~ di-(sulphonaphthyi)-methane with the addition o~ ~ small quantity o~ water (about 50 ml~ and the slurry obtalned wa~ then milled wi$h 200 g o~ quartz -~ A-G 1413 - 23 -. .
sand having an average particl0 diameter of a~out 1 mm in a sand mill, e.g. as illustrated in Figure 1, for 2 hour~.
The sensitizer compound used had an average particle size before milling of about o.6 mm. A~ter milling, it had an average particle size of 0.5 ~m (if the sen~itizer has a particle size of more than o.6 mm before millin~, it must first be reduced to a particle size of less than or equal to 0.6 mm in an ordinary mill before it iB milled in a sand mill as described above). The proportion of the particle size of the substance which is required to be milled and the diameter of the milling elements should alway~ be optimisedO A use~ul rule of thumb is that the be~t results are always obtained when the average particle diameter of the substance to be milled is less than or equal to 2/3 of the average particle diameter o~ the milling elements.
The aqueo~s dispersion obtained as described above was shock frozen wi$h liquid nitrogen after removal of the milling eleme~ts and then stored in the dry state after subli~ation.
A sample containing 260 mg o~ ~ensitizer was added i~mediately, and other sampleæ at interval~ o~ 4 week~, ~ to 1000 g oi a silver halide emulsio~ ~hich had been ; prepared as described below.
Tv 1000 g of a silver iodobromide emulsion havi~g a 6ilver halide content o~ 0~55 mol per kg were added 100 ml o~ a 1~ ~queoue solution of 4~hydroxy-6-methyl-1,3,3a,7-, .
.~ .
: :. , ,. ,- . '-. :. : . . ' , .: .
,: , ~ ' f~S~
tetraazaindene, 20 ml o~ a l~ aqueous pyrocatechol solution and 50 ml of a 5~ sodium salt solu~ion of pentadecylene succinic acid diglycolide. 42 g of cyan colour coupler of the ~ormula OH
~ CONH~2)40- ~3t~C4Hg ` ~
were added to the ~ilver halide emulsion in the ~orm of a coupler dispersion prepared by emulsifying the colour coup er together with 21 g of dibutylphthalate and ~.2 g of dodecyl benzene sulphonic acid sodium in 400 ml of a 2.5~ gelatine solution.
The photographic emulsions obtained were sensitometric-ally assessed in the usual manner after they had been cast on a transparent cellulose triacetate substrate.
Sensitometric assessment showed that the individual photographic materials prepared ~rom the individual s~mples were completely identical in their sensiti~ity, gradation and ma~imum density o~er a period of half a year.
The sensitizi~g ef~ect o~ the sensitiz0r was not reduc2d by storage in tha dry state.
A photographic material whlch had been prepared as described above e~cept that the sensitizer dispersion was - immediately added to the silver halide emulsio~ ~fter ~ ~ milling ln the sand mill wa~ also sen~itometrioally assessed ' ~ A-G 1413 - 25 -,, ,. ~ - , , . , :
for comparison.
This assessment of the sensitometric results showed tha-t the photographic emulsion which had been sensitized with freshly prepared sensitizer dispersion provided the same results with regard to sensitivity, gradation a~d maximum density as emulsions which had been s~ntized with freeze dried sensitizer.
The comparison shows that the sffect ~f the spectral sen~itizer has in no way been deleteriously affected by the freeze drying treatment.
E ~MPLE 2 80 g of sensiti~er or stabilizer were mixed with 250 g o~ glass beads obtainable under the name o~ reflex beads (Dragonwerke, Bayreuth) ha~ing a diameter o~ from 0.85mm to 0.95mm and the mixture, together with lO0 ml of water and 3 ml of a 40% aqueous solution o~ a polymeric alkyl naphthalene sulphonate, was milled for 3 hours in a laboratory sand mill illustrated in Figure 1, which was operated at a speed of 7000 rev~/min. The temperature inside the mill iB kep-t below 40C by adjusting the rate of supply of cooling water. The ~hole contents of the mill were then ~iltered through a glass ~rit having a pore diame$er o~ from 40~to 90 ~ into a gla~s filter pot containing 5 l o~ a 10% gelatine ~olution which had been :;~ 25 heated to 40C~ When the filter had been thoroughly washed, a ~urther 5 l of li~uid 10 % gelatine solution were added to the ~1ltrate~ The volume was then made up to :~ 20 l with waterO
.; .
.:., ' - ' ' - ` ' ', ,' -', ' . ' ~57~
The resulting filtrate was again briefly heated to 40C and stored at 4C to solidify. The dispersion, which solidi~ied in the form of a gel, could be immediately added to the silver halide emulsion for sensitization or stabilization purposes or it may first bs stored for any length of time.
Sensitizer dispersions prepared as described above contain, in the disperse ~orm, one of the above mentioned sensitizers I to X while the stabilizer dispersions contain one of the above mentioned stabilizers XI or XII. The sensitizer or stabilizer dispersions are then added to the silver halide emulsions as desoribed below.
l kg of a silver iodobromide emulsion containing l mol of silver halide per kg was spectrally sensitized with one of the sensitizer dispersions described above, containing 260 mg of sensitizer IV, and a colour coupler dispersion obtained by emulsifying 30 g of the colour coupler described in Example 1~ 12 g of colour coupler of the formula .
OH
': Cl~0~2~
z o ~ ~l 4H29 .
21 g of dibutyl phthalate and 4.2 g of dodecylbenzene sulphonic acid ~odium in 300 ml of an aqueous gelatine ~olution containing lO g o~ gelatine/were then added.
Emulsion A9~ w~ich was now ready ior oasting, was transferred , -to a circulatory system tempered at 40C and driven by a Centrichem rotary pump of EC0-Pump-Corporation.
For comparison, a similar colour coupler containing silver halide emulsion B was prepared except that the sensi-tizer was added to the silver halide emulsion in the form o~
a 0005 ~ solution in dimethylformamide instead of by the method according to the inventionO
Small portions were removed from both samples at intervals of 4 hours and examined microscopically~
Another small portion was applied to a transparent cellulose triacetate substrate and, after hardening with a water-soluble carbodiimide and the usual photographic processing (colour development with colour developer N-ethyl-N-~-oxyethyl~3~methyl-p-phenylenediamine at 38C
for 3~4 minutes) 7 it was examined to determine the gradation and sur~ace glossO
; Both in the miorosoopio investigation a~d in the ex~mination for sur~ace gloss, the photogr~phic emulsion containing colour coupler was examined to determine the resistance of the colour ooupler to cry~tallisation. .
Crystalli~ed ¢olour ¢oupler compounds can either be seen microscopically or detected by the resulting clouding or . ~ , matting o~ the s~rfaoe of the resulting photogra~hic materi al O
~he ~ollowing results were obtained:
: ;
: A-G 1413 - 28 -:~
Sample Digestion Gradation Surface Crystallisation time gloss (hours) y 1 ~ 2 .. . . ..
~ 0 0.68 1.04 glossy no crystal~
B 0 o.65 1.05 glossy no crystals ; A 8 o~65 1007- glossy no crysta~
B 8 0058 0.98 slight isolated crys$al matting plates A 24 0.70 1.10 glossy no crysta~
B 24 0.48 0.75 very mainly ootagonal severe crystal plates matting due to crystall-isation The experimant shows that the presence o~ dimethyl-formamide in the casting solution reduces very considerably the resistance to digestion so that crystallisation phenomena can be observed after a diges~ontime o~ only 8 hours.
A comparison of the photographic materials shows that i~
the comparison casting solution has been digested for 8 hours, its use ~or photographic materials is difficult since the photographi¢ properties, expr~ssed by the gradation values and Y2 and by the surface gloss of the photographic : material, are oonsiderably impairedO The comparlson also shows that photographic castlng solutio~ prepared in accord~nce with the invention have e~cellent resistance to digestion and produoe exoelle~t photographic materials in which the~properties are in no way deleter~ously ~: af~eoted by prolonged storage o~ the casting solutionO
A-G 1413 ~ 29 -,:
.
~5~
EXA~LE 3 A) 1 kg of a silver iodobromide emulsion containing 1 mol of silver halide was spectrally sensitized by means of a sensitizer dispersion which had been prepared as described in Example 2 and contained 130 mg of sensitizer I. To this sensitized emulsion were then added 150 ml of a 1~ aqueous solution of 4-hydroxy-6-methyl~ ,3a,7-tetraazaindene, 2 ml o~ a 50% aqueous glycerine solution and 35 g of magenta coupler of the formula ~ 10 ~1 C ~ Cl . t~H11 2 ~ -C5H11 together with ~5 g of tricresylphosphate and 3.5 g o~
.' sodium dodecylbenzene sulphonate emulsified in 250 ml of 3.5 % aqueous gelatine solutionO 60 ml o~ a 4~ solution . of a wetting agent of the formula ` C4H9cH(~2H5)cH2oooc~lgcH(so3Na)cooN~Iso~cl5H3l~
: 20 5 ml of a N-sodium hydro~ide solution, 5 ml of a 5~ solution Qf basic chrom~um acetate and 30 ml of a 1% pyrocatechol ; ~ solution were then added.
B) ~he procedure 1~ the same a~ that described ~or ~B sample A3 except that a gensitizer dispersion prepared as described i~ E~ample 2 a~d containi~g 130 mg o~ ~ensitizer - II was also added.
... .
C) I'he procedure is the same a~ that described for sample A-G 1413 _ 30 _ ~5~
B) except that, in addition, a stabilizer disper~ion prepared according to Example 2 and containing 65 mg of stabilizer compound XI was added.
For comparison, comparison compositions D) to F) were prepared by the method described for samples A) to C) except that instead of using sensitizer dispersions or stabilizer dispersion, sensitizer I was added to the silver iodobromide emulsion in the form of a 0.1~ methanolic solution, sensitizer II was added in the form of a 0.05 methanolic solution and the stabilizer in the form of a 0.05~ me-thanolic solutionO In Figure 2, tAe resulting viscosity values ~ o~ the individual casting 30lutions ~ o~ samples D) to F) are plotted against the quantity : of methanol added, It can be seen tha$ even a small addition of methanol to the ca~tingsolution cau3es severe changes in viscosity. In contrast to the comparison samples, samples A)y B) and C) are virtually independent in their viscosity on the nature and quantity of sensitizer or stabilizer added, and their VisCoBitieS are 39.5, 39 and 38.5. Moreo~er, the viSCOS1ty o~ emulsion~ prepared : : aocording to th~ invention is appro~imately the ~ame a~
that oi a~ emul~ian which has been prepared in a similar : manner but using pure ge~atine solution instead of the sensitizer dispersion, In comparison solution~ E) and F), : 25 $he vi8cosity 18 already so much reduoed that casting on a film sub~trate does not result in the formation of a photographio layer ¢ontaining a su~fioient quantity of ~-~ 1413 - 31 -silver halide. Due to sedimentation phenomenaJ low : viscosity casting solu-tions become depleted o~ silver halide in the casting apparatus at the point where the film substrate dips into the solution ~o that, with low viscosity casting solutions, i-t is not possible to obtain layers containing more than a small quantity o~ silver halide.
EXAMPLE_4 100 ml of a 1~ aqueous solution of 4-hydroxy-6-methyl-10 1,3,3a,7-tetraazaindene, 20 ml of a 1~ aqueou~ pyrocatechol solution and 50 ml of a 5~ solution o~ the sodium salt of pentadecylene succinic aoid diglycolide were added to 1000 g of a silver iodobromide emulsion containing 0.55 mol of silver halide per ~g. As colour coupler were used ~2 g of the colour coupler described in Example 1 in emulsi~ied form together with 21 g of dibutyl phthalate and 201 g of dodecylbenzeneslllphonic acid sodium in k20 ml of ~ ~ gelatine, The emulsion was sensitized by the method described in Example 3. Comparison sample H was sensitized wi-th 190 mg of sensitizer dye III in the ~orm of a 0005~ solution in a mixture of methanol a~d dimethylformamide (volumetric ratio 1:1) while s~mple G according to the inYentiOn was sensitized with a ~ensitizer dispersion according to E~ample 2 containing 190 mg of sensitizer III. The 9ample9 prepared in this way ~ere ~tored at 40C. Thi~ storage at 40~C
is in practice a necessary part of prepara$ion for casting.
When the solu-tions ready for oasting were ~torod at 40C, .
S7~i~
the comparison composition H showed signs of considerable sedimentation of the dispersed silver halide grainsO By contrast, sample G according to the invention was seen to be much less susceptible to sedimentation.
The si.lver halide emulsion used in Example 4 was an emulsion containing silver halide grains in which the most frequently occurring grain diameter was about 0.55 ~m.
The percentage proportion of silver halide grains containing the most frequent grain diameter was about 15~.
Curve 1 of Figure ~ represents the frequency of individual grains plotted against their grain diameter in percent.
Ex~mple 4 was repeated e~cept that the silver iodo-bromide emulsion used was replaced by a~ emulsion which wa~
similar except that the silver halide grains having the most frequently occurring grain diameter of o.6 ~m wa~ present only to an extent of about 8 % while a larger proportion of the silver halide grains than in the compariso~ emulsion of Example 4 had a grain diameter of 1 pm and 2 ~m and the : proportion of coarse grained silver halide grains was : oonsiderably higher than in Example 4. A comparison o~
: the ~requency distribution o~ two emul-sio~s can be seen in ~; Figure 39 in whioh curve 2 represe~ts th0 ~requenoy distribution of silver halide grains in the emulsion used in Exa,mple 5 whlle ourve 1, as already me~tioned above, repre~ents the frequenoy distribution in the emulsion of Example 1413 33 ~
, .
' ,, ,, :
57~L
Figure 4 shows the results obtained from ~edimentatio~
measurements9 Along the ordinate are plotted the height in the storage tank (filling height 40 cm) ~rom which the individual samples for measurement were removed and along the abscissa are entered the silver content found at these different height~, measured as g of silver nitrate per kg of emulsionO The mea~urements represe~ted in Figure 4 were carried out after the emulsion had been left to stand for 6 hours. Curves G and ~I represent the values obtained with emulsions o~ Example 4 and curve~ G' and H~ the ~alues obtained with emulsions of Example 5. Curves G and G~ ~re obtained from samples according to the invention and curves H and H~ from comparison sample~.
The comparison shows that photographic emulsions prepared according to ~he invention have much less tendency ; to sedimentation phenomena than compari~on emulsions9 the results depending on whether the silver halide emulsions used are comparatively homodisperse or heterodisperse.
EX~MPLE 6 This example shows that compared with proces3es known in the art, the sen~itization process according to the invention i~ capable of producin~ photographic materials ~`~ with improved sensitivity.
To 1 kg of an iodobrQmide emulsion (silver content 0.3 mol per kg) oontaining 4-hydroxy-6-methyl-1,3,3a-7-tetraazaindene, a pyrocatechol solution and a sodium salt solution oi pentadeoylenesuccinic aoid dîglycolide were ; ' ' ' ' .
7~
added 24 g of coupler of the formula Cl O
Cl ~ ~ ~COC13H27 Cl Cl in an emulsi~ied ~orm with 6 g of dibutyl phthalate and ~ 180 g o~ a 2.5~ aqueous gelatine solution.
: Sensitization was carried out by the process described in Example 2. Sample I according to the inve~tion was sensitized with a sensiti~er dispersion according to Example 2 containing 45 mg of sensitizer I while comparison sample K was sensitized with 45 mg of sensitizer I dissolved to ~orm a 1:1000 solution in methyl alcohol.
Each o~ the resulting emulsions was hardened with 2 ml of a 5% triaorylo~ormal solution and cast on a transparent cellulose triacetate substrate, ' - Af-ter exposure and development oi the photographic : ~ ~ 20 materials~, U31~g N-butyl-N- 6-sulpho~utyl-p-phenylene ;diamine as developer sub~tanoe at room temperature, oompari-. : son shows that the ~ample acoording to the in~ention i9 more sensitive by 1.5 DIN than the comparison ~ample to ,~
~ : which the sensiti2ing dye had been added in methanolic : ~ 25 solution.
.
Other ~amples according to the-invention L and N
a~d comparison samples M and O were prepared in a similar : ~ h-G 1413 - 35 -~ .
' , ~
, . .. . . . . .
manner except that, for comparison with sample I and with comparison sample K, instead of using 45 mg of sen~itizer - II, only 20 mg were used in samples L and M and 10 mg in samples N and 0, When the sensitometric results are assessed, it is surprisingly found that even when smaller quantities of sensitizer are used in the materials according to the invention, these materials ~till show a sensitivity gain of from 1 to 105 DIN compared with comprison samples K, M and 0.
~Z .
~nother comparison example shows th0 advantage obtained with the process according to the invention when freeze dried sensitizer dispersions are used, in comparison ~: 15 with processe~ known in the art~
120 ml o~ a 1~ aqueous solution of 4-hydroxy-6-methyl-1,393a,7-tetraazaindene and 1 ml of glycerol were added to 1 kg of an iodobromide emul~ion (0.7 mol of sil~er per kg). The colour coupler used consisted of 42 g o~ the ~ 20 colour coupler degcribed in Example 6 added in emulsified j form in 12 g o~ dibutyl phthalate in 180 g o~ a 2.5 gelatine SOlUtiDn.
The amulsion was sansitized with 110 mg of sensitizer II which had been pretreated as ~ollows:
10 g of son~itizer II were milled as desoribed in Example 1 with 23.3 g o~ a oondensation product o~ naphthalene with formaldehyde and sulphurio acid ~aYerage molecular : wei~ht 420) as sodium ~alt, 100 g of sand a~d 100 ml of water.
A-a 1413 - 36 ;
The sand was then filtered off and the filtrate shock ~rozen with liquid nitrogen while the water was removed by sublimation under vacuum at a temperature below the melting point of the crystallised aqueous phase. l g of the resulting produc-t was taken up in 75 ml of water and from it, the quantity corresponding to llO mg of sensitizer was added to the emulsion previously described.
Working up the emul~ion, preparation of the photo-graphic material, exposure and processing were carried out as desc~ibed in Example 6.
A comparison material Q was prepared in a similar manner. In contrast to material P prepared according to the invention, it was sensitized with llO mg of sensitizer ~ which had been emulsified a~ described below before it was - added to the emulsion:
l g of sensitizer II was dissolved in a mixture of 50 ml of m-oresol and 25 ml of methyl alcohol and to this solution was added a solution of 3.33 g of a 50~ aqueous sodium dodecylbenzene sulphonate paste in 17 ml of ethyl acetate.
The oombined solutions were then emulsiXied i~ 350 ml of a 6~ gelatine solution with vigorou~ ~tirring ~nd $he volume of the emulsion was then made up $o lO0 ml wnth water. A qu~nt1ty of this sensit1zer emulsion w~ich corresponded to llO ~g of se~æitizer was added to l kg o~
the above desor1bed silver halide emulsion.
~he compari~on shows that the sensitivity of material ~-C 1413 _ 37 _ ,~ ~
i7~
P prepared according to the invention is higher by one ~IN than that of the comparison material Q.
1 kg of a silver iodobromide emulsion containing 1 mol of silver halide per kg and provided in the form o~
a mixture of a conventional silver iodobromide emulsion Wit}l a convert emulsion in proportions of 8:2 was màde ready for casting, using the cyan coupler a~d additives indicated in Example 2.
The emulsion was sensitized with 130 mg o~ sensitizer V and 130 mg of sensitizer III. In sample R according to the invention, the sensitizer mixture was dispersed in a dilute gelatine solution by the method described in Example 2 whereas in comparison s~mple S the sensitizer mixture was added as a 0.05% solution of sen3itizer V in dimethylformamide and as a 001% solution o~ sensitizer III
in methyl alcohol.
When the resulting emulsions had been cast and hardened with a water-soluble carbodiimide9 the photographic m~terials obtained were exposed and then developed in the usual manner, using N-ethyl-N-~-o~yethyl-3-methyl-p-phenylene diamine as developer sub~tanceO Sensitometric assessment shows that, in comparison wqth s~mple S o~ the known art7 Sample R a¢cording ~o the invention has gained in sensi-tivity by two DIN and its colour ~og is reduced by o . o6 colour densit~ units~
A-G 1413 - ~8 -.
Claims (7)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Process for introducing a substantially water-insoluble sensitizer or stabilizer into a light-sensitive silver halide emulsion comprising the steps of:
(a) preparing an aqueous dispersion of a substantial-ly water-insoluble sensitizer or stabilizer having a particle size of less than 1 µ, and (b) adding the aqueous or dried dispersion of said substantially water-insoluble sensitizer or stabilizer to a light-sensitive silver halide emulsion, the aqueous dispersion of step (a) being prepared by milling the sensitizer or stabilizer in an aqueous phase which is sub-stantially free from organic solvents in the presence of a dis-persing agent selected from monomeric, oligomeric and polymeric alkyl-aryl sulphonates.
(a) preparing an aqueous dispersion of a substantial-ly water-insoluble sensitizer or stabilizer having a particle size of less than 1 µ, and (b) adding the aqueous or dried dispersion of said substantially water-insoluble sensitizer or stabilizer to a light-sensitive silver halide emulsion, the aqueous dispersion of step (a) being prepared by milling the sensitizer or stabilizer in an aqueous phase which is sub-stantially free from organic solvents in the presence of a dis-persing agent selected from monomeric, oligomeric and polymeric alkyl-aryl sulphonates.
2. Process as claimed in claim 1 in which the water is completely removed from the aqueous dispersion and the dried dispersion of sensitizer or stabilizer is added to the silver halide dispersion.
3. Process as claimed in claim 2 in which the water is removed by freeze drying or atomisation drying.
4. Process as claimed in claim 3 in which the dried dis-persion of sensitizer or stabilizer is added to a melted silver halide emulsion either immediately or after it has been intro-duced into water or into an aqueous solution of binder.
5. Process as claimed in claim 4 in which the binder is gelatine and the weight ratio of gelatine to silver is less than 0.7.
6. Process as claimed in claim 1 in which the monomeric, oligomeric or polymeric alkyl-aryl sulphonate has at least 18 C
atoms in the molecule.
atoms in the molecule.
7. Process as claimed in claim 1 in which a sand mill is used for milling the sensitizer or stabilizer.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP2609742.7 | 1976-03-09 | ||
| DE19762609742 DE2609742C2 (en) | 1976-03-09 | 1976-03-09 | Process for the introduction of photographic additives in silver salt emulsions |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1105761A true CA1105761A (en) | 1981-07-28 |
Family
ID=5971915
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA273,559A Expired CA1105761A (en) | 1976-03-09 | 1977-03-09 | Method of introducing water insoluble sensitizers or stabilizers into silver halide emulsions |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS606496B2 (en) |
| BE (1) | BE852138A (en) |
| CA (1) | CA1105761A (en) |
| DE (1) | DE2609742C2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5360695A (en) * | 1993-01-26 | 1994-11-01 | Eastman Kodak Company | Aqueous developable dye diffusion transfer elements containing solid particle thermal solvent dispersions |
| US5401623A (en) * | 1992-10-05 | 1995-03-28 | Eastman Kodak Company | Reactivity control in microcrystalline coupler dispersions |
| US5512414A (en) * | 1993-09-23 | 1996-04-30 | Eastman Kodak Company | Solid particle coupler dispersions for color diffusion transfer elements |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1579481A (en) * | 1977-02-18 | 1980-11-19 | Ciba Geigy Ag | Preparation of photographic material |
| US4927744A (en) * | 1988-08-05 | 1990-05-22 | Eastman Kodak Company | Photographic element having solid particle dispersion oxidized developer scavenger |
| DE4433637A1 (en) | 1994-09-21 | 1996-03-28 | Agfa Gevaert Ag | Color photographic silver halide material |
-
1976
- 1976-03-09 DE DE19762609742 patent/DE2609742C2/en not_active Expired
-
1977
- 1977-03-07 BE BE1007996A patent/BE852138A/en not_active IP Right Cessation
- 1977-03-09 CA CA273,559A patent/CA1105761A/en not_active Expired
- 1977-03-09 JP JP2495577A patent/JPS606496B2/en not_active Expired
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5401623A (en) * | 1992-10-05 | 1995-03-28 | Eastman Kodak Company | Reactivity control in microcrystalline coupler dispersions |
| US5434036A (en) * | 1992-10-05 | 1995-07-18 | Eastman Kodak Company | Process for forming microcrystalline coupler dispersions |
| US5360695A (en) * | 1993-01-26 | 1994-11-01 | Eastman Kodak Company | Aqueous developable dye diffusion transfer elements containing solid particle thermal solvent dispersions |
| US5494775A (en) * | 1993-01-26 | 1996-02-27 | Eastman Kodak Company | Heat image separation with solid particle thermal solvent dispersions |
| US5512414A (en) * | 1993-09-23 | 1996-04-30 | Eastman Kodak Company | Solid particle coupler dispersions for color diffusion transfer elements |
Also Published As
| Publication number | Publication date |
|---|---|
| DE2609742C2 (en) | 1984-09-27 |
| JPS52110012A (en) | 1977-09-14 |
| DE2609742A1 (en) | 1977-09-22 |
| JPS606496B2 (en) | 1985-02-19 |
| BE852138A (en) | 1977-09-07 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| GB1570362A (en) | Method of introducing photographic additives into silver salt emulsions | |
| DE69920841T2 (en) | LIQUID CRYSTALLINE FILTER DYES FOR IMAGE RECORDING ELEMENTS | |
| GB2115569A (en) | Method of incorporating a photographic additive into a coating solution | |
| EP0566079B1 (en) | Aqueous, solid particle dispersions of dichalcogenides for photographic emulsions and coatings | |
| CA1105761A (en) | Method of introducing water insoluble sensitizers or stabilizers into silver halide emulsions | |
| JP3440162B2 (en) | Imaging element | |
| DE69916731T2 (en) | Photographic material with improved light absorption | |
| JPH05505255A (en) | Improving the stability of amorphous particle dispersions | |
| CA1076776A (en) | Method of making silver halide emulsions | |
| US4332887A (en) | Method for preparing photosensitive silver halide emulsions | |
| US3615789A (en) | Process for the manufacture of enriched colloidal silver | |
| EP0521612B1 (en) | Ultrafine gold and/or silver chalcogenide and production thereof | |
| US3883355A (en) | Crystallization of silver halide within an aqueous mixture of a water soluble silver complex and a polymeric colloid binder | |
| EP0985969A1 (en) | Liquid crystalline filter dyes for imaging elements | |
| US4533627A (en) | Process for the preparation of a silver halide emulsion | |
| US5104785A (en) | Process of forming silver halide grains | |
| US5240827A (en) | Photographic element containing large, selenium-sensitized silver chloride grains | |
| US5443948A (en) | Process for preparation of a photographic element | |
| EP0656401B1 (en) | New dyes for use in diverse applications | |
| DE2609741C2 (en) | ||
| BE1007901A3 (en) | Method for processing a black-white silver halogen photographic materialwith spectrally sensitised emulsions | |
| US1954334A (en) | Photographic emulsion containing fog inhibitors | |
| JPS63106744A (en) | Silver halide photographic sensitive material having high sensitivity to infrared rays | |
| US5888717A (en) | Photographic silver halide emulsion | |
| US4743534A (en) | Preformed silver halides for photothermographic system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |