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
  • G03C1/485—Direct positive emulsions
  • G03C1/48515—Direct positive emulsions prefogged
  • G03C1/48523—Direct positive emulsions prefogged characterised by the desensitiser
  • G03C1/4853—Direct positive emulsions prefogged characterised by the desensitiser polymethine dyes

Definitions

• Thej present invention relates to silver halide emulsions, more specifically to direct positive silver halide emulsions sensitized by novel dimethinecyanine dyes.
• the direct positive silver halide emulsions in the present specification are silver halide emulsions which are prepared so as to form positive images directly upon exposure to light (positive light image) and developing.
• one object of the present invention is to provide direct positive silver halide emulsions which retain maximum image density and do not cause residual color.
• the present invention relates to direct positive silver halide emulsions which contain at least one dimethinecyanine dye in which the 3-position of the indole nucleus (which has a hydrogen atom, chlorine atom, lower (C -C alkyl group, carboxyl group or lower (C -C alkoxycarbonyl group in the 2-position thereof) joins to the l, 2, 3 or 4-position of the cyanine heterocyclic nucleus, with the proviso that only when the cyanine heterocyclic nucleus is isoquinoline is the joining to the 1- or 3- position (but when joined to the 4-position, the cyanine nucleus is a quinoline or pyridine), through a dimethine chain, and, if desired, an organic desensitizer.
• the 3-position of the indole nucleus which has a hydrogen atom, chlorine atom, lower (C -C alkyl group, carboxyl group or lower (C -C alkoxycarbonyl group in the
• substituent in the 2-position of the indole nucleus of dimethinecyanine dyes used in the present invention there are a methyl group, ethyl group or butyl group as the lower alkyl group and a methoxycarbonyl group, ethoxycarbonyl group or t-butoxycarbonyl group as the lower alkoxycarbonyl group.
• cyanine heterocyclic nucleus of the dimethine cyanine dyes used in the present invention there are, for example, an oxazoline nucleus, oxazole nucleus, benzoxazole nucleus, naphthoxazole nucleus, thiazoline nucleus, thiazole nucleus, benzothiazole nucleus, naphthothiazole nucleus, selenazole nucleus, benzoselenazole nucleus, naphthoselenazole nucleus, Z-pyridine nucleus, 4-pyridine nucleus, 2-quinoline nucleus, 4-quinoline nucleus, 3-isoquinoline nucleus, l-isoquinoline nucleus, benzoimidazole nucleus, 3,3-dialkylindolenine nucleus, e.g., 3,3-dimethylimidazo-(4,5-b)-quinoxaline nucleus and pyrrolidine nucleus, where
• Such substituents there are alkyl groups, aryl groups, a hydroxyl group, an alkoxy group, a carboxyl group, an alkoxycarbonyl group, a nitro group or ahalogen atom, with preferred alkyl groups having 1-20 carbon atoms, preferred alkoxy groups having l-lO carbon atoms and a preferred aryl group being a phenyl group.
• thiazoles such as thiazole, 4-methylthiazole, 4-phenylthiazole, 4-(p-hydroxyphenyl)thiazole, S-methylthiazole, S-phenylthiazole, 5-(o-hydroxyphenyl)- thiazole, 4,5-dimethylthiazole and 4,5-diphenylthiaz'ole'; benzothiazoles such as benzothiazole, 4-hydroxybenzothiazole, 4-fiuorobenzothiazole, 4-chlorobenzothiazole,' 5 chlorobenzothiazole, 6 chlorobenzothiazole, 7 chloro benzothiazole, 4 methylbenzothiazole, 5 methylbenzothiazole, 6-methylbenzothiazole, 5,6 dimethylbenzothiazole, S-brornobenzothiazole, 6-brornobenzothia zole, 5- phenylbenzothiazole, 6
• the dimethinecyanine dyes used in the present invention can be synthesized, for example, by reacting aldehyde derivatives of indole compounds having a hydrogen atom, chlorine atom, lower alkyl group, carboxyl group or lower alkoxycarbonyl group in the 2-position with alkyl substituted quaternary ammonium salts of compounds having the desired cyanine heterocyclic nucleus in a suitable solvent, such as acetic anhydride and nitrobenzene, by heating.
• a suitable solvent such as acetic anhydride and nitrobenzene
• alkyl substituted quaternary ammonium salts of compounds having the desired cyanine heterocyclic nucleus can be represented by the formula:
• A is methyl, substituted methyl, e.g., methoxymethyl, etc.
• a methine chain may be formed by joining the carbon atom of the methyl group of A and R
• the other symbols have the same meaning as in Formula I.
• dimethinecyanine dyes used in the present invention are represented by the following formula (I).
• R represents a hydrogen atom or nitro group
• R represents a hydrogen atom, chlorine atom, lower (C -C alkyl group, carboxyl group or lower (C -C alkoxycarbonyl group
• R represents a hydrogen atom, alkyl group having 1-6 carbon atoms or aryl group such as phenyl or substituted phenyl such as tolyl, methoxyphenyl and nitrophenyl
• R represents an alkyl group having 1-6 carbon atoms, allyl group or aryl group such as phenyl or substituted phenyl
• L represents an unsubstituted methine group
• L represents methine group, e.g., a methine group which can be lower alkyl (C -C substituted, aralkyl substituted, e.g., benzyl, aryl substituted, e.g., phenyl, etc., substituted, wherein a substituent in L may bind
• R and Z were described in detail in the above.
• Examples of the alkyl group having 1-6 carbon atoms in R include a methyl group, ethyl group, butyl group or hexyl group, which may be substituted, for example, with a carboxy group.
• As the aryl group in R a phenyl group and a tolyl group are particularly preferable.
• alkyl group having 1-6 carbon atoms in R examples include, for example, a methyl group, ethyl group, propyl group, hexyl group, a hydroxyalkyl group (e.g., a fi-hydroxyethyl group), alkoxyalkyl groups (e.g., a ,s-methoxyethyl group), carboxyalkyl groups (e.g., ficarboxypropyl group), sulfoalkyl groups (e.g., a 'y-sulfopropyl group) and aralkyl groups (e.g., a monocyclic aralkyl group, preferably, having less than 3 carbon atoms in the alkyl moiety such as a phenethyl group and a henzyl group).
• a methyl group e.g., a fi-hydroxyethyl group
• alkoxyalkyl groups e.g., a ,s
• the aryl group in R a phenyl group and a tolyl group are particularly preferred.
• the substituent in the substituted methine group may be, for example, a methyl group, ethyl group, carboxyethyl group, phenethyl group, hydroxyethyl group, a methoxyethyl group, and this substituent may bind to R to form a methylene group. In this case, it is particularly preferred to form a 5- or 6-member ring.
• X- there are, for example, a chlorine ion, bromine ion, iodine ion, p-toluenesulfonic acid ion, ethylsulfonic acid ion and a perchlorate ion.
• n is 1 in the case that the compound represented by the formula (I) has a betaine structure or 2 in the other cases.
• dirnethinecyanine dyes can be synthesized in a manner similar to those described by merely substituting appropriate starting materials. The synthesis procedure per se is conventional.
• an organic desensitizer be included in the direct positive emulsions of the present invention.
• the organic desensitizers used in the present invention aer substances which have the ability to trap free electrons generated in silver halide particles by the application of radiant rays, and are substances which are adsorbed in the silver halide particles.
• they are compounds having a maximum occupied electron energy level lower than that of the valence electron zone of the particles. Measurement of the values of the electron energy levels can be made, though complicated operations are necessary. For example, determination for simple symmetric cyanine dyes is described in Photographic Science and Engineering, Vol. 11(3), page 129 1967), Tani and Kikuchi. Another such deterrnination for typical merocyanine dyes is described in Preprint (No. B-12) of International Congress of Photographic Science, 1970 (Moscow), Shiba and Kubodera.
• the electron enregy level corresponds primarily to an anode polarographic half-wave potential (Eox) and a cathode polarographic half-wave potential (Ered).
• Organic desensitizers are described in, for example, US. Pats. 3,023,102, 3,314,796, 2,901,351 and 3,367,779, in British Pats. 723,019, 698,575, 698,576, 834,839, 667,206, 748,681, 796,873, 875,887, 905,237, 907,367 and 940,152, French Pats.
• desensitizers which give a particularly preferred result are compounds represented by formula (II) in which the cathode polarographic halfwave potential (Ered) is more positive than 1.0 volt.
• R represents an alkyl group or allyl group
• Z, X- and m each have the same meaning as in formula (I) and a represents 1 or 2.
• R examples include a methyl group, ethyl group, butyl .group, hydroxyalkyl groups (e.g., an hydroxyethyl group), carboxyalkyl groups (e.g., a carboxymethyl group and a 3-carboxylpropyl group) and sulfoalkyl groups (e.g., a 2-sulfoethyl group and a 4-sulfobutyl p).
• hydroxyalkyl groups e.g., an hydroxyethyl group
• carboxyalkyl groups e.g., a carboxymethyl group and a 3-carboxylpropyl group
• sulfoalkyl groups e.g., a 2-sulfoethyl group and a 4-sulfobutyl p.
• organic desensitizers used in the present invention with success include, for example,
• silver halide emulsions used in the presentinvention there are silver chloride, silver bromide, silver bromochloride, silver iodochloride and silver iodobromochloride.
• the silver halide may have a particle size in the range of those as are commonly used in this art, those having an average particle size of 0.05it-L0 give a particularly preferred result.
• the silver halide used in the present invention may be composed of either regular particles or irregular particles, but regular particles display a more prefered effect. (See US. Pat. 3,501,306.)
• monodispersed emulsions are preferably used. (See U.S. Pat. 3,501,306.)
• raw emulsions used in direct positive silver halide photosensitve materials are classified into two types.
• the emulsion has nuclei for trapping free electrons in the interior of the silver halide crystals, the surface of which has previsuoly been chemically fogged.
• a characteristic of emulsions of this type is that they di rectly form positive images themselves, and it is possible only not to increase a spectral sensitization function but to sensitize the intrinsic absorption region of such emulsions by adding sensitizing dye(s) thereto.
• the compositions of the silver halides present should be adjusted so that chemical sensitizers or metal salts of a Group VIII metal which are used to give free electron trapping nuclei easily enter into the interior of the silver halide.
• the organic desensitizer it is possible to decrease minimum density (clean out) and particularly to prevent re-reversal. Furthermore, it is possible to increase the maximum density, sensitization and to improvement clean-out by adding bromine ions in an amount of from 1 to 10 mol percent or iodine ions in an amount of from 0.2 to 3 mol percent based on the silver halide.
• the second type of raw emulsions used in forming direct positives are those which do not have free electron trapping nuclei in the interior of the silver halide but wherein the surface is chemically fogged.
• These emulsions are silver halide emulsions composed of regular crystals which do not have a twinning plane and which are as free of lattice defects as possible. Such emulsions are preferably pure silver bromide.
• These emulsions do not form direct positive images themselves. However, if they adsorb organic desensitizer in the silver halide of the emulsons, direct positive images are obtained at high sensitivity.
• either of the above raw emulsions can be used, i.e., both raw emulsions can be effectively sensitized by adding the compounds in accordance with the present invention, preferably those represented by formula (I).
• the silver halide emulsions used in the present inven tion can be fogged by light or chemically.
• Chemical fog nuclei can be formed by adding, for example, hydrazine derivatives, formalin, thiourea dioxide, polyamine compounds, amine borane, methtyldichlorosilane and other known agents as disclosed in Belgian Pats. Nos. 721,564 and 708,563, US. Pat. No. 2,588,982, British Pat. Nd. 821,251, French Pat. No. 739,755 and Japanese Patent Publication No. 43-13,488. r
• fog nuclei can be formed by using a reducer together with metal ions nobler than silver (for example, gold ions, platinum ions and iridium ions) or further with halogen ions, as disclosed in US. Pats. Nos. 2,717,833 and 3,023,102, Belgian Pats. Nos. 713,272 and 721,567 and British Pat. No. 707,704. W
• gelatin is usually used as the protective colloid, and inactive gelatin (inert gelatin) is preferably used.
• inactive gelatin inactive gelatin
• photographically inactive gelatin deriva tives and water soluble synthetic polymers (for example, polyvinyl acrylate, polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl alginate, carboxymethyl cellulose and by droxyrnethyl cellulose) can be used, alone or as mixtures.
• the direct positive silver halide emulsions used in the present invention may containv additives such as a fog nuclei stabilizers (e.g. mercapto compounds, thione compounds and tetrazaindene compounds), an agent to decrease minimum density (e.g. stilbene compounds and triazine compounds), a whitening agent, an ultraviolet ray absorbing agent, a hardener (e.g. chromium alum, 2,4- dichloro-s-triazine compounds, azilydine compounds, epoxy compounds, mucohalogen acids and halogenoformyl-maleic acid derivatives), a coating assistant (e.g.
• a fog nuclei stabilizers e.g. mercapto compounds, thione compounds and tetrazaindene compounds
• an agent to decrease minimum density e.g. stilbene compounds and triazine compounds
• a whitening agent e.g. stilbene compounds and triazine compounds
• an ultraviolet ray absorbing agent
• a plasticizer e.g. polyalkylacrylate, alkylacrylateacrylic acid copolymers and polyalkylene oxide
• the amount of the dimethine dyes used in the present invention depends upon largely on the quantity of silver halide and the surface area of the silver halide particles, but 1 10- to 2x10 mols per mole of solver salt provides good results.
• dyes are applied by dissolving them in water or water miscible solvents such as methanol, ethanol, ethylene glycol monomethyl ether, methylethylketone, acetone and pyridine. Ultraonic vibrations can be applied to the dyes during dissolution, if desired. Further, the methods used in the sensitization of negative type emulsions, for example, as described in Japanese Patent Publication No. Sho 44-23389, Sho 44-27,555 and Sho 44-22,948, U.S. Pats. 3,485,634, 3,342,605 and 2,912,343, or German Pat. 1,947,935 can also be used. The addition of the dyes to the emulsion is conveniently carried out just before applica- 5 tion to the support, but the dyes may be added during chemical ripening or at precipitation of the emulsion.
• water miscible solvents such as methanol, ethanol, ethylene glycol monomethyl ether, methylethylketone, acetone and pyr
• An amount of the organic desensitizer used in the present invention varies depending upon the kind thereof, but 2 10' mols per mol of the silver halide(s) is preferably used.
• the emulsions according to the present invention can be applied to many kinds of supports to produce photographic elements.
• the emulsions may be applied to one surface or both surfaces of the support.
• the support may be transparent or opaque.
• typical supports there are cellulose nitrate films, cellulose acetate films, polyvinyl acetal films, polystyrene films, polyethylene terephthalate films and other polyester films, glass, paper, metal, wood,
• Plastic coated paper can also be used.
• the emulsions according to this invention are preferably treated in a development bath, a fixing bath and a stabilizing bath or in a bath which combines all of these treatments.
• One characteristic of the present invention is to sensitize direct positive emulsions using certain new dimethine dyes which do not cause substantial residual color.
• a chemical structural feature of the new dimethine dyes is that the 2- position of the indole nucleus is substituted by a hydrogen atom, lower alkyl group, chlorine atom, carboxyl group or lower alkoxycarbonyl group.
• sensitizing dyes which have a sensitizing function for common negative emulsions, particularly carbocyanine dyes,are effective for the sensitization of direct positive emulsions if they are used in a very large amount.
• this method is not prefered since the dyes strongly color the emulsions and cause residual color.
• dimethine' dyes having a 2-phenylindole nucleus or 2-pyridylindole nucleus show an excellent reversal property. However, they are unsatisfactory because residual color is caused. In the case of adding such dyes to direct positive emulsions untilmaximum sensitivity is obtained, a particular'tendency for residual color to occur is encountered.
• the dimethine dyes discovered by the present inventors have the characteristic that the residual color is very low, with residual color hardly being observed in the case that the 2-position of the indole nucleus is substituted by a "carboxyl group or a lower alkoxycarbonyl group;
• the second characteristic of the present invention is that the maximum density of the direct positive emulsion does not decrease substantially upon theuse of the dyes of the present invention.
• the third characteristic of the present invention is that not only do the dimethine dyes used in the present invention cause a low degree of residual color but also flattening of the characteristic curve (softening) is small.
• carbocyanine dyes and merocyanine dyes which are useful for the sensitization of negative emulsions have a tendency to flatten the characteristic curve. This flattening of the characteristic curve is not preferred in a high contrast direct positive sensitive materials such as reproduction films for lithotype films.
• the direct positive silver halide emulsions sensitized by the dimethine dyes used in the present invention have a good clean-out (minimum density) and have the excellent characteristic that re-reversal does not substantially occur.
• the new dimethine dyes used in the present invention have many excellent characteristics. However, if these dyes are used together with the organic a desensitizer, reversal sensitivity further increases and it is possible to produce direct positive silver halide emulsions having good clean-out.
• the direct positive silver halide emulsions according to the present invention can be used not only for hard direct positive silver halide photosensitive materials such as photosensitive materials for the reproduction of lithotype films and photosensitive materials for copying originals, but also for comparatively soft direct positive silver halide sensitive materials such as photosensitive materials for the reproduction of microfilm and photosensitive materials for the reproduction of X-ray films, etc. Further, they can be used for color photosensitive materials.
• the direct positive silver halide emulsions according to the present invention are useful not only in the case of application of light but also in the case of application of electrons X-rays and 'y-rays, etc.
• Solution 2 and Solution 3 were slowly added to Solution 1 over minutes while keeping all solutions at C.
• the mixture was then subjected to physical ripening at 60 C. for 5 minutes.
• 15 cc. of a 0.2N solution of potassium iodide was added thereto and the pAg was adjusted to 6.0 by adding silver nitrate solution thereto.
• the solution was subjected to ripening for 10 minutes by adding 1.2 mg. hydrazine and 1.0 mg. of potassium tetrachloroaurate (III) thereto.
• the solution was then neutralized with citric acid and washed with water.
• Solution 4 was added thereto to prepare a raw emulsion.
• the resulting emulsion contained silver halide particles having an average particle size of about 0.2 comprised particles of a regular tetragonal system having a phase.
• composition of the developer G. Metol 3.1 Anhydrous sodium sulfite 45 Hydroquinone 12 Sodium carbonate monohydrate 79 Potassium bromide 2 Water to make 1 liter. 7
• the dyes of the present invention have excellent characteristics in that D is high, the clean-out is good and the sensitivity is high as compared with the comparison dyes.
• Solution 1 prepared by dissolving 10 g. of inactive gelatin in 5 cc. of a 1N sodium chloride solution and 500 cc. of water at 60 0.
• Solution 2 prepared by dissolving 100 g. of silver nitrate in 500 cc. of water at 60 C.
• Solution 3 prepared by dissolving 35 g. of sodium chloride in 300 cc. of water at 60 C.
• Solution 4 prepared by dissolving 14 g. of potassium bromide in 200 cc. of Water at 60 C. was added over 5 minutes with stirring.
• the dyes, of the present invention have excellent properties with respect to sensitivi'ty, maximum optical density and cleanout, and the residual color is low. It is surprising that this difference is based on the difference of the substituent in the 2-position of the indolenine nucleus.
• Solution 1 prepared by dissolving 10 g. of inactive gelatin in 5 cc. of 1N sodium chloride solution and 500 cc. of water at 0.
• Solution 2 prepared by dissolving 100 g. of silver nitrate in 500 cc. of water at 60 C.
• Solution 3 prepared by dissolving 35 g. of sodium' chloride and 14 g. of potassium bromide in 300 cc. of water at 60 C.
• the mixture was subjected to ripening for- 5 minutes as in' Example 2, and the temperature was reduced to 35 C.
• the mixture was dissolved again by warming and the pH'was adjusted to 10.
• the'mixture was subjected to' iripenin'g for 10 minutes, at 60 C. and the pH was adjusted to'6. 5 with citric acid as in Example 2.
• dimethine cyanine dyes are compounds represented by formula (I).
• R group of the dimethinecyanine dyes represented by formula (I) is a hydrogen atom, chlorine atom, carboxyl group or lower alkoxycarbonyl group.
• organic desensitizer is a compound represented by formula (II):
• R represents an alkyl group
• X- represents an anion
• m and a each represent 1 or 2
• Z represents the non-metallic atoms necessary to complete a 5- or 6- membered heterocyclic ring.
• Fogged direct positive silver halide emulsions which contain at least one dimethinecyanine dye in which the 3-position of the indole nucleus, having a hydrogen atom, chlorine atom, lower alkyl group, carboxyl group or lower alkoxycarbonyl group in the 2-position thereof, joins to the 1-, 2-, 3-, or 4-position of the cyanine heterocyclic nucleus through a dimethine chain, with the proviso that only when the cyanine nucleus is isoquinoline is the joining to the 1- or S-position, and when joining is to the 4- position, the cyanine nucleus comprises a quinoline or pyridine ring, said dimethinecyanine dye; being-present in an amount eifective to provide maximum retained image density without residual color.
• cyanine nucleus is selected from the-.group-consisting of an. oxazoline nucleus, oxazolenucleus, benzoxazole nucleus, naphthoxazole nucleus, thiazoline :nu'cleus, thiazole nucleus, benzothiazole nucleus, naphthothiazole nucleus, selenazole nucleus, benzoselenazole nucleus,-naphthoselenagole nucleus, Z-pyridine nucleus,.
• 4 pyridine nucleus, 2- qumoline nucleus, 4-quinolinenucleus, .3-isoquinoline nu cleus, 1 -isoquinoline nucleus,- benzoimidazole nucleus," 3,3- dialkylindolenine nucleus, imidazo(4,5-b)quinoxaline 'nucleus and pyrrolidine nucleus.
• aryl group a hydroxyl group, an alkoxy group, a carboxyl group, an alkoiry carbonyl group, 'a nitro group or s hal.
• R is a hydrogen atom or C C alkyl group
• R comprises a C C alkyl group, an allyl group or an aryl group
• L and L comprise a methine group
• X- is an anion
• Z represents the non-metallic atoms necessary to complete a cyanine heterocyclic nucleus.
• the direct positive emulsions of Claim 1 which further include an organic desensitizer, which organic desensitizer has a cathodic polarographic half-wave potential (Ered) more positive than 1.0.
• R is an alkyl group or allyl group
• X- is an anion
• m and a are 1 or 2
• Z represents the non-metallic atoms necessary to complete a cyanine heterocyclic nucleus.

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• Silver Salt Photography Or Processing Solution Therefor (AREA)
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• 1971
  • 1971-12-24 JP JP93572A patent/JPS5437490B2/ja not_active Expired
• 1972
  • 1972-12-21 FR FR7245682A patent/FR2164806B1/fr not_active Expired
  • 1972-12-22 GB GB5955872A patent/GB1379290A/en not_active Expired
  • 1972-12-26 US US00318047A patent/US3832184A/en not_active Expired - Lifetime
  • 1972-12-27 DE DE2263529A patent/DE2263529A1/de active Pending

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