EP0345444A1 - Light-sensitive non-silver photographic element and process for incorporating hydrophobic compositions into hydrophilic colloid compositions - Google Patents
Light-sensitive non-silver photographic element and process for incorporating hydrophobic compositions into hydrophilic colloid compositions Download PDFInfo
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- EP0345444A1 EP0345444A1 EP89107013A EP89107013A EP0345444A1 EP 0345444 A1 EP0345444 A1 EP 0345444A1 EP 89107013 A EP89107013 A EP 89107013A EP 89107013 A EP89107013 A EP 89107013A EP 0345444 A1 EP0345444 A1 EP 0345444A1
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- dye
- light
- counter ion
- silver photographic
- ionic
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- 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
- G03C7/02—Direct bleach-out processes; Materials therefor; Preparing or processing such materials
Definitions
- the present invention relates to a light-sensitive non-silver photographic element including a support base and a hydrophilic layer coated thereon said hydrophilic layer including an ionic dye-counter ion imaging combination dissolved in water-immiscible organic solvent droplets dispersed therein in reactive association with a non-ionic surfactant compound.
- Non-silver imaging methods capable of recording a positive image simply upon exposure to radiation of selected wavelength are known in the art; the radiation absorbed by the dye which is in reactive association with an appropriate counter ion causes the dye to bleach.
- Non-silver imaging methods are based on the fact that light absorption by a dye sensitizes the dye's own destruction or decolorization. For example, a yellow dye absorbs blue light and the excited dye thus formed reacts with an activator which releases a species to bleach the dye. Similarly, green and red lights would respectively cause the destruction of the magenta and cyan dyes. Thereafter the element may be stabilized to fix the image by destruction of the counter ion or by separation of the dye from the counter ion.
- the same ionic dye-counter ion combinations act as photoinitiators for free-radical addition polymerizable compositions.
- imaging dyes are normally ionic dyes (that is a dye with a positive or negative charge) associated with an appropriate counter ion as described in British Patent Application No. 84 301 156.
- ionic dyes that is a dye with a positive or negative charge
- a dye ⁇ -iodonium+ combination has been described in EP patent applications Nos. 120,601 and 175,504 and dye+-borate ⁇ combination has been described in US patent No.4,307,182.
- European Patent Application No. 223,587 describes analogous ionic dye-counter ion combinations in association with free-radical polymerizable compounds and color forming compounds.
- the dyes used may be of any color and any chemical class which is capable of bleaching upon exposure to radiation of selected wavelength in the presence of a counter ion.
- photographic additives such as the ionic dye-counter ion combinations
- ionic dye-counter ion combinations are hardly soluble in water and, when soluble in water-miscible organic solvents, they are incompatible with hydrophilic colloid compositions when incorporated therein through said organic solutions.
- hydrophobic compounds into hydrophilic colloidal binders
- dispersion technique One way of introducing hydrophobic compounds into hydrophilic colloidal binders is the so-called dispersion technique.
- the hydrophobic photographic additives are dissolved in water-immiscible high-boiling organic solvents (also called in the art permanent solvents, crystalloidal solvents, oil-type solvents, oil-formers and the like) and the resulting organic solution is added to an aqueous composition containing a hydrophilic colloid (gelatin) and a dispersing agent (normally including an anionic surfactant).
- the mixture is then passed through a homogenizing apparatus (colloidal mill) to form a dispersion of fine droplets of said organic solvent containing the hydrophobic photographic additives.
- a homogenizing apparatus colloidal mill
- the obtained dispersion is then mixed with the hydrophilic colloid composition (gelatin silver halide emulsion or other gelatin-containing composition) which is used to form (by coating) the photographic layer.
- US patent 3,860,425 refers to the above mentioned dispersion technique in which the dispersed phase is an oil such as dibutylphthalate, butyllaurate, tricresylphthalate and tricresylphosphate and the material dissolved in such dispersed oil is an oleophilic material such as a dye for silver dye bleaching process, a coupler free of water solubilizing group, an ultraviolet absorber, an antioxidant, a dye image stabilizer, or an optical brightener, the dispersion being stabilized with a non-ionic agent used in combination with an anionic agent.
- an oil such as dibutylphthalate, butyllaurate, tricresylphthalate and tricresylphosphate
- the material dissolved in such dispersed oil is an oleophilic material such as a dye for silver dye bleaching process, a coupler free of water solubilizing group, an ultraviolet absorber, an antioxidant,
- the imaging methods which make use of ionic dye-counter ion imaging combinations dissolved in water-immiscible oil solvents dispersed in hydrophilic media can give better results if the dispersion is made in presence of a sorbitan ester non-ionic surfactant (including a polyoxyethylene derivative thereof) having a HLB (hydrophilic-lipophilic balance) value in the range from 4 to 10 in absence of anionic surfactants.
- a sorbitan ester non-ionic surfactant including a polyoxyethylene derivative thereof having a HLB (hydrophilic-lipophilic balance) value in the range from 4 to 10 in absence of anionic surfactants.
- the present invention relates to a light-sensitive non-silver photographic element including a support base and a hydrophilic layer coated thereon including an ionic dye-counter ion imaging combination dissolved in water-immiscible organic solvent droplets.
- the droplets are dispersed in the hydrophilic layer in reactive association with a sorbitan ester non-ionic surfactant having a HLB value in the range from 4 to 10.
- the selection of the surfactant needed to make the oil ionic dye-counter ion dispersion and to keep it stable (free from crystallization) within the layer (including it) is critical not only to the stability of the dispersion but also to the sensitometric results obtained with such dye-ion imaging combination.
- the use of anionic and cationic surfactants has been found to result in poor sensitivity and high D min . It is believed that they disrupt the ionic dye-counter ion reactive association which is the basis of the imaging process of interest to the present invention.
- Non-ionic surfactants are believed to be particularly good aids for the ionic dye-counter ion imaging chemistry due to the fact that they do not apparently disrupt the necessary dye-activator salt. Within the class of non-ionic surfactants, it has been found that better results are obtained if the dispersion is made in the presence of a sorbitan ester non-ionic surfactant having a HLB value of 4 to 10.
- Such sorbitan ester non-ionic surfactant compounds may be a sorbitan fatty acid ester non-ionic surfactant or a polyoxyethylene sorbitan fatty acid ester non-ionic surfactant, represented by the general formula (I) : wherein w+x+y+z represents 0 to 30, preferably 5 to 20, and R1, R2, R3 and R4 each represents a hydroxy group or a -O- -R5 group wherein R5 represents an aliphatic saturated or unsaturated carbon atom alyphatic chain of a fatty acid, preferably including 5 to 30 carbon atoms, such as lauric acid, myristic acid, palmitic acid, oleic acid, stearic acid, ricinoleic acid and the like, in which at least one of R1, R2, R3 and R4 represents a hydroxy group and at least one of R1, R2, R3 and R4 represents a -O- -R5 group, and the value of w+
- the sorbitan fatty acid ester non-ionic surfactants are, in general, manufactured by direct reaction of sorbitol with fatty acids under the influence of heat or acidic reagents or both, during which internal ether formation as well as esterification occurs.
- the sorbitan fatty acid esters resulting from simultaneous internal ether formation and esterification consist of components esterified to different extents (mono-, di- and triesters) as described by F. R. Benson in Nonionic Surfactants, edited by M. J. Schick, M. Dekker Inc. New York, 1967, pages 264-266.
- polyoxyalkylene sorbitan fatty acid ester non-ionic surfactants are, in general, manufactured by reaction of ethylene oxide with sorbitan fatty acid esters as described by F. R. Benson in Nonionic Surfactants, edited by M. J. Schick, M. Dekker Inc. New York, 1967, pages 270-272.
- non ionic surfactants are to be used in the substantial or total absence of any anionic or cationic surfactants.
- Sorbitan esters such as for example SpanTM-20, are highly preferred as leading to thermo-stable, well resolved ( ⁇ 1 ⁇ m) droplet dispersion of oil in gelatin, with the imaging chemistry located in the oil as desired.
- TergitolTM e.g. TMN-10 non-ionic surfactants may be used but they give dispersions with medium to poor thermo-stability and larger droplets than attainable with sorbitan esters.
- HLB hydrophilic-lipophilic balance
- Sorbitan esters SPANTM
- polyoxyethylene sorbitan esters TWEENTM
- the ionic dyes used may be either anionic and cationic, depending on the polarity of the active counter ion.
- a preferred embodiment of the invention involves an anionic dye in reactive association with a positively charged counter ion, such as for example an iodonium+ counter ion.
- Particularly useful anionic dyes for use in this invention are oxonol dyes of the general formula (II): wherein R6, R7, R8 and R9 each represents 1 to 10 atoms chosen among carbon, hydrogen, nitrogen, oxygen or sulfur to form a substituent such as substituted or unsubstituted alkly group or aryl group (such as phenyl, naphthyl group) or heterocyclic group (such as pyridyl group) directly linked to the rest of the molecule or attached to the molecule through link groups such as oxygen, sulfur, carbonyl, sulfonyl, carbonamido, sulfonamido, ureido, carbonylester, carbamoyl, sulfamoyl, aminocarnonyl and aminosulfonyl, and the like, or other terminal groups, preferably electron-withdrawing groups, such as cyano, hydroxy, nitro and halogen (Cl, Br and F).
- R6, R7, R8 and R9 may be the same or different and are chosen to form a symmetrical or an unsymmetrical dye molecule.
- R6 and R7 and, respectively, R8 and R9 may be taken together to represent the C, H, N, O and S atoms to form a simple (5 or 6 atoms) or condensed (including 9 or 10 atoms) heterocyclic or alicyclic nucleus (such as barbituric acid, thiobarbituric acid, pyrazolone, oxindole, indandione, isoxazolone and 1,1-dioxo-3-oxothiophene).
- R10, R11 and R12 each represents hydrogen, low alkyl groups (containing 1 to 5 carbon atoms), aryl groups (such as phenyl group), saturated and unsaturated heterocyclic groups (such as pyridine and pyrroline groups) or alicyclic groups having 5 or 6 carbon atoms (such as cyclopentane and cyclohexane) or atoms chosen within carbon, hydrogen, nitrogen, oxygen and sulfur to form a simple (including 5 or 6 atoms) or condensed (including 9 or 10 atoms) aromatic or heterocyclic or alicyclic nucleus (such as phenyl, piridyl, naphthalene groups).
- R6, R7, R8, R9, R10, R11 and R12 are chosen to give dyes useful to the present invention as known in the art, preferably having no more than 40 carbon atoms.
- Y+ represents a cation.
- oxonol dyes examples include:
- a particular useful counter ion to be associated with a negatively charged dye is an iodonium+ counter ion of an iodonium salt.
- the iodonium salts that may be used in the imaging system are compounds consisting of a cation wherein a positively charged iodine atom bears two covalently bonded carbon atoms, and any anion.
- the acid from which the anion is derived has a pKa ⁇ 5.
- the preferred compounds are diaryl, aryl/heteroaryl or diheteroaryl iodonium salts in which the carbon-iodine bonds are from aryl or heteroaryl groups.
- Aliphatic iodonium salts are not normally thermally stable at temperature above 0°C. However, stabilised alkyl phenyl iodonium salts such as those disclosed in Chem.Lett. 1982, 65-6 are stable at room temperature and may be used.
- Suitable iodonium salts may be represented by the formula (III): wherein Ar1 and Ar2 independently represent carbocyclic or heterocyclic aromatic-type groups generally having from 4 to 20 carbon atoms, or together with the iodine atom complete an "aromatic" heterocyclic ring (to the purposes of the present invention pyrazole, thiazole and furane are considered aromatic heterocyclic nuclei).
- Ar1 and Ar2 independently represent carbocyclic or heterocyclic aromatic-type groups generally having from 4 to 20 carbon atoms, or together with the iodine atom complete an "aromatic" heterocyclic ring (to the purposes of the present invention pyrazole, thiazole and furane are considered aromatic heterocyclic nuclei).
- These groups include substituted and unsubstituted aromatic hydrocarbon rings, e.g. phenyl or naphthyl, which may be substituted with alkyl groups, e.g. methyl, alkoxy
- hetero-cyclic groups include thienyl, furanyl and pyrazolyl groups which may be substituted with similar substituents as described above.
- Condensed aromatic/hetero-aromatic groups, e.g. 3-indolinyl, may also be present.
- Z ⁇ represents an anion (such as, for example, Cl ⁇ , I ⁇ , Br ⁇ , perfluoro(4-ethylcyclohexane)sulfonate, sulfate, methyl sulfate, methanesulfonate) which may be incorporated into Ar1 or Ar2.
- anion such as, for example, Cl ⁇ , I ⁇ , Br ⁇ , perfluoro(4-ethylcyclohexane)sulfonate, sulfate, methyl sulfate, methanesulfonate
- Ar1 and Ar2 do not have more than two substituents at the ⁇ -positions of the aryl groups. More preferably, Ar1 and Ar2 are both phenyl groups containing no ⁇ substituents, such as in iodonium salts represented by the formula (IV): wherein R is an alkyl group having 1 to 20 carbon atoms, preferably having 1 to 5 carbon atoms, such as methyl, ethyl, iso-propyl or n-butyl. Z ⁇ has the same meaning as in (III).
- the ⁇ -positions of the aryl groups may be linked together to include the iodine atom within a ring structure, such as in iodonium salts represented by the formula (V): in which A is an oxygen or sulphur atom.
- Z ⁇ has the same meaning as in (III).
- Suitable iodonium salts include polymers containing units (VI) in which Ph represents phenyl. Z ⁇ has the same meaning as in (III).
- iodonium salts examples include:
- the dye/iodonium system has its greatest sensitivity at the lambda max of the longest wavelenght absorbance peak. Generally, it is necessary to irradiate the system with radiation of wavelenght in the vicinity of this lambda max for bleaching to occur.
- a combination of coloured dyes may be used, e.g. yellow, magenta and cyan, in the same or different layers in an element and these can be selectively bleached by appropriate visible radiation to form a full color image.
- Monochromatic or polychromatic images may be produced by using the photosensitive materials with relatively short exposure times in daylight or sunlight or even artificial sources of light (e.g. fluorescent lamps or laser beam).
- the exposure time for adequate results, for example when using an 0.5 kW tungsten lamp at a distance of 0.7 m, may be between 1 second to 10 minutes.
- the weight ratio of bleachable dye to iodonium salt in the element is in the range from 1:1 to 1:50, preferably in the range from 1:2 to 1:10.
- a preferred composition of the dye iodonium ion bleaching reaction is the combination of an oxonol dye anion with the activator iodonium cation to form an organic salt which is highly soluble in oils, such as di-butyl phthalate, di-butyl lauramide.
- the close reactive association of the sensitizing dye with the iodonium moiety ensures easy electron transfer from the dye to the iodonium moiety, as desired.
- Another embodiment of the present invention com strictlyprises a cationic dye in reactive association with a negatively charged counter ion.
- dye bleaching systems can give good results by using positively charged dyes in reactive association with a negatively charge counter-ion, such as a borate ⁇ counter ion.
- the cationic dye to be used in reactive association with the borate ⁇ counter ion may be of any color and any chemical class.
- the dyes should not contain groups which would fix or desensitize the borate salts (e.g. carboxylic acid groups, sulfonic acid groups and readily reducible metal cations such as metal cations at least as readily reducible as ferric ion).
- the bleachable dyes may be selected from a wide range of known classes of dyes including methine, cyanine, carbocyanine, azomethine, styryl, xanthene, azine or rhodamine dyes.
- Particularly useful cationic dyes are cyanine dyes of the general formula (VII): wherein p is an integer of 0 to 5 and R13, R14, R15 and R16 each represents 1 to 10 atoms chosen among carbon, hydrogen, nitrogen, oxygen or sulfur to form a substituent such as substituted or unsubstituted alkly group or aryl group (such as phenyl, naphthyl group) or heterocyclic group (such as pyridyl group) directly linked to the rest of the molecule or attached to the molecule through link groups such as oxygen, sulfur, carbonyl, sulfonyl, carbonamido, sulfonamido, ureido, carbonylester, carbamoyl, sulfamoyl, aminocarbonyl and aminosulfonyl, and the like, or other terminal groups, preferably electron-withdrawing groups, such as cyano, hydroxy, nitro and halogen (Cl
- R13, R14, R15 and R16 may be the same or different and are chosen to form a symmetrical or an unsymmetrical dye molecule.
- R13 and R14 and, respectively, R15 and R16 may be taken together to represent the C, H, N, O and S atoms to form a simple (5 or 6 atoms) or condensed (including 9 or 10 atoms) heterocyclic nucleus, such as oxazoline, oxazole, benzoxazole, the naphthoxazoles (e.g.
- the benzimidazoles e.g. 1,1-dimethylbenzimidazole
- imidazoline imidazole
- benzimidazole the naphthimidazoles (e.g. naphth ⁇ 2,3-d ⁇ imidazole)
- pyridine a wide variety of substituents, such as hydroxy, the halogens (e.g. fluoro, bromo, chloro and iodo), alkyl groups or substituted alkyl groups (e.g.
- aryl groups or substituted aryl groups e.g. phenyl, 1-naphthyl, 2-naphthyl, 4-sulfophenyl, 3-carboxyphenyl and 4-biphenyl
- aralkyl groups e.g. benzyl and phenethyl
- alkoxy groups e.g.
- aryloxy groups e.g. phenoxy and 1naphthoxy
- alkylthio groups e.g. ethylthio and methylthio
- arylthio groups e.g. phenylthio, p-tolylthio and 2-naphthylthio
- methylenedioxy cyano, 2-thienyl, styryl, amino or substituted amino groups (e.g. anilino, dimethylanilino, diethylanilino and morpholino)
- acyl groups e.g. acetyl and benzoyl
- sulfo groups e.g. acetyl and benzoyl
- R17 and R18 can be the same or different and represent alkyl groups, aryl groups, alkenyl groups or aralkyl groups, with or without substituents (e.g. carboxymethyl, 2-hydroxyethyl, 3-sulfopropyl, 3-sulfobutyl, 4-sulfobutyl, 2-methoxyethyl, 2-sulfatoethyl, 3-thiasulfatoethyl, 2-phosphonoethyl, chlorophenyl and bromophenyl) having 1 to 10 carbon atoms.
- substituents e.g. carboxymethyl, 2-hydroxyethyl, 3-sulfopropyl, 3-sulfobutyl, 4-sulfobutyl, 2-methoxyethyl, 2-sulfatoethyl, 3-thiasulfatoethyl, 2-phosphonoethyl, chlorophenyl and bromoph
- R19, R20 and R21 each represents hydrogen, low alkyl groups (containing 1 to 5 carbon atoms), aryl groups (such as phenyl groups), saturated and unsaturated heterocyclic groups (such as pyridine and pyrroline groups) or alicyclic groups having 5 or 6 carbon atoms (such as cyclopentane and cyclohexane) or atoms chosen within carbon, hydrogen, nitrogen, oxygen and sulfur to form (when taken together) a simple (including 5 or 6 atoms) or condensed (including 9 or 10 atoms) aromatic or heterocyclic or alicyclic nucleus (such as phenyl, piridyl, naphthalene groups).
- the substituents R13, R14, R15, R16, R17, R18, R19, R20 and R21 are to give dyes useful to the present invention, as known in the art, preferably having no more than 40 atoms.
- X ⁇ represents an anion (such as, for example, Cl ⁇ , I ⁇ , Br ⁇ , perfluoro(4-ethylcyclohexane)sulfonate, sulfate, methyl sulfate, methanesulfonate).
- cyanine dyes include: wherein PECHS is perfluoro(4-ethylcyclohexane)sulphonate.
- particular useful counter ion to be associated with the positively charged dye is a borate ⁇ counter ion of a borate salt.
- the borate salts that may be used in the imaging system are the tetra(aliphatic)borates, as described in US 4,307,182, wherein all of the carbon-to-boron bonds are from aliphatic groups.
- Imaging in the light sensitive dye/borate system is affected by irradiation.
- the radiation which is absorbed by the dye/borate system causes the dye to bleach.
- a positive image is then produced.
- the use of cationic dyes is believed to spectrally sensitize the borates to radiation absorbed by the dyes associated with the borate. These are not used as sensitizing dyes as used in photographic imaging systems (usually in ratios of 1/500 or 1/10000 of dye to light sensitive agents). These dyes are used in proportion of at least 1/10 to about 1/1 in ratio to the borate. Because the dye-borate system is molecularly spectrally sensitive, a multiplicity of colored dyes may be used (e.g. cyan, magenta and yellow) in the same or different layers.
- Reactive association is defined as such physical proximity between the compounds as to enable a chemical reaction to take place between them upon exposure to light.
- an element may be prepared which is sensitive to radiation of a selected wavelength band within useful ranges, such as 300 to 1100 nm, the particular wavelength and the width of the band depending upon the absorption characteristics of the dye.
- useful ranges such as 300 to 1100 nm, the particular wavelength and the width of the band depending upon the absorption characteristics of the dye.
- a dye has more than one absorption peak it is the wavelength corresponding to the longest wavelength peak at which one would choose to irradiate the element.
- Elements intended for the production of images from radiation in the visible region will contain dyes which will bleach from a colored to a substantially colorless or very pale state.
- such bleachable dyes will undergo a change such that the transmission optical density at the lambda max will drop from 1.0 or more to less than 0.09, preferably to less than 0.05.
- the dyes will generally be coated on the support to provide an optical density of about 3.0 or more.
- the dyes will not normally be colored to the eye and there may be no visible change upon exposure to ultraviolet and bleaching.
- the image-wise exposed elements may be used as masks for further ultraviolet exposure after fixing.
- Infrared sensitive elements contain dyes having an absorption peak in the wavelength range 700 to 1100 nm. These dyes may also have absorption peaks in the visible region before and/or after bleaching. Thus as well as providing a mean for obtaining masks for subsequent infrared exposure in a similar manner to the ultraviolet masks, infrared sensitive elements may record a visible image upon image-wise exposure to infrared radiation.
- the present invention also relates to a coating composition for the manufacture of a light sensitive non-silver photographic element which includes an ionic dye-counter ion imaging composition dissolved in a water immiscible organic solvent dispersed therein in the form of droplets associated with a non-ionic sorbitan ester surfactant compound having a HLB value of 4 to 10.
- the present invention relates to a process for the manufacturing of a light sensitive non-silver photographic element which includes coating on a support base a composition substantially consisting of a hydrophilic binder having dispersed therein droplets of a water immiscible organic solvent including dissolved therein an ionic dye-counter ion imaging composition in the presence of a sorbitan ester surfactant compound having a HLB value of 4 to 10.
- the process of incorporating hydrophobic additives such as hydrophobic dye-counter ion combination agents, into hydrophilic colloid components layers of photographic materials (such as light sensitive layers, protective layers, intermediate layers and the like), consists of incorporating into hydrophilic colloid coating compositions of said layers the hydrophobic additives themselves in the form of a dispersion of fine droplets consisting of a water-immiscible high boiling organic solvent in which said hydrophobic additives have been dissolved.
- hydrophobic additives such as hydrophobic dye-counter ion combination agents
- the hydrophobic photographic additives are dissolved in water-immiscible high boiling organic solvents (also called in the art permanent solvents, crystalloidal solvents, oil solvents, oil-formers and the like) and the resulting organic solution is added to an aqueous composition containing the hydrophilic colloid (gelatin) and a dispersing agent (surfactant).
- the mixture is then passed through a homogeneizing apparatus (colloidal mill) to form a dispersion of fine droplets of said organic solvent comprising the hydrophobic photographic additives.
- the obtained dispersion is then mixed with the hydrophilic colloid composition (light sensitive gelatin composition or other gelatin composition) which is used to form (by coating) the photographic layer.
- the obtained photographic layer includes the additive dispersed therein.
- Organic solvents for dispersing hydrophobic compounds are desired to meet several requirements. They have to possess an excellent dissolving power towards said additives, to keep the fine droplets stably dispersed, to have a refractive index which is as close as possible to that of the hydrophilic colloid wherein they are dispersed, and not to deteriorate the physical properties of the layers wherein they are incorporated. Moreover, said organic solvents have to not negatively affect the photographic properties of the materials wherein they are used to disperse photographic additives. Organic solvents may be selected from esters of carboxylic acid, phosphate esters, carboxyl amides, ethers and substituted hydrocarbons.
- di-n-butyl phthalate 2(ethyl-hexyl)phthalate, di-octyl phthalate, diisodecyl phthalate, di-(methoxyethyl) phthalate, N-N-diethyl lauramide, di-butyl lauramide, butyl acetanilide, tricresyl phosphate, tributyl phosphate, tri (butoxy-ethyl) phosphate, di-butyl sebacate, di-octyl sebacate, etc.
- the amounts of high boiling solvents used according to this invention for dispersing hydrophobic additives can vary according to the used additive. It is, however, undesiderable to use large amounts of such solvents, because large excess of solvents may sometimes deteriorate the physical properties of the photographic layers. Accordingly, it is normal practice to use the high boiling solvents in a weight ratio to each additive in the range 01 to 8.0, preferably in the range 0.3 to 3.0.
- a low-boiling solvent or water-soluble high-boiling solvent is sometimes advantageously used along with the water-insoluble high-boiling solvent as mentioned above for dissolving the ionic dye-counter ion combination, e.g., propylene carbonate, ethyl acetate, butyl acetate, ethyl propionate, sec-butyl alcohol, tetrahydro-furan, cyclohexanone, dimethylformamide, diethylsulphoxide and 2-methoxy ethanol.
- ionic dye-counter ion combination e.g., propylene carbonate, ethyl acetate, butyl acetate, ethyl propionate, sec-butyl alcohol, tetrahydro-furan, cyclohexanone, dimethylformamide, diethylsulphoxide and 2-methoxy ethanol.
- the bleachable dye and counter ion salt may be applied to the support in a binder.
- Suitable binders are transparent or translucent, are generally colourless and include natural polymers, synthetic resins, polymers and copolymers, and other film forming media.
- the binders may range from thermoplastic to highly cross-linked, and may be coated from aqueous or organic solvents or emulsions.
- Gelatin is the preferred hydrophilic colloid for use in the present invention.
- other water-soluble colloidal substances or mixture thereof can also be used.
- Exemplary hydrophilic colloidal substances include gelatine derivatives, such as phthalated gelatin and acetylated gelatine, cellulose derivatives, such as carboxymethyl cellulose, starch, casein, zein, synthetic hydrophilic colloids such as polyvinyl alcohol, polyvinyl pyrrolidone, copolymers of acrylic acid esters, acrylonitrile and acrylamides, etc.
- the amount of gelatin used in practice depends on the dispersing solvent amount and the coating thickness required. It is advantageously used in the amount of 2.5 to 5% by weight of whole dispersion.
- Suitable supports include transparent film, e.g. polyester, paper e.g. baryta-coated photographic paper, and metallised film. Opaque vesicular polyester films are also useful.
- Yellow dyes represented by the formulas (1) and (4) (2.0 g and 1.6 g) were dissolved in a mixture of 24 ml of DEL (diethyl lauramide), 4 ml of dimethyl formamide (DMF) and ethanol (30 ml) at 50°C.
- DEL diethyl lauramide
- DMF dimethyl formamide
- ethanol 30 ml
- iodonium salt 9 (5.2 g).
- the resulting solution was dropwise added to 200 ml of 10% aqueous gelatin while stirring with a high speed rotating mixer to effect dispersion.
- the dispersion was continued for 5 minutes, after which time 136 ml water was added and dispersion maintained for 3 minutes.
- This stock emulsion is used immediately, because although initially the emulsion is well formed with ⁇ 0.1 ⁇ m droplets, it is not stable after 12 hours at room temperature. Separation of the oil is observed.
- the emulsion was found to separate large oil drops after 24 hours.
- the emulsion was conventionally coated onto subbed polyester and dried for 1 hour at 40°C in the dark.
- the resulting yellow coating was analysed by monitoring the sensitivity of the yellow dye bleach at 460 nm.
- the HostapurTM surfactant of case b) is an anionic surfactant. It gives a good stability but the values of D max and D min obtained by the use of such a type of surfactant are worse than the values obtained without the use of any surfactants.
- the TergitolTM TMN-4 and TergitolTM TMN-10 surfactants of, respectively, cases c) and d) are non-ionic surfactants.
- TergitolTM TMN-4 a good stability is obtained and the values of D max and D min are better than the values obtained in case b) (by the use of an anionic surfactant).
- the resulting solution was added to 50 ml of an aqueous solution kept at 45°C and containing 5 g of gelatine. The resulting mixture was stirred for 5 minutes in a high speed rotary mixer to effect dispersion.
- oxonol salt of formula (3) 0.5 g was dissolved by heating in a mixture of 6 ml of DEL, 1 ml of DMF, 7 ml ethanol and 0.2 of non-ionic surfactant (SpanTM 20). Under a diminuished yellow-green light, 0.6g of iodonium salt (9) was added and the resulting solution was stirred by Silverson into 50 ml of 10% aqueous gelatin kept at 45°C.
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Abstract
Description
- The present invention relates to a light-sensitive non-silver photographic element including a support base and a hydrophilic layer coated thereon said hydrophilic layer including an ionic dye-counter ion imaging combination dissolved in water-immiscible organic solvent droplets dispersed therein in reactive association with a non-ionic surfactant compound.
- Non-silver imaging methods capable of recording a positive image simply upon exposure to radiation of selected wavelength are known in the art; the radiation absorbed by the dye which is in reactive association with an appropriate counter ion causes the dye to bleach. Non-silver imaging methods are based on the fact that light absorption by a dye sensitizes the dye's own destruction or decolorization. For example, a yellow dye absorbs blue light and the excited dye thus formed reacts with an activator which releases a species to bleach the dye. Similarly, green and red lights would respectively cause the destruction of the magenta and cyan dyes. Thereafter the element may be stabilized to fix the image by destruction of the counter ion or by separation of the dye from the counter ion.
- In other non-silver imaging methods, the same ionic dye-counter ion combinations act as photoinitiators for free-radical addition polymerizable compositions.
- Such imaging dyes are normally ionic dyes (that is a dye with a positive or negative charge) associated with an appropriate counter ion as described in British Patent Application No. 84 301 156. Particularly, a dye⁻-iodonium⁺ combination has been described in EP patent applications Nos. 120,601 and 175,504 and dye⁺-borate⁻ combination has been described in US patent No.4,307,182. European Patent Application No. 223,587 describes analogous ionic dye-counter ion combinations in association with free-radical polymerizable compounds and color forming compounds.
- The dyes used may be of any color and any chemical class which is capable of bleaching upon exposure to radiation of selected wavelength in the presence of a counter ion.
- Generally, many photographic additives, such as the ionic dye-counter ion combinations, are hardly soluble in water and, when soluble in water-miscible organic solvents, they are incompatible with hydrophilic colloid compositions when incorporated therein through said organic solutions.
- One way of introducing hydrophobic compounds into hydrophilic colloidal binders is the so-called dispersion technique. Briefly, according to this technique, as described in US patent 2,322,027, the hydrophobic photographic additives are dissolved in water-immiscible high-boiling organic solvents (also called in the art permanent solvents, crystalloidal solvents, oil-type solvents, oil-formers and the like) and the resulting organic solution is added to an aqueous composition containing a hydrophilic colloid (gelatin) and a dispersing agent (normally including an anionic surfactant). The mixture is then passed through a homogenizing apparatus (colloidal mill) to form a dispersion of fine droplets of said organic solvent containing the hydrophobic photographic additives. In some cases it may be advantageous to facilitate the dissolution of the additives by use of an auxiliary water-immiscible low-boiling organic solvent, which is removed afterwards by evaporation, as described e.g. in US patents 2,801,170; 2,801,171 and 2,949,360. The obtained dispersion is then mixed with the hydrophilic colloid composition (gelatin silver halide emulsion or other gelatin-containing composition) which is used to form (by coating) the photographic layer.
- Organic solvents for dispersing photographic additives are well known in the art, as disclosed for example in US patents 2,322,027; 2,801,171; 2,835,579; 2,533,514; 3,554,755; 3,748,141; 3,779,765; 4,353,979; 4,430,421 and 4,430,422.
- These high-boiling water-immiscible organic solvents as well as methods to obtain a dispersion of hydrophobic compounds in hydrophilic binders have been mainly developed for use in color silver halide photography, wherein the so-called "dispersed couplers" are used to obtain color images upon development of exposed silver halide grains.
- US patent 3,860,425 refers to the above mentioned dispersion technique in which the dispersed phase is an oil such as dibutylphthalate, butyllaurate, tricresylphthalate and tricresylphosphate and the material dissolved in such dispersed oil is an oleophilic material such as a dye for silver dye bleaching process, a coupler free of water solubilizing group, an ultraviolet absorber, an antioxidant, a dye image stabilizer, or an optical brightener, the dispersion being stabilized with a non-ionic agent used in combination with an anionic agent.
- In the present invention,the imaging methods which make use of ionic dye-counter ion imaging combinations dissolved in water-immiscible oil solvents dispersed in hydrophilic media can give better results if the dispersion is made in presence of a sorbitan ester non-ionic surfactant (including a polyoxyethylene derivative thereof) having a HLB (hydrophilic-lipophilic balance) value in the range from 4 to 10 in absence of anionic surfactants.
- The present invention relates to a light-sensitive non-silver photographic element including a support base and a hydrophilic layer coated thereon including an ionic dye-counter ion imaging combination dissolved in water-immiscible organic solvent droplets. The droplets are dispersed in the hydrophilic layer in reactive association with a sorbitan ester non-ionic surfactant having a HLB value in the range from 4 to 10.
- The selection of the surfactant needed to make the oil ionic dye-counter ion dispersion and to keep it stable (free from crystallization) within the layer (including it) is critical not only to the stability of the dispersion but also to the sensitometric results obtained with such dye-ion imaging combination. The use of anionic and cationic surfactants has been found to result in poor sensitivity and high Dmin. It is believed that they disrupt the ionic dye-counter ion reactive association which is the basis of the imaging process of interest to the present invention.
- Non-ionic surfactants are believed to be particularly good aids for the ionic dye-counter ion imaging chemistry due to the fact that they do not apparently disrupt the necessary dye-activator salt. Within the class of non-ionic surfactants, it has been found that better results are obtained if the dispersion is made in the presence of a sorbitan ester non-ionic surfactant having a HLB value of 4 to 10.
- Such sorbitan ester non-ionic surfactant compounds may be a sorbitan fatty acid ester non-ionic surfactant or a polyoxyethylene sorbitan fatty acid ester non-ionic surfactant, represented by the general formula (I) :
-O--R₅
group wherein R₅ represents an aliphatic saturated or unsaturated carbon atom alyphatic chain of a fatty acid, preferably including 5 to 30 carbon atoms, such as lauric acid, myristic acid, palmitic acid, oleic acid, stearic acid, ricinoleic acid and the like, in which at least one of R₁, R₂, R₃ and R₄ represents a hydroxy group and at least one of R₁, R₂, R₃ and R₄ represents a
-O--R₅
group, and the value of w+x+y+z and the nature and size of R₅ are chosen to get a HLB value of 4 to 10. - The sorbitan fatty acid ester non-ionic surfactants are, in general, manufactured by direct reaction of sorbitol with fatty acids under the influence of heat or acidic reagents or both, during which internal ether formation as well as esterification occurs. The sorbitan fatty acid esters resulting from simultaneous internal ether formation and esterification consist of components esterified to different extents (mono-, di- and triesters) as described by F. R. Benson in Nonionic Surfactants, edited by M. J. Schick, M. Dekker Inc. New York, 1967, pages 264-266.
- The polyoxyalkylene sorbitan fatty acid ester non-ionic surfactants are, in general, manufactured by reaction of ethylene oxide with sorbitan fatty acid esters as described by F. R. Benson in Nonionic Surfactants, edited by M. J. Schick, M. Dekker Inc. New York, 1967, pages 270-272.
- The following table reports sorbitan ester non-ionic surfactants for use in the present invention:
Chemical Name w+x+y+z HLB Trade Name Sorbitan oleate 0 4.3 SPANTM 80 Sorbitan stearate 0 4.7 SPANTM 60 Sorbitan palmitate 0 6.7 SPANTM 40 Sorbitan laurate 0 8.6 SPANTM 20 Polyoxyethylene sorbitan stearate 5 9.6 TWEENTM 61 - Such non ionic surfactants are to be used in the substantial or total absence of any anionic or cationic surfactants. Sorbitan esters, such as for example Span™-20, are highly preferred as leading to thermo-stable, well resolved (<1 µm) droplet dispersion of oil in gelatin, with the imaging chemistry located in the oil as desired. Tergitol™ (e.g. TMN-10) non-ionic surfactants may be used but they give dispersions with medium to poor thermo-stability and larger droplets than attainable with sorbitan esters.
- HLB (hydrophilic-lipophilic balance) is a measure of the emulsifying efficiency of a surfactant and is related to the polarity of the molecule, the least hydrophilic surfactants having low HLB numbers, and increasing HLB numbers corresponding to increasing hydrophilic character (for a detailed definition of HLB see M.J. Schick, Surfactants Science Series, Vol. 1 Nonionic Surfactants, Chapter 18, M. Dekker Inc. (New York), 1967).
- Sorbitan esters (SPAN™) and polyoxyethylene sorbitan esters (TWEEN™) can be used in conjunction, taking care that the average of the two HLB values remains between 4 to 10.
- The ionic dyes used may be either anionic and cationic, depending on the polarity of the active counter ion.
- A preferred embodiment of the invention involves an anionic dye in reactive association with a positively charged counter ion, such as for example an iodonium⁺ counter ion.
- Particularly useful anionic dyes for use in this invention are oxonol dyes of the general formula (II):
-
- As already said, a particular useful counter ion to be associated with a negatively charged dye is an iodonium⁺ counter ion of an iodonium salt. The iodonium salts that may be used in the imaging system are compounds consisting of a cation wherein a positively charged iodine atom bears two covalently bonded carbon atoms, and any anion. Preferably the acid from which the anion is derived has a pKa <5. The preferred compounds, as described in European patent application No.120,601, are diaryl, aryl/heteroaryl or diheteroaryl iodonium salts in which the carbon-iodine bonds are from aryl or heteroaryl groups. Aliphatic iodonium salts are not normally thermally stable at temperature above 0°C. However, stabilised alkyl phenyl iodonium salts such as those disclosed in Chem.Lett. 1982, 65-6 are stable at room temperature and may be used.
- Suitable iodonium salts may be represented by the formula (III):
- Z⁻ represents an anion (such as, for example, Cl⁻, I⁻, Br⁻, perfluoro(4-ethylcyclohexane)sulfonate, sulfate, methyl sulfate, methanesulfonate) which may be incorporated into Ar¹ or Ar².
- Preferably, Ar¹ and Ar² do not have more than two substituents at the α-positions of the aryl groups. More preferably, Ar¹ and Ar² are both phenyl groups containing no α substituents, such as in iodonium salts represented by the formula (IV):
-
-
-
- The dye/iodonium system has its greatest sensitivity at the lambdamax of the longest wavelenght absorbance peak. Generally, it is necessary to irradiate the system with radiation of wavelenght in the vicinity of this lambdamax for bleaching to occur. Thus, a combination of coloured dyes may be used, e.g. yellow, magenta and cyan, in the same or different layers in an element and these can be selectively bleached by appropriate visible radiation to form a full color image. Monochromatic or polychromatic images may be produced by using the photosensitive materials with relatively short exposure times in daylight or sunlight or even artificial sources of light (e.g. fluorescent lamps or laser beam). The exposure time, for adequate results, for example when using an 0.5 kW tungsten lamp at a distance of 0.7 m, may be between 1 second to 10 minutes. In general, the weight ratio of bleachable dye to iodonium salt in the element is in the range from 1:1 to 1:50, preferably in the range from 1:2 to 1:10.
- A preferred composition of the dye iodonium ion bleaching reaction is the combination of an oxonol dye anion with the activator iodonium cation to form an organic salt which is highly soluble in oils, such as di-butyl phthalate, di-butyl lauramide. The close reactive association of the sensitizing dye with the iodonium moiety ensures easy electron transfer from the dye to the iodonium moiety, as desired.
- Another embodiment of the present invention comprises a cationic dye in reactive association with a negatively charged counter ion. In fact, as described in US patent No. 4,307,182, dye bleaching systems can give good results by using positively charged dyes in reactive association with a negatively charge counter-ion, such as a borate⁻ counter ion.
- The cationic dye to be used in reactive association with the borate⁻ counter ion may be of any color and any chemical class. The dyes, of course, should not contain groups which would fix or desensitize the borate salts (e.g. carboxylic acid groups, sulfonic acid groups and readily reducible metal cations such as metal cations at least as readily reducible as ferric ion).
- When the ionic dye is a cationic dye, the bleachable dyes may be selected from a wide range of known classes of dyes including methine, cyanine, carbocyanine, azomethine, styryl, xanthene, azine or rhodamine dyes.
- Particularly useful cationic dyes are cyanine dyes of the general formula (VII):
- R₁₇ and R₁₈ can be the same or different and represent alkyl groups, aryl groups, alkenyl groups or aralkyl groups, with or without substituents (e.g. carboxymethyl, 2-hydroxyethyl, 3-sulfopropyl, 3-sulfobutyl, 4-sulfobutyl, 2-methoxyethyl, 2-sulfatoethyl, 3-thiasulfatoethyl, 2-phosphonoethyl, chlorophenyl and bromophenyl) having 1 to 10 carbon atoms.
- R₁₉, R₂₀ and R₂₁ each represents hydrogen, low alkyl groups (containing 1 to 5 carbon atoms), aryl groups (such as phenyl groups), saturated and unsaturated heterocyclic groups (such as pyridine and pyrroline groups) or alicyclic groups having 5 or 6 carbon atoms (such as cyclopentane and cyclohexane) or atoms chosen within carbon, hydrogen, nitrogen, oxygen and sulfur to form (when taken together) a simple (including 5 or 6 atoms) or condensed (including 9 or 10 atoms) aromatic or heterocyclic or alicyclic nucleus (such as phenyl, piridyl, naphthalene groups).
- The substituents R₁₃, R₁₄, R₁₅, R₁₆, R₁₇, R₁₈, R₁₉, R₂₀ and R₂₁ are to give dyes useful to the present invention, as known in the art, preferably having no more than 40 atoms.
- X⁻ represents an anion (such as, for example, Cl⁻, I⁻, Br⁻, perfluoro(4-ethylcyclohexane)sulfonate, sulfate, methyl sulfate, methanesulfonate).
- This class of dyes is very well known particularly in the silver halide photographic art and are the subject of numerous patents. General references to these dyes include "The Chemistry of Synthetic Dyes", K.Venkataraman ed., Academic Press,Vol.4 (1971) and "The Theory of the Photographic Process",T.H. James,ed.,MacMillan, Editions 3 and 4.
-
- As already said, particular useful counter ion to be associated with the positively charged dye is a borate⁻ counter ion of a borate salt. Preferably, the borate salts that may be used in the imaging system are the tetra(aliphatic)borates, as described in US 4,307,182, wherein all of the carbon-to-boron bonds are from aliphatic groups.
- Examples of borate salts include:
(C₂H₅)₄N⁺ (C₄H₉)₄B⁻ (Borate salt 1) (C₂H₅)₄N⁺ (C₄H₉)₃(C₆H₅)B⁻ (Borate salt 2) (C₂H₅)₄N⁺ (C₄H₉)(C₆H₅)₃B⁻ (Borate salt 3) Na⁺ (C₆H₅)₄B⁻ (Borate salt 4) (C₂H₅)₄N⁺ (C₄H₉)₃(CN)B⁻ (Borate salt 5) (C₂H₅)₄N⁺ (COCH₃)₄B⁻ (Borate salt 6) (C₂H₅)₄N⁺ (C₄H₉)₃(CH=CH₂)B⁻ (Borate salt 7) (C₂H₅)₄N⁺ (C₄H₉)₃(CH₂-C₆H₅)B⁻ (Borate salt 8) (C₂H₅)₄N⁺ (C₄H₉)₃(C≡CCH₃)B⁻ (Borate salt 9) - Imaging in the light sensitive dye/borate system is affected by irradiation. The radiation which is absorbed by the dye/borate system causes the dye to bleach. A positive image is then produced. The use of cationic dyes is believed to spectrally sensitize the borates to radiation absorbed by the dyes associated with the borate. These are not used as sensitizing dyes as used in photographic imaging systems (usually in ratios of 1/500 or 1/10000 of dye to light sensitive agents). These dyes are used in proportion of at least 1/10 to about 1/1 in ratio to the borate. Because the dye-borate system is molecularly spectrally sensitive, a multiplicity of colored dyes may be used (e.g. cyan, magenta and yellow) in the same or different layers.
- "Reactive association", as used herein, is defined as such physical proximity between the compounds as to enable a chemical reaction to take place between them upon exposure to light.
- By a suitable selection of dye, an element may be prepared which is sensitive to radiation of a selected wavelength band within useful ranges, such as 300 to 1100 nm, the particular wavelength and the width of the band depending upon the absorption characteristics of the dye. In general, where a dye has more than one absorption peak it is the wavelength corresponding to the longest wavelength peak at which one would choose to irradiate the element.
- Elements intended for the production of images from radiation in the visible region (400 to 700 nm) will contain dyes which will bleach from a colored to a substantially colorless or very pale state. In practice, such bleachable dyes will undergo a change such that the transmission optical density at the lambdamax will drop from 1.0 or more to less than 0.09, preferably to less than 0.05. The dyes will generally be coated on the support to provide an optical density of about 3.0 or more.
- In the case of elements sensitive to ultraviolet radiation (300 to 400 nm), the dyes will not normally be colored to the eye and there may be no visible change upon exposure to ultraviolet and bleaching. The image-wise exposed elements may be used as masks for further ultraviolet exposure after fixing.
- Infrared sensitive elements contain dyes having an absorption peak in the wavelength range 700 to 1100 nm. These dyes may also have absorption peaks in the visible region before and/or after bleaching. Thus as well as providing a mean for obtaining masks for subsequent infrared exposure in a similar manner to the ultraviolet masks, infrared sensitive elements may record a visible image upon image-wise exposure to infrared radiation.
- The present invention also relates to a coating composition for the manufacture of a light sensitive non-silver photographic element which includes an ionic dye-counter ion imaging composition dissolved in a water immiscible organic solvent dispersed therein in the form of droplets associated with a non-ionic sorbitan ester surfactant compound having a HLB value of 4 to 10.
- In another aspect, the present invention relates to a process for the manufacturing of a light sensitive non-silver photographic element which includes coating on a support base a composition substantially consisting of a hydrophilic binder having dispersed therein droplets of a water immiscible organic solvent including dissolved therein an ionic dye-counter ion imaging composition in the presence of a sorbitan ester surfactant compound having a HLB value of 4 to 10.
- Typically, the process of incorporating hydrophobic additives, such as hydrophobic dye-counter ion combination agents, into hydrophilic colloid components layers of photographic materials (such as light sensitive layers, protective layers, intermediate layers and the like), consists of incorporating into hydrophilic colloid coating compositions of said layers the hydrophobic additives themselves in the form of a dispersion of fine droplets consisting of a water-immiscible high boiling organic solvent in which said hydrophobic additives have been dissolved.
- Generally, according to said dispersion technique, the hydrophobic photographic additives are dissolved in water-immiscible high boiling organic solvents (also called in the art permanent solvents, crystalloidal solvents, oil solvents, oil-formers and the like) and the resulting organic solution is added to an aqueous composition containing the hydrophilic colloid (gelatin) and a dispersing agent (surfactant). The mixture is then passed through a homogeneizing apparatus (colloidal mill) to form a dispersion of fine droplets of said organic solvent comprising the hydrophobic photographic additives. The obtained dispersion is then mixed with the hydrophilic colloid composition (light sensitive gelatin composition or other gelatin composition) which is used to form (by coating) the photographic layer. The obtained photographic layer includes the additive dispersed therein.
- Organic solvents for dispersing hydrophobic compounds are desired to meet several requirements. They have to possess an excellent dissolving power towards said additives, to keep the fine droplets stably dispersed, to have a refractive index which is as close as possible to that of the hydrophilic colloid wherein they are dispersed, and not to deteriorate the physical properties of the layers wherein they are incorporated. Moreover, said organic solvents have to not negatively affect the photographic properties of the materials wherein they are used to disperse photographic additives. Organic solvents may be selected from esters of carboxylic acid, phosphate esters, carboxyl amides, ethers and substituted hydrocarbons. Specific examples are di-n-butyl phthalate, 2(ethyl-hexyl)phthalate, di-octyl phthalate, diisodecyl phthalate, di-(methoxyethyl) phthalate, N-N-diethyl lauramide, di-butyl lauramide, butyl acetanilide, tricresyl phosphate, tributyl phosphate, tri (butoxy-ethyl) phosphate, di-butyl sebacate, di-octyl sebacate, etc.
- The amounts of high boiling solvents used according to this invention for dispersing hydrophobic additives can vary according to the used additive. It is, however, undesiderable to use large amounts of such solvents, because large excess of solvents may sometimes deteriorate the physical properties of the photographic layers. Accordingly, it is normal practice to use the high boiling solvents in a weight ratio to each additive in the range 01 to 8.0, preferably in the range 0.3 to 3.0.
- A low-boiling solvent or water-soluble high-boiling solvent is sometimes advantageously used along with the water-insoluble high-boiling solvent as mentioned above for dissolving the ionic dye-counter ion combination, e.g., propylene carbonate, ethyl acetate, butyl acetate, ethyl propionate, sec-butyl alcohol, tetrahydro-furan, cyclohexanone, dimethylformamide, diethylsulphoxide and 2-methoxy ethanol. Auxiliary low boiling organic solvents are for example described in U.S. patents Nos. 2,801,170; 2,801,171; 2,835,579 and 2,949,360.
- The bleachable dye and counter ion salt may be applied to the support in a binder. Suitable binders are transparent or translucent, are generally colourless and include natural polymers, synthetic resins, polymers and copolymers, and other film forming media. The binders may range from thermoplastic to highly cross-linked, and may be coated from aqueous or organic solvents or emulsions.
- Gelatin is the preferred hydrophilic colloid for use in the present invention. However, other water-soluble colloidal substances or mixture thereof can also be used. Exemplary hydrophilic colloidal substances include gelatine derivatives, such as phthalated gelatin and acetylated gelatine, cellulose derivatives, such as carboxymethyl cellulose, starch, casein, zein, synthetic hydrophilic colloids such as polyvinyl alcohol, polyvinyl pyrrolidone, copolymers of acrylic acid esters, acrylonitrile and acrylamides, etc.
- The amount of gelatin used in practice depends on the dispersing solvent amount and the coating thickness required. It is advantageously used in the amount of 2.5 to 5% by weight of whole dispersion.
- Suitable supports include transparent film, e.g. polyester, paper e.g. baryta-coated photographic paper, and metallised film. Opaque vesicular polyester films are also useful.
- The following stock emulsion was prepared.
- Yellow dyes represented by the formulas (1) and (4) (2.0 g and 1.6 g) were dissolved in a mixture of 24 ml of DEL (diethyl lauramide), 4 ml of dimethyl formamide (DMF) and ethanol (30 ml) at 50°C. To this solution, in red light, was added the iodonium salt (9) (5.2 g). The resulting solution was dropwise added to 200 ml of 10% aqueous gelatin while stirring with a high speed rotating mixer to effect dispersion. The dispersion was continued for 5 minutes, after which time 136 ml water was added and dispersion maintained for 3 minutes. This stock emulsion is used immediately, because although initially the emulsion is well formed with <0.1 µm droplets, it is not stable after 12 hours at room temperature. Separation of the oil is observed.
- A 100 ml aliquot of above stock solution was placed at 40°C for 24 hours and its oil/gelatin dispersion stability monitored by optical observation of the droplets between glass plates.
- The emulsion was found to separate large oil drops after 24 hours.
- The emulsion was conventionally coated onto subbed polyester and dried for 1 hour at 40°C in the dark. The resulting yellow coating was analysed by monitoring the sensitivity of the yellow dye bleach at 460 nm. The time taken to bleach the dye by Dmax-1 speed point by known amount of light at 460 nm was obtained. There was no unbleached dye, i.e. Dmin = 0.05.
- As above, but adding 7 ml of 10% aqueous anionic Hostapur™ surfactant to 100 ml of the stock dispersion. The stability was monitored for 24 hours/40°C. A sample of the obtained coated film was analyzed as above for sensitivity and Dmin.
- As in case b), but using non-ionic Tergitol™ TMN-4 surfactant (10%aqueous, 7 ml).
- As in case b), but using non-ionic Tergitol™ TMN-10 surfactant (10%aqueous, 7 ml).
- The stock dispersion is completely destroyed with considerable oil separation.
- As in case b), but using SpanTm 20, 0.2 g for 100 ml dispersion.
- The results of the test are shown in the following table 2:
Dispersion Stability 24 hrs/40°C Time (Secs) (Dmax-1) Unbleached dye (Dmin) Case a) Oil Separation 25 0.05 Case b) Good stability 40 0.39 Case c) Good stability 30 0.10 Case d) Considerable oil separation -- - Case e) Good stability 23 0.10 - As we can see in table 2, the best dispersion stability, high speed and low Dmin is achieved in the case e), corresponding to the use of the non-ionic Span™ 20 type surfactant.
- The Hostapur™ surfactant of case b) is an anionic surfactant. It gives a good stability but the values of Dmax and Dmin obtained by the use of such a type of surfactant are worse than the values obtained without the use of any surfactants.
- The Tergitol™ TMN-4 and Tergitol™ TMN-10 surfactants of, respectively, cases c) and d) are non-ionic surfactants. By the use of Tergitol™ TMN-4 a good stability is obtained and the values of Dmax and Dmin are better than the values obtained in case b) (by the use of an anionic surfactant).
- 1.3 g of the iodonium salt (9) was added under diminuished red light to a solution obtained by heating to 56°C ± 2° of 0.5 g of yellow dye (10) and 0.4 g of yellow dye (4), 6 ml of DEL, 1 ml of DMF, 7 ml of ethanol and 0.2 g of Sorbitan monolaurate.
- The resulting solution was added to 50 ml of an aqueous solution kept at 45°C and containing 5 g of gelatine. The resulting mixture was stirred for 5 minutes in a high speed rotary mixer to effect dispersion.
- To the whole dispersion thus formed was added 33.91 ml of water; this was stirred for an additional 3 minutes, then observed by means of an optical microscope. This is a process for producing a unique combination of organic solvent (DEL) and non-ionic surfactant, without any anionic surfactant, permitting the formation of thermostable, well resolved oil-in-gelatin dispersion.
The dispersion was stable and it was observed that no agglomeration of the particles, growth of the particles or crystallisation occurred. - To a solution obtained by heating a mixture of 0.5 g of magenta oxonol dye (6), 6 ml of DEL, 1 ml of DMF, 7 ml of ethanol and 0.2 g of Span™ 20, was added under diminuished red light 0.6 g of the iodonium salt (9).The resulting solution was added to 85 ml of an aqueous solution kept at 45°C and containing 5 g of gelatin, and the resulting mixture was treated for 5 minutes by means of 20 kHz electromagnetic ultrasonic generator (Sonifer™ Mod. B-12 of Branson Co.). The dispersion showed good drop size distribution curve (DSDC) and an excellent thermostability; no crystals were observed.
- 0.5 g of the oxonol salt of formula (3) was dissolved by heating in a mixture of 6 ml of DEL, 1 ml of DMF, 7 ml ethanol and 0.2 of non-ionic surfactant (Span™ 20). Under a diminuished yellow-green light, 0.6g of iodonium salt (9) was added and the resulting solution was stirred by Silverson into 50 ml of 10% aqueous gelatin kept at 45°C.
- After homogenising for 10 minutes, additional 35 ml of water was poured in and subjected to Siverson homogenisation for a further 2 minutes. The whole dispersion was thus prepared, showed good DSDC and stability without any tendency to crystallise.
Claims (12)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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IT20523/88A IT1224317B (en) | 1988-05-10 | 1988-05-10 | LIGHT-SENSITIVE PHOTOGRAPHIC ELEMENT NOT BASED ON SILVER AND PROCEDURE TO INCORPORATE HYDROPHOBIC COMPOSITIONS HYDROPHILE COLLOIDAL COMPOSITIONS |
IT2052388 | 1988-05-10 |
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EP0345444A1 true EP0345444A1 (en) | 1989-12-13 |
EP0345444B1 EP0345444B1 (en) | 1994-06-22 |
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EP89107013A Expired - Lifetime EP0345444B1 (en) | 1988-05-10 | 1989-04-19 | Light-sensitive non-silver photographic element and process for incorporating hydrophobic compositions into hydrophilic colloid compositions |
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EP (1) | EP0345444B1 (en) |
JP (1) | JPH0216540A (en) |
DE (1) | DE68916325T2 (en) |
IT (1) | IT1224317B (en) |
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US5387498A (en) * | 1991-10-14 | 1995-02-07 | Minnesota Mining And Manufacturing Company | Positive-acting photothermographic materials comprising a photo-acid generator |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3676141A (en) * | 1968-08-22 | 1972-07-11 | Fuji Photo Film Co Ltd | Process for the preparation of color-photographic sensitive materials using nonionic and anionic surface active agents |
US3860425A (en) * | 1971-08-25 | 1975-01-14 | Fuji Photo Film Co Ltd | Dispersion containing nonionic surface acting agent with units of polyoxyethylene and polyoxypropylene |
GB1460894A (en) * | 1973-03-19 | 1977-01-06 | Agfa Gevaert | Method of incorporating photographic ingredients into hydrophilic colloids |
EP0109773A2 (en) * | 1982-10-25 | 1984-05-30 | Minnesota Mining And Manufacturing Company | Dispersed imaging systems with tetra(hydrocarbyl) borate salts |
-
1988
- 1988-05-10 IT IT20523/88A patent/IT1224317B/en active
-
1989
- 1989-04-19 DE DE68916325T patent/DE68916325T2/en not_active Expired - Fee Related
- 1989-04-19 EP EP89107013A patent/EP0345444B1/en not_active Expired - Lifetime
- 1989-05-09 JP JP1115929A patent/JPH0216540A/en active Pending
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3676141A (en) * | 1968-08-22 | 1972-07-11 | Fuji Photo Film Co Ltd | Process for the preparation of color-photographic sensitive materials using nonionic and anionic surface active agents |
US3860425A (en) * | 1971-08-25 | 1975-01-14 | Fuji Photo Film Co Ltd | Dispersion containing nonionic surface acting agent with units of polyoxyethylene and polyoxypropylene |
GB1460894A (en) * | 1973-03-19 | 1977-01-06 | Agfa Gevaert | Method of incorporating photographic ingredients into hydrophilic colloids |
EP0109773A2 (en) * | 1982-10-25 | 1984-05-30 | Minnesota Mining And Manufacturing Company | Dispersed imaging systems with tetra(hydrocarbyl) borate salts |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5387498A (en) * | 1991-10-14 | 1995-02-07 | Minnesota Mining And Manufacturing Company | Positive-acting photothermographic materials comprising a photo-acid generator |
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IT1224317B (en) | 1990-10-04 |
IT8820523A0 (en) | 1988-05-10 |
JPH0216540A (en) | 1990-01-19 |
DE68916325D1 (en) | 1994-07-28 |
EP0345444B1 (en) | 1994-06-22 |
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