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
  • G03C1/76—Photosensitive materials characterised by the base or auxiliary layers
  • G03C1/825—Photosensitive materials characterised by the base or auxiliary layers characterised by antireflection means or visible-light filtering means, e.g. antihalation
  • G03C1/83—Organic dyestuffs therefor
  • G03C1/832—Methine or polymethine dyes
• • 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
  • G03C1/494—Silver salt compositions other than silver halide emulsions; Photothermographic systems ; Thermographic systems using noble metal compounds
  • G03C1/498—Photothermographic systems, e.g. dry silver
  • G03C1/49836—Additives
  • G03C1/49845—Active additives, e.g. toners, stabilisers, sensitisers
  • G03C1/49854—Dyes or precursors of dyes

Definitions

• This invention relates to a photographic element incorporating an antihalation or acutance dye.
• Light sensitive recording materials may suffer from a phenomenon known as halation which causes degradation in the quality of the recorded image. Such degradation may occur when a fraction of the imaging light which strikes the photosensitive layer is not absorbed but passes through to the film base on which the photosensitive layer is coated. A portion of the light reaching the base may be reflected back to strike the photosensitive layer from the underside. Light thus reflected may, in some cases, contribute significantly to the total exposure of the photosensitive layer. Any particular matter in the photosensitive element may cause light passing through the element to be scattered. Scattered light which is reflected from the film base will, on its second passage through the photosensitive layer, cause exposure over an area adjacent to the point of intended exposure. It is this effect which leads to image degradation.
• Silver halide based photographic materials are prone to this form of image degradation since the photosensitive layers contain light scattering particles.
• the effect of light scatter on image quality is well documented and is described, for example, in T. H. James "The Theory of the Photographic Process", 4th Edition, Chapter 20, Macmillan 1977.
• a light absorbing layer within the photographic element. To be effective the absorption of this layer must be at the same wavelengths as the sensitivity of the photosensitive layer.
• a light absorbing layer is frequently coated on the reverse side of the base from the photosensitive layer. Such a coating, known as an "antihalation layer", effectively prevents reflection of any light which has passed through the photosensitive layer.
• a similar effect may be achieved by a light absorbing layer interposed between the photosensitive layer and the base.
• This construction described as an "antihalation underlayer” is applicable to photosensitive coatings on transparent or non-transparent bases.
• a light absorbing substance may be incorporated into the photosensitive layer itself, in order to absorb scattered light. Substances used for this purpose are known as "acutance dyes". It is also possible to improve image quality by coating a light absorbing layer above the photosensitive layer of a wet processed photographic element. Coatings of this kind, described in U.S. Patent Specification No. 4,312,941 prevent multiple reflections of scattered light between the internal surfaces of a photographic element.
• Triarylmethane and oxonol dyes in particular, are used extensively in this connection. There is, however, a need for antihalation and acutance dyes which absorb in the near infrared region of the spectrum. Dyes of this type are required for recording materials which are spectrally sensitized to near infrared wavelengths, for example, materials which are designed to record the output of near infrared lasers. Coatings of infrared absorbing pigments such as carbon black may be used. However, the use of this material is objectionable since it does not decolorise during processing and must therefore be coated in a binder which dissolves in developing solution allowing the carbon black to wash off causing objectionable contamination of the developer.
• Coatings of antihalation or acutance dyes which absorb in the visible region of the spectrum are required to become colorless during processing of the photographic material, either by washing out or chemical reaction in wet processing techniques or thermal bleaching during heat processing techniques.
• Cyanine dyes are well known in the photographic art and are extensively used as spectral sensitizers for silver halide based materials. Cyanine dyes are not usually used or considered suitable for antihalation or acutance purposes owing to their limited solubility in aqueous media and especially to their inability to decolorise completely during photographic processing when present in large quantities.
• R1 and R2 independently represent an alkyl, substituted alkyl, alkenyl, substituted alkenyl or aralkyl group of up to 20 carbon atoms
• R3 and R4 independently represent a hydrogen atom or an alkyl, substituted alkyl, alkenyl or substituted alkenyl group of up to 10 carbon atoms
• R5, R6, R7 and R8, which together may not contain more than 12 carbon atoms independently represent a hydrogen atom, an alkyl, substituted alkyl, alkenyl, substituted alkenyl, aryl or alkaryl group, or one of R5 and R6 together with one of R7 and R8 represent the necessary atoms to complete a carbocyclic ring (e.g. a benzene ring) in which case the others of R5 to R8 are absent,
• Q1 and Q2 together represent the non-metallic atomsnecessary to complete an acidic nucleus of the type present in oxonol or merocyanine dyes.
• the heterocyclic nuclei formed by Z1 and Z2 may be any of the wide range of nuclei known in the cyanine dye art. Generally, Z1 and Z2 each represent the non-metallic atoms necessary to complete a heterocyclic nucleus containing 5 to 6 atoms in the heterocyclic ring, the nucleus optionally possessing substituents.
• the heterocyclic ring is composed of ring atoms selected form C, N, O, S and Se. Examples of such heterocyclic nuclei include: the thiazole series, e.g.
• thiazole 4-methylthiazole, 4-phenylthiazole, 5-methylthiazole, 5-phenylthiazole, 4,5-dimethylthiazole, 4,5-diphenylthiazole, 4-(2-thienyl)-thiazole, the benzothiazole series, e.g.
• naphtho[1,2]-thiazole naphtho[2,1]thiazole, 5-methoxynaphtho-[2,1]-thiazole, 5-ethoxynaphtho[2,1]thiazole, 8-methoxynaphtho[1,2]thiazole, 7-methoxynaphtho[1,2]thiazole, the thianaphtheno-7′,6′,4,5-thiazole series, e.g. 4′-methoxythianaphtheno-7′,6′,4,5,-thiazole, the oxazole series, e.g.
• quinoline 3-methylquinoline, 5-methylquinoline, 7-methylquinoline, 8-methylquinoline, 6-chloroquinoline, 8-chloroquinoline, 6-methoxy-quinoline, 6-ethoxyquinoline, 6-hydroxyquinoline, 8-hydroquinoline, the 4-quinoline series, e.g. quinoline, 6-methoxyquinoline, 7-methylquinoline, 8-methylquinoline, the 1-isoquinoline series, e.g. isoquinoline, 3,4-dihydroisoquinoline, the 3-isoquinoline series, e.g. isoquinoline, the benzimidazole series, e.g.
• Z1 and/or Z2 complete a benzothiazole nucleus or a 3,3-dialkylindolenine nucleus.
• the groups R1 and R2 contain less than 8 carbon atoms. More preferably R1 and R2 are lower alkyl groups containing up to 4 carbon atoms.
• the alkyl groups may contain any substituent which does not deleteriously effect the properties of the dye as known in the cyanine art. Suitable substituted alkyl groups include alkoxy-alkyl, benzyl and carboxy-alkyl.
• R3 and R4 represent a hydrogen atom or a lower alkyl group containing 1 to 4 carbon atoms.
• R5 to R8 are hydrogen.
• certain substituted cyclopentanones are commercially available which may be used as intermediates in the preparation of the dyes of formula (I), e.g. 3-methyl-cyclopentanone and 3-phenylcyclopentanone and accordingly one of R5 to R8 may readily represent these substituents.
• the cyclic acid nuclei completed by the groups Q1 and Q2 preferably have the ring atoms selected from C, S, N, O and Se.
• Suitable moieties are derived from the following nuclei which may additionally possess substituents: 1,3-indandione, pyrazolone, isoxazolone, e.g.
• a preferred cyclic nucleus completed by Q1 and Q2 has the general formula: in which: R9 and R10 independently represent a hydrogen atom, an alkyl or cycloalkyl gruop which may be substituted, e.g. hydroxyalkyl, alkoxy-alkyl, alkoxycarbonyl, polyoxyalkyl; alkenyl or substituted alkenyl, an aryl group which may be substituted, or an aralkyl group, any of which groups may contain up to 25 carbon atoms.
• R9 and R10 together contain at least 8 carbon atoms and are aliphatic groups, more preferably at least one of R9 and R10 ⁇ represents an alkyl group containing at least 8 carbon atoms.
• the dyes of formula (I) absorb in the near infrared having a very low visible absorption whilst retaining a high extinction coefficient at the absorption maximum.
• the dyes of the invention have extinction coefficients at their maximum absorption wavelength (typically 800 nm or higher) of the order of 2.5 x 105 to 3.0 x 105. However, at 700 nm the absorption has generally fallen to approximately 10% of this value and at 650 nm the absorption is down to approximately 2% of the value, as measured in methanolic solution.
• the dyes may be incorporated into wet processed photographic or photothermographic elements as actuance dyes according to conventional techniques.
• the dyes may also be incorporated into antihalation layers according to techniques of the prior art, for example, in the case of wet processed photographic elements, as an antihalation backing layer, an antihalation underlayer or as an overcoat. It is also anticipated that similar nonamethine dyes would be suitable for use as actuance and antihalation dyes.
• the present invention describes the preparation and use of water soluble, holopolar dyes as a non-stining antihalation system for near infrared recording media.
• Dyes similar to formula (I) are known without the ring, water solubilizing groups.
• a class of dyes is disclosed in U.S. Patent Specification No. 2,955,939 for the sensitization of silver halide emulsions and in U.S. Patent 4,581,325 for use as antihalation dyes.
• U.S. Patent 3,194,805 discloses a class of merocyanine and holopolar dyes containing arylene-chain substitution and their use as spectral sensitizing dyes.
• the quantity of sensitising dye used in the emulsions disclosed in U.S. Patent Specification No. 2,955,939 is in the general range 5 to 100, usually 10 to 20 mg per liter of emulsion whereas for acutance purposes in accordance with the invention the dyes would generally be used in the range 200 to 1000 mg per liter of emulsion.
• U.S. 2,955,939 - holopolar dyes as sensitizers Cover tri, penta and heptamethine dyes in examples. Examples cover different middle rings such as barbituric acid, 2-thiobarbaturic, rhodanine, thianaphthenone-1,1-­dioxide, isoxazolone, and pyrazolone.
• Table I contains the dyes of formula (I) which have been prepared and also other classes of dyes for comparison. Also included are references for the preparation of these compounds. The structures of the dyes are listed below.
• 2-methylbenzthiazole 60 g, 0.4 mole was placed in a 250 ml round bottom flask fitted with a stirring bar, thermometer, condenser, and heating mantle. While stirring, 100 ml of concentrated sulfuric acid was added with subsequent temperature rise to 80°C. Oleum (80 ml, 30%) was added over a two minute period with the temperature rising to 115°C and formation of a dark solution. Ferric chloride (0.3 g) was added to the reaction heated to 200°C for one hour. The reaction was cooled to 50°C and poured into 6 liters of cool (10°C) acetone with good stirring. The resulting slurry was stirred for 15 minutes.
• the sodium salt of 2-methyl-6-sulfobenzthiazole (40 g, 0.159 mole) was placed in a 500 ml flask equipped with a mechanical stirrer, thermometer, condenser, and a heating mantle.
• Ethyl-p-toluenesulfonate (169 g, 0.845 mole) and 7 ml of dimethylformamide were added with stirring and the mixture was heated to 175°C for three hours.
• 2,6-dimethyl-4-heptanone (25 ml) was added to aid stirring, and the mass was cooled to 60°C.
• the thick fluid was poured into 250 ml of well stirred acetone to precipitate the product. The slurry was cooled, filtered and dried at 80°C for two hours. Recovered 61.5 g; an 85.6% yield.
• the sodium salt of 2-methyl-3-ethyl-6-sulfobenzthiazolium tosylate (4.51 g, 0.01 mole), and 5-(2-5-dianilinomethylenecyclo­pentylidene)-1,3-dimethylbarbituric acid (1.98 g, 0.005 mole), 20 ml of dimethylformamide, and 3 ml of triethylamine were mixed together in a 100 ml flask fitted with a thermometer, stirrer, reflux condenser and oil bath. The mixture was heated to 100°C with stirring for 5 minutes. The reaction mixture was poured into 200 ml of hexane with vigorous stirring.
• Evaluation of the dyes was performed by coating an antihalation backing layer containing the dyes on 7 mil polyester base. Each dye was dissolved in water and added to an aqueous solution of gelatin at 40°C. A surfactant and formaldehyde (4.3 ml, 4%) were also added. THe final solution was at 5% gelatin. The dye-gelatin mixture was coated at 65 ml/m2 onto subbed polyester base and dried. The characteristics of the AH coatings are reported in Table II.
• the results listed in Table II show that the water soluble holopolar dyes (Ex. 1-4) offer particular advantages over water soluble cyanine dyes (A-D).
• the water soluble cyanine dye E does give a strong near infrared absorbing coating but has the drawback of high stain after automatic processing.
• the cyanine dyes, A-D had strong maximum absorbance from 760-810 nm in methanol. However, when these dyes were added to water and coated as a gelatin solution, the absorbance curves shifted to lower wavelengths.
• An emulsion was prepared by a double jet precipitation having 64% chloride and 36% bromide with an average grain size of 0.24 micrometers.
• the emulsion was digested with p-toluenesulfinic acid, sodium thiosulfate and sodium gold tetrachloride (NaAuCl4).
• Final preparation of the emulsions comprised the addition of water and gelatin to a level of 5.0% gelatin and 2500 g of emulsion per mole of silver.
• the pH was adjusted to 7.0, and the pAg was adjusted to 7.2.
• Infrared sensitizing dye (F) was added in methanol at 30 mg/mole Ag.
• Phenyl-5-mercaptotetrazole in methanol (115 mg/mole Ag), poly(ethylacrylate) (30 g/mole Ag), formaldehyde hardener and surfactant were also added before coating.
• the material was coated at 2.4 g Ag/m2.
• the emulsion was coated on

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• 1989
  • 1989-02-17 JP JP3812889A patent/JPH025041A/ja active Pending
  • 1989-02-20 EP EP89301637A patent/EP0329491A3/de not_active Withdrawn

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