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
  • G03C7/00—Multicolour photographic processes or agents therefor; Regeneration of such processing agents; Photosensitive materials for multicolour processes
  • G03C7/28—Silver dye bleach processes; Materials therefor; Preparing or processing such materials

Definitions

• Photographic elements useful in the silver dye bleach process and containing a bleachable dye in association with a silver halide emulsion are efficiently spectrally sensitized to record red light with the use Of a symmetrical thiacarbocyanine dye Whose cationic portion is free from carboxyalkyl and alkylsulfate substituent groups, and to record green light with the use of symmetrical oxacarbocyanine dye whose cationic portion is free from carboxyalkyl and alkylsulfate substituent groups.
• This invention relates to improvements in color photography.
• One aspect of this invention relates to improved spectrally-sensitized photographic elements useful in processes wherein colored bleachable dyes associated with a silver halide emulsion layer are bleached imagewise in the vicinity of a silver image.
• a multilayer element comprising silver halide layers differentially sensitized to blue, green and red radiation and having in association therewith, respectively, bleachable yellow, magenta and cyan colored dyes.
• these elements may be developed in a black-and-white silver halide developer solution to form low contrast silver images in the exposed layers.
• the element is subjected to one or more acidic bleaching solutions comprising an agent commonly referred to as a bleach catalyst.
• This bleach catalyst oxidizes the metallic silver formed during processing and in so doing is reduced.
• the reduced catalyst then acts to reduce the colored, bleachable dye to a colorless product, while at the same time the catalyst is itself oxidized back to its original state.
• the catalyst may be included in the element or in the developer rather than in the bleach bath.
• the element may then be fixed in a conventional fixing bath.
• bleach processes of this type utilize azo dyes which are reductively destroyed in the presence of the developed silver image.
• azo dyes which are reductively destroyed in the presence of the developed silver image.
• other types of dyes e.g., certain anthraquinone and triphenyl methane dyes, may be used, depending on their ability to be reductively cleaved under the bleach conditions.
• the reduction may be accomplished either by a stoichiometric reaction in acid solution with the photolytic silver acting as the reducing agent, or by the reduction of the dye by stannite or other reducing agent which is catalyzed by the silver.
• the acidic bleach solutions may contain complex formers for silver ion, e.g., thiourea, mercaptans and benzimidazoles. Processes have also been described in which the halogen ion serves as a complex former for the silver ion.
• bleachable dyes employed in association with silver halide emulson layers cause undesirable reduction in sensitivity in various ways, such as by desorbing spectral sensitizing dyes from the silver halide grains. Sensitivity of the emulsion layers is also frequently reduced because the bleachable dye is of a col r which is complementary to the light which the emulsion layer is to record. In addition, bleachable dyes cause undesirable fog in the emulsion layer, which results in undesirable bleaching of the dye in non-image areas of the record. It therefore appears highly desirable to provide improved spectral sensitization of dye bleach materials whereby improved sensitivity and reduced fog are obtained.
• silver-dye bleach elements of greatly increased sensitivity may be prepared by the 'use of certain red and green spectral sensitizers.
• Another object of my invention is to provide novel color materials which retain the inherent advantages of the silver-dye bleach processes While significantly increasing the speed of such elements. Another object of my invention is to provide novel red and green spectral sensitizing combinations for silver halide photographic layers utilized in silver-dye bleach color photography.
• dye bleach materials comprising a silver halide emulsion layer coated on a support, said layer having in association therewith a bleachable cyan dye, said emulsion being sensitized to red radiation with a symmetrical thiacarbocyanine dye whose cation is free from carboxyalkyl and alkyl sulfate groups.
• the symmetrical thiacarbocyanine dyes employed herein have at least one N-substituted sulfoalkyl group, such as sulfoethyl, sulfopropyl, sulfobutyl, e.g., 3-sulfopropyl, 3-sulfobutyl and 4-sulfobutyl; and, said dyes are free from carboxyalkyl and alkyl sulfate groups.
• Useful symmetrical thiacarbocyanine dyes of this invention include those having the following general I ia I ia X wherein Z represents the non-metallic atoms necessary to complete a cyclic nucleus such as phenyl or naphthyl, which nucleus may be substituted, for example with halogen, e.g., chlorine or bromine, or sulfoalkyl; R represents a hydrogen atom, or a hydrocarbon substituent such as lower alkyl, e.g., methyl, ethyl, propyl or butyl, or an aryl group such as phenyl; R and R each represents a-lower alkyl group, preferably of from about 1 to 4 carbon atoms, free from carboxyl and sulfate substituents, and X represents an ion, such as bromide, chloride, iodide, benzenesulfonate, methylsulfate, p-tol
• At least one of R and R represents a sulfoalkyl substituent, in which case the sulfo group is the anion.
• the symmetrical red-sensitizing thiacarbocyanine dyes provides particularly useful sensitization in silver dye bleach materials in that they unexpectedly result in decreased fog and increased speed as compared to 'prior art dye bleach elements wherein the red sensitization is provided by closely related dyes, such as unsymmetircal carbocyanine dyes, or symmetrical thiacarbocyanine dyes which contain carboxyalkyl or alkyl sulfate substituents.
• the red sensitizers of my invention are utilized in combination with a supersensitizing concentration of a non-ionized trinuclear cyanine dye of the type described in Brooker and White US. Patent 2,739,964, issued Mar. 27, 1956.
• Dyes of this type, which contain no acid anion may be represented by the general formula:
• R and R each represents an alkyl group
• Q represents the non-metallic atoms necessary to complete a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring including those of the indandione series
• A represents a member selected from the group consisting of an oxygen atom and a sulfur atom
• 11, m and d each represents a positive integer of from 1 to 2
• Z and Z each represents the non-metallic atoms necessary to complete a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring.
• dye bleach materials comprising a silver halide emulsion layer coated on a support, said layer having in association therewith a bleachable magenta dye, said emulsion being sensitized to green radiation with a symmetrical oxacarbocyanine dye Whose cation is free from carboxyalkyl and alkyl sulfate groups.
• the symmetrical oxacarbocyanine dyes employed herein have at least one N-substituted sulfoalkyl group, such as sulfoethyl, sulfopropyl, or sulfobutyl, e.g., 3-sulfopropyl, 3-su1- fobutyl and 4-sulfobutyl; and, said dyes are free from carboxy alkyl and alkyl sulfate groups.
• Useful symmetrical oxacarbocyanine dyes of this invention include those having the following formula:
• Z represents the non-metallic atoms necessary to complete a cyclic nucleus such as phenyl or naphthyl, which nucleus may be substituted, for example with halogen, e.g., chlorine, bromine or sulfoalkyl
• R represents a hydrogen atom, or a hydrocarbon s-ubstitutent such as alkyl, e.g., methyl, ethyl, propyl or butyl, or a phenyl substituent
• R and R each represents an alkyl group, preferably of from about 1 to 4 carbon atoms, free from carboxyl and sulfate substituents, and
• X represents an anion.
• At least one of R and R represents a sulfoalkyl substituents, in which case the sulfo group is the anion.
• the symmetrical green-sensitizing oxacarbocyanine dyes provide particularly useful sensitization in silver dye bleach materials in that they unexpectedly result in decreased fog and increased speed as compared to prior art dye bleach elements wherein the green sensitization is provided by closely related dyes, such as unsymmetrical carbocyanin'e dyes or symmetrical oxacarbocyanine dyes which contain carboxyalkyl or alkyl sulfate substituents.
• the green sensitizers of my invention are utilized in combination with a supersensitizing concentration of a benzimidazolocarbocyanine dye of the type described in Jones U.S. Patent 2,945,763, issued July 19, 1960.
• Dyes of this type may be represented by the following general formula:
• R and R each represents an alkyl group, such as methyl, ethyl, ,G-hydroxyethyl, n-propyl, n-butyl, [3- carboxyethyl, 'y-carboxypropyl, 4-carboxybutyl, fl-sulfoethyl, -sulfopropyl, 'y-sulfobutyl, 4-sulfobutyl, etc. (e.g., an alkyl group containing from 1 to 4 carbon atoms), R and R each represents an alkyl group, such as methyl, ethyl, n-propyl, n-butyl, etc.
• magenta dye has the following formula:
• the advantages of this invention are realized with dye bleach materials wherein a silver halide emulsion layer has in association therewith a bleachable dye.
• the bleachable dye may be in a layer contiguous to the desired emulsion layer.
• the bleachable dyes are incorporated in the emulsion layer to eliminate light scattering by the emulsion, thereby improving image sharpness and the ability to reproduce fine detail.
• the invention is applicable to any bleachable dye which tends to cause fogging and desensitization of spectrally sensitized silver halide emulsions. It is especially useful with bleachable azo dyestuffs which contain a phenolic (including naphtholic) group.
• Layer BGreen sensitive silver bromoiodide emulsion 162 mg. silver/ft magenta colored azo dye, 62 mg./ ft poly-a-methyl-allyl-N-guanidyl ketimine glycollate mordant, 157 mg./ft. 6,7 dimethyl-2,3-dipyridylquinoxaline, l0 mg./ft. gelatin, 320 mg./ft.
• CHzCHzCHCHg Coating 0' contained 200 mg. anhydro-5,5'-dichloro- 9 ethyl-3,3'-di-(4-sulfobutyl)thiacarbocyanine hydroxide per silver mole.
• Coating D* contained 200 mg. anhydro-9-ethyl-3,3'- d1-(3 sulfopropyl) 4,5,4',5' dibenzothiacarbocyanine hydroxide, sodium salt per silver mole.
• Coating E contained 200 mg. anhydro-B-ethy1-5-phenyl- 1-(4-sulfobutyl)thia-4'-carbocyanine hydroxide per silver e
• Coating G contained 200 mg. of anhydro-S-B-carboxyethyl chloro-1'-ethylthia-4'-carbocyanine hydroxide,
• RED SENSI'IIZATION MINUS BLUE EXPOSURE Black-and-white developer silver mg. lftfi] Contains dyes within the scope of my invention. Increased reversal DEF indicates lower fog.
• Example 2 Five coatings of the type represented by basic Element H were prepared.
• Coating A* contained 200 mg. of anhydro-9-ethyl-5,5'- diphenyl 3,3 di-(3 sulfobutyl)oxacarbocyanine hydroxide, m'onosodium salt, a dye within the scope of my invention, per silver mole.
• Coating B contained 200 mg. of 3,3,9-triethyl-5,5'-
• Coating C contained 200 mg. of anhydro-l-ethyl-3-(2- sulfohydroxypropyl)thia-2'-cyaniue hydroxide per silver mole.
• Coating D contained 200 mg. of anhydro-l-ethyl-3-(3- sulfohydroxypropyl)thia-2'-cyanine hydroxide per silver
• crncmomosoio Coating E contained 200 mg. of anhydro-l'-ethyl-3(3- sulfobutyl)thia-2'-cyanine hydroxide per silver mole.
• Example 3 Three additional coatings of the type represented by basic Element II were prepared.
• Coating A was identical to Coating A of Example II.
• Coating B contained 200* mg. of anhydro-3-ethyl-9- methyl-3-(3 sulfohydroxypropyl)thicarbocyanine hydroxide per mole.
• Coatings A and B contained dyes within :the scope of my invention.
• Coating C contained 200 mg. of anhydro-3-ethyl-9- methyl-3-(3-sulfopropyl)thiacarbocyanine hydroxide per silver mole.
• Example 4 CHaO CHzCHz-N N-CHzCHzOCHg Coating C contained 200 mg. of anhydro-5,S'-dichloro- 9-ethyl-3,3'-di-(4-sulfobutyl)thiacarbocyanine hydroxide per silver mole.
• Coating D contained 175 mg. of anhydro-5,5'-dichloro- 9-ethyl-3,3'-di-(4-sulfobutyl)thiacarbocyanine hydroxide plus 17.5 mg. of 5-[di (1-ethyl-2(lH)-l3-naphtho-[1,2]- thiazolylidene)-isopropylidene] 1,3 di-(fi-methoxyethyl)barbituric acid per silver mole.
• EXAMPLE 5 The effect of the combination of a benzimidazolocarbocyanine dye with the preferred green sensitizers is illustrated by the following examples.
• Coating A contained 200 mg. of anhydro-9'-ethyl-5,5'- diphenyl-3,3'-di(3 sulfobutyDoxacarbocyanine hydro-xide, monosodium salt per silver mole.
• Coating B contained 135 mg. of anhydro-9-ethyl-5,5- diphenyl-3,3'-di-(3 sulfobutyl)oxacarbocyanine hydroxixde monosodium salt plus 54 mg. of anhydro-5,5,6,6'- tetrachloro 1,1 diethyl-3,3-di-(3-sulfobutyl)benzimidazolocarbocyanine hydroxide per silver mole.
• Coating A contained 200 mg. of 3,3',9-triethyl-5,5-diphenyl-oxacarbocyanine iodide per silver mole.
• Coating B contained mg. of 3,3,9-triethyl5,5- diphenyl-oxacarbocyanine iodide plus 54 mg. of 5,5, 6,6 tetrachloro 1,l,3,3-tetraethylbenzimidazolocarbocyanine iodide per silver mole.
• Coating A contained 200 mg. of the red sensitizer anhydro 9 ethyl-3,3-di-(3-sulfopropy1)-4,5,4,5-dibenzothiacarbocyanine hydroxide monosodium salt per silver mole in Layer E. It also contained 200 mg. of the green sensitizer anhydro 9 ethyl-5 ,5 -dipheny1-3,3-di-(3-sulfobutyl)oxacarbocyanine hydroxide monosodium salt per silver mole in Layer D.
• the dyes utilized in this element are within the scope of my invention.
• Coating B contained 175 mg. of anhydro-9-ethyl-3,3'- di (3 sulfopropyl) 4,5,4,5 dibenzothiacarbocyanine hydroxide monosodium salt plus 17.5 mg. of S-[di-(lethyl 2(1H) ⁇ 3 naphtho[1,2]thiazolylidine)isopropylidene]-l,3-di-(,8-methoxyethyl)barbituric acid per silver mole in Layer E. It also contained 135 mg.
• Coating C contained 200 mg. of the red sensitizer 3,3- di-fl-carboxyethylthiacarbocyanine bromide per silver mole in Layer E. It also contained 200 mg. of the green sensitizer anhydro-l'-ethyl-3-(3-sulfobutyl)thia-2-cyanine hydroxide per silver mole in Layer D. These dyes are outside the scope of my invention.
• Coating A which contained sensitizers within the scope of my invention exhibited significantly less fog than Coating C which contained dyes not included in the scope of my invention.
• Coating B which contained red and green dye sensitizer combinations of my invention, exhibited an especially low fog level.
• sensitizing dyes employed in this invention may be used effectively over a wide concentration range, with best results at concentrations of about 10 to 250 mg. of dye per mole of silver halide.
• supersensitizing dyes are also effective over a broad concentration range, with especially good results being achieved at ratios of sensitizing dye to supersensitizing dye of about 1:5 to about 5:1, by weight.
• the photographic emulsions used in my invention can contain additional conventional addenda known in the art such as chemical sensitizers, stabilizers, development modifiers, plasticizers, hardeners, coating aids, etc.
• Various silver salts may be utilized as the sensitive salt such as silver bromide, silver iodide, silver chloride or mixed silver halides such as silver chlorobromide, silver chlorobromoiodide or silver bromoiodide.
• the spectrally sensitized emulsions of my invention can be used in emulsions which form latent images predominantly inside the silver halide crystal, such as those described in Davey and Knott US. Patent 2,592,250 issued Apr. 8, 1952.
• the dispersing agent for the silver halide grains there may be employed as the dispersing agent for the silver halide grains, gelatin or some other colloidal material such as colloidal albumin, a cellulose derivative or a synthetic resin, for instance, a polyvinyl compound.
• a variety of materials may be used as the support for the photographic layers of my invention.
• cellulose acetate, polyethylene terephthalate, paper, glass or metal supports may be utilized.
• a photographic element comprising a support having coated thereon a silver halide emulsion layer,
• N lite l h Xe wherein Z repersents the non-metallic atoms necessary to complete a cyclic nucleus selected from the group consisting of phenyl and naphthyl; R represents a substituent selected from the group consisting of hydrogen, lower alkyl and aryl; R and R each represents lower alkyl, said alkyl groups being free from carboxyl and sulfate substituents; and X represents an anion.
• a photographic element comprising a support having coated thereon a silver halide emulsion layer, said layer having in association therewith an azo dye, bleachable in the silver dye bleach process, which tends to cause fogging and desensitization of said emulsion, said emulsion being sensitized to red radiation with a symmetrical thiacarbocyanine dye having the following formula:
• R1 wherein Z represents the non-metallic atoms necessary to complete a cyclic nucleus selected from the group consisting of phenyl and naphthyl; R represents a substituent selected from the group consisting of hydrogen, lower alkyl and aryl; R and R each represents lower alkyl, said alkyl groups being free from carboxyl and sulfate substituents; and X represents an anion, and containing a supersensitizing concentration of a trinuclear dye having the general formula:
• R and R each represents an alkyl group
• Q, Z and Z each represents the non-metallic atoms necessary to complete a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring
• A represents a member selected from the group consisting of an oxygen atom and a sulfur atom
• n, m and d each represents a positive integer of from 1 to 2.
• a photographic element comprising a support having coated thereon a silver halide emulsion layer containing a bleachable cyan colored dye which tends to cause fogging and densitization of the silver halide emulsion, said emulsion being sensitized to red radiation with anhydro-9-ethyl-3,3-di-di(3 sulfopropyl)-4,5,4,5-dibenzothiacarbocyanine hydroxide.
• a photographic element comprising a support having coated thereon a silver halide emulsion layer, said layer having in association therewith an azo dye, bleachable in the silver dye bleach process, which tends to cause fogging and densensitization of said emulsion, said emulsion being sensitized to red radiation with a symmetrical thiacarbocyanine dye having the following formula:
• Z represents the non-metallic atoms necessary to complete a cyclic nucleus selected from the group consisting of phenyl and naphthyl
• R represents a substituent selected from the group consisting of hydrogen, lower alkyl and aryl
• R and R each represents lower alkyl, said alkyl groups being free from carboxyl and sulfate substituents
• X represents an anion, and containing a supersensitizing concentration of a trinuclear dye having the general formula:
• R and R each represents an alkyl group
• Q, Z and Z each represents the non-metallic atoms necessary to complete a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring
• A represents a member selected from the group consisting of an oxygen atom and a sulfur atom
• n, m and d each represents a positive integer of from 1 to 2.
• a photographic element comprising a support having coated thereon a silver halide emulsion layer, said layer having in association therewith an azo dye, bleachable in the silver dye bleach process, which tends to cause fogging and densensitization of said emulsion, said emulsion being sensitized to red radiation with a symmetrical thiacarbocyanine dye having the following formula:
• R I ia X wherein Z represents the non-metallic atoms necessary to complete a cyclic nucleus selected from the group consisting of phenyl and naphthyl; R represents a substituent selected from the group consisting of hydrogen, lower alkyl and aryl; R and R each represents lower alkyl, said alkyl groups being free from carboxyl and sulfate substituents; and X represents an anion, and containing a supersensitizing concentration of a trinuclear dye having the general formula:
• R and R each represents an alkyl group
• Q, Z and Z each represents the non-metallic atoms necessary to complete a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring
• A represents a member selected from the group consisting of an oxygen atom and a sulfur atom
• n, m and d each represents a positive integer of from 1 to 2.
• a photographic element comprising a support having coated thereon a silver halide emulsion layer containing a bleachable magenta colored dye which tends to cause fogging and desensitization of the silver halide emulsion, said emulsion being sensitized to green radiation with anhydro 9-ethyl-5,5'-diphenyl-3,3'-di-(3-sulfobutyl) oxacarbocyanine hydroxide, monosodium salt.
• a photographic element comprising a support having coated thereon a silver halide emulsion layer, said layer having in association therewith an azo dye, bleachable in the silver dye bleach process, which tends to cause fogging and desensitization of said emulsion, said emul- 14 sion being sensitized to red radiation with a symmetrical thiacarbocyanine dye having the following formula:
• Z represents the non-metallic atoms necessary to complete a cyclic nucleus selected from the group consisting of phenyl and naphthyl
• R represents a substituent selected from the group consisting of hydrogen, lower alkyl and aryl
• R and R each represents lower alkyl, said alkyl groups being free from carboxyl and sulfate substituents
• X represents an anion, and containing a supersensitizing concentration of a trinuclear dye having the general formula:
• R and R each represents an alkyl group
• Q, Z and Z each represents the non-metallic atoms necessary to complete a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring
• A represents a member selected from the group consisting of an oxygen atom and a sulfur atom
• n, m and d each represents a positive integer of from 1 to 2.
• a photographic element comprising a support having coated thereon at least two silver halide emulsion layers, one of said layers containing a bleachable cyan colored dye which tends to cause fogging and desensitization of the silver halide emulsion, the silver halide of said layer being spectrally sensitized to red radiation with anhydro 9 ethyl-3,3'-di-di(3-sulfopropyl)-4,5,4',5'-dibenzothiacarbocyanine hydroxide; and said other layer having incorporated therein a bleachable magenta colored dye which tends to cause fogging and desensitization of the silver halide emulsion, the silver halide of said layer being spectrally sensitized to green radiation with anhydro 9 ethyl-5,5'-diphenyl-3,3'-di-(3-sulfobutyl)oxycarbocyanine hydroxide, monosodium salt.
• a photographic element as described in claim 1 wherein the symmetrical thiacarbocyanine dye is selected from the group consisting of anhydro-5,5'-dichloro-3,9-diethyl-3'-(3-sulfobutyl)thiacarbocyanine hydroxide, anhydro-5,5-dichloro 9 ethyl-3,3'-di-(4-sulfobuty1)thiacarbocyanine hydroxide, and anhydro-'9-ethyl-3,3'-di-(3-sul fopropyl)-4,5,4,5-dibenzothiacanbocyanine hydroxide.
• a photographic element as described in claim 2 wherein the symmetrical thiacarbocyanine dye is selected from the group consisting of anhydro-5,5'-dichloro-3,9-diethyl-3'-(3-sulfobutyl)thiacarbocyanine hydroxide and anhydro-5,5'-dichloro 9 ethyl-3,3-di-(4-sulfobutyl)thiacarbocyanine hydroxide and the trinuclear dye is 5-[di 1- ethyl 3(lH)-fl-naphtho-[1,2]-thiazolylidene)isopropylidene]-l,3-di-(,B-methoxyethyl)barbituric acid.
• a photographic element as described in claim 4 wherein the symmetrical oxacarbocyanine dye is selected from the group consisting of anhydro-9-ethyl-5,5-diphenyl 3,3 di (3-sulfobutyl)oxacarbocyanine hydroxide, monosodium salt and 3,3,9-triethyl-5,5'-diphenyloxacarbocyanine iodide.
• a photographic element as described in claim 5 wherein the symmetrical oxacarbocyanine dye is selected from the group consisting of anhydro-9-ethyl-5,5'-diphenyl 3,3 di (3-sulfobutyl)oxacarbocyanine hydroxide, monosodium salt, and 3,3,9-triethyl-5,5-diphenyloxacarbocyanine iodide and the benzimidazolocarbocyanine dye is selected from the group consisting of anhydro-5,5',6,6'- tetrachloro-l,1'-diethyl 3,3 di-(3-sulfobutyl)benzimid- 15 16 azolocarbocyanine hydroxide and 5,S',6,6-tetrachl0ro-1, 3,157,507 11/1964 Bruengger 96-99 1,3,3'-tetraethyl benzimidazolocarbocyanine iod

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Cited By (2)

• 1965
  • 1965-08-19 US US481064A patent/US3574623A/en not_active Expired - Lifetime
• 1966
  • 1966-08-04 DE DE19661547719 patent/DE1547719A1/de active Pending
  • 1966-08-10 BE BE685341D patent/BE685341A/xx unknown
  • 1966-08-16 CH CH1179166A patent/CH458922A/fr unknown
  • 1966-08-19 GB GB37231/66A patent/GB1147086A/en not_active Expired

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