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
  • G03C5/00—Photographic processes or agents therefor; Regeneration of such processing agents
  • G03C5/26—Processes using silver-salt-containing photosensitive materials or agents therefor
  • G03C5/29—Development processes or agents therefor
  • G03C5/305—Additives other than developers
  • G03C5/3056—Macromolecular additives
• • 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
  • G03C5/00—Photographic processes or agents therefor; Regeneration of such processing agents
  • G03C5/26—Processes using silver-salt-containing photosensitive materials or agents therefor
  • G03C5/29—Development processes or agents therefor
  • G03C5/305—Additives other than developers

Definitions

• Photographic developer compositions such as liquid concentrates, containing a silver halide developing agent, an organic activator and a polyvinylpyrrolidone. Solutions comprising developer concentrates diluted with water and their use for developing photographic elements are also disclosed.
• This invention is directed to photographic compositions and processes, especially photographic developer compositions.
• the invention is directed to photographic silver halide developer compositions, especially liquid concentrates, containing a silver halide developing agent, an organic activator and a polyvinylpyrrolidone, and having a low concentration of or no inorganic salt.
• Silver halide developer compositions containing a silver halid developing agent, an organic activator, i.e., an organic compound which activates development, and having a low concentration or no inorganic salt, such as little or no alkali metal hydroxide, alkali metal carbonate, alkali metal sulfite or alkali metal inorganic silver halide solvent, are known and have been used. These compositions have been useful where it is undesirable to employ a developer composition containing any inorganic salts or more than a low concentration of inorganic salts, and further, provide a method of obtaining a highly concentrated solution. However, certain difficulties have arisen with these compositions, such as in some cases formation of dichroic stain and/or loss in emulsion speed of the photographic element processed.
• compositions of this type are concentrated liquid developing compositions which contain organic activators, e.g. organic amines, as the only development activator or as the major development activator.
• organic activators e.g. organic amines
• Typical concentrates of this type are disclosed in British Pat. 958,678, issued May 21, 1964. Such concentrates have advantages over other developer solutions, such as requiring less storage space, ease of shipping, etc.
• the solvent action for silver halides of organic amines typically employed as the activators has given rise to silver stains, i.e. dichroic stain, on certain photographic elements developed with these compositions.
• Such stains which appear on the surface of processed photographic elements, especially photographic film are apparent as a deposit of fine or colloidal silver. This problem has been troublesome especially with fine grain silver halide films.
• Phenylmercaptotetrazole, benzotriazole and similar known heterocyclic antifoggants have been found unsatisfactory for this purpose due to the fact that they cause loss in speed of the photographic emulsion processed in addition to problems associated with replenishment and exhaustion of the developer composition. It was also surprisingly found that a monomeric pyrrolidone, such as N-methylpyrrolidone, as set out in US. Pat. 3,276,875, or N-vinylpyrrolidone, has been found ineffective alone for preventing dichroic stain when employed in developer concentrates containing an organic amine activator. This is illustrated in following EX- arnples 11 and 12.
• polyvinylpyrrolidone in photographic elements and compositions has been known heretofore.
• polyvinylpyrrolidone has been employed in photographic emulsions for various purposes as disclosed, for example, in U.S. Pat. 3,013,018 and US. Pat. 3,167,429.
• an object of this invention to provide novel photographic developer compositions containing an organic development activator and processes of development which avoid formation of dichroic stain in combination with maintaining emulsion speed of photographic elements processed in such compositions.
• Another object of the invention is to provide a means for developing exposed silver halide photographic emul- SlOIlS.
• dichroic stain can be Wholly or substantially avoided in combination with little or no loss in emulsion speed in a photographic emulsion by employing a developer composition; for example, a liquid concentrate diluted with water, comprising a specific combination of ingredients, as described herein.
• a developer composition for example, a liquid concentrate diluted with water, comprising a specific combination of ingredients, as described herein.
• the liquid developers of the invention have a low inorganic salt content. This is intended to mean that the inorganic salt content does not exceed about 5% by weight of the total developer composition and is specifically 0% to about 5%, preferably less than 1% by weight.
• inorganic salts include inorganic sulfites, such as sodium sulfite, inorganic thiocyanates such as sodium thiocyanate, sodium thiosulfate and the like, as well as inorganic alkalis, such as alkali metal hydroxides, e.g. potassium hydroxide and sodium hydroxide and inorganic carbonates such as sodium carbonate.
• the developer is also preferably a liquid concentrate which is suitable for preparation of photographic silver halide developer solutions merely by the addition of water.
• the concentrates of the invention typically contain a small proportion of, or no, free uncombined water.
• Any polyvinylpyrrolidone polymer can be employed in the practice of the invention which prevents dichroic stain on the photographic element processed and does not provide a loss in emulsion speed.
• the molecular Weight of a polyvinylpyrrolidone added to the developer compositions of the invention can vary over a wide range. Suitable molecular weight ranges include those of about 10,000 to about 40,000 or more.
• the solubility of the polyvinylpyrrolidone in the developer compositions, especially the developer concentrates and/or in the resulting solution of the concentrate diluted with water is affected by the molecular weight of the polyvinylpyrrolidone.
• Polyvinylpyrrolidone having molecular weight of about 10,000 to about 40,000 is soluble in the developer concentrate of the invention without the use of organic solvents to aid the solubility of polyvinylpyrrolidone in the concentrate.
• Polyvinylpyrrolidone having a molecular weight above about 40,000 is also suitable; however, compounds above this molecular weight may not be soluble in the concentrate of the invention without the aid of organic solvents.
• the suitable concentration of polyvinylpyrrolidone in the developer compositions of the invention can vary over a wide range. Usually about .001% to about by weight of polyvinylpyrrolidone in the developer composition is suitable. Concentrations above about 10 grams of polyvinylpyrrolidone per liter of developer concentrate have not been found necessary. Usually a concentration of 0.1 gram to about 10 grams of polyvinylpyrrolidone per liter of developer concentrate is suitable. With most developer concentrates of the invention, concentrations of about 0.25 gram to about 0.5 gram per liter of concentrate to provide the desired results. Concentrations outside these ranges can be used.
• Polyvinylpyrrolidone as employed herein is typically represented by the general formula:
• L CH OHZJH wherein n represents a whole number, e.g. a number sufficiently high to provide a molecular weight of about 10,000 to about 40,000 or more.
• polymers are well known and can be prepared, for example, by processes of polymerization of N-vinyl-Z-pyrrolidone, disclosed in U.S. Pat. 2,265,540, issued Dec. 9, 1941 and U.S. Pat. 2,335,454, issued Nov. 30, 1943.
• the polymer can also contain groups or radicals, such as hydroxyethyl radicals and/or sulfonate radicals which make the polymer more soluble in the developer compositions of the invention or lower alkyl groups, e.g. methyl or ethyl groups.
• Organic activators which can be employed in the practice of the invention include any organic compound which is effective in activating the silver halide developing agent present in the developer composition.
• Typical organic activators employed in the developer compositions of the invention are set out in British Pat.
• Such activators are usually amine activators, especially morpholine or hydroxyalkylamines, represented by the formula:
• R is a hydroxyalkyl radical having 1 to 5 carbon atoms, and R and R are each hydrogen, an alkyl radical having 1 to 4 carbon atoms or a hydroxyalkyl radical having 1 to 3 carbon atoms.
• the hydroxyalkyl amines used in the developer concentrates of the invention typically serve both as a solvent and as a development activator.
• One or more of the suitable hydroxyalkyl compounds is typically in liquid form. Hydroxyalkylamine activators within the scope of the invention include:
• the photographic silver halide developing agents suitable for the purposes of the invention include any silver halide developing agent which is compatible with components of the developer composition and provides the desired development action.
• the suitable silver halide developing agents are preferably soluble in the developer composition.
• Suitable developing agents which can be employed include, for example, polyhydroxy benzenes, such as hydroquinone developing agents, e.g.
• hydroquinone alkyl substituted hydroquinone, such as t-butylhydroquinone, methylhydroquinone, dimethylhydroquinone; catechol and pyragollol; chloro substituted hydroquinones, such as chlorohydroquinone, or dichlorohydroquinone; alkoxy substituted hydroquinone, such as methoxy or ethoxy hydroquinone; aminophenol developing agents, such as N-methyl-p-aminophenol and 2,4-diaminophenols; ascorbic acid developing agents; pyrazolidone developing agents, including those described in British Pat.
• the amount of developing agent which is suitable also can vary over a wide range depending on many factors, such as the element to be processed, the other components of the composition, the desired image, and the like. It usually comprises about 2% to about 45% by weight of the total developer composition. In a liquid concentrate, it typically comprises about 2% to about 30% by weight of the total compositions.
• One especially suitable embodiment of the invention comprises a liquid silver halide developer concentrate comprising a combination of silver halide developing agents, such as a combination of a pyrazolidone developing agent and a hydroquinone developing agent; a hydroxyalkylamine activator; a polyvinylpyrrolidone soluble in the concentrate; a hydroxyalkylamine sulfur dioxide addition product; and to about by weight of inorganic salt.
• a combination of silver halide developing agents such as a combination of a pyrazolidone developing agent and a hydroquinone developing agent
• a hydroxyalkylamine activator such as a combination of a pyrazolidone developing agent and a hydroquinone developing agent
• a hydroxyalkylamine activator such as a combination of pyrazolidone developing agent and a hydroquinone developing agent
• a hydroxyalkylamine activator such as a hydroxyalkylamine activator
• Silver halide developing agents About 2% to about 30% Silver halide developing agents. About 5% to about 80% Hydroxyalkylamine activator. About .001% to about Polyvinylpyrrolidone.
• Another embodiment includes, for example, a liquid developer silver halide developer concentrate comprising:
• the developer compositions of the invention are typically diluted with water before use.
• the usual ratio of developer concentrate to water is about one part by volume developer concentrate to about 1 part to about parts by volume water, e.g. 1 part by volume concentrate to about 10 to about 50 parts by volume water. Concentration ranges outside of this range can also be used.
• the developer compositions and diluted solutions prepared from the developer compositions of the invention can be prepared in any suitable manner.
• the composition can be prepared merely by mixing the components of the composition. Since some of the components are typically in liquid form, this aids in dissolving the polyvinylpyrrolidone.
• Another convenient way of preparing compositions within the scope of the invention is by adding hydroxyalkylarnines to the developer components and then adding sulfur dioxide to the resulting mixture until the desired ratio of sulfur dioxide addition products is obtained. This method is set out, for example, in British Pat. 958,678, issued May 21, 1964. In certain instances, it can be advantageous to prepare the hydroxyalkylamine-sulfur dioxide addition product before addition to the developer composition.
• liquid developer compositions of the invention can be stored for extended periods of time without material deterioration of the developer. This is especially true when the developer composition is sealed in containers, such as those customarily used for liquid solutions.
• the developer can comprise a liquid concentrate as described above diluted with water, e.g. about 1 part by volume concentrate to about 1 to 50 parts by volume water.
• the developer concentrates of the invention are suitable for development of a wide variety of photographic emulsions particularly silver halide gelatino photographic emulsions.
• the photographic emulsion developed with the concentrates or diluted concentrates of the invention include, for example, those which are non-spectrally sensitized, such as X-ray type emulsions or emulsions which are orthochromatic, panchromatic, infrared sensitive, and the like, containing spectral sensitizing dyes such as described in US. Pats. 2,526,632 and 2,503,776.
• Spectral sensitizers which can be used in a photographic emulsion processed with the developer compositions of the invention include cyanines, merocyanines, styryls and the like.
• photographic emulsions employed in the practice of the invention can be sensitized by using any of the well known techniques used in emulsion making, e.g. by digesting with naturally active gelatin or various sulfur, selenium, noble metal and/or gold compounds.
• the photographic emulsions processed according to the invention, and the compositions employed for processing, including the developer concentrates and diluted concentrates of the invention, can contain various photographic addenda, especially those known to be beneficial in photographic compositions.
• the types of addenda and concentrations to be employed can be determined by those skilled in the art.
• Suitable photographic addenda include, for example, hardeners, such as alum, such as those set out in British Pat. 974,317; buffers which maintain the desired pH level including various sulfonamides and boraxes; coating aids; plasticizers; speed increasing addenda such as quaternary ammonium salts and alkylene oxide polymers, e.g. polyethylene glycols; and stabilizing agents such as sodium sulfite.
• the silver halides employed in the practice of the invention include any of the photographic silver halides, such as silver bromide, silver iodide, silver chloride, or mixed silver halides such as silver ohlorobromide, silver bromoiodide, and the like.
• the silver halides can be those which form latent images predominantly on the surface of the silver halide grains or those which form latent images inside the silver halide crystals, such as described in US. Pat. 2,592,250Davey and Knott, issued Apr. 8, 1952.
• Typical supports include films, such as cellulose acetate films, polyethylene terephthalate or other polyester films, polyvinyl acetal films, polystyrene films, polycarbonate films and related materials, papers, such as paper supports which are coated with resinous materials, e.g. coated with polyethylene, polypropylene and/or ethylene-butene copolymers, glass, metal and the like.
• the photographic elements processed according to the invention typically contain a layer comprising any of the known hydrophilic water-permeable binding materials suitable for photographic purposes. These include, for example, gelatin, cellulose derivatives, polymerized vinyl compounds, as well as mixtures of such binding agents.
• the binding agents can also contain water insoluble polymers, such as polymerized ethylenically unsaturated compounds, e.g. polymers of acrylates and methacrylates.
• an organic sequestering agent present in the developer composition of the invention and in such instances ethylenediamine tetraacetic acid, 1,3-diamino-2-propanol tetraacetic acid and diglycolic acid, for example, can be used.
• Other sequestering agents can also be used.
• Suitable antifoggants include organic antifoggants, for example, benzotriazole, benzimidazole, 2-mercaptobenzimidazole and mercaptotetrazole antifoggants.
• the developer compositions of the invention can contain an inorganic antifoggant, such as potassium bromide, potassium iodide and/ or sodium bromide.
• the photographic element processed can also contain an antifoggant.
• the concentration of antifoggant in either the photographic element processed or in the developer composition will vary depending upon the desired image, other components present, subsequent processing steps and the like. Usually less than about 2% by weight, e.g. 01% to about 2% by weight, antifoggant is suitable in the developer composition of the invention.
• Development of photographic elements with the developer compositions of the invention is usually carried out at ambient temperatures such as between about 20 C. and about 30 C. However, higher temperatures can be employed if desired.
• compositions of the invention can have a pH value typically above about 7, such as above about 7 to about 11.
• the appropriate pH value will be determined by the photographic element to be processed, the developer composition, the desired degree of development, and the like.
• the time for processing employing the developer compositions of the invention can vary between about a few minutes up to about an hour or more depending upon the desired image, processing conditions, and the like.
• the components of the developer compositions of the invention can be stored in separate containers such as in separate packets or bottles as part of a kit before use. At the time of use, the components can be mixed together and diluted with water to the desired concentration. For example, developing agent and organic amine activator components can be present in one container and the polyvinylpyrrolidone in another. These two compositions can be mixed before use.
• developer replenisher compositions include compositions added to a developer composition to increase its developing activity.
• a typical example of a developer replenisher is one containing about to about 15%, e.g. about 9%, by weight diethylene glycol, about 20 to about 40%, e.g. about 34%, by weight iminodiethanol-sulfur dioxide addition product, about 10 to about e.g. about 13%, by weight iminodiethanol, about 2% to about 30% by weight silver halide developing agent, such as a mixture of a pyrazolidone developing agent and a hydroquinone developing agent, about 1% to about 10% by weight of 2- aminoethanol, about .001 to about 10% by weight of polyvinylpyrrolidone, in addition to minor proportions, e.g.
• This developer replenisher composition can be diluted with water in the same ratios as the developer compositions described. It can also be added to a developer composition in undiluted form.
• concentrations of developer replenisher added to the developer compositions of the invention can vary over a wide range depending upon the degree of exhaustion of the developer com-position, processing conditions, number of photographic elements to be processed, and the like. Typically, about 20 milliliters of developer replenisher composition is added to each liter of the developer solution for each square inches of film to be processed.
• concentrate as employed herein is intended to mean a liquid solution of a silver halide developer, an organic activator and a polyvinylpyrrolidone, which is more concentrated than is usually necessary to develop an exposed photographic element.
• Developer concentrates are well known in the photographic art and have the advantage that they require less space during storage before use and are more convenient and more economical to ship.
• a concentrate suitable for the purposes of the invention is one which is diluted with water in ratio of about 1 part by volume concentrate to about 1 to about 50 or more parts by volume of water to produce an aqueous developer solution suitable for developing exposed silver halide emulsions.
• EXAMPLE 1 This example illustrates a developer composition and process of the invention using a polyvinylpyrrolidone in a developer concentrate containing an organic amine activator.
• a liquid developer concentrate is prepared by mixing at about 20 C. the following components:
• Example 1 The procedure set out in Example 1 is repeated employing the same developer concentrate without the addition of polyvinylpyrrolidone. An identical film is developed under the same conditions. The resulting developed film has a pronounced deposit of dichroic stain.
• EXAMPLE 3 This example illustrates that polyvinylpyrrolidone can be used in the developer compositions of the invention over a range of concentrations.
• Example 1 The procedure set out in Example 1 is repeated employing the same developer concentrate with the exception that 0.5 gram of polyvinylpyrrolidone is added. An identical film is developed under the same conditions, as in Example 1. The resulting developed film is free of dichroic stain. No loss in emulsion speed is observed.
• Example 1 The procedure set out in Example 1 is repeated employing the same developer concentrate with the exception that 3.2 grams of polyvinylpyrrolidone having a molecular Weight of about 10,000 is dissolved in each liter of the described developer concentrate. The film after development is free of dichroic stain and no loss in emulsion speed takes place.
• EXAMPLE 5 This is a further example illustrating the use of polyvinylpyrrolidone according to the invention.
• Example 1 The procedure set out in Example 1 is repeated employing the same developer concentrate with the exception that 0.25 gram of polyvinylpyrrolidone having a molecular weight of about 40,000 (PVP Grade K-30, a commercial product of General Aniline and Film Corporation, New York, N.Y.) is added. An identical film is developed under the same conditions as in Example 1. The developed film is free of dichroic stain and no loss in emulsion speed is observed.
• PVP Grade K-30 a commercial product of General Aniline and Film Corporation, New York, N.Y.
• Example 6 The procedure in Example 1 is repeated employing the same developer concentrate with the exception that 0.5 gram of polyvinylpyrrolidone having a molecular weight of about 40,000 is added. An identical film under the same conditions is developed as in Example 1. The developed film is free of dichroic stain and exhibits no loss in emulsion speed.
• Example 7 The procedure set out in Example 1 is repeated employing the same developer concentrate with the exception that 3.2 grams of polyvinylpyrrolidone having a molecular weight of about 40,000 is added. An identical film under the same conditions is developed as in Example 1. The developer film is free of dichroic stain and exhibits no loss in emulsion speed.
• EXAMPLE 8 This example illustrates that the developer concentrate of the invention can be diluted with a range of amounts of water.
• Example 1 The procedure set out in Example 1 is repeated with the exception that the described developer concentrate is diluted in the ratio of 1 part by volume concentrate to parts by volume water. Similar results to those obtained in Example 1 are obtained using this dilution.
• EXAMPLE 9 The procedure set out in Example 1 is repeated with the exception that 0.5 gram of polyvinylpyrrolidone is added to the developer concentrate rather than 0.25 gram. Also, several sheets of the described film are processed in the diluted developer concentrate each week for a period of four weeks. milliliters of a developer replenisher composition containing:
• EXAMPLE 10 This example illustrates the use of a sequestering agent and an antifoggant in a developer composition of the invention.
• a liquid developer concentrate is prepared by mixing at about 20 C. the following components:
• One part by volume of the mixture is diluted with 20 parts by volume of water at about 20 C.
• a sheet of photographic film having a medium grain silver bromoiodide emulsion is exposed imagewise to light.
• the resulting image is developed by immersing the film in the diluted developer for a few minutes at about 21 C.
• Favorable results are obtained.
• EXAMPLE 11 This is a comparative example illustrating that surprisingly monomeric pyrrolidones are not effective alone in the developer concentrates of the invention for preventing dichroic stain.
• a developer concentrate is prepared as in Example 1 with the components as set out in Example 1 without the addition of polyvinylpyrrolidone.
• the resulting concentrate is divided into six equal parts, (A), (B), (C), (D), (E) and (F).
• the following compounds and amounts per liter of concentrate are added to these parts respectively:
• strip (E) All of the strips contained significant dichroic stain except strip (E).
• the high concentration of N-vinyl pyrrolidone in solution (E) provided some reduction of dichroic stain but the high concentration of the monomeric pyrrolidone causes excessive dilution of the developer solution.
• EXAMPLE 12 This is another comparative example illustrating that known antistain agents which have been employed in developers containing an inorganic alkaline activator are not efi ective in developer solutions prepared by diluting the developer concentrates of the invention with water.
• a developer concentrate is prepared as in Example 1 with the components as set out in Example 1 without the addition of polyvinylpyrrolidone.
• the concentrate is divided into 8 Parts and (N). Each of these is diluted with water in the ratio of 1 part by volume concentrate with 31 parts by volume Water. The following compounds and amounts per liter of diluted concentrate are added to these parts respectively:
• All of the developed strips of film contain a significant amount of dichroic stain except those developed in solutions containing polyvinylpyrrolidone (L and M).
• the films developed in solutions containing polyvinyl pyrrolidone exhibit no loss in emulsion speed or in contrast.
• a photographic silver halide developer comprising:
• a developer as in claim 1 comprising a liquid con centrate.
• a developer as in claim 1 wherein said silver halide developing agent comprises a pyrazolidone developing agent.
• a developer as in claim 1 wherein said silver halide developing agent comprises a combination of a pyrazolidone developing agent and a hydroquinone developing agent.
• a developer as in claim 1 wherein said organic activator comprises a hydroxyalkylamine.
• organic activator comprises morpholine or a hydroxyalkylamine represented by the following structure:
• R is a hydroxyalkyl radical having 1 to 5 carbon atoms and R and R are each hydrogen, an alkyl radical containing 1 to 3 carbon atoms or a hydroxyalkyl radical having 1 to 3 carbon atoms.
• a developer as in claim 1 also comprising a hydroxyalkylamine-sulfur dioxide addition product and/or hydroxyalkylamine sulfite.
• a developer as in claim 2 containing about 0.001 to about grams of polyvinylpyrrolidone per liter of concentrate.
• a developer as in claim 1 comprising a liquid concentrate of:
• a developer as in claim 1 comprising a liquid concentrate of (a) a pyrazolidone developing agent and a hydroquinone developing agent,
• a developer as in claim 13 also comprising an antifoggant.
• a developer as in claim 13 wherein said antifoggant is potassium bromide.
• a developer as in claim 1 also comprising an organic sequestering agent which is ethylenediamine tetraacetic acid.
• a photographic developer as in claim 1 comprising a liquid concentrate admixed with water.
• a photographic developer as in claim 1 comprising a liquid concentrate dissolved in water in the ratio of about 1 part by volume of concentrate to about 1 to about 50 parts by volume of water.
• a process for developing a latent image in an exposed silver halide emulsion comprising contacting said emulsion With a silver halide developer comprising:
• a photographic silver halide developer as in claim 1 comprising an admixture of:

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• General Physics & Mathematics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Silver Salt Photography Or Processing Solution Therefor (AREA)

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Cited By (14)

• 1967
  • 1967-09-25 US US670389A patent/US3552969A/en not_active Expired - Lifetime
• 1968
  • 1968-09-20 GB GB44722/68A patent/GB1248448A/en not_active Expired
  • 1968-09-20 CH CH1409868A patent/CH496968A/fr not_active IP Right Cessation
  • 1968-09-23 FR FR1587093D patent/FR1587093A/fr not_active Expired
  • 1968-09-23 BE BE721292D patent/BE721292A/xx not_active IP Right Cessation
  • 1968-09-24 DE DE19681797387 patent/DE1797387A1/de active Pending

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