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

Definitions

• This invention relates to photographic develop-,- ers and a method of photographic development, and is, in part, a continuation of my application Serial No. 196,366, filed March 17, 1938. entitled Photographic developer.
• a developer for this purpose must be'satisfactory for use in the tanks of continuous developing machines; it must have a relatively long life, i. e., must not age too rapidly; and it must maintain its developing action substantially constant during its period of usefulness.
• One object of my invention is to provide an improved method of photographic development.
• Another object of my invention is to provide animproved method of maintaining the alkalinity effectively constant during development.
• Another object of my invention is to provide an improved method of removing deleterious materials from the developer during development.
• Another object of my invention' is to provide an improved method of removing exhausted developing material from the developer during development.
• v 1 Another object of my invention is to provide an improved method of maintaining the effective strength of the developer constant by maintaining its volume constant.
• Another object of my invention is to provide an improved method of maintaining equilibrium between the rate of development of photographic material and the rate of replenisment of developer physically removed and developer chemically 5 exhausted.
• Another object of my invention is to provide an improved method of maintaining a developer at constant effective developing power by replen x ishment of the developer with a developing solution of the same composition and strength as the original developer.
• Another object of my invention is to provide ,an improved method of preventing reticulation and clumping of silver grains by hardening the emul- 15 sion material in the developer. 7
• Another object of my invention is to provide an improved method of hardening emulsion mate-- rial.
• Another object of my invention is to harden emulsion material in an alkaline developer.
• the objects are accomplished according to my invention by adding a metallic compound, such, for example, as' potassium alum, to the develop ing solution, and using an alkali in suflicient quantity to dissolve or redissolve the precipitate which tends to be, or is, first formed.
• a metallic compound such as' potassium alum
• My invention in its broad aspect, is applicablev to developers containing practically any of the usual developing agents which function in alkaline solution, and also is adapted to the use of any of the usual alkalies, although some developing agents and some alkaliesare preferable to others.
• alum in developer
• the aluminum may be introduced in the readily available form of potassium aluminum sulphate, known generally as alum, or any other convenient water soluble aluminum salt may be used, such, for example, as aluminum sulphate, aluminum chloride, or aluminum bromide.
• aluminum is the metal which I have found to be usually most desirable for my purpose, I find that appropriate salts of either zinc, tin, chromium or lead may also be used.
• the aluminum compounds produce sufficient tanning action on the gelatine, or prevent the softening action of the alkali to such an extent,
• the developing agent may be, so far as I have been able to ascertain, any usual or customary photographic developing agent.
• the following developing agents have been satisfactory used with each of the aforementioned metals:
• Hydroquino'ne must be protected by the presence of sulphite before sodium hydroxide is added, that is, for the best results. Duratol will not dissolve without the presence of sodium hydroxide. These examples merely indicate that there is a variation in the properties of the various developing agents. dissolve the developing agent simultaneously with sodium hydroxide. Sodium sulphite is added to the solution, as is potassium bromide or a suitable halidesalt, to act as a restrainer. The order of admixture of the various components of the developer is immaterial.
• the admixture must be made in such a fashion that a proper balance can be observed, that is, the precipitate which first tends to be or is formed by the metallic salt is redissolved by adding an appropriate quantity of alkali. The balance between this precipitate and the alkali is produced when the metallic precipitate is just redissolved.
• the alum and alkali may, if desired, be dissolved separately and then mixed, or the alum may be dissolved first and the alkali added afterward, or vice ve according to which is most convenient.
• sodium hydrate is used, the quantity thereof must be approximately the same as that of the alum, whereas if the carbonate is used, the quantity thereof must be of the order of four times the quantity of the alum, depending upon the degree of hydration of the carbonate.
• the developing agent may be mixed in a quantity amounting to approximately to gram molecular weight per liter.
• the amount of developer used is determined by the desired developer speed or reaction velocity, Sodium sulphite is added as a preservative in a quantity amounting to approximately. V4 mol. per liter or more.
• the concentration of sulphite is not critical, and should be not less than 1 molecule of sulphite for each molecule of developer.
• Sodium hydroxide is, as pointed out above, used as an energizer, and the quantity'of this is determined by the characteristics desired in the developer.
• the usable concentrations range from below grains per liter to above 300 grams per liter. 0
• the sodium hydroxide is balanced with an appropriate amount of alum determined as follows: Powdered alum is slowly added to the solution containinghydroxide. As addition of the alum is continued, the rate of solution slowly decreases untilthe point is reached where further addition of alum produces no further-solution, leaving undissolved alum crystals. Conversely, the alum may be dissolved first and the sodium hydroxide added later. In this case, the initial addition of sodium hydroxide produces a precipitate of aluminum hydroxide which is redissolved on further addition of sodium hydroxide, and when this precipitated aluminum hydroxide is just redissolved the solution is in proper equilibrium.
• the appropriate amount ofpotassium bromide may be added to the solution at any time during preparation thereof. The addition of other substances to the developing solution for other or incidental purposes is within the scope of my invention provided only that the aforesaid balance between the aluminum content and alkali content is maintained.
• NazSO "grams" 50 p-hydroxyphenyl- Glycine (Glycim do.. NaOH do KaKSOd 2.121110 1 do Water to make ccs 1000 For maximum contrast with this'developer, 10
• Hydroquinone para-dihydroxybenzene Water to make ccs 1000 proximately 250 feet of film with the same loss of strength, corresponding to a decrease of approximately .2 in the density of the finished film. As compared to the prior developers used on sound film which, with the customary exposure, would develop the film to a density of the order of 1.9, my improved.
• the film footage per liter above referred to is such that no replenishment of the developer is required in ordinary film developing machines.
• the film runs through the machine at a speed of the order of 180 feet per minute, and -a compressed air jet is used to blow adhering developer from the film back into the tank'.
• this residual adhering developer is a quantity of the order of magnitude of the developer used in developing the -film.
• the second developer formula given above has the advantage over the first formula inthat it is somewhat less expensive and requires a development time, in a developing machine, of the order of four minutes, as against nine to eleven min-' utes for the first formula.
• Aluminate ions exist from the reaction It is understood that each and every compound indicated in the above reaction will form certain ions in solution. For example, the alum in solution would produce potassium ions, aluminum ions and sulphate ions. The sodium aluminate indicated would, in solution, produce sodium ions and aluminate ions. It is evident from the above reaction, which is really a mass reaction balance consisting of three reactions, that there will be present in the solution a large number of different ions.
• This coagulation of aluminum and deleterious material may be either permitted to settle to the bottom of the developing container and removed therefrom at convenient intervals or the developer may be passed into a separate settling tank or container from which the sediment may be removed from time to time. Since the addition of fresh developer of the original composition does not tend to redissolve the aluminum as the addition of a stronger solution, such as generally used for enrichment of developer, would do, this precipitate does not tend to become finely divided or redissolved, and it is therefore readily removed from the zone of operations in the manner before described. This greatly decreases the cost.
• a further advantage of my improved developer is that if the aforesaid gelatinous precipitate is not removed, but is kept in suspension in the solution by mechanical agitation, either through the passage of the film through a relatively small quantity of solution or otherwise, this gelatinous precipitate does not shown the tendency to adhere to the film, which is common to the materials in suspension in a partly exhausted developer of the usual type. In other words, a considerable portion of such material is removed from a developing machine by the blow-back and any residual material which may adhere to the film is easily removed in the rinse water, leaving no spots or stains whatever on the film.
• the method of maintaining the alkalinity of a photographic developer effectively constant comprising substantially balancing the alkali content of the developer with a salt of a metal of the group consisting of aluminum, chromium, tin, lead and zinc at such a point that the alkali in the developer is just suflicient to keep the said metal from precipitating in the form of hydroxide, and releasing alkali by precipitation of a salt of the metal of such group as alkaliis required.
• the method of maintaining the alkalinity of a photographic developer effectively constant comprising substantially balancing the alkali content of the developer with alum at such a point that the alkali in the developer is 'just sufficient to keep the aluminum from precipitating in the form of hydroxide, and releasing alkali by precipitation of aluminum hydroxide as alkali is required.
• the method of maintaining thealkalinity of a photographic developer effectively constant comprising adding an excess of alkali to the developer, substantially balancing the alkali content of the developer with alum at such a point that the effective alkalinity is just sufficient to keep the resulting aluminum salt in solution, and releasing alkali by precipitation of aluminum hydroxide.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Silver Salt Photography Or Processing Solution Therefor (AREA)
• Photosensitive Polymer And Photoresist Processing (AREA)

Priority Applications (5)

Applications Claiming Priority (3)

Publications (1)

Family

ID=27393601

Family Applications (2)

Family Applications After (1)

Country Status (4)

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• 1938
  • 1938-04-30 US US205362A patent/US2199903A/en not_active Expired - Lifetime
  • 1938-04-30 US US205363A patent/US2199904A/en not_active Expired - Lifetime
• 1939
  • 1939-01-27 FR FR849548D patent/FR849548A/fr not_active Expired
  • 1939-02-08 BE BE432624D patent/BE432624A/xx unknown
  • 1939-03-03 GB GB7062/39A patent/GB525944A/en not_active Expired

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