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
  • G03C5/18—Diazo-type processes, e.g. thermal development, or agents therefor

Definitions

• the invention relates to a process for developing diazotype copies according to the so-called semi-dry method, and to novel developer compositions for use in said process.
• the invention is more particularly concerned with a process, in which a thin layer of an acid-reacting, aqueous, buttered developing liquid, which contains phloroglucinol as the sole or as the principal coupling component, is spread over the surface of imagewise exposed one-component diazotype paper, which has been sensitized with a diazo compound of the formula:
• R and R are methyl or ethyl groups, and in which, when R is a methyl group, R may also be a cyclohexyl group, and Ar is a phenyl radical, or a phenyl radical carrying at most two substitutents.
• one-component diazotype material is normally developed according to the so-called thin-layer method.
• a thin layer of an aqueous buttered developing liquid is uniformly spread over the light-sensitive side, and, in order to promote the flatness of the developed copies, often also over the non-light-sensitive side of the i magewise exposed diazotype material.
• the quantity of developing liquid applied on one side of the diazotype material is normally expressed in the number of grams of liquid per m? of material. If the quantity is small, such as 6-9 g./m. the developing method is called semi-wet or semi-dry.
• Developing liquids which are suitable for this method have to be very reactive, which means that they have to neutralize rapidly the acid that is present in the diazotype material and the acid that is liberated in the azo-dyestuif formation, and they have to contain actively coupling azo components.
• an azo component is phloroglucinol.
• In practice use is made of Weakly acid and weakly alkaline developing liquids which contain phloroglucinol.
• the weakly acid developing liquids can be buttered with ammonium, alkali metal, or alkaline earth metal salts of weak acids such as formic acid, acetic acid, succinic acid, malic acid, citric acid, tartaric acid, benzoic acid, phenylamido acetic acid, molybdic acid, tungstic acid, stannic acid, phosphoric acid, phthalic acid, glutaric acid, adipic acid, fi-methyladipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, isosebacic acid, antidimethylsuccinic acid, aspartic acid, glutamic acid, itaconic acid, Z-ethyI-suberic acid, 2,5-dimethyladipic acid, and propane tricarboxylic acid. See British patent specification 425,- 235 and British patent application 31,362/60.
• the weakly acid developing liquids applied in practice have a pH between 5 and 7 and generally have very good keeping qualities. They are used for developing diazotype materials which have been sensitized with a very actively coupling diazo compound, such as pdiazo-2,5- dicthoxybenzoylamidobenzene, p diazo 2,5 diethoxy- (4-methyl)-phenylmercaptobenzene, and p-diazo-2,5-diethoxy (4 methoxy) phenylbenzene. They are not suitable for the development of diazotype materials which have been sensitized with less actively coupling diazo com pounds, because in that case the coupling of the phloroglucinol with the diazo compound takes place so slowly that complete development is not obtained.
• a very actively coupling diazo compound such as pdiazo-2,5- dicthoxybenzoylamidobenzene, p diazo 2,5 diethoxy- (4-methyl)-phenylmercaptobenzene, and
• the keeping qualities of the weakly alkaline developing liquids containing pholorglucinol are not nearly so good. Their pH lies between 7 and 10.
• As buffer salts for these developing liquids the alkali metal salts of acetic acid, propionic acid, adipic acid, citric acid, maleic acid, phthalic acid, carbonic acid, phosphoric acid, and boric acid have been proposed. In practice carbonate, phosphate, and borate buffers are mainly used in the weakly alkaline developing liquids.
• the weakly alkaline developing liquids are used to develop diazotype materials which contain rather slowly coupling diazo compounds, such as p-diazo-N-ethyl-N- benzylaniline and p-diazo-o-chloro-diethylaniline.
• British patent application 37,797/59 and British patent application 7,359/ 61 describe diazotype papers which have been sensitized with diazo compounds according to the formula OAr in which X is an anion or anionic group, R and R are methyl or ethyl groups, and in which, when R is a methyl group, R may be a cyclohexyl radical, and Ar is a phenyl radical or a phenyl radical carrying at most 2 substituents.
• diazotype papers are very interesting because of their great light-sensitivity and the possibility of developing them With a Weakly acid phloroglucinol developer according to the thin layer method, in which they yield, both in the non-exposed and in the partly exposed portions, azo-dyestuiis with the same colour Without any inconvenient additional shade.
• a Weakly acid phloroglucinol developer according to the thin layer method in which they yield, both in the non-exposed and in the partly exposed portions, azo-dyestuiis with the same colour Without any inconvenient additional shade.
• weakly acid developing liquids containing phloroglucinol which have been buffered with formate, benzoate, citrate, they develop into black azo-dyestutfs, but the development often proceeds slowly and/or incompletely.
• the diazotype paper has to be heated after the application of the thin layer of developing liquid in order to ensure a fast and, at the same time, complete development.
• This developing liquid effects a distinctly faster and more complete development of these diazotype papers than the conventional weakly acid developing liquids, particularly also when its temperature is on the low side and the copies are not heated after the application of the developing liquid.
• the process according to the invention is very suitable for application in oflices using simple photo-printing machines. These machines are preferably equipped with a light-source that can be switched on and off at any time.
• Suitable light-sources of this kind are actinically fluorescent low-pressure mercury vapour lamps, which, how ever, do not have a particularly great luminous intensity. In machines equipped with such lamps, very light-sensitive materials are therefore preferably used.
• the diazotype papers which are used in the process according to the invention are very light-sensitive and have reasonable keeping qualities.
• the developing liquid too has good keeping qualities. Moreover it has a lesser tendency to dry up in the developing machines, as compared with the conventional weakly acid developing liquids, which often form inconvenient crystal crusts. All this prevents fouling of the machines and is very important if the developing liquid is used in a developing device with liquid-applying rollers provided with capillary grooves according to British patent specification 544,882.
• Developing liquids according to the present invention may be prepared by dissolving in water, besides the usual substances such as the azo component, reducing agents such as thiourea, stabilizers such as hydroquinone monosulphonic acid, wetting agents, substances which counteract the discoloration of the developing liquid, such as a very small quantity (5% of the total quantity of buffer salt for instance,) of sec. alkali phosphate, the desired quantity of maleic acid or maleic anhydride and then adjusting the pH of the liquid to the correct value with potassium hydroxide solution or lithium hydroxide solution.
• the azo component such as thiourea
• stabilizers such as hydroquinone monosulphonic acid
• wetting agents such as a very small quantity (5% of the total quantity of buffer salt for instance,) of sec. alkali phosphate, the desired quantity of maleic acid or maleic anhydride and then adjusting the pH of the liquid to the correct value with potassium hydroxide solution or lithium hydroxide solution.
• the developer may contain a relatively small quantity of one or more other buffer salts. These can be added as such, but the acids forming such buffer salts can also be used.
• the developer may be formulated as a ready-for-use liquid, or in the form of powder mixtures or tablets, which have to be dissolved in the requisite quantity of water before use.
• Example 1 White base-paper of weight g./m. and suitable for the diazotype process is sensitized with a solution of:
• the light-sensitive side of a sheet of the diazotype paper is covered with a sheet of tracing-paper, on which a pencil drawing has been made, and exposed in a printer equipped with actinically fluorescent low-pressure mercury vapour lamps.
• the latent diazotype copy obtained is developed according to the semi-dry method by applying on the image side a layer of 9 g./m. of a deveolping liquid of the following composition:
• the developer has excellent keeping qualities. With a conventional acid developer with an equivalent quantity of sodium formate, which has the same pH, the paper is developed markedly less rapidly and completely, especially when the temperature of the developing liquid is on the low side.
• Example II White base-paper of weight 80 g./m. and suitable for the diazotype process is sensitized with a solution of:
• a sheet of the diazotype paper is imagewise exposed as described in Example I. The endpoint of the exposure is soon reached.
• the latent diazotype copy thus obtained is developed according to the semi-wet method by applying on the image side a layer of approximately 8 g./m. of a developing liquid of the following composition:
• the developing liquid has a pH of 6.8 and a temperature of 18 C. This is also the temperature of the room.
• the azo-dyestuff has a fine black colour and does not show any oil-shades.
• the developer dries very slowly on the parts of the developing device which are moistened with it.
• a conventional acid developer of the same temperature (18 C.) such as that described in Example II of British patent application 7,359/61, the image also soon becomes visible.
• the pH of that developer has also been adjusted to 6.8.
• the copies consequently are rather faint.
• This developer dries much faster in the developing device, While inconvenient crystals are formed.
• Example III White base-paper of Weight 80 g./m. and suitable for the diazotype process is sensitized with a solution of:
• the copy is developed rapidly and completely, the image becoming visible immediately after the application of the developer.
• the azo-dyestuff is black and does not show any oiT-shades.
• the developer has very good keeping qualities and does not give any difiiculties with respect to crystallization.
• R and R are selected from the class consisting of methyl groups, ethyl groups, a methyl group and an ethyl group, and a methyl group and a cyclohexyl group
• Ar is a phenyl radical carrying at most two substituents, a thin layer of an acid-reacting, aqueous, buttered developing liquid, which contains phloroglucinol as at least the principal coupling component, and which contains alkali metal maleate selected from the class consisting of potassium maleate, lithium maleate and mixtures thereof as the principal bufier salt and has a pH between 6.5 and 7.
• a developer composition for one-component diazotype material which comprises phloroglucinol as at least the principal coupling component, which contains as the principal buffer salt alkali metal maleate selected from the class consisting of potassium maleate, lithium maleate and mixtures thereof and which has in aqueous solution a pH of 6.5 to 7.
• a developer composition for one-component diazotype material which comprises phloroglucinol as at least the principal coupling component, which contains dipotassium maleate as the principal butter salt and which has in aqueous solution a pH of 6.5 to 7.
• a developer composition for one-component diazotype material which comprises phloroglucinol as at least the principal coupling component, which contains dilithium maleate as the principal buffer salt and which has in aqueous solution a pH of 6.5 to 7.
• a developer composition for one-component diazotype material which comprises phloroglucinol as at least the principal coupling component, which contains as the principal bufier salt a mixture of dipotassium and dilithium maleates and which has in aqueous solution a pH of 6.5 to 7.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Non-Silver Salt Photosensitive Materials And Non-Silver Salt Photography (AREA)

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Citations (6)

• 0
  • NL NL268816D patent/NL268816A/xx unknown
• 1962
  • 1962-08-22 GB GB32338/62A patent/GB957837A/en not_active Expired
  • 1962-08-29 SE SE9374/62A patent/SE315796B/xx unknown
  • 1962-08-29 US US220129A patent/US3261684A/en not_active Expired - Lifetime
  • 1962-08-30 CH CH1033762A patent/CH425462A/de unknown
  • 1962-12-19 GB GB47920/62A patent/GB961515A/en not_active Expired
• 1963
  • 1963-12-17 FR FR957418A patent/FR1378466A/fr not_active Expired

Patent Citations (7)

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