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
  • G03C1/52—Compositions containing diazo compounds as photosensitive substances
  • G03C1/61—Compositions containing diazo compounds as photosensitive substances with non-macromolecular additives

Definitions

• the invention relates to diazotype compositions and their use in diazotype.
• diazotype reproduction prints are obtained by an imagewise exposure of a light-sensitive diazo material to ultraviolet light followed by development of the exposed diazotype material.
• a light-sensitive diazo material to ultraviolet light
• the light-sensitive diazo material generally comprises a light-sensitive diazo composition affixed to a support base such as paper or film such as polyethylene terephthalate film, cellulose acetate, or a polymeric resin coated, like base support.
• the light-sensitive diazo composition may comprise a light-sensitive diazonium salt compound in admix­ture with diazo enhancing compounds.
• the unmasked portions of the diazonium salt are decomposed by the ultrviolet radiation whereas the masked portions are left undecomposed.
• the latent image created by the image-­wise exposure may then be developed by the methods described above.
• the light-­sensitive diazo composition will contain, in addition to the light-sensitive diazonium salt, an azo coupling agent or color former and an acidic coupling inhibitor.
• Development of the latent azo dye image is accomplished by placing the exposed diazo material in an alkaline atmosphere which neu­tralizes the acidic inhibitor, allowing the undecomposed diazonium salt and coupler to react. The latent image is thereby developed.
• the light sensitive diazo composition contains essentially the diazonium salt compound.
• development of the latent azo dye image is accomplished in a pH adjusted solution containing at least one coupler to react with the undecomposed diazonium salt.
• the diazotype compositions generally contain other stabilizing salts, anti­oxidants for improved print stability, development accelera­tors and solubilizing compounds for adequate compatability of all active components in the sensitizing solution.
• the commonly used diazo compounds are benzene diazonium salts with various substitutions in the benzene ring and they are more or less ionized into the diazonium cation and the anion of the acid of the salt.
• diazo couplers are aromatic compounds with enolic character or are compounds with active methylene groups.
• the couplers depending on radicals substitution in their molecule, may have anionic or cationic character. Diazos and couplers in the sensitizing solution, dpending on their ionic character and radicals substitutions may form salts and/or complex compounds of different degrees of solu­bility.
• the most widely used antioxidizer is thiourea which is also known to form complex compounds asnd thus afffects dye shade.
• Development accelerators are often various glycols, allylhydroxethylthiourea and substituted ureas. These com­pounds of polaric character easily complex azo (print) dyes thereby affecting dye shade.
• xanthane derivatives such as caffeine.
• Caffeine is also a solubilizer for may azo dies and probably because of its complexing action, affects the dye shade.
• Solution compatibility is or prime importance for the diazotype coating process since it is the basis for obtaining an even coating application in the preparation of the base support.
• Additives for other specific purposes such as improve­ment of solution stability, shelf life of sensitized paper and rate of development, often affect the print shade in a highly unsatisfactory manner, shifting blackline print colors all the way between blue and brown containing substantial reddish components.
• the present invention overcomes the shortcomings described above.
• the class of compounds used in this invention function as a solubilizer and as a stabilizer to replace all or at least a substantial portion of the other­wise necessary stabilizing acids such as citric-, sulfosali­cylic-, and sulfuric acids and commonly used solubilizers, such as for example caffeine, theophyllin, dialkylureas and alkyl-hydroxy-ethyl thiourea.
• solubilizers such as for example caffeine, theophyllin, dialkylureas and alkyl-hydroxy-ethyl thiourea.
• the invention comprises the use of compounds of the formulae:- wherein X represents the cation of a metal or the cation formed by the addition of a proton to the nitrogen atom of an amine base selected from the group consisting of ammonia, urea, a dialkylurea, an organic alkylamine, a mono-, di-, or trialkanolamine, an aralkylamine or a heterocyclic nitrogen base amine; and wherein Y represents the multivalent cation of an alkylene diamine or piperazine; as solubilizers and stabilizers in diazotype reproduction materials asnd diazotype materials.
• the invention also comprises the method of using the compounds (I) and (II) in diazotype reproduction materials (compositions) of the invention.
• metal as used herein to describe salts of the 5-sulfosalicylic acid is embracive of alkali metals such as lithium, sodium, potassium, and the like.
• alkylene is used herein to mean the divalent moiety obtained upon removal of two hydrogen atoms from a parent hydrocarbon.
• Representatives of alkylene are alkylene of 1 to 6 carbon atoms, inclusive, such as methylene, ethyl­ene, propylene, butylene, pentylene, hexylene and the like.
• the above-described acidic salts of formulae (I) and (II) may be used alone or in admixture with salts of 5-­sulfosalicylic acid in which both the sulfonic radical and the carboxylic radical, are neutralized.
• the sulfosalicylic acid salts of the formulae (I) and (II) are easy to prepare at a low cost and their use results in a cost saving when compared with the more expensive caffeine, theophyllin and alkyl hydroxyethyl thiourea together with the acid stabiliz­ers which they replace in the compositions of the invention.
• the compounds of the formulae (I) and (II) given above are well known salts of 5-sulfosalicylic acid, as are the methods of their preparation.
• the compounds of the formula (I) wherein X represents the cation of an alkali metal may be prepared by reacting stoichiometric proportions of 5-sulfosalicylic acid with a salt of the metal.
• reaction may be carried out over a broad range of tem­peratures and pressures, neither being a critical parameter of the reaction.
• the reaction is carried out at a temperature within the range of from about 0°C to about 100°C, preferably at room temperature (circa 26°C) and under atmospheric pressures.
• the reactions are generally complete within minutes and are indicated by precipitation of the desired product com­pounds of the formulae (I) and (II) given above, in the reac­tion mixture.
• Precipitation usually occurs without further treatment of the solution, although under certain conditions, it may be desirable to initiate precipitation of the product salts by cooling the reaction mixtures, seeding the solution or adding some sodium chloride or like salt to reduce the solubility of the product salts in the reaction mixture.
• the desired salts of the formulae (I) or (II) are readily separated from the reaction mixture by conventional technique such as by filtering, washing and recrystallization.
• amine bases may be employed to prepare the compounds of the formulae (I) and (II) described above.
• X in the for­mula (I) will be the ammonium cation.
• urea or a dial­kylurea are used, the X will represent the corresponding cation of the base.
• dialkylurea is used herein to mean urea wherein a hydrogen atom on each of the two nitrogen atoms is replaced with an alkyl group.
• alkyl is used throughout the specification and claims as meaning the monovalent moiety obtained by re­moval of a hydrogen atom from a parent alkane, which latter for example, contains 1 to 12 carbon atoms.
• Illustrative of such moieties are alkyl of 1 to 12 carbon atoms, inclusive, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl and isomeric forms thereof.
• dialkylureas are dimethylurea, dibutylurea, dihexylurea and the like.
• Alkylamines employed to prepare the compounds of formula (I) given above are compounds of the formula:- H2N-R (III) wherein R represents alkyl as defined above.
• Representative of alkylamines are methylamine, propylamine, butylamine, hexylamine and the like.
• the aralkylamine bases are com­pounds of the formula (III) given above wherein R represents aralkyl.
• the term "aralkyl” is used to mean the monovalent moiety obtained upon removal of a hydrogen atom from the alkyl portion of an alkyl-substituted aromatic hydrocarbon. Representative of aralkyl are benzyl, phenethyl, phenpropyl, phenbutyl and the like.
• Heterocyclic nitrogen base amines are generally well known compounds, represented by morpholine and piperidine.
• the alkylene diamines are also generally well known compounds and include ethylene diamine, propylene diamine, hexylene diamine and the like.
• the alkylene diamines employed to prepare the compounds of formula (II) will have 1 to 6 carbon atoms, inclusive.
• the mono-, di- and tri-alkanolamines are also a well known class of compounds as are methods of their preparation.
• Representative of the class of compounds are ethanolamine, 2-amino-l-propanol, 3-hydroxypropylamine, diethanolamine, triethanolamine and the like.
• diazo compositions for the two-component diazotype process comprise at least one light-­sensitive diazonium compound, at least one azo coupler and acidic stabilizers which are necessary to obtain a diazotype copy.
• the term "light-sensitive” as used herein means the compound or material undergoes photolytic decomposition.
• any of the conventionally employed, light-sensitive diazonium compounds may be employed.
• Aromatic para amino and para mer­capto substituted diazo compounds of more or less pronounced yellow color and which absorb ultraviolet light to undergo a photolyitic decomposition to colorless products are advanta­geously used.
• azo couplers are mixed with the diazonium compounds in an acid environment to prevent precoupling.
• the coupling reaction occurs to produce an azo dye as is known in the art.
• Azo couplers are generally aromatic compouds with phenolic hydroxyl group ⁇ with or without other substituent groups.
• the proportions of the various components of the comp­sitions of the invention described above may be those pro­portions conventionally used in their use prior to this invention, in the preparation of prior art diazo light-­sensitive compositions (where they were so used). These proportions are well known to those skilled in the art; see for example the disclosure of Kopsar, supra and of U.S. Patents 3,923,518 and 3,996,056.
• the aqueous diazo coating compositions contain from about 0.1 to about 10 percent by weight of the light-sensitive diazonium com­pound and sufficient coupler to react with and couple the diazonium compound upon development.
• a necessary ingredient of the diazo coating compositions of the invention is a stabilizing proportion of a compound of the formulae (I) and/or (II) given above.
• a stabilizing proportion is one which will maintain the desired acid pH of the diazo coating until development occurs.
• a stabilizing proportion of the compounds as represented by those of the formulae (I) and (II) given above will be within the range of from about 5 gms to 200 gms (preferably 20 gms to 70 gms) for each liter of aqueous diazo coating composition to be stabilized.
• the proportion of the compounds (I) and (II) is one within the range of from 1 to 5 parts by weight for each part by weight of the light-­sensitive diazonium compound.
• the compounds (I) and/or (II) may be used as the sole stabilizer, or they may be used in conjunction with reduced conventional proportions of previ­ously known acid stabilizers employed in diazotypy. Repre­sentative of such prior art acid stabilizers are citric acid, tartaric acid, hydrochloric acid, sulfuric acid, boric acid, mixtures thereof and the like.
• the light-sensitive diazo coating compositions of the invention may contain any number of additional ingredients conventionally used in the preparation of prior art light­sensitive diazo coating compositions such as, for example,
• the diazo compositions of the invention may be prepared by bringing the ingredients together in a suitable vessel.
• the diazo compositions of the invention are prepared in an aqueous media for use as an aqueous coating mixture to prepare diazotype reproduction materials of the invention.
• precoating it is possible to add one or more components to a precoat preparation and at least one of the remaining components of the compositions of this invention to a secondary coating preparation.
• the diazotype reproduction materials of the invention may be prepared by coating aqueous mixtures of the diazo compositions of the invention on a suitable base support material, using conventional diazo coating apparatus.
• suitable base supports are opaque paper, translucent papers, polymeric resin films, and like supports. Preferred are the commer­cially avilable diazobase papers.
• Diazotype sheets are exposed for 24 hours at 50°C to an atmosphere of 50% and/or 75% relative humidity. This is done by suspending sample sheets of sensitized diazotypes in a closed box over a supersaturated solution of potassium car­bonate (50% R.H.) and in another closed box over a supersa­ turated solution of sodium chloride (for 75% R.H.); and the boxes being placed inside an oven at 50°C. Thereafter they are half covered with a black opaque sheet and exposed to UV light in the printing section of a diazo copying machine, sufficiently to decompose all diazo in the non- covered area.
• the sheets are then fully developed with ammonia by passing the diazotype sheet through the developing section of a dia­zotype copying machine.
• a fresh sheet of the same diazotype paper is also half covered with a black opaque sheet and printed and developed in the same manner.
• the resulting prints are then compared as to their loss of full tone print color density and discoloration of their print background brightness in the light exposed areas.
• the loss of print color and the degree of print background discoloration are an indication of their useful shelf life.
• the aging test with a 50 percent relative humidity (R,H.) atmosphere in general, reflects a normal shelf life of 3 months.
• the aging test with a 75 percent R.H. atmosphere reflects behaviour under extremely adverse conditions.
• Example 2 show that the sodium sulfosali­cylate not only replaces conventional acids such as citric-, tartaric- or p-toluenesulfonic-acid as a stabilizer for shelf life, but also acts as an active solubilizer for solution compatability of the various diazotype components.
• Example 3 show that the use of sodium sulfosalicylate with or without citric acid in the diazotype sensitizing solution instead of citric acid alone improves solution compatibility and allows the use of sensitizing solutions at room temperature and avoids the need for heating solutions during the coating operation.
• sulfosalicylic acid salts of the invention does not exclude their appliction in con­juction with conventional stabilizing acids or solubilizing compounds, in particular if some special effects from such compounds are useful for the particular application.
• diazotype paper When the clear solutions G and H were applied to a precoated paper in a conventional diazotype coating machine, diazotype paper was obtained which, when image-wise exposed and developed; with ammonia, resulted in blackline prints of equally good print contrast and brightness, although the paper obtained with solution H had more grey neutral half tones than the paper obtained with Solution G which exhibited more reddish half tones.

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• Physics & Mathematics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• General Physics & Mathematics (AREA)
• Non-Silver Salt Photosensitive Materials And Non-Silver Salt Photography (AREA)
• Heat Sensitive Colour Forming Recording (AREA)

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Citations (2)

• 1987
  • 1987-08-25 EP EP87112341A patent/EP0277273A1/de not_active Withdrawn

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