US2106868A - Method of obtaining photographic contrasts - Google Patents

Method of obtaining photographic contrasts Download PDF

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Publication number
US2106868A
US2106868A US758332A US75833234A US2106868A US 2106868 A US2106868 A US 2106868A US 758332 A US758332 A US 758332A US 75833234 A US75833234 A US 75833234A US 2106868 A US2106868 A US 2106868A
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Prior art keywords
light
exposure
layer
coloring matter
formation
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Expired - Lifetime
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US758332A
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English (en)
Inventor
Boer Jan Hendrik De
Klaassens Klaas Hinderikus
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Koninklijke Philips NV
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Philips Gloeilampenfabrieken NV
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    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B5/00—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture
    • C03B5/16—Special features of the melting process; Auxiliary means specially adapted for glass-melting furnaces
    • C03B5/20—Bridges, shoes, throats, or other devices for withholding dirt, foam, or batch
    • 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

Definitions

  • the formation of- ,photographic contrasts is obtained by means of an actinic exposure of a self-developing layer sensitized by means of a na'phthalene diazonium l0 compound.
  • self-developmen By the term self-developmen ",'as used herein, is meantpthe propertyofforming, as a result of and subsequently to an exposure to actinic light,v 5 coloring matter by means of the union between the light decomposition product-formed from .a4
  • diazonium compound in the light sensitive layer during the exposure-and the available excess of diazonium compound; without the addition of any further chemical reagents such as ammonia gas or alkaline solutions, and correspondingly a lightsensitive material having such property, is referred to as self-developing", which promotes the obtention of a minimum moisture content of the layer.
  • naphthalene diazonium* compounds are'used as self-developing materials, which compounds, under the conditions more fully to be described hereinafter, give a material of greater stability than can be 'obtained with the self-developing ⁇ layer formed with benzenediazonium compounds.
  • the ingor being mamedxum having.
  • Figure l is a diagram showing the dependency of the formation speed of the coloring matter upon the pH value (acidity or alkalinity) of the light-sensitive material.
  • Fig. 2 is a diagram showing the relation between the intensity of the nal coloring obtained and the amount of actinically acting light striking the light-sensitive layer.
  • the abscissae give the pH values of the light-sensitive layer, whereas the ordinates give the corresponding formation speed of the coloring matter.
  • the curve 8 represents the formation speed of the coloring matter for a given moisture content of the layer and for different pH values (acidities and alkalinities) of the light-sensitive layer.
  • the line I0 which is parallel to the abscissa. axis, represents the speed of photochemical decomposition for a given light intensity or actinic light energy falling on the light-sensitive layers during the exposure.
  • the diagram is shown to be divided, according to the pH value of the light-sensitive layer, into three zones ⁇ marked A, B and C. Of these zones, zone A extends from the ordinate axis to the ordinate through point I, the latter point falling somewhat to the right of the point I2 (which corresponds to the pH value 'l or chemical neutrality), the point I representing the alkalinity at which the formation speed of coloring matter is rst discernible.
  • the zone B extends from the ordinate passing l through point I to the ordinate passing through point 2, which latter point is the intersection of the curve 8 with the linev I0, While the zone C extends towards the right of zone B.
  • the diazonium compound can be photochemically decomposed.
  • no formation of coloring matter can take place either during the actual exposure under the template, or thereafter when keeping the exposed print in the dark, and therefore the zone A is unsuitable for the purpose of the invention.
  • zone C the formation speed of the coloring matter is greater than is the. speed of the decomposition of the diazonium compound and therefore the formation of coloring matter takes place so rapidly during the exposure that no copying out is possible, even by means of the most intensive available light sources.
  • zone B which extends from layers having slight alkalinity to layers having moderate alkalinity, it will be noted that the formation speed of the coloring matter, while increasing toward the right, remains smaller thanthe speed of photochemical decomposition.
  • light-sensitive layers having pH values falling within the zone B can be copied out and subsequently produce coloring matter by self-development
  • the zone B is, therefore, the only zone which is suitable for the process of the invention and to obtain a reasonable formation speed of the coloring matter it is desirable to work in the right-hand portion of this zone, although preferably staying a reasonable distance to the lef-t of the point 2, as too close an approach to point 2 increases the danger "of coloration during the exposure:
  • theformation speed of the coloring matter alsodepends upon the quantity of moisture which the light-sensitive layer possesses or is capable of taking up during exposure, and the formation speed decreases with decreasing moisture content and vice versa.
  • the dotted curve 9 represents the formation speed of the coloring matter for a moisture cori tent 1owe ⁇ r ⁇ than in the case of curve 8.
  • the zone B can be extended by using either a higher light intensity for the exposure or a lower moisture content of the light-sensitive layer.
  • the extension of the useful zone B is limited Y by the fact that a very high alkalinity will so strongly increase the formation speed of the co1- oring matter as to prevent the possibility of copying out.
  • Fig. 2 The importance of the proper relationship between th ⁇ e speed of photochemical decomposition of the diazonium compound and the formation speed of the coloring matter by self-development will further appear from Fig. 2.
  • curve AIl gives the intensity of the final coloring obtained as a function of the amount of actinically-active light striking the light-sensitive layer during the exposure.
  • abscissae give the amount of actinic light and the ordinates the intensity of the resulting-coloring.
  • a positive is made of a tracing whereby, in the print obtained, upon actinic exposure of the light-sensitive layer, the portion corresponding to the lines of the tracing which will remain either unexposed or only slightly exposed to light, appear as colored lines, whilethe blank and thus transparent portions of the tracing will cause the corresponding portions of the print to be fully exposed and thus to appear uncolored.
  • a positive from a positive is obtained.
  • the self-development of 'the print may take place in the dark or by subjecting the print, after removal of the tracing, to a slightly actinic light. In this latter case an equal and small amount of light uniformly strikes all of portions of the photographic layer, this amount of light being in.
  • the intensities of the final coloring are represented by the ordinate -1 corresponding to the amount of light 6, and is practically zero corresponding to the amount of light 5. It will be thus noted that at the pointsv 4 and 5 the light intensity is so great that the entire diazonium compound becomes decomposed, and
  • the sensitive carrier for ⁇ instance the paper carrying' the light-sensitive substance
  • intensive drying in such a manner that the paper retains a moisture content of less than 1%.
  • Such intensive drying may also be achieved by subjecting the material to'a ow of 'moisturemoisture by freezing out 'the moisture from the v gas at a very low temperature.
  • Example 1 The sensitized photographic material adapted for making prints from tracings is obtained by soaking a suitable paper carrier in a solution of 1% 1diazlmium-Z-hydroxynaphthalene-i-sulfoacid (1 mol.) +0.6% anhydrous sodium carbonate in water, and by subsequently drying it in air.
  • the sensitized paper is exposed under a template, for instance a tracing, for a time interval of about three minutes, and using as a light source, for instance a 5 kw. incandescent ⁇ iilament lamp placed at a distance of about 25 cm. from the template.
  • a template for instance a tracing
  • a light source for instance a 5 kw. incandescent ⁇ iilament lamp placed at a distance of about 25 cm. from the template.
  • the so-exposed paper is then allowed to remain in the dark during which the self-development takes place, which may be accelerated by the presence of water vapor.
  • the self-development may also be accelerated by putting a moistened cloth heated to a temperature of about 100 C. on the paper.
  • a positive is obtained from a positive and the image has a brownish-yellow tone. If the quantity of anhydrous sodium carhas been stated before. the sensitized paper is subjected to intensive drying before being used for the exposure. With the moisture content thus minimized, the formation speed of the coloring matter during the exposure is so reduced thatno coloring whatsoever takes place at the lfully exposed portions.
  • sodium carbonate other alkaline agents, especially salts giving slightly alkaline reaction,.are suitable for carrying out the invention, for example, sodium borate (Nemici-10H30),
  • NaaPO4.10H2O sodium phosphate
  • NazSeOa sodium selenite
  • the step of imparting to said layer prior to exposure a pH value lying within a range having an upper limit corresponding .to the point at which there will be substantially no formation of coloring matter during the exposure and a lower limit greater than '7 and corresponding to the point at which the color formation subsequent to the exposure can be obtained solely by the influence of water and withcait ⁇ the addition and removal of any chemical substance.
  • the method of producing photographicprints comprising the steps sensitizing a layer with a naphthalene diazonium compound, alkalizing the layer to give same a pH value less 'than that value at which there will be substantially no formation of coloring matter during the exposure and more than that value at which the color formation can be obtained solely by the influence of water and without the addition or removal of any chemical substance, drying the layer to reduce its moisture content to below 1%, selectively exposing the layer to actinic light to partially decompose the diazonium compound on selected portions without the formation of appreciable coloring matter, and wet-ironing the exposed layer at .a temperature of about 100 C.
  • JAN HENDRIK m BOER.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Organic Chemistry (AREA)
  • Paper (AREA)
  • Heat Sensitive Colour Forming Recording (AREA)
  • Non-Silver Salt Photosensitive Materials And Non-Silver Salt Photography (AREA)
US758332A 1933-12-27 1934-12-19 Method of obtaining photographic contrasts Expired - Lifetime US2106868A (en)

Applications Claiming Priority (1)

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DE433586X 1933-12-27

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US2106868A true US2106868A (en) 1938-02-01

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BE (1) BE407017A (en))
FR (1) FR783321A (en))
GB (1) GB433586A (en))

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2571671A (en) * 1946-01-18 1951-10-16 Hartford Nat Bank & Trust Co Process of producing photographic contrasts
US2571670A (en) * 1946-01-21 1951-10-16 Hartford Nat Bank & Trust Co Method of producing photographic contrasts
US4094681A (en) * 1975-10-23 1978-06-13 Trans World Technology Laboratories, Inc. Image amplification of negative-working diazo materials

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2571671A (en) * 1946-01-18 1951-10-16 Hartford Nat Bank & Trust Co Process of producing photographic contrasts
US2571670A (en) * 1946-01-21 1951-10-16 Hartford Nat Bank & Trust Co Method of producing photographic contrasts
US4094681A (en) * 1975-10-23 1978-06-13 Trans World Technology Laboratories, Inc. Image amplification of negative-working diazo materials

Also Published As

Publication number Publication date
GB433586A (en) 1935-08-16
BE407017A (en))
FR783321A (fr) 1935-07-11

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