US 3091535 A
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United The present invention relates to photographic elements and more particularly it relates to photographic films. Still more particularly it relates to photographic translucent print films having improved antihalation and resolution characteristics.
Photographic emulsions on translucent to opaque film supports have a wide variety of applications in the fields of cartography, transilluminated display and mural Work, drafting and chart work, and technical and sales manuals.
It has been proposed to make such films by coating a photographic emulsion on one side of a transparent film support and coating on the opposite side of the support a translucent layer containing an opaque substance and which may or may not contain an antihalation dye. It has also been proposed to prepare such films by coating on one side of a transparent film support, in order, a slow speed emulsion containing an opalescent substance such as starch or rubber latex and a fast speed silver halide emulsion. On the opposite side there may be coated a plain gelatin layer or a layer containing an antihalation dye. Both of these proposals leave much to be desired in the way of good resolution and antihalation qualities. Further, it has been proposed to coat an antihalation layer between the emulsion layer and the support. This type of structure has some very serious disadvantages. When such elements are exposed and processed, the prints resulting therefrom are often stained in an unsightly manner which results in failure to obtain the desired white background for reflection viewing. This is caused by inadequate bleaching or color destruction during processing due to the presence of the emulsion layer which re tards diffusion of treatment solutions into and out of the non-halation layer. In addition, placing antihalation material in a layer contiguous with the silver halide layer often aifects the sensitometric characteristics by producing fog. Another proposal has been to coat a white water-resistant support with a silver halide emulsion on one side and tinted layer on the opposite side. An alternative method is to coat a tinted support with a white pigment coating on top of which there is coated a silver halide emulsion. These latter elements are also deficient in providing satisfactory resoution and antihalation qualities.
An object of this invention is to provide improved translucent photographic print films. Another object is to provide such films which have improved antihalation and resolution characteristics. Yet another object is to provide such films which are relatively simple in construction and embody commercially available and economical antihalation materials and pigments. A further object is to provide such films which do not produce objectionable stain when the exposed films are developed and fixed. A still further object is to provide such films which can be made by the use of conventional mixing and coating apparatus. Still further objects will be apparent from the following description of the invention.
The photographic elements of the present invention have (1) a transparent hydrophobic copolymer film base, (2) a translucent layer on one side of the base comprising dispersed finely divided particles of an inert inorganic white pigment having an average particle size in the range 0.1 to 2.0 microns in a water-permeable macromolecular atent ice organic colloid of high molecular weight as a binding agent, (3) a photographic silver halide emulsion layer on the translucent layer and on the other surface of the base (4) an antihalation layer comprising a binding agent, colloidal antihalation material, e.g., a dye or pigment, and finely divided particles of a white pigment is described for the translucent layer.
In general, the white pigment is present in an amount from 1.5 to 3.0 parts by weight per part of binding agent. The antihalation dye or pigment in general will be colloidal (in the range of 1 to 100 millimicrons) in their largest diameter. The amount of antihalation material present is that used in conventional antihalation layers and in general comprises 0.05 to 0.10 part per part of binding agent.
The support may be any conventional transparent hydrophobic film such as cellulose esters, e.g., cellulose acetate, cellulose nitrate, cellulose butyrate, cellulose mixed esters; vinyl polymers, e.g., polyvinyl acetate, polyvinyl chloride, polyvinylidene chloride, polystyrenes and copolymers thereof; polyamides, e.g., polypentamethylene sebacamide, polyhexamethylene sebacamide, polypentamethylene suberamide, polydecamethylene adipamide and superpolyesters, e.g., a highly polymeric linear polyester of a dicarboxylic acid with a dihydric alcohol. A prefered type of support comprises a polyester film as disclosed in Whinfield et al. US. 2,465,319 bearing a thin layer of an adherent film-forming essentially hydrophobic copolymer made and coated in the manner taught by Alles et al., U.S. Patent 2,627,088, and Alles, US. Patent 2,779,684, and patents referred to in the specifications of these patents. A film made according to Example IV of Alles US. Patent 2,779,684 which may or may not be coated with a thin gelatin substratum is coated on one surface with an aqueous gelatin dispersion comprising from about 30 to 50% of gelatin and from about 50 to of titanium dioxide based on total dry weight to give a layer having a dry coating weight of about 10mg./dm. of gelatin. Over this layer, any suitable light-sensitive layer may be coated. Gelatino-silver halide emulsions are preferred, however. For example, the variable gamma gelatino-silver halide emulsions dislcosed in Potter et al. US. Patent 2,280,300 have been found to be particularly useful. The type of light-sensitive layer will, however, depend on the manner in which the novel film elements are to be used. On the opposite side of the film there is coated an aqueous gelatin dispersion containing from about 50 to 70% of titanium dioxide and from about .25 to 10% of colloidal manganese dioxide. The layer is coated and dried in a conventional manner to give a dry weight about 70 mg./dm. of gelatin. To increase the utility of the novel film, delustering or matting agents, i.e., silica, starch, etc., may be added to the molten gelatino-silver halide emulsion as a final addition before coating to form a retouchable or drawing surface on the emulsion side of the film. For example, the highly porous siliceous compounds disclosed in Webster US. Patent 2,626,867 are suitable for this purpose.
Titanium dioxides of various crystalline forms may be used as the white pigment, however, the rutile crystalline form is preferred because of its greater hiding power (greater opacity for a given weight). Other white pigments such as barium sulfate can also be used. Likewise, while colloidal manganese dioxide is preferred as the bleachable non-halation coloring component, other bleachable non-halation dyes or pigments, i.e., Aur-amine (C. 1.655), Acid Blue Black (C. 1.246) and Nigrosine (C. 1.864) may be used. Other ingredients for various purposes may be added to any one or all of the layers. For example, so-called optical brightener, i.e., compounds which fluoresce under the influence of visible radiation to increase the brightness of the layers, may be added to the molten gelatino-silver halide emulsion, to the aqueous gelatin-titanium dioxide dispersion and/or to the aqueous gelatin-titanium dioxide-manganese dioxide dispersion as a final addition before coating.
The invention will now be illustrated in and by the following examples, but is not intended to be limited thereby.
Example I A dimensionally stable vinylidine chloride/methyl acrylate/itaconic acid copolymer-coated polyethylene terephthalate film made as described in Example IV of -Alles US. Patent 2,779,684 Was coated on one surface with an aqueous dispersion containing 3.5% gelatin and 7.0% of rutile'crystalline titanium dioxide (Du Pont Ti- Pure R-1-00) based on the total weight and to which had been added a small amount of an alkyl naphthalene sulfonate Wetting agent and a small amount of a bis-triazinostilbene compound as an optical brightening agent. The dispersion was coated at 56 feet per minute to give a dry gelatin coating weight of -mg./dm. Over this layer, there was coated a high speed variable contrast silver iodo-bromide emulsion containing 3% iodide and the rest being silver bromide and 73% gelatin based on total weight of dry solids. The emulsion was coated and dried in a conventional manner. The emulsion was made in the manner described in 'Potter et al. U.S. Patent 2,280,300 and contained 0.12 gram/gram of dry gelatin of highly porous S10 as a matting agent to provide a retouchable surface. There was also added to the molten emulsion before coating a small amount of the above optical brightening agent and 140 mg./mole silver halide of benzotriazole as an antifoggant. The dry coating weight was 33 mg./dm. of silver halide expressed as AgNO On the opposite side of the film there was coated an aqueous dispersion containing 6% gelatin, 12% rutile crystalline titanium dioxide, and 0.4% colloidal manganese dioxide. This aqueous dispersion was coated to give a dry gelatin coating weight of 70 mg./dm.
The resulting photographic film element was exposed by conventional projection enlarging equipment. The
exposed film was developed for 1 /2 minutes at 20 C.
in'a developer having the following composition:
Grams p-Methylaminophenol sulfate 2.5 Hydroquinone 10.0 Sodium sulfite (anhydrous) 37.5 Sodium carbonate, monohydrated 44.0 Potassium bromide 5.0
Water to make 1 liter.
The above developer .was used by diluting with two parts of water. The film was then fixed in a photographic fixer having the following composition:
Sodium thiosulfate grams 240.0 Sodium sulfite, anhydrous do 15.0 'Glacial'acetic acid ml. 47.0 Potassium aluminum sulfate grams 15.0
Water to make 1.0 liter.
ing the film elements for halation, they were exposed behind a neutral wedge with a density range of 0 to 7 over a length of 12 cm. and a mask with a 1 mm. slit with clean cut-edges parallel to theslope of the wedge. Sufficient exposure was given to cause inversion of the image by solaiization under the lightest part of the wedge. At this level of exposure the image of the slit is bordered on either side, at a distance which depends on the thickness of the film support, by two bands due to halation. The efiiciency of antihalation protection can be measured as the ratio of the exposures corresponding respectively to the threshold of halation and the threshold of blackening of the bands.
The resolution was determined by the method outlined in National Bureau of Standards Circular C248, A Test of Lens Resolution for the Photographer.
Opacity was determined as the transmission density to blue light. The measurements below show the comparison of the novel films of the inventions with known structures.
Reso- Anti- Backing Underlayer Opacity lution hala- Stain tion 1. White+bleach- White-l-bleach- 1.10 122. 44 Bad.
able color. able color. 2. White-l-bleach- White 1.10 107 40 None.
able col do 1.10 137 27 Do.
White+bleach-- 1.10 137 36 Bad.
ab color. 5. Single weight paper base 1.30 77 50 Good.
1 The larger the number, the better the antihalation characteristics.
Example I] Example I was repeated except that in place of the variable contrast silver iodo-bromide emulsion of that examplethere was coated a gelatino-silver chlorobromide emulsion. The emulsion contained about 34% silver chloride and the rest silver bromide. The .emulsioncont ained a delustrant-as a matting agent to provide a retouchable surface as is conventional in the art. The dry coating had a weightof 22 mg./dm. of silver-halide expressed as AgNO The backing was coated to a dry weight of v mg./dm. of gelatin (instead of 70 mg./dm; The resulting film had similar characteristics to the film of Example 1. Because of the warm image color and response to direct toning, the product was particularly suited to portrait and photomini-ature application requiring special effects.
Example III Example I was repeated except that in place of the emulsion of that example, there was coated a high contrast contact speed bromochloride emulsion containing 30% silver bromide and 70% silver chloride. The dry coating weight was 22 mg./dm. of silver halide expressed as AgNO The backing was coated to a weight of 40 mg/drn. of gelatin. A planar, non-curling film was obtained whichwas exposed in a conventionalcontact printer for 20 seconds at 15 feet using a single 50 ampere arc lamp. The film was developed for 2 /2 minutes at.20 C. in a developer having the following composition Grams .p-Methylaminophenol sulfate 1.5 Hydroquinone 6.0 Sodium sulfite, anhydrous 19.5 Sodium carbonate, monohydrated 28.0 Potassium bromide 0.8
Water to make 1.0 liter.
The film was then fixed for ten minutes in the fixing composition set forth in Example I. The film showed excellent sensitometric resolution and non-halation characteristics.
Example IV Example I was repeated except that-in place of the silver halide emulsion of that example, there was coated a high contrast direct positive silver chloride emulsion to a dry weight of 35 rng./dm. of silver halide expressed as AgNO The film was exposed through an amber filter to a high intensity mercury vapor lamp. The exposed film was developed for one minute in the developer described in Example '1 but diluted 1:1 with water. The film was fixed for 10 minutes in the fixing composition described in Example I. The resulting direct positive image showed good resolution and non-halation characteristics.
Other emulsions such as cold tone projection and contact speed emulsions may also be coated on the novel film structures to advantage.
All or a portion of the gelatin for the various layers may be replaced by other water-permeable colloids. For example, natural or synthetic, essentially hydirophilic polymers may be used to form the aqueous dispersions. Casein, albumin, interpolyamides, agar-agar, polyvinyl alcohol, polyacrylamides and polyvinylacetals may be used. In addition, certain other polymers or polymer mixtures such as polyvinyl-N-vinyllactams, butadiene-acrylonitrile copolymers, vinyl acetate-vinyl stearate copolymers, styrene-butadiene copolymers, alkyd and acrylic resins may be used in combination with gelatin.
Supports other than those mentioned above are polyethylene terephthalate/isophthalate of the British Patent 766,290 and Canadian 562,672 and those obtainable by condensing terephthalic acid or dimethylterephthalate with propylene glycol, diethylene glycol, tetramethylene glycol or cyclohexane-1,4-dimethanol (hexadydro-p-xylene alcohol).
Other bleachable coloring materials may be used in place of colloidal manganese dioxide although it is preferred because of its greater stability under adverse storage conditionings. For example, the coloring materials disclosed in Baldsiefen, US. Patent 2,203,7 67 may be used.
Other white pigments may be used in place of the rutile crystalline titanium dioxide mentioned above, e.g., barium sulfate, calcium sulfate and zinc oxide.
The unexpected and advantageous result is that the antihalation and resolution characteristics of the novel structure are surprisingly good. The following is a comparison of the characteristics of prior art structures with those of the novel structures of the instant case.
Sensito- Backing Under layer Anti- Stain metric Halation Compati bility White-i-bleachable White+bleach- Good.... Bad... Poor.
color. able color.
Do Whflite pigment --do.--. None Good.
y. White only. White only P0or.... .do Do. Do White bleach- .--do Bad-.- Poor.
photographs, commercial displays, murals, education devices, etc.
For all applications, the planar, non-curling characteristics offer superior advantages over paper based products. For example, because of the durability of the films of the instant invention they are especially applicable to making sales manuals and instruction charts, etc.
In addition, because of the superior dimensional stability of the novel films they are especially useful in the field of aerial mapping and general survey mapping.
For transilluminated displays, a striking effect can be achieved by coloring only the side opposite the silver halide emulsion layer with appropriate colors. With reflection lighting only, the print appears black and white, but with transmission lighting the image appears in color. In this application, non-penetrating coloring matters are most suitable.
What is claimed is:
1. A translucent photographic print film comprising (1) transparent hydrophobic copolymer film base,
(2) a translucent layer on one surface of the base comprising dispersed finely divided particles of an inert inorganic white pigment having an average particle size in the range 0.1 to 2.0 microns in a waterpermeable macromolecular organic colloid of high molecular weight as a binding agent, there being 30 to 50%, by weight, of colloid and 50 to by weight, of said pigment,
(3) a photographic silver halide emulsion layer on the translucent layer, and on the other surface of the base (4) an antihalation layer comprising a water-permeable colloid binding agent, bleachable colloidal antihalation material and finely divided particles of the white pigment and having the particle size defiined in layer (2), said antihalation layer having a coating weight of 40 to mg. per sq. dm. of colloid, there being present about 50 to 70% of the white pigment and about 0.25 to 10% of the antihalation material, based on the colloid.
2. An element according to claim 1 wherein said pigment is titanium dioxide.
3. An element according to claim 1 wherein said pigment is titanium dioxide, the binding agent is gelatin and layer (2) has a coating weight of about 10 mg. per sq. dm. of gelatin.
4. A photographic print film as set forth in claim 1 wherein said colloid binding agent in each of layers (2) and (3) is gelatin.
5. A photographic print film as set forth in claim 1 wherein said antihalation material is manganese dioxide.
6. A photographic print film as set forth in claim 1 wherein said emulsion layer is a gelatino silver iodobromide emulsion layer.
References Cited in the file of this patent UNITED STATES PATENTS 1,597,727 De Sperati Aug. 31, 1926 1,631,421 Lohofer June 7, 1927 2,095,018 Wilmanns et a1. Oct. 5, 1937 2,313,570 Nadeau et al Mar. 9, 1943 2,698,235 Swindells Dec. 28, 1954 2,773,769 Goldschein Dec. 11, 1956