GB2027431A - Photographic Dye Images and Colour Couplers Therefor - Google Patents

Abstract

Photographic dye images which have a density of at least 1.0 at 800 nm and are thus useful for forming infrared absorbing sound tracks for use with S-1 photo cells are constituted by a dye which is represented by formula I: <IMAGE> wherein R<1> is the residue of an oxidized primary amino phenylene diamine colour developing agent and R<2> is a group of formula II: <IMAGE> wherein R<3> is an alkyl group having from 1 to 6 carbon atoms; and of which dye at least a portion is in microcrystalline form. Such dye images can be produced in photographic elements of the invention comprising a support and a layer unit which comprises a photographic silver halide emulsion and coupler/solvent particles dispersed in the emulsion layer or in an adjacent hydrophilic colloid layer, said coupler being represented by formula III: <IMAGE> wherein R is a coupling-off group preferably H and R<2> is a group of formula II defined above: and said coupler being present in a concentration sufficient to yield a dye density of at least 1 at 800 nm; and said solvent being an alkyl ester of phthalic acid in which each alkyl group has from 1 to 6 carbon atoms, preferably dibutyl phthalate, and the ratio by weight of said coupler to said solvent being from 5:1 to 1:2. The couplers of formula ill are novel.

Description

SPECIFICATION Photographic Infrared-absorbing Dye Images, Such as Sound Tracks, and Couplers Therefor This invention relates to photographic reproductions comprising infrared-absorbing dye images such as sound tracks and to photographic elements useful for making such reproductions, particularly such elements as are useful in forming integral dye sound tracks in motion picture films, and to couplers for forming such dye images.

In black-and-white motion picture projection films it is frequently desirable to provide an integral sound track. Both the photographic image and sound track images in such films are composed of silver.

The sound track, which can be of variable density or variable area, is read optically by a photocell which detects infrared radiation passing therethrough. The peak sensitivity of these photocells, generally referred to as "S-l photocells", is typically at about 800 nm plus or minus 50 nm. The wide variance in peak absorption is of little importance, since silver has a substantially uniform absorption in the infrared region of the spectrum.

In colour photography, instead of employing silver images, as in black-and-white photography, the oxidized developing agent which is generated an imagewise developing silver halide to silver is used to form a dye image. The formation of colour photographic images by imagewise reaction (coupling) of oxidized aromatic primary amine developing agents with colour-forming couplers to form dyes is well known. In these processes, the#subtractive process of colour formation is ordinarily used, and the image dyes customarily formed are cyan, magenta and yellow, the colours that are complementary to the primary colours, red, green and blue, respectively. The silver image which is formed by development is an unwanted by-product which is removed by bleaching.

In colour motion picture projection films it is conventional to employ a silver sound track. The requirement that silver be retained in the optical sound track of the motion picture film is distinctly disadvantageous because the developed silver must be removed from the picture area without disturbing the silver in the optical sound track. This has given rise to processing techniques which require the separate treatment of a portion of the film at least once during processing in order to obtain a silver sound track.

The desirability of employing dye sound tracks in colour motion picture projection films, particularly dye sound tracks compatible with projection equipment now in use designed for films having silver sound tracks, has been long recognized. Unfortunately, the subtractive dyes which form the picture image have their regions of maximum absorption in the range of from about 400 to 700 nm and are relatively transparent in the infrared region where the S-l photocells are most sensitive. In looking for dyes suitable for use in forming infrared absorbing sound tracks for colour motion picture projection films two principal obstacles have been encountered. First, the dyes of the prior art have for the most part lacked sufficient peak absorption in the required region of the spectrum.Second, the absorption peaks of these dyes have not been broad enough to accommodate the plus or minus 50 nm variation in peak sensitivity of 5-1 photocells. Infrared absorbing dyes which have been disclosed for use in forming integral dye sound tracks are described in U.S. Patents 2,266,452 and 2,373,821. More recent disclosures pertaining to maximum absorption peak densities, but which do not address the breadth of the absorption peak, are illustrated by Japanese Publication 59838, based on patent application 94265 and United Kingdom Patent 1,424,454.

Cyan dye-forming couplers containing fluorine substituents are known in the art. U.S. Patent 3,758,308 disclosures para-fluoro substituted phenolic couplers which can contain a perfluorinated phenyl substituent and U.S. Patent 3,998,642 discloses a difluoro substituted phenolic coupler. N Biphenylyl-1-hydroxy-2-naphthamide couplers useful in forming infrared absorbing sound tracks are disclosed by Ciurca, Research Disclosure, Vol. 134, June 1975, Item 13460.

We have now found that dye images can be obtained from certain couplers which have a density of at least 1.0 to 800 nm and are thus useful for forming infrared absorbing sound tracks for use with S-l photo cells.

According to the present invention there is provided a photographic reproduction comprising a dye image constituted by a dye which is represented by formula l:

wherein R1 is the residue of an oxidised primary amino phenylene diamine colour developing agent and R2 is a group of formula II:

wherein R3 is an alkyl group having from 1 to 6 carbon atoms; and of which dye at least a portion is in microcrystalline form, said dye image having a density v. wavelength curve showing a density of at least 1 at 800 nm.

The term "microcrystalline dye" refers to a dye which is present in a crystalline physical form but of which the dye crystals are too small to be seen with the unaided eye. Such crystals can sometimes be seen upon microscopic examination but in many instances the crystals are of submicroscopic sizes.

(Crystallinity, particularly submicroscopic microcrystallinity, can be ascertained by a number of known general analytical techniques as well as by some techniques which are peculiar to the photographic arts. In photography, microcrystalline dyes are commonly associated with shifts in hue as a function of concentration and by asymmetrical absorption peaks. Both hyposchromic and bathochromic shifts attributable to microcrystallinity have been observed in varied conventional dye structures. Microcrystalline dyes have, for example, found applications in photographic elements because of their sharp transition between high peak and low toe densities, as illustrated by S. J. Ciurca, Research Disclosure, Viol. 1 57, May 1977, Item 15730.Analytical techniques, such as X-ray diffraction and detection of birefringence, can also be employed to identify crystalline structure. Such analytical techniques are described by A. Weissberger and B. W. Rossiter, Techniques of Chemistry, Physical Methods of Chemistry, Vol. 1, p. 3A-D, Wiley, 1972).

The dye image in the photographic reproduction of the invention has a density v. wavelength curve which shows a density of at least 1 and broad absorption peak in the 800 nm region. Preferably the curve shows a density of at least.1 over the range 750 to 850 nm. Preferably the curve exhibits a density of at least 2 over the range 750 to 850 nm.

The present invention also provides a photographic element for use in making a photographic reproduction of the invention said element comprising a support and a layer unit which comprises a photographic silver halide emulsion and coupler/solvent particles dispersed in the emulsion layer or in an adjacent hydrophilic colloid layer, said coupler being represented by formula Ill:

wherein R is a coupling-off group and R2 is a group of formula II defined above: and said coupler being present in a concentration sufficient to yield a dye density of at least 1 at 800 nm, and said solvent being an alkyl ester of phthalic acid in which the alkyl group has from 1 to 6 carbon atoms and the ratio by weight of said coupler to said solvent being from 5:1 to 1:2.

Since each dye in the processed photographic element of the invention is a reaction product of a coupler and an oxidized colour developing agent in a coupler/solvent particle, it follows that the steric configuration of the coupler, the developing agent and the coupler solvent as well as their relative proportions all influence the crystallinity of the dye produced. The choice of the coupler is generally most important to making photographic elements which can form microcrystalline dyes.

The formation of mixed phases of microcrystalline and noncrystalline dyes is specifically contemplated and is in many instances preferred to permit the formation of broadened absorption peaks. It is believed that the broadening of the absorption peak is the product of two unresolved or fused absorption peaks-one attributable to the microcrystalline dye produced and the other attributable to the noncrystalline dye produced, Although at least a portion of the dye produced is microcrystalline, it should be noted that the couplers are not themselves crystalline, since crystallinity in couplers produces significant loss of dye density attributable to lack of availabity of the coupler as well as severe problems in dispersing and coating the crystalline coupler.

The coupler-coupler solvent combinations defined above can produce infrared absorbing dye images having sufficient peak densities and spectral peak breadth to be useful in modulating the response of an S-l photocell when coated in a photographic element to form a sound track. The present invention offers the specific advantage of permitting colour motion picture projection films to be formed with integral infrared absorbing dye sound tracks, thereby eliminating the disadvantages in processing of selectively retaining silver in sound track areas and offering the distinct advantage of allowing such integral infrared-absorbing dye sound track colour motion picture films to be employed in projection equipment having 5-1 and similar photocells intended for modulation with a silver sound track.

As regards couplers used in the photographic elements of the invention, the coupling-off groups, represented by R in Formula III, are well known to those skilled in the art. Such groups are displaced when the coupler reacts with oxidized colour developing agent. Thus, the coupling-off group is not included in the dye formed by this reaction. The coupling-off group can perform useful photographic functions, such as determining the equivalency of the coupler (e.g., determining if the coupler is a twoequivalent or a four-equivalent coupler), modifying the reactivity of the coupler or releasing a photographically useful fragment which can modulate other characteristics, such as inhibiting or accelerating bleaching, inhibiting development, or colour correction.Representative of useful conventional coupling-off groups are H, alkoxy, aryloxy, arylazo, thioether and heterocyclic groups, such as oxazoyl, diazolyl, triazolyl, and tetrazolyl groups. H is a preferred coupling-off group.

R1 in the above coupler formula Ill can be a lower alkyl grnup-i.e., any alkyl group having from 1 to 6 carbon atoms, such as methyl, ethyl, or any one of the various isomeric forms of propyl, butyl, amyl and hexyl groups. R1 can in each occurrence be independently selected, but in a preferred form R1 is the same alkyl group in each occurrence.

The couplers can be chemically synthesized by techniques well known to those skilled in the art.

For example, the synthesis of N-(2,4-di-t-amylphenoxybu#l)-5,6,7,8-tetrafiuorn# 1 -hydroxy-2- naphtamide set forth below can be adapted to the synthesis of other couplers used in the invention by employing variation, such as the substituents in the starting materials which provide the coupling-off groups.

The coupler solvents which are used in combination with the above couplers are lower alkyl esters of phthalic acid, the lower alkyl group having 1 to 6 carbon atoms such as methyl, ethyl, or any of the various isomeric forms of propyl, butyl, amyl or hexyl groups. The alkyl ester of phthalic acid can be the half ester of phthalic acid or, preferably, the diester.

The following are preferred coupler solvents: dimethyl phthalate, diethyl phthalate, di-n-butyl phthalate, di-i-amyl phthalate and n-amyl phthalate.

Coupler to coupler solvent weight ratios of from 5:1 to 1:2 are used in the photographic elements of the invention. A preferred range of weight ratios is from 4:1 to 1 :1, with the optimum being from 2.5:1 to 1.5:1 for the preferred coupler solvents.

The coupler solvents used in the photographic elements of the invention and techniques for dissolving couplers therein are known to those skilled in the art.

Techniques are well known for dispersing coupler-containing coupler solvents in hydrophilic colloid-containing coating compositions useful in forming photographic elements. The couplercontaining coupler solvent is typically dispersed in the hydrophilic colloid-containing coating composition in the form of particles of relatively.smajl size, typically from 0.3 to 3.0 microns in mean diameter, usually by colloid milling. The coupler solvents herein employed, the dispersion of couplers therein, the introduction of the coupler-containing coupler solvents into hydrophilic colloid-containing coating compositions and the coating of the composition to form layers in photographic elements, are illustrated in U.S. Patents 2,304,940,2,322,027, 2,801,170,2,801,171, 2,835,579,2,949,360, as well as in Japanese Publication 59838 and U.K.Patent 1,424,454.

In a simple form the photographic element of this invention comprises a photographic support having coated thereon a single layer unit which comprises a photographic silver halide emulsion containing therein in a photographically useful amount particles of the coupler and coupler solvent combined in the weight ratio described above. In a variation, instead of incorporating the couplercontaining coupler/solvent particles directly in the silver halide emulsion layer, the particles can be dispersed in a hydrophilic colloid layer immediately adjacent to the silver halide emulsion layer. In this form the hydrophilic colloid layer containing the particles and the silver halide emulsion layer together form the layer unit.

Such a single layer unit element can be employed for the sole purpose of forming a sound track or, preferably, the element can be employed to form both a photographic image and a sound track. It is possible with such an element to form an infrared absorbing dye sound track and a silver photographic image or, alternatively, a silver sound track and an infrared absorbing photographic dye image. In a specifically preferred use an integral dye sound track is formed. As employed herein, the term "integral sound track" indicates that a sound track and a photographic image are formed in separate portions of the same element and that following exposure the separate areas are concurrently and identically processed (i.e., requiring no process steps other than those required for processing the photographic image portion) to form sound track and photographic records, respectively.Since the couplers employed in the practice of this invention produce dyes which absorb not only in the infrared but also in the visible portion of the spectrum, both a sound track and a photographic image can be formed solely by the dye. For example, an integral sound track and photographic image can be formed by the dye, the sound track portion being read by an S-l or similar infrared responsive photocell and the photographic image being read by the eye as a projected dye image.

In a form capable of recording multicolour images the photographic element contains in addition to the support and the single layer unit described above at least two additional layer units, and the photographic element is capable of producing multicolour photographic images. The single layer unit described above can contain a red-sensitized silver hatide emulsion and be employed to form a cyan dye image as well as an infrared absorbing dye image. The same dye can form both the cyan and the infrared absorbing dye image but it is preferred in that instance that the single layer unit described above be modified to include in addition a conventional cyan dye-forming coupler. The cyan dyeforming coupler is preferably dispersed in separate coupler solvent particles from those containing the infrared absorbing dye-forming coupler or coated without employing a coupler solvent.A second layer unit is present containing a blue-sensitive silver halide emulsion and a yellow dye-forming coupler, and a third layer unit is present containing a green-sensitized silver halide emulsion and a magenta dyeforming coupler. The construction of the second and third layer units and their relationship to the first layer unit is conventional and requires no detailed description.

In another form, which is specifically preferred, the photographic element is provided with four separate layer units. Three layer units are conventional cyan, magenta and yellow dye-forming layer units of the type found in conventional silver halide photographic elements intended to form multicolour dye images. The fourth layer unit can be identical to the single layer unit described above.

In a preferred form the silver halide emulsion in the fourth layer unit is sensitized to a portion of the spectrum to which the remaining layers are relatively insensitive. For example, the fourth layer unit emulsion can be spectrally sensitized to the infrared portion of the spectrum or to portions of the visible spectrum which lie at the fringes of the spectral regions the remaining layer units are intended to record. The blue portion of the spectrum is nominally defined as from 400 to 500 nm, the green portion of the spectrum from 500 to 600 nm and the red portion of the spectrum from 600 to 700 nm. The spectral regions in the vicinity of about 500 nm and 600 nm are frequently relatively insensitive to light as compared to the midregions of the blue, green and red portions of the spectrum.This is done intentionally to avoid recording in the layer unit light exposure from one of the two remaining thirds of the visible spectrum. By spectrally sensitizing the emulsion of the fourth layer unit to a peak sensitivity in a region of the spectrum where the silver halide emulsions of the other three layer units are relatively insensitive for instance at about 470 to 500 nm, the fourth layer unit can be exposed by light in this region of the spectrum to form a sound track. However in one preferred form the fourth layer unit is spectrally sensitized to the infrared portion of the spectrum.The fourth layer unit can be coated in any convenient order with respect to the remaining layer units, but it is preferable to coat the fourth layer unit nearer the exposure light source than the remaining layer units, typically to overcoat the other three layer units, so that the best possible definition of the sound track image will be produced. Useful layer arrangements are disclosed in Japanese Publication 59838 and U.K. Patent 1,424,454.

Still other variant forms of the photographic elements can be employed. For example, the emulsion of the sound track layer unit can be employed with only its native spectral sensitivity. In this instance the response of the sound track layer unit is confined to exposure to ultraviolet and the adjacent blue portion of the spectrum, the blue response varying to some extent with the silver halide chosen. In still another variant form the speed rather than the spectral response of the sound track recording layer unit can be different from that of another, image-forming layer unit. The sound track recording layer unit can be either faster or slower than an image-forming layer unit of similar spectral response. A combination of both differing spectral response and speed can also be employed to allow selective exposure of the sound track and image-forming layer units.

The photographically useful amount of particles of the infrared absorbing dye-forming coupler and coupler solvent present in the layer units described above is preferably sufficient to provide a maximum dye density of at least 1.0 over the spectral region of from 750 to 850 nm, preferably at least 2. Such dye densities can be obtained readily with the coupler-coupler solvent combination within the concentration ranges conventionally employed for coupler solvent particles containing cyan, magenta and yellow dye-forming couplers. Generally coupler concentrations ranging from 0.40 to 1.30 grams per square metre are used, preferably from 0.65 to 1.05 grams per square metre, optimally from 0.75 to 0.95 gram per square metre.

The photographic silver halide emulsion layers, the adjacent hydrophilic colloid-containing layers in which the infrared absorbing dye-forming couplers can be incorporated and other layers, including overcoat, subbing and interlayer coatings of conventional character, can contain various colloids alone or in combination as vehicles. Suitable hydrophilic vehicle materials include both naturally-occurring substances such as proteins, for example, gelatin, gelatin derivatives, cellulose derivatives, polysaccarides such as dextran and gum arabic and synthetic polymeric substances such as water soluble polyvinyl compounds like poly(vinylpyrrolidone) and acrylamide polymers.

Photographic emulsion layers and other layers of photographic elements such as overcoat layers, interlayers and subbing layers, as well as receiving layers in image transfer elements can also contain alone or in combination with hydrophilic, water-permeable colloids, other synthetic polymeric vehicle compounds such as dispersed vinyl compounds such as in latex form and particularly those which increase the dimensional stability of the photographic materials. Typically synthetic polymers include those described in U.S. Patents 3,142,568, 3,193,386, 3,062,674,3,220,844, 3,287,289 and 3,411,911. Other vehicle materials include those water-insoluble polymers of alkyl acrylates and methacrylates, acrylic acid, sulphoalkyl acrylates or methacrylates, those which have cross-linking sites which facilitate hardening or curing as described in U.S Patent 3,488,708 and those having recurring sulphobetaine units as described in Canadian Patent 774,054.

The vehicles and binders are typically coated from aqueous dispersions. The preferred hydrophilic colloids for coating purposes are gelatin and related derivatives. Gelatin and gelatin derivatives are typically coated in a concentrated of from 0.1 to 10 percent, preferably 2 to 6 percent, by weight, dry, based on total weight. The other hydrophilic colloids can be coated in similar concentration levels.

The silver halide photographic emulsions employed can be of any conventional, convenient form.

For example, the silver halide emulsion types set forth in Paragraph I, Product Licensing Index, Vol. 92, December 1971, Item 9232, can be employed. The emulsions can be washed as described in Paragraph II, chemically sensitized, as described in Paragraph Ill and/or spectrally sensitized, as described in Paragraph XV.The emulsion and other hydrophilic colloid-containing layers of the photographic elements can contain development modifiers, as described in Paragraph IV, antifoggants and stabilizers, as described in Paragraph V, developing agents, as described in Paragraph Vl, hardeners, as described in Paragraph VII, plasticizers and lubricants, as described in Paragraph Xl, coating aids, as described in Paragraph Xll, matting agents, as described in Paragraph Xlil, brighteners, as described in Paragraph XIV, and absorbing and filter dyes, as described in Paragraph XVI. The various addenda can be incorporated by known methods of addition, as described in Paragraph XVII.

The photographic elements can contain antistatic layers, as set forth in Paragraph IX. The colourforming materials, particularly the dye-forming couplers, can be chosen from those illustrated by Paragraph XXII. The dye-forming couplers which form the dye image to be viewed need not be coated in a coupler solvent, but can be coated in any conventional manner illustrated by the patents, in Paragraph XVIII. As these patents further illustrate, interlayers can be provided between adjacent layer units containing compounds such as ballasted hydroquinones to prevent migration out of the layer unit of oxidized developing agent. Coating of the various materials can be undertaken employing procedures such as those described in Paragraph XVIII. Product Licensing Index is published by Industrial Opportunities Ltd., Homewell, Havant Hampshire, P09 1 EF, UK.

The silver halide emulsion and remaining layers of the photographic elements can be coated on any conventional photographic support. For projection film applications including an integral sound track the support is specularly transmissive-e.g., transparent. For such applications conventional photographic film supports can be employed, such as cellulose nitrate film, cellulose acetate film, poly(vinyl acetal) film, polystyrene film, poly(ethylene terephthalate) film, polycarbonate film and similar resinous film supports.

In one preferred mode of exposure the photographic element of the invention is panchromatically exposed and an edge portion of the film is exposed to infrared radiation to form the sound track. When this mode of exposure is undertaken, the silver halide grains in the sound track recording layer unit are spectrally sensitized with infrared absorbing spectral sensitizing dyes. Typical useful infrared spectral sensitizing dyes are described, in U.S. Patents, 2,245,236, 2,095,854, 2,095,856, 2,084,436, 2,104,064, 2,199,542, 2,213,238, 2,734,900, 3,582,344, 2,134,546, 2,186,624, 2,073,759, 2,611 ,695, 2,955,939. 3,573,921, 3,552,974, 3,482,978, 3,623,881 and and 3,652,288.

The photographic elements can be processed to form dye images which correspond to or are reversals of the silver halide rendered selectively developable by imagewise exposure by conventional techniques. Multicolour reversal dye images can be formed in photographic elements having differentially spectrally sensitized silver halide layers by black-and-white development followed by a single colour development step, as illustrated by the KODAK 'Ektachrome' E4 and E6 and AGFA film processes described in British Journal ofPhotographyAnnual, 1977, pp. 194-197, and British Journal of Photography, pp. 668-669. The photographic elements can be adapted for direct colour reversal processing (i.e., production of reversal colour images without prior black-and-white development), as illustrated in U.S.Patents 3,243,294; 3,647,452; 3,457,077 and 3,467520 and German OLS's 1,257,570; 1,259,700; 1,259,701 and 2,005,091 and U.K. Patents 1,075,385 and 1,132,736.

Multicolour dye images which correspond to the silver halide rendered selectively developabie by imagewise exposure, typically negative dye images, can be produced by processing, as illustrated by the 'Kodacolor' C-22, the KODAK 'Flexicolor' C-41 and the AGFA colour processes described in British Journal of Photography Annual, 1977, pp.201-205. The photographic elements can also be processed by the KODAK 'Ektaprint'-3 and -300 processes as described in KODAK Color Dataguide, 5th Ed., 1975, pup.18~19, and the AGFA colour process as described in British Journal of PhotographyAnnual, 1977, pp. 205-206.

The photographic elements can be processed in the presence of reducible species, such as transition metal ion complexes (e.g. cobalt (III) and ruthenium (III) complexes containing amine and/or am mine ligands) and peroxy compounds (e.g. hydrogen peroxide and alkali metal perborates and percarbonates).

The dye images can be formed or amplified by processes which employ in combination with a dye-image-generating reducing agent an inert transition metal ion complex oxidizing agent, as illustrated by U.S. Patents 3,748,138, 3.826,652, 3,862,842, 3,989,526 and 3,765,891, and/or a peroxide oxidizing agent, as illustrated by U.S. Patent 3,674,490 Research Disclosure, Viol. 11 6, December 1 973, Item 11660, and Bissonette, Research Disclosure, Vol. 148, August 1976, Items 14836, 14846 and 14847. The photographic elements can be particularly adapted to form dye images by such processes, as illustrated by U.S. Patents 3,822,129; 3,834,907, 3.847.619; 3,902,905 and 3,904,413.

In a specific preferred application a photographic element of this invention is employed to form a motion picture film for projection containing an integral sound track useful in a projector having an S-l photocell. The photographic element is comprised of a transparent film support on which are coated, in the order recited, a red-sensitized, cyan dye-forming coupler containing first layer unit, a greensensitized, magenta dye-forming coupler containing a second layer unit, a blue-sensitive, yellow dyeforming coupler containing third layer unit and an infrared-sensitized fourth layer unit containing coupler solvent particles according to this invention, as has been described above. The picture recording portion of the element is flashed to infrared and is then exposed to the blue, green and red portions of the spectrum through a master image film.The master image film has a transparent support and has been processed so that it carries a positive multicolor dye image. The edge of the photographic element on which the integral sound track is to be formed is panchromatically exposed through a positive sound track master by a light source to which at least the fourth layer unit is sensitive. In a preferred form this is a white light source which exposes the red-sensitized, green-sentitized and bluesensitive layer units. The fourth layer unit by reason of its native sensitivity to blue light is also exposed by the white light source. The white light source can also emit infrared to expose the fourth layer unit.

The photographic element after exposure of both the picture and sound track areas is reversal processed. In reversal processing of negative-working silver halide emulsions, positive dye images are formed in unexposed areas. Since the picture area was uniformly flashed to infrared, no density attributable to the fourth layer unit is present in the picture area. In the sound track area the major portion of the infrared density is attributable to the fourth layer unit, but the other layer units can also add to the total infrared density.

In another specific application which further illustrates the diversity of uses contemplated, a motion picture projection film containing an integral sound track can also be obtained using a fourth layer unit which is spectrally sensitized to the region of 470 to 500 nm. The element can be exposed in picture recording areas through a multicolour negative master image film with red, green and blue (420 to 470 nm) light. The film sound track area can be exposed through a negative master sound track using a light source emitting in at least the 470 to 500 nm region of the spectrum. Using negative-working silver halide emulsion in the layer units, preferably in the order blue, red and greensensitive from the support, development produces in picture and sound track areas of the element positive dye images. The sound track image is formed primarily by the fourth layer unit.

In processing a photographic element of the invention to form a dye image of the invention described above any primary amino phenylene diamine colour developing agent can be employed which will lead to the formation of an infra-red absorbing dye image of the invention. Depending upon the specific colour developing agent selected, the maximum dye densities, the wavelength of the peak densities and the increased breadth of bathochromic absorption will vary within the invention. The colour developing agent 4-amino-3-methyl-N-,B-(methanesulphonamide)ethylaniline sulphate hydrate has been observed to produce microcrystalline infrared-absorbing dye images having a maximum density in excess of 1.0, often in excess in of 2.0, not only at 800 nm, but over the entire spectral region of from about 750 to 850 nm.Such microcrystalline infrared-absorbing dye images are ideally suited to forming dye sound tracks for use in motion picture projection film equipment employing S-l and similar photocells intended to respond to silver sound tracks. In the photographic elements of this invention can be produced infrared-absorbing dye sound tracks which are comparable in fidelity with the silver sound tracks they are intended to replace, although a somewhat higher gain may be required for comparable decibel output, since the dye sound track is of somewhat lower maximum density than are silver sound tracks.

The practice of this invention is further illustrated by the following Examples.

The Figure in the accompanying drawing referred to in Example 2 shows dye absorbtion curves produced by plotting density on an ordinate versus wave-length on an abscissa.

Example 1 A. A sample of N-(2,4-di-t-amylphenoxybutyl)-5,6,7,8-tetrafluoro-1 -hydroxy-2-naphthamide, hereinafter designated "Coupler 1", was prepared in the following manner: To 2.0 grams of phenyl 5,6,7,8-tetrafluoro-1 -hydroxy-2-naphthoate were added 2.0 grams 4-(di 2,4-t-amylphenoxy)butylamine. The mixture was heated at 1 300C for 1 hour with constant stirring.

Following cooling to room temperature 100 ml of n-hexane were added. The mixture was heated to dissolve the gummy solid and then cooled in an ice bath to give an off-white solid. Recrystallization from fresh n-hexane gave 1.2 grams of a white product, m.p. 95 to 960C. Coupler 1 is of the following structure:

B. A sample of N-(2-tetradecylphenyl)-5,6,7,8-tetrafluoro-1 -hydroxy-2-naphthamide. hereinafter designated Control Coupler 1 was prepared for purposes of comparison with- Coupler 1. It is to be noted that Coupler 1 and Control Coupler 1 have the same molecular weight, Control Coupler 1 is of the following structure: Example 2

A. A photographic element having a transparent film support and a gelatino-silver halide emulsion layer was prepared.The emulsion coating contained the ingredients set forth below in Table I.

Unless otherwise stated, all coating coverages in the examples are reported parenthetically in terms of grams per square metre. Silver halide coverages are reported in terms of silver.

Table I Photographic Element 2-A Gelatino-Silver Halide Emulsion Layer: Silver Bromoiodide (1.47); Gelatin (4.86); Coupler 1 (0.93); Coupler Solvent Di-n-butyl phthalate (0.46) Transparent Film Support The coupler was dispersed in the coupler solvent which was in turn dispersed in particulate form in the gelatin of the silver halide emulsion.

B. A sample of the photographic element was exposed for 1/50 second at a colour temperature of 3000 OK with an Eastman 1 B sensitometer through a graduated density step object. The test object had 21 equal density steps ranging from 0 density at Step 1 to a density of 3.0 at Step 21.

C. The exposed sample of the photographic element was then processed at 200C in the following manner: The sample was developed for 10 minutes in the color developer set forth in Table II.

Table II Colour Developer Water 800 ml Benzyl alcohol 4.0 ml Sodium hexametaphosphate 0.5 g Sodium sulphite 2.0g 40% Sodium hydroxide solution 0.4 ml 4-Amino-3-methyl-N-ethyl-N-p(methanesulphonamido)ethylaniline sulphate hydrate 5.0g Sodium carbonate 50.0 g 50% Sodium bromide solution 1.72 ml Water to 1 litre, pH 10.75 The sample was then immersed in a stop-fix bath for 5 minutes. The composition of the stop-fix bath is set forth in Table Ill.

Table Ill Stop-Fix Bath Water 800 ml Sodium thiosulphate 240 g Sodium suiphite 15g 28% Acetic acid solution 48 ml Boric acid 7.5 g Potassium Alum 15.0 g Water to 1 litre, pH 4.25 The sample was washed for 5 minutes in water and then immersed for 5 minutes in a bleach bath of the composition set forth in Table IV.

Table IV Bleach Bath Water 800 ml Sodium bromide 21.5g Potassium ferricyanide 100.0g NaH2PO4.H2O 0.07 g Water to 1 litre, pH 7.0 The sample was again washed for 5 minutes in water, again immersed for 5 minutes in the stopfix bath of Table III, again washed for 5 minutes in water and allowed to dry.

D. In Figure 1 a plot of density versus wavelength is shown. The reference numerals applied to the curves refer to the step number (.1 5 density steps) of the step tablet through which that portion of the sample was exposed. It can be seen where low maximum dye densities were produced the absorption peak produced by the dye was in the vicinity of about 700 to 725 nm. In Curve 1 5 and in the lower numbered curves broadening of the absorption peak and shifting the peak to well above 800 nm is in evidence. In Curves 13, 11 and 9 the absorption peak extends over the entire spectral region about 700 nm to above 850 nm. In Curve 9 the second absorption peak above 800 nm has clearly become predominant.

E. When a procedure generally similar to that described above was repeated substituting Control Coupler 1 for Coupler 1 a maximum dye density was obtained as illustrated by Curve C1 in Figure 1. It can be seen that the dye had a maximum density in the range of less than 700 nm. There is no evidence of spreading of the absorption peak, and the density of the dye in the region of 800 nm is relatively low.

The Curve C1 is the curve for the step which produced the highest peak density. The other steps produced progressively lower dye densities. In each instance the peak dye density observed for a given step in an element containing Control Coupler 1 was lower than that for the corresponding step employing Coupler 1.

F. When another colour developer was employed containing 4-amino-3-methyl-N,Ndiethylaniline hydrochloride as the developing agent, a higher peak dye density was obtained with Control Coupler 1, but the absorption peak remained at less than 700 nm and showed no evidence of broadening. The absorption of the dye produced with Control Coupler 1 and this developing agent was relatively low at 800 nm. With this developing agent Coupler 1 produced a dye image, the peak absorption being at about 720 nm. No broadening of the absorption curve was in evidence, and the absorption was relatively low in the region of from 800 to 860 nm.

Claims (33)

Claims

1. A photographic reproduction comprising a dye image constituted by a dye which is represented by formula l:

wherein R' is the residue of an oxidized primary amino phenylene diamine colour developing agent and R2 is a group of formula II:

wherein R3 is an alkyl group having from 1 to 6 carbon atoms; and of which dye at least a portion is in microcrystalline form, said dye image having a density v. wavelength curve showing a density of at least 1 at 800 nm.

2. A reproduction according to Claim 1 wherein said curve shows a density of at least 1 over the range 700 to 850 nm.

3. A reproduction according to Claim 1 wherein said curve shows a density of at least 2 over the range 750 to 850 nm.

4. A reproduction according to Claim 1 wherein only some of said dye is in microcrystalline form.

5. A reproduction according to any of Claims 1 to 4 which is a sound track.

6. A motion picture film having a sound track as defined in Claim 5.

7. A photographic element comprising a support and a layer unit which comprises a photographic silver halide emulsion and coupler/solvent particles dispersed in the emulsion layer or in an adjacent hydrophilic colloid layer; said coupler being represented by formula Ill:

wherein R is a coupling-off group and R2 is a group of formula 11 defined in Claim 1: and said coupler being present in a concentration sufficient to yield a dye density of at least 1 at 800 nm, and said solvent being an alkyl ester of phthalic acid in which the alkyl group has from 1 to 6 carbon atoms and the ratio by weight of said coupler to said solvent being from 5:1 to 1 :2.

8. A photographic element according to claim 7 wherein, in said formula Ill (of the coupler), R=H.

9. A photographic element according to claim 7 or 8 wherein, in said formula Ill (of the coupler) the R3 groups in the R2 group are the same.

10. A photographic element according to claim 9 wherein each R3 group is amyl.

11. A photographic element according to claim 7 in'which said coupler is N-(2,4-di-t amylphenoxybutyl)-5,6,7,8-tetrafluoro- 1 -hydroxy-2-naphthamide.

12. A photographic element according to any of claims 7 to 11 which contains from 0.4 to 1.30 grams of said coupler per square metre.

13. A photographic element according to any of claims 7 to 12 wherein said solvent is a diester of phthalic acid.

14. A photographic element according to claim 13 wherein said solvent is di-n-butyl, phthalate.

15. A photographic element according to any of Claims 7 to 14 wherein the weight ration of said coupler to said solvent is from 4:1 to 1:1.

16. A photographic element according to Claim 15, said ratio being from 2.5:1 to 1.5:1.

17. A photographic element according to any of Claims 7 to 16 wherein said silver halide emulsion is sensitized to the infrared portion of the spectrum.

18. A photographic element according to any of Claims 7 to 16 wherein said silver halide emulsion is sensitized in the region of the spectrum from 470 to 500 nm.

19. A photograhpic element according to any of Claims 7 to 18 wherein said element includes three layer units, one spectrally responsive to the blue region of the spectrum and containing a yellow dye-forming coupler, one spectrally responsive to the green region of the spectrum and containing a magenta dye-forming coupler and one spectrally responsive to the red region of the spectrum and containing a cyan dye-forming coupler.

20. A photographic element according to Claim 19 which comprises a support, said three layer units coated on the support in the order blue-sensitive, red-sensitive and green-sensitive and a fourth layer unit over said three layer units which fourth layer is a unit containing a silver halide emulsion layer as defined in Claim 18.

21. A photographic element according to Claim 1 9 which comprises a support, said three layer units coated on the support in the order red-sensitive, green-sensitive and blue-sensitive and a fourth layer unit over said three layer units which fourth layer unit is a unit containing a silver halide emulsion as defined in Claim 17.

22. A photographic element according to claim 1 adapted to form an integral infrared absorbing dye sound track comprising a transparent film support and a a layer unit coated on said film support comprising a gelatino-silver halide emulsion layer containing coupler solvent particles comprised of N-(2,4-diamylphenoxybutyl)-5,6,7,8-tetrafiuoro- 1 -hydroxy-2-naphthamide infrared absorbing dye-forming coupler and a dibutyl phthalate coupler solvent, said coupler and said coupler solvent being present in a weight ratio of from 4:1 to 1:1.

23. A photographic element according to any of Claims 19 to 22 which is a motion picture film.

24. A photographic element substantially in accordance with Example 2-A herein.

25. A process for producing a reproduction as defined in any of Claims 1 to 5 in which a photographic element as defined in any of Claims 7 to 24 is imagewise exposed and developed and in which said infrared absorbing dye is produced by use of a primary amino phenyiene diamine colour developing agent.

26. A process according to Claim 25 in which said development is 4-amino-3-methyl-N-ethyl-N- ,B)methane sulphonamido)ethyl aniline sulphate.

27. A process according to Claim 26 substantially as described in Example 2 herein.

28. A coupler as defined in Claim 7, 8, 9 or 10.

29. A coupler as defined in Claim 11.

30. A composition comprising a hydrophilic colloid and coupler/solvent particles as defined in any of Claims 7 to 16.

31. A composition according to Claim 30 which is a silver halide emulsion.

32. A composition according to Claim 31 in which said silver halide is sensitized to the infrared region of the spectrum.

33. A composition according to Claim 31 in which said silver halide is spectrally sensitized to have a peak sensitivity within the 470 to 500 nm region of the spectrum.